JP2004198570A - Black magnetic toner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnetic black toner which has good transfer efficiency, which exhibits little fog and scattering, and which exhibits excellent endurance stability and blackness. <P>SOLUTION: The magnetic black toner is a small particle size magnetic substance (0.1 to 0.3 μm) containing 0.3 to 1.5 mass% titanium, wherein the ratio A/B of the proportion (A%) of FeO to total Fe in 10 mass% from the particle surface to the proportion (B%) of FeO to total Fe in the remaining 90 mass% ranges from 0.7 to 1.0, the magnetic substance has an electric resistance of 5×10<SP>1</SP>to 5×10<SP>3</SP>Ω cm, the surface of the magnetic substance is coated with an iron-zinc oxide film, and further the surface layer contains silicon elements. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

【００７１】
円形度標準偏差ＳＤは、上記式（１）及び（８）で求めた平均円形度をａ、各粒子における円形度をａｉ、測定粒子数をｍとすると、下記式（９）から算出される。
【００７２】
【数２】

【００７３】
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。
【００７４】
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。
【００７５】
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とする事で、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事ができる。
【００７６】
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。
【００７７】
試料分散液は、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。
【００７８】
更に本発明においてその目的を達成するに好ましいトナーの構成を以下に詳述する。
【００７９】
本発明に使用される磁性材料としての、酸化鉄粒子とは、好ましくはＦｅＯの高いマグネタイトを主成分とするものである。以下の説明では、酸化鉄粒子としてその代表的なものであるマグネタイト粒子について説明する。又、酸化鉄粒子又はマグネタイト粒子と言う時には、その内容によって個々の粒子又はその集合の何れも意味する。
【００８０】
具体的には、本発明のマグネタイト粒子は、粒子中にチタンを含有し、且つ粒子表面から１０質量％中における総Ｆｅ量に対するＦｅＯの割合（Ａ％）と、残りの９０質量％中における総Ｆｅ量に対するＦｅＯの割合（Ｂ％）との比Ａ／Ｂ（以下、「表面／内部ＦｅＯ比」と称す）が０．７〜１であり、粒子表面が鉄−亜鉛酸化物の被膜が被覆され、その上に鉄−珪素酸化物の被膜で被覆されている酸化鉄粒子であり、
粉体抵抗（電気抵抗）が５×１０¹〜５×１０³（Ω・ｃｍ）である事を特徴とする。
【００８１】
水溶液反応により得られる酸化鉄粒子、特にＦｅＯの高いマグネタイト粒子は、一般的に第一鉄塩水溶液とアルカリ溶液とを中和混合して得られた水酸化第一鉄スラリーを酸化することにより得られる。かかる公知技術で得られるマグネタイト粒子の表面／内部ＦｅＯ比については、特開２０００−２４２６号公報に記載されるように、約０．３〜０．６程度である。（この公報記載の粒子半径の３．５％相当厚みの粒子近傍層は、本発明の重量に換算して粒子表面から１０質量％とほぼ合致する）
【００８２】
これに対して、本発明で使用する酸化鉄粒子は表面／内部ＦｅＯ比が０．７〜１であり、粒子表面近傍のＦｅＯ含有量が十分に高く、黒色度は十分高い上、多少の表面酸化があっても黒色度の経時劣化の影響を受けない。
【００８３】
この表面／内部ＦｅＯ比が０．７未満の場合。表面粒子近傍のＦｅＯ量が十分とは言えず黒色度が低いものであったり、黒色度は高くても、経時劣化の面で劣る、耐環境性の不良なマグネタイト粒子となる。又、表面／内部ＦｅＯ比が１を超える場合、黒色度や耐環境性には優れるものの、粒子表面のＦｅＯを必要以上に高くしても、更なる本願発明効果も改善は得られない。この表面／内部ＦｅＯ比は、黒色度、耐環境性の改善をより高める事を考慮すると、０．８〜１が好ましく、０．９〜１がより好ましい。
【００８４】
又、本発明で使用する酸化鉄粒子は、粒子中にチタンを含有している事が重要であり、チタンが、酸化鉄粒子総量に対して、チタン換算で０．３〜１．５質量％含有されている事が好ましい。本発明においては、マグネタイト粒子にチタンが含有されている事が、マグネタイト粒子の表面／内部ＦｅＯ比が０．７〜１となる事に大きく関与している事は後述するがこのチタン含有量が０．３質量％未満では、粒子表面近傍のチタン含有量が少なくなる傾向にあり、水溶液反応により得られるマグネタイト粒子の表面／内部ＦｅＯ比を０．７〜１にする事が困難であり、１．５質量％を超える場合には、粒子表面近傍のチタン含有量が過剰となる傾向にあり、チタン含有量が高過ぎて、磁気特性や黒色度、色相等、他の特性不良を惹き起こす場合があり、好ましくない。このチタン含有量は、チタン含有量をより減らし、且つ、表面／内部ＦｅＯ比が低下しないように調整する上で、０．４〜１．２質量％とする事が好ましく、０．４〜０．８質量％とする事がより好ましい。
【００８５】
又、本発明に使用する酸化鉄粒子は、粉体抵抗（電気抵抗）が５×１０¹〜５×１０³（Ω・ｃｍ）であることが重要である。粉体抵抗が５×１０³（Ω・ｃｍ）以上となる場合には、トナー粒子表面に析出した酸化鉄粒子が十分にリークサイトとして働かない場合があり好ましくない。５×１０¹（Ω・ｃｍ）未満となる場合には、トナー自体の抵抗が下がり過ぎて帯電特性に影響を与える場合があり好ましくない。粉体抵抗（電気抵抗）は、トナーの帯電特性を十分に満足し、且つ、リークサイトとしての効果を発揮させる上で、８×１０¹〜２×１０³（Ω・ｃｍ）とする事がより好ましい。
【００８６】
又、本発明に使用する酸化鉄粒子は、粒子表面が鉄−亜鉛の被膜が被覆されていることが重要であり、酸化鉄粒子中に含有される亜鉛量が、全鉄元素を基準として、０．１〜１．６重量％含有されている事が好ましい。亜鉛含有量が１．６重量％以上となる場合には、磁性体自体の色味が黒味から黄味を帯びた色となる場合があり、又、本小粒径酸化鉄は特に、黒味を確保する目的で表層のＦｅＯ含有量を高める設計を施している為、電気抵抗は低めとなる。亜鉛を含有せせる事により、更に電気抵抗は下がる方向になり、トナー自体の帯電特性に影響を与える場合があり好ましくない。亜鉛含有量が０．１重量％未満となる場合には酸化鉄粒子表層の被膜生成が十分に達成できない場合があり好ましくない。
【００８７】
又、本発明に使用する酸化鉄粒子は、粒子表面が鉄−珪素酸化物の被膜が被覆されていることが重要であり、酸化鉄粒子中に含有される珪素元素が、全鉄元素を基準として、０．０５〜２．０重量％含有されている事が好ましい。珪素元素含有量が２．０重量％以上となる場合には、高湿下における長期放置後の吸湿性に問題発生する場合があり、又、本小粒径酸化鉄は特に、飛び散りを防止する目的があり、珪素添加により抵抗が上がりすぎることで、過剰帯電緩和効果が薄れる場合があり好ましくない。珪素元素含有量が０．０５重量％未満となる場合には、磁性トナーの流動性が低下する場合があり、又、亜鉛を被覆させる事により低抵抗化した酸化鉄粒子の抵抗を十分に調整出来ない場合があり好ましくない。
【００８８】
又、本発明で使用する酸化鉄粒子は、平均粒子径が０．１〜０．３μｍであることが分散性、黒味等に対して問題は無く好ましい、更に、本発明で用いる酸化鉄粒子の特徴をより発揮する為には、平均粒子径を０．１〜０．２μｍとする事が好ましく、０．１〜０．１５とする事がより好ましい好ましい。平均粒子径が０．１μｍ未満となる場合、トナー中における酸化鉄の再凝集等による分散不良をや、本発明用酸化鉄粒子を用いても、トナー黒味を損なう場合があり好ましくない。平均粒子径が０．３μｍ超えとなる場合、トナー黒味としては申し分無いが、トナー粒子中の分散悪化の原因となる場合があり、又、本来の目的であるトナー表面への酸化鉄粒子の析出が十分に達成できず、飛び散りが悪化する場合があり好ましくない。
【００８９】
又、本発明で使用する酸化鉄粒子は、粒状粒子であれば、球状、六面体状、多面体状等、いかなる粒子でも問題は無いが、トナー粒子中への分散性、黒味の面から、八面体状である事がより好ましい。
【００９０】
又、本発明に使用する酸化鉄粒子は、Ａｌ、Ｐ、Ｓ、Ｃｒ、Ｍｎ、Ｃｏ。Ｎｉ、Ｃｕ、Ｚｎ、Ｍｇの総含有量が少ない事が好ましい。上記成分はマグネタイト粒子製造時に原料由来の不可避成分として含有されるか、分散性や流動性改良手段として添加される事により、酸化鉄粒子中に含有される。本発明用の酸化鉄粒子においては、表面／内部ＦｅＯ比コントロール及び高磁気特性の維持を考慮した場合、上記成分の含有量は低い方がより効果を発揮しやすく、１質量％以下である事が好ましく、０．８質量％である事がより好ましい。
【００９１】
特に、Ｍｎ、Ｍｇ元素に関しては、全鉄元素を基準として、総量が０．２０重量％以下である事が好ましい。Ｍｎ、Ｍｇ元素の含有量が０．２０％以上となる場合には、酸化鉄粒子のＦｅＯ量をコントロールする事が困難となる場合や、酸化鉄粒子の磁気特性低下の原因となる場合があり好ましくない。
【００９２】
又、本発明に使用する酸化鉄粒子は、ＪＩＳ Ｋ５１０１−１９９１に準拠した粉体の黒色度及び色相測定において、色差計によるＬ値が２０以下、ａ値が０．１以下、ｂ値が０．１以下である事が好ましい。このＬ値が２０超え、ａ値が０．１超え、ｂ値が０．１超えとなる場合、トナー化後のべた黒画像における黒味を損なう場合があり好ましくない。
【００９３】
これらの酸化鉄粒子は、７９５．８ｋＡ／ｍ印加での磁気特性が抗磁力１．６〜１２．０ｋＡ／ｍ、飽和磁化５０〜２００Ａｍ²／ｋｇ（好ましくは５０〜１００Ａｍ²／ｋｇ）、残留磁化２〜２０Ａｍ²／ｋｇのものが好ましい。
【００９４】
結着樹脂１００質量部に対して、酸化鉄粒子は５０〜１５０質量部、好ましくは６０〜１２０質量部使用するのが良い。５０質量部未満となる場合には、カブリ，飛び散りが悪化するだけでなく、磁性黒色トナーとした場合には、黒味不足となる場合もあり、好ましくない。
【００９５】
１５０質量部超えとなる場合には、帯電付与部材（現像スリーブ）からの飛翔が十分に行えなくなり、画像濃度低下の原因となる場合もあり、好ましくない。
【００９６】
次に、本発明で用いられる酸化鉄粒子の製造方法は一般的なマグネタイト粒子の製造方法を用いても特に問題は無いが、特に好ましい製造方法について、以下、具体的に説明する。
【００９７】
本発明用酸化鉄粒子は、第一鉄塩水溶液とアルカリ溶液とを中和混合して得られた、水酸化第一鉄スラリーを酸化して、酸化鉄粒子を製造する方法において、４価のチタン塩及び／又はチタン酸塩が、水酸化チタンとして析出しないように、第一鉄塩水溶液のＰＨを１．５以下、且つ温度７０℃以下に調整して、第一鉄塩水溶液に添加、混合することにより得られた水酸化第一鉄スラリーを使用することより製造できる。
【００９８】
ここで、重要なのは、４価のチタン塩及び／又はチタン酸塩が、水酸化チタンとして析出しないように、第一鉄塩水溶液のＰＨを１．５以下、且つ温度７０℃以下に調整して、第一鉄塩水溶液に添加、混合することにある。
【００９９】
第一鉄塩水溶液のＰＨを１．５以下、且つ温度７０℃以下に調整する理由は、添加する４価のチタン塩及び／又はチタン酸塩が加水分解し、水酸化チタンとして析出しないように行うものである。この方法によれば、粒子の核生成から最終的な粒子成長完了に至るまで、価数４価のチタン成分が粒子内に均一に含有され、粒子表面においてもＦｅ２＋が安定して生成されることになる。
【０１００】
添加するチタン塩及び／又はチタン酸塩は、最終的な酸化鉄粒子総量に対して、チタン換算して０．３〜１．５質量％となるように調整する。
【０１０１】
第一鉄塩として利用できるものは、硫酸第一鉄、塩化第一鉄等、水可溶性塩ならば特に限定されない。又、添加に用いられるチタン塩やチタン酸塩として使用できるものは、硫酸チタン（ＩＶ）、塩化チタン（ＩＶ）、硫酸チタニル、硝酸チタニル等が挙げられる。
【０１０２】
次に、得られた４価のチタン成分を含有する第一鉄塩水溶液とアルカリ溶液とを中和混合して、水酸化第一鉄スラリーを生成させる。
【０１０３】
水酸化第一鉄スラリーを生成させる際のアルカリ溶液量は、求める酸化鉄粒子の形状に応じて調整すればよい。具体的には、水酸化第一鉄スラリーのＰＨが８．０未満となるように調整すれば、球状粒子が得られ、８．０〜９．５となるように調整すれば、六面体状粒子が得られ、９．５を超えるように調整すれば、八面体状粒子が得られるので、適宣調整する。
【０１０４】
アルカリ溶液は、水酸化ナトリウムや水酸化カリウム水溶液等の水酸化アルカリ水溶液を用いる事が出来る。
【０１０５】
こうして得られた、水酸化第一鉄スラリーより、酸化鉄粒子を得るために、常法の酸素含有ガス、好ましくは空気をスラリー中に吹き込みながら酸化反応を行い、第一の酸化反応を終了させる。次に、酸化鉄粒子全体におけるＺｎ／Ｆｅの重量比（重量％）が０．１〜１．６重量％となるように、亜鉛を含む第一鉄塩を添加し、ＰＨ６．０〜９．０に調整し、再び酸化反応を行い、第二の酸化反応を終了させる。次に、酸化鉄粒子全体におけるＳｉ／Ｆｅの重量比（重量％）が０．０５〜２．０重量％となるように、珪酸塩を含む第一鉄塩を添加し、ＰＨ６．０〜９．０に調整し、再び酸化反応を行い、酸化反応終了後のスラリーを常法のろ過、洗浄、乾燥、粉砕処理を行う。
【０１０６】
本発明に用いられる結着樹脂としては、ビニル系樹脂、ポリエステル系樹脂、エポキシ樹脂等が挙げられる。中でもビニル系樹脂とポリエステル系樹脂が帯電性や定着性でより好ましい。
【０１０７】
ビニル系樹脂としては、例えばスチレン；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−ドデシルスチレンの如きスチレン誘導体；エチレン、プロピレン、ブチレン、イソブチレンの如きエチレン不飽和モノオレフィン類；ブタジエンの如き不飽和ポリエン類；塩化ビニル、塩化ビニリデン、臭化ビニル、沸化ビニルの如きハロゲン化ビニル類；酢酸ビニル、プロピオン酸ビニル、ベンゾエ酸ビニルの如きビニルエステル類；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の如き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の如き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の如きビニルエーテル類；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の如きビニルケトン類；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−ビニルピロリドンの如き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、アクリルアミドの如きアクリル酸もしくはメタクリル酸誘導体；α，β−不飽和酸のエステル、二塩基酸のジエステル類が挙げられる。これらのビニル系モノマーが単独もしくは２つ以上で用いられる。
【０１０８】
これらの中でもスチレン系共重合体、スチレン−アクリル系共重合体となるようなモノマーの組み合わせが好ましい。
【０１０９】
また、必要に応じて以下に例示する様な架橋性モノマーで架橋された重合体又は共重合体であってもよい。
【０１１０】
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−ペンタンジオールジアクリレート、１，６ヘ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ト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結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類として例えば、商品名ＭＡＮＤＡ（日本化薬）が挙げられる。
【０１１１】
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。
【０１１２】
これらの架橋剤は、他のモノマー成分１００質量部に対して、０．０１〜１０質量部（さらに好ましくは０．０３〜５質量部）用いることができる。
【０１１３】
これらの架橋性モノマーのうち、トナー用樹脂に定着性、耐オフセット性の点から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。
【０１１４】
本発明において、ビニル系モノマーの単重合体または共重合体、ポリエステル、ポリウレタン、エポキシ樹脂、ポリビニルブチラール、ロジン、変性ロジン、テルペン樹脂、フェノール樹脂、脂肪族または脂環族炭化水素樹脂、芳香族系石油樹脂等を、必要に応じて前述した結着樹脂に混合して用いることができる。
【０１１５】
２種以上の樹脂を混合して、結着樹脂として用いる場合、より好ましい形態としては分子量の異なるものを適当な割合で混合するのが好ましい。
【０１１６】
結着樹脂のガラス転移温度は好ましくは４５〜８０℃、より好ましくは５５〜７０℃であり、数平均分子量（Ｍｎ）は２，５００〜５０，０００、重量平均分子量（Ｍｗ）は１０，０００〜１，０００，０００であることが好ましい。
【０１１７】
ビニル系重合体又は共重合体からなる結着樹脂を合成する方法としては、塊状重合法、溶液重合法、懸濁重合法、乳化重合法の如き重合法が利用できる。カルボン酸モノマー又は酸無水物モノマーを用いる場合には、モノマーの性質上、塊状重合法または溶液重合法を利用することが好ましい。
【０１１８】
一例として次のような方法が挙げられる。ジカルボン酸、ジカルボン酸無水物、ジカルボン酸モノエステルの如きモノマーを用い、塊状重合法、溶液重合法によりビニル系共重合体を得ることができる。溶液重合法においては、溶媒留去時にジカルボン酸、ジカルボン酸モノエステル単位を留去条件を工夫することにより一部無水化することができる。更に、塊状重合法または溶液重合法によって得られたビニル系共重合体を加熱処理することで更に無水化を行うことができる。酸無水物をアルコールの如き化合物により一部エステル化することもできる。
【０１１９】
逆に、この様にして得られたビニル系共重合体を加水分解処理で酸無水物基を閉環させ、一部ジカルボン酸とすることができる。
【０１２０】
一方、ジカルボン酸モノエステルモノマーを用い、懸濁重合法、乳化重合法で得られたビニル系共重合体を加熱処理による無水化及び加水分解処理による開環により無水物からジカルボン酸を得ることができる。塊状重合法または溶液重合法で得られたビニル系共重合体を、モノマー中に溶解し、次いで懸濁重合法または乳化重合法により、ビニル系重合体または共重合体を得る方法を用いれば、酸無水物の一部は開環してジカルボン酸単位を得ることができる。重合時にモノマー中に他の樹脂を混合してもよく、得られた樹脂を加熱処理による酸無水物化、弱アルカリ水処理による酸無水物の開環アルコール処理によりエステル化を行うことができる。
【０１２１】
ジカルボン酸、ジカルボン酸無水物モノマーは交互重合性が強いので、無水物、ジカルボン酸の如き官能基をランダムに分散させたビニル系共重合体を得る為には以下の方法が好ましい方法の一つである。ジカルボン酸モノエステルモノマーを用い溶液重合法によってビニル系共重合体を得、このビニル系共重合体をモノマー中に溶解し、懸濁重合法によって結着樹脂を得る方法である。この方法では溶液重合後の溶媒留去時に処理条件により、全部またはジカルボン酸モノエステル部を脱アルコール閉環無水化させることができ酸無水物を得ることができる。懸濁重合時には酸無水物基が加水分解開環し、ジカルボン酸が得られる。
【０１２２】
ポリマーにおける酸無水物化は、カルボニルの赤外吸収が酸またはエステルの時よりも高波数側にシフトするので酸無水物の生成または消滅は確認できる。
【０１２３】
この様にして得られる結着樹脂は、カルボキシル基、無水物基、ジカルボン酸基が結着樹脂中に均一に分散されているので、トナーに良好な帯電性を与えることができる。
【０１２４】
結着樹脂としては以下に示すポリエステル樹脂も好ましい。
【０１２５】
ポリエステル樹脂は、全成分中４５〜５５ｍｏｌ％がアルコール成分であり、５５〜４５ｍｏｌ％が酸成分である。
【０１２６】
アルコール成分としては、エチレングリコール、プロピレングリコール、１，３−ブタンジオール、１，４−ブタンジオール、２，３−ブタンジオール、ジエチレングリコール、トリエチレングリコール、１，５−ペンタンジオール、１，６−ヘキサンジオール、ネオペンチルグリコール、２−エチル１，３−ヘキサンジオール、水素化ビスフェノールＡ、下記（Ｂ）式で表わされるビスフェノール誘導体；
【０１２７】
【化１】

【０１２８】
また、（Ｃ）式で示されるジオール類；
【０１２９】
【化２】

【０１３０】
グリセリン、ソルビット、ソルビタン等の多価アルコール類が挙げられる。
【０１３１】
また、全酸成分中５０ｍｏｌ％以上を含む２価のカルボン酸としてはフタル酸、テレフタル酸、イソフタル酸、無水フタル酸の如きベンゼンジカルボン酸類又はその無水物；こはく酸、アジピン酸、セバシン酸、アゼライン酸の如きアルキルジカルボン酸類又はその無水物、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、イタコン酸の如き不飽和ジカルボン酸又はその無水物等が挙げられ、また、３価以上のカルボン酸としてはトリメリット酸、ピロメリット酸、ベンゾフェノンテトラカルボン酸やその無水物等が挙げられる。
【０１３２】
特に好ましいポリエステル樹脂のアルコール成分としては前記（Ｂ）式で示されるビスフェノール誘導体であり、酸成分としては、フタル酸、テレフタル酸、イソフタル酸又はその無水物、こはく酸、ｎ−ドデセニルコハク酸又はその無水物、フマル酸、マレイン酸、無水マレイン酸の如きジカルボン酸類；トリメリット酸又はその無水物のトリカルボン酸類が挙げられる。
【０１３３】
これらの酸成分及びアルコール成分から得られたポリエステル樹脂を結着樹脂として使用した熱ローラー定着用トナーとして定着性が良好で、耐オフセット性に優れているからである。
【０１３４】
ポリエステル樹脂の酸価は好ましくは９０ｍｇＫＯＨ／ｇ以下、より好ましくは５０ｍｇＫＯＨ／ｇ以下であり、ＯＨ価は好ましくは５０ｍｇＫＯＨ／ｇ以下、より好ましくは３０ｍｇＫＯＨ／ｇ以下であることが良い。これは、分子鎖の末端基数が増えるとトナーの帯電特性において環境依存性が大きくなる為である。
【０１３５】
ポリエステル樹脂のガラス転移温度は好ましくは５０〜７５℃、より好ましくは５５〜６５℃であり、さらに数平均分子量（Ｍｎ）は好ましくは１，５００〜５０，０００、より好ましくは２，０００〜２０，０００であり、重量平均分子量（Ｍｗ）は好ましくは６，０００〜１００，０００、より好ましくは１０，０００〜９０，０００であることが良い。
【０１３６】
本発明のトナーは、その帯電性をさらに安定化させる為に必要に応じて荷電制御剤を用いることができる。荷電制御剤は、結着樹脂１００質量部当り０．５〜１０質量部使用するのが好ましい。０．５質量部未満となる場合には、十分な帯電特性が得られない場合があり好ましくなく、１０質量部を超える場合には、他材料との相溶性が悪化したり、低湿下において帯電過剰になったりする場合があり好ましくない。
【０１３７】
荷電制御剤としては、以下のものが挙げられる。
【０１３８】
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。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。
【０１３９】
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。
【０１４０】
本発明において、必要に応じて一種又は二種以上の離型剤を、トナー粒子中に含有させてもかまわない。離型剤としては次のものが挙げられる。
【０１４１】
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脂肪族炭化水素系ワックス、また、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。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。
【０１４２】
離型剤の量は、結着樹脂１００質量部あたり０．１〜２０質量部、好ましくは０．５〜１０質量部が好ましい。
【０１４３】
また、これらの離型剤は、通常、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、混練時に混合する方法で結着樹脂に含有させることができる。
【０１４４】
本発明のトナーに使用される無機微粉体は、トナー粒子に外添することにより、流動性が添加前後を比較すると増加し得るものである。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末の如きフッ素系樹脂粉末；湿式製法シリカ、乾式製法シリカの如き微粉末シリカ、微粉末酸化チタン、微粉末アルミナ、それらをシランカップリング剤、チタンカップリング剤、シリコーンオイルにより表面処理を施した処理シリカ等がある。
【０１４５】
好ましい流動性向上剤としては、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、いわゆる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水素焔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。
ＳｉＣｌ₂＋２Ｈ₂＋Ｏ₂→ＳｉＯ₂＋４ＨＣｌ
【０１４６】
この製造工程において、塩化アルミニウム又は塩化チタン等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、シリカとしてはそれらも包含する。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。
【０１４７】
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。
【０１４８】

【０１４９】
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に疎水化処理した処理シリカ微粉体がより好ましい。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。
【０１５０】
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等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。
【０１５１】
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、ρ−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ある。さらに、ジメチルシリコーンオイルの如きシリコーンオイルが挙げられる。これらは１種あるいは２種以上の混合物で用いられる。
【０１５２】
流動性向上剤は、ＢＥＴ法で測定した窒素吸着による比表面積が３０ｍ²／ｇ以上、好ましくは５０ｍ²／ｇ以上のものが良好な結果を与える。トナー１００質量部に対して流動性向上剤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。０．０１質量部未満となる場合には、求める効果としての流動性向上が達成できない場合があり好ましくなく、８質量部超えとなる場合には、カブリが悪化する場合があり、好ましくない。
【０１５３】
本発明のトナーには、研摩効果に加え、帯電性付与性及び流動性付与、クリーニング助剤として、上述以外の無機微粉体を添加しても良い。無機微粉体は、トナー粒子に外添することにより、添加前後を比較するとより効果が増加し得るものである。本発明に用いられ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。
【０１５４】
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（ＳｒＴｉＯ₃）及びチタン酸カルシウム（ＣａＴｉＯ₃）、ケイ酸ストロンチウム（ＳｒＳｉＯ₃）、チタン酸バリウム（ＴｉＢａＯ₃）が好ましい。
【０１５５】
本発明で使用する無機微粒子は、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。
【０１５６】
本発明における無機微粒子は、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。
【０１５７】
本発明の磁性黒色トナーの製造方法としては、先に述べた、一般的な製造装置を用いて、所望の円形度及び粒子径が得られれば、特に限定するものでは無い。
【０１５８】
具体的には、結着樹脂と磁性体、又はその他の添加剤として電荷制御剤や離型剤等を加えて、ヘンシェルミキサー、ボールミルの如き混合機により乾式混合し、ニーダー、ロールミル、エクストルーダーの如き熱混練機を用いて溶融・混練して樹脂類を互いに相溶せしめ、溶融混練物を冷却固化後に固化物を粗粉砕し、得られた租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た後、流動化剤や研磨剤等の無機微粉体を外添混合することで本発明のトナーを得る事が出来る。
【０１５９】
又、本発明の磁性黒色トナーは、粗粉砕品を微粉砕する際の粉砕条件を工夫するか、或いは、微粉砕後又は分級後に表面改質装置等を用いることにより、所望の円形度を達成する事が出来るが、生産性及び粉砕条件の設定等が容易に出来る、機械式粉砕機を使用する事がより好ましい。
【０１６０】
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、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、装置内温度を下げる事で容易に円形度をコントロールする事が出来る。
【０１６１】
次に、以下の実施例中で測定した各種物性データの測定方法に関して以下に説明する。
【０１６２】
（１）粒度分布の測定
粒度分布については、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った。
【０１６３】
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。測定法としては前記電解水溶液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、個数分布とを算出した。それから体積分布から求めた重量基準の重量平均径を求める。
【０１６４】
（２）ワックスの融点測定
示差熱分析測定装置（ＤＳＣ測定装置），ＤＳＣ−７（パーキンエルマー社製）を用い測定する。測定はＡＳＴＭ Ｄ３４１８−８２に準じておこなう。測定試料２〜１０ｍｇを精秤して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。この昇温過程で、温度３０〜２００℃の範囲におけるメインピークの吸熱ピークが得られる。この吸熱メインピークの温度をもってワックスの融点とする。
【０１６５】
（３）ガラス転移温度（Ｔｇ）の測定
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。
【０１６６】
測定試料は５〜２０ｍｇ、好ましくは１０ｍｇを精密に秤量する。
【０１６７】
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。
【０１６８】
この昇温過程で、温度４０〜１００℃の範囲におけるメインピークの吸熱ピークが得られる。
【０１６９】
このときの吸熱ピークが出る前と出た後のベースラインの中間点の線と示差熱曲線との交点を本発明におけるガラス転移温度Ｔｇとする。
【０１７０】
（４）結着樹脂原料の分子量分布の測定
ＧＰＣによるクロマトグラムの分子量は次の条件で測定される。
【０１７１】
４０℃のヒートチャンバー中でカラムを安定化させ、この温度におけるカラムに、溶媒としてテトラヒドロフラン（ＴＨＦ）を毎分１ｍｌの流速で流す。試料をＴＨＦに溶解後０．２μｍフィルターで濾過し、その濾液を試料として用いる。試料濃度として０．０５〜０．６質量％に調整した樹脂のＴＨＦ試料溶液を５０〜２００μｌ注入して測定する。試料の分子量測定にあたっては、試料の有する分子量分布を、数種の単分散ポリスチレン標準試料により作製された検量線の対数値とカウント数との関係から算出する。検量線作成用の標準ポリスチレン試料としては、例えば、Ｐｒｅｓｓｕｒｅ Ｃｈｅｍｉｃａｌ Ｃｏ．製あるいは、東洋ソーダ工業社製の分子量が６×１０²，２．１×１０³，４×１０³，１．７５×１０⁴，５．１×１０⁴，１．１×１０⁵，３．９×１０⁵，８．６×１０⁵，２×１０⁶，４．４８×１０⁶のものを用い、少なくとも１０点程度の標準ポリスチレン試料を用いるのが適当である。検出器にはＲＩ（屈折率）検出器を用いる。
【０１７２】
カラムとしては、１０³〜２×１０⁶の分子量領域を適確に測定するために、市販のポリスチレンゲルカラムを複数組合せるのが良く、例えば、Ｗａｔｅｒｓ社製のμ−ｓｔｙｒａｇｅｌ ５００，１０³，１０⁴，１０⁵の組合せや、昭和電工社製のｓｈｏｄｅｘ ＫＡ−８０１，８０２，８０３，８０４，８０５，８０６，８０７の組合せが好ましい。
【０１７３】
（５）磁性トナーから酸化鉄粒子を回収する方法
使用している結着樹脂に対して、良溶媒を選択し、酸化鉄粒子は、磁石を用いて分離する。
【０１７４】
この操作を複数回繰り返す事により、磁性トナーから酸化鉄粒子を回収する。尚、回収した酸化鉄粒子は加温する事無く、減圧乾燥又は自然乾燥により溶媒除去を行う。
【０１７５】
【実施例】
次に、本発明の実施例及び比較例を挙げて本発明を更に詳細に説明する。
【０１７６】
（酸化鉄粒子の製造例１：Ｍ−１）
２．０ｍｏｌ／ｌを含む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８．５リットルを、ＰＨ１、温度５０℃の条件下で混合させ、十分撹拌する。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リットルを混合して水酸化第一鉄スラリーを得る。この水酸化第一鉄スラリーをＰＨを１２に維持し、８５℃にて空気を吹き込み第一の酸化反応を行った。次いで、Ｆｅ²⁺１．５ｍｏｌ／ｌを含む硫酸第一鉄水溶液中に、Ｚｎ²⁺０．５ｍｏｌ／ｌとなるように硫酸亜鉛を添加した水溶液２．５ｌを加え、再び空気を吹き込み第ニの酸化反応を行った。次いで、Ｆｅ²⁺１．１ｍｏｌ／ｌを含む硫酸第一鉄水溶液中に、Ｓｉ⁴⁺０．６ｍｏｌ／ｌとなるように珪酸ナトリウムを添加した水溶液２．７ｌを加え、再び空気を吹き込み第三の酸化反応を行った。得られたマグネタイト粒子を含むスラリーを常法のろ過、洗浄、乾燥、粉砕を行ない、酸化鉄粒子（Ｍ−１）を得た。
【０１７７】
得られた酸化鉄粒子は、下記に示す方法にて分析し、表−１のデーターを得た。
【０１７８】
（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。
【０１７９】
（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。
【０１８０】
（ｃ）表面／内部ＦｅＯ比
３．８ｌの脱イオン水に試料２５ｇを加え、ウオーターバスで３５〜４０℃を保ちながら、
撹拌速度２００ｒｐｍで撹拌する。このスラリー中に特急塩酸試薬４２４ｍｌを溶解した塩酸水溶液（脱イオン水）１２５０ｍｌを加え、溶解を開始する。
【０１８１】
溶解開始から全て溶解して透明になるまで、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、ろ液を採取する。
【０１８２】
採取したろ液の内、２５ｍｌをＩＣＰによって鉄元素の定量を行う。
【０１８３】
鉄元素溶解率（％）は下記式（１０）にて算出する。
【０１８４】
【数３】

【０１８５】
各サンプルのＦｅＯ含有量は、残りのろ液２５ｍｌに脱イオン水約７５ｍｌを加えて試料を調整して、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て、０．１Ｎ重クロム酸カリウムを用いて酸化還元滴定し、該試料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（１１）によりＦｅＯの鉄元素に対する比率（質量％）を求めた。
【０１８６】
【数４】

【０１８７】
粒子表面から１０質量％中における総Ｆｅ量に対するＦｅＯの割合及び残りの９０質量％中における総Ｆｅ量に対するＦｅＯの割合は、各部位に含有されるＦｅＯ含有量を各部位に含有されるＦｅ量に対する割合（質量％）で求めた。そして、下記式（１２）にて表面／内部ＦｅＯ比を求めた。
【０１８８】
【数５】

【０１８９】
（ｄ）酸化鉄粒子中のＴｉ、Ｚｎ、Ｓｉ及びその他の金属元素の含有量測定
試料を溶解して、プラズマ発光分析（ＩＣＰ）にて、各元素を測定した。
【０１９０】
（ｅ）酸化鉄粒子のＺｎ／Ｓｉ被膜の確認
５ｌビーカーに３ｌの脱イオン水を入れ、５０〜６０℃に加温する。約４００ｍｌの脱イオン水でスラリーとした酸化鉄粒子２５ｇを約３００ｍｌの脱イオン水で水洗しながら、該脱イオン水とともに５ｌビーカー中へ加える。
【０１９１】
次いで、温度を５０℃、撹拌スピードを２００ｒｐｍに保ちながら、特級塩酸を加え、酸化鉄の溶解を開始する。溶解開始から、すべて溶解するまで（透明になるまで）の間に数回、約２０ｍｌサンプリングし、０．２μｍメンブランフィルターでろ過し、ろ液を採取して分析用サンプルとする。このろ液をＩＣＰによって鉄、亜鉛、珪素の各元素を定量する。
【０１９２】
下記式（１３）により、各試料ごとの鉄元素溶解率が計算される。
【０１９３】
【数６】

【０１９４】
更に下記式（１４），（１５）により、各試料ごとの珪素元素及び亜鉛元素の含有率が計算される。
【０１９５】
【数７】

【０１９６】
【数８】

【０１９７】
各サンプルにおける、鉄元素溶解率−珪素元素含有率及び鉄元素溶解率−亜鉛元素含有率をプロットし曲線を得る事で、酸化鉄表層近傍に存在する珪素元素及び亜鉛元素の量を確認する。（鉄元素溶解率が少ない段階で珪素元素及び亜鉛元素含有率が高いと言う事は、表層に被膜成形が達成されたと判断する。）
【０１９８】
被膜成形判断は下記式（１６）、（１７）より計算した、鉄元素溶解率１０％における、各亜鉛元素及び珪素元素の含有率とした。
【０１９９】
【数９】

