JP3979588B2 - Method for producing carrier for electrophotographic developer - Google Patents

Description

上記式中、Ｒ１は、水素原子、炭素数１〜４のアルキル基又はフェニル基、Ｒ２及びＲ３は水素基、炭素原子１〜４のアルキル基、炭素原子数１〜４のアルコキシ基、フェニル基、炭素原子数２〜４のアルケニル基、炭素原子数２〜４のアルケニルオキシ基、ヒドロキシ基、カルボキシル基、エチレンオキシド基、グリジニル基又は下記で示される基である。
【００６２】
【化２】

（上記式中、Ｒ４、Ｒ５はヒドロキシ基、カルボキシル基、炭素原子数１〜４のアルキル基、炭素原子数１〜４のアルコキシ基、炭素原子数２〜４のアルケニル基、炭素原子数２〜４のアルケニル基、炭素原子数２〜４のアルケニルオキシ基、フェニル基、フェノキシ基、ｋ、ｌ、ｍ、ｎ、O、ｐは１以上の正数を示す）。上記各置換基は未置換のもののほか、例えばアミノ基、ヒドロキシ基、カルボキシル基、メルカプト基、アルキルキ、フェニル基、エチレンオキシド基、ハロゲン原子のような置換基を有してもよい。
例えば、市販品としてストレートシリコン樹脂は、信越化学社製のＫＲ２７１、ＫＲ２５５、ＫＲ１５２、東レダウコーニング社製のＳＲ２４００、ＳＲ２４０５等があり、変性シリコン樹脂は、信越化学社製のＫＲ２０６（アルキッド変性）、ＫＲ５２０８（アクリル変性）、ＥＳ１００１Ｎ（エポキシ変性）、ＫＲ３０５（ウレタン変性）、東レダウコーニング社製のＳＲ２１１５（エポキシ変性）、ＳＲ２１１０（アルキッド変性）などがある。
【００６３】
更に、以下の理由により特定の官能基を有するシランカップリング剤を添加することができる。
１：シランカップリング剤を加えることにより、キャリアとシリコ−ン樹脂被覆層の接着性が向上し、被覆層の剥がれない高耐久のキャリアとなる。
２：シランカップリング剤にアミノ基を含有させることにより、キャリア自体の帯電性を正極性にすることができるため、負極性トナーに対し均一な帯電を付与することが可能である。
３：シランカップリング剤にクロロ基あるいはグリシドキシ基を含有させることで、キャリア自体の帯電性を負極性にできるので、正極性トナーに対し均一な帯電性を付与できる。
【００６４】
本発明に用いられるカップリング剤としては、以下に挙げるシランカップリング剤が好ましいが、そのほかチタンカップリング剤、アルミニュウムカップリング剤等も用いることができる。
【００６５】
本発明に好ましく用いられるシランカップリング剤としては、例えばγ−（２−アミノエチル）アミノプロピルトリメトキシシラン、γ−（２−アミノエチル）アミノプロピルメチルジメトキシシラン、γ−メタクリロキシプロピルトリメトキシシラン、Ｎ−β−（Ｎ−ビニルベンジルアミノエチル）−γ−アミノプロピルトリメトキシシラン塩酸塩、γ−グリシドキシプロピルトリメトキシシラン、γ−メルカプトプロピルトリメトキシシラン、メチルトリメトキシシラン、メチルトリエトキシシラン、ビニルトリアセトキシシラン、γ−クロロプロピルトリメトキシシラン、ヘキサメチルジシラザン、γ−アニリノプロピルトリメトキシシラン、ビニルトリメトキシシラン、オクタデシルジメチル［３−（トリメトキシシリル）プロピル］アンモニュウムクロライド、γ−クロロプロピルメチルジメトキシシラン、メチルトリクロロシラン、ジメチルジクロロシラン、トリメチルクロロシラン、（以上トーレ・シリコン社製）、アリルトリエトキシシラン、３−アミノプロピルメチルジエトキシシラン、３−アミノプロピルトリメトキシシラン、ジメチルジエトキシシラン、１．３−ジビニルテトラメチルジシラザン、メタクリルオキシエチルジメチル（３−トリメトキシシリルプロピル）アンモニュウムクロライド（以上チッソ社製）等が挙げられる。
【００６６】
本発明に用いられるシランカップリング剤の量としては、シリコン樹脂固形分に対し、１〜２５ｗｔ％が好ましい。シランカップリング剤の含有量が１ｗｔ％より少ないとその効果が発揮しにくい、該キャリアとシリコン被覆層の接着が劣るため、長期間での使用で被覆層の剥がれが生じやすくなる。また、含有量が２５ｗｔ％を越えるとシリコンの耐スペント性が悪化し、やはり長期間でのトナーのスペント化が発生しやすくなる。
【００６７】
本発明のキャリアは、１０００［Ｏｅ］の磁場中における飽和磁化を３０〜１２０［ｅｍｕ／ｇ］、好ましくは４０〜１００［ｅｍｕ／ｇ］とすることにより、現像領域における現像剤の現像スリーブへの磁気束縛力が大きくなるために、感光体上へのキャリアの現像が有効に防止され、良好な画像が得られる。
また、本発明のキャリアは、重量平均粒子径が２０〜１００μｍ、好ましくは２０〜８０μｍとすることにより、現像領域における現像剤層のトナー濃度を高くすることができるため、高速機での現像条件においても画像濃度の高い良好な画像が得られる。
【００６８】
次に、本発明に使用するトナーとしては、従来の公知の方法で製造されたものを使用できる。具体的には、結着樹脂、磁性体、極性制御剤、必要に応じて任意の添加剤よりなる混合物を熱ロールミルで溶融混練した後、冷却固化せしめ、これを粉砕分級し、必要に応じて外添剤を混合してえられる。
【００６９】
本発明の現像剤は、画像形成装置内で現像剤中のトナー濃度が以下に示される一般式で制御される。
【００７０】
【数１１】
Ｖ＝０．１０１（Ｚ） ^２ −１．３３Ｚ＋５．０２
（Ｖ）：トナー濃度制御電圧
（Ｚ）：トナー濃度
トナー濃度は、（Ｚ±３）％の範囲で制御されるが、Ｚが＋３％以上になると現像剤中のトナー濃度が高くなり過ぎ、帯電量低下を招き地肌汚れが発生する。また、Ｚが−３％以下になると著しく画像濃度低下を招くと同じにスペント化と呼ばれるキャリア表面へのトナー固着が発生する。
【００７１】
この結着樹脂としては、公知のものがすべて使用できる。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、ニトリル−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、ロジン、変性ロジン、テルペン樹脂、クマロインデン樹脂、脂肪族または脂肪族炭化水素樹脂、芳香族系石油樹脂、塩素化パラフィン、パラフィンワックスなど単独あるいは混合して使える。特に加熱加圧定着においては、結着樹脂としてポリエステル樹脂を用いることにより、耐塩ビマット融着性に優れ、熱ロールへの耐オフセット性に優れたトナーを得ることができる。加圧定着方式を用いる場合には、例えばポリスチレン、ポリプロピレン、ポリメチレン、ポリウレタンエラストマー、エチレン−エチルアクリレート共重合体、エチレン−酢酸ビニル共重合体、アイオノマー樹脂、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、線状飽和ポリエステル、パラフィンなどがある。
【００７２】
トナーには、荷電制御剤をトナー粒子に内添、またはトナー粒子に外添して用いることが好ましい。荷電制御剤によって、現像システムに応じた最適の荷電量コントロールが可能となり、特に本発明では荷電制御剤を用いることにより前記のトナー濃度を制御しない現像方法に用いた場合有効である。
【００７３】
トナーに用いる極性制御剤としては従来から公知のものでよく、正極性制御剤として、ニグロシン及び樹脂金属塩等による変性物；トリブチルベンジルアンモニュウム−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ュウムテトラフルオロボレートなどの四級アンモニュウム塩、；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；ジブチルガノスズボレイトを単独あるいは２種類以上組み合わせて用いることができる。これらの中でも、ニグロシン系化合物、有機四級アンモニュウム塩の如き極性制御剤が特に好ましく用いられる。負極性制御剤としては、例えば有機金属化合物、キレート化合物が有効である。その例としてはアルミニュムアセチルアセトナート、３,５−ジタ−シャリ−ブチルサリチル酸クロム等があり、特にアセチルアセトン金属錯体、モノアゾ金属錯体、ナフトエ酸あるいはサリチル酸系の金属錯体または、塩が好ましく特にサリチル酸金属錯体、モノアゾ金属錯体またはサリチル酸系金属塩が好ましい。
【００７４】
前記の極性制御剤は、微粒子状として用いることが好ましく、具体的には３μｍ以下の個数平均粒径が好ましい。
トナーに使用される極性制御剤の使用量は、結着樹脂の種類、必要に応じて使用される添加剤の有無、分散方法を含めたトナー製造方法によって決定されるもので、一義的に限定されるものではないが、好ましくは結着剤１００重量部に対して、０．１〜２０重量部の範囲、好ましくは０．２〜１０重量部で用いられる。０．１重量部未満では、トナーの帯電量が不足し実用的でない。また、２０重量部を越える場合にはトナーの帯電量が大きすぎ、キャリアとの静電吸引力の増大のため、現像剤の流動性低下や、画像濃度の低下を招く。
【００７５】
また、本発明のトナーは帯電安定性、現像性、流動性、耐久性向上のために、添加剤を用いることが好ましい。
これら添加剤として例えば、酸化セリウム、酸化ジルコニウム、酸化ケイ素、酸化チタン、酸化アルミニウム、酸化亜鉛、酸化アンチモン、酸化スズ等の金属酸化物や炭化珪素等の微粉末等の流動性向上剤や、例えばフッ素系樹脂粒子、シリコーン系樹脂微粒子、アクリル系樹脂微粒子等の樹脂微粒子やステアリン酸亜鉛、ステアリン酸カルシウム、ステアリン酸アルミニウム、ステアリン酸マグネシウム等の金属石鹸系滑剤等のクリーニング助剤が挙げられる。
【００７６】
この中でも特に流動性向上剤としては酸化ケイ素、酸化チタンが好ましく、クリーニング助剤としては、ステアリン酸亜鉛が好ましい。また、流動性向上剤として、必要に応じてシリコーンワニス、各種変性シリコーンワニス、シリコーンオイル、各種変性シリコーンオイル、シランカップリング剤、官能基を有するシランカップリング剤、その他有機珪素化合物の処理剤、あるいは種々の処理剤で併用して処理されていることが好ましい。また、定着時の離型性を良くする目的で離型剤を含有させてもよい。離型剤として、例えば低分子量ポリエチレン、低分子量ポリプロピレン、マイクロクリスタリンワックス、カルナバワックス、パラフィンワックス等をバインダー樹脂１００重量部に対し０．１〜１０重量％を磁性トナーに加えることが好ましい。現像剤を構成するキャリアとしては、１０００（Ｏｅ）の磁場中における飽和磁化を３０〜１２０（ｅｍｕ／ｇ）、好ましくは４０〜１００（ｅｍｕ／ｇ）とすることにより現像領域における現像剤の現像スリーブへの磁気束縛力が大きくなり、良好な画像が得られる。
【００７７】
また、トナーには必要に応じて顔料や染料等の着色剤を添加してもよい。顔料としては、例えば黒色の着色剤として、カーボンブラック、アニリンブラック、ファーネスブラック、ランプブラック等が使用できる。シアンの着色剤として例えば、フタロシアニンブルー、メチレンブルー、ビクトリアブルー、メチルバイオレット、アニリンブルー、ウルトラマリンブルー等が使用できる。マゼンタの着色剤として例えば、ローダミン６Ｇレーキレーキジメチルキナクリドン、ローズベンガル、ローダミンＢ、アリザリンレーキ等が使用できる。イエローの着色剤として例えば、クロムイエロー、ハンザイイエロー、モリブデンオレンジ、キノリンイエロー、タートラジン等が使用できる。その使用量は、樹脂１００重量部に対し０．１〜２０重量部、好ましくは２〜１０重量部の添加量がよい。染料としては例えば、アゾ系染料、アントラキノン系染料、キサンテン系染料、メチン系染料、等があり樹脂１００重両部に対し、０．０５〜１０重量部、好ましくは０．１〜３重量部の添加量がよい。
【００７８】
本発明で用いられるキャリアは、その体積固有抵抗を制御するために被覆層中に導電性付与材料を分散してもよい。
分散される導電性材付与は従来から公知のものでよく、例えば鉄、銅等の金属；フェライト、マグネタイト等の酸化鉄；カーボンブラック等の顔料が挙げられる。この中でも特にカーボンブラックのひとつであるファーネスブラックとアセチレンブラックの混合物を用いることにより、少量の導電性微粉末の添加で効果的に導電性の調整が可能で、更に被覆層の耐磨耗性に優れたキャリアを得ることが可能である。これらの導電性微粉末は、粒径０．０１〜１０μｍ程度が好ましく、更には５〜２０重量部が好ましい。
【００７９】
【実施例】
以下、本発明を実施例により説明する。
次にキャリアの製造例を以下に示す。
＜キャリア製造例１＞
湿式法により作成したマグネタイト１００重量部に対してポリビニルアルコール２重量部、水６０重量部をボールミルに入れ１２時間混合してマグネタイトのスラリーを調製した。このスラリーをスプレードライヤーにて噴霧造粒し、平均５４μｍの球形粒子とした。この粒子を窒素雰囲気で１０００℃の温度で３時間焼成後冷却し核体粒子１を得た。
【００８０】

