JP4040164B2 - Negatively chargeable toner and image forming method - Google Patents

Description

【００１８】
なお従来、１．００μｍ未満の粒径を測定可能な装置はいくつか存在したが、１．００μｍ未満の領域はノイズが大きく影響し、データの再現性に問題があった。上記装置は円相当径１．００μｍ未満の領域でも再現性が良く、また実際に粒子画像としての情報が同時に得られるため、粒子の確認をすることもできる。
【００１９】
本発明におけるトナー粒子は円相当径による粒度分布において、０．６０μｍ以上１．００μｍ未満の占める割合が個数基準で５．０％未満であり、個数平均円相当径が４．０〜１０．０μｍである場合に、問題を解決できる。
【００２０】
トナー粒子の円相当径による粒度分布において、０．６０μｍ以上１．００μｍ未満の占める割合が個数基準で５．０％以上である場合、トナー粒子１個における外添剤量が少なくなり、転写前のトナーの帯電量を十分に高めることができずネガスリーブゴースト抑制が悪化する。また、個数平均円相当径が４．０μｍ未満の場合、クリーニング不良が発生し、個数平均円相当径が１０．０μｍを超える場合は、トナーが感光体に付着するいわゆるフィルミングが発生してしまう。
【００２１】
該トナー粒子の３．００μｍ以上の粒子において、円形度ａが０．９０以上の粒子を個数基準で９０％以上有し、且つ、円形度ａが０．９８以上の粒子が３０％未満であることが好ましい。
【００２２】
該トナー粒子の円相当径３．００μｍ以上の粒子において、円形度ａが０．９０以上の粒子を個数基準で９０％未満の場合、トナーの感光体に対する付着力が増し、転写性が悪化する。また、円形度ａが０．９８以上の粒子が３０％以上ある場合には、クリーニング不良が発生する。
【００２３】
本発明における円形度ａとは、粒子の形状を定量的に表現する簡便な方法として用いたものであり、例えば東亜医用電子製フロー式粒子像分析装置 ＦＰＩＡ−１０００を用いて、下式より得られた値を円形度と定義する。
【００２４】
円形度ａ＝Ｌ₀／Ｌ
（Ｌ₀；粒子像と同じ投影面積をもつ円の周囲長、Ｌ；粒子像の周囲長）
【００２５】
本発明におけるトナー粒子の円形度分布は、上記粒子像分析装置を用いて、前記した円相当径の測定と同様の方法で、上記式により算出した。
【００２６】
本発明で使用する樹脂微粒子は、形状係数ＳＦ−１が１００以上乃至１５０未満（より好ましくはＳＦ−１が１１５以上乃至１４５未満）、形状係数ＳＦ−２が１１０以上乃至２００未満（より好ましくはＳＦ−２が１２０以上乃至１７５未満）であることが好ましい。
【００２７】
樹脂微粒子含有の効果を発揮するためには、樹脂微粒子の粒径を規定した上で両者の球形度（ＳＦ−１）、凹凸度（ＳＦ−２）を規定することが重要であることを、本発明者らは鋭意検討の結果発見した。
【００２８】
形状係数ＳＦ−１が１５０以上あるいは形状係数ＳＦ−２が２００以上である場合、トナー粒子と樹脂微粒子の接触面積が極端に減り、転写前のトナーの帯電量を十分に上げることができず、ネガスリーブゴースト抑制が悪化する。また、ＳＦ−２が１００以上乃至１１０未満である場合、クリーニング不良が発生する。
【００２９】
形状係数ＳＦ−１，ＳＦ−２は日立製作所ＦＥ−ＳＥＭ（Ｓ−８００）を用い、外添剤の本発明の平均粒径の範囲内の粒子を３００００〜６００００倍に拡大した像を１０個無作為にサンプリングし、その画像情報はインターフェースを介して、ニコレ社製画像解析装置（Ｌｕｚｅｘ３）に導入し、解析を行い下式より算出する。
【００３０】
【数１】

