JP3697167B2 - Replenishment developer, developing method and image forming method - Google Patents

Description

【００６２】
なお、本発明で用いる測定装置である「ＦＰＩＡ−１０００」は、各粒子の円形度を算出後、平均円形度の算出に当たって、粒子を得られた円形度によって、円形度０．４０〜１．００を６１分割したクラスに分け、分割点の中心値と頻度を用いて平均円形度の算出を行う算出法を用いている。しかしながら、この算出法で算出される平均円形度の各値と、上述した各粒子の円形度を直接用いる算出式によって算出される平均円形度の各値との誤差は、非常に少なく、実質的には無視できる程度のものであり、本発明においては、算出時間の短縮化や算出演算式の簡略化の如きデータの取り扱い上の理由で、上述した各粒子の円形度を直接用いる算出式の概念を利用し、一部変更したこのような算出法を用いても良い。
【００６３】
測定手順としては、以下の通りである。
【００６４】
界面活性剤約０．１ｍｇを溶解している水１０ｍｌに、磁性トナー約５ｍｇを分散させて分散液を調製し、超音波（２０ｋＨｚ，５０Ｗ）を分散液に５分間照射し、分散液濃度を５０００〜２万個／μｌとして、前記装置により測定を行い、３μｍ以上の円相当径の粒子群の平均円形度及びモード円形度を求める。
【００６５】
本発明における平均円形度とは、トナーの凹凸の度合いの指標であり、磁性トナーが完全な球形の場合１．０００を示し、トナーの表面形状が複雑になるほど平均円形度は小さな値となる。
【００６６】
トナーに使用される結着樹脂としては、下記の結着樹脂の使用が可能である。
【００６７】
例えば、ポリスチレン、ポリ−ｐ−クロルスチレン、ポリビニルトルエンの如きスチレン及びその置換体の単重合体；スチレン−ｐ−クロルスチレン共重合体、スチレン−ビニルトルエン共重合体、スチレン−ビニルナフタリン共重合体、スチレン−アクリル酸エステル共重合体、スチレン−メタクリル酸エステル共重合体、スチレン−α−クロルメタクリル酸メチル共重合体、スチレン−アクリロニトリル共重合体、スチレン−ビニルメチルエーテル共重合体、スチレン−ビニルエチルエーテル共重合体、スチレン−ビニルメチルケトン共重合体、スチレン−ブタジエン共重合体、スチレン−イソプレン共重合体、スチレン−アクリロニトリル−インデン共重合体の如きスチレン系共重合体；ポリ塩化ビニル；フェノール樹脂；天然変性フェノール樹脂；天然樹脂変性マレイン酸樹脂；アクリル樹脂；メタクリル樹脂；ポリ酢酸ビニール；シリコーン樹脂；ポリエステル樹脂；ポリウレタン；ポリアミド樹脂；フラン樹脂；エポキシ樹脂；キシレン樹脂；ポリビニルブチラール；テルペン樹脂；クマロンインデン樹脂；石油系樹脂が使用できる。好ましい結着樹脂としては、スチレン系共重合体もしくはポリエステル樹脂が挙げられる。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。
【００６８】
スチレン系共重合体の重合性単量体として、スチレンモノマーとスチレンコモノマーが用いられるが、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のようなビニルエーテル類；の如きビニル単量体が単独もしくは組み合わせて用いられる。
【００６９】
本発明において、トナーの結着樹脂のＴＨＦ可溶分の数平均分子量は３，０００〜１００万（より好ましくは、６，０００〜２０万）がよい。
【００７０】
本発明において、トナーのＴＨＦ可溶分とは、以下の様に調製したものである。
【００７１】
予めトナーをソックスレー抽出器を用い、トルエン溶剤で２０時間抽出を行い、得られた抽出液をロータリーエバポレーターでトルエンを留去せしめた後、テトラヒドロフラン（ＴＨＦ）に可溶させる。そのようにして得たＴＨＦ可溶分を、ポア径が０．３μｍの耐溶剤性メンブランフィルターでろ過したサンプルを、ウォーターズ社製１５０Ｃを用い、カラム構成は昭和電工製Ａ−８０１，８０２，８０３，８０４，８０５，８０６，８０７を連結し標準ポリスチレン樹脂の検量線を用い、分子量分布を測定してＴＨＦ可溶分の数平均分子量を測定し得る。
【００７２】
スチレン系重合体またはスチレン系共重合体は架橋されていても良く、さらに架橋されている樹脂と架橋されていない樹脂との混合樹脂でも良い。
【００７３】
結着樹脂の架橋剤としては、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を用いてもよい。例えば、ジビニルベンゼン、ジビニルナフタレンのような芳香族ジビニル化合物；エチレングリコールジアクリレート、エチレングリコールジメタクリレート、１，３−ブタンジオールジメタクリレートのような二重結合を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、ジビニルスルホンの如きジビニル化合物；および３個以上のビニル基を有する化合物が挙げられる。これらは単独もしくは混合物として用いられる。
【００７４】
架橋剤の添加量としては、重合性単量体１００質量部に対して０．００１〜１０質量部が好ましい。
【００７５】
また、トナーは荷電制御剤を含有しても良い。
【００７６】
トナーを負帯電性に制御するものとして下記物質がある。例えば、有機金属化合物、キレート化合物が有効であり、さらにモノアゾ金属化合物、アセチルアセトン金属化合物、芳香族ハイドロキシカルボン酸、芳香族ダイカルボン酸系の金属化合物が好ましく用いられる。さらに、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れらの金属塩、それらの無水物、それらのエステル類、ビスフェノールの如きそれらのフェノール誘導体類；尿素誘導体；含金属サリチル酸系化合物；含金属ナフトエ酸化合物；ホウ素化合物；４級アンモニウム塩；カリックスアーレン；ケイ素化合物；スチレンーアクリル酸共重合体；スチレンーメタクリル酸共重合体；スチレン−アクリル−スルホン酸共重合体；及びノンメタルカルボン酸系化合物が挙げられる。
【００７７】
トナーを正荷電性に制御するものとして下記物質がある。例えば、ニグロシン及び脂肪酸金属塩等による変性物、グアニジン化合物、イミダゾール化合物、トリブチルベンジルアンモニウム−１−ヒドロキシ−４−ナフトスルフォン酸塩、テトラブチルアンモニウムテトラフルオロボレートなどの４級アンモニウム塩、及びこれらの類似体であるホスホニウム塩等のオニウム塩及びこれらのレーキ顔料、トリフェニルメタン染料及びこれらのレーキ顔料（レーキ化剤としては、りんタングステン酸、りんモリブデン酸、りんタングステンモリブデン酸、タンニン酸、ラウリン酸、没食子酸、フェリシアン化物、フェロシアン化物など）、高級脂肪酸の金属塩；ジブチルスズオキサイド、ジオクチルスズオキサイド、ジシクロヘキシルスズオキサイドなどのジオルガノスズオキサイド；ジブチルスズボレート、ジオクチルスズボレート、ジシクロヘキシルスズボレートなどのジオルガノスズボレート類；これらを単独で或いは２種類以上組合せて用いることができる。これらの中でも、ニグロシン系、４級アンモニウム塩の如き荷電制御剤が特に好ましく用いられる。
【００７８】
これらの荷電制御剤は、トナーの樹脂成分１００質量部に対して０．０１〜２０質量部、好ましくは０．１〜１０質量部、より好ましくは０．２〜４質量部使用するのが良い。
【００７９】
本発明に用いられるトナーの着色剤は、黒色着色剤としてカーボンブラック，磁性体、以下に示すイエロー／マゼンタ／シアン着色剤を用い黒色に調合されたものが利用される。
【００８０】
イエロー着色剤としては、縮合アゾ化合物、イソインドリノン化合物、アンスラキノン化合物、アゾ金属錯体、メチン化合物、アリルアミド化合物に代表される化合物が用いられる。具体的には、Ｃ．Ｉ．ピグメントイエロー１２、１３、１４、１５、１７、６２、７４、８３、９３、９４、９５、１０９、１１０、１１１、１２８、１２９、１４７、１６８又は１８０が好適に用いられる。さらにＣ．Ｉ．ソルベントイエロー９３、１６２等の染料を併用しても良い。
【００８１】
マゼンタ着色剤としては、縮合アゾ化合物、ジケトピロロピロール化合物、アンスラキノン、キナクリドン化合物、塩基染料レーキ化合物、ナフトール化合物、ベンズイミダゾロン化合物、チオインジゴ化合物、ペリレン化合物が用いられる。具体的には、Ｃ．Ｉ．ピグメントレッド２、３、５、６、７、２３、４８：２、４８：３、４８：４、５７：１、８１：１、１４４、１４６、１６６、１６９、１７７、１８４、１８５、２０２、２０６、２２０、２２１又は２５４が好適に用いられる。
【００８２】
シアン着色剤としては、銅フタロシアニン化合物及びその誘導体、アンスラキノン化合物、塩基染料レーキ化合物等が利用できる。具体的には、Ｃ．Ｉ．ピグメントブルー１、７、１５、１５：１、１５：２、１５：３、１５：４、６０、６２、６６が特に好適に利用できる。
【００８３】
これらの着色剤は、単独又は混合し更に固溶体の状態で用いることができ、色相角、彩度、明度、耐候性、ＯＨＰ透明性、トナー中への分散性の点から選択される。該着色剤の添加量は、樹脂１００質量部に対し１〜２０質量部添加して用いられる。
【００８４】
トナー粒子には、固体ワックスが１〜４０質量％、好ましくは２〜３０質量％含有されることが好適である。ワックスが１質量％未満であるとオフセット抑制効果が小さく、４０質量％を超えるとトナー表面にも偏在するようになり、キャリア汚染等が生じやすくなることで補給キャリア量を多くしないと、画像濃度変化が大きくなりやすいばかりでなく、キャリアの流動性が変化するために、現像剤の密度変化が大きくなり、キャリアの回収が不安定になってしまう。
【００８５】
好ましいワックスとして、ゲルパーミエーションクロマトグラフィ（ＧＰＣ）によって測定される分子量分布において、重量平均分子量（Ｍｗ）／数平均分子量（Ｍｎ）が１．４５以下であり、かつ溶解度パラメーターが８．４〜１０．５のワックスを用いることにより、トナーは流動性に優れ、光沢ムラのない均一な定着画像が得られ、さらに定着装置の加熱部材に対する汚染や保存性の低下が生じ難く、かつ定着性及び定着画像の光透過性に優れ、トナーを溶融させて透明性に優れたフルカラーＯＨＰを作成する際に、ワックスの一部または全部が適度に加熱部材を被覆し、トナーがオフセットすることなく、フルカラーＯＨＰが作成でき、かつ良好な低温定着性が発現できることに加えて、圧接部材の長寿命化を達成できる。
【００８６】
Ｍｗ/Ｍｎがさらに好ましくは１．３０以下であることが、トナーの良好な転写性及び感光体に接触して帯電するための接触帯電手段に対する汚染の防止の点で、より好ましい。
【００８７】
本発明においてワックスの分子量分布は、ダブルカラムを用いたＧＰＣにより次の条件で測定される。
【００８８】
（ＧＰＣ測定条件）
装置 ：ＧＰＣ−１５０Ｃ（ウォーターズ社製）
カラム：ＧＭＨ−ＨＴ３０ｃｍ２連（東ソー社製）
温度 ：１３５℃
溶媒 ：ｏ−ジクロロベンゼン（０．１％アイオノール添加）
流速 ：１．０ｍｌ／ｍｉｎ
試料 ：濃度０．１５％の試料を０．４ｍｌ注入
以上の条件で測定し、試料の分子量算出にあたっては単分散ポリウレタン標準試料により作成した分子量較正曲線を使用する。さらに、Ｍａｒｋ−Ｈｏｕｗｉｎｋ粘度式から導き出される換算式でポリエチレン換算することによって、重量平均分子量および数平均分子量を算出する。
【００８９】
本発明に用いられるワックスの融点は、４０〜１５０℃であることが好ましく、５０〜１２０℃が特に好ましい。ワックスの融点が４０℃より低い場合はトナーの耐ブロッキング性を弱め、多数枚の複写時でのスリーブを汚染しやすくなり、画像形成スピードを変えた際に現像剤のコートが不均一となり画像濃度ムラが生じやすい。ワックスの融点が１５０℃を超える場合は、粉砕法によるトナーの製法において結着樹脂との均一混合に過大のエネルギーが必要になり、重合法によるトナーの製法においても結着樹脂への均一化のために、粘度を高めることによる装置の大型化あるいは相溶する量に限界があるため、多量に含有されることが難しくなるなど好ましくない。
【００９０】
ワックスの融点は、ＡＳＴＭ Ｄ３４１８−８に準じて測定される吸熱曲線における主体極大ピーク（ｍａｉｎ ｐｅａｋ）値の温度とする。
【００９１】
ＡＳＴＭ Ｄ３４１８−８に準ずる測定には、例えばパーキンエルマー社製ＤＳＣ−７を用い行う。装置検出部の温度補正はインジウム亜鉛の融点を用い、熱量の補正についてはインジウムの融解熱を用いる。サンプルはアルミニウム製パンを用い対照用に空パンをセットし、昇温速度１０℃／ｍｉｎで温度２０〜２００℃の範囲で測定を行う。
【００９２】
本発明に用いられるワックスの１００℃における溶融粘度は、１〜５０ｍＰａ・ｓであることが好ましく、更に３〜３０ｍＰａ・ｓを有するワックス化合物が特に好ましい。
【００９３】
ワックスの溶融粘度が１ｍＰａ・ｓより低い場合には、磁性キャリアを用いトナーを現像する際にトナーと磁性キャリア間のズリ力によりダメージを生じやすく、外添剤の埋没やトナー破砕が生じやすく、種々の画像形成スピードに対して、常に安定量の現像剤をコートするのが難しくなる傾向がある。ワックスの溶融粘度が５０ｍＰａ・ｓを超える場合には、重合方法を用いてトナーを製造する際、分散質の粘度が高すぎ、均一な粒径を有する微小粒径のトナーを得ることが容易でなく、粒度分布の広いトナーとなりやすい。
【００９４】
ワックスの溶融粘度の測定は、ＨＡＡＫＥ社製ＶＴ−５００にてコーンプレート型ローター（ＰＫ−１）を用い測定する方法が挙げられる。
【００９５】
さらに、本発明に用いられるワックスは、ＧＰＣにより測定される分子量分布が、２つ以上のピーク又は１つ以上のピークと１つ以上のショルダーとを有し、かつ分子量分布において、重量平均分子量（Ｍｗ）が２００〜２０００、数平均分子量（Ｍｎ）が１５０〜２０００であることが好ましい。上述の分子量分布は、単一のワックス又は複数のワックスのいずれで達成しても良く、結果として結晶性が阻害でき、透明性が一層向上することを見い出した。２種以上のワックスをブレンドする方法としては特に制約を受けるものではないが、例えばブレンドするワックスの融点以上においてメディア式分散機（ボールミル、サンドミル、アトライター、アペックスミル、コボールミル、ハンディミル）を用いて溶融ブレンドすることや、ブレンドするワックスを重合性単量体中へ溶解させ、メディア式分散機にてブレンドすることも可能である。このとき添加物として、顔料、荷電制御剤、重合開始剤を使用しても構わない。
【００９６】
ワックスの重量平均分子量（Ｍｗ）は２００〜２０００、数平均分子量（Ｍｎ）は１５０〜２０００であることが好ましい。より好ましくはＭｗが２００〜１５００、さらに好ましくは３００〜１０００、Ｍｎは２００〜１５００、さらに好ましくは２５０〜１０００であることが良い。ワックスのＭｗが２００未満又はＭｎが１５０未満の場合には、トナーの耐ブロッキング性が低下することがある。ワックスのＭｗが２０００超又はＭｎが２０００超の場合には、ワックス自体の結晶性が発現し、透明性が低下することがある。
【００９７】
本発明に用いることが可能なワックスとしては、例えばパラフィン系ワックス、ポリオレフィン系ワックス、これらの変性物（例えば、酸化物やグラフト処理物）、高級脂肪酸、およびその金属塩、アミドワックス、及びエステル系ワックスなどが挙げられる。その中でも、より高品位なフルカラーＯＨＰ画像が得られる点でエステルワックスが特に好ましい。
【００９８】
次に本発明に用いられる平均円形度０．９６０以上のトナーを製造するための好ましい方法について説明する。本発明に用いられるトナーは、粉砕トナー製法及び重合トナー製法を用いて製造することが可能であるが、好ましくは重合トナー製法が用いられる。
【００９９】
重合トナーの製造法は、特公昭５６−１３９４５号公報等に記載のディスク又は多流体ノズルを用い溶融混合物を空気中に霧化し球状トナーを得る方法や、特公昭３６−１０２３１号公報、特開昭５９−５３８５６号公報、特開昭５９−６１８４２号公報に述べられている懸濁重合法を用いて直接トナーを生成する方法や、単量体には可溶で得られる重合体が不溶な水系有機溶剤を用い直接トナーを生成する分散重合法又は水溶性極性重合開始剤存在下で直接重合しトナーを生成するソープフリー重合法に代表される乳化重合法や、予め一次極性乳化重合粒子を作った後、反対電荷を有する極性粒子を加え会合させるヘテロ凝集法等を用いトナーを製造することが可能である。
【０１００】
この中でも、重合性単量体、着色剤及びワックスを少なくとも含む単量体組成物を直接重合してトナー粒子を生成する方法で得られる重合トナー粒子が好ましい。
【０１０１】
分散重合法においては、得られるトナーは極めてシャープな粒度分布を示すが、使用する材料の選択が狭いことや有機溶剤の利用が廃溶剤の処理や溶剤の引火性に関する観点から製造装置が複雑で煩雑化しやすい。従って、重合性単量体、着色剤及びワックスを少なくとも含む単量体組成物を水系媒体中で直接重合してトナー粒子を生成する方法が、より好ましい。しかしながら、ソープフリー重合に代表される乳化重合法は、トナーの粒度分布が比較的揃うため有効であるが、使用した乳化剤や開始剤末端がトナー粒子表面に存在した時に環境特性を悪化させやすい。
【０１０２】
従って、本発明においては、比較的容易に粒度分布がシャープな微粒子トナーが得られる常圧下での、または、加圧下での懸濁重合法が特に好ましい。一旦得られた重合粒子に更に単量体を吸着せしめた後、重合開始剤を用い重合せしめる所謂シード重合法も本発明に好適に利用することができる。
【０１０３】
本発明に用いられるトナーの好ましい形態としては、透過電子顕微鏡（ＴＥＭ）を用いたトナーの断層面測定法で、ワックスが外殻樹脂層で内包化されたものである。定着性の観点から多量のワックスをトナーに含有せしめる必要性から、ワックスを外殻樹脂層で内包化せしめることがトナーの保存性や流動性の点で好ましい。内包化せしめない場合のトナーは、キャリア汚染が起きやすく、キャリアの回収性が不安定になるので好ましくない。
【０１０４】
ワックスを内包化せしめる具体的な方法としては、水系媒体中での材料の極性を主要単量体よりワックスの方を小さく設定し、更に少量の極性の大きな樹脂又は単量体を添加せしめることでワックスを外殻樹脂で被覆した所謂コア−シェル構造を有するトナーを得ることができる。トナーの粒度分布制御や粒径の制御は、難水溶性の無機塩や保護コロイド作用をする分散剤の種類や添加量を変える方法や機械的装置条件、例えばローターの周速・パス回数・撹拌羽根形状等の撹拌条件や容器形状又は、水溶液中での固形分濃度等を制御することにより所定の本発明のトナーを得ることができる。
【０１０５】
本発明においてトナーの断層面を測定する具体的な方法としては、常温硬化性のエポキシ樹脂中にトナーを十分分散させた後、温度４０℃の雰囲気中で２日間硬化させ得られた硬化物を、四三酸化ルテニウム、必要により四三酸化オスミウムを併用し染色を施した後、ダイヤモンド歯を備えたミクロトームを用い薄片状のサンプルを切り出し透過電子顕微鏡（ＴＥＭ）を用いトナーの断層形態を測定する。本発明においては、用いるワックスと外殻を構成する樹脂との若干の結晶化度の違いを利用して材料間のコントラストを付けるため、四三酸化ルテニウム染色法を用いることが好ましい。
【０１０６】
本発明のトナー製造方法に直接重合方法を用いる場合においては、以下の如き製造方法によって具体的にトナーを製造することが可能である。単量体中にワックス、着色剤、荷電制御剤、重合開始剤その他の添加剤を加え、ホモジナイザー、超音波分散機等によって均一に溶解又は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通常の撹拌機またはホモミキサー、ホモジナイザーの如き撹拌機により分散せしめる。好ましくは単量体組成物の液滴が所望のトナー粒子のサイズを有するように撹拌速度・時間を調整し、造粒する。その後は分散安定剤の作用により、粒子状態が維持され、且つ粒子の沈殿が防止される程度の撹拌を行えば良い。重合温度は４０℃以上、一般的には５０〜９０℃の温度に設定して重合を行う。また、重合反応後半に昇温しても良く、更に、トナー定着時の臭いの原因等となる未反応の重合性単量体や副生成物等を除去するために反応後半、又は反応終了後に一部水系媒体を留去しても良い。反応終了後、生成したトナー粒子を洗浄・濾過により回収し、乾燥する。懸濁重合法においては、通常単量体組成物１００質量部に対して水３００〜３０００質量部を分散媒として使用するのが好ましい。
【０１０７】
重合法を用い直接トナーを得る際の重合性単量体としては、スチレン、ｏ（ｍ−，ｐ−）−メチルスチレン、ｍ（ｐ−）−エチルスチレンの如きスチレン系単量体；（メタ）アクリル酸メチル、（メタ）アクリル酸エチル、（メタ）アクリル酸プロピル、（メタ）アクリル酸ブチル、（メタ）アクリル酸オクチル、（メタ）アクリル酸ドデシル、（メタ）アクリル酸ステアリル、（メタ）アクリル酸ベヘニル、（メタ）アクリル酸２−エチルヘキシル、（メタ）アクリル酸ジメチルアミノエチル、（メタ）アクリル酸ジエチルアミノエチルの如き（メタ）アクリル酸エステル系単量体；ブタジエン、イソプレン、シクロヘキセン、（メタ）アクリロニトリル、アクリル酸アミドの如きジエン系単量体が好ましく用いられる。
【０１０８】
トナーの重合法に用いられる極性樹脂としては、メタクリル酸ジメチルアミノエチル、メタクリル酸ジエチルアミノエチルの如き含窒素単量体の重合体もしくは含窒素単量体とスチレン−不飽和カルボン酸エステルとの共重合体；アクリロニトリルの如きニトリル系単量体；塩化ビニルの如き含ハロゲン系単量体；アクリル酸、メタクリル酸の如き不飽和カルボン酸；不飽和二塩基酸；不飽和二塩基酸無水物；ニトロ系単量体の重合体もしくはそれとスチレン系単量体との共重合体；ポリエステル；エポキシ樹脂；が挙げられる。より好ましいものとして、スチレンと（メタ）アクリル酸の共重合体、マイレン酸共重合体、飽和ポリエステル樹脂、エポキシ樹脂が挙げられる。
【０１０９】
重合開始剤としては、例えば、２，２’−アゾビス−（２，４−ジメチルバレロニトリル）、２，２’−アゾビスイソブチロニトリル、１，１’−アゾビス（シクロヘキサン−１−カルボニトリル）、２，２’−アゾビス−４−メトキシ−２，４−ジメチルバレロニトリル、アゾビスイソブチロニトリルの如きアゾ系又はジアゾ系重合開始剤；ベンゾイルペルオキシド、メチルエチルケトンペルオキシド、ジイソプロピルペルオキシカーボネート、クメンヒドロペルオキシド、ｔ−ブチルヒドロペルオキシド、ジ−ｔ−ブチルペルオキシド、ジクシルペルオキシド、２，４−ジクロロベンゾイルペルオキシド、ラウロイルペルオキシド、２，２−ビス（４，４−ｔ−ブチルペルオキシシクロヘキシル）プロパン、トリス−（ｔ−ブチルペルオキシ）トリアジンの如き過酸化物系開始剤；過酸化物を側鎖に有する高分子開始剤；過硫酸カリウム及び過硫酸アンモニウムの如き過硫酸塩；過酸化水素などが使用される。これらは単独で又は２種以上を併用して用いることができる。
【０１１０】
重合開始剤は、重合性単量体１００質量部に対して０．５〜２０質量部の添加量が好ましい。
【０１１１】
分子量をコントロールするために、公知の架橋剤や連鎖移動剤を添加しても良く、好ましい添加量としては重合性単量体１００質量部に対して０．００１〜１５質量部である。
【０１１２】
乳化重合、分散重合、懸濁重合、シード重合、ヘテロ凝集法を用いる重合法によって、重合法トナーを製造する際に用いられる分散媒には、適当な無機化合物又は有機化合物の安定化剤を使用することが好ましい。無機化合物の安定化剤としては、例えば、リン酸三カルシウム、リン酸マグネシウム、リン酸アルミニウム、リン酸亜鉛、炭酸カルシウム、炭酸マグネシウム、水酸化カルシウム、水酸化マグネシウム、水酸化アルミニウム、メタケイ酸カルシウム、硫酸カルシウム、硫酸バリウム、ベントナイト、シリカ、アルミナが挙げられる。有機化合物の安定化剤としては、ポリビニルアルコール、ゼラチン、メチルセルロース、メチルヒドロキシプロピルセルロース、エチルセルロース、カルボキシメチルセルロースのナトリウム塩、ポリアクリル酸及びその塩、デンプン、ポリアクリルアミド、ポリエチレンオキシド、ポリ（ハイドロオキシステアリン酸−ｇ−メタクリル酸メチル−ｅｕ−メタクリル酸）共重合体やノニオン系或いはイオン系界面活性剤が挙げられる。
【０１１３】
乳化重合法及びヘテロ凝集法を用いる場合には、アニオン系界面活性剤、カチオン系界面活性剤、両性イオン界面活性剤及びノニオン系界面活性剤が使用される。これらの安定剤は重合性単量体１００質量部に対して０．２〜３０質量部を使用することが好ましい。
【０１１４】
これら安定化剤の中で、無機化合物を用いる場合、市販のものをそのまま用いても良いが、細かい粒子を得るために、分散媒中にて該無機化合物を生成させても良い。
【０１１５】
これら安定化剤の微細な分散のために、重合性単量体１００質量部に対して０．００１〜０．１質量部の界面活性剤を使用してもよい。この界面活性剤は上記分散安定化剤の安定化作用を促進するためのものである。その具体例としては、ドデシルベンゼン硫酸ナトリウム、テトラデシル硫酸ナトリウム、ペンタデシル硫酸ナトリウム、オクチル硫酸ナトリウム、オレイン酸ナトリウム、ラウリル酸ナトリウム、ステアリン酸カリウム、オレイン酸カルシウム等が挙げられる。
【０１１６】
本発明において重合法トナーに用いられる着色剤としては、着色剤の持つ重合阻害性や水相移行性に注意を払う必要があり、前記着色剤を好ましくは表面改質、たとえば重合阻害のない疎水化処理を施したほうが良い。特に染料系やカーボンブラックは、重合阻害性を有しているものが多いので使用の際に注意を要する。染料系を表面処理する好ましい方法としては、これら染料の存在下に重合性単量体をあらかじめ重合せしめる方法が挙げられ、得られた着色重合体を単量体系に添加する。また、カーボンブラックについては、上記染料と同様の処理のほか、ポリオルガノシロキサンの如きカーボンブラックの表面官能基と反応する物質で処理を行っても良い。
【０１１７】
本発明に用いられるワックスの融点は、前述したように４０〜１５０℃であることが好ましく、より好ましくは５０〜１２０℃が特に好ましいが、さらにトナーのワックスの融点は結着樹脂のガラス転移温度よりも高く、その温度差は、好ましくは１００℃以下、より好ましくは７５℃以下、さらに好ましくは５０℃以下であることが良い。
【０１１８】
この温度差が１００℃を超える場合には、低温定着性が低下してしまう傾向がある。さらにこの温度差が近すぎる場合には、トナーの保存性と耐高温オフセット性との両立できる温度領域が狭くなることから、好ましくは２℃以上であることが良い。このことから結着樹脂のガラス転移温度は、好ましくは４０〜９０℃、より好ましくは５０〜８５℃であることが良い。
【０１１９】
結着樹脂のガラス転移温度が４０℃未満の場合には、トナーの保存性が低下し、かつ流動性が悪化し、良好な画像が得られない傾向がある。結着樹脂のガラス転移温度が９０℃を超える場合には、低温定着性が劣るのに加え、フルカラートランスペアレンシーの透過性が悪化してしまう。とりわけ、ハーフトーン部がくすみ、彩度のない投影画像になりやすい。
【０１２０】
結着樹脂のガラス転移温度（Ｔｇ）は、ＡＳＴＭ Ｄ３４１８−８に準ずる測定によって行う。例えばパーキンエルマー社製ＤＳＣ−７を用いて行う。装置検出部の温度補正はインジウムと亜鉛の融点を用い、熱量の補正についてはインジウムの融解熱を用いる。サンプルはアルミニウム製パンを用い対照用に空パンをセットし、昇温速度１０℃／ｍｉｎで温度２０〜２００℃の範囲で測定を行う。
【０１２１】
次に、トナー粒子に外添される外添剤について説明する。
【０１２２】
