JP2004333681A - Development method, development apparatus, and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a development method capable of stably supplying high-grade images which are high in image density and in which a stripe unevenness, ghosts, blotches, toner contamination, etc., do not appear even at the time of repetitive image production, a development apparatus and an image forming apparatus. <P>SOLUTION: A quaternary ammonium salt compound of positive electrostatic chargeability to at least iron powder is contained in the top of a developer carrier in development using a developer in which the ratio occupied by particles of 0.6 to 1.0 μm in grain size in the grain size distribution by the diameter of the equivalent circle of the toner particles is <5.0% of the entire part on a number base. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

（式中のＲ_１，Ｒ_２，Ｒ_３，Ｒ_４は、各々、置換基を有しても良いアルキル基、置換基を有しても良いアリール基、アルアルキル基を表し、Ｒ_１〜４は各々同一でもあるいは異なっていてもよい。Ｘ⁻は酸の陰イオンを表す。）
【００２４】
これに対し、例えば下記式［化２］で表されるような、それ自身が鉄粉に対して負帯電性を有する含フッ素４級アンモニウム塩化合物についても検討を行ったが、該化合物の添加によっては本発明の所期の目的が達成されないことがわかった。即ち、下記式［化２］で表される化合物は、電子吸引性の強いフッ素樹脂原子が構造中にあるので、それ自身が鉄粉に対して負帯電性を有するが、本発明の場合と同様に、該化合物を樹脂中に分散させた樹脂組成物を結着樹脂とし、これを加熱乾燥させてキャリア芯材に被覆層を形成しても、それ自身が鉄粉に対して正帯電性である第４級アンモニウム塩化合物を含有させたほどには、効果は得られなかった。
【００２５】
【外２】

【００２６】
本発明に好適に用いられる、それ自身が鉄粉に対して正帯電性である第４級アンモニウム塩化合物としては、具体的には、以下のようなものが挙げられるが、勿論、本発明は、これらに限定されるものではない。
【００２７】
【外３】