（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。）
【００３１】
本発明のトナーは、樹脂微粒子の平均粒径が０．０５〜２．０μｍ、好ましくは０．１〜１．０μｍの微粒子をトナー母粒子に外添することで、さらにネガスリーブゴーストを抑制することができる。樹脂微粒子の平均粒径が０．０５μｍ未満では、微粒子のトナー表面への付着力が大きすぎ、現像時・転写時にトナー母体からの分離が十分に起こらず、転写前のトナーの帯電量を高めることができないために、ネガスリーブゴースト抑制が悪化する。樹脂微粒子の平均粒径が２．０μｍを超えると、樹脂微粒子の表面積が小さく転写前のトナーの帯電量を高める効果が小さく、ネガスリーブゴースト抑制が悪化する。また、樹脂微粒子を核にしてトナー粒子の凝集が起こり、カブリの増加を招く場合もある。
【００３２】
また、樹脂微粒子のトナー中の含有量が０．０１〜０．５重量％であることが好ましい。微粒子のトナーへの含有量が０．０１重量％未満であると、転写前のトナーの帯電量を高める効果が不十分であり、ネガスリーブゴーストを十分に防ぐことができない。微粒子のトナーへの含有量が０．５重量％を超えると、カブリが発生しやすくなる。
【００３３】
好ましくは、上記樹脂微粒子が正帯電性を有することを特徴とする負帯電性トナーを用いる。上記樹脂微粒子が正帯電性を有する場合、特に転写前のトナーの帯電量を高めることができ、ネガスリーブゴースト抑制の効果がより高まる。
【００３４】
（樹脂微粒子の帯電極性の測定）
試料として測定する樹脂微粒子２重量部及び鉄粉９８重量部をターブラミキサーで６０秒間混合する。この混合物を図７に示す装置において、混合物を底部に５００メッシュの導電性スクリーン８３を装着した金属製の容器８２に入れる。そしてそのときのコンデンサ８８の電位を零とする。そして吸引口８７を経て吸引機８１で吸引し、容器８２に接続されたコンデンサ８８に蓄積された電圧極性から帯電極性を判断する。即ち５００メッシュ上には鉄粉が残り、試料は５００メッシュを通過するため、例えば正極性の試料を用いた場合にはコンデンサ８３には負極性の電圧が残ることになる。
【００３５】
図７において、８４は蓋を示し、８５は真空計を示し、８９は電位計を示す。吸引の際、吸引圧を２５０ｍｍＨ₂Ｏとする。鉄粉としては、例えばＥＦＶ ２００／３００（パウダーテック社製）を用いる。
【００３６】
樹脂微粒子を構成する樹脂としては、メラミン系樹脂、さらに重合性単量体として、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、ｐ−メトキシスチレン、ｐ−エチルスチレンの如きスチレン系単量体；アクリル酸単量体；メタクリル酸単量体；アクリル酸メチル、アクリル酸エチル、アクリル酸ｎ−ブチル、アクリル酸イソブチル、アクリル酸ｎ−プロピル、アクリル酸ｎ−オクチル、アクリル酸ドデシル、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２−クロルエチル、アクリル酸フェニルの如きアクリル酸エステル単量体；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−プロピル、メタクリル酸ｎ−ブチル、メタクリル酸イソブチル、メタクリル酸ｎ−オクチル、メタクリル酸ドデシル、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、メタクリル酸フェニル、メタクリル酸ジメチルアミノエチル、メタクリル酸ジエチルアミノエチルの如きメタクリル酸エステル単量体；その他のアクリロニトリル、メタクリロニトリル、アクリルアミドの如き単量体が挙げられる。特に、メラミン系樹脂を用いるのが好ましい。
【００３７】
重合方法としては、懸濁重合、乳化重合、ソープフリー重合等が使用可能であるが、より好ましくはソープフリー重合によって得られる粒子が良い。
【００３８】
さらに上記樹脂微粒子が所望のＳＦ−１，ＳＦ−２の値を得る手段としては、得られた樹脂微粒子に機械的衝撃力を加えるなどの方法が考えられる。
【００３９】
特に、上記特徴を有する樹脂微粒子は、一次帯電装置としてローラ、ブラシあるいは、ブレードの如き接触帯電系において、感光体ドラムの融着抑制に多大な効果をもたらすことが確認されている。
【００４０】
本発明のトナーに用いられる無機微粉末の外添剤としては、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、チタニアの如き無機微粉体、あるいはその複酸化物が好ましい。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合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、また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，ＳＯ₃ ^2-等の製造残滓の少ない乾式シリカの方が好ましい。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。
【００４１】
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粒子１００重量部に対してシリカ微粉末０．１〜８重量部、好ましくは０．５〜５重量部、さらに好ましくは１．０を超えて３．０重量部まで使用するのが特に良い。
【００４２】
本発明に用いられる無機微粉末は、必要に応じ疎水化、帯電性制御の目的で、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、有機チタン化合物の如き処理剤を単独で、あるいは、複数を併用して処理されていることが好ましい。
【００４３】
比表面積はＢＥＴ法に従って、比表面積測定装置オートソーブ１（湯浅アイオニクス社製）を用いて試料表面に窒素ガスを吸着させ、ＢＥＴ多点法を用いて比表面積を算出した。
【００４４】
安定したトナーの保存性を維持するためには、無機微粉体は少なくともシリコーンオイルで処理されることが好ましい。
【００４５】
本発明のトナー粒子に使用される結着樹脂の種類としては、例えば、ポリエチレン、ポリ−ｐ−クロルスチレン、ポリビニルトルエンの如き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−インデン共重合体の如き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；石油系樹脂が使用できる。架橋されたスチレン系樹脂も好ましい結着樹脂である。
【００４６】
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、ビニル系単量体が単独、又は複数を組合わせて用いることができる。ビニル系単量体としては例えば、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、アクリルアミドの如き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の如き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、安息香酸ビニルの如きビニルエステル類；例えば、エチレン、プロピレン、ブチレンの如き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の如きビニルケトン類；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の如きビニルエーテル類が挙げられる。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、単独、又は複数を組合わせて用いることができる。このような化合物としては、例えば、ジビニルベンゼン、ジビニルナフタレンの如き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の如き二重結合を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、ジビニルスルホンの如きジビニル化合物；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。
【００４７】
本発明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。
【００４８】
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。
【００４９】
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。
【００５０】
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が特に好適に利用できる。
【００５１】
これらの着色剤は、単独または混合し、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重量部に対し１〜２０重量部添加して用いられる。
【００５２】
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重量部に対し３０〜２００重量部添加して用いられる。
【００５３】
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、アルミニウム又は硅素の元素を含む金属酸化物がある。中でも四三酸化鉄、γ−酸化鉄など、酸化鉄を主成分とするものが好ましい。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の如き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であることが良く、更にモース硬度が５〜７であることが好ましい。
【００５４】
磁性体の形状としては、８面体，６面体，球状，針状，鱗片状があるが、８面体，６面体，球体，不定形型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。
【００５５】
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。
【００５６】
磁性体量は結着樹脂１００重量部に対し３０〜２００重量部、好ましくは４０〜２００重量部、更には５０〜１５０重量部が好ましい。３０重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やすい傾向であった。一方、２００重量部を超えると定着性に問題が生ずる傾向であった。
【００５７】
本発明において、必要であればトナー粒子中にワックスを内添しても構わない。用いられるワックスとしては、ポリプロピレン、ポリエチレン、マイクロクリスタリンワックス、カルナバワックス、サゾールワックス、パラフィンワックス、高級アルコール系ワックス、エステルワックスなど及びこれらの酸化物やグラフト変性物などが挙げられる。
【００５８】
これらの低分子量ワックスは、トナー製造時に予め結着樹脂中に添加、混合しても良い。添加量としては、結着樹脂１００重量部に対し約１〜２０重量部が好ましい。
【００５９】
本発明のトナーには、必要に応じて荷電制御剤をトナー粒子に配合（内添）、またはトナー粒子と混合（外添）して用いることもできる。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になり、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事が可能である。
【００６０】
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。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、芳香族モノカルボン酸、芳香族ポリカルボン酸及びそれらの金属塩、それらの無水物、それらのエステル類、ビスフェノールの如きフェノール誘導体類がある。
【００６１】
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、好ましくは３μｍ以下、より好ましくは０．５乃至３μｍであることが良い。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重量部に対して０．１〜２０重量部、特に、０．２〜１０重量部使用することが好ましい。
【００６２】
上記の樹脂微粒子及び荷電制御剤の平均粒径は、以下の方法で測定した値である。
【００６３】
電子顕微鏡Ｓ−８００（日立製作所社製）を用いて、樹脂微粒子は１００００乃至２００００倍、荷電制御剤は１０００乃至５０００倍の倍率で写真撮影を行い、撮影された微粒子から、樹脂微粒子は０．０１μｍ以上の粒子について、荷電制御剤は０．０５μｍ以上の粒子について、ランダムに１００乃至２００個を抽出し、ノギス等の測定機器を用いてそれぞれの直径を測定し、平均化したものを各微粒子の平均粒径とした。
【００６４】
一般的にトナーを作製するには、例えば、結着樹脂、着色剤としての顔料、染料、または磁性体、必要に応じてワックス、金属塩ないしは金属錯体、荷電制御剤その他の添加剤をヘンシェルミキサー、ボールミルの如き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着色剤、必要に応じて金属化合物、顔料、染料を分散または溶解せしめ、冷却固化、粉砕後、必要に応じて分級及び表面処理を行ってトナー粒子を得、さらに樹脂微粒子及び無機微粉体等を添加混合して製造する方法が好ましく用いられる。
【００６５】
本発明のトナーに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の如き機械衝撃式粉砕機を用いる方法、または、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。具体的に、本発明のトナーを得るためには、例えば図４に示す機械衝撃式粉砕機であるターボ工業社製のターボミルを用い、３５℃以上の雰囲気下で、ブレード１２１の周速が６０ｍ／秒から１５０ｍ／秒程度の範囲でローター１１４を回転させて、トナーを微粉砕しながら円形度分布と粒度分布を整える方法、あるいはそれに加えて、機械的衝撃力による表面処理を行う方法などが好ましい。
【００６６】
機械的衝撃力を加える場合は、トナーの微粉砕工程の後、あるいは、さらに分級工程を経た後に行う場合、ネガスリーブゴースト抑制を高める上で特に好ましい。
【００６７】
図４に示す機械衝撃式粉砕機の構成としては、図４の断面図に示されているような水平方向の円盤上に４枚の処理ブレード１２１が水平に取り付けられた垂直方向に回転するローター１１４が、水平方向に延びる回転軸１１５に沿って４段配置されている処理室１を有する機械的衝撃力を与える方式の表面改質装置Ｉを用いた。表面処理の具体的な方法としては、駆動モーター４の可動により、夫々のローター１１４を周速４０ｍ／ｓで回転させ、図３に示すように、表面改質装置Ｉの出口側にサイクロン２０及びブロアー２４を取り付け、ブロアー風量３．０ｍ²にて吸引した状態で、処理装置上部のトナー供給口から、トナー収納器４０中のトナーをオートフィーダー１５にて毎時２０ｋｇの速度で投入口１１１よりトナーを供給し、トナーの表面処理を行うものである。表面改質装置の処理室１に導入されたトナーは、回転する処理ブレード１２１と処理室１の内壁との微小空隙１１３を通過する際に衝撃力を受けて球形化処理が施される。
【００６８】
表面処理を施したトナーは、出口１０からサイクロン入口１９を通って、ロータリーバルブ２１で回収される。尚、トナーのバグ微粉は、バグフィルター２２を通って、ロータリーバルブ２３で回収される。
【００６９】
衝撃式表面処理装置では図２及び図３に示すように、駆動手段によって回転軸６１を駆動し、表面処理すべき物質の性質により粒子が解砕しない程度の周速で回転盤６２を回転させ、該回転盤の回転に伴って発生した急激な気流により、衝撃室６８に開口する循環路６３を巡って回転盤６２の中心部に戻る循環流れを起こす。
【００７０】
次に、一定量の被処理粉体を原料ホッパー６４から衝撃室６８に投入し、投入された該被処理粉体は高速回転する回転盤６２によって瞬間的な打撃を受け、さらに周辺の衝突リング５８に突入して衝撃作用を受けた後、該循環流れにより循環路６３を介して再び衝撃室６８へ戻り、再度打撃作用を受け表面処理が行われる。ブレード５５の周速は６０ｍ／秒から１５０ｍ／秒の範囲になるように回転盤を回転させることが好ましい。
【００７１】
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。
【００７２】
本発明の画像形成方法の好ましい一具体例を図１を参照しながら説明する。
【００７３】
一次帯電器としての帯電ローラーからなる接触帯電部材１６１で静電潜像保持体としてのＯＰＣ感光ドラム１５３表面を負極性に帯電し、レーザ光による露光１５５によりイメージスキャニングによりデジタルの静電潜像を形成し、カウンター方向に設置されたウレタンゴム製の弾性ブレード１５８および磁石１６５を内包している現像スリーブ（トナー担持体）１５６を具備する現像手段としての現像装置１５１の負摩擦帯電性磁性トナー１６３で該静電潜像を反転現像する。または、アモルファスシリコン感光体を使用し、アモルファスシリコン感光体を正極性に帯電し、静電潜像を形成し、負摩擦帯電性磁性トナーを用いて正規現像をおこなう。現像スリーブ１５６に、バイアス印加手段１６２により交互バイアス、パルスバイアス及び／又は直流バイアスが印加されている。記録材としての記録紙Ｐが搬送されて、転写部にくると転写手段としての転写ローラーからなる接触転写部材１５４により記録紙Ｐの背面（感光ドラム側と反対面）から帯電をすることにより、感光ドラム表面上のトナー画像が記録紙Ｐ上へ静電転写される。感光ドラム１５３から分離された記録紙Ｐは、内部に加熱手段１７０を有する定着ローラー１７１と定着ローラ１７１に圧接する加圧ローラー１７２とを有する加熱加圧定着装置の定着ローラー１７１と加圧ローラー１７２の圧接部を通過することにより記録紙Ｐ上のトナー画像を定着するために定着処理される。
【００７４】
転写工程後の感光ドラム１５３に残留するトナーは、クリーニングブレード１５７を有するクリーニング器１６４で除去される。クリーニング後の感光ドラム１５３は、イレース露光１６０により除電され、再度、一次帯電器１６１による帯電工程から始まる工程が繰り返される。
【００７５】
静電潜像保持体（感光ドラム）は感光層及び導電性基体を有し、矢印方向に動く。現像剤担持体である非磁性円筒の現像スリーブ１５６は、現像部において静電潜像保持体表面と同方向に進むように回転する。非磁性円筒の現像スリーブ１５６の内部には、磁界発生手段である多極永久磁石１６５（マグネットロール）が回転しないように配されている。現像装置１５１内のトナー１６３は非磁性円筒面上に塗布され、かつ現像スリーブ１５６の表面とトナー粒子との摩擦によって、トナー粒子はマイナスのトリボ電荷が与えられる。さらに弾性ドクターブレード１５８を配置することにより、現像剤層の厚さを薄く（３０μｍ〜３００μｍ）且つ均一に規制して、現像部における感光ドラム１５３と現像スリーブ１５６の間隙よりも薄いトナー層を非接触となるように形成する。このスリーブ１５６の回転速度を調整することにより、スリーブ表面速度が静電潜像保持体表面の速度と実質的に等速、もしくはそれに近い速度となるようにする。
【００７６】
現像スリーブ１５６に交流バイアスまたはパルスバイアスをバイアス手段１６２により印加しても良い。この交流バイアスはｆが２００〜４，０００Ｈｚ、Ｖｐｐが５００〜３，０００Ｖであることが好ましい。
【００７７】
現像部分におけるトナー粒子の転移に際し、静電潜像を保持する感光ドラム１５３の表面の静電的力及び交流バイアスまたはパルスバイアスの作用によってトナー粒子は静電潜像側に転移する。
【００７８】
前記現像スリーブ１５６は、任意の構造とし得る。通常は、磁石１６５を内蔵した非磁性の現像スリーブ１５６から構成される。現像スリーブ１５６は図示されるように円筒状の回転体とすることもできる。循環移動するベルト状とすることも可能である。その材質としては通常、アルミニウムやＳＵＳが用いられることが好ましい。
【００７９】
本発明に用いられる弾性ブレード１５８は、材質としてシリコーンを用いる。シリコーンの中でも材質として弾性を有するシリコーンゴムが特に好ましい。また、シリコーンの中に有機化合物、無機化合物を添加しても良く、溶融混合させても良いし、分散させても良い。例えば、金属酸化物、金属粉、セラミックス、炭素同素体、ウイスカー、無機繊維、染料、顔料、界面活性剤などがある。弾性ブレードを現像スリーブに当接させる方法としては、弾性を有するシリコーンゴムのブレードをそのまま当接させる方法の他に、金属などの他の弾性体シリコーンを現像スリーブに当接する部分に貼り合わせる方法でも良い。
【００８０】
本発明のトナーと、材質としてシリコーンを用いた上記弾性ブレードを組み合わせることで、さらにネガスリーブゴーストを改善する効果がある。弾性ブレードにシリコーンを用いることで、現像するトナーの帯電性が上がり、その結果転写前のトナーの帯電性が上がることが理由と考えられる。
【００８１】
本発明の画像形成方法をファクシミリのプリンターに適用する場合には、光像露光Ｌは受信データをプリントするための露光になる。図５はこの場合の一例をブロック図で示したものである。
【００８２】
コントローラ１８１は画像読取部１８０とプリンター１８９を制御する。コントローラ１８１の全体はＣＰＵ１８７により制御されている。画像読取部からの読取データは、送信回路１８３を通して相手局に送信される。相手局から受けたデータは受信回路１８２を通してプリンター１８９に送られる。画像メモリには所定の画像データが記憶される。プリンタコントローラ１８８はプリンター１８９を制御している。１８４は電話である。
【００８３】
回線１８５から受信された画像（回線を介して接続されたリモート端末からの画像情報）は、受信回路１８２で復調された後、ＣＰＵ１８７は画像情報の複号処理を行い順次画像メモリ１８６に格納される。そして、少なくとも１ページの画像がメモリ１８６に格納されると、そのページの画像記録を行う。ＣＰＵ１８７は、メモリ１８６より１ページの画像情報を読み出しプリンタコントローラ１８８に複合化された１ページの画像情報を送出する。プリンタコントローラ１８８は、ＣＰＵ１８７からの１ページの画像情報を受け取るとそのページの画像情報記録を行うべく、プリンタ１８９を制御する。
【００８４】
尚、ＣＰＵ１８７は、プリンタ１８９による記録中に、次のページの受信を行っている。
【００８５】
以上の様に、画像の受信と記録が行われる。
【００８６】
【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、これは本発明を何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重量部である。
【００８７】

