JP2004053863A - Magnetic toner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a toner excellent in charge stability, durability stability, and high developability, and having high blackness. <P>SOLUTION: In the magnetic toner including toner particles at least including a binder resin and a magnetic body and an inorganic fine particles existing on the surfaces of the toner particles, the binder resin at least includes a polyester resin having a polyester monomer unit and a vinyl resin having a vinyl monomer unit. The content ratio of the polyester monomer unit to the vinyl monomer unit in terms of the mass ratio is 50/50 to 90/10. The weight average particle diameter (D4) of the magnetic toner is 5-12 μm. In the magnetic body, (1) the magnetic body is iron oxide particles having the average particle diameter of 0.1-0.3 μm, (2) titanium element included in the iron oxide particles is 0.3-1.5 mass% of the total amount of the iron oxide particle, and (3) the formula 0.7≤A/B≤1 is satisfied, with respect to the ratio (A/B), where the ratio (A%) is the ratio of FeO to the total amount of Fe that is within 10 mass% from the surface of the iron oxide, and the ratio (B%) is the ratio of FeO to the total amount of Fe that is in the rest 90 mass%. <P>COPYRIGHT: (C)2004,JPO

Description

【００６７】
【化２】

【００６８】
酸成分としては、フタル酸、テレフタル酸、イソフタル酸、無水フタル酸などのベンゼンジカルボン酸類又はその無水物；こはく酸、アジピン酸、セバシン酸、アゼライン酸などのアルキルジカルボン酸類又はその無水物、またさらに炭素数６〜１８のアルキル基又はアルケニル基で置換されたこはく酸もしくはその無水物；フマル酸、マレイン酸、シトラコン酸、イタコン酸などの不飽和ジカルボン酸又はその無水物等が挙げられる。
【００６９】
また本発明で用いられるポリエステル樹脂は、３価以上の多価カルボン酸またはその無水物及び／または３価以上の多価アルコールを含むポリエステル樹脂であると、さらに分子量や粘度をコントロールしやすく好ましい。３価以上の多価カルボン酸またはその無水物としては、例えば、１，２，４−ベンゼントリカルボン酸、１，２，４−シクロヘキサントリカルボン酸、１，２，４−ナフタレントリカルボン酸、ピロメリット酸及びこれらの酸無水物または低級アルキルエステルなどが挙げられ、３価以上の多価アルコールとしては、例えば、１，２，３−プロパントリオール、トリメチロールプロパン、ヘキサントリオール、ペンタエリスリトールなどが挙げられる。本発明の結着樹脂においては、環境変動による安定性も高い芳香族系アルコールが特に好ましく、例えば１，２，４−ベンゼントリカルボン酸及びその無水物等が挙げられる。
【００７０】
ビニル系樹脂を生成する為のビニル系モノマーとしては、次のようなものが挙げられる。
【００７１】
スチレン；ｏ−メチルスチレン、ｍ−メチルスチレン、ｐ−メチルスチレン、ｐ−メトキシスチレン、ｐ−フェニルスチレン、ｐ−クロルスチレン、３，４−ジクロルスチレン、ｐ−エチルスチレン、２，４−ジメチルスチレン、ｐ−ｎ−ブチルスチレン、ｐ−ｔｅｒｔブチルスチレン、ｐ−ｎ−ヘキシルスチレン、ｐ−ｎ−オクチルスチレン、ｐ−ｎ−ノニルスチレン、ｐ−ｎ−デシルスチレン、ｐ−ｎ−ドデシルスチレンなどのスチレン及びその誘導体；エチレン、プロピレン、ブチレン、イソブチレンなどのスチレン不飽和モノオレフィン類；ブタジエン、イソプレンなどの不飽和ポリエン類；塩化ビニル、塩化ビニリデン、臭化ビニル、沸化ビニルなどのハロゲン化ビニル類；酢酸ビニル、プロピオン酸ビニル、ベンゾエ酸ビニルなどのビニルエステル類；メタクリル酸メチル、メタクリル酸エチル、メタクリル酸プロピル、メタクリル酸ｎ−ブチル、メタクリル酸イソブチル、メタクリル酸ｎ−オクチル、メタクリル酸ドデシル、メタクリル酸２−エチルヘキシル、メタクリル酸ステアリル、メタクリル酸フェニル、メタクリル酸ジメチルアミノエチル、メタクリル酸ジエチルアミノエチルなどのα−メチレン脂肪族モノカルボン酸エステル類；アクリル酸メチル、アクリル酸エチル、アクリル酸ｎブチル、アクリル酸イソブチル、アクリル酸プロピル、アクリル酸ｎ−オクチル、アクリル酸ドデシル、アクリル酸２−エチルヘキシル、アクリル酸ステアリル、アクリル酸２−クロルエチル、アクリル酸フェニルなどのアクリル酸エステル類；ビニルメチルエーテル、ビニルエチルエーテル、ビニルイソブチルエーテルなどのビニルエーテル類；ビニルメチルケトン、ビニルヘキシルケトン、メチルイソプロペニルケトンなどのビニルケトン類；Ｎ−ビニルピロール、Ｎ−ビニルカルバゾール、Ｎ−ビニルインドール、Ｎ−ビニルピロリドンなどのＮ−ビニル化合物；ビニルナフタリン類；アクリロニトリル、メタクリロニトリル、アクリルアミドなどのアクリル酸もしくはメタクリル酸誘導体が挙げられる。
【００７２】
また、マレイン酸、シトラコン酸、イタコン酸、アルケニルコハク酸、フマル酸、メサコン酸などの不飽和二塩基酸；マレイン酸無水物、シトラコン酸無水物、イタコン酸無水物、アルケニルコハク酸無水物などの不飽和二塩基酸無水物；マレイン酸メチルハーフエステル、マレイン酸エチルハーフエステル、マレイン酸ブチルハーフエステル、シトラコン酸メチルハーフエステル、シトラコン酸エチルハーフエステル、シトラコン酸ブチルハーフエステル、イタコン酸メチルハーフエステル、アルケニルコハク酸メチルハーフエステル、フマル酸メチルハーフエステル、メサコン酸メチルハーフエステルなどの不飽和二塩基酸のハーフエステル；ジメチルマレイン酸、ジメチルフマル酸などの不飽和二塩基酸エステル；アクリル酸、メタクリル酸、クロトン酸、ケイヒ酸などのα，β−不飽和酸；クロトン酸無水物、ケイヒ酸無水物などのα，β−不飽和酸無水物、該α，β−不飽和酸と低級脂肪酸との無水物；アルケニルマロン酸、アルケニルグルタル酸、アルケニルアジピン酸、これらの酸無水物及びこれらのモノエステルなどのカルボキシル基を有するモノマーが挙げられる。
【００７３】
さらに、２−ヒドロキシエチルアクリレート、２−ヒドロキシエチルメタクリレート、２−ヒドロキシプロピルメタクリレートなどのアクリル酸またはメタクリル酸エステル類；４−（１−ヒドロキシ−１−メチルブチル）スチレン、４−（１−ヒドロキシ−１−メチルヘキシル）スチレンなどのヒドロキシ基を有するモノマーが挙げられる。上記各モノマーを単独で、または２種以上を組み合わせて用いることができる。
【００７４】
本発明の磁性トナーにおいて、結着樹脂に含有されるビニル系樹脂は、ビニル基を２個以上有する架橋剤で架橋された架橋構造を有してもよいが、この場合に用いられる、２個のビニル基を有する架橋剤は、芳香族ジビニル化合物として例えば、ジビニルベンゼン、ジビニルナフタレンが挙げられ；アルキル鎖で結ばれたジアクリレート化合物類として例えば、エチレングリコールジアクリレート、１，３−ブチレングリコールジアクリレート、１，４−ブタンジオールジアクリレート、１，５−ペンタンジオールアクリレート、１，６−へキサンジオールジアクリレート、ネオペンチルグリコールジアクリレート、及び以上の化合物のアクリレートをメタアクリレートに代えたものが挙げられ；エーテル結合を含むアルキル鎖で結ばれたジアクリレート化合物類としては、例えば、ジエチレングリコールジアクリレート、トリエチレングリコールジアクリレート、テトラエチレングリコールジアクリレート、ポリエチレングリコール＃４００ジアクリレート、ポリエチレングリコール＃６００ジアクリレート、ジプロピレングリコールジアクリレート、及び以上の化合物のアクリレー卜をメタアクリレートに代えたものが挙げられ；芳香族基及びエーテル結合を含む鎖で緒ばれたジアクリレート化合物類として例えば、ポリオキシエチレン（２）−２，２−ビス（４−ヒドロキシフェニル）プロパンジアクリレート、ポリオキシエチレン（４）−２，２−ビス（４−ヒドロキシフェニル）プロパンジアクリレート、及び以上の化合物のアクリレートをメタアクリレートに代えたものが挙げられ；ポリエステル型ジアクリレート化合物類として例えば、商品名ＭＡＮＤＡ（日本化薬）が挙げられる。
【００７５】
多官能の架橋剤としては、ペンタエリスリトールトリアクリレート、トリメチロールエタントリアクリレート、トリメチロールプロパントリアクリレート、テトラメチロールメタンテトラアクリレート、オリゴエステルアクリレート、及び以上の化合物のアクリレートをメタアクリレートに代えたもの；トリアリルシアヌレート、トリアリルトリメリテート；が挙げられる。
【００７６】
これらの架橋剤は、他のビニル系モノマー１００質量部に対して、０．０１〜１０質量部（更に好ましくは０．０３〜５質量部）用いることができる。
【００７７】
これらの架橋性モノマーのうち、定着性、耐オフセット性の点から結着樹脂に好適に用いられるものとして、芳香族ジビニル化合物（特にジビニルベンゼン）、芳香族基及びエーテル結合を含む鎖で結ばれたジアクリレート化合物類が挙げられる。
【００７８】
本発明におけるビニル系樹脂を製造する場合に用いられる重合開始剤としては、例えば、２，２’−アゾビスイソブチロニトリル、２，２’−アゾビス（４−メトキシ−２，４−ジメチルバレロニトリル）、２，２’−アゾビス（−２，４−ジメチルバレロニトリル）、２，２’−アゾビス（−２メチルブチロニトリル）、ジメチル−２，２’−アゾビスイソブチレート、１，１’−アゾビス（１−シクロヘキサンカルボニトリル）、２−（カーバモイルアゾ）−イソブチロニトリル、２，２’−アゾビス（２，４，４−トリメチルペンタン）、２−フェニルアゾ−２，４−ジメチル−４−メトキシバレロニトリル、２，２−アゾビス（２−メチルプロパン）、メチルエチルケトンパーオキサイド、アセチルアセトンパーオキサイド、シクロヘキサノンパーオキサイドなどのケトンパーオキサイド類、２，２−ビス（ｔ−ブチルパーオキシ）ブタン、ｔ−ブチルハイドロパーオキサイド、クメンハイドロパーオキサイド、１，１，３，３−テトラメチルブチルハイドロパーオキサイド、ジ−ｔ−ブチルパーオキサイド、ｔ−ブチルクミルパーオキサイド、ジクミルパーオキサイド、α，α’−ビス（ｔ−ブチルパーオキシイソプロピル）ベンゼン、イソブチルパーオキサイド、オクタノイルパーオキサイド、デカノイルパーオキサイド、ラウロイルパーオキサイド、３，５，５−トリメチルヘキサノイルパーオキサイド、ベンゾイルパーオキサイド、ｍ−トリオイルパーオキサイド、ジ−イソプロピルパーオキシジカーボネート、ジ−２−エチルヘキシルパーオキシジカーボネート、ジ−ｎ−プロピルパーオキシジカーボネート、ジ−２−エトキシエチルパーオキシカーボネート、ジメトキシイソプロピルパーオキシジカーボネート、ジ（３−メチル−３−メトキシブチル）パーオキシカーボネート、アセチルシクロヘキシルスルホニルパーオキサイド、ｔ−ブチルパーオキシアセテート、ｔ−ブチルパーオキシイソプチレート、ｔ−ブチルパーオキシネオデカノエイト、ｔ−ブチルパーオキシ−２−エチルヘキサノエイト、ｔ−ブチルパーオキシラウレート、ｔ−ブチルパーオキソベンゾエイト、ｔ−ブチルパーオキシイソプロピルカーボネート、ジ−ｔ−ブチルパーオキシイソフタレート、ｔ−ブチルパーオキシアリルカーボネート、ｔ−アミルパーオキシ−２−エチルヘキサノエート、ジ−ｔ−プチルパーオキシヘキサハイドロテレフタレート，ジ−ｔ−ブチルパーオキシアゼレートが挙げられる。
【００７９】
本発明ではビニル系樹脂及び／又はポリエステル樹脂を構成する成分中に、両樹脂成分と反応し得るモノマー成分を含むことが好ましい。ポリエステル樹脂を構成するモノマーのうちビニル系樹脂と反応し得るものとしては、例えば、フタル酸、マレイン酸、シトラコン酸、イタコン酸などの不飽和ジカルボン酸又はその無水物などが挙げられる。ビニル系樹脂を構成するモノマーのうちポリエステル樹脂成分と反応し得るものとしては、カルボキシル基又はヒドロキシ基を有するものや、アクリル酸またはメタクリル酸エステル類が挙げられる。
【００８０】
ビニル系樹脂とポリエステル樹脂とが一部反応してなるハイブリッド樹脂を得る方法としては、先に挙げたビニル系樹脂及びポリエステル樹脂のそれぞれと反応しうるモノマー成分を含むポリマーが存在しているところで、どちらか一方もしくは両方の樹脂の重合反応をさせることにより得る方法が好ましい。
【００８１】
このハイブリッド樹脂においては、ポリエステル系モノマーユニットとビニル系モノマーユニットとの共重合比が質量比で５０／５０〜９０／１０であることが好ましく、６０／４０〜８５／１５であることがより好ましい。ポリエステル系モノマーユニットが５０％未満の場合は低温定着性が損なわれるだけでなく、９０％を超える場合は耐高温オフセット性が悪化したり、粉砕性に悪影響を及ぼす場合がある。また、ポリエステル系モノマーユニットが５０％未満となっても９０％を超えても、前述の理由で酸化鉄粒子の結着樹脂中における良好な分散性を達成することが難しくなる。
【００８２】
また、上記のような結着樹脂を単独で使用しても良いが、軟化点の異なる２種以上の結着樹脂を混合して使用しても良い。このような系では、磁性トナーの分子量分布の設計を比較的容易に行うことができ、幅広い定着領域を持たせることができるので好ましい。
【００８３】
結着樹脂の「軟化点」は、「ＪＩＳ　Ｋ　７２１０」に示される測定方法に則り、降下式フローテスターにより測定されるものを指す。具体的な測定方法を以下に示す。
【００８４】
降下式フローテスター（島津製作所製）を用い、１ｃｍ^３の試料樹脂を昇温速度６℃／ｍｉｎで加熱しながら、プランジャーにより１９６０Ｎ／ｍ^２（２０ｋｇ／ｃｍ^２）の荷重を与えて、試料樹脂を直径１ｍｍ、長さ１ｍｍのノズルから押し出すようにする。これにより、プランジャー降下量（流れ値）−温度曲線を描き、そのＳ字曲線の高さをｈとするとき、ｈ／２に対応する温度（試料樹脂の半分が流出した温度）を軟化点とする。
【００８５】
［本発明の磁性トナー］
以下、上述したような磁性体および結着樹脂を含有する本発明の磁性トナーについて説明する。本発明の磁性トナーは、上記結着樹脂と上記磁性体とを少なくとも含有するトナー粒子と、このトナー粒子表面に存在する無機微粉体とを有するものである。
【００８６】
本発明の磁性トナーを構成するトナー粒子は、その帯電性をさらに安定化させる為に、上述した結着樹脂と磁性体との他に、必要に応じて１種又は２種以上の荷電制御剤を組み合わせて含有してもよい。荷電制御剤は、結着樹脂１００質量部当たり０．１〜１０質量部を使用することが好ましく、０．１〜５質量部使用することがより好ましい。
【００８７】
荷電制御剤としては、従来よりトナーに含有される公知のものを用いることができ、特に限定されないが、例えば以下のものが挙げられる。
【００８８】
磁性トナーを負荷電性に制御する負荷電性制御剤として、例えば有機金属錯体又はキレート化合物が有効である。例えば、モノアゾ金属錯体、芳香族ヒドロキシカルボン酸の金属錯体、芳香族ジカルボン酸系の金属錯体が挙げられる。他には、芳香族ハイドロキシカルボン酸、芳香族モノ及びポリカルボン酸及びその金属塩、その無水物、又はそのエステル類、又はビスフェノールのフェノール誘導体類が挙げられる。
【００８９】
トナーを正荷電性に制御する正荷電性制御剤としては、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４級アンモニウム塩、及びこれらの類似体であるホスホニウム塩等のオニウム塩及びこれらのキレート顔料として、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、燐タングステン酸、燐モリブデン酸、燐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、フェリシアン酸、フェロシアン化合物等）、高級脂肪酸の金属塩として、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シド等のジオルガノスズオキサイドや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が挙げられる。
【００９０】
また、本発明で用いられるトナー粒子はワックスをさらに含有してもよい。ワックスは従来よりトナーに含有される公知のものを用いることができ、特に限定されないが、磁性トナー中での分散のしやすさ、離型性の高さから、低分子量ポリエチレン、低分子量ポリプロピレン、マイクロクリスタリンワックス、パラフィンワックスなどの炭化水素系ワックスが好ましく用いられる。また、必要に応じて以下に例示するようなワックスのうち一種又は二種以上を少量併用してもかまわない。
【００９１】
酸化ポリエチレンワックスなどの脂肪族炭化水素系ワックスの酸化物、またはそれらのブロック共重合物；カルナバワックス、サゾールワックス、モンタン酸エステルワックスなどの脂肪酸エステルを主成分とするワックス類；及び脱酸カルナバワックスなどの脂肪酸エステル類を一部または全部を脱酸化したものなどが挙げられる。
【００９２】
さらに、パルミチン酸、ステアリン酸、モンタン酸などの飽和直鎖脂肪酸類；プラシジン酸、エレオステアリン酸、バリナリン酸などの不飽和脂肪酸類；ステアリルアルコール、アラルキルアルコール、ベヘニルアルコール、カルナウビルアルコール、セリルアルコール、メリシルアルコールなどの飽和アルコール類；長鎖アルキルアルコール類；ソルビトールなどの多価アルコール類；リノール酸アミド、オレイン酸アミド、ラウリン酸アミドなどの脂肪酸アミド類；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などの飽和脂肪酸ビスアミド類；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などの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などの芳香族系ビスアミド類；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などの脂肪酸金属塩（一般に金属石けんといわれているもの）、また、脂肪族炭化水素系ワックスにスチレンやアクリル酸などのビニル系モノマーを用いてグラフト化させたワックス類；また、ベヘニン酸モノグリセリドなどの脂肪酸と多価アルコールの部分エステル化物、また、植物性油脂の水素添加など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などが挙げられる。
【００９３】
また、上記ワックスの示差走査型熱量計（ＤＳＣ）で測定される昇温時の最大吸熱ピーク温度で規定される融点は、７０〜１４０℃であることが好ましい。より好ましくは９０〜１３５℃である。ワックスの融点が７０℃以下の場合はトナーの粘度が低下して感光体へのトナー付着が発生しやすくなり、融点が１４０℃以上の場合は、低温定着性が悪化してしまう。
【００９４】
ワックスの「融点」は、示差走査熱量計（ＤＳＣ測定装置），ＤＳＣ−７（パーキンエルマー社製）を用いてＡＳＴＭ　Ｄ３４１８−８２に準じて測定することによって求められる。
【００９５】
測定に際し、測定試料は５〜２０ｍｇ、好ましくは１０ｍｇを精密に秤量する。これをアルミパン中に入れ、リファレンスとして空のアルミパンを用い、測定温度範囲３０〜２００℃の間で、昇温速度１０℃／ｍｉｎで常温常湿下で測定を行う。２回目の昇温過程で、温度４０〜１００℃の範囲において最大吸熱ピークが得られるので、その最大吸熱ピークの温度をワックスの融点として用いる。
【００９６】
ワックスの量は、結着樹脂１００質量部当たり０．１〜２０質量部、好ましくは０．５〜１０質量部が好ましく用いられる。
【００９７】
なお、これらのワックスは、結着樹脂の製造時に樹脂を溶剤に溶解し、樹脂溶液温度を上げ、撹拌しながら添加混合する方法や、磁性トナー製造中の溶融混練時に添加する方法などにより結着樹脂に混合させることができる。
【００９８】
また、本発明の磁性トナーにおいては、流動性を向上させるために無機微粉体がトナー粒子に外添されて、トナー粒子表面に存在する。本発明に用いられる無機微粉体としては、例えばフッ化ビニリデン微粉末、ポリテトラフルオロエチレン微粉体などのフッ素系樹脂粉体；湿式製法シリカ、乾式製法シリカなどの微粉末シリカ；微粉末酸化チタン；微粉末アルミナ；シランカップリング剤、チタンカップリング剤、シリコーンオイル等により表面処理を施した処理シリカ、処理酸化チタン、処理アルミナ等が挙げられる。
【００９９】
好ましい無機微粉体としては、ケイ素ハロゲン化合物の蒸気相酸化により生成された微粉体であり、乾式法シリカ又はヒュームドシリカと称されるものである。例えば、四塩化ケイ素ガスの酸素、水素中における熱分解酸化反応を利用するもので、基礎となる反応式は次の様なものである。
【０１００】
【化３】
ＳｉＣｌ_４＋２Ｈ_２＋Ｏ_２　→　ＳｉＯ_２＋４ＨＣｌ
この製造工程において、例えば塩化アルミニウム又は塩化チタンなどの他の金属ハロゲン化合物をケイ素ハロゲン化合物と共に用いることによってシリカと他の金属酸化物の複合微粉体を得ることも可能であり、それらも包含する。その粒径は、平均の一次粒径として、０．００１〜２μｍの範囲内であることが好ましく、特に好ましくは、０．００２〜０．２μｍの範囲内のシリカ微粉体を使用するのが良い。
【０１０１】
ケイ素ハロゲン化合物の蒸気相酸化により生成された市販のシリカ微粉体としては、例えば以下の様な商品名で市販されているものがある。
【０１０２】