【００２８】
【外４】

【００２９】
上記に示したような本発明で使用する第４級アンモニウム塩化合物の添加量は、結着樹脂１００部に対して１〜１００部とすることが好ましい。１部未満では添加による帯電付与性の向上が見られず、１００部を超えると結着樹脂中への分散不良となり被膜強度の低下を招きやすい。また樹脂分に対して余剰となった正帯電性の四級アンモニウム塩が存在してしまうため本発明の有効な効果が低下しはじめてしまう。本発明の被覆層に用いられる結着樹脂として特に限定はされないが、結着樹脂の一部又は全部がその分子構造中に少なくとも−ＮＨ_２基、＝ＮＨ基、もしくは−ＮＨ−結合のいずれかの構造を有していることが好ましい。このような樹脂を用いて被覆層を形成することで、本発明の効果が容易に発揮可能である。本発明において、現像剤担持体の樹脂層として上記のような構成のものを用いると、自身が負帯電付与性へと変化することについての明確な理由は定かではないが、本発明で用いる、それ自身が鉄粉に対して正帯電性である第４級アンモニウム塩化合物及び、−ＮＨ_２基、＝ＮＨ基、もしくは−ＮＨ−結合の少なくとも一つの構造を有している結着樹脂を用いて樹脂被覆層を形成することにより樹脂の構造中に第４級アンモニウム塩が取り込まれる。その際、正極性を有する第４級アンモニウム塩の元の構造が失われ、これらを取り込んだ樹脂の帯電性が均一且つ十分な負帯電性を有するようになるためではないかと考えられる。
【００３０】
−ＮＨ_２基を有する物質としては、Ｒ−ＮＨ_２で表される第１アミンもしくはそれらを有するポリアミン、ＲＣＯ−ＮＨ_２で表される第１アミドもしくはそれらを有するポリアミド等、＝ＮＨ基を有する物質としては、Ｒ＝ＮＨで表される第２アミンもしくはそれらを有するポリアミン、（ＲＣＯ）_２＝ＮＨで表される第２アミドもしくはそれらを有するポリアミド等、−ＮＨ−結合を有する物質としては、前述したポリアミン、ポリアミド等の他に−ＮＨＣＯＯ−結合を有するポリウレタン等が挙げられ、以上の物質を１種又は２種以上、あるいは共重合体として含有し、工業的に合成された樹脂が好適に用いられる。
【００３１】
それらのうち汎用性等の面から、アンモニアを媒体としたフェノール樹脂、ポリアミド樹脂、及びウレタン樹脂等が好ましい。フェノール樹脂としては、本発明者らが鋭意検討を重ねた結果、その製造工程において含窒素化合物を触媒として使用したフェノール樹脂を用いることで、加熱硬化時に該４級アンモニウム塩化合物がフェノール樹脂の構造中に取り込まれ易いことがわかった。そのためこのようなフェノール樹脂を現像剤担持体上の樹脂被覆層を構成する材料の１つとして用いることで、良好な現像装置が得られる。フェノール樹脂の製造工程において触媒として用いられる含窒素化合物としては、例えば酸性触媒としては、硫酸アンモニウム、燐酸アンモニウム、スルファミド酸アンモニウム、炭酸アンモニウム、酢酸アンモニウム、マレイン酸アンモニウムといった、酸のアンモニウムまたはアミノ塩類、また、塩基性触媒としては、アンモニア、或いはジメチルアミン、ジエチルアミン、ジイソプロピルアミン、ジイソブチルアミン、ジアミルアミン、トリメチルアミン、トリエチルアミン、トリ−ｎ−ブチルアミン、トリアミルアミン、ジメチルベンジルアミン、ジエチルベンジルアミン、ジメチルアニリン、ジエチルアニリン、ｎ，ｎ−ジ−ｎ−ブチルアニリン、ｎ，ｎ−ジアミルアニリン、ｎ，ｎ−ジ−ｔ−アミルアニリン、ｎ−メチルエタノールアミン、ｎ−エチルエタノールアミン、ジエタノールアミン、トリエタノールアミン、ジメチルエタノールアミン、ジエチルエタノールアミン、エチルジエタノールアミン、ｎ−ブチルジエタノールアミン、ジ−ｎ−ブチルエタノールアミン、トリイソプロパノールアミン、エチレンジアミン、ヘキサメチレンテトラアミン等のアミノ化合物、ピリジン、α−ピコリン、β−ピコリン、γ−ピコリン、２，４−ルチジン、２，６−ルチジン等のピリジン及びその誘導体、キノリン化合物、イミダゾール、２−メチルイミダゾール、２，４−ジメチルイミダゾール、２−エチル−４−メチルイミダゾール、２−フェニルイミダゾール、２−フェニル−４−メチルイミダゾール、２−ヘプタデシルイミダゾール等のイミダゾール及びその誘導体、等の含窒素複素環式化合物、等がある。
【００３２】
又、ポリアミド樹脂としては、例えば、ナイロン６，６６，６１０，１１，１２，９，１３，Ｑ２ナイロン等、或いはこれらを主成分とするナイロンの共重合体等、或いはＮ−アルキル変性ナイロン、Ｎ−アルコキシルアルキル変性ナイロン等、いずれも好適に用いることができる。更にはポリアミド変性フェノール樹脂等のようにポリアミドにて変性された各種樹脂、或いは、硬化剤としてポリアミド樹脂を用いたエポキシ樹脂、といったように、ポリアミド樹脂分を含有している樹脂であれば、いずれも好適に用いることができる。
【００３３】
又、ウレタン樹脂としてはウレタン結合を含んだ樹脂で有れば、いずれも好適に用いることができる。このウレタン結合はポリイソシアネートとポリオールとの重合付加反応によって得られる。
【００３４】
このポリウレタン樹脂の主原料となるポリイソシアネートとしては、ジフェニレンメタン−４，４′−ジイソシアネート（ＭＤＩ）、イソホロンジイソシアネート（ＩＰＤＩ）、ポリメチレンポリフェニルポリイソシアネート、トリレンジイソシアネート、ヘキサメチレンジイソシアネート、１，５−ナフタリンジイソシアネート、４，４′−ジシクロヘキシルメタンジイソリアネート、カルボジイミド変性ジフェニルメタン−４，４′−ジイソシアネート、トリメチルヘキサメチレンジイソシアネート、オルトトルイジンジイソシアネート、ナフチレンジイソシアネート、キシレンジイソシアネート、パラフェニレンジイソシアネート、リジンジイソシアネートメチルエステル、ジメチルジイソシアネート等が使用可能である。
【００３５】
またポリウレタン樹脂の主原料となるポリオールとしては、ポリエチレンアジペートエステル、ポリブチレンアジペートエステル、ポリジエチレングリコールアジペートエステル、ポリヘキセンアジペートエステル、ポリカプロラクトンエステル等のポリエステルポリオール、ポリテトラメチレングリコール、ポリプロピレングリコール等のポリエーテルポリオール等が使用可能である。
【００３６】
被覆層の結着樹脂材料としては、上記の他に一般に公知の樹脂が使用可能である。例えば、スチレン系樹脂、ビニル系樹脂、ポリエーテルスルホン樹脂、ポリカーボネート樹脂、ポリフェニレンオキサイド樹脂、フッ素樹脂、繊維素系樹脂、アクリル系樹脂、エポキシ樹脂、ポリエステル樹脂、アルキッド樹脂、メラミン樹脂、尿素樹脂、シリコン樹脂、ポリイミド樹脂等の熱可塑性樹脂、または光硬化性樹脂等を使用することができる。なかでもシリコーン樹脂及びフッ素樹脂のような離型性のあるもの、あるいはポリエーテルスルホン、ポリカーボネート、ポリフェニレンオキサイド、ポリエステル、スチレン系樹脂及びアクリル樹脂のような機械的に優れたものがより好ましい。
【００３７】
ただし、本発明の目的を容易に達成するためには、前述のごとく、−ＮＨ_２基、＝ＮＨ基、もしくは−ＮＨ−結合の少なくとも一つの構造を有している、またはそれらの構造を有する群により変性されている結着樹脂を用いることが好ましい。また、上記一般的な結着樹脂と混合して用いることも可能である。
【００３８】
本発明に用いられる現像剤担持体は該被覆層の体積抵抗を調節する為、結着樹脂中に他の導電性微粒子を分散含有させても良い。このような導電性微粒子としては、個数平均粒径が２０μｍ以下が好ましく、１０μｍ以下がより好ましい。樹脂表面に形成される凹凸を避けるためには、１μｍ以下のものを用いる。
【００３９】
本発明で使用される導電性微粒子の構成としては、ファーネスブラック、ランプブラック、サーマルブラック、アセチレンブラック、チャンネルブラック等のカーボンブラック；酸化チタン、酸化スズ、酸化亜鉛、酸化モリブデン、チタン酸カリ、酸化アンチモン及び酸化インジウム等の金属酸化物等；アルミニウム、銅、銀、ニッケル等の金属、グラファイト、金属繊維、炭素繊維等の無機系充填剤等が挙げられる。
【００４０】
上述した被覆層中の導電性微粒子の添加量としては、結着樹脂１００重量部に対して１００重量部以下の範囲が好ましい結果を与える。添加量が１００重量部を越えると被膜強度の低下が起こり易く、また多量の非帯電性粒子の添加は、トナーの帯電性の低下が生じうる。
【００４１】
本発明に用いられる現像剤担持体の樹脂被覆層の構成としては、潤滑性物質を被覆樹脂層中に分散させることで、より本発明の効果が促進されるので好ましい。潤滑性物質としては、例えばグラファイト、二硫化モリブデン、窒化硼素、雲母、フッ化グラファイト、銀−セレン化ニオブ、塩化カルシウム−グラファイト、滑石、ステアリン酸亜鉛等の脂肪酸金属塩等が挙げられ、特にグラファイトが被覆層の導電性を損なわないので好ましく用いられる。これらの潤滑性物質は、個数平均粒径が好ましくは０．２〜２０μｍ程度、より好ましくは０．３〜１５μｍのものを使用するのがよい。
【００４２】
上記潤滑性物質の添加量としては、結着樹脂１００重量部に対して１０〜１２０重量部の範囲で特に好ましい結果を与える。添加量が１２０重量部を越える場合は被膜強度の低下が生じ易く、また非帯電性の添加物を多量に添加することは、トナーの帯電量の低下が発生する。逆に１０重量部未満では現像剤担持体へのトナー付着防止に対する添加効果を得ることができにくい。
【００４３】
次に本発明に用いられる現像剤担持体の構成について説明を加える。現像剤担持体は基体と、それを取り巻いて被覆する樹脂層とからなる。基体としては、円筒状部材、円柱状部材、ベルト状部材等があるが、ドラムに非接触の現像方法においては金属の円筒管が好ましく用いられる。金属円筒管は主としてステンレススチール、アルミニウムおよびその合金等の非磁性のものが好適に用いられる。また、ドラムに直接接触させる現像方法の場合の基体としては、ウレタン、ＥＰＤＭ、シリコン等のゴムやエラストマーを含む層構成を有する円筒部材が好ましく用いられる。
【００４４】
また、現像剤担持体の樹脂被覆層の構成として、前述した添加物質に加えて、粒径が０．３〜３０μｍの球状粒子を被覆樹脂層中に分散させることで、表面粗さを安定化させ、現像剤担持体上のトナーコート量を最適化することが可能である。該球状粒子は、現像剤担持体の被覆層表面に均一な表面粗度を保持させると同時に、被覆層表面が磨耗した場合でも被覆層の表面粗度の変化が少なく、且つトナー汚染やトナー融着を発生しにくくする効果がある。
【００４５】
本発明に使用される球状粒子としては、個数平均径が０．３〜３０μｍ、好ましくは２〜２０μｍである。球状粒子の個数平均粒径が０．３μｍ未満では表面に均一な粗さを付与する効果と帯電性能を高める効果が少なく、現像剤への迅速且つ均一な帯電が不十分となると共に、被覆層の磨耗によるトナーのチャージアップ、トナー汚染及びトナー融着が発生し、ゴーストの悪化、画像濃度低下を生じやすくなるため好ましくない。個数平均粒径が３０μｍを越える場合には、被覆層表面の粗さが大きくなり過ぎ、トナーの帯電が十分に行なわれにくくなってしまうと共に、被覆層の機械的強度が低下してしまうため好ましくない。さらに好ましくは、球状粒子の真密度は、３ｇ／ｃｍ^３以下、好ましくは２．７ｇ／ｃｍ^３以下、より好ましくは０．９〜２．３ｇ／ｃｍ^３であることが良い。即ち、球状粒子の真密度が３ｇ／ｃｍ^３を越える場合には、被覆層中での球状粒子の分散性が不十分となる為、被覆層表面に均一な粗さを付与しにくくなる。また、塗料の保存安定性が良くないため、ここでも均一表面凹凸を有する摩擦帯電付与部材表面が得にくくなる。
【００４６】
球状粒子の真密度が０．９ｇ／ｃｍ^３より小さい場合にも、被覆層中での球状粒子の分散性および保存安定性が不十分となる。
【００４７】
本発明に於いて、導電性球状粒子における球状とは、粒子の長径／短径の比が１．０〜１．５程度の物を意味しており、本発明において好ましくは、長径／短径の比が１．０〜１．２の粒子を使用することが良い。
【００４８】
球状粒子の長径／短径の比が１．５を越える場合には、被覆層表面粗さの不均一化が発生し、トナーの迅速且つ均一な帯電化及び導電性被覆層の強度の点で好ましくない。
【００４９】
本発明に用いられる球状粒子は、公知の球状粒子が使用可能である。例えば、球状の樹脂粒子、球状の金属酸化物粒子、球状の炭素化物粒子などがある。
【００５０】
球状の粒子としては、例えば、懸濁重合、分散重合法等による球状の樹脂粒子などが用いられる。球状の樹脂粒子は、より少ない添加量で好適な表面粗さが得られ、更に均一な表面形状が得られやすい。この様な球状粒子としては、ポリアクリレート、ポリメタクリレート等のアクリル系樹脂粒子、ナイロン等のポリアミド系樹脂粒子、ポリエチレン、ポリプロピレン等のポリオレフィン系樹脂粒子、シリコーン系樹脂粒子、フェノール系樹脂粒子、ポリウレタン系樹脂粒子、スチレン系樹脂粒子、ベンゾグアナミン粒子、等々が挙げられる。粉砕法により得られた樹脂粒子を熱的にあるいは物理的な球形化処理を行ってから用いてもよい。
【００５１】
また、該球状粒子の表面に無機物を付着させる、あるいは固着させて用いてもよい。この様な無機微粉体としては、ＳｉＯ_２，ＳｒＴｉＯ_３，ＣｅＯ_２，ＣｒＯ，Ａｌ_２Ｏ_３，ＺｎＯ，ＭｇＯ，の如き酸化物、Ｓｉ_３Ｎ_４の如き窒化物、ＳｉＣの如き炭化物、ＣａＳＯ_４，ＢａＳＯ_４，ＣａＣＯ_３，の如き硫酸塩、炭酸塩、等々が挙げられる。このような無機微粉末は、カップリング剤により処理して用いても良い。
【００５２】
特に結着樹脂との密着性を向上させる目的、あるいは粒子に疎水性を与える、等々の目的では好ましく用いることが可能である。このようなカップリング剤としては、例えば、シランカップリング剤、チタンカップリング剤、ジルコアルミネートカップリング剤等がある。より具体的には、例えばシランカップリング剤としては、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、トリオルガノシリルメルカプタン、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、ビニルイジメチルアセトキシシラン、ジメチルジエトキシシラン、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及び１分子当たり２から１２個のシロキサン単位を有し末端に位置する単位にそれぞれ１個宛の硅素原子に結合した水素基を含有したジメチルポリシロキサン等が挙げられる。
【００５３】
このように球状樹脂粒子表面に対して無機微粉末で処理することにより、被覆層中への分散性、被覆層表面の均一性、被覆層の耐汚染性、トナーへの帯電付与性、被覆層の耐磨耗性等を向上させることができる。
【００５４】
また、本発明に使用する球状粒子は、導電性であることが好ましい。即ち、球状粒子に導電性を持たせることによって、その導電性のゆえに粒子表面にチャージが蓄積しにくく、トナー付着の軽減やトナーへの帯電付与性を向上させることができるからである。本発明において、球状粒子の導電性としては、体積抵抗値が１０^６Ω・ｃｍ以下、より好ましくは１０^−３〜１０^６Ω・ｃｍの粒子であることが好ましい。
【００５５】
本発明において、球状粒子の体積抵抗が１０^６Ω・ｃｍを超えると、磨耗によって被覆層表面に露出した球状粒子を核としてトナーの汚染や融着を発生しやすくなるとともに、迅速且つ均一な帯電が行われにくくなるため、好ましくない。このような導電性球状粒子を得る方法としては、以下に示す様な方法が好ましいが、必ずしもこれらの方法に限定されるものではない。
【００５６】
本発明に使用される特に好ましい導電性球状粒子を得る方法としては、例えば、樹脂系球状粒子やメソカーボンマイクロビーズを焼成して炭素化及び／又は黒鉛化して得た低密度且つ良導電性の球状炭素粒子を得る方法が挙げられる。そして、樹脂系球状粒子に用いられる樹脂としては、例えば、フェノール樹脂、ナフタレン樹脂、フラン樹脂、キシレン樹脂、ジビニルベンゼン重合体、スチレン−ジビニルベンゼン共重合体、ポリアクリロニトリルが挙げられる。
【００５７】
又、メソカーボンマイクロビーズは、通常、中ピッチを加熱焼成していく過程で生成する球状結晶を多量のタール、中油、キノリンの如き溶剤で洗浄することによって製造することができる。
【００５８】
より好ましい導電性球状粒子を得る方法としては、エノール樹脂、ナフタレン樹脂、フラン樹脂、キシレン樹脂、ジビニルベンゼン重合体、スチレン−ジビニルベンゼン共重合体、ポリアクリロニトリルの如き球状樹脂粒子表面に、メカノケミカル法によってバルクメソフェーズピッチを被覆し、被覆された粒子を酸化性雰囲気化で熱処理した後に不活性雰囲気下又は真空下で焼成して炭素化及び／又は黒鉛化し、導電性球状炭素粒子を得る方法が挙げられる。この方法で得る球状炭素粒子は、黒鉛化すると得られる球状炭素粒子の被覆部の結晶化が進んだものとなるので導電性が向上し、より好ましい。
【００５９】
上記した方法で得られる導電性の球状炭素粒子は、いずれの方法でも、焼成条件を変化させることによって得られる球状炭素粒子の導電性を制御することが可能であり、本発明において好ましく使用される。又、上記の方法で得られる球状炭素粒子は、場合によっては、更に導電性を高めるために導電性球状粒子の真密度が３ｇ／ｃｍ^３を越えない範囲で、導電性の金属及び／または金属酸化物のメッキを施しても良い。
【００６０】
本発明で使用される導電性球状粒子を得る他の方法としては、球状樹脂粒子からなる芯粒子に対して、芯粒子の粒径より小さい粒径の導電性微粒子を適当な配合比で機械的に混合することによって、ファンデルワールスカ及び静電気力の作用により、芯粒子の周囲に均一に導電性微粒子を付着した後、例えば機械的衝撃力を付与することによって生ずる局部的温度上昇により芯粒子表面を軟化させ、芯粒子表面に導電性微粒子を成膜して導電化処理した球状樹脂粒子を得る方法が挙げられる。
【００６１】
本発明に使用される導電性球状粒子を得る更に他の方法としては、球状樹脂粒子中に導電性微粒子を均一に分散させることにより、導電性微粒子が分散された導電性球状粒子を得る方法が挙げられる。球状樹脂粒子中に導電性微粒子を均一に分散させる方法としては、例えば、結着樹脂と導電性微粒子とを混練して導電性微粒子を分散させた後、冷却固化し、所定の粒径に粉砕し、機械的処理及び熱的処理により球形化して導電性球状粒子を得る方法；又は、重合性単量体中に重合開始剤、導電性微粒子及びその他の添加剤を加え、分散機によって均一に分散せしめた単量体組成物を、分散安定剤を含有する水相中に攪拌機等によって所定の粒子径になるように懸濁させて重合を行ない、導電性微粒子が分散された球状粒子を得る方法；が挙げられる。
【００６２】
本発明の樹脂被覆層を形成する方法については、特に限定されない、例えば、現像剤担持体の基材に、本発明の組成物を含有する塗布液をディッピング法、スプレー法、はけ塗り法などの方法で乾燥させれば、本発明の現像剤担持体が得られる。
【００６３】
次に本発明において、静電潜像から可視画像を得るために用いられる現像剤（トナー）について説明する。
【００６４】
本発明におけるトナーの円相当径及び粒度分布は、東亜医用電子（株）製フロー式粒子像分析装置ＦＰＩＡ−１０００を用いて測定した値を用いた。この装置において、円相当径は次のように測定される。
【００６５】
測定法としては、フィルターを通すなどして微細なゴミを取り除いた水（１０^−３ｃｍ^３の粒子数が２０個以下）約５０ｍｌ中に分散剤として界面活性剤（好ましくはアルキルベンゼンするフォン酸塩）を数滴加え、更に測定試料を２〜２０ｍｇ程度加えて超音波分散器で約１〜３分間分散処理を行い、測定試料の粒子濃度を４０００〜８０００個／１０^−３ｃｍ^３に調整した試料液を、フローセル中に薄い層にして流し、その流動する粒子の投影写真を撮影して、粒子一個一個について投影面積を測定し、それと同じ面積を有する真円の直径を円相当径として算出し、さらに円相当径の粒度分布を求め、粒径０．６μｍ以上１．０μｍ以下の粒子の個数基準％と個数平均粒径を算出した。
【００６６】
従来、１．０μｍ以下の粒径を測定可能な装置はいくつか存在したが、１．０μｍ以下の領域はノイズが大きく影響し、データの再現性に問題があった。この装置は１．０μｍ以下の領域でも再現性が良く、また実際に粒子画像としての情報が同時に得られるため、粒子の確認もできるという点で優れている。
【００６７】
本発明におけるトナー粒子は円相当径による粒度分布において、０．６μｍ以上１．０μｍ以下の占める割合が個数基準で５．０％未満であり、個数平均粒径が４〜１０μｍである場合に、問題を解決できる。
【００６８】
トナー粒子の円相当径による粒度分布において、０．６μｍ以上１．０μｍ以下の占める割合が個数基準で５．０％以上である場合、トナー粒子１個における外添剤量が少なくなり、転写前のトナーの帯電量を十分に高めることができずネガスリーブゴーストが悪化する。また、個数平均粒径が４μｍ未満の場合、クリーニング不良が発生し、個数平均粒径が１０μｍを越える場合は、トナーが感光体に付着するいわゆるフィルミングが発生してしまう。
【００６９】
トナー粒子の３μｍ以上の粒子において、円形度ａ＝０．９０以上の粒子を個数基準で９０％未満の場合、トナーの感光体に対する付着力が増し、転写性が悪化する。また、円形度０．９８以上の粒子が３０％以上ある場合には、クリーニング不良が発生する。
【００７０】
本発明における円形度とは、粒子の形状を定量的に表現する簡便な方法として用いたものであり、例えば東亜医用電子製フロー式粒子像分析装置ＦＰＩＡ−１０００を用いて、下記式より得られた値を円形度と定義する。本発明におけるトナー粒子の円形度分布は、下記粒子像分析装置を用いて、前記した円相当径の測定と同様の方法で、下記式により算出した。
ａ＝Ｌ０／Ｌ
Ｌ０；粒子像と同じ投影面積を持つ円の周囲長
Ｌ ；粒子像の周囲長
【００７１】
本発明に使用されるトナーの結着樹脂の種類としては、例えば、ポリエチレン、ポリ−ｐ−クロルスチレン、ポリビニルトルエン等のスチレン及びその置換体の単重合体、スチレン−ｐ−クロルスチレン共重合体、スチレン−ビニルトルエン共重合体、スチレン−ビニルナフタリン共重合体、スチレン−アクリル酸エステル共重合体、スチレン−メタクリル酸エステル共重合体、スチレン−α−クロルメタクリル酸メチル共重合体、スチレン−アクリロニトリル共重合体、スチレン−ビニルメチルエーテル共重合体、スチレン−ビニルエチルエーテル共重合体、スチレン−ビニルメチルケトン共重合体、スチレン−ブタジエン共重合体、スチレン−イソプレン共重合体、スチレン−アクリロニトリル−インデン共重合体等のスチレン系共重合体；ポリ塩化ビニル、フェノール樹脂、天然変性フェノール樹脂、天然樹脂変性マレイン酸樹脂、アクリル樹脂、メタクリル樹脂、ポリ酢酸ビニール、シリコーン樹脂、ポリエステル樹脂、ポリウレタン、ポリアミド樹脂、フラン樹脂、エポキシ樹脂、キシレン樹脂、ポリビニルブチラール、テルペン樹脂、クマロンインデン樹脂、石油系樹脂などが使用できる。また、架橋されたスチレン系樹脂も好ましい結着樹脂である。
【００７２】
スチレン系共重合体のスチレンモノマーに対するコモノマーとしては、例えば、アクリル酸、アクリル酸メチル、アクリル酸エチル、アクリル酸ブチル、アクリル酸ドデシル、アクリル酸オクチル、アクリル酸−２−エチルヘキシル、アクリル酸フェニル、メタクリル酸、メタクリル酸メチル、メタクリル酸エチル、メタクリル酸ブチル、メタクリル酸オクチル、アクリロニトリル、メタクリロニトリル、アクリルアミド等のような二重結合を有するモノカルボン酸もしくはその置換体；例えば、マレイン酸、マレイン酸ブチル、マレイン酸メチル、マレイン酸ジメチル、等のような二重結合を有するジカルボン酸、及びその置換体；例えば、塩化ビニル、酢酸ビニル、安息香酸ビニル等のようなビニルエステル類、例えば、エチレン、プロピレン、ブチレン等のようなエチレン系オレフィン類；例えばビニルメチルケトン、ビニルヘキシルケトン等のようなビニルケトン類；例えば、ビニルメチルエーテル、ビニルエチルエーテル、ビニルイソブチルエーテル等のようなビニルエーテル類；等のビニル単量体が単独もしくは組み合わせて用いられる。ここで架橋剤としては、主として２個以上の重合可能な二重結合を有する化合物が用いられ、例えば、ジビニルベンゼン、ジビニルナフタレン等のような芳香族ジビニル化合物；例えばエチレングリコールジアクリレート、エチレングリコールジメタクリレート、１．３−ブタンジオールジメタクリレート等のような二重結合を２個有するカルボン酸エステル；ジビニルアニリン、ジビニルエーテル、ジビニルスルフィド、ジビニルスルホン等のジビニル化合物；及び３個以上のビニル基を有する化合物；が単独もしくは混合物として使用できる。
【００７３】
又、トナー中には着色剤として顔料を含有することができる。例えば、カーボンブラック、ニグロシン染料、ランプ黒、スーダンブラックＳＭ、ファースト・イエローＧ、ベンジジン・イエロー、ピグメント・イエロー、インドファースト・オレンジ、イルガジン・レッド、パラニトロアニリン・レッド、トルイジン・レッド、カーミンＦＢ、パーマネント・ボルドーＦＲＲ、ピグメント・オレンジＲ、リソール・レッド２Ｇ、レーキ・レッドＣ、ローダミンＦＢ、ローダミンＢレーキ、メチル・バイオレッドＢレーキ、フタロシアニン・ブルー、ピグメント・ブルー、ブリリアント・グリーンＢ、フタロシアニングリーン、オイルイエローＧＧ、ザボン・ファーストイエローＣＧＧ、カヤセットＹ９６３、カヤセットＹＧ、ザボン・ファーストオレンジＲＲ、オイル・スカーレット、オラゾール・ブラウンＢ、ザボン・ファーストスカーレットＣＧ、オイルピンクＯＰ等が適用できる。
【００７４】
トナーを磁性トナーとして用いる場合には、トナーの中に磁性粉を含有せしめるが、このような磁性粉としては、磁場の中におかれて磁化される物質が用いられる。
【００７５】
磁性体としては、鉄、コバルト、ニッケル、銅、マグネシウム、マンガン、アルミニウム、硅素などの元素を含む金属酸化物などがある。中でも四三酸化鉄、γ−酸化鉄など、酸化鉄を主成分とするものが好ましい。また、トナー帯電性コントロールの観点から硅素元素またはアルミニウム元素など、他の金属元素を含有していてもよい。これら磁性粒子は、窒素吸着法によるＢＥＴ比表面積が好ましく２〜３ｍ^２／ｇ、特に３〜２８ｍ^２／ｇ、更にモース硬度が５〜７の磁性粉が好ましい。
【００７６】
磁性体の形状としては、８面体、６面体、球状、針状、鱗片状などがあるが、８面体、６面体、球体、不定形型の異方性の少ないものが画像濃度を高める上で好ましい。磁性体の平均粒径としては０．０５〜１．０μｍが好ましく、さらに好ましくは０．１〜０．６μｍ、さらには０．１〜０．４μｍが好ましい。
【００７７】
磁性体量は結着樹脂１００質量部に対し３０〜２００質量部、好ましくは４０〜２００質量部、更には５０〜１５０質量部が好ましい。３０質量部未満ではトナー搬送に磁気力を用いる現像器においては、搬送性が不十分で現像剤担持体上の現像剤層にむらが生じ画像むらとなる傾向であり、さらに現像剤トリボの上昇に起因する画像濃度の低下が生じやすい傾向であった。一方、２００質量部を越えると定着性に問題が生ずる傾向であった。
【００７８】
本発明において、上記トナーを非磁性トナーとして用いる場合は、キャリアと混合して二成分系現像剤として用いることも、或いは、キャリアと混合せずに非磁性一成分現像剤として用いることが可能である。
【００７９】
また、本発明のトナーに用いられる無機微粉末の外添剤としては、帯電安定性、現像性、流動性、保存性向上のため、シリカ、アルミナ、チタニアなどの無機微粉体、あるいはその複酸化物の中から選ばれることが好ましい。さらにはシリカであることがより好ましい。例えば、かかるシリカは硅素ハロゲン化合物やアルコキシドの蒸気相酸化により生成されたいわゆる乾式法、またはヒュームドシリカと称される乾式シリカ及びアルコキシド、水ガラス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Ｎａ_２Ｏ，ＳＯ_３ ^２−等の製造残滓の少ない乾式シリカの方が好ましい。また、乾式シリカにおいては、製造工程において例えば、塩化アルミニウム、塩化チタン等他の金属ハロゲン化合物を硅素ハロゲン化合物と共に用いることによって、シリカと他の金属酸化物の複合微粉体を得ることも可能であり、それらも包含する。
【００８０】
本発明に用いられる無機微粉体はＢＥＴ法で測定した窒素吸着による比表面積が３０ｍ^２／ｇ以上、特に５０〜４００ｍ^２／ｇの範囲のものが良好な結果を与え、トナー１００質量部に対してシリカ微粉末０．１〜８質量部、好ましくは０．５〜５質量部、さらに好ましくは１．０を越えて３．０質量部まで使用するのが特に良い。
【００８１】
また、本発明に用いられる無機微粉末は、必要に応じ疎水化、帯電性制御などの目的でシリコーンワニス、シリオーンオイル、各種変性シリコーンオイル、シランカップリング剤、官能基を有するシランカップリング剤、その他有機硅素化合物、有機チタン化合物などの処理剤で、あるいは、種々の処理剤で併用して処理されていることも可能であり、好ましい。
【００８２】
比表面積は、ＢＥＴ法に従って、比表面積測定装置オートソーブ１（湯浅アイオニクス社製）を用いて試料表面に窒素ガスを吸着させ、ＢＥＴ多点法を用いて比表面積を算出した。
【００８３】
安定したトナーの保存性を維持するためには、無機微粉体は少なくともシリコーンオイルで処理されることが好ましい。
【００８４】
本発明中のトナーには、必要に応じてシリカ微粉体以外の外部添加剤を添加してもよい。
【００８５】
例えば帯電補助剤、導電性付与剤、流動性付与剤、ケーキング防止剤、熱ロール定着時の離型剤、滑剤、研磨剤等の働きをする樹脂微粒子である。
【００８６】
樹脂微粒子としては、その平均粒径が０．０５〜２．０μｍのものが好ましく、その樹脂を構成する重合性単量体としては、スチレン・ｏ−メチルスチレン・ｍ−メチルスチレン・ｐ−メチルスチレン・ｐ−メトキシスチレン・ｐ−エチルスチレン等のスチレン系単量体、アクリル酸・メタクリル酸等のメタクリル酸類、アクリル酸メチル・アクリル酸エチル・アクリル酸ｎ−ブチル・アクリル酸イソブチル・アクリル酸ｎ−プロピル・アクリル酸ｎ−オクチル・アクリル酸ドデシル・アクリル酸２−エチルヘキシル・アクリル酸ステアリル・アクリル酸２−クロルエチル・アクリル酸フェニル等のアクリル酸エステル類、メタクリル酸メチル・メタクリル酸エチル・メタクリル酸ｎ−プロピル・メタクリル酸ｎ−ブチル・メタクリル酸イソブチル・メタクリル酸ｎ−オクチル・メタクリル酸ドデシル・メタクリル酸２−エチルヘキシル・メタクリル酸ステアリル・メタクリル酸フェニル・メタクリル酸ジメチルアミノエチル・メタクリル酸ジエチルアミノエチル等のメタクリル酸エステル類その他のアクリロニトリル・メタクリロニトリル・アクリルアミド等の単量体・ベンゾグアナミンホルムアルデヒド樹脂・メラミン系樹脂が挙げられるが、特にメラミン系樹脂を用いるのが迅速且つ均一な帯電をより向上させるため好ましい。重合方法としては、懸濁重合、乳化重合、ソープフリー重合等、が使用可能であるが、より好ましくは、ソープフリー重合によって得られる粒子が良い。
【００８７】
本発明において、必要であればトナー粒子中にワックスを内添しても構わない。用いられるワックスとしては、ポリプロピレン、ポリエチレン、マイクロクリスタリンワックス、カルナバワックス、サゾールワックス、パラフィンワックス、高級アルコール系ワックス、エステルワックスなど及びこれらの酸化物やグラフト変化物などが挙げられる。
【００８８】
これらの低分子量ワックスは、トナー製造時に予め結着樹脂中に添加、混合しても良い。添加量としては、結着樹脂１００質量部に対し約１〜２０質量部が好ましい。
【００８９】
また、本発明のトナーには、必要に応じて荷電制御剤をトナー粒子に配合（内添）して用いることもできる。荷電制御剤によって、現像システムに応じた最適の荷電量コントロールが可能になり、特に本発明では粒度分布と荷電量とのバランスを更に安定したものとする事が可能である。トナーを負荷電性に制御するものとして下記物質がある。
【００９０】
例えば有機金属錯体、キレート化合物が有効であり、モノアゾ金属錯体、アセチルアセトン金属錯体、芳香族ハイドロキシカルボン酸、芳香剤ダイカルボン酸系の金属錯体がある。他には、芳香族ハイドロキシカルボン酸、芳香族モノ及びポリカルボン酸及びその金属塩、無水物、エステル類、ビスフェノール等のフェノール誘導体類等がある。
【００９１】
上述した荷電制御剤は微粒子状として用いることが好ましく、この場合、これらの荷電制御剤の個数平均粒径は４μｍ以下さらには３μｍ以下が特に好ましい。これらの荷電制御剤をトナーに内添する場合には、結着樹脂１００質量部に対して０．１〜２０質量部、特に０．２〜１０質量部使用することが好ましい。
【００９２】
上述したような材料からなるトナーを作成するには、従来公知の方法が用いられる。例えば、一般的に行われている、結着樹脂、着色剤としての顔料、染料、又は磁性体、必要に応じて添加されるワックス、金属塩乃至は金属錯体、荷電制御剤その他の添加剤等からなるトナー形成材料を、ヘンシェルミキサー、ボールミル等の混合器により充分混合してから、加熱ロール、ニーダー、エクストルーダーの如き熱混練機を用いて溶融混練して、樹脂類をお互いに相溶せしめた中に着色剤、金属化合物等を分散または溶解せしめ、冷却固化後、粉砕して、必要に応じて分級及び表面処理を行ってトナー粒子を得、更に、無機微粉体等を添加混合して製造する方法が好ましく用いられる。
【００９３】
先に述べたように、本発明においては、円相当径による粒度分布において、０．６０μｍ以上１．００μｍ未満の占める割合が個数基準で５．０％未満に調整されたトナー、より好ましくは、トナー粒子の円相当径１．０μｍ未満の粒子が除去された状態に調整されたトナーを使用するが、円相当径１．０μｍ未満のトナー粒子の除去を行う場合に、下記に説明する機械的衝撃力を加える処理によって行うことが好ましい。即ち、ホソカワミクロン社製のメカノフージョンシステムや奈良機械製作所製のハイブリダイゼーションシステム等の装置のように、高速回転する羽根によりトナーをケーシングの内側に遠心力により押しつけて、圧縮力、摩擦力等の力によりトナーに機械的衝撃力を加える方法が挙げられる。具体的に、本発明で使用する円相当径による粒度分布において、０．６０μｍ以上１．００μｍ未満の占める割合が個数基準で５．０％未満に調整されたトナーを得るためには、トナーを微粉砕しながら円形度分布と粒度分布を整える方法、あるいはそれに加えて、機械的衝撃力による表面処理を行うなどが好ましい。
【００９４】
機械的衝撃力を加える工程は、通常トナーの微粉砕行程の後に行われるのがトナー粒子の円形度分布や粒度分布を均一に調整するには分級工程によりある程度の分級をした後に処理した方がより有効である。
【００９５】
衝撃式表面処理装置では図１及び図２に示すように、駆動手段によって回転軸１６１を駆動し、表面処理すべき物質の性質により粒子が解砕しない程度の周速で回転盤１６２を回転させ、該回転盤の回転に伴って発生した急激な気流により、衝撃室１６８に開口する循環路１６３を巡って回転盤１６２の中心部に戻る循環流れを起こす。
【００９６】
次に、一定量の被処理粉体を原料ホッパー１６４から衝撃室１６８に投入し、投入された該被処理粉体は高速回転する回転盤１６２によって瞬間的な打撃を受け、さらに周辺の衝突リング５８に突入して衝撃作用を受けた後、該循環流れにより循環路１６３を介して再び衝撃室１６８へ戻り、再度打撃作用を受け表面処理が行われる。ブレード１５５の周速は６０ｍ／秒から１５０ｍ／秒の範囲になるように回転盤を回転させる。
【００９７】
分級及び表面処理の順序はどちらが先でも良い。分級行程においては生産効率上、多分割分級機を用いることが好ましい。
【００９８】
次に、上記したような本発明の現像装置及び画像形成装置について説明する。
【００９９】
図３は本発明の一実施形態の現像装置の模式図を示す。
【０１００】
図３において、公知のプロセスにより形成された静電潜像を保持する静電潜像保持体潜像保持体、例えば、電子写真感光ドラム１は、矢印Ａ方向に回転される。現像剤担持体としての現像現像スリーブ８は、現像剤容器としてのホッパー３によって供給された磁性トナーを有する一成分系現像剤４を担持して、矢印Ａ方向に回転することによって、現像スリーブ８と感光ドラム１とが対向している現像領域Ｄに現像剤４を搬送する。図３に示すように、現像スリーブ８内には、現像剤４を現像スリーブ８上に磁気的に吸引且つ保持する為に、磁石が内接されているマグネットローラー５が配置されている。
【０１０１】
本発明の現像装置で用いられる現像スリーブ８は、基体としての金属円筒管６上に被覆された導電性被覆層７を有する。ホッパー３中には、現像剤４を攪拌するための攪拌翼１０が設けられている。現像スリーブ８とマゲネットローラー５とは非接触状態にある。
【０１０２】
現像剤４は、磁性トナー相互間及び現像スリーブ８上の導電性被覆層７との摩擦により、感光ドラム１上の静電潜像を現像することが可能な摩擦帯電電荷を得る。図３の例では、現像領域Ｄに搬送される現像剤４の層厚を規制するために、現像剤層厚規制部材としての強磁性金属製の磁性規制ブレード２が、現像スリーブ８の表面から約５０〜５００μｍのギャップ幅を持って現像スリーブ８に臨む様に、ホッパー３から垂下されている、マグネットローラー５の磁極Ｎ１からの磁力線が磁性規制ブレード２に集中することにより、現像スリーブ８上に現像剤４の薄層が形成される。本発明においては、この磁性規制ブレードにかえて非磁性ブレードを使用することもできる。
【０１０３】
この様にして、現像スリーブ８上に形成される現像剤４の薄層の厚みは、現像領域Ｄにおける現像スリーブ８と感光ドラム１との間の最小間隔よりも更に薄いものであることが好ましい。
【０１０４】
本発明の現像剤担持体は、以上の様な現像剤の薄層により静電潜像を現像する方式の現像装置、即ち、非接触型現像装置に組み込むのが特に有効であるが、現像領域Ｄにおいて、現像剤層の厚みが現像スリーブ８と感光ドラム１との間の最小間隙以上の厚みである現像装置、即ち接触型現像装置にも本発明の現像剤担持体を適用することができる。
【０１０５】
説明の煩雑を避けるため、以下の説明では、上記したような非接触型現像装置を例に採って行う。
【０１０６】
上記現像スリーブ８に担持された磁性トナーを有する一成分系現像剤４を飛翔させる為、上記現像スリーブ８にはバイアス手段としての現像バイアス電源９により現像バイアス電圧が印加される。この現像バイアス電圧として直流電圧を使用するときに、静電潜像の画像部（現像剤４が付着して可視化される領域）の電位と背景部の電位との間の値の電圧を現像スリーブ８に印加するのが好ましい。
【０１０７】
現像された画像の濃度を高め、或は階調性を向上するためには、現像スリーブ８に交番バイアス電圧を印加し、現像領域Ｄに向きが交互に反転する振動電界を形成してもよい。この場合には、上記した現像画像部の電位と背景部の電位の中間の値を有する直流電圧成分を重畳した交番バイアス電圧を現像スリーブ８に印加するのが好ましい。
【０１０８】
高電位部と低電位部を有する静電潜像の高電位部にトナーを付着させて可視化する、所謂、正規現像の場合には、静電潜像の極性と逆極性に帯電するトナーを使用する。
【０１０９】
高電位部と低電位部を有する静電潜像の低電位部にトナーを付着させて可視化する、所謂、反転現像の場合には、静電潜像の極性と同極性に帯電するトナーを使用する。
【０１１０】
高電位、低電位というのは、絶対値による表現である。これらいずれの場合にも、現像剤４は少なくとも現像スリーブ８との摩擦により帯電する。
【０１１１】
図３はあくまでも本発明の現像装置を模式的に例示したものであり、現像剤容器（ホッパー３）の形状、攪拌翼１０の有無、磁極の配置に様々な形態があることは言うまでもない。勿論、これらの装置では、トナーとキャリアを含む二成分系現像剤を用いる現像に使用することもできる。
【０１１２】
図４を参照しながら、図３で例示した本発明の現像剤担持体を有する現像装置を使用した画像形成装置の一例について説明する。
【０１１３】
先ず、一次帯電手段としての接触（ローラー）帯電手段２９により静電潜像担持体としての感光ドラム１の表面を負極性に帯電し、レーザー光の露光２５によるイメージスキャニングによりデジタル潜像が感光ドラム１上に形成される。次に、現像剤層厚規制部材としての規制ブレード１１を有し、現像剤担持体としての現像スリーブ８が具備されている現像装置によって、上記のデジタル潜像が、現像容器としてのホッパー３内の磁性トナーを有する負帯電性一成分系現像剤４によって反転現像される。図４に示す様に、現像領域Ｄにおいて感光ドラム１の導電性基体は接地されており、現像スリーブ８にはバイアス印加手段９により交互バイアス、パルスバイアス及び／又は直流バイアスが印加されている。次に、被記録材Ｐが搬送されて転写部に来ると、転写手段としての接触（ローラー）転写手段２３により被記録材Ｐの背面（感光ドラム側と反対面）から電圧印加手段２４で帯電されることにより、感光ドラム１の表面上に形成されている現像画像が接触転写手段２３で被記録材Ｐ上へ転写される。次に、感光ドラム１から分離された被記録材Ｐは、定着手段としての加熱加圧ローラー定着器２７に搬送され、該定着器２７によって被記録材Ｐ上の現像画像の定着処理がなされる。
【０１１４】
転写工程後の感光ドラム１に残留する一成分系現像剤４は、クリーニングブレード２８ａを有するクリーニング手段２８で除去される。残留する一成分系現像剤４が少ない場合には、クリーニング工程を省くことも可能である。クリーニング後の感光ドラム１は、必要によりイレース露光２６により除電され、再度、一次帯電手段としての接触（ローラー）帯電手段２９による帯電工程から始まる上記工程が繰り返される。
【０１１５】
上記の一連の工程において、感光ドラム（即ち、静電潜像担持体）１は感光層及び導電性基体を有するものであり、矢印方向に動く。現像スリーブ８は、現像領域Ｄにおいて感光ドラム１の表面と同方向に進む様に回転する。ホッパー３内の一成分系現像剤４は、現像スリーブ８上に担持され、且つ現像スリーブ８の表面との摩擦及び／又トナー同士の摩擦によって、例えば、マイナスのトリボ電荷が与えられる。更に、規制ブレード１１により、現像剤層の厚さを薄く（３０μｍ〜３００μｍ）且つ均一に規制して、現像領域Ｄにおける感光ドラム１と現像スリーブ８との間隙よりも薄い現像剤層を形成させる。現像スリーブ８の回転速度を調整することによって、現像スリーブ８の表面速度が感光ドラム１の表面の速度と実質的に等速、もしくはそれに近い速度となる様にする。現像領域Ｄにおいて、現像スリーブ８に現像バイアス電圧として、交流バイアス又はパルスバイアスをバイアス印加手段９により印加してもよい。この交流バイアスはｆが２００〜４，０００Ｈｚ、Ｖｐｐが５００〜３，０００Ｖであればよい。
【０１１６】
現像領域Ｄにおける現像剤の移転に際し、感光ドラム１の表面の静電気力、及び交流バイアス又はパルスバイアスの如き現像バイアス電圧の作用によって、現像剤は静電潜像側に移転する。
【０１１７】
一次帯電手段としては、以上の如く接触帯電手段として帯電ローラー２９を用いて説明したが、帯電ブレード、帯電ブラシの如き接触帯電手段でもよく、更に非接触のコロナ帯電手段でもよい。しかしながら、帯電によるオゾンの発生が少ない点で接触帯電手段の方が好ましい。
【０１１８】
転写手段としては、以上の如く転写ローラー２３の如き接触転写手段を用いて説明したが、非接触のコロナ転写手段でもよい。しかしながら、こちらも転写によるオゾンの発生が少ない点で接触転写手段の方が好ましい。
【０１１９】
【発明の実施の形態】
以下に、実施例及び比較例を挙げて本発明をより具体的に説明するが、本発明はこれら実施例に限定されるものではない。
【０１２０】