【０２００】
【数１０】

【０２０１】
（ｆ）酸化鉄粒子の粉体抵抗（電気抵抗）測定
試料１０ｇを薬包紙に秤量し、測定セルに試料を入れ、油圧シリンダーにより、成形圧６００ｋｇ／ｃｍ³（ゲージ圧）にて成形する。
【０２０２】
圧力を解放後、抵抗計をセットし、油圧シリンダーにより測定圧１５０ｋｇ／ｃｍ³（ゲージ圧）を加える。
【０２０３】
抵抗計スイッチを入れ、測定を開始し、３分後の測定値を読み取る。
【０２０４】
次に、試料の成形品を試料セルより抜き出し、成形厚み（ｃｍ）をノギスにて測定する。
【０２０５】
下記計算式（１８）にて粉体抵抗（電気抵抗）（Ω・ｃｍ）を算出する。
【０２０６】
【数１１】

【０２０７】
（測定器具）
抵抗計：横河電気製 ＹＥＷ ＭＯＤＥＬ ２５０６Ａ ＤＩＧＩＴＡＬ ＭＡＬＴＩＭＥＴＯＲ
油圧シリンダー：理研製機（株）理研 ＰＯＷＥＲ ＭＯＤＥＬ Ｐ−１８ ７００ｋｇ／ｃｍ²
【０２０８】
（酸化鉄粒子の製造例２〜１０：Ｍ−２〜Ｍ−１０）
酸化鉄製造例１における硫酸チタニル及び硫酸亜鉛、珪酸ナトリウムの添加量を変更した以外は同様にして、酸化鉄粒子（Ｍ−２）、（Ｍ−３）、（Ｍ−４）、（Ｍ−５）、（Ｍ−６）、（Ｍ−７）、（Ｍ−８）、（Ｍ−９）、（Ｍ−１０）を得た。得られた酸化鉄粒子の分析結果は表−１となった。
【０２０９】
（酸化鉄粒子の製造例１１〜１６：Ｍ−１１〜Ｍ−１６）
酸化鉄製造例１における、空気流入量及び反応温度、反応時間を変更する以外は同様にして、酸化鉄粒子（Ｍ−１１）、（Ｍ−１２）、（Ｍ−１３）、（Ｍ−１４）、（Ｍ−１５）、（Ｍ−１６）、を得た。得られた酸化鉄粒子の分析結果は表−１となった。
【０２１０】
（酸化鉄粒子の製造例１７：Ｍ−１７）
酸化鉄製造例１において第一反応終了後の硫酸亜鉛、珪酸ナトリウムを添加した第二、第三の反応を行わなかった以外は同様にして、酸化鉄粒子（Ｍ−１７）を得た。得られた酸化鉄粒子の分析結果は表−１となった。
【０２１１】
（酸化鉄粒子の製造例１８：Ｍ−１８）
酸化鉄製造例１における、硫酸チタニル水溶液を添加しせず、硫酸亜鉛、珪酸ナトリウムは同様に添加するが、第二、第三の反応において、添加方法、反応時ＰＨ、反応時間、反応温度を変更することにより、酸化鉄粒子（Ｍ−１８）を得た。得られた酸化鉄粒子の分析結果は表−１となった。
【０２１２】
（酸化鉄粒子の製造例１９：Ｍ−１９）
酸化鉄製造例１において硫酸チタニル水溶液、硫酸亜鉛、珪酸ナトリウムをを添加しなかった以外は同様にして、酸化鉄粒子（Ｍ−１９）を得た。得られた酸化鉄粒子の分析結果は表−１となった。
【０２１３】
（酸化鉄粒子の製造例２０〜２４：Ｍ−２０〜Ｍ−２４）
酸化鉄製造例１９における、空気流入量及び反応温度、反応時間を変更する以外は同様にして、酸化鉄粒子（Ｍ−２０）、（Ｍ−２１）、（Ｍ−２２）、（Ｍ−２３）、（Ｍ−２４）を得た。得られた酸化鉄粒子の分析結果は表−１となった。
【０２１４】
（酸化鉄粒子の製造例２５：Ｍ−２５）
２．０ｍｏｌ／ｌを含む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８．５リットルを、ＰＨ２．５、温度７５℃の条件下で混合させ、十分撹拌する。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リットルを混合して水酸化第一鉄スラリーを得る。この水酸化第一鉄スラリーをＰＨを１２に維持し、８５℃にて空気を吹き込み第一の酸化反応を行った。次いで、Ｆｅ²⁺１．５ｍｏｌ／ｌを含む硫酸第一鉄水溶液中に、Ｚｎ²⁺０．５ｍｏｌ／ｌとなるように硫酸亜鉛を添加した水溶液２．５ｌを加え、再び空気を吹き込み第ニの酸化反応を行った。次いで、Ｆｅ²⁺１．１ｍｏｌ／ｌを含む硫酸第一鉄水溶液中に、Ｓｉ⁴⁺０．６ｍｏｌ／ｌとなるように珪酸ナトリウムを添加した水溶液２．７ｌを加え、再び空気を吹き込み第三の酸化反応を行った。得られたマグネタイト粒子を含むスラリーを常法のろ過、洗浄、乾燥、粉砕を行ない、酸化鉄粒子（Ｍ−２５）を得た。得られた酸化鉄粒子の分析結果は表−１となった。
【０２１５】
＜実施例１＞
・結着樹脂（ポリエステル樹脂）： １００質量部
（Ｔｇ５８℃、酸価２２ｍｇＫＯＨ／ｇ、水酸基価３０ｍｇＫＯＨ／ｇ、分子量：Ｍｐ６５００、Ｍｎ３０００、Ｍｗ５２０００）
・酸化鉄粒子（Ｍ−１）： ９０質量部
・アゾ系鉄錯体化合物： ２質量部
・低分子量エチレン−プロピレン共重合体： ３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１５０℃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。
【０２１６】
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は−１０℃、出口温度は４８℃となるように粉砕し、重量平均径が６．５μｍであり、粒径４．０μｍ以下の粒子が５４個数％、且つ粒径１０．１μｍ以上の粒子を５．２体積％含有する微粉砕品を得た。
【０２１７】
次いで、風力分級機で分級することで、重量平均径が６．５μｍであり、粒径４．０μｍ以下の粒子が２０．１個数％、且つ粒径１０．１μｍ以上の粒子を３．６体積％含有する分級品（Ａ−１）を得た。
【０２１８】
この分級品Ａ−１ １００質量部に対して、疎水性シリカ微粉体（ＢＥＴ２００ｍ²／ｇ）１．２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（Ｔ１）とした。
【０２１９】
このトナーは重量平均径が６．５μｍであり、粒径４．０μｍ以下の粒子が２１．０個数％、且つ粒径１０．１μｍ以上の粒子を３．５体積％含有し、ＦＰＩＡ １０００にて測定した結果、平均円形度が０．９５５であり、円形度ａ＝０．９００以上の粒子が９６．１個数％、円形度ａ＝０．９５０以上の粒子が７８．６個数％、であった。
【０２２０】
又、３μｍ以下の粒子をカット前（全粒子）粒子濃度Ａは１５５１２．３個数／μｌであり、３μｍ以上の測定粒子濃度Ｂは１３５１１．７個数／μｌであった。
【０２２１】
（評価−１：）
評価用トナー（Ｔ１）を３８０ｇキヤノン製ＩＲ６０００複写機用現像器に入れ、高温高湿室（３２．５℃／８５％）に一晩（１２時間以上）放置する。現像器の重量を測定後、ＩＲ６０００へ現像器を設置し、現像スリーブを３分間回転させた。この時、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、重量を測定しておく。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（Ｔ１）の転写率は９１％となった。
【０２２２】
転写率は以下の計算式で算出した。
【０２２３】
【数１２】

【０２２４】
（評価−２）
評価用トナー（Ｔ１）を用いて、ＩＲ６０００内の転写前帯電器（ポスト帯電器）を取り外した以外は、評価−１と全く同じ方法で転写率測定を実施した。評価用トナー（Ｔ１）の転写率は８７％となった。
【０２２５】
（評価−３）
上記の転写率を測定した後、複写機を、常温低湿室（２３℃／５０％）へ移した後、現像器へ評価用トナー（Ｔ１）を本体設置モードにて供給した後、印字比率４％のテストチャートを用いて、２０００枚画出しを行い、べた黒画像の透過濃度が１．６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。
【０２２６】
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０．４２、ｂ値が０．０８、Ｌ値が２０．２となった。又、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。
評価レベルは以下に示す。
◎ ：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
×××：１０人全員が赤味が強いと判定
【０２２７】
（評価−４）
評価用トナー（Ｔ１）を３８０ｇキヤノン製ＩＲ６０００複写機用現像器に入れ、高温乾燥機（４５℃）に３０日間放置する。複写機を、常温低湿室（２３℃／５０％）へ設置後、上記現像器を本体に設置して、３分間空回転を実施する。印字比率４％のテストチャートを用いて、５００枚画出しを行い、べた黒画像の透過濃度が１．６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、評価−３と同様に色味評価を実施した。
【０２２８】
その結果、ａ値が０．４４、ｂ値が０．１２、Ｌ値が２１．２となった。又、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。
【０２２９】
（評価−５）
評価用トナー（Ｔ１）を用いて、キヤノン製ＩＲ６０００複写機を、常温低湿室（２３℃／５％）へ設置後、現像器を機外に取り出して５日間放置した後、ＩＲ６０００へ現像器を設置し、現像スリーブを１分間回転させた。印字比率３％のテストチャートを用いて、１０００枚画出しを行い、テストチャート上の白部のカブリと文字周辺へのトナー飛び散り具合にて画質評価した。カブリは初期から１０００枚目まで０．３％未満であり問題の無いレベルとなった。又、文字周辺の飛び散りに関しても、ルーペで拡大して目視確認したが、殆ど無い状態だった。
【０２３０】
評価レベルは以下に示す。
【０２３１】
カブリ測定用反射測定機ＲＥＦＬＥＣＴＭＥＴＥＲ（東京電色（株））にて、上記の画像の白部及び未使用紙の反射率を測定し、両者の差をカブリとする。
未使用紙反射率−画像白部の反射率＝カブリ％
◎ ：カブリ０．３％未満
○ ：カブリ０．３〜１．０％
△ ：カブリ１．０〜２．０％
× ：カブリ２．０〜２．５％
××：カブリ２．５％以上
【０２３２】
文字周辺へのトナー飛び散り具合は画像上の文字をルーペにて拡大して、目視にて判断した。
◎ ：文字周辺に飛び散ったトナーが無い
○ ：文字周辺に飛び散ったトナーが極僅か確認できる
△ ：文字周辺に飛び散ったトナーが有るが、ラインははっきりしている
× ：文字周辺に飛び散ったトナーが多数存在する
××：文字周辺に飛び散ったトナーが多数存在し、ラインもはっきりしない
【０２３３】
（評価−６）
上記のカブリを測定した後、複写機を、高温高湿室（３２．５℃／８５％）へ移し、現像器を機外に取り出して２日間放置した後、ＩＲ６０００へ現像器を設置し、現像スリーブを３分間回転させた。印字比率４％のテストチャートを用いて、１０００００枚画出しを行い、テストチャート上の黒部の画像濃度を測定して、耐久時の濃度推移を確認した。結果は初期画像濃度１．４５であり、ラスト（１０万枚目）１．４３となり、ΔＤｍａｘ＝０．０２と非常に安定していた。評価レベルは以下に示す。
尚、ΔＤｍａｘ＝初期画像濃度−耐久ラスト（１０万枚目）画像濃度とした。
◎ ：ΔＤｍａｘ ０．０５ 未満
○ ：ΔＤｍａｘ０．０５〜０．１０
△ ：ΔＤｍａｘ０．１０〜０．２５
× ：ΔＤｍａｘ０．２５〜０．４０
××：ΔＤｍａｘ０．４０以上
【０２３４】
＜実施例２＞
実施例１で作成した粉体原料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１．２ｋｇ／ｈｒ、粉砕圧１．８ｋｇＰａ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６．８μｍであり、粒径４．０μｍ以下の粒子が６２個数％、且つ粒径１０．１μｍ以上の粒子を１０．１体積％含有する微粉砕品を得た。
【０２３５】
次いで、風力分級機で分級することで、重量平均径が６．６μｍであり、粒径４．０μｍ以下の粒子が２２．２個数％、且つ粒径１０．１μｍ以上の粒子を３．７体積％含有する分級品（Ａ−２）を得た。
【０２３６】
この分級品Ａ−２ １００質量部に対して、疎水性シリカ微粉体（ＢＥＴ２００ｍ²／ｇ）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質量部をヘンシェルミキサーにて外添添加して評価用トナー（Ｔ２）とした。このトナーの粒度は表−２、円形度は表−３であった。
【０２３７】
評価用トナー（Ｔ２）を実施例１と同様に評価して、表−４の結果を得た。
【０２３８】
＜実施例３＞
実施例１で作成した粉体原料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５．０ｋｇ／ｈｒ、粉砕圧５．５ｋｇＰａ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７．０μｍであり、粒径４．０μｍ以下の粒子が５５．８個数％、且つ粒径１０．１μｍ以上の粒子を９．１体積％含有する微粉砕品を得た。更に、得られた微粉砕品を６２℃の熱球形化装置を通した後、風力分級機で分級することで、重量平均径が６．８μｍであり、粒径４．０μｍ以下の粒子が１８．９個数％、且つ粒径１０．１μｍ以上の粒子を４．２体積％含有する分級品（Ａ−３）を得た。
【０２３９】
この分級品Ａ−３ １００質量部に対して、疎水性シリカ微粉体（ＢＥＴ２００ｍ²／ｇ）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質量部をヘンシェルミキサーにて外添添加して評価用トナー（Ｔ３）とした。このトナーの粒度は表−２、円形度は表−３であった。
【０２４０】
評価用トナー（Ｔ３）を実施例１と同様に評価して、表−４の結果を得た。
【０２４１】
＜実施例４〜１４＞
実施例１で使用した酸化鉄粒子（Ｍ−１）の替わりに、酸化鉄粒子（Ｍ−２）、（Ｍ−３）、（Ｍ−４）、（Ｍ−５）、（Ｍ−６）、（Ｍ−９）、（Ｍ−１０）、（Ｍ−１１）、（Ｍ−１２）、（Ｍ−１３）、（Ｍ−１４）とした以外は全て同様にして、評価用トナー（Ｔ４）、（Ｔ５）、（Ｔ６）、（Ｔ７）、（Ｔ８）、（Ｔ９）、（Ｔ１０）、（Ｔ１１）、（Ｔ１２）、（Ｔ１３）、（Ｔ１４）とした。
【０２４２】
このトナーの粒度は表−２、円形度は表−３であった。
【０２４３】
評価用トナー（Ｔ４）、（Ｔ５）、（Ｔ６）、（Ｔ７）、（Ｔ８）、（Ｔ９）、（Ｔ１０）、（Ｔ１１）、（Ｔ１２）、（Ｔ１３）、（Ｔ１４）を実施例１と同様に評価して、表−４及び表−５の結果を得た。
【０２４４】
＜実施例１５〜１７＞
実施例１で作成した粉体原料Ａ（粗粉砕物）をターボ工業社製ターボミルＴ−２５０型を用い、粗砕品供給量及び機械式粉砕機内の入口温度と、出口温度を任意に調整して粒径及び円形度の異なる粉砕物を作成し、風力分級機で分級することで、分級品を得た後、この分級品 １００質量部に対して、疎水性シリカ微粉体（ＢＥＴ２００ｍ２／ｇ）０．５〜１．２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（Ｔ１５）、（Ｔ１６）、（Ｔ１７）とした。このトナーの粒度は表−２、円形度は表−３であった。評価用トナー（Ｔ１５）、（Ｔ１６）、（Ｔ１７）を実施例１と同様に評価して、表−４及び表−５の結果を得た。
【０２４５】
＜実施例１８〜２１＞
実施例１で使用した酸化鉄粒子（Ｍ−１）の添加量を５０，７５，１２０，１５０部に変更した以外は全て同様にして、評価用トナー（Ｔ１８）、（Ｔ１９）、（Ｔ２０）、（Ｔ２１）とした。
【０２４６】
このトナーの粒度は表−２、円形度は表−３であった。
【０２４７】
評価用トナー（Ｔ１８）、（Ｔ１９）、（Ｔ２０）、（Ｔ２１）を実施例１と同様に評価して、表−４及び表−５の結果を得た。
【０２４８】
＜実施例２２＞
本検討に用いた酸化鉄粒子（Ｍ−１）〜（Ｍ−２５）に含まれる、Ｍｎ、Ｍｇを定量分析した結果、全て、Ｍｎ含有量は０．０８％以下、Ｍｇ含有量は０．０５％以下であった。
【０２４９】
そこで、原料となる硫酸鉄からＭｎ、Ｍｇ含有量の多いものを選定し、実施例１と同様にして、酸化鉄粒子（Ｍ−２６）を得た。得られた酸化鉄粒子の分析結果は表−１となった。更に、酸化鉄粒子（Ｍ−２６）に含まれる、Ｍｎ、Ｍｇを定量分析した結果、Ｍｎ含有量は０．１８％、Ｍｇ含有量は０．１０％であった。
【０２５０】
実施例１と同様にして、評価用トナー（Ｔ３７）を作成した。このトナーの粒度は表−２、円形度は表−３であった。
【０２５１】
評価用トナー（Ｔ３７）を実施例１と同様に評価して、表−４及び表−５の結果を得た。
【０２５２】
＜比較例１＞
実施例１で使用した、酸化鉄粒子（Ｍ−１）の替わりに、酸化鉄粒子（Ｍ−１９）とした以外は全て同様にして、比較評価用トナー（Ｔ２２）を作成した。このトナーは重量平均径が６．５μｍであり、粒径４．０μｍ以下の粒子が２０．８個数％、且つ粒径１０．１μｍ以上の粒子を３．７体積％含有し、ＦＰＩＡ １０００にて測定した結果、平均円形度が０．９５１であり、円形度ａ＝０．９００以上の粒子が９６．８個数％、円形度ａ＝０．９５０以上の粒子が７８．２個数％、であった。
【０２５３】
又、３μｍ以下の粒子をカット前（全粒子）粒子濃度Ａは１４３０９．４個数／μｌであり、３μｍ以上の測定粒子濃度Ｂは１３２００．１個数／μｌであった。
【０２５４】
このトナーを実施例１と同様にして評価したところ、転写率、カブリ、飛び散り、濃度推移に関しては問題が無かったが、べた黒画像の色調を測定した結果、ａ値が０．７５、ｂ値が０．６９、Ｌ値が２３．５となり、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人中７人が黒味不十分との回答を出した。尚、実施例１にて行った、評価４に関しては、評価３の結果が××の為、実施しなかった。
【０２５５】
＜比較例２〜３＞
比較例１で使用した、酸化鉄粒子（Ｍ−１１）の替わりに、酸化鉄粒子（Ｍ−１５）、（Ｍ−１６）とした以外は全て同様にして、比較評価用トナー（Ｔ２３）、（Ｔ２４）を作成した。このトナーの粒度は表−２、円形度は表−３であった。
【０２５６】
評価用トナー（Ｔ２３）、（Ｔ２４）を実施例１と同様に評価して、表−４及び表−５の結果を得た。
【０２５７】
＜比較例４＞
比較例１で作成した、粗砕品を用いて、日本ニューマチック工業社製Ｉ−２型ミルを用い、微粉砕後の熱球形化処理をしない以外は、実施例３と同様にして、比較評価用トナー（Ｔ２５）を作成した。このトナーの粒度は表−２、円形度は表−３であった。
【０２５８】
評価用トナー（Ｔ２５）を実施例１と同様に評価して、表−４及び表−５の結果を得た。
【０２５９】
＜比較例５〜１３＞
比較例４で使用した、酸化鉄粒子（Ｍ−１１）の替わりに、酸化鉄粒子（Ｍ−７）、（Ｍ−８）、（Ｍ−１７）、（Ｍ−１８）、（Ｍ−２０）、（Ｍ−２１）、（Ｍ−２２）、（Ｍ−２３）、（Ｍ−２４）とした以外は全て同様にして、比較評価用トナー（Ｔ２６）、（Ｔ２７）、（Ｔ２８）、（Ｔ２９）、（Ｔ３０）、（Ｔ３１）、（Ｔ３２）、（Ｔ３３）、（Ｔ３４）を作成した。このトナーの粒度は表−２、円形度は表−３であった。
【０２６０】
評価用トナー（Ｔ２６）、（Ｔ２７）、（Ｔ２８）、（Ｔ２９）、（Ｔ３０）、（Ｔ３１）、（Ｔ３２）、（Ｔ３３）、（Ｔ３４）を実施例１と同様に評価して、表−４及び表−５の結果を得た。
【０２６１】
＜比較例１４＞
比較例１で使用した、酸化鉄粒子（Ｍ−１１）の替わりに、酸化鉄粒子（Ｍ−２５）とした以外は全て同様にして、比較評価用トナー（Ｔ３５）を作成した。このトナーの粒度は表−２、円形度は表−３であった。
【０２６２】
評価用トナー（Ｔ３５）を実施例１と同様に評価して、表−４及び表−５の結果を得た。
【０２６３】
＜比較例１５＞
微粉砕後に行う熱球形化処理温度を８２℃に変更した以外は全て実施例３と同様にして、比較評価用トナー（Ｔ３６）を作成した。このトナーの粒度は表−２、円形度は表−３であった。
【０２６４】
評価用トナー（Ｔ３６）を実施例１と同様に評価して、表−４及び表−５の結果を得た。
【０２６５】
【表１】

