JP4072411B2 - Dry magnetic toner - Google Patents

Description

【００７１】
磁性酸化鉄における表面の原子濃度は、測定された各元素のピーク強度より表面原子濃度を見積もり、その見積もった原子濃度から各原子の比率を算出することにより求められる。なお、表面原子濃度の計算には、アルバックファイ社提供の相対感度因子を用い、表面金属原子濃度の算出については、上記測定によって検出された全金属原子の原子濃度を１００％に換算した後、各金属原子の濃度を算出する方法を用いることができる。
【００７２】
（２）磁性酸化鉄中に存在する金属元素量の定量
本発明において、磁性酸化鉄中の鉄以外の金属元素の含有率（磁性酸化鉄を基準とする）は次のような方法によって求めることができる。例えば、５リットルのビーカーに約３リットルの脱イオン水を入れ、４５乃至５０℃になるようにウォーターバスで加温する。約４００ｍｌの脱イオン水でスラリーとした磁性酸化鉄約２５ｇを約３００ｍｌの脱イオン水で水洗いしながら、前記脱イオン水と共に５リットルビーカー中に加える。
【００７３】
次いで、温度を約５０℃、撹拌スピードを約３．３３ｓ^-1に保ちながら、特級塩酸又は塩酸とフッ化水素酸との混酸を加え、溶解を開始する。このとき塩酸水溶液を約３ｍｏｌ／リットルとする。すべて溶解して透明になった液を約２０ｍｌサンプリングし、０．１μｍメンブランフィルターでろ過し、ろ液を採取する。ろ液をプラズマ発光分光（ＩＣＰ）によって測定し、鉄元素及び鉄元素以外の金属元素の定量を行う。磁性酸化鉄を基準としたときの、鉄元素以外の金属元素の含有率は次式によって計算される。
【００７４】
【数１】
磁性酸化鉄を基準としたときの金属元素の含有率（質量％）
＝｛（ｃ×ｄ）／（ｅ×１０００）｝×１００
（ただし、式中ｃは採取したサンプル中の金属元素濃度（ｍｇ／ｌ）であり、ｄは採取したサンプル量（ｌ）であり、ｅは磁性酸化鉄重量（ｇ）である。）
【００７５】
（３）磁性酸化鉄の嵩密度
本発明に用いられる磁性酸化鉄の嵩密度は、ＪＩＳ Ｋ ５１０１の顔料試験法に準じて測定することができる。
【００７６】
（４）磁性酸化鉄の個数平均粒径
本発明に用いられる磁性酸化鉄の個数平均粒径は、透過電子顕微鏡写真（倍率３００００倍）より、写真上の粒子を無造作に１００個選び、その粒子径を計測し、その平均値から求めることができる。
【００７７】
（５）磁性酸化鉄の比表面積
本発明に用いられる磁性酸化鉄の比表面積は、ＢＥＴ法に従って、比表面積測定装置オートソープ１（湯浅アイオニクス社製）を用いて試料表面に窒素ガスを吸着させ、ＢＥＴ多点法を用いて算出することができる。
【００７８】
（６）磁性酸化鉄の磁気特性
本発明に用いられる磁性酸化鉄の磁気特性は、例えば「振動試料型磁力計ＶＳＭ−３Ｓ−１５」（東英工業社製）を用いて外部磁場７９５．８ｋＡ／ｍの下で測定することができる。
【００７９】
本発明の乾式トナーは、結着樹脂を含有する。本発明では、結着樹脂はポリエステル樹脂を主成分として含有することを特徴とする。ここで「ポリエステル樹脂を主成分として含有する」とは、結着樹脂の６０質量％以上にポリエステル樹脂を使用することを言う。副成分としては、結着樹脂として従来より知られている種々の樹脂化合物を用いることができる。
【００８０】
ポリエステル樹脂は、公知のように、二価以上の多価アルコールと二価以上の多価有機酸類との縮重合によって得られ、一般的にその末端に極性をもつカルボキシル基を有するが、本発明においてはこのカルボキシル基が磁性酸化鉄中のＭｇ、Ｃｕ、Ｚｎ、Ｔｉ、及びＡｌから選ばれる少なくとも一つの元素αと相互作用し、乾式トナー中における原材料の分散状態を向上させる。すなわち、本発明において結着樹脂としてポリエステル樹脂を用いることで、相乗的に原材料の分散性が高められ、帯電量の分布が均一となり、高速現像システムにおいても現像性の優れた乾式トナーを得ることができるのである。
【００８１】
以下に本発明で用いられるポリエステル樹脂を具体的に示す。ポリエステル樹脂は、全成分中４５〜５５ｍｏｌ％がアルコール成分であり、５５〜４５ｍｏｌ％が酸成分であることが好ましい。
【００８２】
アルコール成分としては、エチレングリコール、プロピレングリコール、１，３−ブタンジオール、１，４−ブタンジオール、２，３−ブタンジオール、ジエチレングリコール、トリエチレングリコール、１，５−ペンタンジオール、１，６−ヘキサンジオール、ネオペンチルグリコール、２−エチル−１，３−ヘキサンジオール、水素化ビスフェノールＡ、下記（Ｂ）式で表されるビスフェノール誘導体；下記（Ｃ）式で示されるジオール類；及び、グリセリン、ソルビット、ソルビタン等の三価以上の多価アルコール類等が挙げられる。
【００８３】
【化１】

【００８４】
【化２】

【００８５】
また、酸成分としてはカルボン酸が好ましくは例示することができ、二価のカルボン酸としてはフタル酸、テレフタル酸、イソフタル酸、無水フタル酸の如きベンゼンジカルボン酸類又はその無水物；コハク酸、アジピン酸、セバシン酸、アゼライン酸の如きアルキルジカルボン酸類又はその無水物；フマル酸、マレイン酸、シトラコン酸、イタコン酸の如き不飽和ジカルボン酸又はその無水物等が挙げられ、また、三価以上のカルボン酸としてはトリメリット酸、ピロメリット酸、ベンゾフェノンテトラカルボン酸やその無水物等が挙げられる。
【００８６】
特に好ましいポリエステル樹脂のアルコール成分としては前記（Ｂ）式で示されるビスフェノール誘導体であり、酸成分としては、フタル酸、テレフタル酸、イソフタル酸又はその無水物、コハク酸、ｎ−ドデセニルコハク酸又はその無水物、フマル酸、マレイン酸、無水マレイン酸の如きジカルボン酸類；トリメリット酸又はその無水物のトリカルボン酸類が挙げられる。
【００８７】
これらの酸成分及びアルコール成分から得られたポリエステル樹脂を結着樹脂として使用することが、画像の定着において熱ローラ定着を用いる画像形成プロセスに本発明の乾式トナーを用いたときに、良好な定着性と優れた耐オフセット性とを実現する上で好ましい。
【００８８】
本発明に用いられるポリエステル樹脂の酸価は１０〜５０ｍｇＫＯＨ／ｇであることが好ましく、１０〜４５ｍｇＫＯＨ／ｇであることがより好ましく、１０〜４０ｍｇＫＯＨ／ｇであることがさらに好ましい。ポリエステル樹脂の酸価が５０ｍｇＫＯＨ／ｇより大きい場合、乾式トナーの帯電特性において環境依存性が大きくなり、乾式トナーの流動性、静電付着性、乾式トナーの表面抵抗（吸着水の影響）が変動し、画質の低下を生じる場合がある。樹脂の酸価が１０ｍｇＫＯＨ／ｇよりも小さい場合、磁性酸化鉄表面に存在するＭｇ、Ｃｕ、Ｚｎ、Ｔｉ、及びＡｌから選ばれる少なくとも一つの元素αとの相互作用が弱まるため、乾式トナー中での原材料の分散性が悪化し、乾式トナーの帯電量の分布が広がるため、不均一に帯電したトナー粒子が存在することとなり、画像濃度の一様性やドット再現性等画質が悪化することがある。ポリエステル樹脂の酸価は、ＪＩＳ Ｋ ００７０に準じて公知の方法により測定することができる。
【００８９】
また、本発明では結着樹脂として、従来より結着樹脂として知られている種々の樹脂化合物をポリエステル樹脂と併用することができ、このような樹脂化合物としては、例えばビニル系樹脂、フェノール樹脂、天然樹脂変性フェノール樹脂、天然樹脂変性マレイン酸樹脂、アクリル樹脂、メタクリル樹脂、ポリ酢酸ビニル、シリコーン樹脂、ポリエステル樹脂、ポリウレタン、ポリアミド樹脂、フラン樹脂、エポキシ樹脂、キシレン樹脂、ポリビニルブチラール、テルペン樹脂、クマロインデン樹脂、石油系樹脂等が挙げられる。
【００９０】
また本発明に用いられる結着樹脂のガラス転移温度は、５０〜７５℃であることが好ましく、５５〜６５℃であることがより好ましくい。さらに前記結着樹脂の数平均分子量（Ｍｎ）は、１，５００〜５０，０００であることが好ましく、２，０００〜２０，０００であることがより好ましくい。また前記結着樹脂の重量平均分子量（Ｍｗ）は、６，０００〜１００，０００であることが好ましく、１０，０００〜９０，０００であることがより好ましい。
【００９１】
結着樹脂のガラス転移温度が上記範囲よりも小さいと乾式トナーの保存安定性が不十分となることがあり、結着樹脂のガラス転移温度が上記範囲よりも大きいと乾式トナーの定着性が不十分となることがある。結着樹脂のガラス転移温度は、後述する示差走査熱量計を用いて測定することができる。
【００９２】
また結着樹脂の数平均分子量及び重量平均分子量は、ＴＨＦ（テトラヒドロフラン）を溶媒としたＧＰＣ（ゲルパーミエションクロマトグラフィー）によって測定することができる。本発明において、トナー及び結着樹脂のＴＨＦ（テトラヒドロフラン）を溶媒としたＧＰＣによる分子量分布は次の条件で測定される。
【００９３】
試料は以下のようにして作製する。
まず試料をＴＨＦ中に入れ、数時間放置した後、十分振とうしＴＨＦとよく混ぜ（試料の合一体が無くなるまで）、さらに１２時間以上静置する。その時ＴＨＦ中への放置時間が２４時間以上となるようにする。その後、サンプル処理フィルター（ポアサイズ０．２〜０．５μｍ、例えばマイショリディスクＨ−２５−２（東ソー社製）など使用できる。）を通過させたものをＧＰＣの試料とする。又、試料濃度は、樹脂成分が０．５〜５ｍｇ／ｍｌとなるように調整する。
【００９４】
検出器にはＲＩ（屈折率）検出器を用いる。またカラムとしては市販のポリスチレンジェルカラムを複数本組み合わせるのが良く、例えば昭和電工社製のｓｈｏｄｅｘ ＧＰＣ ＫＦ−８０１、８０２、８０３、８０４、８０５、８０６、８０７、８００Ｐの組み合わせや、東ソー社製のＴＳＫｇｅｌ Ｇ１０００Ｈ（Ｈ_ＸＬ）、Ｇ２０００Ｈ（Ｈ_ＸＬ）、Ｇ３０００Ｈ（Ｈ_ＸＬ）、Ｇ４０００Ｈ（Ｈ_ＸＬ）、Ｇ５０００Ｈ（Ｈ_ＸＬ）、Ｇ６０００Ｈ（Ｈ_ＸＬ）、Ｇ７０００Ｈ（Ｈ_ＸＬ）、ＴＳＫｇｕｒｄ ｃｏｌｕｍｎの組み合せを挙げることができる。
【００９５】
４０℃のヒートチャンバー中でカラムを安定化させ、この温度におけるカラムに溶媒としてＴＨＦを毎分１ｍｌの流速で流し、ＴＨＦ試料溶液を約１００μｌ注入して測定する。
【００９６】
試料の分子量測定にあたっては試料の有する分子量分布を数種の単分散ポリスチレン標準試料により作成された検量線の対数値とカウント値との関係から算出する。検量線作成用の標準ポリスチレン試料としては例えば、東ソー社製あるいは昭和電工社製の分子量が１０²〜１０⁷程度のものを用い、少なくとも１０点程度の標準ポリスチレン試料を用いるのが適当である。
【００９７】
本発明の乾式トナーは、示差走査熱量計（ＤＳＣ）により測定される昇温時のＤＳＣ曲線に少なくとも一つの吸熱ピークが存在し、前記吸熱ピークが６０〜１２０℃に存在することが好ましい。この吸熱ピークは、６５〜１２０℃に存在することがより好ましく、７０〜１１５℃に存在することがさらに好ましい。吸熱ピークは二つ以上存在していてもよいが、その場合は６０〜１２０℃に少なくとも一つの吸熱ピークを有することが好ましい。
【００９８】
昇温時のＤＳＣ曲線からは、乾式トナーの吸熱に伴う融解挙動を見ることができる。吸熱ピークが６０〜１２０℃に存在すると、乾式トナーを加熱溶融混練したときに十分に粘度が下がり、磁性酸化鉄が良好に分散することができ、乾式トナーの帯電性を安定させる上で好ましい。
【００９９】
本発明の乾式トナーの吸熱ピークは、適当なワックスを選択して乾式トナーに含有させることによって所望の吸熱ピークを得ることができる。このような吸熱ピークを乾式トナーに付与することができるワックスは、その溶融特性から、乾式トナー表面において高い疎水性を乾式トナーに付与しやすく、本発明の特徴とする濡れ性を乾式トナーに付与する上で効果的である。
【０１００】
本発明においては、乾式トナーのＤＳＣ曲線は、示差走査熱量計（ＤＳＣ測定装置）、例えばＤＳＣ−７（パーキンエルマー社製）やＤＳＣ２９２０（ＴＡインスツルメンツジャパン社製）を用い、ＡＳＴＭ Ｄ３４１８−８２に準じて測定することができる。ＤＳＣ曲線は、一回昇温、降温させ、前履歴を取った後、昇温速度１０℃／ｍｉｎで昇温させたときに測定されるＤＳＣ曲線を用いる。結着樹脂のガラス転移点に伴うピークは、例えば結着樹脂のみを測定するなどして区別することができる。
【０１０１】
本発明の乾式トナーは、前述した結着樹脂及び磁性酸化鉄以外の材料として種々の材料を含有していても良い。このよう他の材料として、前述したワックスや荷電制御剤等が挙げられる。
【０１０２】
本発明に用いられるワックスとしては様々なワックスが挙げられ、例えば低分子量ポリエチレン、低分子量ポリプロピレン、ポリオレフィン共重合物、ポリオレフィンワックス、マイクロクリスタリンワックス、パラフィンワックス、フィッシャートロプシュワックスの如き脂肪族炭化水素系ワックス；酸化ポリエチレンワックスの如き脂肪族炭化水素系ワックスの酸化物；又は、それらのブロック共重合物；キャンデリラワックス、カルナバワックス、木ろう、ホホバろうの如き植物系ワックス；みつろう、ラノリン、鯨ろうの如き動物系ワックス；オゾケライト、セレシン、ペトロラクタムの如き鉱物系ワックス；モンタン酸エステルワックス、カスターワックスの如き脂肪族エステルを主成分とするワックス類；脱酸カルナバワックスの如き脂肪族エステルを一部又は全部を脱酸化したものが挙げられる。
【０１０３】
さらに前記ワックスとしては、例えばパルミチン酸、ステアリン酸、モンタン酸、或いはさらに長鎖のアルキル基を有する長鎖アルキルカルボン酸類の如き飽和直鎖脂肪酸；ブラシジン酸、エレオステアリン酸、バリナリン酸の如き不飽和脂肪酸；ステアリルアルコール、エイコシルアルコール、ベヘニルアルコール、カウナビルアルコール、セリルアルコール、メリシルアルコール、或いはさらに長鎖のアルキル基を有するアルキルアルコールの如き飽和アルコール；ソルビトールの如き多価アルコール；リノール酸アミド、オレイン酸アミド、ラウリン酸アミドの如き脂肪族アミド；メチレンビスステアリン酸アミド、エチレンビスカプリン酸アミド、エチレンビスラウリン酸アミド、ヘキサメチレンビスステアリン酸アミドの如き飽和脂肪族ビスアミド；エチレンビスオレイン酸アミド、ヘキサメチレンビスオレイン酸アミド、Ｎ，Ｎ’−ジオレイルアジピン酸アミド、Ｎ，Ｎ’−ジオレイルセバシン酸アミドの如き不飽和脂肪酸アミド類；ｍ−キシレンビスステアリン酸アミド、Ｎ，Ｎ’−ジステアリルイソフタル酸アミドの如き芳香族系ビスアミド；ステアリン酸カルシウム、ラウリン酸カルシウム、ステアリン酸亜鉛、ステアリン酸マグネシウムの如き脂肪族金属塩（一般に金属石けんといわれているもの）；脂肪族炭化水素系ワックスにスチレンやアクリル酸の如きビニル系モノマーを用いてグラフト化させたワックス；ベヘニン酸モノグリセリドの如き脂肪酸と多価アルコールの部分エステル化物；植物性油脂を水素添加することによって得られるヒドロキシル基を有するメチルエステル化合物等が挙げられる。
【０１０４】
また、これらのワックスを、プレス発汗法、溶剤法、再結晶法、真空蒸留法、超臨界ガス抽出法又は融液晶析法を用いて分子量分布をシャープにしたものや低分子量固形脂肪酸、低分子量固形アルコール、低分子量固形化合物、その他の不純物を除去したものも好ましく用いられる。
【０１０５】
また、本発明においては、荷電制御剤を添加して使用することが好ましい。本発明では、荷電制御剤として負荷電性及び正荷電性のいずれの荷電制御剤も用いることができる。
【０１０６】
負荷電制御剤の具体例としては、特公昭４１−２０１５３号公報、特公昭４２−２７５９６号公報、特公昭４４−６３９７号公報、特公昭４５−２６４７８号公報等に記載されているモノアゾ染料の金属錯体、さらには特開昭５０−１３３８３８号公報に記載されているニトロフミン酸及びその塩或いはＣ．Ｉ．１４６４５等の染顔料、特公昭５５−４２７５２号公報、特公昭５８−４１５０８号公報、特公昭５８−７３８４号公報、特公昭５９−７３８５号公報等に記載されているサリチル酸、ナフトエ酸、ダイカルボン酸のＺｎ、Ａｌ、Ｃｏ、Ｃｒ、Ｆｅ、及びＺｒ等の金属錯体、スルホン化した銅フタロシアニン顔料、ニトロ基、ハロゲンを導入したスチレンオリゴマー、塩素化パラフィン等を挙げることができる。
【０１０７】
特に分散性に優れ、画像濃度の安定性やカブリの低減に効果のある、一般式（Ｉ）で表されるアゾ系金属錯体や一般式（II）で表される塩基性有機酸金属錯体が好ましい。
【０１０８】
【化３】