本発明に使用されるトナーにはシリカ、アルミナ、酸化チタンの如き無機微粒子；ポリテトラフロロエチレン、ポリビニリデンフロライド、ポリメチルメタクリレート、ポリスチレン、シリコーンの如き有機微粒子の微粉末が外添されていることが好適である。トナー粒子に上述した微粉末を外添することによって、トナーとキャリア、あるいはトナー粒子相互の間に微粉末が存在することになり、現像剤の流動性が向上され、さらに現像剤の寿命も向上する。上述した微粉末の平均粒径は０．２μｍ以下であることが好ましい。個数平均粒径が０．２μｍを超えると流動性向上の効果が少なくなり、現像時、転写時の不良等により画質を低下させてしまう場合がある。これら微粉末の個数平均粒径の測定は後述する。
【０１２３】
これらの微粉末の表面積としては、ＢＥＴ法による窒素吸着によった比表面積が３０ｍ²／ｇ以上、特に５〜４００ｍ²／ｇの範囲のものが良好である。微粉末の添加量は、トナー粒子１００質量部に対して０．１〜２０質量部で使用することが好適である。
【０１２４】
本発明において特に好ましく用いられる負帯電性トナーにおいては、少なくとも１種類は疎水化処理されたシリカを用いることが、帯電性の点から好ましい。つまり、シリカあるいは酸化チタンの方がアルミナ等の流動化剤より負帯電性が高いため、トナー粒子との密着性が高く、遊離した外添剤が少なくなる。そのため、静電潜像担持体上のフィルミングと、一部遊離した外添剤がキャリアへ移行してしまう傾向にある。その場合でも、本発明の重合法キャリアは、その表面の凹凸等が均一な表面形状故に流動化剤の付着を抑制することができる。
【０１２５】
また、該無機微粒子は高湿下での帯電性を維持するために、疎水化処理されることが好ましい。その疎水化処理の例を下記に示す。
【０１２６】
疎水化処理剤の一つとして、シランカップリング剤が挙げられ、その量は、無機微粒子１００質量部に対して、１〜４０質量部、好ましくは２〜３５質量部を用いるのが良い。１〜４０質量部であると耐湿性が向上し凝集体が発生しにくい。
【０１２７】
本発明に用いられるシランカップリング剤としては、下記一般式（５）で示されるものが挙げられる。
【０１２８】
ＲｍＳｉＹｎ 式（５）
〔式中、Ｒはアルコキシ基又は塩素原子を示し、ｍは１〜３の整数であり、Ｙは、炭化水素基（例えば、アルキル基、ビニル基、グリシドキシ基、メタクリル基が挙げられる）を示し、ｎは３〜１の整数である。〕
【０１２９】
具体的には例えば、ジメチルジクロルシラン、トリメチルクロルシラン、アリルジメチルクロルシラン、ヘキサメチルジシラザン、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、ビニルトリエトキシシラン、γ−メタクリルオキシプロピルトリメトキシシラン、ビニルトリアセトキシシラン、ジビニルクロルシラン、ジメチルビニルコロルシラン等を挙げることができる。
【０１３０】
上記無機微粒子のシランカップリング剤処理は、無機微粒子を撹拌によりクラウド状としたものに気化したシランカップリング剤を反応させる乾式処理、又は、無機微粒子を溶媒中に分散させシランカップリング剤を滴下反応させる湿式法の如き一般に知られた方法で処理することができる。上述の疎水化処理は適宜併用可能である。
【０１３１】
また、別の疎水化処理剤の一つとしてシリコーンオイルが挙げられる。
【０１３２】
好ましいシリコーンオイルとしては、２５℃における粘度が５〜２０００ｍｍ²／ｓのものが好ましく用いられる。分子量が低すぎて低粘度のシリコーンオイルは加熱処理により、揮発分が発生することがあり好ましくなく、一方、分子量が高すぎて高粘度のシリコーンオイルは表面処理操作がしにくくなる。シリコーンオイルとしては、メチルシリコーンオイル、ジメチルシリコーンオイル、フェニルメチルシリコーンオイル、クロルフェニルメチルシリコーンオイル、アルキル変性シリコーンオイル、脂肪酸変性シリコーンオイル、ポリオキシアルキル変性シリコーンオイルが好ましい。
【０１３３】
上述のシリコーンオイルは、トナーの帯電性を高めるため、トナー粒子と同極性の負帯電性のものを用いることが好ましい。
【０１３４】
無機微粒子をシリコーンオイル処理する方法としては、公知の技術が用いられる。例えば無機微粒子とシリコーンオイルとをヘンシェルミキサーの如き混合機を用いて直接混合しても良いし、無機微粒子へシリコーンオイルを噴霧する方法によっても良い。あるいは適当な溶剤にシリコーンオイルを溶解あるいは分散せしめた後、無機微粒子と混合し、その後、溶剤を除去して作製しても良い。
【０１３５】
シリコーンオイルは、処理を施す無機微粒子１００質量部に対して、１．５〜６０質量部、好ましくは３．５〜４０質量部用いるのが良い。１．５〜６０質量部であると、シリコーンオイルによる表面処理が均一に行え、好適にフィルミング及び中抜けを防止でき、高湿下での吸湿によるトナーの帯電性の低下を防止し、耐久における画像濃度の低下を防止し得る。
【０１３６】
各種トナー特性付与を目的とした添加剤は、トナー中に、あるいはトナーに添加した時の耐久性の点から、平均粒径が０．００５〜０．２μｍであることが好ましい。この添加剤の平均粒径とは、電子顕微鏡におけるトナー粒子の表面観察により求めたその個数平均粒径を意味する。これら特性付与を目的とした添加剤としては、例えば以下のようなものが用いられる。
【０１３７】
上述した無機微粒子、有機微粒子以外に他の流動性付与剤として、例えばカーボンブラック及びフッ化カーボンが挙げられる。これらはそれぞれ、疎水化処理を行ったものが、より好ましい。
【０１３８】
研磨剤としては、例えば、チタン酸ストロンチウム、酸化セリウム、酸化アルミニウム、酸化マグネシウム及び酸化クロムなどの如き金属酸化物；窒化ケイ素の如き窒化物；炭化ケイ素などの炭化物；及び硫酸カルシウム、硫酸バリウム及び炭酸カルシウムの如き金属塩が挙げられる。
【０１３９】
滑剤としては、例えばフッ化ビニリデン及びポリテトラフルオロエチレンの如きフッ素系樹脂粉末；及びステアリン酸亜鉛及びステアリン酸カルシウムの如き脂肪酸金属塩が挙げられる。
【０１４０】
荷電制御性粒子あるいは導電性付与粒子としては、例えば酸化錫、酸化チタン、酸化亜鉛、酸化ケイ素及び酸化アルミニウムの如き金属酸化物；及びカーボンブラックが挙げられる。
【０１４１】
これら添加剤は、トナー粒子１００質量部に対し、好ましくは０．１〜１０質量部、より好ましく０．１〜５質量部が用いられる。これら添加剤は、単独で用いても、また複数併用しても良い。
【０１４２】
本発明に用いる現像剤は、上述した磁性キャリアとトナーとを混合してスタート現像剤として用いる。
【０１４３】
トナーと磁性キャリアとを混合してスタート用現像剤を調製する場合、その混合比率は現像剤中のトナー濃度として、２〜１５質量％、好ましくは４〜１３質量％にすると良好な結果が得られる。トナー濃度が２質量％未満の場合には、画像濃度が低くなりやすく、１５質量％を超える場合にはカブリや機内飛散を生じやすく、現像剤の耐用寿命も低下しやすいことから好ましくない。
【０１４４】
次に、本発明の上記補給用現像剤を用いる現像装置を備えた画像形成装置について説明する。図１は、ロータリー回転方式の現像装置を搭載した電子写真方式のフルカラー画像形成装置の概略構成図である。
【０１４５】
まず、静電潜像担持体１は、帯電装置１５によりその表面を負極性に一様に帯電される。次に、露光装置１４により、一色目、例えばイエロー画像に対応する像露光がなされ、静電潜像担持体１の表面にはイエロー画像に対応する静電潜像が形成される。
【０１４６】
現像装置１３は、回転移動式の構成であり、前記イエロー画像に対応する静電潜像の先端が現像位置に到達する以前に、イエロー現像器が静電潜像担持体１に対向し、その後磁気ブラシが静電潜像を摺擦して、前記静電潜像担持体上にイエロートナー像を形成する。
【０１４７】
上記の現像に用いられる現像装置には、例えば、現像器の内部は、現像スリーブ、供給ロール、マグネットロール、規制部材、スクレーパ等が設けられている。図２は、図１の現像器２、３、４および５の概略構成図である。図２によって現像機内の現像剤が現像されるまでの搬送されていく流れを説明する。
【０１４８】
現像スリーブ６は、固定したマグネットを内包し、静電潜像担持体１の周面との間に所定の現像間隔を保ち、駆動回転される。なお、現像スリーブ６と静電潜像担持体１とは接触している場合もある。規制部材７は剛性かつ磁性を有し、現像スリーブ６に対し現像剤が介在しない状態で所定の荷重をもって圧接されるものや、現像スリーブ６との間に所定の間隔を保って配されるもの等、種々のものがある。一対の１０、１１は、スクリュー構造を持ち、互いに逆方向に現像剤を搬送循環させて、トナーとキャリアを十分撹拌混合した上、現像剤として現像スリーブ６に送る作用をするものである。マグネットロール８は、例えば、Ｎ極およびＳ極を交互に等間隔に配置した等磁力の４極の磁石から構成されるもの、或いは、スクレーパに接する部分において反発磁界を形成し、現像剤の剥離を容易にするために、１極欠落させて５極とし、前記現像スリーブ６内で固定した状態で内包させたものであってもよい。
【０１４９】
上記二本の現像剤撹拌搬送部材１０、１１は、互いに相反する方向に回転する撹拌部材を兼ねる部材であって、撹拌スクリューの推力によってトナー収容装置９より補給される補給用トナーを搬送すると共に、トナーと磁性キャリアとの混合作用によって、摩擦帯電がなされた均質な二成分の現像剤とされ、現像スリーブ６の周面上にその現像剤を層状に付着する。現像スリーブ６の表面の現像剤は、マグネットロール８の磁極に対向して設けた非磁性材料と磁性材からなる二重構造の規制部材７により、均一な層を形成する。均一に形成された現像剤層は、現像領域において、静電潜像担持体１の周面上の潜像を現像し、トナー像を形成する。
【０１５０】
図１において、用紙または透明シート等の転写材１２は、給紙トレイ２６または２７から、送り出しロール２８または２９により搬送され、一度レジストレーションロール２５で先端を塞き止められた後、所定のタイミングで転写ドラム２４へと送り出される。送り出された転写材１２は、吸着装置３２と対向ロール３０により転写ドラム２４へ静電的に保持され、転写ドラム２４と静電潜像担持体１が対向する転写領域へ搬送される。そこで前記転写材は、静電潜像担持体１上のイエロートナー像と密着し、転写装置３１の作用でイエロートナー像が転写材１２上に転写され、前記転写ドラム２４は、転写材１２を保持したまま次の工程に備える。
【０１５１】
イエロートナーの転写を終えた静電潜像担持体１は、その後、必要に応じてクリーニング前処理が施された後、除電コロトロンで除電され、クリーニング装置１８により表面に残ったイエロートナーが掻き取られ、さらに除電装置１６で表面に残った電荷が除電される。
【０１５２】
次に、二色目、例えば、マゼンタの画像形成工程のために、前記静電潜像担持体１は、帯電器１５によりその表面を負極性に一様に帯電され、レーザー露光器１４により、マゼンタ画像に対応する像露光がなされ、静電潜像担持体１の表面にはマゼンタ画像に対応する静電潜像が形成される。また、現像装置１３は、イエロートナー層の形成を終了した後で、マゼンタの現像器が前記静電潜像担持体１に対向するように切り換えられており、前記マゼンタ画像に対応する静電潜像は、マゼンタ用の磁気ブラシで現像される。そして、前記転写ドラム上に保持されていた転写材が、再び転写領域へと搬送され、転写装置３１の作用で、今度はイエロートナーの上にマゼンタトナーが多重転写される。
【０１５３】
マゼンタトナーの転写を終えた静電潜像担持体１は、その後、イエロー画像形成工程と同様にして、表面の残留トナーのクリーニングと残留電荷の除電が行われ、一方で、マゼンタトナーの転写を終えた転写材は、転写ドラム２４に保持されたまま、次の工程に備える。
【０１５４】
その後、マゼンタ画像形成工程と同様にして、三色目、例えばシアンの画像形成工程が行われ、最後に四色目、例えばブラックの画像形成工程が行われる。最後のブラックの画像形成工程では、転写材の搬送が前記三色目までの工程と異なる。すなわち、四色目の転写を終えた転写材は、剥離除電器１９および搬送ガイド部材２０の先端の図示していない剥離フィンガーにより、転写ドラム２４から分離され、定着器２１で多重トナー像が転写材に転写された後、画像形成装置の外に搬出される。
【０１５５】
また、転写材の分離を終えた転写ドラム２４は、その表面を除電装置２２、３３で除電した後、クリーニング装置２３で表面クリーニングが行われ、次の転写材１２の供給を待つことになる。
【０１５６】
上記のような複写動作が繰り返されると、図２の現像器内の現像槽１７内に収納されている現像剤中のトナーは徐々に消費され、キャリアに対するトナーの比率、すなわちトナー濃度が低下していく。このトナー濃度の変化は、現像槽１７に設けられた図示しないトナー濃度センサによりトナー濃度が現像に必要な適性範囲内に常に入るようにフィードバック制御される。上記制御によりトナー補給部（トナー収容装置９）の補給口から、現像器内の現像槽１７に供給される。
【０１５７】
一方、現像槽１７内の現像剤中のキャリアは、現像により消費されることはなく、現像槽１７内でのトナーと一緒に撹拌されたり、マグネットロールの磁力、および静電潜像担持体１との接触等の影響により、徐々に表面等が汚染されて、劣化していく。このようにキャリアが劣化していくと、トナーに所定の帯電量を付与し得なくなり、画質の低下を生じることになる。そこで、上記の現像器内の消費されない劣化したキャリアを新しいキャリアと置換する必要がある。図１においては、新しいキャリアを現像装置内に補給する手段として、現像により消費されたトナーを補給するためのトナーカートリッジ（トナー収容装置９）の中に補給用のトナーと上記所定の量のキャリアを混合した現像剤を入れ、トナー収容装置９の補給口から、各々の現像器２、３、４、５に補給する。過剰になった現像剤は、下記のように現像器側現像剤排出口より排出される。
【０１５８】
そこで、図１に示した回転移動する現像装置１３内の回転移動を利用した現像剤の入れ替えについて図３及び４によって説明する。回転移動方式を採用した現像装置１３によりフルカラー画像形成装置において、現像器２、３、４、５は、現像装置１３の内部で回転移動し、現像時、静電潜像担持体１に対向する位置に回転移動して現像を行い、非現像時は静電潜像担持体１に対向していない位置に回転移動する。
【０１５９】
現像器２が静電潜像担持体１に対向し、現像動作を行っている位置で、現像器２に設けられた現像器側現像剤排出口３４から溢出した現像剤は、回転動作により連通管３６内を移動し、回転式現像器切替装置の回転中心軸に設けられた現像剤回収口３５から排出される。
【０１６０】
本発明の磁性キャリアを使用する現像方法としては、具体的には、現像剤担持体に交流電圧を印加して、現像領域に交番電界を形成しつつ、磁気ブラシが感光ドラム１に接触している状態で現像を行うことが好ましい。現像剤担持体（現像スリーブ）６と感光ドラム１の距離（Ｓ−Ｄ間距離）は、１００〜１０００μｍであることがキャリア付着防止及びドット再現性の向上において良好である。１００μｍより狭いと現像剤の供給が不十分になりやすく、画像濃度が低くなり、１０００μｍを超えると磁極Ｓ₁からの磁力線が広がり磁気ブラシの密度が低くなり、ドット再現性に劣ったり、磁性コートキャリアを拘束する力が弱まりキャリア付着が生じやすくなる。
【０１６１】
交番電界のピーク間の電圧は３００〜３０００Ｖが好ましく、周波数は５００〜１００００Ｈｚ、好ましくは１０００〜７０００Ｈｚであり、それぞれプロセスにより適宜選択して用いることができる。この場合、交番電界を形成するための交流バイアスの波形としては三角波、矩形波、正弦波、あるいはＤｕｔｙ比を変えた波形が挙げられる。ときにトナー像の形成速度の変化に対応するためには、非連続の交流バイアス電圧を有する現像バイアス電圧（断続的な交番重畳電圧）を現像剤担持体に印加して現像を行うことが好ましい。印加電圧が３００Ｖより低いと十分な画像濃度が得られにくく、また非画像部のカブリトナーを良好に回収することができない場合がある。また、３０００Ｖを超える場合には磁気ブラシを介して、潜像を乱してしまい、画質低下を招く場合がある。
【０１６２】
良好に帯電したトナーを有する二成分系現像剤を使用することで、カブリ取り電圧（Ｖｂａｃｋ）を低くすることができ、感光体の一次帯電を低めることができるために感光体寿命を長寿命化できる。Ｖｂａｃｋは、現像システムにもよるが２００Ｖ以下、より好ましくは１５０Ｖ以下が良い。コントラスト電位としては、十分画像濃度が出るように１００〜４００Ｖが好ましく用いられる。
【０１６３】
また、周波数が５００Ｈｚより低いと、プロセススピードにも関係するが、静電潜像担持体に接触したトナーが現像スリーブに戻される際に、十分な振動が与えられずカブリが生じやすくなる。１００００Ｈｚを超えると、電界に対してトナーが追随できず画質低下を招きやすい。
【０１６４】
本発明の現像方法で重要なことは、十分な画像濃度を出し、ドット再現性に優れ、かつ磁性キャリア付着のない現像を行うために、現像スリーブ１１上の磁気ブラシの感光ドラム１との接触幅（現像当接部）を好ましくは３〜８ｍｍにすることである。現像当接部が３ｍｍより狭いと十分な画像濃度とドット再現性を良好に満足することが困難であり、８ｍｍより広いと現像剤のパッキングが起き機械の動作を止めてしまったり、また磁性キャリア付着を十分に抑えることが困難になる。現像当接部の調整方法としては、規制ブレード７と現像スリーブ６との距離を調整したり、現像スリーブ６と感光ドラム１との距離（Ｓ−Ｄ間距離）を調整することで当接幅を適宜調整する方法がある。
【０１６５】
感光体の構成としては、通常、画像形成装置に用いられる感光体と同じで良く、例えば、アルミニウム、ＳＵＳ等の導電性基体の上に、順に導電層、下引き層、電荷発生層、電荷輸送層、必要に応じて電荷注入層を設ける構成の感光体が挙げられる。
【０１６６】
導電層、下引き層、電荷発生層、電荷輸送層は、通常、感光体に用いられるもので良い。
【０１６７】
感光体の最表面層として、例えば電荷注入層あるいは保護層を用いてもよい。
【０１６８】
さらに初期の高画質化と併せて、本発明の補給用キャリアを用いることで現像装置内での現像剤にかかるシェアが小さく、多数枚の複写においてもキャリアへのトナーあるいは外添剤等のスペントが抑制され、少量の補給キャリアでも画質低下の少ない本発明の効果が十分に発揮できる。
【０１６９】
図面を参照しながらさらに本発明の画像形成方法について説明する。
【０１７０】
図５において、マグネットローラ１１２の有する磁力によって搬送スリーブ１２２の表面に磁性粒子１２３よりなる帯電用磁気ブラシを形成し、この磁気ブラシを電子写真感光体（以下、「感光体」という）１０１の表面に接触させ、感光体１０１を帯電する。搬送スリーブ１１１には、図示されないバイアス印加手段により帯電バイアスが印加されている。帯電された感光体１０１に、図示されない露光装置によりレーザ光１２４を照射することにより、デジタルな静電潜像を形成する。感光体１０１上に形成された静電潜像は、マグネットローラ１１２を内包し、図示されないバイアス印加装置によって現像バイアスを印加されている現像スリーブ１１１に担持された現像剤１１９中のトナー１１９ａによって、現像される。
【０１７１】
現像装置１０４は、隔壁１１７により現像剤室Ｒ₁、撹拌室Ｒ₂に区画され、それぞれ現像剤搬送スクリュー１１３、１１４が設置されている。撹拌室Ｒ₂の上方には、補給用トナー１１８を収容したトナー貯蔵室Ｒ₃が設置され、貯蔵室Ｒ₃の下部にはトナー補給口１２０が設けられている。
【０１７２】
現像剤搬送スクリュー１１３は回転することによって、現像剤室Ｒ₁内の現像剤を撹拌しながら現像スリーブ１１１の長手方向に沿って一方向に搬送する。隔壁１１１７には図の手前側と奥側に図示しない開口が設けられており、スクリュー１１３によって現像剤室Ｒ₁の一方に搬送された現像剤は、その一方側の隔壁１１７の開口を通って撹拌室Ｒ₂に送り込まれ、現像剤搬送スクリュー１１４に受け渡される。スクリュー１１４の回転方向はスクリュー１１３と逆で、撹拌室Ｒ₂内の現像剤、現像剤室Ｒ₁から受け渡された現像剤及びトナー貯蔵室Ｒ₃から補給されたトナーを撹拌、混合しながら、スクリュー１１３とは逆方向に撹拌室Ｒ₂内を搬送し、隔壁１１７の他方の開口を通って現像剤室Ｒ₁に送り込む。
【０１７３】
感光体１上に形成された静電潜像を現像するには、現像剤室Ｒ₁内の現像剤１１９がマグネットローラ１１２の磁力により汲み上げられ、現像スリーブ１１１の表面に担持される。現像スリーブ１１１上に担持された現像剤は、現像スリーブ１１１の回転にともない規制ブレード１１５に搬送され、そこで適正な層厚の現像剤薄層に規制された後、現像スリーブ１１１と感光体１０１とが対向した現像領域に至る。マグネットローラ１１２の現像領域に対応した部位には、磁極（現像極）Ｎ₁が位置されており、現像極Ｎ₁が現像領域に現像磁界を形成し、この現像磁界により現像剤が穂立ちして、現像領域に現像剤の磁気ブラシが生成される。そして磁気ブラシが感光体１０１に接触し、反転現像法により、磁気ブラシに付着しているトナーおよび現像スリーブ１１１の表面に付着しているトナーが、感光体１０１上の静電潜像の領域に転移して付着し、静電潜像が現像されトナー像が形成される。
【０１７４】
現像領域を通過した現像剤は、現像スリーブ１１１の回転にともない現像装置１０４内に戻され、スクリュー１１３により現像スリーブ１１１から剥ぎ取られ、現像剤室Ｒ₁および撹拌室Ｒ₂内に落下して回収される。
【０１７５】
上記の現像により現像装置１０４内の現像剤１１９のＴ／Ｃ比（トナーとキャリアの混合比、すなわち現像剤中のトナー濃度）が減ったら、補給現像剤貯蔵室Ｒ₃から補給現像剤１１８を現像で消費された量に見あった量で撹拌室Ｒ₂に補給し、必要以上に増量したキャリアは、トナーと混合された劣化現像剤として、１２９の排出スクリューから外部へ除去され、現像装置１０４内の現像剤１１９のＴ／Ｃおよびキャリア量が所定量に保たれる。その容器１０４内の現像剤１１９のＴ／Ｃ比の検知には、コイルのインダクタンスを利用して現像剤の透磁率の変化を測定するトナー濃度検知センサー１２８を使用する。該トナー濃度検知センサーは、図示されないコイルを内部に有している。
【０１７６】
現像スリーブ１１１の下方に配置され、現像スリーブ１１１上の現像剤１１９の層厚を規制する規制ブレード１１５は、アルミニウム又はＳＵＳ３１６の如き非磁性材料で作製される非磁性ブレード１１５である。その端部と現像スリーブ１１１面との距離は１５０〜８００μｍ、好ましくは２５０〜７００μｍである。この距離が１５０μｍより小さいと、磁性キャリアが凝集してこの間に詰まり現像剤層にムラを生じやすいと共に、良好な現像を行うのに必要な現像剤を塗布しにくく、濃度の薄いムラの多い現像画像が形成されやすい。現像剤中に混在している不用粒子による不均一塗布（いわゆるブレードづまり）を防止するためにはこの距離は１５０μｍ以上が好ましい。８００μｍより大きいと現像スリーブ１１１上へ塗布される現像剤量が増加し所定の現像剤層厚の規制が行いにくく、感光体１０１への磁性キャリア粒子の付着が多くなると共に現像剤の循環、規制ブレード１１５による現像規制が弱まりトナーのトリボが低下しカブリやすくなる。
【０１７７】
この磁性キャリア粒子層は、現像スリーブ１１１が矢印方向に回転駆動されても磁気力・重力に基づく拘束力と現像スリーブ１１１の移動方向への搬送力との釣合いによってスリーブ表面から離れるに従って動きが遅くなる。重力の影響により落下するものである。
【０１７８】
また、現像されたトナー像は、搬送されてくる転写材（記録材）１２５上へ、バイアス印加手段１２６により転写バイアス印加されている転写手段である転写ブレード１２７により転写され、転写材上に転写されたトナー像は、図示されていない定着装置により転写材に定着される。転写工程において、転写材に転写されずに感光体１０１上に残った転写残トナーは、帯電工程において、帯電を調整され、現像時に回収される。
【０１７９】
図６は、本発明の画像形成方法をフルカラー画像形成装置に適用した概略図を示す。また、図６におけるフルカラー画像形成装置においても、感光体上に残存した転写残トナーを回収し貯蔵するための独立したクリーニング手段を有さず、現像手段がトナー像を転写材上に転写した後に像担持体に残留したトナーを回収する現像同時クリーニング方法を行っているものである。
【０１８０】
補給現像剤に含有されるキャリアによって増量したキャリアは、容量ＵＰ分がオーバーフローして現像剤回収オーガに取り込まれ、補給用現像剤容器あるいは別の回収容器へ搬送される。
【０１８１】
フルカラー画像形成装置本体には、第１画像形成ユニットＰａ、第２画像形成ユニットＰｂ、第３画像形成ユニットＰｃ及び第４画像形成ユニットＰｄが併設され、各々異なった色の画像が潜像形成、現像、転写のプロセスを経て転写材上に形成される。
【０１８２】
画像形成装置に併設される各画像形成ユニットの構成について第１の画像形成ユニットＰａを例に挙げて説明する。
【０１８３】
第１の画像形成ユニットＰａは、静電潜像担持体としての直径３０ｍｍの感光体６１ａを具備し、この感光体６１ａは矢印ａ方向へ回転移動される。帯電手段としての一次帯電器６２ａは、直径１６ｍｍのスリーブの表面に形成された帯電用磁気ブラシが感光体６１ａの表面に接触するように配置されている。レーザ光６７ａは、一次帯電器６２ａにより表面が均一に帯電されている感光体６１ａに静電潜像を形成するために、図示されていない露光装置により照射される。感光体６１ａ上に担持されている静電潜像を現像してカラートナー像を形成するための現像手段としての現像装置６３ａは、カラートナーを保持している。転写手段としての転写ブレード６４ａは、感光体６１ａの表面に形成されたカラートナー像をベルト状の転写材担持体６８によって搬送されて来る転写材（記録材）の面に転写する。この転写ブレード６４ａは、転写材担持体６８の裏面に当接して転写バイアスを印加し得るものである。
【０１８４】
第１の画像形成ユニットＰａは、一次帯電器６２ａによって感光体６１ａを均一に一次帯電した後、露光装置６７ａにより感光体に静電潜像を形成し、現像装置６３ａで静電潜像をカラートナーを用いて現像し、この現像されたトナー像を第１の転写部（感光体と転写材の当接位置）で転写材を担持搬送するベルト状の転写材担持体６８の裏面側に当接する転写ブレード６４ａから転写バイアスを印加することによって転写材の表面に転写する。
【０１８５】
現像によりトナーが消費され、Ｔ／Ｃ比が低下すると、その低下をコイルのインダクタンスを利用して現像剤の透磁率の変化を測定するトナー濃度検知センサー８５で検知し、消費されたトナー量に応じて補給用トナー容器６５ａからトナーを補給する。なお、トナー濃度検知センサー８５は図示されないコイルを内部に有している。
【０１８６】
本画像形成装置は、第１の画像形成ユニットＰａと同様の構成で、現像装置に保有されるカラートナーの色の異なる第２の画像形成ユニットＰｂ、第３の画像形成ユニットＰｃ、第４の画像形成ユニットＰｄの４つの画像形成ユニットを併設するものである。例えば、第１の画像形成ユニットＰａにイエロートナー、第２の画像形成ユニットＰｂにマゼンタトナー、第３の画像形成ユニットＰｃにシアントナー、及び第４の画像形成ユニットＰｄにブラックトナーをそれぞれ用い、各画像形成ユニットの転写部で各カラートナーの転写材上への転写が順次行なわれる。この工程で、レジストレーションを合わせつつ、同一転写材上に一回の転写材の移動で各カラートナーは重ね合わせられ、終了すると分離帯電器６９によって転写材担持体６８上から転写材が分離され、搬送ベルトの如き搬送手段によって定着装置７０に送られ、ただ一回の定着によって最終のフルカラー画像が得られる。
【０１８７】
