JP3988380B2 - Toner for developing electrostatic latent image, two-component developer, and method for producing the same - Google Patents

Description

【００５６】
【化２】

【００５７】
添加量としては、トナー全体の１〜３０質量％、好ましくは２〜２０質量％、更に好ましくは３〜１５質量％である。
【００５８】
本発明のトナーは、モノマー中に定着改良剤を溶解させたものを水中に分散し、重合させ、樹脂粒子中に上記の例示化合物を内包させた粒子を形成させ、焼成ブラック粒子とともに塩析／融着させたものが好ましい。
【００５９】
本発明に使用されるトナーは離型剤を内包した樹脂粒子を水系媒体中において融着させることが好ましい。この様に樹脂粒子中に離型剤を内包させた樹脂粒子を焼成ブラック粒子と共に水系媒体中で塩析／融着させることで、微細に離型剤が分散されたトナーを得ることができる。
【００６０】
該トナーはトナー製造時から表面に凹凸がある形状を有しており、更に、水系媒体中で融着するため、粒子間の形状や表面性に差がでることも少なく、結果として表面性が均一となりやすいために漆黒調の深みある黒を発色できるものである。
【００６１】
他の製造法として、懸濁重合法や、必要な添加剤の乳化液を加えた液中にて単量体を乳化重合し、微粒の重合粒子を製造し、その後に、有機溶媒、凝集剤等を添加して会合する方法で製造することができる。会合の際にトナーの構成に必要な離型剤や焼成ブラックなどの分散液と混合して会合させて調製する方法や、単量体中に離型剤や焼成ブラックなどのトナー構成成分を分散した上で乳化重合する方法などが挙げられる。ここで会合とは樹脂粒子及び焼成ブラック粒子が複数個融着することを示す。尚、本発明でいうところの水系媒体とは、少なくとも水が５０質量％以上含有されたものを示す。即ち、重合性単量体中に焼成ブラックや必要に応じて離型剤、荷電制御剤、更に重合開始剤等の各種構成材料を添加し、ホモジナイザー、サンドミル、サンドグラインダー、超音波分散機などで重合性単量体に各種構成材料を溶解或いは分散させる。この各種構成材料が溶解或いは分散された重合性単量体を分散安定剤を含有した水系媒体中にホモミキサーやホモジナイザーなどを使用しトナーとしての所望の大きさの油滴に分散させる。その後、攪拌機構が後述の攪拌翼である反応装置へ移し、加熱することで重合反応を進行させる。反応終了後、分散安定剤を除去し、濾過、洗浄し、更に乾燥することで本発明のトナーを調製する。
【００６２】
又、樹脂の構成としては複数の分子量の異なる樹脂を使用することが定着性の向上の観点で好ましい。特に、高分子量成分と低分子量成分を両方存在させることで、オフセット性の向上と紙等の画像形成支持体への接着性を両立することができる。トナーの樹脂の分子量は、１６０，０００〜１，０００，０００の領域にピークもしくは肩を有する高分子量成分と、１，０００〜５０，０００未満の領域にピークもしくは肩を有する低分子量成分の両成分を少なくとも含有する樹脂とする。好ましくはピーク分子量で１５，０００〜１００，０００の部分にピーク又は肩を有する中間分子量体の樹脂を使用することが好ましい。更に好ましくは２５，０００〜７５，０００の部分にピーク又は肩を有する中間分子量体の樹脂を使用することが好ましい。
【００６３】
ＧＰＣによる樹脂の分子量測定方法は、ＴＨＦを溶媒としたＧＰＣ（ゲルパーミエーションクロマトグラフィー）による測定である。即ち、測定試料０．５〜５ｍｇ、より具体的には１ｍｇに対してＴＨＦを１ｍｌ加え、室温にてマグネチックスターラーなどを用いて撹拌を行い、充分に溶解させる。次いで、ポアサイズ０．４５〜０．５０μｍのメンブランフィルターで処理した後に、ＧＰＣへ注入する。ＧＰＣの測定条件は、４０℃にてカラムを安定化させ、ＴＨＦを毎分１ｍｌの流速で流し、１ｍｇ／ｍｌの濃度の試料を約１００μｌ注入して測定する。カラムは、市販のポリスチレンジェルカラムを組み合わせて使用することが好ましい。例えば、昭和電工社製のＳｈｏｄｅｘ ＧＰＣ ＫＦ−８０１、８０２、８０３、８０４、８０５、８０６、８０７の組合せや、東ソー社製のＴＳＫｇｅｌＧ１０００Ｈ、Ｇ２０００Ｈ、Ｇ３０００Ｈ、Ｇ４０００Ｈ、Ｇ５０００Ｈ、Ｇ６０００Ｈ、Ｇ７０００Ｈ、ＴＳＫ ｇｕａｒｄ ｃｏｌｕｍｎの組合せなどを挙げることができる。又、検出器としては、屈折率検出器（ＩＲ検出器）、或いはＵＶ検出器を用いるとよい。試料の分子量測定では、試料の有する分子量分布を単分散のポリスチレン標準粒子を用いて作製した検量線を用いて算出する。検量線作製用のポリスチレンとしては１０点程度用いるとよい。
【００６４】
樹脂を構成する重合性単量体として使用されるものは、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、α−メチルスチレン、ｐ−クロロスチレン、３，４−ジクロロスチレン、ｐ−フェニルスチレン、ｐ−エチルスチレン、２，４−ジメチルスチレン、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様なスチレン或いはスチレン誘導体、メタクリル酸メチル、メタクリル酸エチル、メタクリル酸ｎ−ブチル、メタクリル酸イソプロピル、メタクリル酸イソブチル、メタクリル酸ｔ−ブチル、メタクリル酸ｎ−オクチル、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、メタクリル酸ラウリル、メタクリル酸フェニル、メタクリル酸ジエチルアミノエチル、メタクリル酸ジメチルアミノエチル等のメタクリル酸エステル誘導体、アクリル酸メチル、アクリル酸エチル、アクリル酸イソプロピル、アクリル酸ｎ−ブチル、アクリル酸ｔ−ブチル、アクリル酸イソブチル、アクリル酸ｎ−オクチル、アクリル酸２−エチルヘキシル、アクリル酸ステアリル、アクリル酸ラウリル、アクリル酸フェニル等の、アクリル酸エステル誘導体、エチレン、プロピレン、イソブチレン等のオレフィン類、塩化ビニル、塩化ビニリデン、臭化ビニル、フッ化ビニル、フッ化ビニリデン等のハロゲン系ビニル類、プロピオン酸ビニル、酢酸ビニル、ベンゾエ酸ビニル等のビニルエステル類、ビニルメチルエーテル、ビニルエチルエーテル等のビニルエーテル類、ビニルメチルケトン、ビニルエチルケトン、ビニルヘキシルケトン等のビニルケトン類、Ｎ−ビニルカルバゾール、Ｎ−ビニルインドール、Ｎ−ビニルピロリドン等のＮ−ビニル化合物、ビニルナフタレン、ビニルピリジン等のビニル化合物類、アクリロニトリル、メタクリロニトリル、アクリルアミド等のアクリル酸或いはメタクリル酸誘導体が挙げられ、これらビニル系単量体は単独或いは組み合わせて使用することができる。
【００６５】
又、樹脂を構成する重合性単量体としてイオン性解離基を有するものを組み合わせて用いることが更に好ましい。例えば、カルボキシル基、スルフォン酸基、燐酸基等の置換基を単量体の構成基として有するもので、具体的には、アクリル酸、メタクリル酸、マレイン酸、イタコン酸、ケイ皮酸、フマール酸、マレイン酸モノアルキルエステル、イタコン酸モノアルキルエステル、スチレンスルフォン酸、アリルスルフォコハク酸、２−アクリルアミド−２−メチルプロパンスルフォン酸、アシッドホスホオキシエチルメタクリレート、３−クロロ−２−アシッドホスホオキシプロピルメタクリレート等が挙げられる。
【００６６】
更に、ジビニルベンゼン、エチレングリコールジメタクリレート、エチレングリコールジアクリレート、ジエチレングリコールジメタクリレート、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メタクリレート、トリエチレングリコールジアクリレート、ネオペンチルグリコールジメタクリレート、ネオペンチルグリコールジアクリレート等の多官能性ビニル類を使用して架橋構造の樹脂とすることもできる。
【００６７】
これら重合性単量体はラジカル重合開始剤を用いて重合することができる。この場合、懸濁重合法では油溶性重合開始剤を用いることができる。この油溶性重合開始剤としては、２，２′−アゾビス−（２，４−ジメチルバレロニトリル）、２，２′−アゾビスイソブチロニトリル、１，１′−アゾビス（シクロヘキサン−１−カルボニトリル）、２，２′−アゾビス−４−メトキシ−２，４−ジメチルバレロニトリル、アゾビスイソブチロニトリル等のアゾ系又はジアゾ系重合開始剤、ベンゾイルパーオキサイド、メチルエチルケトンペルオキサイド、ジイソプロピルペルオキシカーボネート、クメンヒドロペルオキサイド、ｔ−ブチルヒドロペルオキサイド、ジ−ｔ−ブチルペルオキサイド、ジクミルペルオキサイド、２，４−ジクロロベンゾイルペルオキサイド、ラウロイルペルオキサイド、２，２−ビス−（４，４−ｔ−ブチルペルオキシシクロヘキシル）プロパン、トリス−（ｔ−ブチルペルオキシ）トリアジンなどの過酸化物系重合開始剤や過酸化物を側鎖に有する高分子開始剤などを挙げることができる。
【００６８】
又、乳化重合法を用いる場合には水溶性ラジカル重合開始剤を使用することができる。水溶性重合開始剤としては、過硫酸カリウム、過硫酸アンモニウム等の過硫酸塩、アゾビスアミノジプロパン酢酸塩、アゾビスシアノ吉草酸及びその塩、過酸化水素等を挙げることができる。
【００６９】
分散安定剤としては、燐酸三カルシウム、燐酸マグネシウム、燐酸亜鉛、燐酸アルミニウム、炭酸カルシウム、炭酸マグネシウム、水酸化カルシウム、水酸化マグネシウム、水酸化アルミニウム、メタケイ酸カルシウム、硫酸カルシウム、硫酸バリウム、ベントナイト、シリカ、アルミナ等を挙げることができる。更に、ポリビニルアルコール、ゼラチン、メチルセルロース、ドデシルベンゼンスルフォン酸ナトリウム、エチレンオキサイド付加物、高級アルコール硫酸ナトリウム等の界面活性剤として一般的に使用されているものを分散安定剤として使用することができる。
【００７０】
本発明において優れた樹脂としては、ガラス転移点が２０〜９０℃のものが好ましく、軟化点が８０〜２２０℃のものが好ましい。ガラス転移点は示差熱量分析方法で測定されるものであり、軟化点は高化式フローテスターで測定することができる。更に、これら樹脂としてはＧＰＣにより測定される分子量が数平均分子量（Ｍｎ）で１０００〜１０００００、重量平均分子量（Ｍｗ）で２０００〜１００００００のものが好ましい。更に、分子量分布として、Ｍｗ／Ｍｎが１．５〜１００、特に１．８〜７０のものが好ましい。
【００７１】
使用される凝集剤としては特に限定されるものではないが、金属塩から選択されるものが好適に使用される。具体的には、一価の金属として例えばナトリウム、カリウム、リチウム等のアルカリ金属の塩、二価の金属として例えばカルシウム、マグネシウム等のアルカリ土類の金属塩、マンガン、銅等の二価の金属の塩、鉄、アルミニウム等の三価の金属の塩等が挙げられ、具体的な塩としては、塩化ナトリウム、塩化カリウム、塩化リチウム、塩化カルシウム、塩化亜鉛、硫酸銅、硫酸マグネシウム、硫酸マンガン等を挙げることができる。これらは組み合わせて使用してもよい。これらの凝集剤は臨界凝集濃度以上添加することが好ましい。この臨界凝集濃度とは、水性分散物の安定性に関する指標であり、凝集剤を添加して凝集が発生する濃度を示すものである。この臨界凝集濃度は、乳化された成分及び分散剤自体によって大きく変化するものである。例えば、岡村誠三他著「高分子化学 １７、６０１（１９６０）日本高分子学会編」等に記述されており、詳細な臨界凝集濃度を求めることができる。又、別な手法として、目的とする粒子分散液に所望の塩を濃度を変えて添加し、その分散液のζ（ゼータ）電位を測定し、この値が変化する塩濃度を臨界凝集濃度として求めることもできる。