【０１０９】
【化４】

【０１１０】
そのうち上記式（Ｉ）で表されるアゾ系金属錯体がより好ましく、とりわけ、中心金属がＦｅである下記式（III）あるいは（IV）で表されるアゾ系鉄錯体が最も好ましい。
【０１１１】
【化５】

【０１１２】
【化６】

【０１１３】
上記式（III）で示されるアゾ系鉄錯体の具体例である下記式（１）〜（６）の化合物を示す。
【０１１４】
【化７】

【０１１５】
【化８】

【０１１６】
【化９】

【０１１７】
【化１０】

【０１１８】
【化１１】

【０１１９】
【化１２】

また、上記式（Ｉ）、（II）、（IV）で示される荷電制御剤の具体例である下記式（７）〜（１３）の化合物を示す。
【０１２０】
【化１３】

【０１２１】
【化１４】

【０１２２】
【化１５】

【０１２３】
【化１６】

【０１２４】
【化１７】

【０１２５】
【化１８】

【０１２６】
【化１９】

【０１２７】
これらの金属錯化合物は、単独でも或いは二種以上組み合わせて用いることが可能である。
【０１２８】
これらの荷電制御剤の使用量は、荷電制御剤の種類によっても異なるが、トナーの帯電量の点から、結着樹脂１００質量部当たり０．１〜５．０質量部が一般に好ましい。
【０１２９】
一方、乾式トナーを正荷電性に制御する荷電制御剤としては、例えばニグロシン及び脂肪酸金属塩等による変性物、トリブチルベンジルアンモニウム−１−ヒドロキシ−４−ナフトスルホン酸塩、テトラブチルアンモニウムテトラフルオロボレート等の四級アンモニウム塩、及びこれらの類似体であるホスホニウム塩等のオニウム塩及びこれらのレーキ顔料、トリフェニルメタン染料及びこれらのレーキ顔料、（レーキ化剤としては、リンタングステン酸、リンモリブデン酸、リンタングステンモリブデン酸、タンニン酸、ラウリン酸、没食子酸、フェリシアン化物、フェロシアン化物等）高級脂肪酸の金属塩；ジブチルスズオキサイド、ジオクチルスズオキサイド、ジシクロヘキシルスズオキサイド等のジオルガノスズオキサイド；ジブチルスズボレート、ジオクチルスズボレート、ジシクロヘキシルスズボレート等のジオルガノスズボレート類；これらを単独で或いは二種類以上組み合わせて用いることができる。
【０１３０】
また、本発明の乾式トナーには、前述した結着樹脂や磁性酸化鉄等の材料で構成されるトナー粒子に外添剤を添加することが好ましい。このような外添剤としては、例えば無機微粉体及び疎水性無機微粉体等が挙げられ、特に好ましい外添剤としてはシリカ微粉末が挙げられる。
【０１３１】
本発明に用いられるシリカ微粉体は、ケイ素ハロゲン化合物の蒸気相酸化により生成されたいわゆる乾式法又はヒュームドシリカと称される乾式シリカ及び水ガラス等から製造されるいわゆる湿式シリカの両方が使用可能であるが、表面及び内部にあるシラノール基が少なく、製造残渣のない乾式シリカの方が好ましい。
【０１３２】
さらに本発明に用いるシリカ微粉体は、疎水化処理されているものが好ましい。疎水化処理には、シリカ微粉体と反応あるいは物理吸着する有機ケイ素化合物等の疎水性の化合物で化学的に処理する方法が好ましい方法として挙げられる。より好ましい方法としては、ケイ素ハロゲン化合物の蒸気相酸化により生成された乾式シリカ微粉体を、シラン化合物で処理した後、あるいはシラン化合物で処理すると同時に、シリコーンオイルの如き有機ケイ素化合物で処理する方法が挙げられる。
【０１３３】
疎水化処理に使用されるシラン化合物としては、例えばヘキサメチルジシラザン、トリメチルシラン、トリメチルクロルシラン、トリメチルエトキシシラン、ジメチルジクロルシラン、メチルトリクロルシラン、アリルジメチルクロルシラン、アリルフェニルジクロルシラン、ベンジルジメチルクロルシラン、ブロムメチルジメチルクロルシラン、α−クロルエチルトリクロルシラン、β−クロルエチルトリクロルシラン、クロルメチルジメチルクロルシラン、トリオルガノシランメルカプタン、トリメチルシリルメルカプタン、トリオルガノシリルアクリレート、ビニルジメチルアセトキシシラン、ジメチルエトキシシラン、ジメチルジメトキシシラン、ジフェニルジエトキシシラン、ヘキサメチルジシロキサン、１，３−ジビニルテトラメチルジシロキサン、１，３−ジフェニルテトラメチルジシロキサン等が挙げられる。
【０１３４】
有機ケイ素化合物としては、シリコーンオイルが挙げられる。シリコーンオイルとしては、２５℃における粘度がおよそ３×１０^-5〜１×１０^-3ｍ²／ｓのものが好ましく、例えばジメチルシリコーンオイル、メチルハイドロジェンシリコーンオイル、メチルフェニルシリコーンオイル、α−メチルスチレン変性シリコーンオイル、クロルフェニルシリコーンオイル、フッ素変性シリコーンオイル等が好ましい。
【０１３５】
シリコーンオイルを用いる外添剤の表面疎水化処理の方法としては、例えばシラン化合物で処理されたシリカ微粉体とシリコーンオイルとをヘンシェルミキサー等の混合機を用いて直接混合しても良いし、ベースとなるシリカへシリコーンオイルを噴射する方法によっても良い。あるいは適当な溶剤にシリコーンオイルを溶解あるいは分散せしめた後、ベースのシリカ微粉体とを混合し、溶剤を除去する方法であっても良い。
【０１３６】
前記無機微粉体及び疎水性無機微粉体の添加量は、その種類や所期の機能等によっても異なるが、トナー粒子１００質量部に対して０．１〜５質量部（好ましくは、０．１〜３質量部）であることが好ましい。
【０１３７】
本発明の乾式トナーには、シリカ微粉体等の前記無機微粉体以外の外添剤を必要に応じて添加してもよい。このような他の外添剤としては、例えば帯電補助剤、導電性付与剤、流動性付与剤、ケーキング防止剤、滑剤、研磨剤等の働きをする樹脂微粒子や無機微粒子である。
【０１３８】
より具体的には、例えばフッ素系樹脂、ステアリン酸亜鉛、ポリフッ化ビニリデンの如き滑剤、中でもポリフッ化ビニリデンが好ましい。或いは酸化セリウム、炭化ケイ素、チタン酸ストロンチウム等の研磨剤、中でもチタン酸ストロンチウムが好ましい。或いは例えば酸化チタン、酸化アルミニウム等の流動性付与剤、中でも特に疎水性のものが好ましい。ケーキング防止剤、或いは例えばカーボンブラック、酸化亜鉛、酸化アンチモン、酸化スズ等の導電性付与剤、また逆極性の白色微粒子及び黒色微粒子を現像性向上剤として少量用いることもできる。
【０１３９】
本発明の乾式トナーは、静電荷像を現像する為に使用されるトナー粒子を生成する通常の方法を用いて製造することが可能である。本発明の乾式トナーの材料としては、前述した結着樹脂及び磁性酸化鉄を少なくとも用い、さらに必要に応じて着色剤、ワックス、荷電制御剤等の他の材料が用いられる。より具体的には、本発明の乾式トナーは、これらの材料をヘンシェルミキサー又はボールミルの如き混合機により十分混合してから、ロール、ニーダー及びエクストルーダーの如き熱混練機を用いて溶融、捏和及び混練して樹脂類を互いに相溶せしめた中に、顔料又は染料を分散又は溶解せしめ、冷却固化後、粉砕及び分級を行うことにより製造することができる。
【０１４０】
本発明の乾式トナーの製造には、公知の装置を用いることができ、例えば混合機としては、ヘンシェルミキサー（三井鉱山社製）；スーパーミキサー（カワタ社製）；リボコーン（大川原製作所社製）；ナウターミキサー、タービュライザー、サイクロミックス（ホソカワミクロン社製）；スパイラルピンミキサー（太平洋機工社製）；レーディゲミキサー（マツボー社製）が挙げられる。
【０１４１】
また混練機としては、例えばＫＲＣニーダー（栗本鉄工所社製）；ブス・コ・ニーダー（Ｂｕｓｓ社製）；ＴＥＭ型押し出し機（東芝機械社製）；ＴＥＸ二軸混練機（日本製鋼所社製）；ＰＣＭ混練機（池貝鉄工所社製）；三本ロールミル、ミキシングロールミル、ニーダー（井上製作所社製）；ニーデックス（三井鉱山社製）；ＭＳ式加圧ニーダー、ニダールーダー（森山製作所社製）；バンバリーミキサー（神戸製鋼所社製）が挙げられる。
【０１４２】
また粉砕機としては、例えばカウンタージェットミル、ミクロンジェット、イノマイザ（ホソカワミクロン社製）；ＩＤＳ型ミル、ＰＪＭジェット粉砕機（日本ニューマチック工業社製）；クロスジェットミル（栗本鉄工所社製）；ウルマックス（日曹エンジニアリング社製）；ＳＫジェット・オー・ミル（セイシン企業社製）；クリプトロン（川崎重工業社製）；ターボミル（ターボ工業社製）；スーパーローター（日清エンジニアリング）が挙げられる。
【０１４３】
また分級機としては、例えばクラッシール、マイクロンクラッシファイアー、スペディッククラシファイアー（セイシン企業社製）；ターボクラッシファイアー（日新エンジニアリング社製）；ミクロンセパレータ、ターボプレックス（ＡＴＰ）、ＴＳＰセパレータ（ホソカワミクロン社製）；エルボージェット（日鉄鉱業社製）、ディスパージョンセパレータ（日本ニューマチック工業社製）；ＹＭマイクロカット（安川商事社製）が挙げられる。
【０１４４】
また粗粒等をふるい分けるために用いられる篩い装置としては、例えばウルトラソニック（晃栄産業社製）；レゾナシーブ、ジャイロシフター（徳寿工作所社）；バイブラソニックシステム（ダルトン社製）；ソニクリーン（新東工業社製）；ターボスクリーナー（ターボ工業社製）；ミクロシフター（槙野産業社製）；円形振動篩い等が挙げられる。
【０１４５】
本発明の乾式トナーは、前述したような公知の方法及び公知の装置によって製造することができるが、本発明の特徴の一つであるトナーの透過率とメタノール濃度との関係、すなわち濡れ性を達成する製造法としての一つとして、本発明においては、図２、図３及び図４に示したような機械式粉砕機を用いることが、粉体原料の粉砕処理及び表面処理を行い、かつ効率向上を図る観点から好ましい。
【０１４６】
この粉砕機において、粉砕時の温度を調整し、結着樹脂の主成分としてポリエステル樹脂を用い、かつ本発明の組成を有する磁性酸化鉄を用いることで、乾式トナーの表面の磁性酸化鉄の表面状態を制御できる。
以下、図２、図３及び図４に示す機械式粉砕機について説明する。
【０１４７】
図２は、本発明の乾式トナーを製造する際に使用される機械式粉砕機の一例の概略断面図を示しており、図３は図２におけるＤ−Ｄ’面での概略的断面図を示しており、図４は図２に示す回転子３１４の斜視図を示している。前記装置は、図２に示されているように、ケーシング３１３、ジャケット３１６、ディストリビュータ２２０、ケーシング３１３内にあって中心回転軸３１２に取り付けられた回転体で表面に多数の溝が設けられている回転子３１４、表面に多数の溝が設けられており回転子３１４の外周に一定間隔を保持して配置されている固定子３１０、さらに、被処理原料を導入するための原料投入口３１１、処理後の粉体を排出する為の原料排出口３０２とから構成されている。
【０１４８】
通常、粉砕原料を機械式粉砕機で粉砕する際には機械式粉砕機の渦巻き室２１２の温度Ｔ１や後室３２０の温度Ｔ２の温度を制御し、樹脂のＴｇ以下で粉砕を行い、表面改質を行わない方法を選択している。しかし、本発明の乾式トナーを製造する場合では、本発明の特徴とする性質の乾式トナーを得るために、原料排出口３０２の温度をＴｇに対して−２５〜−５℃の範囲となる温度に設定し、実際の粉砕状態ではＴｇの−２０〜±０℃の温度にして、粉砕後乾式トナー表面に存在する磁性酸化鉄の一部を樹脂が覆う状態となるように粉砕を行う。それにより、乾式トナー表面での原材料の存在分布が適正な値となりやすく、このような粉砕を行うことが、本発明の特徴とする疎水特性を乾式トナーに付与する上で好ましい。
【０１４９】
【実施例】
本発明の基本的な構成と特色について以上に述べたが、実施例に基づき具体的に本発明について以下に説明する。しかしながら本発明は、以下の実施例によって何ら限定されるものではない。実施例中の部数は質量部である。実施例に用いられる結着樹脂を表１に、ワックスを表２に、磁性酸化鉄粒子を表３に記す。表１に記載された結着樹脂としてのポリエステル樹脂は脱水縮合法により合成した。磁性酸化鉄粒子の製造方法については以下のとおりである。
【０１５０】
【表１】