【００８１】
上記混合物をホモミキサーで１０分間分散し、被覆層形成液１（分散液１）を調製した。
この被覆層形成液を流動床型コーティング装置（岡田精工社製：ＳＰ−４０）にて核体粒子：平均粒子径が５０μｍのフェライトキャリア（パウダーテック社製：Ｆ−３００）を２０００重量部の表面にコーティングして、シリコーン樹脂被覆キャリアＡを得た。コート／乾燥条件は、７０℃、キャリア粒径Ｄｃ、噴霧液滴粒径Ｄｓの比を１／５になるようにスプレー条件（スプレーエアー圧力：５．５ｋｇ／ｃｍ^２、スプレーエアー流量：３４０Ｌ／ｍｉｎ）を調整し、噴霧コーティングした。
【００８２】
また、焼成条件は、使用架橋剤沸点Ｆが２５９℃であるので、Ｂ３、Ｂ２温度が２７０℃、Ｂ１温度が２００℃になるように設定した。回転筒状乾燥炉内の内圧は−５０ｍｍＨｇになるように制御した。
【００８３】
＜キャリア製造例２＞
ＣｕＯ：２４ｍｏｌ％、ＺｎＯ：２５ｍｏｌ％、Ｆｅ_２Ｏ_３：５ｍｏｌ％に水を加え、湿式ボールミルにて１２時間粉砕混合し、スラリーを得た。このスラリーを乾燥し粉砕した後、１０００℃の温度で仮焼成を行なった。仮焼成後さらに湿式ボールミルにて１０時間粉砕し、分散剤及びバインダーを加えて、ついでスプレードライヤーにて造粒、乾燥し電気炉にて１１００℃で３時間焼成した。その後、粉砕／分級し平均粒径８０μｍの核体粒子２を得た。この核体粒子に対して、製造例１同様に流動層コーティング装置にて被覆層を形成し、キャリアＢを得た。
【００８４】
（実施例１）
製造例１で作成されたキャリアＡ：１００重量部に対し、トナーａ：５重量部をそれぞれ加え、ターブラーミキサーで混合し現像剤を得た。次に現像装置：（株）リコー製のＦＴ２２００に組み込み、画像出し試験を行ない、画像濃度地肌汚れ、キャリア現像、画像濃度制御性を評価した。ＦＴ２２００は、前記現像剤を画像形成装置に設置したときのトナー濃度をＺ１、そのときのトナー濃度制御電圧をＶ１としたとき、連続複写したときＺ１は（Ｚ１±３）％の範囲で制御され、トナー濃度は以下に示す関係式でトナー電圧制御される。
【００８５】
【数１２】
Ｖ＝０．１０１（Ｚ） ^２ −１．３３（Ｚ）＋５．０２
Ｖ＝トナー濃度制御電圧（Ｖ）
Ｚ＝トナー濃度（ｗｔ％）
【００８６】
実施例１〜実施例７、比較例１〜比較例３の製造条件／結果を一覧表１及び２に示す。
【００８７】
【表１】