定着装置７０は、一対の直径４０ｍｍの定着ローラ７１と直径３０ｍｍの加圧ローラ７２を有し、定着ローラ７１は、内部に加熱手段７５及び７６を有している。
【０１８８】
転写材上に転写された未定着のカラートナー像は、この定着装置７０の定着ローラ７１と加圧ローラ７２との圧接部を通過することにより、熱及び圧力の作用により転写材上に定着される。
【０１８９】
図６において、転写材担持体６８は、無端のベルト状部材であり、このベルト状部材は、８０の駆動ローラによって矢印ｅ方向に移動するものである。他に、転写ベルトクリーニング装置７９、ベルト従動ローラ８１であり、ベルト除電器８２を有し、一対のレジストローラ８３は転写材ホルダー内の転写材を転写材担持体６８に搬送するためものである。
【０１９０】
転写手段としては、転写材担持体の裏面側に当接する転写ブレードに代えて、ローラ状の転写ローラの如き転写材担持体の裏面側に当接して転写バイアスを直接印加可能な接触転写手段を用いることが可能である。
【０１９１】
さらに、上記の接触転写手段に代えて一般的に用いられている転写材担持体の裏面側に非接触で配置されているコロナ帯電器から転写バイアスを印加して転写を行う非接触の転写手段を用いることも可能である。
【０１９２】
しかしながら、転写バイアス印加時のオゾンの発生量を制御できる点で接触転写手段を用いることが、より好ましい。
【０１９３】
【実施例】
以下、本発明を実施例を用いて具体的に説明するが、本発明はこれらに限定されない。
【０１９４】
＜１＞トナーの製造：
＜トナー１の製造＞
イオン交換水７１０質量部に、０．１Ｍ−Ｎａ₃ＰＯ₄水溶液４５０質量部を投入し、６０℃に加温した後、ＴＫ式ホモミキサー（特殊機化工業製）を用いて、１３０００ｒｐｍにて撹拌した。これに１．０Ｍ−ＣａＣｌ₂水溶液６８質量部を徐々に添加し、リン酸カルシウム化合物を含むｐＨ６．２の水系媒体を得た。
【０１９５】
一方、
・スチレン １６６質量部
・ｎ−ブチルアクリレート ３４質量部
・銅フタロシアニン顔料 １０質量部
・ジ−ｔ−ブチルサリチル酸アルミ化合物 １．５質量部
・非晶質ポリエステル １０質量部
・モノエステルワックス ２０質量部
（Ｍｗ：５００、Ｍｎ：４００、Ｍｗ／Ｍｎ：１．２５）
上記材料を室温にて、メディア分散機にて顔料を十分に微分散させ、メディアを分離した後６０℃に加温し、上記ＴＫ式ホモミキサー（特殊機化工業製）に投入して、１３０００ｒｐｍにて均一に溶解・分散した。これに、重合開始剤２，２’−アゾビス（２，４−ジメチルバレロニトリル）１０ｇを溶解し、重合性単量体組成物を調製した。
【０１９６】
前記水系媒体中に重合性単量体組成物を投入し、６０℃，Ｎ₂雰囲気下において、クレアミキサー（エムテクニック社製）にて１１０００ｒｐｍで６分間撹拌し、重合性単量体組成物を造粒した。その後、水系媒体をパドル撹拌翼で撹拌しつつ、８０℃に昇温し、ｐＨを６．２に維持しながら５時間の重合反応を行った。
【０１９７】
重合反応終了後、冷却し、ｐＨ２となるように塩酸を加えリン酸カルシウム化合物を溶解させた後、ろ過、水洗、乾燥、分級をして、重合粒子（トナー粒子）を得た。
【０１９８】
得られた重合粒子（トナー粒子）１００質量部に対して、下記の外添剤２種を外添し、外添後に３００メッシュ（目開き５３μｍ）の篩で粗粒を除去し、負帯電性のシアントナー１を得た。シアントナー１の重量平均粒径は７．５μｍであり、平均円形度０．９７８であり、２μｍ以下のトナー粒子が８．３個数％であった。
【０１９９】
・第１の外添剤（疎水性シリカ微粉体０．６質量部）
シリカ微粉体１００質量部に対して気相中でヘキサメチルジシラザン１０質量部で疎水化処理したものであり、ＢＥＴ比表面積が４０ｍ²／ｇであり、個数平均粒径３０ｎｍである。
【０２００】
・第２の外添剤（疎水性酸化チタン微粉体０．７質量部）
酸化チタン微粉体１００質量部に対して水媒体中でｎ−オクチルトリメトキシシラン１０質量部で疎水化処理したものであり、ＢＥＴ比表面積が９５ｍ²／ｇであり、個数平均粒径３５ｎｍである。
【０２０１】
＜トナー２の製造＞
トナー１の製造例において、リン酸カルシウム化合物に加えて乳化剤を併用する以外は同様にして、負帯電性のシアントナー２を得た。シアントナー２の重量平均粒径は２．８μｍであり、平均円形度０．９８２であり、２μｍ以下のトナー粒子が３８．６個数％であった。
【０２０２】
＜トナー３の製造＞
トナー１の製造例において、リン酸カルシウム化合物を２／３量にする以外は同様にして、負帯電性のシアントナー３を得た。シアントナー３の重量平均粒径は１０．５μｍであり、平均円形度０．９６８であり、２μｍ以下のトナー粒子が７．５個数％であった。
【０２０３】
＜トナー４の製造＞
トナー１の製造例において、モノエステルワックスを使用しない以外は同様にして、負帯電性のシアントナー４を得た。シアントナー４の重量平均粒径は７．１μｍであり、平均円形度０．９７５であり、２μｍ以下のトナー粒子が７．９個数％であった。
【０２０４】
＜トナー５の製造＞
トナー１の製造例において、モノエステルワックスを８５質量部使用する以外は同様にして、負帯電性のシアントナー５を得た。シアントナー５の重量平均粒径は８．１μｍであり、平均円形度０．９６２であり、２μｍ以下のトナー粒子が１５．４個数％であった。
【０２０５】
＜トナー６の製造＞
・テレフタル酸／フマル酸／無水トリメリット酸／プロピレンオキサイド
付加ビスフェノールＡの誘導体からなるポリエステル樹脂 １００質量部
・銅フタロシアニン顔料 ５質量部
・ジ−ｔ−ブチルサリチル酸のアルミ化合物 ２質量部
上記材料をヘンシェルミキサーにより十分予備混合を行い、二軸押出式混練機により溶融混練し、冷却後ハンマーミルを用いて約１〜２ｍｍ程度に粗粉砕し、次いでエアージェット方式による微粉砕機で微粉砕した。さらに得られた微粉砕物を分級して、重量平均粒径が５．８μｍである負摩擦帯電性のシアントナー粒子を得た。
【０２０６】
得られたシアントナー粒子にシアントナー１の製造と同様に２種の外添剤を外添して負帯電性のシアントナー６を調製した。シアントナー６は、重量平均粒径５．８μｍ、平均円形度０．９５４、２μｍ以下のトナー粒子が２６．８個数％があった。
【０２０７】
＜トナー７の製造＞
銅フタロシアニン顔料のかわりにキナクリドン顔料１０質量部を使用すること以外は、トナー１の製造と同様にしてマゼンタ色の重合粒子（トナー粒子）を得た。得られた重合粒子にトナー１の製造と同様にして外添剤２種を外添して負帯電性のマゼンタトナー７を調製した。マゼンタトナー７は、重量平均粒径７．６μｍ、平均円形度０．９７３、２μｍ以下のトナー粒子が８．８個数％であった。
【０２０８】
＜トナー８の製造＞
銅フタロシアニン顔料のかわりにＣ．Ｉ．ピグメントイエロー１７を１０質量部使用すること以外は、トナー１の製造と同様にしてイエローの重合粒子（トナー粒子）を得た。得られた重合粒子にトナー１の製造と同様にして外添剤を外添して負帯電性のイエロートナー８を調製した。イエロートナー８は、重量平均粒径７．７μｍ、平均円形度が０．９７３、２μｍ以下のトナー粒子が１０．１個数％であった。
【０２０９】
＜トナー９の製造＞
銅フタロシアニン顔料のかわりにカーボンブラック１２質量部を使用すること以外は、トナー１の製造と同様にしてブラック色の重合粒子（トナー粒子）を得た。得られた重合粒子にトナー１の製造と同様にして外添剤を外添して負帯電性のブラックトナー９を調製した。ブラックトナーは、重量平均粒径７．２μｍ、平均円形度が０．９７７、２μｍ以下のトナー粒子が７．９個数％であった。
【０２１０】
＜２＞磁性キャリアの製造：
＜磁性キャリア１の製造＞
・フェノール（ヒドロキシベンゼン） ５０質量部
・３７質量％のホルマリン水溶液 ８０質量部
・水 ５０質量部
・シラン系カップリング剤で表面処理された
マグネタイト微粒子 ３２０質量部
（５０％粒径０．２５μｍ、体積抵抗値３×１０⁵Ωｃｍ）
・シラン系カップリング剤で表面処理された
α−Ｆｅ₂Ｏ₃微粒子 ８０質量部
（５０％粒径０．３５μｍ、体積抵抗値６×１０⁹Ωｃｍ）
・２５質量％のアンモニア水 １５質量部
上記材料を四ツ口フラスコに入れ、撹拌混合しながら５０分間で８５℃まで昇温保持し、１２０分間反応・硬化させた。その後３０℃まで冷却し５００質量部の水を添加した後、上澄み液を除去し、沈殿物を水洗し、風乾した。次いでこれを減圧下（６６５Ｐａ＝５ｍｍＨｇ）１６０℃で２４時間乾燥して、フェノール樹脂をバインダー樹脂とする磁性キャリアコア（Ａ）を得た。
【０２１１】
得られた磁性キャリアコア（Ａ）の表面に、下記一般式（６）で表されるγ−アミノプロピルトリメトキシシランの３質量％メタノール溶液を塗布した。
【０２１２】
【化１】

【０２１３】
磁性キャリアコア（Ａ）の表面は、０．１２質量％γ−アミノプロピルトリメトキシシランで処理されていた。塗布中は、磁性キャリアコア（Ａ）に剪断応力を連続して印加しながら、塗布しつつメタノールを揮発させた。
【０２１４】
磁性キャリアコア（Ａ）の表面に
【０２１５】
【化２】

が存在しているのが確認された。
【０２１６】
上記処理機内のシランカップリング剤で処理された磁性キャリアコア（Ａ）を５０℃で撹拌しながら、シリコーン樹脂ＳＲ２４１０（東レダウコーニング（株）製）を、シリコーン樹脂固形分として２０％になるようトルエンで希釈した後、減圧下で添加して、０．５質量％の樹脂被覆を行った。
【０２１７】
以後、窒素ガスの雰囲気下で２時間撹拌しつつ、トルエンを揮発させた後、窒素ガスによる雰囲気下で１４０℃，２時間熱処理を行い、凝集をほぐした後、２００メッシュ（７５μｍの目開き）以上の粗粒を除去し、磁性キャリア１を得た。
【０２１８】
得られた磁性キャリア１の５０％粒径は３５μｍ、体積抵抗値は８×１０¹³Ωｃｍ、７９．６ｋＡ／ｍ（１０００エルステッド）における飽和磁化は４４Ａｍ²／ｋｇであり、残留磁化は５．１Ａｍ²／ｋｇ、真比重は３．７０であり、嵩密度は１．８６ｇ／ｃｍ³であった。
【０２１９】
＜磁性キャリア２の製造＞
磁性キャリア１の製造において、磁性キャリアコア（Ａ）の代わりにＢｉ−Ｎｉ−Ｚｎ−Ｆｅ組成のフェライトコアを使用する以外は同様にして、５０％粒径３８μｍ、体積抵抗値５×１０¹¹Ωｃｍ、飽和磁化６６Ａｍ²／ｋｇ、残留磁化２．５Ａｍ²／ｋｇ、真比重４．７１、嵩密度は２．３５ｇ／ｃｍ³の磁性キャリア２を得た。
【０２２０】
＜磁性キャリア３の製造＞
・テレフタル酸無水トリメリット酸／プロピレンオキサイド
付加ビスフェノールＡの誘導体からなるポリエステル樹脂 １００質量部
・製造例１使用のマグネタイト ５００質量部
・４級アンモニウム塩化合物 ５質量部
上記材料をヘンシェルミキサーにより十分予備混合を行い、二軸押出式混練機により溶融混練し、冷却後ハンマーミルを用いて約１〜２ｍｍ程度に粗粉砕し、次いでエアージェット方式による微粉砕機で微粉砕した。さらに得られた微粉砕物を分級した後、０．０２μｍのスチレン／メチルメタクリレート共重合樹脂粒子を、ハイブリタイザー（奈良機械社製）で乾式コートして、５０％粒径４３μｍ、体積抵抗値４×１０⁹Ωｃｍ、飽和磁化５２Ａｍ²／ｋｇ、残留磁化４．５Ａｍ²／ｋｇ、真比重４．０５、嵩密度は１．６６ｇ／ｃｍ³の磁性キャリア３を得た。
【０２２１】
＜磁性キャリア４の製造＞
磁性キャリア１の製造において、磁性キャリアコア（Ａ）に０．０２μｍのスチレン／メチルメタクリレート共重合樹脂粒子を、ハイブリタイザー（奈良機械社製）で乾式コートする以外は同様にして、５０％粒径３８μｍ、体積抵抗値９×１０¹²Ωｃｍ、飽和磁化４１Ａｍ²／ｋｇ、残留磁化５．２Ａｍ²／ｋｇ、真比重３．７１、嵩密度は１．８３ｇ／ｃｍ³の磁性キャリア４を得た。
【０２２２】
＜磁性キャリア５の製造＞
磁性キャリア３の製造において、粉砕分級条件を変える以外は同様にして、５０％粒径２３μｍ、体積抵抗値１×１０⁹Ωｃｍ、飽和磁化５０Ａｍ²／ｋｇ、残留磁化４．６Ａｍ²／ｋｇ、真比重４．０２、嵩密度は１．５２ｇ／ｃｍ³の磁性キャリア５を得た。
【０２２３】
＜磁性キャリア６の製造＞
磁性キャリア３の製造において、粉砕分級条件を変える以外は同様にして、５０％粒径５３μｍ、体積抵抗値３×１０⁹Ωｃｍ、飽和磁化５１Ａｍ²／ｋｇ、残留磁化４．７Ａｍ²／ｋｇ、真比重４．０２、嵩密度は１．６５ｇ／ｃｍ³の磁性キャリア６を得た。
【０２２４】
＜３＞感光体の製造：
＜感光体１の製造＞
感光体は負帯電用の有機光導電物質を用いた感光体であり、φ３０ｍｍのアルミニウム製のシリンダー上に機能層を５層設けた。
【０２２５】
第１層は導電層であり、アルミニウムシリンダーの欠陥などをならすため、またレーザ露光の反射によるアモレの発生を防止するために設けられている厚さ約２０μｍの導電性粒子分散樹脂層である。
【０２２６】
第２層は正電荷注入防止層（下引き層）であり、アルミニウム基体から注入された正電荷が感光体表面に帯電された負電荷を打ち消すのを防止する役割を果たし、６−６６−６１０−１２−ナイロンとメトキシメチル化ナイロンによって１０⁶Ω・ｃｍ程度に抵抗調整された厚さ約１μｍの中抵抗層である。
【０２２７】
第３層は電荷発生層であり、ジスアゾ系の顔料を樹脂に分散した厚さ約０．３μｍの層であり、レーザ露光を受けることによって正負の電荷対を発生する。
【０２２８】
第４層は電荷輸送層であり、ポリカーボネート樹脂にヒドラゾンを分散したものであり、Ｐ型半導体である。従って、感光体表面に帯電された負電荷はこの層を移動することはできず、電荷発生層で発生した正電荷のみを感光体表面に輸送することができる。
【０２２９】
第５層は電荷注入層であり、光硬化性のアクリル樹脂にＳｎＯ₂超微粒子、更に帯電部材と感光体との接触時間を増加させて、均一な帯電を行うために粒径約０．２５μｍの四フッ化エチレン樹脂粒子を分散したものである。具体的には、酸素欠損型の低抵抗化した粒径約０．０３μｍのＳｎＯ₂粒子を樹脂に対して１２０質量％、更に四フッ化エチレン樹脂粒子を２０質量％、分散剤を１．０質量％分散したものである。
【０２３０】
これによって感光体１の表面層の体積抵抗値は、荷電輸送層単体の場合５×１０¹⁵Ωｃｍだったのに比べ、８×１０¹¹Ωｃｍにまで低下した。
【０２３１】
＜４＞帯電部材に用いる磁性粒子の製造：
＜磁性粒子ａの製造＞
ＭｇＯを１０質量部、ＭｎＯを１０質量部、Ｆｅ₂Ｏ₃を８０質量部それぞれ微粒化した後、水を添加混合し、造粒した後、１３００℃にて焼成し、粒度を調整した後、平均粒径２２μｍのフェライト芯材（飽和磁化６３Ａｍ²／ｋｇ）を得た。
【０２３２】
このフェライト芯材に、イソプロポキシトリイソステアロイルチタネート１０質量部をトルエン９９質量部／水１質量部に混合させたものを、０．１質量部となるように表面処理して、５０％粒径が２５．５μｍ、体積抵抗値が７×１０⁷Ωｃｍの磁性粒子ａを得た。
【０２３３】
〔実施例１〕
上記で得られた磁性キャリア１（９２質量部）とシアントナー１（８質量部）をＶ型混合機で混合し、スタート用シアン現像剤１とした。
【０２３４】
一方、磁性キャリア１（１質量部）とシアントナー１（１９質量部）をＶ型混合機で混合し、補給用シアン現像剤１とした。
【０２３５】
次に、市販の複写機ＧＰ５５（キヤノン製）の現像装置を図３に示す如く改造した。具体的には、現像スリーブとしてはφ１６ｍｍのＳＵＳスリーブをサンドブラスト処理によって表面形状を表面粗さＲｚ＝１２．１μｍに調整したものを使用した。
【０２３６】
帯電部材としては、図５に示す磁気ブラシ帯電器を用いて磁性粒子ａを使用し、感光体の当接部に対して逆方向に１００％で回転させ、直流／交流電界（−７００Ｖ、１．５ｋＨｚ／１．２ｋＶｐｐ）を重畳印加し、感光体を帯電させる。また、クリーニングユニットを取り外し、現像コントラスト２５０Ｖ、カブリとの反転コントラスト−１８０Ｖに設定し、不示図の現像バイアス印加手段から図７の非連続の交流電圧を有する現像バイアスを印加し、定着装置を加熱ローラ、加圧ローラともに、表層をＰＦＡ（４フッ化エチレン−パーフルオロアルキルビニルエーテル共重合体）で１．２μｍ被覆したローラに変更し、且つ、オイル塗布機構を除去した構成に改造した。
【０２３７】
画像面積３５％のオリジナル原稿を使用し、２３℃／６０％（以下、「Ｎ／Ｎ」とも記載する）、２３℃／５％（以下、「Ｎ／Ｌ」とも記載する）、３２．５℃／９０％（以下、「Ｈ／Ｈ」とも記載する）の各環境で、それぞれＣＬＣ８０ｇ紙（キヤノン販売社製）を用いて１２０ｍｍ／ｓｅｃの画像形成速度で通紙試験を行い、以下の評価方法に基づいて評価した。
【０２３８】
結果を表１に示すが、表１からわかるように良好な結果が得られた。
【０２３９】
[評価方法・基準]
（１）画像濃度
画像濃度は、ＳＰＩフィルターを装着したマクベス社製マクベスデンシトメータＲＤ９１８タイプ（Ｍａｃｂｅｔｈ Ｄｅｎｓｉｔｏｍｅｔｅｒ ＲＤ９１８ｍａｎｕｆａｃｔｕｒｅｄ ｂｙ Ｍｃｂｅｔｈ Ｃｏ．）を使用して、オリジナル画像濃度１．５で普通紙上に形成された画像の４隅、中央の５点平均の相対濃度として測定した。
【０２４０】
（２）ハーフトーン再現性
オリジナル画像濃度０．３を用いて（１）同様相対濃度として測定した。
◎：０．３〜０．４
○：０．２５〜０．３未満
△：０．２０〜０．２５未満
×：０．２未満
【０２４１】
（３）カブリ
画出し前の普通紙の平均反射率Ｄｒ（％）をリフレクトメータ（東京電色株式会社製の「ＲＥＦＬＥＣＴＯＭＥＴＥＲ ＭＯＤＥＬ ＴＣ−６ＤＳ」）によって測定した。一方、普通紙上にベタ白画像を画出しし、次いでベタ白画像の反射率Ｄｓ（％）を測定した。カブリ（％）は下記式から算出する。
【０２４２】
Ｆｏｇ（％）＝Ｄｒ（％）−Ｄｓ（％）
◎：０．４％未満
○：０．４〜０．８％未満
△：０．８〜１．２％未満
×：１．２％以上
【０２４３】
（４）ベタ均一性
オリジナル画像濃度１．５を用いて（１）同様５点の相対濃度を測定し、最大濃度差として測定した。
◎：０．０〜０．０５未満
○：０．０５〜０．１５未満
△：０．１５〜０．２５未満
×：０．２５以上
【０２４４】
〔比較例１〕
実施例１において、シアントナー２を使用する以外は同様にして行ったところ、表１に示すように各環境の通紙条件で画像濃度が低下し、カブリも悪化した。これは、トナーの粒径が小さいために、トナーの帯電均一性が損なわれたためと推測される。
【０２４５】
〔比較例２〕
実施例１において、シアントナー３を使用する以外は同様にして行ったところ、表１に示すようにＨ／Ｈ下の通紙条件でハーフトーン再現性が低下し、カブリも悪化した。これは、トナーの粒径が大きいために、トナーの帯電性が低く、潜像に忠実に現像することが困難になったためと推測される。
【０２４６】
〔比較例３〕
実施例１において、シアントナー４を使用する以外は同様にして行ったところ、表１に示すように各環境の通紙条件で、紙が定着ローラーに貼りつき、ハーフトーン再現性が低下し、ベタ均一性も悪化したので初期評価だけで評価を中止した。これは、トナーにワックスが無いために、トナーがオフセットして通紙することが困難になったためと推測される。
【０２４７】
〔比較例４〕
実施例１において、シアントナー５を使用する以外は同様にして行ったところ、表１に示すように特にＨ／Ｈ下の通紙条件で、ハーフトーン再現性が低下し、カブリ、ベタ均一性も悪化した。これは、トナーにワックスが多いために、トナーがキャリアにスペントして帯電が不均一なったためと推測される。
【０２４８】
〔実施例２〕
実施例１において、シアントナー６を使用する以外は同様にして行ったところ、表１に示すようにＨ／Ｈ下の通紙条件で若干特性が悪化したものの実用上問題無い結果が得られた。これは、トナー非球形状になったために、転写性が若干悪化したためと推測される。
【０２４９】
〔比較例５〕
実施例１において、磁性キャリア１（１質量部）とシアントナー１（１質量部）をＶ型混合機で混合した補給用シアン現像剤２を使用する以外は同様にして行ったところ、表１に示すように各環境の通紙条件で、５００枚時点で、画像濃度低下、ベタ均一性が悪化したので評価を中止した。これは、補給現像剤中のトナー量が少ないために、ベタ画像において、トナー補給が追いつかず、不均一なったためと推測される。
【０２５０】
〔比較例６〕
実施例１において、磁性キャリア１（１質量部）とシアントナー１（６０質量部）をＶ型混合機で混合した補給用シアン現像剤３を使用する以外は同様にして行ったところ、表１に示すように各環境の通紙条件で、カブリが悪化した。これは、補給現像剤中のキャリア量が少ないために、トナースペントしたキャリアの交換が追いつかず、トナーの帯電が不均一なったためと推測される。
【０２５１】
〔比較例７〕
実施例１において、磁性キャリア２を使用する以外は同様にして行ったところ、表１に示すように各環境の通紙条件で、カブリが悪化した。これは、キャリアの比重が大きいために現像剤にストレスがかかりやすく、トナースペントが多くなり、トナーの帯電が不均一なったためと推測される。
【０２５２】
〔実施例３〕
実施例１において、磁性キャリア３を使用する以外は同様にして行ったところ、表１に示すように特にＮ／Ｌ下の通紙条件で特性が悪化したものの、良好な結果が得られた。これは、キャリアが非球状であるために、現像機内の循環性が若干悪化し、トナーへの帯電付与能が低下したためと推測される。
【０２５３】
【表１】

【０２５４】
〔実施例５〕
実施例１において、磁性キャリア５を使用する以外は同様にして行ったところ、表１に示すように各環境で特性が若干悪化したものの、良好な結果が得られた。これは、キャリアの粒径が小さいために、現像機内での循環が乱され、現像スリーブ上のコートムラが生じやすくなったものと推測される。
【０２５５】
〔実施例６〕
実施例１において、磁性キャリア６を使用する以外は同様にして行ったところ、表１に示すように各環境で特性が若干悪化したものの、良好な結果が得られた。これは、キャリアの粒径が大きいために、トナーへの帯電付与能が低下し、トナーの帯電不均一が生じやすくなったものと推測される。
【０２５６】
〔実施例７〕
マゼンタトナー７、イエロートナー８、シアントナー１、ブラックトナー９を使用し、ＣＬＣ１０００（キヤノン製）を改造した、図６の画像形成装置を用いて、フルカラー画像を作成したところ、実施例１と同様に良好な結果が得られた。
【０２５７】
【表１】

【０２５８】
【発明の効果】
本発明の補給現像剤は、上記の構成を有するから、環境に左右されることなくトナーの帯電性が安定化し、良好な画質を長期にわたって得ることができる。
【図面の簡単な説明】
【図１】本発明の補給用現像剤が使用されるロータリー回転方式の現像装置を備えた画像形成装置の一つの実施の形態である図を示す。
【図２】図１の現像装置の一つの実施の形態である図を示す。
【図３】図１の現像装置を説明するための拡大構成図を示す。
【図４】図３の現像装置の一つの実施の形態である図を示す。
【図５】本発明のクリーナーレスシステムに使用される現像装置を備えた画像形成装置の一つの実施の形態である図を示す。
【図６】本発明のフルカラー画像形成装置の一つの実施の形態である図を示す。
【図７】図５で用いられる画像形成装置に使用される現像バイアスの非連続の交流電界を有するバイアスを示す。
【符号の説明】
１ 感光ドラム
２，３，４，５ 現像装置
６ 現像スリーブ
７ 規制ブレード
８ マグネットローラ
９ 補給現像剤収容装置
１０，１１ 現像剤搬送スクリュー
１２ 転写材
１３ 現像装置
１４ 露光手段
１５ ローラー帯電装置
１７ 現像槽
１８，２３ クリーニング装置
１９，２２，３３ 除電装置
２０ 搬送ガイドブザイ部材
２１ 定着機
２４ 転写ドラム
２５ レジローラー
２６，２７ 給紙トレイ
２８，２９ 送りローラー
３０ 対向ローラー
３１ 転写装置
３２ 吸着装置
３４ 現像剤排出口
３５ 現像剤回収口
３７ 現像剤一次保管部
３８ 現像剤回収オーガ[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to a replenishing developer for visualizing an electrostatic latent image in electrophotography and electrostatic recording.,Development methodAnd image forming methodAbout.
[0002]
[Prior art]
Currently, the mainstream two-component development method consumes toner by development and stays in the developing machine without consuming the carrier, so that carrier contamination occurs due to transfer of the toner component to the carrier, or the carrier itself is stress in the developing machine. As a result, the resin coating layer is peeled off, affecting the developer characteristics such as chargeability, and the image density is fluctuated and fogging occurs.
[0003]
As a solution to this problem, for example, in JP-B-2-21591, a carrier is added together with toner consumed by development, and the carrier in the developing machine is replaced little by little to suppress the change in charge amount. However, a developing device that stabilizes the image density, a so-called trickle developing device is disclosed. However, since the carrier used is an iron powder carrier having a large saturation magnetization, the carrier stress in the developing machine is large, and the carrier is likely to deteriorate during repeated copying operations. Otherwise, image degradation was likely to be quick and was not satisfactory.
[0004]