【００７２】
凝集剤の添加量は、臨界凝集濃度以上であればよいが、好ましくは臨界凝集濃度の１．２倍以上、更に好ましくは、１．５倍以上添加することがよい。無限溶解する溶媒とは、即ち水に対して無限溶解する溶媒を示し、この溶媒は、本発明においては形成された樹脂を溶解させないものが選択される。具体的には、メタノール、エタノール、プロパノール、イソプロパノール、ｔ−ブタノール、メトキシエタノール、ブトキシエタノール等のアルコール類、アセトニトリル等のニトリル類、ジオキサン等のエーテル類を挙げることができる。特に、エタノール、プロパノール、イソプロパノールが好ましい。この無限溶解する溶媒の添加量は、凝集剤を添加した重合体含有分散液に対して１〜１００体積％が好ましい。
【００７３】
本発明のトナーは少なくとも樹脂と焼成ブラックを含有するものであるが、必要に応じて定着性改良剤である離型剤や荷電制御剤等を含有することもできる。更に、上記樹脂と焼成ブラックを主成分とするトナー粒子に対して無機微粒子や有機微粒子等で構成される外添剤を添加したものであってもよい。
【００７４】
本発明のトナーの形状係数は、下記式により示されるものであり、トナー粒子の丸さの度合いを示す。
【００７５】
形状係数＝（（最大径／２）²×π）／投影面積
ここに、最大径とは、トナー粒子の平面上への投影像を２本の平行線ではさんだとき、その平行線の間隔が最大となる粒子の幅をいう。又、投影面積とは、トナー粒子の平面上への投影像の面積をいう。
【００７６】
本発明では、この形状係数は、走査型電子顕微鏡により２０００倍にトナー粒子を拡大した写真を撮影し、次いでこの写真に基づいて「ＳＣＡＮＮＩＮＧ ＩＭＡＧＥ ＡＮＡＬＹＺＥＲ」（日本電子社製）を使用して写真画像の解析を行うことにより測定した。この際、１００個のトナー粒子を使用して本発明の形状係数を上記算出式にて測定したものである。
【００７７】
本発明においては、この形状係数が１．０〜１．６の範囲にあるトナー粒子が６５個数％以上とすることが好ましく、より好ましくは、７０個数％以上である。更に好ましくは、この形状係数が１．２〜１．６の範囲にあるトナー粒子が６５個数％以上とすることであり、より好ましくは、７０個数％以上である。この形状係数が１．０〜１．６の範囲にあるトナー粒子が６５個数％以上であることにより、現像剤搬送部材などでの摩擦帯電性がより均一となり、過度に帯電したトナーの蓄積が無く、現像剤搬送部材表面よりトナーがより交換しやすくなるために、現像ゴースト等の問題も発生しにくくなる。更に、トナー粒子が破砕しにくくなってキャリア或いは帯電付与部材の汚染が減少し、トナーの帯電性が安定する。
【００７８】
この形状係数を制御する方法は特に限定されるものではない。例えばトナー粒子を熱気流中に噴霧する方法、又はトナー粒子を気相中において衝撃力による機械的エネルギーを繰り返して付与する方法、或いはトナーを溶解しない溶媒中に添加し旋回流を付与する方法等により、形状係数を１．０〜１．６、又は１．２〜１．６にしたトナーを調製し、これを通常のトナー中へ本発明の範囲内になるように添加して調整する方法がある。又、いわゆる重合法トナーを調整する段階で全体の形状を制御し、形状係数を１．０〜１．６、又は１．２〜１．６に調整したトナーを同様に通常のトナーへ添加して調整する方法がある。
〔２〕現像剤
本発明のトナーは、▲１▼マグネットロールを使用しない所謂非磁性一成分現像法にて単独で使用するもの、▲２▼キャリアと混合して２成分現像剤として使用するものの何れであってもよいが、上記▲２▼の使用態様が好ましい。
【００７９】
本発明のトナーに混合されるキャリアとしては、▲１▼鉄、フェライト等の磁性材料粒子のみで構成されるキャリア、▲２▼芯材粒子の表面が樹脂により被覆されてなる樹脂被覆キャリアの何れであってもよいが、耐久性等の観点から上記▲２▼の樹脂被覆キャリアを使用することが好ましい。
【００８０】
キャリアの粒子径としては、体積平均粒径で１５〜１００μｍ、好ましくは６０〜８０μｍである。
【００８１】
キャリアが有する磁化特性としては、飽和磁化で１８．８×１０^-6〜１０．０×１０^-5Ｗ・ｂｍ／ｋｇであることが好ましい。
【００８２】
樹脂被覆キャリアを構成する芯材粒子としては、鉄粉、マグネタイト、各種フェライト等を挙げることができ、これらのうち、マグネタイト及びフェライトが好ましい。
【００８３】
ここに、フェライトとしては、銅、亜鉛、ニッケル、マンガン等の重金属を含有するフェライト、アルカリ金属（例えばＬｉ、Ｎａ）及び／又はアルカリ土類金属（例えばＭｇ、Ｃａ、Ｓｒ、Ｂａ）を含有する軽金属フェライトを使用することが好ましく、当該軽金属フェライトを使用することが特に好ましい。
【００８４】
軽金属フェライトは、下記式（１）又は式（２）で表される組成を有するものである。
【００８５】
式（１） （Ｍ₂Ｏ）_x（Ｆｅ₂Ｏ₃）_1-x
式（２） （ＭＯ）_x（Ｆｅ₂Ｏ₃）_1-x
式中、Ｍはアルカリ金属又はアルカリ土類金属を示す。又、Ｍ₂Ｏ及び／又はＦｅ₂Ｏ₃の一部をアルカリ土類金属酸化物で置換したものであってもよい。又、ｘとしては３０モル％以下、好ましくは１８モル％以下であり、更に置換されるアルカリ土類金属及び／又はアルカリ金属酸化物は１〜１５モル％が好ましく、更に好ましくは３〜１５モル％である。
【００８６】