【０１５１】
【表２】

【０１５２】
【表３】

【０１５３】
＜磁性酸化鉄粒子の製造例１＞
硫酸第一鉄水溶液中に、鉄元素に対しケイ素元素の含有量が０．４８％となるようにケイ酸ソーダを添加した後、苛性ソーダ溶液を混合し、水酸化第一鉄を含む水溶液を調製した。水溶液のｐＨを１０に調整しながら空気を吹き込み、８０乃至９０℃で酸化反応を行い、種晶を生成させるスラリー液を調製した。
【０１５４】
種晶の生成が確認されたら、このスラリー液にさらに硫酸第一鉄水溶液を適宜加え、スラリー液のｐＨを１０に調整しながら空気を吹き込み酸化反応を進めた。その間に、未反応の水酸化第一鉄濃度を調べながら反応の進行率を調べつつ、適宜硫酸亜鉛を加え、さらに水溶液のｐＨを酸化反応の初期はｐＨを９に、反応中期にはｐＨを８に、反応後期にはｐＨを６にというように段階的に調整することで磁性酸化鉄内での金属元素の分布を制御し、酸化反応を完結させた。生成した磁性酸化鉄粒子を常法により洗浄、ろ過乾燥した。得られた磁性酸化鉄粒子の一次粒子は、凝集して凝集体を形成しているので、ミックスマーラーを使用して磁性酸化鉄粒子の凝集体に圧縮力及びせん断力を付与して、前記凝集体を解砕して磁性酸化鉄粒子を一次粒子にすると共に、磁性酸化鉄粒子の表面を平滑にし、表３に示すような特性を有する磁性酸化鉄１を得た。
【０１５５】
＜磁性酸化鉄粒子の製造例２〜５＞
ケイ酸ソーダの添加量、他種元素αの塩の添加量、添加時期、及び種類の少なくともいずれかを変えた以外は製造例１と同様にして、表３に示す物性を有する磁性酸化鉄２〜５を得た。
【０１５６】
＜磁性酸化鉄粒子の製造例６＞
硫酸第一鉄水溶液中に、鉄元素に対しケイ素元素の含有量が０．４０％となるようにケイ酸ソーダを添加した後、苛性ソーダ溶液を混合し、水酸化第一鉄を含む水溶液を調製した。水溶液のｐＨを１０に調整しながら空気を吹き込み、８０乃至９０℃で酸化反応を行い、種晶を生成させるスラリー液を調製した。
【０１５７】
種晶の生成が確認されたら、このスラリー液にさらに硫酸第一鉄水溶液を適宜加え、スラリー液のｐＨを１０に調整しながら空気を吹き込み酸化反応を進めた。その間に、未反応の水酸化第一鉄濃度を調べながら反応の進行率を調べつつ、適宜硫酸マグネシウムを加え、さらに水溶液のｐＨを８に調整しながら酸化反応を完結させた。生成した磁性酸化鉄粒子を常法により洗浄、ろ過乾燥した。得られた磁性酸化鉄粒子の一次粒子は、凝集して凝集体を形成しているので、ミックスマーラーを使用して磁性酸化鉄粒子の凝集体に圧縮力及びせん断力を付与して、前記凝集体を解砕して磁性酸化鉄粒子を一次粒子にすると共に、磁性酸化鉄粒子の表面を平滑にし、表３に示すような特性を有する磁性酸化鉄６を得た。
【０１５８】
＜実施例１＞
・結着樹脂Ａ １００質量部
・磁性酸化鉄１ ９０質量部
・ワックスｄ ４質量部
・下記構造式に示す荷電制御剤Ａ ２質量部
上記混合物を、１４０℃に加熱された二軸エクストルーダで溶融混練し、冷却した混練物をハンマーミルで粗粉砕し、得られた粗粉砕物をターボミル（ターボ工業社製）で機械式粉砕により微粉砕し、得られた微粉砕粉を固定壁型風力分級機で分級して分級粉を得た。さらに、得られた分級粉を、コアンダ効果を利用した多分割分級装置（日鉄鉱業社製エルボジェット分級機）で分級し、超微粉及び粗粉を同時に厳密に分級除去して、重量平均粒径（Ｄ４）６．５μｍの負帯電性トナー粒子を得た。
【０１５９】
【化２０】

【０１６０】
この得られたトナー粒子１００質量部に対し、ヘキサメチルジシラザン１５ｗｔ％とジメチルシリコーン１５ｗｔ％で疎水化処理したメタノールウェッタビリティ８０％、ＢＥＴ比表面積１２０ｍ²／ｇの疎水性シリカ微粉体を１．３質量部とチタン酸ストロンチウム１．０質量部とを外添混合してトナー１を調整した。トナー内添処方及び物性を表４に、トナー１の、７８０ｎｍの波長の光の透過率に対するメタノール濃度のグラフを図１に示す。
【０１６１】
このトナー１を、市販のＬＢＰプリンタ（ＬｅｓｅｒＪｅｔ ４１００、ＨＰ社製）を１．５倍のプリントスピードに改造し、これを画出し試験機として、１５℃、１０％ＲＨの環境、２３℃、６０％ＲＨの環境と３０℃、８０％ＲＨの環境で１万枚のプリント試験を行った。この際、ページ内の画像濃度一様性については、高温高湿環境下でのプリントアウト画像内での、画像濃度の最高値と最低値の差によりページ内の画像濃度一様性を判断した。
【０１６２】
画像濃度は、マクベス濃度計（マクベス社製）でＳＰＩフィルターを使用して、５ｍｍ角の画像を反射濃度測定することにより測定した。カブリは、反射濃度計（リフレクトメーター モデル ＴＣ−６ＤＳ 東京電色社製）を用いて画像形成前後の転写材を測定し、画像形成後の白地部反射濃度最悪値をＤｓ、画像形成前の転写材の反射平均濃度をＤｒとし、Ｄｓ−Ｄｒを求め、これをカブリ量として評価した。数値の少ない方がカブリが抑制されていることを示す。これらの評価を、初期、１００００枚時、機外に一日放置した後のそれぞれの時期に行った。
【０１６３】
帯電量の立ち上がりの評価については、上記画出し試験機を用いて１５℃、１０％ＲＨの環境で４ドットの横ラインを１７６ドットスペースおきに印字した横ラインパターンを、１０秒に１枚の間隔で画出しする間欠プリント試験を行い、１枚目、３枚目、７枚目、１５枚目、５０枚目、１００枚時に５ｍｍ角の画像をサンプリングし、画像濃度を測定した。画出し枚数の早いうちから高い画像濃度が得られているものほど帯電量の立ち上がりが早いと言える。
【０１６４】
画質の評価については、上記画出し試験機を用いて、常温常湿環境（２３℃、６０％ＲＨ）で１２００ｄｐｉの孤立した１ドットのパターンを画出しし、光学顕微鏡で画像を観察してドット再現性を以下の基準により評価した。
Ａ：潜像からのトナーのはみ出しが全くなく、ドットを完全に再現している
Ｂ：潜像からのトナーのはみ出しが少しある
Ｃ：潜像からのトナーのはみ出しが多い
【０１６５】
尾引きについては、上記画出し試験機を用いて、４ドットの横ラインを２０ドットスペースに印字したパターンを画出しし、ライン上で尾を引いた数を数え、以下の基準により評価した。
Ａ：発生なし
Ｂ：３個未満
Ｃ：３〜７個未満
Ｄ：７〜１５個未満
Ｅ：１５個以上
【０１６６】
画像飛び散りについては、上記画出し試験機を用いて、４ドットの横ラインを１７６ドットスペースおきに印字した横ラインパターンを、１０秒に１枚の間隔で画出しする間欠プリント試験を行い、１００００枚目の画像飛び散りを以下の基準により評価した。
Ａ：拡大観察によっても画像飛び散りの少ない画像
Ｂ：拡大観察により飛び散りが見られるが、目視では見えない
Ｃ：飛び散りにより、文字が多少にじむ
Ｄ：飛び散りにより、ラインの太さにむらが出る
Ｅ：飛び散りにより、細かな文字の一部につぶれが見られる
【０１６７】
また、得られたトナーを温度４０℃、湿度９０％ＲＨの環境下に３０日間放置し、その後通常環境下（温度２３℃、湿度６０％ＲＨ）で、上記画出し試験機を用いて５００枚の画出し試験を行った。そのときの５００枚目の画像濃度及びカブリの評価を表６に示す。
【０１６８】
＜実施例２〜７、比較例１＞
表４に記載の処方で実施例１と同様にトナー２〜８を作製した。表中の荷電制御剤Ｂ及び荷電制御剤Ｃの構造式を以下に示す。またこれらのトナーを用いて実施例１と同様の試験を行った。結果を表５、６、７、８、９に示す。
【０１６９】
【化２１】

【０１７０】
【化２２】

【０１７１】
＜比較例２＞
分級後に得られたトナー粒子を、３００℃の熱風中を瞬間的に通過させる処理を行った以外は、表４に記載の処方で実施例１と同様にトナー９を作製した。このトナー９を用いて実施例１と同様の試験を行った。結果を表５、６、７、８、９に示す。
【０１７２】
＜比較例３＞
粉砕工程では、衝突式気流粉砕による微粉砕機を用いた以外は、表４に記載の処方で実施例１と同様にトナー１０を作製した。このトナー１０を用いて実施例１と同様の試験を行った。結果を表５、６、７、８、９に示す。
【０１７３】
【表４】