さらには、該ケイ素ハロゲン化合物の気相酸化により生成されたシリカ微粉体を疎水化処理した処理シリカ微粉体を用いることがより好ましい。該処理シリカ微粉体において、メタノール滴定試験によって測定された疎水化度が３０〜８０の範囲の値を示すようにシリカ微粉体を処理したものが特に好ましい。
【０１０３】
疎水化方法としては、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及び／又はシリコーンオイルで化学的に処理することによって付与される。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シリカ微粉体を有機ケイ素化合物で処理する。
【０１０４】
有機ケイ素化合物としては、ヘキサメチルジシラザン、トリメチルシラン、トリメチルクロルシラン、トリメチルエトキシシラン、ジメチルジクロルシラン、メチルトリクロルシラン、アリルジメチルクロルシラン、アリルフェニルジクロルシラン、ベンジルジメチルクロルシラン、ブロムメチルジメチルクロルシラン、α−クロルエチルトリクロルシラン、β−クロルエチルトリクロルシラン、クロルメチルジメチルクロルシラン、トリオルガノシリルメルカプタン、トリメチルシリルメルカプタン、トリオルガノシリルアクリレート、ビニル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および１分子当たり２から１２個のシロキサン単位を有し末端に位置する単位にそれぞれ１個宛のＳｉに結合した水酸基を含有するジメチルポリシロキサン等が挙げられる。これらは１種あるいは２種以上の混合物で用いられる。
【０１０５】
窒素原子を有するアミノプロピルトリメトキシシラン、アミノプロピルトリエトキシシラン、ジメチルアミノプロピルトリメトキシシラン、ジエチルアミノプロピルトリメトキシシラン、ジプロピルアミノプロピルトリメトキシシラン、ジブチルアミノプロピルトリメトキシシラン、モノブチルアミノプロピルトリメトキシシラン、ジオクチルアミノプロピルジメトキシシラン、ジブチルアミノプロピルジメトキシシラン、ジブチルアミノプロピルモノメトキシシラン、ジメチルアミノフェニルトリエトキシシラン、トリメトキシシリル−γ−プロピルフェニルアミン、トリメトキシシリル−γ−プロピルベンジルアミンなどのシランカップリング剤も単独あるいは併用して使用される。好ましいシランカップリング剤としては、へキサメチルジシラザン（ＨＭＤＳ）が挙げられる。
【０１０６】
本発明で用いる好ましいシリコーンオイルとしては、２５℃における粘度が０．５〜１００００センチストークス、好ましくは１〜１０００センチストークス、さらに好ましくは１０〜２００センチストークスのものが用いられ、例えばジメチルシリコーンオイル、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が特に好ましい。シリコーンオイル処理の方法としては、例えばシランカップリング剤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などの混合機を用いて直接混合する方法；ベースとなるシリカ微粉体にシリコーンオイルを噴霧する方法；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させた後、シリカ微粉体を加え混合し溶剤を除去する方法；を用いることが可能である。
【０１０７】
シリコーンオイルで処理されたシリカは、シリコーンオイルによる処理後にシリカを不活性ガス中で２００℃以上（より好ましくは２５０℃以上）に加熱し表面のコートを安定化させることがより好ましい。
【０１０８】
本発明においては、シリカを予めカップリング剤で処理した後にシリコーンオイルで処理する方法、または、シリカをカップリング剤とシリコーンオイルで同時に処理する方法によって処理されたものが好ましい。
【０１０９】
本発明で用いられる無機微粉体は、ＢＥＴ法で測定した窒素吸着による比表面積が３０ｍ^２／ｇ以上、好ましくは５０ｍ^２／ｇ以上のものが良好な結果を与える。トナー粒子１００質量部に対して、流動性向上のための無機微粉体を０．０１〜８質量部、好ましくは０．１〜４質量部使用するのが良い。
【０１１０】
本発明の磁性トナーにおいては、研磨効果、帯電性付与性及び流動性付与を目的として、またクリーニング助剤として、上述（流動性向上のための無機微粉体）以外の無機微粉体を単独、もしくは上述の無機微粉体と併用して用いることができる。このような研磨効果を有する無機微粉体は、トナー粒子に外添して、トナー粒子表面に存在させることにより、添加前後と比較するとより効果が増加し得るものであり、特に限定されない。本発明に用いられる研磨効果を有する無機微粉体としては、マグネシウム、亜鉛、コバルト、マンガン、ストロンチウム、セリウム、カルシウム、バリウム等のチタン酸塩及び／又はケイ酸塩が挙げられる。
【０１１１】
特に本発明の効果をより発揮できることから、チタン酸ストロンチウム（ＳｒＴｉＯ_３）及びチタン酸カルシウム（ＣａＴｉＯ_３）、ケイ酸ストロンチウム（ＳｒＳｉＯ_３）、チタン酸バリウム（ＢａＴｉＯ_３）が好ましい。
【０１１２】
本発明で使用する無機微粉体は、例えば焼結法によって生成し、機械粉砕した後、風力分級して、所望の粒度分布であるものを用いるのが良い。
【０１１３】
本発明においては、研磨効果を有する無機微粉体は、トナー１００質量部に対して、０．１〜１０質量部、好ましくは０．２〜８質量部用いるのが良い。
【０１１４】
本発明の磁性トナーは、上述したような、特定の結着樹脂と特定の磁性体とを少なくとも含有するトナー粒子と、このトナー粒子の表面に存在する無機微粉体とを有するものである。
【０１１５】
上記本発明の磁性トナーは、重量平均粒子径が５〜１２μｍであることを特徴とする。上記磁性トナーの重量平均粒子径は好ましくは５〜１１μｍであり、より好ましくは５．５〜１０μｍである。さらに、特定の円形度を有する磁性トナーを製造する場合は、粒子径４．０μｍ以下の粒子が４０個数％以下であり、粒径１０．１μｍ以上の粒子が２５体積％以下であるトナーに限定される。
【０１１６】
重量平均粒子径が１２μｍを上回る磁性トナーの場合には、トナー粒子径自体の大きさにより、高画質化の面で問題があり好ましくない。重量平均粒子径が５μｍを下回る磁性トナーの場合には、トナーの円形度と酸化鉄粒子の分散状態のバランスを十分に取る事が出来ず、カブリ、飛び散りを悪化させる事があり好ましくない。粒子径が４．０μｍ以下の粒子の割合が４０個数％を越える場合及び粒子径が１０．１μｍ以上の粒子の割合が２５体積％を越える場合に関しても同様である。
【０１１７】
また、本発明の磁性トナーは、透過濃度が１．２〜１．７のべた黒画像の色調測定におけるａ、ｂ値が下記式（２）および（３）の関係を満足することが好ましい。
【０１１８】
【数３】
０　≦　ａ値　≦　０．５　　　　（２）
−０．５　≦　ｂ値　≦　０．８　　　　（３）
（但し、酸化鉄粒子の平均粒子径は０．１〜０．３μｍの範囲とする）
なお、上記ａ値は０〜０．４５であることがより好ましく、ｂ値は−０．５〜０．７であることがより好ましい。
【０１１９】
また、本発明の磁性トナーは、粒子径が３μｍ以上の粒子における、下記式（４）
【０１２０】
【数４】
円形度ａ　＝　Ｌ_０／Ｌ　　　　（４）
〔式中、Ｌ_０は粒子像と同じ投影面積を持つ円の周囲長を示し、Ｌは粒子像の周囲長を示す。〕
より求められる円形度（ａ）の分布において、円形度（ａ）が０．９００以上の粒子を個数基準の累積値で９０％以上有し、且つ上記円形度（ａ）の平均値が０．９４以上であることが好ましい。詳細は後述するが、前述したような特定の結着樹脂と特定の酸化鉄粒子を含有する本発明の磁性トナーの円形度分布を上記のようにすることにより、本発明の効果が最大限に発揮される。
【０１２１】
上記磁性トナーの円形度分布における円形度（ａ）が０．９００以上の粒子の個数基準の累積値が９０％未満となる場合には、トナー粒子と感光体との接触面積が大きくなり、トナー粒子の感光体への付着力が増大する為、十分な転写効率を得られず好ましくない。
【０１２２】
また、本発明の磁性トナーにおいて、重量平均粒子径及び円形度が上記範囲であれば、転写効率、帯電のコントロールに問題は無いが、粒子径の違うトナーに対して、絶えず同一の効果を与える為には、以下のように更に詳細な円形度を規定することがより好ましい。
【０１２３】
すなわち、本発明の磁性トナーはさらに、下記（Ｉ）または（ＩＩ）のいずれかを満たすものであることが好ましい。
【０１２４】
（Ｉ）重量平均粒子径（Ｘ）とカット率（Ｚ）との関係が下記式（５）
【０１２５】
【数５】
Ｚ　≦　５．３×Ｘ　　　　（５）
（より好ましくは、０　＜　Ｚ　≦　５．３×Ｘ　　　　（５’））
を満足し、且つ、上記円形度分布において、円形度（ａ）が０．９５０以上の粒子の個数基準累積値（Ｙ）と磁性トナーの重量平均粒子径（Ｘ）との関係が下記式（６）
【０１２６】
【数６】
Ｙ　≧　ｅｘｐ５．５１×Ｘ−０．６４５　　　　（６）
を満足する。
【０１２７】
（ＩＩ）重量平均粒子径（Ｘ）とカット率（Ｚ）との関係が下記式（７）
【０１２８】
【数７】
Ｚ　＞　５．３×Ｘ　　　　（７）
（より好ましくは、９５　＞　Ｚ　＞　５．３×Ｘ　　　　（７’））
を満足し、且つ、上記円形度分布において、円形度（ａ）が０．９５０以上の粒子の個数基準累積値（Ｙ）と磁性トナーの重量平均粒子径（Ｘ）との関係が下記式（８）
【０１２９】
【数８】
Ｙ　≧　ｅｘｐ５．３７×Ｘ−０．５４５　　　　（８）
を満足する。
【０１３０】
なお、本発明において、磁性トナーのカット率（Ｚ）は、東亜医用電子製フロー式粒子像分析装置ＦＰＩＡ−１０００を用いて下記の方法により測定される全測定粒子の粒子濃度をＡ（個数／μｌ）とし、円相当径３μｍ以上の測定粒子濃度をＢ（個数／μｌ）とした時、下記式（９）で表されるものである。
【０１３１】
【数９】
Ｚ　＝　（１−Ｂ／Ａ）×１００　　　（９）
上記（Ｉ）、（ＩＩ）のいずれも満たさない場合、すなわち上記式（５）を満たして上記式（６）を満たさない場合または上記式（７）を満たして上記式（８）を満たさない場合には、磁性トナーの定着部材等への付着を促進しやすくなり、トナーの流動性も悪化する場合があり、また転写効率を低下させる原因となる場合がある。
【０１３２】
このような各円形度を有する粒子のバラツキを評価する一つの目安として、円形度標準偏差ＳＤを用いることもできる。本発明においては標準偏差ＳＤが０．０３０〜０．０５０であれば問題ない。
【０１３３】
本発明における平均円形度は、粒子の形状を定量的に表現する簡便な方法として用いたものであり、本発明では東亜医用電子製フロー式粒子像分析装置ＦＰＩＡ−１０００を用いて各粒子の粒子像の投影面積および周囲長が測定される。測定結果から粒子の円形度（ａ）を上記式（４）により求める。さらに下記式（１０）で表すように、測定された全粒子の円形度（ａ）の総和を全粒子数で除した値を平均円形度と定義する。
【０１３４】
【数１０】

【０１３５】
円形度標準偏差ＳＤは、上記式（４）及び（１０）より求められる平均円形度をａ_ｍ、各粒子の円形度をａ_ｉ、測定粒子数をｍとすると、下記式から算出される。
【０１３６】
【数１１】

【０１３７】
本発明における円形度はトナー粒子の凹凸の度合いの指標であり、トナーが完全な球形の場合１．００を示し、表面形状が複雑になるほど円形度は小さな値となる。また、本発明における円形度分布のＳＤはばらつきの指標であり、数値が小さいほどシャープな分布であることを示す。
【０１３８】
なお、本発明で用いている測定装置である「ＦＰＩＡ−１０００」は、各粒子の円形度を算出後、平均円形度及び円形度標準偏差の算出に当たって、粒子を得られた円形度によって、円形度０．４〜１．０を６１分割したクラスに分け、分割点の中心値と頻度を用いて平均円形度及び円形度標準偏差の算出を行う算出法を用いている。しかしながら、この算出法で算出される平均円形度及び円形度標準偏差の各値と、上述した各粒子の円形度を直接用いる算出式によって算出される平均円形度及び円形度標準偏差の各値との誤差は非常に少なく、実質的には無視できる程度であり、本発明においては、算出時間の短縮化や算出演算式の簡略化の如きデータの取り扱い上の理由で、上述した各粒子の円形度を直接用いる算出式の概念を利用し、一部変更したこのような算出法を用いても良い。
【０１３９】
具体的な測定方法としては、容器中の予め不純物を除去した水１００〜１５０ｍｌ中に分散剤として界面活性剤、好ましくはアルキルベンゼンスルフォン酸塩を０．１〜０．５ｍｌ加え、更に測定試料を０．１〜０．５ｇ程度加える。試料を分散した懸濁液は超音波分散機で約１〜３分間分散処理を行い、分散液濃度を１．２〜２．０万個／μｌとして、上記フロー式粒子像測定装置を用い、０．６０μｍ以上１５９．２１μｍ未満の円相当径を有する粒子の円形度分布を測定する。尚、分散液濃度を１．２〜２．０万個／μｌとすることで、カット率が大きくなった場合でも装置の精度が保てるだけの粒子濃度を維持することができる。
【０１４０】
測定の概略は、東亜医用電子社（株）発行のＦＰＩＡ−１０００のカタログ（１９９５年６月版）、測定装置の操作マニュアル及び特開平８−１３６４３９号公報に記載されているが、以下の通りである。
【０１４１】
試料分散液を、フラットで扁平な透明フローセル（厚み約２００μｍ）の流路（流れ方向に沿って広がっている）を通過させる。フローセルの厚みに対して交差して通過する光路を形成するように、ストロボとＣＣＤカメラが、フローセルに対して、相互に反対側に位置するように装着される。試料分散液が流れている間に、ストロボ光がフローセルを流れている粒子の画像を得るために１／３０秒間隔で照射され、その結果、それぞれの粒子は、フローセルに平行な一定範囲を有する２次元画像として撮影される。それぞれの粒子の２次元画像の面積から、同一の面積を有する円の直径を円相当径として算出する。それぞれの粒子の２次元画像の投影面積及び投影像の周囲長から上記の円形度算出式を用いて各粒子の円形度を算出する。
【０１４２】
また、磁性トナーの粒度分布は種々の方法によって測定できるが、本発明においてはコールターカウンターのマルチサイザーを用いて行う。
【０１４３】
測定装置としてはコールターカウンターのマルチサイザーＩＩ型（コールター社製）を用い、個数分布、体積分布を出力するインターフェイス（日科機製）及びＣＸ−１パーソナルコンピューター（キヤノン製）を接続し、電解液は特級または１級塩化ナトリウムを用いて１％ＮａＣｌ水溶液を調製する。測定に際して、まず前記電解水溶液１００〜１５０ｍｌ中に分散剤として界面活性剤（好ましくはアルキルベンゼンスルホン酸塩）を０．１〜５ｍｌ加え、さらに測定試料を２〜２０ｍｇ加える。試料を懸濁した電解液は超音波分散器で約１〜３分間分散処理を行い、前記コールターカウンターのマルチサイザーＩＩ型により、アパーチャーとして、トナー粒子径を測定するときは１００μｍアパーチャーを用い、無機微粉末粒径を測定するときは１３μｍアパーチャーを用いて測定する。トナー及び無機微粉末の体積、個数を測定して、体積分布と、個数分布とを算出する。これより体積分布から求めた重量基準の重量平均粒子径（Ｄ４）を求めることができる。
【０１４４】
本発明の磁性トナーは一般的なトナー製造装置を用いて製造することができ、その製造方法は特に限定されないが、円形度及び粒子径を上述の所望の範囲に容易に制御できる製造方法が特に好ましい。
【０１４５】
具体的な例としては、結着樹脂と磁性体および必要に応じて他の添加剤としての電荷制御剤や離型剤等を加えて、ヘンシェルミキサー、ボールミルなどの混合機により乾式混合し、ニーダー、ロールミル、エクストルーダーなどの熱混練機を用いて溶融・混練して樹脂類を互いに相溶させて溶融混練物を得る。この溶融混練物を冷却固化後に固化物を粗粉砕し、得られた粗粉砕物をジェットミル、ミクロンジェット、ＩＤＳ型ミル等の衝突式気流粉砕機又はクリプトロン、ターボミル、イノマイザー等の機械式粉砕機を用いて微粉砕し、得られた微粉砕品を気流式分級機等を用いて所望の粒度分布として、本発明におけるトナー粒子が得られる。得られたトナー粒子に流動化剤や研磨剤等の無機微粉体を外添混合することにより、無機微粉体がトナー粒子表面に存在する本発明のトナーを得ることができる。
【０１４６】
トナーを混合する際の混合機としては、例えば、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一（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、混練機としては、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（神戸製銅所社製）が挙げられ、粉砕機としては、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（ターボエ業社製）が挙げられ、分級機としては、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、粗粒などをふるい分けるために用いられる篩い装置としては、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。
【０１４７】
本発明の磁性トナーを得る際の微粉砕装置としては、前述のような粉砕機を用いることができるが、ジェットミルなどのような気流式粉砕機を用いる場合には、円形度の大きなトナーが得られにくく、転写率が低くなり廃トナー減を達成することが難しい。その対策としては、処理量を下げて、粉砕圧を下げることによってソフト粉砕を行うなどして粉砕条件を工夫するか、微粉砕後又は分級後に更に表面改質処理工程を加えることが好ましい。よって、トナー生産効率向上の面から、粉砕手段としては、機械式粉砕機を用いることがより好ましい。
【０１４８】
具体的には、機械式粉砕機を用いることで、トナーの円形度を上げたい場合には、装置内負荷を上げて装置内温度を上昇させ、逆にトナーの円形度を下げたい場合には、装置内負荷を下げて装置内温度を下げることで、容易に円形度をコントロールすることが出来る。
【０１４９】
本発明のトナーを最適に生産できる機械式粉砕・分級システムは、混練過程において、溶融混練・冷却・粗粉砕することによって得られた粗粉砕物からなる粉体原料を、第１定量供給機に導入し、少なくとも中心回転軸に取り付けられた回転体からなる回転子と、該回転子表面と一定間隔を保持して回転子の周囲に配置されている固定子とを具備し、且つ間隔を保持することによって形成される環状空間が気密状態となるように構成されている機械式粉砕機内に、上記第１定量供給機から所定量の粉体原料を該機械式粉砕機の粉体導入口を介して導入し、該機械式粉砕機の上記回転子を高速回転させることによって粉体原料を微粉砕する。
【０１５０】
該微粉砕された微粉砕物を機械式粉砕機の粉体排出口から排出して第２定量供給機に導入し、第２定量供給機から所定量の微粉砕物を、交差気流とコアンダ効果を利用して粉体を気流分級する多分割気流式分級機に導入し、該多分割気流式分級機内で微粉砕物を少なくとも微粉体、中粉体及び粗粉体に分級し、分級された粗粉体を粉体原料と混入し、上記機械式粉砕機に導入して粉砕し、分級された中粉体からトナーを生成するシステムである。
【０１５１】
ここで、機械式粉砕機内で生成した微粉砕物は、機械式粉砕機の後室を経由して粉体排出口から機外へ排出される。その際、機械式粉砕機の後室の室温Ｔ１が３０〜６０℃、より好ましくは３５〜５５℃となるように、冷却装置、回転子の周速、負荷、又は回転子と固定子の最小間隔を微調節することが重要である。この温度範囲を下回っている場合は、十分に粉砕されていなかったり、粗粉砕物のままショートパスしてしまっている可能性があり、望ましい粒度・円形度にならない場合がある。一方、この温度範囲を上回っている場合は、粉砕時に過粉砕されている可能性があり、熱によるトナーの表面変質で所望の耐久安定性が得られないだけでなく、機内融着を引き起こしやすく、トナー生産性という点からも好ましくない。
【０１５２】
【実施例】
以下、実施例によって本発明をより具体的に説明するが、本発明はこれらの実施例にのみ限定されるものではない。
【０１５３】
〈酸化鉄粒子の製造例１〉
２ｍｏｌ／ｌの硫酸第一鉄水溶液５０リットルに、０．１４ｍｏｌ／ｌの硫酸チタニル水溶液５リットルを、ｐＨ＝１、温度５０℃の条件下で混合させ、十分攪拌してチタン塩含有硫酸第一鉄水溶液を得る。このチタン塩含有硫酸第一鉄水溶液と、５ｍｏｌ／ｌの水酸化ナトリウム水溶液４３リットルとを混合して水酸化第一鉄スラリーを得た。この水酸化第一鉄スラリーをｐＨ＝１２に維持し、８５℃にて空気を吹き込み酸化反応を行った。得られたマグネタイト粒子を含むスラリーを常法に従ってろ過、洗浄、乾燥、粉砕し、酸化鉄粒子（Ｍ−１）を得た。
【０１５４】
得られた酸化鉄粒子は、下記に示す方法にて分析した。分析結果を表１に示す。
【０１５５】
（ａ）平均粒子径
走査型電子顕微鏡（３００００倍）の写真を撮影し、フェレ径にて算出した。
【０１５６】
（ｂ）磁気特性
東英工業製振動試料型磁力計ＶＳＭ−Ｐ７を使用して、外部磁場７９６ｋＡ／ｍにて測定した。
【０１５７】
（ｃ）表面／内部ＦｅＯ比
３．８リットルの脱イオン水に試料の酸化鉄粒子２５ｇを加え、ウォーターバスにて温度を３５〜４０℃を保ちながら、攪拌速度２００ｒｐｍで攪拌した。このスラリー中に特級塩酸試薬４２４ｍｌを溶解した塩酸水溶液（脱イオン水）１２５０ｍｌを加え、溶解を開始した。
【０１５８】
スラリー中の酸化鉄粒子が溶解開始から全て溶解して液が透明になるまで、１０分毎に５０ｍｌサンプリングし、０．１μｍメンブランフィルターでろ過して、ろ液を採取した。採取したろ液の内、２５ｍｌをＩＣＰによって鉄元素の定量を行った。ＩＣＰにより定量された、各時間毎に採取されたろ液（採取サンプル）中の鉄元素濃度および酸化鉄粒子が完全に溶解した時の鉄元素濃度から、下記式（１２）により鉄元素溶解率を求めた。
【０１５９】
【数１２】

