JP3862199B2 - Two-component developer for electrostatic charge development - Google Patents

Description

【００１０】
【化２】

[式中、Ｒ₁は４級炭素、メチン、メチレンであり、Ｎ、Ｓ、Ｏ、Ｐのヘテロ原子を含んでもよく、Ｙは飽和結合又は不飽和結合で結ばれた環状構造を表わし、Ｒ₂、Ｒ₃は相互に独立してアルキル基、アルケニル基、アルコキシ基、置換基を有してもよいアリール基又はアリールオキシ基又はアラルキル基又はアラルキルオキシ基、ハロゲン基、水素、水酸基、置換基を有してもよいアミノ基、カルボキシル基、カルボニル基、ニトロ基、ニトロソ基、スルホニル基、シアノ基を表わし、Ｒ₄は水素又はアルキル基を表わし、ｌは０又は３〜１２の整数、ｍは１〜２０の整数、ｎは０〜２０の整数、ｏは０〜４の整数、ｐは０〜４の整数、ｑは０〜３の整数、ｒは１〜２０の整数、ｓは０〜２０の整数を表わす。]
【００１１】
本発明者らの検討によれば、２成分現像剤において、５μｍ以下のトナーを多く含んだ小粒径トナーを用い、なお且つ経時で地肌汚れの良好な画像を得るためには、磁性体が該トナー中に１３〜２８重量％含有されることが必要であることが判明した。二成分現像剤における磁性体含有の効果は、磁気バイアス効果により充分に帯電していない弱帯電トナーを現像せずに、地肌汚れの発生を抑制しているものと考えられる。ここで、磁性体量が１３重量％未満のときは、磁気バイアス効果が不十分で磁性体含有による地肌汚れへの効果が見られず、また、２８重量％より多い場合は、磁気バイアスの効果が大きすぎて現像能力が極端に落ち、画像濃度の点で不具合が見られた。
【００１２】
また、本発明者らの検討によれば、ドット再現性の良い画像を得るには、５μｍ以下の小粒径トナーの寄与率が非常に高いことが判明した。ここで、トナー粒子が４０個数％未満の場合は、ドット再現性及び画像濃度が劣り鮮明な画像が得られず、８０個数％を超えると、トナー粒子相互の凝集状態が生じ易く、本来の粒径以上のトナー塊となるため、流動性が悪化し、荒れた画質となり、解像性を低下させるのみではなく、地肌汚れが極端に悪化する等の欠点を有していた。好ましくは５０〜７０個数％の範囲が最もよい。ここで、トナー体積平均粒径、体積分布の標準偏差、変動係数、５μｍ以下の個数％の測定は、種々の方法によって測定可能であるが、本発明では米国コールター・エレクトロニクス社製のコールターカウンターＴＡIIを用いた。
【００１３】
また、体積平均粒径（Ｍ）のトナーは、その内の、２＜トナー粒径＜Ｍ＋２（μｍ）の範囲内にあるトナー粒子が、上記の式を満たす場合に、小粒径トナーの使用においても経時で流動性が悪化し難く、ドット再現性等の画像品質が良好で、なお且つ地肌汚れが良好であることを見い出した。ここで、平均円形度（ＳＦ１）はトナー表面の滑らかさを表わす形状指数で、トナー表面が滑らかで円（球）形に近いほど１．００に近い値になるものである。この形状指数が０．９４０以上、より好ましくは０．９４４以上のときは、トナー表面が充分に滑らかなため、トナー粒子自体が持っている流動性が向上し、トナー小粒径化による流動性悪化に起因した帯電量低下に伴う地肌汚れが改善されることが判明し、該小粒径トナーの使用が充分可能であることが見い出された。このことは、トナー円形度の特定の値が小粒径トナー使用の分岐点になっていると考えられる。なお、前記形状指数の測定は、東亞医用電子株式会社製、ＦＰＩＡ−１０００フロー式粒子像分析装置を用いた画像解析により求められる。
【００１４】
また、本発明の磁性トナーは、５μｍ以下の粒子が多いことから、小粒径トナー中への帯電制御剤の分散性が地肌汚れ改善のためには必要とされ、前記構造式を有するジルコニウム系化合物を帯電制御剤として用いることにより、従来の帯電制御剤に比べて樹脂中での分散性が適度に良好なことから、小粒径トナー中へも適度の分散が行なわれ、帯電が安定化され、前記欠点の地肌汚れ等が解消できることが判明した。
【００１５】
また、特に前記静電潜像現像剤が機内リサイクル手段を搭載した画像形成装置に用いられることにより、リサイクルされたトナーの帯電量が低下されにくいことから、５μｍ以下の粒子が多い該トナーの使用においても、地肌汚れ等の発生の問題が無く、良好な画質が得られることが判明した。
【００１６】
次に本発明のトナーに用いられる材料について詳細に説明する。
本発明に使用される結着樹脂としては、ポリスチレン、ポリ−ｐ−クロロスチレン、ポリビニルトルエンなどのスチレン及びその置換体の単重合体；スチレン−ｐ−クロロスチレン共重合体、スチレン−プロピレン共重合体、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−アクリル酸メチル共重合体、スチレン−アクリル酸エチル共重合体、スチレン−アクリル酸ブチル共重合体、スチレン−アクリル酸オクチル共重合体、スチレン−メタクリル酸メチル共重合体、スチレン−メタクリル酸エチル共重合体、スチレン−メタクリル酸ブチル共重合体、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、スチレン−マレイン酸共重合体、スチレン−マレイン酸エステル共重合体などのスチレン系共重合体が挙げられる。