【００８８】
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、気流分級機と衝突式気流粉砕機を有する粉砕手段で粗粉砕を微粉砕した。得られた微粉砕物を、粉体供給部に圧縮エアを用いた強制粉体分散装置を内蔵しているコアンダ効果を用いた多分割分級機にて、２．０ｋｇ／ｃｍ²の圧縮エアで強制的に分散させながら供給し、厳密に分級して、個数平均円相当径６．２μｍ、円相当径０．６０μｍ以上１．００μｍ未満の粒子の占める割合が個数基準で全体の３．７％の磁性トナー粒子を得た。
【００８９】
さらに、該磁性トナー粒子を、ローターを回転して機械的衝撃力を与える方式の表面改質装置を用いて表面処理した。得られたトナー粒子１の個数平均円相当径は６．４μｍ、円相当径０．６０μｍ以上１．００μｍ未満の粒子の占める割合が個数基準で全体の０．７％、円形度ａが０．９０以上の粒子は個数基準で９５．２％、円形度ａが０．９８以下の粒子は個数基準で２４．０％であった。
【００９０】
得られたトナー粒子１に、表２に示す樹脂微粒子ａを０．１％、シリコーンオイルとヘキサメチルジシラザン処理乾式シリカを１．２％添加し、混合機にて混合してトナー１を得た。
【００９１】
［画像評価］
現像装置として、以下のようなものを用いて評価した。
【００９２】
現像剤担持体として、引き抜き加工したままのアルミ円筒素管（外径：２０ｍｍ）のスリーブの表面に、カーボンブラックとグラファイトとアクリル樹脂粒子がフェノール樹脂１０部中に１：９：０．７５の割合で分散している樹脂被覆層をコートしたもの（平均表面粗さ１．３μｍ）を用いた。
【００９３】
また、この円筒スリーブの内部に、現像極の磁束密度が９０ｍＴの４極マグネットを内蔵させた。
【００９４】
現像剤規制部材としては、厚さ１．５５ｍｍのシリコーンゴムブレードを用い、現像剤担持体に２６．４Ｎの引き抜き圧で当接させた。
【００９５】
感光体としては、直径が６２ｍｍの有機感光体を用い、現像剤担持体と感光体との最近接距離を３００μｍに設定した。
【００９６】
一次帯電器としては、ローラー帯電器を用い、露光手段としてはレーザー光を用い、６００ｄｐｉで潜像を形成した。また、転写帯電器としては、ローラー帯電器を用いた。
【００９７】
転写工程で感光体上に残留した現像剤を除去するクリーニング装置としては、ブレードクリーニング装置を用い、クリーニングブレードとしてはウレタンブレードを用いた。
【００９８】
感光体上の潜像の電位は、暗部電位：−５００Ｖ、明部電位−１５０Ｖあるように設定した。
【００９９】
感光体は１１７ｍ／ｓで回転させた。現像剤担持体は１４０ｍ／ｓで回転させた。現像剤担持体には現像バイアスとして直流電圧：−５００Ｖ、交流電圧：１６００Ｖ（ピークトゥピーク）、交流周波数：２３００Ｈｚの矩形波を印加した。
【０１００】
［ネガスリーブゴーストの評価］
現像装置として上記現像装置を用い、図６に示すような、現像剤担持体１周分ブロック上のベタ黒画像があり、その下にハーフトーンの全面ベタが続く画像をプリントし、その際のネガスリーブゴーストの画像濃度差をもって評価した。具体的には、図６におけるＢの領域の画像濃度からＡの領域の画像濃度を差し引いた値である。その評価結果を表３に示す。なお、画像濃度はマクベス反射濃度計により測定した。
【０１０１】
トナーとしてはトナー１を用い、上記方法でネガスリーブゴーストを評価したところ、画像濃度差は０．０１であり、ネガスリーブゴースト抑制は非常に良好であった。
【０１０２】
また、更に５０００枚画出しし、ベタ黒画像の画像濃度と感光体上のカブリを測定した。感光体上のカブリは、ベタ白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剥ぎ取り、紙上に貼ったものの反射濃度からテープのみを貼ったものの反射濃度を差し引いた数値で評価した。なお、カブリは反射式濃度計（ＴＯＫＹＯ ＤＥＮＳＨＯＫＵ ＣＯ．，ＬＴＤ社製 ＲＥＦＬＥＣＴＯＭＥＴＥＲ ＯＤＥＬ ＴＣ−６ＤＳ）を用いて測定（プリン２３ト後の反射濃度最悪値Ｄｓからプリント前の反射濃度平均値Ｄｒを引いた値；Ｄｓ−Ｄｒ）した。
【０１０３】
（トナーの摩擦帯電量の測定）
トナーの摩擦帯電量は、吸引式ファラデーケージ法を用いて求める。
【０１０４】
吸引式ファラデーケージ法とは、トナー回収装置を用いて複写機又はプリンターの現像スリーブ上の一定面積における全てのトナーを吸引回収し、回収したトナーの重量及び電荷量を測定し、測定されたトナーの重量と電荷量から、トナーの単位重量当たりの電荷量、すなわち、摩擦帯電量（ｍＣ／ｋｇ）を求める方法である。
【０１０５】
この吸引式ファラデーケージ法で用いるトナー回収装置は、エアーと共にトナーを吸引するための吸引装置及びこの吸引装置に連結されたトナーを回収するための回収装置とを有している。回収装置は、現像スリーブ上のトナーを吸引するための現像スリーブの外周曲率に対応した曲率の先端部を持った吸引口を有する外筒と、吸引したトナーを回収するための円筒ろ紙を有する内筒とを有している。
【０１０６】
このトナー回収装置を用いて現像スリーブ上のトナーの吸引回収を具体的に行うには、現像スリーブの回転を停止し、上記の吸引装置を用いて、現像スリーブ上のトナーを、現像スリーブの一端側から他端側にかけて長手方向に沿って吸引装置の吸引口を現像スリーブ表面に押し付けながら吸引し、吸引したトナーを回収装置の円筒ろ紙で回収する。
【０１０７】
トナーを回収した円筒ろ紙の重量Ｗ₂（ｇ）を測り、この回収後の円筒ろ紙の重量から回収前の円筒ろ紙の重量Ｗ₁（ｇ）を引いた値を回収したトナーの重量Ｗ₂−Ｗ₁（ｇ）とする。このとき、回収装置にエレクトロメータ（ＫＥＩＴＨＫＥＹ社製 モデル６１７型）を接続して、外部から静電的にシールドされた内筒の円筒ろ紙に回収されたトナーの帯電量Ｅ（μＣ）を測定し、下記式に基づいてトナーの摩擦帯電量Ｑｍ（ｍＣ／ｋｇ）を求める。
Ｑｍ＝Ｅ／（Ｗ₂−Ｗ₁）
【０１０８】
＜実施例２〜４、比較例１＞
実施例１において添加する樹脂微粒子を、表２に示す樹脂微粒子ｂ〜ｅにする以外は、実施例１と同様にして表３に示すトナー２〜５を得た。
【０１０９】
＜実施例５〜８＞
実施例１において添加する樹脂微粒子ａの添加量を、表３に示す量にする以外は、実施例１と同様にして表３に示すトナー６〜９を得た。
【０１１０】
＜実施例９＞
機械的衝撃力による表面処理を行わない以外は、実施例１と同様にして表３に示すトナー１０を得た。製造過程で得られるトナー粒子２の物性を表１に示す。
【０１１２】
＜比較例２＞
実施例１の磁性体量を５０部にし、分級工程において、トナー供給時に圧縮エアで強制的な分散を行わず、機械的衝撃力による表面処理も行わない以外は、実施例１と同様にして表３に示すトナー１１を得た。製造過程で得られるトナー粒子３の物性を表１に示す。
【０１１４】
［評価］
上記実施例及び比較例のトナー２〜１１を実施例１と同様な方法で評価を行った。結果を表３に示す。
【０１１５】
＜比較例３＞
評価に用いる現像装置において、用いる樹脂微粒子として樹脂微粒子ｅ用い、現像剤規制部材としてウレタンゴム製の弾性ブレードを用いる以外は実施例１と同様に評価を行った。結果を表３に示す。
【０１１６】
【表１】