この軽金属フェライト及びマグネタイトが好ましい理由としては単に近年で盛んとなっており廃棄物の汚染問題のみではなく、これらに加えてキャリア自体を軽量化することができ、トナーに対するストレスを軽減することができる利点を有しているからである。
【００８７】
樹脂被覆キャリアを構成する樹脂としては特に限定されるものではなく、例えばシリコーン樹脂、スチレン−アクリル樹脂、フッ化ビニリデン系樹脂、フッ化ビニリデン系以外のフッ素系樹脂を挙げることができる。
【００８８】
上記シリコーン樹脂としては特に限定されないが、加熱脱水縮合反応、以下に示す室温湿気硬化反応等で硬化する縮合反応型シリコーン樹脂が好ましく用いられる。
【００８９】
【化３】

【００９０】
上記反応式中、Ｒ₁、Ｒ₂はそれぞれアルキル基等の置換基を表し、ＯＸはアルコキシ基、ケトキシ基、アセトキシ基、アミノキシ基等の基を表す。
【００９１】
この中でも、置換基がメチル基であるものは被覆層が緻密になり、耐久性の良好なキャリアとすることができる。
【００９２】
本発明で好ましく用いられるシリコーン樹脂として、例えば「ＳＲ−２４１１」（東レシリコン社製）、「ＳＲ−２４１０」（東レシリコン社製）、「ＫＲ−２５５」（信越化学社製）、「ＫＲ−２７１」（信越化学社製）などがある。
【００９３】
又、スチレン−アクリル樹脂としては、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、α−メチルスチレン、ｐ−クロロスチレン、３，４−ジクロロスチレン、ｐ−フェニルスチレン、ｐ−エチルスチレン、２，４−ジメチルスチレン、ｐ−ｔ−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ようなスチレン又はスチレン誘導体と、メタクリル酸メチル、メタクリル酸エチル、メタクリル酸ｎ−ブチル、メタクリル酸イソプロピル、メタクリル酸イソブチル、メタクリル酸ｔ−ブチル、メタクリル酸ｎ−オクチル、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、メタクリル酸ラウリル、メタクリル酸フェニル、メタクリル酸ジエチルアミノエチル、メタクリル酸ジメチルアミノエチル等のメタクリル酸エステル誘導体、アクリル酸メチル、アクリル酸エチル、アクリル酸イソプロピル、アクリル酸ｎ−ブチル、アクリル酸ｔ−ブチル、アクリル酸イソブチル、アクリル酸ｎ−オクチル、アクリル酸２−エチルヘキシル、アクリル酸ステアリル、アクリル酸ラウリル、アクリル酸フェニル、アクリル酸ジメチルアミノエチル、アクリル酸ジエチルアミノエチル等のアクリル酸エステル誘導体等との共重合体を挙げることができる。この共重合体におけるスチレン（誘導体）の含有割合は、耐久性の向上を図る観点から２０〜９０質量％であることが好ましい。
【００９４】
又、フッ化ビニリデン系樹脂としては、フッ化ビニリデンと、テトラフルオロエチレン、ヘキサフロオロプロピレン、モノクロロトリフルオロエチレン、モノフルオロエチレン、トリフルオロエチレン等と共重合成分との共重合体が好ましく、フッ化ビニリデンが共重合体中に２０質量％以上含有されていることが特に好ましい。
【００９５】
フッ化ビニリデン系樹脂を得るための共重合体成分としては、前述の含ハロゲン系単量体以外に、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、α−メチルスチレン、ｐ−クロロスチレン、３，４−ジクロロスチレン、ｐ−フェニルスチレン、ｐ−エチルスチレン、２，４−ジメチルスチレン、ｐ−ｔ−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様なスチレン又はスチレン誘導体と、メタクリル酸メチル、メタクリル酸エチル、メタクリル酸ｎ−ブチル、メタクリル酸イソプロピル、メタクリル酸イソブチル、メタクリル酸ｔ−ブチル、メタクリル酸ｎ−オクチル、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、メタクリル酸ラウリル、メタクリル酸フェニル、メタクリル酸ジエチルアミノエチル、メタクリル酸ジメチルアミノエチル等のメタクリル酸エステル誘導体、アクリル酸メチル、アクリル酸エチル、アクリル酸イソプロピル、アクリル酸ｎ−ブチル、アクリル酸ｔ−ブチル、アクリル酸イソブチル、アクリル酸ｎ−オクチル、アクリル酸２−エチルヘキシル、アクリル酸ステアリル、アクリル酸ラウリル、アクリル酸フェニル、アクリル酸ジメチルアミノエチル、アクリル酸ジエチルアミノエチル等のアクリル酸エステル誘導体等との共重合体も挙げることができる。
【００９６】
芯材粒子に対して樹脂を被覆する方法としては、▲１▼樹脂溶液を芯材粒子に噴霧して乾燥する方法、▲２▼芯材粒子に被覆樹脂粒子を静電的に付着させた後に機械的エネルギーを付与して被覆する方法、▲３▼芯材粒子に被覆樹脂粒子を静電的に付着した後に当該樹脂の溶融温度以上に加熱し溶融被覆する方法、▲４▼樹脂溶液中に芯材粒子を浸漬する方法、▲５▼硬化剤を含有した樹脂を被覆した後に加熱して硬化させる方法など種々の方法を使用することができる。
【００９７】
樹脂の被覆量としては、芯材粒子の表面を均一に被覆するに足りる量であればよく、具体的には、芯材粒子に対して０．１〜５．０質量％とされ、好ましくは０．５〜３．０質量％である。この被覆量が過少である場合にはその効果を発揮することができず、被覆量が過大である場合には、被覆樹脂が遊離し、画像欠陥を発生することがある。
【００９８】
【実施例】
以下、本発明の実施例について説明するが、本発明はこれらに限定されるものではない。
（１）焼成ブラックの製造
「焼成ブラック１」