On the other hand, Japanese Patent Application Laid-Open No. 3-145678 discloses that toner is contained in a carrier having a higher resistance value than that of a carrier stored in advance in a developing machine to maintain chargeability and suppress deterioration in image quality. Has been. Furthermore, Japanese Patent Application Laid-Open No. 11-223960 discloses that a carrier that imparts a higher charge amount to the toner contains toner to maintain chargeability and suppress deterioration in image quality. However, in these methods, since the amount of the carrier to be replaced differs depending on the difference in toner consumption, the resistance or charge amount of the developer in the developing machine changes, and the image density tends to fluctuate, which is not satisfactory. There wasn't.
[0005]
Further, Japanese Patent Application Laid-Open No. 8-234550 discloses a method of replenishing each toner sequentially using a plurality of replenishing toners containing a carrier having different physical properties from the carrier previously stored in the developing machine. In practice, however, the specific gravity of the carrier and toner is extremely different from the fact that replenishment toner containing multiple carriers having different physical properties in one toner replenishment container is replenished in order so as not to mix. In addition, it is very difficult, and since there is much toner relative to the carrier, the carrier is likely to be deteriorated, and a stable image cannot be obtained for a long time.
[0006]
[Problems to be solved by the invention]
  The present invention has been made for the purpose of solving various problems as described above. That is, an object of the present invention is to provide a replenishing developer capable of obtaining a stable image throughout the life of the main body.,Development method using the sameAnd image forming methodIs to provide.
[0007]
[Means for Solving the Problems]
As a result of studying a two-component developer exhibiting good characteristics throughout the life of the main body, the present inventors use a magnetic fine particle dispersed resin carrier having at least inorganic compound particles and a binder resin as a carrier to be included in the replenishing toner. Thus, the present inventors have found that the above problem can be solved even if a toner having a weight average particle diameter of 3 to 10 μm and containing 1 to 40% by weight of solid wax is used as a toner, and the present invention is completed. It came to.
[0008]
  That is, the present invention replenishes a replenishment developer when developing a latent image on a latent image holding body using a developing machine containing a two-component developer composed of toner and carrier.And discharge the excess developer.A developer for replenishment for use in a development method in which development is performed, wherein the carrier and the toner are contained in parts by mass, in a blending ratio of 2 to 50 parts of toner with respect to 1 part of the carrier, and the carrier is at least A magnetic fine particle dispersed resin carrier having inorganic compound particles and a binder resin.What,Volume resistance is 1 × 10 ⁹ ~ 1x10 ¹⁵ Ω · cm and true specific gravity of 2.8 to 4.2 g / cm ^Three AndThe toner has a weight average particle diameter of 3 to 10 μm and contains 1 to 40% by mass of a solid wax. Further, the carrier core of the magnetic fine particle dispersed resin carrier is preferably a polymerized carrier core, and the toner particles are preferably polymerized toner particles.
[0009]
  The developing method of the present invention replenishes the replenishment developer using a developing machine containing a two-component developer composed of toner and carrier.And discharge the excess developer.In the developing method for developing the latent image on the latent image carrier, the carrier and toner are contained in a mass ratio as a replenishment developer in a mixing ratio of 2 to 50 parts of toner with respect to 1 part of carrier. Is a magnetic fine particle dispersed resin carrier having at least inorganic compound particles and a binder resin.What,Volume resistance is 1 × 10 ⁹ ~ 1x10 ¹⁵ Ω · cm and true specific gravity of 2.8 to 4.2 g / cm ^Three AndThe toner has a weight average particle diameter of 3 to 10 μm and contains 1 to 40% by mass of a solid wax. Further, the carrier core of the magnetic fine particle dispersed resin carrier is preferably a polymerized carrier core, and the toner particles are preferably polymerized toner particles.Further, the image forming method of the present invention develops the latent image on the latent image holding member using a developing machine containing a two-component developer composed of toner and carrier, replenishes the replenishment developer, and becomes excessive. In an image forming method for forming an image while discharging a developer, the replenishment developer contains a carrier and a toner in a mass ratio of 2 to 50 parts of toner with respect to 1 part of the carrier. A magnetic fine particle-dispersed resin carrier having at least inorganic compound particles and a binder resin, and having a volume resistance of 1 × 10 ⁹ ~ 1x10 ¹⁵ Ω · cm and true specific gravity of 2.8 to 4.2 g / cm ^Three And
  The toner has a weight average particle diameter of 3 to 10 μm and contains 1 to 40% by mass of a solid wax.
[0010]
In particular, the dispersion type carrier produced by the polymerization method is excellent in fluidity because it is relatively easy to make a spherical shape with a small particle shape distortion and high particle strength. Can be controlled sharply, so there is little difference in the particle size distribution between the carrier remaining in the developing machine and the recovered carrier, and it is excellent in recoverability without uneven distribution such as collecting only fine powder or coarse powder. It is.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail with reference to embodiments of the present invention.
[0012]
The carrier particle size used in the present invention is preferably 50 to 50 μm, more preferably 25 to 50 μm, based on volume basis. When the 50% particle size of the carrier is less than 15 μm, the fluidity of the carrier is lowered, and fine powder tends to accumulate, and uniform carrier recovery may not be carried out satisfactorily. When the 50% particle size of the carrier is larger than 60 μm, the density of the magnetic brush is likely to be impaired, and image unevenness may occur.
[0013]
In the present invention, the volume resistivity of the carrier is 1 × 10⁸~ 1x10¹⁶Preferably, it is Ω · cm, more preferably 1 × 10⁹~ 1x10¹⁵It should be Ω · cm.
[0014]
The volume resistivity of the carrier is 1 × 10⁸If it is less than Ω · cm, the carrier and toner in the replenishment developer are likely to be liberated, making quantitative replenishment difficult.
[0015]
The volume resistivity of the carrier is 1 × 10¹⁶If it exceeds Ω · cm, an edge-enhanced image is likely to be formed, and further, the charge on the carrier surface is difficult to leak. Therefore, the image density decreases due to the charge-up phenomenon, and the newly supplied carrier and toner It may cause fogging and scattering due to non-uniform charging. Further, the toner may be charged with a substance such as the inner wall of the replenishing container, and the amount of charge of the toner to be originally applied may become non-uniform. In addition, it tends to cause image defects such as electrostatic external additives.
[0016]
The volume resistance value of the carrier was measured using a powder insulation resistance measuring instrument manufactured by Vacuum Riko Co., Ltd. The measurement conditions were as follows: a carrier left at 23 ° C. and 60% for 24 hours or more had a diameter of 20 mm (0.283 cm)²11.8 kPa (120 g / cm)²), The thickness was set to 2 mm, and the applied voltage was measured at 500V.
[0017]
The true specific gravity of the carrier is 2.5 to 4.5, preferably 2.8 to 4.2. When the true specific gravity exceeds 4.5, the specific gravity difference with the toner becomes large, and it becomes difficult to recover the carrier stably, and the apparatus tends to be complicated. On the other hand, when the true specific gravity is less than 2.5, although it is related to the magnetic characteristics of the carrier, carrier adhesion is likely to occur.
[0018]
The magnetic property of the carrier is such that the strength of magnetization at 1000 / 4π (kA / m) [1000 oersted] is preferably 15 to 65 Am.²/ Kg, more preferably 25 to 45 Am²It is good that the magnetic force is as low as / kg.
[0019]
Carrier magnetization is 65 Am²Exceeding / kg is related to the carrier particle size, but the stress in the developing machine increases and the carrier deterioration is promoted. If the amount of replenishment carrier is not increased, the durability of the developer is deteriorated particularly by copying or printing a large number of sheets. Is likely to occur.
[0020]
Also, the residual magnetization of the carrier is 20 Am²If it exceeds / kg, the fluidity deteriorates due to magnetic aggregation, the miscibility with the toner decreases, and image deterioration such as fog tends to occur.
[0021]
Carrier magnetization strength is 15 Am²/ Kg or residual magnetization is 0.1 Am²If it is less than / kg, even if the carrier fine powder is removed, the magnetic force of the carrier is reduced, and carrier adhesion tends to occur.
[0022]
The measurement of the magnetic properties of the carrier was performed using an oscillating magnetic field type magnetic property automatic recording apparatus BHV-35 manufactured by Riken Denshi Co., Ltd. As measurement conditions, an external magnetic field of 1000 / 4π (kA / m) was created as the magnetic characteristics of the carrier powder, and the strength of magnetization at that time was determined. Prepare the carrier packed in a cylindrical plastic container so that the carrier particles do not move sufficiently, measure the magnetization moment in this state, measure the actual mass when the sample is put in , Magnetization strength (Am²/ Kg).
[0023]
In the present invention, examples of the magnetic particles as the inorganic compound particles used for the carrier core include magnetite or ferrite having magnetism represented by the following formula (1) or (2).
[0024]
MO ・ Fe₂O_Three                            ... (1)
M ・ Fe₂O_Four                              ... (2)
(In the formula, M represents a trivalent, divalent or monovalent metal ion.)
[0025]
M includes Mg, Al, Si, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Ba, Pb, and Li can be mentioned, and these can be used alone or in plural.
[0026]
Specific examples of the metal compound particles having magnetism include, for example, magnetite, Zn—Fe ferrite, Mn—Zn—Fe ferrite, Ni—Zn—Fe ferrite, Mn—Mg—Fe ferrite, Ca— Examples thereof include iron-based oxides such as Mn—Fe ferrite, Ca—Mg—Fe ferrite, Li—Fe ferrite, and Cu—Zn—Fe ferrite.
[0027]
Furthermore, in the present invention, the inorganic fine particles used for the carrier core may be a mixture of the above magnetic particles and the following nonmagnetic metal compound.
[0028]
Examples of nonmagnetic metal compounds include Al.₂O_Three, SiO₂, CaO, TiO₂, V₂O_Five, CrO, MnO₂, Α-Fe₂O_Three, CoO, NiO, CuO, ZnO, SrO, Y₂O_ThreeAnd ZrO₂Is mentioned. In this case, one kind of metal compound can be used, but it is particularly preferable to use a mixture of at least two kinds of metal compounds. In that case, it is more preferable to use particles having similar specific gravity and shape in order to increase the adhesion to the binder resin and the strength of the carrier core particles.
[0029]
Specific examples of the combination include, for example, magnetite and hematite, magnetite and γ-Fe.₂O_Three, Magnetite and SiO₂, Magnetite and Al₂O_Three, Magnetite and TiO₂Magnetite and Ca—Mn—Fe based ferrite, and magnetite and Ca—Mg—Fe based ferrite can be preferably used. Among these, a combination of magnetite and hematite can be particularly preferably used.
[0030]
When the above metal compound exhibiting magnetism is used alone or mixed with a nonmagnetic metal compound, the number average particle diameter of the metal compound exhibiting magnetism also varies depending on the number average particle diameter of the carrier core. However, it is preferably 0.02 to 2 μm, more preferably 0.05 to 1 μm.