【０１１７】
【表２】

【０１１８】
【表３】

【０１１９】
【発明の効果】
本発明によれば、トナー粒子が特定の円形度分布及び特定の粒度分布を有していることから、耐久性に優れ、ネガスリーブゴーストを抑制することができる。
【０１２０】
特にトナーに含有される粒径及び形状の規定された樹脂微粒子により、ネガスリーブゴーストをさらに抑制することができる。
【図面の簡単な説明】
【図１】本発明の画像形成方法を実施し得る画像形成装置の概略構成図を示す。
【図２】処理装置システムの一例を示す図である。
【図３】図２における表面処理装置の概略断面図である。
【図４】機械式粉砕装置の一例を示す図である。
【図５】本発明の画像形成方法をファクシミリ装置のプリンターに適用するためのブロック図である。
【図６】スリーブゴーストの評価方法の説明図を示す。
【図７】樹脂微粒子の帯電極性を測定するための測定装置の概略説明図である。
【符号の説明】
１ 円筒形ケーシング
４ プーリー
１０ 排出口
１５ 振動フィーダー
１９ バルブ
２０ サイクロン
２１，２３，２６ バルブ
２２ バグフィルター
２４ ブロアー
２８ 排出弁制御装置
４０ 定量供給機
５９ 排出用開閉弁
６０ 排出口
６２ 回転盤
６３ 循環回路
６４ 原料ホッパー
６８ 衝撃室
７７ ジャケット
１１０ ライナー
１１１ 投入口
１１３ 処理領域
１１４ ローター
１１５ ローター軸
１２１ ブレード
１５１ 現像装置
１５３ 感光体ドラム
１５６ 現像スリーブ
１５８ 弾性ブレード
１６３ トナー
１７１ 定着ローラー
１７２ 加圧ローラー[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a negatively chargeable toner used in an image forming method using an electrophotographic method, an electrostatic recording method, a magnetic recording method, a toner jet method, and the like, and an image forming method using the toner. Specifically, the present invention relates to a negatively chargeable toner used in an image forming apparatus such as a copying machine, a printer, and a fax machine in which a toner image is previously formed on an electrostatic latent image carrier and then transferred onto a recording material to form an image. About.
[0002]
[Prior art]
Conventionally, a number of methods are known as electrophotographic methods. In general, a photoconductive substance is used to form an electrical latent image on a photoreceptor by various means, and then the latent image is formed with toner. Development is performed to obtain a visible image, and the toner image is transferred to a transfer material such as paper as necessary, and then the toner image is fixed on the transfer material by heat, pressure, or the like to obtain a copy.
[0003]
As a method for visualizing an electric latent image, a cascade development method, a magnetic brush development method, and a pressure development method are known. Furthermore, a method is also known 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]
In recent years, LED and LBP printers have become mainstream 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. In this direction, the method of forming an electrostatic charge image with a laser is the main method, so it is also progressing in the direction of high resolution, and here again, a high-resolution and high-definition development method is required as in the case of a printer. . For this reason, the toner particle size is being reduced, and Japanese Patent Application Laid-Open Nos. 1-112253 and 2-284158 propose a toner having a specific particle size distribution and a small particle size.
[0005]
As described above, the recent trend is toward high resolution, but on the other hand, there is an increasing demand for higher quality graphic images. One aspect of the quality of a graphic image is the uniformity of image density in a solid image.
[0006]
Regarding the uniformity of density in the solid image, in the one-component development method, when a solid image such as a halftone is printed, a reverse image of the image printed immediately before the solid image appears at a period of the toner carrier. There is a phenomenon called “negative sleeve ghost”, and there is a problem that the quality of the graphic image is lowered. In order to improve the quality of graphic images, suppression of negative sleeve ghosts is required.
[0007]
[Problems to be solved by the invention]
An object of the present invention is to provide a negatively chargeable toner that solves the above-mentioned problems of the prior art.
[0008]
That is, an object of the present invention is to provide a negatively chargeable toner capable of obtaining a high-quality graphic image without a “negative sleeve ghost” and an image forming method using the toner.
[0009]
[Means for Solving the Problems]
  The present invention is a negatively chargeable toner having at least toner particles, inorganic fine powder and resin fine particles,
  The toner particles have at least a binder resin and a colorant, and the proportion of particles having an equivalent circle diameter of 0.60 μm or more and less than 1.00 μm is based on the number in the particle size distribution by the equivalent circle diameter of the toner particles. Less than 5.0% of the total, and the number average equivalent circle diameter is 4.0 to 10.0 μm,
  In the toner particles having a circle-equivalent diameter of 3.00 μm or more, the ratio of the particles having a circularity a of 0.90 or more obtained from the following formula (1) is 90% or more on the basis of the number, and the circularity a The proportion of particles having a ratio of 0.98 or more is less than 30% on a number basis,
      Circularity a = L ₀ / L (1)
  (L ₀ ; Circumference of a circle having the same projected area as the particle image, L; circumference of the particle image)
  The resin fine particles have an average particle diameter of 0.05 to 2.0 μm, a shape factor SF-1 of 100 or more and less than 150, and a shape factor SF-2 of 110 or more and less than 200. Relates to a toner.
[0010]
According to another aspect of the present invention, there is provided an image forming apparatus having at least a latent image holding member and a developing device for visualizing a latent image, wherein the developing device uses at least a surface material of silicone as a toner regulating member. ,
The present invention relates to an image forming method using the above negatively chargeable toner as the toner.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
For the particle size distribution of the toner particles according to the present invention based on the equivalent circle diameter, a value measured using a flow type particle image analyzer FPIA-1000 manufactured by Toa Medical Electronics Co., Ltd. was used. In this apparatus, the equivalent circle diameter is measured as follows.
[0012]
The measurement removes fine debris through a filter and results in 10^-3cm^ThreeA surfactant (preferably an alkylbenzene sulfonate) is added in 100 to 150 ml of water having a measurement range (for example, an equivalent circle diameter of 0.60 μm or more and less than 159.21 μm) of 20 or less in water. Add 0.5 ml, further add 0.1 to 0.5 g of the measurement sample, perform dispersion treatment for about 1 to 3 minutes with an ultrasonic disperser, and adjust the particle concentration of the measurement sample to 3000 to 10,000 particles / 10.^-3cm^ThreeUsing the sample dispersion liquid prepared for (measurement equivalent circle diameter range), the particle size distribution and circularity distribution of particles having an equivalent circle diameter of 0.60 μm or more and less than 159.21 μm are measured, and the circle equivalent The number-based content and number average particle diameter of particles having a diameter equivalent to a circle of 0.60 μm or more and less than 1.00 μm are calculated.
[0013]
The outline of the measurement is described in the catalog (June 1995 edition) of FPIA-1000 published by Toa Medical Electronics Co., Ltd., the operation manual of the measuring apparatus, and JP-A-8-136439. It is.
[0014]
The sample dispersion is passed through a flat and flat transparent flow cell (thickness: about 200 μm) flow path (spread along the flow direction). The strobe and the CCD camera are mounted on the flow cell so as to be opposite to each other so as to form an optical path that passes through the thickness of the flow cell. While the sample dispersion is flowing, strobe light is irradiated at 1/30 second intervals to obtain an image of the particles flowing through the flow cell, so that each particle has a certain range parallel to the flow cell. Photographed as a two-dimensional image. From the area of the two-dimensional image of each particle, the diameter of a circle having the same area is calculated as the equivalent circle diameter.
[0015]
In about 1 minute, the equivalent circle diameter of 1200 or more particles can be measured, and the number based on the equivalent circle diameter distribution and the ratio (number%) of particles having a prescribed equivalent circle diameter can be measured. In particular, the particle concentration of the example is 6000 particles / 10.^-3cm^ThreeIn the case of this toner dispersion, about 1800 equivalent circle diameters can be measured in about 1 minute.
[0016]
As shown in Table 1, the results (frequency% and cumulative%) can be obtained by dividing the range of 0.06 to 400 μm into 226 channels (divided into 30 channels for one octave). In actual measurement, particles are measured in the range where the equivalent circle diameter is 0.60 μm or more and less than 159.21 μm.
[0017]
[Table 1]