【０１６０】
各サンプルのＦｅＯ含有量は、残りのろ液（採取サンプル）２５ｍｌに脱イオン水約７５ｍｌを加えて試料溶液を調製し、指示薬としてジフェニルアミンスルホン酸ナトリウムを加え、０．１Ｎ重クロム酸カリウム溶液を用いて酸化還元滴定した。試料溶液が青紫色に着色したところを終点として滴定量を求め、下記式によりＦｅＯの鉄元素に対する比率（質量％）を求めた。
【０１６１】
【数１３】

【０１６２】
粒子表面から１０質量％中における総Ｆｅ量に対するＦｅＯの割合は、上記式（１２）によって得られる鉄元素溶解率が１０％となる時の採取サンプルに含有されるＦｅＯ含有量の上記採取サンプルに含有されるＦｅ量に対する割合（質量％）で求めた。また、残りの９０質量％中における総Ｆｅ量に対するＦｅＯの割合は、酸化鉄粒子が完全に溶解したときの採取サンプル中のＦｅＯ含有比および鉄元素溶解率が１０％となる時のＦｅＯ含有比から求めた。そして、下記式により表面／内部ＦｅＯ比を求めた。
【０１６３】
【数１４】

【０１６４】
〈酸化鉄粒子の製造例２〜６〉
酸化鉄粒子の製造例１において硫酸第一鉄水溶液への硫酸チタニル水溶液の添加量を変更した以外は上記製造例１と同様の方法を用いて、酸化鉄粒子（Ｍ−２）、（Ｍ−３）、（Ｍ−４）、（Ｍ−５）、（Ｍ−６）を得た。なお、（Ｍ−４）製造時には乾燥条件を真空乾燥とすることで、粒子表面のＦｅＯ量の増加を試みた。得られた各酸化鉄粒子について、上記製造例１と同様の分析を行った。分析結果を表１に示す。
【０１６５】
〈酸化鉄粒子の製造例７〜１０〉
酸化鉄粒子の製造例１において、水酸化第一鉄の酸化反応時の空気流入量及び反応温度、反応時間をそれぞれ変更した以外は上記製造例１と同様の方法を用いて、酸化鉄粒子（Ｍ−７）、（Ｍ−８）、（Ｍ−９）、（Ｍ−１０）を得た。得られた各酸化鉄粒子について、上記製造例１と同様の分析を行った。分析結果を表１に示す。
【０１６６】
〈酸化鉄粒子の製造例１１〉
酸化鉄粒子の製造例１において、硫酸第一鉄水溶液に硫酸チタニル水溶液を添加しなかった以外は上記製造例１と同様の方法を用いて、酸化鉄粒子（Ｍ−９）を得た。得られた酸化鉄粒子（Ｍ−９）について、上記製造例１と同様の分析を行った。分析結果を表１に示す。
【０１６７】
〈酸化鉄粒子の製造例１２〉
２ｍｏｌ／ｌの硫酸第一鉄水溶液５０リットルに、０．１４ｍｏｌ／ｌの硫酸チタニル水溶液５リットルを、ｐＨ＝２．５、温度７５℃の条件下で混合させ、十分攪拌してチタン塩含有硫酸第一鉄水溶液を得た。このチタン塩含有硫酸第一鉄水溶液と、５ｍｏｌ／ｌの水酸化ナトリウム水溶液４３リットルとを混合して水酸化第一鉄スラリーを得た。この水酸化第一鉄スラリーのｐＨを１２に維持し、８５℃にて空気を吹き込み酸化反応を行った。得られたマグネタイト粒子を含むスラリーを常法に従ってろ過、洗浄、乾燥、粉砕し、酸化鉄粒子（Ｍ−１２）を得た。得られた酸化鉄粒子（Ｍ−１２）について、上記製造例１と同様の分析を行った。分析結果を表１に示す。
【０１６８】
〈酸化鉄粒子の製造例１３〉
酸化鉄粒子の製造例１において、水酸化第一鉄スラリーを生成させる際のアルカリ溶液（水酸化ナトリウム水溶液）の量を調整して、水酸化第一鉄スラリーのｐＨを７．８とした以外は上記製造例１と同様の方法を用いて、酸化鉄粒子（Ｍ−１３）を得た。得られた酸化鉄粒子（Ｍ−１３）について、上記製造例１と同様の分析を行った。分析結果を表１に示す。
【０１６９】
【表１】

【０１７０】
〈結着樹脂の製造例１〉
・テレフタル酸　　　　　　　　　　　６１０ｇ
・無水トリメリット酸　　　　　　　　６１０ｇ
・フマル酸　　　　　　　　　　　　　３１０ｇ
・プロポキシ化ビスフェノールＡ　　　１０５０ｇ
・エトキシ化ビスフェノールＡ　　　　４５０ｇ
【０１７１】
上記ポリエステルモノマーを、炭化水素系ワックス１８９ｇ、エステル化触媒とともに４口フラスコに仕込み、減圧装置、水分離装置、窒素ガス導入装置、温度測定装置及び撹拌装置を装着して窒素雰囲気下にて１３０℃の温度で撹拌しつつ、ビニル系重合体モノマー（スチレン６２１ｇ、２−エチルヘキシルアクリレート１３６ｇ、ジビニルベンゼン０．１３ｇ）を混合したものを滴下ロートから４時間かけて滴下した。これを１３０℃に保持したまま３時間熟成し、２３０℃に昇温して反応を行った。反応終了後容器から取り出し、冷却、粉砕し、結着樹脂Ａを得た。
【０１７２】
〈結着樹脂の製造例２〜７〉
結着樹脂の製造例１において、モノマーの使用量を表２に示すように変更した以外は上記製造例１と同様の方法を用いて、結着樹脂Ｂ〜Ｇを得た。
【０１７３】
〈結着樹脂の製造例８〉
表２に示すようなモノマーを縮重合して、ポリエステル樹脂Ｈを得た。
【０１７４】
〈結着樹脂の製造例９〉
キシレン１００質量部を、還流管、撹拌機、窒素導入管、温度計、滴下装置及び減圧装置を備えた反応容器に投入した後に、スチレン１３９４ｇ、アクリル酸ブチル４３６ｇ、マレイン酸モノブチル５５０ｇ及び重合開始剤としてジ−ｔ−ブチルパーオキサイド１５８ｇを投入し、窒素を通気しながら還流温度まで加熱して１２時間保持した。次にキシレンを減圧留去することによりビニル系樹脂Ｉを得た。
【０１７５】
結着樹脂Ａ〜Ｉの組成を表２に示す。
【０１７６】
【表２】

【０１７７】
〈実施例１〉
・結着樹脂Ａ　　　　　　　　　　１００質量部
・酸化鉄粒子（Ｍ−１）　　　　　　９０質量部
（平均粒子径０．１３μｍ、７９５．８ｋＡ／ｍ磁場での特性：Ｈｃ＝１１．５ｋＡ／ｍ、σｓ＝８６．５Ａｍ^２／ｋｇ、σｒ＝１５．７Ａｍ^２／ｋｇ）
・アゾ系鉄錯体化合物　　　　　　　　２質量部
上記の処方の材料を、ヘンシェルミキサー（ＦＭ−７５型、三井三池化工機（株）製）でよく混合した後、温度１３０℃に設定した２軸混練機（ＰＣＭ−３０型、池貝鉄工（株）製）にて混練した。得られた混練物を冷却し、ハンマーミルにて粒子径１ｍｍ以下に粗粉砕し、トナー製造用粉体原料である粉体原料Ａ（粗粉砕物）を得た。
【０１７８】
粉体原料Ａをターボ工業社製ターボミルＴ−２５０型を用い、粗砕品供給量を２０ｋｇ／ｈｒとして、機械式粉砕機内の入口温度を−１０℃、出口温度を４８℃となるように調整して微粉砕を行い、重量平均粒子径が７．１μｍである微粉砕品を得た。次いでこの微粉砕品を風力分級機で分級することで、重量平均粒子径が７．２μｍである分級品（Ｂ−１）を得た。
【０１７９】
この分級品（Ｂ−１）１００質量部に対して、疎水性シリカ微粉体（ＢＥＴ比表面積＝３００ｍ^２／ｇ）１．２質量部をヘンシェルミキサーにて外添添加して、磁性トナーである評価用トナー１を得た。
【０１８０】
このトナーは重量平均粒子径が７．２μｍであり、ＦＰＩＡ　１０００にて測定した結果、平均円形度が０．９５２であり、円形度ａ＝０．９００以上の粒子が９４．５個数％、円形度ａ＝０．９５０以上の粒子が７０．５個数％であった。また、粒子径が３μｍ以下の粒子のカット前の（全粒子）粒子濃度Ａは１４３６５．２個数／μｌであり、粒子径が３μｍ以上の測定粒子濃度Ｂは１２００５．６個数／μｌであった。
【０１８１】
（評価１）
キヤノン製複写機ＩＲ６０００の現像、感光体、光学、紙搬送系等を全て調整して複写速度を２０％アップさせ、さらに転写前帯電器（ポスト帯電器）を取り外した。上記改造機と評価用トナー１を、高温高湿環境室（３２．５℃、８５％ＲＨ）に二晩（２４時間以上）放置した。このとき、結露防止として、高温高湿環境室に入れる際、トナー及びＩＲ６０００改造機をビニールで包装し、６時間以上調温・調湿後開封した。二晩放置後、評価用トナー１を現像器に手補給し、現像器の質量を測定後、ＩＲ６０００へ設置し、現像スリーブを３分間空回転させた。このとき、本体内のクリーナー部及び廃トナー回収部は事前に一旦取り外し、質量を測定しておいた。
【０１８２】
印字比率６％のテストチャートを用いて、５００枚画出しを行い転写率を評価した。評価用トナー１の転写率は８８％となった。なお、転写率は下記式より算出した。
【０１８３】
【数１５】

【０１８４】
（評価２）
評価用トナー１を３６０ｇをＩＲ６０００用現像器に手補給し、評価１で使用したＩＲ６０００改造機に転写前帯電器（ポスト帯電器）を装備させた装置とともに、常温低湿室（２３℃／５０％）に一晩（１２時間以上）放置した。その後、印字比率４％のテストチャートを用いて、２０００枚画出しを行った。その後、べた黒画像の透過濃度が１．７となるように調整し、Ａ３用紙にてべた黒画像３枚を出力した。出力した３枚目のべた黒画像の色調を測定した。
【０１８５】
色調測定は１９７６年に国際照明委員会（ＣＩＥ）で規格された表色系の定義に基づき、定量的に測定した。測定機にはＸ−Ｒｉｔｅ社製分光測色計タイプ９３８を用い、観察用光源はＣ光源、視野角は２°とした。その結果、ａ値が０．３４、ｂ値が０．０３、Ｌ値が２２．５となった。また、同時に複写機開発及びトナー開発に関わる１０人に上記測定した画像を目視にて黒味確認してもらったところ、１０人全員が黒味は十分との回答を出した。
【０１８６】
評価レベルは以下の通りである。
【０１８７】
◎　：１０人全員が問題無しと判定
○　：８人以上が問題無しと判定
△　：６人以上が問題無しと判定
×　：５人以上が赤味が強いと判定
××：７人以上が赤味が強いと判定
【０１８８】
（評価３）
評価２で使用したＩＲ６０００改造機と評価用トナー１を、高温高湿環境下（３０℃／８５％）に二晩（２４時間以上）放置した。このとき、評価１と同様に調温・調湿した。二晩放置後、現像スリーブを３分間回転させたのち、印字比率６％のテストチャートを用いて、１００万枚の通紙試験を行い、耐久前後での画像濃度の比較、耐久後のかぶり、感光体へのトナー付着を評価した。
【０１８９】
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反射濃度測定を行い、画像中の５ｍｍ丸（５φ）の濃度を測定した。測定結果は以下のような基準により評価した。
【０１９０】
濃度安定性は、耐久初期の値と耐久後の濃度差で評価した。
【０１９１】
◎：優れている（濃度差が０．０３未満）
○：良好　　　（濃度差が０．０３以上０．１未満）
△：問題なし　（濃度差が０．１以上０．３未満）
×：劣る　　　（濃度差が０．３以上）
カブリは、テストチャート上の白地部にて画質評価した。カブリは、リフレクトメーター（東京電色社製）により測定した、定着画像の白地部分の白色度と、転写材の白色度の差から、カブリ濃度（％）を算出し、画像カブリを評価した。
【０１９２】
カブリレベルは以下の基準によって判断した。
【０１９３】
◎：カブリが０．１％未満
○：カブリが０．１以上１．０％未満
△：カブリが１．０以上２．０％未満
×：カブリが２．０以上３．０％未満
トナー付着の評価は、べた黒画像における画像欠陥である白点の個数によって以下の評価基準に従い評価した。
【０１９４】
◎：１０万枚の耐久試験後にも５個以下。
〇：５万枚の耐久試験後に５個以下で、実用上問題なし。
△：　３万枚の耐久試験後に５個以下、３０万枚の耐久試験後に５個以上。
×：　３万枚の耐久試験後に５個以上確認できる。
【０１９５】
各評価の評価結果を表５に示す。
【０１９６】
〈実施例２〉
実施例１で作製した粉体原料Ａ（粗粉砕物）を、日本ニューマチック工業社製Ｉ−２型ミルを用い、粗砕品供給量を５．５ｋｇ／ｈｒ、粉砕圧６ｋｇＰａとし、更に、所定の粒径に粉砕されなかったトナー粗砕品は再度、粉砕機内へ戻るように設定して粉砕し、重量平均径が７．３μｍである微粉砕品を得た。更に、風力分級機で分級することで、重量平均径が７．４μｍである分級品（Ｂ−２）を得た。
【０１９７】
この分級品（Ｂ−２）１００質量部に対して、疎水性シリカ微粉体（ＢＥＴ比表面積＝３００ｍ^２／ｇ）１．０質量部をヘンシェルミキサーにて外添添加して評価用トナー２を得た。この評価用トナー２の粒度、円形度を表３に示す。評価用トナー２について実施例１と同様の評価を行った。評価結果を表５に示す。
【０１９８】
〈実施例３〉
実施例１で使用した酸化鉄粒子（Ｍ−１）の代わりに、酸化鉄粒子（Ｍ−３）を使用した以外は、実施例１と同様の方法を用いて粉体原料Ｂ（粗粉砕物）を得た。この粉体原料Ｂを微粉砕した後に、得られた微粉砕品をさらに６２℃の熱球形化装置を通したこと以外は、実施例２と同様の方法を用いて、評価用トナー３を作製した。この評価用トナー３の粒度、円形度を表３に示す。この評価用トナー３について実施例１と同様の評価を行った。評価結果を表５に示す。
【０１９９】
〈実施例４〉
実施例１で使用した酸化鉄粒子（Ｍ−１）の代わりに、酸化鉄粒子（Ｍ−４）を使用した以外は、実施例１と同様の方法を用いて粉体原料Ｃ（粗粉砕物）を得た。この粉体原料Ｃを、日本ニューマチック工業社製Ｉ−２型ミルを用い、粗砕品供給量を１．５ｋｇ／ｈｒ、粉砕圧２ｋｇＰａとした以外は、上記実施例２と同様の方法を用いて、評価用トナー４を得た。この評価用トナー４の粒度、円形度を表３に示す。この評価用トナー４について実施例１と同様の評価を行った。評価結果を表５に示す。
【０２００】
〈実施例５、６〉
実施例１において、酸化鉄粒子（Ｍ−１）の代わりに酸化鉄粒子（Ｍ−５）および（Ｍ−８）をそれぞれ用い、機械式粉砕機で微粉砕する際の粗砕品供給量、及び粉砕機内の入口温度と出口温度を任意に調整した以外は、上記実施例１と同様の方法を用いて分級品を作製した。各分級品１００質量部に対して、疎水性シリカ微粉体（ＢＥＴ比表面積＝３００ｍ^２／ｇ）１．０質量部とチタン酸ストロンチウム（平均粒径１．８μｍ）４．０質量部をそれぞれヘンシェルミキサーにて外添添加して評価用トナー５、６を得た。これら各トナーの粒度、円形度を表３に示す。各評価用トナー５、６について実施例１と同様の評価を行った。評価結果を表５に示す。
【０２０１】
〈実施例７〉
実施例１において、酸化鉄粒子（Ｍ−１）の代わりに酸化鉄粒子（Ｍ−９）を用い、機械式粉砕機で微粉砕する際の粗砕品供給量、及び粉砕機内の入口温度と出口温度を任意に調整した以外は、上記実施例１と同様の方法を用いて評価用トナー７を得た。この評価用トナー７の粒度、円形度を表３に示す。この評価用トナー７について実施例１と同様の評価を行った。評価結果を表５に示す。
【０２０２】
〈実施例８、９〉
実施例１において、結着樹脂Ａの代わりに結着樹脂Ｂ、Ｃをそれぞれ用い、機械式粉砕機で微粉砕する際の粗砕品供給量及び、粉砕機内の入口温度と出口温度を任意に調整した以外は、上記実施例１と同様の方法を用いて分級品を作製した。これらの分級品１００質量部に対して、疎水性シリカ微粉体（ＢＥＴ比表面積＝３００ｍ^２／ｇ）１．０質量部とチタン酸ストロンチウム（平均粒径１．８μｍ）４．０質量部をヘンシェルミキサーにて外添添加して、評価用トナー８、９を得た。これら各評価用トナー８、９の粒度、円形度を表３に示す。各評価用トナー８、９について実施例１と同様の評価を行った。評価結果を表５に示す。
【０２０３】
〈実施例１０、１１〉
実施例１において、結着樹脂Ａの代わりに結着樹脂Ｄ、Ｅをそれぞれ用い、更に酸化鉄粒子（Ｍ−１）の代わりに酸化鉄粒子（Ｍ−３）を用い、機械式粉砕機で微粉砕する際の粗砕品供給量及び、粉砕機内の入口温度と出口温度を任意に調整した以外は、上記実施例１と同様の方法を用いて分級品を作製した。これらの分級品１００質量部に対して、疎水性シリカ微粉体（ＢＥＴ比表面積＝３００ｍ^２／ｇ）１．０質量部とチタン酸ストロンチウム（平均粒径１．８μｍ）４．０質量部をヘンシェルミキサーにて外添添加して評価用トナー１０、１１を得た。これら各評価用トナー１０、１１の粒度、円形度を表３に示す。各評価用トナー１０、１１について実施例１と同様の評価を行った。評価結果を表５に示す。
【０２０４】
〈実施例１２〜１５〉
実施例１において、結着樹脂Ａの代わりに結着樹脂Ｅを用い、更に酸化鉄粒子（Ｍ−１）の代わりに、酸化鉄粒子（Ｍ−５）を使用した。酸化鉄粒子（Ｍ−５）の添加量を５０、７５、１２０、１５０質量部にそれぞれ変更し、機械式粉砕機で微粉砕する際の粗砕品供給量及び、粉砕機内の入口温度と出口温度を任意に調整した以外は、上記実施例１と同様の方法を用いて分級品を作製した。これらの分級品１００質量部に対して、疎水性シリカ微粉体（ＢＥＴ比表面積＝３００ｍ^２／ｇ）０．５〜１．２質量部とチタン酸ストロンチウム（平均粒径１．８μｍ）４．０質量部とをヘンシェルミキサーにて外添添加して評価用トナー１２、１３、１４、１５を得た。これら各トナー１２〜１５の粒度、円形度を表３に示す。各評価用トナー１２〜１５について実施例１と同様の評価を行った。評価結果を表５に示す。
【０２０５】
〈実施例１６〉
実施例１において、結着樹脂Ａの代わりに結着樹脂Ｅを用い、更に酸化鉄粒子（Ｍ−１）の代わりに酸化鉄粒子（Ｍ−１３）を使用し、酸化鉄粒子（Ｍ−１３）の添加量を１２０質量部とした以外は、上記実施例１と同様の方法を用いて評価用トナー１６を得た。得られたトナー１６の粒度、円形度を表３に示す。この評価用トナー１６について実施例１と同様の評価を行った。評価結果を表５に示す。
【０２０６】
〈実施例１７〉
・結着樹脂Ｈ　　　　　　　　　　８０質量部
・結着樹脂Ｉ　　　　　　　　　　２０質量部
・酸化鉄粒子（Ｍ−１）　　　　　９０質量部
（平均粒子径０．１３μｍ、７９５．８ｋＡ／ｍ磁場での特性：Ｈｃ＝１１．５ｋＡ／ｍ、σｓ＝８６．５Ａｍ^２／ｋｇ、σｒ＝１５．７Ａｍ^２／ｋｇ）
・アゾ系鉄錯体化合物　　　　　　　２質量部
・炭化水素系ワックス　　　　　　　４質量部
上記の処方の材料を、実施例１と同様に、混合、混練後、粗粉砕し、トナー製造用粉体原料である粉体原料Ｄ（粗粉砕物）を得た。
【０２０７】
粉体原料Ｄを実施例１と同様に微粉砕、分級した。得られた分級品１００質量部に対して、疎水性シリカ微粉体（ＢＥＴ比表面積＝３００ｍ^２／ｇ）１．０質量部をヘンシェルミキサーにて外添添加して評価用トナー１７を得た。この評価用トナー１７の粒度、円形度を表３に示す。この評価用トナー１７について実施例１と同様の評価を行った。評価結果を表５に示す。
【０２０８】
〈比較例１、２〉
実施例１において、結着樹脂Ａの代わりに、結着樹脂Ｆおよび結着樹脂Ｇを使用し、機械式粉砕機で微粉砕する際の粗砕品供給量及び、粉砕機内の入口温度と出口温度を任意に調整した以外は、実施例１と同様の方法を用いて比較評価用トナー１８、１９を得た。これら各トナー１８、１９の粒度、円形度を表４に示す。各比較評価用トナー１８、１９について実施例１と同様の評価を行った。評価結果を表５に示す。
【０２０９】
〈比較例３〉
・結着樹脂Ｈ　　　　　　　　　　１００質量部
・酸化鉄粒子（Ｍ−１）　　　　　１２０質量部
（平均粒子径０．１３μｍ、７９５．８ｋＡ／ｍ磁場での特性：Ｈｃ＝１１．５ｋＡ／ｍ、σｓ＝８６．５Ａｍ^２／ｋｇ、σｒ＝１５．７Ａｍ^２／ｋｇ）
・アゾ系鉄錯体化合物　　　　　　　　２質量部
・炭化水素系ワックス　　　　　　　　４質量部
上記の処方の材料を、実施例１と同様に、混合、混練後、粗粉砕し、トナー製造用粉体原料である粉体原料Ｅ（粗粉砕物）を得た。
【０２１０】
粉体原料Ｅを実施例１と同様に微粉砕、分級した。得られた分級品１００質量部に対して、疎水性シリカ微粉体（ＢＥＴ比表面積＝３００ｍ^２／ｇ）１．０質量部をヘンシェルミキサーにて外添添加して比較評価用トナー２０を得た。得られた比較評価用トナー２０の粒度、円形度を表４に示す。この比較評価用トナー２０について実施例１と同様の評価を行った。評価結果を表５に示す。
【０２１１】
〈比較例４〉
比較例３において、結着樹脂Ｈの代わりに結着樹脂Ｉを使用し、且つ酸化鉄粒子（Ｍ−１）の代わりに酸化鉄粒子（Ｍ−２）を使用し、機械式粉砕機で微粉砕する際の粗砕品供給量及び、粉砕機内の入口温度と出口温度を任意に調整した以外は、比較例３と同様の方法を用いて比較評価用トナー２１を得た。得られた比較評価用トナー２１の粒度、円形度を表４に示す。この比較評価用トナー２１について実施例１と同様の評価を行った。評価結果を表５に示す。
【０２１２】
〈比較例５〜９〉
実施例１において、酸化鉄粒子（Ｍ−１）の代わりに酸化鉄粒子（Ｍ−６）、（Ｍ−７）、（Ｍ−１０）、（Ｍ−１１）、（Ｍ−１２）をそれぞれ用い、機械式粉砕機で微粉砕する際の粗砕品供給量及び、粉砕機内の入口温度と出口温度を任意に調整した以外は、実施例１と同様の方法を用いて比較評価用トナー２２、２３、２４、２５、２６を得た。これら各比較評価用トナー２２〜２６の粒度、円形度を表４に示す。各評価用トナー２２〜２６について実施例１と同様の評価を行った。評価結果を表５に示す。
【０２１３】
【表３】