【００８８】
［上記実施例における固定条件］
１：コート装置…（株）岡田精工製スピラコーターＳＰ−４０
２：回転筒状乾燥炉…（株）栗本鉄工所製外熱式ロータリーキルンＩＲＫ−０５
焼成温度は、スタート時とラスト排出時に炉内充填量が変動するため、２００〜３００℃（炉内焼成キャリア品温）で制御する。処理時間は、処理キャリアの滞留時間が２Ｈｒになるようにキルン回転数を調整する。
３：キャリア粒子…５０〜７０μｍのマグネタイトキャリア
４：コート処理量…平均２．５Ｋｇ／バッチを決定した。液滴粒径は、レーザー式粒径分布測定器（ＬＤＳＡ−２３００Ａ）にて計測して求める。
なお、計算方法は、（ロージン・ラムラー分布関数）で算出し、ＳＭＤ値を液滴平均粒径とした。
５：その他
【００８９】
各評価項目の評価方法について以下に説明する。
（抵抗特性、帯電特性）
抵抗特性・帯電特性は、基準値（目標値）に対して、ずれ度合いに応じて５段階に送別し、ずれの最も少ない物を◎とし、ずれに応じて評価分けした。
【００９０】
（凝集体粒径）
ＳＥＭ樹脂被覆断面写真の凝集体の粒径を計測し、ｎ＝１０の平均値を求める。
（凝集体存在率）
上記断面写真内の導電性粉体の１μｍ^２の存在量を面積化し、全面積に対する比率を求めた。
（Ｄｃ／Ｄｓ比）
噴霧液滴の粒径Ｄｓは、レーザー式粒度分布計により液滴計測を行ない、以下の式に当てはめ算出した。
粒径算出：ＳＭＤ
ＳＭＤ＝ΣＤ^３Δｎ／ΣＤ^２Δｎ
【００９１】
総合評価は、製品の生産性・品質を含め５段階に評価分けし、ランク５を◎としランク１を×とした。
【００９２】
【発明の効果】
以上、詳細かつ具体的な説明により明らかなように、本発明によって、キャリア粒子表面を被覆形成膜が一様に形成され且つ高耐久化が達成されるので安定品質が長期間得られる。
また、液滴径を微粒化且つスプレー方式を改善しているので、コートカスの発生が極力低減されるため、凝集の発生が少なくなり、コート品質が安定する。
【図面の簡単な説明】
【図１】膜状態模式図である。
【図２】流動層コーティング装置を示す図である。
【図３】連続式回転筒状乾燥炉を示す図である。
【符号の説明】
１ キャリア層
２ コート層
３ 導電性粉体の塊
４ コート層下層部（乾燥温度：高温）
５ コート層上層部（乾燥温度：低温）
１１ 乾燥エアー吸入管
１２ コーティング装置本体
１３ 排気サイクロン
１４ スプレーノズル
１５ 流動キャリア
１６ 温度センサー
１７ 回転ディスク版
１８ 分散液タンク
１９ 吸気ブロアー
２０ 調湿装置
２１ 回収容器
２２ ディスク駆動モーター
３１ オートフィーダー
３２ 燒結炉
３３ 排出口[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to a carrier for a developer used in a two-component development method based on an electrophotographic method or an electrostatic printing method.AManufacturing methodTo the lawIt is related.
[0002]
[Prior art]
The dry two-component developer used in the two-component development method is composed of toner particles and carrier particles, and fine toner particles are held on the surface of relatively large particles by the electric force generated by the friction of both particles. When the electrostatic latent image approaches the electrostatic latent image, the attracting force in the direction of the latent image with respect to the toner particles by the electric field formed by the electrostatic latent image overcomes the binding force between the toner particles and the carrier particles, and the toner particles The electrostatic latent image is visualized by being attracted and attracted onto the image.
The developer is repeatedly used while replenishing the toner consumed by the development. Therefore, in this two-component development method, in order to obtain a stable image density, it is necessary to make the mixing ratio (toner density) of the carrier and toner constant, and it is necessary to mount a toner replenishment mechanism and a toner density sensor for that purpose. Therefore, there is a drawback that the developing device becomes large and its operation mechanism becomes complicated.
[0003]
On the other hand, the one-component developing method does not use a developer in which carrier particles and toner particles are mixed as in the two-component developing method, and an electric force generated by friction between the toner and the developing sleeve or a toner and a magnet containing a magnetic material. The toner is held on the developing sleeve by the magnetic force between the developing sleeve and the electrostatic latent image forms an electrostatic latent image that forms an electrostatic latent image. Overcoming the coupling force between the developing sleeves, the toner particles are attracted and adhered onto the electrostatic latent image to visualize the electrostatic latent image.
[0004]
In the one-component development method, there is an advantage that the developing device can be reduced in size because it is not necessary to control the toner density. However, since the number of toner particles in the development region is smaller than that in the two-component method, the toner on the photoconductor The amount of development was insufficient, making it difficult to handle high-speed copying machines. As a method for improving these disadvantages, a two-component development method that does not require toner density control such as Japanese Patent Publication No. 5-67233 has been devised. In order to charge the toner by taking the toner into the developer and regulating the developer with a layer thickness regulating member, there is no need for a replenishment mechanism for replenishing the toner or a sensor for detecting the toner concentration. Since the amount of the developer cannot be increased as compared with the apparatus, in the case of a high-speed machine in which the linear velocity of the developing sleeve is increased, the toner cannot be sufficiently charged, and background staining occurs.
[0005]
In addition, in order to impart sufficient charge to the toner, it is necessary to increase the regulation stress at the layer thickness regulating member, so that a toner film is formed on the carrier surface due to heat generated by collision between developer particles. The so-called spent state occurs, and the charging characteristics of the carrier decrease with use time, causing toner scattering, background contamination, and the like.
[0006]
In addition, since the developer used in the above-described small-sized developing device needs to be charged to the toner replenished in a short time, a large amount of the replenished toner is mixed with the developer quickly. Although a fluidity improver was added, when such a developer is used repeatedly, an excessive fluidity improver in the toner adheres to the electrostatic latent image carrier, and an abnormal image on a streak is generated. There was a drawback.
Furthermore, when the agitation stress of the developer is increased, there is a problem that a so-called charge-up phenomenon that the toner charge amount becomes larger than necessary occurs in addition to the phenomenon of spent.
In addition, since these small-sized developing devices have a small amount of developer, the amount of toner consumed increases when a document with a small amount of toner held by the developer and a large image area is continuously copied, There is a drawback that the image density is lowered because the toner density in the developer changes extremely.
[0007]
Further, in this developing device, the amount of toner taken in is different between a portion where the developer moves actively and a portion where the developer is not moving, or a portion where the developer is large and a portion where the developer is small, and the toner density becomes partially unstable. Image density unevenness and fog are likely to occur.
Therefore, a technique for solving density unevenness and fogging in the longitudinal direction of the apparatus by disposing two toner supply members in the toner hopper and allowing the developer to pass through a path formed by each toner supply member. 63-4282. However, in the technique described in the above publication, since two toner supply members are used, there is a problem that the developing unit becomes large and the cost increases.
[0008]
On the other hand, as the resin used to coat the surface of the carrier base particle, a material having a low surface sea surface tension is usually used, and typical examples thereof include a tetrafluoroethylene polymer and a silicone resin. it can.
However, although the tetrafluoroethylene polymer can be prevented from being spent, it has a negative polarity and is difficult to use when charging the toner to the negative polarity.
In the case of a silicone resin, although the spent resistance is improved, the apparent specific resistance of the carrier is increased, so that there is a disadvantage that peripheral effects are likely to occur and the reproducibility of a wide black region and halftone region is deteriorated. In addition, since the counter charge at the time of toner detachment is excessive, carrier adhesion to non-image portions due to the electrostatic latent image is likely to occur.
[0009]
  Therefore, the conductive layer such as carbon black is applied to the coating layer made of silicone resin.powderIt has been proposed to mix the bodies.
  For example, Japanese Patent Application Laid-Open No. 56-126743 discloses a carrier coated with a material mainly composed of carbon black and resin, and Japanese Patent Application Laid-Open No. 62-45984 discloses a porous carbon black coating layer. A carrier contained therein is disclosed.
  However, in these methods, when the developer is prepared by mixing toner particles and carrier particles, or when copying is continuously repeated, the carbon in the coating layer drops off, causing contamination of the developing sleeve and the photosensitive member. Furthermore, there is a problem of causing contamination in the copying machine.
[0010]
In addition, a carrier provided with a coating layer made of a silicone resin containing a conductive substance has the advantage that the spent resistance is remarkably improved and the resistance value can be easily adjusted. The image quality such as manuscript reproducibility and fine line reproducibility has not yet met the higher level currently required in the market.
As one solution for achieving such high image quality, development is being carried out to reduce the particle size of toner and carrier.
However, for the small particle size carrier, in order to uniformly include the conductive material in the coating layer as described above, it is necessary to atomize like carbon black. There is a problem that the viscosity rapidly increases and cannot be handled by the usual spray method / conditions, but no solution has been proposed yet.
[0011]
On the other hand, there is a fluidized bed granulation method as a method for producing a resin-coated carrier.
Fluidized bed granulators have been actively introduced since around 1970, mainly in the pharmaceutical and food industries, because they can process small-quantity, multi-product production, mixing, granulation, and drying in the same container. In addition, the social environment required for granulated products is that granulated products of particle size, density, shape, etc. can be arbitrarily obtained for small-lot, high-mix production, and mixing, granulation, coating, and drying are performed by a single facility. Therefore, there has been a desire for a complex operation capable of selecting an arbitrary process and a multifunctional FA-based unmanned system capable of arbitrarily obtaining the above-described quality. In response to these demands, each equipment manufacturer has been developing and commercializing a composite granulator since about 1980, and equipment for processing each granulation method of fluidized bed, stirring, and rolling in the same container has been put to practical use. .
[0012]
Combined granulation method combines or fuses the functions of agitation granulation, rolling granulation, and fluidized bed granulation in the same container, and freely manufactures the quality of the granulated product such as shape, density, and particle size. There is a function that can be arbitrarily operated according to the purpose and application such as unit function such as mixing, granulation, drying and coating.
[0013]
Next, specific examples of the composite granulator will be given.
First, in the stirred fluidized bed type, there are (Super Fine Matrix SMA type) made by Nara Machinery Co., Ltd. and (Multiflex Granulator MP type) made by Paulek.
[0014]
In the rolling fluidized bed type, (Spiracoater SP type) manufactured by Okada Seiko is exemplified. In the agitating rolling fluidized bed type, there are Freund Sangyo (Spiraflow SFC type), Fuji Powder (Neumeralizer NQ type), and the like.
These spraying methods generally employ a spraying method (top spraying method, hereinafter referred to as a top spraying method) in which the spraying direction is sprayed from the top to the bottom, but has some problems.
[0015]
As one of them, the coating film is formed on the surface of the carrier base particle by spraying the forming liquid from the spray nozzle until the droplet sprayed from the spray nozzle reaches the carrier base particle. Therefore, the properties of the droplets (droplet diameter, droplet surface tension, droplet viscosity, drying speed, etc.) change immediately after spraying and when they reach the surface of the carrier particles, and the desired coating film quality is obtained. It may not be possible. In addition, since spraying is performed from above in one direction in the apparatus, many coating substances often adhere or adhere to other portions of the apparatus such as disk plates or wall surfaces other than carrier base particles.
Regarding the production of a coating film carrier based on a fluidized bed granulation method by spraying droplets, for example, Japanese Patent Publication No. 2-56935, Japanese Patent Publication No. 3-1063, Japanese Patent Publication No. 3-42028, Japanese Patent Publication No. No. 3-42029, No. 3-135430, No. 5-4128, No. 5-49901, No. 5-11508, No. 5-192555 and No. 6-195 Various proposals have been made in Japanese Patent No. 186.
However, even in these proposals, when the droplet collides with the carrier base particle, a lot of split recoil droplets are generated, and this droplet adheres to the inner wall surface of the apparatus, the rotating disk plate, or other carrier particles in a large amount. Many agglomerates are formed. In addition, these split recoil droplets are fine particles with a very small diameter compared to spray droplets, so some of them instantly solidify, and the solidified coating substance has a low specific gravity. This leads to a decrease in yield, and further adheres to the carrier surface in a dry solidified state (coat residue), which also deteriorates the quality of the coating film.
[0016]
  In addition, in order to prevent carrier adhesion to non-image areas, conductive properties such as carbon black are used in the coating resin coating layer.powderAlthough it is proposed to mix the body, if the appropriate carbon particle size and agglomeration state are not achieved, it will fall off when creating the developer mixture, or when copying continuously in the copier, the inside of the machine will be contaminated by scattering Or a deviation from the set carrier resistance value occurs. In that case, there is a problem that the carrier resistance becomes low, causing the occurrence of carrier adhesion and an abnormal image.
[0017]
[Problems to be solved by the invention]
An object of the present invention is to provide a carrier for an electrophotographic developer having a desired resistance value and sufficiently imparting charge to a toner for a long period of time, and a method for producing the same.
Another object of the present invention is to provide a two-component developer capable of obtaining a good image free of toner scattering, background stains, and streak stains, and an image forming method and apparatus using the same.
Another object of the present invention is to provide a two-component developer that is excellent in reproducibility of fine lines and halftones even in a small-sized developing device, and that can obtain a good image without development of a carrier on a photoreceptor. Image forming method and apparatus.
Another object of the present invention is to provide a long-life two-component developer capable of maintaining stable charging with little spent on a carrier even when the developer is used for a long time, and an image forming method and apparatus using the same. Is to provide.
[0024]
[Means for Solving the Problems]
  In addition, the above problem is1) "Using a combined fluidized bed granulator comprising at least a granulation cylinder, a rotating disk plate provided almost horizontally on the bottom surface near the bottom of the cylinder, and a spray nozzle for spraying coated droplets provided on the side wall of the cylinder The carrier base particles are supplied into the granulation cylinder, the rotating disk plate is rotated, and air is fed from both the upper part and the lower part of the apparatus, whereby the rotation direction of the disk plate made of carrier base particles A carrier for an electrophotographic developer is formed by forming a coating layer on the surface of the carrier base particles by spraying coating layer forming droplets from the spray nozzle after forming a fluidized bed in which the carrier base particles advance and swirl. In which the coating layer forming liquid is mainly composed of silicone resin, conductive powder and solvent, and the ambient temperature in the apparatus is formed while the coating layer is formed and dried. An electrophotographic developer characterized by gradually lowering the temperature from the first set temperature to the second set temperature and causing the aggregates of the conductive powder to exist in different states on the surface side of the coating layer and the carrier base particle side Manufacturing method for carrier ", (2) “The difference between the first set temperature and the second set temperature is 20 ° C. to 40 ° C.,1) Manufacturing method of carrier for electrophotographic developer according to item ", (3) "When the boiling point of the solvent constituting the coating layer forming liquid is T ° C, the atmospheric temperature in the apparatus is (T-10 to T-50) ° C.1) Or number (2) Manufacturing method of carrier for electrophotographic developer according to item ", (4) “When the coating layer forming solution contains a catalyst and the silicone resin contained in the coating layer forming solution is a thermosetting type, and the lower limit temperature of the curing is S ° C., the drying temperature after coating is (S− 20 to S-50) is dried at a drying atmosphere temperature of ° C.1) To (3) Method for producing a carrier for an electrophotographic developer according to any one of items5) “When the average particle diameter of the carrier base particles is Dc and the average particle diameter of the coating layer forming droplets sprayed from the spray nozzle is Ds, the (Ds / Dc) is 1/3 to 1/25. Characterized by the above (1) To (1)4) Method for producing a carrier for an electrophotographic developer according to any one of items6) “The relationship between the spray pressure and the spray air flow rate is sprayed under the conditions shown by the following formula,1) To (5) A method for producing a carrier for an electrophotographic developer according to any one of the items;
[0025]
[Formula 6]
Y = 52X + 57
    X: Spray air pressure (Kg / cm²)
    (X is 2.0 to 6.5)
    Y: Spray air flow rate (L / min) ”, (7) “Covered from the spray nozzle in the same direction as the carrier matrix particles, and in the range of + 5 ° to −40 ° with respect to the horizontal line, with respect to the carrier matrix particles forming a fluidized bed by rolling with centrifugal stirring. Spraying layer-forming droplets, said (1) To (6) Method for producing a carrier for an electrophotographic developer according to any one of items8) “The spray nozzle is installed at a portion where the swirling fluidized bed made of carrier base particles is in contact with the inner wall of the apparatus and at the center of the fluidized bed.1) To (7) Method for producing a carrier for an electrophotographic developer according to any one of items9) “Spray by adjusting the spray height of spray droplets to be 1/7 to 1/2 of the carrier base particle soaring height (both spray height and soaring height are based on the disk surface) The above (1) To (8) Method for producing a carrier for an electrophotographic developer according to any one of items10) “The pressure in the composite fluidized bed granulator is in the range of 0 to 50 Pa when the atmospheric pressure is 0 Pa.1) To (9) Method for producing a carrier for an electrophotographic developer according to any one of items11) "The above (1) To (10), A carrier having a coating layer (referred to as a coated carrier) produced on the surface thereof by sintering in a drying sintering furnace, and a method for producing a carrier for an electrophotographic developer ” , (12) “The drying sintering furnace is a rotary cylindrical mold, and the moving speed of the coated carrier in the drying sintering furnace is 40 to 110 mm / min.11) Manufacturing method of carrier for electrophotographic developer according to item ", (13) "Rotating cylindrical type drying sintering furnace with three separate heating zones from the entrance, the actual powder temperature in the heating zone at the inlet is B1 ° C, the actual powder temperature in the central heating zone is B2 When the actual powder temperature in the heating zone at the outlet is B3 ° C., the actual powder temperature is set so that the relationship expressed by the following (Equation 1) is satisfied, and the dry sintering furnace is rotated to sinter the coated carrier The first (11) Or item (12A method for producing the carrier for an electrophotographic developer according to item);
[0026]
[Expression 7]
B1 <B2 ≦ B3 (Formula 1)
    Real entrancepowderTemperature: B1 ° C
    Central fruitpowderTemperature: B2 ° C
    Exit partpowder(Temperature: B3 ° C.), (14) “Method for producing carrier for electrophotographic developer according to item (13), wherein temperature difference between B1 and B2 is 5 to 80 ° C.” 15) “The coating layer of the coated carrier contains a crosslinking agent, and when the boiling point of the crosslinking agent is F ° C., it is sintered under the conditions represented by the following (formula 2), (13) The method for producing a carrier for an electrophotographic developer according to item (14) or
[0027]
[Equation 8]
(B1 <B2 ≦ B3) → B3 = (F + 30) ° C. to (F−50) ° C. (Formula 2) ”, (16) "At the entrance of the drying sintering furnace heating zone, the temperature of the carrier after the coating resin treatment introduced at the start of the sintering treatment and before the drying sintering and the temperature of the carrier after the coating resin treatment introduced at the end of the sintering treatment and before the drying sintering The difference is processed at 100 ° C. or less., Said (12) To (15) Method for producing a carrier for an electrophotographic developer according to any one of items17) “The drying sintering furnace is a rotary cylindrical mold having a polygonal shape, and the coated carrier in the rotary furnace is advanced to the discharge side while causing a side slip by an avalanche phenomenon.11) To (16) Method for producing a carrier for an electrophotographic developer according to any one of items18) “The drying sintering furnace is a rotary cylindrical mold, and the pressure in the drying sintering furnace is controlled to 0 to −150 mmHg.11) To (17) Method for producing a carrier for an electrophotographic developer according to any one of items19) "The above (11) To (18The method for producing a carrier for an electrophotographic developer, wherein the coated carrier sintered in a dry sintering furnace is cooled at a cooling rate of 5 ° C./min or less by the method according to any one of the items Is solved by.
[0028]
In the carrier for an electrophotographic developer of the present invention, the presence state of the conductive powder that is in an aggregated state in the coating layer formed on the surface of the carrier base particle is controlled, and the obtained carrier has a desired resistance value. It is characterized by this. As a result, an image obtained using the developer comprising the carrier for an electrophotographic developer of the present invention and a toner has a high quality free from toner scattering, background stains and streak stains.