[0031]
When the number average particle diameter of the metal compound exhibiting magnetism is less than 0.02 μm, it is difficult to contain a large amount in the carrier and it is difficult to obtain preferable magnetic properties. When the number average particle size of the metal compound exhibiting magnetism exceeds 2 μm, dispersion is likely to be non-uniform and it becomes difficult to obtain a carrier having a particle size in a preferable range with high strength.
[0032]
When using a mixture of a magnetic metal compound and a nonmagnetic compound, the number average particle diameter of the nonmagnetic metal compound is preferably 0.05 to 5 μm, more preferably 0.1 to 3 μm. Since it is easy to obtain a resistance that preferably has a particle size larger than that of the metal compound having the above.
[0033]
The number average particle size of the metal oxide is 300 particles randomly having a particle size of 0.01 μm or more using a photographic image magnified 5000 to 20000 times by a transmission electron microscope H-800 manufactured by Hitachi, Ltd. One or more samples were extracted, measured with a horizontal ferret diameter as a metal oxide particle diameter by an image processing analyzer Luzex3 manufactured by Nireco Corporation, and averaged to calculate the number average particle diameter.
[0034]
In the carrier core of the present invention, the content of the metal compound is preferably 80 to 99% by mass with respect to the carrier core.
[0035]
When the content of the metal compound is less than 80% by mass, the chargeability tends to become unstable, and the carrier is charged particularly in a low-temperature and low-humidity environment. The agent easily adheres to the surface of the carrier particles, and an appropriate specific gravity cannot be obtained. When the content of the metal compound exceeds 99% by weight, the carrier strength is lowered, and problems such as cracking of the carrier due to durability tend to occur.
[0036]
Furthermore, as a preferable form of the present invention, in the carrier core containing a mixture of a magnetic metal compound and a nonmagnetic compound, the content of the metal compound having magnetism in the entire metal compound contained is preferably 50 to 95. It is good that it is mass%, More preferably, it is 60-95 mass%.
[0037]
The binder resin (binder resin) of the carrier core particles used in the present invention is a thermosetting resin and is preferably a resin that is partly or wholly crosslinked three-dimensionally. As a result, the dispersed metal compound particles can be strongly bound, so that the strength of the carrier core can be increased, and the metal compound is hardly detached even in a large number of copies. It becomes easy to coat well.
[0038]
The method for obtaining the magnetic material-dispersed carrier core is not particularly limited to the method described below, but in the present invention, from a solution in which the monomer and the solvent are uniformly dispersed or dissolved, Production method of polymerization method in which particles are produced by polymerizing monomers, in particular, a magnetic substance with a sharp particle size distribution and a small amount of fine powder by applying a lipophilic treatment to the metal oxide dispersed in the carrier core particles A method of obtaining a dispersed resin carrier core is preferably used.
[0039]
As the monomer used for the binder resin of the carrier core particle, a radical polymerizable monomer can be used. For example, styrene; styrene derivatives such as o-methyl styrene, m-methyl styrene, p-methoxy styrene, p-ethyl styrene, p-tertiary butyl styrene; acrylic acid, methyl acrylate, ethyl acrylate, n-butyl acrylate Acrylates such as n-propyl acrylate, isobutyl acrylate, octyl acrylate, dodecyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, 2-chloroethyl acrylate, phenyl acrylate; methacrylic acid, methyl methacrylate , Ethyl methacrylate, n-propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, meta Methacrylic acid esters such as phenyl laurate, dimethylaminomethyl methacrylate, diethylaminoethyl methacrylate, benzyl methacrylate; 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate; acrylonitrile, methacrylonitrile, acrylamide; methyl vinyl ether, ethyl vinyl ether , Propyl vinyl ether, n-butyl ether, isobutyl ether, β-chloroethyl vinyl ether, phenyl vinyl ether, p-methylphenyl ether, p-chlorophenyl ether, p-bromophenyl ether, p-nitrophenyl vinyl ether, p-methoxyphenyl vinyl ether And vinyl ethers; and diene compounds such as butadiene.
[0040]
These monomers can be used alone or in combination, and a suitable polymer composition can be selected so that preferable characteristics can be obtained.
[0041]
The most preferred binder resin is a phenolic resin. Examples of the starting material include phenol compounds such as phenol, m-cresol, 3,5-xylenol, p-alkylphenol, resorcil, and p-tert-butylphenol, and aldehyde compounds such as formalin, paraformaldehyde, and furfural. A combination of phenol and formalin is particularly preferable.
[0042]
When these phenol resins are used, a basic catalyst can be used as a curing catalyst. As the basic catalyst, various catalysts used in the production of ordinary resole resins can be used. Specific examples include amines such as aqueous ammonia, hexamethylenetetramine, diethyltriamine, and polyethyleneimine.
[0043]
In the present invention, the metal compound contained in the carrier core is preferably oleophilic in order to sharpen the particle size distribution of the magnetic carrier particles and to prevent the metal compound particles from being detached from the carrier. . When forming carrier core particles in which a metal compound subjected to lipophilic treatment is dispersed, particles insolubilized in the solution are generated at the same time as the polymerization reaction proceeds from a liquid in which the monomer and solvent are uniformly dispersed or dissolved. At that time, it is considered that the metal oxide is taken in uniformly and at a high density inside the particles and has an effect of preventing aggregation of the particles and sharpening the particle size distribution. Furthermore, when a metal compound subjected to oleophilic treatment is used, there is no need to use a suspension stabilizer, charging suspension due to the suspension stabilizer remaining on the carrier surface, uneven coating resin during coating And reaction inhibition when a reactive resin such as a silicone resin is coated can be prevented. In addition, the suspension stabilizer is not present on the surface and it is easy to eliminate the adverse effects associated therewith.
[0044]
The oleophilic treatment is treated with an oleophilic agent which is an organic compound having one or more functional groups selected from epoxy groups, amino groups and mercapto groups, and a mixture thereof. Is preferred. In particular, an epoxy group is preferably used in order to obtain a carrier having stable charge imparting ability of the present invention.
[0045]
The magnetic metal oxide particles are preferably treated with a lipophilic treatment agent in an amount of 0.1 to 10 parts by weight, more preferably 0.2 to 6 parts by weight per 100 parts by weight of the magnetic metal oxide particles. It is preferable for enhancing the lipophilicity and hydrophobicity of the magnetic metal oxide particles.
[0046]
Examples of the lipophilic agent having an epoxy group include γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropyltrimethoxysilane, β- (3,4-epoxycyclohexyl) trimethoxysilane, epichlorohydrin, and glycidol. And styrene- (meth) acrylic acid glycidyl copolymer.
[0047]
Examples of the lipophilic agent having an amino group include γ-aminopropyltrimethoxysilane, γ-aminopropylmethoxydiethoxysilane, γ-aminopropyltriethoxysilane, and N-β (aminoethyl) -γ-amino. Propyltrimethoxysilane, N-β (aminoethyl) -γ-aminopropylmethyldimethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, ethylenediamine, ethylenetriamine, styrene- (meth) acrylic acid dimethylaminoethyl copolymer Combined and isopropyl tri (N-aminoethyl) titanate are used.
[0048]
Examples of the lipophilic agent having a mercapto group include mercaptoethanol, mercaptopropionic acid, and γ-mercaptopropyltrimethoxysilane.
[0049]
The resin that coats the surface of the carrier core is not particularly limited. Specifically, for example, acrylic resin such as polystyrene and styrene-acrylic copolymer, vinyl chloride, vinyl acetate, polyvinylidene fluoride resin, fluorocarbon resin, perfluorocarbon resin, solvent-soluble perfluorocarbon resin, polyvinyl alcohol, polyvinyl acetal, Polyvinyl pyrrolidone, petroleum resin, cellulose, cellulose derivative, novolak resin, low molecular weight polyethylene, saturated alkyl polyester resin, aromatic polyester resin, polyamide resin, polyacetal resin, polycarbonate resin, polyethersulfone resin, polysulfone resin, polyphenylene sulfide resin, poly Ether ketone resin, phenol resin, modified phenol resin, maleic resin, alkyd resin, epoxy resin, acrylic resin, anhydrous male Unsaturated polyester obtained by polycondensation of acid, terephthalic acid and polyhydric alcohol, urea resin, melamine resin, urea-melamine resin, xylene resin, toluene resin, guanamine resin, melamine-guanamine resin, acetoguanamine resin, gliptal Examples thereof include resins, furan resins, silicone resins, polyimide resins, polyamideimide resins, polyetherimide resins, and polyurethane resins.
[0050]
Among them, a fluorine-containing resin such as polyvinylidene fluoride resin, fluorocarbon resin, perfluorocarbon resin, solvent-soluble perfluorocarbon resin, or silicone resin is preferable because of high release properties.
[0051]
In the present invention, a silicone resin is preferably used from the viewpoints of adhesion to the core, prevention of spent, and film strength. The silicone resin can be used alone, but it is preferably used in combination with a coupling agent in order to further increase the strength of the coating layer and control the charge to a preferable level. Furthermore, the coupling agent described above is preferably used as a so-called primer agent in which a part of the coupling agent is treated on the surface of the carrier core before coating the resin, and the subsequent coating layer is accompanied by a covalent bond. , It can be formed in a more adhesive state.
[0052]
Aminosilane is preferably used as the coupling agent. As a result, an amino group having positive chargeability can be introduced on the surface of the carrier, and the toner can be favorably imparted with negative charge characteristics. Furthermore, the presence of amino groups activates both the lipophilic treatment agent that is preferably treated with the metal compound and the silicone resin, thereby further improving the adhesion between the silicone resin carrier core and simultaneously curing the resin. By promoting the above, a stronger coating layer can be formed.
[0053]
The replenishment developer of the present invention is characterized in that the above-mentioned carrier and a toner described later are contained in a mixing ratio of 2 to 50 parts by mass of toner with respect to 1 part by mass of the carrier. TonerOver 50 parts by weightEven if the magnetic fine particle dispersed carrier of the present invention is used, fogging due to durability or toner scattering is likely to occur, and the replacement of the developer by a service person is required, which is not preferable. on the other hand,Less than 2 parts by weightAlthough the life of the developer is improved, the amount of the replenished developer becomes heavy due to the large amount of the carrier, the discharge property from the replenishment developer container to the developing machine deteriorates, or the recovered deteriorated developer The collection means becomes complicated, which is not preferable. Furthermore, the actual toner amount in the replenishment developer container decreases, the frequency of replacement of the toner container increases, and not only the load on the user increases but also the cost increases, which is not preferable.
[0054]
The toner for constituting the two-component developer in combination with the carrier described above contains at least a binder resin for toner and a colorant, and has a weight average particle diameter of 3 to 10 μm, preferably 3 to 8 μm. It is particularly effective. When the weight average particle size of the toner is less than 3 μm, problems such as charge-up tend to occur particularly in a low-humidity environment, and it becomes difficult to sufficiently obtain the effect using the carrier of the present invention. However, the handling property as a powder is low. When the weight average particle size of the toner exceeds 10 μm, problems such as scattering and fogging are likely to occur particularly under high temperature and high humidity, and the effect of using the carrier of the present invention cannot be sufficiently observed. Furthermore, since one toner particle becomes large, it is difficult to obtain a high-resolution and dense image. Further, when electrostatic transfer is performed, toner scattering is likely to occur.
[0055]
The average particle size and particle size distribution of the toner were measured as follows.
[0056]
0.1 to 5 ml of a surfactant (alkylbenzene sulfonate) is added to 100 to 150 ml of the electrolyte solution, and 2 to 20 mg of a measurement sample is added thereto. Disperse the electrolyte in which the sample is suspended with an ultrasonic disperser for 1 to 3 minutes, and use a Coulter Counter Multisizer (manufactured by Coulter Inc.) to measure the volume using an aperture appropriately adjusted to a toner size such as 17 μm or 100 μm. As a particle size distribution of 0.3 to 40 μm. The number average particle diameter and the weight average particle diameter measured under these conditions are determined by computer processing, and the cumulative ratio of the number average particle diameter less than or equal to the ½ double diameter cumulative distribution is calculated from the number-based particle size distribution. Find the cumulative value below the double diameter cumulative distribution. Similarly, a cumulative ratio equal to or greater than the double diameter cumulative distribution of the weight average particle diameter is calculated from the volume-based particle size distribution, and a cumulative value equal to or greater than the double diameter cumulative distribution is obtained.
[0057]
Further, the toner preferably has an average circularity of 0.960 or more.
[0058]
For toners with an average circularity of less than 0.960, the change in developer fluidity tends to be large, carrier recovery tends to be unstable, and the amount of charge tends to change in a long-term durability test. . A toner having an average circularity within the above range has high transfer efficiency onto paper, and even if the amount of toner put on the photoreceptor is small, the same density as the conventional toner can be obtained, which is advantageous in terms of cost. It is. In addition, since it is easy to roll on the carrier and the packing density of the developer is high and stable, there are many opportunities for contact with the carrier, and it is easy to always maintain a stable charge. This is preferable because it is performed stably.
[0059]
Further, the average circularity in the present invention is used as an index for quantitatively expressing the shape of the particles. In the present invention, the average circularity is measured using a flow type particle image analyzer “FPIA-1000” manufactured by Toa Medical Electronics. The circularity (ai) of the measured particles is obtained by the following formula (3), and the total roundness of all the particles measured as shown by the following formula (4) is expressed as the total number of particles (m). The divided value is defined as the average circularity (am).
[0060]
[Expression 1]
Circularity (ai) = L₀/ L Formula (3)
(Where L₀Indicates the perimeter of a circle having the same projected area as the toner particle image, and L indicates the perimeter of the projected image of the toner particles. )
[0061]
[Expression 2]

[0062]
In addition, "FPIA-1000" which is a measuring apparatus used in the present invention calculates the circularity of each particle, and then calculates the average circularity, and the circularity of 0.40 to 1.. A calculation method is used in which 00 is divided into 61 classes, and the average circularity is calculated using the center value and frequency of the division points. However, there is very little error between each value of the average circularity calculated by this calculation method and each value of the average circularity calculated by the above-described calculation formula that directly uses the circularity of each particle. In the present invention, the calculation formula directly using the circularity of each particle described above is used for reasons of data handling such as shortening the calculation time and simplifying the calculation formula. Such a calculation method that is partially changed using the concept may be used.
[0063]
The measurement procedure is as follows.
[0064]
A dispersion is prepared by dispersing about 5 mg of magnetic toner in 10 ml of water in which about 0.1 mg of a surfactant is dissolved, and the dispersion is irradiated with ultrasonic waves (20 kHz, 50 W) for 5 minutes. Measurement is performed with the above apparatus at 5000 to 20,000 / μl, and the average circularity and mode circularity of a particle group having a circle-equivalent diameter of 3 μm or more are obtained.
[0065]
The average circularity in the present invention is an index of the degree of unevenness of the toner, and is 1.000 when the magnetic toner is a perfect sphere, and the average circularity becomes smaller as the toner surface shape becomes more complicated.
[0066]
As the binder resin used for the toner, the following binder resins can be used.
[0067]
For example, styrene such as polystyrene, poly-p-chlorostyrene, and polyvinyltoluene, and homopolymers of substituted styrene; styrene-p-chlorostyrene copolymer, styrene-vinyltoluene copolymer, styrene-vinylnaphthalene copolymer , Styrene-acrylic acid ester copolymer, styrene-methacrylic acid ester copolymer, styrene-α-chloromethyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-vinyl methyl ether copolymer, styrene-vinyl Styrene copolymers such as ethyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-acrylonitrile-indene copolymer; polyvinyl chloride; phenol Resin; Naturally modified Natural resin modified maleic acid resin; acrylic resin; methacrylic resin; polyvinyl acetate; silicone resin; polyester resin; polyurethane; polyamide resin; furan resin; Petroleum-based resins can be used. Preferable binder resins include styrene copolymers or polyester resins. A cross-linked styrene resin is also a preferable binder resin.
[0068]
A styrene monomer and a styrene comonomer are used as the polymerizable monomer of the styrene copolymer. Examples of the comonomer for the styrene monomer include acrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, and dodecyl acrylate. , Having double bonds such as octyl acrylate, 2-ethylhexyl acrylate, phenyl acrylate, methacrylic acid, methyl methacrylate, ethyl methacrylate, butyl methacrylate, octyl methacrylate, acrylonitrile, methacrylonitrile, acrylamide Monocarboxylic acids or substituted products thereof; for example, dicarboxylic acids having a double bond such as maleic acid, butyl maleate, methyl maleate, dimethyl maleate and substituted products thereof; for example, vinyl chloride, vinyl acetate, Vinyl esters such as vinyl benzoate; ethylene-based olefins such as ethylene, propylene and butylene; vinyl ketones such as vinyl methyl ketone and vinyl hexyl ketone; for example vinyl methyl ether and vinyl ethyl ether Vinyl monomers such as vinyl ethers such as vinyl isobutyl ether are used alone or in combination.
[0069]
In the present invention, the number average molecular weight of the THF-soluble component of the toner binder resin is preferably 3,000 to 1,000,000 (more preferably 6,000 to 200,000).
[0070]
In the present invention, the THF soluble content of the toner is prepared as follows.
[0071]
The toner is extracted in advance with a toluene solvent using a Soxhlet extractor for 20 hours, and the resulting extract is dissolved in tetrahydrofuran (THF) after the toluene is distilled off with a rotary evaporator. A sample obtained by filtering the THF-soluble matter thus obtained with a solvent-resistant membrane filter having a pore size of 0.3 μm was used with 150C manufactured by Waters Co., Ltd., and the column configuration was A-801, 802, 803 manufactured by Showa Denko. , 804, 805, 806, and 807, and using a standard polystyrene resin calibration curve, the molecular weight distribution can be measured to determine the number average molecular weight of the THF soluble matter.
[0072]
The styrenic polymer or styrenic copolymer may be cross-linked, or may be a mixed resin of a cross-linked resin and a non-cross-linked resin.
[0073]
As the crosslinking agent for the binder resin, a compound having two or more polymerizable double bonds may be mainly used. For example, aromatic divinyl compounds such as divinylbenzene and divinylnaphthalene; carboxylic acid esters having two double bonds such as ethylene glycol diacrylate, ethylene glycol dimethacrylate, and 1,3-butanediol dimethacrylate; divinylaniline; And divinyl compounds such as divinyl ether, divinyl sulfide and divinyl sulfone; and compounds having three or more vinyl groups. These are used alone or as a mixture.
[0074]
As addition amount of a crosslinking agent, 0.001-10 mass parts is preferable with respect to 100 mass parts of polymerizable monomers.
[0075]
The toner may contain a charge control agent.
[0076]
The following substances are used for controlling the toner to be negatively charged. For example, organometallic compounds and chelate compounds are effective, and monoazo metal compounds, acetylacetone metal compounds, aromatic hydroxycarboxylic acids, and aromatic dicarboxylic acid metal compounds are preferably used. Further, aromatic hydroxycarboxylic acids, aromatic mono- and polycarboxylic acids and their metal salts, their anhydrides, their esters, their phenol derivatives such as bisphenol; urea derivatives; metal-containing salicylic acid compounds; Metallic naphthoic acid compounds; boron compounds; quaternary ammonium salts; calixarene; silicon compounds; styrene-acrylic acid copolymers; styrene-methacrylic acid copolymers; styrene-acrylic-sulfonic acid copolymers; and nonmetal carboxylic acid systems Compounds.
[0077]
The following substances are used to control the toner to be positively charged. For example, modified products such as nigrosine and fatty acid metal salts, guanidine compounds, imidazole compounds, quaternary ammonium salts such as tributylbenzylammonium-1-hydroxy-4-naphthosulfonate, tetrabutylammonium tetrafluoroborate, and the like Onium salts such as phosphonium salts and their lake pigments, triphenylmethane dyes and their lake pigments (as rake agents, phosphotungstic acid, phosphomolybdic acid, phosphotungsten molybdic acid, tannic acid, lauric acid, Gallic acid, ferricyanide, ferrocyanide, etc.), metal salts of higher fatty acids; diorganotin oxides such as dibutyltin oxide, dioctyltin oxide, dicyclohexyltin oxide; Over DOO, dioctyl tin borate, diorgano tin borate such as dicyclohexyl tin borate; can be used in combination singly, or two or more kinds. Among these, a charge control agent such as a nigrosine-type quaternary ammonium salt is particularly preferably used.
[0078]
These charge control agents may be used in an amount of 0.01 to 20 parts by weight, preferably 0.1 to 10 parts by weight, more preferably 0.2 to 4 parts by weight, based on 100 parts by weight of the resin component of the toner. .
[0079]
As the colorant of the toner used in the present invention, a black colorant prepared by using carbon black, a magnetic material, and the following yellow / magenta / cyan colorant is used.
[0080]
As the yellow colorant, compounds represented by condensed azo compounds, isoindolinone compounds, anthraquinone compounds, azo metal complexes, methine compounds, and allylamide compounds are used. Specifically, C.I. I. Pigment Yellow 12, 13, 14, 15, 17, 62, 74, 83, 93, 94, 95, 109, 110, 111, 128, 129, 147, 168 or 180 is preferably used. Furthermore, C.I. I. You may use together dyes, such as Solvent Yellow 93 and 162.
[0081]
As the magenta colorant, condensed azo compounds, diketopyrrolopyrrole compounds, anthraquinones, quinacridone compounds, basic dye lake compounds, naphthol compounds, benzimidazolone compounds, thioindigo compounds, and perylene compounds are used. Specifically, C.I. I. Pigment Red 2, 3, 5, 6, 7, 23, 48: 2, 48: 3, 48: 4, 57: 1, 81: 1, 144, 146, 166, 169, 177, 184, 185, 202, 206, 220, 221 or 254 is preferably used.
[0082]
As the cyan colorant, copper phthalocyanine compounds and derivatives thereof, anthraquinone compounds, basic dye lake compounds, and the like can be used. Specifically, C.I. I. Pigment Blue 1, 7, 15, 15: 1, 15: 2, 15: 3, 15: 4, 60, 62, and 66 can be particularly preferably used.
[0083]
These colorants can be used alone or mixed and further used in the form of a solid solution, and are selected from the viewpoints of hue angle, chroma, lightness, weather resistance, OHP transparency, and dispersibility in the toner. The colorant is added in an amount of 1 to 20 parts by mass with respect to 100 parts by mass of the resin.
[0084]
The toner particles preferably contain 1 to 40% by mass, preferably 2 to 30% by mass of solid wax. If the wax is less than 1% by mass, the effect of suppressing offset is small, and if it exceeds 40% by mass, the toner surface is unevenly distributed, and carrier contamination is likely to occur. Not only the change tends to be large, but also the fluidity of the carrier changes, so that the density change of the developer becomes large and the carrier recovery becomes unstable.
[0085]
As a preferred wax, in the molecular weight distribution measured by gel permeation chromatography (GPC), the weight average molecular weight (Mw) / number average molecular weight (Mn) is 1.45 or less, and the solubility parameter is 8.4-10. By using the wax No. 5, the toner has excellent fluidity, and a uniform fixed image without gloss unevenness can be obtained. Further, the heating member of the fixing device is hardly contaminated and the storage stability is hardly deteriorated. When a full color OHP having excellent light transmissivity and melting the toner is produced, a part of or all of the wax covers the heating member appropriately, and the full color OHP is formed without offset of the toner. In addition to being able to be produced and exhibiting good low-temperature fixability, it is possible to extend the life of the pressure contact member.
[0086]
Mw / Mn is more preferably 1.30 or less from the viewpoint of good transferability of toner and prevention of contamination to contact charging means for charging by contact with the photoreceptor.
[0087]
In the present invention, the molecular weight distribution of the wax is measured by GPC using a double column under the following conditions.
[0088]
(GPC measurement conditions)
Apparatus: GPC-150C (manufactured by Waters)
Column: GMH-HT 30 cm 2 series (manufactured by Tosoh Corporation)
Temperature: 135 ° C
Solvent: o-dichlorobenzene (0.1% ionol added)
Flow rate: 1.0 ml / min
Sample: 0.4 ml of 0.15% sample was injected
Measurement is performed under the above conditions, and a molecular weight calibration curve prepared from a monodisperse polyurethane standard sample is used in calculating the molecular weight of the sample. Furthermore, a weight average molecular weight and a number average molecular weight are calculated by converting to polyethylene using a conversion formula derived from the Mark-Houwink viscosity formula.
