JP4310135B2 - Image forming method - Google Patents

Description

【００８２】
【表２】

【００８３】
また、本発明に係る導電性微粒子は、比表面積（ｃｍ²／ｃｍ³）が５×１０⁵以上１００×１０⁵以下であることが望ましい。一般に球形と仮定される粒子がほぼ平面と仮定される部材と接触する場合、接点数は１である。これは導電性微粒子と、帯電部材やトナー粒子との接触についても当てはまる。そこでトナー粒子や帯電部材との接点数を増やすには、材料表面に多数の凹凸を形成すれば接触する凸部が増加し、接触点を増やすことができる。但し、例えばトナー粒子の表面に多数の凹凸を形成させることは、摩擦帯電特性上決して好ましいとは言えない。一方、導電性微粒子表面に凹凸を形成することは、トナー粒子のみならず帯電部材との接触点も増加するため、帯電部材自身の設計などは自由度が広まり好ましい。
【００８４】
すなわち導電性微粒子の表面に多数の凹凸を形成して使用することは、プリンタ本体側や用いるトナーには特殊仕様の必要が無く、広い範囲で適応可能な技術と言える。
【００８５】
この粒子表面の凹凸の数の指標として、粒子粉末の比表面積が通常用いられる。但し、一般に用いられる比表面積はその単位「ｃｍ²／ｇ」からも分かるように、単位質量当たりの表面積であり、この数値を用いる議論では比重の異なる材料での比較あるいは最適化が容易ではない。
【００８６】
そこで本発明者らは比表面積として、微粒子１個当たりの表面積に対応する物性である、「ｃｍ²／ｃｍ³」単位を採用し、導電性微粒子とトナー及び帯電部材との接触点数と、画像特性及び帯電性との関係を鋭意検討した。
【００８７】
使用トナーに含有される導電性微粒子の比表面積（ｃｍ²／ｃｍ³）が５×１０⁵以上１００×１０⁵以下である場合、帯電性並びに画像特性が大きく改善され、特に直接注入帯電機構を含む画像形成方法においては、帯電部材が汚染されても良好な帯電性を維持できることを見出した。これは金属化合物微粒子とトナー及び帯電部材との接触点数を増加させた効果によることは間違いないと思われる。但し、比表面積が大きすぎる場合、即ち表面凸部が多すぎる場合、トナーとの付着性が強すぎるため転写工程時にトナーと共に被転写体上に移動し、感光体上に残らない。従って帯電性改良効果が低下してしまう。好ましくは１０×１０⁵以上８０×１０⁵以下とすることで、より好ましくは１２×１０⁵以上４０×１０⁵以下とすることで、帯電性及び画像特性がより一層向上する。
【００８８】
ここで、金属化合物微粒子の比表面積は以下のようにして求めた。
【００８９】
まず、ＢＥＴ法に従い、比表面積測定装置「ジェミニ２３７５ Ｖｅｒ．５．０」（島津製作所社製）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ＢＥＴ比表面積（ｃｍ²／ｇ）を算出する。
【００９０】
次に、乾式自動密度計「Ａｃｃｕｐｙｃ １３３０」（島津製作所社製）を用いて真密度（ｇ／ｃｍ³）を求める。この際、１０ｃｍ³の試料容器を用い、試料前処理としてはヘリウムガスパージを最高圧１９．５ｐｓｉｇで１０回行う。この後、容器内圧力が平衡に達したか否かの圧力平衡判定値として、試料室内の圧力の振れが０．００５０／ｍｉｎを目安とし、この値以下であれば平衡状態とみなして測定を開始し、真密度を自動測定する。測定は５回行い、その平均値を求め、真密度とする。
【００９１】
ここで、粉体の比表面積は以下のようにして求まる。
比表面積(ｃｍ²／ｃｍ³)＝ＢＥＴ比表面積(ｃｍ²／ｇ)×真密度(ｇ／ｃｍ³)
【００９２】
本発明に係る金属化合物微粒子の好ましい体積抵抗は、１×１０^-1〜１×１０⁹Ωｃｍである。１×１０⁹Ωｃｍを超えると、接触帯電工程を含む画像形成方法において用いた場合帯電性の改良効果が見込まれない。一方、１×１０^-1Ωｃｍ未満の場合は高湿下でのトナーの摩擦帯電特性を阻害してしまい、現像性の低下に加えてカブリや転写性の悪化が見られ、現像同時クリーニングシステムにおいては帯電部材の汚染が悪化してしまうため、比表面積を大きくしたことによる帯電性改良効果が見られなくなってしまう。
【００９３】
ここで、粒子の抵抗の測定は以下のようにして行う。
【００９４】
円筒形の金属製セルに試料を充填し、試料に接するように上下に電極を配し、上部電極には荷重６８６ｋＰａ（７ｋｇｆ／ｃｍ²）を加える。この状態で電極間に電圧Ｖを印加し、その時に流れる電流Ｉ（Ａ）から本発明の抵抗（体積抵抗率ＲＶ）を測定する。この時電極面積をＳ（ｃｍ²）、試料厚みをＭ（ｃｍ）とすると、
ＲＶ（Ωｃｍ）＝１００Ｖ×Ｓ（ｃｍ²）／Ｉ（Ａ）／Ｍ（ｃｍ）
である。本発明では、電極と試料の接触面積２．２６ｃｍ²とし、電圧Ｖ＝１００Ｖで測定した。
【００９５】
本発明に係る導電性微粒子は少なくとも酸化スズを有していることが望ましい。本発明の実施例では直接注入帯電機構とクリーナレスを組み合わせて行っており、注入電荷用トラップ剤としての導電性酸化スズを表面保護層に含有させた有機感光体を用いているが、この時、感光体と帯電部材の当接部に存在する金属化合物微粒子が酸化スズを含有している場合が直接注入帯電性が良好であった。このことは、金属化合物微粒子から感光体表面のトラップ剤への電荷移動は同元素間の方が障壁が少なく速いためと思われる。従って、該金属化合物微粒子が少なくとも酸化スズを含有していることが好ましく、その含有量が多い方が良い。
【００９６】
しかしながら、通常の酸化スズがほぼ１００質量％の金属化合物微粒子では抵抗制御が不十分である。そこで本発明では、直接注入帯電速度が速く、色味も淡色で適正な抵抗制御が可能な、還元処理型酸化スズを金属化合物微粒子として用いることがより好ましい。
【００９７】
金属化合物微粒子に適正な表面処理を施して使用することは、高温高湿環境下での特性を改良する上から好ましい。金属化合物微粒子が吸湿すると、▲１▼トナーの摩擦帯電特性改良効果が著しく低下し、画質が低下する、▲２▼帯電部材から脱離しやすく、帯電性改良効果が低減する、などの問題が起こりやすい。そういう意味で、疎水化処理の処理剤としてはシラン化合物が撥水性が高く好ましい。疎水化処理に使用されるシラン化合物としては、例えば無機微粒子の表面処理に用いられるようなヘキサメチルジシラザン、トリメチルシラン、トリメチルクロルシラン、トリメチルエトキシシラン、ジメチルジクロルシラン、メチルトリクロルシラン、アリルジメチルクロルシラン、アリルフェニルジクロルシラン、ベンジルジメチルクロルシラン、ブロムメチルジメチルクロルシラン、α−クロルエチルトリクロルシラン、β−クロルエチルトリクロルシラン、クロルメチルジメチルクロルシラン、トリオルガノシランメルカプタン、トリメチルシリルメルカプタン、トリオルガノシリルアクリレート、ビニルジメチルアセトキシシラン、ジメチルエトキシシラン、ジメチルジメトキシシラン、ジフェニルジエトキシシラン、ヘキサメチルジシロキサン、１，３−ジビニルテトラメチルジシロキサン、１，３−ジフェニルテトラメチルジシロキサン、ビニルトリメトキシシランが挙げられる。
【００９８】
また、使用されるシリコーンオイルとしては、例えばジメチルシリコーンオイル、メチルフェニルシリコーンオイル、α−メチルスチレン変性シリコーンオイル、クロルフェニルシリコーンオイル、フッ素変性シリコーンオイル、アミノ変性シリコーンオイル等が特に好ましい。
【００９９】
これらの表面処理剤を酸化スズに塗布後、温度、もしくは機械的な処理を施して、酸化スズ表面に処理剤を強固に付着させることがより好ましい。
【０１００】
本発明に係る導電性微粒子は、凝集度が７０％以下であることが好ましい。本発明に使用する導電性微粒子はトナー表面にある程度遊離した状態で存在させることが重要となる。そのため、導電性微粒子は単独で像担持体に飛翔し、帯電部材まで搬送され、像担持体とトナーの再帯電を行う。このとき、帯電ローラーに担持されたトナーと導電性微粒子は回収シークエンスにより帯電ローラーから像担持体上に吐き出され、現像担持体での回収が行われる。このとき、導電性微粒子の凝集性が７０％より高い場合、トナー全体の凝集度を高めてしまい、トナー凝集体の塊が大きくなる。この結果、像担持体上に吐き出されたトナー塊が大きいため、レーザー露光時に凝集塊が存在する部分は像担持体上に潜像を書くことが出来ないため、白い粒状の画像抜けが発生する。これを遮光という。このとき、連続で印字させた場合は、特に転写残のトナーが帯電ローラーに蓄積されやすいため顕著に現れる。導電性微粒子の凝集度が６０％以下の場合、吐き出されたトナーは凝集しにくく、分散した状態で像担持体上に存在するため、レーザー露光時に均一に潜像を書くことが出来、白抜け（遮光）の無い良好な画像を得ることができる。
【０１０１】
導電性微粒子の凝集度の測定方法は、トナーのＣａｒｒの噴流性指数の中の凝集度の測定に準ずる。
【０１０２】
本発明に使用するプロセスカートリッジは、トナーを収容するトナー容器の空間が、像担持体に近い側で且つ静電潜像を前記トナーによりトナー画像を形成する現像手段が配置された第１の空間と、像担持体から遠い側の第２の空間に分割され、該第１の空間と第２の空間との境界に、その一端部側が前記第１の空間側に揺動可能な弁部材を有することを特徴とする。
【０１０３】
ここで、図により本発明に係る現像装置、画像形成装置及びプロセスカートリッジの一実施形態を具体的に説明する。図１は本発明に係る現像装置を装備するプロセスカートリッジを装着した画像形成装置の実施形態の一つの例である構成を示す概略側面図、図２は図１での実施形態の現像装置の構成を示す断面説明図、図３は図１での実施形態の現像装置において、第１の空間側から見た弁部材の動きを示す図、図４は第１実施形態の現像装置において、弁部材の動きを説明する図である。
【０１０４】
先ず、図１〜図４を用いて本発明に係る現像装置、画像形成装置及びプロセスカートリッジの第１実施形態の構成について説明する。図１において、１は像担持体としての電子写真感光体ドラムであり、外径直径３０ｍｍで、その表面にＯＰＣ（オーガニックフォトコンダクタ；有機光電導性感光体；ネガ感光体）が設けられており、図示しない駆動手段により図１の時計回り方向に５０ｍｍ／ｓｅｃの周速度（プロセススピード）で回転駆動される。
【０１０５】
帯電ローラ２の材質としては、弾性発泡体に限定するものではなく、弾性体の材料として、ＥＰＤＭ（エチレン−プロピレン−ジエン三元共重合体）、ウレタン、ＮＢＲ（ニトリルブタジエンゴム）、シリコーンゴムや、ＩＲ（分散型赤外分光光度計）等に抵抗調整のためにカーボンブラックや金属酸化物等の導電性物質を分散したゴム材や、またこれらを発泡させたものがあげられる。また、特に導電性物質を分散せずに、イオン導電性の材料を用いて抵抗調整をすることも可能である。
【０１０６】
帯電ローラ２は、被帯電体としての感光体ドラム１に対して弾性に抗して所定の押圧力で圧接させて配設してある。ｎは感光体ドラム１と帯電ローラ２との当接部である帯電当接部である。本実施形態では、帯電ローラ２を帯電当接部ｎにおいて該帯電ローラ２の表面と感光体ドラム１の表面とを互いに逆方向（カウンタ方向）に移動するように図１の時計回り方向に周速７５ｍｍ／ｓｅｃで回転駆動させた。
【０１０７】
即ち、接触帯電部材としての帯電ローラ２の表面は被帯電体としての感光体ドラム１の表面に対して速度差を持たせるようにした。
【０１０８】
帯電ローラ２により帯電された像担持体となる感光体ドラム１の帯電面に静電潜像を形成する画像情報書き込み手段となるレーザダイオード、ポリゴンミラー等を含む図示しないレーザビームスキャナ（露光器）は、目的の画像情報の時系列電気ディジタル画素信号に対応して強度変調されたレーザ光Ｌを出力し、該レーザ光Ｌで回転駆動される感光体ドラム１の一様帯電面を走査露光する。この走査露光Ｌにより回転駆動される感光体ドラム１の表面に、目的の画像情報に対応した静電潜像が形成される。
【０１０９】
４は現像装置であり、回転駆動される感光体ドラム１の表面の静電潜像は、この現像装置４によりトナーｔ（トナー粒子＋無機微粒子）及び導電性微粒子ｍを含むトナー４ｄを供給してトナー画像として可視像化して現像される。本実施形態の現像装置４は磁性一成分絶縁トナー（ネガトナー）を用いた反転現像装置である。現像手段となるトナー担持搬送部材としての非磁性回転現像スリーブ４ａは、その内部にマグネットロール４ｂを内包しており、この現像スリーブ４ａに規制ブレード４ｃでトナー４ｄが薄層にコートされる。
【０１１０】
トナー４ｄは規制ブレード４ｃで現像スリーブ４ａに対する層厚が規制され、また電荷が付与される。現像スリーブ４ａにコートされたトナー４ｄは現像スリーブ４ａの回転により、感光体ドラム１と現像スリーブ４ａの対向部である現像部（現像領域部）に搬送される。
【０１１１】
これにより、感光体ドラム１側の静電潜像がトナー４ｄで現像される。
【０１１２】
図１において、５は接触転写手段としての中抵抗の転写ローラであり、感光体ドラム１に所定の圧力で圧接させて転写当接部Ｂを形成させてある。この転写当接部Ｂに図示しない給送部から所定のタイミングで記録媒体としての転写材Ｐが給送され、且つ転写ローラ５に転写バイアス印加電源Ｓ３から所定の転写バイアス電圧が印加されることで、感光体ドラム１側のトナー画像が転写当接部Ｂに給送された転写材Ｐの面に順次転写されていく。
【０１１３】
即ち、転写当接部Ｂに導入された転写材Ｐは、この転写当接部Ｂを挟持搬送されて、その表面側に回転駆動される感光体ドラム１の表面に形成担持されているトナー画像が順次に静電気力と押圧力にて転写されていく。
【０１１４】
６は熱定着方式等の定着装置である。転写当接部Ｂに給送されて感光体ドラム１側のトナー画像の転写を受けた転写材Ｐは回転駆動される感光体ドラム１の表面から分離されて、この定着装置６に導入され、トナー画像の定着を受けて画像形成物（プリント、コピー）として装置外へ排出される。
【０１１５】
上述した本実施形態の画像形成装置のうち、像担持体となる感光体ドラム１、帯電手段となる帯電ローラ２及び現像装置４は、画像形成装置を構成するその他の部品（以下、「画像形成装置本体」という）とは独立した枠体内に一体的にまとめられてプロセスカートリッジを形成しており、画像形成装置本体に対して脱着可能に構成されている。
【０１１６】
本実施形態の画像形成装置はクリーニング手段を有さないクリーナレスであり、転写材Ｐに対するトナー画像転写後の感光体ドラム１の表面に未転写で残留した転写残トナー４ｄはクリーナで除去されることなく、感光体ドラム１の回転に伴い、帯電ローラ２を経由して現像部に至り、現像装置４において現像同時クリーニング（回収）されるトナーリサイクルプロセス方式で構成される。
【０１１７】
ところで、現像装置４のトナー４ｄに含有させた導電性を有する導電性微粒子ｍは、現像装置４による感光体ドラム１表面に形成された静電潜像のトナー現像時に適当量が感光体ドラム１側に移行する。
【０１１８】
感光体ドラム１上のトナー画像は、転写当接部８において転写バイアス電圧の影響で転写材Ｐ側に引かれて積極的に転移するが、感光体ドラム１上の導電性微粒子ｍは、導電性であることから転写材Ｐ側には積極的には転移せず、感光体ドラム１上に実質的に付着保持されて残留する。
【０１１９】
そして、トナーリサイクルプロセスの画像形成装置はクリーナを用いないため、転写後の感光体ドラム１の表面に残存する転写残トナーｔ及び導電性微粒子ｍは該感光体ドラム１と接触帯電部材である帯電ローラ２との帯電当接部ｎに感光体ドラム１の回転でそのまま持ち運ばれて帯電ローラ２に付着・混入する。
【０１２０】
従って、感光体ドラム１と帯電ローラ２との帯電当接部ｎに、この導電性微粒子ｍが持ち運ばれて介在（存在）した状態で、帯電バイアス印加電源Ｓ１により帯電ローラ２に帯電バイアス電圧が印加されて感光体ドラム１の接触帯電が行なわれる。
【０１２１】
尚、印字初期においては帯電ローラ２の表面に導電性微粒子ｍが供給されず、帯電が行えないので該帯電ローラ２の表面には予め導電性微粒子ｍを塗布しておく必要がある。
【０１２２】
この導電性微粒子ｍの存在により帯電ローラ２にトナー４ｄが付着・混入した場合でも該帯電ローラ２の感光体ドラム１への緻密な接触性と接触抵抗を維持出来るため接触帯電部材が帯電ローラ２のような簡易な部材であり、しかも帯電ローラ２の転写残トナー４ｄによる汚染にかかわらず該帯電ローラ２による感光体ドラム１の直接注入帯電を行わせることが出来る。
【０１２３】
つまり、帯電ローラ２が導電性微粒子ｍを介して密に感光体ドラム１に接触して該帯電ローラ２と感光体ドラム１との帯電当接部ｎに存在する導電性微粒子ｍが感光体ドラム１の表面を隙間なく摺擦することで、該帯電ローラ２による感光体ドラム１の帯電は導電性微粒子ｍの存在により放電現象を用いない安定且つ安全な直接注入帯電が支配的となり、従来のローラ帯電等では得られなかった高い帯電効率が得られ、帯電ローラ２に印加した電圧と略同等の電位を感光体ドラム１に与えることが出来る。
【０１２４】
また、帯電ローラ２に付着・混入した転写残トナー４ｄは、帯電ローラ２から徐々に感光体ドラム１上に吐き出されて該感光体ドラム１の表面の移動と共に現像スリーブ４ａが対向する現像部に至り、現像装置４において現像同時クリーニング（回収）されるトナーリサイクルプロセスが行なわれる。
【０１２５】
現像同時クリーニングは、前述したように、転写後に感光体ドラム１上に残留したトナー４ｄを、後続する画像形成工程の現像時、即ち引き続き感光体ドラム１を帯電し、露光して潜像を形成し、その潜像の現像時において、現像装置４のカブリ取りバイアス、即ち現像装置４に印加する直流電圧と感光体ドラム１の表面電位間の電位差であるカブリ取り電位差Ｖ_backによって回収するものである。
【０１２６】
本実施形態における画像形成装置のように反転現像の場合では、この現像同時クリーニングは、感光体ドラム１の暗部電位から現像スリーブ４ａにトナー４ｄを回収する電界と、現像スリーブ４ａから感光体ドラム１の明部電位へトナー４ｄを付着させる電界の作用でなされる。
【０１２７】
また、帯電ローラ２から導電性微粒子ｍが脱落しても、画像形成装置が稼働されることで、現像装置４のトナー４ｄに含有させてある導電性微粒子ｍが現像部で感光体ドラム１の表面に移行し、該感光体ドラム１の回転により転写当接部８を経て帯電ローラ２が対向する帯電部に持ち運ばれて該帯電ローラ２に逐次に供給され続けるため導電性微粒子ｍの存在による良好な帯電性が安定して維持される。
【０１２８】
このように、接触帯電方式、接触転写方式、トナーリサイクルプロセスの画像形成装置において、接触帯電部材として帯電ローラ２を用いて、しかも該帯電ローラ２の転写残トナー４ｄによる汚染にかかわらず、低印加電圧でオゾンレスの直接注入帯電を長期に渡り安定に維持させることが出来、均一な帯電性を与えることが出来、オゾン生成物による障害、帯電不良による障害等のない、簡易な構成で低コストな画像形成装置を得ることが出来る。
【０１２９】
本実施形態で使用する現像剤４ｄはトナーｔ及び導電性粒子ｍを一定割合で混合したものであるが、画像形成を行う際の印字比率によりトナーｔと導電性粒子ｍの消費のされ方が異なる。
【０１３０】
例えば、低印字率の場合には導電性粒子ｍが消費され易い。しかしながら、導電性粒子ｍが先行消費されてしまうとトナーｔがまだ残っているにもかかわらず帯電性能が低下し、画像不良が発生してしまう。
【０１３１】
この導電性粒子ｍの先行消費を防ぐためには現像剤４ｄを少量づつ現像剤担持体となる現像スリーブ４ａに搬送し、一旦、現像剤担持体である現像スリーブ４ａ付近に搬送した現像剤４ｄを元に戻さないようにすれば良い。
【０１３２】
また、本実施形態のようなクリーナレスの電子写真プロセスでは、転写残トナーｔとして現像領域に戻ってきた現像剤４ｄを現像装置４で回収するが、この回収した現像剤４ｄは劣化している可能性が高く、現像剤容器７内にある、まだ画像形成に使用していない新鮮なトナーｔとの混合をなるべく避けることが好ましい。
【０１３３】
本実施形態では、現像装置４の現像剤容器７の第２の空間１１から第１の空間１０への現像剤４ｄの移動のみを可能とすることにより、導電性粒子ｍの先行消費を防止し、画像不良のない画像形成装置及びプロセスカートリッジを提供することが出来るものである。
【０１３４】
本実施形態で用いている現像剤４ｄはトナーｔに対し導電性粒子ｍを一定割合で混合したものであるが、上述したように画像形成時の印字比率によりトナーｔと導電性粒子ｍの消費のされ方が異なるので、例えば導電性粒子ｍが先行消費されてしまうと、トナーｔがまだ残っているにもかかわらず帯電性能が低下し、画像不良が発生してしまう。
【０１３５】
プロセスカートリッジにおいてはトナーｔが残っているのにプロセスカートリッジの寿命が尽きてしまうというのは誠に不都合である。この導電性粒子ｍの先行消費を防ぐためには、現像剤４ｄを少量づつ現像スリーブ４ａに搬送し、一旦現像スリーブ４ａの付近に搬送した現像剤４ｄを現像スリーブ４ａの近傍の第１の空間１０内に留めるようにすれば良い。
【０１３６】
本実施形態ではその具体的な実現方法として第１の空間１０と第２の空間１１との境界に弁部材９を用いている。
【０１３７】
ここで、弁構成について詳しく説明する。本実施形態で用いた弁部材９は薄い樹脂のフィルムＰＥＴ（ポリエチレンテレフタレート）である。厚みは好ましくは１００μｍ以下、より好ましくは８０μｍ以下を使用する。
【０１３８】
弁部材９は図３・６に示すように、該弁部材９の長手方向の上部９ａを、第１の空間１０と第２の空間１１との間に設けた開口部３を有する仕切り壁７ａに取り付け、下方はフリーにして第１の空間１０側へのみ揺動し得るように構成されている。
【０１３９】
該弁部材９は、図２〜６に示すように、長手方向の上端部９ａを、７ａの第一の空間側１０と第２の空間側１１のどちらに支持しても良い。これは、弁部材の厚み、撹拌部材の厚み、撹拌スピード、撹拌翼の、第一の空間側への侵入量などにより適宜変更してよい。
【０１４０】
上記構成により、第２の空間１１から第一の空間１０へのトナーの移動空間への揺動がスムーズに行われ、第１の空間から第２の空間にトナーが逆流するのを抑制することができる。
【０１４１】
第１の空間１０に余裕があるときには、現像剤容器７の第２の空間１１内の現像剤４ｄを搬送、攪拌する搬送攪拌手段となる攪拌部材１２の押圧により図４（ａ）に示すように弁部材９が第１の空間１０側に揺動し、第２の空間１１から第１の空間１０へ現像剤４ｄが移動する。
【０１４２】
一方、第１の空間１０に余裕がないときには、図４（ｂ）に示すように弁部材９が第１の空間１０側へ動かず、従って現像剤４ｄも移動しない。更に、第２の空間１１から第１の空間１０へ現像剤４ｄが移動すると、一時的に第１の空間１０内の現像剤４ｄの密度が高まり、現像スリーブ４ａの回転によって第１の空間１０内で図４（ｃ）中の矢線で示したような現像剤４ｄの循環が起きると共に、第２の空間１１へ現像剤４ｄを押し戻そうとする力が生じる。
【０１４３】
すると、図４（ｄ）に示すように、弁部材９が第１の空間１０から第２の空間１１への現像剤４ｄの移動を妨げる方向に揺動し、第１の空間１０と第２の空間１１との現像剤４ｄの移動通路である開口部３をふさいでしまうので、第１の空間１０から第２の空間１１へ現像剤４ｄが移動するのを防止出来る。
【０１４４】
このときに、開口部３の開口幅は２０ｍｍ以下であることが好ましい。このときのより好ましい範囲は１０ｍｍ以下である。
【０１４５】
開口部が２０ｍｍよりも大きい場合、弁部材の揺動長が長すぎるため、弁開口時の開口幅も大きくなり、弁開口時にトナーが第一の空間１０から第２の空間１１へ逆流しやすくなる。また、トナーの少量補給が困難となり、長期耐久後半においてカブリ・遮光等の弊害が生じる。
【０１４６】
開口部３の開口幅が２０ｍｍ以下、特に好ましくは１０ｍｍ以下である場合に、トナーの逆流を生じず、またトナーの安定少量補給が可能となる。その結果、長期耐久においてカブリ・遮光の悪化を生じることなく良好な画像を得ることができる。
【０１４７】
尚、弁部材９は、攪拌部材１２の先端が弁部材９に接触して所定の侵入量を持たせて揺動させる方式でも良いし、弁部材９と攪拌部材１２とは直接接触せず、攪拌部材１２によって押し出された現像剤４ｄによって間接的に弁部材９を押して揺動させる方式でも良い。
【０１４８】
本発明において、無機微粒子は、トナー粒子の表面に付着させることでトナーの流動性を改良し、トナー粒子を均一に帯電させるために添加されるのみでなく、導電性微粒子をトナー中でトナー粒子に対して均一に分散させ、像担持体上に均一に導電性微粒子を供給せしめる効果も併せ持つ。
【０１４９】
本発明において無機微粒子の一次粒子の個数平均粒径の測定は、以下のように行うことができる。すなわち、走査型電子顕微鏡により拡大撮影したトナーの写真と、更に走査型電子顕微鏡に付属させたＸ線マイクロアナライザー（ＸＭＡ）等の元素分析手段によって無機微粒子の含有する元素でマッピングされたトナーの写真を対照し、トナー粒子表面に付着或いは遊離して存在している無機微粒子の一次粒子を１００個以上測定し、個数平均粒径を求めることができる。
【０１５０】
また本発明において無機微粒子は、一次粒子の個数平均粒径４〜８０ｎｍのシリカ、チタニア（酸化チタン）及びアルミナから選ばれる少なくとも一種を含有することが好ましい。例えば、シリカ微粒子としてはケイ素ハロゲン化物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-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ケイ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。
【０１５１】
また本発明において無機微粒子は、疎水化処理されたものであることが好ましい。無機微粒子を疎水化処理することによって、無機微粒子の高湿環境における帯電性の低下を防止し、無機微粒子が表面に付着したトナー粒子の摩擦帯電量の環境安定性を向上させることで、トナーとしての画像濃度、カブリ等の現像特性の環境安定性をより高めることができる。環境による無機微粒子の帯電性及び無機微粒子が表面に付着したトナー粒子の帯電量の変動を抑制することで、導電性微粒子のトナー粒子からの遊離し易さが変動することを防止でき、環境による導電性微粒子の像担持体上への供給量を安定化し、像担持体帯電性及び転写残トナー粒子回収性の環境安定性を高めることができる。
【０１５２】
疎水化処理の処理剤としては、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、シラン化合物、シランカップリング剤、その他有機ケイ素化合物、有機チタン化合物の如き処理剤を単独で或いは併用して処理しても良い。その中でも、無機微粒子は少なくともシリコーンオイルで処理されたものであることが特に好ましい。処理は公知の方法に従って行うことができる。
【０１５３】
疎水化処理に使用されるシラン化合物としては、例えばヘキサメチルジシラザン、トリメチルシラン、トリメチルクロルシラン、トリメチルエトキシシラン、ジメチルジクロルシラン、メチルトリクロルシラン、アリルジメチルクロルシラン、アリルフェニルジクロルシラン、ベンジルジメチルクロルシラン、ブロムメチルジメチルクロルシラン、α−クロルエチルトリクロルシラン、β−クロルエチルトリクロルシラン、クロルメチルジメチルクロルシラン、トリオルガノシランメルカプタン、トリメチルシリルメルカプタン、トリオルガノシリルアクリレート、ビニルジメチルアセトキシシラン、ジメチルエトキシシラン、ジメチルジメトキシシラン、ジフェニルジエトキシシラン、ヘキサメチルジシロキサン、１，３−ジビニルテトラメチルジシロキサン、１，３−ジフェニルテトラメチルジシロキサンが挙げられる。
【０１５４】
上記シリコーンオイルは、２５℃における粘度が１０〜２００，０００ｍｍ²／ｓのものが、さらには３，０００〜８０，０００ｍｍ²／ｓのものが好ましい。シリコーンオイルの粘度が上記範囲よりも小さすぎる場合には、無機微粒子の処理に安定性がなく、熱及び機械的な応力により、処理したシリコーンオイルが脱離、転移或いは劣化して画質が劣化する傾向がある。また、粘度が上記範囲よりも大きすぎる場合には、無機微粒子の均一な処理が困難になる傾向がある。
【０１５５】
使用されるシリコーンオイルとしては、例えばジメチルシリコーンオイル、メチルフェニルシリコーンオイル、α−メチルスチレン変性シリコーンオイル、クロルフェニルシリコーンオイル、フッ素変性シリコーンオイル等が特に好ましい。
【０１５６】
シリコーンオイルの処理の方法としては、例えばシラン化合物で処理された無機微粒子とシリコーンオイルとをヘンシェルミキサー等の混合機を用いて直接混合してもよいし、無機微粒子にシリコーンオイルを噴霧する方法を用いてもよい。あるいは適当な溶剤にシリコーンオイルを溶解あるいは分散せしめた後、シリカ微粉体を加え混合し溶剤を除去する方法でもよい。無機微粒子の凝集体の生成が比較的少ない点で噴霧機を用いる方法がより好ましい。
【０１５７】
シリコーンオイルの処理量は無機微粒子１００質量部に対し１〜２３質量部、好ましくは５〜２０質量部が良い。シリコーンオイルの量が上記範囲よりも少なすぎると良好な疎水性が得られず、多すぎるとカブリ発生等の不具合が生ずることがある。
【０１５８】
また本発明において無機微粒子は、少なくともシラン化合物で処理されると同時に、又はその後にシリコーンオイルで処理されたものであることが好ましい。無機微粒子の処理にシラン化合物を用いることが、シリコーンオイルの無機微粒子への付着性を高めて、無機微粒子の疎水性及び帯電性を均一化する上で特に好ましい。
【０１５９】
無機微粒子の処理条件としては、例えば第一段反応としてシリル化反応を行いシラノール基を化学結合により消失させた後、第二段反応としてシリコーンオイルにより表面に疎水性の薄膜を形成することが挙げられる。
【０１６０】
また、本発明のトナーは、無機微粒子の含有量がトナー全体の０．１〜３．０質量％であることが好ましい。無機微粒子の含有量が上記範囲より少なすぎる場合には、無機微粒子を添加することの効果が十分に得られず、また上記範囲より多すぎる場合には、トナー粒子に対して過剰な無機微粒子が導電性微粒子を被覆してしまい、導電性微粒子の抵抗が高い場合と同様な挙動を示すようになり、像担持体上への導電性微粒子の供給性の低下、像担持体の帯電促進効果の低下、転写残トナーの回収性の低下等、の本発明の効果を損なうようになる傾向がある。無機微粒子の含有量は、トナー全体の０．３〜２．０質量％であることがより好ましく、さらに好ましくは０．５〜１．５質量％である。
【０１６１】
本発明で用いられる一次粒子の個数平均粒径が４〜８０ｎｍの無機微粒子は、ＢＥＴ法で測定した窒素吸着による比表面積が４０〜３００ｍ²／ｇの範囲内のものが好ましく、６０〜２５０ｍ²／ｇのものがより好ましい。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多点法を用いて算出することができる。
【０１６２】
以上のように、本発明において、トナーの噴流性指数と、トナーに添加された無機微粒子と導電性微粒子のトナーからの遊離率を制御したトナーを、トナーの供給状態を制御できる構成のプロセスカートリッジで使用することで、導電性微粒子が高い遊離率を保った状態でどのような環境下でもトナーがフラッシングしやすく、弁開口時でのトナーの供給がスムーズに行われる。その結果、高温高湿環境で長期耐久しても、高い流動性と高い遊離率を保ったままトナー供給が行われるため、フェーディングを起こしにくく、また耐久後半でもトナーの再帯電・回収がスムーズに行われるため、帯電性の悪化・遮光の悪化を起こさず、耐久を通して良好な画像を形成することができる。
【０１６３】
本発明のトナーについて更に説明する。
【０１６４】
本発明のトナーに係る樹脂組成物は、保存性の観点から、ガラス転移温度（Ｔｇ）が４５〜８０℃、好ましくは５０〜７０℃であり、Ｔｇが４５℃より低いと高温雰囲気下でのトナーの劣化や定着時でのオフセットの原因となる。また、Ｔｇが８０℃を超えると、定着性が低下する傾向にある。
【０１６５】
本発明の樹脂のガラス転移温度を測定する方法として、示差熱分析測定装置（ＤＳＣ測定装置）、ＤＳＣ−７（パーキンエルマー社製）や、ＥＸＳＴＡＲ６０００、ＳＳＣ／５２００（セイコーインスツルメンツ社製）、ＤＳＣ２９２０ＭＤＳＣ（ＴＡインスツルメンツ社製）等を用い、下記の条件にて測定することができる。
【０１６６】