That is, “the presence state of the controlled conductive powder” means that the abundance of the conductive powder in the agglomerated state increases from the carrier base particle boundary surface of the coating layer toward the surface and / or the agglomeration. This means that the conductive powder in a state is present more on the surface side of the coating layer than on the carrier core particle side.
[0029]
The reason why the conductive powder is defined as being in an aggregated state is that when a coating layer containing the conductive powder is formed on the carrier base particle surface, the conductive powder usually exists in an aggregated state in most cases. If there is a conductive powder that is not in an agglomerated state, the carrier within the scope of the present invention can be used as long as the above existing state is formed by combining the agglomerated state and the non-aggregated state. Within.
[0030]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a schematic diagram showing a state in which a conductive powder in an agglomerated state is present in a coating layer. The coating layer (coat layer) (2) is formed on the carrier layer (1), and the aggregated conductive powder mass (3) is present more in the upper layer part (5) than in the lower layer part (4) of the coat film. Indicates the state.
[0031]
In conventional carriers, the abundance of conductive powder does not change much between the carrier base surface side and the surface side in the coating film, and a certain film thickness is maintained in the initial state of use. Over time, the film is scraped into a thin film state, and if a considerable amount of conductive powder is present at that time, the conductivity is further improved and a leak phenomenon (carrier discharge) occurs, causing abnormalities. The result was an image.
[0032]
The carrier of the present invention can solve such problems caused by the conventional carrier by reducing the amount of conductive powder so that the resistance of the lower layer portion of the film becomes high even when used.
As described above, the carrier for an electrophotographic developer of the present invention having excellent characteristics that have not been obtained in the past is not particularly limited as to its production method, but the present inventors have repeatedly investigated the production of the carrier, The method created as a result will be described.
[0033]
FIG. 2 is a conceptual diagram showing an example of a coating apparatus using a fluidized bed granulation method, which is used to manufacture the electrophotographic developer carrier of the present invention.
In the coating apparatus main body, the air introduced through the dry air suction pipe (11) is finally exhausted through the intake blower. The air into which the rotating disk plate rotated by the disk drive motor is introduced is turned into a swirling airflow, and a floating swirling fluidized bed (flowing carrier (15)) is formed by a large number of carrier base particles supplied into the apparatus main body.
A dispersion liquid (coating liquid) for forming a coating film in the dispersion liquid tank (18) is sprayed from the spray nozzle (14) to the fluidized bed composed of the carrier base particles to A coating film is formed by coating.
In the apparatus main body, the atmospheric temperature is controlled by the temperature sensor (16), and the humidity is controlled by the humidity controller (20).
By changing the ambient temperature in the coating process, a special existence state of the conductive particles existing in the carrier coating film of the present invention is formed. The change in the atmospheric temperature may be performed continuously even if the coating is interrupted.
[0034]
The carrier for an electrophotographic developer of the present invention can control the aggregation state of conductive powder such as carbon black in the coating coating layer to an arbitrary size and presence state by controlling the coating conditions. The desired carrier resistance can be adjusted, and if the obtained carrier is used, the required high image quality can be obtained.
[0035]
The coated coated carrier formed by the production method of the present invention can maintain a desired carrier resistance even when the coated film is deteriorated / scratched by an external pressure such as stress.
In particular, in the coating coating process, when the atmosphere temperature in the film forming apparatus to be described later is set higher than the temperature at the time of forming the coating film lower layer part at the time of forming the film, the aggregated conductive powder Can be present in a lower state in the lower layer.
[0036]
On the other hand, when forming the upper layer film, it is important to lower the atmosphere temperature in the apparatus during film formation from the temperature during lower layer film formation. It is effective to set the temperature 20 to 40 ° C. lower than the ambient temperature when forming the lower layer part. If the temperature difference during film formation between the upper layer and the lower layer becomes small, the difference in the aggregation state of the conductive powder tends to be almost eliminated, and the film resistance at the initial use of the carrier becomes high and the desired image quality cannot be obtained. Tend. On the other hand, when the treatment is performed with the temperature difference being increased, film scraping progresses, and a sudden change in film resistance tends to occur, making it difficult to obtain desired charging characteristics.
[0037]
If the ambient temperature during the film formation of the upper layer and the lower layer is suddenly changed, the agglomeration state of the conductive powder cannot be remarkably changed so that the boundary between the upper layer and the lower layer can be clearly defined. Although not possible, the carrier of the present invention tends not to greatly affect its characteristics depending on whether the boundary is clear or not.
[0038]
In the carrier manufacturing method of the present invention, the coating of the lower layer portion and the upper layer portion is normally performed as a series of steps in the apparatus for normal working efficiency, and is not interrupted to set the upper layer coating temperature. Rather, since the temperature is gradually lowered, the film does not become two layers having a boundary, and the conductive powder in an aggregated state is gradually present in a large amount from the bottom to the top in the coating layer, that is, An existence gradient will be formed.
[0039]
Although the boundary of the coating film of the carrier of the present invention is not necessarily clear, the upper layer part and the lower layer part are distinguished from the viewpoint of the existence state of the conductive powder, and divided into two in the film thickness direction, from the center line The upper side (the surface side of the film) is referred to as the upper layer part, and the lower side (carrier base side) is referred to as the lower layer part.
In the lower layer portion, the conductive powder is present in a relatively small aggregated state: 0.05 to 0.3 μm, and the upper layer portion is present in a relatively large state: 0.05 to 0.5 μm. This existence state can be adjusted by changing the above-described coating conditions, specifically, the drying temperature at the time of coating by changing the above-described temperature conditions.
[0040]
  Conductivity in coating filmpowderIn addition to the drying temperature at the time of coating, the agglomeration state of the body contributes to the spray droplet diameter, spray conditions, and internal pressure in the coating apparatus.
  The conductive powder present in the carrier of the present invention is 1 square μm at the film cross section and at the upper layer.²By making it exist at a ratio of 50% or more per unit, a film having a resistance lower than that of the lower part of the coating film is formed.
  Conversely, the lower layer of the film is 1 square μm²By making it exist at a ratio of 50% or less per film, a film having a film resistance higher than that of the upper layer part of the film is formed.
[0041]
  As the dispersant constituting the film forming liquid used for the coating of the present invention, a solvent-based solvent is usually used. When the boiling point of the solvent is T ° C., an arbitrary carbon dispersion state is formed by forming at a dry atmosphere temperature of (T-10 to T-60) ° C., and a resin-coated carrier having a specific resistance is obtained. .
  If created outside these conditions, the spray droplets will rapidly evaporate and become conductive.powderIt is not preferable because an appropriate amount of the body does not adhere or the evaporation is slowed to cause aggregation between carriers.
  The spraying condition of the production method of the present invention is that when the particle size of the carrier matrix to be coated is Dc, the spray droplet diameter Ds is 1/3 to 1/25 of the particle size of the carrier matrix. Is done. When the spray droplet diameter is close to the particle size of the carrier matrix (1/3 or more), a large number of split recoil droplets are generated when the spray droplet collides with the carrier matrix particles, and the carrier matrices are Aggregation and adhesion of coating liquid to the inside of the apparatus occur.
  On the contrary, when the spray droplet diameter becomes small (1/25 or less), the droplet evaporates at the same time as the spray and mist of the coating resin is generated, resulting in a problem that the adhesion efficiency is lowered. The droplet diameter is preferably 1/5 to 1/10 of the carrier base particle.
[0042]
Further, in order to obtain the droplet diameter, the spraying conditions of the present invention are performed under the following conditions of spray air pressure and spray air flow rate.
When the spray air pressure is X and the spray air flow rate is Y, the necessary condition is expressed by the following relational expression.
[0043]
[Equation 9]
Y = 52X + 57
X: 2 to 6.5
The spray air pressure and the spray air flow rate are sprayed under the above-mentioned conditions, and the spray air pressure is sprayed in the range of 2 to 6.5. Preferably, 4-6 is good. When the spray air pressure is 2 or less, the spray droplet diameter increases rapidly, resulting in droplets larger than the carrier particle diameter, leading to liquid dripping and aggregation between carriers. In addition, when sprayed at a high pressure of spray air pressure of 6.5 or more, the droplets instantly evaporate, and a large amount of resin mist is generated or does not adhere to the carrier base particles, so that the adhesion efficiency is reduced. . In the coating method of the present invention, the spray is sprayed in the horizontal + 5 ° to −40 ° direction inside the apparatus body.
[0044]
When the spray droplet average particle diameter is 1/3 or more of the particle to be coated (carrier base particle), the dried film formed on the surface of the carrier base particle is formed as a large uneven shape. The coating film becomes uneven. In addition, the protrusions are difficult to dry inside the film (even if the film surface is dried, the inside remains undried), so when contacting with other coating substances (small particle carrier particles after coating) And it joins at the time of a collision and becomes an aggregate. Further, since the droplet diameter is large, a desired coating film thickness cannot be obtained, and the film thickness may vary. On the other hand, when the spray droplets are 5 μm or less, the solvent contained in the sprayed droplets instantly evaporates (due to the drying speed UP) and solidifies and cannot be formed into a film. For this reason, the resin component in the coating liquid may become dry solid particles, adhere to the inner wall of the apparatus as scattered matter or debris, or fly to the exhaust side, resulting in a decrease in yield.
[0045]
In the coating method of the present invention, the carrier base particles are spray-coated with droplets in the horizontal direction + 5 ° to −40 ° in a composite airflow that forms an annular flow and a vortex flow in the device layer. If the behavior of the material to be coated in the layer is only an annular flow, the carrier particles after coating and the carrier base particles before coating may not move smoothly, and it may not be possible to uniformly coat all the particles.
[0046]
A large number of carrier base particles swirl in a donut shape, and the outermost part of the “donut” fluidized bed formed by the centrifugal force is formed in a portion closest to the inner wall of the apparatus.
When the spray nozzle in the apparatus is installed at a portion where the swirling fluidized bed made of carrier base particles is in contact with the inner wall of the apparatus and at the center of the fluidized bed, spray coating can be performed effectively.
Furthermore, the height of the spray nozzle from the disk plate is set to 1/7 to 1/2 of the carrier rising height, that is, the spray height of the spray droplets is 1/7 to 1/1 of the carrier base particle rising height. It is preferable to perform spraying while adjusting the pressure to be 2.
[0047]
In general, droplets are sprayed in a fan-like conical shape, the height of the spray center is the spray height, and the carrier base particle flying height is the average height of the flying upper stage height, both of which are the disc surface The scale is attached in advance to the inner wall of the coater and read.
If spray nozzle is set at a height of less than 1/7 of the carrier body height and sprayed, the nozzle position is low, so the spray liquid adheres and solidifies on the disk plate, and agglomeration of carrier particles often occurs. The tendency to do comes out. On the other hand, if the height of the nozzle and the carrier soaring height are set at a height that is 1/2 or more of the carrier soaring height, there is a tendency for the problem that the adhesion efficiency of the spray droplets to the carrier particles greatly decreases. come.
[0048]
The pressure in the apparatus at the time of coating of the present invention is treated in a positive pressure atmosphere of 0 to 50 Pa when the atmospheric pressure is 0 Pa. When the internal pressure is a negative pressure, the flow behavior of the carrier particles in the apparatus is deteriorated, and the carriers are easily aggregated. On the other hand, when the internal pressure becomes 50 Pa or more, the flow state of the particles in the apparatus becomes intense, the establishment of collision of spray droplets is lowered, and the film is easily thinned.
[0049]
The carrier having the coating film formed on the surface as described above (coated carrier) is usually sintered in a dry sintering furnace in order to increase the strength of the coating film.
FIG. 3 is a conceptual diagram showing an example of a rotary cylindrical dry sintering furnace which is a kind of drying sintering furnace used in this sintering process.
The rotary cylindrical dry sintering furnace is divided into three independent heating zones from the entrance, and a heating element (heater 1, heater 2 and heater 3) is installed in each zone, and has a mechanism that rotates. In addition, the furnace is set to be slightly lower on the discharge side.
[0050]
The coated carrier put in the auto feeder (31) is quantitatively introduced into the heated sintering furnace (32). The charged carriers are sequentially heated and sintered by the respective heaters. During the sintering, the furnace is slowly rotated, and the heated and sintered carrier slowly moves from the inlet side to the discharge port (33) side and is discharged. After the discharged carriers are cooled, coarse substances (aggregates and the like) are removed with a vibrating sieve or the like.
[0051]
The actual powder temperature of the heating zone at the entrance of the rotating cylindrical type dry sintering furnace was B1 ° C, the actual powder temperature of the heating zone at the center was B2 ° C, and the actual powder temperature of the heating zone at the outlet was B3 ° C. At this time, the relationship of the actual powder temperature in each zone portion in the rotary cylindrical dry sintering furnace is sintered according to the relationship represented by the following relational expression.
[0052]
[Expression 10]
(B1 <B2 ≦ B3) → B3 = (F + 30) ° C. to (F−50) ° C.
[0053]
  The in-furnace temperature of the rotary cylindrical dry sintering furnace used in the production method of the present invention can be arbitrarily set in each zone.
  When the temperature of the above relational expression (B1 <B2 ≦ B3) is processed at a temperature equal to or higher than F ° C., unreacted crosslinking agent and crosslinking agent during crosslinking are removed from the coated resin film during sintering of the coated resin. It becomes easy to detach and causes film deterioration. In the sintering method of the present invention,powderTemperature B1 and center partpowderBy controlling the temperature difference of the temperature B2 to 5 to 80 ° C., stable quality can be obtained. When the temperature difference between B1 and B2 is 5 ° C. or less, the coating resin film is strongly sintered, so that the film surface is scraped and a large amount of resin mist adheres to the film surface, resulting in desired charging characteristics and resistance. No value can be obtained.
[0054]
  When the sintering process is performed using a rotary cylindrical dry sintering furnace, the process in the furnace is performed at the start and end.powderResidence amount fluctuates. For this reason, if the treatment is continued under the conditions for the stable treatment, the sintering becomes too strong, and it is necessary to control the sintering temperature. In order to solve the above-mentioned problem, the present invention obtains a sintered carrier having a stable quality by suppressing the temperature change at the entrance in the rotary cylindrical dry sintering furnace after the coating resin is charged to within 100 ° C. I found out.
  When the temperature change at the entrance after the final charging becomes 100 ° C. or more, the coating resin film deteriorates due to the rapid temperature change and the film strength is lowered, that is, uneven baking occurs, and the carrier surface after coating changes greatly, The characteristics may change greatly, which is not preferable.
[0055]
  The rotary cylindrical drying furnace of the present invention is a horizontal cylindrical drying furnace and does not cause a showering phenomenon, and the rotary inner cylinder has a polygonal shape with six surfaces. There are no blades that generate shower ring on the surface of each surface, and a side slip phenomenon that moves downward by rotation occurs. When showering occurs, damage to the resin film on which the coating is formed is large, and film deterioration (film scraping) is likely to occur.
  Further, the inside of the rotary cylindrical drying furnace is controlled to an internal pressure of 0 to 150 mmHg, and in the inner cylinder portion, constant air flows from the discharge side to the input portion side. The air that flows in is a high-temperature gas containing low-molecular components in the coating resin that is generated during sintering, and resin dropping that occurs when a lateral shift occurs.powderHas the effect of discharging to the outside of the furnace. When the internal pressure becomes positive, there is no appropriate air flow rate in the furnace, so gas and resin drop off in the previous period.powderWill not be discharged and will adhere to the surface of the carrier particles, degrading the carrier quality. Further, when the internal pressure becomes a negative pressure of −150 mmHg or more, the flow velocity in the furnace is increased, and the low specific gravity carrier is also discharged out of the furnace, resulting in a decrease in yield.
[0056]
The resin-coated carrier of the present invention is processed at a moving speed of the carrier to be sintered of 40 to 110 mm / min. When the moving speed is 40 mm / min or less, the thermal energy received by the carrier is increased, the thermal energy equal to or higher than the cross-linking agent boiling point + 30 ° C. or higher is received, and the film strength is weakened.
On the other hand, when the moving speed is 110 mm / min or more, the carrier is subjected to great stress, and the coating formation film surface is easily scraped. The scraped film becomes a residue and adheres to the surface, so that desired quality cannot be obtained.
[0057]
In the carrier of the present invention, the air to be blown into the sintering furnace is blown in a dehumidified state by an apparatus such as a dryer, but if the air is blown without being dehumidified, the low molecular component gas generated during carrier sintering and the air Moisture reacts and the sintering temperature falls below the target sintering temperature, which also tends to cause quality degradation.
[0058]
As the carrier base particles used in the production of the carrier of the present invention, conventionally known particles can be used, for example, ferromagnetic metals such as iron, cobalt and nickel; alloys and compounds such as magnetite, hematite and ferrite; Examples include a composite of magnetic fine particles and a resin.
[0059]
In the method for producing a carrier of the present invention, the coating layer forming liquid prepared in advance for coating the core material is a curing catalyst as necessary in addition to the silicone resin, the conductive powder, and the solvent-based dispersant. It is composed of
When a catalyst is used, the properties of the film can be changed by controlling the film formation temperature.
In the case of the present invention, if the temperature is kept low, the film curing becomes slow. Therefore, the conductive powder existing in the atomized state and without agglomeration immediately after spraying can be moved inside the film and becomes conductive powder. They tend to aggregate together. On the other hand, when the film is dried at a high temperature, the film itself begins to dry quickly, so that the conductive powder is difficult to move and the aggregates are few.
[0060]
As the silicone resin that is a coating resin for the core material used in the present invention, any of a conventionally known thermosetting type, ultraviolet curable type or photocurable type silicone resin can be used. .
For example, a straight silicone resin composed only of an organosiloxane bond represented by the following formula and a silicone resin modified with alkyd, polyester, epoxy, urethane, etc. can be mentioned.
[0061]
[Chemical 1]