[0089]
The melting point of the wax used in the present invention is preferably 40 to 150 ° C, particularly preferably 50 to 120 ° C. When the melting point of the wax is lower than 40 ° C., the toner blocking resistance is weakened, the sleeve is easily contaminated when copying a large number of sheets, and the developer coating becomes non-uniform when the image forming speed is changed, and the image density Unevenness is likely to occur. When the melting point of the wax exceeds 150 ° C., excessive energy is required for uniform mixing with the binder resin in the toner production method by the pulverization method, and even in the toner production method by the polymerization method For this reason, there is a limit to the size of the apparatus by increasing the viscosity or the amount of compatibility, which makes it difficult to contain a large amount.
[0090]
The melting point of the wax is the temperature at the main peak value in the endothermic curve measured according to ASTM D3418-8.
[0091]
For the measurement according to ASTM D3418-8, for example, DSC-7 manufactured by Perkin Elmer is used. The temperature correction of the device detection unit uses the melting point of indium zinc, and the correction of heat uses the heat of fusion of indium. For the sample, an aluminum pan is used, and an empty pan is set as a control.
[0092]
The melt viscosity at 100 ° C. of the wax used in the present invention is preferably 1 to 50 mPa · s, more preferably a wax compound having 3 to 30 mPa · s.
[0093]
When the melt viscosity of the wax is lower than 1 mPa · s, when developing the toner using a magnetic carrier, it is easy to cause damage due to the shearing force between the toner and the magnetic carrier, and the external additive is easily buried or the toner is crushed. It tends to be difficult to always coat a stable amount of developer for various image forming speeds. When the melt viscosity of the wax exceeds 50 mPa · s, the viscosity of the dispersoid is too high when the toner is produced using the polymerization method, and it is easy to obtain a toner having a fine particle size having a uniform particle size. The toner tends to have a wide particle size distribution.
[0094]
The melt viscosity of the wax may be measured by using a cone plate rotor (PK-1) with a AKE-VT VT-500.
[0095]
Further, the wax used in the present invention has a molecular weight distribution measured by GPC having two or more peaks or one or more peaks and one or more shoulders, and in the molecular weight distribution, the weight average molecular weight ( Mw) is preferably 200 to 2,000, and the number average molecular weight (Mn) is preferably 150 to 2,000. The molecular weight distribution described above may be achieved with either a single wax or a plurality of waxes, and as a result, it has been found that crystallinity can be hindered and transparency is further improved. The method of blending two or more kinds of waxes is not particularly limited. For example, a media type disperser (ball mill, sand mill, attritor, apex mill, coball mill, handy mill) is used above the melting point of the wax to be blended. It is also possible to melt and blend, or to dissolve the wax to be blended into a polymerizable monomer and blend it with a media type disperser. At this time, pigments, charge control agents, and polymerization initiators may be used as additives.
[0096]
The wax preferably has a weight average molecular weight (Mw) of 200 to 2000 and a number average molecular weight (Mn) of 150 to 2000. More preferably, it is good that Mw is 200-1500, More preferably, it is 300-1000, Mn is 200-1500, More preferably, it is 250-1000. When the Mw of the wax is less than 200 or the Mn is less than 150, the blocking resistance of the toner may be lowered. When the Mw of the wax exceeds 2000 or the Mn exceeds 2000, the crystallinity of the wax itself is developed, and the transparency may be lowered.
[0097]
Examples of waxes that can be used in the present invention include paraffin waxes, polyolefin waxes, modified products thereof (for example, oxides and grafted products), higher fatty acids, and metal salts thereof, amide waxes, and ester systems. Wax etc. are mentioned. Among these, ester wax is particularly preferable in that a higher-quality full-color OHP image can be obtained.
[0098]
Next, a preferred method for producing a toner having an average circularity of 0.960 or more used in the present invention will be described. The toner used in the present invention can be produced using a pulverized toner production method and a polymerized toner production method, but a polymerized toner production method is preferably used.
[0099]
As a method for producing the polymerized toner, a method of obtaining a spherical toner by atomizing a molten mixture into air using a disk or a multi-fluid nozzle described in JP-B-56-13945, JP-B-36-10231, JP A method of directly producing toner using the suspension polymerization method described in JP-A-59-53856 and JP-A-59-61842, or a monomer that is soluble and insoluble in a monomer. An emulsion polymerization method represented by a dispersion polymerization method that directly produces a toner using an aqueous organic solvent or a soap-free polymerization method that produces a toner by directly polymerizing in the presence of a water-soluble polar polymerization initiator, After the production, the toner can be produced using a hetero-aggregation method in which polar particles having opposite charges are added and associated.
[0100]
Among these, polymerized toner particles obtained by a method of directly polymerizing a monomer composition containing at least a polymerizable monomer, a colorant and a wax to produce toner particles are preferable.
[0101]
In the dispersion polymerization method, the toner obtained has a very sharp particle size distribution, but the production equipment is complicated from the viewpoint of the processing of waste solvent and the flammability of the solvent due to the narrow selection of materials used and the use of organic solvents. Easy to get complicated. Therefore, a method of directly polymerizing a monomer composition containing at least a polymerizable monomer, a colorant and a wax in an aqueous medium to produce toner particles is more preferable. However, an emulsion polymerization method typified by soap-free polymerization is effective because the particle size distribution of the toner is relatively uniform. However, when the used emulsifier and initiator terminals are present on the surface of the toner particles, the environmental characteristics are easily deteriorated.
[0102]
Therefore, in the present invention, a suspension polymerization method under normal pressure or under pressure, in which a fine particle toner having a sharp particle size distribution can be obtained relatively easily, is particularly preferable. A so-called seed polymerization method in which a monomer is further adsorbed to the polymer particles once obtained and then polymerized using a polymerization initiator can also be suitably used in the present invention.
[0103]
As a preferable form of the toner used in the present invention, wax is encapsulated in an outer shell resin layer by a tomographic surface measurement method of a toner using a transmission electron microscope (TEM). From the viewpoint of fixing properties, it is necessary to include a large amount of wax in the toner, so that the wax is encapsulated in the outer shell resin layer from the viewpoint of the storage stability and fluidity of the toner. In the case where the toner is not encapsulated, carrier contamination is likely to occur, and the carrier recoverability becomes unstable.
[0104]
As a specific method for embedding the wax, the polarity of the material in the aqueous medium is set to be smaller than that of the main monomer, and a small amount of a large polarity resin or monomer is added. A toner having a so-called core-shell structure in which wax is coated with an outer shell resin can be obtained. Toner particle size distribution control and particle size control can be done by changing the type and amount of a poorly water-soluble inorganic salt or a protective colloid-dispersing agent, as well as mechanical equipment conditions such as rotor speed, number of passes, and agitation. A predetermined toner of the present invention can be obtained by controlling stirring conditions such as blade shape, container shape, solid content concentration in an aqueous solution, and the like.
[0105]
As a specific method for measuring the tomographic plane of the toner in the present invention, a cured product obtained by sufficiently dispersing the toner in a room temperature curable epoxy resin and curing it in an atmosphere at a temperature of 40 ° C. is obtained. After dyeing with ruthenium tetroxide and, if necessary, osmium tetroxide, a flaky sample is cut out using a microtome with diamond teeth, and the tomographic morphology of the toner is measured using a transmission electron microscope (TEM) . In the present invention, it is preferable to use a ruthenium tetroxide dyeing method in order to provide contrast between materials by utilizing a slight difference in crystallinity between the wax used and the resin constituting the outer shell.
[0106]
When the direct polymerization method is used in the toner manufacturing method of the present invention, the toner can be specifically manufactured by the following manufacturing method. Add monomer, wax, colorant, charge control agent, polymerization initiator and other additives to the monomer, and uniformly dissolve or disperse the monomer composition with a homogenizer, ultrasonic disperser, etc. The aqueous phase is dispersed with a normal stirrer or a stirrer such as a homomixer or a homogenizer. Preferably, granulation is performed by adjusting the stirring speed and time so that the droplets of the monomer composition have a desired toner particle size. Thereafter, stirring may be performed to such an extent that the particle state is maintained and precipitation of particles is prevented by the action of the dispersion stabilizer. Polymerization is carried out at a polymerization temperature of 40 ° C. or higher, generally 50 to 90 ° C. Further, the temperature may be raised in the latter half of the polymerization reaction, and further, in order to remove unreacted polymerizable monomers and by-products that cause odor during toner fixing, the latter half of the reaction or after the completion of the reaction. A part of the aqueous medium may be distilled off. After completion of the reaction, the produced toner particles are recovered by washing and filtration and dried. In the suspension polymerization method, it is usually preferable to use 300 to 3000 parts by weight of water as a dispersion medium with respect to 100 parts by weight of the monomer composition.
[0107]
As a polymerizable monomer for directly obtaining a toner by using a polymerization method, a styrene monomer such as styrene, o (m-, p-)-methylstyrene, m (p-)-ethylstyrene; ) Methyl acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, octyl (meth) acrylate, dodecyl (meth) acrylate, stearyl (meth) acrylate, (meth) (Meth) acrylate monomers such as behenyl acrylate, 2-ethylhexyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate; butadiene, isoprene, cyclohexene, (meta ) Diene monomers such as acrylonitrile and acrylamide are preferably used.
[0108]
Examples of polar resins used in the toner polymerization method include polymers of nitrogen-containing monomers such as dimethylaminoethyl methacrylate and diethylaminoethyl methacrylate, or a copolymer of nitrogen-containing monomers and styrene-unsaturated carboxylic acid esters. Nitrile monomers such as acrylonitrile; halogen-containing monomers such as vinyl chloride; unsaturated carboxylic acids such as acrylic acid and methacrylic acid; unsaturated dibasic acids; unsaturated dibasic acid anhydrides; A monomer polymer or a copolymer thereof and a styrene monomer; polyester; epoxy resin; More preferable examples include a copolymer of styrene and (meth) acrylic acid, a maleic acid copolymer, a saturated polyester resin, and an epoxy resin.
[0109]
Examples of the polymerization initiator include 2,2′-azobis- (2,4-dimethylvaleronitrile), 2,2′-azobisisobutyronitrile, 1,1′-azobis (cyclohexane-1-carbonitrile). ), 2,2′-azobis-4-methoxy-2,4-dimethylvaleronitrile, azo or diazo polymerization initiators such as azobisisobutyronitrile; benzoyl peroxide, methyl ethyl ketone peroxide, diisopropyl peroxycarbonate, cumene hydro Peroxide, t-butyl hydroperoxide, di-t-butyl peroxide, dicyl peroxide, 2,4-dichlorobenzoyl peroxide, lauroyl peroxide, 2,2-bis (4,4-t-butylperoxycyclohexyl) propane, tris- (T-Butylperu Sheet) such as triazine peroxide initiators; peroxide polymer initiator having a side chain; such persulfate potassium persulfate and ammonium persulfate; hydrogen peroxide, etc. are used. These can be used alone or in combination of two or more.
[0110]
The polymerization initiator is preferably added in an amount of 0.5 to 20 parts by mass with respect to 100 parts by mass of the polymerizable monomer.
[0111]
In order to control the molecular weight, a known crosslinking agent or chain transfer agent may be added, and a preferable addition amount is 0.001 to 15 parts by mass with respect to 100 parts by mass of the polymerizable monomer.
[0112]
A suitable inorganic compound or organic compound stabilizer is used for the dispersion medium used in the production of the polymerization method toner by emulsion polymerization, dispersion polymerization, suspension polymerization, seed polymerization, or polymerization method using hetero-aggregation method. It is preferable to do. Examples of inorganic compound stabilizers include tricalcium phosphate, magnesium phosphate, aluminum phosphate, zinc phosphate, calcium carbonate, magnesium carbonate, calcium hydroxide, magnesium hydroxide, aluminum hydroxide, calcium metasilicate, Examples thereof include calcium sulfate, barium sulfate, bentonite, silica, and alumina. As stabilizers for organic compounds, polyvinyl alcohol, gelatin, methylcellulose, methylhydroxypropylcellulose, ethylcellulose, sodium salt of carboxymethylcellulose, polyacrylic acid and its salts, starch, polyacrylamide, polyethylene oxide, poly (hydroxystearic acid) -G-methyl methacrylate-eu-methacrylic acid) copolymers and nonionic or ionic surfactants.
[0113]
When the emulsion polymerization method and the heteroaggregation method are used, an anionic surfactant, a cationic surfactant, a zwitterionic surfactant and a nonionic surfactant are used. These stabilizers are preferably used in an amount of 0.2 to 30 parts by mass with respect to 100 parts by mass of the polymerizable monomer.
[0114]
Among these stabilizers, when an inorganic compound is used, a commercially available one may be used as it is, but in order to obtain fine particles, the inorganic compound may be produced in a dispersion medium.
[0115]
In order to finely disperse these stabilizers, 0.001 to 0.1 parts by mass of a surfactant may be used with respect to 100 parts by mass of the polymerizable monomer. This surfactant is for promoting the stabilizing action of the dispersion stabilizer. Specific examples thereof include sodium dodecylbenzene sulfate, sodium tetradecyl sulfate, sodium pentadecyl sulfate, sodium octyl sulfate, sodium oleate, sodium laurate, potassium stearate, calcium oleate and the like.
[0116]
In the present invention, as the colorant used in the polymerization toner, it is necessary to pay attention to the polymerization inhibitory property and water phase transferability of the colorant. It is better to apply the process. In particular, dyes and carbon blacks have a polymerization inhibition property, so care must be taken when using them. A preferable method for surface-treating the dye system includes a method of polymerizing a polymerizable monomer in the presence of these dyes in advance, and the obtained colored polymer is added to the monomer system. Carbon black may be treated with a material that reacts with the surface functional groups of carbon black, such as polyorganosiloxane, in addition to the same treatment as the above dye.
[0117]
As described above, the melting point of the wax used in the present invention is preferably 40 to 150 ° C., more preferably 50 to 120 ° C., and the melting point of the toner wax is more preferably the glass transition temperature of the binder resin. The temperature difference is preferably 100 ° C. or lower, more preferably 75 ° C. or lower, and further preferably 50 ° C. or lower.
[0118]
When this temperature difference exceeds 100 ° C., the low-temperature fixability tends to decrease. Further, when this temperature difference is too close, the temperature range in which the storage stability of the toner and the high-temperature offset resistance can be compatible becomes narrow, so that the temperature is preferably 2 ° C. or more. From this, the glass transition temperature of the binder resin is preferably 40 to 90 ° C, more preferably 50 to 85 ° C.
[0119]
When the glass transition temperature of the binder resin is less than 40 ° C., the storability of the toner is lowered and the fluidity is deteriorated, and a good image tends not to be obtained. When the glass transition temperature of the binder resin exceeds 90 ° C., the low-temperature fixability is inferior, and the transparency of full color transparency is deteriorated. In particular, the halftone part is dull and a projected image with no saturation is likely to occur.
[0120]
The glass transition temperature (Tg) of the binder resin is measured by measurement according to ASTM D3418-8. For example, it is performed using DSC-7 manufactured by PerkinElmer. The temperature correction of the device detection unit uses the melting points of indium and zinc, and the correction of heat uses the heat of fusion of indium. For the sample, an aluminum pan is used, and an empty pan is set as a control.
[0121]
Next, the external additive that is externally added to the toner particles will be described.
[0122]
In the toner used in the present invention, inorganic fine particles such as silica, alumina and titanium oxide; fine powders of organic fine particles such as polytetrafluoroethylene, polyvinylidene fluoride, polymethyl methacrylate, polystyrene and silicone are externally added. Is preferred. By externally adding the above-mentioned fine powder to the toner particles, the fine powder exists between the toner and the carrier or between the toner particles, the developer fluidity is improved, and the developer life is also improved. To do. The average particle size of the fine powder is preferably 0.2 μm or less. When the number average particle diameter exceeds 0.2 μm, the effect of improving fluidity is reduced, and the image quality may be deteriorated due to defects during development and transfer. The measurement of the number average particle diameter of these fine powders will be described later.
[0123]
As the surface area of these fine powders, the specific surface area by nitrogen adsorption by the BET method is 30 m.²/ G or more, especially 5 to 400 m²Those in the range of / g are good. The addition amount of the fine powder is preferably 0.1 to 20 parts by mass with respect to 100 parts by mass of the toner particles.
[0124]
In the negatively chargeable toner particularly preferably used in the present invention, it is preferable from the viewpoint of chargeability to use at least one type of silica subjected to hydrophobic treatment. That is, since silica or titanium oxide has a higher negative chargeability than a fluidizing agent such as alumina, the adhesion to the toner particles is high, and the free external additive is reduced. For this reason, filming on the electrostatic latent image carrier and a part of the external additive that has been released tend to move to the carrier. Even in such a case, the polymerization method carrier of the present invention can suppress the adhesion of the fluidizing agent because of the surface shape with uniform surface irregularities.
[0125]
In addition, the inorganic fine particles are preferably subjected to a hydrophobic treatment in order to maintain chargeability under high humidity. An example of the hydrophobic treatment is shown below.
[0126]
A silane coupling agent is mentioned as one of the hydrophobizing agents, and the amount thereof is 1 to 40 parts by mass, preferably 2 to 35 parts by mass with respect to 100 parts by mass of the inorganic fine particles. When the amount is 1 to 40 parts by mass, moisture resistance is improved and aggregates are hardly generated.
[0127]
As a silane coupling agent used for this invention, what is shown by following General formula (5) is mentioned.
[0128]
RmSiYn Formula (5)
[In the formula, R represents an alkoxy group or a chlorine atom, m is an integer of 1 to 3, and Y represents a hydrocarbon group (for example, an alkyl group, a vinyl group, a glycidoxy group, or a methacryl group). , N is an integer of 3-1. ]
[0129]
Specifically, for example, dimethyldichlorosilane, trimethylchlorosilane, allyldimethylchlorosilane, hexamethyldisilazane, allylphenyldichlorosilane, benzyldimethylchlorosilane, vinyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, Examples thereof include vinyltriacetoxysilane, divinylchlorosilane, dimethylvinylcholorsilane and the like.
[0130]
The silane coupling agent treatment of the inorganic fine particles is a dry treatment in which the vaporized silane coupling agent is reacted with the inorganic fine particles made into a cloud by stirring, or the inorganic fine particles are dispersed in a solvent and the silane coupling agent is dropped. The treatment can be performed by a generally known method such as a wet method for reacting. The above hydrophobization treatment can be used in combination as appropriate.
[0131]
Another example of the hydrophobizing agent is silicone oil.
[0132]
As a preferable silicone oil, the viscosity at 25 ° C. is 5 to 2000 mm.²/ S is preferably used. A silicone oil having a low molecular weight and a low viscosity is not preferable because volatile matter may be generated by heat treatment, while a silicone oil having a high molecular weight and a high viscosity is difficult to perform a surface treatment operation. As the silicone oil, methyl silicone oil, dimethyl silicone oil, phenylmethyl silicone oil, chlorophenyl methyl silicone oil, alkyl-modified silicone oil, fatty acid-modified silicone oil, and polyoxyalkyl-modified silicone oil are preferable.
[0133]
The above-described silicone oil is preferably a negatively chargeable oil having the same polarity as the toner particles in order to improve the chargeability of the toner.
[0134]
A known technique is used as a method of treating the inorganic fine particles with silicone oil. For example, inorganic fine particles and silicone oil may be directly mixed using a mixer such as a Henschel mixer, or a method of spraying silicone oil onto inorganic fine particles may be used. Alternatively, it may be prepared by dissolving or dispersing silicone oil in an appropriate solvent, mixing with inorganic fine particles, and then removing the solvent.
[0135]
The silicone oil is used in an amount of 1.5 to 60 parts by mass, preferably 3.5 to 40 parts by mass, with respect to 100 parts by mass of the inorganic fine particles to be treated. When the amount is 1.5 to 60 parts by mass, the surface treatment with silicone oil can be performed uniformly, and filming and voids can be suitably prevented, and the toner chargeability is prevented from deteriorating due to moisture absorption under high humidity, and durable. It is possible to prevent a decrease in image density.
[0136]
The additive for the purpose of imparting various toner characteristics preferably has an average particle diameter of 0.005 to 0.2 μm in the toner or from the viewpoint of durability when added to the toner. The average particle diameter of the additive means the number average particle diameter obtained by observing the surface of the toner particles with an electron microscope. As additives for the purpose of imparting these characteristics, for example, the following are used.
[0137]
In addition to the inorganic fine particles and organic fine particles described above, other fluidity imparting agents include, for example, carbon black and carbon fluoride. Each of these is more preferably subjected to a hydrophobic treatment.
[0138]
Examples of the abrasive include metal oxides such as strontium titanate, cerium oxide, aluminum oxide, magnesium oxide and chromium oxide; nitrides such as silicon nitride; carbides such as silicon carbide; and calcium sulfate, barium sulfate and carbonic acid. Examples include metal salts such as calcium.
[0139]
Examples of the lubricant include fluorine resin powders such as vinylidene fluoride and polytetrafluoroethylene; and fatty acid metal salts such as zinc stearate and calcium stearate.
[0140]
Examples of the charge controllable particles or conductivity imparting particles include metal oxides such as tin oxide, titanium oxide, zinc oxide, silicon oxide and aluminum oxide; and carbon black.
[0141]
These additives are preferably used in an amount of 0.1 to 10 parts by weight, more preferably 0.1 to 5 parts by weight, based on 100 parts by weight of the toner particles. These additives may be used alone or in combination.
[0142]
The developer used in the present invention is used as a start developer by mixing the above-described magnetic carrier and toner.
[0143]
In the case of preparing a starting developer by mixing toner and a magnetic carrier, good results are obtained when the mixing ratio is 2 to 15% by mass, preferably 4 to 13% by mass, as the toner concentration in the developer. It is done. When the toner concentration is less than 2% by mass, the image density tends to be low. When the toner concentration exceeds 15% by mass, fogging and in-machine scattering are likely to occur, and the service life of the developer is likely to decrease.
[0144]
Next, an image forming apparatus provided with a developing device using the replenishment developer of the present invention will be described. FIG. 1 is a schematic configuration diagram of an electrophotographic full-color image forming apparatus equipped with a rotary rotating developing device.
[0145]
First, the surface of the electrostatic latent image carrier 1 is uniformly charged negatively by the charging device 15. Next, the exposure device 14 performs image exposure corresponding to the first color, for example, a yellow image, and an electrostatic latent image corresponding to the yellow image is formed on the surface of the electrostatic latent image carrier 1.
[0146]
The developing device 13 is of a rotational movement type. Before the leading edge of the electrostatic latent image corresponding to the yellow image reaches the developing position, the yellow developing device faces the electrostatic latent image carrier 1, and thereafter A magnetic brush rubs the electrostatic latent image to form a yellow toner image on the electrostatic latent image carrier.
[0147]
In the developing device used for the above development, for example, a developing sleeve, a supply roll, a magnet roll, a regulating member, a scraper, and the like are provided inside the developing device. FIG. 2 is a schematic configuration diagram of the developing devices 2, 3, 4, and 5 of FIG. The flow of transport until the developer in the developing device is developed will be described with reference to FIG.
[0148]
The developing sleeve 6 contains a fixed magnet and is driven to rotate while maintaining a predetermined developing interval with the peripheral surface of the electrostatic latent image carrier 1. The developing sleeve 6 and the electrostatic latent image carrier 1 may be in contact with each other. The regulating member 7 is rigid and magnetic, and is pressed against the developing sleeve 6 with a predetermined load with no developer interposed therebetween, or is arranged with a predetermined gap between the developing member 6 and the developing member 6. And so on. The pair of 10 and 11 has a screw structure, and transports and circulates the developer in opposite directions to sufficiently agitate and mix the toner and the carrier, and then sends the developer and developer to the developing sleeve 6 as a developer. The magnet roll 8 is composed of, for example, a four-pole magnet having equal magnetic force in which N-poles and S-poles are alternately arranged at equal intervals, or a repulsive magnetic field is formed at a portion in contact with the scraper to separate the developer. In order to facilitate the process, one pole may be missing to form five poles, and may be included while being fixed in the developing sleeve 6.