【０２６６】
【表２】

【０２６７】
【表３】

【０２６８】
【表４】

【０２６９】
【表５】

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a 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]
As electrophotography, many methods are known as described in U.S. Pat. No. 2,297,691, Japanese Patent Publication No. 42-23910 and Japanese Patent Publication No. 43-24748. Generally, a photoconductive substance is used to form an electrostatic latent image on a photoreceptor by various means, then the latent image is developed using toner, and a toner image is formed on a transfer material such as paper as necessary. After the transfer, the toner image is fixed by heating, pressure, heating pressure or solvent vapor to obtain a toner image.
[0003]
In recent years, with the multifunctionality of copiers and printers, higher image quality of copy images, and higher speeds, the performance required for toner has become more severe, and the particle size of the toner has been reduced to a fine particle size, Is required to contain no coarse particles and to be sharp with little ultrafine powder.
[0004]
Even though the resolution and sharpness of an image can be increased by making the toner finer, various problems arise.
[0005]
By reducing the particle size of the toner, the specific surface area of the toner increases and the toner charge itself can be increased, but at the same time, the width of the charge distribution increases, and the fog in which the toner is developed on the non-image area is increased. Easily occur. Further, when the toner is transferred from the photoreceptor to the transfer material, if excessively charged toner is present, a phenomenon called "scattering" occurs in which the toner scatters around characters and line images. If toner charging is not performed sufficiently for the purpose of suppressing the scattering, there is a toner that is insufficiently charged, which causes a decrease in developability and fog.
[0006]
Further, the charging characteristics of the toner are more easily affected by the environment. Attempts have been made to sharpen the toner particle size distribution for the purpose of reducing this fog, but this causes a cost increase due to a decrease in the yield in the production of the toner.
[0007]
Further, by dispersing the toner into fine particles, the dispersibility of the binder resin and other internal additives more easily affects the toner performance. In particular, in the case of a toner having iron oxide particles as magnetic powder, problems such as a reduction in image density, a reduction in durability stability, and a reduction in image quality may be caused by the dispersion state of the iron oxide particles.
[0008]
When the iron oxide particles in the 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. Therefore, when the toner is frictionally charged with the charging member (developing sleeve), the toner If there is no or very little iron oxide particles on the surface, the charge on the toner surface will increase.On the other hand, if there is an excess of iron oxide particles on the toner surface, the iron oxide particles will act as leak sites and charge the toner surface. Is lower. In this way, the width of the charge distribution is further expanded, which causes the various problems described above.
[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. . Although the dispersion of the magnetic substance in the toner can be easily made uniform by this treatment, the problem that the particle diameter of the magnetic substance is reduced to a fine particle also occurs.
[0010]
Conventionally, the blackness of iron oxide particles, particularly iron oxide particles containing FeO (or Fe2 +) such as magnetite particles, depends 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 deteriorates. It goes without saying that the deterioration with time is greatly affected by the environment in which the iron oxide particles are placed, but the fineness of the iron oxide particles promotes the deterioration of blackness.
[0011]
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.
[0012]
The role of these additional elements is to coat the particles with additional element oxides so that FeO does not directly contact the atmosphere of the outside world, or by replacing them with additional element oxides that do not reduce blackness instead of FeO. Deterioration of blackness is suppressed.
[0013]
However, in the iron oxide particles obtained by such a method, it is not enough to increase the FeO amount of the iron oxide particles themselves for the purpose of forming fine particles for the purpose of uniform dispersion in the toner particles. It is insufficient to prevent the degree of deterioration and to suppress the deterioration over time. Depending on the added element, it may affect the magnetic properties of the iron oxide particles themselves, and may cause defects related to development other than color.
[0014]
Further, when the toner image is transferred from the photoreceptor to the transfer material in the above-described image forming process, the transfer residual toner exists on the photoreceptor.
[0015]
In order to make continuous copying quickly, 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.
[0016]
To address environmental issues, it is necessary to design a main unit with a recycling system inside the main unit as a waste tonerless system.
[0017]
However, in order to achieve multifunctional copying machines and printers, high-quality copy images, and higher speeds, a fairly large-scale recycling system is required in the main body, and the copying machines and printers themselves become large. Inability to cope with miniaturization from the viewpoint of space saving. The same applies to a system in which waste toner is stored in a container or a collection box installed in the main body, or a system in which a photoconductor and a portion for collecting the waste toner are integrated.
[0018]
In order to cope with these, it is necessary to improve the transfer rate when the toner image is transferred from the photoreceptor to the transfer material.
[0019]
JP-A-9-26672 discloses a transfer efficiency improver having an average particle diameter of 0.1 to 3 μm and a BET specific surface area of 50 to 300 m.^Two/ G of hydrophobic silica fine powder to reduce the toner volume resistance, and improve the transfer efficiency by forming a thin film layer with a transfer efficiency improver on the photoreceptor. However, since the toner produced by the pulverization method has a particle size distribution, it is difficult to exert an effect uniformly on all particles, and further improvement is required.
[0020]
As a method for improving the transfer efficiency, toners obtained by manufacturing methods such as spray granulation, solution dissolution, and polymerization are disclosed in JP-A-3-84558 and JP-A-3-229268, in which the shape of the toner is approximated to a spherical shape. And JP-A-4-1766 and JP-A-4-102862. However, the production of these toners requires not only large-scale facilities, but also problems related to cleaning because the toner approaches a true sphere. Not a way.
[0021]
There is also a method of improving transfer efficiency by carrying out pre-transfer charging (post-charging) in the image forming process for the purpose of improving transfer efficiency, thereby relaxing excess charges.
[0022]
However, in the case of a magnetic black toner, scattering may be worsened by making the toner shape close to a sphere and performing pre-transfer charging (post-charging) in order to improve transfer efficiency.
[0023]
This is particularly noticeable when the ratio of the iron oxide particles present on the toner surface is non-uniform for each particle.
[0024]
Generally, as a method for producing a toner, as a raw material, a binder resin for fixing to a material to be transferred, various colorants for giving a color as a toner, and a charge control agent for giving a charge to particles are used. In a so-called one-component developing method as disclosed in JP-A-54-42141 and JP-A-55-18656, in addition to these, various magnetic materials for imparting transportability and the like to the toner itself are used. Further, if necessary, for example, other additives such as a release agent and a fluidity-imparting agent were added and dry-mixed, and thereafter, the mixture was melt-kneaded with a general-purpose kneading device such as a roll mill and an extruder, and cooled and solidified. Thereafter, the kneaded material is refined by various crushing devices such as a jet air crusher and a mechanical collision crusher, and the obtained finely crushed material is introduced into various air classifiers to classify the kneaded material. Particle size Give the collated classified product, further, adding a fluidizing agent or lubricant as necessary to dry blending, and the toner to be subjected to image formation.
[0025]
As a method of spheroidizing the magnetic black toner for the purpose of improving the transfer efficiency, the production conditions are devised when the above-mentioned kneaded material is miniaturized by various crushing devices such as a jet air crusher and a mechanical collision crusher. And a method of spheroidizing using a surface modification device after pulverization or classification.
[0026]
However, in the case of using a jet stream type pulverizer, it is necessary to reduce the processing amount by setting the pulverization conditions to soft pulverization. In addition, in the method using a surface reforming apparatus, one step is added in terms of toner production. It is necessary to take into account the deterioration of productivity and increase of equipment. From these points, it is more preferable to produce the toner using a mechanical collision type pulverizer.
[0027]
Further, in the case of the spherical fine magnetic black toner, the compatibility of the individual materials contained in the toner becomes relatively important. In particular, except for the binder resin, iron oxide which is a magnetic material material contained in a large amount is used. The properties of the particles are more severely restricted than in the past in terms of developability.
[0028]
In other words, at present, there is room for further study on the magnetic black toner having high transferability and improved transfer efficiency in order to reduce transfer residual toner on the photoconductor, which is waste toner.
[0029]
[Problems to be solved by the invention]
SUMMARY OF THE INVENTION It is an object of the present invention to provide a magnetic black toner having high transfer efficiency and little generation of waste toner.
[0030]
SUMMARY OF THE INVENTION An object of the present invention is to provide a magnetic black toner having a sufficient degree of blackness even for fine particles.
[0031]
An object of the present invention is to provide a magnetic black toner having a sufficient degree of blackness even for long-term storage.
[0032]
SUMMARY OF THE INVENTION An object of the present invention is to provide a magnetic black toner that can maintain good developability even with fine particles.
[0033]
SUMMARY OF THE INVENTION An object of the present invention is to provide a magnetic black toner which is not affected by an image-drawing environment, that is, can maintain good developability under high temperature and high humidity and normal temperature and low humidity.
[0034]
SUMMARY OF THE INVENTION It is an object of the present invention to provide a highly developable magnetic black toner with good fog and scattering even in an image forming process including pre-transfer charging (post-charging).
[0035]
An object of the present invention is to provide a high-productivity magnetic black toner that can be easily manufactured by a pulverization method.
[0036]
[Means for Solving the Problems]
In a magnetic black toner having at least a binder resin and a magnetic material,
In the toner having a weight average particle diameter (X) of 5 μm to 12 μm and a particle size of 3 μm or more, the circularity distribution based on the number (a) of circularity (a) obtained from the following equation (1) is 0. 90% by number or more of particles having a circularity (a) of .900 or more, an average circularity of 0.94 to 0.97,
Circularity a = L₀/ L (1)
[Where L₀Represents the perimeter of a circle having the same projected area as the particle image, and L represents the perimeter of the particle image. ]
And the magnetic material is
Iron oxide particles having an average particle size of 0.1 to 0.3 μm,
Containing 0.3 to 1.5 mass% titanium in terms of titanium, based on the total amount of iron oxide particles,
The ratio of the ratio (A%) of FeO to the total amount of Fe in 10% by mass from the particle surface and the ratio (B%) of FeO to the total amount of Fe in the remaining 90% by mass satisfy the following formula (2). And
0.7 ≦ A / B ≦ 1 (2)
Iron oxide particles whose particle surface is coated with a coating of iron-zinc oxide, on which a coating of iron-silicon oxide is coated,
Powder resistance (electric resistance) is 5 × 10¹~ 5 × 10^Three(Ωcm)
A black magnetic toner, wherein inorganic fine powder is present on the surface of toner particles.
[0037]
BEST MODE FOR CARRYING OUT THE INVENTION
Conventionally, it has been known that the shape of the toner affects various properties of the toner. However, the present inventors have studied the particle size and shape of the magnetic black toner manufactured by the pulverization method, It has been found that there is a close relationship between the degree of circularity of the particles and transferability, developability (image quality), and fixability.
[0038]
Further, in the case of a magnetic black toner containing a large amount of iron oxide particles, the toner which has been found to have a large effect on the properties of the iron oxide particles with respect to developability and blackness of an image is reduced in particle size. This increases the specific surface area of the toner particles. This increases the cohesiveness and adhesion of the toner. For this reason, when the toner image is transferred onto the transfer material from the photoconductor, the adhesive force acting between the photoconductor 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.
[0039]
Furthermore, in the case of a fine magnetic black toner containing a large amount of iron oxide particles, it has been found that the dispersion state of the iron oxide particles greatly contributes to the developing property such as fogging and scattering.
[0040]
In other words, in order to improve the transfer efficiency, it is important to provide a toner having a small particle size and an adhesive property equal to or higher than that of the normal particle size toner.
[0041]
Further, in order to control the dispersion of the iron oxide particles in the toner, it is important to reduce the particle diameter of the iron oxide particles themselves.
[0042]
By making the iron oxide particles themselves into fine particles, uniform dispersion in the toner can be achieved.
[0043]
However, by making the iron oxide particles finer, the above-mentioned deterioration of FeO (or Fe2 +) in the iron oxide particles is promoted, and it becomes difficult to maintain the black tint as the magnetic black toner.
[0044]
In other words, when the iron oxide particles themselves are made into fine particles for the purpose of controlling the dispersion state of the iron oxide particles in the magnetic black toner, it is necessary to further study in order to achieve both image quality and blackness as image quality. .
[0045]
Also, by making the toner spherical, it is possible to reduce the contact area between the toner and the photoreceptor and improve the transfer efficiency. However, it is very difficult to produce a spherical toner with a pulverized toner. Therefore, a method has been considered in which the corners of the pulverized toner are removed and the surface is made smoother by smoothing the surface. As a result, the transfer efficiency of the toner can be improved, but there are various problems due to the pulverization method, and further investigation is required.
[0046]
When a surface modification step is introduced after the pulverization or classification step for the purpose of spherifying the toner, the surface of the toner particles is treated with a constant heat. When iron oxide particles are used as a colorant as the magnetic black toner, the above treatment reduces the amount of iron oxide particles deposited on the toner particle surfaces, and when the toner is frictionally charged with a charging member (developing sleeve), It is likely to be excessively charged, and in particular, scattering may worsen.
[0047]
When a toner having a small particle diameter is used, dot reproducibility is improved, but fog and scattering tend to be deteriorated. This is considered to be due to the fact that toner such as fine powder and ultrafine powder and a large number of particles having a desired particle diameter are mixed in order to produce a fine particle toner from a coarsely pulverized toner having a large particle size. In other words, toners having different particle diameters have different charging characteristics and different adhesions to individual particles. For this reason, by reducing the particle size, the distribution of the charge amount of the toner becomes wider on the contrary. Further, in the case of the magnetic black toner, when the dispersion of the added iron oxide particles is non-uniform, this tendency is even more remarkable, and the effect on scattering is particularly large.
[0048]
Further, by repeatedly classifying the pulverized toner, a sharp particle size distribution can be obtained, but it is difficult to adapt to the actual toner production.
[0049]
The present inventors have proceeded with studies aimed at solving the above-mentioned problems, and have already proposed the use of fine-particle iron oxide having an increased ratio of the surface element FeO containing Ti element. This is because by increasing the amount of iron oxide particles precipitated on the surface of the toner particles, it is possible to prevent excessive charging, suppress the deterioration of scattering, and increase and stabilize the surface FeO of the iron oxide particles themselves, thereby improving image quality. Achieved the balance of blackness as quality.
[0050]
To prevent iron oxide particles from being deposited on the toner surface layer and to prevent excessive charging by providing a leak site, make the particle diameter of the iron oxide particles themselves sufficiently small, or reduce the amount of the iron oxide particles themselves added. It is achieved by increasing.
[0051]
However, in the melt-kneading process at the time of toner production, various raw materials receive a thermal history. The same applies to the iron oxide particles. In the case where the iron oxide particles are designed to be partially deposited on the surface layer of the toner as in the present invention, it is particularly necessary to consider the influence.
[0052]
Furthermore, the life cycle of iron oxide particles as a raw material for toner (the period from production to toner conversion) is estimated to be 3 to 6 months from the production scale even if it is long. However, it is necessary to determine that the life cycle of a toner is short, even one year, from the time of manufacture to the time of shipment and use in the world. In addition, when exporting from a production base to overseas, usually transport by ship is the main. In this case, in the process of loading, loading, unloading, and transporting the toner, the toner may receive a heat history that is beyond imagination, and a material design that takes into account the temporal change due to the heat history of the toner itself is required. .
[0053]
That is, according to the study of the present inventors, in the magnetic black toner manufactured by the pulverization method, by increasing the transfer rate when transferring the toner image from the photoreceptor to the transfer material, the generation of waste toner is reduced. In order to suppress the color, to achieve both image quality and blackness as image quality even under high temperature, high humidity and low humidity, and to prevent the color change of the toner itself from occurring over a long period of time, a resin or a magnetic material must be used. Wherein the magnetic material is iron oxide particles having an average particle diameter of 0.1 to 0.3 μm, and the iron oxide particles contain 0.3 to 1.5 mass% titanium in terms of titanium. The ratio of 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 (B%) of FeO to the total amount of Fe in the remaining 90% by mass is as follows:
0.7 ≦ A / B ≦ 1
And, the particle surface is an iron oxide particle coated with a film of iron-zinc oxide, and further coated with a film of iron-silicon oxide,
Powder resistance (electric resistance) is 5 × 10¹~ 5 × 10^Three(Ω · cm) to improve the dispersibility with other materials, to have a stable charge amount, and to obtain a toner having a sufficient degree of blackness, and
(2) It is important that the magnetic black toner produced by the pulverization method has a specific particle size distribution and circularity.
[0054]
More preferably, by controlling the circularity of particles having a particle diameter of 3 μm or more by controlling the toner weight average diameter and the fine powder content of 3 μm or less, the same effect can be exhibited in toners having different particle diameters.
[0055]
When a magnetic black toner having a specific circularity is manufactured, the weight average particle diameter is 5 to 12 μm, particles having a particle diameter of 4.0 μm or less are 40% by number or less, and particles having a particle diameter of 10.1 μm or more are 25% by volume. % Or less.
[0056]
In the case of a magnetic black toner having a weight average 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.
[0057]
In the case of a magnetic black toner having a weight average 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 are undesirably deteriorated. The same applies to the case of 4.0 μm or less and 10.1 μm or more.
[0058]
That is, in a toner having a weight average particle diameter of 5 to 12 μm, particles having a particle diameter of 4.0 μm or less being 40% by number or less, and particles having a particle diameter of 10.1 μm or more being 25% by volume or less, 3 μm of the toner is used. Among the above particles, the particles having a circularity a of 0.900 or more obtained by the following formula (1) have a cumulative value on a number basis of 90% or more, the average circularity is 0.94 to 0.97,
Circularity a = L₀/ L (1)
[Where L₀Represents the perimeter of a circle having the same projected area as the particle image, and L represents the perimeter of the particle image. ]
And the magnetic material is
(1) Iron oxide particles having an average particle diameter of 0.1 to 0.3 μm,
(2) containing 0.3 to 1.5 mass% titanium in terms of titanium, based on the total amount of iron oxide particles,
(3) The ratio of the ratio (A%) of FeO to the total amount of Fe in 10% by mass from the particle surface and the ratio (B%) of FeO to the total amount of Fe in the remaining 90% by mass is expressed by the following formula (2). )
0.7 ≦ A / B ≦ 1 (2)
{Circle around (4)} iron oxide particles whose surface is coated with an iron-zinc oxide film, and on which an iron-silicon oxide film is coated;
(5) Powder resistance (electric resistance) is 5 × 10¹~ 5 × 10^Three(Ω · cm) is preferable.
[0059]
When such a toner particle diameter range and circularity and specific iron oxide particles are used, the blackness, which is the image quality, is not impaired, and further, there is no color change due to aging, and the toner charge control is easy. In addition, uniform charging and durability stability can be obtained. Further, it has been found that when the circularity is as described above, the transfer efficiency is increased. This is because, in the case of the toner having the above-described circularity, the contact area between the toner particles and the photoconductor is reduced, and the adhesive force acting between the toner and the photoconductor is reduced. Further, since the specific surface area of the toner particles is reduced as compared with the toner manufactured by the conventional pulverization method, the contact area between the toner particles is reduced, and the bulk density of the toner powder becomes high, so that the toner particles can be fixed at the time of fixing. By improving the heat conduction of the above, the effect of improving the fixing property can also be obtained.
[0060]
When the number of particles having a circularity a of 0.900 or more in the particles of 3 μm or more of the magnetic black toner is less than 90% in terms of the number-based cumulative value, the contact area between the toner particles and the photoconductor increases. However, since the adhesion of the toner particles to the photoreceptor increases, sufficient transfer efficiency cannot be obtained, which is not preferable.
[0061]
Further, when the toner particle diameter is different, the charge amount and specific surface area of the toner itself are different. That is, the toner having a small particle diameter has a large content of fine powder, a high charge amount, and a large specific surface area. Conversely, a toner having a large particle size has a large coarse powder content, a low charge amount, and a small specific surface area.
[0062]
As long as the particle diameter and the circularity are within the above-mentioned ranges, there is no problem in controlling the transfer efficiency and the charge. However, in order to constantly provide the same effect to toners having different particle diameters, the details are further described as follows. It is more preferable to define a proper circularity.
[0063]
In a toner having a weight average particle diameter (X) of 5 μm to 12 μm and a particle size of 3 μm or more, the circularity distribution based on the number of circularity (a) obtained from the following equation (1) is 0. Particles having a circularity (a) of 900 or more are present in 90% by number or more;
Circularity a = L₀/ L (1)
[Where L₀Represents the perimeter of a circle having the same projected area as the particle image, and L represents the perimeter of the particle image. ]
and
a) The relationship between the cut rate Z and the toner weight average diameter (X) satisfies the following expression (3).
Cut rate Z ≦ 5.3 × X (3)
[However, the cut rate Z is the particle concentration A (number / μl) of all measurement particles measured by the flow particle image analyzer FPIA-1000 manufactured by Toa Medical Electronics, and the measurement particle concentration B (number / Μl), it is represented by the following equation (4).
[0064]
Z = (1−B / A) × 100 (4)
In addition, the number-based cumulative value Y of the particles having a circularity (a) of 0.950 or more and the toner weight average diameter X in the number-based circularity distribution of the circularity (a) of the particles of 3 μm or more of the toner. Satisfy the following expression (5).
[0065]
Number reference value of particles having a circularity of 0.950 or more Y ≧ exp5.51 × X^-0.645(5)
[However, the weight average particle diameter of the toner X: 5.0 to 12.0 μm]
Or
b) The relationship between the cut ratio Z and the toner weight average diameter (X) satisfies the following expression (6).
Cut ratio Z> 5.3 × X (6)
In addition, the number-based cumulative value Y of the particles having a circularity (a) of 0.950 or more and the toner weight average diameter X in the number-based circularity distribution of the circularity (a) of the particles of 3 μm or more of the toner. Satisfy the following expression (7).
[0066]
Number standard value of particles having a circularity of 0.950 or more Y ≧ exp5.37 × X^-0.545(7)
[However, the weight average particle diameter of the toner X: 5.0 to 12.0 μm]
Particles having a circularity a of 0.950 or more in particles of 3 μm or more of the toner are cumulative values based on the number. A) The relationship between the cut rate Z and the toner weight average diameter X is as follows.
A cut rate Z ≦ 5.3 × X, preferably satisfying an equation of 0 <cut rate Z ≦ 5.3 × X,
Number-based cumulative value Y ≧ exp5.51 × X^-0.645Is not satisfied, that is,
Number-based cumulative value Y <exp 5.51 × X^-0.645If you are satisfied with
Alternatively, particles having a circularity a of 0.950 or more in the particles of 3 μm or more of the toner are cumulative values based on the number, and b) the relationship between the cut rate Z and the toner weight average diameter X is
A cut rate Z> 5.3 × X, preferably satisfying an equation of 95 ≧ cut rate Z ≦ 5.3 × X,
Number-based cumulative value Y ≧ exp 5.37 × X^-0.545Is not satisfied, that is,
Number-based cumulative value Y <exp 5.37 × X^-0.545If you are satisfied with
Adhesion to a fixing member or the like is facilitated, the fluidity of the toner may be deteriorated, and the transfer efficiency may be reduced.
[0067]
The standard deviation SD can also be used as one measure of such a variation of the particles having each circularity. In the present invention, there is no problem if the standard deviation SD is 0.030 to 0.050.
[0068]
The average circularity in the present invention is used as a simple method for quantitatively expressing the shape of particles, and in the present invention, measurement is performed using a flow particle image analyzer FPIA-1000 manufactured by Toa Medical Electronics, The circularity of the measured particles is determined by the following equation (1), and the value obtained by dividing the sum of the circularities of all the particles measured by the following equation (8) by the total number of particles is defined as the average circularity. I do.
[0069]
Circularity a = L₀/ L (1)
[Where L₀Represents the perimeter of a circle having the same projected area as the particle image, and L represents the perimeter of the particle image. ]
[0070]
(Equation 1)