In the above formula, R1 is a hydrogen atom, an alkyl group having 1 to 4 carbon atoms or a phenyl group, R2 and R3 are hydrogen groups, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, and a phenyl group. , An alkenyl group having 2 to 4 carbon atoms, an alkenyloxy group having 2 to 4 carbon atoms, a hydroxy group, a carboxyl group, an ethylene oxide group, a glycinyl group, or a group shown below.
[0062]
[Chemical 2]

(In the above formula, R4 and R5 are a hydroxy group, a carboxyl group, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, an alkenyl group having 2 to 4 carbon atoms, and 2 to 2 carbon atoms. 4 alkenyl group, alkenyloxy group having 2 to 4 carbon atoms, phenyl group, phenoxy group, k, l, m, n, O, and p are each a positive number of 1 or more). Each of the above substituents may have a substituent such as an amino group, a hydroxy group, a carboxyl group, a mercapto group, an alkyl group, a phenyl group, an ethylene oxide group, or a halogen atom in addition to an unsubstituted group.
For example, commercially available straight silicon resins include KR271, KR255, KR152 manufactured by Shin-Etsu Chemical Co., Ltd., SR2400, SR2405 manufactured by Toray Dow Corning Co., Ltd., and modified silicon resins include KR206 (alkyd modified) manufactured by Shin-Etsu Chemical There are KR5208 (acrylic modification), ES1001N (epoxy modification), KR305 (urethane modification), SR2115 (epoxy modification) and SR2110 (alkyd modification) manufactured by Toray Dow Corning.
[0063]
Furthermore, a silane coupling agent having a specific functional group can be added for the following reason.
1: By adding a silane coupling agent, the adhesion between the carrier and the silicone resin coating layer is improved, and a highly durable carrier that does not peel off the coating layer is obtained.
2: By containing an amino group in the silane coupling agent, the chargeability of the carrier itself can be made positive, so that uniform charging can be imparted to the negative toner.
3: By adding a chloro group or a glycidoxy group to the silane coupling agent, the chargeability of the carrier itself can be made negative, so that uniform chargeability can be imparted to the positive toner.
[0064]
As the coupling agent used in the present invention, the following silane coupling agents are preferable, but in addition, titanium coupling agents, aluminum coupling agents, and the like can also be used.
[0065]
Examples of the silane coupling agent preferably used in the present invention include γ- (2-aminoethyl) aminopropyltrimethoxysilane, γ- (2-aminoethyl) aminopropylmethyldimethoxysilane, and γ-methacryloxypropyltrimethoxysilane. N-β- (N-vinylbenzylaminoethyl) -γ-aminopropyltrimethoxysilane hydrochloride, γ-glycidoxypropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, methyltrimethoxysilane, methyltriethoxy Silane, vinyltriacetoxysilane, γ-chloropropyltrimethoxysilane, hexamethyldisilazane, γ-anilinopropyltrimethoxysilane, vinyltrimethoxysilane, octadecyldimethyl [3- (trimethoxysilyl) propyl] an Neutium chloride, γ-chloropropylmethyldimethoxysilane, methyltrichlorosilane, dimethyldichlorosilane, trimethylchlorosilane (made by Torre Silicone), allyltriethoxysilane, 3-aminopropylmethyldiethoxysilane, 3-aminopropyl Examples include trimethoxysilane, dimethyldiethoxysilane, 1.3-divinyltetramethyldisilazane, methacryloxyethyldimethyl (3-trimethoxysilylpropyl) ammonium chloride (manufactured by Chisso Corporation).
[0066]
As a quantity of the silane coupling agent used for this invention, 1-25 wt% is preferable with respect to silicon resin solid content. When the content of the silane coupling agent is less than 1 wt%, the effect is difficult to exert. The adhesion between the carrier and the silicon coating layer is inferior, so that the coating layer is easily peeled off when used for a long period of time. On the other hand, when the content exceeds 25 wt%, the spent resistance of silicon deteriorates, and the spent toner tends to occur for a long period of time.
[0067]
The carrier of the present invention has a saturation magnetization in a magnetic field of 1000 [Oe] of 30 to 120 [emu / g], preferably 40 to 100 [emu / g], so that the developer in the developing region can be transferred to the developing sleeve. Therefore, the development of the carrier onto the photosensitive member is effectively prevented, and a good image can be obtained.
The carrier of the present invention has a weight average particle diameter of 20 to 100 μm, preferably 20 to 80 μm, so that the toner concentration of the developer layer in the development region can be increased. In this case, a good image with high image density can be obtained.
[0068]
Next, as the toner used in the present invention, a toner produced by a conventionally known method can be used. Specifically, a mixture consisting of a binder resin, a magnetic material, a polarity control agent, and optional additives as necessary is melt-kneaded with a hot roll mill, cooled and solidified, and pulverized and classified, if necessary. Can be obtained by mixing external additives.
[0069]
In the developer of the present invention, the toner concentration in the developer is controlled by the general formula shown below in the image forming apparatus.
[0070]
## EQU11 ##
V = 0.101(Z) ² -1.33Z + 5.02
    (V): toner density control voltage
    (Z): Toner concentration
  The toner concentration is controlled in the range of (Z ± 3)%. However, when Z is + 3% or more, the toner concentration in the developer becomes too high, resulting in a decrease in charge amount and background stains. Further, when Z is −3% or less, if the image density is remarkably lowered, toner fixation to the carrier surface called “spenting” occurs.
[0071]
Any known binder resin can be used. For example, styrene and its substituted homopolymers such as polystyrene, poly-p-chlorostyrene, polyvinyltoluene; 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 Styrenic copolymers such as ethyl ether copolymer, styrene-vinyl methyl ketone copolymer, nitrile-isoprene copolymer, styrene-acrylonitrile-indene copolymer; polyvinyl chloride, phenol resin, naturally modified phenol resin, Natural resin-modified maleic acid Fat, acrylic resin, methacrylic resin, polyvinyl acetate, silicone resin, polyester resin, polyurethane, polyamide resin, furan resin, epoxy resin, xylene resin, polyvinyl butyral, rosin, modified rosin, terpene resin, coumaroindene resin, aliphatic or fat Aromatic hydrocarbon resin, aromatic petroleum resin, chlorinated paraffin, paraffin wax, etc. can be used alone or in combination. In particular, in heat and pressure fixing, by using a polyester resin as a binder resin, it is possible to obtain a toner having excellent resistance to PVC mat fusion and excellent resistance to offset to a hot roll. When using the pressure fixing method, for example, polystyrene, polypropylene, polymethylene, polyurethane elastomer, ethylene-ethyl acrylate copolymer, ethylene-vinyl acetate copolymer, ionomer resin, styrene
-Butadiene copolymer, styrene-isoprene copolymer, linear saturated polyester, paraffin and the like.
[0072]
In the toner, it is preferable to use a charge control agent added internally to the toner particles or externally added to the toner particles. The charge control agent makes it possible to control the optimum charge amount according to the development system. In particular, the present invention is effective when used in the development method in which the toner concentration is not controlled by using the charge control agent.
[0073]
The polarity control agent used in the toner may be a conventionally known one, and as the positive polarity control agent, a modified product with nigrosine and a resin metal salt; tributylbenzylammonium-1-hydroxy-4-naphthosulfonate, tetrabutylammonium Quaternary ammonium salts such as tetrafluoroborate; diorganotin oxides such as dibutyltin oxide, dioctyltin oxide and dicyclohexyltin oxide; dibutylganotin borate can be used alone or in combination of two or more. Among these, polar controlling agents such as nigrosine compounds and organic quaternary ammonium salts are particularly preferably used. As the negative polarity control agent, for example, organometallic compounds and chelate compounds are effective. Examples thereof include aluminum acetylacetonate, chromium 3,5-di-tert-butylsalicylate, etc., and particularly preferred are acetylacetone metal complexes, monoazo metal complexes, naphthoic acid or salicylic acid metal complexes or salts, and particularly salicylic acid metal. Complexes, monoazo metal complexes or salicylic acid metal salts are preferred.
[0074]
The polarity control agent is preferably used in the form of fine particles, and specifically, a number average particle diameter of 3 μm or less is preferable.
The amount of the polarity control agent used in the toner is uniquely determined by the type of binder resin, the presence or absence of additives used as necessary, and the toner production method including the dispersion method. However, it is preferably used in the range of 0.1 to 20 parts by weight, preferably 0.2 to 10 parts by weight with respect to 100 parts by weight of the binder. If it is less than 0.1 part by weight, the charge amount of the toner is insufficient, which is not practical. On the other hand, when the amount exceeds 20 parts by weight, the charge amount of the toner is too large, and the electrostatic attractive force with the carrier is increased, leading to a decrease in developer fluidity and a decrease in image density.
[0075]
In addition, it is preferable to use an additive in the toner of the present invention in order to improve charging stability, developability, fluidity, and durability.
Examples of these additives include fluidity improvers such as fine powders of metal oxides such as cerium oxide, zirconium oxide, silicon oxide, titanium oxide, aluminum oxide, zinc oxide, antimony oxide and tin oxide, and silicon carbide. Cleaning aids such as resin fine particles such as fluorine resin particles, silicone resin fine particles, and acrylic resin fine particles, and metal soap lubricants such as zinc stearate, calcium stearate, aluminum stearate, and magnesium stearate can be mentioned.
[0076]
Of these, silicon oxide and titanium oxide are particularly preferred as the fluidity improver, and zinc stearate is preferred as the cleaning aid. In addition, as a fluidity improver, if necessary, silicone varnish, various modified silicone varnishes, silicone oil, various modified silicone oils, silane coupling agents, silane coupling agents having a functional group, other organosilicon compound treating agents, Or it is preferable to process by using together with various processing agents. Further, a release agent may be added for the purpose of improving the releasability at the time of fixing. As a release agent, for example, low molecular weight polyethylene, low molecular weight polypropylene, microcrystalline wax, carnauba wax, paraffin wax and the like are preferably added to the magnetic toner in an amount of 0.1 to 10% by weight based on 100 parts by weight of the binder resin. As the carrier constituting the developer, the development of the developer in the development region is achieved by setting the saturation magnetization in a magnetic field of 1000 (Oe) to 30 to 120 (emu / g), preferably 40 to 100 (emu / g). The magnetic binding force on the sleeve is increased, and a good image can be obtained.
[0077]
Further, a colorant such as a pigment or a dye may be added to the toner as necessary. As the pigment, for example, carbon black, aniline black, furnace black, lamp black and the like can be used as a black colorant. Examples of cyan colorants include phthalocyanine blue, methylene blue, Victoria blue, methyl violet, aniline blue, and ultramarine blue. As a magenta colorant, for example, rhodamine 6G lake lake dimethylquinacridone, rose bengal, rhodamine B, alizarin lake and the like can be used. Examples of yellow colorants that can be used include chrome yellow, hansai yellow, molybdenum orange, quinoline yellow, and tartrazine. The amount used is 0.1 to 20 parts by weight, preferably 2 to 10 parts by weight, based on 100 parts by weight of the resin. Examples of the dye include azo dyes, anthraquinone dyes, xanthene dyes, methine dyes, and the like, and 0.05 to 10 parts by weight, preferably 0.1 to 3 parts by weight with respect to 100 parts by weight of the resin. The amount added is good.
[0078]
In the carrier used in the present invention, a conductivity-imparting material may be dispersed in the coating layer in order to control its volume resistivity.
Application of the conductive material to be dispersed may be conventionally known, and examples thereof include metals such as iron and copper; iron oxides such as ferrite and magnetite; and pigments such as carbon black. Among these, in particular, by using a mixture of furnace black and acetylene black, which is one of carbon blacks, it is possible to effectively adjust the conductivity with the addition of a small amount of conductive fine powder, and to further improve the wear resistance of the coating layer. It is possible to obtain an excellent carrier. These conductive fine powders preferably have a particle size of about 0.01 to 10 μm, more preferably 5 to 20 parts by weight.
[0079]
【Example】
Hereinafter, the present invention will be described with reference to examples.
Next, an example of manufacturing a carrier is shown below.
<Carrier production example 1>
A magnetite slurry was prepared by putting 2 parts by weight of polyvinyl alcohol and 60 parts by weight of water into a ball mill for 12 hours with respect to 100 parts by weight of magnetite prepared by a wet method. This slurry was sprayed and granulated with a spray dryer to obtain spherical particles having an average of 54 μm. The particles were fired in a nitrogen atmosphere at a temperature of 1000 ° C. for 3 hours and then cooled to obtain core particles 1.
[0080]