[0018]
Conventionally, there have been several apparatuses capable of measuring a particle diameter of less than 1.00 μm, but noise was greatly affected in an area of less than 1.00 μm, and there was a problem in data reproducibility. The above apparatus has good reproducibility even in a region with an equivalent circle diameter of less than 1.00 μm, and since information as a particle image can be actually obtained at the same time, particles can be confirmed.
[0019]
In the toner particle according to the present invention, in the particle size distribution by the equivalent circle diameter, the ratio of 0.60 μm or more and less than 1.00 μm is less than 5.0% on the number basis, and the number average equivalent circle diameter is 4.0 to 10.0 μm. Can solve the problem.
[0020]
In the particle size distribution by the equivalent circle diameter of the toner particles, when the ratio of 0.60 μm or more and less than 1.00 μm is 5.0% or more on the basis of the number, the amount of the external additive in one toner particle is reduced, and before transfer The charge amount of the toner cannot be sufficiently increased, and the negative sleeve ghost suppression is deteriorated. Also, when the number average equivalent circle diameter is less than 4.0 μm, cleaning failure occurs, and when the number average equivalent circle diameter exceeds 10.0 μm, so-called filming in which the toner adheres to the photoreceptor occurs. .
[0021]
Among the toner particles having a particle size of 3.00 μm or more, 90% or more of particles having a circularity a of 0.90 or more on the number basis, and particles having a circularity a of 0.98 or more are less than 30%. It is preferable.
[0022]
When the toner particles have an equivalent circle diameter of 3.00 μm or more and the degree of circularity a is less than 90% on the basis of the number of particles, the adhesion of the toner to the photoreceptor increases and the transferability deteriorates. . In addition, when there are 30% or more of particles having a circularity a of 0.98 or more, cleaning failure occurs.
[0023]
The circularity a in the present invention is used as a simple method for quantitatively expressing the shape of the particles. For example, the flow type particle image analyzer FPIA-1000 manufactured by Toa Medical Electronics is used to obtain from the following formula. The value obtained is defined as circularity.
[0024]
Circularity a = L₀/ L
(L₀; Circumference of a circle having the same projected area as the particle image, L; circumference of the particle image)
[0025]
The circularity distribution of the toner particles in the present invention was calculated by the above formula using the above particle image analyzer in the same manner as the measurement of the equivalent circle diameter described above.
[0026]
The resin fine particles used in the present invention have a shape factor SF-1 of 100 or more and less than 150 (more preferably SF-1 is 115 or more and less than 145), and a shape factor SF-2 of 110 or more and less than 200 (more preferably). SF-2 is preferably 120 or more and less than 175).
[0027]
In order to exert the effect of containing resin fine particles, it is important to define the sphericity (SF-1) and irregularity (SF-2) of both after defining the particle diameter of the resin fine particles, The present inventors discovered as a result of earnest examination.
[0028]
When the shape factor SF-1 is 150 or more or the shape factor SF-2 is 200 or more, the contact area between the toner particles and the resin fine particles is extremely reduced, and the charge amount of the toner before transfer cannot be sufficiently increased. Negative sleeve ghost suppression worsens. Further, when SF-2 is 100 or more and less than 110, a cleaning failure occurs.
[0029]
The shape factors SF-1 and SF-2 used Hitachi FE-SEM (S-800), and 10 images of the external additives within the range of the average particle diameter of the present invention were magnified 30000 to 60000 times. The image information is sampled at random, and the image information is introduced into the image analysis apparatus (Luzex 3) manufactured by Nicole via the interface, analyzed, and calculated from the following equation.
[0030]
[Expression 1]