また、下記の樹脂を混合して使用することもできる。ポリメチルメタクリレート、ポリブチルメタクリレート、ポリ塩化ビニル、ポリ酢酸ビニル、ポリエチレン、ポリプロピレン、ポリエステル、ポリウレタン、ポリアミド、エポキシ樹脂、ポリビニルブチラール、ポリアクリル酸樹脂、ロジン、変性ロジン、テルペン樹脂、フェノール樹脂、脂肪族又は脂環族炭化水素樹脂、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が挙げられる。
【００１７】
また、特に圧力定着用に好適な結着樹脂としては下記のものを挙げることができ、混合して使用できる。
ポリオレフィン（低分子量ポリエチレン、低分子量ポリプロピレン、酸化ポリエチレンポリ４弗化エチレンなど）、エポキシ樹脂、ポリエステル樹脂、スチレン−ブタジエン共重合体（モノマー比５〜３０：９５〜７０）、オレフィン共重合体（エチレン−アクリル酸共重合体、エチレン−アクリル酸エステル共重合体、エチレン−メタクリル酸共重合体、エチレン−メタクリル酸エステル共重合体、エチレン−塩化ビニル共重合体、エチレン−酢酸ビニル共重合体、アイオノマー樹脂）、ポリビニルピロリドン、メチルビニルエーテル−無水マレイン酸共重合体、マレイン酸変性フェノール樹脂、フェノール変性テルペン樹脂等。
【００１８】
更に、本発明の磁性トナーは着色剤の役割を兼ねても良いが、磁性材料を含有している。本発明の磁性トナー中に含まれる磁性材料としては、マグネタイト、ヘマタイト、フェライト等の酸化鉄、鉄、コバルト、ニッケルのような金属あるいはこれら金属のアルミニウム、コバルト、銅、鉛、マグネシウム、スズ、亜鉛、アンチモン、ベリリウム、ビスマス、カドミウム、カルシウム、マンガン、セレン、チタン、タングステン、バナジウムのような金属の合金およびその混合物などが挙げられる。これらの強磁性体は平均粒径が０．１〜２μｍ程度のものが望ましい。
【００１９】
帯電制御剤としては、ニグロシン染料、金属錯塩型染料、第四級アンモニウム塩等の従来公知のいかなる極性制御剤も、ジルコニウム系化合物と混合して使用できる。これらの極性制御剤の使用量は、トナー樹脂成分に対し、０．１〜１０重量部、好ましくは１〜５重量部である。
【００２０】
なお、本発明のジルコニウム化合物の一般的製法は、水又は／及び有機溶剤を用い、金属付与剤を用いて反応させ生成物を濾取して洗浄することによって得ることができる。本発明の化合物の製造に用いることができる金属付与剤としては、４価の陽イオン体の場合はＺｒＣｌ₄、ＺｒＦ₄、ＺｒＢｒ₄、ＺｒＩ₄等のハロゲン化ジルコニウム化合物、Ｚｒ（ＯＲ）₄ （Ｒはアルキル基、アルケニル基等を示す）、又はＺｒ（ＳＯ₄）₂等の無機ジルコニウム化合物等が挙げられる。オキソ化合物の２価の陽イオン体の場合はＺｒＯＣｌ₂、ＺｒＯ（ＮＯ₃）₂、ＺｒＯ（ＣｌＯ₄）₂、Ｈ₂ＺｒＯ（ＳＯ₄）₂、ＺｒＯ（ＳＯ₄）・Ｎａ₂ＳＯ₄、ＺｒＯ（ＨＰＯ₄）₂等の無機酸ジルコニウム化合物、ＺｒＯ（ＣＯ₃）、（ＮＨ₄）₂ＺｒＯ（ＣＯ₃）₂、（ＮＨ₄）₂ＺｒＯ（Ｃ₂Ｈ₃Ｏ₂）₂、ＺｒＯ（Ｃ₂Ｈ₃₅Ｏ₂）₂、ＺｒＯ（Ｃ₁₈Ｈ₃₅Ｏ₂）₂等の有機酸ジルコニム化合物等が挙げられる。
【００２１】
また、本発明に用いられる疎水性無機微粉末としては、公知のものを用いることができるが、疎水性シリカ微粉末、疎水性チタン微粉末等が好ましい。また、本発明で用いられる疎水性シリカ粒子は、公知のものが使用できる。シランカップリング剤、シリコーンワニス、シリコーンオイル、有機ケイ素化合物又は官能基を有するこれらの物質などの疎水化処理剤としては、例えばヘキサメチルジシラザン、ヘキサメチレンジシラザン、トリメチルシラン、トリメチルクロルシラン、トリメチルエトキシシラン、ジメチルジクロルシラン、メチルトリクロルシラン、ベンジルジメチルクロルシラン、クロルメチルジメチルクロルシラン、ジクロロジメチルシラン、トリオルガノシリルメルカプタン、トリメチルシリルメルカプタン、ビニルジメチルアセトキシシラン、ジメチルエトキシシラン、ジメチルジメトキシシラン、ジフェニルジエトキシシラン、アミノプロピルトリメトキシシラン、ジプロピルアミノプロピルトリメトキシシラン、ジブチルアミノプロピルトリメトキシシラン、ジブチルアミノプロピルメチルジメトキシシラン、トリメトキシシリル−γ−プロピルフェニルアミン等がある。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、アミノ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等がある。これらは１種或いは２種以上の混合物で用いられる。以上のような処理においては単一の処理或いは種々の処理を併用してもよい。