【０１６７】
本発明に用いる結着樹脂成分は、ＴＨＦ可溶成分のＧＰＣにより測定される分子量において、Ｍｎ（数平均分子量）が３０００〜２００００、また、Ｍｗ（重量平均分子量）が５０，０００〜５００，０００の範囲であることが好ましい。この範囲内であれば定着性と耐久性のバランスが非常に良い。
【０１６８】
これらの結着樹脂成分は、トナーの製造に際し、予めワックス成分を混合、分散させておくこともできる。予めワックス成分を混合しておくことで、ミクロ領域での相分離が緩和され、良好な分散状態が得られる。
【０１６９】
本発明において、トナー又は結着樹脂の、ＴＨＦ（テトラハイドロフラン）を溶媒としたＧＰＣによる分子量分布は次の条件で測定される。
【０１７０】
４０℃のヒートチャンバ中でカラムを安定化させ、この温度におけるカラムに、溶媒としてＴＨＦを毎分１ｍｌの流速で流し、試料のＴＨＦ溶液を約１００μｌ注入して測定する。試料の分子量測定にあたっては、試料の有する分子量分布を、数種の単分散ポリスチレン標準試料により作成された検量線の対数値とカウント数との関係から算出する。検量線作成用の標準ポリスチレン試料としては、例えば東ソー社製、或いは昭和電工社製の分子量が１０²〜１０⁷程度のものを用い、少なくとも１０点程度の標準ポリスチレン試料を用いるのが適当である。検出器にはＲＩ（屈折率）検出器を用いる。カラムとしては、市販のポリスチレンジェルカラムを複数本組み合わせるのが良い。例えば昭和電工社製のｓｈｏｄｅｘ ＧＰＣ ＫＦ−８０１，８０２，８０３，８０４，８０５，８０６，８０７，８００Ｐの組み合わせや、東ソー社製のＴＳＫｇｅｌＧ１０００Ｈ（Ｈ_XL），Ｇ２０００Ｈ（Ｈ_XL），Ｇ３０００Ｈ（Ｈ_XL），Ｇ４０００Ｈ（Ｈ_XL），Ｇ５０００Ｈ（Ｈ_XL），Ｇ６０００Ｈ（Ｈ_XL），Ｇ７０００Ｈ（Ｈ_XL），ＴＳＫｇｕａｒｄｃｏｌｕｍｎの組み合わせを挙げることができる。
【０１７１】
試料は以下のようにして作製する。
【０１７２】
試料をＴＨＦに入れ、数時間放置した後、十分振とうしＴＨＦとよく混ぜ（試料の合一体がなくなるまで）、更に１２時間以上静置する。このときＴＨＦ中への試料の放置時間が２４時間以上となるようにする。その後、サンプル処理フィルター（ポアサイズ０．４５〜０．５μｍ、例えばマイショリディスクＨ−２５−５ 東ソー社製、エキクロディスク２５ＣＲ ゲルマン サイエンス ジャパン社製等が利用できる）を通過させたものを、ＧＰＣの測定試料とする。試料濃度は、樹脂成分が０．５〜５ｍｇ／ｍｌとなるように調整する。
【０１７３】
本発明における結着樹脂の種類としては、スチレン系樹脂、スチレン系共重合樹脂、ポリエステル樹脂、ポリオール樹脂、ポリ塩化ビニル樹脂、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、ポリ酢酸ビニル、シリコーン樹脂、ポリウレタン樹脂、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、石油系樹脂が挙げられる。
【０１７４】
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、ビニルトルエンの如きスチレン誘導体、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の如きアクリル酸エステル；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の如きメタクリル酸エステル；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エステル；アクリルアミド、アクリロニトリル、メタクリロニトリル、ブタジエン；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；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；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；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が挙げられる。これらのビニル系単量体が単独もしくは２つ以上用いられる。
【０１７５】
本発明における結着樹脂は、１〜１００ｍｇＫＯＨ／ｇの範囲で酸価を有することが好ましい。とくに好ましくは１〜７０ｍｇＫＯＨ／ｇの酸価を有する樹脂である。７０ｍｇＫＯＨ／ｇより大きくなると、高湿下での摩擦帯電量が不十分となり、１ｍｇＫＯＨ／ｇより小さいと、低湿下での摩擦帯電速度が遅くなる。
【０１７６】
結着樹脂の酸価を調整するモノマーとしては、例えば、アクリル酸、メタクリル酸、α−エチルアクリル酸、クロトン酸、ケイヒ酸、ビニル酢酸、イソクロトン酸、アンゲリカ酸などのアクリル酸及びそのα−或いはβ−アルキル誘導体、フマル酸、マレイン酸、シトラコン酸、アルケニルコハク酸、イタコン酸、メサコン酸、ジメチルマレイン酸、ジメチルフマル酸などの不飽和ジカルボン酸及びそのモノエステル誘導体又は無水物などがあり、このようなモノマーを単独、或いは混合し、他のモノマーと共重合させることにより所望の重合体を作ることができる。この中でも、特に不飽和ジカルボン酸のモノエステル誘導体を用いることが酸価値をコントロールする上で好ましい。
【０１７７】
より具体的には、例えば、マレイン酸モノメチル、マレイン酸モノエチル、マレイン酸モノブチル、マレイン酸モノオクチル、マレイン酸モノアリル、マレイン酸モノフェニル、フマル酸モノメチル、フマル酸モノエチル、フマル酸モノブチル、フマル酸モノフェニルなどのようなα，β−不飽和ジカルボン酸のモノエステル類；ｎ−ブテニルコハク酸モノブチル、ｎ−オクテニルコハク酸モノメチル、ｎ−ブテニルマロン酸モノエチル、ｎ−ドデセニルグルタル酸モノメチル、ｎ−ブテニルアジピン酸モノブチルなどのようなアルケニルジカルボン酸のモノエステル類などが挙げられる。
【０１７８】
以上のようなカルボキシル基含有モノマーは、結着樹脂を構成している全モノマー１００質量部に対し０．１〜２０質量部、好ましくは０．２〜１５質量部添加すればよい。
【０１７９】
本発明の結着樹脂の合成方法として本発明に用いることの出来る重合法として、溶液重合法、乳化重合法や懸濁重合法が挙げられる。
【０１８０】
このうち、乳化重合法は、水にほとんど不溶の単量体（モノマー）を乳化剤で小さい粒子として水相中に分散させ、水溶性の重合開始剤を用いて重合を行う方法である。この方法では反応熱の調節が容易であり、重合の行われる相（重合体と単量体からなる油相）と水相とが別であるから停止反応速度が小さく、その結果重合速度が大きく、高重合度のものが得られる。更に、重合プロセスが比較的簡単であること、及び重合生成物が微細粒子であるために、トナーの製造において、着色剤及び荷電制御剤その他の添加物との混合が容易であること等の理由から、トナー用バインダー樹脂の製造方法として有利な点がある。
【０１８１】
しかし、添加した乳化剤のため生成重合体が不純になり易く、重合体を取り出すには塩析などの操作が必要で、この不便を避けるためには懸濁重合が好都合である。
【０１８２】
懸濁重合においては、水系溶媒１００質量部に対して、モノマー１００質量部以下（好ましくは１０〜９０質量部）で行うのが良い。使用可能な分散剤としては、ポリビニルアルコール、ポリビニルアルコール部分ケン化物、リン酸カルシウム等が用いられ、一般に水系溶媒１００質量部に対して０．０５〜１質量部で用いられる。重合温度は５０〜９５℃が適当であるが、使用する開始剤、目的とするポリマーによって適宜選択される。
【０１８３】
本発明に用いられる結着樹脂は、以下に例示する様な多官能性重合開始剤単独あるいは単官能性重合開始剤と併用して生成することが好ましい。
【０１８４】
多官能構造を有する多官能性重合開始剤の具体例としては、１，１−ジ−ｔ−ブチルパーオキシ−３，３，５−トリメチルシクロヘキサン、１，３−ビス−（ｔ−ブチルパーオキシイソプロピル）ベンゼン、２，５−ジメチル−２，５−（ｔ−ブチルパーオキシ）ヘキサン、２，５−ジメチル−２，５−ジ−（ｔ−ブチルパーオキシ）ヘキサン、トリス−（ｔ−ブチルパーオキシ）トリアジン、１，１−ジ−ｔ−ブチルパーオキシシクロヘキサン、２，２−ジ−ｔ−ブチルパーオキシブタン、４，４−ジ−ｔ−ブチルパーオキシバレリックアシッド−ｎ−ブチルエステル、ジ−ｔ−ブチルパーオキシヘキサハイドロテレフタレート、ジ−ｔ−ブチルパーオキシアゼレート、ジ−ｔ−ブチルパーオキシトリメチルアジペート、２，２−ビス−（４，４−ジ−ｔ−ブチルパーオキシシクロヘキシル）プロパン、２，２−ｔ−ブチルパーオキシオクタン及び各種ポリマーオキサイド等の１分子内に２つ以上のパーオキサイド基などの重合開始機能を有する官能基を有する多官能性重合開始剤、及びジアリルパーオキシジカーボネート、ｔ−ブチルパーオキシマレイン酸、ｔ−ブチルパーオキシアリルカーボネート及びｔ−ブチルパーオキシイソプロピルフマレート等の１分子内に、パーオキサイド基などの重合開始機能を有する官能基と重合性不飽和基の両方を有する多官能性重合開始剤から選択される。
【０１８５】
これらの内、より好ましいものは、１，１−ジ−ｔ−ブチルパーオキシ−３，３，５−トリメチルシクロヘキサン、１，１−ジ−ｔ−ブチルパーオキシシクロヘキサン、ジ−ｔ−ブチルパーオキシヘキサハイドロテレフタレート、ジ−ｔ−ブチルパーオキシアゼレート及び２，２−ビス−（４，４−ジ−ｔ−ブチルパーオキシシクロヘキシル）プロパン、及びｔ−ブチルパーオキシアリルカーボネートである。
【０１８６】
これらの多官能性重合開始剤は、トナー用バインダーとして要求される種々の性能を満足する為には、単官能性重合開始剤と併用されることが好ましい。特に該多官能性重合開始剤の半減期１０時間を得る為の分解温度よりも低い半減期１０時間の分解温度を有する重合開始剤と併用することが好ましい。
【０１８７】
具体的には、ベンゾイルパーオキシド、１，１−ジ（ｔ−ブチルパーオキシ）−３，３，５−トリメチルシクロヘキサン、ｎ−ブチル−４，４−ジ（ｔ−ブチルパーオキシ）バレレート、ジクミルパーオキシド、α，α’−ビス（ｔ−ブチルパーオキシジイソプロピル）ベンゼン、ｔ−ブチルパーオキシクメン、ジ−ｔ−ブチルパーオキシド等の有機過酸化物、アゾビスイソブチロニトリル、ジアゾアミノアゾベンゼン等のアゾおよびジアゾ化合物等が挙げられる。
【０１８８】
これらの単官能性重合開始剤は、前記多官能性重合開始剤と同時にモノマー中に添加しても良いが、該多官能性重合開始剤の効率を適正に保つ為には、重合工程において該多官能性重合開始剤の示す半減期を経過した後に添加するのが好ましい。
【０１８９】
これらの開始剤は、効率の点からモノマー１００質量部に対し０．０５〜２質量部で用いるのが好ましい。
【０１９０】
結着樹脂は架橋性モノマーで架橋されていることも好ましい。
【０１９１】
架橋性モノマーとしては主として２個以上の重合可能な二重結合を有するモノマーが用いられる。具体例としては、芳香族ジビニル化合物（例えば、ジビニルベンゼン、ジビニルナフタレン等）；アルキル鎖で結ばれたジアクリレート化合物類（例えば、エチレングリコールジアクリレート、１，３−ブチレングリコールジアクリレート、１，４−ブタンジオールジアクリレート、１，５−ペンタンジオールジアクリレート、１，６−ヘキサンジオールジアクリレート、ネオペンチルグリコールジアクリレート、及び以上の化合物のアクリレートをメタクリレートに代えたもの）；エーテル結合を含むアルキル鎖で結ばれたジアクリレート化合物類（例えば、ジエチレングリコールジアクリレート、トリエチレングリコールジアクリレート、テトラエチレングリコールジアクリレート、ポリエチレングリコール＃４００ジアクリレート、ポリエチレングリコール＃６００ジアクリレート、ジプロピレングリコールジアクリレート、及び以上の化合物のアクリレートをメタクリレートに代えたもの）；芳香族基及びエーテル結合を含む鎖で結ばれたジアクリレート化合物類（例えば、ポリオキシエチレン（２）−２，２−ビス（４−ヒドロキシフェニル）プロパンジアクリレート、ポリオキシエチレン（４）−２，２−ビス（４−ヒドロキシフェニル）プロパンジアクリレート、及び、以上の化合物のアクリレートをメタクリレートに代えたもの）；更には、ポリエステル型ジアクリレート化合物類（例えば、商品名ＭＡＮＤＡ（日本化薬））が挙げられる。多官能の架橋剤としては、ペンタエリスリトールアクリレート、トリメチロールエタントリアクリレート、トリメチロールプロパントリアクリレート、テトラメチロールプロパントリアクリレート、テトラメチロールメタンテトラアクリレート、オリゴエステルアクリレート、及び以上の化合物のアクリレートをメタクリレートに代えたもの；トリアリルシアヌレート、トリアリルトリメリテート；等が挙げられる。
【０１９２】
これらの架橋剤は、他のモノマー成分１００質量部に対して、０．００００１〜１質量部、好ましくは０．００１〜０．０５質量部の範囲で用いることが好ましい。
【０１９３】
これらの架橋性モノマーのうち、トナーの定着性，耐オフセット性の点から好適に用いられるものとして、芳香族ジビニル化合物（特にジビニルベンゼン）、芳香族基及びエーテル結合を含む鎖で結ばれたジアクリレート化合物類が挙げられる。
【０１９４】
その他の合成方法としては、塊状重合方法、溶液重合方法を用いることができる。しかし、塊状重合法では、高温で重合させて停止反応速度を速めることで、低分子量の重合体を得ることができるが、反応をコントロールしにくい問題点がある。その点、溶液重合法は、溶媒によるラジカルの連鎖移動の差を利用して、また、開始剤量や反応温度を調整することで、所望の分子量の重合体を温和な条件で容易に得ることができるので好ましい。特に、開始剤使用量を最小限に抑え、開始剤が残留することによる影響を極力抑えるという点で、加圧条件下での溶液重合法も好ましい。
【０１９５】
本発明に用いられるポリエステル樹脂の組成は以下の通りである。
【０１９６】
２価のアルコール成分としては、エチレングリコール、プロピレングリコール、１，３−ブタンジオール、１，４−ブタンジオール、２，３−ブタンジオール、ジエチレングリコール、トリエチレングリコール、１，５−ペンタンジオール、１，６−ヘキサンジオール、ネオペンチルグリコール、２−エチル−１，３−ヘキサンジオール、水素化ビスフェノールＡ、また（Ｅ）式で表わされるビスフェノール及びその誘導体；
【０１９７】
【化１】

（式中、Ｒはエチレンまたはプロピレン基であり、ｘ，ｙはそれぞれ０以上の整数であり、かつ、ｘ＋ｙの平均値は０〜１０である。）
また（Ｆ）式で示されるジオール類；
【０１９８】
【化２】

【０１９９】
２価の酸成分としては、例えばフタル酸、テレフタル酸、イソフタル酸、無水フタル酸などのベンゼンジカルボン酸類又はその無水物、低級アルキルエステル；こはく酸、アジピン酸、セバシン酸、アゼライン酸などのアルキルジカルボン酸類又はその無水物、低級アルキルエステル；ｎ−ドデセニルコハク酸、ｎ−ドデシルコハク酸などのアルケニルコハク酸類もしくはアルキルコハク酸類、又はその無水物、低級アルキルエステル；フマル酸、マレイン酸、シトラコン酸、イタコン酸などの不飽和ジカルボン酸類又はその無水物、低級アルキルエステル；等のジカルボン酸類及びその誘導体が挙げられる。
【０２００】
また架橋成分として働く３価以上のアルコール成分と３価以上の酸成分を併用することが好ましい。
【０２０１】
３価以上の多価アルコール成分としては、例えばソルビトール、１，２，３，６−ヘキサンテトロール、１，４−ソルビタン、ペンタエリスリトール、ジペンタエリスリトール、トリペンタエリスリトール、１，２，４−ブタントリオール、１，２，５−ペンタントリオール、グリセロール、２−メチルプロパントリオール、２−メチル−１，２，４−ブタントリオール、トリメチロールエタン、トリメチロールプロパン、１，３，５−トリヒドロキシベンゼン等が挙げられる。
【０２０２】
また、本発明における三価以上の多価カルボン酸成分としては、例えばトリメリット酸、ピロメリット酸、１，２，４−ベンゼントリカルボン酸、１，２，５−ベンゼントリカルボン酸、２，５，７−ナフタレントリカルボン酸、１，２，４−ナフタレントリカルボン酸、１，２，４−ブタントリカルボン酸、１，２，５−ヘキサントリカルボン酸、１，３−ジカルボキシル−２−メチル−２−メチレンカルボキシプロパン、テトラ（メチレンカルボキシル）メタン、１，２，７，８−オクタンテトラカルボン酸、エンポール三量体酸、及びこれらの無水物、低級アルキルエステル；次式
【０２０３】
【化３】