[0071]
The circularity standard deviation SD is calculated from the following equation (9), where a is the average circularity obtained by the above equations (1) and (8), ai is the circularity of each particle, and m is the number of measured particles. .
[0072]
(Equation 2)

[0073]
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.
[0074]
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, and in the present invention, for the reasons of data handling such as shortening of calculation time and simplification of calculation formula, each particle described above is used. Such a calculation method partially modified using the concept of a calculation formula using the circularity directly may be used.
[0075]
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 becomes large.
[0076]
The outline of the measurement is described in the catalog of FPIA-1000 (June 1995 edition) issued by Toa Medical Electronics Co., Ltd., the operation manual of the measuring device, and JP-A-8-136439. It is.
[0077]
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.
[0078]
Further, the constitution of a toner which is preferable for achieving the object in the present invention will be described in detail below.
[0079]
The iron oxide particles as the magnetic material used in the present invention are preferably composed mainly of magnetite having a high FeO content. In the following description, 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.
[0080]
Specifically, the magnetite particles of the present invention contain titanium in the particles, and the ratio (A%) of FeO to the total amount of Fe in 10% by mass from the particle surface and the total amount in the remaining 90% by mass. The ratio A / B to the ratio of FeO to the amount of Fe (B%) (hereinafter referred to as “surface / internal FeO ratio”) is 0.7 to 1, and the particle surface is coated with an iron-zinc oxide film. And iron oxide particles coated thereon with an iron-silicon oxide coating,
Powder resistance (electric resistance) is 5 × 10¹~ 5 × 10^Three(Ω · cm).
[0081]
The iron oxide particles obtained by the aqueous solution reaction, particularly the magnetite particles having a high FeO, are generally obtained by oxidizing a ferrous hydroxide slurry obtained by neutralizing and mixing a ferrous salt aqueous solution and an alkaline solution. Can be 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-2000-2426. (The layer near the particle 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 the weight of the present invention.)
[0082]
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.
[0083]
When the surface / internal FeO ratio is less than 0.7. The amount of FeO in the vicinity of the surface particles is not sufficient, and the blackness is low. Even if the blackness is high, the magnetite particles are poor in deterioration with time and poor in environmental resistance. 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.
[0084]
It is important that the iron oxide particles used in the present invention contain titanium in the particles, and titanium is contained in an amount of 0.3 to 1.5% by mass in terms of titanium with respect to the total amount of the iron oxide particles. It is preferable that it is contained. In the present invention, it will be described later that the fact that the titanium is contained in the magnetite particles greatly contributes to the fact that the surface / internal FeO ratio of the magnetite particles becomes 0.7 to 1. If the content is less than 0.3% by mass, the titanium content in the vicinity of the particle surface tends to be small, and it is difficult to make the surface / internal FeO ratio of the magnetite particles obtained by the aqueous solution reaction 0.7 to 1, and 1 When the content exceeds 0.5% by mass, the titanium content in the vicinity of the particle surface tends to be excessive, and the titanium content is too high, which causes other characteristics defects such as magnetic properties, blackness, and hue. Is not preferred. The titanium content is preferably set to 0.4 to 1.2% by mass in order to further reduce the titanium content and not to decrease the surface / internal FeO ratio, and to set the titanium content to 0.4 to 0% by mass. More preferably, it is set to 0.8% by mass.
[0085]
The iron oxide particles used in the present invention have a powder resistance (electric resistance) of 5 × 10¹~ 5 × 10^Three(Ω · cm) is important. 5 × 10 powder resistance^Three(Ω · cm) or more is not preferable because iron oxide particles precipitated on the surface of the toner particles may not sufficiently function as leak sites. 5 × 10¹If it is less than (Ω · cm), the resistance of the toner itself may be too low to affect the charging characteristics, which is not preferable. The powder resistance (electric resistance) is 8 × 10 to sufficiently satisfy the charging characteristics of the toner and to exhibit the effect as a leak site.¹~ 2 × 10^Three(Ω · cm) is more preferable.
[0086]
Further, the iron oxide particles used in the present invention, it is important that the particle surface is coated with an iron-zinc coating, the amount of zinc contained in the iron oxide particles, based on all iron elements, Preferably, it is contained in an amount of 0.1 to 1.6% by weight. When the zinc content is 1.6% by weight or more, the color of the magnetic substance itself may change from black to yellowish. Since the design is made to increase the FeO content of the surface layer for the purpose of ensuring the taste, the electric resistance becomes lower. When zinc is contained, the electric resistance further decreases, which may undesirably affect the charging characteristics of the toner itself. If the zinc content is less than 0.1% by weight, the formation of a film on the surface of the iron oxide particles may not be sufficiently achieved, which is not preferable.
[0087]
It is important that the iron oxide particles used in the present invention have an iron-silicon oxide coating on the particle surface, and the silicon element contained in the iron oxide particles is based on the total iron element. Is preferably contained at 0.05 to 2.0% by weight. When the silicon element content is 2.0% by weight or more, there may be a problem in hygroscopicity after long-term storage under high humidity, and the small-particle-size iron oxide particularly prevents scattering. There is a purpose, and if the resistance is excessively increased by the addition of silicon, the effect of alleviating excess charge may be undesirably reduced. When the silicon element content is less than 0.05% by weight, the fluidity of the magnetic toner may be reduced, and the resistance of the iron oxide particles, which have been reduced in resistance by coating with zinc, is sufficiently adjusted. It is not preferable because it may not be possible.
[0088]
Further, the iron oxide particles used in the present invention preferably have an average particle size of 0.1 to 0.3 μm without any problem with respect to dispersibility, blackness, etc. Further, the iron oxide particles used in the present invention In order to further exhibit the characteristics described above, the average particle diameter is preferably from 0.1 to 0.2 μm, more preferably from 0.1 to 0.15. If the average particle size is less than 0.1 μm, dispersion failure due to re-aggregation of iron oxide in the toner and the use of the iron oxide particles of the present invention may undesirably impair toner blackness. When the average particle size is more than 0.3 μm, the blackness of the toner is satisfactory, but it may cause deterioration of the dispersion in the toner particles. Precipitation cannot be sufficiently achieved, and scattering may be deteriorated, which is not preferable.
[0089]
The iron oxide particles used in the present invention may be any particles such as spherical, hexahedral, and polyhedral particles as long as they are granular particles. However, from the viewpoints of dispersibility in toner particles and blackness, there are no problems with iron oxide particles. More preferably, it is in the form of a face.
[0090]
The iron oxide particles used in the present invention are Al, P, S, Cr, Mn, and Co. It is preferable that the total content of Ni, Cu, Zn, and Mg is small. The above components are contained as inevitable components derived from raw materials during the production of magnetite particles, or are added to iron oxide particles by being added as a means for improving dispersibility and fluidity. In the iron oxide particles for use in the present invention, in consideration of controlling the surface / internal FeO ratio and maintaining high magnetic properties, the lower the content of the above components, the easier the effect is exhibited, and the lower the content of the components, the lower the content of the component. Is preferred, and more preferably 0.8% by mass.
[0091]
In particular, the total amount of Mn and Mg elements is preferably 0.20% by weight or less based on all iron elements. When the content of the Mn and Mg elements is 0.20% or more, it may be difficult to control the FeO content of the iron oxide particles, or it may cause a decrease in the magnetic properties of the iron oxide particles. Not preferred.
[0092]
The iron oxide particles used in the present invention have an 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, and the b value exceeds 0.1, the black tint of a solid black image after toner formation may be impaired, which is not preferable.
[0093]
These iron oxide particles 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.^Two/ Kg (preferably 50-100 Am^Two/ Kg), residual magnetization 2 to 20 Am^Two/ Kg is preferred.
[0094]
Iron oxide particles are used in an amount of 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 amount is less than 50 parts by mass, not only fog and scattering are deteriorated, but when the magnetic black toner is used, blackness may be insufficient, which is not preferable.
[0095]
If the amount is more than 150 parts by mass, the toner cannot fly sufficiently from the charging member (developing sleeve), which may cause a reduction in image density, which is not preferable.
[0096]
Next, 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, but a particularly preferable production method will be specifically described below.
[0097]
The iron oxide particles for use in the present invention are obtained by oxidizing a ferrous hydroxide slurry obtained by neutralizing and mixing an aqueous ferrous salt solution and an alkaline solution to produce iron oxide particles. 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 titanium salt and / or titanate does not precipitate as titanium hydroxide, and added to the ferrous salt aqueous solution. It can be produced by using a ferrous hydroxide slurry obtained by mixing.
[0098]
Here, what is important is that 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. Is added to and mixed with the aqueous ferrous salt solution.
[0099]
The reason for adjusting the pH of the aqueous ferrous salt solution to 1.5 or less and the temperature to 70 ° C. or less is to prevent the tetravalent titanium salt and / or titanate to be added from being hydrolyzed and precipitated as titanium hydroxide. Is what you do. According to this method, from the nucleation of the particles to the completion of the final particle growth, a tetravalent titanium component is uniformly contained in the particles, and Fe2 + is stably generated even on the particle surface. become.
[0100]
The added titanium salt and / or 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.
[0101]
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. Further, titanium salts used for the addition and those usable as titanates include titanium (IV) sulfate, titanium (IV) chloride, titanyl sulfate, titanyl nitrate and the like.
[0102]
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.
[0103]
The amount of the alkali solution when the ferrous hydroxide slurry is generated may be adjusted according to the shape of the iron oxide particles to be obtained. Specifically, when the pH of the ferrous hydroxide slurry is adjusted to be less than 8.0, spherical particles are obtained, and when the pH is adjusted to 8.0 to 9.5, the hexahedral particles are obtained. Is adjusted to exceed 9.5, so that octahedral particles are obtained.
[0104]
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.
[0105]
From the ferrous hydroxide slurry thus obtained, in order to obtain iron oxide particles, an oxidation reaction is performed while blowing a conventional oxygen-containing gas, preferably air, into the slurry to terminate the first oxidation reaction. . Next, a ferrous salt containing zinc was added so that the weight ratio (% by weight) of Zn / Fe in the entire iron oxide particles was 0.1 to 1.6% by weight, and the pH was 6.0 to 9%. It is adjusted to 0, the oxidation reaction is performed again, and the second oxidation reaction is terminated. Next, a ferrous salt containing a silicate is added so that the weight ratio (% by weight) of Si / Fe in the whole iron oxide particles becomes 0.05 to 2.0% by weight, and PH 6.0 to 9 is added. After the oxidation reaction is completed, the slurry after the completion of the oxidation reaction is subjected to filtration, washing, drying and pulverization processes in a usual manner.
[0106]
Examples of the binder resin used in the present invention include a vinyl resin, a polyester resin, and an epoxy resin. Among them, vinyl resins and polyester resins are more preferable in terms of chargeability and fixability.
[0107]