【０２１４】
【表４】

【０２１５】
【表５】

【０２１６】
【発明の効果】
本発明によれば、小粒径化したり形状を球形に近づけても、帯電安定性、耐久安定性および高現像性に優れ且つ黒色度の高いトナーを提供することができる。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a magnetic toner used in an image forming method such as an electrophotographic method, an electrostatic recording method, an electrostatic printing method, or a toner jet recording method.
[0002]
[Prior art]
2. Description of the Related Art In recent years, image forming apparatuses have spread not only to copy originals but also as information output devices linked to other information devices by digitization, and have been used for toners such as high definition, high quality, high image quality, high speed, and high reliability. The required performance is only increasing. In particular, the functions of the copying machines have been advanced, and digital copying machines have become mainstream. This digital copier mainly uses a method of forming an electrostatic charge image with a laser. To achieve a high-resolution and high-definition developing method, the toner particle size has been reduced and the particle size distribution has been sharpened. I have.
[0003]
On the other hand, when a toner image is transferred from a photoreceptor to a transfer material in an image forming process by a copying machine, toner remaining after transfer exists on the photoreceptor. In order to quickly perform continuous copying, it is necessary to clean the residual toner on the photoconductor. Further, the collected residual toner is disposed in a container or a collection box installed in the main body and then discarded, or is recycled through an appropriate process. In order to reduce this residual toner, it is common to reduce the residual toner by improving the transfer rate when the toner image is transferred to the transfer material from the photoreceptor by reducing the residual toner to a more spherical shape. is there.
[0004]
However, if the toner is simply reduced in particle size or made more spherical, the dispersibility of the binder resin and other internal additives easily affects the toner performance. In particular, in the case of a magnetic toner containing a large amount of iron oxide particles as magnetic powder, the details will be described later. However, depending on the dispersion state of the iron oxide particles, problems such as a decrease in image density, a decrease in durability stability, and a decrease in image quality are caused. May cause
[0005]
When the iron oxide particles in the magnetic toner particles are in a non-uniform state, the total amount of the iron oxide particles precipitated on the toner particle surface is different from each other, so that when the toner is frictionally charged with the charging member (developing sleeve), When there is no or very small iron oxide particles on the toner surface, the chargeability of the toner surface is increased. Conversely, when the iron oxide particles are excessively present on the toner surface, the iron oxide particles act as leak sites, and Has low chargeability. An increase in the width of the charge distribution in this way causes various problems.
[0006]
For example, not only the charging characteristics of the toner are easily affected by the environment, but also the fog in which the toner is developed in the non-image area is likely to occur. Also, when transferring toner from a photoreceptor to a transfer material, if excessively charged toner is present, a phenomenon called "scattering" occurs in which toner scatters around a character or a line image. In particular, in a high-speed machine, there is a method of improving transfer efficiency by performing pre-transfer charging (post-charging) to reduce excess charges, but in this case, scattering is remarkably deteriorated.
[0007]
If the toner is not sufficiently charged for the purpose of suppressing scattering, there is a toner that is insufficiently charged, which causes a decrease in developability and fog. For the purpose of reducing the fog, attempts have been made to further sharpen the toner particle size distribution, but this causes a cost increase due to a decrease in yield in the production of toner.
[0008]
Furthermore, especially when the copy volume becomes very large over a long period of time due to repeated toner replenishment, the iron oxide particles are not sufficiently dispersed in the toner particles, so that the iron oxide particles may be released from the toner particles or may be left on the toner surface. The exposed iron oxide particles not only affect the fluidity of the magnetic toner in the developing unit and the frictional charging property between the photoconductor and the charging member, but also cause toner adhesion to the photoconductor and cause image defects. Cheap.
[0009]
JP-A-3-101743 and JP-A-3-101744 disclose reducing the particle size of the magnetic powder and narrowing the particle size distribution in order to uniformly disperse the magnetic powder in the toner particles. ing. Japanese Patent Application Laid-Open No. 3-48257 discloses a device which aims at the same effect by using a spherical magnetic material.
[0010]
Certainly, these treatments tend to make the magnetic substance dispersion in the toner easier to homogenize, but the iron oxide particles having a small particle diameter have a strong cohesive property, so that they can be sufficiently dispersed in the toner with a normal toner manufacturing apparatus. It may not be possible. In other words, in the toner manufacturing process, if a large agglomerate of iron oxide particles is converted into a toner without being broken into small agglomerates, oxidization such as the ratio of the content in the fine powder to the content in the coarse powder may occur. Even if the macrodispersibility of the iron particles is sufficiently ensured, it cannot be said that the uniformity precisely controlled to the level of the primary particles of the iron oxide particles is achieved.
[0011]
In particular, in the case of a toner having a small particle diameter or a toner having a more spherical shape, the dispersibility of iron oxide particles from a microscopic viewpoint is insufficient. And other problems become remarkable. Therefore, further improvement in durability stability, developability and dispersibility of iron oxide particles of magnetic toners are expected, but more precise dispersibility improvement cannot be achieved only by controlling physical properties of iron oxide particles. is the current situation.
[0012]
Further, when the iron oxide particles are made into fine particles, a problem of deterioration in blackness also arises. Conventionally, iron oxide particles, in particular, FeO (or ²⁺ ) Is known to be dependent on the content of FeO. However, the content of FeO in the iron oxide particles decreases as the deterioration over time due to oxidation after the production proceeds, which is accompanied by a phenomenon that the blackness is deteriorated. Needless to say, this aging is greatly affected by the environment in which the iron oxide particles are placed, but is accelerated by making the iron oxide particles finer.
[0013]
In order to obtain iron oxide particles having high blackness and excellent environmental resistance, a technique of adding various elements to iron oxide particles has been disclosed in the past. For example, an iron oxide particle having a composite iron oxide coating containing Co described in JP-A-6-100317 or JP-A-8-133744, or a composite iron oxide coating containing Zn described in JP-A-8-133745 is disclosed. Examples include iron oxide particles and iron oxide particles containing a composite iron oxide containing Mn, Zn, Cu, Ni, Co, Mg and the like described in JP-A-4-162050. The role of these additional elements is to coat the particles with an additional element oxide so that the FeO does not directly contact the atmosphere of the outside world, or to replace the FeO with an additional element oxide that does not reduce the blackness, Deterioration of blackness is suppressed.
[0014]
However, the iron oxide particles obtained by such a method are insufficient for preventing the decrease in blackness and suppressing the deterioration with time for the purpose of forming fine particles for uniform dispersion in the toner particles. Depending on the additive element, it may affect the magnetic properties of the iron oxide particles themselves, and may cause defects related to development other than color. That is, at present, a magnetic toner having a high degree of blackness with a small particle diameter, a shape closer to a sphere for the purpose of improving transfer efficiency, and further having both durability stability and high developability cannot be realized.
[0015]
[Problems to be solved by the invention]
Accordingly, the present invention has been made in view of the above-described circumstances in the related art, and has an object to improve the disadvantages. That is, an object of the present invention is to provide a toner having high blackness, which is excellent in charge stability, durability stability and high developability even when the particle diameter is reduced.
[0016]
Another object of the present invention is to provide a toner having high blackness, which is excellent in charge stability, durability stability and high developability even when the shape is made closer to a sphere for the purpose of improving transfer efficiency.
[0017]
[Means for Solving the Problems]
As a result of intensive studies, the present inventors focused on the structure of the binder resin contained in the magnetic toner, the dispersion state of Fe (II) and the content of Ti in the magnetic material, and set these as specific ones. As a result, it has been found that a magnetic toner having a high blackness can be obtained without impairing charging stability, durability stability and high developability even with a magnetic toner having a small particle diameter and a spherical shape, and the present invention has been completed.
[0018]
That is, the present invention is as follows.
[0019]
(1) A magnetic toner comprising toner particles containing at least a binder resin and a magnetic material, and inorganic fine powder present on the surface of the toner particles,
The binder resin contains at least a polyester resin containing a polyester monomer unit and a vinyl resin containing a vinyl monomer unit, and the content ratio of the polyester monomer unit to the vinyl monomer unit is 50/50 to 90 / by mass ratio. 10 and
A weight average particle diameter (D4) of the magnetic toner is 5 to 12 μm;
The magnetic substance is (1) iron oxide particles having an average particle diameter of 0.1 to 0.3 μm,
(2) 0.3 to 1.5 mass% of titanium element is contained in the iron oxide particles with respect to the total amount of the iron oxide particles,
{Circle over (3)} The ratio of the ratio of FeO (A%) to the total amount of Fe in 10% by mass from the surface of the iron oxide particles (A%) and the ratio of FeO to the total amount of Fe (B%) in the remaining 90% by mass (A / B) is the following formula (1)
0.7 ≦ A / B ≦ 1 (1)
A magnetic toner characterized by satisfying the following.
[0020]
(2) The a and b values in the S color tone measurement of a solid black image having a transmission density of 1.2 to 1.7 satisfy the relationship of the following equations (2) and (3). Magnetic toner.
[0021]
0 ≦ a value ≦ 0.5 (2)
−0.5 ≦ b value ≦ 0.8 (3)
(However, the average particle diameter of the iron oxide particles is in the range of 0.1 to 0.3 μm.)
(3) The magnetic toner according to (1) or (2), wherein the iron oxide particles are octahedral.
[0022]
(4) The magnetic toner according to any one of (1) to (3), wherein the iron oxide particles are contained in an amount of 50 to 150 parts by mass with respect to 100 parts by mass of the binder resin.
[0023]
(5) The magnetic toner according to any one of (1) to (3), wherein the iron oxide particles are contained in an amount of 60 to 120 parts by mass with respect to 100 parts by mass of the binder resin.
[0024]
(6) Formula (4) below for particles of 3 μm or more in magnetic toner.
Circularity a = L ₀ / L (4)
[Where L ₀ Represents the perimeter of a circle having the same projected area as the particle image, and L represents the perimeter of the particle image. ]
In the number-based circularity distribution obtained from the circularity (a), particles having a circularity (a) of 0.900 or more exist in 90% by number or more, and the average value of the circularity (a) is 0. The magnetic toner according to any one of (1) to (5), wherein the magnetic toner has a ratio of 94 or more.
[0025]
(7) The relationship between the weight average particle diameter (X) and the cut ratio (Z) of the magnetic toner is expressed by the following equation (5).
Z ≦ 5.3 × X (5)
Satisfied,
In the circularity distribution, the relationship between the number-based cumulative value (Y) of particles having a circularity (a) of 0.950 or more and the weight average diameter (X) of the magnetic toner is represented by the following equation (6).
Y ≧ exp5.51 × X−0.645 (6)
(6) The magnetic toner according to (6), wherein
[0026]
(8) The relationship between the weight average particle diameter (X) and the cut rate (Z) of the magnetic toner is represented by the following equation (7).
Z> 5.3 × X (7)
Satisfied,
In the circularity distribution, the relationship between the number-based cumulative value (Y) of particles having a circularity (a) of 0.950 or more and the weight average diameter (X) of the magnetic toner is represented by the following equation (8).
Y ≧ exp 5.37 × X−0.545 (8)
(6) The magnetic toner according to (6), wherein
[0027]
(9) The magnetic toner according to any one of (1) to (8), wherein the content ratio of the polyester monomer unit to the vinyl monomer unit in the binder resin is 60/40 to 85/15. .
[0028]
(10) The magnetic material according to any one of (1) to (9), wherein the binder resin further contains a hybrid resin component obtained by partially reacting the polyester-based monomer unit and the vinyl-based monomer unit. toner.
[0029]
(11) The polyester-based monomer unit of the binder resin has a structure crosslinked with a trivalent or higher polyhydric carboxylic acid or an anhydride thereof and / or a trivalent or higher polyhydric alcohol. The magnetic toner according to any one of (1) to (10).
[0030]
BEST MODE FOR CARRYING OUT THE INVENTION
The magnetic toner of the present invention has toner particles containing at least a binder resin and a magnetic substance, and inorganic fine powder present on the surface of the toner particles, wherein the binder resin is a polyester resin containing a polyester monomer unit. It contains at least a vinyl-based resin containing a vinyl-based monomer unit, the content ratio between the polyester-based monomer unit and the vinyl-based monomer unit is 50/50 to 90/10 by mass, and the weight-average particle diameter (D4) is 5 The magnetic material is (1) iron oxide particles having an average particle diameter of 0.1 to 0.3 μm, and (2) 0.3 to 1.5 mass% with respect to the total amount of iron oxide particles. The titanium element is contained in the iron oxide particles. (3) The ratio (A%) of FeO to the total amount of Fe in 10% by mass from the surface of the iron oxide particles, and the total amount of Fe in the remaining 90% by mass. The ratio (A / B) of the ratio (A / B) of FeO to the ratio (B%) of
[0031]
(Equation 1)
0.7 ≦ A / B ≦ 1 (1)
Is satisfied.
[0032]
Conventionally, it is known that the shape of toner particles affects various properties of the toner. However, the present inventors have studied the particle size and shape of the magnetic toner, and have determined that the toner particles having a particle size of 3 μm or more are used. It has been found that there is a close relationship between the degree of circularity and transferability, developability (image quality), and fixability.
[0033]
For example, the specific surface area of the toner particles is increased by reducing the particle size of the toner in response to recent demands for high image quality and high image quality. This increases the cohesiveness and adhesion of the toner. For this reason, when the toner image is transferred onto the transfer material from the photoreceptor, the adhesive force acting between the photoreceptor and the toner is increased, and the transfer efficiency is reduced. In particular, the magnetic black toner produced by the conventional pulverizing method is irregular and angular, and this tendency is remarkable. In other words, in order to improve the transfer efficiency, it is important to reduce the contact area between the toner and the photoconductor by making the toner shape closer to a sphere, and to provide low adhesion even with a small particle size. It is.
[0034]
Since the magnetic toner contains a large amount of iron oxide particles, the developability and durability stability of the toner are likely to be influenced by the fineness of the dispersibility. For this reason, emphasis has been placed on more uniform dispersibility of iron oxide particles in magnetic toner particles. Various studies have been conducted to improve the dispersibility of iron oxide particles.The iron oxide particles added to the toner particles themselves can be reduced in particle size, and iron oxide particles having a nearly spherical shape can be used as toner particles. Some internal dispersion uniformity has been achieved by internal addition to the particles.
[0035]
However, by making the iron oxide particles themselves finer, FeO (or Fe ²⁺ ) Deterioration is promoted, and it is difficult to maintain the black tint as a magnetic black toner, or the iron oxide particles are made into a spherical shape, so that the number of iron oxide particles that are released may increase. Problems also occurred. Further, as described above, when the toner has a smaller particle size or a shape closer to a true sphere, it is difficult to achieve sufficient dispersion uniformity only by making the iron oxide particles themselves finer. It has become.