【０１７４】
【表５】

【０１７５】
【表６】

【０１７６】
【表７】

【０１７７】
【表８】

【０１７８】
【表９】

【０１７９】
【発明の効果】
本発明によれば、少なくとも結着樹脂及び磁性酸化鉄を有するトナーにおいて、結着樹脂は、ポリエステル樹脂を主成分として含有し、磁性酸化鉄は、Ｓｉと、Ｍｇ、Ｃｕ、Ｚｎ、Ｔｉ、及びＡｌから選ばれる少なくとも一つの元素である元素αとを含有し、磁性酸化鉄におけるＳｉの含有量は、磁性酸化鉄を基準として０．１〜２．０質量％であり、磁性酸化鉄における元素αの含有量は、磁性酸化鉄を基準として０．１〜４．０質量％であり、Ｘ線光電子分光法によって測定される磁性酸化鉄の最表面における元素αの原子濃度が１．００〜７．００％であり、メタノール及び水の混合溶媒に対するトナーの濡れ性を７８０ｎｍの波長の光の透過率で測定した場合、透過率が８０％のときのメタノール濃度が４５〜６５体積％の範囲内で、また、透過率が１０％のときのメタノール濃度が４５〜６５体積％の範囲内であることから、高温高湿、低温低湿のような厳しい環境下における高速現像においても長期の使用において高い現像性を維持し、帯電量の立ち上がりの速い、高画質でありかつ、良好な現像性、環境安定性を持つことができるトナーを得ることができる。
【０１８０】
また本発明では、メタノール及び水の混合溶媒に対するトナーの濡れ性を７８０ｎｍの波長の光の透過率で測定した場合、透過率が８０％のときのメタノール濃度が５０〜６５体積％の範囲内で、また、透過率が１０％のときのメタノール濃度が５０〜６５体積％の範囲内であると、乾式トナーの帯電量を適正に保ち、カブリを防止し、かつ画像濃度の高い良好な画像を形成する上でより一層効果的である。
【０１８１】
また本発明では、示差走査熱量計により測定されるトナーの昇温時のＤＳＣ曲線に少なくとも一つの吸熱ピークが存在し、吸熱ピークが６０℃〜１２０℃に存在すると、トナー粒子中に磁性酸化鉄を良好に分散させ、乾式トナーの帯電性を安定させる上でより一層効果的である。
【０１８２】
また本発明では、ポリエステル樹脂の酸価が１０〜５０ｍｇＫＯＨ／ｇであると、乾式トナーの帯電性を安定させ、かつ環境変化によらない安定した良好な画像を形成する上でより一層効果的である。
【０１８３】
また本発明では、磁性酸化鉄におけるＳｉの含有量は、磁性酸化鉄を基準として０．３〜１．８質量％であると、乾式トナーを適度にかつすばやく帯電させる上でより一層効果的である。
【０１８４】
また本発明では、磁性酸化鉄における元素αの含有量は、磁性酸化鉄を基準として０．１〜２．０質量％であると、環境変化によらず乾式トナーを十分に帯電させ、高画質及び高画像濃度の良好な画像を形成する上でより一層効果的である。
【０１８５】
また本発明では、元素αがＭｇ、Ａｌ、及びＺｎから選ばれる元素であると、環境変化によらず乾式トナーを十分に帯電させ、高画質及び高画像濃度の良好な画像を形成する上でより一層効果的である。
【０１８６】
また本発明では、Ｘ線光電子分光法によって測定される磁性酸化鉄の最表面におけるＳｉ原子の原子濃度が１２．５〜１７．５％であり、Ｆｅ原子の原子濃度が７０．００〜８５．００％であると、磁性酸化鉄の通電性と電気抵抗のバランスをとり、乾式トナーの帯電量を制御し、その結果、環境によらず高画像濃度、高画質な現像性を得る上でより一層効果的である。
【０１８７】
また本発明では、Ｘ線光電子分光法によって測定される磁性酸化鉄の最表面の原子濃度において、Ｓｉ原子に対する元素αの比が０．０５〜０．５であり、Ｓｉ原子に対するＦｅ原子の比が３．００〜７．００であり、元素αに対するＦｅ原子の比が１０．０〜７０．０であると、磁性酸化鉄の通電性と電気抵抗のバランスをとり、乾式トナーの帯電量を制御し、その結果、環境によらず高画像濃度、高画質な現像性を得る上でより一層効果的である。
【０１８８】
また本発明では、磁性酸化鉄を結着樹脂１００質量部に対して３０〜１５０質量部含有していると、良好な帯電性と現像性とを両立させ、良好な画像を形成する上でより一層効果的である。
【図面の簡単な説明】
【図１】本発明の実施例１におけるトナー１の、メタノール濃度に対する波長の光７８０ｎｍの透過率を示したグラフである。
【図２】本発明の乾式トナーを製造する際に使用され得る機械式粉砕機の概略断面図である。
【図３】図２に示す機械式粉砕機をＤ−Ｄ’面に沿って切断して示す概略的断面図である。
【図４】図２に示す回転子の斜視図である。
【符号の説明】
２１２ 渦巻き室
２１９ パイプ
２２０ ディストリビュータ
２２２ バグフィルター
２２４ 吸引ブロワ
２２９ 捕集サイクロン
３０１ 機械式粉砕機
３１０ 固定子
３１１ 原料投入口
３１２ 中心回転軸
３１３ ケーシング
３１４ 回転子
３１５ 定量供給機
３１６ ジャケット
３２０ 後室[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electrophotographic image forming method for developing an electrostatic image, and a developing toner used in a toner jet.
[0002]
[Prior art]
An apparatus using electrophotographic technology is widely used not only in a copying machine for copying an original document but also in a field such as a printer or a facsimile as an output of a computer.
[0003]
In recent years, such devices have been rigorously pursued for improvements such as smaller, lighter, faster, and more reliable, and such devices are composed of simpler elements in various respects. Tend to be. As a result, the performance required for the toner becomes higher, and if the improvement in the performance of the toner cannot be achieved, it tends to be difficult to establish a more excellent device.
[0004]
In addition, various development methods have been put to practical use in electrophotographic development methods. Among them, a simple developing device has few troubles, long life, and easy maintenance. Component development is preferably used. In such a developing method, the quality of image formation greatly depends on the performance of the magnetic toner. In the magnetic toner, the magnetic iron oxide is made magnetic by containing the magnetic iron oxide, so that the magnetic iron oxide affects the developability and durability of the magnetic toner.
[0005]
In view of this technical background, in recent years, various techniques for improving toner performance have been proposed. As such a technique, the toner is dispersed in an ethanol / water mixed solution, the absorbance at that time is measured, and the amount of magnetic iron oxide present on the surface of the magnetic toner is known, so that a charging roller caused by the magnetic toner is obtained. There is known a technique that can easily know how much dirt or fusing of magnetic toner to a photosensitive drum occurs (see, for example, Patent Document 1). However, even if the toner with a small amount of magnetic iron oxide on the surface is effective for the above-mentioned dirt and fusion, the presence of magnetic iron oxide on the surface of the magnetic toner cannot be said to be appropriate. There are problems such as poor charging of the magnetic toner due to too little magnetic iron oxide on the toner surface and deterioration of image quality due to uneven charging distribution of the magnetic toner.
[0006]
As for the toner, a technique relating to a toner having a certain wetting property with respect to ethanol is known (for example, see Patent Document 2). This wetting property is a hydrophobic property of the toner represented by an ethanol drop transmittance curve, and is determined by measuring the transmittance with respect to the ethanol content. Although the toner having such characteristics is effective in preventing drum fusion and suppressing image flow, the dispersion state of raw materials on the surface of the toner is not sufficiently controlled, and is caused by the surface state of the toner. There is still room for improvement regarding the control of the toner charge amount.
[0007]
Further, the magnetic iron oxide used in the magnetic toner contains 1.7 to 4.5 atomic% of silicon with respect to Fe in terms of Si, and metal elements other than iron include Mn, Zn, Ni, Cu, Al, Magnetite particles containing 0 to 10 atomic percent of one or more metal elements selected from Ti with respect to Fe are known (see, for example, Patent Documents 3 and 4). According to the magnetite particles, the magnetic properties and charging properties of the magnetic toner are improved. However, simply adding the above metal leaves room for improvement in terms of compatibility between developability and image quality in a high-speed development system. Has been.
[0008]
Further, as the magnetite particles, Zn, Mn, Cu, Ni, Co, Cr, which contains a silicon component continuously from the center of the magnetite particle to the surface, the silicon component is exposed on the particle surface, and is bonded to the silicon component. There is known a magnetite particle in which a particle outer shell is coated with a metal compound composed of at least one metal component selected from Cd, Al, Sn, Mg, and Ti (see, for example, Patent Document 5). However, the use of such magnetite particles has not yet improved the deterioration in image quality and developability associated with long-term use, particularly in a high-speed development system, and has further points to be improved.
[0009]
Further, as the magnetic iron oxide, based on the iron element, the content of one or more metal elements selected from the group consisting of Mn, Zn, Ni, Cu, Co, Cr, Cd, Al, Sn, and Mg, and Magnetic iron oxides are known that define the silicon element content, the content ratio of silicon elements present up to 20 mass% of iron element, and the content ratio of silicon elements present up to 10% of iron element solubility. (For example, see Patent Documents 6, 7, and 8.) According to such magnetic iron oxide, although various metals are contained in the magnetic iron oxide and the distribution of Si in the magnetic iron oxide is regulated, an improvement effect is seen in environmental stability, but a high-speed development system Further improvement is desired with regard to durability.
[0010]
Further, as the magnetite particles, Zn, Mn, Cu, which contains a silicon component and an aluminum component continuously from the center of the magnetite particle to the surface, are exposed to the particle surface, and are bonded to the silicon component and the aluminum component. Magnetite particles having a particle outer shell coated with a metal compound composed of at least one metal component selected from Ni, Co, Cr, Cd, Al, Sn, Mg, and Ti are known (for example, Patent Document 9). reference.). However, the use of the magnetite particles has not yet provided sufficient charging stability to the magnetic toner.
[0011]
As for the magnetic properties of the toner, a method is known in which the saturation magnetization of the toner is reduced by replacing the divalent iron of magnetite with a divalent metal such as zinc or copper (for example, Patent Documents 10 and 11). reference.). However, in such a method, it is not sufficient to control the charge amount of the toner in the high-speed development system only by controlling the magnetic properties of the magnetic material and the toner.
[0012]
[Patent Document 1]
JP 11-194533 A
[Patent Document 2]
JP 2000-242027 A
[Patent Document 3]
Japanese Patent Laid-Open No. 9-59024
[Patent Document 4]
JP-A-9-59025
[Patent Document 5]
JP 11-157843 A
[Patent Document 6]
JP 11-316474 A
[Patent Document 7]
Japanese Patent Laid-Open No. 11-249335
[Patent Document 8]
Japanese Patent Laid-Open No. 11-282201
[Patent Document 9]
Japanese Patent Laid-Open No. 11-189420
[Patent Document 10]
JP-A-4-184354
[Patent Document 11]
JP-A-4-223487
[0013]
[Problems to be solved by the invention]
An object of the present invention is to provide a toner that solves the above-mentioned problems, and the charge amount of the toner rises quickly even in a high-speed development system, and image quality deterioration and image density reduction do not occur even in long-term use. Another object is to provide a toner having excellent environmental stability.
[0014]
[Means for Solving the Problems]
The present invention relates to a toner having at least a binder resin and magnetic iron oxide, wherein the binder resin contains a polyester resin as a main component, and the magnetic iron oxide is composed of Si, Mg, Cu, Zn, Ti, and Al. And the content of Si in the magnetic iron oxide is 0.1 to 2.0% by mass based on the magnetic iron oxide, and the content of the element α in the magnetic iron oxide. Content is 0.1-4.0 mass% on the basis of magnetic iron oxide, and atomic concentration of element (alpha) in the outermost surface of magnetic iron oxide measured by X ray photoelectron spectroscopy is 1.00-7. When the wettability of the toner with respect to the mixed solvent of methanol and water is measured by the transmittance of light having a wavelength of 780 nm, the methanol concentration when the transmittance is 80% is within the range of 45 to 65% by volume. ,Also, Methanol concentration when the excessive rate of 10% related to dry toner is in the range of 45 to 65 vol%.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
The present inventors have developed a magnetic toner having a polyester resin by controlling the wettability of the magnetic toner to a specific solvent and controlling the atomic concentration of a specific metal element present on the outermost surface of the magnetic iron oxide. The present invention has been found to be extremely excellent in properties, durability and fluidity, and that excellent developability can be obtained even in high-speed development.
[0016]
In the dry toner of the present invention, when the wettability of the toner with respect to a mixed solvent of methanol and water is measured by the transmittance of light having a wavelength of 780 nm, the methanol concentration when the transmittance is 80% is in the range of 45 to 65% by volume. In addition, the methanol concentration when the transmittance is 10% is in the range of 45 to 65% by volume. According to such characteristics, a dry toner can be obtained in which charging characteristics are stabilized and excellent developability is exhibited even in each environment such as low temperature and low humidity and high temperature and high humidity.
[0017]
FIG. 1 shows a graph of methanol concentration versus light transmittance at a wavelength of 780 nm of the dry toner of Example 1 described later. A region where the transmittance exceeds 80% indicates that the dry toner is almost not wet with methanol, and a region where the transmittance is lower than 10% indicates that the dry toner is almost completely wetted.
[0018]
The wettability of the dry toner of the present invention to a mixed solvent of methanol and water (hereinafter also referred to as “methanol-water mixed solvent”) is greatly influenced by the surface material composition of the toner particles and the presence state thereof. The smaller the exposure of the magnetic iron oxide on the surface of the toner particles, that is, the higher the proportion of the toner particle surface covered with the binder resin component, the higher the concentration of methanol particles gets wet. As the ratio of the binder resin component on the toner particle surface increases, the chargeability of the dry toner is improved and higher developability can be obtained. On the contrary, if the exposure of the magnetic iron oxide is too small, the dry toner of the present invention cannot obtain an appropriate charging performance, which is not preferable.
[0019]
Further, the more the magnetic iron oxide is exposed, that is, the smaller the proportion of the toner particle surface covered with the binder resin component, the more the toner particles become wet at a lower methanol concentration. As the ratio of the magnetic iron oxide on the toner particle surface increases, the charge leakage site of the dry toner of the present invention increases, so that it is difficult to maintain the charge amount and it is difficult to obtain good developability.
[0020]
That is, as shown in FIG. 1, when the methanol concentration of the mixed solvent is 45 to 65% by volume and the transmittance reaches 80%, the methanol concentration is 45 to 65% by volume and the transmittance reaches 10%. This means that the particles have moderate wettability with water (hydrophobic properties with respect to water), means that the surface material composition in the toner particles and the state of their presence are uniform, and are dry toners with excellent charging properties. It means that there is.
[0021]
When the wettability of the dry toner of the present invention to a methanol-water mixed solvent is measured by the transmittance of light having a wavelength of 780 nm, the methanol concentration when the transmittance is 80% is 45 to 65% by volume, preferably 50. It is -65 volume%, More preferably, it exists in the range of 55-65 volume%. The methanol concentration of the mixed solvent within the above range indicates that the ratio of the binder resin exposed on the surface of the toner particles to the magnetic iron oxide is within the proper range, and the dry toner of the present invention is properly charged. It shows that the amount can be kept.
[0022]
That is, when the ratio of the exposed binder resin to magnetic iron oxide is within an appropriate range, the binder resin component is sufficiently and moderately present on the surface of the toner particles to increase the chargeability of the dry toner, and the magnetic iron oxide Represents that the dry toner is prevented from being excessively charged by being appropriately exposed.
[0023]
If the methanol concentration when the transmittance is 80% is lower than 45% by volume, it means that there are a large number of toner particles in which a large amount of magnetic iron oxide is exposed on the surface. The chargeability of the toner becomes insufficient and the developability becomes poor. If the methanol concentration exceeds 80% by volume when the transmittance is 80%, it means that there are many toner particles with little exposure to the surface of the magnetic iron oxide, and the dry toner tends to be excessively charged. If the sufficient charge amount cannot be maintained, the image density may decrease and fogging may increase.
[0024]
Further, when the wettability of the dry toner of the present invention to a methanol-water mixed solvent is measured by the transmittance of light having a wavelength of 780 nm, the methanol concentration when the transmittance is 10% is 45 to 65% by volume, preferably Is from 50 to 65% by volume, more preferably from 55 to 65% by volume. The fact that the methanol concentration of the mixed solvent is within the above range indicates that the exposure ratio of the binder resin and magnetic iron oxide on the surface of most of the toner particles is in an appropriate range, and the dry toner has an appropriate charge amount. It can be kept.
[0025]
If the methanol concentration when the transmittance is 10% is lower than 45% by volume, most of the toner particles in the dry toner have a large proportion of magnetic iron oxide exposed on the surface. Becomes insufficient and developability becomes poor. If the methanol concentration when the transmittance is 10% exceeds 65% by volume, the ratio of the toner particles having the magnetic iron oxide properly exposed on the surface is small, and the dry toner tends to be excessively charged, The charge amount cannot be maintained, and the image density may decrease and fog may increase.
[0026]
In the present invention, the relationship between the transmittance and the methanol concentration, that is, the wettability of the dry toner, that is, the hydrophobic property of the dry toner is measured using a methanol dropping transmittance curve. Specifically, as the measuring device, for example, a powder wettability tester WET-100P manufactured by Reska Co., Ltd. may be mentioned, and specific measuring operations may include the methods exemplified below.
[0027]
First, 70 ml of a hydrated methanol solution composed of 40% by volume of methanol and 60% by volume of water is placed in a container and dispersed for 5 minutes with an ultrasonic disperser in order to remove bubbles and the like in the measurement sample. To this, 0.5 g of a dry toner as a specimen is precisely weighed and added to prepare a sample solution for measuring the hydrophobic characteristics of the dry toner.
[0028]
Next, this sample solution for measurement was 6.67 s. ^-1 Methanol at 1.3 ml / min. Are continuously added at a dropping rate of, and the transmittance is measured with light having a wavelength of 780 nm to prepare a methanol dropping transmittance curve as shown in FIG. In this case, methanol was used as the titration solvent because various toner materials such as dyes, pigments, and charge control agents contained in the toner particles are less likely to elute and the surface condition of the dry toner can be observed more accurately. It is. In this measurement, the container has a cylindrical shape with a bottom diameter of 5 cm and a glass beaker with a thickness of 1.75 mm. The magnetic stirrer has a spindle shape with a length of 25 mm and a maximum diameter of 8 mm, and fluorine. The one coated with resin was used.
[0029]
In the case where the dry toner gets wet when the methanol concentration is less than 40% by volume, the transmittance with light having a wavelength of 780 nm rapidly decreases and approaches 0% just by adding the dry toner to the mixed solvent and stirring. .
[0030]
The dry toner of the present invention has magnetic iron oxide. This magnetic iron oxide contains Si and an element α which is at least one element selected from Mg, Cu, Zn, Ti, and Al, and the content of Si in the magnetic iron oxide is based on the magnetic iron oxide. The content of the element α in the magnetic iron oxide is 0.1 to 4.0% by mass based on the magnetic iron oxide, and X-ray photoelectron spectroscopy (XPS) The atomic concentration of the element α on the outermost surface of the magnetic iron oxide measured by the above is characterized by being 1.00 to 7.00%.
[0031]
The element α is at least one element selected from Mg, Cu, Zn, Ti, and Al, preferably an element selected from Mg, Zn, and Al. Content of element (alpha) is 0.1-4.0 mass% on the basis of magnetic iron oxide, More preferably, it is 0.1-2.0 mass%.
[0032]
The magnetic iron oxide containing the element α has an excellent balance such as the degree of exposure of the magnetic iron oxide particles to the surface of the toner particles, and can keep the toner charge amount high regardless of the environment. Further, it has a function of controlling the toner charge amount distribution to be narrow. As a result, narrow and short spikes can be densely formed on the developer carrier, and high image density performance can be obtained with high image quality (dot reproducibility, etc.).
[0033]
When the content of the element α is less than 0.1% by mass, the electric resistance of the magnetic iron oxide itself is lowered, and it becomes difficult to maintain the charge amount of the toner in an environment such as high temperature and high humidity. May lead to a decrease in concentration. On the other hand, when the content of the element α is less than 0.1% by mass, the magnetic iron oxide is difficult to be exposed on the surface of the toner particles, which may cause a decrease in density and an increase in fog due to charge-up.
[0034]
When the content of the element α is more than 4.0% by mass, the electric resistance of the magnetic iron oxide itself is excessively increased and fogging may increase. In addition, since the toner charge amount rises at a slower rate, the toner charge amount distribution tends to be broad, and the toner spikes on the developer carrier become non-uniform, resulting in dot reproducibility and on paper. Scattering tends to get worse.
[0035]
Furthermore, the magnetic iron oxide used in the present invention contains at least Si. Content of Si in magnetic iron oxide is 0.1-2.0 mass% on the basis of magnetic iron oxide, More preferably, it is 0.3-1.8 mass%.
[0036]
If the Si content is less than 0.1% by mass, the toner cannot obtain a desired charge amount, and the rise of the charge amount is delayed, which may cause a decrease in image density. When the Si content is more than 2.0% by mass, the charge amount of the toner is too high, which may cause a decrease in density and an increase in fog due to charge-up.
[0037]
The magnetic iron oxide used in the present invention has an atomic concentration of element α on the outermost surface measured by X-ray photoelectron spectroscopy (XPS) of 1.00 to 7.00%, more preferably 1.00. ~ 6.00%.
[0038]
When the atomic concentration of the element α is less than 1.00%, the surface electric resistance of the magnetic iron oxide itself is lowered, and it becomes difficult to maintain the charge amount of the dry toner in an environment such as high temperature and high humidity. May lead to a decrease in image density. Further, if the atomic concentration of the element α on the outermost surface is less than 1.00%, the magnetic iron oxide becomes difficult to be exposed on the surface of the toner particles, which may cause a decrease in concentration due to charge-up and an increase in fog. When the concentration of the element α on the outermost surface is higher than 7.00%, the surface electric resistance of the magnetic iron oxide itself is excessively increased and fogging may increase.
[0039]
Here, the dry toner of the present invention will be described from the viewpoint of the charge amount distribution.
In continuous development in a high-speed development system, it is particularly required that a magnetic toner regulated by a regulation blade on a developer carrier, so-called development sleeve, be charged quickly and uniformly. As a result, it is possible to always provide a good image even in a high-speed development system. However, if the magnetic toner is charged unevenly and the distribution of the charge amount varies, When an image is developed, there is a large variation between the charge amount of the magnetic toner supplied on the developing sleeve and the charge amount of the magnetic toner on the developing sleeve, and an image with much scattering may be generated. Furthermore, toner spikes on the developing sleeve become non-uniform and dot reproducibility tends to deteriorate.
[0040]
The charge amount distribution of the magnetic toner is greatly influenced by the material dispersibility on the surface of the magnetic toner, and the charge amount distribution becomes uniform as the uniformity of the material dispersibility increases. In the present invention, the material dispersibility on the surface of the dry toner can be determined by measuring the wettability behavior of the dry toner with respect to the methanol-water mixed solvent. The more uniform the material dispersibility on the surface, the smaller the concentration difference of methanol from the start of wetness of the dry toner to the methanol-water mixed solvent until the end of wetness.
[0041]
In the present invention, when the wettability of the toner with respect to a mixed solvent of methanol and water is measured by the transmittance of light having a wavelength of 780 nm, the methanol concentration when the transmittance is 80% is within the range of 45 to 65% by volume. The methanol concentration when the transmittance is 10% is in the range of 45 to 65% by volume. Thus, in the dry toner of the present invention, the difference in concentration between the methanol concentration when the transmittance is 80% and the methanol concentration when the transmittance is 10% is small, which means that the charge amount distribution of the dry toner is uniformized. This shows that uniform and high chargeability can be quickly imparted to the dry toner. Moreover, the magnetic iron oxide used in the present invention can further promote this effect.
[0042]
In addition, magnetic toner having high chargeability is poor in fluidity, the magnetic toner tends to aggregate locally on the developing sleeve, and the coating state of the developing sleeve becomes uneven as a result, resulting in an image density. In the present invention, at least the atomic concentration and the atomic ratio of the element α on the surface of the magnetic iron oxide are controlled, so that the magnetic iron oxide on the surface of the dry toner is reduced. Can promote uniform charge and prevent this phenomenon.
[0043]
Since the present invention has moderate methanol wettability, the magnetic iron oxide is uniformly exposed on the surface of the dry toner. In other words, the ratio of exposure of the magnetic iron oxide to the surface of the dry toner is small, but by controlling the atomic concentration and atomic ratio of iron, silica, and zinc on the outermost surface of the magnetic iron oxide, it is more effective with a small exposure amount. Can be demonstrated. In addition, this makes it possible to impart good fluidity to the dry toner without impairing the high and uniform chargeability of the dry toner. Even when it starts, it is possible to maintain developability and effectively prevent image deterioration.
[0044]
As a result, it becomes possible to impart good fluidity to the dry toner without impairing the high and uniform chargeability of the dry toner, and the in-machine temperature in the image forming apparatus rises and the dry toner is exposed to stress. Even when toner deterioration starts, the present invention can maintain good developability and can effectively prevent image deterioration.
[0045]
Regarding the toner charge amount distribution in the present invention, the methanol concentration when the transmittance is 80% is lower than 45% by volume, or the methanol concentration when the transmittance is 10% is lower than 45% by volume. In other words, the charge amount distribution of the dry toner becomes broad, the developability is inferior, the scattering and the dot reproducibility of minute portions may deteriorate. When the methanol concentration when the transmittance is 80% exceeds 65% by volume, or when the methanol concentration exceeds 65% by volume when the transmittance is 10%, the dry toner becomes excessively charged or the dry toner is charged. The amount distribution becomes broad and non-uniformly charged toner particles exist, which may deteriorate image quality such as uniformity of image density and dot reproducibility.
[0046]
In the present invention, at least one element α selected from Mg, Cu, Zn, Ti, and Al is simultaneously present on the outermost surface of the magnetic iron oxide at a certain ratio at the same time. And the electric resistance are balanced to control the charge amount of the toner, and as a result, it is preferable for obtaining developability with high image density and high image quality regardless of the environment.
[0047]
That is, in the present invention, the atomic concentration of Si atoms on the outermost surface of the magnetic iron oxide measured by X-ray photoelectron spectroscopy (XPS) is 12.5 to 17.5% (more preferably 12.50 to 17.5. And the atomic concentration of Fe atoms is preferably 70.00 to 85.00% (more preferably 75.00 to 85.00%).
[0048]
In the present invention, the ratio of the element α to Si atoms, that is, the element α / Si is 0.05 to 0.5 (at the outermost surface of the magnetic iron oxide measured by X-ray photoelectron spectroscopy (XPS). More preferably 0.05 to 0.40), and the ratio of Fe atoms to Si atoms, that is, Fe / Si is 3.00 to 7.00 (more preferably 4.00 to 7.00). It is preferable that the ratio of Fe atom to element α, that is, Fe / element α is 10.0 to 70.0 (more preferably 10.00 to 65.00).
[0049]
When the concentration of Si atoms on the outermost surface is less than 12.50%, the dry toner cannot obtain a desired charge amount, and the rise of the charge amount is also delayed, and when an image is formed with such a toner. The image density may be reduced. If the concentration of Si atoms on the outermost surface is higher than 17.50%, the charge amount of the toner is too high, and this may cause a decrease in density and an increase in fog due to charge-up.
[0050]
In addition, when the concentration of Fe atoms on the outermost surface is less than 70.00%, the electrical resistance of the surface of the magnetic iron oxide itself decreases, making it difficult to maintain the charge amount of the dry toner in an environment such as high temperature and high humidity. As a result, the image density may be lowered in the morning. If the concentration of Fe atoms on the outermost surface is higher than 85.00%, the rate of rise of the charge amount of the dry toner becomes slow, so the distribution of the charge amount as a toner tends to be broad, and the toner on the developer carrying member is Earing becomes uneven and dot reproducibility and scattering on paper may deteriorate.
[0051]
In addition, when the element α / Si is less than 0.05, the charge amount of the dry toner increases, but the surface electric resistance of the magnetic iron oxide itself decreases. It is difficult to maintain the amount of charge in an environment such as high temperature and high humidity, resulting in a decrease in image density in the morning. When the element α / Si is larger than 0.50, not only the rising of the charge amount of the dry toner is delayed, but also the surface electric resistance of the magnetic iron oxide itself is excessively increased and fogging may be increased.
[0052]
Further, when the Fe / Si is less than 3.00, the charge amount of the dry toner is increased, but the surface electric resistance of the magnetic iron oxide itself is reduced. It may be difficult to maintain the charge amount in an environment such as high temperature and high humidity, and as a result, the image density may be lowered in the morning. When the Fe / Si ratio is larger than 7.00, the dry toner cannot obtain a desired charge amount, and the rise of the charge amount is delayed, which may cause a decrease in image density. Furthermore, since the rate of rise of the charge amount of the dry toner is slow, the charge amount distribution as a dry toner tends to be broad, and the toner rises unevenly on the developer carrier, resulting in dot reproducibility and on paper. Splattering may worsen.
[0053]
On the other hand, when the Fe / element α is less than 10.00, the surface electric resistance of the magnetic iron oxide itself is excessively increased and fogging may increase. When Fe / element α is larger than 70.00, the electric resistance of the magnetic iron oxide itself is lowered, and it becomes difficult to maintain the charge amount of the dry toner in an environment such as high temperature and high humidity. May lead to Furthermore, the magnetic iron oxide is less likely to be exposed on the toner particle surface, which may lead to a decrease in density and an increase in fog due to charge-up.
[0054]
As described above, when the configuration state of the atoms on the outermost surface of the magnetic iron oxide is out of the above range, the balance between the electric resistance and the charging property of the magnetic iron oxide itself cannot be achieved, the image density is lowered, the fog is deteriorated, the dot reproducibility, It may lead to deterioration of scattering on the paper, which is not preferable.
[0055]
The magnetic iron oxide used in the present invention uses an appropriate salt containing Si atoms and an appropriate salt containing the element α, and appropriately adjusts the pH in the reaction system when producing ordinary magnetic iron oxide. It is possible to manufacture with. Taking the case of using zinc as the element α as an example, the method for producing magnetic iron oxide used in the present invention will be described below.
[0056]
In the magnetic iron oxide according to the present invention, after adding a predetermined amount of a metal salt of Zn and a silicate to an aqueous ferrous salt solution, an alkali such as sodium hydroxide or more equivalent to the iron component is added, and water is added. An aqueous solution containing ferrous oxide is prepared. Air was blown in while maintaining the pH of the prepared aqueous solution at pH 7 or higher (preferably pH 8 to 10), and iron oxide hydroxide was oxidized while heating the aqueous solution to 70 ° C. or higher. First, a seed crystal is formed.
[0057]
Next, an aqueous solution containing a first equivalent of ferrous sulfate is added to the slurry-like liquid containing seed crystals based on the amount of alkali added previously. Then, while maintaining the pH of the liquid at 6 to 10, the reaction of ferrous hydroxide proceeds while blowing air, and the magnetic iron oxide particles are grown with the seed crystal as the core. In the magnetic iron oxide characterized in that the composition ratio of the elements on the outermost surface of the magnetic iron oxide is kept constant, the progress of the oxidation reaction is advanced step by step in combination with the adjustment of the pH. For example, the oxidation reaction proceeds in a stepwise manner depending on the pH, such that the pH is 9 to 10 at the beginning of the reaction, the pH is 8 to 9 in the middle of the reaction, and the pH is 6 to 8 in the late reaction. Thus, the composition ratio of the outermost surface of magnetic iron oxide can be controlled more easily. Further, the pH of the liquid shifts to the acidic side as the oxidation reaction proceeds, but it is preferable that the pH of the liquid not be less than 6.
[0058]
Examples of the metal salt containing silicon or element α to be added include sulfate, nitrate, and chloride of silicon or element α. Silicon may be used as a silicate. Examples of the silicate added include sodium silicate and potassium silicate.
[0059]
As ferrous salts, it is possible to use iron sulfate generally produced as a by-product in the production of sulfuric acid method titanium, iron sulfate produced as a by-product when the surface of the copper plate is cleaned, and iron chloride, etc. should also be used. Is possible.
[0060]
In a method for producing magnetic iron oxide by an aqueous solution method, generally, an iron salt is used at an iron concentration of about 0.5 to 2 mol / liter from the viewpoint of preventing an increase in viscosity during reaction and solubility of iron sulfate. . The iron sulfate concentration generally tends to be finer as the product becomes thinner. In the reaction, the larger the amount of air and the lower the reaction temperature, the easier the atomization.
[0061]
According to the above-described manufacturing method, the magnetic iron oxide particles are mainly composed of spherical particles formed with a curved surface having no plate-like surface as observed with a transmission electron micrograph, and the magnetic iron oxide hardly contains octahedral particles. Iron oxide can be generated, and in the present invention, it is preferable to use magnetic iron oxide having such a particle shape.
[0062]
Furthermore, in the present invention, the magnetic iron oxide has a bulk density of 0.3 to 2.0 g / cm. ^Three Preferably, 0.5 to 1.3 g / cm ^Three It is more preferable that Bulk density is 0.3g / cm ^Three If it is less than the range, it tends to adversely affect the physical mixing properties of the toner with other constituent materials at the time of toner production, and the dispersibility of the magnetic iron oxide in the dry toner may deteriorate.
[0063]
Further, in the present invention, the magnetic iron oxide has a number average particle diameter of 0.05 to 1.00 μm from the viewpoint of dispersibility of the magnetic iron oxide in the binder resin and uniformity of the charge of the dry toner. Preferably, it is 0.10 to 0.40.
[0064]
In the present invention, the magnetic iron oxide has a BET specific surface area of 15.0 m. ² / G or less, and further 12.0m ² / G or less is preferable. BET specific surface area of magnetic iron oxide particles is 15.0m ² When the amount exceeds / g, the moisture adsorption property of the magnetic iron oxide particles increases, which affects the hygroscopicity and chargeability of the dry toner containing the magnetic iron oxide particles.
[0065]
Further, in the present invention, magnetic iron oxide has a magnetic property of 10 to 200 Am in saturation magnetization under a magnetic field of 795.8 kA / m. ² / Kg (more preferably 70-100 Am ² / Kg), and the residual magnetization is 1 to 100 Am. ² / Kg (more preferably 2 to 20 Am ² / Kg), and the coercive force is preferably 1 to 30 kA / m (more preferably 2 to 15 kA / m). It is preferable that the magnetic iron oxide has the magnetic properties as described above in order to obtain a dry toner having good developability in which image density and fog are balanced.
[0066]
The dry toner of the present invention preferably contains 30 to 150 parts by mass of magnetic iron oxide with respect to 100 parts by mass of the binder resin. When the content of the magnetic iron oxide is less than 30 parts by mass, the transportability of the dry toner during development is insufficient, and the dry toner layer on the developer carrying member may be uneven, resulting in image unevenness. . Further, since the degree of exposure of the magnetic iron oxide to the toner surface is reduced, the dry toner is excessively charged and cannot maintain an appropriate charge amount, so that the image density may be lowered and fogging may be increased. When the content of magnetic iron oxide exceeds 150 parts by mass, there are many toner particles with a large amount of magnetic iron oxide exposed on the surface, so that charging leakage sites increase and the dry toner cannot be charged sufficiently. It becomes inferior in developability.
[0067]
In the present invention, the magnetic iron oxide may be treated with a surface treatment agent such as a silane coupling agent, a titanium coupling agent, titanate, aminosilane, or an organosilicon compound.
[0068]
The preferable measuring method of the various physical property data regarding the magnetic iron oxide used for this invention is explained in full detail below.
[0069]
(1) Analysis of the outermost surface of magnetic iron oxide by X-ray photoelectron spectroscopy (XPS)
In the present invention, the composition ratio of the metal element on the outermost surface of magnetic iron oxide can be determined by the following method. For example, magnetic iron oxide powder is pressurized at 9.807 MPa using a tablet molding machine to mold pellets. The pellet is fixed on a carbon sheet on a sample holder, and is measured by, for example, the following measuring apparatus and measuring method.
[0070]