(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.)
[0031]
The toner of the present invention further suppresses negative sleeve ghost by externally adding fine particles having an average particle size of resin fine particles of 0.05 to 2.0 μm, preferably 0.1 to 1.0 μm, to the toner base particles. be able to. When the average particle size of the resin fine particles is less than 0.05 μm, the adhesion force of the fine particles to the toner surface is too large, and separation from the toner base does not occur sufficiently at the time of development and transfer, increasing the charge amount of the toner before transfer. Negative sleeve ghost suppression is exacerbated because it cannot. When the average particle diameter of the resin fine particles exceeds 2.0 μm, the surface area of the resin fine particles is small, and the effect of increasing the charge amount of the toner before transfer is small, and the negative sleeve ghost suppression is deteriorated. In addition, toner particles may aggregate using resin fine particles as nuclei, resulting in an increase in fog.
[0032]
The content of the resin fine particles in the toner is preferably 0.01 to 0.5% by weight. When the content of the fine particles in the toner is less than 0.01% by weight, the effect of increasing the charge amount of the toner before transfer is insufficient, and the negative sleeve ghost cannot be sufficiently prevented. If the content of the fine particles in the toner exceeds 0.5% by weight, fog is likely to occur.
[0033]
Preferably, a negatively chargeable toner is used in which the resin fine particles have a positive chargeability. When the resin fine particles have positive chargeability, the charge amount of the toner before transfer can be increased, and the effect of suppressing the negative sleeve ghost is further enhanced.
[0034]
(Measurement of charging polarity of resin fine particles)
2 parts by weight of resin fine particles to be measured as a sample and 98 parts by weight of iron powder are mixed with a turbula mixer for 60 seconds. In the apparatus shown in FIG. 7, this mixture is put in a metal container 82 having a 500 mesh conductive screen 83 attached to the bottom. The potential of the capacitor 88 at that time is set to zero. Then, it is sucked by the suction machine 81 through the suction port 87, and the charging polarity is judged from the voltage polarity stored in the capacitor 88 connected to the container 82. That is, iron powder remains on 500 mesh, and the sample passes through 500 mesh. For example, when a positive sample is used, a negative voltage remains in the capacitor 83.
[0035]
In FIG. 7, 84 indicates a lid, 85 indicates a vacuum gauge, and 89 indicates an electrometer. At the time of suction, the suction pressure is 250mmH₂O. As the iron powder, for example, EFV 200/300 (manufactured by Powder Tech) is used.
[0036]
Examples of the resin constituting the resin fine particles include melamine resins, and polymerizable monomers such as styrene such as styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, p-methoxystyrene, and p-ethylstyrene. Monomers: acrylic acid monomer; methacrylic acid monomer; methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, n-propyl acrylate, n-octyl acrylate, dodecyl acrylate Acrylate monomers such as 2-ethylhexyl acrylate, stearyl acrylate, 2-chloroethyl acrylate, phenyl acrylate; methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, n-butyl methacrylate, methacryl Isobutyl acid, n-octyl methacrylate, Methacrylic acid ester monomers such as dodecyl tacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, phenyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate; other monomers such as acrylonitrile, methacrylonitrile, acrylamide The body is mentioned. In particular, it is preferable to use a melamine resin.
[0037]
As the polymerization method, suspension polymerization, emulsion polymerization, soap-free polymerization, and the like can be used, but particles obtained by soap-free polymerization are more preferable.
[0038]
Further, as a means for obtaining the desired SF-1 and SF-2 values for the resin fine particles, a method of applying a mechanical impact force to the obtained resin fine particles can be considered.
[0039]
In particular, it has been confirmed that the resin fine particles having the above characteristics have a great effect on suppressing fusion of the photosensitive drum in a contact charging system such as a roller, a brush or a blade as a primary charging device.
[0040]
As the external additive of the inorganic fine powder used in the toner of the present invention, an inorganic fine powder such as silica, alumina, titania, or a double oxide thereof is used for improving charging stability, developability, fluidity, and storage stability. preferable. Further, silica is more preferable. For example, such a silica can be used as a so-called dry method produced by vapor phase oxidation of a silicon halogen compound or an alkoxide, or a dry silica and alkoxide called fumed silica, or a so-called wet silica produced from water glass. There are few silanol groups on the surface and in the silica fine powder, and Na₂O, SO_Three  ^2-For example, dry silica with less production residue is preferred. In dry silica, it is 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.
[0041]
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, and 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 with respect to 100 parts by weight of toner particles. It is particularly good to use up to 3.0 parts by weight.
[0042]
The inorganic fine powder used in the present invention is made of silicone varnish, silicone oil, various modified silicone oils, silane coupling agents, silane coupling agents having functional groups, and other organic substances for the purpose of hydrophobization and chargeability control as necessary. It is preferable that treatments such as silicon compounds and organic titanium compounds are used alone or in combination.
[0043]
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.
[0044]
In order to maintain stable toner storage stability, the inorganic fine powder is preferably treated with at least silicone oil.
[0045]
The binder resin used in the toner particles of the present invention includes, for example, polyethylene, poly-p-chlorostyrene, styrene such as polyvinyltoluene, and a homopolymer of its substitution product, styrene-p-chlorostyrene copolymer. Polymer, styrene-vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, styrene-acrylic acid ester copolymer, styrene-methacrylic acid ester copolymer, styrene-α-chloromethyl methacrylate copolymer, styrene- Acrylonitrile copolymer, styrene-vinyl methyl ether copolymer, styrene-vinyl ethyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-acrylonitrile- Styrene like indene copolymer Copolymer; Polyvinyl chloride; Phenol resin; Naturally modified phenolic resin; Natural resin modified maleic acid resin; Acrylic resin; Methacrylic resin; Polyvinyl acetate; Silicone resin; Polyester resin; Xylene resin; polyvinyl butyral; terpene resin; coumarone indene resin; petroleum resin can be used. Cross-linked styrene resins are also preferred binder resins.
[0046]
As a comonomer with respect to the styrene monomer of a styrene-type copolymer, a vinyl-type monomer can be used individually or in combination. Examples of vinyl monomers include acrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, dodecyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, phenyl acrylate, methacrylic acid, methyl methacrylate, Monocarboxylic acid having a double bond such as ethyl methacrylate, butyl methacrylate, octyl methacrylate, acrylonitrile, methacrylonitrile, acrylamide or a substituted product thereof; for example, maleic acid, butyl maleate, methyl maleate, dimethyl maleate Dicarboxylic acids having a double bond such as, and substituted products thereof; vinyl esters such as vinyl chloride, vinyl acetate and vinyl benzoate; ethylene-based olefins such as ethylene, propylene and butylene; Methyl ketone, such as vinyl ketones vinyl hexyl ketone; for example, vinyl methyl ether, vinyl ethyl ether, such as vinyl ethers vinyl isobutyl ether. Here, as the crosslinking agent, a compound having two or more polymerizable double bonds is mainly used, and these can be used alone or in combination. Examples of such compounds include aromatic divinyl compounds such as divinylbenzene and divinylnaphthalene; carboxyls having two double bonds such as ethylene glycol diacrylate, ethylene glycol dimethacrylate, and 1,3-butanediol dimethacrylate. Acid esters; divinyl compounds such as divinylaniline, divinyl ether, divinyl sulfide, divinyl sulfone; and compounds having three or more vinyl groups can be used alone or as a mixture.
[0047]
As the colorant used in the present invention, carbon black, a magnetic material, and a yellow / magenta / cyan colorant shown below are used as a black colorant, and a black colorant is used.
[0048]
As the yellow colorant, compounds represented 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.
[0049]
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.
[0050]
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, and 66 can be particularly preferably used.
[0051]
These colorants can be used alone or in combination, and further in a solid solution state. 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 weight based on 100 parts by weight of the resin.
[0052]
When a magnetic material is used as the black colorant, it is used by adding 30 to 200 parts by weight to 100 parts by weight of the resin, unlike other colorants.
[0053]
As the magnetic material, there is a metal oxide containing an element of iron, cobalt, nickel, copper, magnesium, manganese, aluminum, or silicon. Among them, those containing iron oxide as a main component such as triiron tetroxide and γ-iron oxide are preferable. 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 a Mohs hardness of 5 to 7 is preferred.
[0054]
As the shape of the magnetic material, there are octahedron, hexahedron, spherical shape, needle shape, and scaly shape, but octahedron, hexahedron, sphere, and amorphous type with less anisotropy are preferable for increasing the image density. .
[0055]
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.
[0056]
The amount of the magnetic material is 30 to 200 parts by weight, preferably 40 to 200 parts by weight, and more preferably 50 to 150 parts by weight with respect to 100 parts by weight of the binder resin. If it is less than 30 parts by weight, in a developing device that uses magnetic force for toner conveyance, the conveyance performance is insufficient, and the developer layer on the developer carrier tends to become uneven, resulting in image unevenness. The image density tends to decrease due to the above. On the other hand, when the amount exceeds 200 parts by weight, there is a tendency that a problem occurs in the fixing property.
[0057]
In the present invention, if necessary, wax may be internally added to the toner particles. Examples of the wax used include polypropylene, polyethylene, microcrystalline wax, carnauba wax, sazol wax, paraffin wax, higher alcohol wax, ester wax, and oxides and graft modified products thereof.
[0058]
These low molecular weight waxes may be added and mixed in the binder resin in advance when the toner is produced. The addition amount is preferably about 1 to 20 parts by weight with respect to 100 parts by weight of the binder resin.
[0059]
In the toner of the present invention, a charge control agent can be blended (internally added) into toner particles or mixed (externally added) with toner particles as necessary. 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.
[0060]
The following substances are used for controlling the toner to be negatively charged. 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. Others include aromatic hydroxycarboxylic acids, aromatic monocarboxylic acids, aromatic polycarboxylic acids and their metal salts, their anhydrides, their esters, and phenol derivatives such as bisphenol.
[0061]
The above-described charge control agent is preferably used in the form of fine particles. In this case, the number average particle diameter of these charge control agents is 4 μm or less, preferably 3 μm or less, more preferably 0.5 to 3 μm. When these charge control agents are internally added to the toner, it is preferable to use 0.1 to 20 parts by weight, particularly 0.2 to 10 parts by weight, based on 100 parts by weight of the binder resin.
[0062]
The average particle diameter of the resin fine particles and the charge control agent is a value measured by the following method.
[0063]
Using an electron microscope S-800 (manufactured by Hitachi, Ltd.), photographs were taken at a magnification of 10,000 to 20000 times for the resin fine particles and 1000 to 5000 times for the charge control agent. For particles having a particle size of 01 μm or more, 100 to 200 charge control agents are randomly extracted from particles having a particle size of 0.05 μm or more, each diameter is measured using a measuring instrument such as a caliper, and each particle is averaged. Average particle diameter.
[0064]
In general, for producing a toner, for example, a binder resin, a pigment as a colorant, a dye, or a magnetic material, and if necessary, a wax, a metal salt or metal complex, a charge control agent, and other additives are added to a Henschel mixer. After mixing thoroughly with a mixer such as a ball mill, the resin is melted and kneaded using a heat kneader such as a heating roll, kneader, and extruder, and the resins are mixed with each other. A method in which a compound, pigment, or dye is dispersed or dissolved, cooled, solidified, pulverized, and classified and surface-treated as necessary to obtain toner particles, and resin fine particles and inorganic fine powder are added and mixed. Preferably used.
[0065]
As a means for applying a mechanical impact force to the toner of the present invention, 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., or a mechano-fusion manufactured by Hosokawa Micron Co., Ltd. There is a method of applying a mechanical impact force to the toner by a compressive force or a frictional force by pressing the toner to the inside of the casing by a centrifugal force with a blade rotating at high speed as in a system or a hybridization system manufactured by Nara Machinery Co., Ltd. Specifically, in order to obtain the toner of the present invention, for example, a turbo mill manufactured by Turbo Industry, which is a mechanical impact pulverizer shown in FIG. 4, is used, and the peripheral speed of the blade 121 is 60 m in an atmosphere of 35 ° C. or higher. For example, a method of adjusting the circularity distribution and the particle size distribution while finely pulverizing the toner by rotating the rotor 114 in a range of about 150 m / second to 150 m / second, or a method of performing a surface treatment by a mechanical impact force. preferable.
[0066]
In the case of applying a mechanical impact force, it is particularly preferable to increase the negative sleeve ghost suppression after the finely pulverizing step of the toner or after the further classification step.
[0067]
The mechanical impact type pulverizer shown in FIG. 4 has a vertical rotating rotor in which four processing blades 121 are horizontally mounted on a horizontal disk as shown in the sectional view of FIG. A surface reforming apparatus I of a type that gives mechanical impact force 114 has the processing chamber 1 arranged in four stages along the rotation shaft 115 extending in the horizontal direction. As a specific method for the surface treatment, each of the rotors 114 is rotated at a peripheral speed of 40 m / s by the movement of the drive motor 4, and as shown in FIG. Install blower 24, blower air volume 3.0m²The toner in the toner container 40 is supplied from the inlet 111 at a rate of 20 kg / hour by the auto feeder 15 from the toner supply port at the top of the processing apparatus in the state where the toner is sucked in, and the surface of the toner is processed. is there. The toner introduced into the processing chamber 1 of the surface reforming apparatus is subjected to a spheroidizing process by receiving an impact force when passing through the minute gap 113 between the rotating processing blade 121 and the inner wall of the processing chamber 1.
[0068]
The surface-treated toner passes through the cyclone inlet 19 from the outlet 10 and is collected by the rotary valve 21. The toner fine powder is collected by the rotary valve 23 through the bag filter 22.
[0069]
In the impact surface treatment apparatus, as shown in FIGS. 2 and 3, the rotating shaft 61 is driven by the driving means, and the rotating disk 62 is rotated at a peripheral speed at which particles are not crushed due to the nature of the material to be surface treated. The rapid air flow generated with the rotation of the rotating disk causes a circulating flow around the circulation path 63 opened to the impact chamber 68 and returning to the center of the rotating disk 62.
[0070]
Next, a certain amount of powder to be treated is put into the impact chamber 68 from the raw material hopper 64, and the thrown powder to be treated is momentarily hit by the rotating disk 62 rotating at high speed, and the surrounding collision ring After entering into 58 and receiving an impact action, the circulation flow returns to the impact chamber 68 again through the circulation path 63, and the impact treatment is again applied to perform the surface treatment. The rotating disk is preferably rotated so that the peripheral speed of the blade 55 is in the range of 60 m / sec to 150 m / sec.
[0071]
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.
[0072]
A preferred specific example of the image forming method of the present invention will be described with reference to FIG.
[0073]
The surface of the OPC photosensitive drum 153 as an electrostatic latent image holding member is negatively charged by a contact charging member 161 composed of a charging roller as a primary charger, and a digital electrostatic latent image is obtained by image scanning by laser light exposure 155. A negative triboelectrically chargeable magnetic toner 163 of a developing device 151 as a developing means, which includes a developing sleeve (toner carrier) 156 that includes an elastic blade 158 made of urethane rubber and a magnet 165 disposed in the counter direction. The electrostatic latent image is reversely developed. Alternatively, an amorphous silicon photoconductor is used, the amorphous silicon photoconductor is charged to a positive polarity, an electrostatic latent image is formed, and normal development is performed using a negative triboelectrically chargeable magnetic toner. An alternating bias, a pulse bias, and / or a direct current bias is applied to the developing sleeve 156 by the bias applying unit 162. When the recording paper P as the recording material is transported and reaches the transfer section, it is charged from the back surface (opposite to the photosensitive drum side) of the recording paper P by the contact transfer member 154 consisting of a transfer roller as the transfer means. The toner image on the surface of the photosensitive drum is electrostatically transferred onto the recording paper P. The recording paper P separated from the photosensitive drum 153 includes a fixing roller 171 and a pressure roller 172 of a heat and pressure fixing device having a fixing roller 171 having a heating unit 170 therein and a pressure roller 172 in pressure contact with the fixing roller 171. In order to fix the toner image on the recording paper P by passing through the press contact portion, a fixing process is performed.
[0074]
The toner remaining on the photosensitive drum 153 after the transfer process is removed by a cleaning device 164 having a cleaning blade 157. The cleaned photosensitive drum 153 is neutralized by erase exposure 160, and the process starting from the charging process by the primary charger 161 is repeated again.
[0075]
The electrostatic latent image holding member (photosensitive drum) has a photosensitive layer and a conductive substrate, and moves in the direction of the arrow. A non-magnetic cylindrical developing sleeve 156 that is a developer carrying member rotates so as to advance in the same direction as the surface of the electrostatic latent image holding member in the developing portion. Inside the non-magnetic cylindrical developing sleeve 156, a multi-pole permanent magnet 165 (magnet roll) as a magnetic field generating means is arranged so as not to rotate. The toner 163 in the developing device 151 is applied on the nonmagnetic cylindrical surface, and the toner particles are given a negative triboelectric charge by friction between the surface of the developing sleeve 156 and the toner particles. Further, by arranging an elastic doctor blade 158, the thickness of the developer layer is made thin (30 μm to 300 μm) and uniformly regulated, and a toner layer thinner than the gap between the photosensitive drum 153 and the developing sleeve 156 in the developing unit is not formed. Form to be in contact. By adjusting the rotational speed of the sleeve 156, the sleeve surface speed is made substantially equal to or close to the speed of the electrostatic latent image holding member surface.
[0076]
An AC bias or a pulse bias may be applied to the developing sleeve 156 by the bias unit 162. This AC bias preferably has f of 200 to 4,000 Hz and Vpp of 500 to 3,000 V.
[0077]
When the toner particles are transferred in the development portion, the toner particles are transferred to the electrostatic latent image side by the electrostatic force on the surface of the photosensitive drum 153 holding the electrostatic latent image and the action of an AC bias or a pulse bias.
[0078]
The developing sleeve 156 may have an arbitrary structure. Usually, it comprises a non-magnetic developing sleeve 156 with a magnet 165 built-in. The developing sleeve 156 may be a cylindrical rotating body as shown. It is also possible to form a belt that circulates and moves. Usually, aluminum or SUS is preferably used as the material.
[0079]
The elastic blade 158 used in the present invention uses silicone as a material. Among silicones, silicone rubber having elasticity as a material is particularly preferable. Moreover, an organic compound and an inorganic compound may be added to silicone, and it may be melt-mixed or dispersed. Examples include metal oxides, metal powders, ceramics, carbon allotropes, whiskers, inorganic fibers, dyes, pigments, and surfactants. As a method of bringing the elastic blade into contact with the developing sleeve, in addition to the method of bringing the elastic silicone rubber blade into contact as it is, a method in which another elastic silicone such as metal is bonded to the portion in contact with the developing sleeve may be used. good.
[0080]
By combining the toner of the present invention with the elastic blade using silicone as a material, there is an effect of further improving the negative sleeve ghost. It is considered that the use of silicone for the elastic blade increases the chargeability of the toner to be developed, and as a result, the chargeability of the toner before transfer increases.
[0081]
When the image forming method of the present invention is applied to a facsimile printer, the optical image exposure L is an exposure for printing received data. FIG. 5 is a block diagram showing an example of this case.
[0082]
The controller 181 controls the image reading unit 180 and the printer 189. The entire controller 181 is controlled by the CPU 187. The read data from the image reading unit is transmitted to the partner station through the transmission circuit 183. Data received from the partner station is sent to the printer 189 through the receiving circuit 182. Predetermined image data is stored in the image memory. The printer controller 188 controls the printer 189. 184 is a telephone.
[0083]
The image received from the line 185 (image information from the remote terminal connected via the line) is demodulated by the receiving circuit 182, and then the CPU 187 performs decoding processing of the image information and sequentially stores it in the image memory 186. The When at least one page image is stored in the memory 186, image recording of the page is performed. The CPU 187 reads one page of image information from the memory 186 and sends the combined one page of image information to the printer controller 188. When the printer controller 188 receives image information of one page from the CPU 187, the printer controller 188 controls the printer 189 to record the image information of the page.
[0084]
Note that the CPU 187 receives the next page during recording by the printer 189.
[0085]
As described above, the image is received and recorded.
[0086]
【Example】
EXAMPLES Hereinafter, although a manufacture example and an Example demonstrate this invention concretely, this does not limit this invention at all. In addition, all the parts in the following mixing | blending are a weight part.
[0087]