[0036]
Therefore, according to the study of the present inventors, as described above, a binder resin containing a polyester resin and a vinyl resin in a specific ratio, and a magnetic resin containing a specific iron oxide particle containing a predetermined amount of titanium. Even when the magnetic toner of the present invention including toner particles containing a toner particle has a small particle size and a shape close to a true sphere in order to achieve high image quality and suppress generation of waste toner, the toner particles It has been found that the dispersibility of the iron oxide particles therein can be maintained, good durability stability and high developability are achieved, and that the black oxide has high blackness.
[0037]
Hereinafter, the magnetic toner of the present invention will be described in detail. In the present invention, as described above, the characteristics of the iron oxide particles and the binder resin as the magnetic substance contained in the toner particles are important. First, the magnetic material and the binder resin will be described.
[0038]
[Magnetic substance used in magnetic toner of the present invention]
The magnetic material used in the present invention is (1) iron oxide particles having an average particle diameter of 0.1 to 0.3 μm, and (2) 0.3 to 1.5 mass% based on the total amount of iron oxide particles. (3) The ratio (A%) of FeO to the total amount of Fe in 10% by mass from the surface of the iron oxide particles, and the ratio of FeO to the total amount of Fe in the remaining 90% by mass. (B /%) (A / B; hereinafter sometimes referred to as “surface / internal FeO ratio”) satisfying the following expression (1).
[0039]
(Equation 2)
0.7 ≦ A / B ≦ 1 (1)
The magnetic material used in the present invention is preferably iron oxide particles mainly composed of magnetite having a high FeO content. Hereinafter, magnetite particles, which are typical iron oxide particles, will be described. When iron oxide particles or magnetite particles are referred to, they mean either individual particles or their aggregates depending on the content.
[0040]
Magnetite particles having a high FeO content can be produced by an aqueous solution reaction which is a known method. Generally, a ferrous hydroxide slurry obtained by neutralizing and mixing a ferrous salt aqueous solution and an alkaline solution is used. Obtained by oxidation. The surface / internal FeO ratio of the magnetite particles obtained by such a known technique is about 0.3 to 0.6 as described in JP-A-2001-2426. (The surface near layer having a thickness equivalent to 3.5% of the particle radius described in this publication substantially corresponds to 10% by mass from the particle surface in terms of mass in the present invention.)
[0041]
On the other hand, the iron oxide particles used in the present invention have a surface / internal FeO ratio of 0.7 to 1, the FeO content near the particle surface is sufficiently high, the blackness is sufficiently high, and the surface Even if it is oxidized, it is not affected by the deterioration with time of blackness.
[0042]
When the surface / internal FeO ratio is less than 0.7, the amount of FeO in the vicinity of the surface particles cannot be said to be sufficient, and the blackness is low. It becomes magnetite particles with poor environmental properties. Further, when the surface / internal FeO ratio exceeds 1, although the blackness and the environmental resistance are excellent, even if FeO on the particle surface is increased more than necessary, the effect of the present invention cannot be further improved. The surface / internal FeO ratio is preferably 0.8 to 1 and more preferably 0.9 to 1 in consideration of further improving the degree of blackness and environmental resistance.
[0043]
It is important that the iron oxide particles used in the present invention contain titanium in the particles, and that the titanium element is contained in an amount of 0.3 to 1.5% by mass based on the total amount of the iron oxide particles. Features. In the present invention, it will be described later that the inclusion of titanium in the magnetite particles as iron oxide particles greatly contributes to making the surface / internal FeO ratio of the magnetite particles 0.7 to 1. If the titanium content is less than 0.3% by mass, the titanium content (A) in the vicinity of the particle surface tends to be small, and the surface / internal FeO ratio of the magnetite particles obtained by the aqueous solution reaction is 0.7 to 1. It will be difficult to do. On the other hand, if the titanium content in the iron oxide particles exceeds 1.5% by mass, the titanium content in the vicinity of the particle surface tends to be excessive, and the titanium content is too high, resulting in poor magnetic properties, blackness and hue. Etc., which may cause other characteristic defects, which is not preferable. The titanium content is preferably set to 0.4 to 1.2 mass% in order to minimize the titanium content and adjust the surface / internal FeO ratio so as not to decrease. More preferably, it is set to 0.8% by mass.
[0044]
In addition, the iron oxide particles used in the present invention preferably have an average particle diameter of 0.1 to 0.3 μm without any problem with respect to dispersibility, blackness and the like. Further, in order to further exhibit the characteristics of the iron oxide particles used in the present invention, the average particle diameter is preferably from 0.1 to 0.2 μm, more preferably from 0.1 to 0.15 μm. If the average particle size is less than 0.1 μm, dispersion failure due to re-aggregation of iron oxide in the toner may be caused, and even if the iron oxide particles for use in the present invention are used, blackness of the toner may be impaired. When the average particle diameter exceeds 0.3 μm, the blackness of the toner is satisfactory, but the dispersion in the toner particles may be deteriorated, which is not preferable.
[0045]
The iron oxide particles used in the present invention may have any shape such as spherical, hexahedral, and polyhedral shapes, but are preferably octahedral. This is because the magnetic iron oxide particles having such a shape are easy to separate from each other, have little cohesiveness, and can be uniformly dispersed in the binder resin. In addition, such iron oxide particles have irregularities on the particle surface, have many surfaces and ridges, and have an appropriate angle, so that they have excellent adhesion to the binder resin and physically have a magnetic toner surface. Since it is fixed above, it can be prevented from falling off the magnetic toner particles.
[0046]
The iron oxide particles used in the present invention preferably have a small total content of Al, Si, P, S, Cr, Mn, Co, Ni, Cu, Zn, and Mg. The above component is contained as an unavoidable component derived from a raw material during the production of magnetite particles, or is added to iron oxide particles by being added as a means for improving dispersibility or fluidity. In the iron oxide particles of the present invention, when controlling the surface / internal FeO ratio within the above range and maintaining high magnetic characteristics, the lower the total content of the above components, the more easily the effect is exhibited. As a specific content, the total content of the above elements is preferably 1% by mass or less of the whole iron oxide particles, and more preferably 0.8% by mass.
[0047]
The iron oxide particles used in the present invention have a L value of 20 or less, an a value of 0.1 or less, and a b value of 0 in a color difference meter in the measurement of blackness and hue of a powder according to JIS K5101-1991. .1 or less. If the L value exceeds 20, the a value exceeds 0.1, or the b value exceeds 0.1, blackness of a solid black image formed by the obtained magnetic toner may be impaired, which is not preferable. .
[0048]
The iron oxide particles according to the present invention have a coercive force of 1.6 to 12.0 kA / m and a saturation magnetization of 50 to 200 Am when 795.8 kA / m is applied. ² / Kg (preferably 50-100 Am ² / Kg), residual magnetization 2 to 20 Am ² / Kg is preferred.
[0049]
The content of the iron oxide particles used in the present invention in the toner particles is 50 to 150 parts by mass, preferably 60 to 120 parts by mass, based on 100 parts by mass of the binder resin. When the content of the iron oxide particles is less than 50 parts by mass, not only fogging occurs in the formed image or toner scattering occurs in the image forming apparatus, but also black when the magnetic black toner is used. The taste may be insufficient, which is not preferable. On the other hand, when the content of the iron oxide particles in the toner particles exceeds 150 parts by mass, it is not possible to sufficiently fly from the charging member (developing sleeve), which may cause a reduction in image density. Absent.
[0050]
Although the method for producing iron oxide particles used in the present invention does not have any particular problem even if a general method for producing magnetite particles is used, a particularly preferred production method will be specifically described below.
[0051]
The iron oxide particles for use in the present invention produce iron oxide particles by oxidizing a ferrous hydroxide slurry obtained by neutralizing and mixing a ferrous salt aqueous solution containing a titanium salt or a titanate and an alkaline solution. In the method, the pH of the aqueous ferrous salt solution is adjusted to 1.5 or less and the temperature to 70 ° C. or less so that the tetravalent titanium salt and / or titanate does not precipitate as titanium hydroxide. It can be produced by using a ferrous hydroxide slurry obtained by adding and mixing a titanium salt or a titanate to an aqueous ferrous salt solution.
[0052]
First, a titanium salt or a titanate is dissolved in an aqueous ferrous salt solution. What can be used as the ferrous salt is not particularly limited as long as it is a water-soluble salt such as ferrous sulfate and ferrous chloride. Examples of the titanium salt or a titanate that can be used for the addition include tetravalent titanium compounds such as titanium (IV) sulfate, titanium (IV) chloride, titanyl sulfate, and titanyl nitrate. The addition amount of the titanium salt and / or the titanate is adjusted to be 0.3 to 1.5% by mass in terms of titanium with respect to the final total amount of iron oxide particles.
[0053]
Here, what is important is to adjust the pH of the aqueous ferrous salt solution to 1.5 or lower and the temperature to 70 ° C or lower so that the tetravalent titanium salt and / or titanate does not precipitate as titanium hydroxide. Adding the above titanium salt or titanate to the aqueous ferrous salt solution and mixing.
[0054]
The reason for adjusting the pH of the ferrous salt aqueous solution at the time of adding the titanium salt or the titanate to 1.5 or less and the temperature to 70 ° C. or less is that the tetravalent titanium salt and / or titanate to be added is hydrolyzed. , To prevent precipitation as titanium hydroxide. By using this method, from the nucleation of the particles to the completion of the final particle growth, the tetravalent titanium component is uniformly contained in the iron oxide particles, and Fe ²⁺ The iron oxide particles which stably exist are generated.
[0055]
Next, the resulting ferrous salt aqueous solution containing a tetravalent titanium component and an alkaline solution are neutralized and mixed to generate a ferrous hydroxide slurry. As the alkali solution, an aqueous solution of an alkali hydroxide such as an aqueous solution of sodium hydroxide or potassium hydroxide can be used.
[0056]
The amount of the alkaline solution when producing the ferrous hydroxide slurry may be adjusted according to the shape of the iron oxide particles to be obtained. Specifically, spherical particles are obtained by adjusting the pH of the ferrous hydroxide slurry to be less than 8.0, and hexahedral particles are obtained by adjusting the pH to be 8.0 to 9.5. If it is adjusted so as to exceed 9.5, octahedral particles can be obtained.
[0057]
From the ferrous hydroxide slurry thus obtained, in order to obtain iron oxide particles, an oxidation reaction is performed while blowing an oxygen-containing gas, preferably air, into the slurry in a conventional manner, and the slurry after the oxidation reaction is subjected to a conventional method. , Filtration, washing, drying and pulverization.
[0058]
As described above, when iron oxide particles are generated by the aqueous solution reaction, by adding a titanium salt or a titanate to the ferrous salt aqueous solution under predetermined conditions, Fe particles can also be present on the particle surface. ²⁺ Can be stably present, and iron oxide particles having a surface / internal FeO ratio of 0.7 to 1 can be obtained.
[0059]
[Binder resin used in magnetic toner of the present invention]
The binder resin used in the magnetic toner of the present invention contains at least a polyester resin containing a polyester monomer unit and a vinyl resin containing a vinyl monomer unit, but the polyester monomer unit and the vinyl monomer unit partially reacted. It is particularly preferable to further contain a hybrid resin component in terms of chargeability, fixability, and storage stability. In the hybrid resin, two kinds of resins having originally poor compatibility are uniformly dispersed, so that the characteristics of both resins can be utilized.
[0060]
In the present invention, “polyester monomer unit” represents a repeating unit constituting a polyester resin, and “vinyl monomer unit” represents a repeating unit constituting a vinyl resin. Further, the “hybrid resin component” means a resin containing a polyester resin and a vinyl-based resin and having a portion in which the polyester-based monomer unit and the vinyl-based monomer unit are chemically bonded. Specifically, a polyester-based monomer unit and a vinyl-based monomer unit having a carboxylic acid ester group such as a (meth) acrylate ester are formed by a transesterification reaction.
[0061]
From the viewpoint of fixability, it is possible to obtain a magnetic toner that utilizes the advantages of both a sharp melt of a polyester resin and an advantage in low-temperature fixability, and the advantages of a vinyl-based resin in high-temperature offset resistance and blocking resistance. . Further, from the viewpoint of chargeability, both the point that the chargeability of the polyester resin is high and the rise is fast and the point that the chargeability of the vinyl resin is stable are utilized. Furthermore, since the hybrid resin has excellent compatibility with other internal additives such as wax, it is possible to obtain a magnetic toner which has a uniform charge amount distribution and can form a good image without a decrease in density and no fog.
[0062]
In the binder resin used in the present invention, the mass ratio between the polyester monomer unit and the vinyl monomer unit is 50/50 to 90/10. In consideration of the dispersion of the iron oxide particles in the binder resin, when the iron oxide particles have a small particle diameter, the specific surface area increases, so that the influence of the surface properties on the dispersion state in the resin increases. . The iron oxide particles of the present invention are considered to have a more non-polar surface because the FeO content near the surface is relatively higher than that of conventionally known iron oxide particles. Therefore, it is desirable that a highly polar polyester resin is mixed as a binder resin in an appropriate ratio with respect to the vinyl resin. Therefore, by setting the content ratio between the polyester-based monomer unit and the vinyl-based monomer unit within the above range, the affinity between the resin and the iron oxide particle surface can be increased, and the surface of the iron oxide particle can be efficiently treated with the binder resin. Can be covered. Then, the magnetic attraction between the iron oxide particles can be reduced by the steric hindrance effect, so that the dispersed state can be more stably maintained. In order to exhibit the effect of uniformly dispersing the iron oxide particles in the binder resin, the mass ratio between the polyester-based monomer unit and the vinyl-based monomer unit is preferably 60/40 to 85/15.
[0063]
Further, when the binder resin of the present invention contains a hybrid resin component in which both the polyester resin and the vinyl resin partially react, as described above, not only is excellent in charge stability and fixing property, storage stability, but also Since the viscosity of the binder resin can be easily controlled, the dispersibility of the iron oxide particles is particularly preferable. As a result, excellent dispersibility from a microscopic viewpoint of iron oxide particles can be achieved, and it is expected that extremely excellent durability stability can be expected even when the magnetic toner has a smaller particle size and a more spherical shape. Can be
[0064]
The polyester resin used in the present invention is obtained by condensation polymerization of an alcohol component and an acid component such as carboxylic acid or carboxylic anhydride or carboxylic acid ester. Examples of the polyester-based monomer constituting the polyester resin include the following.
[0065]
The alcohol component is not particularly limited as long as it is a dihydric or higher alcohol. Ethylene glycol, propylene glycol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, diethylene glycol, triethylene Glycol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, 2-ethyl-1,3-hexanediol, bisphenol A hydride, bisphenol derivative represented by the following formula (1-1) And diols represented by the following formula (1-2).
[0066]
Embedded image