[0081]
The mixture was dispersed with a homomixer for 10 minutes to prepare coating layer forming liquid 1 (dispersion liquid 1).
Using a fluidized bed coating apparatus (Okada Seiko Co., Ltd .: SP-40), the core layer particle: Ferrite carrier (Powder Tech Co., Ltd .: F-300) having an average particle diameter of 50 μm was added to 2000 parts by weight of this coating layer forming liquid. The surface was coated to obtain a silicone resin-coated carrier A. The coating / drying conditions are such that the ratio of the carrier particle diameter Dc and the spray droplet diameter Ds is 70, and the spray condition (spray air pressure: 5.5 kg / cm)²Spray air flow rate: 340 L / min), and spray coating was performed.
[0082]
The firing conditions were set such that the B3 and B2 temperatures were 270 ° C. and the B1 temperature was 200 ° C. because the used crosslinking agent boiling point F was 259 ° C. The internal pressure in the rotary cylindrical drying furnace was controlled to be −50 mmHg.
[0083]
<Carrier production example 2>
CuO: 24 mol%, ZnO: 25 mol%, Fe₂O₃: Water was added to 5 mol%, and the mixture was pulverized and mixed in a wet ball mill for 12 hours to obtain a slurry. The slurry was dried and pulverized, and then calcined at a temperature of 1000 ° C. After calcination, the mixture was further pulverized with a wet ball mill for 10 hours, added with a dispersant and a binder, granulated and dried with a spray dryer, and baked at 1100 ° C. for 3 hours with an electric furnace. Thereafter, pulverization / classification was performed to obtain core particles 2 having an average particle size of 80 μm. A coating layer was formed on the core particles using a fluidized bed coating apparatus in the same manner as in Production Example 1 to obtain carrier B.
[0084]
Example 1
To 100 parts by weight of carrier A prepared in Production Example 1, 5 parts by weight of toner a was added and mixed with a tumbler mixer to obtain a developer. Next, it was incorporated into a developing device: FT2200 manufactured by Ricoh Co., Ltd., and an image output test was conducted to evaluate image density background contamination, carrier development, and image density controllability. In the FT2200, when the toner density is set to Z1 when the developer is installed in the image forming apparatus and the toner density control voltage at that time is V1, Z1 is controlled within a range of (Z1 ± 3)% when continuously copying. The toner density is controlled by the following relational expression.
[0085]
[Expression 12]
V = 0.101 (Z) ² -1.33 (Z) +5.02
    V = toner density control voltage (V)
    Z = toner concentration (wt%)
[0086]
The production conditions / results of Examples 1 to 7 and Comparative Examples 1 to 3 are shown in Tables 1 and 2.
[0087]
[Table 1]