【０１２１】
上記材料をブレンダーにて混合し、１３０℃に加熱した二軸エクストルーダーで溶融混練し、冷却した混練物をハンマーミルで粗粉砕し、粗粉砕を気流分級機と衝突式気流粉砕機を有する粉砕手段で微粉砕した。得られた微粉砕物を粉体供給部に圧縮エアを用いた強制粉体分散装置を内蔵しているコアンダ効果を用いた多分割分級機にて、１．９６×１０^−１ＭＰａの圧縮エアで強制的に分散させながら供給し、厳密に分級して、個数平均円相当径６．３μｍ、円相当径０．６μｍ以上１．０μｍ以下の粒子の占める割合が個数基準で全体の３．９％の磁性トナーを得た。
【０１２２】
さらに、該磁性トナー粒子を、ローターを回転して機械的衝撃力を与える方式の表面改質装置を用いて表面処理した。得られたトナー粒子１の個数平均円相当径は６．７μｍ、円相当径０．６μｍ以上１．０μｍ以下の粒子の占める割合が個数基準で全体の０．６％、粒径３．０μｍ以上のトナーにおいて、円形度ａ＝０．９０以上の粒子は個数基準で９５．４％、円形度ａ＝０．９８以上の粒子は個数基準で２３．５％であった。
【０１２３】
得られたトナー粒子１に、シリコーンオイルとヘキサメチルジシラザン処理乾式シリカを１．５％添加し、混合機にて混合してトナー（１）を得た。
【０１２４】
（トナー製造例２〜４）
製造例１での機械的衝撃力による表面処理の条件を変えて表面処理を行った。得られたトナー粒子に、トナー製造例１と同様にシリコーンオイルとヘキサメチルジシラザン処理乾式シリカを１．５％添加し、混合機にて混合してトナー（２）〜（４）を得た。得られたトナー粒子の物性を表１に示す。
【０１２５】
（トナー製造例５）
機械的衝撃力による表面処理を行わない以外はトナー製造例１と同様にして、トナー（５）を得た。得られたトナー粒子の物性を表１に示す。
【０１２６】
次に現像スリーブの製造について述べる。
【０１２７】
まず４級アンモニウム塩化合物（１）の鉄粉との摩擦帯電量は、市販の摩擦帯電量測定器（東芝ケミカル製ＴＢ−２００型）を用いてブローオフ法により求めたところ、正極性であった。
【０１２８】
また導電性球状粒子として、個数平均粒径５．５μｍの球状フェノール樹脂１００質量部に、ライカイ機（自動乳鉢、石川工場製）を用いて、個数平均粒径１．５μｍ以下の石炭系バルクメソフェーズピッチ粉末１４重量部を均一に被覆し、酸化性雰囲気下で熱安定化処理した後に２，２００℃で焼成することにより黒鉛化して得られた導電性の球状炭素粒子を用いた。この球状炭素粒子は、個数平均粒径５．０μｍ、真密度１．５０ｇ／ｃｍ^３、体積抵抗７．５×１０^−２Ω・ｃｍ、長径／短径比が１．１５であった。
【０１２９】
粒子の物性を表２に示す。
【０１３０】

【０１３１】
上記材料をφ２ｍｍのジルコニア粒子にて３時間サンドミルを用いて分散を行い、その後ジルコニア粒子を篩いで分離し、メタノールで固形分を３０％に調整し塗料１を得た。この塗料をスプレー法にてφ２４．５ｍｍのＡｌ円筒体に１０μｍの被膜を形成させ、次いで熱風乾燥器により１５０℃／３０分間加熱・硬化させ現像剤担持体（１）を作製した。表３に塗料処方及び現像剤担持体物性を示す。
【０１３２】
この現像剤担持体をＮＰ６３５０（キヤノン製複写機）に組み込み、上記現像剤を用いて、画出しを行った。結果を表４，５に示す。良好な結果であった。
【０１３３】
（実施例２）
４級アンモニウム塩化合物（２）を実施例１と同様に鉄粉を用いたブローオフにより帯電量を測定したところ、正極性であった。実施例１において４級アンモニウム塩化合物（２）とした以外は実施例１と同様にして塗料２を作製し、現像剤担持体（２）を得た。これを実施例１と同様に画出し評価した。良好な結果であった。
【０１３４】
（実施例３）
４級アンモニウム塩化合物（３）を実施例１と同様に鉄粉を用いたブローオフにより帯電量を測定したところ、正極性であった。実施例１において４級アンモニウム塩化合物（３）とした以外は実施例１と同様にして塗料３を得、現像剤担持体（３）を作製した。これを実施例１と同様に画出し評価した。良好な結果であった。
【０１３５】
（実施例４〜６）
実施例１〜３で作成した現像剤担持体（１）〜（３）をトナー製造例２で作成したトナー（２）を用いて実施例１と同様に画出し評価を行った。良好な結果であった。
【０１３６】
（実施例７）
実施例１において、４級アンモニウム塩化合物（１）の添加量を５０質量部から５質量部に変えて塗料４を作製した以外は同様にして現像剤担持体（４）を得た。実施例１と同様の評価をおこなった。
【０１３７】
（実施例８）
実施例１において、４級アンモニウム塩化合物（１）の添加量を５０質量部から８０質量部に変えて塗料５を作製した以外は同様にして現像剤担持体（５）を得た。実施例１と同様の評価をおこなった。
【０１３８】
（実施例９）
実施例１において、個数平均粒径５μｍの粒状炭素粒子（Ａ）の添加量を２０質量部から５０質量部に変えて塗料６を作製した以外は同様にして現像剤担持体（６）を得た。実施例１と同様の評価をおこなった。
【０１３９】
（実施例１０）
実施例１と同様にして作成した個数平均径２．１μｍの球状炭素粒子を用い、その他は同様にして現像剤担持体（７）を得た。実施例１と同様の評価をおこなった。
【０１４０】
（実施例１１）
実施例１と同様にして作成した個数平均径２０．３μｍの球状炭素粒子を用い、その他は同様にして現像剤担持体（８）を得た。実施例１と同様の評価をおこなった。
【０１４１】
（実施例１２）
実施例１において用いた、個数平均粒径５μｍの球状炭素粒子の代わりに、個数平均粒径５．１μｍのＰＭＭＡ粒子を用いた以外は、実施例１と同様にして現像剤担持体（９）を作製し、実施例１と同様の評価を行った。このＰＭＭＡ粒子は、真密度１．１９ｇ／ｃｍ^３、体積抵抗１０^１５以上Ω・ｃｍ、長径／短径比が１．１２であった。
【０１４２】
（実施例１３〜１５）
実施例１で作成した現像剤担持体（１）とトナー（３）〜（５）を用いて同様の画出し評価を行った。
【０１４３】