[0067]
Embedded image

[0068]
As the acid component, phthalic acid, terephthalic acid, isophthalic acid, benzenedicarboxylic acids such as phthalic anhydride or anhydrides thereof; succinic acid, adipic acid, sebacic acid, alkyldicarboxylic acids such as azelaic acid or anhydrides thereof, and furthermore Examples include succinic acid or an anhydride thereof substituted with an alkyl group or an alkenyl group having 6 to 18 carbon atoms; unsaturated dicarboxylic acids such as fumaric acid, maleic acid, citraconic acid, and itaconic acid, and anhydrides thereof.
[0069]
Further, the polyester resin used in the present invention is preferably a polyester resin containing a trivalent or higher polyhydric carboxylic acid or an anhydride thereof and / or a trivalent or higher polyhydric alcohol because the molecular weight and viscosity can be further controlled. Examples of the trivalent or higher polyvalent carboxylic acid or its anhydride include 1,2,4-benzenetricarboxylic acid, 1,2,4-cyclohexanetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, and pyromellitic acid And trihydric or higher polyhydric alcohols such as 1,2,3-propanetriol, trimethylolpropane, hexanetriol, and pentaerythritol. In the binder resin of the present invention, an aromatic alcohol having high stability due to environmental fluctuation is particularly preferable, and examples thereof include 1,2,4-benzenetricarboxylic acid and anhydrides thereof.
[0070]
Examples of the vinyl-based monomer for producing the vinyl-based resin include the following.
[0071]
Styrene; o-methylstyrene, m-methylstyrene, p-methylstyrene, p-methoxystyrene, p-phenylstyrene, p-chlorostyrene, 3,4-dichlorostyrene, p-ethylstyrene, 2,4-dimethyl Styrene, p-n-butylstyrene, p-tert-butylstyrene, p-n-hexylstyrene, p-n-octylstyrene, p-n-nonylstyrene, p-n-decylstyrene, p-n-dodecylstyrene, etc. Styrene and its derivatives; styrene unsaturated monoolefins such as ethylene, propylene, butylene and isobutylene; unsaturated polyenes such as butadiene and isoprene; vinyl halides such as vinyl chloride, vinylidene chloride, vinyl bromide and vinyl fluoride And vinyl acetate, vinyl propionate, vinyl benzoate Vinyl esters of methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, phenyl methacrylate Α-methylene aliphatic monocarboxylic esters such as dimethylaminoethyl methacrylate and diethylaminoethyl methacrylate; methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, propyl acrylate, n-octyl acrylate Acrylates such as acrylamide, dodecyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, 2-chloroethyl acrylate, phenyl acrylate; vinyl methyl ether, vinyl acetate Vinyl ethers such as ethyl ether and vinyl isobutyl ether; vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone and methyl isopropenyl ketone; N-vinyl pyrrole, N-vinyl carbazole, N-vinyl indole, N-vinyl pyrrolidone and the like N-vinyl compounds; vinyl naphthalenes; acrylic acid or methacrylic acid derivatives such as acrylonitrile, methacrylonitrile, and acrylamide.
[0072]
Also, unsaturated dibasic acids such as maleic acid, citraconic acid, itaconic acid, alkenyl succinic acid, fumaric acid, mesaconic acid; maleic anhydride, citraconic anhydride, itaconic anhydride, alkenyl succinic anhydride, etc. Unsaturated dibasic acid anhydrides: methyl maleate half ester, maleic acid ethyl half ester, maleic acid butyl half ester, citraconic acid methyl half ester, citraconic acid half ester, citraconic acid butyl half ester, itaconic acid methyl half ester, Half esters of unsaturated dibasic acids such as methyl alkenyl succinate half ester, methyl half fumarate ester and methyl half ester mesaconate; unsaturated dibasic acid esters such as dimethyl maleic acid and dimethyl fumaric acid; acrylic acid, methacrylic acid Α, β-unsaturated acids such as sulfonic acid, crotonic acid and cinnamic acid; α, β-unsaturated acid anhydrides such as crotonic anhydride and cinnamic anhydride; the α, β-unsaturated acids and lower fatty acids And monomers having a carboxyl group such as alkenyl malonic acid, alkenyl glutaric acid, alkenyl adipic acid, acid anhydrides and monoesters thereof.
[0073]
Further, acrylic acid or methacrylic acid esters such as 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate and 2-hydroxypropyl methacrylate; 4- (1-hydroxy-1-methylbutyl) styrene, 4- (1-hydroxy-1) And a monomer having a hydroxy group such as (-methylhexyl) styrene. Each of the above monomers can be used alone or in combination of two or more.
[0074]
In the magnetic toner of the present invention, the vinyl resin contained in the binder resin may have a crosslinked structure crosslinked by a crosslinking agent having two or more vinyl groups. Examples of the crosslinking agent having a vinyl group include aromatic divinyl compounds such as divinylbenzene and divinylnaphthalene; and diacrylate compounds linked by an alkyl chain such as ethylene glycol diacrylate and 1,3-butylene glycol divinyl compound. Acrylates, 1,4-butanediol diacrylate, 1,5-pentanediol acrylate, 1,6-hexanediol diacrylate, neopentyl glycol diacrylate, and those obtained by replacing the acrylate of the above compound with methacrylate Di-linked by alkyl chains containing ether linkages Examples of the acrylate compounds include diethylene glycol diacrylate, triethylene glycol diacrylate, tetraethylene glycol diacrylate, polyethylene glycol # 400 diacrylate, polyethylene glycol # 600 diacrylate, dipropylene glycol diacrylate, and acrylates of the above compounds. For example, polyoxyethylene (2) -2,2-bis (4-hydroxyphenyl) as diacrylate compounds cross-linked by a chain containing an aromatic group and an ether bond. Propane diacrylate, polyoxyethylene (4) -2,2-bis (4-hydroxyphenyl) propane diacrylate, and methacrylate instead of the above compound acrylate It can be mentioned; as, for example, polyester type diacrylate compounds, include trade name MANDA (Nippon Kayaku) is.
[0075]
Examples of the multifunctional crosslinking agent include pentaerythritol triacrylate, trimethylolethane triacrylate, trimethylolpropane triacrylate, tetramethylolmethanetetraacrylate, oligoester acrylate, and those obtained by replacing the acrylate of the above compound with methacrylate; Allyl cyanurate, triallyl trimellitate;
[0076]
These crosslinking agents can be used in an amount of 0.01 to 10 parts by mass (more preferably 0.03 to 5 parts by mass) based on 100 parts by mass of the other vinyl monomer.
[0077]
Among these crosslinkable monomers, those which are preferably used as a binder resin from the viewpoint of fixing properties and anti-offset properties include aromatic divinyl compounds (particularly divinylbenzene), which are linked by a chain containing an aromatic group and an ether bond. Diacrylate compounds.
[0078]
Examples of the polymerization initiator used for producing the vinyl resin in the present invention include 2,2′-azobisisobutyronitrile and 2,2′-azobis (4-methoxy-2,4-dimethylvalero). Nitrile), 2,2'-azobis (-2,4-dimethylvaleronitrile), 2,2'-azobis (-2methylbutyronitrile), dimethyl-2,2'-azobisisobutyrate, 1'-azobis (1-cyclohexanecarbonitrile), 2- (carbamoylazo) -isobutyronitrile, 2,2'-azobis (2,4,4-trimethylpentane), 2-phenylazo-2,4-dimethyl- 4-methoxyvaleronitrile, 2,2-azobis (2-methylpropane), methyl ethyl ketone peroxide, acetylacetone peroxide, cyclohexanone Ketone peroxides such as peroxide, 2,2-bis (t-butylperoxy) butane, t-butyl hydroperoxide, cumene hydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide, Di-t-butyl peroxide, t-butylcumyl peroxide, dicumyl peroxide, α, α′-bis (t-butylperoxyisopropyl) benzene, isobutyl peroxide, octanoyl peroxide, decanoyl peroxide, Lauroyl peroxide, 3,5,5-trimethylhexanoyl peroxide, benzoyl peroxide, m-trioil peroxide, di-isopropylperoxydicarbonate, di-2-ethylhexylperoxydicarbonate, di-n-propyl Pilperoxydicarbonate, di-2-ethoxyethylperoxycarbonate, dimethoxyisopropylperoxydicarbonate, di (3-methyl-3-methoxybutyl) peroxycarbonate, acetylcyclohexylsulfonyl peroxide, t-butylperoxyacetate T-butyl peroxyisobutyrate, t-butyl peroxy neodecanoate, t-butyl peroxy-2-ethylhexanoate, t-butyl peroxy laurate, t-butyl peroxobenzoate, t -Butylperoxyisopropyl carbonate, di-t-butylperoxyisophthalate, t-butylperoxyallylcarbonate, t-amylperoxy-2-ethylhexanoate, di-t-butylperoxyhexahydrote Examples include phthalate and di-t-butylperoxyazelate.
[0079]
In the present invention, it is preferable that the components constituting the vinyl resin and / or the polyester resin include a monomer component capable of reacting with both resin components. Among the monomers constituting the polyester resin, those which can react with the vinyl resin include, for example, unsaturated dicarboxylic acids such as phthalic acid, maleic acid, citraconic acid, itaconic acid and anhydrides thereof. Among the monomers constituting the vinyl resin, those which can react with the polyester resin component include those having a carboxyl group or a hydroxy group, and acrylic acid or methacrylic acid esters.
[0080]
As a method for obtaining a hybrid resin obtained by partially reacting a vinyl resin and a polyester resin, where a polymer containing a monomer component capable of reacting with each of the above-mentioned vinyl resin and polyester resin is present, A method obtained by polymerizing one or both resins is preferred.
[0081]
In this hybrid resin, the copolymerization ratio between the polyester monomer unit and the vinyl monomer unit is preferably from 50/50 to 90/10, more preferably from 60/40 to 85/15 by mass ratio. . When the content of the polyester-based monomer unit is less than 50%, not only the low-temperature fixability is impaired, but when it exceeds 90%, the high-temperature offset resistance is deteriorated and the pulverizability may be adversely affected. In addition, if the content of the polyester-based monomer unit is less than 50% or more than 90%, it is difficult to achieve good dispersibility of the iron oxide particles in the binder resin for the above-described reason.
[0082]
Further, the above-mentioned binder resins may be used alone, or two or more kinds of binder resins having different softening points may be used in combination. Such a system is preferable because the molecular weight distribution of the magnetic toner can be designed relatively easily and a wide fixing area can be provided.
[0083]
The “softening point” of the binder resin refers to a value measured by a descending flow tester in accordance with a measuring method described in “JIS K 7210”. A specific measuring method will be described below.
[0084]
1cm using descending flow tester (manufactured by Shimadzu Corporation) ³ While heating the sample resin at a heating rate of 6 ° C./min, 1960 N / m ² (20kg / cm ² The sample resin is extruded from a nozzle having a diameter of 1 mm and a length of 1 mm by applying a load of (1). Thus, a plunger descent (flow value) -temperature curve is drawn, and when the height of the S-shaped curve is h, the temperature corresponding to h / 2 (the temperature at which half of the sample resin flows out) is set to the softening point. And
[0085]
[Magnetic toner of the present invention]
Hereinafter, the magnetic toner of the present invention containing the above-described magnetic substance and binder resin will be described. The magnetic toner of the present invention has toner particles containing at least the binder resin and the magnetic substance, and inorganic fine powder present on the surface of the toner particles.
[0086]
In order to further stabilize the chargeability of the toner particles constituting the magnetic toner of the present invention, in addition to the binder resin and the magnetic material described above, one or more charge control agents may be used, if necessary. May be contained in combination. The charge control agent is preferably used in an amount of 0.1 to 10 parts by mass, more preferably 0.1 to 5 parts by mass, per 100 parts by mass of the binder resin.
[0087]
As the charge control agent, a known charge control agent which is conventionally contained in a toner can be used, and is not particularly limited. Examples thereof include the following.
[0088]
For example, an organometallic complex or a chelate compound is effective as a negative charge controlling agent for controlling the magnetic toner to negative charge. Examples thereof include a monoazo metal complex, a metal complex of an aromatic hydroxycarboxylic acid, and a metal complex of an aromatic dicarboxylic acid. Other examples include aromatic hydroxycarboxylic acids, aromatic mono- and polycarboxylic acids and metal salts thereof, anhydrides thereof, esters thereof, and phenol derivatives of bisphenol.
[0089]
Examples of the positive charge controlling agent for controlling the toner to be positively charged include denaturation products such as nigrosine and fatty acid metal salts, and tributylbenzylammonium-1-hydroxy-4-naphthosulfonate and tetrabutylammonium tetrafluoroborate. Onium salts such as quaternary ammonium salts and phosphonium salts, which are analogs thereof, and triphenylmethane dyes and these lake pigments as chelating pigments thereof (phosphor tungstic acid, phosphomolybdic acid, phosphorous tungsten Molybdic acid, tannic acid, lauric acid, gallic acid, ferricyanic acid, ferrocyanide compound, etc., and as metal salts of higher fatty acids, diorganotin oxides such as dibutyltin oxide, dioctyltin oxide, dicyclohexyltin oxide and dibutyltin oxide , Dioctyl tin borate include diorgano tin borate such as dicyclohexyl tin borate.
[0090]
Further, the toner particles used in the present invention may further contain a wax. As the wax, a known wax conventionally used in a toner can be used, and it is not particularly limited, but from the viewpoint of easy dispersibility in a magnetic toner and high releasability, low molecular weight polyethylene, low molecular weight polypropylene, Hydrocarbon waxes such as microcrystalline wax and paraffin wax are preferably used. If necessary, one or more of the waxes exemplified below may be used in a small amount.
[0091]
Oxides of aliphatic hydrocarbon waxes such as oxidized polyethylene wax, or block copolymers thereof; waxes mainly containing fatty acid esters such as carnauba wax, sasol wax, montanic acid ester wax; and deoxidized carnauba Examples thereof include those obtained by partially or entirely deoxidizing fatty acid esters such as wax.
[0092]
Furthermore, saturated straight-chain fatty acids such as palmitic acid, stearic acid and montanic acid; unsaturated fatty acids such as pracidic acid, eleostearic acid, and vinaric acid; , Alcohols such as sorbitol; fatty acid amides such as linoleic acid amide, oleic acid amide, lauric acid amide; methylenebisstearic acid amide, ethylenebiscaprin Saturated fatty acid bisamides such as acid amide, ethylenebislauric acid amide, hexamethylenebisstearic acid amide; ethylenebisoleic acid amide, hexamethylenebisoleic acid amide, N, N'-dioleylurea Unsaturated fatty acid amides such as dipinamide and N, N-dioleyl sebacamide; aromatic bisamides such as m-xylene bisstearic acid amide and N, N-distearylisophthalic acid amide; calcium stearate and laurate Fatty acid metal salts such as calcium phosphate, zinc stearate, and magnesium stearate (commonly referred to as metal soaps), and grafted onto aliphatic hydrocarbon waxes with vinyl monomers such as styrene and acrylic acid Waxes; partial esterified products of fatty acids such as behenic acid monoglyceride and polyhydric alcohols, and methyl ester compounds having a hydroxyl group obtained by hydrogenation of vegetable oils and the like.
[0093]
Further, the melting point of the wax specified by the maximum endothermic peak temperature at the time of temperature rise measured by a differential scanning calorimeter (DSC) is preferably 70 to 140 ° C. More preferably, it is 90 to 135 ° C. When the melting point of the wax is 70 ° C. or less, the viscosity of the toner decreases, and the toner tends to adhere to the photosensitive member. When the melting point is 140 ° C. or more, the low-temperature fixability deteriorates.
[0094]
The “melting point” of the wax can be determined by using a differential scanning calorimeter (DSC measuring device) and DSC-7 (manufactured by PerkinElmer) in accordance with ASTM D3418-82.
[0095]
Upon measurement, a measurement sample is precisely weighed in an amount of 5 to 20 mg, preferably 10 mg. This is put in an aluminum pan, and an empty aluminum pan is used as a reference, and measurement is performed at a temperature rising rate of 10 ° C./min under normal temperature and normal humidity within a measurement temperature range of 30 to 200 ° C. Since the maximum endothermic peak is obtained in the temperature range of 40 to 100 ° C. in the second heating process, the temperature of the maximum endothermic peak is used as the melting point of the wax.
[0096]
The amount of the wax is preferably 0.1 to 20 parts by mass, more preferably 0.5 to 10 parts by mass per 100 parts by mass of the binder resin.
[0097]
These waxes are bound by dissolving the resin in a solvent during the production of the binder resin, increasing the temperature of the resin solution, and adding and mixing while stirring, or by adding at the time of melt-kneading during the production of the magnetic toner. It can be mixed with resin.
[0098]
Further, in the magnetic toner of the present invention, an inorganic fine powder is externally added to the toner particles in order to improve fluidity, and is present on the surface of the toner particles. The inorganic fine powder used in the present invention includes, for example, fluorine resin powder such as vinylidene fluoride fine powder and polytetrafluoroethylene fine powder; fine powder silica such as wet-process silica and dry process silica; fine powder titanium oxide; Finely divided alumina; silane coupling agent, titanium coupling agent, treated silica surface-treated with silicone oil or the like, treated titanium oxide, treated alumina, and the like.
[0099]
Preferred inorganic fine powders are fine powders produced by the vapor phase oxidation of silicon halide compounds, and are referred to as dry silica or fumed silica. For example, it utilizes the thermal decomposition oxidation reaction of silicon tetrachloride gas in oxygen and hydrogen, and the basic reaction formula is as follows.
[0100]
Embedded image
SiCl ₄ + 2H ₂ + O ₂ → SiO ₂ +4 HCl
In this production process, it is also possible to obtain a composite fine powder of silica and another metal oxide by using another metal halide compound such as aluminum chloride or titanium chloride together with the silicon halide compound. The particle size is preferably in the range of 0.001 to 2 μm as an average primary particle size, and particularly preferably, silica fine powder in the range of 0.002 to 0.2 μm is used. .
[0101]
Commercially available fine silica powder produced by vapor phase oxidation of a silicon halide compound includes, for example, those commercially available under the following trade names.
[0102]

Further, it is more preferable to use a treated silica fine powder obtained by subjecting a silica fine powder generated by vapor-phase oxidation of the silicon halide to a hydrophobic treatment. It is particularly preferable that the treated silica fine powder is obtained by treating the silica fine powder such that the degree of hydrophobicity measured by a methanol titration test shows a value in the range of 30 to 80.
[0103]
The method for imparting hydrophobicity is provided by chemically treating with an organosilicon compound and / or silicone oil that reacts or physically adsorbs with the silica fine powder. As a preferred method, silica fine powder generated by vapor phase oxidation of a silicon halide is treated with an organosilicon compound.
[0104]
As organic silicon compounds, hexamethyldisilazane, trimethylsilane, trimethylchlorosilane, trimethylethoxysilane, dimethyldichlorosilane, methyltrichlorosilane, allyldimethylchlorosilane, allylphenyldichlorosilane, benzyldimethylchlorosilane, bromomethyldimethyl Chlorosilane, α-chloroethyltrichlorosilane, β-chloroethyltrichlorosilane, chloromethyldimethylchlorosilane, triorganosilylmercaptan, trimethylsilylmercaptan, triorganosilyl acrylate, vinyldimethylacetoxysilane, dimethylethoxysilane, dimethyldimethoxysilane, diphenyl Diethoxysilane, hexamethyldisiloxane, 1,3-divinyltetramethyldisiloxane, 1,3 -Diphenyltetramethyldisiloxane and dimethylpolysiloxane having from 2 to 12 siloxane units per molecule and containing hydroxyl groups bonded to Si, each of which is located at one of the terminal units. These may be used alone or as a mixture of two or more.
[0105]
Aminopropyltrimethoxysilane having a nitrogen atom, aminopropyltriethoxysilane, dimethylaminopropyltrimethoxysilane, diethylaminopropyltrimethoxysilane, dipropylaminopropyltrimethoxysilane, dibutylaminopropyltrimethoxysilane, monobutylaminopropyltrimethoxy Silanes such as silane, dioctylaminopropyldimethoxysilane, dibutylaminopropyldimethoxysilane, dibutylaminopropylmonomethoxysilane, dimethylaminophenyltriethoxysilane, trimethoxysilyl-γ-propylphenylamine, and trimethoxysilyl-γ-propylbenzylamine Coupling agents may be used alone or in combination. Preferred silane coupling agents include hexamethyldisilazane (HMDS).
[0106]
As the preferred silicone oil used in the present invention, those having a viscosity at 25 ° C of 0.5 to 10000 centistokes, preferably 1 to 1000 centistokes, more preferably 10 to 200 centistokes, for example, dimethyl silicone oil, Methylphenyl silicone oil, α-methylstyrene-modified silicone oil, chlorophenyl silicone oil, and fluorine-modified silicone oil are particularly preferred. As a method of the silicone oil treatment, for example, a method in which silica fine powder treated with a silane coupling agent and silicone oil are directly mixed using a mixer such as a Henschel mixer; Or a method of dissolving or dispersing silicone oil in an appropriate solvent, adding silica fine powder, mixing and removing the solvent.
[0107]
The silica treated with the silicone oil is more preferably heated to 200 ° C. or more (more preferably 250 ° C. or more) in an inert gas after the treatment with the silicone oil to stabilize the surface coat.
[0108]
In the present invention, it is preferable that silica is treated with a coupling agent and then treated with silicone oil, or silica is treated with a coupling agent and silicone oil at the same time.
[0109]
The inorganic fine powder used in the present invention has a specific surface area of 30 m by nitrogen adsorption measured by the BET method. ² / G or more, preferably 50 m ² / G gives good results. It is preferable to use 0.01 to 8 parts by mass, preferably 0.1 to 4 parts by mass of an inorganic fine powder for improving fluidity with respect to 100 parts by mass of the toner particles.
[0110]
In the magnetic toner of the present invention, an inorganic fine powder other than the above (inorganic fine powder for improving the fluidity) may be used alone or as a cleaning aid for the purpose of imparting a polishing effect, chargeability and fluidity, or It can be used in combination with the above-mentioned inorganic fine powder. The inorganic fine powder having such a polishing effect is added to the toner particles and is present on the surface of the toner particles, so that the effect can be increased more than before and after the addition, and is not particularly limited. Examples of the inorganic fine powder having a polishing effect used in the present invention include titanates and / or silicates such as magnesium, zinc, cobalt, manganese, strontium, cerium, calcium, and barium.
[0111]
In particular, strontium titanate (SrTiO.sub.2) can be more effectively used in the present invention. ₃ ) And calcium titanate (CaTiO ₃ ), Strontium silicate (SrSiO ₃ ), Barium titanate (BaTiO) ₃ Is preferred.
[0112]
The inorganic fine powder used in the present invention is preferably produced by, for example, a sintering method, mechanically pulverized, and then subjected to air classification to have a desired particle size distribution.
[0113]
In the present invention, the inorganic fine powder having a polishing effect is used in an amount of 0.1 to 10 parts by mass, preferably 0.2 to 8 parts by mass, based on 100 parts by mass of the toner.
[0114]
The magnetic toner of the present invention has toner particles containing at least a specific binder resin and a specific magnetic substance as described above, and inorganic fine powder present on the surface of the toner particles.
[0115]
The magnetic toner of the present invention has a weight average particle diameter of 5 to 12 μm. The weight average particle diameter of the magnetic toner is preferably 5 to 11 μm, and more preferably 5.5 to 10 μm. Further, when producing a magnetic toner having a specific circularity, the number of particles having a particle diameter of 4.0 μm or less is 40% by number or less, and the number of particles having a particle diameter of 10.1 μm or more is 25% by volume or less. Is done.
[0116]
In the case of a magnetic toner having a weight average particle diameter exceeding 12 μm, there is a problem in terms of high image quality due to the size of the toner particle diameter itself, which is not preferable. In the case of a magnetic toner having a weight average particle diameter of less than 5 μm, the balance between the circularity of the toner and the dispersion state of the iron oxide particles cannot be sufficiently achieved, and fog and scattering may be deteriorated, which is not preferable. The same applies to the case where the ratio of particles having a particle diameter of 4.0 μm or less exceeds 40% by number and the case where the ratio of particles having a particle diameter of 10.1 μm or more exceeds 25% by volume.
[0117]
Further, in the magnetic toner of the present invention, it is preferable that the a and b values in the color tone measurement of a solid black image having a transmission density of 1.2 to 1.7 satisfy the relations of the following equations (2) and (3).
[0118]
[Equation 3]
0 ≦ a value ≦ 0.5 (2)
−0.5 ≦ b value ≦ 0.8 (3)
(However, the average particle diameter of the iron oxide particles is in the range of 0.1 to 0.3 μm.)
The value a is more preferably 0 to 0.45, and the value b is more preferably -0.5 to 0.7.
[0119]
The magnetic toner of the present invention has the following formula (4) for particles having a particle diameter of 3 μm or more.
[0120]
(Equation 4)
Circularity a = L ₀ / L (4)
[Where L ₀ Represents the perimeter of a circle having the same projected area as the particle image, and L represents the perimeter of the particle image. ]
In the distribution of the circularity (a) obtained from the above, particles having a circularity (a) of 0.900 or more have a cumulative value on a number basis of 90% or more, and the average value of the circularity (a) is 0. It is preferably 94 or more. Although the details will be described later, the effect of the present invention is maximized by making the circularity distribution of the magnetic toner of the present invention containing the specific binder resin and the specific iron oxide particles as described above as described above. Be demonstrated.
[0121]
When the cumulative value based on the number of particles having a circularity (a) of 0.900 or more in the circularity distribution of the magnetic toner is less than 90%, the contact area between the toner particles and the photoconductor becomes large, Since the adhesion of the particles to the photosensitive member increases, sufficient transfer efficiency cannot be obtained, which is not preferable.
[0122]
Further, in the magnetic toner of the present invention, if the weight average particle diameter and the circularity are in the above ranges, there is no problem in control of transfer efficiency and charging, but the same effect is constantly provided for toners having different particle diameters. For this purpose, it is more preferable to define more detailed circularity as described below.
[0123]
That is, the magnetic toner of the present invention preferably further satisfies any of the following (I) or (II).
[0124]
(I) The relationship between the weight average particle diameter (X) and the cut ratio (Z) is expressed by the following formula (5).
[0125]
(Equation 5)
Z ≦ 5.3 × X (5)
(More preferably, 0 <Z ≦ 5.3 × X (5 ′))
In the circularity distribution, the relationship between the number-based cumulative value (Y) of particles having a circularity (a) of 0.950 or more and the weight average particle diameter (X) of the magnetic toner is represented by the following formula ( 6)
[0126]
(Equation 6)
Y ≧ exp5.51 × X−0.645 (6)
To be satisfied.
[0127]
(II) The relationship between the weight average particle diameter (X) and the cut ratio (Z) is expressed by the following equation (7).
[0128]
(Equation 7)
Z> 5.3 × X (7)
(More preferably, 95>Z> 5.3 × X (7 ′))
In the circularity distribution, the relationship between the number-based cumulative value (Y) of particles having a circularity (a) of 0.950 or more and the weight average particle diameter (X) of the magnetic toner is represented by the following formula ( 8)
[0129]
(Equation 8)
Y ≧ exp 5.37 × X−0.545 (8)
To be satisfied.
[0130]
In the present invention, the cut ratio (Z) of the magnetic toner is represented by A (number / number) of the particle concentration of all the measured particles measured by the following method using a flow particle image analyzer FPIA-1000 manufactured by Toa Medical Electronics. μl), and B (number / μl) is the concentration of the measured particles having an equivalent circle diameter of 3 μm or more, and is represented by the following equation (9).
[0131]
(Equation 9)
Z = (1−B / A) × 100 (9)
When none of the above (I) and (II) is satisfied, that is, when the above equation (5) is satisfied and the above equation (6) is not satisfied, or when the above equation (7) is satisfied and the above equation (8) is not satisfied In this case, the adhesion of the magnetic toner to the fixing member or the like is easily promoted, the fluidity of the toner may be deteriorated, and the transfer efficiency may be reduced.
[0132]
As one measure for evaluating the variation of particles having each circularity, the circularity standard deviation SD can be used. In the present invention, there is no problem if the standard deviation SD is 0.030 to 0.050.
[0133]
The average circularity in the present invention is used as a simple method for quantitatively expressing the shape of the particles. In the present invention, the particle size of each particle is measured using a flow particle image analyzer FPIA-1000 manufactured by Toa Medical Electronics. The projected area and perimeter of the image are measured. From the measurement results, the circularity (a) of the particles is determined by the above equation (4). Further, as represented by the following equation (10), the value obtained by dividing the total sum of the measured circularities (a) of all the particles by the total number of particles is defined as the average circularity.
[0134]
(Equation 10)