【００２２】
また、本発明で用いられる疎水性チタン粒子は、公知のものが使用できる。表面処理剤としては、メチルハイドロジェンポリシロキサン、ジメチルポリシロキサン、メチルフェニルポリシロキサン等の各種のシリコーンオイル、メチルトリメトキシシラン、エチルトリメトキシシラン、ヘキシルトリメトキシシラン、オクチルトリメトキシシラン、デシルトリメトキシシラン、オクタデシルトリメトキシシラン、ジメチルジメトキシシラン、オクチルトリエトキシシラン、ｎ-オクタデシルジメチル（３−（トリメトキシシリル）プロピル）アンモニウムクロライド等の各種のアルキルシラン、トリフルオロメチルエチルトリメトキシシラン、ヘプタデカフルオロデシルトリメトキシシラン等の各種のフルオロアルキルシラン、特にビニルトリメトキシシラン、γ−アミノプロピルトリメトキシシラン等のシランカップリング剤に代表されるシラン系・チタン系・アルミ系・アルミナ−ジルコニア系等の各金属系カップリング剤のいすれの処理剤も使用可能であり、これらを２種以上を混合している。
【００２３】
また、本発明のトナーは、必要に応じて添加物を混合してもよい。添加物としては、例えばテフロン（商品名）、ステアリン酸亜鉛のごとき滑剤あるいは酸化セリウム、炭化ケイ素等の研磨剤、あるいは例えばコロイダルシリカ、酸化アルミニウムなどの流動性付与剤、ケーキング防止剤、あるいは例えばカーボンブラック、酸化スズ等の導電性付与剤、あるいは低分子量ポリオレフィンなどの定着助剤等がある。
【００２４】
着色剤としては、トナー用として公知のものが使用できる。黒色の着色剤としては、例えば、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は、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は、例えば、ローダミン６Ｇレーキ、ジメチルキナクリドン、ウォッチングレッド、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は、例えば、クロムイエロー、ベンジジンイエロー、ハンザイエロー、ナフトールイエロー、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。
【００２５】
本発明に使用し得るキャリアとしては、公知のものが使用可能であり、例えば鉄粉、フェライト粉、ニッケル粉のごとき磁性を有する粉体、ガラスビーズ等及びこれらの表面を樹脂などで処理したものなどが挙げられる。
【００２６】
本発明におけるキャリアにコーティングし得る樹脂粉末としては、スチレン−アクリル共重合体、シリコーン樹脂、マレイン酸樹脂、フッ素系樹脂、ポリエステル樹脂、エポキシ樹脂等がある。スチレン−アクリル共重合体の場合は、３０〜９０重量％のスチレン分を有するものが好ましい。この場合スチレン分が３０重量％未満だと現像特性が低く、９０重量％を超えるとコーティング膜が硬くなって剥離しやすくなり、キャリアの寿命が短くなるからである。
また、本発明におけるキャリアの樹脂コーティングは、上記樹脂の他に接着付与剤、硬化剤、潤滑剤、導電材、荷電制御剤等を含有してもよい。
【００２７】
【発明の実施の形態】
以下、本発明を実施例によってさらに具体的に説明するが、本発明はこれらに限定されるものではない。なお、評価装置は、トナー機内リサイクル手段を搭載した（株）リコー製ＭＦ−２５０を用いた。また、部数はすべて重量部である。
各実施例のスタート時と１４万枚後の評価結果の平均を以下に示す評価に基いて行なった。結果を表１に示す。
【００２８】
評価方法
（地肌汚れ）
白色原稿を用いてＡ３サイズで出力し、その画像の任意の６個所の位置の画像濃度を、マクベス反射濃度計で測定し、そのＩＤについて以下の判断基準により５段階で行なった。なお、全く地肌汚れが無い状態は、紙の反射濃度と同等な値であり、その値が大きいほど地肌汚れは悪い結果となっている。
良 ◎：大変良い、○：良い、□：普通、△：悪い、×：大変悪い 悪
【００２９】
（ベタ均一性（画像濃度））
一部のベタ部を前後左右に各６点持ったＡ３サイズのチャートを用いて画像をＡ３サイズで出力し、その画像のベタ部６個所の位置の画像濃度を、マクベス反射濃度計で測定し、そのＩＤ偏差について以下の判断基準により５段階で行なった。
良 ◎：大変良い、○：良い、□：普通、△：悪い、×：大変悪い 悪
【００３０】
（ドット再現性）
ドット再現性の評価を行った。評価は、以下の判断基準により５段階で行なった。
良 ◎：大変良い、○：良い、□：普通、△：悪い、×：大変悪い 悪
【００３１】
ジルコニア系化合物１
３，５−ジ−ｔ−ブチルサリチル酸とジルコニウム化合物との反応により得られたジルコニア系化合物をジルコニア系化合物１とする。
【００３２】
ジルコニア系化合物２〜３
同様にして得られたジルコニア系化合物の例を以下に示すが、これらに限定されるものではない。
【００３３】
ジルコニア系化合物２：
配位子
【００３４】
【化３】