[0088]
The above materials are mixed with a blender, melt-kneaded with a twin screw extruder heated to 130 ° C., the cooled kneaded product is coarsely pulverized with a hammer mill, and coarsely crushed with a pulverizing means having an airflow classifier and a collision-type airflow pulverizer. The grinding was pulverized. The obtained finely pulverized product is 2.0 kg / cm in a multi-division classifier using the Coanda effect that incorporates a forced powder dispersion device using compressed air in the powder supply unit.²The particles are supplied while being forcedly dispersed with compressed air and strictly classified, and the ratio of the number average equivalent circle diameter of 6.2 μm and the equivalent circle diameter of 0.60 μm to less than 1.00 μm is based on the number. 3.7% of magnetic toner particles were obtained.
[0089]
Further, the magnetic toner particles were subjected to a surface treatment by using a surface modification device of a system that applies a mechanical impact force by rotating a rotor. The obtained toner particles 1 have a number average equivalent circle diameter of 6.4 μm, the proportion of particles having an equivalent circle diameter of 0.60 μm or more and less than 1.00 μm is 0.7% based on the number, and the circularity a is 0.00. 90 or more particles were 95.2% on the number basis, and particles having a circularity a of 0.98 or less were 24.0% on the number basis.
[0090]
To the obtained toner particles 1, 0.1% of resin fine particles a shown in Table 2 and 1.2% of silicone oil and hexamethyldisilazane-treated dry silica are added and mixed in a mixer to obtain toner 1. It was.
[0091]
[Image evaluation]
Evaluation was made using the following developing devices.
[0092]
As a developer carrier, carbon black, graphite, and acrylic resin particles are 1: 9: 0.75 in 10 parts of phenol resin on the surface of a sleeve of an aluminum cylinder tube (outer diameter: 20 mm) as drawn. What coated the resin coating layer disperse | distributed in the ratio (average surface roughness 1.3 micrometers) was used.
[0093]
In addition, a quadrupole magnet having a developing pole magnetic flux density of 90 mT was built in the cylindrical sleeve.
[0094]
As the developer regulating member, a 1.55 mm thick silicone rubber blade was used and brought into contact with the developer carrying member with a 26.4 N drawing pressure.
[0095]
As the photosensitive member, an organic photosensitive member having a diameter of 62 mm was used, and the closest distance between the developer carrying member and the photosensitive member was set to 300 μm.
[0096]
A roller charger was used as the primary charger, laser light was used as the exposure means, and a latent image was formed at 600 dpi. A roller charger was used as the transfer charger.
[0097]
A blade cleaning device was used as a cleaning device for removing the developer remaining on the photoconductor in the transfer process, and a urethane blade was used as the cleaning blade.
[0098]
The potential of the latent image on the photosensitive member was set to have a dark part potential: -500V and a bright part potential -150V.
[0099]
The photoreceptor was rotated at 117 m / s. The developer carrying member was rotated at 140 m / s. A rectangular wave having a DC voltage of −500 V, an AC voltage of 1600 V (peak to peak), and an AC frequency of 2300 Hz was applied as a developing bias to the developer carrying member.
[0100]
[Evaluation of negative sleeve ghost]
Using the above-mentioned developing device as a developing device, there is a solid black image on the developer carrying member 1 block as shown in FIG. The negative sleeve ghost was evaluated based on the image density difference. Specifically, it is a value obtained by subtracting the image density of the area A from the image density of the area B in FIG. The evaluation results are shown in Table 3. The image density was measured with a Macbeth reflection densitometer.
[0101]
When toner 1 was used as the toner and negative sleeve ghost was evaluated by the above method, the image density difference was 0.01, and the negative sleeve ghost suppression was very good.
[0102]
Further, 5000 images were printed, and the image density of the solid black image and the fog on the photoconductor were measured. The fog on the photoconductor was evaluated by a numerical value obtained by subtracting the reflection density of the tape with only the tape from the reflection density of what was stuck on the paper after taping off the transfer residual toner on the solid white photoconductor with tape. . In addition, fog was measured using a reflection densitometer (TOKYO DENSHOKU CO., REFECTOMETER ODEL TC-6DS manufactured by LTD). The reflection density average value Dr before printing was subtracted from the reflection density worst value Ds after printing. Value; Ds-Dr).
[0103]
(Measurement of toner triboelectric charge)
The triboelectric charge amount of the toner is obtained using a suction type Faraday cage method.
[0104]
The suction type Faraday cage method uses a toner recovery device to suck and recover all toner in a certain area on the developing sleeve of a copying machine or printer, and measures the weight and charge amount of the recovered toner, and the measured toner In this method, the charge amount per unit weight of the toner, that is, the triboelectric charge amount (mC / kg) is obtained from the weight of the toner and the charge amount.
[0105]
The toner recovery device used in the suction type Faraday cage method has a suction device for sucking toner together with air and a recovery device for recovering toner connected to the suction device. The collecting device includes an outer cylinder having a suction port having a tip corresponding to the outer peripheral curvature of the developing sleeve for sucking the toner on the developing sleeve, and a cylindrical filter paper for collecting the sucked toner. And a cylinder.
[0106]
In order to specifically perform the suction and recovery of the toner on the developing sleeve using this toner recovery device, the rotation of the developing sleeve is stopped, and the toner on the developing sleeve is transferred to one end of the developing sleeve by using the suction device. From the side to the other end side, suction is performed while pressing the suction port of the suction device against the surface of the developing sleeve along the longitudinal direction, and the sucked toner is collected by the cylindrical filter paper of the collection device.
[0107]
Weight W of cylindrical filter paper from which toner has been collected₂(G) is measured, and the weight W of the cylindrical filter paper before recovery from the weight of the cylindrical filter paper after recovery.₁The value obtained by subtracting (g) is the weight W of the collected toner.₂-W₁(G). At this time, an electrometer (Model 617 manufactured by KEITKEY Co.) is connected to the recovery device, and the charge amount E (μC) of the toner recovered on the cylindrical filter paper of the inner cylinder electrostatically shielded from the outside is measured. The toner triboelectric charge amount Qm (mC / kg) is obtained based on the following equation.
Qm = E / (W₂-W₁)
[0108]
<Examples 2 to 4, Comparative Example 1>
Toners 2 to 5 shown in Table 3 were obtained in the same manner as in Example 1 except that the resin fine particles added in Example 1 were changed to resin fine particles be to e shown in Table 2.
[0109]
<Examples 5 to 8>
Toners 6 to 9 shown in Table 3 were obtained in the same manner as in Example 1 except that the addition amount of the resin fine particles a added in Example 1 was changed to the amount shown in Table 3.
[0110]
<Example 9>
Toner 10 shown in Table 3 was obtained in the same manner as in Example 1 except that the surface treatment by mechanical impact force was not performed. Table 1 shows the physical properties of the toner particles 2 obtained in the production process.
[0112]
  <Comparative example 2>
  The magnetic material amount of Example 1 is set to 50 parts, and in the classification process, the toner is not forcedly dispersed with compressed air at the time of toner supply, and the surface treatment by mechanical impact force is not performed. Toner shown in Table 311Got. In the manufacturing processGainTable 1 shows the physical properties of the toner particles 3 to be obtained.
[0114]
  [Evaluation]
  Toners 2 to 2 in the above examples and comparative examples11Was evaluated in the same manner as in Example 1. The results are shown in Table 3.
[0115]
  <Comparative example3>
  Evaluation was performed in the same manner as in Example 1 except that in the developing device used for evaluation, resin fine particles e were used as the resin fine particles used, and an elastic blade made of urethane rubber was used as the developer regulating member. The results are shown in Table 3.
[0116]
[Table 1]