[0135]
The circularity standard deviation SD is obtained by calculating the average circularity obtained from the above equations (4) and (10) by a _m , The circularity of each particle is a _i When the number of particles to be measured is m, it is calculated from the following equation.
[0136]
[Equation 11]

[0137]
The circularity in the present invention is an index of the degree of unevenness of the toner particles, and is 1.00 when the toner is perfectly spherical, and the circularity becomes smaller as the surface shape becomes more complicated. Further, the SD of the circularity distribution in the present invention is an index of variation, and a smaller numerical value indicates a sharper distribution.
[0138]
In addition, "FPIA-1000" which is a measuring device used in the present invention calculates the circularity of each particle, and then calculates the average circularity and the circularity standard deviation. The degree 0.4 to 1.0 is divided into 61 divided classes, and a calculation method of calculating the average circularity and the circularity standard deviation using the center value and frequency of the division points is used. However, each value of the average circularity and circularity standard deviation calculated by this calculation method, and each value of the average circularity and circularity standard deviation calculated by the above-described calculation formula directly using the circularity of each particle, Is very small and practically negligible. In the present invention, the circular shape of each particle described above is used for data handling reasons such as shortening of calculation time and simplification of calculation formula. Such a calculation method partially modified using the concept of a calculation formula using the degree directly may be used.
[0139]
As a specific measurement method, 0.1 to 0.5 ml of a surfactant, preferably an alkylbenzene sulfonate, is added as a dispersant to 100 to 150 ml of water from which impurities have been removed in a container. Add about 1 to 0.5 g. The suspension in which the sample was dispersed was subjected to a dispersion treatment for about 1 to 3 minutes with an ultrasonic disperser, and the concentration of the dispersion was adjusted to 1.2 to 20 thousand / μl, and the above-mentioned flow type particle image measuring apparatus was used. The circularity distribution of particles having an equivalent circle diameter of 0.60 μm or more and less than 159.21 μm is measured. In addition, by setting the concentration of the dispersion liquid to 12 to 20 thousand particles / μl, it is possible to maintain the particle concentration enough to maintain the accuracy of the apparatus even when the cut rate increases.
[0140]
The outline of the measurement is described in the catalog of FPIA-1000 (June 1995 version) issued by Toa Medical Electronics Co., Ltd., the operation manual of the measuring device, and JP-A-8-136439. It is.
[0141]
The sample dispersion liquid is passed through a flow path (spread along the flow direction) of a flat and flat transparent flow cell (thickness: about 200 μm). The strobe and the CCD camera are mounted on the flow cell so as to be positioned on opposite sides of the flow cell so as to form an optical path that intersects with the thickness of the flow cell. While the sample dispersion is flowing, strobe light is applied at 1/30 second intervals to obtain an image of the particles flowing through the flow cell, so that each particle has a range parallel to the flow cell Photographed as a two-dimensional image. The diameter of a circle having the same area is calculated as the equivalent circle diameter from the area of the two-dimensional image of each particle. The circularity of each particle is calculated from the projected area of the two-dimensional image of each particle and the perimeter of the projected image using the above-described circularity calculation formula.
[0142]
The particle size distribution of the magnetic toner can be measured by various methods. In the present invention, the particle size distribution is measured using a Coulter counter multisizer.
[0143]
As a measuring device, a Coulter counter Multisizer II (manufactured by Coulter) was used, and an interface (manufactured by Nikkaki) for outputting the number distribution and volume distribution and a CX-1 personal computer (manufactured by Canon) were connected. Prepare a 1% NaCl aqueous solution using special grade or primary grade sodium chloride. In the measurement, first, 0.1 to 5 ml of a surfactant (preferably an alkylbenzene sulfonate) is added as a dispersant to 100 to 150 ml of the electrolytic aqueous solution, and 2 to 20 mg of a measurement sample is further added. The electrolytic solution in which the sample was suspended was subjected to dispersion treatment for about 1 to 3 minutes using an ultrasonic disperser, and a multi-sizer type II of the Coulter counter was used. When measuring the particle size of the fine powder, use a 13 μm aperture. The volume and the number of the toner and the inorganic fine powder are measured, and the volume distribution and the number distribution are calculated. From this, the weight-based weight average particle diameter (D4) obtained from the volume distribution can be obtained.
[0144]
The magnetic toner of the present invention can be manufactured using a general toner manufacturing apparatus, and the manufacturing method is not particularly limited, but a manufacturing method capable of easily controlling the circularity and the particle diameter to the above-described desired ranges is particularly preferable. preferable.
[0145]
Specific examples include adding a binder resin and a magnetic substance and, if necessary, a charge controlling agent and a releasing agent as other additives, dry-mixing with a mixer such as a Henschel mixer or a ball mill, and kneading the mixture. The mixture is melted and kneaded using a hot kneader such as a roll mill or an extruder to make the resins compatible with each other to obtain a melt-kneaded product. After cooling and solidifying the melt-kneaded product, the solidified product is coarsely pulverized, and the obtained coarsely pulverized product is mechanically pulverized using a jet mill, a micron jet, an IDS type mill or other impingement type air current pulverizer, or a kryptron, a turbo mill, an inomizer, or the like. The resulting finely pulverized product is subjected to a desired particle size distribution using an airflow classifier or the like to obtain the toner particles of the present invention. By externally adding and mixing an inorganic fine powder such as a fluidizing agent or an abrasive to the obtained toner particles, the toner of the present invention in which the inorganic fine powder exists on the surface of the toner particles can be obtained.
[0146]
Examples of a mixer for mixing the toner include a Henschel mixer (manufactured by Mitsui Mining); a super mixer (manufactured by Kawata); a ribocorn (manufactured by Okawara Seisakusho); a Nauta mixer, a turbulizer, and a cyclomix (Hosokawa Micron). Spiral Pin Mixer (manufactured by Taiheiyo Kiko Co., Ltd.); Reedige Mixer (manufactured by Matsubo Co., Ltd.). Kneading machines include KRC Kneader (manufactured by Kurimoto Iron Works); Bus Co Kneader (Buss) TEM extruder (manufactured by Toshiba Machine Co., Ltd.); TEX twin-screw kneader (manufactured by Nippon Steel Works); PCM kneader (manufactured by Ikegai Iron Works); three-roll mill, mixing roll mill, kneader (Inoue Seisakusho) Kneedex (manufactured by Mitsui Mining Co., Ltd.); MS type pressure kneader, nider ruder (manufactured by Moriyama Seisakusho); Banbury mixer (Kobe Copper Mill); examples of the crusher include a counter jet mill, a micron jet, and an inomaizer (manufactured by Hosokawa Micron); an IDS type mill, a PJM jet crusher (manufactured by Nippon Pneumatic), and a cross jet. Mill (made by Kurimoto Tekkosho); Ulmax (made by Nisso Engineering); SK Jet O Mill (made by Seishin Enterprise); Kryptron (made by Kawasaki Heavy Industries); Turbo Mill (made by Turbo E) Classifiers include Classile, Micron Classifier, Spedick Classifier (Seisin Enterprise); Turbo Classifier (Nissin Engineering); Micron Separator, Turboplex (ATP), TSP Separator (Hosokawa Micron) Elbow Jet (Nippon Steel) Trade separator (manufactured by Nippon Pneumatic Industries Co., Ltd.); YM Micro Cut (manufactured by Yasukawa Shoji Co., Ltd.). Ultra Sonic (Koei) is used as a sieving apparatus used to screen coarse particles and the like. Resona sieve, gyro shifter (Tokuju Kosakusho); Vibrasonic system (Dalton); Sonic Clean (Shinto Kogyo); Turbo screener (Turbo Kogyo); Micro shifter (Makino Sangyo) Company); circular vibrating sieve and the like.
[0147]
As the fine pulverizer for obtaining the magnetic toner of the present invention, the above-described pulverizer can be used.However, when an air-flow type pulverizer such as a jet mill is used, a toner having a large circularity is used. It is difficult to obtain, and the transfer rate is low, so that it is difficult to reduce waste toner. As a countermeasure, it is preferable to devise pulverizing conditions such as performing soft pulverization by lowering the processing amount and pulverizing pressure, or to add a surface modification treatment step after fine pulverization or classification. Therefore, it is more preferable to use a mechanical pulverizer as the pulverizing means from the viewpoint of improving toner production efficiency.
[0148]
Specifically, by using a mechanical pulverizer, when it is desired to increase the circularity of the toner, when the load in the apparatus is increased to increase the temperature in the apparatus, and when it is desired to decrease the circularity of the toner, In addition, the degree of circularity can be easily controlled by lowering the load in the apparatus to lower the temperature in the apparatus.
[0149]
In the kneading process, the mechanical pulverization / classification system capable of optimally producing the toner according to the present invention converts a powder material consisting of a coarsely pulverized material obtained by melt-kneading, cooling, and coarse pulverization into a first constant feeder. A rotor comprising a rotor that is introduced and is attached to at least a central rotation shaft, and a stator that is disposed around the rotor while maintaining a constant interval from the rotor surface, and maintains an interval. A predetermined amount of the powdery raw material is supplied from the first metering device into a mechanical pulverizer configured so that an annular space formed by the pulverization is airtight. The powder raw material is finely ground by rotating the rotor of the mechanical crusher at a high speed.
[0150]
The finely pulverized material is discharged from a powder discharge port of a mechanical pulverizer and introduced into a second quantitative feeder, and a predetermined amount of the finely pulverized material from the second quantitative feeder is subjected to cross airflow and Coanda effect. Introduced into a multi-divided airflow classifier that classifies the powder using air, and the finely pulverized material is classified into at least fine powder, medium powder and coarse powder in the multi-divided airflow classifier, and classified. This is a system in which a coarse powder is mixed with a powder raw material, introduced into the mechanical pulverizer, pulverized, and a toner is generated from the classified medium powder.
[0151]
Here, the finely pulverized product generated in the mechanical pulverizer is discharged out of the powder pulverizer through a rear chamber of the mechanical pulverizer. At this time, the cooling device, the peripheral speed of the rotor, the load, or the minimum of the rotor and the stator are adjusted so that the room temperature T1 of the rear chamber of the mechanical pulverizer is 30 to 60 ° C., more preferably 35 to 55 ° C. It is important to fine-tune the spacing. If the temperature is lower than this range, it may not be sufficiently pulverized or may have been short-passed as a coarse pulverized product, and may not have a desired particle size and circularity. On the other hand, if the temperature is higher than this range, it may be excessively pulverized at the time of pulverization, so that not only the desired durability stability is not obtained due to the surface deterioration of the toner due to heat, but also it is easy to cause in-machine fusion. This is not preferable from the viewpoint of toner productivity.
[0152]
【Example】
Hereinafter, the present invention will be described more specifically with reference to Examples, but the present invention is not limited to only these Examples.
[0153]
<Production example 1 of iron oxide particles>
5 liters of a 0.14 mol / l aqueous solution of titanyl sulfate was mixed with 50 liters of a 2 mol / l aqueous solution of ferrous sulfate under the conditions of pH = 1 and a temperature of 50 ° C. Obtain an aqueous iron solution. This titanium salt-containing aqueous ferrous sulfate solution was mixed with 43 liters of a 5 mol / l aqueous sodium hydroxide solution to obtain a ferrous hydroxide slurry. The ferrous hydroxide slurry was maintained at pH = 12, and air was blown at 85 ° C. to perform an oxidation reaction. The obtained slurry containing magnetite particles was filtered, washed, dried and pulverized according to a conventional method to obtain iron oxide particles (M-1).
[0154]
The obtained iron oxide particles were analyzed by the following method. Table 1 shows the analysis results.
[0155]
(A) Average particle size
A photograph was taken with a scanning electron microscope (magnification: 30,000) and calculated by Feret's diameter.
[0156]
(B) Magnetic properties
The measurement was performed with an external magnetic field of 796 kA / m using a vibration sample type magnetometer VSM-P7 manufactured by Toei Industry.
[0157]
(C) Surface / internal FeO ratio
25 g of the sample iron oxide particles were added to 3.8 liters of deionized water, and the mixture was stirred at a stirring speed of 200 rpm in a water bath while maintaining the temperature at 35 to 40 ° C. To this slurry, 1250 ml of an aqueous hydrochloric acid solution (deionized water) in which 424 ml of a special grade hydrochloric acid reagent was dissolved was added, and dissolution was started.
[0158]
Until all the iron oxide particles in the slurry were dissolved from the start of dissolution and the liquid became transparent, 50 ml was sampled every 10 minutes and filtered through a 0.1 μm membrane filter to collect the filtrate. From the collected filtrate, 25 ml of the iron element was quantified by ICP. From the iron element concentration in the filtrate (collected sample) collected at each time and the iron element concentration when the iron oxide particles were completely dissolved, determined by ICP, the iron element dissolution rate was calculated by the following equation (12). I asked.
[0159]
(Equation 12)

[0160]
The FeO content of each sample was determined by adding about 75 ml of deionized water to 25 ml of the remaining filtrate (collected sample) to prepare a sample solution, adding sodium diphenylamine sulfonate as an indicator, and adding a 0.1 N potassium dichromate solution. And redox titration. The titration was determined with the sample solution colored blue-violet as the end point, and the ratio (% by mass) of FeO to the iron element was determined by the following equation.
[0161]
(Equation 13)

[0162]
The ratio of FeO to the total amount of Fe in 10% by mass from the particle surface is the same as the above-mentioned collected sample of the FeO content contained in the collected sample when the iron element dissolution rate obtained by the above formula (12) becomes 10%. It was determined by the ratio (% by mass) to the amount of Fe contained. The ratio of FeO to the total amount of Fe in the remaining 90% by mass is defined as the FeO content ratio in the collected sample when the iron oxide particles are completely dissolved and the FeO content ratio when the iron element dissolution rate is 10%. Asked from. Then, the surface / internal FeO ratio was determined by the following equation.
[0163]
[Equation 14]

[0164]
<Production Examples 2 to 6 of iron oxide particles>
Using the same method as in Production Example 1 except that the amount of the aqueous solution of titanyl sulfate added to the aqueous ferrous sulfate solution was changed in Production Example 1 of iron oxide particles, the iron oxide particles (M-2) and (M- 3), (M-4), (M-5) and (M-6) were obtained. At the time of (M-4) production, an attempt was made to increase the amount of FeO on the particle surface by setting the drying conditions to vacuum drying. The same analysis as in Production Example 1 was performed on each of the obtained iron oxide particles. Table 1 shows the analysis results.
[0165]
<Production Examples 7 to 10 of iron oxide particles>
In Production Example 1 of iron oxide particles, the same method as in Production Example 1 was used, except that the air inflow amount, reaction temperature, and reaction time during the oxidation reaction of ferrous hydroxide were changed, respectively. M-7), (M-8), (M-9) and (M-10) were obtained. The same analysis as in Production Example 1 was performed on each of the obtained iron oxide particles. Table 1 shows the analysis results.
[0166]
<Production Example 11 of Iron Oxide Particles>
Iron oxide particles (M-9) were obtained in the same manner as in Production Example 1 except that the aqueous solution of titanyl sulfate was not added to the aqueous ferrous sulfate solution in Production Example 1 of iron oxide particles. About the obtained iron oxide particle (M-9), the same analysis as the said manufacture example 1 was performed. Table 1 shows the analysis results.
[0167]
<Production Example 12 of Iron Oxide Particles>
5 liters of a 0.14 mol / l aqueous solution of titanyl sulfate were mixed with 50 liters of a 2 mol / l aqueous solution of ferrous sulfate under the conditions of pH = 2.5 and a temperature of 75 ° C. An aqueous ferrous solution was obtained. This titanium salt-containing aqueous ferrous sulfate solution was mixed with 43 liters of a 5 mol / l aqueous sodium hydroxide solution to obtain a ferrous hydroxide slurry. The pH of the ferrous hydroxide slurry was maintained at 12, and air was blown at 85 ° C. to perform an oxidation reaction. The obtained slurry containing magnetite particles was filtered, washed, dried and pulverized according to a conventional method to obtain iron oxide particles (M-12). About the obtained iron oxide particle (M-12), the same analysis as the said manufacture example 1 was performed. Table 1 shows the analysis results.
[0168]
<Production example 13 of iron oxide particles>
Except that the pH of the ferrous hydroxide slurry was adjusted to 7.8 by adjusting the amount of the alkali solution (aqueous sodium hydroxide solution) when producing the ferrous hydroxide slurry in Production Example 1 of the iron oxide particles. In the same manner as in Production Example 1, iron oxide particles (M-13) were obtained. The same analysis as in Production Example 1 was performed on the obtained iron oxide particles (M-13). Table 1 shows the analysis results.
[0169]
[Table 1]

[0170]
<Production example 1 of binder resin>
・ Terephthalic acid 610g
・ Trimellitic anhydride 610g
・ 310 g of fumaric acid
・ Propoxylated bisphenol A 1050g
・ 450 g of ethoxylated bisphenol A
[0171]
The above polyester monomer was charged into a four-necked flask together with 189 g of a hydrocarbon wax and an esterification catalyst, and equipped with a decompression device, a water separation device, a nitrogen gas introduction device, a temperature measurement device, and a stirring device at 130 ° C. under a nitrogen atmosphere. A mixture of vinyl polymer monomers (621 g of styrene, 136 g of 2-ethylhexyl acrylate, and 0.13 g of divinylbenzene) was dropped from the dropping funnel over 4 hours while stirring at a temperature of. This was aged for 3 hours while maintaining the temperature at 130 ° C., and the temperature was raised to 230 ° C. to perform a reaction. After the reaction was completed, the resin was taken out of the vessel, cooled and pulverized to obtain a binder resin A.
[0172]
<Production Examples 2 to 7 of binder resin>
Binder resins B to G were obtained in the same manner as in Production Example 1 except that the amount of the monomer used in Production Example 1 of the binder resin was changed as shown in Table 2.
[0173]
<Production example 8 of binder resin>
Polyester resin H was obtained by condensation polymerization of monomers as shown in Table 2.
[0174]
<Production Example 9 of Binder Resin>
After 100 parts by mass of xylene was charged into a reaction vessel equipped with a reflux pipe, a stirrer, a nitrogen inlet pipe, a thermometer, a dropping device, and a decompression device, 1394 g of styrene, 436 g of butyl acrylate, 550 g of monobutyl maleate and a polymerization initiator were added. Then, 158 g of di-t-butyl peroxide was added thereto, and the mixture was heated to the reflux temperature while passing nitrogen gas, and maintained for 12 hours. Next, xylene was distilled off under reduced pressure to obtain a vinyl resin I.
[0175]
Table 2 shows the compositions of the binder resins A to I.
[0176]
[Table 2]