（式中、Ｘは炭素数３以上の側鎖を１個以上有する炭素数５〜３０のアルキレン基又はアルケニレン基）
で表わされるテトラカルボン酸等、及びこれらの無水物、低級アルキルエステル等の多価カルボン酸類及びその誘導体が挙げられる。
【０２０４】
本発明に用いられるアルコール成分としては４０〜６０ｍｏｌ％、好ましくは４５〜５５ｍｏｌ％、酸成分としては６０〜４０ｍｏｌ％、好ましくは５５〜４５ｍｏｌ％であることが好ましい。また三価以上の多価の成分は、全成分中の５〜６０ｍｏｌ％であることが好ましい。
【０２０５】
該ポリエステル樹脂も通常一般に知られている縮重合によって得られる。
【０２０６】
本発明に用いられるワックスには次のようなものがある。例えば低分子量ポリエチレン、低分子量ポリプロピレン、ポリオレフィン共重合物、ポリオレフィンワックス、マイクロクリスタリンワックス、パラフィンワックス、フィッシャートロプシュワックスの如き脂肪族炭化水素系ワックス；酸化ポリエチレンワックスの如き脂肪族炭化水素系ワックスの酸化物；又は、それらのブロック共重合物；キャンデリラワックス、カルナバワックス、木ろう、ホホバろうの如き植物系ワックス；みつろう、ラノリン、鯨ろうの如き動物系ワックス；オゾケライト、セレシン、ペトロラクタムの如き鉱物系ワックス；モンタン酸エステルワックス、カスターワックスの如き脂肪族エステルを主成分とするワックス類；脱酸カルナバワックスの如き脂肪族エステルを一部又は全部を脱酸化したものが挙げられる。更に、パルミチン酸、ステアリン酸、モンタン酸、或いは更に長鎖のアルキル基を有する長鎖アルキルカルボン酸類の如き飽和直鎖脂肪酸；ブラシジン酸、エレオステアリン酸、バリナリン酸の如き不飽和脂肪酸；ステアリルアルコール、エイコシルアルコール、ベヘニルアルコール、カウナビルアルコール、セリルアルコール、メリシルアルコール、或いは更に長鎖のアルキル基を有するアルキルアルコールの如き飽和アルコール；ソルビトールの如き多価アルコール；リノール酸アミド、オレイン酸アミド、ラウリン酸アミドの如き脂肪族アミド；メチレンビスステアリン酸アミド、エチレンビスカプリン酸アミド、エチレンビスラウリン酸アミド、ヘキサメチレンビスステアリン酸アミドの如き飽和脂肪族ビスアミド；エチレンビスオレイン酸アミド、ヘキサメチレンビスオレイン酸アミド、Ｎ，Ｎ’−ジオレイルアジピン酸アミド、Ｎ，Ｎ’−ジオレイルセバシン酸アミドの如き不飽和脂肪酸アミド類；ｍ−キシレンビスステアリン酸アミド、Ｎ，Ｎ’−ジステアリルイソフタル酸アミドの如き芳香族系ビスアミド；ステアリン酸カルシウム、ラウリン酸カルシウム、ステアリン酸亜鉛、ステアリン酸マグネシウムの如き脂肪族金属塩（一般に金属石けんといわれているもの）；脂肪族炭化水素系ワックスにスチレンやアクリル酸の如きビニル系モノマーを用いてグラフト化させたワックス；ベヘニン酸モノグリセリドの如き脂肪酸と多価アルコールの部分エステル化物；植物性油脂を水素添加することによって得られるヒドロキシル基を有するメチルエステル化合物が挙げられる。
【０２０７】
また、これらのワックスを、プレス発汗法、溶剤法、再結晶法、真空蒸留法、超臨界ガス抽出法又は融液晶析法を用いて分子量分布をシャープにしたものや低分子量固形脂肪酸、低分子量固形アルコール、低分子量固形化合物、その他の不純物を除去したものも好ましく用いられる。
【０２０８】
本発明の着色剤としては磁性酸化鉄を用いても良く、その場合磁性トナーとして用いることができ、磁性酸化鉄としては、マグネタイト，マグヘマイト，フェライト等の酸化鉄が用いられ、その磁性酸化鉄表面あるいは内部に非鉄元素を含有するものが好ましい。
【０２０９】
本発明を磁性トナーとして適用する場合には、そこに使用される磁性酸化鉄は、鉄元素基準で異種元素を０．０５〜１０質量％含有することが好ましい。とくに好ましくは、０．１〜５質量％である。
【０２１０】
また、これら磁性酸化鉄は、結着樹脂１００質量部に対して２０〜２００質量部含有されていることが好ましい。更に好ましくは、５０〜１２０質量部含有されていることが好ましい。
【０２１１】
異種元素としては、マグネシウム、アルミニウム、ケイ素、リン、イオウから選択される元素であることが好ましい。また、以下の、リチウム，ベリリウム，ボロン，ゲルマニウム，チタン，ジルコニウム，錫，鉛，亜鉛，カルシウム，バリウム，スカンジウム，バナジウム，クロム，マンガン，コバルト，銅，ニッケル，ガリウム，カドミウム，インジウム，銀元素，パラジウム，金，水銀，白金，タングステン，モリブデン，ニオブ，オスミウム，ストロンチウム，イットリウム，テクネチウム等の金属も挙げられる。
【０２１２】
これらの磁性酸化鉄は個数平均粒径が０．０５〜１．０μｍが好ましく、更には０．１〜０．５μｍのものが好ましい。磁性酸化鉄はＢＥＴ比表面積は２〜４０ｍ²／ｇ（より好ましくは、４〜２０ｍ²／ｇ）のものが好ましく用いられる。形状には特に制限はなく、任意の形状のものが用いられる。磁気特性としては、磁場７９５．８ｋＡ／ｍ下で飽和磁化が１０〜２００Ａｍ²／ｋｇ（より好ましくは、７０〜１００Ａｍ²／ｋｇ）、残留磁化が１〜１００Ａｍ²／ｋｇ（より好ましくは、２〜２０Ａｍ²／ｋｇ）、抗磁力が１〜３０ｋＡ／ｍ（より好ましくは、２〜１５ｋＡ／ｍ）であるものが好ましく用いられる。
【０２１３】
また、本発明のトナーとして磁性トナーを用いる場合は該磁性トナーの密度が、１．３〜２．２ｇ／ｃｍ³であることが望ましい。更には、１．５〜２．０ｇ／ｃｍ³の範囲であることが好ましい。磁性トナーの質量（密度）は磁性トナー粒子に働く磁気力、静電気力、重力の作用に相関があり、磁性トナーの密度がこの範囲である場合、磁性酸化鉄の作用が適正であるため、帯電と磁気力とのバランスが良く、優れた現像力を示すことが出来る。
【０２１４】
また、磁性トナーの密度が１．３ｇ／ｃｍ³未満の場合、磁性トナーに対する磁性酸化鉄の作用が弱いため、磁気力が低くなる。このため、現像時に感光体ドラムへ飛翔するための静電気力が勝り、現像過多の状態となり、カブリや、消費量の増加につながる。反対に磁性トナー密度が２．２ｇ／ｃｍ³超である場合、磁性トナーに対する磁性酸化鉄の作用が強くなり磁気力が静電気力に勝るようになり、その強い磁気力作用が大きく比重も重くなるため、現像時にスリーブから飛翔しにくく、現像不足の状態となり、画像濃度薄や画像劣化につながる。
【０２１５】
また、場合により、本発明の磁性トナーに用いる磁性酸化鉄は、シランカップリング剤、チタンカップリング剤、チタネート、アミノシラン等で処理しても良い。
【０２１６】
本発明のトナーは荷電制御剤を含有することが好ましい。
【０２１７】
トナーを負荷電性に制御するものとして下記化合物が挙げられる。
【０２１８】
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の金属錯体が挙げられる。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、ビスフェノールのフェノール誘導体類が挙げられる。
【０２１９】
中でも、下記式（Ｉ）で表されるアゾ系金属錯体が好ましい。
【０２２０】
【化４】

〔式中、Ｍは配位中心金属を表し、Ｓｃ，Ｔｉ，Ｖ，Ｃｒ，Ｃｏ，Ｎｉ，Ｍｎ又はＦｅ等が挙げられる。Ａｒはアリール基であり、フェニル基、ナフチル基の如きアリール基であり、置換基を有してもよい。この場合の置換基としては、ニトロ基、ハロゲン基、カルボキシル基、アニリド基及び炭素数１〜１８のアルキル基、炭素数１〜１８のアルコキシ基がある。Ｘ，Ｘ’，Ｙ及びＹ’は−Ｏ−，−ＣＯ−，−ＮＨ−，−ＮＲ−（Ｒは炭素数１〜４のアルキル基）である。Ｃ⁺はカウンターイオンを示し、水素、ナトリウム、カリウム、アンモニウム、脂肪族アンモニウム或いはそれらの混合イオンを示す。〕
【０２２１】
特に中心金属としてはＦｅが好ましく、置換基としてはハロゲン、アルキル基又はアニリド基が好ましく、カウンターイオンとしては水素、アルカリ金属、アンモニウム又は脂肪族アンモニウムが好ましい。カウンターイオンの異なる錯塩の混合物も好ましく用いられる。
【０２２２】
トナーを正荷電性に制御するものとして下記の化合物がある。
【０２２３】
ニグロシン及び脂肪酸金属塩等によるニグロシン変成物；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など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の如き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、りんタングステン酸、りんモリブデン酸、りん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、フェロシアン化物など）；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の如き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の如きジオルガノスズボレート類；グアニジン化合物；イミダゾール化合物が挙げられる。これらを単独で或いは２種類以上組み合わせて用いることができる。これらの中でも、トリフェニルメタン化合物、カウンターイオンがハロゲンでない四級アンモニウム塩が好ましく用いられる。下記式（ＩＩ）
【０２２４】
【化５】

〔式中Ｒ₁はＨ又はＣＨ₃を示し、Ｒ₂及びＲ₃は置換または未置換のアルキル基（好ましくは、Ｃ１〜Ｃ４）を示す。〕
で表されるモノマーの単重合体；前述したスチレン、アクリル酸エステル、メタクリル酸エステルの如き重合性モノマーとの共重合体を正荷電性制御剤として用いることができる。この場合、この単重合体及び共重合体は荷電制御剤としての機能と、結着樹脂（の全部または一部）としての機能を有する。
【０２２５】
荷電制御剤をトナーに含有させる方法としては、トナー粒子内部に添加する方法と外添する方法がある。これらの荷電制御剤の使用量としては、結着樹脂の種類、他の添加剤の有無、分散方法を含めたトナー製造方法によって決定されるもので、一義的に限定されるものではないが、好ましくは結着樹脂１００質量部に対して０．１〜１０質量部、より好ましくは０．１〜５質量部の範囲で用いられる。
【０２２６】
本発明のトナーを製造する方法としては、上述したようなトナー構成材料をボールミルその他の混合機により十分混合した後、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よく混練し、冷却固化後、機械的に粉砕し、粉砕粉を分級することによってトナーを得る方法が好ましい。他には、結着樹脂を構成すべき単量体に所定の材料を混合して乳化懸濁液とした後に、重合させてトナーを得る重合法；コア材及びシェル材から成るいわゆるマイクロカプセルトナーにおいて、コア材あるいはシェル材、あるいはこれらの両方に所定の材料を含有させる方法；結着樹脂溶液中に構成材料を分散した後、噴霧乾燥することによりトナーを得る方法が挙げられる。更に必要に応じ所望の添加剤とトナー粒子とを混合機により前述した各種方法を用いて十分に混合し、本発明のトナーを製造することができる。
【０２２７】
例えば混合機としては、ヘンシェルミキサー（三井鉱山社製）；スーパーミキサー（カワタ社製）；リボコーン（大川原製作所社製）；ナウターミキサー、タービュライザー、サイクロミックス（ホソカワミクロン社製）；スパイラルピンミキサー（太平洋機工社製）；レーディゲミキサー（マツボー社製）が挙げられ、混練機としては、ＫＲＣニーダー（栗本鉄工所社製）；ブス・コ・ニーダー（Ｂｕｓｓ社製）；ＴＥＭ型押し出し機（東芝機械社製）；ＴＥＸ二軸混練機（日本製鋼所社製）；ＰＣＭ混練機（池貝鉄工所社製）；三本ロールミル、ミキシングロールミル、ニーダー（井上製作所社製）；ニーデックス（三井鉱山社製）；ＭＳ式加圧ニーダー、ニダールーダー（森山製作所社製）；バンバリーミキサー（神戸製鋼所社製）が挙げられ、粉砕機としては、カウンタージェットミル、ミクロンジェット、イノマイザ（ホソカワミクロン社製）；ＩＤＳ型ミル、ＰＪＭジェット粉砕機（日本ニューマチック工業社製）；クロスジェットミル（栗本鉄工所社製）；ウルマックス（日曹エンジニアリング社製）；ＳＫジェット・オー・ミル（セイシン企業社製）；クリプトロン（川崎重工業社製）；ターボミル（ターボ工業社製）が挙げられ、分級機としては、クラッシール、マイクロンクラッシファイアー、スペディッククラシファイアー（セイシン企業社製）；ターボクラッシファイアー（日清エンジニアリング社製）；ミクロンセパレータ、ターボプレックス（ＡＴＰ）、ＴＳＰセパレータ（ホソカワミクロン社製）；エルボージェット（日鉄鉱業社製）、ディスパージョンセパレータ（日本ニューマチック工業社製）；ＹＭマイクロカット（安川商事社製）が挙げられ、粗粒などをふるい分けるために用いられる篩い装置としては、ウルトラソニック（晃栄産業社製）；レゾナシーブ、ジャイロシフター（徳寿工作所社製）；バイブラソニックシステム（ダルトン社製）；ソニクリーン（新東工業社製）；ターボスクリーナー（ターボ工業社製）；ミクロシフター（槙野産業社製）；円形振動篩い等が挙げられる。
【０２２８】
【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。
【０２２９】
［導電性微粒子Ａ−１の製造例］
酸性の塩化スズ水溶液を６０〜８０℃に制御し、そこにアンモニア水溶液を添加して沈殿物を生成させ、ろ過、洗浄して導電性微粒子のスラリーを得た。得られたスラリーを乾燥、解砕した後、窒素雰囲気下で５００℃で２時間、さらに窒素／水素混合ガス雰囲気下で５００℃で１時間焼成し、再度解砕して金属化合物微粒子を得た。得られた金属化合物微粒子をアミノ変性シリコーンオイル３．５質量部で表面処理を行った。表面処理方法としては、加熱型混合機に金属化合物微粒子１００質量部とトルエンで希釈したアミノ変性シリコーンオイル３．５質量部とを加え、８０℃で撹拌混合しながら溶媒を除去した。その後混合を続けながら１２０℃で３０分間加熱処理を行った。室温に戻した後に解砕処理を行った。得られた導電性微粒子Ａ−１の物性は、凝集度が３５．２％、比表面積が５５×１０⁵ｃｍ²／ｃｍ³、体積抵抗６．０×１０²Ωｃｍ、Ｄ₅₀＝１．２μｍ、Ｄ₉₀＝２．２μｍであった。
【０２３０】
［導電性微粒子Ａ−２の製造例］
金属化合物微粒子の製造例１において、塩化スズ濃度、アンモニア水溶液の添加速度、焼成温度及び焼成時間を適宜調整して金属化合物微粒子を製造し、加熱型混合機中、１００質量部の金属化合物微粒子に対し、メチルハイドロジェンシリコーンオイル３．２質量部を加えた溶液を８０℃で撹拌混合し、噴霧終了後さらに１２０℃に昇温して３０分間の加熱処理を行った。取り出し後、室温まで冷却し、解砕して表面処理を施した導電性微粒子Ａ−２を得た。得られた導電性微粒子Ａ−２の物性は、凝集度が２８．７％、比表面積が３０×１０⁵ｃｍ²／ｃｍ³、体積抵抗７．５×１０²Ωｃｍ、Ｄ₅₀＝１．４μｍ、Ｄ₉₀＝２．６μｍであった。
【０２３１】
［導電性微粒子Ａ−３の製造例］
導電性微粒子Ａ−１の製造例１において、塩化スズ濃度、アンモニア水溶液の添加速度、焼成温度及び焼成時間を適宜調整して金属化合物粒子を製造し、加熱型混合機中、１００質量部の金属化合物微粒子に対し、メチルハイドロジェンシリコーンオイル１．７質量部とアミノ変性シリコーンオイル１．８質量部を混合し、後は製造例１と同様に導電性微粒子Ａ−３を得た。得られた導電性微粒子Ａ−３の物性は、凝集度が３８．６％、比表面積が７５×１０⁵ｃｍ²／ｃｍ³、体積抵抗１．１×１０³Ωｃｍ、Ｄ₅₀＝０．７μｍ、Ｄ₉₀＝１．７μｍであった。
【０２３２】
［導電性微粒子Ａ−４の製造例］
導電性微粒子Ａ−１の製造例１において、塩化スズ濃度、アンモニア水溶液の添加速度、焼成温度及び焼成時間を適宜調整して金属化合物粒子を製造し、加熱型混合機中、１００質量部の金属化合物微粒子に対し、ビニルシラン１．５質量部で表面処理を行ったほかは、導電性微粒子Ａ−１の製造例と同様に導電性微粒子Ａ−４を得た。得られた導電性微粒子Ａ−４の物性は、凝集度が５８．２％、比表面積が１０×１０⁵ｃｍ²／ｃｍ³、体積抵抗２．０×１０³Ωｃｍ、Ｄ₅₀＝３．０μｍ、Ｄ₉₀＝５．２μｍであった。
【０２３３】
［導電性微粒子Ａ−５の製造例］
塩化スズと塩化アンチモンを、スズとアンチモンのモル比が１００：７となるよう混合溶解したｐＨ約１の塩酸水溶液を８０℃とし、そこに水酸化ナトリウム水溶液を添加して、共沈物を生成させ、ろ過、洗浄して導電性微粒子のスラリーを得た。得られたスラリーを乾燥、解砕した後、５００℃で３時間焼成し、再度解砕して金属化合物微粒子を得た。得られた導電性微粒子Ａ−５の物性は、凝集度が７７．８％、比表面積が３．７×１０⁵ｃｍ²／ｃｍ³、体積抵抗３．０×１０Ωｃｍ、Ｄ₅₀＝４．２μｍ、Ｄ₉₀＝６．７μｍであった。
【０２３４】
［導電性微粒子Ａ−６の製造例］
導電性微粒子Ａ−５の製造例で粒径を変え、導電性微粒子Ａ−６を得た。得られた導電性微粒子Ａ−６の物性は、凝集度が９９．４％、比表面積が８６×１０⁵ｃｍ²／ｃｍ³、体積抵抗５．３×１０Ωｃｍ、Ｄ₅₀＝０．３μｍ、Ｄ₉₀＝０．７μｍであった。
【０２３５】
表３に各導電性微粒子の物性を示す。
【０２３６】
【表３】

【０２３７】
〔トナーの製造例１〕
材料構成
・結着樹脂 １００質量部
（スチレン−アクリル樹脂（ＤＳＣ測定によるガラス転移温度 Ｔｇが５８℃、酸価２３．０ｍｇＫＯＨ／ｇ、ＧＰＣによるＭｎ（数平均分子量）７０００、Ｍｗ（重量平均分子量）４０００００、モノマー比：スチレン７２．５質量部、ｎ−ブチルアクリレート２０質量部、モノ−ｎ−ブチルマレート７質量部、ジビニルベンゼン０．５質量部）
・磁性酸化鉄 ９５質量部
（平均粒径：０．２０μｍ、ＢＥＴ比表面積：８．０ｍ²／ｇ、抗磁力：３．７ｋＡ／ｍ、飽和磁化：８２．３Ａｍ²／ｋｇ、残留磁化：４．０Ａｍ²／ｋｇ）
・ポリエチレンワックス（融点１１０℃） ４質量部
・荷電制御剤（アゾ化合物の鉄錯体） ２質量部
上記化合物を、１３０℃に加熱され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祖粉砕した。粉砕はターボミル（ターボ工業社製）を用い、機械式粉砕を行った。得られた微粉砕物をコアンダ効果を利用した多分割分級装置（日鉄鉱業社製エルボジェット分級機）で、超微粉および粗粉を厳密に分級除去してトナー粒子１を得た。得られたトナー粒子１の重量平均径は８．０μｍであった。
【０２３８】
次に、
・上記トナー粒子１ １００質量部
・一次粒径１２ｎｍの疎水性シリカＢ １．０質量部
（ジメチルシリコーンオイルとヘキサメチルジシラザンで疎水化処理された、ＢＥＴ１１５ｍ²／ｇのもの）
・導電性微粒子Ａ−１ １．０質量部
上記の材料をヘンシェルミキサーＦＭ１０Ｃ／ｌ（三井鉱山株式会社製）にて周速４０ｓ^-1で２分間混合処理を行いトナー１を得た。
【０２３９】
〔トナー２の製造方法〕
トナー製造例１と同様に、トナー粒子を用い、表４に記載の導電性微粒子と無機微粒子量を用い周速６５ｓ^-1で２分間混合処理を行い、トナー２を得た。
【０２４０】
〔トナー４の製造方法〕
トナー粒子１ １００質量部に対して、疎水性シリカ１．０％を周速７０ｓ−１で２分間外添処理した後、導電性微粒子Ａ−１ １．０質量部を周速３０ｓ−１で０．５分間混合処理を行い、トナー４を得た。
【０２４１】
〔トナー５の製造方法〕
トナー製造例１と同様に、トナー粒子を用い、表４に記載の条件により、導電性微粒子と無機微粒子を添加し、周速７０ｓ^-1で２分間の混合処理を２回行いトナー５を得た。
【０２４２】
〔トナー６の製造方法〕
トナー製造例１と同様に、トナー粒子を用い、表４に記載の条件により、導電性微粒子と無機微粒子を添加し、周速７０ｓ^-1で２分間混合処理を行いトナー６を得た。
【０２４３】
〔トナー７の製造方法〕
トナー製造例１と同様に、トナー粒子を用い、表４に記載の条件により、導電性微粒子と無機微粒子を添加し、周速５０ｓ^-1で２分間の混合処理を２回行いトナー７を得た。
【０２４４】
〔トナー８の製造方法〕
トナー製造例１と同様に、トナー粒子を用い、表４に記載の条件により、導電性微粒子と無機微粒子を添加し、周速４０ｓ^-1で２分間の混合処理を２回行いトナー８を得た。
【０２４５】
〔トナー９の製造方法〕
トナー粒子１ １００質量部に対し、導電性微粒子Ａ−１ １．０質量部をまず添加し周速７０ｓ^-1で２分間外添混合した後、疎水性シリカＢ５％添加の後周速３０ｓ^-1で１分間混合処理を行い、トナー９を得た。
【０２４６】
〔トナー１０の製造方法〕
トナー製造例１と同様に、トナー粒子を用い、表４に記載の条件により、導電性微粒子と無機微粒子を添加し、周速６０ｓ^-1で２分間混合処理を行いトナー１０を得た。
【０２４７】
〔トナー１１の製造方法〕
トナー製造例１と同様に、トナー粒子を用い、表４に記載の条件により、導電性微粒子と無機微粒子を添加し、周速７０ｓ^-1で２分間混合処理を行いトナー１１を得た。
【０２４８】
各トナーの物性、製造条件を表４に示す。
【０２４９】
【表４】

【０２５０】
［感光体の製造例１］
φ３０ｍｍ×２６０．５ｍｍのアルミニウムシリンダーを支持体として、この上にポリアミド樹脂のメタノール溶液を浸漬法で塗布し、膜厚が０．５μｍの下引き層を設けた。
【０２５１】
オキシチタニウムフタロシアニン顔料４質量部、ポリビニルブチラール樹脂２質量部及びシクロヘキサノン８０質量部を、サンドミル装置で４時間ほど分散した。この分散液を前記下引き層上に塗布し、０．２μｍの電荷発生層を形成した。
【０２５２】
次いで、トリフェニルアミン化合物１０質量部及びポリカーボネート樹脂１０質量部を、モノクロロベンゼン１００質量部に溶解した。この溶液を、前記電荷発生層上に塗布し、熱風乾燥し、膜厚が２０μｍの電荷輸送層を形成した。
【０２５３】
次に、電荷注入層として、シリコーンオイルで表面処理したアンチモンドープ酸化スズ微粒子５０質量部をエタノール１５０質量部中に分散し、更に、ポリテトラフルオロエチレン微粒子２０質量部を加えて分散した。その後、レゾール型熱硬化型フェノール樹脂を樹脂成分として１５０質量部を溶解し、調合液とした。
【０２５４】
この調合液を用いて、先の電荷輸送層上に浸漬塗布法により、膜を形成し、熱風乾燥して電荷注入層を形成して感光体１得た。この時、感光体１の電荷注入層の膜厚測定は、薄膜のため光の干渉による瞬間マルチ測光システムＭＣＰＤ−２０００（大塚電子（株）製）を用いて測定し、その膜厚は２μｍであった。その他の膜厚測定法としては、感光体の膜の断面をＳＥＭ等で直接観察測定することもできる。
【０２５５】
［帯電部材の製造例１］
直径６ｍｍ、長さ２６４ｍｍのＳＵＳローラを芯金とし、芯金上にウレタン樹脂、導電性物質としてのカーボンブラック、硫化剤、発泡剤等を処方した中抵抗の発泡ウレタン層をローラ状に形成し、さらに切削研磨し形状及び表面性を整え、可撓性部材として直径１２ｍｍ、長さ２３４ｍｍの帯電部材１を作製した。
【０２５６】
得られた帯電部材１は、抵抗値が１０⁵Ωｃｍであり、硬度がアスカーＣ硬度で３０度であった。
【０２５７】
＜実施例１＞
本例の画像形成装置の全体的な概略構成を図１に示す。図１は転写式電子写真プロセスを利用した現像同時クリーニングプロセス（クリーナレスシステム）のレーザプリンタ（記録装置）である。クリーニングブレード等のクリーニング部材を有するクリーニング手段を除去したプロセスカードリッジを有し、トナーとしてはトナー１を使用し、トナー担持体上のトナー層と像担持体が非接触となるよう配置される非接触現像法を用いる。
【０２５８】
このとき、開口部３の開口幅は９．２ｍｍにし、第２の空間側に弁端部を支持させ、第一の空間側に揺動させるようにした。
【０２５９】
像担持体としての感光体１は、感光体の製造例１で得られたものを用い、矢印のＸ方向に９４ｍｍ／ｓｅｃの周速度（プロセススピード）をもって回転駆動される。
【０２６０】
接触帯電部材としては、上記の帯電部材の製造例１から得られた帯電ローラ２が用いられ、図に示すように帯電ローラ２は感光体１に対して弾性に抗して所定の押圧力で圧接させて配設してある。ｎは感光体１と帯電ローラ２の当接部である帯電当接部である。本例では、帯電ローラ２は感光体１との接触面である帯電当接部ｎにおいて対向方向（矢印Ｙ方向）に１００％の周速で回転駆動されている。帯電ローラ２の表面は感光体１の表面に対して、相対移動速度比２００％の相対速度差を有している。また、帯電ローラ２の表面には、塗布量がおよそ１×１０⁴個／ｍｍ²で均一になるように前記導電性微粒子Ａ−１が塗布されている。
【０２６１】
また帯電ローラ２の芯金２ａには、帯電バイアス印加電源Ｓ１から−６５０Ｖの直流電圧を帯電バイアスとして印加するようにした。本例では感光体１の表面は帯電ローラ２に対する印加電圧とほぼ等しい電位（−６３０Ｖ）に直接注入帯電方式にて一様に帯電処理される。
【０２６２】
露光手段であるレーザダイオード・ポリゴンミラー等を含むレーザビームスキャナ（露光器）３は、目的の画像情報の時系列電気デジタル画素信号に対応して強度変調されたレーザ光を出力し、該レーザ光で上記感光体１の一様帯電面を走査露光する。この走査露光により回転感光体１の面に目的の画像情報に対応した静電潜像が形成される。現像手段としての現像装置４により、感光体１の表面の静電潜像はトナー像として現像される。
【０２６３】
本例の現像装置４は、トナーとしてトナー１を用いた、非接触型の反転現像装置である。
【０２６４】
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）１．０μｍの樹脂層を、表面をブラストした直径１６ｍｍのアルミニウム円筒上に形成した現像スリーブ４ａを使用し、現像磁極９０ｍＴ（９００ガウス）のマグネットロールを内包し、トナー層厚規制部材として厚み１．０ｍｍ、自由長１．５ｍｍのウレタン製の弾性ブレード４ｃを２９．４Ｎ／ｍ（３０ｇ／ｃｍ）の線圧で当接させた。感光体１と現像スリーブ４ａとの間隙は２９０μｍとした。
・フェノール樹脂 １００質量部
・グラファイト（体積平均粒径約７μｍ） ９０質量部
・カーボンブラック １０質量部
【０２６５】
また、現像スリーブ４ａは、感光体１との対向部である現像部ａ（現像領域部）にて感光体１の回転方向と順方向に感光体１の周速の１２０％の周速で回転させる。
【０２６６】
この現像スリーブ４ａに弾性ブレード２４ｃでトナーが薄層にコートされる。トナーは弾性ブレード４ｃで現像スリーブ４ａに対する層厚が規制され、また電荷が付与される。この時、現像スリーブ４ａにコートされたトナー量は、１６ｇ／ｍ²であった。
【０２６７】
現像スリーブ４ａにコートされたトナーは、現像スリーブ４ａの回転により、感光体１と現像スリーブ４ａの対向部である現像部ａに搬送される。また、スリーブ４ａには現像バイアス印加電源Ｓ２より現像バイアス電圧が印加される。現像バイアス電圧は、−４４０Ｖの直流電圧と、周波数１６００Ｈｚ、ピーク間電圧１５００Ｖ（電界強度５×１０⁶Ｖ／ｍ）の矩形の交流電圧を重畳したものを用い、現像スリーブ４ａと感光体１の間、現像部ａで一成分ジャンピング現像を行わせた。
【０２６８】
接触転写手段としての中抵抗の転写ローラ５は、感光体１に９８Ｎ／ｍ（１００ｇ／ｃｍ）の線圧で圧接させて転写当接部ｂを形成させてある。この転写当接部ｂに不図示の給紙部から所定のタイミングで転写材Ｐが給紙され、かつ転写ローラ５に転写バイアス印加電源Ｓ３から所定の転写バイアス電圧が印加されることで、感光体１側のトナー像が転写当接部ｂに給紙された転写材Ｐの面に順次に転写されていく。
【０２６９】
本例では転写ローラ５の体積抵抗値は５×１０⁸Ωｃｍのものを用い、＋２０００Ｖの直流電圧を印加して転写を行った。即ち、転写当接部ｂに導入された転写材Ｐはこの転写当接部ｂを挟持搬送されて、その表面側に感光体１の表面に形成担持されているトナー像が順次に静電気力と押圧力にて転写されていく。転写当接部ｂに給紙されて感光体１側のトナー像の転写を受けた転写材Ｐは感光体の表面から分離されて、定着手段である熱定着方式等の定着装置６に導入され、トナー像の定着を受けて画像形成物（プリント、コピー）として装置外へ排出される。
【０２７０】
本例の画像形成装置はクリーニング手段を除去しており、転写材Ｐに対するトナー像転写後の感光体１の表面に残留の転写残トナーはクリーナで除去されることなく、感光体１の回転にともない帯電当接部ｎを経由して現像部ａに至り、現像装置４において現像同時クリーニング（回収）される。
【０２７１】
従来、トナーは絶縁体であるため帯電当接部ｎへの転写残トナーの混入は感光体の帯電において帯電不良を生じさせる因子である。しかしこの場合でも、ＢＥＴ値の大きい金属化合物微粒子ｍが感光体１と帯電ローラ２との帯電当接部ｎに介存することにより、帯電ローラ２の感光体１への緻密な接触性と接触抵抗を維持できるため、帯電ローラ２の転写残トナーによる汚染にかかわらず、低印加電圧でオゾンレスの直接帯電を長期に渡り安定に維持させることができ、均一な帯電性を与えることが出来る。
【０２７２】
また、本実施例では、プリンタの非画像記録時である紙間時において、シーケンス制御回路により帯電バイアス印加電源のスイッチを切り換え、直流電圧に交流電圧を直列に接続化することにより、帯電ローラ２の芯金２ａに
ＤＣ電圧：−６５０Ｖ
ＡＣ電圧：ピーク間電圧２００Ｖ、周波数５００Ｈｚの矩形波の重畳電圧を印加させている。
【０２７３】
またこの紙間時において、現像装置４の現像スリーブ４ａには、画像記録時と同じく、
ＤＣ電圧：−４４０Ｖ
ＡＣ電圧：ピーク間電圧１５００Ｖ、周波数１．６ｋＨｚ、矩形波の重畳電圧を印加した。
【０２７４】
これらのバイアス関係を維持することにより、帯電ローラ２上で負に摩擦帯電されたトナーを感光体１上に現像し（帯電ローラ２上のトナーの感光体１側への吐き出し）、更にそのトナーを現像装置４のバックコントラストで回収することができる。
【０２７５】
本実施例では、上記画像形成装置に１２０ｇのトナー１を充填して、初期から１０００枚までは印字面積比率１％の格子パターンからなる画像パターンにより、１００１から２０００枚は印字面積３％の横線でトナーカートリッジ内でトナー量が少なくなるまで使用した。転写材としては７５ｇ／ｍ²のＡ４コピー紙を用い、高温高湿環境下（３２．５℃，８０％ＲＨ）で１５秒一枚間欠で１０００枚／日、トータル２０００枚のプリントを行い、耐久初期、２日目耐久初期、２０００枚後一日放置時について以下の評価を行った。結果は表５に示した。
【０２７６】
［評価］
耐久５００枚ごとにベタ白画像をとり、紙上カブリの評価を行った。紙上カブリの測定は、東京電色社製のＲＥＦＬＥＣＴＭＥＴＥＲ ＭＯＤＥＬ ＴＣ−６ＤＳを使用して測定した。フィルターは、グリーンフィルターを用いた。カブリの数値は、ベタ白画像で下記の式より算出した。紙上カブリは、２．５％以下であれば良好な画像である。
カブリ(反射率)(％)＝標準紙上の反射率(％)−サンプル非画像部の反射率(％)
【０２７７】
耐久初期、５０１枚目、１００１枚目、１５０１枚目、２日目耐久初期、耐久後一日放置時点でベタ黒画像をプリントし、画像濃度の評価を行った。画像濃度はベタ黒画像をマクベス濃度計ＲＤ９１８（マクベス社製）で５点平均で測定した。
【０２７８】
フェーディングの評価は、上記評価ベタ黒画像が部分的に薄くなっているかどうかで判断を行った。
Ａ：フェーディング無し
Ｂ：一日放置後フェーディング
Ｃ：１５００枚通紙後フェーディング
Ｄ：１０００枚通紙語フェーディング
Ｅ：５００枚通紙後フェーディング
【０２７９】
帯電ムラの評価
帯電ムラは、上端部（画像先端部から３ｃｍ幅）がベタ画像及び非画像の混合画像で、画像先端部から３ｃｍ以降が均一な中間調である画像パターンにより評価した。帯電ローラーに存在する導電性微粒子量が少なくなると、帯電ローラーと感光体とのニップ部で導電性微粒子量が不足する。そのため、感光体上で再帯電できない部分は電位が下がらずレーザー露光の影響のみを受け、その部分だけより多くのトナーが現像されやすい。その結果、特に中間調部をプリントアウトする場合などにおいて、細かい筋のような黒い線が発生する。この評価は、耐久を通してどの時点で帯電ムラが発生するか、５００枚ごとに中間調部画像をプリントし、帯電性能の評価を行った。
Ａ：２０００枚耐久を通して黒筋発生無し もしくは非常に軽微で分かりにくい
Ｂ：１５００枚通紙後発生
Ｃ：１０００枚通紙後発生
Ｄ：５００枚通紙後発生
Ｅ：初期〜５００枚通紙から見られる
【０２８０】
白ポチ（遮光）の評価
白ポチの評価は５００枚耐久ごとに１ｄｏｔ１ｓｐａｃｅパターンを連続５枚プリントし、白ポチ（遮光）の数を数えて評価を行った。
Ａ：白ポチはほとんど発生しない、もしくは白ポチ３０個以下
Ｂ：白ポチ３１〜５０個
Ｃ：白ポチ５１〜１００個
Ｄ：白ポチ１０１〜２００個
Ｅ：全面に白ポチ発生
【０２８１】
導電性微粒子の供給安定性の評価
２０００枚耐久後、カートリッジの第２の空間と第一の空間に残っているトナーを採取し、蛍光Ｘ線を測定して導電性微粒子量の測定を行った。装置は、ＲＩＧＡＫＵのＲＩＸ３０００を使い、５０ｋｖ７０ｍＡの条件で、Ｓｎのピーク強度により、導電性微粒子の量を測定した。
【０２８２】
＜実施例２〜４、参考例１、実施例６及び７＞
表４に記載のトナー２〜７を用い、図１に記載の画像形成装置を用い、実施例１と同様に評価を行った。評価結果を表５に示す。
【０２８３】
＜比較例１＞
表４に記載のトナー７と、図７に記載の弁構成の無い画像形成装置と、感光体の製造例１に記載の感光体１と帯電部材の製造例１に記載の帯電ローラー２を用いて、実施例１と同様に評価を行った。評価結果を表５に示す。このときの開口幅は３０ｍｍであった。
【０２８４】
＜比較例２〜３＞
表４に記載のトナー８・９と、図２に記載の画像形成装置を用い、感光体の製造例１に記載の感光体１と帯電部材の製造例１に記載の帯電ローラー２を用いて、実施例１と同様に評価を行った。評価結果を表５に示す。
【０２８６】
＜比較例４〜５＞
表４に記載のトナー１０・１１と、図２に記載の画像形成装置を用い、感光体の製造例１に記載の感光体１と帯電部材の製造例１に記載の帯電ローラー２を用いて、比較例１と同様に評価を行った。評価結果を表５に示す。
【０２８７】
【表５】