[0071]
The surface atomic concentration in magnetic iron oxide is obtained by estimating the surface atomic concentration from the measured peak intensity of each element and calculating the ratio of each atom from the estimated atomic concentration. In addition, for the calculation of the surface atom concentration, using the relative sensitivity factor provided by ULVAC-PHI, for the calculation of the surface metal atom concentration, after converting the atomic concentration of all metal atoms detected by the above measurement to 100%, A method of calculating the concentration of each metal atom can be used.
[0072]
(2) Determination of the amount of metal elements present in magnetic iron oxide
In the present invention, the content of metal elements other than iron in magnetic iron oxide (based on magnetic iron oxide) can be determined by the following method. For example, about 3 liters of deionized water is placed in a 5 liter beaker and heated in a water bath to 45 to 50 ° C. About 25 g of magnetic iron oxide slurried with about 400 ml of deionized water is added to a 5 liter beaker together with the deionized water while being washed with about 300 ml of deionized water.
[0073]
Next, the temperature is about 50 ° C., and the stirring speed is about 3.33 s. ^-1 While maintaining the solution, add special grade hydrochloric acid or a mixed acid of hydrochloric acid and hydrofluoric acid, and start dissolution. At this time, the aqueous hydrochloric acid solution is adjusted to about 3 mol / liter. About 20 ml of the solution that has been completely dissolved and cleared is sampled, filtered through a 0.1 μm membrane filter, and the filtrate is collected. The filtrate is measured by plasma emission spectroscopy (ICP) to quantify iron elements and metal elements other than iron elements. The content of metal elements other than iron elements when magnetic iron oxide is used as a reference is calculated by the following equation.
[0074]
[Expression 1]
Metal element content based on magnetic iron oxide (mass%)
= {(C × d) / (e × 1000)} × 100
(Where c is the metal element concentration (mg / l) in the sample collected, d is the sample amount (l) collected, and e is the weight (g) of magnetic iron oxide.)
[0075]
(3) Bulk density of magnetic iron oxide
The bulk density of the magnetic iron oxide used in the present invention can be measured according to the pigment test method of JIS K 5101.
[0076]
(4) Number average particle diameter of magnetic iron oxide
The number average particle diameter of the magnetic iron oxide used in the present invention is obtained from a transmission electron micrograph (magnification of 30000 times), randomly selecting 100 particles on the photograph, measuring the particle diameter, and obtaining the average value. Can do.
[0077]
(5) Specific surface area of magnetic iron oxide
The specific surface area of the magnetic iron oxide used in the present invention is determined by adsorbing nitrogen gas on the sample surface using a specific surface area measuring device Auto Soap 1 (manufactured by Yuasa Ionics) according to the BET method, and using the BET multipoint method. Can be calculated.
[0078]
(6) Magnetic properties of magnetic iron oxide
The magnetic properties of the magnetic iron oxide used in the present invention can be measured under an external magnetic field of 795.8 kA / m using, for example, a “vibrating sample magnetometer VSM-3S-15” (manufactured by Toei Kogyo Co., Ltd.). it can.
[0079]
The dry toner of the present invention contains a binder resin. In the present invention, the binder resin contains a polyester resin as a main component. Here, “containing a polyester resin as a main component” means that the polyester resin is used in 60% by mass or more of the binder resin. As the subcomponent, various resin compounds conventionally known as binder resins can be used.
[0080]
As is well known, the polyester resin is obtained by polycondensation of a dihydric or higher polyhydric alcohol and a dihydric or higher polyvalent organic acid, and generally has a polar carboxyl group at its end. In this case, this carboxyl group interacts with at least one element α selected from Mg, Cu, Zn, Ti, and Al in the magnetic iron oxide, thereby improving the dispersion state of the raw material in the dry toner. That is, by using a polyester resin as the binder resin in the present invention, the dispersibility of the raw materials is synergistically increased, the charge amount distribution becomes uniform, and a dry toner having excellent developability even in a high-speed development system can be obtained. Can do it.
[0081]
The polyester resin used in the present invention is specifically shown below. It is preferable that 45 to 55 mol% of the polyester resin is an alcohol component and 55 to 45 mol% is an acid component in all components.
[0082]
As alcohol components, ethylene glycol, propylene glycol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, diethylene glycol, triethylene glycol, 1,5-pentanediol, 1,6-hexane Diol, neopentyl glycol, 2-ethyl-1,3-hexanediol, hydrogenated bisphenol A, bisphenol derivatives represented by the following formula (B); diols represented by the following formula (C); and glycerin, sorbit And trihydric or higher polyhydric alcohols such as sorbitan.
[0083]
[Chemical 1]