黒色顔料ＢａｙｆｅｒｒｏｘＲ３０３Ｔ（Ｂａｙｅｒ ＡＧの製品）を振動ボールミル（媒体めのうボール使用）によって、体積平均粒径０．２μｍまで粉砕し、γ−（２−アミノエチル）アミノプロピルトリメトキシシランによって表面処理した後、再び振動ボールミルによって、体積平均粒径０．２μｍまで解砕した。回折分析により、原料はスピネルの構造の相を含んでいることが確認された。体積平均粒径の測定は、レーザー回折式粒度測定装置ＳＡＬＤ−１０００を用いた。分析によるとＦｅ₂Ｏ₃：ＭｎＯの比は６０：４０であった。得られた粉末粒子を焼成ブラック１とする。
「焼成ブラック２」
通気撹拌機を備えた３０Ｌの撹拌槽で、ＦｅＳＯ₄濃度が２００ｇ／ＬのＦｅＳＯ₄溶液１０．１Ｌ及びＭｎＳＯ₄・Ｈ₂Ｏ濃度が６００ｇ／ＬのＭｎＳＯ₄溶液０．９Ｌを合わせ、窒素でパージした。その後ＮａＯＨ濃度が６５６ｇ／Ｌの水酸化ナトリウム水溶液２．３Ｌを１５分かけて加え、撹拌しながら８５℃に加熱した。その後８５℃にて３００Ｌ／時間の空気を５．５時間通した。吸引漏斗上で黒色の懸濁液を約２０Ｌの水を用いて洗浄し、空気循環乾燥室で８０℃にて乾燥し、焼成ブラックの原料を得た。得られた原料の比表面積は、測定の結果５．３ｍ²／ｇだった。回折分析により、原料はスピネルの構造の相を含んでいることが確認された。３００ｇの原料を回転キルン中で７００℃にて４時間焼成し、その間５００Ｌ／時間の空気を通し、焼成ブラックを得た。得られた焼成ブラックを分析したところ、Ｆｅ₂Ｏ₃：ＭｎＯの比は８０：２０であった。顔料のＸ線回折図は、ヘマタイトの回折線のみを示す。振動ボールミル中で０．３μｍまで粉砕した。得られた粉末粒子を焼成ブラック２とする。
「焼成ブラック３」
原料の製造に、ＦｅＳＯ₄濃度が２００ｇ／ＬのＦｅＳＯ₄溶液１１．３９Ｌ及びＭｎＳＯ₄・Ｈ₂Ｏ濃度が６００ｇ／ＬのＭｎＳＯ₄溶液４．５０Ｌ及び２．３２Ｌの水酸化ナトリウム水溶液（６５６ｇ／Ｌ）を用いる他は焼成ブラック２と同様の方法を用いた。回折分析により、原料はスピネルの構造の相を含んでいることが確認された。原料を７００℃にて４時間焼成し、蒸気：生成物の比率が３：１にてスチームジェットミル中で粉砕し焼成ブラックを得た。得られた焼成ブラックを分析したところ、Ｆｅ₂Ｏ₃：ＭｎＯの比は４６：５４であり、ヘマタイトの構造の相を含む。得られた粉末粒子を焼成ブラック３とする。
「焼成ブラック４」
Ｍｎ₃Ｏ₄の製造：ガス導入口が備わっている加熱可能な撹拌容器の中で、１Ｌ当たり６００ｇのＭｎＳＯ₄・Ｈ₂Ｏから成る濃度のＭｎＳＯ₄溶液２ｍ³を７．５ｍ³の水で希釈した。３９５Ｌの４５％水酸化ナトリウム溶液を添加することで、ｐＨを１１に調整した。その後、このＭｎ（ＯＨ）₂懸濁液を８０℃に加熱し、そして６時間当たり７０ｍ³から成る空気を供給した。この得られた固体状物質を濾別、洗浄した後、１３０℃で乾燥した。上述したようにして得られたＭｎ₃Ｏ₄フィルターケーキの６６０ｋｇを、３６５ｋｇのＣｒ₂Ｏ₃ＧＮ（Ｂａｙｅｒ ＡＧの製品）、３３２ｋｇのＣｕＣＯ₃・Ｃｕ（ＯＨ）₂・ｘＨ₂Ｏ（４６％のＣｕ、Ｔｈ． Ｇｏｌｄｓｃｈｍｉｄｔ ＡＧの製品）、９ｋｇのＮａ₂Ｂ₄Ｏ₇・５Ｈ₂Ｏ及び１０００Ｌの水と一緒に、ローター−ステーターミキサーで処理して均一な懸濁液を生じさせた。この混合物を乾燥した後、回転ドラム炉を用い酸化雰囲気中８００℃で６時間焼成した。このファーネスクリンカーの大きさを、最初に湿ったままボールミル中で小さくした後、パールミルのカスケード中で０．４μｍに微粉砕し、焼成ブラック４を得た。組成は、Ｃｕ：Ｃｒ：Ｍｎ＝１６．５：２７．０：２８．６である。Ｘ線回折分析によると、この焼成ブラック４はスピネル構造の構造の相を含んでいることが確認された。
（２）ラテックス調整
（ラテックス１）
撹拌装置、温度センサー、冷却管、窒素導入装置を付けた５０００ｍｌのセパラブルフラスコに予めアニオン系活性剤（ドデシルスルフォン酸ナトリウム：ＳＤＳ）７．０８ｇをイオン交換水（３０１０ｇ）に溶解させた溶液を添加する。窒素気流下２３０ｒｐｍの撹拌速度で撹拌しつつ、内温を８０℃に昇温させた。一方でスチレン７０．１ｇ、ｎ−ブチルアクリレート１９．９ｇ、メタクリル酸１０．９ｇからなるモノマー溶液を作製した。次いで、重合開始剤（過硫酸カリウム：ＫＰＳ）９．２ｇをイオン交換水２００ｇに溶解させた溶液を添加し、その後７５℃に昇温し、前記モノマー溶液を１時間で滴下し、更に７５℃にて２時間加熱、撹拌することでラテックス粒子を作製した。ここまでをＨＰ工程と称する。得られたラテックス粒子をラテックスＨＰとする。
【００９９】
別途、攪拌装置を有するフラスコにてスチレン１０５．６ｇ、ｎ−ブチルアクリレート３０．０ｇ、メタクリル酸６．４ｇ、ｎ−オクチル−３−メルカプトプロピオン酸エステル５．６ｇの溶液に例示化合物１９）７２．０ｇを８０℃に加熱し溶解する。次いでＳＤＳ＝１．６ｇを２７００ｍｌの水に溶解させた溶液を８０℃に加熱し、前述のＨＰ工程で得られたラテックス粒子、固形分相当で２８ｇを添加し、そのＳＤＳ水溶液へ循環経路を有する機械式分散機（クレアミックス）により上記モノマーへ例示化合物１９）を加熱させた溶液を混合分散させ、均一な分散粒子径を有する乳化粒子を含む乳化液を作製した。
【０１００】
引き続いて前記ラテックス粒子を有する分散液に重合開始剤（ｋｐｓ）５．１ｇをイオン交換水２４０ｍｌに溶解させた溶液を添加し、更に水７５０ｍｌを添加し、８０℃に加熱し、８０℃にて３時間反応させ、高分子量体を核として中間分子量体をカプセリングしたラテックスを調整した。この工程をＭＰ工程とする。更に、前記ラテックスにＫＰＳ＝７．４ｇを水２００ｍｌに溶解した溶液を加え、８０℃に保った状態で、スチレン＝３００ｇ、ブチルアクリレート＝９５ｇ、メタクリル酸＝１５．３ｇ及びｎ−オクチル−３−メルカプトプロピオン酸エステル＝１０．４ｇを混合した溶液を１時間かけて滴下した。次いで、２時間反応させ、目的とするラテックス粒子を得た。この反応工程をＬＰ工程とする。このラテックス粒子をラテックス１とする。