【０２８８】
【発明の効果】
本発明に記載の、該トナーのＣａｒｒの噴流性指数が８０より大きく、該トナーの重量平均粒径が５μｍ以上１２μｍ以下であり、該導電性微粒子は体積基準のメジアン径（Ｄ₅₀）が０．４μｍ以上４．０μｍ以下でトナーの質量平均粒径未満であり、Ｄ₉₀が６．０μｍ以下の導電性微粒子であり、トナー粒子に対する導電性微粒子の遊離率ａと無機微粒子の遊離率ｂとが
遊離率ｂ＜遊離率ａ
を満足するトナーを用い、トナーを収容するトナー容器の空間が、像担持体に近い側で且つ静電潜像を前記トナーによりトナー画像を形成する現像手段が配置された第１の空間と、像担持体から遠い側の第２の空間に分割され、該第１の空間と第２の空間との境界に、その一端部側が揺動可能な弁部材を設けてある画像形成装置に適用することで、高温高湿下で長期にわたって帯電ムラ、フェーディングを起こさず、高い画像濃度とカブリ良化を達成することができる。
【図面の簡単な説明】
【図１】本発明に係る現像装置を装備するプロセスカートリッジを装着した画像形成装置の第１実施形態の構成を示す概略側面図である。
【図２】第１実施形態の現像装置の構成を示す断面説明図である。
【図３】第１実施形態の現像装置において、第１の空間側から見た弁部材の動きを示す図である。
【図４】第１実施形態の現像装置において、弁部材の動きを説明する図である。
【図５】本発明に係る現像装置の第２実施形態の構成を示す断面説明図である。
【図６】第２実施形態の現像装置において、第１の空間側から見た弁部材の動きを示す図である。
【図７】従来例を説明する図である。
【符号の説明】
１…感光体ドラム
２…帯電ローラ
２ａ…芯金
２ｂ…中抵抗層
３…開口部
４…現像装置
４ａ…現像スリーブ
４ｂ…マグネットロール
４ｃ…規制ブレード
４ｄ…トナー
５…転写ローラ
６…空隙
７…トナー容器
７ａ…仕切り壁
９…弁部材
９ａ…上部
１０…第１の空間
１１…第２の空間
１２…攪拌部材
Ｌ…レーザ光（走査露光）
ａ…現像部
ｂ…転写当接部
ｍ…導電性微粒子
ｎ…帯電当接部
Ｐ…転写材
Ｓ１…帯電バイアス印加電源
Ｓ２…現像バイアス印加電源
Ｓ３…転写バイアス印加電源
ｔ…トナー[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a toner used for an electrophotographic apparatus, an electrostatic recording apparatus, a magnetic recording apparatus, and the like, and an image forming method using such a toner. The present invention also relates to a process cartridge that can be attached to and detached from an image forming apparatus such as a copying machine, a printer, a facsimile, and a plotter, which forms a toner image on an image carrier and then forms the image by transferring the toner image onto a recording medium. .
[0002]
[Prior art]
Conventionally, as an image forming method, many methods such as an electrostatic recording method, a magnetic recording method, and a toner jet method are known. For example, electrophotography generally forms an electrical latent image on an image carrier such as a photoconductor using a photoconductive material by various means, and then develops the latent image with toner. A visible toner image is formed, and the toner image is transferred to a recording medium such as paper as necessary, and then the toner image is fixed on the recording medium by heat, pressure, or the like to obtain an image.
[0003]
On the other hand, as a system that does not generate waste toner, a technique called simultaneous development cleaning or cleanerless has been proposed. There are Patent Literature 1, Patent Literature 2, Patent Literature 3, Patent Literature 4, Patent Literature 5, Patent Literature 6, Patent Literature 7, Patent Literature 8, and the like that disclose technologies related to this cleaner-less. No detailed and specific system configuration is mentioned.
[0004]
In the simultaneous development cleaning that essentially does not have a cleaning device, it has become essential to rub the surface of the image carrier with toner and the toner carrier. Therefore, as a preferred development method, toner or toner is applied to the image carrier. Many contact development methods that come into contact have been studied. This is because it is considered that a configuration in which the toner or toner contacts and rubs the image carrier in order to collect the transfer residual toner in the developing unit is advantageous. However, the simultaneous development cleaning or the cleaner-less process using the contact development method causes toner deterioration, toner carrier surface deterioration, image carrier surface deterioration or wear, etc. due to long-term use, and is a sufficient solution to durability characteristics. Not done.
[0005]
On the other hand, a direct injection charging mechanism has been proposed as a new environment-friendly new technique that enables simultaneous development cleaning not only in a contact development system but also in a non-contact development system and does not generate active ions such as ozone.
[0006]
This direct injection charging mechanism will be briefly described.
[0007]
The direct injection charging mechanism is a mechanism in which the surface of the charged body is charged by directly injecting charges from the contact charging member to the charged body. It is also called direct charging, injection charging, or charge injection charging. More specifically, a medium-resistance contact charging member comes into contact with the surface of the member to be charged, and charge is directly injected into the surface of the member to be charged without going through a discharge phenomenon, that is, basically using no discharge. Therefore, even if the applied voltage to the contact charging member is an applied voltage that is equal to or lower than the discharge threshold, the object to be charged can be charged to a potential corresponding to the applied voltage. Since this charging system is not accompanied by the generation of ions, there is no adverse effect caused by the discharge products. However, since it is direct injection charging, the number of contact points and the contact area of the contact charging member to the member to be charged greatly affect the charging property. Therefore, in order to take a configuration that contacts the charged body at a higher frequency, a configuration is required in which the contact charging member has a denser contact point, and the contact time with the charged body is maintained longer.
[0008]
Among them, as a method for increasing the density of the contact points between the charging member and the charged body, there is a high efficiency by providing conductive charge-promoting particles at the contact portion between the charging member and the charged body, so-called image carrier. A method for ensuring a good injection chargeability has been proposed.
[0009]
For example, as a method for supplying the conductive charge promoting particles so as to always exist at the contact portion with the image carrier, in Patent Document 9, the solidified charge promoting particle member is brought into contact with the charging roller, and is itself scraped. In Patent Document 10, a method of supplying a charge-promoting particle by a fur brush in contact with the charging roller; in Patent Document 10, a method of supplying a charge-promoting particle application member to a charging roller in Patent Document 11; In No. 12, there is a method of supplying the charge promoting particles to the charging member by scraping the granules. However, these methods stably supply a certain amount of the charge promoting particles through durability in a high temperature / high humidity environment or a low temperature / low humidity environment. It is difficult to continue, and it is not possible to achieve the low cost and downsizing that are the advantages of cleaner-less.
[0010]
In Japanese Patent Application Laid-Open No. H11-260260, image formation in which toner containing toner particles and conductive charge accelerating particles having a particle size equal to or less than ½ of the toner particle size is applied to a developing and cleaning image forming method using a direct injection charging mechanism An apparatus is disclosed. According to this proposal, it is possible to obtain a developing and cleaning image forming apparatus which can greatly reduce the amount of waste toner without generating a discharge product and is advantageous for downsizing at low cost. Alternatively, a good image that does not cause diffusion can be obtained. Further, in Patent Document 14, the conductive fine particles are applied to a developing and cleaning image forming method using a toner containing conductive fine particles having a particle size of 1/50 to 1/2 of the toner particle size in a direct injection charging mechanism. An image forming apparatus having a transfer promoting effect is disclosed.
[0011]
Further, in Patent Document 15, the particle diameter of the metal fine particles is set to 10 nm to 50 μm in order to make the particle diameter of the conductive fine particles equal to or smaller than the size of one constituent pixel and to obtain better charging uniformity. It is described.
[0012]
Further, according to Patent Document 16, by setting the particle size of the conductive fine particles to be equal to or smaller than the toner particle size, the development of the toner is inhibited during development, or the development bias is prevented from leaking through the conductive fine particles. By eliminating the defects in the image and setting the particle size of the conductive fine particles to be larger than 0.1 μm, the adverse effect of shielding the exposure light by embedding the conductive fine particles in the image bearing member can be solved. A developing and cleaning image forming method using a direct injection charging mechanism for realizing recording is described.
[0013]
Further, many methods for adding conductive fine particles as an external additive have been proposed. For example, carbon black as conductive fine particles is used to attach or adhere to the toner surface for the purpose of imparting conductivity to the toner, or for the purpose of suppressing excessive charging of the toner and making the tribo distribution uniform. It is widely known to use as an external additive. Patent Document 17, Patent Document 18, and Patent Document 19 disclose that conductive fine particles of tin oxide, zinc oxide, and titanium oxide are externally added to the high-resistance magnetic toner, respectively. Further, in Patent Document 20, developability and transferability are achieved by adding a conductive magnetic powder such as iron oxide, iron powder, and ferrite to a high-resistance magnetic toner and accelerating charge induction into the magnetic toner. Toners that satisfy both requirements have been proposed. Further, Patent Document 21, Patent Document 22, Patent Document 23, and Patent Document 24 disclose that graphite, magnetite, polypyrrole conductive powder, polyaniline conductive powder is added to the toner, and various conductive properties. It is known to add fine particles to the toner.
[0014]
Even when such conductive fine particles are used, if the supply state and the existence state of the conductive fine particles are not adjusted appropriately, insufficient supply or excessive supply of conductive fine particles may occur in a low-temperature and low-humidity environment or a high-temperature and high-humidity environment. There was a problem that developability deteriorated due to defects.
[0015]
[Patent Document 1]
JP 59-133573 A
[Patent Document 2]
JP-A-62-203182
[Patent Document 3]
JP-A-63-133179
[Patent Document 4]
JP-A 64-20587
[Patent Document 5]
Japanese Patent Laid-Open No. 2-302772
[Patent Document 6]
JP-A-5-2289
[Patent Document 7]
Japanese Patent Laid-Open No. 5-53482
[Patent Document 8]
JP-A-5-61383
[Patent Document 9]
Japanese Patent Laid-Open No. 11-72991
[Patent Document 10]
JP-A-11-149196
[Patent Document 11]
Japanese Patent Laid-Open No. 11-194484
[Patent Document 12]
JP 2000-148767 A
[Patent Document 13]
JP-A-10-307456
[Patent Document 14]
Japanese Patent Laid-Open No. 10-307421
[Patent Document 15]
JP-A-10-307455
[Patent Document 16]
JP-A-10-307458
[Patent Document 17]
JP 57-151952 A
[Patent Document 18]
JP 59-168458 A
[Patent Document 19]
JP 60-69660 A
[Patent Document 20]
JP-A-56-142540
[Patent Document 21]
JP-A 61-275864
[Patent Document 22]
JP-A-62-258472
[Patent Document 23]
Japanese Patent Laid-Open No. 61-141452
[Patent Document 24]
Japanese Patent Laid-Open No. 02-120865
[0016]
[Problems to be solved by the invention]
  An object of the present invention is a direct injection charging mechanism that, when used in an image forming method including a contact charging step, is substantially free of discharge products such as ozone and can uniformly charge an image carrier at a low applied voltage. Can be uniformly charged, and even with repeated use over a long period of time, good images can be obtained without causing poor charging.RutoImage forming methodThe lawIt is to provide.
[0017]
  The object of the present invention is not influenced by the environment, does not cause uneven charging and fading over a long period of time, and provides a high image density and no fog image.RutoImage forming methodThe lawIt is to provide.
[0018]
[Means for Solving the Problems]
  In order to solve the above problems, the present inventor, PaintingImage formationThe lawThe following configuration was adopted.
[0025]
  That isThe present invention is a toner used in a developing device that supplies toner to an electrostatic latent image formed on a charged surface of an image carrier to visualize the toner image.
  A developing unit is provided in which the space of the toner container for storing the toner in the developing device is close to the image carrier and the electrostatic latent image is visualized as a toner image by the toner. And a second space on the side far from the image carrier, and a valve member is provided at the boundary between the first space and the second space. And
  The opening width of the opening between the first space and the second space is 20 mm or less,
  A charging step in which a voltage is applied to the charging member to bring it into contact with the image carrier and charging; an electrostatic latent image forming step in which an electrostatic latent image is formed on the charged image carrier; and a toner carrier A developing step of transferring the carried toner to the electrostatic latent image held on the surface of the image carrier to form a toner image; and a toner image formed on the image carrier through an intermediate transfer member. In an image forming method including at least a transfer step of transferring to a transfer material without or intervening,
  The image forming method does not have a cleaning step between the transfer step and the charging step,
  The toner has at least toner particles, conductive fine particles, and inorganic fine particles. The toner has at least a binder resin and a colorant. The toner has a Carr jetting index greater than 80. The weight average particle diameter is 5 μm or more and 12 μm or less, and the conductive fine particles have a volume-based median diameter (D50) of 0.4 μm or more and 4.0 μm or less and less than the weight average particle diameter of the toner, and D90 is 6.0 μm. The following conductive fine particles have a free particle a release rate a and inorganic fine particle release rate b with respect to toner particles.
      Liberation rate b <release rate a
Satisfied,The liberation rate a is not less than 59% and not more than 95%, and
  underSteps (1) and (2)The present invention relates to an image forming method.
(1) As the charging step, a voltage is applied to the charging member with at least the conductive fine particles interposed in a nip portion that is a contact portion between the image carrier and a charging member that contacts the image carrier. Contact charging process to charge the image carrier
(2) As the developing step, a developing and cleaning step of visualizing the electrostatic latent image and collecting the toner remaining on the surface of the image carrier after the toner image is transferred to the transfer material
[0027]
DETAILED DESCRIPTION OF THE INVENTION
The present inventors have developed a toner having at least a binder resin and a colorant, a toner having at least inorganic particles and conductive particles, and a toner composed of inorganic particles and conductive particles having a specific relationship in particle size. By controlling the liberation rate from the substrate, when used in an image forming method including a contact charging step, there is substantially no generation of discharge products such as ozone, and uniform charging of the image carrier can be achieved with a low applied voltage. It has been found that uniform charging using the obtained direct injection charging mechanism can be performed uniformly with a simple configuration, and that a good image can be obtained without charging failure even when the toner is repeatedly used over a long period of time.
[0028]
Further, the inventors of the present invention have a first toner space in which a toner container for containing toner is located on a side close to the image carrier and a developing unit for forming a toner image from the electrostatic latent image with the toner. A valve member that is divided into a second space far from the image carrier and whose one end side can swing toward the first space at the boundary between the first space and the second space. As described above, when a process cartridge used in an image forming apparatus is used in an image forming method including a contact charging step by controlling the liberation rate of inorganic fine particles / conductive fine particles from toner particles to a toner, Since the supply state of the conductive fine particles can be made stable and constant even in a temperature / humidity environment, the image quality was excellent without causing charging failure over a long period of time.
[0029]
In addition, since the cartridge configuration of the present invention has the configuration as described above, it is possible to move toner from the second space to the first space only by the valve member, thereby reducing the prior consumption of the conductive fine particles. Therefore, the supply of the conductive fine particles to the contact charging member is stable even in the latter half of the durability, and the graphic halftone image can be reproduced finely through the durability.
[0030]
The toner having the above characteristics will be briefly described below together with the behavior during image formation.
[0031]
The toner of the present invention includes a toner having at least a binder resin and a colorant, an inorganic fine particle, and a conductive fine particle. It has a release rate. When the electrostatic latent image formed on the image carrier is developed, an appropriate amount of the conductive fine particles contained in the toner is transferred from the toner carrier to the image carrier. The toner image formed on the image carrier by developing the electrostatic latent image is transferred to a transfer material such as paper in the transfer process. At this time, a part of the conductive fine particles on the image carrier adheres to the transfer material, but the rest remains adhered to and held on the image carrier.
[0032]
When image formation is repeatedly performed on the image carrier, a known cleaning process performed between the transfer process and the charging process, that is, the toner component adhered and held on the image carrier is removed from the image carrier. In the image forming method that does not include the removing step, toner particles remaining on the surface of the image carrier after transfer (hereinafter referred to as “transfer residual toner particles”) and the remaining conductive fine particles form an image on the image carrier. It is carried to the charging unit as the carrying surface (hereinafter referred to as “image carrying surface”) moves.
[0033]
When a contact charging member is used for charging the image carrier, the conductive fine particles are carried to the charging part, which is a nip formed by the contact between the image carrier and the contact charging member, and adhere to and mix with the contact charging member. To do. Therefore, contact charging of the image carrier is performed with the conductive fine particles interposed in the nip portion.
[0034]
Although conductive fine particles are attached and mixed in the contact charging member and the conductive fine particles are present in the charging portion, the contact charging member is contaminated by the adhesion and mixing of transfer residual toner particles. Since the resistance can be maintained, the image carrier can be favorably charged by the contact charging member. If a sufficient amount of conductive fine particles are not present in the charged part of the contact charging member, the charge of the image carrier easily decreases due to adhesion and mixing of the transfer residual toner particles to the contact charging member, and image smearing occurs. Prone to occur.
[0035]
Furthermore, since the conductive fine particles are actively carried to the nip formed by the contact between the image carrier and the contact charging member, the contact charging member can be kept in close contact with the image carrier and the contact resistance. Further, direct injection charging of the image carrier by the contact charging member can be performed satisfactorily.
[0036]
The transfer residual toner particles pass through the charging portion or are gradually discharged from the contact charging member onto the image carrier, and reach the developing portion as the image carrying surface moves. Here, in the image forming method including the development and cleaning process, the development and cleaning, that is, the collection of the transfer residual toner particles is performed in the development process. Further, the conductive fine particles remaining attached to and held on the image carrier after the transfer step reach the developing portion along with the movement of the image carrying surface in the same manner as the transfer residual toner particles.
[0037]
That is, the conductive fine particles are present on the image carrier together with the transfer residual toner particles, and the transfer residual toner particles are collected in the development process. When the transfer residual toner particles are collected using the development bias electric field in the development process, the transfer residual toner particles are collected by the development bias electric field, whereas the conductive fine particles on the image carrier are electrically conductive. It is difficult to be recovered because it is sex. For this reason, a part of the conductive fine particles is collected, but the rest remains attached and held on the image carrier.
[0038]
According to the study by the present inventors, in the cleaning process, when the transfer residual toner particles discharged on the image carrier are discharged in a large lump, the toner lump on the image carrier is a portion where the toner lump is present. A latent image cannot be formed by laser exposure. For this reason, particularly when a high-print image is continuously printed, the transfer residual toner is accumulated, so that a large amount of toner lump is ejected onto the image carrier, and the laser exposure is canceled and the white spots are removed. "Is more likely to occur.
[0039]
It has also been found that the presence of conductive fine particles that are difficult to recover in the development step on the image carrier can provide an effect of improving the recoverability of transfer residual toner particles on the image carrier. In other words, the conductive fine particles on the image carrier act as an auxiliary agent for collecting the residual toner particles on the image carrier, making the recovery of the residual toner particles in the development process more reliable, and the poor recovery of the residual toner particles. Therefore, it is possible to effectively prevent image defects such as shading of exposure light and fogging.
[0040]
Conventionally, most of the purpose of externally adding conductive fine particles to the toner is to control the triboelectric chargeability of the toner particles by attaching the conductive fine particles to the surface of the toner particles. Conductive fine particles have been treated as adverse effects that cause changes or deterioration of toner characteristics or image carrier deterioration.
[0041]
In contrast, in the toner of the present invention, by controlling the particle sizes of the conductive fine particles and the inorganic fine particles, the conductive fine particles are actively released from the surface of the toner particles without releasing the inorganic fine particles. The above-mentioned effects can be obtained by supplying the toner to the toner, and at least the amount of the conductive fine particles remaining on the image carrier after leaving the image carrier after the transfer process is small and there are few residual toner particles on the image carrier. This is different from the external addition of conductive fine particles to the toner, which has been studied in the past, in that the above effect can be obtained more preferably. That is, the toner of the present invention has an excellent effect in an image forming method including a contact charging step, an image forming method including a developing and cleaning step, or an image forming method including both of these steps.
[0042]
In the toner of the present invention, the conductive fine particles are easily released from the surface of the toner particles, and the nip portion formed by the contact between the image carrier and the contact charging member via the conductive fine particles transferred on the image carrier. By carrying and interposing it in the charging portion, the chargeability of the image carrier is improved, charging failure is prevented, and stable and uniform charging is possible. In addition, since the conductive fine particles are present on the image carrier in the development process, the conductive fine particles serve as a recovery aid for the residual toner particles on the image carrier, and the transfer residual toner particles in the development process can be more recovered. Image defects such as fogging due to poor recovery of transfer residual toner particles can be effectively prevented.
[0043]