【０１４４】
上記材料を実施例１と同様に分散し、ＩＰＡで固形分を３０％に調整し比較塗料１を得た。この塗料を実施例１と同様の操作で比較用現像剤担持体１を作製し、実施例１と同様にして評価された。
【０１４５】
（比較例２）
実施例１で用いた４級アンモニウム塩化合物（１）の代わりに下記式の４級アンモニウム塩化合物（４）を用いた以外は実施例１と同様にして塗料を作製し、比較用現像剤担持体２を得た。これを実施例１と同様に画出し評価した。４級アンモニウム塩化合物（４）について、同様に鉄粉を用いたブローオフにより帯電量を測定したところ、負極性を示した。
【外５】

【０１４６】
（比較例３）
クロルフェノールを含むアゾナフトールのクロム錯体の鉄粉との摩擦帯電量を実施例１と同様にブローオフ法により求めたところ、負極性であった。実施例１において、４級アンモニウム塩化合物（１）の代わりに、クロルフェノールを含むアゾナフトールのクロム錯体とした以外は実施例１と同様にして、比較用現像剤担持体３を作成し、実施例１と同様に画出し評価した。
【０１４７】

上記材料を実施例１と同様に分散し、メタノールで固形分を３５％に調整し現像剤担持体（１０）を得た。
【０１４８】

上記材料を用いてトナー製造例１と同様にしてトナーを製造した。個数平均円相当径６．９μｍ、円相当径０．６μｍ以上１．０μｍ以下の粒子の占める割合が個数基準で全体の３．３％の磁性トナーを得た。
【０１４９】
さらに、該磁性トナー粒子を、表面改質装置を用いて表面処理した。得られたトナー粒子の個数平均円相当径は７．２μｍ、円相当径０．６μｍ以上１．０μｍ以下の粒子の占める割合が個数基準で全体の０．９％、粒径３．０μｍ以上のトナーにおいて、円形度ａ＝０．９０以上の粒子は個数基準で９５．７％、円形度ａ＝０．９８以上の粒子は個数基準で２４．６％であった。
【０１５０】
得られたトナー粒子に、シリコーンオイルとヘキサメチルジシラザン処理乾式シリカを１．３％を添加し、混合機にて混合してトナー（６）を得た。
【０１５１】
（トナー製造例７）
製造例６での機械的衝撃力による表面処理の条件を変えて表面処理を行った。得られたトナー粒子に、トナー製造例６と同様にシリコーンオイルとヘキサメチルジシラザン処理乾式シリカの添加量を１．３％に添加しトナー（７）を得た。トナー（６）及びトナー（７）を用いて、実施例１と同様の評価をおこなった。
【０１５２】
（実施例１８，１９）
実施例１６において、４級アンモニウム塩化合物（１）の添加量を９０質量部から５０質量部に変えて塗料１１を作製した以外は同様にして現像剤担持体（１１）を得た。トナー（６）及びトナー（７）を用いて、実施例１と同様の評価をおこなった。
【０１５３】
（実施例２０）
実施例１６で用いたグラフィアトに変えて、窒化硼素を用いた。
【０１５４】

上記材料を実施例１と同様にして分散し、メタノールで固形分を３５％に調整し塗料１２を得た。この塗料を実施例１と同様に現像剤担持体（１２）を作製した。トナー（６）を用いて、実施例１と同様に画出し評価した。
【０１５５】
（実施例２１）
実施例２０において、４級アンモニウム塩（１）を（２）に変えたこと以外は実施例２０と同様にして現像剤担持体（１３）を作製した。トナー（６）を用いて、実施例１と同様に画出し評価した。
【０１５６】
（実施例２２）
実施例２０で用いたグラファイトに変えて、二硫化モリブデンを用いた。
【０１５７】

上記材料を実施例１と同様にして分散し、メタノールで固形分を３５％に調整し塗料１４を得た。この塗料を実施例１と同様に現像剤担持体（１４）を作製した。トナー（６）を用いて、実施例１と同様に画出し評価した。
【０１５８】
（実施例２３）
下記の材料により作製された固形分を２０％に調整した塗料を用いた以外は、実施例１と同様にして現像剤担持体（１５）を作製し、トナー（６）を用いて、実施例１と同様に画出し評価した。
【０１５９】

【０１６０】
（実施例２４）
トナー製造例６において、機械的衝撃力による表面処理を行わない以外はトナー製造例７と同様にして、トナー（８）を得た。得られたトナー粒子の物性を表１に示す。
【０１６１】
実施例１６で作成した現像剤担持体（１０）とトナー（８）を用いて画出し評価を行った。
【０１６２】
（比較例４）
実施例１６で用いた４級アンモニウム塩化合物（１）の代わりに４級アンモニウム塩化合物（４）を用いた以外は実施例１６と同様にして塗料を作製し、比較用現像剤担持体４を得た。トナー（６）を用いて、実施例１と同様に画出し評価した。
【０１６３】
（比較例５）
実施例１６で用いた４級アンモニウム塩化合物（１）の代わりに、比較例３で用いたクロルフェノールを含むアゾナフトールのクロム錯体を用いた以外は実施例１６と同様にして比較用現像剤担持体５を作成し、トナー（６）を用いて、実施例１と同様に画出し評価した。
【０１６４】
（比較例６）
実施例１７において、導電性被覆層を形成しないで、粒径＃３００のガラスビーズを用いて、基体表面をサンドブラストしたＦＧＢスリーブを比較用現像剤担持体６とし、トナー（６）を用いて、実施例１と同様に画出し評価した。
【０１６５】
（評価）
下記に挙げる評価項目について耐久試験を行い、実施例及び比較例の現像剤担持体の評価を行った。
【０１６６】
（１）画像濃度
画出しは、２４℃、１０％ＲＨの常温低湿（Ｎ／Ｌ）、及び３０℃、８０％ＲＨの高温高湿（Ｈ／Ｈ）環境下にて、１０万枚（１００ｋ）まで行った。画像比率５．５％のテストチャート上のφ５黒丸の画像濃度を、反射濃度ＲＤ９１８（マクベス社製）で測定して、５点の平均点をとって画像濃度とした。
【０１６７】
（２）トナー帯電量（Ｑ／Ｍ）及びトナー搬送量（Ｍ／Ｓ）
現像スリーブ上に担持されたトナーを、金属円筒管と円筒フィルターにより吸引捕集し、その際金属円筒管を通じてコンデンサーに蓄えられた電荷量Ｑ、捕集されたトナー重量Ｍと、トナーを吸引した面積Ｓから、単位重量当たりの電荷量Ｑ／Ｍ（ｍＣ／ｋｇ）と単位面積当たりのトナー重量Ｍ／Ｓ（ｍｇ／ｃｍ^２）を計算し、それぞれトナー帯電量（Ｑ／Ｍ）、トナー搬送量（Ｍ／Ｓ）とした。
【０１６８】
（３）スジ、ムラ
ベタ黒、ハーフトーン、ライン画像等の各種画像を確認し、その際、現像スリーブ上のスジ、波状ムラ等、スリーブ上でのトナーコート不良の目視による観察を参考にして、評価結果を下記の指標で示した。
【０１６９】
◎ ：画像にもスリーブ上にも全く確認できない。
○ ：スリーブ上でわずかに確認できるが、画像ではほとんど確認できない。
○△：数枚〜数十枚に１枚程度画像を透かしてみると確認できる。
△○：ハーフトーン画像又はベタ黒画像の１枚目で、スリーブ周期の１周目に確認できる。
△ ：ハーフトーン画像又はベタ黒画像で確認できる。実用レベル下限。
△×：ベタ黒画像全体で画像不良が確認できる。実用不可レベル。
× ：ベタ白画像上にも確認できる。
【０１７０】
（４）ブロッチ
ベタ黒、ハーフトーン等の各種画像を確認し、その際、現像スリーブ上のブロッチ等のスリーブ上でのトナーコート不良の目視による観察を参考にして、評価結果を下記の指標で示した。
【０１７１】
◎ ：画像にもスリーブ上にも全く確認できない。
○ ：スリーブ上でわずかに確認できるが、画像ではほとんど確認できない。
○△：数枚〜数十枚に１枚程度画像を透かしてみると確認できる。
△○：ハーフトーン画像又はベタ黒画像の１枚目で、スリーブ周期の１周目に確認できる。
△ ：ハーフトーン画像又はベタ黒画像で確認できる。実用レベル下限。
△×：ベタ黒画像全体で画像不良が確認できる。実用不可レベル。
× ：ベタ白画像上にも確認できる。
【０１７２】
（５）ゴースト
ベタ白部とベタ黒部が隣り合う画像を現像した現像スリーブの位置が現像スリーブの次の回転時に現像位置に来て、ハーフトーン画像を現像するようにして、ハーフトーン画像上に現われる濃淡差を目視で下記の基準で評価した。
【０１７３】
○ ：濃淡差が全く見られない。
○△：軽微な濃淡差が見られる。
△ ：濃淡差がやや見られるが実用可。
× ：濃淡差が顕著に見られ、実用不可。
【０１７４】
（６）被覆層の耐汚染性
耐久後の現像剤担持体表面をＳＥＭで観察し、トナー汚染の程度を下記の基準で評価した。
【０１７５】
○ ：軽微な汚染が観察される。
○△：やや汚染が観察される。
△ ：部分的に汚染が観察される。
× ：著しい汚染が観察される。
【０１７６】
（７）導電性被覆層の削れ量（膜削れ）
ＫＥＹＥＮＣＥ社製レーザー法測定器を用いた。コントローラＬＳ−５５００およびセンサーヘッドＬＳ−５０４０Ｔを用い、スリーブ固定治具およびスリーブ送り機構を取り付けた装置にセンサー部を別途固定し、スリーブの外径寸法の平均値から測定を行った。測定はスリーブ長手方向に対し３０分割して３０箇所測定し、さらにスリーブを周方向に９０°回転させた後さらに３０箇所、計６０箇所の測定を行い、その平均値をとった。表面被覆層塗布前のスリーブの外径を予め測定しておき、表面被覆層形成後の外径、さらに耐久使用後の外径を測定し、その差分をコート膜厚および削れ量とした。
【０１７７】
【表１】