金属付与剤：ＺｒＯＣｌ₂
配位子：金属付与剤＝５：４
【００３５】
ジルコニア系化合物３：
配位子
【００３６】
【化４】

金属付与剤：Ｚｒ（ｉ−ＰｒＯ）₄
配位子：金属付与剤＝４：１
【００３７】
次に、本実施例等に用いるシリコーン樹脂を被覆層に有するキャリアの製造例を示す。これは公知の手段により行なうことができる。
【００３８】

上記処方をホモミキサーで３０分間分散して被覆層形成液を調製した。この被覆層形成液を平均粒径１００μｍの球状フェライト１０００重量部の表面に流動床型塗布装置を用いて被覆層を形成したキャリアＡを得た。
【００３９】
実施例１〜３、比較例１〜４

【００４０】
上記組成の混合物をヘンシェルミキサー中で充分撹拌混合した後、ロールミルで１３０〜１４０℃の温度で約３０分間加熱溶融し、室温まで冷却後、得られた混練物をジェットミル又は機械式粉砕機、風力分級機で粉砕分級し、所定の粒径及び円形度のトナー母体を得た。このときの粒径、粒径分布、円形度の値はジェットミル中の滞留時間又は機械式粉砕機の使用及び風力分級機の条件の変更により変化させた。得られたトナー母体に疎水性シリカ０．５重量％添加混合し、最終的なトナーとした。
【００４１】
このトナー１３．０部に対し、上記キャリアＡ８７．０部とをボールミルで混合し現像剤を得た。この現像剤に前記ＭＦ−２５０を用いて複写実験を行なった結果を表１に示す。
【００４２】
比較例５
実施例１のトナー中、ジルコニア系化合物を含金属アゾ化合物に変更した事以外は実施例１と同様に実験を行なった。
【００４３】
比較例６
実施例１のトナー中、マグネタイト微粒子を７５部（４１．４重量％）とした事以外は実施例１と同様に実験を行なった。
【００４４】
比較例７
実施例１のトナー中、マグネタイト微粒子を１０部（８.２重量％）としたこと以外は実施例１と同様に実験を行なった。
【００４５】
【表１】

【００４６】
【発明の効果】
以上、詳細かつ具体的な説明より明らかなように、本発明の磁性二成分現像剤に用いるトナーであって、特定の粒径と円形度の範囲を満足し、構造式を有するジルコニア系化合物を含有するものを用いることで、コピー経時でも高画質を有し、地肌汚れの発生を低減させた高画質な画像を得ることができる静電荷現像用二成分現像剤を提供できるという優れた効果を奏する。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electrostatic charge developing toner, an image forming method, and an image forming apparatus used in electrophotography, electrostatic printing, and the like.
[0002]
[Prior art]
The dry two-component developer used in the two-component development method is such that minute toner particles are held on the surface of relatively large particles by the electric force generated by the friction between the two particles. The attracting force in the direction of the latent image with respect to the toner particles due to the electric field force formed by the electrostatic latent image overcomes the binding force between the toner particles and the carrier particles, and the toner particles are attracted and adhered onto the electrostatic latent image. The image is visualized. The developer is repeatedly used while replenishing the toner consumed by the development.
[0003]
At this time, when toner that is not sufficiently charged or weakly charged toner that is slightly reversely charged is generated, the toner particles are developed in a place other than the image portion where the electrostatic latent image is formed. Occurrence of a so-called background stain phenomenon or the like is seen and is regarded as a problem. As countermeasures, measures such as sharpening the charge amount distribution have been made. Initially, good images can be obtained, but over time, especially in machines equipped with in-flight recycling means, in-flight recycling is restored. Due to the lowering of the charging ability of the toner, phenomena such as deterioration of the background stain compared to the initial stage were observed. This phenomenon is particularly noticeable and problematic in relatively soft low-temperature fixing toners using a polyester resin or the like used for energy saving.
[0004]
In recent years, toners used in electrophotographic development methods have been increasingly demanded for image quality, and are moving toward smaller particle sizes. An image forming apparatus using a digital image signal forms an image by forming a latent image of minute dots on a photosensitive member and developing the latent image. At this time, if the particle diameter of the toner is large, the toner protrudes from the latent image dots, and there is a problem in that dots are not formed faithfully to the latent image and a high-quality image cannot be obtained.
[0005]
In order to solve this problem, toner having a particle size of 5 μm or less is an indispensable component for forming a high-quality image, and a technique for using this toner has been devised. As a typical example, a toner having a small particle diameter is used by defining the range of the toner particle diameter described in JP-B-7-60273, and 17 to 60% by number of magnetic toner particles of 5 μm or less are used. Some have aimed to improve image quality by defining the range.
However, the method is limited to a one-component magnetic toner containing a large amount of magnetic substance in content, and in the use of a two-component development process as in the present invention, the sharpness of the image, particularly In terms of image density, it was not sufficient, and there was a problem in terms of compatibility with background stains.
The technique described in Japanese Patent No. 2776949 aims to improve the image by increasing the number of particles of 5 μm or less to 60% by number or more. By making the distribution relatively sharp, it is possible to obtain a high-quality image, which is problematic in terms of productivity in producing a toner with a sharp distribution, and magnetically This is a one-component magnetic toner containing a large amount of body, and when used in two-component development, there is a problem that it is not sufficient in terms of image sharpness, particularly in terms of image density.
Japanese Patent Publication No. 6-93136 discloses a magnetic toner that defines a particle size distribution and contains a carbon allotrope. This method is a one-component containing a large amount of magnetic substance. In the use of a two-component development process as in the present invention, it is not sufficient in terms of image sharpness, particularly in terms of image density, and is compatible with background stains. There was a problem in that. In any case, in the use of a toner having a small particle size for achieving high image quality, there is an urgent need to solve the problem of background contamination.
[0006]
In addition, when dry toner is manufactured by a pulverization method, the shape is angular and irregular, and therefore, the flowability is inferior to spherical toners such as polymerized toners, and in particular to achieve high image quality. As mentioned above, due to the remarkable deterioration in fluidity due to the reduction in particle size, the occurrence of defects such as deterioration of the background stain due to the presence of insufficiently charged toner as described above was observed. It was.
[0007]
[Problems to be solved by the invention]
An object of the present invention is to provide a developer for developing an electrostatic charge that can solve the above problems and obtain a high-quality image.
[0008]
[Means for Solving the Problems]
As a result of intensive studies, the present inventors have found that in a magnetic two-component developer comprising a magnetic toner having at least a binder resin, magnetic powder and hydrophobic silica fine powder, and a carrier, the magnetic material is 13 to 28 in the magnetic toner. Toner having a volume average particle size (M) of 40% to 80% by weight, containing 40% by weight of toner particles having a volume average particle size M (μm) of 4 to 8 μm, and having a particle size of 5 μm or less. It is of which, containing 2 <toner particles in the range of toner particle size <M + 2 ([mu] m) is, fulfills the value represented by the following formula, the magnetic toner of the zirconium-based compound having the following structural formula In addition, it has been found that the above-mentioned drawback can be eliminated by using an electrostatic charge developing developer characterized in that the developer is used in an image forming apparatus equipped with in-machine recycling means.
[0009]
[Expression 2]