Examples of the vinyl resin include styrene; o-methylstyrene, m-methylstyrene, p-methylstyrene, p-methoxystyrene, p-phenylstyrene, p-chlorostyrene, 3,4-dichlorostyrene, p-ethyl Styrene, 2,4-dimethylstyrene, p-n-butylstyrene, p-tert-butylstyrene, p-n-hexylstyrene, p-n-octylstyrene, p-n-nonylstyrene, p-n-decylstyrene And styrene derivatives such as pn-dodecylstyrene; ethylenically unsaturated monoolefins such as ethylene, propylene, butylene and isobutylene; unsaturated polyenes such as butadiene; vinyl chloride, vinylidene chloride, vinyl bromide and vinyl fluoride. Vinyl halides such as vinyl acetate, vinyl propionate, and benzoate Vinyl esters such as vinyl; methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, methacryl Α-methylene aliphatic monocarboxylic esters such as phenyl acrylate, dimethylaminoethyl methacrylate and diethylaminoethyl methacrylate; methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, propyl acrylate, acrylic acid Acrylic esters such as n-octyl, dodecyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, 2-chloroethyl acrylate, phenyl acrylate; vinyl methyl ester Vinyl ethers such as vinyl ether, vinyl 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 Vinyl naphthalenes; acrylic acid or methacrylic acid derivatives such as acrylonitrile, methacrylonitrile and acrylamide; esters of α, β-unsaturated acids and diesters of dibasic acids. These vinyl monomers are used alone or in combination of two or more.
[0108]
Among these, a combination of monomers that results in a styrene copolymer or a styrene-acrylic copolymer is preferable.
[0109]
Further, a polymer or a copolymer cross-linked by a cross-linkable monomer as exemplified below may be used as necessary.
[0110]
Examples of aromatic divinyl compounds include divinylbenzene and divinylnaphthalene; examples of diacrylate compounds linked by an alkyl chain include ethylene glycol diacrylate, 1,3-butylene glycol diacrylate, and 1,4-butanediol diacrylate. Acrylates, 1,5-pentanediol diacrylate, 1,6 hexanediol diacrylate, neopentyl glycol diacrylate and the above compounds in which the acrylate is replaced by methacrylate; linked by an alkyl chain containing an ether bond Examples of the diacrylate compounds include diethylene glycol diacrylate, triethylene glycol diacrylate, tetraethylene glycol diacrylate, and polyethylene glycol # 400 diacrylate. Acrylates, polyethylene glycol # 600 diacrylate, dipropylene glycol diacrylate and methacrylates instead of the above compounds; as diacrylate compounds linked by a chain containing an aromatic group and an ether bond. For example, polyoxyethylene (2) -2,2-bis (4-hydroxyphenyl) propane diacrylate, polyoxyethylene (4) -2,2-bis (4-hydroxyphenyl) propane diacrylate and the above compounds The acrylate is replaced with methacrylate; polyester-type diacrylates include, for example, the trade name MANDA (Nippon Kayaku).
[0111]
Examples of the polyfunctional crosslinking agent include pentaerythritol triacrylate, trimethylolethane triacrylate, trimethylolpropane triacrylate, tetramethylolmethanetetraacrylate, oligoester acrylate, and acrylates of the above compounds replaced with methacrylate; triallylcia Nurate and triallyl trimellitate are exemplified.
[0112]
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 monomer components.
[0113]
Among these crosslinkable monomers, those which are preferably used from the viewpoint of fixability and offset resistance to a toner resin include an aromatic divinyl compound (particularly, divinylbenzene), a chain containing an aromatic group and an ether bond. Diacrylate compounds.
[0114]
In the present invention, a homopolymer or copolymer of a vinyl monomer, polyester, polyurethane, epoxy resin, polyvinyl butyral, rosin, modified rosin, terpene resin, phenol resin, aliphatic or alicyclic hydrocarbon resin, aromatic resin A petroleum resin or the like can be used by mixing it with the binder resin described above as necessary.
[0115]
When two or more resins are mixed and used as a binder resin, as a more preferred form, those having different molecular weights are preferably mixed at an appropriate ratio.
[0116]
The glass transition temperature of the binder resin is preferably 45 to 80 ° C, more preferably 55 to 70 ° C, the number average molecular weight (Mn) is 2,500 to 50,000, and the weight average molecular weight (Mw) is 10,000. Preferably it is ~ 1,000,000.
[0117]
As a method for synthesizing a binder resin comprising a vinyl polymer or a copolymer, a polymerization method such as a bulk polymerization method, a solution polymerization method, a suspension polymerization method, and an emulsion polymerization method can be used. When a carboxylic acid monomer or an acid anhydride monomer is used, it is preferable to use a bulk polymerization method or a solution polymerization method due to the nature of the monomer.
[0118]
One example is the following method. Using a monomer such as dicarboxylic acid, dicarboxylic anhydride or dicarboxylic acid monoester, a vinyl copolymer can be obtained by a bulk polymerization method or a solution polymerization method. In the solution polymerization method, the dicarboxylic acid or dicarboxylic acid monoester unit can be partially dehydrated by devising the conditions for distilling off the dicarboxylic acid or dicarboxylic acid monoester unit when the solvent is distilled off. Further, the vinyl copolymer obtained by the bulk polymerization method or the solution polymerization method can be further dehydrated by heat treatment. The acid anhydride can also be partially esterified with a compound such as an alcohol.
[0119]
Conversely, the vinyl copolymer obtained in this manner can be hydrolyzed to close the acid anhydride group to partially form a dicarboxylic acid.
[0120]
On the other hand, using a dicarboxylic acid monoester monomer, it is possible to obtain a dicarboxylic acid from an anhydride by subjecting a vinyl copolymer obtained by a suspension polymerization method or an emulsion polymerization method to dehydration by heat treatment and ring opening by hydrolysis treatment. it can. By using a method of dissolving a vinyl copolymer obtained by a bulk polymerization method or a solution polymerization method in a monomer and then obtaining a vinyl polymer or a copolymer by a suspension polymerization method or an emulsion polymerization method, Part of the acid anhydride can be opened to obtain a dicarboxylic acid unit. At the time of polymerization, another resin may be mixed into the monomer. The obtained resin can be esterified by acid treatment by heat treatment or by ring-opening alcohol treatment of the acid anhydride by treatment with weak alkaline water.
[0121]
Since dicarboxylic acid and dicarboxylic anhydride monomer have strong alternating polymerizability, the following method is one of the preferred methods for obtaining a vinyl copolymer in which functional groups such as anhydride and dicarboxylic acid are randomly dispersed. It is. In this method, a vinyl copolymer is obtained by a solution polymerization method using a dicarboxylic acid monoester monomer, and the vinyl copolymer is dissolved in the monomer to obtain a binder resin by a suspension polymerization method. In this method, the entire or dicarboxylic acid monoester moiety can be de-alcoholized and subjected to ring-closing anhydridation depending on the processing conditions when the solvent is distilled off after the solution polymerization, and an acid anhydride can be obtained. At the time of suspension polymerization, the acid anhydride group is hydrolytically ring-opened to obtain a dicarboxylic acid.
[0122]
The formation or disappearance of the acid anhydride can be confirmed because the infrared absorption of the carbonyl shifts to a higher wave number side than that of the acid or ester in the acid anhydride formation in the polymer.
[0123]
In the binder resin thus obtained, a carboxyl group, an anhydride group, and a dicarboxylic acid group are uniformly dispersed in the binder resin, so that good chargeability can be imparted to the toner.
[0124]
As the binder resin, the following polyester resins are also preferable.
[0125]
In the polyester resin, 45 to 55 mol% of all components are alcohol components, and 55 to 45 mol% are acid components.
[0126]
Examples of the alcohol component include ethylene glycol, propylene glycol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, diethylene glycol, triethylene glycol, 1,5-pentanediol, and 1,6-hexane. Diol, neopentyl glycol, 2-ethyl 1,3-hexanediol, hydrogenated bisphenol A, bisphenol derivative represented by the following formula (B);
[0127]
Embedded image

[0128]
A diol represented by the formula (C);
[0129]
Embedded image

[0130]
Polyhydric alcohols such as glycerin, sorbit, and sorbitan are exemplified.
[0131]
Examples of the divalent carboxylic acid containing 50 mol% or more of the total acid component include benzenedicarboxylic acids such as phthalic acid, terephthalic acid, isophthalic acid, and phthalic anhydride or anhydrides thereof; succinic acid, adipic acid, sebacic acid, and azelaic acid. Alkyl dicarboxylic acids such as acids or anhydrides thereof, and succinic acids or anhydrides further substituted with alkyl or alkenyl groups having 6 to 18 carbon atoms; unsaturated acids such as fumaric acid, maleic acid, citraconic acid and itaconic acid Examples thereof include dicarboxylic acids and anhydrides thereof, and examples of the trivalent or higher carboxylic acids include trimellitic acid, pyromellitic acid, benzophenonetetracarboxylic acid and anhydrides thereof.
[0132]
A particularly preferred alcohol component of the polyester resin is a bisphenol derivative represented by the formula (B), and an acidic component is phthalic acid, terephthalic acid, isophthalic acid or anhydride thereof, succinic acid, n-dodecenyl succinic acid or anhydride thereof. And dicarboxylic acids such as fumaric acid, maleic acid and maleic anhydride; and tricarboxylic acids such as trimellitic acid or anhydride thereof.
[0133]
This is because a toner for fixing with a heat roller using a polyester resin obtained from the acid component and the alcohol component as a binder resin has good fixability and excellent offset resistance.
[0134]
The acid value of the polyester resin is preferably 90 mgKOH / g or less, more preferably 50 mgKOH / g or less, and the OH value is preferably 50 mgKOH / g or less, more preferably 30 mgKOH / g or less. This is because the environmental dependence of the charging characteristics of the toner increases as the number of terminal groups in the molecular chain increases.
[0135]
The glass transition temperature of the polyester resin is preferably from 50 to 75 ° C, more preferably from 55 to 65 ° C, and the number average molecular weight (Mn) is preferably from 1,500 to 50,000, more preferably from 2,000 to 20. And the weight average molecular weight (Mw) is preferably from 6,000 to 100,000, more preferably from 10,000 to 90,000.
[0136]
In the toner of the present invention, a charge control agent can be used as needed to further stabilize the chargeability. It is preferable to use 0.5 to 10 parts by mass of the charge control agent per 100 parts by mass of the binder resin. If the amount is less than 0.5 parts by mass, sufficient charging characteristics may not be obtained in some cases. If the amount is more than 10 parts by mass, compatibility with other materials may be deteriorated, or the particles may be charged under low humidity. It may be excessive, which is not preferable.
[0137]
Examples of the charge control agent include the following.
[0138]
For example, an organometallic complex or a chelate compound is effective as a negative charge controlling agent for controlling the toner to negative charge. Examples 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.
[0139]
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 (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.
[0140]
In the present invention, one or more release agents may be contained in the toner particles as needed. The following are examples of the release agent.
[0141]
Oxides of aliphatic hydrocarbon waxes such as low molecular weight polyethylene, low molecular weight polypropylene, microcrystalline wax, paraffin wax, and aliphatic hydrocarbon waxes such as oxidized polyethylene wax, or block copolymers thereof; Carnauba Waxes mainly containing fatty acid esters such as wax, sasol wax and montanic acid ester wax; and those obtained by partially or entirely deoxidizing fatty acid esters such as deoxidized carnauba wax. 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; stearyl alcohol, aralkyl alcohol, behenyl alcohol, carnaubyl alcohol, and seryl alcohol And saturated alcohols such as melisyl alcohol; long-chain alkyl alcohols; polyhydric alcohols such as sorbitol; fatty acid amides such as linoleic acid amide, oleic acid amide and lauric acid amide; Saturated fatty acid bisamides such as acid amide, ethylenebislauric amide, hexamethylenebisstearic acid amide; ethylenebisoleic amide, hexamethylenebisoleic amide, N, N'-dioleyl 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 aliphatic hydrocarbon waxes grafted with vinyl monomers such as styrene and acrylic acid Waxes; also, partially 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.
[0142]
The amount of the release agent is preferably 0.1 to 20 parts by mass, and more preferably 0.5 to 10 parts by mass per 100 parts by mass of the binder resin.
[0143]
These release agents can be contained in the binder resin by dissolving the resin in a solvent, increasing the temperature of the resin solution, and mixing while stirring, or by mixing during kneading.
[0144]
The inorganic fine powder used in the toner of the present invention can be added to toner particles to increase the fluidity before and after the addition. For example, fluorine-based resin powders 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, fine-powder alumina, and a silane coupling agent thereof; Titanium coupling agents, treated silica surface-treated with silicone oil, and the like are available.
[0145]
Preferred fluidity improvers are fine powders produced by vapor phase oxidation of silicon halide compounds, and are so-called dry silica or fumed silica. For example, it utilizes the thermal decomposition oxidation reaction of silicon tetrachloride gas in an oxyhydrogen flame, and the basic reaction formula is as follows.
SiCl_Two+ 2H_Two+ O_Two→ SiO_Two+4 HCl
[0146]
In this production step, 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. I do. 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. .
[0147]
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.
[0148]