【０１７８】
【表２】

【０１７９】
【表３】

【０１８０】
【表４】

【０１８１】
【表５】

【０１８２】
【発明の効果】
以上説明したように、本発明によれば、現像剤の円相当径による粒度分布において、粒径０．６μｍ以上１．０μｍ未満の粒子の占める割合が個数基準で全体の５．０％未満である現像剤を用いる場合において、現像剤担持体基体上に形成された樹脂被覆層を、少なくとも結着樹脂と鉄粉に対して正帯電製である第４級アンモニウム塩化合物を含有する樹脂組成物より形成することで、現像剤に対して過剰耐電（チャージアップ）させることなく安定して適切な帯電付与を行うことができ、負帯電性トナーを好適なトリボにコントロールすることのできる現像方法、現像装置および画像形成装置が提供できる。
【０１８３】
さらには衝撃的表面処理装置により球形化処理されたチャージアップしやすく、従来安定した帯電付与が困難であった現像剤を用いた場合においても、好適なトリボにコントロールすることのできる現像方法、現像装置および画像形成装置が提供できる。
【０１８４】
また、現像剤に対して電荷をチャージアップさせにくく、異なる環境下においても安定して適切な帯電付与を行うことができる構成であるため、現像剤担持体表面への融着防止など耐汚染性に優れ、スジムラやゴースト、ブロッチの現れない高品位な画像を長期の画出し耐久においても、安定して提供することができる。
【図面の簡単な説明】
【図１】一成分磁性トナーを用いる現像装置の構成例を示す模式図である。
【図２】画像形成装置の構成例を示す模式図である。
【図３】トナーの円形度をコントロールするための処理システムの模式図である。
【図４】衝撃的比処理装置の例を示す模式図である。
【符号の説明】
１ 電子写真感光ドラム（潜像担持体）
２ 磁性規制ブレード
３ ホッパー
４ トナー（現像剤）
６ 金属製円筒管（基体）
７ 樹脂被膜層
８ 現像スリーブ（現像剤担持体）
９ 電源
１０ トナー攪拌翼
１１ 規制ブレード（現像剤層厚規制部材）[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a developing method for developing a latent image formed on an image carrier such as an electrophotographic photosensitive member or an electrostatic recording dielectric to visualize the latent image and an image forming apparatus using the same.
[0002]
[Prior art]
Conventionally, a number of methods are known as electrophotography. In general, a photoconductive substance is used to form an electric latent image on an electrostatic latent image carrier (photoreceptor) by various means. Then, the latent image is developed with a developer (toner) to form a visible image, and if necessary, the toner image is transferred to a transfer material such as paper, and then the toner image is transferred onto the transfer material by heat, pressure, or the like. This is to obtain a copy after fixing.
[0003]
Development methods in electrophotography are mainly classified into a one-component development method and a two-component development method. In recent years, since it is necessary to reduce the size of a copying apparatus for the purpose of reducing the weight and size of an electrophotographic apparatus, a developing apparatus using a one-component developer is often used.
[0004]
Unlike the two-component system, the one-component developing system does not require carrier particles such as glass beads and iron powder, so that the developing device itself can be reduced in size and weight. Further, in the two-component developing method, since it is necessary to keep the toner concentration in the developer constant, a device for detecting the toner concentration and supplying a necessary amount of toner is required. Therefore, the developing device is also large and heavy here. In the one-component developing system, such an apparatus is not necessary, so that the apparatus can be made small and light, which is preferable.
[0005]
For example, as a developing method using a one-component developer, an electrostatic latent image is formed on the surface of a photosensitive drum as an image carrier, and friction between a developing sleeve as a developer carrier and the developer, and / or A positive or negative charge is applied to the developer by friction between the developer regulating member and the developer that regulates the amount of the developer applied on the sleeve, and the developer is thinly applied on the developing sleeve to form a photosensitive drum and a developing sleeve. Are transported to a developing area where the surface of the photosensitive drum is opposed to the developing area, and the developer flies and adheres to the electrostatic latent image on the surface of the photosensitive drum in the developing area to develop the latent image, thereby developing the electrostatic latent image as a toner image. ing. As for printer devices, LED and LBP printers have become the mainstream in the recent market, and the direction of technology has been increased to higher resolution, that is, 300,400 dpi in the past, to 600,800,1200 dpi. Accordingly, the development system is required to have higher definition. In addition, the functions of the copiers are also becoming more sophisticated, and accordingly, they are moving toward digitalization. In this direction, the method of forming an electrostatic charge image with a laser is the main method, so it is also proceeding in the direction of high resolution, and here, as in the case of printers, high resolution and high definition development methods are required. JP-A-1-112253, JP-A-2-284158, and the like have proposed toners having a small particle diameter, and the toner particle diameter is proceeding in a further smaller direction.
[0006]
The toner image formed on the photoconductor in the development process is transferred to a transfer material in the transfer process. However, the transfer residual toner remaining on the photoconductor is cleaned in a cleaning process, and the toner is stored in a waste toner container. For this cleaning step, conventionally, blade cleaning, fur brush cleaning, roller cleaning, and the like have been used. From the viewpoint of the apparatus, the provision of such a cleaning apparatus inevitably increases the size of the apparatus, which has been a bottleneck when aiming for a more compact apparatus. Further, from the viewpoint of ecology, a system with a small amount of waste toner is desired in terms of effective utilization of the toner, and a toner having good transfer efficiency has been demanded.
[0007]
Japanese Unexamined Patent Publication (Kokai) No. 63-235953 proposes a magnetic toner which is made spherical by a mechanical impact force. However, the transfer efficiency is still insufficient and further improvement is needed.
[0008]
In the case of using such a spherical toner, it is difficult to adjust the toner charge, and although various measures have been taken with the developer, the toner is stable in durability such as non-uniformity of toner charge and occurrence of fusion to the sleeve surface. Sexual issues have not been completely solved.
[0009]
In particular, as the developing sleeve rotates repeatedly, the charge amount of the toner coated on the developing sleeve becomes too high due to the contact with the developing sleeve, and the toner attracts due to the mirroring force with the surface of the developing sleeve and develops. When a so-called charge-up phenomenon occurs, in which the toner is immobilized on the surface of the sleeve and does not move from the developing sleeve to the latent image on the electrostatic latent image holding member (drum), the toner in the upper layer is hardly charged, and the toner is developed. Since the amount is reduced, problems such as thinning of a line image and low image density of a solid image occur.
[0010]
Further, the toner particles that are not sufficiently charged due to the charge-up become out of regulation and flow out onto the sleeve, so that a so-called blotch phenomenon that causes spot-like and wavy unevenness occurs.
[0011]
Further, the toner layer formation state of the image portion (toner consuming portion) and the non-image portion change, and the charging state changes. For example, the position where a solid image having a high image density is developed is located next to the developing sleeve. When a halftone image is developed at the developing position during rotation, a phenomenon in which a solid image appears on the image, that is, a so-called sleeve ghost phenomenon is likely to occur. In particular, such a phenomenon is likely to occur remarkably when toner sphericalized by mechanical impact is used.
[0012]
As a method for solving such a phenomenon, as disclosed in JP-A-3-200986, a conductive coating layer in which a conductive fine powder such as a solid lubricant and carbon, and spherical particles are further dispersed in a resin is used. There has been proposed a method of using a sleeve provided on a metal base for a developing device.
[0013]
Although the use of this method is effective in preventing the charge-up phenomenon and improving the uniformity of charging, the addition of such a large amount of fine powder causes a problem of a decrease in durability due to abrasion of the sleeve surface layer. Further, when the toner is used for the toner subjected to the sphering treatment and having the property of high transfer efficiency used in the present invention, the developing sleeve is insufficient. Further, it has been proposed to add a material having the same polarity as the toner to the sleeve in order to lower the chargeability of the toner, but none of them can provide a satisfactory result. Therefore, further improvements such as prevention of charge-up phenomenon, improvement of uniformity of charging, improvement of sleeve ghost phenomenon, suppression of toner contamination and toner fusion, and the like are desired.
[0014]
[Problems to be solved by the invention]
Accordingly, an object of the present invention is to solve the above-described problems, to prevent a charge-up phenomenon when using a toner subjected to a sphering treatment, and to quickly and uniformly develop a toner capable of imparting charge to a toner. A method and an image forming apparatus are provided.
[0015]
Another object of the present invention is to provide a developing method and an image forming apparatus capable of stably obtaining a high-quality image free from problems such as thinning of a line image, low image density of a solid image, and sleeve ghost. That is.
[0016]
Further, an object of the present invention is to provide a developing method and an image forming apparatus which are less likely to cause toner contamination and toner fusion, have good durability, have a stable charge level even in long-term image formation, and can stabilize image performance. It is to be.
[0017]
[Means for Solving the Problems]
The above object is achieved by the present invention described below. That is, it has a latent image carrier, a developer carrier for carrying and transporting the developer, and a developer layer thickness regulating member for regulating the thickness of the developer layer on the developer carrier. The developer is pressed into contact with the developer carrier via the developer, and passes between the layer thickness regulating member and the developer carrier to carry and transport the formed thin developer layer to a developing area facing the latent image carrier. In a developing method of developing a latent image formed on a latent image carrier by a developer on the carrier and visualizing the latent image, the developer has at least a binder resin and a colorant, and In the particle size distribution based on the equivalent circle diameter, a developer having a particle size of 0.6 μm or more and less than 1.0 μm occupying less than 5.0% of the total number on a number basis is provided on the base of the developer carrying member. A developing method in which the resin layer contains a quaternary ammonium salt compound which is positively charged with respect to iron powder; Is achieved by law.
[0018]
A step of performing charging by a charging device to which a voltage is externally applied;
Forming an electrostatic latent image on the charged latent image carrier;
Supporting the developer contained in the developing container on a developer carrier;
Regulating the developer carried on the developer carrier by a developer layer thickness regulating member;
Transporting the developer carried on the developer carrier to a development area where the developer carrier and the electrostatic latent image carrier are opposed to each other;
Developing the electrostatic latent image formed on the latent image carrier;
A transfer step of transferring the developed image to a transfer material by a transfer unit and transferring the transferred image;
A fixing step of heating and fixing the transferred image transferred on the transfer body,
In an image forming method having at least,
The developer has at least a binder resin and a colorant, and the particle occupation ratio of particles having a particle diameter of 0.6 μm or more and less than 1.0 μm in the particle size distribution based on the equivalent circle diameter of the developer is 5. The developer is less than 0%, and the developer carrier comprises a substrate and a resin layer formed on the substrate, wherein the resin layer is a quaternary ammonium salt which is positively chargeable with respect to iron powder. This is achieved by an image forming apparatus containing a compound.
[0019]
Next, this operation will be described.
[0020]
The present inventors, prior to the present invention, a quaternary ammonium salt compound conventionally known as a positive charge control agent for a toner, that is, a quaternary ammonium salt which itself is positively chargeable with respect to iron powder. Using a salt compound, as a binder resin, in particular, part or all of the binder resin has at least -NH in its molecular structure.₂When the coating layer of the triboelectric charging member is formed using a compound having any one of a group, a = NH group and a -NH- bond, the quaternary ammonium salt compound is incorporated into the binder resin, and the resin (resin layer) itself is formed. Has a strong negative charging property and a good charging property with respect to the positive charging toner, and proposes that a very good image can be obtained by using this as a friction charging member in a developing device. It is carried out. The advantage of this method, for example, in comparison with a system in which silica, fluororesin powder, and a negative charge control agent are added to impart a positive charge to the toner, is that quaternary ammonium is contained in the binder resin solvent. Since the salt compound can be dissolved and uniformly present in the resin, when the resin layer is formed, the entire resin layer becomes a uniform negatively chargeable material and is dispersed in a matrix like a silica-added system. In addition, it has good charge-imparting properties as compared with the above, and furthermore, since it is not a powder-added system, the mechanical strength, that is, the durability is good.
[0021]
In view of these points, as a result of various studies, it was found that the developing device using the toner having the negative charge property and having undergone the spheroidization treatment was charged with the fourth charge control agent, which is conventionally known as the positive charge control agent for the toner. A quaternary ammonium salt compound, that is, a quaternary ammonium salt compound that itself is positively charged with respect to iron powder, and as a binder resin, particularly, a part or all of the binder resin has a molecule In the structure, -NH₂The formation of the coating layer of the developer carrying member using a compound having any one of a group, an = NH group and a -NH- bond causes charge-up, generation of a blotch and development of the spherically treated negatively chargeable toner. It has been found that it is possible to effectively prevent the strong adhesion of the developer to the surface of the agent carrier, and to charge the triboelectric charge to a suitable level by adjusting the amount of the quaternary ammonium salt compound added. This has led to the present invention.
[0022]
As the quaternary ammonium salt compound having the above-mentioned function, which is preferably used in the present invention, a compound having a positive charging property with respect to iron powder is used. For example, a compound represented by the following general formula [Formula 1] can be given.
[0023]
[Outside 1]

(R in the formula₁, R₂, R₃, R₄Represents an alkyl group which may have a substituent, an aryl group which may have a substituent, and an aralkyl group;_1-4May be the same or different. X⁻Represents an anion of an acid. )
[0024]
On the other hand, fluorinated quaternary ammonium salt compounds which themselves have a negative charge on iron powder, such as those represented by the following formula [Chemical Formula 2], were examined. It was found that the intended purpose of the present invention was not achieved in some cases. That is, the compound represented by the following formula [Formula 2] itself has a negative charge property on iron powder because a fluorine resin atom having a strong electron-withdrawing property is present in the structure. Similarly, even if a resin composition in which the compound is dispersed in a resin is used as a binder resin, and this is heated and dried to form a coating layer on the carrier core material, the carrier itself is positively charged with respect to iron powder. No effect was obtained as much as the quaternary ammonium salt compound was contained.
[0025]
[Outside 2]

[0026]
Specific examples of the quaternary ammonium salt compound which is preferably used in the present invention and which itself is positively charged with respect to iron powder include the following. Of course, the present invention provides However, the present invention is not limited to these.
[0027]
[Outside 3]

[0028]
[Outside 4]