In the present invention, conductive fine particles that adhere to the toner particle surface and behave together with the toner particles (that is, conductive fine particles that are not released from the toner particle surface) are charged with the chargeability of the image carrier on which the toner of the present invention is effective. Does not contribute to acceleration and improvement of development and cleaning performance. For this reason, toner particles having conductive fine particles strongly adhered to the surface have reduced triboelectric chargeability, lower developability, lower transfer residual toner particle recoverability during development and cleaning, and lower transferability. Increasing the amount may cause uniform charging or inhibition of latent image formation.
[0044]
According to the inventors' investigation on the effect of promoting the chargeability of the image bearing member and the effect of developing and cleaning, the free state of the conductive fine particles and the inorganic fine particles from the toner particles, that is, the release rate of the conductive fine particles. a and the liberation rate b of the inorganic fine particles
Liberation rate b <release rate a
(Preferably 40b <a, more preferably 30b <a)
It is better to control so as to satisfy In this way, by controlling the free state of the conductive fine particles and inorganic fine particles on the surface of the toner particles, the conductive fine particles pass through the transferred image carrier and the image carrier and the contact charging member come into contact with each other. It is carried to the charging part, which is the nip part to be formed, and by interposing the conductive fine particles, the chargeability of the image carrier is improved, charging failure is prevented, and stable and uniform charging is possible. And In addition, when the conductive fine particles are present on the image carrier and the inorganic fine particles are appropriately adhered on the surface of the toner particles in the development process, the conductive fine particles are recovered from the transfer residual toner particles on the image carrier. In addition to acting as an auxiliary agent, the rising speed of recharging of the residual toner particles is increased, so that the residual toner particles are more reliably recovered in the development process, and the exposure light due to poor recovery of the residual toner particles is recovered. Image defects such as light shielding and fogging can be effectively prevented.
[0045]
In addition, even if image formation is repeated over a long period of time, the conductive fine particles are newly transferred to the image carrying surface in the development process, and together with the conductive fine particles remaining on the image carrying surface, the transfer process is performed along with the movement of the image carrying surface. It is carried to the charging unit and continuously supplied to the charging unit. In addition, since the amount of the inorganic fine particles in the toner particles is controlled, the toner hardly deteriorates even during long-term image formation. Therefore, even if the conductive fine particles fall off at the charged part or the uniform charge promoting ability of the conductive fine particles deteriorates, the conductive fine particles continue to be supplied to the charged part. In this case, the charging property of the image carrier is prevented from being deteriorated, and good uniform charging is stably maintained, and image defects such as exposure light shielding and fogging due to poor collection of residual toner particles are effectively prevented. can do.
[0046]
As described above, by controlling the release state of the conductive fine particles and inorganic fine particles on the surface of the toner particles, the supply of the conductive fine particles to the contact charging member is promoted to improve the uniform chargeability and transfer residual. Since the toner can be collected effectively, an image forming method by high-quality contact charging that can be reproduced finely to the halftone of the graphic image becomes possible.
[0047]
In the present invention, the free state of the conductive fine particles and the inorganic fine particles from the toner particles, that is, the release rate a of the conductive fine particles and the release rate b of the inorganic fine particles are
Free rate b ≧ Free rate a
In such a case, the conductive fine particles tend to adhere more firmly to the surface of the toner particles than the inorganic fine particles, indicating that the inorganic fine particles are in a state of a large amount of release from the toner particles. For this reason, the conductive fine particles cannot be sufficiently supplied to the image bearing surface in the development process, and the conductive fine particles are hardly released from the surface of the toner particles in the transfer process. Further, since a large amount of inorganic fine particles are released from the toner, the toner charge rises slowly, and the toner particles remaining after transfer increase.
[0048]
For this reason, it is difficult to positively leave the conductive fine particles on the image carrier after the transfer, and to actively supply the conductive fine particles to the charged portion, and a lot of toner particles remain in the charged portion. As a result, the chargeability of the image carrier is lowered and image defects are likely to occur. Also in the development and cleaning process, the conductive fine particles cannot be sufficiently supplied onto the image carrier, and the rise of the charge of the transfer residual toner is slow, so that the effect of improving the recovery of the transfer residual toner is obtained. On the contrary, since the transfer residual toner to be recovered increases, image defects such as exposure light shading and fogging due to poor recovery of transfer residual toner particles are likely to occur.
[0049]
Further, the release rate a of the conductive fine particles from the toner particles in the toner of the present invention is 40 to 95%, more preferably 50 to 95%, still more preferably 60 to 95%. When the liberation rate a is lower than 40%, the conductive fine particles cannot be sufficiently supplied to the image bearing surface in the development process, and the conductive fine particles are not easily released from the toner particle surfaces in the transfer process. For this reason, the conductive fine particles remain positively on the image carrier after transfer, and it becomes difficult to positively supply the conductive fine particles to the charging portion. Prone to defects. Also in the development and cleaning process, the conductive fine particles cannot be sufficiently supplied onto the image carrier, and the effect of improving the recovery of the transfer residual toner cannot be obtained. Image defects such as shading of exposure light and fogging due to defects are likely to occur. Further, when the liberation rate a is higher than 95%, the conductive fine particles are almost free from the toner particles. Therefore, although the conductive fine particles can be supplied to the image bearing surface in the development process, image formation can be performed over a long period of time. As the process is repeated, the concentration of the conductive fine particles in the toner decreases, and in the latter half of the endurance, it becomes difficult to positively supply the conductive fine particles to the charged portion, and many toner particles remain in the charged portion. As a result, the chargeability of the image carrier is lowered and image defects are likely to occur. Also, in the development and cleaning process, the conductive fine particles cannot be sufficiently supplied onto the image carrier, and on the contrary, the transfer residual toner to be recovered increases. It is easy to cause image defects such as shading of exposure light and fogging.
[0050]
Further, the liberation ratio b of the inorganic fine particles from the toner particles in the toner of the present invention is 0.1 to 5%, more preferably 0.1 to 3%. When the liberation rate b is higher than 5%, a large amount of inorganic fine particles are liberated from the toner, so that the rising of charging of the toner is delayed and toner particles remaining after transfer increase.
[0051]
For this reason, a large amount of toner particles remain in the charging portion, and the chargeability of the image carrier is lowered and image defects are likely to occur. Also, in the development and cleaning process, since the rise of the charge of the transfer residual toner is slow, the effect of improving the recovery of the transfer residual toner cannot be obtained, and conversely the transfer residual toner to be recovered increases. Image defects such as shading of exposure light and fog due to poor collection of transfer residual toner particles are likely to occur.
[0052]
When the liberation rate b is lower than 0.1%, it is indicated that almost no inorganic fine particles are released from the toner particles, and in such a state, the degree of embedding of the inorganic fine particles in the toner particles is usually large. Easy to happen. In such a case, not only the rising of charging is delayed, but also it becomes difficult to maintain the charge amount, so that it is difficult to obtain good developability.
[0053]
The release ratio of the conductive fine particles and inorganic fine particles from the toner particles in the present invention is measured by a particle analyzer (PT1000: manufactured by Yokogawa Electric Corporation). The particle analyzer is 65 to 68 in the paper of Japan Hardcopy 97. Measurement is performed according to the principle described on the page. Specifically, the apparatus is an apparatus in which fine particles such as toner are introduced into the plasma one by one and the element of the luminescent material, the number of particles, and the particle size of the particles can be known from the emission spectrum of the fine particles. For example, consider a case where toner particles, in which silica is used as inorganic fine particles and tin oxide is added as conductive fine particles, are introduced into the plasma. When the toner particles are introduced into the plasma, they are constituent elements of the binder resin with respect to one toner particle. Carbon emission and Si atom and Sn atom emission are observed, respectively. That is, since one light emission is obtained for each toner particle, the number of toner particles can be obtained from the number of times of light emission. At that time, the Si and Sn atoms emitted within 2.6 msec from the emission of carbon atoms were simultaneously emitted, and the subsequent emission of Si and Sn atoms was only the Si and Sn atoms. In the toner of the present invention, the fact that carbon atoms and Si and Sn atoms emit light at the same time means that silica and tin oxide are attached to the surface of the toner particles, respectively. It can be said that silica and tin oxide are liberated from the toner particles. As a specific method, a toner sample conditioned by being left overnight in an environment of a temperature of 23 ° C. and a humidity of 60% is measured using helium gas containing 0.1% oxygen in the environment. That is, carbon atoms (measurement wavelength 247.86 nm) are measured in channel 1, tin atoms (measurement wavelength 326.23 nm) are measured in channel 2, silica atoms (measurement wavelength 288.16 nm) are measured in channel 3, and carbon is measured in one scan. Sampling is performed so that the number of light emission of atoms is 1000 to 1400, and scanning is repeated until the total number of light emission of carbon atoms reaches 10,000 or more, and the number of light emission is integrated. Then, by counting the number of light emission of only Si and Sn atoms at that time, the number of free silica and tin oxide is obtained. At this time, the noise cut level is 1.50V.
[0054]
By combining the above toner with a process cartridge, new toner that has not deteriorated throughout the endurance is supplied to the first space little by little, so toner with conductive particles with a high release rate is used in the second half of the endurance. it can. Therefore, even in the latter half of the endurance, the transfer residual toner is highly recoverable and rechargeable, and evenly discharged from the contact charging member to the photosensitive member and collected by the developing unit.
[0055]
Further, in the toner of the present invention, the particle diameter of the conductive fine particles is a volume-based median diameter (D₅₀) Is 0.4 μm or more and 4.0 μm or less, D₉₀Is a conductive fine particle of 6.0 μm or less. Preferably, D₅₀Is 0.6 μm to 3.0 μm, D₉₀Is 5.0 or less, and also D₅₀Is 0.8 to 2.5 μm, D₉₀Is preferably 4.5 μm or less.
[0056]
In general, the greater the difference in particle size between particles, the stronger the adhesive force due to the interaction between particles. As described above, in order for the conductive fine particles according to the present invention to act as a charging auxiliary material, it is necessary to positively convey only the conductive fine particles to the charging member by separating from the toner particles after the transfer process, If the interaction between the conductive fine particles and the toner is too strong, it becomes difficult. In addition, as one of the main roles of the conductive fine particles according to the present invention, there is also a development assist effect from the improvement of the tribocharging property in the contact friction with the toner particles in the development process. If it adheres strongly, the effect is difficult to be demonstrated. Taking these into account, preferred D of the conductive fine particles according to the present invention₅₀0.4 μm to 4.0 μm, D₉₀Is 6.0 or less.
[0057]
D₅₀The conductive fine particles having a particle size of less than 0.4 μm are difficult to separate from the toner particles, so that the action as a charging auxiliary material and further as a developing auxiliary material becomes insufficient, resulting in poor charging and poor developability.
[0058]
On the other hand, D₅₀As the value increases, the interaction with the toner becomes weaker, and the effect of improving the frictional charging characteristics and the like decreases. Especially D of conductive fine particles₅₀When the toner exceeds the weight average of the toner, the effect of the interaction is hardly seen, and it acts as an electrode under the developing electric field, which rather hinders the movement of the toner. Or the resolution is reduced. Deterioration of fog leads to contamination of the charging member, leading to a decrease in chargeability. Therefore, D of conductive fine particles₅₀Is less than the weight average of the toner and is preferably 4.0 μm or less, particularly preferably 3.5 μm or less. For this reason, it is preferable that the conductive fine particles have few large particles, and D is used as an indicator of the distribution on the coarse powder side.₉₀Is used, the conductive fine particles D₉₀Is preferably 6.0 μm or less, and more preferably 4.0 μm or less.
[0059]
In this sense, it is preferable that the conductive fine particles have fewer fine particles in the particle size distribution. Here, D of conductive fine particles₅₀, D₉₀Is measured as follows.
[0060]
A liquid module is attached to a laser diffraction particle size distribution analyzer [LS-230 type] (manufactured by Coulter, Inc.), a particle size of 0.04 to 2000 μm is set as a measuring range, and the particle size distribution based on the obtained volume-based particle size distribution is used._Ten, D₅₀, D₉₀Is calculated. About 10 mg of particles were added to 10 ml of methanol and dispersed for 2 minutes with an ultrasonic disperser, and then measured under the conditions of a measurement time of 90 seconds and a single measurement.
[0061]
In the toner of the present invention, the content of the conductive fine particles is preferably 0.1 to 5.0% by mass (more preferably 0.1 to 2.0% by mass) of the whole toner. By setting the content of the conductive fine particles in the above range, an appropriate amount of conductive fine particles for promoting charging of the image carrier can be supplied to the charging portion, and the recovery of the transfer residual toner particles can be achieved in development and cleaning. An amount of conductive fine particles necessary for the enhancement can be supplied onto the image carrier.
[0062]
When the content of the conductive fine particles of the toner is too smaller than the above range, the amount of the conductive fine particles supplied to the charging portion is likely to be insufficient, and it is difficult to obtain a stable charge-carrying effect of the image carrier. Even in image formation using development and cleaning, the amount of conductive fine particles present on the image carrier together with residual transfer toner particles tends to be insufficient, and it is difficult to improve the recovery of residual transfer toner particles. Further, when the content of the conductive fine particles in the toner is too larger than the above range, the excessive conductive fine particles are easily supplied to the charging portion, and a large amount of conductive fine particles that cannot be held in the charging portion is large. It becomes easy to produce the exposure defect by being discharged | emitted above. Further, the triboelectric charging property of the toner particles may be reduced or disturbed, which may cause a decrease in image density and an increase in fog. From such a viewpoint, the content of the conductive fine particles in the toner is preferably within the above range.
[0063]
As a production method for achieving the above-mentioned release rate, there are cases where the addition timing of inorganic fine particles and conductive fine particles added to the toner and the processing conditions (mixing strength, mixing time, etc.) of the mixing device used at the time of addition are changed. Among these, it is desirable to appropriately adjust the two-stage processing conditions in which toner particles and inorganic fine particles are first added to the mixing device and then mixed and then the conductive fine particles are added, the blade shape, the mixing time, and the rotation speed.
[0064]
For example, Henschel mixer (made by Mitsui Mining); Super mixer (made by Kawata); Ribocorn (made by Okawara Seisakusho); Nauter mixer, turbulizer, cyclomix (made by Hosokawa Micron) A spiral pin mixer (manufactured by Taiheiyo Kiko Co., Ltd.) and a Ladige mixer (manufactured by Matsubo Co., Ltd.).
[0065]
There are many methods for evaluating the fluidity that is one of the characteristics of the toner, but Carr is used as an index for comprehensively evaluating the fluidity of the powder based on data on several phenomena and characteristics related to the fluidity. There is a jet nature index. When toner adheres to the contact charging member, if the toner remains attached without being removed, problems such as fusion to the charging member and scraping of the photosensitive member are caused. Since the surface of the charging member fused with the toner becomes highly resistant, even if metal compound fine particles with a large specific surface area and a large number of contact points are used, the effect of maintaining the charging property is exhibited to some extent, but only the effect Is not enough. As a more preferable situation, the adhesion force between the contaminated toner and the charging member surface is loosened due to vibration or the like when the contact charging member is driven, and the contaminated toner is excluded on the photosensitive member by an electric field due to a potential difference between the member surface and the photosensitive member. It is to be done. For this purpose, it is preferable to use a toner that smoothly transitions from a static state to a fluid state.
[0066]
The jetability index is a measure of the likelihood of the flushing phenomenon. Flushing means that a fluid whose fluidity has been lowered in a stationary state becomes a fluid state like a liquid when it starts to flow due to vibration. It means that the higher the jet property index value, the higher the jet property of the toner powder.
[0067]
In the present invention, the jetability index was measured by the following method.
[0068]
Using a powder tester P-100 (manufactured by Hosokawa Micron Corporation), parameters of repose angle, collapse angle, difference angle, degree of compression, degree of aggregation, spatula angle and degree of dispersion are measured. The values obtained for each were applied to the Carr jetability index table, converted into respective indices of 25 or less, and the sum of the indices obtained from each parameter was calculated as the fluidity index / jetability index. The measurement method of each parameter is shown below.
[0069]
▲ 1 angle of repose
150 g of toner is deposited on a circular table of direct 8 cm through a mesh having a mesh size of 710 μm. At this time, the toner is deposited so that the toner overflows from the end of the table. The angle of repose was determined by measuring the angle formed between the ridge line of the toner deposited on the table and the circular table surface with a laser beam.
[0070]
(2) Compression degree
The degree of compression can be determined from the loosely packed bulk density (loose apparent specific gravity A) and the tapping bulk density (hardened apparent specific gravity P).
Compressibility (%) = 100 (PA) / P
○ Lack apparent specific gravity measurement method 150 g of toner is gently poured into a cup having a diameter of 5 cm, a height of 5.2 cm, and a capacity of 100 cc. When the measurement cup is filled with toner, the surface of the toner is ground, and the loose apparent specific gravity is calculated from the amount of toner filled in the cup.
○ Measurement method of solid apparent specific gravity Add the attached cap to the measuring cup used for loose apparent specific gravity. Fill the cup with toner and tap the cup 180 times. When tapping is complete, remove the cap and remove excess toner from the cup. The solid apparent specific gravity is calculated from the amount of toner filled in the cup.
[0071]
The apparent specific gravity value is inserted into the compression degree formula to obtain the compression degree.
[0072]
▲ 3 ▼ Spatula corner
Place the bottom of the 10 cm x 15 cm bat against the 3 cm x 8 cm spatula. Deposit toner on the spatula. At this time, the toner is deposited so as to rise on the spatula. Then, only the bat is gently lowered, and the inclination angle of the toner side surface remaining on the spatula is measured with a laser beam. Then, after applying an impact once with a shocker attached to the spatula, the spatula angle is measured again. The average of this measured value and the measured value before giving an impact was calculated as a spatula angle.
[0073]
(4) Degree of aggregation
On the shaking table, sieves are set in the order of 250 μm, 150 μm, and 75 μm from the top. The vibration amplitude is 1 mm, the vibration time is 20 seconds, and 5 g of toner is gently put on it to vibrate. After the vibration stops, measure the weight remaining on each sieve.
(Amount of toner remaining on upper screen) ÷ 5 (g) × 100...
(Amount of toner remaining on the middle screen) ÷ 5 (g) × 100 × 0.6... B
(The amount of toner remaining on the lower screen) ÷ 5 (g) × 100 × 0.2... C
a + b + c = calculation degree (%)
[0074]
The value obtained from the parameters is converted into an index of 25 or less according to Tables 1 and 2 (cited from Chemical Engineering. Jan. 18.1965) of Carr's fluidity index and jetability index, and if these values are summed, Carr The liquidity index.
(1) + (2) + (3) + (4) = (Carr's liquidity index)
[0075]
(5) Collapse angle
After measuring the angle of repose, shock is applied three times with a shocker to the bat on which the circular table for measurement is placed. Thereafter, the angle of the toner remaining on the table is assumed using a laser beam, and the collapse angle is obtained.
[0076]
▲ 6 ▼ Difference angle
The difference between the angle of repose and the collapse angle is the difference angle.
[0077]
(7) degree of dispersion
10 g of toner is dropped as a lump onto a watch glass having a diameter of 10 cm from a height of about 60 cm. Then, the toner remaining on the watch glass is measured, and the degree of dispersion is obtained by the following equation.
Dispersity (%) = ((10− (amount of toner remaining on the plate)) × 10
[0078]
The sum of the index that can be converted from the values of (5), (6), and (7) and the index corresponding to the fluidity index value obtained above can be obtained as the jetability index from the aforementioned Carr table.
[0079]
When this measurement is performed, if the toner has good jet properties such that the jet property index is greater than 80, toner fusion to the charging member is unlikely to occur even in a cleanerless system including a contact charging step. The charging property maintaining effect by the metal compound fine particles according to the present invention is sufficiently exhibited. In particular, since the high fluidity and jet property are maintained even after being left for a long time in a high temperature and high humidity environment, the toner is uniformly conveyed even in the latter half of the durability, and a phenomenon such as fading hardly occurs.
[0080]
On the other hand, when a toner having a jetability index of 80 or less is used, the toner is fused to the charging member, and the charging performance tends to be reduced accordingly, and the refading is caused by the low jetness. And image degradation occurs. In the present invention, a more preferable jetability index is 82 or more. Particularly preferred is a toner of 84 or more.
[0081]
[Table 1]