[0010]
[Chemical 2]

[Wherein R ₁ is quaternary carbon, methine, methylene, and may contain a heteroatom of N, S, O, P, Y represents a cyclic structure connected by a saturated bond or an unsaturated bond, R ₂ and R ₃ are each independently an alkyl group, an alkenyl group, an alkoxy group, an aryl group or an aryloxy group or an aralkyl group or an aralkyloxy group which may have a substituent, a halogen group, hydrogen, a hydroxyl group or a substituent. Represents an amino group, a carboxyl group, a carbonyl group, a nitro group, a nitroso group, a sulfonyl group or a cyano group, R ₄ represents hydrogen or an alkyl group, l is 0 or an integer of 3 to 12, m Is an integer from 1 to 20, n is an integer from 0 to 20, o is an integer from 0 to 4, p is an integer from 0 to 4, q is an integer from 0 to 3, r is an integer from 1 to 20, and s is 0 Represents an integer of ~ 20. ]
[0011]
According to the study by the present inventors, in order to obtain a good image of background stains over time using a small particle size toner containing a large amount of toner of 5 μm or less in a two-component developer, a magnetic material is used. It has been found necessary to contain 13 to 28% by weight in the toner . The effect of containing a magnetic substance in the two-component developer is considered to suppress the occurrence of background stains without developing weakly charged toner that is not sufficiently charged due to the magnetic bias effect. Here, when the amount of the magnetic material is less than 13% by weight, the magnetic bias effect is insufficient and the effect on the background stain due to the inclusion of the magnetic material is not seen. Is too large, the developing ability is extremely lowered, and a defect is observed in terms of image density.
[0012]
Further, according to the study by the present inventors, it has been found that the contribution ratio of a small particle size toner of 5 μm or less is very high in order to obtain an image with good dot reproducibility. Here, when the toner particles are less than 40% by number, the dot reproducibility and the image density are inferior, and a clear image cannot be obtained. Since the toner lump is larger than the diameter, the fluidity is deteriorated, the image quality becomes rough, and not only the resolution is lowered, but also the background stain is extremely deteriorated. A range of 50 to 70% by number is preferable. Here, the toner volume average particle diameter, the standard deviation of the volume distribution, the coefficient of variation, the number% of 5 μm or less can be measured by various methods. In the present invention, the Coulter Counter TAII manufactured by Coulter Electronics, Inc. of the United States is used. Was used.
[0013]
Further, the toner having a volume average particle diameter (M), of which, 2 <toner particles in the range of toner over particle size <M + 2 ([mu] m) is, if it meets the above formula, the small particle size toner In use, it was found that the fluidity hardly deteriorates with time, the image quality such as dot reproducibility was good, and the background stain was good. Here, the average circularity (SF1) is a shape index representing the smoothness of the toner surface, and becomes closer to 1.00 as the toner surface becomes smoother and closer to a circle (sphere). When the shape index is 0.940 or more, and more preferably 0.944 or more, the toner surface itself is sufficiently smooth, so that the fluidity of the toner particles themselves is improved, and the fluidity by reducing the toner particle size is reduced. It has been found that the background stain due to the decrease in the charge amount due to the deterioration is improved, and it has been found that the use of the toner having a small particle diameter is sufficiently possible. This is considered that the specific value of the toner circularity is a branching point for using the toner having a small particle diameter. The shape index can be measured by image analysis using a FPIA-1000 flow type particle image analyzer manufactured by Toago Medical Electronics Co., Ltd.
[0014]
Further, since the magnetic toner of the present invention has a large number of particles of 5 μm or less, the dispersibility of the charge control agent in the toner having a small particle diameter is required to improve the background stain, and the zirconium series having the above structural formula By using the compound as a charge control agent, the dispersibility in the resin is reasonably good compared to conventional charge control agents. As a result, it has been found that the above-mentioned defects such as background stains can be eliminated.
[0015]
In particular, since the electrostatic latent image developer is used in an image forming apparatus equipped with an in-machine recycling means, the amount of charged recycled toner is unlikely to be reduced. Also, it was found that good image quality can be obtained without causing problems such as background stains.
[0016]
Next, materials used for the toner of the present invention will be described in detail.