[0117]
[Table 2]

[0118]
[Table 3]

[0119]
【The invention's effect】
According to the present invention, since the toner particles have a specific circularity distribution and a specific particle size distribution, the toner particles are excellent in durability and negative sleeve ghost can be suppressed.
[0120]
In particular, the negative sleeve ghost can be further suppressed by the resin fine particles having a defined particle diameter and shape contained in the toner.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of an image forming apparatus capable of carrying out an image forming method of the present invention.
FIG. 2 is a diagram illustrating an example of a processing apparatus system.
3 is a schematic cross-sectional view of the surface treatment apparatus in FIG.
FIG. 4 is a diagram showing an example of a mechanical crusher.
FIG. 5 is a block diagram for applying the image forming method of the present invention to a printer of a facsimile apparatus.
FIG. 6 is an explanatory diagram of a sleeve ghost evaluation method.
FIG. 7 is a schematic explanatory diagram of a measuring apparatus for measuring the charging polarity of resin fine particles.
[Explanation of symbols]
1 Cylindrical casing
4 Pulley
10 Discharge port
15 Vibrating feeder
19 Valve
20 Cyclone
21,23,26 Valve
22 Bug filter
24 Blower
28 Discharge valve control device
40 metering machine
59 Discharge on / off valve
60 outlet
62 Turntable
63 Circulation circuit
64 Raw material hopper
68 Shock chamber
77 jacket
110 liner
111 slot
113 Processing area
114 rotor
115 rotor shaft
121 blade
151 Development Device
153 Photosensitive drum
156 Development sleeve
158 Elastic blade
163 Toner
171 Fixing roller
172 Pressure roller

Claims (16)

A negatively chargeable toner having at least toner particles, inorganic fine powder and resin fine particles,
The toner particles have at least a binder resin and a colorant, and the proportion of particles having an equivalent circle diameter of 0.60 μm or more and less than 1.00 μm is based on the number in the particle size distribution by the equivalent circle diameter of the toner particles. Less than 5.0% of the total, and the number average equivalent circle diameter is 4.0 to 10.0 μm,
In the toner particles having a circle-equivalent diameter of 3.00 μm or more, the ratio of the particles having a circularity a of 0.90 or more obtained from the following formula (1) is 90% or more on the basis of the number, and the circularity a The proportion of particles having a ratio of 0.98 or more is less than 30% on a number basis,
Circularity a = L ₀ / L (1)
(L ₀ : Perimeter of a circle having the same projected area as the particle image, L: Perimeter of the particle image)
The resin fine particles have an average particle diameter of 0.05 to 2.0 μm, a shape factor SF-1 of 100 or more and less than 150, and a shape factor SF-2 of 110 or more and less than 200. Toner.   2. The negatively chargeable toner according to claim 1, wherein the resin fine particles have a shape factor SF-1 of 115 or more and less than 145, and a shape factor SF-2 of 120 or more and less than 175.   3. The negatively chargeable toner according to claim 1, wherein the resin fine particles have an average particle size of 0.1 to 1.0 μm.   4. The negatively chargeable toner according to claim 1, wherein the resin fine particles are contained in the toner in an amount of 0.01 to 0.5% by weight.   5. The negatively chargeable toner according to claim 1, wherein the resin fine particles are composed of a melamine formaldehyde resin or a benzoguanamine-formaldehyde resin.   The negatively chargeable toner according to claim 1, wherein the resin fine particles have positive chargeability.   The negatively chargeable toner according to claim 1, further comprising means for removing at least particles having an equivalent circle diameter of less than 1.00 μm in the developing toner manufacturing process.   The negatively chargeable toner according to claim 7, wherein the step of removing particles having an equivalent circle diameter of less than 1.00 μm of the toner particles is a process of applying a mechanical impact force. In an image forming apparatus having at least a latent image holding member and a developing device for visualizing a latent image, the developing device uses at least a surface material of silicone as a toner regulating member.
The toner to be used is a negatively chargeable toner having at least toner particles, inorganic fine powder and resin fine particles,
The toner particles have at least a binder resin and a colorant, and the proportion of particles having an equivalent circle diameter of 0.60 μm or more and less than 1.00 μm is based on the number in the particle size distribution by the equivalent circle diameter of the toner particles. Less than 5.0% of the total, and the number average equivalent circle diameter is 4.0 to 10.0 μm,
In the toner particles having a circle-equivalent diameter of 3.00 μm or more, the ratio of the particles having a circularity a of 0.90 or more obtained from the following formula (1) is 90% or more on the basis of the number, and the circularity a The proportion of particles having a ratio of 0.98 or more is less than 30% on a number basis,
Circularity a = L ₀ / L (1)
(L ₀ : Perimeter of a circle having the same projected area as the particle image, L: Perimeter of the particle image)
The resin fine particles have an average particle diameter of 0.05 to 2.0 μm, a shape factor SF-1 of 100 or more and less than 150, and a shape factor SF-2 of 110 or more and less than 200. Method. The image forming method according to claim 9 , wherein the resin fine particles have a shape factor SF-1 of 115 or more and less than 145, and a shape factor SF-2 of 120 or more and less than 175. The image forming method according to claim 9 or 10 , wherein the resin fine particles have an average particle size of 0.1 to 1.0 µm. The resin fine particles, an image forming method according to any one of claims 9 to 11, characterized in that it is contained 0.01 to 0.5 wt% in the toner. The resin fine particles, melamine-formaldehyde resins or benzoguanamine - The image forming method according to any one of claims 9 to 12, characterized in that it is constituted by formaldehyde resin. The resin fine particles, an image forming method according to any one of claims 9 to 13, characterized in that it has a positive charge. In the manufacturing process of the developing toner image, an image forming method according to any one of claims 9 to 14, characterized in that it comprises a means for removing at least the toner particles of less than the equivalent circle diameter 1.00μm particles. The image forming method according to claim 15 , wherein the step of removing particles having an equivalent circle diameter of less than 1.00 μm of the toner particles is a process of applying a mechanical impact force.

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