[0082]
[Table 2]

[0083]
The conductive fine particles according to the present invention have a specific surface area (cm²/ Cm^Three) Is 5 × 10^Five100 × 10 or more^FiveThe following is desirable. The number of contacts is 1 when a particle that is generally assumed to be spherical contacts a member that is assumed to be substantially planar. This also applies to the contact between the conductive fine particles and the charging member or toner particles. Therefore, in order to increase the number of contact points with the toner particles and the charging member, if many irregularities are formed on the surface of the material, the number of contact portions increases, and the number of contact points can be increased. However, for example, forming a large number of irregularities on the surface of the toner particles is not preferable in terms of frictional charging characteristics. On the other hand, it is preferable to form irregularities on the surface of the conductive fine particles because the contact point with not only the toner particles but also the charging member is increased, so that the design of the charging member itself is more flexible.
[0084]
In other words, forming and using a large number of irregularities on the surface of the conductive fine particles can be said to be a technology that can be applied in a wide range without requiring special specifications for the printer body and the toner used.
[0085]
As an index of the number of irregularities on the particle surface, the specific surface area of the particle powder is usually used. However, the specific surface area generally used is the unit "cm²As can be seen from “/ g”, it is the surface area per unit mass, and it is not easy to compare or optimize materials having different specific gravities in the discussion using this numerical value.
[0086]
Therefore, the present inventors have a physical property corresponding to the surface area per fine particle as the specific surface area, “cm²/ Cm^ThreeThe unit was adopted, and the relationship between the number of contact points between the conductive fine particles, the toner and the charging member, and the image characteristics and chargeability was intensively studied.
[0087]
Specific surface area of conductive fine particles contained in toner used (cm²/ Cm^Three) Is 5 × 10^Five100 × 10 or more^FiveIn the following cases, it has been found that the chargeability and image characteristics are greatly improved, and in particular, in an image forming method including a direct injection charging mechanism, good chargeability can be maintained even if the charging member is contaminated. This is believed to be due to the effect of increasing the number of contact points between the metal compound fine particles, the toner and the charging member. However, if the specific surface area is too large, that is, if there are too many surface protrusions, the adhesion to the toner is too strong, so that it moves with the toner onto the transfer medium and does not remain on the photoreceptor. Accordingly, the effect of improving the charging property is lowered. Preferably 10 × 10^Five80 × 10 or more^FiveMore preferably 12 × 10^Five40 × 10 or more^FiveBy making the following, the chargeability and image characteristics are further improved.
[0088]
Here, the specific surface area of the metal compound fine particles was determined as follows.
[0089]
First, according to the BET method, nitrogen gas is adsorbed on the sample surface using a specific surface area measuring device “Gemini 2375 Ver. 5.0” (manufactured by Shimadzu Corporation), and the BET specific surface area (cm²/ G).
[0090]
Next, true density (g / cm) using a dry automatic densimeter “Acupyc 1330” (manufactured by Shimadzu Corporation)^Three) At this time, 10cm^ThreeAs a sample pretreatment, helium gas purge is performed 10 times at a maximum pressure of 19.5 psig. After that, as a pressure equilibrium judgment value as to whether or not the pressure in the container has reached equilibrium, the pressure fluctuation in the sample chamber is 0.0050 / min as a guide. Start and automatically measure true density. The measurement is performed 5 times, the average value is obtained, and the true density is obtained.
[0091]
Here, the specific surface area of the powder is obtained as follows.
Specific surface area (cm²/ Cm^Three) = BET specific surface area (cm²/ G) x true density (g / cm^Three)
[0092]
The preferred volume resistance of the metal compound fine particles according to the present invention is 1 × 10.^-1~ 1x10⁹Ωcm. 1 × 10⁹If it exceeds Ωcm, the effect of improving the chargeability is not expected when used in an image forming method including a contact charging step. Meanwhile, 1 × 10^-1If it is less than Ωcm, the triboelectric charging characteristics of the toner under high humidity will be hindered, and in addition to deterioration in developability, fogging and transferability will be deteriorated. For this reason, the effect of improving the chargeability by increasing the specific surface area cannot be seen.
[0093]
Here, the resistance of the particles is measured as follows.
[0094]
A cylindrical metal cell is filled with a sample, and electrodes are arranged up and down so as to contact the sample. A load of 686 kPa (7 kgf / cm) is applied to the upper electrode.²). In this state, a voltage V is applied between the electrodes, and the resistance (volume resistivity RV) of the present invention is measured from the current I (A) flowing at that time. At this time, the electrode area is S (cm²), Where the sample thickness is M (cm)
RV (Ωcm) = 100 V × S (cm²) / I (A) / M (cm)
It is. In the present invention, the contact area between the electrode and the sample is 2.26 cm.²And measured at a voltage V = 100V.
[0095]
The conductive fine particles according to the present invention desirably have at least tin oxide. In the embodiment of the present invention, a direct injection charging mechanism and a cleanerless are combined, and an organic photoreceptor in which a surface protective layer contains conductive tin oxide as a trap agent for injection charge is used. When the metal compound fine particles present at the contact portion between the photosensitive member and the charging member contain tin oxide, the direct injection charging property was good. This seems to be because the charge transfer from the metal compound fine particles to the trapping agent on the surface of the photoreceptor is faster between the elements with fewer barriers. Therefore, it is preferable that the metal compound fine particles contain at least tin oxide, and the content is preferably high.
[0096]
However, resistance control is not sufficient with fine metal compound fine particles containing about 100% by mass of ordinary tin oxide. Therefore, in the present invention, it is more preferable to use reduction-treated tin oxide as the metal compound fine particles, which has a high direct injection charging speed, a light color, and capable of appropriate resistance control.
[0097]
It is preferable to use the metal compound fine particles after applying an appropriate surface treatment from the viewpoint of improving the characteristics in a high temperature and high humidity environment. When the metal compound fine particles absorb moisture, problems such as (1) the effect of improving the triboelectric charging property of the toner is remarkably lowered and the image quality is lowered, and (2) the toner is easily detached from the charging member and the effect of improving the charging property is reduced. Cheap. In that sense, a silane compound is preferable because of high water repellency as a treatment agent for the hydrophobic treatment. Examples of the silane compound used for the hydrophobization treatment include hexamethyldisilazane, trimethylsilane, trimethylchlorosilane, trimethylethoxysilane, dimethyldichlorosilane, methyltrichlorosilane, and allyldimethyl as used for the surface treatment of inorganic fine particles. Chlorosilane, allylphenyldichlorosilane, benzyldimethylchlorosilane, bromomethyldimethylchlorosilane, α-chloroethyltrichlorosilane, β-chloroethyltrichlorosilane, chloromethyldimethylchlorosilane, triorganosilane mercaptan, trimethylsilyl mercaptan, triorgano Silyl acrylate, vinyldimethylacetoxysilane, dimethylethoxysilane, dimethyldimethoxysilane, diphenyldiethoxysilane, hexamethyl Examples include disiloxane, 1,3-divinyltetramethyldisiloxane, 1,3-diphenyltetramethyldisiloxane, and vinyltrimethoxysilane.
[0098]
Further, as the silicone oil used, for example, dimethyl silicone oil, methylphenyl silicone oil, α-methylstyrene modified silicone oil, chlorophenyl silicone oil, fluorine modified silicone oil, amino modified silicone oil and the like are particularly preferable.
[0099]
More preferably, these surface treatment agents are applied to tin oxide, and then subjected to temperature or mechanical treatment to firmly attach the treatment agent to the tin oxide surface.
[0100]
The conductive fine particles according to the present invention preferably have an aggregation degree of 70% or less. It is important that the conductive fine particles used in the present invention are present in a state of being liberated to some extent on the toner surface. Therefore, the conductive fine particles fly alone to the image carrier and are transported to the charging member to recharge the image carrier and the toner. At this time, the toner and conductive fine particles carried on the charging roller are discharged from the charging roller onto the image carrier by the collection sequence, and are collected on the development carrier. At this time, if the cohesiveness of the conductive fine particles is higher than 70%, the aggregation degree of the whole toner is increased, and the lump of the toner aggregate becomes large. As a result, since a large amount of toner is ejected onto the image carrier, a latent image cannot be written on the image carrier in the portion where the aggregate is present during laser exposure, and a white granular image is lost. . This is called shading. At this time, when printing is performed continuously, the toner remaining after transfer is particularly prominent because it tends to accumulate on the charging roller. When the degree of aggregation of the conductive fine particles is 60% or less, the discharged toner is less likely to aggregate and is present in a dispersed state on the image carrier. A good image without (light shielding) can be obtained.
[0101]
The method for measuring the degree of aggregation of the conductive fine particles is in accordance with the measurement of the degree of aggregation in the Carr jetability index of the toner.
[0102]
In the process cartridge used in the present invention, the space of the toner container for storing the toner is a first space in which a developing unit for forming a toner image from the electrostatic latent image with the toner is disposed on the side close to the image carrier. And a valve member that is divided into a second space far from the image carrier, and whose one end is swingable toward the first space at the boundary between the first space and the second space. It is characterized by having.
[0103]
Here, an embodiment of a developing device, an image forming apparatus, and a process cartridge according to the present invention will be specifically described with reference to the drawings. FIG. 1 is a schematic side view showing a configuration as one example of an embodiment of an image forming apparatus equipped with a process cartridge equipped with a developing device according to the present invention, and FIG. 2 is a configuration of the developing device of the embodiment in FIG. FIG. 3 is a diagram illustrating the movement of the valve member as viewed from the first space side in the developing device of the embodiment in FIG. 1, and FIG. 4 is a valve member in the developing device of the first embodiment. It is a figure explaining movement of.
[0104]
First, the configuration of the first embodiment of the developing device, the image forming apparatus, and the process cartridge according to the present invention will be described with reference to FIGS. In FIG. 1, reference numeral 1 denotes an electrophotographic photosensitive drum as an image carrier, which has an outer diameter of 30 mm and is provided with an OPC (organic photoconductor; organic photoconductive photoconductor; negative photoconductor) on its surface. Rotation is driven at a peripheral speed (process speed) of 50 mm / sec in the clockwise direction of FIG.
[0105]
The material of the charging roller 2 is not limited to the elastic foam, and as the material of the elastic body, EPDM (ethylene-propylene-diene terpolymer), urethane, NBR (nitrile butadiene rubber), silicone rubber, In addition, a rubber material in which a conductive material such as carbon black or a metal oxide is dispersed to adjust resistance in an IR (dispersion type infrared spectrophotometer) or the like, and those obtained by foaming these materials are exemplified. It is also possible to adjust the resistance using an ion conductive material without dispersing the conductive substance.
[0106]
The charging roller 2 is disposed in pressure contact with a photosensitive drum 1 as a member to be charged with a predetermined pressing force against elasticity. Reference numeral n denotes a charging contact portion that is a contact portion between the photosensitive drum 1 and the charging roller 2. In the present embodiment, the charging roller 2 is rotated in the clockwise direction of FIG. 1 so that the surface of the charging roller 2 and the surface of the photosensitive drum 1 are moved in opposite directions (counter direction) at the charging contact portion n. It was rotationally driven at a speed of 75 mm / sec.
[0107]
That is, the surface of the charging roller 2 as a contact charging member has a speed difference with respect to the surface of the photosensitive drum 1 as a member to be charged.
[0108]
A laser beam scanner (exposure device) (not shown) including a laser diode, a polygon mirror, and the like serving as image information writing means for forming an electrostatic latent image on a charging surface of the photosensitive drum 1 serving as an image carrier charged by the charging roller 2. Outputs a laser beam L whose intensity is modulated in accordance with a time-series electric digital pixel signal of target image information, and scans and exposes a uniformly charged surface of the photosensitive drum 1 that is rotationally driven by the laser beam L. . An electrostatic latent image corresponding to target image information is formed on the surface of the photosensitive drum 1 that is rotationally driven by the scanning exposure L.
[0109]
Reference numeral 4 denotes a developing device. The electrostatic latent image on the surface of the photosensitive drum 1 that is driven to rotate is supplied with toner 4d containing toner t (toner particles + inorganic fine particles) and conductive fine particles m by the developing device 4. The toner image is visualized and developed. The developing device 4 of the present embodiment is a reversal developing device using a magnetic one-component insulating toner (negative toner). A non-magnetic rotating developing sleeve 4a serving as a toner carrying / conveying member serving as a developing means includes a magnet roll 4b inside, and the developing sleeve 4a is coated with a toner 4d in a thin layer by a regulating blade 4c.
[0110]
The toner 4d is regulated in layer thickness with respect to the developing sleeve 4a by the regulating blade 4c, and is charged. The toner 4d coated on the developing sleeve 4a is conveyed to a developing portion (developing region portion) that is a portion facing the photosensitive drum 1 and the developing sleeve 4a by the rotation of the developing sleeve 4a.
[0111]
As a result, the electrostatic latent image on the photosensitive drum 1 side is developed with the toner 4d.
[0112]
In FIG. 1, reference numeral 5 denotes a medium resistance transfer roller as a contact transfer unit, and a transfer contact portion B is formed by pressing the photosensitive drum 1 with a predetermined pressure. A transfer material P as a recording medium is fed to the transfer contact portion B from a feeding portion (not shown) at a predetermined timing, and a predetermined transfer bias voltage is applied to the transfer roller 5 from a transfer bias application power source S3. Thus, the toner image on the photosensitive drum 1 side is sequentially transferred onto the surface of the transfer material P fed to the transfer contact portion B.
[0113]
That is, the transfer material P introduced into the transfer contact portion B is nipped and conveyed by the transfer contact portion B, and the toner image formed and supported on the surface of the photosensitive drum 1 that is rotationally driven to the surface side thereof. Are sequentially transferred by electrostatic force and pressing force.
[0114]
Reference numeral 6 denotes a fixing device such as a heat fixing method. The transfer material P that is fed to the transfer contact portion B and receives the transfer of the toner image on the photosensitive drum 1 side is separated from the surface of the photosensitive drum 1 that is rotationally driven, and is introduced into the fixing device 6. When the toner image is fixed, it is discharged out of the apparatus as an image formed product (print, copy).
[0115]
In the image forming apparatus of the present embodiment described above, the photosensitive drum 1 serving as an image carrier, the charging roller 2 serving as a charging unit, and the developing device 4 are other components (hereinafter referred to as “image forming”). The process cartridge is integrally formed in a frame independent of the “device main body”), and is configured to be detachable from the image forming apparatus main body.
[0116]
The image forming apparatus according to the present embodiment is cleanerless without a cleaning unit, and untransferred residual toner 4d remaining on the surface of the photosensitive drum 1 after the transfer of the toner image onto the transfer material P is removed by the cleaner. Instead, a toner recycling process system is used in which the developing device 4 is simultaneously cleaned (collected) by the developing device 4 through the charging roller 2 as the photosensitive drum 1 is rotated.
[0117]
By the way, the conductive fine particles m having conductivity contained in the toner 4d of the developing device 4 have an appropriate amount when the toner of the electrostatic latent image formed on the surface of the photosensitive drum 1 by the developing device 4 is developed. To the side.
[0118]
The toner image on the photosensitive drum 1 is attracted and transferred to the transfer material P side at the transfer contact portion 8 due to the influence of the transfer bias voltage, but the conductive fine particles m on the photosensitive drum 1 are electrically conductive. Therefore, it does not actively transfer to the transfer material P side, and remains substantially adhered and held on the photosensitive drum 1.
[0119]
Since the image forming apparatus of the toner recycling process does not use a cleaner, the transfer residual toner t and the conductive fine particles m remaining on the surface of the photosensitive drum 1 after the transfer are charged with the photosensitive drum 1 and a contact charging member. The photosensitive drum 1 is carried as it is by the rotation of the photosensitive drum 1 to the charging contact portion n with the roller 2 and adheres to and mixes with the charging roller 2.
[0120]
Accordingly, the charging bias voltage is applied to the charging roller 2 by the charging bias application power source S1 in a state where the conductive fine particles m are carried and interposed (exist) in the charging contact portion n between the photosensitive drum 1 and the charging roller 2. Is applied and the photosensitive drum 1 is contact-charged.
[0121]
In the initial stage of printing, since the conductive fine particles m are not supplied to the surface of the charging roller 2 and charging cannot be performed, it is necessary to apply the conductive fine particles m to the surface of the charging roller 2 in advance.
[0122]
Even when the toner 4d adheres to and mixes with the charging roller 2 due to the presence of the conductive fine particles m, the contact charging member can be maintained as the contact roller with respect to the photosensitive drum 1 and the contact charging member becomes the charging roller 2. In addition, the charging roller 2 can perform direct injection charging of the photosensitive drum 1 regardless of contamination by the transfer residual toner 4d of the charging roller 2.
[0123]
That is, the charging roller 2 is in close contact with the photosensitive drum 1 through the conductive fine particles m, and the conductive fine particles m present at the charging contact portion n between the charging roller 2 and the photosensitive drum 1 are transferred to the photosensitive drum. By rubbing the surface of 1 without gaps, the charging of the photosensitive drum 1 by the charging roller 2 is dominated by stable and safe direct injection charging without using a discharge phenomenon due to the presence of the conductive fine particles m. High charging efficiency that cannot be obtained by roller charging or the like is obtained, and a potential substantially equal to the voltage applied to the charging roller 2 can be applied to the photosensitive drum 1.
[0124]
Further, the transfer residual toner 4d adhering to and mixed in the charging roller 2 is gradually discharged from the charging roller 2 onto the photosensitive drum 1, and is moved to the developing portion facing the developing sleeve 4a as the surface of the photosensitive drum 1 moves. Finally, a toner recycling process in which the developing device 4 is simultaneously cleaned (collected) is performed.
[0125]
In the simultaneous development cleaning, as described above, the toner 4d remaining on the photosensitive drum 1 after the transfer is developed in the subsequent image forming process, that is, the photosensitive drum 1 is continuously charged and exposed to form a latent image. At the time of developing the latent image, the defogging bias V of the developing device 4, that is, the potential difference between the DC voltage applied to the developing device 4 and the surface potential of the photosensitive drum 1._backIs to be collected.
[0126]
In the case of reversal development as in the image forming apparatus according to the present embodiment, this simultaneous development cleaning includes an electric field for collecting the toner 4d from the dark portion potential of the photosensitive drum 1 to the developing sleeve 4a, and the photosensitive drum 1 from the developing sleeve 4a. This is done by the action of an electric field that causes the toner 4d to adhere to the bright portion potential.
[0127]
Even if the conductive fine particles m fall off from the charging roller 2, the image forming apparatus is operated, so that the conductive fine particles m contained in the toner 4d of the developing device 4 are transferred to the photosensitive drum 1 in the developing unit. The presence of the conductive fine particles m since the surface of the photosensitive drum 1 is moved to the surface of the surface and the charging roller 2 is carried to the opposite charging portion through the transfer contact portion 8 by the rotation of the photosensitive drum 1 and continuously supplied to the charging roller 2. Good chargeability due to is maintained stably.
[0128]
As described above, in the image forming apparatus of the contact charging method, the contact transfer method, and the toner recycling process, the charging roller 2 is used as the contact charging member, and the low application is performed regardless of the contamination of the charging roller 2 due to the transfer residual toner 4d. Ozone-less direct injection charging with voltage can be stably maintained over a long period of time, uniform chargeability can be given, and there is no obstruction due to ozone products, no obstruction due to poor charging, etc. An image forming apparatus can be obtained.
[0129]
The developer 4d used in the present embodiment is a mixture of the toner t and the conductive particles m at a certain ratio. However, the toner t and the conductive particles m are consumed depending on the printing ratio when the image is formed. Different.
[0130]
For example, when the printing rate is low, the conductive particles m are easily consumed. However, if the conductive particles m are consumed in advance, the charging performance is deteriorated even though the toner t still remains, and an image defect occurs.
[0131]
In order to prevent the prior consumption of the conductive particles m, the developer 4d is transported little by little to the developing sleeve 4a serving as a developer bearing member, and once the developer 4d transported to the vicinity of the developing sleeve 4a serving as the developer bearing member is transported. Don't put it back.
[0132]
In the cleanerless electrophotographic process as in this embodiment, the developer 4d that has returned to the development area as the transfer residual toner t is collected by the developing device 4, but the collected developer 4d is deteriorated. It is highly possible to avoid mixing with fresh toner t in the developer container 7 that has not yet been used for image formation.
[0133]
In the present embodiment, by allowing only the developer 4d to move from the second space 11 to the first space 10 of the developer container 7 of the developing device 4, the prior consumption of the conductive particles m can be prevented. It is possible to provide an image forming apparatus and a process cartridge free from image defects.
[0134]
The developer 4d used in the present embodiment is a mixture of the conductive particles m at a constant ratio with respect to the toner t. As described above, the consumption of the toner t and the conductive particles m depends on the printing ratio during image formation. Therefore, for example, if the conductive particles m are consumed in advance, the charging performance is deteriorated despite the toner t still remaining, and an image defect occurs.
[0135]
In the process cartridge, it is very inconvenient that the life of the process cartridge is exhausted even though the toner t remains. In order to prevent the prior consumption of the conductive particles m, the developer 4d is transported to the developing sleeve 4a little by little, and the developer 4d once transported to the vicinity of the developing sleeve 4a is first space 10 in the vicinity of the developing sleeve 4a. Just keep it inside.
[0136]
In this embodiment, the valve member 9 is used in the boundary of the 1st space 10 and the 2nd space 11 as the concrete implementation method.
[0137]
Here, the valve configuration will be described in detail. The valve member 9 used in this embodiment is a thin resin film PET (polyethylene terephthalate). The thickness is preferably 100 μm or less, more preferably 80 μm or less.
[0138]
As shown in FIGS. 3 and 6, the valve member 9 is a partition wall 7 a having an opening 3 in which a longitudinal upper portion 9 a of the valve member 9 is provided between the first space 10 and the second space 11. The lower part is free and can be swung only to the first space 10 side.
[0139]
As shown in FIGS. 2 to 6, the valve member 9 may support the upper end portion 9 a in the longitudinal direction on either the first space side 10 or the second space side 11 of 7 a. This may be appropriately changed depending on the thickness of the valve member, the thickness of the stirring member, the stirring speed, the amount of the stirring blade entering the first space, and the like.
[0140]
With the above configuration, the toner can be smoothly swung from the second space 11 to the first space 10 and the toner can be prevented from flowing backward from the first space to the second space. Can do.
[0141]
When the first space 10 has room, the developer 4d in the second space 11 of the developer container 7 is pressed and agitated by a stirring member 12 serving as a transport stirring means for transporting and stirring, as shown in FIG. Then, the valve member 9 swings toward the first space 10, and the developer 4 d moves from the second space 11 to the first space 10.
[0142]
On the other hand, when the first space 10 has no room, the valve member 9 does not move toward the first space 10 as shown in FIG. 4B, and therefore the developer 4d does not move. Further, when the developer 4d moves from the second space 11 to the first space 10, the density of the developer 4d in the first space 10 temporarily increases, and the rotation of the developing sleeve 4a causes the first space 10 to rotate. 4D, the developer 4d is circulated as shown by the arrow in FIG. 4C, and a force for pushing the developer 4d back into the second space 11 is generated.
[0143]
Then, as shown in FIG. 4D, the valve member 9 swings in a direction that prevents the developer 4d from moving from the first space 10 to the second space 11, and the first space 10 and the second space 10 are moved. Since the opening 3 which is the movement path of the developer 4d with respect to the space 11 is blocked, the developer 4d can be prevented from moving from the first space 10 to the second space 11.
[0144]
At this time, the opening width of the opening 3 is preferably 20 mm or less. A more preferable range at this time is 10 mm or less.
[0145]
When the opening is larger than 20 mm, the swinging length of the valve member is too long, so the opening width at the time of opening the valve becomes large, and the toner easily flows back from the first space 10 to the second space 11 when the valve is opened. Become. In addition, it becomes difficult to supply a small amount of toner, and problems such as fogging and shading occur in the second half of the long-term durability.
[0146]
When the opening width of the opening 3 is 20 mm or less, particularly preferably 10 mm or less, the toner does not flow backward, and a stable small amount of toner can be supplied. As a result, a good image can be obtained without causing deterioration of fog and light shielding in the long-term durability.
[0147]
In addition, the valve member 9 may be of a type in which the tip of the stirring member 12 contacts the valve member 9 and swings with a predetermined intrusion amount, and the valve member 9 and the stirring member 12 are not in direct contact with each other. A system in which the valve member 9 is indirectly pushed and swung by the developer 4d pushed out by the stirring member 12 may be used.
[0148]
In the present invention, the inorganic fine particles are not only added to improve the fluidity of the toner by adhering to the surface of the toner particles and to uniformly charge the toner particles, but also the conductive fine particles in the toner particles. In addition, the conductive fine particles are uniformly distributed on the image bearing member.
[0149]
In the present invention, the number average particle size of the primary particles of the inorganic fine particles can be measured as follows. That is, a photograph of a toner magnified by a scanning electron microscope and a photograph of a toner mapped with elements contained in inorganic fine particles by an elemental analysis means such as an X-ray microanalyzer (XMA) attached to the scanning electron microscope. In contrast, the number average particle diameter can be determined by measuring 100 or more primary particles of inorganic fine particles adhering to or leaving the toner particle surface.
[0150]
In the present invention, the inorganic fine particles preferably contain at least one selected from silica, titania (titanium oxide) and alumina having a primary particle number average particle size of 4 to 80 nm. For example, as the silica fine particles, both a so-called dry method produced by vapor phase oxidation of silicon halide or dry silica called fumed silica, and so-called wet silica produced from water glass or the like can be used. There are few silanol groups on the surface and inside the silica fine powder, and Na₂O, SO^3-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.
[0151]
In the present invention, the inorganic fine particles are preferably subjected to a hydrophobic treatment. Hydrophobic treatment of inorganic fine particles prevents deterioration of the chargeability of inorganic fine particles in a high-humidity environment, and improves the environmental stability of the triboelectric charge amount of toner particles with inorganic fine particles adhering to the surface. It is possible to further improve the environmental stability of development characteristics such as image density and fog. By controlling the chargeability of the inorganic fine particles due to the environment and the fluctuation of the charge amount of the toner particles with the inorganic fine particles adhering to the surface, it is possible to prevent fluctuations in the ease of release of the conductive fine particles from the toner particles. The supply amount of the conductive fine particles onto the image carrier can be stabilized, and the environmental stability of the image carrier chargeability and transfer residual toner particle recoverability can be enhanced.
[0152]
As treatment agents for hydrophobic treatment, treatment agents such as silicone varnish, various modified silicone varnishes, silicone oil, various modified silicone oils, silane compounds, silane coupling agents, other organic silicon compounds, and organic titanium compounds may be used alone or in combination. And may be processed. Among these, the inorganic fine particles are particularly preferably those treated with at least silicone oil. The treatment can be performed according to a known method.
[0153]
Examples of the silane compound used for the hydrophobization treatment include hexamethyldisilazane, trimethylsilane, trimethylchlorosilane, trimethylethoxysilane, dimethyldichlorosilane, methyltrichlorosilane, allyldimethylchlorosilane, allylphenyldichlorosilane, and benzyl. Dimethylchlorosilane, bromomethyldimethylchlorosilane, α-chloroethyltrichlorosilane, β-chloroethyltrichlorosilane, chloromethyldimethylchlorosilane, triorganosilane mercaptan, trimethylsilyl mercaptan, triorganosilyl acrylate, vinyldimethylacetoxysilane, dimethylethoxy Silane, dimethyldimethoxysilane, diphenyldiethoxysilane, hexamethyldisiloxane, 1,3-divinyltetramethyl Examples include tildisiloxane and 1,3-diphenyltetramethyldisiloxane.
[0154]
The silicone oil has a viscosity at 25 ° C. of 10 to 200,000 mm.²/ S, even 3,000-80,000mm²/ S is preferred. If the viscosity of the silicone oil is too lower than the above range, the processing of the inorganic fine particles is not stable, and the processed silicone oil is detached, transferred or deteriorated by heat and mechanical stress, and the image quality is deteriorated. Tend. Moreover, when a viscosity is larger than the said range, there exists a tendency for the uniform process of an inorganic fine particle to become difficult.
[0155]
As the silicone oil used, for example, dimethyl silicone oil, methylphenyl silicone oil, α-methylstyrene modified silicone oil, chlorophenyl silicone oil, fluorine modified silicone oil and the like are particularly preferable.
[0156]
As a method for treating silicone oil, for example, inorganic fine particles treated with a silane compound and silicone oil may be directly mixed using a mixer such as a Henschel mixer, or a method of spraying silicone oil onto inorganic fine particles. It may be used. Alternatively, after dissolving or dispersing silicone oil in a suitable solvent, silica fine powder may be added and mixed to remove the solvent. A method using a sprayer is more preferable in that the formation of inorganic fine particle aggregates is relatively small.
[0157]
The treatment amount of the silicone oil is 1 to 23 parts by mass, preferably 5 to 20 parts by mass with respect to 100 parts by mass of the inorganic fine particles. If the amount of the silicone oil is too smaller than the above range, good hydrophobicity cannot be obtained, and if it is too large, problems such as fogging may occur.
[0158]
In the present invention, the inorganic fine particles are preferably those treated with silicone oil at the same time or after treatment with at least the silane compound. It is particularly preferable to use a silane compound for the treatment of the inorganic fine particles in order to increase the adhesion of the silicone oil to the inorganic fine particles and to make the hydrophobicity and chargeability of the inorganic fine particles uniform.
[0159]
As the treatment conditions for the inorganic fine particles, for example, a silylation reaction is performed as a first-stage reaction and silanol groups are eliminated by chemical bonds, and then a hydrophobic thin film is formed on the surface with silicone oil as a second-stage reaction. It is done.
[0160]
In the toner of the present invention, the content of inorganic fine particles is preferably 0.1 to 3.0% by mass of the whole toner. When the content of the inorganic fine particles is too small than the above range, the effect of adding the inorganic fine particles cannot be sufficiently obtained, and when the content is excessively larger than the above range, there are excessive inorganic fine particles with respect to the toner particles. The conductive fine particles are coated, and the behavior becomes the same as when the conductive fine particles have a high resistance, and the supply of the conductive fine particles onto the image carrier is reduced, and the charging effect of the image carrier is enhanced. There is a tendency that the effects of the present invention, such as a decrease and a decrease in recoverability of transfer residual toner, are impaired. The content of the inorganic fine particles is more preferably 0.3 to 2.0% by mass of the whole toner, and further preferably 0.5 to 1.5% by mass.
[0161]
The inorganic fine particles having a primary particle number average particle size of 4 to 80 nm used in the present invention have a specific surface area of 40 to 300 m by nitrogen adsorption measured by the BET method.²/ G is preferably within the range of 60 to 250 m.²/ G is more preferable. The specific surface area can be calculated using the BET multipoint method by adsorbing nitrogen gas to the sample surface using a specific surface area measuring device Autosorb 1 (manufactured by Yuasa Ionics Co., Ltd.) according to the BET method.
[0162]
As described above, in the present invention, the process cartridge having a configuration capable of controlling the supply state of the toner, which controls the jetability index of the toner and the release rate of the inorganic fine particles and conductive fine particles added to the toner from the toner. The toner is easily flushed in any environment with the conductive fine particles maintaining a high liberation rate, and the toner can be smoothly supplied when the valve is opened. As a result, even if it is durable for a long time in a high-temperature and high-humidity environment, the toner is supplied while maintaining high fluidity and a high release rate, so that fading does not occur easily, and toner recharging and recovery are smooth even in the latter half of the durability. Therefore, a good image can be formed through durability without causing deterioration of chargeability and light shielding.
[0163]
The toner of the present invention will be further described.
[0164]
From the viewpoint of storage stability, the resin composition according to the toner of the present invention has a glass transition temperature (Tg) of 45 to 80 ° C., preferably 50 to 70 ° C. When Tg is lower than 45 ° C., This may cause toner deterioration and offset during fixing. On the other hand, when Tg exceeds 80 ° C., fixability tends to decrease.
[0165]
As a method for measuring the glass transition temperature of the resin of the present invention, a differential thermal analysis measurement device (DSC measurement device), DSC-7 (manufactured by Perkin Elmer), EXSTAR6000, SSC / 5200 (manufactured by Seiko Instruments Inc.), DSC2920MDSC ( TA Instruments, etc.) can be used under the following conditions.
[0166]