Examples of the binder resin used in the present invention include styrene such as polystyrene, poly-p-chlorostyrene, and polyvinyltoluene, and a homopolymer of a substituted product thereof; styrene-p-chlorostyrene copolymer, styrene-propylene copolymer Polymer, styrene-vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-octyl acrylate Copolymer, styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, styrene-α-chloromethyl methacrylate copolymer, styrene-acrylonitrile copolymer, Styrene-vinyl methyl ether copolymer, styrene Vinyl ethyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-acrylonitrile-indene copolymer, styrene-maleic acid copolymer, styrene-maleic Examples thereof include styrenic copolymers such as acid ester copolymers.
Moreover, the following resin can also be mixed and used. Polymethyl methacrylate, polybutyl methacrylate, polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene, polyester, polyurethane, polyamide, epoxy resin, polyvinyl butyral, polyacrylic acid resin, rosin, modified rosin, terpene resin, phenol resin, aliphatic Or an alicyclic hydrocarbon resin, an aromatic petroleum resin, chlorinated paraffin, paraffin wax, etc. are mentioned.
[0017]
In addition, examples of the binder resin particularly suitable for pressure fixing include the following, which can be used in combination.
Polyolefin (low molecular weight polyethylene, low molecular weight polypropylene, polyethylene oxide polytetrafluoroethylene, etc.), epoxy resin, polyester resin, styrene-butadiene copolymer (monomer ratio 5-30: 95-70), olefin copolymer (ethylene -Acrylic acid copolymer, ethylene-acrylic acid ester copolymer, ethylene-methacrylic acid copolymer, ethylene-methacrylic acid ester copolymer, ethylene-vinyl chloride copolymer, ethylene-vinyl acetate copolymer, ionomer Resin), polyvinylpyrrolidone, methyl vinyl ether-maleic anhydride copolymer, maleic acid-modified phenol resin, phenol-modified terpene resin, and the like.
[0018]
Further, the magnetic toner of the present invention may serve as a colorant, but contains a magnetic material. Examples of the magnetic material contained in the magnetic toner of the present invention include iron oxides such as magnetite, hematite, and ferrite, metals such as iron, cobalt, and nickel, or aluminum, cobalt, copper, lead, magnesium, tin, and zinc of these metals. And alloys of metals such as antimony, beryllium, bismuth, cadmium, calcium, manganese, selenium, titanium, tungsten, vanadium, and mixtures thereof. These ferromagnetic materials preferably have an average particle size of about 0.1 to 2 μm.
[0019]
As the charge control agent, any conventionally known polarity control agent such as a nigrosine dye, a metal complex dye, or a quaternary ammonium salt can be used by mixing with a zirconium compound. The amount of these polar control agents used is 0.1 to 10 parts by weight, preferably 1 to 5 parts by weight, based on the toner resin component.
[0020]
In addition, the general manufacturing method of the zirconium compound of this invention can be obtained by using water or / and an organic solvent, making it react with a metal provision agent, and filtering and wash | cleaning a product. In the case of a tetravalent cation, the metal-imparting agent that can be used for the production of the compound of the present invention is a halogenated zirconium compound such as ZrCl ₄ , ZrF ₄ , ZrBr ₄ , ZrI ₄ , Zr (OR) ₄ ( R represents an alkyl group, an alkenyl group, or the like), or an inorganic zirconium compound such as Zr (SO ₄ ) ₂ . In the case of a divalent cation of an oxo compound, ZrOCl ₂ , ZrO (NO ₃ ) ₂ , ZrO (ClO ₄ ) ₂ , H ₂ ZrO (SO ₄ ) ₂ , ZrO (SO ₄ ) · Na ₂ SO ₄ , ZrO Inorganic acid zirconium compounds such as (HPO ₄ ) ₂ , ZrO (CO ₃ ), (NH ₄ ) ₂ ZrO (CO ₃ ) ₂ , (NH ₄ ) ₂ ZrO (C ₂ H ₃ O ₂ ) ₂ , ZrO (C ₂ And organic acid zirconium compounds such as H ₃₅ O ₂ ) ₂ and ZrO (C ₁₈ H ₃₅ O ₂ ) ₂ .
[0021]
As the hydrophobic inorganic fine powder used in the present invention, known ones can be used, but hydrophobic silica fine powder, hydrophobic titanium fine powder and the like are preferable. Moreover, a well-known thing can be used for the hydrophobic silica particle used by this invention. Examples of hydrophobizing agents such as silane coupling agents, silicone varnishes, silicone oils, organosilicon compounds, or those having functional groups include hexamethyldisilazane, hexamethylenedisilazane, trimethylsilane, trimethylchlorosilane, and trimethyl. Ethoxysilane, dimethyldichlorosilane, methyltrichlorosilane, benzyldimethylchlorosilane, chloromethyldimethylchlorosilane, dichlorodimethylsilane, triorganosilylmercaptan, trimethylsilylmercaptan, vinyldimethylacetoxysilane, dimethylethoxysilane, dimethyldimethoxysilane, diphenyldi Ethoxysilane, aminopropyltrimethoxysilane, dipropylaminopropyltrimethoxysilane, dibutylaminopropylto Silane, dibutyl aminopropyl dimethoxysilane, there is trimethoxysilyl -γ- propylphenyl amine. Examples of the silicone oil include methyl silicone oil, dimethyl silicone oil, phenylmethyl silicone oil, chlorophenyl methyl silicone oil, alkyl-modified silicone oil, fatty acid-modified silicone oil, amino-modified silicone oil, and polyoxyalkyl-modified silicone oil. These are used alone or as a mixture of two or more. In the above processes, a single process or various processes may be used in combination.