[0029]
The amount of the quaternary ammonium salt compound used in the present invention as described above is preferably 1 to 100 parts with respect to 100 parts of the binder resin. If the amount is less than 1 part, the charge imparting property is not improved by the addition, and if it exceeds 100 parts, the dispersion in the binder resin becomes poor and the strength of the coating film tends to be reduced. In addition, since a positively chargeable quaternary ammonium salt is present in excess with respect to the resin component, the effective effects of the present invention begin to decrease. The binder resin used in the coating layer of the present invention is not particularly limited, but some or all of the binder resin has at least -NH in its molecular structure.₂It preferably has a structure of any one of a group, a = NH group and a -NH- bond. By forming a coating layer using such a resin, the effects of the present invention can be easily exhibited. In the present invention, when a resin layer of the developer carrier having the above-described configuration is used, a clear reason for the change to the negative charge imparting property is not clear, but is used in the present invention. A quaternary ammonium salt compound which itself is positively charged with respect to iron powder, and -NH₂A quaternary ammonium salt is incorporated into the resin structure by forming a resin coating layer using a binder resin having at least one structure of a group, = NH group, or -NH- bond. At that time, it is considered that the original structure of the quaternary ammonium salt having the positive polarity is lost, and the resin having the quaternary ammonium salt has a uniform and sufficient negative charging property.
[0030]
-NH₂As a substance having a group, R-NH₂A primary amine or a polyamine having the same, RCO-NH₂Examples of the substance having an ＮＨNH group, such as a primary amide represented by the following formula or a polyamide having the same, include a secondary amine represented by R ＝ NH or a polyamine having the same, (RCO)₂Examples of the substance having an -NH- bond, such as a secondary amide represented by = NH or a polyamide having the same, include a polyurethane having an -NHCOO- bond in addition to the above-described polyamine, polyamide, and the like. And one or more of these, or as a copolymer, and industrially synthesized resins are suitably used.
[0031]
Among them, phenol resins, polyamide resins, urethane resins and the like using ammonia as a medium are preferable from the viewpoint of versatility and the like. As a phenol resin, the present inventors have conducted intensive studies. As a result of using a phenol resin using a nitrogen-containing compound as a catalyst in the production process, the quaternary ammonium salt compound has the structure of the phenol resin when cured by heating. It was found that it was easily taken in. Therefore, by using such a phenol resin as one of the materials constituting the resin coating layer on the developer carrying member, a good developing device can be obtained. Examples of the nitrogen-containing compound used as a catalyst in the production process of the phenolic resin include, for example, acidic catalysts such as ammonium sulfate, ammonium phosphate, ammonium sulfamate, ammonium carbonate, ammonium acetate, and ammonium maleate; As the basic catalyst, ammonia or dimethylamine, diethylamine, diisopropylamine, diisobutylamine, diamylamine, trimethylamine, triethylamine, tri-n-butylamine, triamylamine, dimethylbenzylamine, diethylbenzylamine, dimethylaniline, diethylaniline , N, n-di-n-butylaniline, n, n-diamylaniline, n, n-di-t-amylaniline, n-methylethanol Lamine, n-ethylethanolamine, diethanolamine, triethanolamine, dimethylethanolamine, diethylethanolamine, ethyldiethanolamine, n-butyldiethanolamine, di-n-butylethanolamine, triisopropanolamine, ethylenediamine, hexamethylenetetraamine, etc. Amino compounds, pyridine, α-picoline, β-picoline, γ-picoline, pyridine such as 2,4-lutidine, 2,6-lutidine and derivatives thereof, quinoline compounds, imidazole, 2-methylimidazole, 2,4-dimethyl Imidazoles such as imidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 2-heptadecylimidazole and derivatives thereof Nitrogen-containing heterocyclic compounds such as and the like.
[0032]
As the polyamide resin, for example, nylon 6,66,610,11,12,9,13, Q2 nylon or the like, a copolymer of nylon containing these as a main component, N-alkyl-modified nylon, N-alkyl Any of alkoxylalkyl-modified nylon and the like can be suitably used. Furthermore, any resin containing a polyamide resin component, such as various resins modified with a polyamide such as a polyamide-modified phenol resin, or an epoxy resin using a polyamide resin as a curing agent, etc. Can also be suitably used.
[0033]
As the urethane resin, any resin containing a urethane bond can be suitably used. This urethane bond is obtained by a polymerization addition reaction between a polyisocyanate and a polyol.
[0034]
Examples of the polyisocyanate as a main raw material of the polyurethane resin include diphenylenemethane-4,4'-diisocyanate (MDI), isophorone diisocyanate (IPDI), polymethylene polyphenyl polyisocyanate, tolylene diisocyanate, hexamethylene diisocyanate, 5-naphthalene diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, carbodiimide-modified diphenylmethane-4,4'-diisocyanate, trimethylhexamethylene diisocyanate, orthotoluidine diisocyanate, naphthylene diisocyanate, xylene diisocyanate, paraphenylene diisocyanate, lysine diisocyanate methyl Esters, dimethyl diisocyanate and the like can be used.
[0035]
Polyols that are the main raw materials of polyurethane resins include polyester polyols such as polyethylene adipate ester, polybutylene adipate ester, polydiethylene glycol adipate ester, polyhexene adipate ester, and polycaprolactone ester; and polyethers such as polytetramethylene glycol and polypropylene glycol. Polyols and the like can be used.
[0036]
As the binder resin material of the coating layer, generally known resins other than those described above can be used. For example, styrene resin, vinyl resin, polyether sulfone resin, polycarbonate resin, polyphenylene oxide resin, fluororesin, cellulose resin, acrylic resin, epoxy resin, polyester resin, alkyd resin, melamine resin, urea resin, silicon A resin, a thermoplastic resin such as a polyimide resin, a photocurable resin, or the like can be used. Among them, those having releasability such as silicone resin and fluorine resin, or those having excellent mechanical properties such as polyether sulfone, polycarbonate, polyphenylene oxide, polyester, styrene resin and acrylic resin are more preferable.
[0037]
However, in order to easily achieve the object of the present invention, as described above, -NH₂It is preferable to use a binder resin having at least one structure of a group, ＮＨNH group, or —NH— bond, or modified by a group having such a structure. It is also possible to use a mixture with the above general binder resin.
[0038]
In the developer carrier used in the present invention, other conductive fine particles may be dispersed and contained in the binder resin in order to adjust the volume resistance of the coating layer. Such conductive fine particles preferably have a number average particle size of 20 μm or less, more preferably 10 μm or less. In order to avoid unevenness formed on the resin surface, a resin having a thickness of 1 μm or less is used.
[0039]
Examples of the configuration of the conductive fine particles used in the present invention include carbon black such as furnace black, lamp black, thermal black, acetylene black, and channel black; titanium oxide, tin oxide, zinc oxide, molybdenum oxide, potassium titanate, and oxides. Metal oxides such as antimony and indium oxide; metals such as aluminum, copper, silver, and nickel; and inorganic fillers such as graphite, metal fibers, and carbon fibers.
[0040]
The amount of the conductive fine particles in the above-mentioned coating layer is preferably in a range of 100 parts by weight or less based on 100 parts by weight of the binder resin. If the amount exceeds 100 parts by weight, the coating strength tends to decrease, and if a large amount of non-chargeable particles is added, the chargeability of the toner may decrease.
[0041]
The configuration of the resin coating layer of the developer carrier used in the present invention is preferable because the effect of the present invention is further promoted by dispersing a lubricating substance in the coating resin layer. Examples of the lubricating substance include fatty acid metal salts such as graphite, molybdenum disulfide, boron nitride, mica, graphite fluoride, silver-niobium selenide, calcium chloride-graphite, talc, zinc stearate and the like, and especially graphite. Is preferably used because it does not impair the conductivity of the coating layer. These lubricating substances preferably have a number average particle size of about 0.2 to 20 μm, more preferably 0.3 to 15 μm.
[0042]
Particularly preferable results are obtained when the amount of the lubricating substance is in the range of 10 to 120 parts by weight based on 100 parts by weight of the binder resin. If the amount exceeds 120 parts by weight, the film strength tends to decrease, and if a large amount of non-chargeable additive is added, the charge amount of the toner will decrease. Conversely, if the amount is less than 10 parts by weight, it is difficult to obtain the effect of preventing toner from adhering to the developer carrying member.
[0043]
Next, the configuration of the developer carrying member used in the present invention will be described. The developer carrier comprises a base and a resin layer surrounding and surrounding the base. As the substrate, there are a cylindrical member, a columnar member, a belt-like member, and the like. In a developing method without contacting the drum, a metal cylindrical tube is preferably used. A non-magnetic metal tube such as stainless steel, aluminum, or an alloy thereof is preferably used. In addition, as the base in the case of the developing method of directly contacting the drum, a cylindrical member having a layer structure containing a rubber or an elastomer such as urethane, EPDM, or silicon is preferably used.
[0044]
In addition, as a constitution of the resin coating layer of the developer carrying member, in addition to the above-mentioned additive substances, spherical particles having a particle size of 0.3 to 30 μm are dispersed in the coating resin layer to stabilize the surface roughness. As a result, it is possible to optimize the amount of toner coating on the developer carrying member. The spherical particles not only maintain uniform surface roughness on the surface of the coating layer of the developer carrying member, but also have a small change in the surface roughness of the coating layer even when the surface of the coating layer is worn out, as well as toner contamination and toner melting. This has the effect of making it less likely to wear.
[0045]
The spherical particles used in the present invention have a number average diameter of 0.3 to 30 μm, preferably 2 to 20 μm. When the number average particle diameter of the spherical particles is less than 0.3 μm, the effect of imparting uniform roughness to the surface and the effect of enhancing the charging performance are small, and the rapid and uniform charging of the developer becomes insufficient, and the coating layer This is not preferable because toner abrasion causes toner charge-up, toner contamination, and toner fusion, which tends to cause ghost deterioration and image density reduction. When the number average particle size exceeds 30 μm, the surface roughness of the coating layer becomes too large, and it becomes difficult to sufficiently charge the toner, and the mechanical strength of the coating layer is reduced, which is preferable. Absent. More preferably, the true density of the spherical particles is 3 g / cm³Or less, preferably 2.7 g / cm³Or less, more preferably 0.9 to 2.3 g / cm³Good to be. That is, the true density of the spherical particles is 3 g / cm.³When the value exceeds, the dispersibility of the spherical particles in the coating layer becomes insufficient, so that it becomes difficult to impart uniform roughness to the surface of the coating layer. In addition, since the storage stability of the paint is not good, it is difficult to obtain a triboelectric charging member surface having uniform surface irregularities.
[0046]
True density of spherical particles is 0.9 g / cm³Even when the particle size is smaller, the dispersibility and storage stability of the spherical particles in the coating layer become insufficient.
[0047]
In the present invention, the term “spherical” in the conductive spherical particles means a particle having a ratio of the major axis / minor axis of the particles of about 1.0 to 1.5, and preferably the major axis / minor axis in the present invention. It is preferable to use particles having a ratio of 1.0 to 1.2.
[0048]
When the ratio of the major axis / minor axis of the spherical particles exceeds 1.5, the surface roughness of the coating layer becomes non-uniform, resulting in rapid and uniform charging of the toner and the strength of the conductive coating layer. Not preferred.
[0049]
As the spherical particles used in the present invention, known spherical particles can be used. For example, there are spherical resin particles, spherical metal oxide particles, and spherical carbonized particles.
[0050]
As the spherical particles, for example, spherical resin particles obtained by suspension polymerization, dispersion polymerization, or the like are used. Spherical resin particles can obtain a suitable surface roughness with a smaller addition amount, and can easily obtain a more uniform surface shape. Examples of such spherical particles include acrylic resin particles such as polyacrylate and polymethacrylate, polyamide resin particles such as nylon, polyolefin resin particles such as polyethylene and polypropylene, silicone resin particles, phenol resin particles, and polyurethane resin particles. Resin particles, styrene resin particles, benzoguanamine particles, and the like. The resin particles obtained by the pulverization method may be used after subjecting them to thermal or physical sphering treatment.
[0051]
Further, an inorganic substance may be attached to or fixed to the surface of the spherical particles. Examples of such inorganic fine powder include SiO₂, SrTiO₃, CeO₂, CrO, Al₂O₃, Oxides such as ZnO, MgO, Si₃N₄Such as nitride, carbide such as SiC, CaSO₄, BaSO₄, CaCO₃, Sulfates, carbonates, and the like. Such an inorganic fine powder may be used after being treated with a coupling agent.
[0052]
In particular, it can be preferably used for the purpose of improving the adhesion to the binder resin or for imparting hydrophobicity to the particles. Examples of such a coupling agent include a silane coupling agent, a titanium coupling agent, a zircoaluminate coupling agent, and the like. More specifically, for example, as a silane coupling agent, hexamethyldisilazane, trimethylsilane, trimethylchlorosilane, trimethylethoxysilane, dimethyldichlorosilane, methyltrichlorosilane, allyldimethylchlorosilane, allylphenyldichlorosilane, Benzyldimethylchlorosilane, bromomethyldimethylchlorosilane, α-chloroethyltrichlorosilane, β-chloroethyltrichlorosilane, chloromethyldimethylchlorosilane, triorganosilylmercaptan, trimethylsilylmercaptan, triorganosilyl acrylate, vinyl idimethylacetoxysilane, Dimethyldiethoxysilane, dimethyldimethoxysilane, diphenyldiethoxysilane, hexamethyldisiloxane, 1,3-divinylte Tramethyldisiloxane, 1,3-diphenyltetramethyldisiloxane and dimethyl containing from 2 to 12 siloxane units per molecule and containing hydrogen groups bonded to silicon atoms, one for each terminal unit Examples include polysiloxane.
[0053]
By treating the surface of the spherical resin particles with the inorganic fine powder as described above, dispersibility in the coating layer, uniformity of the coating layer surface, stain resistance of the coating layer, charge imparting property to the toner, coating layer Can be improved in abrasion resistance and the like.
[0054]
The spherical particles used in the present invention are preferably conductive. That is, by imparting conductivity to the spherical particles, charge is less likely to be accumulated on the surface of the particles due to the conductivity, and it is possible to reduce adhesion of toner and improve the charge-imparting property to the toner. In the present invention, the volume resistivity of the spherical particles is 10⁶Ω · cm or less, more preferably 10^-3-10⁶The particles are preferably Ω · cm.
[0055]
In the present invention, the volume resistance of the spherical particles is 10⁶If it exceeds Ω · cm, the toner is likely to be contaminated or fused by spherical particles exposed on the surface of the coating layer due to abrasion, and it is difficult to perform quick and uniform charging. As a method for obtaining such conductive spherical particles, the following methods are preferable, but are not necessarily limited to these methods.
[0056]
As a particularly preferred method for obtaining conductive spherical particles used in the present invention, for example, low-density and good conductive particles obtained by firing and carbonizing and / or graphitizing resin-based spherical particles or mesocarbon microbeads A method of obtaining spherical carbon particles can be used. Examples of the resin used for the resin-based spherical particles include a phenol resin, a naphthalene resin, a furan resin, a xylene resin, a divinylbenzene polymer, a styrene-divinylbenzene copolymer, and polyacrylonitrile.
[0057]
In addition, mesocarbon microbeads can be usually produced by washing spherical crystals generated in the process of heating and firing a medium pitch with a large amount of a solvent such as tar, medium oil and quinoline.
[0058]
As a more preferable method for obtaining conductive spherical particles, the enol resin, naphthalene resin, furan resin, xylene resin, divinylbenzene polymer, styrene-divinylbenzene copolymer, polyacrylonitrile spherical resin particles such as polyacrylonitrile surface, mechanochemical method A method of obtaining a conductive spherical carbon particle by coating a bulk mesophase pitch with an oxidizing atmosphere, followed by heat treatment of the coated particle and then firing under an inert atmosphere or vacuum to carbonize and / or graphitize. Can be Spherical carbon particles obtained by this method are more preferable, because when graphitized, the coating portion of the obtained spherical carbon particles has advanced crystallization, so that the conductivity is improved.
[0059]
The conductive spherical carbon particles obtained by the above-described method can control the conductivity of the spherical carbon particles obtained by changing the firing conditions in any method, and are preferably used in the present invention. . In some cases, the spherical carbon particles obtained by the above method have a true density of the conductive spherical particles of 3 g / cm 3 in order to further increase the conductivity.³The plating of a conductive metal and / or metal oxide may be performed within a range not exceeding the above range.
[0060]
Another method for obtaining the conductive spherical particles used in the present invention is to mechanically mix conductive fine particles having a particle diameter smaller than the particle diameter of the core particles with a suitable mixing ratio with respect to the core particles composed of spherical resin particles. After the conductive fine particles are uniformly attached around the core particles by the action of van der Waalska and electrostatic force, the surface of the core particles is increased due to a local temperature rise caused by applying a mechanical impact force. Is softened, and conductive fine particles are formed on the surface of the core particles to obtain conductive resin-treated spherical resin particles.
[0061]
As still another method of obtaining the conductive spherical particles used in the present invention, a method of uniformly dispersing conductive fine particles in spherical resin particles to obtain conductive spherical particles in which conductive fine particles are dispersed is mentioned. No. As a method of uniformly dispersing the conductive fine particles in the spherical resin particles, for example, kneading a binder resin and the conductive fine particles to disperse the conductive fine particles, then solidify by cooling, and pulverized to a predetermined particle size A method of obtaining conductive spherical particles by mechanical and thermal treatments to obtain conductive spherical particles; or adding a polymerization initiator, conductive fine particles and other additives to a polymerizable monomer, and uniformly dispersing the same by a dispersing machine. The dispersed monomer composition is suspended in an aqueous phase containing a dispersion stabilizer so as to have a predetermined particle size by a stirrer or the like and polymerized to obtain spherical particles in which conductive fine particles are dispersed. Method.
[0062]
The method for forming the resin coating layer of the present invention is not particularly limited, for example, a dipping method, a spray method, a brushing method, and the like of a coating solution containing the composition of the present invention on a substrate of a developer carrier. The developer carrier of the present invention can be obtained by drying in the method described above.
[0063]
Next, in the present invention, a developer (toner) used for obtaining a visible image from an electrostatic latent image will be described.
[0064]
The equivalent circle diameter and the particle size distribution of the toner in the present invention were measured using a flow-type particle image analyzer FPIA-1000 manufactured by Toa Medical Electronics Co., Ltd. In this device, the equivalent circle diameter is measured as follows.
[0065]
As a measuring method, water (10^-3cm³The number of particles is 20 or less.) In about 50 ml, a few drops of a surfactant (preferably a phonate for alkylbenzene) is added as a dispersant, and about 2 to 20 mg of a measurement sample is further added. The dispersion treatment is performed for 3 minutes, and the particle concentration of the measurement sample is set to 4000 to 8000 particles / 10^-3cm³The sample solution adjusted as described above is flowed in a thin layer into the flow cell, and a projection photograph of the flowing particles is taken, the projected area of each particle is measured, and the diameter of a perfect circle having the same area is equivalent to a circle. The diameter was calculated, and the particle size distribution of the equivalent circle diameter was obtained, and the number-based% and the number average particle diameter of the particles having a particle diameter of 0.6 μm or more and 1.0 μm or less were calculated.
[0066]
Conventionally, there have been some devices capable of measuring a particle size of 1.0 μm or less. However, noise has a large effect in a region of 1.0 μm or less, and there is a problem in reproducibility of data. This apparatus is excellent in that reproducibility is good even in an area of 1.0 μm or less, and since information as a particle image is actually obtained at the same time, particles can be confirmed.
[0067]
In the particle size distribution of the toner particles according to the present invention, when the proportion of 0.6 μm or more and 1.0 μm or less is less than 5.0% on a number basis and the number average particle diameter is 4 to 10 μm, Can solve the problem.
[0068]
In the case where the ratio of 0.6 μm to 1.0 μm in the particle size distribution of the toner particles in the circle is 5.0% or more based on the number, the amount of the external additive per toner particle is reduced, and the amount of the external additive before transfer is reduced. In this case, the charge amount of the toner cannot be sufficiently increased, and the negative sleeve ghost deteriorates. When the number average particle size is less than 4 μm, cleaning failure occurs. When the number average particle size exceeds 10 μm, so-called filming in which the toner adheres to the photoreceptor occurs.
[0069]
If the number of particles having a circularity of a = 0.90 or more is less than 90% of the toner particles having a particle diameter of 3 μm or more, the adhesion of the toner to the photoconductor increases, and the transferability deteriorates. When 30% or more of the particles have a circularity of 0.98 or more, cleaning failure occurs.
[0070]
The circularity in the present invention is used as a simple method for quantitatively expressing the shape of particles, and is obtained from the following equation using, for example, a flow particle image analyzer FPIA-1000 manufactured by Toa Medical Electronics. Is defined as the circularity. The circularity distribution of the toner particles in the present invention was calculated by the following equation using the following particle image analyzer in the same manner as the above-described measurement of the equivalent circle diameter.
a = L0 / L
L0: Perimeter of a circle having the same projected area as the particle image
L: Perimeter of particle image
[0071]
Examples of the kind of the binder resin of the toner used in the present invention include, for example, a homopolymer of styrene such as polyethylene, poly-p-chlorostyrene and polyvinyltoluene and a substituted product thereof, and a styrene-p-chlorostyrene copolymer. Styrene-vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, styrene-acrylate copolymer, styrene-methacrylate copolymer, styrene-α-chloromethyl methacrylate copolymer, styrene-acrylonitrile Copolymer, styrene-vinyl methyl ether copolymer, styrene-vinyl ethyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-acrylonitrile-indene Styrene copolymer such as copolymer ; Polyvinyl chloride, phenolic resin, natural modified phenolic resin, natural resin modified maleic resin, acrylic resin, methacrylic resin, polyvinyl acetate, silicone resin, polyester resin, polyurethane, polyamide resin, furan resin, epoxy resin, xylene resin, Polyvinyl butyral, terpene resin, coumarone indene resin, petroleum resin, and the like can be used. A crosslinked styrene resin is also a preferred binder resin.
[0072]
Examples of the comonomer for the styrene monomer of the styrene copolymer include acrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, dodecyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, phenyl acrylate, and methacryl. Monocarboxylic acid having a double bond such as acid, methyl methacrylate, ethyl methacrylate, butyl methacrylate, octyl methacrylate, acrylonitrile, methacrylonitrile, acrylamide or a substituted product thereof; for example, maleic acid, butyl maleate Dicarboxylic acids having a double bond, such as methyl, methyl maleate, dimethyl maleate, and the like, and substituted products thereof; for example, vinyl esters such as vinyl chloride, vinyl acetate, and vinyl benzoate; Vinyls such as ethylene-based olefins such as styrene and butylene; vinyl ketones such as vinyl methyl ketone and vinyl hexyl ketone; vinyl ethers such as vinyl methyl ether, vinyl ethyl ether and vinyl isobutyl ether; Monomers may be used alone or in combination. Here, as the cross-linking agent, a compound having two or more polymerizable double bonds is mainly used, for example, an aromatic divinyl compound such as divinylbenzene, divinylnaphthalene, or the like; for example, ethylene glycol diacrylate, ethylene glycol diacrylate, or the like. Carboxylic acid esters having two double bonds such as methacrylate, 1.3-butanediol dimethacrylate; divinyl compounds such as divinylaniline, divinyl ether, divinyl sulfide, divinyl sulfone; and having three or more vinyl groups Compound can be used alone or as a mixture.
[0073]
Further, the toner may contain a pigment as a colorant. For example, carbon black, nigrosine dye, lamp black, Sudan Black SM, First Yellow G, Benzidine Yellow, Pigment Yellow, India First Orange, Irgazine Red, Paranitroaniline Red, Toluidine Red, Carmine FB, Permanent Bordeaux FRR, Pigment Orange R, Risor Red 2G, Lake Red C, Rhodamine FB, Rhodamine B Lake, Methyl Bio Red B Lake, Phthalocyanine Blue, Pigment Blue, Brilliant Green B, Phthalocyanine Green, Oil Yellow GG, Pomelo First Yellow CGG, Kaya Set Y963, Kaya Set YG, Pomelo First Orange RR, Oil Scarlet, Orazol Bra Down B, pomelo First Scarlet CG, Oil Pink OP, etc. can be applied.
[0074]
When the toner is used as a magnetic toner, a magnetic powder is contained in the toner. As such a magnetic powder, a substance that is magnetized in a magnetic field is used.
[0075]
Examples of the magnetic material include metal oxides containing elements such as iron, cobalt, nickel, copper, magnesium, manganese, aluminum, and silicon. Among them, those containing iron oxide as a main component, such as ferric oxide and γ-iron oxide, are preferable. Further, other metal elements such as a silicon element or an aluminum element may be contained from the viewpoint of controlling the chargeability of the toner. These magnetic particles preferably have a BET specific surface area of 2 to 3 m by a nitrogen adsorption method.²/ G, especially 3 to 28 m²/ G, and a magnetic powder having a Mohs hardness of 5 to 7 is more preferable.
[0076]
Examples of the shape of the magnetic material include an octahedron, a hexahedron, a sphere, a needle, a scale, and the like, and an octahedron, a hexahedron, a sphere, and an amorphous type having low anisotropy increase the image density. preferable. The average particle size of the magnetic material is preferably 0.05 to 1.0 μm, more preferably 0.1 to 0.6 μm, and further preferably 0.1 to 0.4 μm.
[0077]
The amount of the magnetic substance is 30 to 200 parts by mass, preferably 40 to 200 parts by mass, and more preferably 50 to 150 parts by mass based on 100 parts by mass of the binder resin. If the amount is less than 30 parts by mass, in a developing device that uses a magnetic force to transport the toner, the transportability is insufficient, and the developer layer on the developer carrier tends to be uneven, resulting in image unevenness. , The image density tends to decrease. On the other hand, if it exceeds 200 parts by mass, a problem tends to occur in the fixing property.
[0078]
In the present invention, when the above toner is used as a non-magnetic toner, it can be used as a two-component developer by mixing with a carrier, or can be used as a non-magnetic one-component developer without being mixed with a carrier. is there.
[0079]
In addition, as an external additive of the inorganic fine powder used in the toner of the present invention, inorganic fine powders such as silica, alumina and titania, or double oxides thereof are used for improving charge stability, developability, fluidity and storage stability. It is preferable to be selected from among objects. Further, silica is more preferable. For example, as the silica, both a so-called dry method produced by a vapor phase oxidation of a silicon halide and an alkoxide, or a so-called wet silica produced from a fumed silica, a dry silica and an alkoxide, a water glass, etc. can be used. However, there are few silanol groups on the surface and inside the silica fine powder, and Na₂O, SO₃ ^2-Dry silica with less production residue such as is preferred. Further, in the case of fumed silica, it is also possible to obtain a composite fine powder of silica and another metal oxide by using another metal halide such as aluminum chloride and titanium chloride together with a silicon halide in the production process. , And also those.
[0080]
The inorganic fine powder used in the present invention has a specific surface area of 30 m by nitrogen adsorption measured by the BET method.²/ G or more, especially 50 to 400 m²/ G gives good results, and 0.1 to 8 parts by mass, preferably 0.5 to 5 parts by mass, more preferably more than 1.0, of silica fine powder with respect to 100 parts by mass of the toner. It is particularly preferable to use up to 3.0 parts by mass.
[0081]
In addition, the inorganic fine powder used in the present invention may be, for example, a silicone varnish, a silicone oil, various modified silicone oils, a silane coupling agent, a silane coupling agent having a functional group for the purpose of hydrophobicity, charge control, etc. It is also possible and preferable to use a treating agent such as an organic silicon compound or an organic titanium compound or a combination of various treating agents.
[0082]
The specific surface area was determined by adsorbing nitrogen gas to the sample surface using a specific surface area measuring device Autosorb 1 (manufactured by Yuasa Ionics) according to the BET method, and calculating the specific surface area using the BET multipoint method.
[0083]
In order to maintain stable storage stability of the toner, the inorganic fine powder is preferably treated with at least silicone oil.
[0084]
If necessary, an external additive other than the silica fine powder may be added to the toner of the present invention.
[0085]
For example, resin fine particles that function as a charge assisting agent, a conductivity-imparting agent, a fluidity-imparting agent, an anti-caking agent, a releasing agent for fixing a hot roll, a lubricant, an abrasive, and the like.
[0086]
The fine resin particles preferably have an average particle size of 0.05 to 2.0 μm, and the polymerizable monomers constituting the resin include styrene, o-methylstyrene, m-methylstyrene, and p-methyl. Styrene monomers such as styrene / p-methoxystyrene / p-ethylstyrene; methacrylic acids such as acrylic acid / methacrylic acid; methyl acrylate / ethyl acrylate / n-butyl acrylate / isobutyl acrylate / n-acrylic acid Acrylates such as -propyl, n-octyl acrylate, dodecyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, 2-chloroethyl acrylate, phenyl acrylate, methyl methacrylate, ethyl methacrylate, and n-methacrylic acid -Propyl / n-butyl methacrylate / isomethacrylate Methacrylic esters such as butyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, phenyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, and other acrylonitrile, methacrylonitrile, Examples thereof include monomers such as acrylamide, benzoguanamine formaldehyde resin, and melamine-based resin, and it is particularly preferable to use melamine-based resin because it is possible to further improve quick and uniform charging. As the polymerization method, suspension polymerization, emulsion polymerization, soap-free polymerization and the like can be used, and more preferably, particles obtained by soap-free polymerization are preferable.
[0087]
In the present invention, if necessary, wax may be internally added to the toner particles. Examples of the wax used include polypropylene, polyethylene, microcrystalline wax, carnauba wax, sasol wax, paraffin wax, higher alcohol wax, ester wax and the like, and oxides and grafts thereof.
[0088]
These low molecular weight waxes may be added and mixed in the binder resin in advance during the production of the toner. The addition amount is preferably about 1 to 20 parts by mass with respect to 100 parts by mass of the binder resin.
[0089]
Further, in the toner of the present invention, a charge control agent may be blended (internally added) to the toner particles, if necessary. The charge control agent makes it possible to control the amount of charge optimally according to the development system. In particular, in the present invention, it is possible to further stabilize the balance between the particle size distribution and the amount of charge. The following substances control the toner to be negatively charged.
[0090]
For example, organic metal complexes and chelate compounds are effective, and examples thereof include monoazo metal complexes, acetylacetone metal complexes, aromatic hydroxycarboxylic acids, and aromatic dicarboxylic acid-based metal complexes. Other examples include aromatic hydroxycarboxylic acids, aromatic mono- and polycarboxylic acids and their metal salts, anhydrides, esters, and phenol derivatives such as bisphenol.
[0091]
The charge control agents described above are preferably used in the form of fine particles. In this case, the number average particle size of these charge control agents is particularly preferably 4 μm or less, more preferably 3 μm or less. When these charge control agents are internally added to the toner, it is preferable to use 0.1 to 20 parts by weight, particularly 0.2 to 10 parts by weight, based on 100 parts by weight of the binder resin.
[0092]
A conventionally known method is used to prepare a toner composed of the above-described materials. For example, binder resins, pigments, dyes, or magnetic substances as colorants, waxes, metal salts or metal complexes, charge control agents, and other additives that are added as necessary are commonly used. Is thoroughly mixed with a mixer such as a Henschel mixer or a ball mill, and then melt-kneaded using a heat kneader such as a heating roll, a kneader or an extruder to make the resins compatible with each other. The colorant, metal compound, etc. are dispersed or dissolved in the mixture, cooled and solidified, pulverized, and subjected to classification and surface treatment as necessary to obtain toner particles.Furthermore, inorganic fine powder is added and mixed. The production method is preferably used.
[0093]
As described above, in the present invention, in the particle size distribution based on the equivalent circle diameter, the toner occupying the ratio of 0.60 μm or more and less than 1.00 μm is adjusted to less than 5.0% by number, more preferably, A toner adjusted to a state in which particles having a circle-equivalent diameter of less than 1.0 μm have been removed is used. However, when toner particles having a circle-equivalent diameter of less than 1.0 μm are to be removed, a mechanical mechanism described below is used. It is preferable to perform the treatment by applying an impact force. That is, as in a device such as a mechano-fusion system manufactured by Hosokawa Micron Corporation or a hybridization system manufactured by Nara Machinery Co., Ltd., toner is pressed against the inside of the casing by centrifugal force by blades rotating at high speed, and a force such as a compressive force or a frictional force is applied. To apply a mechanical impact force to the toner. Specifically, in order to obtain a toner in which the proportion occupying 0.60 μm or more and less than 1.00 μm in the particle size distribution according to the circle equivalent diameter used in the present invention is adjusted to less than 5.0% on a number basis, the toner must be A method of adjusting the circularity distribution and the particle size distribution while finely pulverizing, or in addition to this, a surface treatment by mechanical impact force is preferably performed.
[0094]
The step of applying a mechanical impact force is usually performed after the fine pulverization process of the toner.In order to uniformly adjust the circularity distribution and the particle size distribution of the toner particles, it is better to process the particles after performing a certain amount of classification by a classification process. More effective.
[0095]
In the impact type surface treatment apparatus, as shown in FIGS. 1 and 2, the rotating shaft 161 is driven by a driving means, and the rotating disk 162 is rotated at a peripheral speed that does not break the particles due to the properties of the material to be surface-treated. The rapid airflow generated by the rotation of the rotating disk causes a circulation flow returning to the center of the rotating disk 162 around the circulation path 163 opened to the shock chamber 168.
[0096]
Next, a predetermined amount of the powder to be treated is charged from the raw material hopper 164 into the impact chamber 168, and the charged powder to be treated is instantaneously hit by the rotating disk 162 which rotates at a high speed. After rushing into 58 and receiving an impact action, the circulating flow returns to the impact chamber 168 again through the circulation path 163, where the impact action is applied again to perform surface treatment. The rotating disk is rotated so that the peripheral speed of the blade 155 is in the range of 60 m / sec to 150 m / sec.
[0097]
Either of the classification and the surface treatment may be performed first. In the classification process, it is preferable to use a multi-division classifier in terms of production efficiency.
[0098]
Next, the developing device and the image forming apparatus of the present invention as described above will be described.
[0099]
FIG. 3 is a schematic view of a developing device according to one embodiment of the present invention.
[0100]
In FIG. 3, an electrostatic latent image holder for holding an electrostatic latent image formed by a known process, for example, an electrophotographic photosensitive drum 1, is rotated in the direction of arrow A. The developing sleeve 8 serving as a developer carrier carries the one-component developer 4 having the magnetic toner supplied by the hopper 3 serving as a developer container. The developer 4 is conveyed to a developing area D where the photosensitive drum 1 and the photosensitive drum 1 face each other. As shown in FIG. 3, in the developing sleeve 8, a magnet roller 5 in which a magnet is inscribed is arranged in order to magnetically attract and hold the developer 4 on the developing sleeve 8.
[0101]
The developing sleeve 8 used in the developing device of the present invention has a conductive coating layer 7 coated on a metal cylindrical tube 6 as a base. A stirring blade 10 for stirring the developer 4 is provided in the hopper 3. The developing sleeve 8 and the magenet roller 5 are in a non-contact state.
[0102]
The developer 4 obtains a triboelectric charge capable of developing the electrostatic latent image on the photosensitive drum 1 by friction between the magnetic toner and the conductive coating layer 7 on the developing sleeve 8. In the example of FIG. 3, in order to regulate the layer thickness of the developer 4 conveyed to the development area D, the magnetic regulation blade 2 made of a ferromagnetic metal as the developer layer thickness regulation member is moved from the surface of the development sleeve 8. The lines of magnetic force from the magnetic pole N1 of the magnet roller 5 hanging down from the hopper 3 are concentrated on the magnetic regulating blade 2 so as to face the developing sleeve 8 with a gap width of about 50 to 500 μm, so that Then, a thin layer of the developer 4 is formed. In the present invention, a non-magnetic blade can be used instead of the magnetic regulating blade.
[0103]
Thus, the thickness of the thin layer of the developer 4 formed on the developing sleeve 8 is preferably smaller than the minimum distance between the developing sleeve 8 and the photosensitive drum 1 in the developing area D. .
[0104]
The developer carrying member of the present invention is particularly effective to be incorporated in a developing device of a system for developing an electrostatic latent image with a thin layer of the developer as described above, that is, a non-contact type developing device. In D, the developer carrier of the present invention can also be applied to a developing device in which the thickness of the developer layer is equal to or greater than the minimum gap between the developing sleeve 8 and the photosensitive drum 1, that is, a contact type developing device. .
[0105]
In order to avoid the complexity of the description, the following description will be made by taking the above-described non-contact type developing device as an example.
[0106]
A developing bias voltage is applied to the developing sleeve 8 by a developing bias power supply 9 serving as a bias unit in order to fly the one-component developer 4 having the magnetic toner carried on the developing sleeve 8. When a DC voltage is used as the developing bias voltage, a voltage having a value between the potential of the image portion of the electrostatic latent image (the region where the developer 4 is adhered and visualized) and the potential of the background portion is used as the developing sleeve. 8 is preferably applied.
[0107]
In order to increase the density of the developed image or to improve the gradation, an alternating bias voltage may be applied to the developing sleeve 8 to form an oscillating electric field in which the direction is alternately reversed in the developing region D. . In this case, it is preferable to apply to the developing sleeve 8 an alternating bias voltage in which a DC voltage component having an intermediate value between the potential of the developed image portion and the potential of the background portion is superimposed.
[0108]
In the case of so-called regular development, toner is attached to the high potential portion of an electrostatic latent image having a high potential portion and a low potential portion to visualize the toner. I do.
[0109]
In the case of so-called reversal development, a toner charged to the same polarity as the polarity of the electrostatic latent image is used for visualizing the toner by attaching toner to the low potential portion of the electrostatic latent image having a high potential portion and a low potential portion. I do.
[0110]
High potential and low potential are expressed by absolute values. In any of these cases, the developer 4 is charged at least by friction with the developing sleeve 8.
[0111]
FIG. 3 schematically illustrates the developing device of the present invention, and it goes without saying that there are various forms in the shape of the developer container (hopper 3), the presence or absence of the stirring blade 10, and the arrangement of the magnetic poles. Of course, these devices can also be used for development using a two-component developer containing a toner and a carrier.
[0112]
An example of an image forming apparatus using the developing device having the developer carrier of the present invention illustrated in FIG. 3 will be described with reference to FIG.
[0113]
First, the surface of the photosensitive drum 1 as an electrostatic latent image carrier is negatively charged by contact (roller) charging means 29 as primary charging means, and a digital latent image is formed by image scanning by exposure 25 to laser light. 1 is formed. Next, the above-described digital latent image is stored in a hopper 3 as a developing container by a developing device having a regulating blade 11 as a developer layer thickness regulating member and a developing sleeve 8 as a developer carrier. Is reversibly developed by a negatively chargeable one-component developer 4 having a magnetic toner of As shown in FIG. 4, the conductive substrate of the photosensitive drum 1 is grounded in the developing region D, and an alternating bias, a pulse bias, and / or a DC bias is applied to the developing sleeve 8 by a bias applying unit 9. Next, when the recording material P is conveyed and arrives at the transfer section, the contact (roller) transfer means 23 as a transfer means is charged by the voltage application means 24 from the back surface (the surface opposite to the photosensitive drum side) of the recording material P. As a result, the developed image formed on the surface of the photosensitive drum 1 is transferred onto the recording material P by the contact transfer unit 23. Next, the recording material P separated from the photosensitive drum 1 is transported to a heating and pressing roller fixing device 27 as a fixing unit, and the fixing device 27 performs a fixing process of a developed image on the recording material P. .
[0114]
The one-component developer 4 remaining on the photosensitive drum 1 after the transfer process is removed by a cleaning unit 28 having a cleaning blade 28a. When the remaining one-component developer 4 is small, the cleaning step can be omitted. After the cleaning, the photosensitive drum 1 is neutralized by the erase exposure 26 if necessary, and the above-described steps starting from the charging step by the contact (roller) charging means 29 as the primary charging means are repeated again.
[0115]
In the above series of steps, the photosensitive drum (that is, the electrostatic latent image carrier) 1 has a photosensitive layer and a conductive substrate, and moves in the direction of the arrow. The developing sleeve 8 rotates so as to advance in the same direction as the surface of the photosensitive drum 1 in the developing area D. The one-component developer 4 in the hopper 3 is carried on the developing sleeve 8 and is provided with, for example, a negative triboelectric charge by friction with the surface of the developing sleeve 8 and / or friction between toners. Further, the regulating blade 11 regulates the thickness of the developer layer thinly (30 μm to 300 μm) and uniformly to form a developer layer thinner than the gap between the photosensitive drum 1 and the developing sleeve 8 in the developing region D. . By adjusting the rotation speed of the developing sleeve 8, the surface speed of the developing sleeve 8 is substantially equal to or close to the speed of the surface of the photosensitive drum 1. In the developing region D, an AC bias or a pulse bias may be applied to the developing sleeve 8 as a developing bias voltage by the bias applying unit 9. The AC bias may be such that f is 200 to 4,000 Hz and Vpp is 500 to 3,000 V.
[0116]
When the developer is transferred in the developing area D, the developer is transferred to the electrostatic latent image side by the electrostatic force on the surface of the photosensitive drum 1 and the action of a developing bias voltage such as an AC bias or a pulse bias.
[0117]
The primary charging means has been described using the charging roller 29 as the contact charging means as described above, but may be a contact charging means such as a charging blade or a charging brush, or a non-contact corona charging means. However, the contact charging means is preferable in that the generation of ozone due to charging is small.
[0118]
Although the transfer unit has been described using the contact transfer unit such as the transfer roller 23 as described above, a non-contact corona transfer unit may be used. However, in this case, the contact transfer unit is more preferable because ozone is less generated by the transfer.
[0119]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.
[0120]