（ラテックス２）
攪拌装置を有するフラスコにてスチレン１０５．６ｇ、ｎ−ブチルアクリレート３０．０ｇ、メタクリル酸６．４ｇに例示化合物１９）７２．０ｇを８０℃に加熱し溶解する。次いでＳＤＳ＝１．６ｇを２７００ｍｌの水に溶解させた溶液を８０℃に加熱し、前述のＨＰ工程で得られたラテックス粒子を固形分相当で２８ｇ添加し、そのＳＤＳ水溶液へ循環経路を有する機械式分散機（クレアミックス）により上記モノマーへ例示化合物１９）を加熱させた溶液を混合分散させ、均一な分散粒子径を有する乳化粒子を含む乳化液を作製した。
【０１０１】
引き続いて前記ラテックス粒子を有する分散液に重合開始剤（ＫＰＳ）５．１ｇをイオン交換水２４０ｍｌに溶解させた溶液を添加し、更に水７５０ｍｌを添加し、８０℃に加熱し、８０℃にて３時間反応させ、高分子量体を核として中間分子量体をカプセリングしたラテックスを調整した。
【０１０２】
更に、前記ラテックスにＫＰＳ＝１４．８ｇを水４００ｍｌに溶解した溶液を加え、８０℃に保った状態で、スチレン＝６００ｇ、ブチルアクリレート＝１９０ｇ、メタクリル酸＝３０．０ｇ及びｎ−オクチル−３−メルカプトプロピオン酸エステル＝２０．８ｇを混合した溶液を１時間かけて滴下する。次いで、２時間反応させ、目的とするラテックス粒子を得た。このラテックス粒子をラテックス２とする。
（３）着色粒子Ｂｋの調製
「着色剤分散液Ｂｋ１」
ｎ−ドデシル硫酸ナトリウム＝５．９ｇをイオン交換水１６０ｍｌに撹拌溶解する。この液に、撹拌下、焼成ブラック１＝１２６ｇを徐々に加え、次いで、クレアミックスを用いて分散した。この分散液を着色剤分散液Ｂｋ１とする。
「着色剤分散液Ｂｋ２」
着色剤分散液Ｂｋ１の調製において、焼成ブラック２を使用した以外は同様にして着色剤分散液Ｂｋ２を得た。
「着色剤分散液Ｂｋ３」
着色剤分散液Ｂｋ１の調製において、焼成ブラック３を使用した以外は同様にして着色剤分散液Ｂｋ３を得た。
「着色剤分散液Ｂｋ４」
着色剤分散液Ｂｋ１の調整において、焼成ブラック４を使用した以外は同様にして着色剤分散液Ｂｋ４を得た。
「比較用着色剤分散液Ｂｋ１」
ｎ−ドデシル硫酸ナトリウム＝５．９ｇをイオン交換水１６０ｍｌに撹拌溶解する。この液に、撹拌下、カーボンブラック（キャポット社製 リーガル３３０）４２ｇを徐々に加え、次いで、クレアミックスを用いて分散した。この分散液を比較用着色剤分散液Ｂｋ１とする。
「比較用着色剤分散液Ｂｋ２」
ｎ−ドデシル硫酸ナトリウム＝５．９ｇをイオン交換水１６０ｍｌに撹拌溶解する。この液に、撹拌下、マグネタイト（戸田工業社製 ＭＡＴ３０５ 粒径０．３μｍ）１２６ｇを徐々に加え、次いで、クレアミックスを用いて分散した。この分散液を比較用着色剤分散液Ｂｋ１とする。
「比較用着色剤分散液Ｂｋ３」
ｎ−ドデシル硫酸ナトリウム＝５．９ｇをイオン交換水１６０ｍｌに撹拌溶解する。この液に、撹拌下、カーボンブラック（キャポット社製 リーガル３３０）４２ｇ、マグネタイト（戸田工業社製 ＭＡＴ３０５ 粒径０．３μｍ）２１ｇを徐々に加え、次いで、クレアミックスを用いて分散した。この分散液を比較用着色剤分散液Ｂｋ３とする。
（４）トナーの製造例
・トナーの製造例１
前述のラテックス１を固形分相当で４２０．７ｇとイオン交換水９００ｍｌ及び着色剤分散液Ｂｋ１を、温度センサー、冷却管、窒素導入装置、攪拌装置を付けた５Ｌの四つ口フラスコに入れ撹拌する。３０℃に調整した後、この溶液に５ｍｏｌ／Ｌの水酸化ナトリウム水溶液を加え、ｐＨを１１．０に調整した。次いで、塩化マグネシウム６水和物１２．１ｇをイオン交換水１０００ｍｌに溶解した水溶液を攪拌下、３０℃にて１０分間で添加した。その後、３分間放置した後に、昇温を開始し、液温度９０℃まで６分で昇温する（昇温速度＝１０℃／分）。その状態で粒径をコールターカウンターＴＡIIにて測定し、体積平均粒径が６．５μｍ以上になった時点で塩化ナトリウム８０．４ｇをイオン交換水１０００ｍｌに溶解した水溶液を添加し粒子成長を停止させ、更に継続して液温度を８０〜９５℃の範囲で、又攪拌時間を１時間から１０時間まで変化させて塩析／融着させた。その後、８℃／ｍｉｎの条件で３０℃まで冷却し、塩酸を添加し、ｐＨを２．０に調整し、撹拌を停止した。生成した着色粒子を濾過し、イオン交換水で繰り返し洗浄し、その後、フラッシュジェットドライヤーを用いて吸気温度６０℃にて乾燥させ、次いで流動層乾燥機を用いて４０℃の温度で乾燥させた。得られた着色粒子の１００質量部に、シリカ微粒子０．８質量部をヘンシェルミキサーにて外添混合して「トナー１」を得た。
・トナーの製造例２
トナーの製造例１において、着色剤分散液Ｂｋ１の代わりに着色剤分散液Ｂｋ２を使用した以外は同様にして「トナー２」を得た
・トナーの製造例３
トナーの製造例１において、ラテックス１の代わりにラテックス２を、着色剤分散液Ｂｋ１の代わりに着色剤分散液Ｂｋ３を使用した以外は同様にして「トナー３」を得た。
・トナーの製造例４
トナーの製造例３において、着色剤分散液Ｂｋ３の代わりに着色剤分散液Ｂｋ４を使用した以外は同様にして「トナー４」を得た。
・トナーの製造例５（懸濁重合法の例）