[0149]
Further, 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 is more preferable. 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.
[0150]
The hydrophobizing method is applied by chemically treating with an organic silicon compound or the like which 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.
[0151]
As organosilicon compounds, hexamethyldisilazane, trimethylsilane, trimethylchlorosilane, trimethylethoxysilane, dimethyldichlorosilane, methyltrichlorosilane, allyldimethylchlorosilane, allylphenyldichlorosilane, benzyldimethylchlorosilane, bromomethyldimethyl Chlorosilane, α-chloroethyltrichlorosilane, ρ-chloroethyltrichlorosilane, chloromethyldimethylchlorosilane, triorganosilylmercaptan, trimethylsilylmercaptan, triorganosilyl acrylate, vinyldimethylacetoxysilane, dimethylethoxysilane, dimethyldimethoxysilane, diphenyl Diethoxysilane, hexamethyldisiloxane, 1,3-divinyltetramethyldisiloxane, 1,3 Diphenyltetramethyldisiloxane and dimethylpolysiloxane containing from 2 to 12 siloxane units per molecule, each containing one hydroxyl group bonded to Si, each of the terminal units. Further, a silicone oil such as dimethyl silicone oil may be used. These may be used alone or as a mixture of two or more.
[0152]
The fluidity improver has a specific surface area of 30 m by nitrogen adsorption measured by the BET method.^Two/ G or more, preferably 50 m^Two/ 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 the fluidity improver based on 100 parts by mass of the toner. If the amount is less than 0.01 part by mass, it may not be possible to achieve the desired effect of improving the fluidity. If the amount is more than 8 parts by mass, fog may be deteriorated, which is not preferable.
[0153]
To the toner of the present invention, an inorganic fine powder other than those described above may be added as a cleaning aid in addition to a polishing effect, chargeability and fluidity, and a cleaning aid. By adding the inorganic fine powder externally to the toner particles, the effect can be more increased when compared before and after the addition. Examples of the inorganic fine powder used in the present invention include titanates and / or silicates such as magnesium, zinc, cobalt, manganese, strontium, cerium, calcium, and barium.
[0154]
In particular, strontium titanate (SrTiO.sub.2) can be more effectively used in the present invention._Three) And calcium titanate (CaTiO_Three), Strontium silicate (SrSiO_Three), Barium titanate (TiBaO)_ThreeIs preferred.
[0155]
The inorganic fine particles used in the present invention are preferably produced by, for example, a sintering method, mechanically pulverized, and then subjected to air classification to have a desired particle size distribution.
[0156]
The inorganic fine particles in the present invention are 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.
[0157]
The method for producing the magnetic black toner of the present invention is not particularly limited as long as desired circularity and particle diameter can be obtained by using the above-mentioned general production apparatus.
[0158]
Specifically, a binder resin and a magnetic substance, or a charge control agent or a release agent as another additive, and the like, and dry-mixed with a mixer such as a Henschel mixer or a ball mill, and a kneader, a roll mill, and an extruder. Melting and kneading using a heat kneading machine to make the resins compatible with each other, cooling and solidifying the melt-kneaded material, coarsely pulverizing the solidified material, and jet-milling, micron jet, IDS-type mill After crushing using a collision-type airflow crusher or a mechanical crusher such as a cryptotron, a turbo mill, and an inomizer, and obtaining the obtained finely crushed product into a desired particle size distribution using an airflow-type classifier or the like, The toner of the present invention can be obtained by externally adding and mixing an inorganic fine powder such as a fluidizing agent or an abrasive.
[0159]
Further, the magnetic black toner of the present invention achieves a desired circularity by devising pulverization conditions when finely pulverizing a coarsely pulverized product, or by using a surface reforming device after fine pulverization or classification. However, it is more preferable to use a mechanical pulverizer that can easily set productivity and pulverization conditions.
[0160]
Specifically, by using a mechanical pulverizer, when it is desired to increase the circularity of the toner, the load in the apparatus is increased, the temperature in the apparatus is increased, and conversely, when it is desired to decrease the circularity of the toner. Can easily control the degree of circularity by reducing the load in the device and the temperature in the device.
[0161]
Next, a method for measuring various physical property data measured in the following examples will be described below.
[0162]
(1) Measurement of particle size distribution
The particle size distribution can be measured by various methods. In the present invention, the measurement was carried out using a Coulter counter multisizer.
[0163]
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. As a measuring method, 0.1 to 5 ml of a surfactant (preferably an alkylbenzene sulfonate) is added as a dispersant to 100 to 150 ml of the aqueous electrolytic 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 with an ultrasonic disperser, and a multi-sizer 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 were measured, and the volume distribution and the number distribution were calculated. Then, the weight-based weight average diameter determined from the volume distribution is determined.
[0164]
(2) Measurement of melting point of wax
The measurement is performed using a differential thermal analysis measurement device (DSC measurement device), DSC-7 (manufactured by PerkinElmer). The measurement is performed according to ASTM D3418-82. A sample of 2 to 10 mg is precisely weighed and placed in an aluminum pan, and an empty aluminum pan is used as a reference, and the temperature is measured at a temperature rising rate of 10 ° C./min at room temperature and normal humidity using an empty aluminum pan as a reference. I do. In this heating process, an endothermic peak of a main peak in a temperature range of 30 to 200 ° C. is obtained. The temperature of the endothermic main peak is defined as the melting point of the wax.
[0165]
(3) Measurement of glass transition temperature (Tg)
It is measured according to ASTM D3418-82 using a differential scanning calorimeter (DSC measuring device) and DSC-7 (manufactured by PerkinElmer).
[0166]
The measurement sample is precisely weighed in an amount of 5 to 20 mg, preferably 10 mg.
[0167]
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.
[0168]
In this heating process, an endothermic peak of a main peak in a temperature range of 40 to 100 ° C. is obtained.
[0169]
The intersection of the line at the midpoint of the baseline before and after the endothermic peak appears and the differential heat curve is defined as the glass transition temperature Tg in the present invention.
[0170]
(4) Measurement of molecular weight distribution of binder resin raw material
The molecular weight of the chromatogram by GPC is measured under the following conditions.
[0171]
The column is stabilized in a 40 ° C. heat chamber and tetrahydrofuran (THF) is passed through the column at this temperature as a solvent at a flow rate of 1 ml per minute. After dissolving the sample in THF, the solution is filtered through a 0.2 μm filter, and the filtrate is used as a sample. The measurement is performed by injecting 50 to 200 μl of a THF sample solution of a resin adjusted to a sample concentration of 0.05 to 0.6% by mass. In measuring the molecular weight of a sample, the molecular weight distribution of the sample is calculated from the relationship between the logarithmic value of a calibration curve prepared from several types of monodisperse polystyrene standard samples and the count number. As a standard polystyrene sample for preparing a calibration curve, for example, Pressure Chemical Co. Or Toyo Soda Kogyo Co., Ltd. has a molecular weight of 6 × 10^Two, 2.1 × 10^Three, 4 × 10^Three, 1.75 × 10^Four, 5.1 × 10^Four, 1.1 × 10^Five, 3.9 × 10^Five, 8.6 × 10^Five, 2 × 10⁶, 4.48 × 10⁶It is appropriate to use at least about 10 standard polystyrene samples. An RI (refractive index) detector is used as the detector.
[0172]
As a column, 10^Three~ 2 × 10⁶In order to accurately measure the molecular weight region of a polystyrene gel column, a plurality of commercially available polystyrene gel columns may be used in combination. For example, μ-styragel 500, 10 manufactured by Waters Inc. may be used.^Three, 10^Four, 10^FiveAnd the combination of Shodex KA-801, 802, 803, 804, 805, 806 and 807 manufactured by Showa Denko KK are preferable.
[0173]
(5) Method for recovering iron oxide particles from magnetic toner
A good solvent is selected for the binder resin used, and the iron oxide particles are separated using a magnet.
[0174]
By repeating this operation a plurality of times, iron oxide particles are collected from the magnetic toner. The solvent is removed from the recovered iron oxide particles by drying under reduced pressure or natural drying without heating.
[0175]
【Example】
Next, the present invention will be described in more detail with reference to Examples and Comparative Examples of the present invention.
[0176]
(Production Example 1 of Iron Oxide Particles: M-1)
To 50 liters of an aqueous ferrous sulfate solution containing 2.0 mol / l, 8.5 liters of a 0.14 mol / l aqueous solution of titanyl sulfate are mixed under conditions of PH1 and a temperature of 50 ° C., and sufficiently stirred. This titanium salt-containing aqueous ferrous sulfate solution and 43 liters of a 5 mol / l sodium hydroxide aqueous solution are mixed to obtain a ferrous hydroxide slurry. The ferrous hydroxide slurry was maintained at pH 12 and air was blown at 85 ° C. to perform a first oxidation reaction. Then, Fe²⁺In an aqueous ferrous sulfate solution containing 1.5 mol / l, Zn²⁺2.5 l of an aqueous solution to which zinc sulfate was added so as to be 0.5 mol / l was added, and air was blown again to perform a second oxidation reaction. Then, Fe²⁺In a ferrous sulfate aqueous solution containing 1.1 mol / l,⁴⁺2.7 l of an aqueous solution to which sodium silicate was added so as to be 0.6 mol / l was added, and air was blown again to perform a third oxidation reaction. The obtained slurry containing magnetite particles was filtered, washed, dried and pulverized in a usual manner to obtain iron oxide particles (M-1).
[0177]
The obtained iron oxide particles were analyzed by the following method, and the data shown in Table 1 were obtained.
[0178]
(A) Average particle size
A photograph was taken with a scanning electron microscope (magnification: 30,000) and calculated by Feret's diameter.
[0179]
(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.
[0180]
(C) Surface / internal FeO ratio
Add 25 g of the sample to 3.8 liters of deionized water, and maintain the temperature at 35 to 40 ° C. in a water bath.
Stir at a stirring speed of 200 rpm. 1250 ml of an aqueous hydrochloric acid solution (deionized water) in which 424 ml of an express hydrochloric acid reagent is dissolved is added to the slurry, and the dissolution is started.
[0181]
From the start of dissolution, 50 ml is sampled every 10 minutes until it is completely dissolved and clear, filtered through a 0.1 μm membrane filter, and the filtrate is collected.
[0182]
From the collected filtrate, 25 ml of the iron element is quantified by ICP.
[0183]
The iron element dissolution rate (%) is calculated by the following equation (10).
[0184]
(Equation 3)

[0185]
The FeO content of each sample was adjusted by adding about 75 ml of deionized water to the remaining 25 ml of the filtrate, adjusting the sample, adding sodium diphenylamine sulfonate as an indicator, and redoxing using 0.1 N potassium dichromate. Titration was performed, and titration was determined with the end point of the sample colored blue-violet to determine the ratio (mass%) of FeO to iron element by the following formula (11).
[0186]
(Equation 4)

[0187]
The ratio of FeO to the total amount of Fe in 10% by mass from the particle surface and the ratio of FeO to the total amount of Fe in the remaining 90% by mass are obtained by dividing the FeO content contained in each part by the Fe amount contained in each part. % (% By mass) with respect to. Then, the surface / internal FeO ratio was determined by the following equation (12).
[0188]
(Equation 5)

[0189]
(D) Content measurement of Ti, Zn, Si and other metal elements in iron oxide particles
The sample was dissolved, and each element was measured by plasma emission analysis (ICP).
[0190]
(E) Confirmation of Zn / Si coating of iron oxide particles
Add 3 liters of deionized water to a 5 liter beaker and warm to 50-60 ° C. 25 g of iron oxide particles slurried with about 400 ml of deionized water are added to a 5 l beaker with the deionized water while washing with about 300 ml of deionized water.
[0191]
Next, while maintaining the temperature at 50 ° C. and the stirring speed at 200 rpm, special grade hydrochloric acid is added to start dissolving the iron oxide. Approximately 20 ml is sampled several times from the start of dissolution until the whole is dissolved (until it becomes transparent), filtered through a 0.2 μm membrane filter, and the filtrate is collected as an analysis sample. The filtrate is quantified by ICP for each element of iron, zinc and silicon.
[0192]
The dissolution rate of iron element for each sample is calculated by the following equation (13).
[0193]
(Equation 6)

[0194]
Further, the contents of the silicon element and the zinc element for each sample are calculated by the following equations (14) and (15).
[0195]
(Equation 7)

[0196]
(Equation 8)

[0197]
In each sample, the amounts of the silicon element and the zinc element existing in the vicinity of the iron oxide surface layer are confirmed by plotting a curve obtained by dissolving the iron element-silicon element content and the iron element dissolution rate-zinc element content. (The fact that the silicon element and zinc element contents are high at a stage where the iron element dissolution rate is low indicates that the film formation on the surface layer has been achieved.)
[0198]
The coating film formation was determined based on the content of each zinc element and silicon element at an iron element dissolution rate of 10%, calculated from the following equations (16) and (17).
[0199]
(Equation 9)

[0200]
(Equation 10)

[0201]
(F) Powder resistance (electric resistance) measurement of iron oxide particles
10 g of a sample is weighed on a packaging paper, the sample is put into a measuring cell, and a molding pressure is 600 kg / cm by a hydraulic cylinder.^Three(Gauge pressure).
[0202]
After releasing the pressure, set the resistance meter and measure the pressure with a hydraulic cylinder at 150 kg / cm.^Three(Gauge pressure).
[0203]
Turn on the ohmmeter, start the measurement, and read the measured value 3 minutes later.
[0204]
Next, the molded product of the sample is extracted from the sample cell, and the molded thickness (cm) is measured with a vernier caliper.
[0205]
The powder resistance (electric resistance) (Ω · cm) is calculated by the following equation (18).
[0206]
(Equation 11)

[0207]
(measurement tool)
Resistance meter: YEWMODEL 2506A DIGITAL MALTIMETOR manufactured by Yokogawa Electric Corporation
Hydraulic cylinder: RIKEN POWER MODEL P-18 700 kg / cm^Two
[0208]
(Production Examples 2 to 10 of iron oxide particles: M-2 to M-10)
Iron oxide particles (M-2), (M-3), (M-4), and (M-) were prepared in the same manner except that the addition amounts of titanyl sulfate, zinc sulfate, and sodium silicate in Iron Oxide Production Example 1 were changed. 5), (M-6), (M-7), (M-8), (M-9) and (M-10) were obtained. Table 1 shows the analysis results of the obtained iron oxide particles.
[0209]
(Production Examples 11 to 16 of Iron Oxide Particles: M-11 to M-16)
Iron oxide particles (M-11), (M-12), (M-13), and (M-14) in the same manner as in Iron Oxide Production Example 1 except that the air inflow rate, the reaction temperature, and the reaction time were changed. ), (M-15) and (M-16). Table 1 shows the analysis results of the obtained iron oxide particles.
[0210]
(Production Example 17 of Iron Oxide Particles: M-17)
Iron oxide particles (M-17) were obtained in the same manner as in Iron Oxide Production Example 1, except that the second and third reactions in which zinc sulfate and sodium silicate were added after the completion of the first reaction were not performed. Table 1 shows the analysis results of the obtained iron oxide particles.
[0211]
(Production Example 18 of Iron Oxide Particles: M-18)
Zinc sulfate and sodium silicate were added in the same manner without adding the aqueous solution of titanyl sulfate in Iron Oxide Production Example 1, but in the second and third reactions, the addition method, PH during the reaction, reaction time, and reaction temperature were changed. By changing, iron oxide particles (M-18) were obtained. Table 1 shows the analysis results of the obtained iron oxide particles.
[0212]
(Production Example 19 of Iron Oxide Particles: M-19)
Iron oxide particles (M-19) were obtained in the same manner as in Iron Oxide Production Example 1, except that the aqueous solution of titanyl sulfate, zinc sulfate, and sodium silicate were not added. Table 1 shows the analysis results of the obtained iron oxide particles.
[0213]
(Production Examples 20 to 24 of Iron Oxide Particles: M-20 to M-24)
Iron oxide particles (M-20), (M-21), (M-22), and (M-23) were prepared in the same manner as in Iron Oxide Production Example 19 except that the air inflow rate, the reaction temperature, and the reaction time were changed. ) And (M-24). Table 1 shows the analysis results of the obtained iron oxide particles.
[0214]
(Production Example 25 of Iron Oxide Particles: M-25)
To 50 liters of an aqueous solution of ferrous sulfate containing 2.0 mol / l, 8.5 liters of an aqueous solution of 0.14 mol / l titanyl sulfate are mixed under conditions of pH 2.5 and a temperature of 75 ° C., and sufficiently stirred. This titanium salt-containing aqueous ferrous sulfate solution and 43 liters of a 5 mol / l sodium hydroxide aqueous solution are mixed to obtain a ferrous hydroxide slurry. The ferrous hydroxide slurry was maintained at pH 12 and air was blown at 85 ° C. to perform a first oxidation reaction. Then, Fe²⁺In an aqueous ferrous sulfate solution containing 1.5 mol / l, Zn²⁺2.5 l of an aqueous solution to which zinc sulfate was added so as to be 0.5 mol / l was added, and air was blown again to perform a second oxidation reaction. Then, Fe²⁺In a ferrous sulfate aqueous solution containing 1.1 mol / l,⁴⁺2.7 l of an aqueous solution to which sodium silicate was added so as to be 0.6 mol / l was added, and air was blown again to perform a third oxidation reaction. The obtained slurry containing magnetite particles was filtered, washed, dried and pulverized in a conventional manner to obtain iron oxide particles (M-25). Table 1 shows the analysis results of the obtained iron oxide particles.
[0215]
<Example 1>
・ Binder resin (polyester resin): 100 parts by mass
(Tg 58 ° C., acid value 22 mg KOH / g, hydroxyl value 30 mg KOH / g, molecular weight: Mp 6500, Mn 3000, Mw 52000)
-Iron oxide particles (M-1): 90 parts by mass
・ Azo-based iron complex compound: 2 parts by mass
-Low molecular weight ethylene-propylene copolymer: 3 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, Ikekai Tekko Co., Ltd.) set at a temperature of 150 ° C. )). The obtained kneaded material was cooled and coarsely pulverized to 1 mm or less with a hammer mill to obtain a powder raw material A (coarse pulverized material) which is a powder raw material for toner production.
[0216]
Powder material A is crushed using a turbo mill T-250 type manufactured by Turbo Kogyo Co., Ltd. so that the supply amount of the crushed product is 20 kg / hr and the inlet temperature in the mechanical crusher is -10 ° C and the outlet temperature is 48 ° C. A finely pulverized product having a weight average diameter of 6.5 μm, 54% by number of particles having a particle size of 4.0 μm or less, and 5.2% by volume of particles having a particle size of 10.1 μm or more was obtained.
[0217]
Then, by classifying with an air classifier, particles having a weight average diameter of 6.5 μm, particles having a particle diameter of 4.0 μm or less are 20.1% by number, and particles having a particle diameter of 10.1 μm or more are 3.6 volume. % Of a classified product (A-1) was obtained.
[0218]
Hydrophobic silica fine powder (BET 200m) was added to 100 parts by mass of the classified product A-1.^Two/ G) 1.2 parts by mass were externally added using a Henschel mixer to obtain a toner for evaluation (T1).
[0219]
This toner has a weight average diameter of 6.5 μm, contains 21.0% by number of particles having a particle diameter of 4.0 μm or less, and contains 3.5% by volume of particles having a particle diameter of 10.1 μm or more. As a result of the measurement, the average circularity was 0.955, 96.1% by number of particles having circularity a = 0.900 or more, and 78.6% by number of particles having circularity a = 0.950 or more. Was.
[0220]
The particle concentration A before cutting the particles having a particle size of 3 μm or less (total particles) was 155122.3 number / μl, and the measurement particle concentration B having a particle size of 3 μm or more was 13511.7 number / μl.
[0221]
(Evaluation-1 :)
380 g of the toner for evaluation (T1) is placed in a developing device for a Canon IR6000 copier, and left overnight (12 hours or more) in a high-temperature and high-humidity room (32.5 ° C./85%). After measuring the weight of the developing device, the developing device was set on the IR6000, and the developing sleeve was rotated for 3 minutes. At this time, the cleaner section and the waste toner collecting section in the main body are once removed in advance and the weight is measured. 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 (T1) was 91%.
[0222]
The transfer rate was calculated by the following formula.
[0223]
(Equation 12)