[0149]
The two developer agitating and conveying members 10 and 11 also serve as agitating members that rotate in opposite directions, and convey the replenishing toner replenished from the toner storage device 9 by the thrust of the agitating screw. The toner and the magnetic carrier are mixed to form a homogeneous two-component developer that is triboelectrically charged, and the developer is deposited on the peripheral surface of the developing sleeve 6 in layers. The developer on the surface of the developing sleeve 6 forms a uniform layer by the dual-structure regulating member 7 made of a nonmagnetic material and a magnetic material provided to face the magnetic pole of the magnet roll 8. The uniformly formed developer layer develops the latent image on the peripheral surface of the electrostatic latent image carrier 1 in the development region, and forms a toner image.
[0150]
In FIG. 1, a transfer material 12 such as a sheet or a transparent sheet is conveyed from a paper feed tray 26 or 27 by a feed roll 28 or 29 and once blocked at the front end by a registration roll 25, and then has a predetermined timing. Is sent to the transfer drum 24. The transferred transfer material 12 is electrostatically held on the transfer drum 24 by the suction device 32 and the opposing roll 30, and is conveyed to a transfer region where the transfer drum 24 and the electrostatic latent image carrier 1 face each other. Therefore, the transfer material is brought into close contact with the yellow toner image on the electrostatic latent image carrier 1, and the yellow toner image is transferred onto the transfer material 12 by the action of the transfer device 31. Prepare for the next step while holding.
[0151]
The electrostatic latent image carrier 1 after the transfer of the yellow toner is then subjected to a pre-cleaning process as necessary, and then is neutralized by a static elimination corotron, and the yellow toner remaining on the surface is scraped off by the cleaning device 18. Further, the charge remaining on the surface is removed by the charge removal device 16.
[0152]
Next, for the second color, for example, magenta image forming process, the surface of the electrostatic latent image carrier 1 is uniformly charged negatively by the charger 15, and magenta by the laser exposure device 14. Image exposure corresponding to the image is performed, and an electrostatic latent image corresponding to the magenta image is formed on the surface of the electrostatic latent image carrier 1. In addition, after the formation of the yellow toner layer is completed, the developing device 13 is switched so that the magenta developing device faces the electrostatic latent image carrier 1, and the electrostatic latent image corresponding to the magenta image is displayed. The image is developed with a magenta magnetic brush. Then, the transfer material held on the transfer drum is conveyed again to the transfer area, and magenta toner is transferred onto the yellow toner multiple times by the action of the transfer device 31.
[0153]
After the transfer of the magenta toner, the electrostatic latent image carrier 1 is then subjected to cleaning of residual toner on the surface and charge removal of the residual charge in the same manner as in the yellow image forming process, while transferring the magenta toner. The finished transfer material is prepared for the next step while being held on the transfer drum 24.
[0154]
Thereafter, as in the magenta image forming process, an image forming process for the third color, for example, cyan is performed, and finally, an image forming process for the fourth color, for example, black is performed. In the final black image forming process, the transfer material is transported differently from the processes up to the third color. That is, the transfer material after the transfer of the fourth color is separated from the transfer drum 24 by the peeling static eliminator 19 and a peeling finger (not shown) at the tip of the conveyance guide member 20, and the multiple toner image is transferred to the transfer material by the fixing device 21. Is transferred to the outside of the image forming apparatus.
[0155]
Further, after the transfer drum 24 has been separated from the transfer material, the surface of the transfer drum 24 is neutralized by the neutralization devices 22 and 33, and then the surface is cleaned by the cleaning device 23, and the next transfer material 12 is awaited.
[0156]
When the copying operation as described above is repeated, the toner in the developer stored in the developing tank 17 in the developing device of FIG. 2 is gradually consumed, and the ratio of the toner to the carrier, that is, the toner concentration is decreased. To go. This change in toner density is feedback-controlled by a toner density sensor (not shown) provided in the developing tank 17 so that the toner density always falls within an appropriate range necessary for development. By the above control, the toner is supplied from the replenishing port of the toner replenishing portion (toner storage device 9) to the developing tank 17 in the developing device.
[0157]
On the other hand, the carrier in the developer in the developing tank 17 is not consumed by the development, and is stirred together with the toner in the developing tank 17, the magnetic force of the magnet roll, and the electrostatic latent image carrier 1. The surface and the like are gradually contaminated and deteriorated due to the influence of contact with the surface. As the carrier deteriorates in this way, a predetermined charge amount cannot be imparted to the toner, resulting in a decrease in image quality. Therefore, it is necessary to replace the deteriorated carrier which is not consumed in the developing device with a new carrier. In FIG. 1, as means for replenishing a new carrier into the developing device, toner for replenishment and a predetermined amount of carrier in a toner cartridge (toner storage device 9) for replenishing toner consumed by development. Is added to each of the developing devices 2, 3, 4, and 5 from the replenishing port of the toner storage device 9. The excess developer is discharged from the developer-side developer discharge port as described below.
[0158]
Therefore, the replacement of the developer using the rotational movement in the rotating developing device 13 shown in FIG. 1 will be described with reference to FIGS. In the full-color image forming apparatus by the developing device 13 adopting the rotational movement method, the developing devices 2, 3, 4, and 5 are rotated and moved inside the developing device 13 and face the electrostatic latent image carrier 1 during development. Development is performed by rotating to a position, and when not developing, the image is rotated to a position not facing the electrostatic latent image carrier 1.
[0159]
At a position where the developing device 2 faces the electrostatic latent image carrier 1 and performs a developing operation, the developer overflowing from the developer-side developer discharge port 34 provided in the developing device 2 is communicated by a rotating operation. It moves through the pipe 36 and is discharged from a developer recovery port 35 provided on the rotation center shaft of the rotary developer switching device.
[0160]
As a developing method using the magnetic carrier of the present invention, specifically, an AC voltage is applied to the developer carrying member to form an alternating electric field in the developing region, while the magnetic brush contacts the photosensitive drum 1. It is preferable to perform development in the state where The distance between the developer carrying member (developing sleeve) 6 and the photosensitive drum 1 (the distance between S and D) is preferably 100 to 1000 μm in terms of preventing carrier adhesion and improving dot reproducibility. If it is narrower than 100 μm, the supply of the developer tends to be insufficient, the image density becomes low, and if it exceeds 1000 μm, the magnetic pole S₁The magnetic lines of force spread and the density of the magnetic brush is lowered, so that the dot reproducibility is inferior, or the force for restraining the magnetic coat carrier is weakened and the carrier adheres easily.
[0161]
The voltage between the peaks of the alternating electric field is preferably 300 to 3000 V, and the frequency is 500 to 10000 Hz, preferably 1000 to 7000 Hz, which can be appropriately selected depending on the process. In this case, the waveform of the AC bias for forming the alternating electric field includes a triangular wave, a rectangular wave, a sine wave, or a waveform with a changed duty ratio. In order to cope with the change in the formation speed of the toner image sometimes, it is preferable to perform development by applying a developing bias voltage (intermittent alternating voltage) having a discontinuous AC bias voltage to the developer carrier. . When the applied voltage is lower than 300 V, it is difficult to obtain a sufficient image density, and the fog toner in the non-image portion may not be recovered well. If the voltage exceeds 3000 V, the latent image may be disturbed via the magnetic brush, leading to a reduction in image quality.
[0162]
By using a two-component developer with well-charged toner, the anti-fogging voltage (Vback) can be lowered and the primary charge of the photoreceptor can be lowered, thus extending the life of the photoreceptor. it can. Vback is 200 V or less, more preferably 150 V or less, although it depends on the development system. The contrast potential is preferably 100 to 400 V so that a sufficient image density is obtained.
[0163]
On the other hand, when the frequency is lower than 500 Hz, although related to the process speed, when the toner in contact with the electrostatic latent image carrier is returned to the developing sleeve, sufficient vibration is not applied and fogging is likely to occur. If it exceeds 10,000 Hz, the toner cannot follow the electric field, and the image quality is likely to deteriorate.
[0164]
What is important in the developing method of the present invention is that the magnetic brush on the developing sleeve 11 contacts the photosensitive drum 1 in order to develop a sufficient image density, excellent dot reproducibility, and without magnetic carrier adhesion. The width (development contact portion) is preferably 3 to 8 mm. If the developing contact area is narrower than 3 mm, it is difficult to satisfactorily satisfy the sufficient image density and dot reproducibility. If the developing contact area is larger than 8 mm, developer packing occurs and the operation of the machine is stopped. It becomes difficult to sufficiently suppress adhesion. As a method for adjusting the developing contact portion, the contact width is adjusted by adjusting the distance between the regulating blade 7 and the developing sleeve 6 or by adjusting the distance between the developing sleeve 6 and the photosensitive drum 1 (distance between SD). There is a method of appropriately adjusting.
[0165]
The structure of the photoreceptor may be the same as that of the photoreceptor used in the image forming apparatus. For example, a conductive layer, an undercoat layer, a charge generation layer, and a charge transport layer are sequentially formed on a conductive substrate such as aluminum or SUS. And a photoreceptor having a structure in which a charge injection layer is provided if necessary.
[0166]
The conductive layer, undercoat layer, charge generation layer, and charge transport layer may be those usually used for a photoreceptor.
[0167]
For example, a charge injection layer or a protective layer may be used as the outermost surface layer of the photoreceptor.
[0168]
In addition to the improvement of the initial image quality, the use of the replenishment carrier of the present invention reduces the share of the developer in the developing device, and even when copying a large number of sheets, spent toner or external additives on the carrier. Therefore, even with a small amount of replenishment carrier, the effects of the present invention with little deterioration in image quality can be sufficiently exhibited.
[0169]
The image forming method of the present invention will be further described with reference to the drawings.
[0170]
In FIG. 5, a charging magnetic brush made of magnetic particles 123 is formed on the surface of the conveying sleeve 122 by the magnetic force of the magnet roller 112, and this magnetic brush is formed on the surface of an electrophotographic photosensitive member (hereinafter referred to as “photosensitive member”) 101. To charge the photoconductor 101. A charging bias is applied to the transport sleeve 111 by a bias applying means (not shown). A digital electrostatic latent image is formed by irradiating the charged photosensitive member 101 with a laser beam 124 by an exposure device (not shown). The electrostatic latent image formed on the photosensitive member 101 includes a magnet roller 112, and the toner 119a in the developer 119 carried on the developing sleeve 111, to which a developing bias is applied by a bias applying device (not shown), Developed.
[0171]
The developing device 104 includes a partition 117 and a developer chamber R.₁, Stirring chamber R₂The developer conveying screws 113 and 114 are installed respectively. Stir chamber R₂Above the toner storage chamber R containing the replenishment toner 118._ThreeIs installed, storage room R_ThreeA toner replenishing port 120 is provided in the lower part of.
[0172]
The developer conveying screw 113 rotates to cause the developer chamber R to rotate.₁The developer inside is stirred and conveyed in one direction along the longitudinal direction of the developing sleeve 111. The partition wall 1117 is provided with openings (not shown) on the front side and the back side of the drawing, and the developer chamber R is formed by a screw 113.₁The developer conveyed to one side of the agitation chamber R passes through the opening of the partition wall 117 on one side of the developer chamber.₂To the developer conveying screw 114. The direction of rotation of the screw 114 is opposite to that of the screw 113, and the stirring chamber R₂Inside developer, developer chamber R₁Developer and toner storage chamber R delivered from_ThreeWhile stirring and mixing the toner replenished from the stirring chamber R in the direction opposite to the screw 113₂The developer chamber R is conveyed through the other opening of the partition wall 117.₁To send.
[0173]
In order to develop the electrostatic latent image formed on the photoreceptor 1, a developer chamber R₁The developer 119 inside is pumped up by the magnetic force of the magnet roller 112 and is carried on the surface of the developing sleeve 111. The developer carried on the developing sleeve 111 is transported to a regulating blade 115 as the developing sleeve 111 rotates, and after being regulated to a developer thin layer having an appropriate layer thickness, the developing sleeve 111, the photoconductor 101, and the like. Reaches the opposite development area. There is a magnetic pole (development pole) N at a position corresponding to the development area of the magnet roller 112.₁Is located at the development pole N₁Forms a developing magnetic field in the developing area, and the developer grows up by this developing magnetic field, and a magnetic brush of the developer is generated in the developing area. Then, the magnetic brush comes into contact with the photosensitive member 101, and the toner adhering to the magnetic brush and the toner adhering to the surface of the developing sleeve 111 are transferred to the electrostatic latent image area on the photosensitive member 101 by the reversal development method. Transfer and adhere, and the electrostatic latent image is developed to form a toner image.
[0174]
The developer that has passed through the developing region is returned to the developing device 104 as the developing sleeve 111 rotates, and is peeled off from the developing sleeve 111 by the screw 113, thereby developing chamber R₁And stirring chamber R₂It falls inside and is collected.
[0175]
When the T / C ratio of the developer 119 in the developing device 104 (mixing ratio of toner and carrier, that is, the toner concentration in the developer) is reduced by the above development, the replenishment developer storage chamber R_ThreeThe amount of the replenishment developer 118 from the amount consumed in the development is equal to the amount of the stirring chamber R₂The carrier that has been replenished and increased more than necessary is removed as a deteriorated developer mixed with toner from the discharge screw 129 to the outside, and the T / C of the developer 119 in the developing device 104 and the carrier amount are a predetermined amount. To be kept. To detect the T / C ratio of the developer 119 in the container 104, a toner concentration detection sensor 128 that measures a change in the magnetic permeability of the developer using the inductance of the coil is used. The toner concentration detection sensor has a coil (not shown) therein.
[0176]
The regulating blade 115 disposed below the developing sleeve 111 and regulating the layer thickness of the developer 119 on the developing sleeve 111 is a nonmagnetic blade 115 made of a nonmagnetic material such as aluminum or SUS316. The distance between the end portion and the surface of the developing sleeve 111 is 150 to 800 μm, preferably 250 to 700 μm. If this distance is less than 150 μm, the magnetic carrier aggregates and clogs in the meantime, and the developer layer is likely to be uneven, and it is difficult to apply the developer necessary for good development, and development with low unevenness in density is difficult. An image is easily formed. In order to prevent non-uniform application (so-called blade clogging) due to unnecessary particles mixed in the developer, this distance is preferably 150 μm or more. If it is larger than 800 μm, the amount of developer applied onto the developing sleeve 111 increases, and it is difficult to regulate the predetermined developer layer thickness, and the magnetic carrier particles adhere to the photoconductor 101 and the developer is circulated and regulated. Development regulation by the blade 115 is weakened, and toner tribo is lowered and fogging easily occurs.
[0177]
Even when the developing sleeve 111 is rotationally driven in the direction of the arrow, the magnetic carrier particle layer moves slowly as it moves away from the sleeve surface due to a balance between the restraining force based on the magnetic force / gravity and the conveying force in the moving direction of the developing sleeve 111. Become. It falls under the influence of gravity.
[0178]
Further, the developed toner image is transferred onto a transfer material (recording material) 125 being conveyed by a transfer blade 127 which is a transfer means to which a transfer bias is applied by a bias applying means 126 and transferred onto the transfer material. The toner image thus fixed is fixed on the transfer material by a fixing device (not shown). In the transfer step, the transfer residual toner that is not transferred to the transfer material and remains on the photosensitive member 101 is adjusted in charge in the charging step and collected during development.
[0179]
FIG. 6 is a schematic view in which the image forming method of the present invention is applied to a full-color image forming apparatus. Also, the full-color image forming apparatus in FIG. 6 does not have an independent cleaning unit for collecting and storing the transfer residual toner remaining on the photosensitive member, but after the developing unit transfers the toner image onto the transfer material. A development simultaneous cleaning method for collecting toner remaining on the image carrier is performed.
[0180]
The carrier increased by the carrier contained in the replenishment developer overflows the capacity UP and is taken into the developer collection auger and conveyed to the replenishment developer container or another collection container.
[0181]
The full-color image forming apparatus main body is provided with a first image forming unit Pa, a second image forming unit Pb, a third image forming unit Pc, and a fourth image forming unit Pd. It is formed on a transfer material through development and transfer processes.
[0182]
The configuration of each image forming unit provided in the image forming apparatus will be described by taking the first image forming unit Pa as an example.
[0183]
The first image forming unit Pa includes a photoreceptor 61a having a diameter of 30 mm as an electrostatic latent image carrier, and the photoreceptor 61a is rotationally moved in the direction of arrow a. The primary charger 62a as a charging means is disposed so that a charging magnetic brush formed on the surface of a sleeve having a diameter of 16 mm contacts the surface of the photoreceptor 61a. The laser beam 67a is irradiated by an exposure device (not shown) to form an electrostatic latent image on the photoreceptor 61a whose surface is uniformly charged by the primary charger 62a. A developing device 63a as developing means for developing the electrostatic latent image carried on the photoreceptor 61a to form a color toner image holds color toner. The transfer blade 64a as a transfer means transfers the color toner image formed on the surface of the photoreceptor 61a onto the surface of the transfer material (recording material) conveyed by the belt-like transfer material carrier 68. The transfer blade 64 a is in contact with the back surface of the transfer material carrier 68 and can apply a transfer bias.
[0184]
The first image forming unit Pa first uniformly charges the photosensitive member 61a by the primary charger 62a, then forms an electrostatic latent image on the photosensitive member by the exposure device 67a, and colorizes the electrostatic latent image by the developing device 63a. Development is performed using toner, and the developed toner image is applied to the back side of a belt-shaped transfer material carrier 68 that carries and conveys the transfer material at the first transfer portion (contact position between the photosensitive member and the transfer material). Transfer is performed on the surface of the transfer material by applying a transfer bias from the transfer blade 64a in contact therewith.
[0185]
When the toner is consumed by the development and the T / C ratio decreases, the decrease is detected by the toner concentration detection sensor 85 that measures the change in the magnetic permeability of the developer using the inductance of the coil, and the amount of consumed toner is calculated. Accordingly, the toner is supplied from the supply toner container 65a. The toner concentration detection sensor 85 has a coil (not shown) inside.
[0186]
This image forming apparatus has the same configuration as that of the first image forming unit Pa, and the second image forming unit Pb, the third image forming unit Pc, and the fourth image forming unit having different color toner colors held in the developing device. The image forming unit Pd is provided with four image forming units. For example, yellow toner is used for the first image forming unit Pa, magenta toner is used for the second image forming unit Pb, cyan toner is used for the third image forming unit Pc, and black toner is used for the fourth image forming unit Pd. The transfer of each color toner onto the transfer material is sequentially performed at the transfer portion of each image forming unit. In this step, the color toners are superimposed on each other by moving the transfer material once on the same transfer material while aligning the registration. When the transfer is completed, the transfer material is separated from the transfer material carrier 68 by the separation charger 69. Then, it is sent to the fixing device 70 by a conveying means such as a conveying belt, and a final full-color image is obtained by only one fixing.
[0187]
The fixing device 70 includes a pair of a fixing roller 71 having a diameter of 40 mm and a pressure roller 72 having a diameter of 30 mm. The fixing roller 71 includes heating means 75 and 76 therein.
[0188]
The unfixed color toner image transferred onto the transfer material passes through the pressure contact portion between the fixing roller 71 and the pressure roller 72 of the fixing device 70 and is fixed onto the transfer material by the action of heat and pressure. The
[0189]
In FIG. 6, a transfer material carrier 68 is an endless belt-like member, and this belt-like member is moved in the direction of arrow e by 80 drive rollers. In addition, a transfer belt cleaning device 79 and a belt driven roller 81 have a belt static eliminator 82, and the pair of registration rollers 83 are for conveying the transfer material in the transfer material holder to the transfer material carrier 68. .
[0190]
As the transfer means, in place of the transfer blade that contacts the back side of the transfer material carrier, contact transfer means that can contact the back side of the transfer material carrier and directly apply the transfer bias, such as a roller-like transfer roller, can be used. It is possible to use.
[0191]
Further, a non-contact transfer unit that performs transfer by applying a transfer bias from a corona charger arranged in a non-contact manner on the back side of a transfer material carrier that is generally used instead of the contact transfer unit described above. It is also possible to use.
[0192]
However, it is more preferable to use the contact transfer means in that the amount of ozone generated when the transfer bias is applied can be controlled.
[0193]
【Example】
EXAMPLES Hereinafter, although this invention is demonstrated concretely using an Example, this invention is not limited to these.
[0194]
<1> Production of toner:
<Manufacture of toner 1>
To 710 parts by mass of ion-exchanged water, 0.1M-Na_ThreePO_FourAfter 450 parts by mass of the aqueous solution was added and heated to 60 ° C., the mixture was stirred at 13000 rpm using a TK homomixer (manufactured by Tokushu Kika Kogyo Co., Ltd.). To this, 1.0M-CaCl₂68 parts by mass of the aqueous solution was gradually added to obtain an aqueous medium having a pH of 6.2 containing a calcium phosphate compound.
[0195]
on the other hand,
・ 166 parts by mass of styrene
・ 34 parts by mass of n-butyl acrylate
・ Copper phthalocyanine pigment 10 parts by mass
・ 1.5 parts by mass of di-t-butylsalicylate aluminum compound
・ 10 parts by mass of amorphous polyester
・ Monoester wax 20 parts by mass
(Mw: 500, Mn: 400, Mw / Mn: 1.25)
The above material is sufficiently finely dispersed with a media disperser at room temperature, the media is separated, heated to 60 ° C., charged into the above TK homomixer (manufactured by Tokushu Kika Kogyo), and 13000 rpm And uniformly dissolved and dispersed. Into this, 10 g of a polymerization initiator 2,2′-azobis (2,4-dimethylvaleronitrile) was dissolved to prepare a polymerizable monomer composition.
[0196]
A polymerizable monomer composition is put into the aqueous medium, and the temperature is 60 ° C., N₂Under an atmosphere, the mixture was stirred at 11000 rpm for 6 minutes with a CLEAR mixer (manufactured by M Technique Co., Ltd.) to granulate the polymerizable monomer composition. Thereafter, while stirring the aqueous medium with a paddle stirring blade, the temperature was raised to 80 ° C., and the polymerization reaction was carried out for 5 hours while maintaining the pH at 6.2.
[0197]
After the completion of the polymerization reaction, the mixture was cooled and hydrochloric acid was added to adjust the pH to 2 to dissolve the calcium phosphate compound, followed by filtration, washing with water, drying, and classification to obtain polymer particles (toner particles).
[0198]
The following two types of external additives are externally added to 100 parts by mass of the obtained polymer particles (toner particles), and after the external addition, coarse particles are removed with a 300 mesh (aperture 53 μm) sieve to obtain a negative chargeability. Of cyan toner 1 was obtained. The weight average particle diameter of cyan toner 1 was 7.5 μm, the average circularity was 0.978, and the number of toner particles having a particle diameter of 2 μm or less was 8.3% by number.
[0199]
・ First external additive (hydrophobic silica fine powder 0.6 parts by mass)
Hydrophobic treatment with 10 parts by mass of hexamethyldisilazane in a gas phase with respect to 100 parts by mass of silica fine powder, and a BET specific surface area of 40 m²/ G, and the number average particle diameter is 30 nm.
[0200]
・ Second external additive (0.7 parts by mass of hydrophobic titanium oxide fine powder)
Hydrophobized with 10 parts by mass of n-octyltrimethoxysilane in an aqueous medium to 100 parts by mass of fine titanium oxide powder, with a BET specific surface area of 95 m²/ G, and the number average particle diameter is 35 nm.
[0201]
<Manufacture of toner 2>
A negatively chargeable cyan toner 2 was obtained in the same manner as in Production Example of Toner 1 except that an emulsifier was used in addition to the calcium phosphate compound. The weight average particle diameter of the cyan toner 2 was 2.8 μm, the average circularity was 0.982, and 38.6% by number of toner particles were 2 μm or less.
[0202]
<Manufacture of toner 3>
A negatively chargeable cyan toner 3 was obtained in the same manner as in the production example of toner 1 except that the amount of calcium phosphate compound was 2/3. The weight average particle size of the cyan toner 3 was 10.5 μm, the average circularity was 0.968, and the toner particles having a size of 2 μm or less were 7.5% by number.
[0203]
<Manufacture of toner 4>
A negatively chargeable cyan toner 4 was obtained in the same manner as in the production example of toner 1 except that monoester wax was not used. The weight average particle size of cyan toner 4 was 7.1 μm, the average circularity was 0.975, and the number of toner particles of 2 μm or less was 7.9% by number.
[0204]
<Manufacture of toner 5>
A negatively chargeable cyan toner 5 was obtained in the same manner as in the production example of toner 1 except that 85 parts by mass of monoester wax was used. The weight average particle diameter of the cyan toner 5 was 8.1 μm, the average circularity was 0.962, and 15.4% by number of toner particles were 2 μm or less.