[0121]
The above materials are mixed in a blender, melt-kneaded in a twin-screw extruder heated to 130 ° C., and the cooled kneaded material is coarsely pulverized by a hammer mill. Finely ground by means. The obtained finely pulverized product was subjected to 1.96 × 10 4 by a multi-partition classifier using the Coanda effect, in which a forced powder dispersing device using compressed air was incorporated in a powder supply section.^-1It is supplied while forcibly dispersing with compressed air of MPa, strictly classified, and the ratio of particles having a number average circle equivalent diameter of 6.3 μm, and a circle equivalent diameter of 0.6 μm to 1.0 μm is occupied on a number basis. 3.9% of a magnetic toner was obtained.
[0122]
Further, the magnetic toner particles were subjected to a surface treatment using a surface reforming apparatus of a type in which a rotor was rotated to apply a mechanical impact force. The number average circle equivalent diameter of the obtained toner particles 1 is 6.7 μm, and the ratio of particles having an equivalent circle diameter of 0.6 μm or more and 1.0 μm or less is 0.6% based on the number of particles and the particle diameter is 3.0 μm or more. In the toner No., particles having a circularity a = 0.90 or more accounted for 95.4% on a number basis, and particles having a circularity a = 0.98 or more accounted for 23.5% on a number basis.
[0123]
1.5% of silicone oil and dry silica treated with hexamethyldisilazane were added to the obtained toner particles 1 and mixed with a mixer to obtain a toner (1).
[0124]
(Toner Production Examples 2 to 4)
The surface treatment was performed by changing the conditions of the surface treatment by the mechanical impact force in Production Example 1. To the obtained toner particles, 1.5% of silicone oil and hexamethyldisilazane-treated dry silica were added in the same manner as in Toner Production Example 1, and mixed with a mixer to obtain toners (2) to (4). . Table 1 shows the physical properties of the obtained toner particles.
[0125]
(Toner Production Example 5)
A toner (5) was obtained in the same manner as in Toner Production Example 1, except that the surface treatment by mechanical impact was not performed. Table 1 shows the physical properties of the obtained toner particles.
[0126]
Next, the production of the developing sleeve will be described.
[0127]
First, the triboelectric charge of the quaternary ammonium salt compound (1) with iron powder was determined by a blow-off method using a commercially available triboelectric charge meter (TB-200, manufactured by Toshiba Chemical), and was found to be positive. .
[0128]
As conductive spherical particles, a coal-based bulk mesophase having a number average particle size of 1.5 μm or less was added to 100 parts by mass of a spherical phenol resin having a number average particle size of 5.5 μm using a raikai machine (automatic mortar, manufactured by Ishikawa Plant). Conductive spherical carbon particles obtained by uniformly coating 14 parts by weight of the pitch powder, performing heat stabilization treatment in an oxidizing atmosphere, and calcining at 2,200 ° C. to graphitize were used. The spherical carbon particles had a number average particle size of 5.0 μm and a true density of 1.50 g / cm.³, Volume resistance 7.5 × 10^-2Ω · cm and the ratio of major axis / minor axis was 1.15.
[0129]
Table 2 shows the physical properties of the particles.
[0130]