[0084]
[Chemical 2]

[0085]
As the acid component, carboxylic acid can be preferably exemplified, and as the divalent carboxylic acid, benzenedicarboxylic acids such as phthalic acid, terephthalic acid, isophthalic acid, and phthalic anhydride or anhydrides thereof; succinic acid, adipine Alkyl dicarboxylic acids such as acid, sebacic acid and azelaic acid or anhydrides thereof; unsaturated dicarboxylic acids such as fumaric acid, maleic acid, citraconic acid, itaconic acid or anhydrides thereof; Examples of the acid include trimellitic acid, pyromellitic acid, benzophenone tetracarboxylic acid and its anhydride.
[0086]
A particularly preferable alcohol component of the polyester resin is a bisphenol derivative represented by the above formula (B), and examples of the acid component include phthalic acid, terephthalic acid, isophthalic acid or anhydride thereof, succinic acid, n-dodecenyl succinic acid or anhydride thereof. Products, dicarboxylic acids such as fumaric acid, maleic acid and maleic anhydride; trimellitic acid or tricarboxylic acids of anhydride thereof.
[0087]
The use of the polyester resin obtained from these acid components and alcohol components as a binder resin provides good fixing when the dry toner of the present invention is used in an image forming process using heat roller fixing in image fixing. This is preferable in realizing high performance and excellent offset resistance.
[0088]
The acid value of the polyester resin used in the present invention is preferably 10 to 50 mgKOH / g, more preferably 10 to 45 mgKOH / g, and further preferably 10 to 40 mgKOH / g. When the acid value of the polyester resin is larger than 50 mgKOH / g, the environmental dependency of the charging characteristics of the dry toner increases, and the flowability and electrostatic adhesion of the dry toner and the surface resistance of the dry toner (effect of adsorbed water) fluctuate. However, the image quality may be degraded. When the acid value of the resin is smaller than 10 mgKOH / g, the interaction with at least one element α selected from Mg, Cu, Zn, Ti and Al present on the surface of the magnetic iron oxide is weakened. As the dispersibility of the raw materials deteriorates and the distribution of the charge amount of the dry toner spreads, unevenly charged toner particles exist, and the image quality such as uniformity of image density and dot reproducibility may deteriorate. is there. The acid value of the polyester resin can be measured by a known method according to JIS K 0070.
[0089]
In the present invention, various resin compounds conventionally known as binder resins can be used in combination with a polyester resin as a binder resin. Examples of such resin compounds include vinyl resins, phenol resins, Natural resin modified phenolic resin, natural resin modified maleic acid resin, acrylic resin, methacrylic resin, polyvinyl acetate, silicone resin, polyester resin, polyurethane, polyamide resin, furan resin, epoxy resin, xylene resin, polyvinyl butyral, terpene resin, coumaroindene Examples thereof include resins and petroleum resins.
[0090]
The glass transition temperature of the binder resin used in the present invention is preferably 50 to 75 ° C, more preferably 55 to 65 ° C. Furthermore, the number average molecular weight (Mn) of the binder resin is preferably 1,500 to 50,000, and more preferably 2,000 to 20,000. The weight average molecular weight (Mw) of the binder resin is preferably 6,000 to 100,000, and more preferably 10,000 to 90,000.
[0091]
If the glass transition temperature of the binder resin is lower than the above range, the storage stability of the dry toner may be insufficient, and if the glass transition temperature of the binder resin is higher than the above range, the fixability of the dry toner may be poor. May be sufficient. The glass transition temperature of the binder resin can be measured using a differential scanning calorimeter described later.
[0092]
The number average molecular weight and weight average molecular weight of the binder resin can be measured by GPC (gel permeation chromatography) using THF (tetrahydrofuran) as a solvent. In the present invention, the molecular weight distribution by GPC using the toner and binder resin THF (tetrahydrofuran) as a solvent is measured under the following conditions.
[0093]
The sample is prepared as follows.
First, put the sample in THF, leave it for several hours, then shake well and mix well with THF (until the sample is no longer united) and let stand for more than 12 hours. At that time, the standing time in THF should be 24 hours or more. After that, a sample processed filter (pore size 0.2 to 0.5 μm, for example, Mysori Disc H-25-2 (manufactured by Tosoh Corporation) can be used) is used as a GPC sample. The sample concentration is adjusted so that the resin component is 0.5 to 5 mg / ml.
[0094]
An RI (refractive index) detector is used as the detector. As the column, it is preferable to combine a plurality of commercially available polystyrene gel columns. For example, a combination of shodex GPC KF-801, 802, 803, 804, 805, 806, 807, 800P manufactured by Showa Denko, TSKgel G1000H (H _XL ), G2000H (H _XL ), G3000H (H _XL ), G4000H (H _XL ), G5000H (H _XL ), G6000H (H _XL ), G7000H (H _XL ), A combination of TSKgull column.
[0095]
The column is stabilized in a heat chamber at 40 ° C., THF is flowed through the column at this temperature as a solvent at a flow rate of 1 ml / min, and about 100 μl of the THF sample solution is injected and measured.
[0096]
In measuring the molecular weight of a sample, the molecular weight distribution of the sample is calculated from the relationship between the logarithmic value of a calibration curve prepared from several types of monodisperse polystyrene standard samples and the count value. As a standard polystyrene sample for preparing a calibration curve, for example, a molecular weight of 10 manufactured by Tosoh Corporation or Showa Denko KK is 10 ² -10 ⁷ It is appropriate to use a standard polystyrene sample of about 10 points.
[0097]
In the dry toner of the present invention, it is preferable that at least one endothermic peak exists in the DSC curve at the time of temperature rise measured by a differential scanning calorimeter (DSC), and the endothermic peak exists at 60 to 120 ° C. This endothermic peak is preferably present at 65 to 120 ° C, more preferably 70 to 115 ° C. Two or more endothermic peaks may exist, and in that case, it is preferable to have at least one endothermic peak at 60 to 120 ° C.
[0098]
From the DSC curve at the time of temperature rise, the melting behavior accompanying the endotherm of the dry toner can be seen. When the endothermic peak is present at 60 to 120 ° C., the viscosity is sufficiently lowered when the dry toner is heated and melt-kneaded, and the magnetic iron oxide can be satisfactorily dispersed, which is preferable in terms of stabilizing the chargeability of the dry toner.
[0099]
The endothermic peak of the dry toner of the present invention can be obtained by selecting an appropriate wax and incorporating it in the dry toner. The wax capable of imparting such an endothermic peak to the dry toner easily imparts high hydrophobicity to the dry toner on the surface of the dry toner due to its melting characteristics, and imparts the wettability characteristic of the present invention to the dry toner. It is effective in doing.
[0100]
In the present invention, the DSC curve of the dry toner is in accordance with ASTM D3418-82 using a differential scanning calorimeter (DSC measuring device) such as DSC-7 (Perkin Elmer) or DSC2920 (TA Instruments Japan). Can be measured. The DSC curve is a DSC curve measured when the temperature is raised and lowered once, the previous history is taken, and then the temperature is raised at a rate of temperature rise of 10 ° C./min. The peak accompanying the glass transition point of the binder resin can be distinguished, for example, by measuring only the binder resin.
[0101]
The dry toner of the present invention may contain various materials other than the binder resin and magnetic iron oxide described above. Examples of such other materials include the waxes and charge control agents described above.
[0102]
Examples of the wax used in the present invention include various waxes such as low molecular weight polyethylene, low molecular weight polypropylene, polyolefin copolymer, polyolefin wax, microcrystalline wax, paraffin wax, and aliphatic hydrocarbon wax such as Fischer-Tropsch wax. An oxide of an aliphatic hydrocarbon wax such as oxidized polyethylene wax; or a block copolymer thereof; a plant wax such as candelilla wax, carnauba wax, wood wax, jojoba wax; beeswax, lanolin, whale wax Animal waxes such as: mineral waxes such as ozokerite, ceresin and petrolactam; waxes based on aliphatic esters such as montanate ester wax and castor wax; deoxidized carnauba wax Such that de-oxidation and the like of part or all of the aliphatic esters.
[0103]
Further, examples of the wax include saturated straight chain fatty acids such as palmitic acid, stearic acid, montanic acid, and long-chain alkyl carboxylic acids having a long-chain alkyl group; Saturated fatty acids; stearyl alcohol, eicosyl alcohol, behenyl alcohol, kaunavir alcohol, seryl alcohol, melyl alcohol, or saturated alcohols such as alkyl alcohols having a long-chain alkyl group; polyhydric alcohols such as sorbitol; linoleic acid amides; Aliphatic amides such as oleic acid amide and lauric acid amide; saturation such as methylene bis stearic acid amide, ethylene biscapric acid amide, ethylene bis lauric acid amide and hexamethylene bis stearic acid amide Aliphatic bisamides; unsaturated fatty acid amides such as ethylene bisoleic acid amide, hexamethylene bisoleic acid amide, N, N′-dioleyl adipic acid amide, N, N′-dioleyl sebacic acid amide; Aromatic bisamides such as stearamide, N, N'-distearylisophthalamide; aliphatic metal salts such as calcium stearate, calcium laurate, zinc stearate, magnesium stearate (generally referred to as metal soap) A wax grafted with an aliphatic hydrocarbon wax using a vinyl monomer such as styrene or acrylic acid; a partially esterified product of a fatty acid and a polyhydric alcohol such as behenic acid monoglyceride; by hydrogenating vegetable oils and fats; Has the resulting hydroxyl group Methyl ester compounds and the like that.
[0104]
In addition, these waxes have a sharp molecular weight distribution using a press sweating method, a solvent method, a recrystallization method, a vacuum distillation method, a supercritical gas extraction method or a melt liquid crystal deposition method, a low molecular weight solid fatty acid, a low molecular weight A solid alcohol, a low molecular weight solid compound, and other impurities are preferably used.
[0105]
Moreover, in this invention, it is preferable to add and use a charge control agent. In the present invention, both negatively charged and positively chargeable charge control agents can be used as the charge control agent.
[0106]
Specific examples of the negative charge control agent include monoazo dyes described in JP-B No. 41-20153, JP-B No. 42-27596, JP-B No. 44-6397, JP-B No. 45-26478, and the like. Nitrohumic acid and salts thereof described in JP-A-50-133838 or C.I. I. Dyes and pigments such as 14645, salicylic acid, naphthoic acid, dicarboxylic acid described in JP-B-55-42752, JP-B-58-41508, JP-B-58-7384, JP-B-59-7385, etc. Examples thereof include metal complexes of acids such as Zn, Al, Co, Cr, Fe, and Zr, sulfonated copper phthalocyanine pigments, nitro groups, styrene oligomers introduced with halogen, and chlorinated paraffins.
[0107]
In particular, an azo metal complex represented by the general formula (I) and a basic organic acid metal complex represented by the general formula (II) are excellent in dispersibility and effective in reducing the image density stability and fog. preferable.
[0108]
[Chemical 3]