[0224]
(Evaluation-2)
The transfer rate was measured in exactly the same manner as in Evaluation-1 except that the pre-transfer charger (post-charger) in the IR6000 was removed using the evaluation toner (T1). The transfer rate of the evaluation toner (T1) was 87%.
[0225]
(Evaluation-3)
After measuring the above-described transfer rate, the copying machine was moved to a room-temperature low-humidity room (23 ° C./50%), and the evaluation toner (T1) was supplied to the developing device in the main body installation mode. Using a test chart of%, image output was performed on 2,000 sheets, the transmission density of the solid black image was adjusted to be 1.6, and three solid black images were output on A3 paper. The color tone of the output third solid black image was measured.
[0226]
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 0.42, the b value was 0.08, and the L value was 20.2. At the same time, 10 persons involved in copier development and toner development were asked to visually confirm the blackness of the measured image, and all 10 persons answered that the blackness was sufficient.
The evaluation levels are shown below.
◎: 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
×××: All 10 persons are judged to be strong reddish
[0227]
(Evaluation-4)
380 g of the evaluation toner (T1) is put in a developing device for a Canon IR6000 copying machine manufactured by Canon, and left in a high-temperature dryer (45 ° C.) for 30 days. After installing the copying machine in a room temperature and low humidity room (23 ° C./50%), the developing device is installed in the main body, and idle rotation is performed for 3 minutes. Using a test chart with a print ratio of 4%, 500 images were printed, the transmission density of the solid black image was adjusted to be 1.6, and three solid black images were output on A3 paper. The color evaluation was performed in the same manner as in the case of -3.
[0228]
As a result, the a value was 0.44, the b value was 0.12, and the L value was 21.2. At the same time, 10 persons involved in copier development and toner development were asked to visually confirm the blackness of the measured image, and all 10 persons answered that the blackness was sufficient.
[0229]
(Evaluation-5)
Using the evaluation toner (T1), a Canon IR6000 copying machine was installed in a room-temperature low-humidity room (23 ° C./5%), the developing device was taken out of the machine and left for 5 days, and then the developing device was transferred to the IR6000. And the developing sleeve was rotated for 1 minute. Using a test chart with a printing ratio of 3%, an image was printed on 1,000 sheets, and the image quality was evaluated based on the fog of white portions on the test chart and the degree of toner scattering around characters. Fog was less than 0.3% from the initial stage to the 1000th sheet, which was a level without any problem. In addition, the scattering around the characters was visually confirmed by magnifying with a magnifying glass, but there was almost no scattering.
[0230]
The evaluation levels are shown below.
[0231]
The reflectivity of the white part of the above image and the unused paper is measured by a fogging measurement reflectometer REFLECTMETER (Tokyo Denshoku Co., Ltd.), and the difference between the two is regarded as fog.
Unused paper reflectance-reflectance of image white part = fog%
◎: fog less than 0.3%
: Fog 0.3 to 1.0%
Δ: fog 1.0 to 2.0%
×: fog 2.0 to 2.5%
XX: fog 2.5% or more
[0232]
The degree of toner scattering around the characters was determined visually by enlarging the characters on the image with a loupe.
◎: No toner scattered around characters
：: Very little toner scattered around characters can be confirmed
Δ: toner scattered around characters, but lines are clear
×: Many toner particles scattered around the character
XX: Many toner particles scattered around characters and lines are not clear
[0233]
(Evaluation-6)
After measuring the above fog, the copying machine was moved to a high-temperature and high-humidity room (32.5 ° C./85%), the developing device was taken out of the device and left for 2 days, and then the developing device was installed on the IR6000. The developing sleeve was rotated for 3 minutes. Using a test chart with a printing ratio of 4%, 100,000 images were printed, the image density of the black portion on the test chart was measured, and the density transition during durability was confirmed. As a result, the initial image density was 1.45, the last (100,000th sheet) was 1.43, and ΔDmax = 0.02, which was very stable. The evaluation levels are shown below.
ΔDmax = initial image density−durable last (100,000th sheet) image density.
◎: less than ΔDmax 0.05
: ΔDmax 0.05 to 0.10
Δ: ΔDmax 0.10 to 0.25
×: ΔDmax 0.25 to 0.40
XX: ΔDmax 0.40 or more
[0234]
<Example 2>
The powder raw material A (coarse pulverized product) prepared in Example 1 was supplied to a pulverized product of 1.2 kg / hr and a pulverization pressure of 1.8 kgPa using an I-2 type mill manufactured by Nippon Pneumatic Industrial Co., Ltd. Further, the coarsely crushed toner particles which have not been crushed to a predetermined particle size are crushed again by setting them back into the crusher, and particles having a weight average diameter of 6.8 μm and a particle size of 4.0 μm or less are 62 particles. A finely pulverized product containing 10.3% by volume of particles having a number% and a particle size of 10.1 μm or more was obtained.
[0235]
Next, by classifying with an air classifier, the weight average diameter is 6.6 μm, the particles having a particle diameter of 4.0 μm or less are 22.2% by number, and the particles having a particle diameter of 10.1 μm or more are 3.7 volume. % Of a classified product (A-2) was obtained.
[0236]
Hydrophobic silica fine powder (BET 200m) was added to 100 parts by mass of the classified product A-2.^Two/ G) 1.2 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 a toner for evaluation (T2). The particle size of this toner is shown in Table-2, and the circularity is shown in Table-3.
[0237]
The evaluation toner (T2) was evaluated in the same manner as in Example 1, and the results shown in Table 4 were obtained.
[0238]
<Example 3>
The powder raw material A (coarse pulverized product) prepared in Example 1 was set to a pulverized product supply rate of 5.0 kg / hr and a pulverization pressure of 5.5 kgPa using an I-2 type mill manufactured by Nippon Pneumatic Industries, Ltd. Further, the coarsely crushed toner particles which have not been crushed to a predetermined particle size are crushed again by setting them back into the crusher, and particles having a weight average particle size of 7.0 μm and a particle size of 4.0 μm or less are 55%. A finely pulverized product containing 8.8% by number and 9.1% by volume of particles having a particle size of 10.1 μm or more was obtained. Further, the obtained finely pulverized product was passed through a thermal sphering device at 62 ° C., and then classified by an air classifier, whereby particles having a weight average diameter of 6.8 μm and a particle size of 4.0 μm or less were 18%. A classified product (A-3) containing 9.9 number% and 4.2 volume% of particles having a particle size of 10.1 μm or more was obtained.
[0239]
Hydrophobic silica fine powder (BET 200m) was added to 100 parts by mass of the classified product A-3.^Two/ G) of 1.2 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 a toner for evaluation (T3). The particle size of this toner is shown in Table-2, and the circularity is shown in Table-3.
[0240]
The evaluation toner (T3) was evaluated in the same manner as in Example 1, and the results shown in Table 4 were obtained.
[0241]
<Examples 4 to 14>
Instead of the iron oxide particles (M-1) used in Example 1, iron oxide particles (M-2), (M-3), (M-4), (M-5), (M-6) , (M-9), (M-10), (M-11), (M-12), (M-13), and (M-14), except that the toner for evaluation (T4 ), (T5), (T6), (T7), (T8), (T9), (T10), (T11), (T12), (T13), and (T14).
[0242]
The particle size of this toner is shown in Table-2, and the circularity is shown in Table-3.
[0243]
Example 1 Evaluation toners (T4), (T5), (T6), (T7), (T8), (T9), (T10), (T11), (T12), (T13), and (T14) The results were evaluated in the same manner as in Table 4 and Table 5 were obtained.
[0244]
<Examples 15 to 17>
The powder raw material A (coarse pulverized material) prepared in Example 1 was arbitrarily adjusted using a turbo mill T-250 manufactured by Turbo Kogyo Co., Ltd. to adjust the supply amount of the coarse pulverized product, the inlet temperature in the mechanical pulverizer, and the outlet temperature. After pulverized products having different particle diameters and circularities are prepared and classified by an air classifier, a classified product is obtained. Then, with respect to 100 parts by mass of the classified product, hydrophobic silica fine powder (BET 200 m2 / g) 0.5 to 1.2 parts by mass of the toner for evaluation (T15), (T16), and (T17) were externally added using a Henschel mixer. The particle size of this toner is shown in Table-2, and the circularity is shown in Table-3. The evaluation toners (T15), (T16) and (T17) were evaluated in the same manner as in Example 1, and the results shown in Tables 4 and 5 were obtained.
[0245]
<Examples 18 to 21>
Evaluation toners (T18), (T19), and (T20) in the same manner except that the addition amount of iron oxide particles (M-1) used in Example 1 was changed to 50, 75, 120, and 150 parts. , (T21).
[0246]
The particle size of this toner is shown in Table-2, and the circularity is shown in Table-3.
[0247]
The evaluation toners (T18), (T19), (T20), and (T21) were evaluated in the same manner as in Example 1, and the results shown in Tables 4 and 5 were obtained.
[0248]
<Example 22>
As a result of quantitative analysis of Mn and Mg contained in the iron oxide particles (M-1) to (M-25) used in this study, the Mn content was 0.08% or less and the Mg content was 0.1% in all cases. It was less than 05%.
[0249]
Therefore, iron sulfate having a high content of Mn and Mg was selected from iron sulfate as a raw material, and iron oxide particles (M-26) were obtained in the same manner as in Example 1. Table 1 shows the analysis results of the obtained iron oxide particles. Furthermore, as a result of quantitative analysis of Mn and Mg contained in the iron oxide particles (M-26), the Mn content was 0.18% and the Mg content was 0.10%.
[0250]
In the same manner as in Example 1, an evaluation toner (T37) was prepared. The particle size of this toner is shown in Table-2, and the circularity is shown in Table-3.
[0251]
The evaluation toner (T37) was evaluated in the same manner as in Example 1, and the results shown in Tables 4 and 5 were obtained.
[0252]
<Comparative Example 1>
A comparative evaluation toner (T22) was prepared in the same manner as in Example 1, except that iron oxide particles (M-19) were used instead of the iron oxide particles (M-1). This toner has a weight average diameter of 6.5 μm, contains 20.8% by number of particles having a particle diameter of 4.0 μm or less, and 3.7% by volume of particles having a particle diameter of 10.1 μm or more. As a result of the measurement, the average circularity was 0.951, 96.8% by number of particles having circularity a = 0.900 or more, and 78.2% by number of particles having circularity a = 0.950 or more. Was.
[0253]
The particle concentration A before cutting the particles having a size of 3 μm or less (total particles) was 14309.4 number / μl, and the measurement particle concentration B having a size of 3 μm or more was 13200.1 number / μl.
[0254]
When this toner was evaluated in the same manner as in Example 1, there was no problem with respect to the transfer rate, fog, scattering, and density transition, but as a result of measuring the color tone of a solid black image, the a value was 0.75 and the b value was 0.75. Was 0.69, and the L value was 23.5. Ten people involved in copier development and toner development visually checked the measured image for darkness. Sufficient response was given. The evaluation 4 performed in Example 1 was not performed because the result of the evaluation 3 was XX.
[0255]
<Comparative Examples 2-3>
Comparative Evaluation Toner (T23), except that iron oxide particles (M-11) and (M-16) were used instead of iron oxide particles (M-11) used in Comparative Example 1. (T24) was created. The particle size of this toner is shown in Table-2, and the circularity is shown in Table-3.
[0256]
The evaluation toners (T23) and (T24) were evaluated in the same manner as in Example 1, and the results shown in Tables 4 and 5 were obtained.
[0257]
<Comparative Example 4>
Using the coarsely crushed product prepared in Comparative Example 1 and using a Pneumatic I-2 type mill manufactured by Nippon Pneumatic Industries Co., Ltd. in the same manner as in Example 3 except that the heat spheroidizing treatment after fine pulverization was not performed. An evaluation toner (T25) was prepared. The particle size of this toner is shown in Table-2, and the circularity is shown in Table-3.
[0258]
The evaluation toner (T25) was evaluated in the same manner as in Example 1, and the results shown in Tables 4 and 5 were obtained.
[0259]
<Comparative Examples 5 to 13>
Instead of iron oxide particles (M-11) used in Comparative Example 4, iron oxide particles (M-7), (M-8), (M-17), (M-18), (M-20) ), (M-21), (M-22), (M-23), and (M-24) except that toners for comparative evaluation (T26), (T27), (T28), (T29), (T30), (T31), (T32), (T33), and (T34) were created. The particle size of this toner is shown in Table-2, and the circularity is shown in Table-3.
[0260]
The evaluation toners (T26), (T27), (T28), (T29), (T30), (T31), (T32), (T33), and (T34) were evaluated in the same manner as in Example 1 to obtain a table. -4 and Table 5 were obtained.
[0261]
<Comparative Example 14>
Comparative Evaluation Toner (T35) was prepared in the same manner except that iron oxide particles (M-25) were used instead of iron oxide particles (M-11) used in Comparative Example 1. The particle size of this toner is shown in Table-2, and the circularity is shown in Table-3.
[0262]
The evaluation toner (T35) was evaluated in the same manner as in Example 1, and the results shown in Tables 4 and 5 were obtained.
[0263]
<Comparative Example 15>
A toner for comparative evaluation (T36) was prepared in the same manner as in Example 3 except that the temperature of the thermal sphering treatment performed after the pulverization was changed to 82 ° C. The particle size of this toner is shown in Table-2, and the circularity is shown in Table-3.
[0264]
The evaluation toner (T36) was evaluated in the same manner as in Example 1, and the results shown in Tables 4 and 5 were obtained.
[0265]
[Table 1]

[0266]
[Table 2]

[0267]
[Table 3]

[0268]
[Table 4]

[0269]
[Table 5]

Claims (11)

In a magnetic black toner having at least a binder resin and a magnetic material,
In the toner having a weight average particle diameter (X) of 5 μm to 12 μm and a particle size of 3 μm or more, the circularity distribution based on the number (a) of circularity (a) obtained from the following equation (1) is 0. 90% by number or more of particles having a circularity (a) of .900 or more, an average circularity of 0.94 to 0.97,
Roundness a = L ₀ / L (1)
[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. ]
The magnetic material is iron oxide particles having an average particle diameter of 0.1 to 0.3 μm,
Containing 0.3 to 1.5 mass% titanium in terms of titanium, based on the total amount of iron oxide particles,
The ratio of the ratio (A%) of FeO to the total amount of Fe in 10% by mass from the particle surface and the ratio (B%) of FeO to the total amount of Fe in the remaining 90% by mass satisfy the following formula (2). And
0.7 ≦ A / B ≦ 1 (2)
Iron oxide particles whose particle surface is coated with a coating of iron-zinc oxide, on which a coating of iron-silicon oxide is coated,
Powder resistance (electric resistance) is 5 × 10 ^{1 to} 5 × 10 ³ (Ω · cm);
A black magnetic toner, wherein inorganic fine powder is present on the surface of toner particles. 2. The magnetic black toner according to claim 1, wherein the iron oxide particles are octahedral. 3. The magnetic black toner according to claim 1, wherein the amount of zinc contained in the iron oxide particles is 0.1 to 1.6% by weight based on the total iron element. 4. The magnetic black toner according to claim 1, wherein the amount of silicon element contained in the iron oxide particles is 0.05 to 2.0% by weight based on the total iron element. 5. The magnetic black toner according to claim 1, wherein the powder resistance (electric resistance) of the iron oxide particles is 8 * 10 < ¹ > to 2 * 10 < ³ > ([Omega] .cm). 6. The magnetic black toner according to claim 1, wherein the iron oxide particles contain titanium in an amount of 0.4 to 1.2% by mass in terms of titanium based on the total amount of the iron oxide particles. , 6. The magnetic black toner according to claim 1, wherein the Mn and Mg elements contained in the iron oxide particles are 0.20% by weight or less based on the total iron element. The magnetic black toner according to any one of claims 1 to 6, wherein 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 black toner according to any one of claims 1 to 6, wherein 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. In a toner having a weight average particle diameter (X) of 5 μm to 12 μm and a particle size of 3 μm or more, the circularity distribution based on the number of circularity (a) obtained from the following equation (1) is 0. Particles having a circularity (a) of 900 or more are present in 90% by number or more;
Roundness a = L ₀ / L (1)
[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. ]
And a) the relationship between the cut rate Z and the toner weight average diameter (X) satisfies the following expression (3), and the cut rate Z ≦ 5.3 × X (3)
[However, the cut rate Z is the particle concentration A (number / μl) of all measurement particles measured by the flow particle image analyzer FPIA-1000 manufactured by Toa Medical Electronics, and the measurement particle concentration B (number / Μl), it is represented by the following equation (4).
Z = (1−B / A) × 100 (4)
In addition, the number-based cumulative value Y of the particles having a circularity (a) of 0.950 or more and the toner weight average diameter X in the number-based circularity distribution of the circularity (a) of the particles of 3 μm or more of the toner. Satisfy the following expression (5).
Number reference value Y of particles having a circularity of 0.950 or more Y ≧ exp5.51 × X− ^0.645 (5)
[However, the weight average particle diameter of the toner X: 5.0 to 12.0 μm]
Or b) the relationship between the cut rate Z and the toner weight average diameter (X) satisfies the following equation (6), and the cut rate Z> 5.3 × X (6)
In addition, the number-based cumulative value Y and the toner weight average diameter X of the particles having a circularity (a) of 0.950 or more in the number-based circularity distribution of the circularity (a) in the particles of 3 μm or more of the toner. 10. The magnetic black toner according to claim 1, wherein the relationship satisfies the following expression (7).
Number reference value of particles having a circularity of 0.950 or more Y ≧ exp 5.37 × X ^−0.545 (7)
[However, the weight average particle diameter of the toner X: 5.0 to 12.0 μm] The toner particles are produced through a melt-kneading step, a fine pulverizing step and a classifying step, and after melt-kneading a mixture containing at least a binder resin and a colorant, and cooling the resulting kneaded material. The cooled material is coarsely pulverized by a pulverizing means, and the obtained powdery raw material composed of the coarsely pulverized material is finely pulverized to obtain 70 particles having a weight average diameter of 4 to 12 μm and a particle diameter of 4.0 μm or less. % Or less, and particles having a particle size of 10.1 μm or more produce a finely pulverized product having a volume of 20% by volume or less,
The finely pulverized material is classified into at least a fine powder, a medium powder and a coarse powder by a multi-split airflow classifier, and is produced from the classified medium powder. 11. The magnetic black toner according to any one of 1 to 10.