[0022]
Moreover, the well-known thing can be used for the hydrophobic titanium particle used by this invention. Surface treatment agents include various silicone oils such as methyl hydrogen polysiloxane, dimethyl polysiloxane, and methylphenyl polysiloxane, methyltrimethoxysilane, ethyltrimethoxysilane, hexyltrimethoxysilane, octyltrimethoxysilane, and decyltrimethoxy. Various alkylsilanes such as silane, octadecyltrimethoxysilane, dimethyldimethoxysilane, octyltriethoxysilane, n-octadecyldimethyl (3- (trimethoxysilyl) propyl) ammonium chloride, trifluoromethylethyltrimethoxysilane, heptadecafluoro Various fluoroalkylsilanes such as decyltrimethoxysilane, especially silane cups such as vinyltrimethoxysilane and γ-aminopropyltrimethoxysilane Silane-titanium-based, aluminum-based, alumina represented by a ring agent - are also possible treatments of Isure of each metallic coupling agent zirconia such use, is mixed with two or more of these.
[0023]
Further, the toner of the present invention may be mixed with additives as necessary. Examples of additives include lubricants such as Teflon (trade name), zinc stearate, abrasives such as cerium oxide and silicon carbide, fluidity-imparting agents such as colloidal silica and aluminum oxide, anti-caking agents, and carbon such as carbon. Examples thereof include conductivity imparting agents such as black and tin oxide, and fixing aids such as low molecular weight polyolefins.
[0024]
As the colorant, those known for toners can be used. As the black colorant, for example, carbon black, aniline black, furnace black, lamp black and the like can be used. Examples of cyan colorants include phthalocyanine blue, methylene blue, Victoria blue, methyl violet, aniline blue, and ultramarine blue. As the magenta colorant, for example, rhodamine 6G lake, dimethylquinacridone, watching red, rose bengal, rhodamine B, alizarin lake and the like can be used. Examples of yellow colorants include chrome yellow, benzidine yellow, hansa yellow, naphthol yellow, molybdenum orange, quinoline yellow, and tartrazine.
[0025]
As the carrier that can be used in the present invention, known ones can be used. For example, magnetic powder such as iron powder, ferrite powder, nickel powder, glass beads, etc., and their surfaces treated with a resin or the like Etc.
[0026]
Examples of the resin powder that can be coated on the carrier in the present invention include a styrene-acrylic copolymer, a silicone resin, a maleic acid resin, a fluorine resin, a polyester resin, and an epoxy resin. In the case of a styrene-acrylic copolymer, those having a styrene content of 30 to 90% by weight are preferred. In this case, if the styrene content is less than 30% by weight, the development characteristics are low, and if it exceeds 90% by weight, the coating film becomes hard and easily peeled, and the life of the carrier is shortened.
Moreover, the resin coating of the carrier in the present invention may contain an adhesion-imparting agent, a curing agent, a lubricant, a conductive material, a charge control agent and the like in addition to the resin.
[0027]
DETAILED DESCRIPTION OF THE INVENTION
EXAMPLES Hereinafter, although an Example demonstrates this invention further more concretely, this invention is not limited to these. The evaluation device used was MF-250 manufactured by Ricoh Co., Ltd. equipped with a toner in-machine recycling means. All parts are parts by weight.
The average of the evaluation results at the start of each example and after 140,000 sheets was performed based on the following evaluation. The results are shown in Table 1.
[0028]
Evaluation method (background dirt)
A white document was output in A3 size, and the image density at arbitrary six positions of the image was measured with a Macbeth reflection densitometer, and the ID was determined in five stages according to the following criteria. The state where there is no background stain is a value equivalent to the reflection density of paper, and the larger the value, the worse the background stain.
Good ◎: Very good, ○: Good, □: Normal, △: Bad, ×: Very bad Evil [0029]
(Solid uniformity (image density))
Using an A3 size chart with 6 points of solid parts in the front, back, left, and right, an image is output in A3 size, and the image density at the position of the 6 solid parts of the image is measured with a Macbeth reflection densitometer. The ID deviation was determined in five stages according to the following criteria.
Good ◎: Very good, ○: Good, □: Normal, △: Bad, ×: Very bad Evil [0030]
(Dot reproducibility)
The dot reproducibility was evaluated. Evaluation was performed in five stages according to the following criteria.
Good ◎: Very good, ○: Good, □: Normal, △: Bad, ×: Very bad Evil [0031]
Zirconia compound 1
A zirconia compound obtained by the reaction of 3,5-di-t-butylsalicylic acid and a zirconium compound is referred to as zirconia compound 1.
[0032]
Zirconia compounds 2-3
Although the example of the zirconia type compound obtained similarly is shown below, it is not limited to these.
[0033]
Zirconia compound 2:
Ligand [0034]
[Chemical 3]