[0205]
<Manufacture of toner 6>
・ Terephthalic acid / fumaric acid / trimellitic anhydride / propylene oxide
100 parts by mass of a polyester resin comprising a derivative of addition bisphenol A
・ Copper phthalocyanine pigment 5 parts by mass
・ 2 parts by mass of aluminum compound of di-t-butylsalicylic acid
The above materials are sufficiently premixed with a Henschel mixer, melt-kneaded with a twin-screw extrusion kneader, cooled and roughly crushed to about 1 to 2 mm using a hammer mill, and then finely pulverized with an air jet fine pulverizer. Crushed. Further, the obtained finely pulverized product was classified to obtain negative triboelectrically chargeable cyan toner particles having a weight average particle diameter of 5.8 μm.
[0206]
In the same manner as in the production of cyan toner 1, two kinds of external additives were externally added to the obtained cyan toner particles to prepare negatively chargeable cyan toner 6. The cyan toner 6 had a weight average particle diameter of 5.8 μm, an average circularity of 0.954, and 26.8% by number of toner particles of 2 μm or less.
[0207]
<Manufacture of toner 7>
Magenta polymer particles (toner particles) were obtained in the same manner as in the production of the toner 1 except that 10 parts by mass of a quinacridone pigment was used instead of the copper phthalocyanine pigment. In the same manner as in the production of the toner 1, two kinds of external additives were externally added to the obtained polymer particles to prepare a negatively chargeable magenta toner 7. The magenta toner 7 had a weight average particle diameter of 7.6 μm, an average circularity of 0.973, and 8.8% by number of toner particles having a particle diameter of 2 μm or less.
[0208]
<Manufacture of toner 8>
Instead of copper phthalocyanine pigment, C.I. I. Yellow polymer particles (toner particles) were obtained in the same manner as in the production of the toner 1 except that 10 parts by mass of Pigment Yellow 17 was used. An external additive was externally added to the obtained polymer particles in the same manner as in the production of the toner 1 to prepare a negatively charged yellow toner 8. The yellow toner 8 had a weight average particle diameter of 7.7 μm, an average circularity of 0.973, and 10.1% by number of toner particles having a particle size of 2 μm or less.
[0209]
<Manufacture of toner 9>
Black polymer particles (toner particles) were obtained in the same manner as in the production of the toner 1 except that 12 parts by mass of carbon black was used instead of the copper phthalocyanine pigment. An external additive was externally added to the obtained polymer particles in the same manner as in the production of the toner 1 to prepare a negatively charged black toner 9. The black toner had a weight average particle diameter of 7.2 μm, an average circularity of 0.977, and 7.9% by number of toner particles having a particle size of 2 μm or less.
[0210]
<2> Production of magnetic carrier:
<Manufacture of magnetic carrier 1>
・ Phenol (hydroxybenzene) 50 parts by mass
・ 80 parts by mass of 37% by weight formalin aqueous solution
・ 50 parts by weight of water
・ Surface treatment with silane coupling agent
320 parts by mass of magnetite fine particles
(50% particle size 0.25 μm, volume resistivity 3 × 10^FiveΩcm)
・ Surface treatment with silane coupling agent
α-Fe₂O_Three80 parts by mass of fine particles
(50% particle size 0.35 μm, volume resistivity 6 × 10⁹Ωcm)
・ 15 mass parts of 25 mass% ammonia water
The above materials were put into a four-necked flask, heated to 85 ° C. for 50 minutes while stirring and mixed, and reacted and cured for 120 minutes. After cooling to 30 ° C. and adding 500 parts by mass of water, the supernatant was removed, the precipitate was washed with water, and air-dried. Next, this was dried under reduced pressure (665 Pa = 5 mmHg) at 160 ° C. for 24 hours to obtain a magnetic carrier core (A) having a phenol resin as a binder resin.
[0211]
A 3% by mass methanol solution of γ-aminopropyltrimethoxysilane represented by the following general formula (6) was applied to the surface of the obtained magnetic carrier core (A).
[0212]
[Chemical 1]

[0213]
The surface of the magnetic carrier core (A) was treated with 0.12% by mass γ-aminopropyltrimethoxysilane. During coating, methanol was volatilized while coating while applying a shear stress to the magnetic carrier core (A) continuously.
[0214]
On the surface of the magnetic carrier core (A)
[0215]
[Chemical 2]

Was confirmed to exist.
[0216]
While stirring the magnetic carrier core (A) treated with the silane coupling agent in the processing machine at 50 ° C., the silicone resin SR2410 (manufactured by Toray Dow Corning Co., Ltd.) is made 20% as the silicone resin solid content. After diluting with toluene, it was added under reduced pressure to coat 0.5% by mass of resin.
[0217]
Thereafter, the toluene was volatilized while stirring in a nitrogen gas atmosphere for 2 hours, and then heat treatment was performed at 140 ° C. for 2 hours in a nitrogen gas atmosphere to loosen the agglomeration, and then 200 mesh (75 μm openings). The above coarse particles were removed to obtain a magnetic carrier 1.
[0218]
The obtained magnetic carrier 1 has a 50% particle size of 35 μm and a volume resistance of 8 × 10.¹³Saturation magnetization at Ωcm, 79.6 kA / m (1000 oersted) is 44 Am²/ Kg and residual magnetization is 5.1 Am²/ Kg, the true specific gravity is 3.70, and the bulk density is 1.86 g / cm.^ThreeMet.
[0219]
<Manufacture of magnetic carrier 2>
In the production of the magnetic carrier 1, a 50% particle size of 38 μm and a volume resistance of 5 × 10 are similarly used except that a ferrite core having a Bi—Ni—Zn—Fe composition is used instead of the magnetic carrier core (A).¹¹Ωcm, saturation magnetization 66 Am²/ Kg, residual magnetization 2.5Am²/ Kg, true specific gravity 4.71, bulk density 2.35g / cm^ThreeMagnetic carrier 2 was obtained.
[0220]
<Manufacture of magnetic carrier 3>
・ Terephthalic acid trimellitic anhydride / propylene oxide
100 parts by mass of a polyester resin comprising a derivative of addition bisphenol A
-500 parts by mass of magnetite used in Production Example 1
-Quaternary ammonium salt compound 5 parts by mass
The above materials are sufficiently premixed with a Henschel mixer, melt-kneaded with a twin-screw extrusion kneader, cooled and roughly crushed to about 1 to 2 mm using a hammer mill, and then finely pulverized with an air jet fine pulverizer. Crushed. Further, after classifying the obtained finely pulverized product, 0.02 μm styrene / methyl methacrylate copolymer resin particles were dry-coated with a hybridizer (manufactured by Nara Machinery Co., Ltd.) to obtain a 50% particle size of 43 μm and a volume resistance of 4 × 10⁹Ωcm, saturation magnetization 52 Am²/ Kg, residual magnetization 4.5Am²/ Kg, true specific gravity 4.05, bulk density 1.66g / cm^ThreeMagnetic carrier 3 was obtained.
[0221]
<Manufacture of magnetic carrier 4>
In the production of the magnetic carrier 1, a 50% particle size was similarly obtained except that 0.02 μm styrene / methyl methacrylate copolymer resin particles were dry-coated with a hybridizer (manufactured by Nara Machinery Co., Ltd.) on the magnetic carrier core (A). 38 μm, volume resistivity 9 × 10¹²Ωcm, saturation magnetization 41 Am²/ Kg, remanent magnetization 5.2Am²/ Kg, true specific gravity 3.71, bulk density 1.83g / cm^ThreeMagnetic carrier 4 was obtained.
[0222]
<Manufacture of magnetic carrier 5>
In the production of the magnetic carrier 3, the 50% particle size is 23 μm and the volume resistance value is 1 × 10, except that the pulverization classification conditions are changed.⁹Ωcm, saturation magnetization 50 Am²/ Kg, remanent magnetization 4.6Am²/ Kg, true specific gravity 4.02, bulk density is 1.52 g / cm^ThreeMagnetic carrier 5 was obtained.
[0223]
<Manufacture of magnetic carrier 6>
In the production of the magnetic carrier 3, the 50% particle size is 53 μm and the volume resistance value is 3 × 10 5 except that the pulverization classification conditions are changed.⁹Ωcm, saturation magnetization 51 Am²/ Kg, residual magnetization 4.7Am²/ Kg, true specific gravity 4.02, bulk density 1.65g / cm^ThreeMagnetic carrier 6 was obtained.
[0224]
<3> Production of photoconductor:
<Manufacture of photoreceptor 1>
The photoreceptor was a photoreceptor using a negatively charged organic photoconductive material, and five functional layers were provided on an aluminum cylinder having a diameter of 30 mm.
[0225]
The first layer is a conductive layer, and is a conductive particle-dispersed resin layer having a thickness of about 20 μm, which is provided to smooth out defects of the aluminum cylinder and to prevent generation of amore due to reflection of laser exposure.
[0226]
The second layer is a positive charge injection preventing layer (undercoat layer), and serves to prevent the positive charge injected from the aluminum substrate from canceling the negative charge charged on the surface of the photoreceptor, and 6-66-610. 10 with 12-nylon and methoxymethylated nylon⁶This is a medium resistance layer having a thickness of about 1 μm, the resistance of which is adjusted to about Ω · cm.
[0227]
The third layer is a charge generation layer, which is a layer having a thickness of about 0.3 μm in which a disazo pigment is dispersed in a resin, and generates positive and negative charge pairs upon receiving laser exposure.
[0228]
The fourth layer is a charge transport layer, which is obtained by dispersing hydrazone in a polycarbonate resin, and is a P-type semiconductor. Accordingly, negative charges charged on the surface of the photoreceptor cannot move through this layer, and only positive charges generated in the charge generation layer can be transported to the surface of the photoreceptor.
[0229]
The fifth layer is a charge injection layer and is made of SnO on a photocurable acrylic resin.₂Ultrafine particles, and further, tetrafluoroethylene resin particles having a particle diameter of about 0.25 μm are dispersed in order to increase the contact time between the charging member and the photosensitive member to perform uniform charging. Specifically, an oxygen-deficient SnO with a reduced resistance particle size of about 0.03 μm₂The particles are dispersed in an amount of 120% by mass, further 20% by mass of tetrafluoroethylene resin particles and 1.0% by mass of a dispersant.
[0230]
Thus, the volume resistance value of the surface layer of the photoreceptor 1 is 5 × 10 in the case of the charge transport layer alone.¹⁵8x10 compared to Ωcm¹¹It decreased to Ωcm.
[0231]
<4> Production of magnetic particles used for the charging member:
<Production of magnetic particles a>
10 parts by mass of MgO, 10 parts by mass of MnO, Fe₂O_ThreeAfter adding 80 parts by mass of each of the particles, water was added, mixed, granulated, fired at 1300 ° C., adjusted in particle size, and then ferrite core material having an average particle size of 22 μm (saturated magnetization 63 Am).²/ Kg).
[0232]
To this ferrite core material, 10 parts by mass of isopropoxy triisostearoyl titanate mixed with 99 parts by mass of toluene / 1 part by mass of water was subjected to a surface treatment so as to be 0.1 part by mass, and 50% particle size Is 25.5 μm and the volume resistivity is 7 × 10⁷A magnetic particle a of Ωcm was obtained.
[0233]
[Example 1]
The magnetic carrier 1 (92 parts by mass) obtained above and cyan toner 1 (8 parts by mass) were mixed with a V-type mixer to obtain a starting cyan developer 1.
[0234]
On the other hand, magnetic carrier 1 (1 part by mass) and cyan toner 1 (19 parts by mass) were mixed with a V-type mixer to obtain a supplementary cyan developer 1.
[0235]
Next, the developing device of a commercially available copying machine GP55 (manufactured by Canon) was modified as shown in FIG. Specifically, as the developing sleeve, a SUS sleeve having a diameter of 16 mm and having a surface shape adjusted to a surface roughness Rz = 12.1 μm by sandblasting was used.
[0236]
As the charging member, magnetic particles a are used by using the magnetic brush charger shown in FIG. 5 and rotated at 100% in the opposite direction with respect to the contact portion of the photosensitive member, and a DC / AC electric field (−700 V, 1 .5 kHz / 1.2 kVpp) is applied in a superimposed manner to charge the photoreceptor. Further, the cleaning unit is removed, the development contrast is set to 250 V, the reversal contrast with fog is set to −180 V, the development bias having the non-continuous AC voltage of FIG. Both the heating roller and the pressure roller were changed to a roller whose surface layer was covered with 1.2 μm of PFA (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer), and the oil coating mechanism was removed.
[0237]
Using an original document with an image area of 35%, 23 ° C./60% (hereinafter also referred to as “N / N”), 23 ° C./5% (hereinafter also referred to as “N / L”), 32.5 In each environment of ℃ / 90% (hereinafter also referred to as “H / H”), a paper passing test was conducted at an image forming speed of 120 mm / sec using CLC 80 g paper (manufactured by Canon Sales Co., Ltd.). Evaluation was based on the method.
[0238]
The results are shown in Table 1. As can be seen from Table 1, good results were obtained.
[0239]
[Evaluation methods and standards]
(1) Image density
The image density was measured by using a Macbeth Densitometer RD918 type (Macbeth Densitometer RD918manufactured by Mcbeth Co.) equipped with an SPI filter. It was measured as the relative concentration of the central 5-point average.
[0240]
(2) Halftone reproducibility
Using the original image density of 0.3, the relative density was measured in the same manner as in (1).
A: 0.3 to 0.4
○: 0.25 to less than 0.3
Δ: 0.20 to less than 0.25
X: Less than 0.2
[0241]
(3) fog
The average reflectance Dr (%) of plain paper before image printing was measured by a reflectometer (“REFLECTOMETER MODEL TC-6DS” manufactured by Tokyo Denshoku Co., Ltd.). On the other hand, a solid white image was drawn on plain paper, and then the reflectance Ds (%) of the solid white image was measured. The fog (%) is calculated from the following formula.
[0242]
Fog (%) = Dr (%) − Ds (%)
A: Less than 0.4%
○: 0.4 to less than 0.8%
Δ: 0.8 to less than 1.2%
×: 1.2% or more
[0243]
(4) Solid uniformity
Using the original image density of 1.5, the relative density of 5 points was measured in the same manner as in (1), and the maximum density difference was measured.
A: 0.0 to less than 0.05
○: 0.05 to less than 0.15
Δ: 0.15 to less than 0.25
X: 0.25 or more
[0244]
[Comparative Example 1]
In Example 1, the same procedure was performed except that cyan toner 2 was used. As shown in Table 1, the image density was lowered and the fogging was deteriorated under the paper passing conditions in each environment. This is presumably because the toner charge uniformity was impaired due to the small particle size of the toner.
[0245]
[Comparative Example 2]
In Example 1, the same procedure was performed except that the cyan toner 3 was used. As shown in Table 1, the halftone reproducibility was lowered under the H / H paper passing conditions, and the fog was also deteriorated. This is presumably because the toner has a large particle size, so that the chargeability of the toner is low and it is difficult to develop the latent image faithfully.
[0246]
[Comparative Example 3]
In Example 1, the same procedure was performed except that cyan toner 4 was used. As shown in Table 1, the paper stuck to the fixing roller under the conditions of passing the paper in each environment, and halftone reproducibility was lowered. Since the solid uniformity also deteriorated, the evaluation was stopped only by the initial evaluation. This is presumably because the toner has no wax and it is difficult for the toner to be offset and to pass the paper.
[0247]
[Comparative Example 4]
In Example 1, the same procedure was performed except that the cyan toner 5 was used. As shown in Table 1, the halftone reproducibility was lowered particularly under the H / H paper feeding conditions, and fog and solid uniformity were observed. Also worsened. This is presumably because the toner was spent on the carrier due to a large amount of wax, resulting in non-uniform charging.
[0248]
[Example 2]
In Example 1, the same procedure was performed except that the cyan toner 6 was used. As shown in Table 1, although the characteristics were slightly deteriorated under the paper passing conditions under H / H, there were obtained practically no problems. . This is presumably because the transferability was slightly deteriorated due to the toner non-spherical shape.
[0249]
[Comparative Example 5]
In Example 1, the same procedure was performed except that the replenishing cyan developer 2 in which the magnetic carrier 1 (1 part by mass) and the cyan toner 1 (1 part by mass) were mixed with a V-type mixer was used. As shown in Fig. 5, the evaluation was stopped because the image density decreased and the solid uniformity deteriorated at the time of 500 sheets under the paper passing conditions in each environment. This is presumably because the amount of toner in the replenishment developer is small and toner replenishment has not caught up in the solid image, resulting in unevenness.
[0250]
[Comparative Example 6]
In Example 1, the same procedure was performed except that the replenishing cyan developer 3 in which the magnetic carrier 1 (1 part by mass) and the cyan toner 1 (60 parts by mass) were mixed with a V-type mixer was used. As shown in Fig. 2, fogging deteriorated under the paper passing conditions in each environment. This is presumably because the amount of carrier in the replenishment developer is small, so that the replacement of the toner spent carrier cannot catch up and the charging of the toner becomes uneven.
[0251]
[Comparative Example 7]
In Example 1, the same procedure was performed except that the magnetic carrier 2 was used. As shown in Table 1, fogging deteriorated under the paper passing conditions in each environment. This is presumed to be because the developer is easily stressed due to the large specific gravity of the carrier, the toner spent is increased, and the toner is non-uniformly charged.
[0252]
  Example 3
  In Example 1, the magnetic carrier3As shown in Table 1, good results were obtained although the characteristics deteriorated particularly under the N / L paper feeding conditions. This is presumably because the carrier is non-spherical, the circulation in the developing machine is slightly deteriorated, and the ability to impart charge to the toner is reduced.
[0253]
[Table 1]

[0254]
Example 5
In Example 1, the same procedure was performed except that the magnetic carrier 5 was used. As shown in Table 1, although the characteristics were slightly deteriorated in each environment, good results were obtained. This is presumed that since the carrier particle size is small, circulation in the developing machine is disturbed and coating unevenness on the developing sleeve is likely to occur.
[0255]
Example 6
In Example 1, the same procedure was performed except that the magnetic carrier 6 was used. As shown in Table 1, although the characteristics were slightly deteriorated in each environment, good results were obtained. This is presumed that because the carrier particle size is large, the ability to impart charge to the toner is reduced, and toner non-uniformity tends to occur.
[0256]
Example 7
A full-color image was created using the image forming apparatus of FIG. 6 using magenta toner 7, yellow toner 8, cyan toner 1 and black toner 9 and modified CLC1000 (manufactured by Canon). Good results were obtained.
[0257]
[Table 1]

[0258]
【The invention's effect】
Since the replenishment developer according to the present invention has the above-described configuration, the chargeability of the toner is stabilized regardless of the environment, and good image quality can be obtained over a long period of time.
[Brief description of the drawings]
FIG. 1 is a diagram showing an embodiment of an image forming apparatus provided with a rotary rotation type developing device in which a replenishing developer of the present invention is used.
FIG. 2 is a diagram showing an embodiment of the developing device of FIG.
FIG. 3 is an enlarged configuration diagram for explaining the developing device of FIG. 1;
FIG. 4 is a diagram showing one embodiment of the developing device of FIG. 3;
FIG. 5 is a diagram showing an embodiment of an image forming apparatus provided with a developing device used in the cleaner-less system of the present invention.
FIG. 6 is a diagram showing one embodiment of a full-color image forming apparatus of the present invention.
7 shows a bias having a discontinuous AC electric field of a developing bias used in the image forming apparatus used in FIG.
[Explanation of symbols]
1 Photosensitive drum
2,3,4,5 Developer
6 Development sleeve
7 Regulatory blade
8 Magnet roller
9 Replenishment developer container
10,11 Developer conveying screw
12 Transfer material
13 Development device
14 Exposure means
15 Roller charging device
17 Developer tank
18, 23 Cleaning device
19, 22, 33 Static eliminator
20 Transport guide buzzer member
21 Fixing machine
24 Transfer drum
25 cashier rollers
26, 27 Paper tray
28, 29 Feed roller
30 Opposite roller
31 Transfer device
32 Adsorption device
34 Developer outlet
35 Developer recovery port
37 Primary developer storage
38 Developer recovery auger

Claims (19)

When developing the latent image on the latent image holding member using a developing machine containing a two-component developer composed of toner and carrier, the developer is supplied while supplying the developer for replenishment and discharging the excess developer. A developer for replenishment for use in a development method,
The carrier and toner are contained in parts by mass, and in a mixing ratio of 2 to 50 parts of toner with respect to 1 part of carrier,
What the carrier Ah with magnetic nanoparticles dispersed resin carrier comprising at least inorganic compound particles and a binder resin, a volume resistivity of ^{1 × 10 9 ~1 × 10 15} Ω · cm, a true specific gravity of 2.8 to is 4.2g / cm ^3,
A developer for replenishment, wherein the toner has a weight average particle diameter of 3 to 10 μm and contains 1 to 40% by mass of a solid wax.   The replenishment developer according to claim 1, wherein the binder resin of the magnetic fine particle dispersed resin carrier is a thermosetting resin.   The replenishment developer according to claim 1 or 2, wherein the thermosetting resin contains at least a phenol resin.   The supply developer according to claim 1, wherein the surface of the carrier core is further coated with another resin.   The replenishment developer according to claim 4, wherein the coating resin is a silicone resin.   The replenishing developer according to any one of claims 1 to 5, wherein the magnetic fine particle dispersed carrier has a weight average particle diameter of 15 to 60 µm. Magnetic fine particle-dispersed carrier, 1 000 / 4π (kA / m) magnetization intensity was measured under a magnetic field of (sigma ₁₀₀₀₎ of 15 to ^{65Am 2 / kg (emu / g} ), residual magnetization (.sigma.r) 0 The replenishment developer according to any one of claims 1 to 6, wherein the developer is 1 to 20 Am ² / kg.   The replenishment developer according to any one of claims 1 to 7, wherein the carrier core of the magnetic fine particle dispersed resin carrier is a polymerized carrier core.   The replenishment developer according to any one of claims 1 to 8, wherein the toner particles are polymerized toner particles. In a developing method for developing a latent image on a latent image holding member while supplying a developer for replenishment using a developing machine containing a two-component developer composed of a toner and a carrier and discharging the excess developer.
As a developer for replenishment, the carrier and the toner are contained in a mass ratio of 2 to 50 parts of the toner with respect to 1 part of the carrier,
What the carrier Ah with magnetic nanoparticles dispersed resin carrier comprising at least inorganic compound particles and a binder resin, a volume resistivity of ^{1 × 10 9 ~1 × 10 15} Ω · cm, a true specific gravity of 2.8 to is 4.2g / cm ^3,
A developing method, wherein the toner has a weight average particle diameter of 3 to 10 μm and contains 1 to 40% by mass of a solid wax.   The developing method according to claim 10, wherein the binder resin of the magnetic fine particle dispersed resin carrier is a thermosetting resin.   The developing method according to claim 11, wherein the thermosetting resin contains at least a phenol resin.   The developing method according to claim 10, wherein the surface of the carrier core is further coated with another resin.   The developing method according to claim 13, wherein the coating resin is a silicone resin.   The developing method according to claim 10, wherein the magnetic fine particle dispersed carrier has a weight average particle diameter of 25 to 50 μm. Magnetic fine particle-dispersed carrier, 1 000 Oersteds intensity of magnetization was measured under a magnetic field (sigma ₁₀₀₀₎ of 15 to ^{60Am 2 / kg (emu / g} ), residual magnetization (.sigma.r) is 0.1 to 20 Am ² / The developing method according to claim 10, wherein the developing method is kg.   The developing method according to claim 10, wherein the carrier core of the magnetic fine particle-dispersed resin carrier is a polymerized carrier core.   The developing method according to claim 10, wherein the toner particles are polymerized toner particles. The latent image on the latent image holding member is developed using a developing machine containing a two-component developer composed of toner and carrier, the replenishment developer is replenished, and the image is formed while discharging the excess developer. In the image forming method,
As a developer for replenishment, the carrier and toner are contained in a mass ratio of 2 to 50 parts of toner with respect to 1 part of carrier,
The carrier is a magnetic fine particle dispersed resin carrier having at least inorganic compound particles and a binder resin, and has a volume resistance of 1 × 10 ⁹ ~ 1x10 ¹⁵ Ω · cm and true specific gravity of 2.8 to 4.2 g / cm ^Three And
An image forming method, wherein the toner has a weight average particle diameter of 3 to 10 μm and contains 1 to 40% by mass of a solid wax.

Images