[0131]
The above-mentioned material was dispersed in zirconia particles of 2 mm in diameter using a sand mill for 3 hours. Thereafter, the zirconia particles were separated by a sieve, and the solid content was adjusted to 30% with methanol to obtain Paint 1. A 10 μm film was formed on an Al cylindrical body having a diameter of 24.5 mm by spraying, and then heated and cured at 150 ° C. for 30 minutes using a hot air drier to produce a developer carrier (1). Table 3 shows the paint formulation and the properties of the developer carrier.
[0132]
This developer carrier was incorporated into an NP6350 (copier made by Canon Inc.), and an image was formed using the developer described above. The results are shown in Tables 4 and 5. Good results.
[0133]
(Example 2)
When the charge amount of the quaternary ammonium salt compound (2) was measured by blow-off using iron powder in the same manner as in Example 1, the charge was positive. A coating material 2 was prepared in the same manner as in Example 1 except that the quaternary ammonium salt compound (2) was used in Example 1, and a developer carrier (2) was obtained. This was evaluated for image formation in the same manner as in Example 1. Good results.
[0134]
(Example 3)
When the charge amount of the quaternary ammonium salt compound (3) was measured by blow-off using iron powder in the same manner as in Example 1, the charge was positive. A coating material 3 was obtained in the same manner as in Example 1 except that the quaternary ammonium salt compound (3) was used in Example 1, and a developer carrier (3) was produced. This was evaluated for image formation in the same manner as in Example 1. Good results.
[0135]
(Examples 4 to 6)
The developer carrying members (1) to (3) prepared in Examples 1 to 3 were evaluated for image formation in the same manner as in Example 1 using the toner (2) prepared in Toner Production Example 2. Good results.
[0136]
(Example 7)
A developer carrier (4) was obtained in the same manner as in Example 1, except that the amount of the quaternary ammonium salt compound (1) was changed from 50 parts by mass to 5 parts by mass to prepare the paint 4. The same evaluation as in Example 1 was performed.
[0137]
(Example 8)
A developer carrier (5) was obtained in the same manner as in Example 1, except that the amount of the quaternary ammonium salt compound (1) was changed from 50 parts by mass to 80 parts by mass to prepare the paint 5. The same evaluation as in Example 1 was performed.
[0138]
(Example 9)
A developer carrier (6) was obtained in the same manner as in Example 1, except that the amount of the granular carbon particles (A) having a number average particle diameter of 5 μm was changed from 20 parts by mass to 50 parts by mass to prepare the coating material 6. Was. The same evaluation as in Example 1 was performed.
[0139]
(Example 10)
A developer carrier (7) was obtained in the same manner as in Example 1, except that spherical carbon particles having a number average diameter of 2.1 μm were prepared in the same manner as in Example 1. The same evaluation as in Example 1 was performed.
[0140]
(Example 11)
A developer carrier (8) was obtained in the same manner as in Example 1, except that spherical carbon particles having a number average diameter of 20.3 μm were prepared in the same manner as in Example 1. The same evaluation as in Example 1 was performed.
[0141]
(Example 12)
A developer carrier (9) in the same manner as in Example 1, except that PMMA particles having a number average particle size of 5.1 μm were used instead of the spherical carbon particles having a number average particle size of 5 μm used in Example 1. Was prepared, and the same evaluation as in Example 1 was performed. The PMMA particles have a true density of 1.19 g / cm.³, Volume resistance 10^FifteenAs described above, Ω · cm and the ratio of major axis / minor axis were 1.12.
[0142]
(Examples 13 to 15)
The same image formation evaluation was performed using the developer carrier (1) and the toners (3) to (5) prepared in Example 1.
[0143]

[0144]
The above materials were dispersed in the same manner as in Example 1, and the solid content was adjusted to 30% with IPA to obtain Comparative Paint 1. This paint was used to produce a comparative developer carrier 1 in the same manner as in Example 1, and evaluated in the same manner as in Example 1.
[0145]
(Comparative Example 2)
A coating material was prepared in the same manner as in Example 1 except that the quaternary ammonium salt compound (4) of the following formula was used in place of the quaternary ammonium salt compound (1) used in Example 1, and a developer for comparison was loaded. Body 2 was obtained. This was evaluated for image formation in the same manner as in Example 1. The charge amount of the quaternary ammonium salt compound (4) was measured by blow-off using iron powder in the same manner, and the result showed negative polarity.
[Outside 5]

[0146]
(Comparative Example 3)
The amount of triboelectric charge of the chromium complex of azonaphthol containing chlorophenol with the iron powder was determined by a blow-off method in the same manner as in Example 1, and the result was negative. Comparative developer carrier 3 was prepared in the same manner as in Example 1 except that a chromium complex of azonaphthol containing chlorophenol was used instead of the quaternary ammonium salt compound (1). Image evaluation was performed in the same manner as in Example 1.
[0147]

The above materials were dispersed in the same manner as in Example 1, and the solid content was adjusted to 35% with methanol to obtain a developer carrying member (10).
[0148]

Using the above materials, a toner was produced in the same manner as in Toner Production Example 1. A magnetic toner having a number average circle-equivalent diameter of 6.9 μm and particles having a circle-equivalent diameter of 0.6 μm or more and 1.0 μm or less occupying 3.3% of the total number of particles was obtained.
[0149]
Further, the magnetic toner particles were subjected to a surface treatment using a surface modification device. The number average circle equivalent diameter of the obtained toner particles is 7.2 μm, and the ratio of particles having an equivalent circle diameter of 0.6 μm or more and 1.0 μm or less occupies 0.9% of the total number and the particle diameter is 3.0 μm or more. In the toner, particles having a circularity a = 0.90 or more accounted for 95.7% on a number basis, and particles having a circularity a = 0.98 or more accounted for 24.6% on a number basis.
[0150]
1.3% of silicone oil and dry silica treated with hexamethyldisilazane were added to the obtained toner particles, and mixed with a mixer to obtain a toner (6).
[0151]
(Toner Production Example 7)
The surface treatment was performed by changing the conditions of the surface treatment by the mechanical impact force in Production Example 6. To the obtained toner particles, in the same manner as in Toner Production Example 6, the addition amount of silicone oil and dry silica treated with hexamethyldisilazane was added to 1.3% to obtain a toner (7). The same evaluation as in Example 1 was performed using the toner (6) and the toner (7).
[0152]
(Examples 18 and 19)
A developer carrier (11) was obtained in the same manner as in Example 16, except that the amount of the quaternary ammonium salt compound (1) was changed from 90 parts by mass to 50 parts by mass to prepare the coating material 11. The same evaluation as in Example 1 was performed using the toner (6) and the toner (7).
[0153]
(Example 20)
Boron nitride was used instead of the graphite used in Example 16.
[0154]

The above materials were dispersed in the same manner as in Example 1, and the solid content was adjusted to 35% with methanol to obtain Paint 12. A developer carrier (12) was prepared from this paint in the same manner as in Example 1. Using the toner (6), image formation was evaluated in the same manner as in Example 1.
[0155]
(Example 21)
A developer carrying member (13) was produced in the same manner as in Example 20, except that the quaternary ammonium salt (1) was changed to (2). Using the toner (6), image formation was evaluated in the same manner as in Example 1.
[0156]
(Example 22)
Instead of the graphite used in Example 20, molybdenum disulfide was used.
[0157]

The above materials were dispersed in the same manner as in Example 1, and the solid content was adjusted to 35% with methanol to obtain Paint 14. Using this paint, a developer carrier (14) was produced in the same manner as in Example 1. Using the toner (6), image formation was evaluated in the same manner as in Example 1.
[0158]
(Example 23)
A developer carrier (15) was prepared in the same manner as in Example 1, except that a coating material having a solid content adjusted to 20% was prepared using the following materials, and a toner (6) was used. The image formation was evaluated in the same manner as in Example 1.
[0159]

[0160]
(Example 24)
In toner production example 6, a toner (8) was obtained in the same manner as in toner production example 7, except that surface treatment by mechanical impact was not performed. Table 1 shows the physical properties of the obtained toner particles.
[0161]
Using the developer carrier (10) and the toner (8) prepared in Example 16, image formation evaluation was performed.
[0162]
(Comparative Example 4)
A coating material was prepared in the same manner as in Example 16 except that the quaternary ammonium salt compound (4) was used instead of the quaternary ammonium salt compound (1) used in Example 16, and the comparative developer carrier 4 was used. Obtained. Using the toner (6), image formation was evaluated in the same manner as in Example 1.
[0163]
(Comparative Example 5)
A developer for comparison was loaded in the same manner as in Example 16 except that the chromium complex of azonaphthol containing chlorophenol used in Comparative Example 3 was used instead of the quaternary ammonium salt compound (1) used in Example 16. A body 5 was prepared, and image formation was evaluated in the same manner as in Example 1 using the toner (6).
[0164]
(Comparative Example 6)
In Example 17, an FGB sleeve whose substrate surface was sandblasted using glass beads having a particle size of # 300 without forming a conductive coating layer was used as a comparative developer carrier 6, and a toner (6) was used. Image formation evaluation was performed in the same manner as in Example 1.
[0165]
(Evaluation)
A durability test was performed for the following evaluation items, and the developer carrying members of Examples and Comparative Examples were evaluated.
[0166]
(1) Image density
Image formation was performed up to 100,000 sheets (100k) in a normal temperature and low humidity (N / L) environment of 24 ° C and 10% RH, and a high temperature and high humidity (H / H) environment of 30 ° C and 80% RH. . The image density of φ5 black circles on the test chart having an image ratio of 5.5% was measured with a reflection density RD918 (manufactured by Macbeth), and the average of the five points was taken as the image density.
[0167]
(2) Toner charge amount (Q / M) and toner transport amount (M / S)
The toner carried on the developing sleeve is collected by suction using a metal cylindrical tube and a cylindrical filter. At this time, the charge amount Q stored in the condenser, the collected toner weight M, and the toner are suctioned through the metal cylindrical tube. From the area S, the charge amount per unit weight Q / M (mC / kg) and the toner weight per unit area M / S (mg / cm)²) Was calculated, and the toner charge amount (Q / M) and the toner transport amount (M / S) were calculated.
[0168]
(3) Streaks and unevenness
Various images such as solid black, halftone, and line images were confirmed. At that time, the evaluation results were as follows with reference to visual observation of toner coat defects on the sleeve, such as streaks on the developing sleeve and wavy unevenness. Indicated by index.
[0169]
：: Neither the image nor the sleeve can be confirmed at all.
：: Slightly confirmed on the sleeve, but hardly confirmed on the image.
△: This can be confirmed by seeing through about one image out of several to several tens of images.
Δ ○: The first halftone image or solid black image, which can be confirmed in the first cycle of the sleeve cycle.
Δ: Confirmable with a halftone image or solid black image. Practical level lower limit.
Δ ×: Image defects can be confirmed on the entire solid black image. Impossible level.
X: It can also be confirmed on a solid white image.
[0170]
(4) Blotch
Various images such as solid black and halftone were confirmed. At this time, evaluation results were indicated by the following indices with reference to visual observation of toner coating failure on a sleeve such as a blotch on a developing sleeve.
[0171]
：: Neither the image nor the sleeve can be confirmed.
：: Slightly confirmed on the sleeve, but hardly confirmed on the image.
△: This can be confirmed by seeing through about one image out of several to several tens of images.
Δ ○: The first halftone image or solid black image, which can be confirmed in the first cycle of the sleeve cycle.
Δ: Confirmable with a halftone image or solid black image. Practical level lower limit.
Δ ×: Image defects can be confirmed on the entire solid black image. Impossible level.
X: It can also be confirmed on a solid white image.
[0172]
(5) Ghost
The position of the developing sleeve that has developed the image in which the solid white part and the solid black part are adjacent comes to the developing position at the next rotation of the developing sleeve, and develops the halftone image. It was visually evaluated according to the following criteria.
[0173]
：: No difference in shade was observed.
○ △: A slight difference in shading is observed.
Δ: Shading difference is slightly observed, but practical.
X: The difference in shading is remarkable, and it is not practical.
[0174]
(6) Stain resistance of the coating layer
The surface of the developer bearing member after the endurance was observed by SEM, and the degree of toner contamination was evaluated according to the following criteria.
[0175]
: Slight contamination is observed.
○ △: Slight contamination is observed.
Δ: Contamination is partially observed.
X: Remarkable contamination is observed.
[0176]
(7) Shaving amount of conductive coating layer (film shaving)
A laser method measuring instrument manufactured by KEYENCE was used. Using the controller LS-5500 and the sensor head LS-5040T, the sensor section was separately fixed to a device to which a sleeve fixing jig and a sleeve feeding mechanism were attached, and measurement was performed from the average value of the outer diameter of the sleeve. The measurement was carried out at 30 points in 30 divisions in the longitudinal direction of the sleeve, and after the sleeve was rotated 90 ° in the circumferential direction, 30 points were further measured at a total of 60 points, and the average value was obtained. The outer diameter of the sleeve before the application of the surface coating layer was measured in advance, the outer diameter after the formation of the surface coating layer, and the outer diameter after the durable use were measured, and the difference was defined as the coating film thickness and the shaved amount.
[0177]
[Table 1]

[0178]
[Table 2]

[0179]
[Table 3]

[0180]
[Table 4]

[0181]
[Table 5]

[0182]
【The invention's effect】
As described above, according to the present invention, in the particle size distribution according to the circle equivalent diameter of the developer, the ratio of particles having a particle diameter of 0.6 μm or more and less than 1.0 μm is less than 5.0% of the total on a number basis. In the case where a certain developer is used, a resin composition containing a quaternary ammonium salt compound which is formed by positively charging at least a binder resin and iron powder with a resin coating layer formed on a developer carrier base A developing method capable of stably providing an appropriate charge without excessively withstanding (charging up) the developer, and controlling a negatively chargeable toner to a suitable tribo. A developing device and an image forming device can be provided.
[0183]
Furthermore, even when using a developer which has been subjected to spheroidization treatment by an impact surface treatment apparatus and is easily charged up, and it has been difficult to provide a stable charge in the past, a developing method and a development method capable of controlling to a suitable tribo are available. An apparatus and an image forming apparatus can be provided.
[0184]
In addition, since it is difficult to charge up the developer, and it is possible to stably and appropriately apply charge even under different environments, contamination resistance such as prevention of fusion to the surface of the developer carrier is prevented. It is possible to stably provide a high-quality image free from streaks, ghosts, and blotches even in long-term image output durability.
[Brief description of the drawings]
FIG. 1 is a schematic diagram illustrating a configuration example of a developing device using one-component magnetic toner.
FIG. 2 is a schematic diagram illustrating a configuration example of an image forming apparatus.
FIG. 3 is a schematic diagram of a processing system for controlling the circularity of toner.
FIG. 4 is a schematic view showing an example of an impact ratio processing device.
[Explanation of symbols]
1. Electrophotographic photosensitive drum (latent image carrier)
2 Magnetic regulation blade
3 Hopper
4 Toner (developer)
6. Metallic cylindrical tube (substrate)
7 Resin coating layer
8 Developing sleeve (developer carrier)
9 Power supply
10 Toner stirring blade
11 Regulation blade (developer layer thickness regulation member)

Claims (17)

A latent image carrier, a developer carrier for carrying and transporting the developer, and a developer layer thickness regulating member for regulating a developer layer thickness on the developer carrier; The developer thin layer formed by passing between the developer carriers is carried and transported to a development area facing the latent image carrier, and the developer on the developer carrier carries the developer thin layer on the latent image carrier. In a developing method of developing a formed latent image to make it a visible image, the developer has at least a binder resin and a colorant, and has a particle size distribution of 0 in the particle size distribution according to the circle equivalent diameter of the developer. The proportion of particles having a particle size of not less than 0.6 μm and less than 1.0 μm is less than 5.0% of the whole by number, and the developer carrier comprises a substrate and a resin coating layer formed on the substrate. The resin coating layer should contain a quaternary ammonium salt compound that is at least positively charged with respect to iron powder. And a developing method. 2. The resin coating layer according to claim 1, wherein a part or all of the binder resin has at least one of —NH ₂ group, ＝ NH group, and —NH— bond in its molecular structure. 3. The developing method described in 1. above. The developing method according to claim 1, wherein the resin layer contains at least a phenol resin. Phenolic resin, a phenolic resin produced using a nitrogen-containing compound as a catalyst, -NH ₂ group in its structure, = NH group claim 3 or -NH- is a phenol resin having either binding, The developing method described in the above. 5. The developing method according to claim 1, wherein a conductive fine powder is further dispersed and contained in the resin layer of the developer carrier to form a conductive coating layer. The developing method according to claim 1, wherein the developer has been subjected to a process of reducing particles having a circle equivalent diameter of less than 1.0 μm. 7. The developing method according to claim 6, wherein the process of reducing particles having an equivalent circle diameter of less than 1.0 μm is performed by a process of applying a mechanical impact force. The developer has 90% to 100% by number of particles having a circularity a of 0.90 or more determined by the following formula (1) in the particles of 3 μm or more, and has a circularity a of 0.98 or more. The developing method according to claim 1, wherein the number of particles is less than 30% based on the number.
a = L0 / L (Equation 1)
L0: Perimeter of a circle having the same projected area as the particle image L: Perimeter of the particle image A latent image carrier, a developer carrier for carrying and transporting the developer, and a developer layer thickness regulating member for regulating a developer layer thickness on the developer carrier; The developer thin layer formed by passing between the developer carriers is carried and transported to a development area facing the latent image carrier, and the developer on the developer carrier carries the developer thin layer on the latent image carrier. In a developing device that develops the formed latent image into a visible image, the developer has at least a binder resin and a colorant, and has a particle size distribution of 0 in the particle size distribution according to the circle equivalent diameter of the developer. The proportion of particles having a particle size of not less than 0.6 μm and less than 1.0 μm is less than 5.0% of the whole by number, and the developer carrier comprises a substrate and a resin coating layer formed on the substrate. The resin coating layer should contain a quaternary ammonium salt compound that is at least positively charged with respect to iron powder. And a developing device. The resin coating layer, a part or all of the binder resin, at least in its molecular structure, -NH ₂ group, = NH group claim 9, characterized or -NH- bonds that have either, 3. The developing device according to claim 1. The developing device according to claim 9, wherein the resin layer contains at least a phenol resin. The phenol resin is a phenol resin produced using a nitrogen-containing compound as a catalyst, and the phenol resin has any one of an —NH ₂ group, an ＮＨNH group, and an —NH— bond in its structure. The developing device as described in the above. The developing device according to claim 9, wherein a conductive fine powder is further dispersed and contained in the resin layer of the developer carrier to form a conductive coating layer. The developing device according to claim 9, wherein the developer has been subjected to a process of reducing particles having a circle-equivalent diameter of less than 1.0 μm. The developing device according to claim 14, wherein the process of reducing particles having a circle equivalent diameter of less than 1.0 µm is performed by a process of applying a mechanical impact force. The developer has 90% to 100% by number of particles having a circularity a of 0.90 or more determined by the following formula (1) in the particles of 3 μm or more, and has a circularity a of 0.98 or more. The developing device according to any one of claims 9 to 15, wherein the developing device has less than 30% of particles based on the number. A step of charging by a charging device to which a voltage is externally applied;
Forming an electrostatic latent image on the charged latent image carrier;
Supporting the developer contained in the developing container on a developer carrier;
Regulating the developer carried on the developer carrier by a developer layer thickness regulating member;
Transporting the developer carried on the developer carrier to a development area where the developer carrier and the electrostatic latent image carrier are opposed to each other;
Developing the electrostatic latent image formed on the latent image carrier;
A transfer step of transferring the developed image to a transfer material by a transfer unit and transferring the transferred image;
A fixing step of heating and fixing the transferred image transferred on the transfer body,
In an image forming method having at least,
An image forming apparatus using the developing device according to claim 9.

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