[0167]
The binder resin component used in the present invention has a Mn (number average molecular weight) of 3000 to 20000 and a Mw (weight average molecular weight) of 50,000 to 500,000 in the molecular weight measured by GPC of the THF soluble component. It is preferable that it is the range of these. Within this range, the balance between fixability and durability is very good.
[0168]
These binder resin components can be mixed and dispersed in advance when the toner is produced. By mixing the wax component in advance, phase separation in the micro region is relaxed, and a good dispersion state is obtained.
[0169]
In the present invention, the molecular weight distribution of the toner or binder resin by GPC using THF (tetrahydrofuran) as a solvent is measured under the following conditions.
[0170]
The column is stabilized in a 40 ° C. heat chamber, and THF as a solvent is allowed to flow through the column at this temperature at a flow rate of 1 ml per minute, and about 100 μl of a sample THF solution is injected and measured. In measuring the molecular weight of a sample, the molecular weight distribution of the sample is calculated from the relationship between the logarithmic value of a calibration curve prepared from several types of monodisperse polystyrene standard samples and the number of counts. As a standard polystyrene sample for preparing a calibration curve, for example, a molecular weight of 10 manufactured by Tosoh Corporation or Showa Denko KK is 10²-10⁷It is appropriate to use a standard polystyrene sample of about 10 points. An RI (refractive index) detector is used as the detector. As the column, it is preferable to combine a plurality of commercially available polystyrene gel columns. For example, a combination of shodex GPC KF-801, 802, 803, 804, 805, 806, 807, and 800P manufactured by Showa Denko KK or TSKgel G1000H (H_XL), G2000H (H_XL), G3000H (H_XL), G4000H (H_XL), G5000H (H_XL), G6000H (H_XL), G7000H (H_XL), A combination of TSK guard column.
[0171]
The sample is prepared as follows.
[0172]
Put the sample in THF, leave it for several hours, then shake well and mix well with THF (until the sample is no longer united) and let stand for more than 12 hours. At this time, the sample is left in THF for 24 hours or longer. Thereafter, a sample processing filter (pore size 0.45 to 0.5 μm, for example, Mysori Disc H-25-5 manufactured by Tosoh Corp., Excro Disc 25CR manufactured by Gelman Science Japan Co., Ltd., etc.) can be used. This is a measurement sample. The sample concentration is adjusted so that the resin component is 0.5 to 5 mg / ml.
[0173]
As the kind of the binder resin in the present invention, styrene resin, styrene copolymer resin, polyester resin, polyol resin, polyvinyl chloride resin, phenol resin, natural modified phenol resin, natural resin modified maleic resin, acrylic resin, Examples include methacrylic resin, polyvinyl acetate, silicone resin, polyurethane resin, polyamide resin, furan resin, epoxy resin, xylene resin, polyvinyl butyral, terpene resin, coumarone indene resin, and petroleum resin.
[0174]
As a comonomer for the styrene monomer of the styrene copolymer, a styrene derivative such as vinyltoluene, acrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, dodecyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, acrylic Acrylic acid ester such as phenyl acid; Methacrylic acid ester such as methacrylic acid, methyl methacrylate, ethyl methacrylate, butyl methacrylate, octyl methacrylate; Maleic acid; Double such as butyl maleate, methyl maleate, dimethyl maleate Dicarboxylic acid ester having a bond; acrylamide, acrylonitrile, methacrylonitrile, butadiene; vinyl chloride; vinyl ester such as vinyl acetate and vinyl benzoate; ethylene, propylene, butylene Such ethylenic olefins, vinyl methyl ketone, such as vinyl vinyl hexyl ketone, vinyl methyl ether, vinyl ethyl ether, vinyl propionate ether. These vinyl monomers are used alone or in combination of two or more.
[0175]
The binder resin in the present invention preferably has an acid value in the range of 1 to 100 mgKOH / g. Particularly preferred is a resin having an acid value of 1 to 70 mgKOH / g. If it exceeds 70 mgKOH / g, the triboelectric charge amount under high humidity is insufficient, and if it is less than 1 mgKOH / g, the triboelectric charging rate under low humidity becomes slow.
[0176]
Examples of the monomer for adjusting the acid value of the binder resin include acrylic acid such as acrylic acid, methacrylic acid, α-ethylacrylic acid, crotonic acid, cinnamic acid, vinyl acetic acid, isocrotonic acid, and angelic acid, and α- β-alkyl derivatives, fumaric acid, maleic acid, citraconic acid, alkenyl succinic acid, itaconic acid, mesaconic acid, dimethyl maleic acid, dimethyl fumaric acid and other unsaturated dicarboxylic acids and monoester derivatives or anhydrides thereof, etc. Such a monomer can be made alone or mixed and copolymerized with other monomers to produce a desired polymer. Among these, it is particularly preferable to use a monoester derivative of an unsaturated dicarboxylic acid for controlling the acid value.
[0177]
More specifically, for example, monomethyl maleate, monoethyl maleate, monobutyl maleate, monooctyl maleate, monoallyl maleate, monophenyl maleate, monomethyl fumarate, monoethyl fumarate, monobutyl fumarate, monophenyl fumarate Monoesters of α, β-unsaturated dicarboxylic acids such as: monobutyl n-butenyl succinate, monomethyl n-octenyl succinate, monoethyl n-butenylmalonate, monomethyl n-dodecenyl glutarate, monobutyl n-butenyl adipate And monoesters of alkenyldicarboxylic acid such as
[0178]
The carboxyl group-containing monomer as described above may be added in an amount of 0.1 to 20 parts by mass, preferably 0.2 to 15 parts by mass, with respect to 100 parts by mass of all monomers constituting the binder resin.
[0179]
Examples of a polymerization method that can be used in the present invention as a method for synthesizing the binder resin of the present invention include a solution polymerization method, an emulsion polymerization method, and a suspension polymerization method.
[0180]
Among them, the emulsion polymerization method is a method in which a monomer (monomer) almost insoluble in water is dispersed as small particles in an aqueous phase with an emulsifier, and polymerization is performed using a water-soluble polymerization initiator. In this method, the reaction heat can be easily adjusted, and the termination reaction rate is low because the phase in which the polymerization is carried out (the oil phase consisting of the polymer and the monomer) and the aqueous phase are separate, resulting in a high polymerization rate. A product having a high degree of polymerization is obtained. Furthermore, the reason is that the polymerization process is relatively simple, and that the polymerization product is fine particles, so that it can be easily mixed with colorants, charge control agents and other additives in the production of toner. Therefore, there is an advantage as a method for producing a binder resin for toner.
[0181]
However, the added polymer is likely to be impure due to the added emulsifier, and an operation such as salting out is necessary to take out the polymer. Suspension polymerization is convenient to avoid this inconvenience.
[0182]
In suspension polymerization, it is good to carry out by 100 mass parts or less (preferably 10-90 mass parts) of monomers with respect to 100 mass parts of aqueous solvents. Examples of the dispersant that can be used include polyvinyl alcohol, partially saponified polyvinyl alcohol, calcium phosphate, and the like, and generally 0.05 to 1 part by mass with respect to 100 parts by mass of the aqueous solvent. The polymerization temperature is suitably 50 to 95 ° C., but is appropriately selected depending on the initiator used and the target polymer.
[0183]
The binder resin used in the present invention is preferably produced by using a polyfunctional polymerization initiator alone or in combination with a monofunctional polymerization initiator as exemplified below.
[0184]
Specific examples of the polyfunctional polymerization initiator having a polyfunctional structure include 1,1-di-t-butylperoxy-3,3,5-trimethylcyclohexane, 1,3-bis- (t-butylperoxy Isopropyl) benzene, 2,5-dimethyl-2,5- (t-butylperoxy) hexane, 2,5-dimethyl-2,5-di- (t-butylperoxy) hexane, tris- (t-butyl) Peroxy) triazine, 1,1-di-t-butylperoxycyclohexane, 2,2-di-t-butylperoxybutane, 4,4-di-t-butylperoxyvaleric acid-n-butyl ester , Di-t-butylperoxyhexahydroterephthalate, di-t-butylperoxyazelate, di-t-butylperoxytrimethyladipate, 2,2-bis- ( , 4-di-t-butylperoxycyclohexyl) propane, 2,2-t-butylperoxyoctane and various polymer oxides, etc., a functional group having a polymerization initiating function such as two or more peroxide groups in one molecule. And a polyfunctional polymerization initiator having a peroxide group in one molecule such as diallyl peroxydicarbonate, t-butylperoxymaleic acid, t-butylperoxyallylcarbonate and t-butylperoxyisopropyl fumarate And a polyfunctional polymerization initiator having both a functional group having a polymerization initiating function and a polymerizable unsaturated group.
[0185]
Of these, more preferred are 1,1-di-t-butylperoxy-3,3,5-trimethylcyclohexane, 1,1-di-t-butylperoxycyclohexane, di-t-butylperoxy. Hexahydroterephthalate, di-t-butylperoxyazelate and 2,2-bis- (4,4-di-t-butylperoxycyclohexyl) propane, and t-butylperoxyallyl carbonate.
[0186]
These polyfunctional polymerization initiators are preferably used in combination with a monofunctional polymerization initiator in order to satisfy various performances required as a binder for toner. In particular, it is preferable to use in combination with a polymerization initiator having a decomposition temperature of a half-life of 10 hours which is lower than the decomposition temperature for obtaining a half-life of 10 hours of the polyfunctional polymerization initiator.
[0187]
Specifically, benzoyl peroxide, 1,1-di (t-butylperoxy) -3,3,5-trimethylcyclohexane, n-butyl-4,4-di (t-butylperoxy) valerate, dichroic Organic peroxides such as milperoxide, α, α'-bis (t-butylperoxydiisopropyl) benzene, t-butylperoxycumene, di-t-butylperoxide, azobisisobutyronitrile, diazoamino Examples include azo and diazo compounds such as azobenzene.
[0188]
These monofunctional polymerization initiators may be added to the monomer at the same time as the polyfunctional polymerization initiator, but in order to keep the efficiency of the polyfunctional polymerization initiator appropriate, in the polymerization step, It is preferably added after the half-life indicated by the polyfunctional polymerization initiator has elapsed.
[0189]
These initiators are preferably used in an amount of 0.05 to 2 parts by mass with respect to 100 parts by mass of the monomer from the viewpoint of efficiency.
[0190]
It is also preferable that the binder resin is crosslinked with a crosslinking monomer.
[0191]
As the crosslinkable monomer, a monomer having two or more polymerizable double bonds is mainly used. Specific examples include aromatic divinyl compounds (eg, divinylbenzene, divinylnaphthalene, etc.); diacrylate compounds linked by alkyl chains (eg, ethylene glycol diacrylate, 1,3-butylene glycol diacrylate, 1,4 -Butanediol diacrylate, 1,5-pentanediol diacrylate, 1,6-hexanediol diacrylate, neopentyl glycol diacrylate, and acrylates of the above compounds replaced with methacrylate); alkyl chain containing an ether bond Diacrylate compounds (eg, diethylene glycol diacrylate, triethylene glycol diacrylate, tetraethylene glycol diacrylate, polyethylene glycol # 400 diacrylate, Ethylene glycol # 600 diacrylate, dipropylene glycol diacrylate, and acrylates of the above compounds in place of methacrylate); diacrylate compounds linked by a chain containing an aromatic group and an ether bond (eg, polyoxyethylene) (2) -2,2-bis (4-hydroxyphenyl) propane diacrylate, polyoxyethylene (4) -2,2-bis (4-hydroxyphenyl) propane diacrylate, and methacrylates of the above compounds Furthermore, polyester-type diacrylate compounds (for example, trade name MANDA (Nippon Kayaku)) are mentioned. As polyfunctional crosslinking agents, pentaerythritol acrylate, trimethylol ethane triacrylate, trimethylol propane triacrylate, tetramethylol propane triacrylate, tetramethylol methane tetraacrylate, oligoester acrylate, and acrylates of the above compounds are replaced with methacrylate. Triallyl cyanurate, triallyl trimellitate; and the like.
[0192]
These crosslinking agents are preferably used in the range of 0.00001 to 1 part by mass, preferably 0.001 to 0.05 part by mass, with respect to 100 parts by mass of the other monomer components.
[0193]
Among these crosslinkable monomers, aromatic divinyl compounds (especially divinylbenzene), diethers linked by a chain containing an aromatic group and an ether bond are preferably used from the viewpoint of toner fixing properties and offset resistance. Examples include acrylate compounds.
[0194]
As other synthesis methods, a bulk polymerization method and a solution polymerization method can be used. However, in the bulk polymerization method, a polymer having a low molecular weight can be obtained by polymerizing at a high temperature to increase the termination reaction rate, but there is a problem that the reaction is difficult to control. In that respect, the solution polymerization method can easily obtain a polymer with a desired molecular weight under mild conditions by utilizing the difference in chain transfer of radicals by a solvent and adjusting the amount of initiator and reaction temperature. Is preferable. In particular, a solution polymerization method under a pressurized condition is also preferable in that the amount of the initiator used is minimized and the influence of the remaining initiator is minimized.
[0195]
The composition of the polyester resin used in the present invention is as follows.
[0196]
Examples of the divalent alcohol component include ethylene glycol, propylene glycol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, diethylene glycol, triethylene glycol, 1,5-pentanediol, 1, 6-hexanediol, neopentyl glycol, 2-ethyl-1,3-hexanediol, hydrogenated bisphenol A, and bisphenol represented by the formula (E) and derivatives thereof;
[0197]
[Chemical 1]

(In the formula, R is an ethylene or propylene group, x and y are each an integer of 0 or more, and the average value of x + y is 0 to 10.)
And diols represented by the formula (F);
[0198]
[Chemical formula 2]

[0199]
Examples of the divalent acid component include benzene dicarboxylic acids such as phthalic acid, terephthalic acid, isophthalic acid, and phthalic anhydride or anhydrides thereof, lower alkyl esters; alkyl dicarboxylic acids such as succinic acid, adipic acid, sebacic acid, and azelaic acid. Acids or anhydrides thereof, lower alkyl esters; alkenyl succinic acids or alkyl succinic acids such as n-dodecenyl succinic acid and n-dodecyl succinic acid, or anhydrides, lower alkyl esters thereof; fumaric acid, maleic acid, citraconic acid, itaconic acid Dicarboxylic acids such as unsaturated dicarboxylic acids or anhydrides thereof, lower alkyl esters;
[0200]
Moreover, it is preferable to use together the trihydric or more alcohol component and trivalent or more acid component which work as a crosslinking component.
[0201]
Examples of the trihydric or higher polyhydric alcohol component include sorbitol, 1,2,3,6-hexanetetrol, 1,4-sorbitan, pentaerythritol, dipentaerythritol, tripentaerythritol, 1,2,4-butane. Triol, 1,2,5-pentanetriol, glycerol, 2-methylpropanetriol, 2-methyl-1,2,4-butanetriol, trimethylolethane, trimethylolpropane, 1,3,5-trihydroxybenzene, etc. Is mentioned.
[0202]
Examples of the trivalent or higher polycarboxylic acid component in the present invention include trimellitic acid, pyromellitic acid, 1,2,4-benzenetricarboxylic acid, 1,2,5-benzenetricarboxylic acid, 2,5, 7-naphthalenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, 1,2,4-butanetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,3-dicarboxyl-2-methyl-2-methylene Carboxypropane, tetra (methylenecarboxyl) methane, 1,2,7,8-octanetetracarboxylic acid, empole trimer acid, and their anhydrides, lower alkyl esters;
[0203]
[Chemical 3]

(Wherein X is an alkylene group or alkenylene group having 5 to 30 carbon atoms having one or more side chains having 3 or more carbon atoms)
And polycarboxylic acids such as anhydrides and lower alkyl esters thereof and derivatives thereof.
[0204]
The alcohol component used in the present invention is 40 to 60 mol%, preferably 45 to 55 mol%, and the acid component is 60 to 40 mol%, preferably 55 to 45 mol%. Moreover, it is preferable that the polyvalent component more than trivalence is 5-60 mol% in all the components.
[0205]
The polyester resin can also be obtained by a generally known condensation polymerization.
[0206]
The waxes used in the present invention include the following. For example, low molecular weight polyethylene, low molecular weight polypropylene, polyolefin copolymer, polyolefin wax, microcrystalline wax, paraffin wax, aliphatic hydrocarbon wax such as Fischer-Tropsch wax; oxide of aliphatic hydrocarbon wax such as oxidized polyethylene wax Or block copolymers thereof; plant waxes such as candelilla wax, carnauba wax, wax wax, jojoba wax; animal waxes such as beeswax, lanolin, spermaceti; mineral systems such as ozokerite, ceresin, petrolactam Waxes; waxes mainly composed of aliphatic esters such as montanic acid ester wax and castor wax; those obtained by partially or fully deoxidizing aliphatic esters such as deoxidized carnauba wax . Further, saturated linear fatty acids such as palmitic acid, stearic acid, montanic acid, or long-chain alkyl carboxylic acids having a long-chain alkyl group; unsaturated fatty acids such as brassic acid, eleostearic acid, and valinal acid; stearyl alcohol Saturated alcohol such as eicosyl alcohol, behenyl alcohol, cannavir alcohol, seryl alcohol, melyl alcohol, or alkyl alcohol having a long chain alkyl group; polyhydric alcohol such as sorbitol; linoleic acid amide, oleic acid amide, lauric acid Aliphatic amides such as acid amides; saturated aliphatic bisamides such as methylene bisstearic acid amide, ethylene biscapric acid amides, ethylene bislauric acid amides, hexamethylene bisstearic acid amides; Unsaturated fatty acid amides such as inamide, hexamethylenebisoleic acid amide, N, N′-dioleyl adipic acid amide, N, N′-dioleyl sebacic acid amide; m-xylene bisstearic acid amide, N, Aromatic bisamides such as N'-distearylisophthalamide; aliphatic metal salts such as calcium stearate, calcium laurate, zinc stearate and magnesium stearate (commonly referred to as metal soap); aliphatic hydrocarbons Wax grafted with a vinyl monomer such as styrene or acrylic acid; Partial esterified product of fatty acid and polyhydric alcohol such as behenic acid monoglyceride; Hydroxyl group obtained by hydrogenating vegetable oil Methyl ester compounds It is.
[0207]
In addition, these waxes have a sharp molecular weight distribution using a press sweating method, a solvent method, a recrystallization method, a vacuum distillation method, a supercritical gas extraction method or a melt liquid crystal deposition method, a low molecular weight solid fatty acid, a low molecular weight A solid alcohol, a low molecular weight solid compound, and other impurities are preferably used.
[0208]
Magnetic iron oxide may be used as the colorant of the present invention, in which case it can be used as a magnetic toner. As the magnetic iron oxide, iron oxides such as magnetite, maghemite, and ferrite are used, and the surface of the magnetic iron oxide is used. Or what contains a nonferrous element inside is preferable.
[0209]
When the present invention is applied as a magnetic toner, the magnetic iron oxide used therein preferably contains 0.05 to 10% by mass of a different element on the basis of the iron element. Especially preferably, it is 0.1-5 mass%.
[0210]
Moreover, it is preferable that these magnetic iron oxides contain 20-200 mass parts with respect to 100 mass parts of binder resin. More preferably, 50 to 120 parts by mass are contained.
[0211]
The different element is preferably an element selected from magnesium, aluminum, silicon, phosphorus, and sulfur. The following lithium, beryllium, boron, germanium, titanium, zirconium, tin, lead, zinc, calcium, barium, scandium, vanadium, chromium, manganese, cobalt, copper, nickel, gallium, cadmium, indium, silver element, Examples of the metal include palladium, gold, mercury, platinum, tungsten, molybdenum, niobium, osmium, strontium, yttrium, and technetium.
[0212]
These magnetic iron oxides preferably have a number average particle diameter of 0.05 to 1.0 μm, more preferably 0.1 to 0.5 μm. Magnetic iron oxide has a BET specific surface area of 2-40m²/ G (more preferably 4 to 20 m²/ G) is preferably used. There is no restriction | limiting in particular in a shape, The thing of arbitrary shapes is used. As magnetic characteristics, saturation magnetization is 10 to 200 Am under a magnetic field of 795.8 kA / m.²/ Kg (more preferably 70-100 Am²/ Kg), residual magnetization 1-100 Am²/ Kg (more preferably 2-20 Am²/ Kg) and a coercive force of 1 to 30 kA / m (more preferably 2 to 15 kA / m) are preferably used.
[0213]
Further, when a magnetic toner is used as the toner of the present invention, the density of the magnetic toner is 1.3 to 2.2 g / cm.^ThreeIt is desirable that Furthermore, 1.5 to 2.0 g / cm^ThreeIt is preferable that it is the range of these. The mass (density) of the magnetic toner correlates with the magnetic force, electrostatic force, and gravity acting on the magnetic toner particles. When the density of the magnetic toner is within this range, the action of magnetic iron oxide is appropriate. The balance between magnetic force and magnetic force is good, and excellent developing power can be exhibited.
[0214]
The density of the magnetic toner is 1.3 g / cm.^ThreeIf it is less than 1, the action of magnetic iron oxide on the magnetic toner is weak, so the magnetic force is low. For this reason, the electrostatic force for flying to the photosensitive drum at the time of development is superior, resulting in an excessive development state, leading to an increase in fog and consumption. Conversely, the magnetic toner density is 2.2 g / cm.^ThreeIf it is too high, the magnetic iron oxide acts on the magnetic toner and the magnetic force is superior to the electrostatic force. The strong magnetic force action is large and the specific gravity is heavy. This leads to low image density and image degradation.
[0215]
In some cases, the magnetic iron oxide used in the magnetic toner of the present invention may be treated with a silane coupling agent, a titanium coupling agent, titanate, aminosilane, or the like.
[0216]
The toner of the present invention preferably contains a charge control agent.
[0217]
Examples of the toner that controls the negative charge include the following compounds.
[0218]
Organic metal complexes and chelate compounds are effective, and examples include monoazo metal complexes, acetylacetone metal complexes, aromatic hydroxycarboxylic acids, and aromatic dicarboxylic acid metal complexes. Others include aromatic hydroxycarboxylic acids, aromatic mono- and polycarboxylic acids and their metal salts, anhydrides, esters, and phenol derivatives of bisphenol.
[0219]
Among these, an azo metal complex represented by the following formula (I) is preferable.
[0220]
[Formula 4]

[In the formula, M represents a coordination center metal, and examples thereof include Sc, Ti, V, Cr, Co, Ni, Mn, and Fe. Ar is an aryl group, which is an aryl group such as a phenyl group or a naphthyl group, and may have a substituent. In this case, examples of the substituent include a nitro group, a halogen group, a carboxyl group, an anilide group, an alkyl group having 1 to 18 carbon atoms, and an alkoxy group having 1 to 18 carbon atoms. X, X ', Y and Y' are -O-, -CO-, -NH-, -NR- (R is an alkyl group having 1 to 4 carbon atoms). C⁺Represents a counter ion, and represents hydrogen, sodium, potassium, ammonium, aliphatic ammonium, or a mixed ion thereof. ]
[0221]
In particular, the central metal is preferably Fe, the substituent is preferably a halogen, an alkyl group or an anilide group, and the counter ion is preferably hydrogen, an alkali metal, ammonium or aliphatic ammonium. A mixture of complex salts having different counter ions is also preferably used.
[0222]
The following compounds are used to control the toner to be positively charged.
[0223]
Nigrosine modified products such as nigrosine and fatty acid metal salts; quaternary ammonium salts such as tributylbenzylammonium-1-hydroxy-4-naphthosulfonate, tetrabutylammonium tetrafluoroborate, and analogs such as phosphonium salts Onium salts and lake pigments thereof; triphenylmethane dyes and lake pigments thereof (as rake agents, phosphotungstic acid, phosphomolybdic acid, phosphotungsten molybdic acid, tannic acid, lauric acid, gallic acid, ferricyanide, Ferrocyanide, etc.); metal salt of higher fatty acid; diorganotin oxide such as dibutyltin oxide, dioctyltin oxide, dicyclohexyltin oxide; dibutyltin borate, dioctyltin borate, di Black hexyl scan such diorgano tin borate such tin borate; guanidine compounds; imidazole compounds. These can be used alone or in combination of two or more. Among these, triphenylmethane compounds and quaternary ammonium salts whose counter ions are not halogen are preferably used. The following formula (II)
[0224]
[Chemical formula 5]

[In the formula, R₁Is H or CH_ThreeR₂And R_ThreeRepresents a substituted or unsubstituted alkyl group (preferably C1 to C4). ]
A copolymer with a polymerizable monomer such as styrene, acrylic acid ester or methacrylic acid ester described above can be used as a positive charge control agent. In this case, the homopolymer and copolymer have a function as a charge control agent and a function as a binder resin (all or a part thereof).
[0225]
As a method of incorporating a charge control agent into the toner, there are a method of adding it inside the toner particles and a method of adding it externally. The amount of these charge control agents used is determined by the toner production method including the type of binder resin, the presence or absence of other additives, and the dispersion method, and is not uniquely limited. Preferably, it is used in the range of 0.1 to 10 parts by mass, more preferably 0.1 to 5 parts by mass with respect to 100 parts by mass of the binder resin.
[0226]
As a method for producing the toner of the present invention, the above-described toner constituent materials are sufficiently mixed by a ball mill or other mixer, and then kneaded well using a heat kneader such as a hot roll kneader or an extruder, and then solidified by cooling. Thereafter, a method of obtaining toner by mechanically pulverizing and classifying the pulverized powder is preferable. In addition, a polymerization method in which a predetermined material is mixed with a monomer that constitutes the binder resin to obtain an emulsion suspension, followed by polymerization to obtain a toner; a so-called microcapsule toner comprising a core material and a shell material In which a predetermined material is contained in the core material, the shell material, or both of them; and a method of obtaining the toner by dispersing the constituent materials in the binder resin solution and then spray-drying. Further, the toner of the present invention can be produced by sufficiently mixing the desired additive and toner particles with a mixer using the various methods described above as required.
[0227]
For example, as a mixer, Henschel mixer (Mitsui Mining Co., Ltd.); Super mixer (Kawata Co., Ltd.); Ribocorn (Okawara Seisakusho Co., Ltd.); (Manufactured by Taiheiyo Kiko Co., Ltd.); Ladige mixer (manufactured by Matsubo Co., Ltd.), and kneading machines such as KRC kneader (manufactured by Kurimoto Iron Works); (Manufactured by Toshiba Machine Co., Ltd.); TEX twin-screw kneader (manufactured by Nippon Steel Works); PCM kneader (manufactured by Ikegai Iron Works Co., Ltd.); Mining company); MS pressure kneader, Nider Ruder (Moriyama Seisakusho); Banbury mixer (Kobe Steel) As a pulverizer, a counter jet mill, a micron jet, an inomizer (manufactured by Hosokawa Micron Co.); an IDS type mill, a PJM jet pulverizer (manufactured by Nippon Pneumatic Industry Co., Ltd.); a cross jet mill (manufactured by Kurimoto Iron Works Co., Ltd.); URMAX (manufactured by Nisso Engineering Co., Ltd.); SK Jet O Mill (manufactured by Seishin Enterprise Co., Ltd.); Kryptron (manufactured by Kawasaki Heavy Industries, Ltd.); Turbo Mill (manufactured by Turbo Industry Co., Ltd.); , Micron Classifier, Spedick Classifier (manufactured by Seishin Enterprise Co., Ltd.); Turbo Classifier (Nisshin Engineering Co., Ltd.); Micron Separator, Turboplex (ATP), TSP Separator (manufactured by Hosokawa Micron Co.); Elbow Jet (Nittetsu Mining) ), Disper Separator (manufactured by Nippon Pneumatic Kogyo Co., Ltd.); YM micro cut (manufactured by Yaskawa Shoji Co., Ltd.), and as a sieving device used for sieving coarse particles, Ultrasonic (manufactured by Koei Sangyo Co., Ltd.) Gyroshifter (manufactured by Deoksugakusha); Vibrasonic system (manufactured by Dalton); Soniclean (manufactured by Shinto Kogyo); Turbo screener (manufactured by Turbo Kogyo); Micro shifter (manufactured by Hadano Sangyo); Circular vibration A sieve etc. are mentioned.
[0228]
【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.
[0229]
[Production Example of Conductive Fine Particle A-1]
The acidic tin chloride aqueous solution was controlled at 60 to 80 ° C., and an aqueous ammonia solution was added thereto to generate a precipitate, followed by filtration and washing to obtain a slurry of conductive fine particles. The obtained slurry was dried and crushed, and then calcined at 500 ° C. for 2 hours in a nitrogen atmosphere and further at 500 ° C. for 1 hour in a nitrogen / hydrogen mixed gas atmosphere, and crushed again to obtain metal compound fine particles. . The obtained metal compound fine particles were surface-treated with 3.5 parts by mass of amino-modified silicone oil. As a surface treatment method, 100 parts by mass of metal compound fine particles and 3.5 parts by mass of amino-modified silicone oil diluted with toluene were added to a heating mixer, and the solvent was removed while stirring and mixing at 80 ° C. Thereafter, heat treatment was performed at 120 ° C. for 30 minutes while continuing mixing. After returning to room temperature, crushing treatment was performed. Regarding the physical properties of the obtained conductive fine particles A-1, the degree of aggregation was 35.2%, and the specific surface area was 55 × 10.^Fivecm²/ Cm^ThreeVolume resistance 6.0 × 10²Ωcm, D₅₀= 1.2 μm, D₉₀= 2.2 μm.
[0230]
[Production Example of Conductive Fine Particle A-2]
In Production Example 1 of metal compound fine particles, metal compound fine particles were produced by appropriately adjusting the tin chloride concentration, the addition rate of the aqueous ammonia solution, the firing temperature and the firing time. In a heating mixer, 100 parts by weight of the metal compound fine particles were produced. On the other hand, a solution to which 3.2 parts by mass of methyl hydrogen silicone oil was added was stirred and mixed at 80 ° C., and after spraying, the temperature was further raised to 120 ° C. and a heat treatment was performed for 30 minutes. After taking out, it cooled to room temperature, crushed, and obtained the electroconductive fine particle A-2 which performed the surface treatment. Regarding the physical properties of the obtained conductive fine particles A-2, the degree of aggregation was 28.7% and the specific surface area was 30 × 10.^Fivecm²/ Cm^ThreeVolume resistance 7.5 × 10²Ωcm, D₅₀= 1.4 μm, D₉₀= 2.6 μm.
[0231]
[Production Example of Conductive Fine Particle A-3]
In Production Example 1 of conductive fine particles A-1, metal compound particles were produced by appropriately adjusting the tin chloride concentration, the addition rate of the aqueous ammonia solution, the firing temperature and the firing time, and 100 parts by weight of metal in the heating mixer. 1.7 parts by mass of methyl hydrogen silicone oil and 1.8 parts by mass of amino-modified silicone oil were mixed with the compound fine particles, and thereafter conductive fine particles A-3 were obtained in the same manner as in Production Example 1. Regarding the physical properties of the obtained conductive fine particles A-3, the degree of aggregation was 38.6%, and the specific surface area was 75 × 10.^Fivecm²/ Cm^ThreeVolume resistance 1.1 × 10^ThreeΩcm, D₅₀= 0.7 μm, D₉₀= 1.7 μm.
[0232]
[Production Example of Conductive Fine Particle A-4]
In Production Example 1 of conductive fine particles A-1, metal compound particles were produced by appropriately adjusting the tin chloride concentration, the addition rate of the aqueous ammonia solution, the firing temperature and the firing time, and 100 parts by weight of metal in the heating mixer. Conductive fine particles A-4 were obtained in the same manner as in the production example of the conductive fine particles A-1, except that the compound fine particles were surface-treated with 1.5 parts by mass of vinylsilane. Regarding the physical properties of the obtained conductive fine particles A-4, the degree of aggregation was 58.2%, and the specific surface area was 10 × 10.^Fivecm²/ Cm^ThreeVolume resistance 2.0 × 10^ThreeΩcm, D₅₀= 3.0 μm, D₉₀= 5.2 μm.
[0233]
[Production Example of Conductive Fine Particle A-5]
A hydrochloric acid aqueous solution having a pH of about 1 in which tin chloride and antimony chloride are mixed and dissolved so that the molar ratio of tin and antimony is 100: 7 is brought to 80 ° C., and an aqueous sodium hydroxide solution is added thereto to form a coprecipitate. Then, filtration and washing were performed to obtain a slurry of conductive fine particles. The obtained slurry was dried and crushed, then calcined at 500 ° C. for 3 hours, and crushed again to obtain metal compound fine particles. Regarding the physical properties of the obtained conductive fine particles A-5, the degree of aggregation was 77.8%, and the specific surface area was 3.7 × 10.^Fivecm²/ Cm^Three, Volume resistance 3.0 × 10Ωcm, D₅₀= 4.2 μm, D₉₀= 6.7 μm.
[0234]
[Production Example of Conductive Fine Particle A-6]
In the production example of conductive fine particles A-5, the particle diameter was changed to obtain conductive fine particles A-6. Regarding the physical properties of the obtained conductive fine particles A-6, the degree of aggregation was 99.4% and the specific surface area was 86 × 10.^Fivecm²/ Cm^Three, Volume resistance 5.3 × 10 Ωcm, D₅₀= 0.3 μm, D₉₀= 0.7 μm.
[0235]
Table 3 shows the physical properties of each conductive fine particle.
[0236]
[Table 3]