[0177]
<Example 1>
・ Binder resin A 100 parts by mass
・ 90 parts by mass of iron oxide particles (M-1)
(Characteristics at an average particle diameter of 0.13 μm, 795.8 kA / m magnetic field: Hc = 11.5 kA / m, σs = 86.5 Am ² / Kg, σr = 15.7 Am ² / Kg)
・ Azo-based iron complex compound 2 parts by mass
The materials of the above formulation were mixed well with a Henschel mixer (Model FM-75, manufactured by Mitsui Miike Kakoki Co., Ltd.), and then a twin-screw kneader (PCM-30 type, Ikekai Tekko Co., Ltd.) set at a temperature of 130 ° C. )). The obtained kneaded product was cooled and coarsely pulverized with a hammer mill to a particle diameter of 1 mm or less to obtain a powder raw material A (coarse pulverized product) as a powder raw material for toner production.
[0178]
Using a turbo mill T-250 manufactured by Turbo Kogyo Co., Ltd. as the powder raw material A, adjusting the supply amount of the crushed product to 20 kg / hr, adjusting the inlet temperature in the mechanical pulverizer to −10 ° C. and the outlet temperature to 48 ° C. Then, a finely pulverized product having a weight average particle size of 7.1 μm was obtained. Next, this finely pulverized product was classified by an air classifier to obtain a classified product (B-1) having a weight average particle size of 7.2 μm.
[0179]
Hydrophobic silica fine powder (BET specific surface area = 300 m) was added to 100 parts by mass of the classified product (B-1). ² / G) 1.2 parts by mass were externally added using a Henschel mixer to obtain Evaluation Toner 1 as a magnetic toner.
[0180]
This toner has a weight average particle diameter of 7.2 μm, and as a result of measurement by FPIA 1000, has an average circularity of 0.952, 94.5% by number of particles having a circularity a = 0.900 or more, and a circular shape. The particles having a degree of 0.950 or more were 70.5% by number. The particle concentration A (all particles) of the particles having a particle diameter of 3 μm or less before cutting (total particles) was 1,4365.2 number / μl, and the measurement particle concentration B having a particle diameter of 3 μm or more was 1205.6 number / μl. .
[0181]
(Evaluation 1)
The development speed, photoreceptor, optics, paper transport system, etc. of the Canon IR6000 copying machine were all adjusted to increase the copying speed by 20%, and the pre-transfer charger (post-charger) was removed. The modified machine and the evaluation toner 1 were left in a high temperature and high humidity environment room (32.5 ° C., 85% RH) for two nights (24 hours or more). At this time, in order to prevent dew condensation, the toner and the modified IR6000 machine were wrapped in vinyl when opened in a high-temperature, high-humidity environment room, and opened after temperature and humidity control for 6 hours or more. After standing for two nights, the evaluation toner 1 was manually supplied to the developing device. After measuring the mass of the developing device, the developing device was set on the IR6000, and the developing sleeve was spun for 3 minutes. At this time, the cleaner section and the waste toner collecting section in the main body were once removed in advance and the mass was measured.
[0182]
Using a test chart having a printing ratio of 6%, 500 images were printed, and the transfer rate was evaluated. The transfer rate of the evaluation toner 1 was 88%. The transfer rate was calculated from the following equation.
[0183]
[Equation 15]

[0184]
(Evaluation 2)
360 g of Toner 1 for evaluation was manually supplied to a developing device for IR6000, and the modified IR6000 machine used in Evaluation 1 was equipped with a pre-transfer charger (post-charger) and a room-temperature low-humidity room (23 ° C./50%). ) Overnight (over 12 hours). Thereafter, using a test chart having a printing ratio of 4%, 2,000 images were printed. Thereafter, the transmission density of the solid black image was adjusted to be 1.7, and three solid black images were output on A3 paper. The color tone of the output third solid black image was measured.
[0185]
The color tone was measured quantitatively based on the definition of the color system standardized by the International Commission on Illumination (CIE) in 1976. A spectrophotometer type 938 manufactured by X-Rite was used as the measuring instrument, the light source for observation was C light source, and the viewing angle was 2 °. As a result, the a value was 0.34, the b value was 0.03, and the L value was 22.5. At the same time, ten people involved in copier development and toner development visually checked the measured image for blackness, and all ten people answered that blackness was sufficient.
[0186]
The evaluation levels are as follows.
[0187]
◎: All 10 people judged no problem
○: Eight or more people judged that there was no problem
△: 6 or more people judged no problem
×: 5 or more people judged that the redness was strong
XX: 7 or more people judged that redness was strong
[0188]
(Evaluation 3)
The modified IR6000 machine and the evaluation toner 1 used in Evaluation 2 were left in a high-temperature and high-humidity environment (30 ° C./85%) for two nights (24 hours or more). At this time, the temperature and humidity were adjusted in the same manner as in Evaluation 1. After standing for two nights, the developing sleeve was rotated for 3 minutes, then a 1 million-sheet passing test was performed using a test chart with a printing ratio of 6%, and image densities before and after endurance, fog after endurance, The toner adhesion to the photoreceptor was evaluated.
[0189]
The image density was measured by measuring reflection density using a Macbeth densitometer (manufactured by Macbeth) using an SPI filter, and measuring the density of a 5 mm circle (5φ) in the image. The measurement results were evaluated according to the following criteria.
[0190]
The density stability was evaluated based on the difference between the initial value of durability and the density after durability.
[0191]
A: Excellent (concentration difference is less than 0.03)
：: good (concentration difference is 0.03 or more and less than 0.1)
Δ: No problem (concentration difference is 0.1 or more and less than 0.3)
×: poor (concentration difference of 0.3 or more)
The image quality of fog was evaluated on a white background portion on the test chart. The fog was evaluated by calculating the fog density (%) from the difference between the whiteness of the white background portion of the fixed image and the whiteness of the transfer material, which was measured by a reflectometer (manufactured by Tokyo Denshoku Co., Ltd.).
[0192]
The fog level was determined according to the following criteria.
[0193]
◎: Fog less than 0.1%
：: fog 0.1 or more and less than 1.0%
Δ: Fog is 1.0 or more and less than 2.0%
×: fog 2.0 or more and less than 3.0%
The evaluation of toner adhesion was evaluated according to the following evaluation criteria based on the number of white spots as image defects in a solid black image.
[0194]
：: 5 or less even after the durability test of 100,000 sheets.
〇: Five or less after endurance test of 50,000 sheets, no practical problem.
Δ: 5 or less after 30,000 sheets of durability test, 5 or more after 300,000 sheets of durability test.
X: Five or more pieces can be confirmed after a 30,000-sheet durability test.
[0195]
Table 5 shows the results of each evaluation.
[0196]
<Example 2>
The powder raw material A (coarse pulverized product) prepared in Example 1 was supplied to a pulverized product of 5.5 kg / hr and pulverization pressure of 6 kgPa by using a type I-2 mill manufactured by Nippon Pneumatic Industries Co., Ltd. The coarsely crushed toner particles having not been crushed to the predetermined particle size were crushed again by setting them back into the crusher to obtain finely crushed products having a weight average diameter of 7.3 μm. Furthermore, by classifying with an air classifier, a classified product (B-2) having a weight average diameter of 7.4 μm was obtained.
[0197]
Hydrophobic silica fine powder (BET specific surface area = 300 m) was added to 100 parts by mass of the classified product (B-2). ² / G) 1.0 part by mass was externally added using a Henschel mixer to obtain Toner 2 for evaluation. Table 3 shows the particle size and circularity of the evaluation toner 2. The same evaluation as in Example 1 was performed for the evaluation toner 2. Table 5 shows the evaluation results.
[0198]
<Example 3>
Powdered raw material B (coarse pulverized product) was produced using the same method as in Example 1 except that iron oxide particles (M-3) were used instead of the iron oxide particles (M-1) used in Example 1. ) Got. After the powder material B was pulverized, an evaluation toner 3 was prepared in the same manner as in Example 2 except that the obtained pulverized product was further passed through a thermal sphering apparatus at 62 ° C. did. Table 3 shows the particle size and circularity of the evaluation toner 3. The same evaluation as in Example 1 was performed for this evaluation toner 3. Table 5 shows the evaluation results.
[0199]
<Example 4>
Except for using iron oxide particles (M-4) in place of the iron oxide particles (M-1) used in Example 1, a powder raw material C (coarse pulverized product) was used in the same manner as in Example 1. ) Got. The same method as in Example 2 was used except that the raw material C was changed to a pulverized product supply amount of 1.5 kg / hr and a pulverizing pressure of 2 kgPa by using an I-2 type mill manufactured by Nippon Pneumatic Industries, Ltd. As a result, evaluation toner 4 was obtained. Table 3 shows the particle size and circularity of the evaluation toner 4. The same evaluation as in Example 1 was performed for this evaluation toner 4. Table 5 shows the evaluation results.
[0200]
<Examples 5 and 6>
In Example 1, the iron oxide particles (M-5) and (M-8) were used instead of the iron oxide particles (M-1), and the amount of coarsely crushed product supplied when finely pulverized by a mechanical pulverizer was used. A classified product was produced using the same method as in Example 1 except that the inlet temperature and the outlet temperature in the pulverizer were arbitrarily adjusted. Hydrophobic silica fine powder (BET specific surface area = 300 m) was added to 100 parts by mass of each classified product. ² / G) of 1.0 part by mass and 4.0 parts by mass of strontium titanate (average particle size: 1.8 μm) were externally added using a Henschel mixer to obtain Evaluation Toners 5 and 6. Table 3 shows the particle size and circularity of each toner. The same evaluation as in Example 1 was performed for each of the evaluation toners 5 and 6. Table 5 shows the evaluation results.
[0201]
<Example 7>
In Example 1, iron oxide particles (M-9) were used in place of the iron oxide particles (M-1), the amount of coarsely crushed product supplied when finely pulverized by a mechanical pulverizer, the inlet temperature in the pulverizer, and An evaluation toner 7 was obtained in the same manner as in Example 1 except that the outlet temperature was arbitrarily adjusted. Table 3 shows the particle size and circularity of the evaluation toner 7. This toner 7 for evaluation was evaluated in the same manner as in Example 1. Table 5 shows the evaluation results.
[0202]
<Examples 8 and 9>
In Example 1, using the binder resins B and C instead of the binder resin A, respectively, the supply amount of the coarsely crushed product when finely pulverized by a mechanical pulverizer, and the inlet temperature and the outlet temperature in the pulverizer are arbitrarily set. A classed product was prepared using the same method as in Example 1 except that the adjustment was performed. A hydrophobic silica fine powder (BET specific surface area = 300 m ² / G) 1.0 parts by mass and 4.0 parts by mass of strontium titanate (average particle size: 1.8 μm) were externally added using a Henschel mixer to obtain toners 8 and 9 for evaluation. Table 3 shows the particle size and circularity of each of the evaluation toners 8 and 9. The same evaluation as in Example 1 was performed for each of the evaluation toners 8 and 9. Table 5 shows the evaluation results.
[0203]
<Examples 10 and 11>
In Example 1, the binder resins D and E were used instead of the binder resin A, and the iron oxide particles (M-3) were used instead of the iron oxide particles (M-1). A classified product was produced using the same method as in Example 1 above, except that the supply amount of the coarsely crushed product and the inlet and outlet temperatures in the crusher were arbitrarily adjusted during the fine pulverization. A hydrophobic silica fine powder (BET specific surface area = 300 m ² / G) of 1.0 part by mass and 4.0 parts by mass of strontium titanate (average particle size: 1.8 μm) were externally added using a Henschel mixer to obtain Toners 10 and 11 for evaluation. Table 3 shows the particle size and circularity of each of the evaluation toners 10 and 11. The same evaluation as in Example 1 was performed for each of the evaluation toners 10 and 11. Table 5 shows the evaluation results.
[0204]
<Examples 12 to 15>
In Example 1, binder resin E was used instead of binder resin A, and iron oxide particles (M-5) were used instead of iron oxide particles (M-1). The addition amount of the iron oxide particles (M-5) was changed to 50, 75, 120, and 150 parts by mass, respectively, the supply amount of the coarsely crushed product when finely pulverized by a mechanical pulverizer, and the inlet temperature and outlet in the pulverizer. A classified product was produced using the same method as in Example 1 except that the temperature was arbitrarily adjusted. A hydrophobic silica fine powder (BET specific surface area = 300 m ² / G) 0.5 to 1.2 parts by mass and 4.0 parts by mass of strontium titanate (average particle size: 1.8 μm) are externally added by a Henschel mixer, and toners for evaluation 12, 13, 14, 15 are added. Got. Table 3 shows the particle size and circularity of each of the toners 12 to 15. The same evaluation as in Example 1 was performed for each of the evaluation toners 12 to 15. Table 5 shows the evaluation results.
[0205]
<Example 16>
In Example 1, the binder resin E was used instead of the binder resin A, and the iron oxide particles (M-13) were used instead of the iron oxide particles (M-1). A toner 16 for evaluation was obtained in the same manner as in Example 1 except that the addition amount of ()) was changed to 120 parts by mass. Table 3 shows the particle size and circularity of the obtained toner 16. This toner 16 for evaluation was evaluated in the same manner as in Example 1. Table 5 shows the evaluation results.
[0206]
<Example 17>
・ Binder resin 80 parts by mass
・ Binder resin I 20 parts by mass
・ 90 parts by mass of iron oxide particles (M-1)
(Characteristics at an average particle diameter of 0.13 μm, 795.8 kA / m magnetic field: Hc = 11.5 kA / m, σs = 86.5 Am ² / Kg, σr = 15.7 Am ² / Kg)
・ Azo-based iron complex compound 2 parts by mass
・ Hydrocarbon wax 4 parts by mass
The materials having the above formulation were mixed, kneaded and coarsely pulverized in the same manner as in Example 1 to obtain a powder raw material D (coarse pulverized product), which is a powder raw material for toner production.
[0207]
Powder material D was pulverized and classified in the same manner as in Example 1. Hydrophobic silica fine powder (BET specific surface area = 300 m) was used with respect to 100 parts by mass of the obtained classified product. ² / G) 1.0 part by mass was externally added using a Henschel mixer to obtain Toner 17 for evaluation. Table 3 shows the particle size and circularity of the evaluation toner 17. This evaluation toner 17 was evaluated in the same manner as in Example 1. Table 5 shows the evaluation results.
[0208]
<Comparative Examples 1 and 2>
In Example 1, instead of the binder resin A, the binder resin F and the binder resin G were used, and the amount of coarsely crushed product supplied when finely pulverized by a mechanical pulverizer, and the inlet temperature and outlet in the pulverizer Using the same method as in Example 1 except that the temperature was arbitrarily adjusted, comparative evaluation toners 18 and 19 were obtained. Table 4 shows the particle size and circularity of each of the toners 18 and 19. The same evaluation as in Example 1 was performed for each of the comparative evaluation toners 18 and 19. Table 5 shows the evaluation results.
[0209]
<Comparative Example 3>
・ Binder resin 100 parts by mass
・ Iron oxide particles (M-1) 120 parts by mass
(Characteristics at an average particle diameter of 0.13 μm, 795.8 kA / m magnetic field: Hc = 11.5 kA / m, σs = 86.5 Am ² / Kg, σr = 15.7 Am ² / Kg)
・ Azo-based iron complex compound 2 parts by mass
・ Hydrocarbon wax 4 parts by mass
The material having the above formulation was mixed, kneaded and coarsely pulverized in the same manner as in Example 1 to obtain a powder raw material E (coarse pulverized product) which is a powder raw material for toner production.
[0210]
Powder material E was finely pulverized and classified in the same manner as in Example 1. Hydrophobic silica fine powder (BET specific surface area = 300 m) was used with respect to 100 parts by mass of the obtained classified product. ² / G) 1.0 part by mass was externally added using a Henschel mixer to obtain a comparative evaluation toner 20. Table 4 shows the particle size and circularity of the obtained comparative evaluation toner 20. This comparative evaluation toner 20 was evaluated in the same manner as in Example 1. Table 5 shows the evaluation results.
[0211]
<Comparative Example 4>
In Comparative Example 3, a binder resin I was used instead of the binder resin H, and iron oxide particles (M-2) were used instead of the iron oxide particles (M-1). Comparative Evaluation Toner 21 was obtained using the same method as in Comparative Example 3, except that the supply amount of the crushed product and the inlet and outlet temperatures in the crusher were arbitrarily adjusted. Table 4 shows the particle size and circularity of the obtained comparative evaluation toner 21. This comparative evaluation toner 21 was evaluated in the same manner as in Example 1. Table 5 shows the evaluation results.
[0212]
<Comparative Examples 5 to 9>
In Example 1, iron oxide particles (M-6), (M-7), (M-10), (M-11), and (M-12) were used instead of the iron oxide particles (M-1). The toner for comparative evaluation 22 was prepared in the same manner as in Example 1 except that the amount of the coarsely crushed product supplied when finely pulverized by a mechanical pulverizer and the inlet and outlet temperatures in the pulverizer were arbitrarily adjusted. , 23, 24, 25, 26 were obtained. Table 4 shows the particle size and circularity of each of the comparative evaluation toners 22 to 26. The same evaluation as in Example 1 was performed for each of the evaluation toners 22 to 26. Table 5 shows the evaluation results.
[0213]
[Table 3]

[0214]
[Table 4]

[0215]
[Table 5]

[0216]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, even if it makes a particle diameter small or a shape approximates a spherical shape, it is excellent in charge stability, durability stability, high developability, and can provide a toner with high blackness.

Claims (11)

Toner particles containing at least a binder resin and a magnetic substance, and a magnetic toner having an inorganic fine powder present on the surface of the toner particles,
The binder resin contains at least a polyester resin containing a polyester monomer unit and a vinyl resin containing a vinyl monomer unit, and the content ratio of the polyester monomer unit to the vinyl monomer unit is 50/50 to 90 / by mass ratio. 10 and
A weight average particle diameter (D4) of the magnetic toner is 5 to 12 μm;
The magnetic substance is (1) iron oxide particles having an average particle diameter of 0.1 to 0.3 μm,
(2) 0.3 to 1.5 mass% of titanium element is contained in the iron oxide particles with respect to the total amount of the iron oxide particles,
{Circle over (3)} The ratio of the ratio of FeO (A%) to the total amount of Fe in 10% by mass from the surface of the iron oxide particles (A%) and the ratio of FeO to the total amount of Fe (B%) in the remaining 90% by mass (A / B) is the following formula (1)
0.7 ≦ A / B ≦ 1 (1)
A magnetic toner characterized by satisfying the following. 2. The magnetic toner according to claim 1, wherein the a and b values in the color tone measurement of a solid black image having a transmission density of 1.2 to 1.7 satisfy the following expressions (2) and (3).
0 ≦ a value ≦ 0.5 (2)
−0.5 ≦ b value ≦ 0.8 (3)
(However, the average particle diameter of the iron oxide particles is in the range of 0.1 to 0.3 μm.) 3. The magnetic toner according to claim 1, wherein the iron oxide particles are octahedral. The magnetic toner according to any one of claims 1 to 3, wherein the iron oxide particles are contained in an amount of 50 to 150 parts by mass with respect to 100 parts by mass of the binder resin. The magnetic toner according to any one of claims 1 to 3, wherein the iron oxide particles are contained in an amount of 60 to 120 parts by mass with respect to 100 parts by mass of the binder resin. Formula (4) below for particles of 3 μm or more of the magnetic toner
Circularity _{a = L 0 / L (4} )
[Where L ₀ represents the circumference of a circle having the same projected area as the particle image, and L represents the circumference of the particle image. ]
In the circularity distribution based on the number of circularities (a) obtained by the calculation, 90% by number or more of particles having a circularity (a) of 0.900 or more exist, and the average value of the circularity (a) is 0. The magnetic toner according to claim 1, wherein the ratio is 94 or more. The relationship between the weight average particle diameter (X) and the cut rate (Z) of the magnetic toner is expressed by the following equation (5).
Z ≦ 5.3 × X (5)
Satisfied,
In the circularity distribution, the relationship between the number-based cumulative value (Y) of particles having a circularity (a) of 0.950 or more and the weight average diameter (X) of the magnetic toner is represented by the following equation (6).
Y ≧ exp5.51 × X−0.645 (6)
7. The magnetic toner according to claim 6, wherein the following formula is satisfied. The relationship between the weight average particle diameter (X) and the cut ratio (Z) of the magnetic toner is expressed by the following equation (7).
Z> 5.3 × X (7)
Satisfied,
In the circularity distribution, the relationship between the number-based cumulative value (Y) of particles having a circularity (a) of 0.950 or more and the weight average diameter (X) of the magnetic toner is represented by the following equation (8).
Y ≧ exp 5.37 × X−0.545 (8)
7. The magnetic toner according to claim 6, wherein the following formula is satisfied. The magnetic toner according to any one of claims 1 to 8, wherein the content ratio of the polyester monomer unit and the vinyl monomer unit in the binder resin is from 60/40 to 85/15. The magnetic toner according to any one of claims 1 to 9, wherein the binder resin further contains a hybrid resin component in which the polyester-based monomer unit and the vinyl-based monomer unit have partially reacted. . The polyester-based monomer unit of the binder resin has a structure crosslinked with a trivalent or higher polyhydric carboxylic acid or an anhydride thereof and / or a trivalent or higher polyhydric alcohol. The magnetic toner according to any one of the above.