[0088]
[Fixed conditions in the above embodiment]
1: Coat device ... Spiral coater SP-40 manufactured by Okada Seiko Co., Ltd.
2: Rotating cylindrical drying furnace ... External heat rotary kiln IRK-05 manufactured by Kurimoto Iron Works
The firing temperature is controlled at 200 to 300 ° C. (in-furnace firing carrier product temperature) because the amount of filling in the furnace varies at the start and last discharge. As for the processing time, the kiln rotational speed is adjusted so that the residence time of the processing carrier is 2 Hr.
3: Carrier particles: magnetite carrier of 50 to 70 μm
4: Coating treatment amount: An average of 2.5 kg / batch was determined. The droplet diameter is determined by measuring with a laser type particle size distribution analyzer (LDSA-2300A).
The calculation method was calculated by (Rosin-Rammler distribution function), and the SMD value was defined as the average droplet diameter.
5: Other
[0089]
The evaluation method for each evaluation item will be described below.
(Resistance characteristics, charging characteristics)
The resistance characteristics and charging characteristics were divided into five levels according to the degree of deviation with respect to the reference value (target value), and the item with the smallest deviation was marked with 、, and the evaluation was divided according to the deviation.
[0090]
(Agglomerate particle size)
The particle size of the aggregate of the SEM resin-coated cross-sectional photograph is measured, and the average value of n = 10 is obtained.
(Aggregate presence rate)
1 μm of conductive powder in the above cross-sectional photograph²The abundance of was aread and the ratio to the total area was determined.
(Dc / Ds ratio)
The particle size Ds of the sprayed droplets was calculated by applying droplet measurement using a laser particle size distribution meter and applying the following equation.
Particle size calculation: SMD
SMD = ΣD³Δn / ΣD²Δn
[0091]
The overall evaluation was divided into five levels including product productivity and quality, rank 5 was marked with ◎, and rank 1 was marked with x.
[0092]
【The invention's effect】
As described above, as is clear from the detailed and specific description, according to the present invention, the coating formation film is uniformly formed on the surface of the carrier particles and high durability is achieved, so that stable quality can be obtained for a long time.
Further, since the droplet diameter is reduced and the spray method is improved, the generation of coat residue is reduced as much as possible, so that the occurrence of aggregation is reduced and the coating quality is stabilized.
[Brief description of the drawings]
FIG. 1 is a schematic diagram of a film state.
FIG. 2 is a diagram showing a fluidized bed coating apparatus.
FIG. 3 is a view showing a continuous rotary cylindrical drying furnace.
[Explanation of symbols]
1 Carrier layer
2 Coat layer
3 Lumps of conductive powder
4 Lower part of coat layer (drying temperature: high temperature)
5 Upper part of coat layer (drying temperature: low temperature)
11 Dry air suction pipe
12 Coating body
13 Exhaust cyclone
14 Spray nozzle
15 Current carrier
16 Temperature sensor
17 Rotating disc version
18 Dispersion tank
19 Intake blower
20 Humidity control device
21 Collection container
22 disc drive motor
31 Auto feeder
32 Sintering furnace
33 Discharge port