スチレン＝１６５ｇ、ｎ−ブチルアクリレート＝３５ｇ、焼成ブラック１＝２７ｇ、ジ−ｔ−ブチルサリチル酸金属化合物＝２ｇ、スチレン−メタクリル酸共重合体＝８ｇ、パラフィンワックス（ｍｐ＝７０℃）＝２０ｇを６０℃に加温し、ＴＫホモミキサー（特殊機化工業社製）にて１２０００ｒｐｍで均一に溶解、分散した。これに重合開始剤として２，２′−アゾビス（２，４−バレロニトリル）＝１０ｇを加えて溶解させ、重合性単量体組成物を調製した。次いで、イオン交換水７１０ｇに０．１ｍｏｌ／Ｌ燐酸ナトリウム水溶液４５０ｇを加え、ＴＫホモミキサーにて１３０００ｒｐｍで攪拌しながら１．０ｍｏｌ／Ｌ塩化カルシウム６８ｇを徐々に加え、燐酸三カルシウムを分散させた懸濁液を調製した。この懸濁液に上記重合性単量体組成物を添加し、ＴＫホモミキサーにて１００００ｒｐｍで２０分間攪拌し、重合性単量体組成物を造粒した。その後、攪拌翼のついた反応装置を使用し、７５〜９５℃にて５〜１５時間反応させた。塩酸により燐酸三カルシウムを溶解除去し、次に遠心分離機を用いて、遠心沈降法により液中にて分級を行い、次いで濾過、洗浄、乾燥させた。得られた着色粒子の１００質量部に、シリカ微粒子１質量部をヘンシェルミキサーにて外添混合して懸濁重合法による「トナー５」を得た。
・トナーの製造例６（粉砕法の例）
ポリエステル樹脂（結着樹脂）１００質量部と、焼成ブラック１＝２９質量部と、ポリプロピレン（Ｍｗ：６６００、Ｍｎ：３０００、Ｍｗ／Ｍｎ：２．２０、融点：８０℃）４質量部と、アゾ系染料（荷電制御剤）１質量部とからなるトナー原料をヘンシェルミキサーにて予備混合し、二軸混練押出機（１９０℃に設定）にて溶融混練し、ハンマーミルにて粗粉砕し、ジェット式粉砕機にて粉砕し、風力分級機により分級し、体積平均粒径８．０μｍの着色粒子である「トナー６」を得た。
・比較用トナーの製造例１
トナーの製造例１において、着色剤分散液Ｂｋ１の代わりに比較用着色剤分散液Ｂｋ１を使用した以外は同様にして「比較用トナー１」を得た。
・比較用トナーの製造例２
トナーの製造例１において、着色剤分散液Ｂｋ１の代わりに比較用着色剤分散液Ｂｋ２を使用した以外は同様にして「比較用トナー２」を得た。
・比較用トナーの製造例３
トナーの製造例１において、着色剤分散液Ｂｋ１の代わりに比較用着色剤分散液Ｂｋ３を使用した以外は同様にして「比較用トナー３」を得た。
【０１０３】
得られたトナーの詳細を以下の表１及び表２に示す。
【０１０４】
【表１】

【０１０５】
【表２】

【０１０６】
（５）現像剤の調製
得られた各トナーと体積平均粒径６０μｍのシリコーンコートフェライトキャリアをトナー濃度６質量％にて混合し、現像剤の調製を行った。
（６）実写テスト
得られた各現像剤を用い、市販のデジタル複写機Ｓｉｔｉｏｓ７０７５（コニカ社製）に装填して１００万プリントの実写テストを行った。
【０１０７】
条件：温度３０℃、湿度８０％ＲＨ、原稿画像黒化面積率５０％
（７）評価
以下の評価項目に従って評価を行った。
・画像濃度
１００万回にわたる実写テストの初期及び終期において、サクラデンシトメーター（コニカ（株）製）を用いて測定した。画像濃度１．３０以上であれば、実用上問題ないレベルである。
・カブリ
１００万回にわたる実写テストの初期及び終期において、サクラデンシトメーター（コニカ（株）製）を用いて転写紙の白地部に対する相対濃度を測定した。カブリ０．００５以下であれば、実用上問題ないレベルである。
・機内飛散
１００万回にわたる実写テストの初期及び終期において、現像器から転写装置付近のトナーの飛散を調べ以下の評価で判定した。
【０１０８】
◎・・・トナーの飛散がない
○・・・トナーの飛散が若干見られる
△・・・トナーの飛散が多い
×・・・トナーの飛散が大量に発生する
・トナースペント
１００万回にわたる実写テストの後、界面活性剤水溶液で現像剤からトナーを洗浄、除去する。得られた洗浄キャリア３ｇをアセトン１００ｍｌで洗浄し、キャリアにスペント（融着）したトナーを溶かし出し、分光光度計で透過率を測定した（波長５００ｎｍ）。透過率６５未満で、帯電不良が発生する。
【０１０９】
◎・・・透過率９０％以上
○・・・透過率８０〜９０％
△・・・透過率６５〜８０％
×・・・透過率６５％未満
【０１１０】
【表３】

【０１１１】
表３から明らかなように、本発明のトナーを使用した現像剤は適度な磁化、即ち弱い磁性があるため、キャリアとの混合性がよく、帯電立ち上がりが速いこと、又画像濃度が低下することなく、弱帯電トナーに現像ロールの磁気吸引力がかかるためトナー飛散、かぶりが発生することがないことが分かる。
【０１１２】
【発明の効果】
本発明のトナーを採用した現像剤によれば、着色剤である焼成ブラックがトナーに良好に分散されるため、高温高湿環境での長期に渡る使用においても、スペント及び帯電不良の発生がなく、又適度な磁性をトナーに与えるため、高い画像濃度を維持しながら、弱帯電トナーの飛散、カブリを防止する作用があり、安定して良好な画像が得られるという顕著に優れた効果を奏する。
【図面の簡単な説明】
【図１】抵抗測定装置の概略図。
【符号の説明】
１ 測定粒子層（試料層）
２ 絶縁性のパイプ
３ 黄銅製の重り
４ 黄銅製の底板
５ 抵抗計[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a toner for developing an electrostatic latent image used in an electrophotographic copying machine, a printer, or the like, and more particularly to a polymerized toner employing a specific colorant and a two-component developer using the same. The present invention also relates to a manufacturing method thereof.