Metal imparting agent: ZrOCl ₂
Ligand: Metal imparting agent = 5: 4
[0035]
Zirconia compound 3:
Ligand [0036]
[Formula 4]

Metal imparting agent: Zr (i-PrO) ₄
Ligand: Metal imparting agent = 4: 1
[0037]
Next, the manufacture example of the carrier which has the silicone resin used for a present Example etc. in a coating layer is shown. This can be done by known means.
[0038]

The above formulation was dispersed with a homomixer for 30 minutes to prepare a coating layer forming solution. A carrier A in which the coating layer was formed on the surface of 1000 parts by weight of spherical ferrite having an average particle diameter of 100 μm by using a fluidized bed coating apparatus was obtained from this coating layer forming liquid.
[0039]
Examples 1-3, Comparative Examples 1-4

[0040]
The mixture having the above composition is sufficiently stirred and mixed in a Henschel mixer, heated and melted at a temperature of 130 to 140 ° C. for about 30 minutes with a roll mill, cooled to room temperature, and the obtained kneaded product is jet mill or mechanical pulverizer, By pulverizing and classifying with an air classifier, a toner base having a predetermined particle size and circularity was obtained. The values of the particle size, particle size distribution, and circularity at this time were changed by changing the residence time in the jet mill or the use of a mechanical pulverizer and the conditions of the air classifier. The resulting toner base was mixed with 0.5% by weight of hydrophobic silica to obtain a final toner.
[0041]
A developer was obtained by mixing 13.0 parts of this toner with 87.0 parts of carrier A by a ball mill. Table 1 shows the results of a copying experiment using MF-250 as the developer.
[0042]
Comparative Example 5
The experiment was performed in the same manner as in Example 1 except that the zirconia compound in the toner of Example 1 was changed to a metal-containing azo compound.
[0043]
Comparative Example 6
The experiment was performed in the same manner as in Example 1 except that 75 parts (41.4% by weight) of magnetite fine particles were used in the toner of Example 1.
[0044]
Comparative Example 7
The experiment was performed in the same manner as in Example 1 except that the amount of magnetite fine particles in the toner of Example 1 was 10 parts (8.2% by weight).
[0045]
[Table 1]

[0046]
【The invention's effect】
As described above, as is clear from the detailed and specific description, the toner used in the magnetic two-component developer of the present invention is a zirconia-based compound having a specific particle size and circularity range and having a structural formula. By using what it contains, it has an excellent effect that it can provide a two-component developer for electrostatic charge development that has a high image quality even with the lapse of time and can obtain a high-quality image with reduced generation of background stains. Play.

Claims (1)

In a magnetic two-component developer comprising a magnetic toner having at least a binder resin, magnetic powder and hydrophobic silica fine powder and a carrier, the magnetic toner is contained in the magnetic toner in an amount of 13 to 28% by weight, and the volume average particle diameter of the toner A toner having a volume average particle diameter (M) of 40 to 80% by number of toner particles satisfying M (μm) of 4 to 8 μm and having a particle diameter of 5 μm or less is 2 <toner particle diameter. The toner particles in the range of <M + 2 (μm) satisfy the value represented by the following formula, and the magnetic toner contains a zirconium-based compound having the following structural formula. A developer for developing an electrostatic charge, which is used in an image forming apparatus mounted thereon.

[Wherein R ₁ is quaternary carbon, methine, methylene, and may contain a heteroatom of N, S, O, or P; Y represents a cyclic structure connected by a saturated bond or an unsaturated bond; ₂ and R ₃ are each independently an alkyl group, an alkenyl group, an alkoxy group, an aryl group or an aryloxy group or an aralkyl group or an aralkyloxy group which may have a substituent, a halogen group, hydrogen, a hydroxyl group or a substituent. Represents an amino group, a carboxyl group, a carbonyl group, a nitro group, a nitroso group, a sulfonyl group, or a cyano group, R ₄ represents hydrogen or an alkyl group, l is 0 or an integer of 3 to 12, m Is an integer from 1 to 20, n is an integer from 0 to 20, o is an integer from 0 to 4, p is an integer from 0 to 4, q is an integer from 0 to 3, r is an integer from 1 to 20, and s is 0 Represents an integer of ~ 20. ]