[0109]
[Formula 4]

[0110]
Among them, the azo metal complex represented by the above formula (I) is more preferable, and the azo iron complex represented by the following formula (III) or (IV) in which the central metal is Fe is most preferable.
[0111]
[Chemical formula 5]

[0112]
[Chemical 6]

[0113]
Compounds of the following formulas (1) to (6), which are specific examples of the azo iron complex represented by the above formula (III), are shown.
[0114]
[Chemical 7]

[0115]
[Chemical 8]

[0116]
[Chemical 9]

[0117]
[Chemical Formula 10]

[0118]
Embedded image

[0119]
Embedded image

Moreover, the compound of the following formula (7)-(13) which is a specific example of the charge control agent shown by said formula (I), (II), (IV) is shown.
[0120]
Embedded image

[0121]
Embedded image

[0122]
Embedded image

[0123]
Embedded image

[0124]
Embedded image

[0125]
Embedded image

[0126]
Embedded image

[0127]
These metal complex compounds can be used alone or in combination of two or more.
[0128]
The amount of these charge control agents used varies depending on the type of the charge control agent, but from the viewpoint of the charge amount of the toner, generally 0.1 to 5.0 parts by mass per 100 parts by mass of the binder resin is preferable.
[0129]
On the other hand, as a charge control agent for controlling the dry toner to be positively charged, for example, modified products such as nigrosine and fatty acid metal salts, tributylbenzylammonium-1-hydroxy-4-naphthosulfonate, tetrabutylammonium tetrafluoroborate, etc. Quaternary ammonium salts thereof, and onium salts such as phosphonium salts thereof and their lake pigments, triphenylmethane dyes and lake lake pigments thereof (the rake agents include phosphotungstic acid, phosphomolybdic acid, Phosphotungstic molybdic acid, tannic acid, lauric acid, gallic acid, ferricyanide, ferrocyanide, etc.) metal salts of higher fatty acids; diorganotin oxides such as dibutyltin oxide, dioctyltin oxide, dicyclohexyltin oxide; dibuty Suzuboreto, dioctyl tin borate, diorgano tin borate such as dicyclohexyl tin borate; can be used in combination singly or in two or more.
[0130]
In the dry toner of the present invention, it is preferable to add an external additive to the toner particles composed of the above-described materials such as the binder resin and magnetic iron oxide. Examples of such external additives include inorganic fine powders and hydrophobic inorganic fine powders, and particularly preferable external additives include silica fine powders.
[0131]
As the silica fine powder used in the present invention, both a so-called dry method produced by vapor phase oxidation of a silicon halogen compound, or a so-called wet silica produced from water glass or the like, can be used. However, dry silica having less silanol groups on the surface and inside and having no production residue is preferable.
[0132]
Further, the silica fine powder used in the present invention is preferably hydrophobized. For the hydrophobizing treatment, a method of chemically treating with a hydrophobic compound such as an organosilicon compound that reacts or physically adsorbs with the silica fine powder is preferable. As a more preferable method, a method of treating a dry silica fine powder produced by vapor phase oxidation of a silicon halogen compound with an organosilicon compound such as silicone oil after treating with a silane compound or simultaneously with a silane compound. Can be mentioned.
[0133]
Examples of the silane compound used for the hydrophobization treatment include hexamethyldisilazane, trimethylsilane, trimethylchlorosilane, trimethylethoxysilane, dimethyldichlorosilane, methyltrichlorosilane, allyldimethylchlorosilane, allylphenyldichlorosilane, and benzyl. Dimethylchlorosilane, bromomethyldimethylchlorosilane, α-chloroethyltrichlorosilane, β-chloroethyltrichlorosilane, chloromethyldimethylchlorosilane, triorganosilane mercaptan, trimethylsilyl mercaptan, triorganosilyl acrylate, vinyldimethylacetoxysilane, dimethylethoxy Silane, dimethyldimethoxysilane, diphenyldiethoxysilane, hexamethyldisiloxane, 1,3-divinyltetramethyl Examples include tildisiloxane and 1,3-diphenyltetramethyldisiloxane.
[0134]
Examples of the organosilicon compound include silicone oil. Silicone oil has a viscosity of about 3 × 10 at 25 ° C. ^-Five ~ 1x10 ^-3 m ² For example, dimethyl silicone oil, methyl hydrogen silicone oil, methyl phenyl silicone oil, α-methyl styrene modified silicone oil, chlorophenyl silicone oil, fluorine modified silicone oil and the like are preferable.
[0135]
As a method for surface hydrophobization treatment of an external additive using silicone oil, for example, silica fine powder treated with a silane compound and silicone oil may be directly mixed using a mixer such as a Henschel mixer, or a base It is also possible to use a method of spraying silicone oil onto silica. Alternatively, a method may be used in which silicone oil is dissolved or dispersed in an appropriate solvent, and then mixed with the base silica fine powder to remove the solvent.
[0136]
The addition amount of the inorganic fine powder and the hydrophobic inorganic fine powder varies depending on the type and intended function, but is 0.1 to 5 parts by mass (preferably 0.1 to 100 parts by mass of the toner particles). ~ 3 parts by mass).
[0137]
If necessary, an external additive other than the inorganic fine powder such as silica fine powder may be added to the dry toner of the present invention. Such other external additives include, for example, resin fine particles and inorganic fine particles that function as a charging aid, a conductivity imparting agent, a fluidity imparting agent, an anti-caking agent, a lubricant, an abrasive, and the like.
[0138]
More specifically, for example, a lubricant such as a fluorine-based resin, zinc stearate, and polyvinylidene fluoride, among which polyvinylidene fluoride is preferable. Alternatively, abrasives such as cerium oxide, silicon carbide, strontium titanate, etc., among which strontium titanate is preferable. Alternatively, for example, fluidity imparting agents such as titanium oxide and aluminum oxide, particularly hydrophobic ones are preferable. A small amount of an anti-caking agent, or a conductivity imparting agent such as carbon black, zinc oxide, antimony oxide or tin oxide, and white and black fine particles having opposite polarity can also be used in small amounts.
[0139]
The dry toner of the present invention can be produced using a conventional method for producing toner particles used for developing an electrostatic image. As a material for the dry toner of the present invention, at least the binder resin and magnetic iron oxide described above are used, and other materials such as a colorant, a wax, and a charge control agent are used as necessary. More specifically, in the dry toner of the present invention, these materials are sufficiently mixed by a mixer such as a Henschel mixer or a ball mill, and then melted and kneaded using a thermal kneader such as a roll, a kneader and an extruder. In addition, while the resins are mixed with each other by kneading, the pigment or dye is dispersed or dissolved, cooled and solidified, and then pulverized and classified.
[0140]
For production of the dry toner of the present invention, a known apparatus can be used. For example, as a mixer, a Henschel mixer (manufactured by Mitsui Mining Co., Ltd.); a super mixer (manufactured by Kawata Corp.); Ribocorn (manufactured by Okawara Seisakusho Co., Ltd.); Nauter mixer, turbulizer, cyclomix (manufactured by Hosokawa Micron Corporation); spiral pin mixer (manufactured by Taiheiyo Kiko Co., Ltd.);
[0141]
As the kneader, for example, KRC kneader (manufactured by Kurimoto Iron Works); bus co-kneader (manufactured by Buss); TEM type extruder (manufactured by Toshiba Machine); TEX twin-screw kneader (manufactured by Nippon Steel Works) PCM kneading machine (Ikegai Iron Works); Three roll mill, mixing roll mill, kneader (Inoue Seisakusho); Needex (Mitsui Mining); MS pressure kneader, Nider Ruder (Moriyama Seisakusho) ); Banbury mixer (manufactured by Kobe Steel).
[0142]
Examples of the pulverizer include counter jet mill, micron jet, inomizer (manufactured by Hosokawa Micron Co.); IDS type mill, PJM jet pulverizer (manufactured by Nippon Pneumatic Industry Co., Ltd.); cross jet mill (manufactured by Kurimoto Iron Works Co., Ltd.); Examples include Max (manufactured by Nisso Engineering Co., Ltd.); SK Jet O Mill (manufactured by Seishin Enterprise Co., Ltd.); Kryptron (manufactured by Kawasaki Heavy Industries, Ltd.); Turbo Mill (manufactured by Turbo Kogyo Co., Ltd.); Super Rotor (Nisshin Engineering).
[0143]
The classifiers include, for example, a class seal, a micron classifier, a speck classifier (manufactured by Seishin Enterprise Co., Ltd.); a turbo classifier (manufactured by Nisshin Engineering Co., Ltd.); a micron separator, a turboplex (ATP), and a TSP separator (Hosokawa Micron Co., Ltd.) Elbow Jet (manufactured by Nippon Steel Mining Co., Ltd.), dispersion separator (manufactured by Nippon Pneumatic Industrial Co., Ltd.); YM Microcut (manufactured by Yaskawa Shoji Co., Ltd.).
[0144]
Moreover, as a sieving device used for sieving coarse particles, etc., for example, Ultrasonic (manufactured by Sakae Sangyo Co., Ltd.); Resona sieve, gyroshifter (Tokuju Kosakusha Co., Ltd.); Vibrasonic system (Dalton Co., Ltd.); Shinto Kogyo Co., Ltd.); turbo screener (Turbo Kogyo Co., Ltd.); micro shifter (Ogino Sangyo Co., Ltd.);
[0145]
The dry toner of the present invention can be produced by a known method and a known apparatus as described above. However, the relationship between the toner transmittance and the methanol concentration, which is one of the characteristics of the present invention, that is, the wettability is improved. As one of the production methods to be achieved, in the present invention, using a mechanical pulverizer as shown in FIGS. 2, 3 and 4 performs pulverization treatment and surface treatment of the powder raw material, and This is preferable from the viewpoint of improving efficiency.
[0146]
In this pulverizer, the temperature of pulverization is adjusted, the polyester resin is used as the main component of the binder resin, and the magnetic iron oxide having the composition of the present invention is used. You can control the state.
Hereinafter, the mechanical grinder shown in FIGS. 2, 3 and 4 will be described.
[0147]
FIG. 2 is a schematic cross-sectional view of an example of a mechanical pulverizer used in manufacturing the dry toner of the present invention, and FIG. 3 is a schematic cross-sectional view taken along the line DD ′ in FIG. 4 shows a perspective view of the rotor 314 shown in FIG. As shown in FIG. 2, the apparatus is a casing 313, a jacket 316, a distributor 220, a rotating body that is attached to the central rotating shaft 312 in the casing 313, and has a large number of grooves on the surface. A rotor 314, a stator 310 provided with a large number of grooves on the surface and arranged at a constant interval on the outer periphery of the rotor 314, a raw material inlet 311 for introducing a raw material to be processed, a treatment It is comprised from the raw material discharge port 302 for discharging | emitting later powder.
[0148]
Usually, when the pulverized raw material is pulverized by a mechanical pulverizer, the temperature T1 of the spiral chamber 212 and the temperature T2 of the rear chamber 320 of the mechanical pulverizer are controlled, and pulverization is performed below the Tg of the resin. Choose a method that doesn't do quality. However, when the dry toner of the present invention is manufactured, in order to obtain the dry toner having the characteristics of the present invention, the temperature of the raw material discharge port 302 is a temperature that falls within the range of −25 to −5 ° C. with respect to Tg. In an actual pulverized state, the temperature is set to -20 to ± 0 ° C. of Tg, and pulverization is performed so that the resin covers a part of the magnetic iron oxide present on the dry toner surface after pulverization. As a result, the distribution of the raw materials on the surface of the dry toner is likely to have an appropriate value, and such pulverization is preferable in order to impart the hydrophobic characteristics characteristic of the present invention to the dry toner.
[0149]
【Example】
Although the basic configuration and features of the present invention have been described above, the present invention will be specifically described below based on examples. However, the present invention is not limited to the following examples. The number of parts in the examples is part by mass. Table 1 shows binder resins used in the examples, Table 2 shows waxes, and Table 3 shows magnetic iron oxide particles. The polyester resin as the binder resin described in Table 1 was synthesized by a dehydration condensation method. The method for producing magnetic iron oxide particles is as follows.
[0150]
[Table 1]

[0151]
[Table 2]

[0152]
[Table 3]