Claims (19)

Using a combined fluidized bed granulator comprising at least a granulation cylinder, a rotating disk plate provided substantially horizontally on the bottom surface in the vicinity of the cylinder bottom, and a spray nozzle for spraying coat droplets provided on the cylinder side wall, The carrier base particles are supplied into the granulation cylinder, the rotating disk plate is rotated, and air is fed from both the upper part and the lower part of the apparatus so that the carrier is rotated in the direction of rotation of the disk plate made of carrier base particles. Production of a carrier for an electrophotographic developer that forms a fluidized bed in which the matrix particles advance and swirls, and then sprays coating layer-forming droplets from the spray nozzle to form a coating layer on the surface of the carrier matrix particles and dry it. In the method, the coating layer forming liquid is mainly composed of a silicone resin, a conductive powder, and a solvent. An electrophotographic developer characterized in that aggregates of conductive powder exist in different states on the surface side of the coating layer and on the carrier base particle side by gradually lowering from the first set temperature to the second set temperature. Carrier manufacturing method . The method for producing a carrier for an electrophotographic developer according to claim 1, wherein the difference between the first set temperature and the second set temperature is 20 ° C to 40 ° C. The atmosphere temperature in the apparatus is set to (T-10 to T-50) ° C when the boiling point of the solvent constituting the coating layer forming liquid is T ° C. A method for producing a carrier for an electrophotographic developer . When the coating layer forming liquid contains a catalyst and the silicone resin contained in the coating layer forming liquid is a thermosetting type, and the lower limit temperature of the curing is S ° C., the drying temperature after coating is (S-20 to 20). The method for producing a carrier for an electrophotographic developer according to any one of claims 1 to 3, wherein the carrier is dried at a drying atmosphere temperature of S-50) ° C. The above (Ds / Dc) is 1/3 to 1/25, where Dc is the average particle size of the carrier base particles and Ds is the average particle size of the coating layer forming droplets sprayed from the spray nozzle. A method for producing a carrier for an electrophotographic developer according to any one of claims 1 to 4 . The method for producing a carrier for an electrophotographic developer according to any one of claims 1 to 5, wherein the spraying is performed under a condition in which a relationship between a spray pressure and a spray air flow rate is represented by the following formula.

    X: Spray air pressure (Kg / cm ² )
    (X is 2.0 to 6.5)
    Y: Spray air flow rate (L / min) A coating layer is formed from a spray nozzle in the same direction as the traveling direction of the carrier base particles and in the range of + 5 ° to −40 ° with respect to the horizontal line with respect to the carrier base particles forming a fluidized bed by rolling motion with centrifugal stirring. The method for producing a carrier for an electrophotographic developer according to claim 1, wherein droplets are sprayed . 8. The electrophotographic developer according to claim 1, wherein the spray nozzle is installed at a portion where the swirling fluidized bed made of carrier base particles is in contact with the inner wall of the apparatus and at the center of the fluidized bed. Carrier manufacturing method . Adjust spraying droplets so that the spray height is 1/7 to 1/2 of the carrier base particle soaring height (both spray height and soaring height are based on the disk surface) The method for producing a carrier for an electrophotographic developer according to any one of claims 1 to 8, wherein the carrier is an electrophotographic developer . The carrier for an electrophotographic developer according to any one of claims 1 to 9, wherein the pressure in the composite fluidized bed granulator is in the range of 0 to 50 Pa when the atmospheric pressure is 0 Pa. Manufacturing method . A carrier for an electrophotographic developer, characterized in that a carrier having a coating layer on its surface (referred to as a coated carrier) produced by the method according to any one of claims 1 to 10 is sintered in a drying sintering furnace. Manufacturing method . The carrier for an electrophotographic developer according to claim 11, wherein the drying sintering furnace is a rotary cylindrical mold, and the moving speed of the coated carrier in the drying sintering furnace is 40 to 110 mm / min. Manufacturing method . Using a rotary cylindrical type drying sintering furnace divided into three independent heating zones from the entrance, the actual powder temperature in the inlet heating zone is B1 ° C, the actual powder temperature in the central heating zone is B2 ° C, When the actual powder temperature in the heating zone at the outlet is B3 ° C., the actual powder temperature is set so as to satisfy the relationship expressed by the following (Equation 1), and the dry sintering furnace is rotated to sinter the coated carrier. The method for producing a carrier for an electrophotographic developer according to claim 11, wherein:

Inlet powder temperature: B1 ℃
Central real powder temperature: B2 ℃
Outlet real powder temperature: B3 ℃ The method for producing a carrier for an electrophotographic developer according to claim 13, wherein the temperature difference between B1 and B2 is 5 to 80 ° C. The cross-linking agent is contained in the coating layer of the coated carrier, and when the boiling point of the cross-linking agent is F ° C, it is sintered under the conditions represented by the following (formula 2). The manufacturing method of the carrier for electrophotographic developers as described in 1 ..

At the entrance of the drying sintering furnace heating zone, the temperature of the carrier after the coating resin treatment introduced at the start of the sintering treatment and before the drying sintering and the temperature of the carrier after the coating resin treatment introduced at the end of the sintering treatment and before the drying sintering The method for producing a carrier for an electrophotographic developer according to any one of claims 12 to 15, wherein the difference is treated at 100 ° C or less . The drying sintering furnace is a rotary cylindrical mold having a polygonal shape, and the coated carrier in the rotary furnace is advanced to the discharge side while causing a side slip by an avalanche phenomenon. The manufacturing method of the carrier for electrophotographic developers in any one . The carrier for an electrophotographic developer according to any one of claims 11 to 17, wherein the drying sintering furnace is a rotary cylindrical mold, and the pressure in the drying sintering furnace is controlled to 0 to -150 mmHg. Manufacturing method . 19. A carrier for an electrophotographic developer, wherein the coated carrier sintered in a dry sintering furnace is cooled at a cooling rate of 5 ° C./min or less by the method according to claim 11. Manufacturing method .

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