[0237]
[Toner Production Example 1]
Material composition
・ Binder resin 100 parts by mass
(Styrene-acrylic resin (glass transition temperature by DSC measurement: Tg: 58 ° C., acid value: 23.0 mg KOH / g, GPC: Mn (number average molecular weight) 7000, Mw (weight average molecular weight) 400000, monomer ratio: styrene 72.5 Parts by mass, 20 parts by mass of n-butyl acrylate, 7 parts by mass of mono-n-butyl malate, 0.5 parts by mass of divinylbenzene)
・ 95 parts by mass of magnetic iron oxide
(Average particle diameter: 0.20 μm, BET specific surface area: 8.0 m²/ G, coercive force: 3.7 kA / m, saturation magnetization: 82.3 Am²/ Kg, residual magnetization: 4.0 Am²/ Kg)
-Polyethylene wax (melting point 110 ° C) 4 parts by mass
・ Charge control agent (iron complex of azo compound) 2 parts by mass
The above compound was melt-kneaded with a biaxial extruder heated to 130 ° C., and the cooled kneaded product was ground by a hammer mill. The pulverization was performed by mechanical pulverization using a turbo mill (manufactured by Turbo Kogyo). The resulting finely pulverized product was subjected to strict classification and removal of ultrafine powder and coarse powder with a multi-division classifier (Elbow Jet Classifier manufactured by Nittetsu Mining Co., Ltd.) using the Coanda effect to obtain toner particles 1. The obtained toner particles 1 had a weight average diameter of 8.0 μm.
[0238]
next,
-Toner particle 1 100 parts by mass
-1.0 part by mass of hydrophobic silica B with a primary particle size of 12 nm
(BET115m hydrophobized with dimethyl silicone oil and hexamethyldisilazane²/ G)
-Conductive fine particles A-1 1.0 part by mass
A peripheral speed of 40 s for the above materials using a Henschel mixer FM10C / l (Mitsui Mining Co., Ltd.)^-1Was mixed for 2 minutes to obtain toner 1.
[0239]
[Production Method of Toner 2]
Similar to Toner Production Example 1, using toner particles, the amount of conductive fine particles and inorganic fine particles shown in Table 4 was used, and the peripheral speed was 65 s.^-1Was mixed for 2 minutes to obtain Toner 2.
[0240]
[Method for Producing Toner 4]
To 100 parts by mass of toner particles 1, 1.0% of hydrophobic silica is externally added at a peripheral speed of 70 s-1 for 2 minutes, and then 1.0 part by mass of conductive fine particles A-1 at a peripheral speed of 30 s-1. The toner 4 was obtained by mixing for 0.5 minutes.
[0241]
[Method for Producing Toner 5]
Similar to Toner Production Example 1, toner particles were used, and conductive fine particles and inorganic fine particles were added under the conditions shown in Table 4, and the peripheral speed was 70 s.^-1The toner 5 was obtained by performing the mixing process for 2 minutes twice.
[0242]
[Method for Producing Toner 6]
Similar to Toner Production Example 1, toner particles were used, and conductive fine particles and inorganic fine particles were added under the conditions shown in Table 4, and the peripheral speed was 70 s.^-1Was mixed for 2 minutes to obtain toner 6.
[0243]
[Production Method of Toner 7]
Similar to Toner Production Example 1, toner particles were used, and conductive fine particles and inorganic fine particles were added under the conditions shown in Table 4, and the peripheral speed was 50 s.^-1The toner 7 was obtained by performing the mixing process for 2 minutes twice.
[0244]
[Method for Producing Toner 8]
Similar to Toner Production Example 1, toner particles were used, and conductive fine particles and inorganic fine particles were added under the conditions shown in Table 4, and the peripheral speed was 40 s.^-1The toner 8 was obtained by performing the mixing process for 2 minutes twice.
[0245]
[Method for Producing Toner 9]
First, 1.0 part by mass of conductive fine particles A-1 is added to 100 parts by mass of toner particle 1 to obtain a peripheral speed of 70 seconds.^-1For 2 minutes, and after adding 5% hydrophobic silica B, the peripheral speed is 30 s.^-1Was mixed for 1 minute to obtain toner 9.
[0246]
[Method for Producing Toner 10]
Similar to Toner Production Example 1, toner particles were used, and conductive fine particles and inorganic fine particles were added under the conditions shown in Table 4, and the peripheral speed was 60 s.^-1The toner 10 was obtained by mixing for 2 minutes.
[0247]
[Method for Producing Toner 11]
Similar to Toner Production Example 1, toner particles were used, and conductive fine particles and inorganic fine particles were added under the conditions shown in Table 4, and the peripheral speed was 70 s.^-1The toner 11 was obtained by mixing for 2 minutes.
[0248]
Table 4 shows the physical properties and production conditions of each toner.
[0249]
[Table 4]

[0250]
[Photoconductor Production Example 1]
A 30 mm × 260.5 mm aluminum cylinder was used as a support, and a methanol solution of polyamide resin was applied thereon by a dipping method to provide an undercoat layer having a thickness of 0.5 μm.
[0251]
4 parts by mass of oxytitanium phthalocyanine pigment, 2 parts by mass of polyvinyl butyral resin, and 80 parts by mass of cyclohexanone were dispersed in a sand mill apparatus for about 4 hours. This dispersion was applied onto the undercoat layer to form a 0.2 μm charge generation layer.
[0252]
Next, 10 parts by mass of the triphenylamine compound and 10 parts by mass of the polycarbonate resin were dissolved in 100 parts by mass of monochlorobenzene. This solution was applied onto the charge generation layer and dried with hot air to form a charge transport layer having a thickness of 20 μm.
[0253]
Next, as a charge injection layer, 50 parts by mass of antimony-doped tin oxide fine particles surface-treated with silicone oil were dispersed in 150 parts by mass of ethanol, and further 20 parts by mass of polytetrafluoroethylene fine particles were added and dispersed. Thereafter, 150 parts by mass of a resol-type thermosetting phenol resin as a resin component was dissolved to obtain a preparation liquid.
[0254]
Using this prepared solution, a film was formed on the above charge transport layer by a dip coating method, and dried with hot air to form a charge injection layer to obtain a photoreceptor 1. At this time, the film thickness of the charge injection layer of the photosensitive member 1 is measured using an instantaneous multi-photometry system MCPD-2000 (manufactured by Otsuka Electronics Co., Ltd.) due to light interference because of the thin film, and the film thickness is 2 μm. there were. As another method for measuring the film thickness, the cross section of the film of the photoreceptor can be directly observed and measured with an SEM or the like.
[0255]
[Production Example 1 of Charging Member]
A SUS roller with a diameter of 6 mm and a length of 264 mm is used as a core, and a medium-resistance foamed urethane layer is formed on the core as a roller. Further, the charging member 1 having a diameter of 12 mm and a length of 234 mm was prepared as a flexible member by cutting and polishing to adjust the shape and surface properties.
[0256]
The obtained charging member 1 has a resistance value of 10^FiveThe hardness was Ωcm, and the hardness was 30 degrees in Asker C hardness.
[0257]
<Example 1>
FIG. 1 shows an overall schematic configuration of the image forming apparatus of this example. FIG. 1 shows a laser printer (recording apparatus) of a development simultaneous cleaning process (cleanerless system) using a transfer type electrophotographic process. It has a process cartridge from which a cleaning means such as a cleaning blade is removed, uses toner 1 as toner, and is arranged so that the toner layer on the toner carrier and the image carrier are not in contact with each other. Contact development is used.
[0258]
At this time, the opening width of the opening 3 was set to 9.2 mm, the valve end was supported on the second space side, and was swung to the first space side.
[0259]
The photoreceptor 1 as an image carrier is the one obtained in Production Example 1 of the photoreceptor, and is rotationally driven at a peripheral speed (process speed) of 94 mm / sec in the X direction of the arrow.
[0260]
As the contact charging member, the charging roller 2 obtained from Production Example 1 of the charging member described above is used. As shown in the figure, the charging roller 2 has a predetermined pressing force against the photoreceptor 1 against elasticity. They are arranged in pressure contact. Reference numeral n denotes a charging contact portion which is a contact portion between the photosensitive member 1 and the charging roller 2. In this example, the charging roller 2 is rotationally driven at a peripheral speed of 100% in the facing direction (arrow Y direction) at the charging contact portion n that is a contact surface with the photoreceptor 1. The surface of the charging roller 2 has a relative speed difference of 200% relative to the surface of the photoreceptor 1. Further, the coating amount is approximately 1 × 10 6 on the surface of the charging roller 2.^FourPiece / mm²The conductive fine particles A-1 are applied so as to be uniform.
[0261]
Further, a DC voltage of −650 V is applied as a charging bias to the cored bar 2a of the charging roller 2 from the charging bias application power source S1. In this example, the surface of the photoreceptor 1 is uniformly charged by a direct injection charging method to a potential (−630 V) substantially equal to the voltage applied to the charging roller 2.
[0262]
A laser beam scanner (exposure device) 3 including a laser diode, a polygon mirror, or the like, which is an exposure means, outputs laser light whose intensity is modulated in accordance with a time-series electric digital pixel signal of target image information. Then, the uniformly charged surface of the photoreceptor 1 is scanned and exposed. By this scanning exposure, an electrostatic latent image corresponding to target image information is formed on the surface of the rotating photosensitive member 1. The electrostatic latent image on the surface of the photoreceptor 1 is developed as a toner image by the developing device 4 as a developing unit.
[0263]
The developing device 4 of this example is a non-contact type reversal developing device using the toner 1 as the toner.
[0264]
As a toner carrier, a developing sleeve 4a in which a resin layer having a layer thickness of about 7 μm and a JIS centerline average roughness (Ra) of 1.0 μm having the following configuration is formed on an aluminum cylinder having a diameter of 16 mm blasted on the surface is used. A magnetic roll of 90 mT (900 gauss) of development magnetic pole is included, and an elastic blade 4c made of urethane having a thickness of 1.0 mm and a free length of 1.5 mm as a toner layer thickness regulating member is 29.4 N / m (30 g / cm). The contact was made with linear pressure. The gap between the photoreceptor 1 and the developing sleeve 4a was 290 μm.
・ Phenolic resin 100 parts by mass
・ 90 parts by mass of graphite (volume average particle size of about 7 μm)
・ 10 parts by mass of carbon black
[0265]
Further, the developing sleeve 4 a rotates at a peripheral speed of 120% of the peripheral speed of the photosensitive member 1 in the forward direction and the rotating direction of the photosensitive member 1 at a developing portion a (developing region portion) that is a portion facing the photosensitive member 1. Let
[0266]
The developing sleeve 4a is coated with a thin layer of toner by an elastic blade 24c. The layer thickness of the toner with respect to the developing sleeve 4a is regulated by the elastic blade 4c, and an electric charge is applied. At this time, the toner amount coated on the developing sleeve 4a is 16 g / m.²Met.
[0267]
The toner coated on the developing sleeve 4a is transported to the developing portion a which is a facing portion between the photosensitive member 1 and the developing sleeve 4a by the rotation of the developing sleeve 4a. A developing bias voltage is applied to the sleeve 4a from a developing bias applying power source S2. The development bias voltage is a DC voltage of −440V, a frequency of 1600 Hz, a peak-to-peak voltage of 1500 V (electric field strength of 5 × 10⁶V / m) rectangular alternating voltage was superimposed, and one-component jumping development was performed between the developing sleeve 4a and the photoreceptor 1 at the developing portion a.
[0268]
The transfer roller 5 having a medium resistance as a contact transfer means is brought into contact with the photosensitive member 1 with a linear pressure of 98 N / m (100 g / cm) to form a transfer contact portion b. The transfer contact portion b is fed with a transfer material P at a predetermined timing from a paper supply unit (not shown), and a predetermined transfer bias voltage is applied to the transfer roller 5 from a transfer bias application power source S3. The toner image on the body 1 side is sequentially transferred onto the surface of the transfer material P fed to the transfer contact portion b.
[0269]
In this example, the volume resistance value of the transfer roller 5 is 5 × 10.⁸Transferring was performed by applying a DC voltage of +2000 V using a Ωcm one. That is, the transfer material P introduced into the transfer contact portion b is nipped and conveyed by the transfer contact portion b, and the toner image formed and supported on the surface of the photosensitive member 1 on the surface side is successively subjected to electrostatic force. It is transferred by pressing force. The transfer material P that has been fed to the transfer contact portion b and has received the transfer of the toner image on the photosensitive member 1 side is separated from the surface of the photosensitive member, and is introduced into a fixing device 6 such as a heat fixing method as a fixing means. The toner image is fixed and discharged as an image formed product (print, copy) to the outside of the apparatus.
[0270]
In the image forming apparatus of this example, the cleaning means is removed, and residual toner remaining on the surface of the photoconductor 1 after the transfer of the toner image onto the transfer material P is not removed by the cleaner, and the photoconductor 1 is rotated. At the same time, it reaches the developing portion a via the charging contact portion n and is simultaneously cleaned (collected) by the developing device 4.
[0271]
Conventionally, since the toner is an insulator, the mixing of the untransferred toner into the charging contact portion n is a factor that causes a charging failure in charging the photosensitive member. However, even in this case, the metal compound fine particles m having a large BET value are present in the charging contact portion n between the photosensitive member 1 and the charging roller 2, so that the contact property and the contact resistance of the charging roller 2 to the photosensitive member 1 are high. Therefore, ozone-less direct charging can be stably maintained over a long period of time with a low applied voltage regardless of contamination of the charging roller 2 due to transfer residual toner, and uniform chargeability can be provided.
[0272]
Further, in this embodiment, the charging roller 2 is switched between the DC bias voltage and the AC voltage in series by switching the switch of the charging bias application power source by the sequence control circuit at the time of paper non-image recording. To the cored bar 2a
DC voltage: -650V
AC voltage: A rectangular wave superimposed voltage having a peak-to-peak voltage of 200 V and a frequency of 500 Hz is applied.
[0273]
In addition, during the interval between the sheets, the developing sleeve 4a of the developing device 4 is similar to that at the time of image recording.
DC voltage: -440V
AC voltage: A peak-to-peak voltage of 1500 V, a frequency of 1.6 kHz, and a rectangular wave superimposed voltage were applied.
[0274]
By maintaining these bias relationships, the toner that is negatively frictionally charged on the charging roller 2 is developed on the photosensitive member 1 (the toner on the charging roller 2 is discharged to the photosensitive member 1), and the toner is further developed. Can be recovered by the back contrast of the developing device 4.
[0275]
In this embodiment, the image forming apparatus is filled with 120 g of toner 1, and from the initial stage up to 1000 sheets, an image pattern composed of a grid pattern with a printing area ratio of 1%, and from 1001 to 2000 sheets, a horizontal line with a printing area of 3%. The toner cartridge was used until the amount of toner decreased. 75g / m as transfer material²A4 copy paper was used, and in a high-temperature and high-humidity environment (32.5 ° C, 80% RH), 1,000 sheets were printed intermittently for 15 seconds and a total of 2000 sheets were printed. The following evaluation was performed when the sample was left for a day after 2000 sheets. The results are shown in Table 5.
[0276]
[Evaluation]
A solid white image was taken for every 500 durability sheets, and the fog on paper was evaluated. The fog on the paper was measured using a REFECTMETER MODEL TC-6DS manufactured by Tokyo Denshoku. A green filter was used as the filter. The fog value was calculated from the following formula using a solid white image. If the fog on paper is 2.5% or less, a good image is obtained.
Fog (reflectance) (%) = reflectance on standard paper (%)-reflectance of sample non-image area (%)
[0277]
A solid black image was printed at the beginning of endurance, the 501st sheet, the 1001st sheet, the 1501st sheet, the 2nd day endurance initial stage, and the one day after the endurance, and the image density was evaluated. The image density was measured by averaging five points on a solid black image with a Macbeth densitometer RD918 (manufactured by Macbeth).
[0278]
The evaluation of fading was made based on whether or not the evaluation solid black image was partially thinned.
A: No fading
B: Fading after leaving for a day
C: Fading after 1500 sheets passed
D: 1000-sheet pass word fading
E: Fading after passing 500 sheets
[0279]
Evaluation of uneven charging
The charging unevenness was evaluated based on an image pattern in which the upper end portion (width 3 cm from the image front end portion) is a mixed image of a solid image and a non-image, and the portion after 3 cm from the image front end portion is a uniform halftone. When the amount of conductive fine particles present on the charging roller is reduced, the amount of conductive fine particles is insufficient at the nip portion between the charging roller and the photoreceptor. For this reason, the portion that cannot be recharged on the photosensitive member is not lowered in potential but only affected by laser exposure, and more toner is easily developed only in that portion. As a result, a black line such as a fine streak is generated particularly when the halftone portion is printed out. In this evaluation, a halftone image was printed for every 500 sheets to determine at which point charging unevenness occurred during endurance, and charging performance was evaluated.
A: There is no black streak through the endurance of 2000 sheets.
B: Generated after passing 1,500 sheets
C: Generated after 1000 sheets passed
D: Generated after passing 500 sheets
E: Seen from the initial through 500 sheets
[0280]
Evaluation of white spot (shading)
Evaluation of white spots was performed by printing 5 sheets of 1 dot 1 space pattern every 500 sheets durability and counting the number of white spots (shading).
A: Almost no white spots occur or less than 30 white spots
B: 31-50 white pots
C: 51-100 white pots
D: 101-200 white pots
E: White spots on the entire surface
[0281]
Evaluation of supply stability of conductive fine particles
After the endurance of 2000 sheets, the toner remaining in the second space and the first space of the cartridge was collected, and the amount of conductive fine particles was measured by measuring fluorescent X-rays. The apparatus used RIGKU RIX3000, and the amount of conductive fine particles was measured based on the Sn peak intensity under the condition of 50 kv and 70 mA.
[0282]
  <Example 24, Reference Example 1, Example 6 and7>
  Evaluation was performed in the same manner as in Example 1 using the toners 2 to 7 shown in Table 4 and the image forming apparatus shown in FIG. The evaluation results are shown in Table 5.
[0283]
<Comparative Example 1>
Using the toner 7 shown in Table 4, the image forming apparatus without the valve configuration shown in FIG. 7, the photoreceptor 1 described in Production Example 1 of the photoreceptor, and the charging roller 2 described in Production Example 1 of the charging member. Evaluation was performed in the same manner as in Example 1. The evaluation results are shown in Table 5. The opening width at this time was 30 mm.
[0284]
  <Comparative Example 2~ 3>
  Toner 8 listed in Table 4・ 92 and using the image forming apparatus shown in FIG. 2 and using the photoreceptor 1 described in Production Example 1 of the photoreceptor and the charging roller 2 described in Production Example 1 of the charging member, evaluation was performed in the same manner as in Example 1. went. The evaluation results are shown in Table 5.
[0286]
<Comparative Examples 4-5>
Using the toners 10 and 11 shown in Table 4 and the image forming apparatus shown in FIG. 2, using the photoreceptor 1 described in Production Example 1 of the photoreceptor and the charging roller 2 described in Production Example 1 of the charging member. Evaluation was performed in the same manner as in Comparative Example 1. The evaluation results are shown in Table 5.
[0287]
[Table 5]

[0288]
【The invention's effect】
According to the present invention, the jet property index of Carr of the toner is greater than 80, the weight average particle size of the toner is 5 μm or more and 12 μm or less, and the conductive fine particles have a volume-based median diameter (D₅₀) Is 0.4 μm or more and 4.0 μm or less and less than the mass average particle diameter of the toner,₉₀Is a conductive fine particle having a particle size of 6.0 μm or less, and the release rate a of the conductive fine particle to the toner particle and the release rate b of the inorganic fine particle are
Liberation rate b <release rate a
A first container in which a space of a toner container for storing toner is close to the image carrier and a developing unit for forming an electrostatic latent image with the toner is formed. The present invention is applied to an image forming apparatus that is divided into a second space far from the image carrier and that has a valve member that can swing at one end at the boundary between the first space and the second space. As a result, high image density and improved fog can be achieved without causing uneven charging and fading over a long period of time under high temperature and high humidity.
[Brief description of the drawings]
FIG. 1 is a schematic side view showing the configuration of a first embodiment of an image forming apparatus equipped with a process cartridge equipped with a developing device according to the present invention.
FIG. 2 is an explanatory cross-sectional view illustrating a configuration of a developing device according to a first embodiment.
FIG. 3 is a diagram illustrating the movement of the valve member as viewed from the first space side in the developing device of the first embodiment.
FIG. 4 is a diagram illustrating the movement of a valve member in the developing device according to the first embodiment.
FIG. 5 is an explanatory cross-sectional view showing a configuration of a second embodiment of the developing device according to the present invention.
FIG. 6 is a view showing the movement of the valve member as viewed from the first space side in the developing device of the second embodiment.
FIG. 7 is a diagram illustrating a conventional example.
[Explanation of symbols]
1 ... Photosensitive drum
2 ... Charging roller
2a ... Core
2b ... Middle resistance layer
3 ... Opening
4 ... Developing device
4a ... Developing sleeve
4b ... Magnet roll
4c ... Regulator blade
4d ... Toner
5 ... Transfer roller
6 ... Gap
7. Toner container
7a ... partition wall
9 ... Valve member
9a… Upper part
10 ... 1st space
11 ... second space
12 ... Stirring member
L ... Laser beam (scanning exposure)
a ... Developer
b: Transfer contact portion
m ... conductive fine particles
n: Charging contact part
P: Transfer material
S1: Charging bias application power source
S2: Power supply for developing bias application
S3: Transfer bias application power source
t ... toner

Claims (6)

Toner used in a developing device that supplies toner to an electrostatic latent image formed on a charged surface of an image carrier to visualize the toner image,
A developing unit is provided in which the space of the toner container for storing the toner in the developing device is close to the image carrier and the electrostatic latent image is visualized as a toner image by the toner. And a second space on the side far from the image carrier, and a valve member is provided at the boundary between the first space and the second space. And
The opening width of the opening between the first space and the second space is 20 mm or less,
A charging step in which a voltage is applied to the charging member to bring it into contact with the image carrier and charging; an electrostatic latent image forming step in which an electrostatic latent image is formed on the charged image carrier; and a toner carrier A developing step of transferring the carried toner to the electrostatic latent image held on the surface of the image carrier to form a toner image; and a toner image formed on the image carrier through an intermediate transfer member. In an image forming method including at least a transfer step of transferring to a transfer material without or intervening,
The image forming method does not have a cleaning step between the transfer step and the charging step,
The toner has at least toner particles, conductive fine particles, and inorganic fine particles. The toner has at least a binder resin and a colorant. The toner has a Carr jetting index greater than 80. The weight average particle diameter is 5 μm or more and 12 μm or less, and the conductive fine particles have a volume-based median diameter (D50) of 0.4 μm or more and 4.0 μm or less and less than the weight average particle diameter of the toner, and D90 is 6.0 μm. The following conductive fine particles, the release rate a of the conductive fine particles to the toner particles and the release rate b of the inorganic fine particles are:
And the liberation rate a is not less than 59% and not more than 95%, and
Image forming method, which comprises a lower Symbol step (1) and (2).
(1) As the charging step, a voltage is applied to the charging member with at least the conductive fine particles interposed in a nip portion that is a contact portion between the image carrier and a charging member that contacts the image carrier. (2) As the developing step, the electrostatic latent image is visualized and the toner remaining on the surface of the image carrier after the toner image is transferred to the transfer material. Development and cleaning process to collect ^2. The image forming method according to claim 1 , wherein the conductive fine particles have a specific surface area (cm ² / cm ³ ) of 5 × 10 ⁵ or more and 100 × 10 ⁵ or less. The image forming method according to claim 1 or 2, wherein the volume resistivity of the conductive fine particles is ^{1 × 10 -1 ~1 × 10 9} Ωcm. Conductive fine particles, an image forming method according to any one of claims 1 to 3, characterized in that it contains at least tin oxide. The image forming method according to any one of claims 1 to 4 the content of the conductive fine particles, characterized in that 0.1 to 5.0 wt% of the total toner. The image forming method according to any one of claims 1 to 5 aggregation degree of the conductive particles is equal to or less than 70%.

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