[0153]
<Production Example 1 of Magnetic Iron Oxide Particles>
After adding sodium silicate so that the silicon element content is 0.48% in the ferrous sulfate aqueous solution, the caustic soda solution is mixed to prepare an aqueous solution containing ferrous hydroxide. did. Air was blown in while adjusting the pH of the aqueous solution to 10, and an oxidation reaction was performed at 80 to 90 ° C. to prepare a slurry liquid for generating seed crystals.
[0154]
When the formation of seed crystals was confirmed, an aqueous ferrous sulfate solution was appropriately added to the slurry liquid, and air was blown in while adjusting the pH of the slurry liquid to 10 to proceed the oxidation reaction. In the meantime, while checking the unreacted ferrous hydroxide concentration and examining the rate of progress of the reaction, zinc sulfate was added as appropriate, and the pH of the aqueous solution was adjusted to 9 at the beginning of the oxidation reaction and to pH at the middle of the reaction. In the latter stage of the reaction, the pH was adjusted stepwise to 6 to control the distribution of metal elements in the magnetic iron oxide and complete the oxidation reaction. The produced magnetic iron oxide particles were washed and filtered and dried by a conventional method. Since the primary particles of the obtained magnetic iron oxide particles are aggregated to form an aggregate, a compressive force and a shear force are applied to the aggregate of the magnetic iron oxide particles using a mix muller to The aggregate was crushed to make the magnetic iron oxide particles primary particles, and the surface of the magnetic iron oxide particles was smoothed to obtain magnetic iron oxide 1 having the characteristics shown in Table 3.
[0155]
<Production Examples 2 to 5 of magnetic iron oxide particles>
Magnetic iron oxide 2 having the physical properties shown in Table 3 in the same manner as in Production Example 1 except that the addition amount of sodium silicate, the addition amount of the salt of the other element α, the addition time, and / or the type were changed. ~ 5 was obtained.
[0156]
<Production Example 6 of Magnetic Iron Oxide Particles>
After adding sodium silicate so that the content of silicon element is 0.40% in the ferrous sulfate aqueous solution, the caustic soda solution is mixed to prepare an aqueous solution containing ferrous hydroxide. did. Air was blown in while adjusting the pH of the aqueous solution to 10, and an oxidation reaction was performed at 80 to 90 ° C. to prepare a slurry liquid for generating seed crystals.
[0157]
When the formation of seed crystals was confirmed, an aqueous ferrous sulfate solution was appropriately added to the slurry liquid, and air was blown in while adjusting the pH of the slurry liquid to 10 to proceed the oxidation reaction. During that time, while examining the unreacted ferrous hydroxide concentration and examining the progress of the reaction, magnesium sulfate was added as appropriate, and the pH of the aqueous solution was adjusted to 8 to complete the oxidation reaction. The produced magnetic iron oxide particles were washed and filtered and dried by a conventional method. Since the primary particles of the obtained magnetic iron oxide particles are aggregated to form an aggregate, a compressive force and a shear force are applied to the aggregate of the magnetic iron oxide particles using a mix muller to The aggregate was crushed to make the magnetic iron oxide particles primary particles, and the surface of the magnetic iron oxide particles was smoothed to obtain magnetic iron oxide 6 having the characteristics shown in Table 3.
[0158]
<Example 1>
・ Binder resin A 100 parts by mass
・ 90 parts by mass of magnetic iron oxide 1
・ 4 parts by weight of wax d
-2 parts by mass of charge control agent A shown in the following structural formula
The above mixture is melt-kneaded with a biaxial extruder heated to 140 ° C., the cooled kneaded product is coarsely pulverized with a hammer mill, and the obtained coarsely pulverized product is finely pulverized by mechanical pulverization with a turbo mill (manufactured by Turbo Kogyo Co., Ltd.). The finely pulverized powder obtained was pulverized and classified with a fixed wall type air classifier to obtain classified powder. Further, the obtained classified powder is classified by a multi-division classifier (Elbow Jet Classifier manufactured by Nittetsu Mining Co., Ltd.) using the Coanda effect, and ultrafine powder and coarse powder are strictly classified and removed at the same time to obtain a weight average particle. Negatively charged toner particles having a diameter (D4) of 6.5 μm were obtained.
[0159]
Embedded image

[0160]
100 wt parts of the obtained toner particles were hydrophobized with 15 wt% hexamethyldisilazane and 15 wt% dimethylsilicone for 80% methanol wettability and 120 m BET specific surface area. ² Toner 1 was prepared by externally mixing 1.3 parts by weight of / g hydrophobic silica fine powder and 1.0 part by weight of strontium titanate. Table 4 shows the toner internal formulation and physical properties, and FIG. 1 shows a graph of the methanol concentration with respect to the transmittance of light having a wavelength of 780 nm.
[0161]
This toner 1 was modified from a commercially available LBP printer (LeserJet 4100, manufactured by HP) to a printing speed of 1.5 times, and this was used as an imaging tester in an environment of 15 ° C., 10% RH, 23 ° C., A print test of 10,000 sheets was performed in an environment of 60% RH and an environment of 30 ° C. and 80% RH. At this time, regarding the image density uniformity within the page, the image density uniformity within the page was judged based on the difference between the highest value and the lowest value of the image density in the printout image under the high temperature and high humidity environment. .
[0162]
The image density was measured by measuring the reflection density of a 5 mm square image using an SPI filter with a Macbeth densitometer (Macbeth). The fog is measured using a reflection densitometer (reflectometer model TC-6DS manufactured by Tokyo Denshoku Co., Ltd.), the transfer material before and after the image formation is measured, the worst value of the white background reflection density after the image formation is Ds, and the transfer before the image formation. The reflection average density of the material was taken as Dr, Ds-Dr was determined, and this was evaluated as the fogging amount. A smaller value indicates that fog is suppressed. These evaluations were performed at the initial stage of 10,000 sheets and at each time after being left outside the machine for a day.
[0163]
Regarding the evaluation of the rise of the charge amount, a horizontal line pattern in which four horizontal lines are printed every 176 dot spaces in the environment of 15 ° C. and 10% RH using the above-described imaging tester is one sheet per 10 seconds. An intermittent print test was performed in which images were printed at intervals of 5 mm square, and 5 mm square images were sampled at the 1st, 3rd, 7th, 15th, 50th, and 100th sheets, and the image density was measured. It can be said that the higher the image density from the earlier the number of images printed, the faster the charge amount rises.
[0164]
For the evaluation of image quality, using the above-described imaging tester, an isolated 1-dot pattern of 1200 dpi was drawn in a normal temperature and humidity environment (23 ° C., 60% RH), and the image was observed with an optical microscope. The dot reproducibility was evaluated according to the following criteria.
A: There is no protrusion of toner from the latent image, and the dots are completely reproduced.
B: There is a slight protrusion of toner from the latent image.
C: There is much protrusion of toner from the latent image
[0165]
For tailing, use the above-mentioned image-drawing tester to draw a pattern in which 4-dot horizontal lines are printed in a 20-dot space, count the number of tails on the line, and evaluate according to the following criteria: did.
A: No occurrence
B: Less than 3
C: Less than 3-7
D: Less than 7-15
E: 15 or more
[0166]
For image scattering, an intermittent print test is performed in which the horizontal line pattern in which 4-dot horizontal lines are printed at intervals of 176 dot spaces is imaged at intervals of one sheet every 10 seconds, using the above-described image output tester. The 10,000th image scattering was evaluated according to the following criteria.
A: Image with little image scattering even by magnified observation
B: Scattering is observed by magnified observation, but is not visible
C: Characters blur slightly due to scattering
D: Unevenness in line thickness due to scattering
E: Some parts of small characters are crushed due to scattering
[0167]
Further, the obtained toner is left in an environment of a temperature of 40 ° C. and a humidity of 90% RH for 30 days, and then in a normal environment (temperature of 23 ° C. and humidity of 60% RH) using the above-described image tester. The image drawing test was performed. Table 6 shows the evaluation of the image density and fog of the 500th sheet.
[0168]
<Examples 2 to 7, Comparative Example 1>
Toners 2 to 8 were prepared in the same manner as in Example 1 with the formulation described in Table 4. The structural formulas of charge control agent B and charge control agent C in the table are shown below. Further, the same test as in Example 1 was performed using these toners. The results are shown in Tables 5, 6, 7, 8, and 9.
[0169]
Embedded image

[0170]
Embedded image

[0171]
<Comparative example 2>
A toner 9 was prepared in the same manner as in Example 1 except that the toner particles obtained after classification were subjected to a treatment for instantaneously passing through 300 ° C. hot air. Using this toner 9, the same test as in Example 1 was performed. The results are shown in Tables 5, 6, 7, 8, and 9.
[0172]
<Comparative Example 3>
In the pulverization step, a toner 10 was produced in the same manner as in Example 1 except that a fine pulverizer by collision type airflow pulverization was used. Using this toner 10, the same test as in Example 1 was performed. The results are shown in Tables 5, 6, 7, 8, and 9.
[0173]
[Table 4]

[0174]
[Table 5]

[0175]
[Table 6]

[0176]
[Table 7]

[0177]
[Table 8]

[0178]
[Table 9]

[0179]
【The invention's effect】
According to the present invention, in a toner having at least a binder resin and magnetic iron oxide, the binder resin contains a polyester resin as a main component, and the magnetic iron oxide includes Si, Mg, Cu, Zn, Ti, and The element α, which is at least one element selected from Al, and the Si content in the magnetic iron oxide is 0.1 to 2.0% by mass based on the magnetic iron oxide, and the element in the magnetic iron oxide The α content is 0.1 to 4.0% by mass based on the magnetic iron oxide, and the atomic concentration of the element α on the outermost surface of the magnetic iron oxide measured by X-ray photoelectron spectroscopy is 1.00. 7.00%, and when the wettability of the toner with respect to the mixed solvent of methanol and water is measured by the transmittance of light having a wavelength of 780 nm, the methanol concentration when the transmittance is 80% is in the range of 45 to 65% by volume. At the inner, In addition, since the methanol concentration when the transmittance is 10% is in the range of 45 to 65% by volume, high developability in long-term use even in high-speed development under severe environments such as high temperature and high humidity and low temperature and low humidity. Thus, it is possible to obtain a toner having a fast charge amount rising, high image quality, and good developability and environmental stability.
[0180]
In the present invention, when the wettability of the toner with respect to the mixed solvent of methanol and water is measured by the transmittance of light having a wavelength of 780 nm, the methanol concentration when the transmittance is 80% is within the range of 50 to 65% by volume. Also, if the methanol concentration when the transmittance is 10% is in the range of 50 to 65% by volume, the charge amount of the dry toner is appropriately maintained, fogging is prevented, and a good image with high image density is obtained. It is even more effective in forming.
[0181]
In the present invention, when at least one endothermic peak is present in the DSC curve at the time of temperature rise of the toner measured by a differential scanning calorimeter, and the endothermic peak is present at 60 ° C. to 120 ° C., the magnetic iron oxide in the toner particles Is more effective in stably dispersing the toner and stabilizing the chargeability of the dry toner.
[0182]
In the present invention, when the acid value of the polyester resin is 10 to 50 mgKOH / g, the chargeability of the dry toner is stabilized and more effective in forming a stable and good image regardless of environmental changes. is there.
[0183]
In the present invention, when the Si content in the magnetic iron oxide is 0.3 to 1.8% by mass based on the magnetic iron oxide, it is more effective for charging the dry toner appropriately and quickly. is there.
[0184]
In the present invention, when the content of the element α in the magnetic iron oxide is 0.1 to 2.0% by mass based on the magnetic iron oxide, the dry toner is sufficiently charged regardless of the environmental change, and high image quality is achieved. And more effective in forming a good image with a high image density.
[0185]
Further, in the present invention, when the element α is an element selected from Mg, Al, and Zn, the dry toner is sufficiently charged regardless of environmental changes, and a good image with high image quality and high image density is formed. Even more effective.
[0186]
In the present invention, the atomic concentration of Si atoms on the outermost surface of magnetic iron oxide measured by X-ray photoelectron spectroscopy is 12.5 to 17.5%, and the atomic concentration of Fe atoms is 70.00 to 85. If it is 00%, it balances the electrical conductivity and electrical resistance of magnetic iron oxide, and controls the charge amount of the dry toner. As a result, high image density and high image quality developability are obtained regardless of the environment. More effective.
[0187]
Moreover, in this invention, in the atomic concentration of the outermost surface of magnetic iron oxide measured by X-ray photoelectron spectroscopy, the ratio of element α to Si atoms is 0.05 to 0.5, and the ratio of Fe atoms to Si atoms Is 3.00 to 7.00 and the ratio of Fe atom to element α is 10.0 to 70.0, the balance between the electrical conductivity and the electrical resistance of the magnetic iron oxide, and the charge amount of the dry toner As a result, it is more effective in obtaining high image density and high image quality developability regardless of the environment.
[0188]
In addition, in the present invention, when magnetic iron oxide is contained in an amount of 30 to 150 parts by mass with respect to 100 parts by mass of the binder resin, both good chargeability and developability can be achieved and a good image can be formed. More effective.
[Brief description of the drawings]
FIG. 1 is a graph showing the transmittance of light at 780 nm with respect to methanol concentration for toner 1 in Example 1 of the present invention.
FIG. 2 is a schematic cross-sectional view of a mechanical pulverizer that can be used in producing the dry toner of the present invention.
FIG. 3 is a schematic cross-sectional view showing the mechanical pulverizer shown in FIG. 2 cut along the line DD ′.
4 is a perspective view of the rotor shown in FIG. 2. FIG.
[Explanation of symbols]
212 Swirl chamber
219 pipe
220 Distributor
222 Bug Filter
224 Suction blower
229 Collection Cyclone
301 mechanical crusher
310 Stator
311 Raw material inlet
312 Center rotation axis
313 casing
314 Rotor
315 Metering machine
316 jacket
320 back room

Claims (7)

In a toner having at least a binder resin and magnetic iron oxide,
The binder resin contains a polyester resin as a main component,
The magnetic iron oxide contains Si and Mg or Zn ,
The content of Si in the magnetic iron oxide is 0.1 to 2.0% by mass based on the magnetic iron oxide,
The content of Mg or Zn in the magnetic iron oxide is 0.1 to 4.0% by mass based on the magnetic iron oxide,
The atomic concentration of Mg or Zn on the outermost surface of the magnetic iron oxide measured by X-ray photoelectron spectroscopy is 1.00 to 7.00%,
When the wettability of the toner with respect to the mixed solvent of methanol and water is measured by the transmittance of light having a wavelength of 780 nm, the methanol concentration when the transmittance is 80% is within the range of 45 to 65% by volume. There Ri range der methanol concentration of 45 to 65 vol% when the 10%
A dry magnetic toner comprising 30 to 150 parts by mass of the magnetic iron oxide with respect to 100 parts by mass of a binder resin . When the wettability of the toner with respect to the mixed solvent of methanol and water is measured by the transmittance of light having a wavelength of 780 nm, the methanol concentration when the transmittance is 80% is in the range of 50 to 65% by volume. 2. The dry magnetic toner according to claim 1, wherein the methanol concentration is 10 to 50% by volume within a range of 50 to 65% by volume. The dry magnetic toner according to claim 1, wherein the polyester resin has an acid value of 10 to 50 mg KOH / g . The dry magnetic toner according to claim 1, wherein a content of Si in the magnetic iron oxide is 0.3 to 1.8% by mass based on the magnetic iron oxide . The content of Mg or Zn in the magnetic iron oxide is 0.1 to 2.0% by mass based on the magnetic iron oxide, according to any one of claims 1 to 4. Dry magnetic toner . The atomic concentration of Si atoms on the outermost surface of the magnetic iron oxide measured by X-ray photoelectron spectroscopy is 12.5 to 17.5%, and the atomic concentration of Fe atoms is 70.00 to 85.00%. The dry magnetic toner according to claim 1, wherein the toner is dry magnetic toner . In the atomic concentration of the outermost surface of the magnetic iron oxide measured by X-ray photoelectron spectroscopy, the ratio of Mg or Zn to Si atoms is 0.05 to 0.5, and the ratio of Fe atoms to Si atoms is The dry magnetism according to any one of claims 1 to 5, wherein the dry magnetism is 3.00 to 7.00, and the ratio of Fe atoms to Mg or Zn is 10.0 to 70.0. Toner .

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