[0002]
[Prior art]
With regard to electrophotographic image forming methods, digital image forming has become mainstream due to recent advances in digital technology. The digital image forming method is based on visualizing a small dot image of one pixel such as 600 dpi (dpi is the number of dots per 2.54 cm). Image quality technology is required.
[0003]
One of the most important technologies for realizing this high image quality technology is a technology related to toner manufacturing technology. So far, so-called pulverized toner, which is obtained by classifying toner powder obtained by mixing binder resin and pigment, pulverizing after kneading, and classifying in the classification process has been mainly used for the formation of electrophotographic images. The toner thus obtained has a limit in making the particle size distribution of the toner particles uniform, and the particle size distribution and shape of the toner particles are insufficiently uniform. It is difficult to achieve sufficient image quality with an electrophotographic image using such pulverized toner.
[0004]
In recent years, an electrophotographic developer using a polymerized toner or an image forming method has been proposed as means for achieving uniform particle size distribution and shape of toner particles. Since the polymerized toner is produced by uniformly dispersing the raw material monomer in an aqueous system and then polymerizing it, a toner having a uniform toner particle size distribution and shape can be obtained.
[0005]
When the polymerized toner is employed in an image forming apparatus, a new technical problem has occurred. In other words, the polymerization toner has low resistance because surfactants and salts used during polymerization remain, and when carbon black is used as a colorant, the resistance of carbon black itself is low, so that charging under high temperature and high humidity is difficult. In addition to a large decrease in the amount, the dispersion diameter of carbon black tends to be large, which causes problems of in-machine dispersion and fogging under high temperature and high humidity. For this reason, there has been a demand for a colorant capable of imparting stable chargeability to environmental fluctuations.
[0006]
In the toner in which magnetite is dispersed as a colorant disclosed in Japanese Patent Laid-Open No. 5-150544, the toner is magnetized. Therefore, in a two-component developer used in the same manner as a magnetic carrier, magnetic attraction from a developing roll is used. The image density decreased due to the force.
[0007]
In particular, when the toner is used for a long period of time, the toner adheres to the carrier due to excessive adhesion between the carrier and the toner, so-called toner spent is caused, resulting in in-machine scattering, fogging, and density reduction due to poor charging.
[0008]
[Problems to be solved by the invention]
The present invention has been made in view of the above circumstances, and the purpose thereof is to prevent the occurrence of toner spent and charging failure even in a long-term specification under a high temperature and high humidity environment, while maintaining a high image density. An object of the present invention is to provide a toner which has an effect of preventing scattering and fogging of weakly charged toner and can stably obtain a good image. Another object of the present invention is to provide a polymerized toner which is particularly excellent in the effect and a developer containing the same.
[0009]
[Means for Solving the Problems]
The above object of the present invention has been achieved by the following constitution.
[0011]
  1. An electrostatic latent image developing toner obtained by fusing at least resin particles and colorant particles in an aqueous medium, wherein the colorant particles contain baked black. toner.
[0013]
  2. The fired black is an iron-manganese composite oxide.1 itemThe toner for developing an electrostatic latent image.
[0014]
  3. Fe in the iron-manganese composite oxide₂O_ThreeThe mass ratio of MnO is 40:60 to 80:202The toner for developing an electrostatic latent image.
[0015]
  4. The saturation magnetization of the fired black is 25.1 × 10^-7~ 31.38 × 10^-6W・1 to 2 characterized in that bm / kg3The toner for developing an electrostatic latent image according to any one of the above.
[0016]
  5. The fired black has a volume resistivity of 1 × 10⁶~ 1x10⁸1 to 1 characterized by being Ωcm4The toner for developing an electrostatic latent image according to any one of the above.
[0017]
  6. 1 to5A two-component developer obtained by mixing the electrostatic latent image developing toner according to any one of the above and a carrier.
[0018]
  7. A method for producing an electrostatic latent image developing toner, comprising: fusing at least a binder resin and a calcined black as a colorant in an aqueous medium to obtain an electrostatic latent image developing toner.
[0019]
  8. A method for producing an electrostatic latent image developing toner, comprising: fusing at least resin particles and colorant particles containing baked black in an aqueous medium to obtain an electrostatic latent image developing toner.
[0021]
  9. The fired black is an iron-manganese composite oxide.7 or 8A method for producing a toner for developing an electrostatic latent image according to item 2.
[0022]
  10. Fe in the iron-manganese composite oxide₂O_ThreeThe mass ratio of MnO is 40:60 to 80:209A method for producing a toner for developing an electrostatic latent image.
[0023]
  11. The saturation magnetization of the fired black is 25.1 × 10^-7~ 31.38 × 10^-6W・It is characterized by being bm / kg7~10The method for producing a toner for developing an electrostatic latent image according to any one of the above.
[0024]
  12. The fired black has a volume resistivity of 1 × 10⁶~ 1x10⁸It is characterized by being Ωcm7~ 11The method for producing a toner for developing an electrostatic latent image according to any one of the above.
[0025]
  13. 1 to5A method for producing a two-component developer, wherein the toner for developing an electrostatic latent image according to any one of the above and a carrier are mixed to obtain a two-component developer.
[0026]
The toner for developing an electrostatic latent image of the present invention has a low resistance of carbon black itself that has been used as a colorant, a significant decrease in charge amount under high temperature and high humidity, and the dispersion of carbon black in the toner. It is obtained by the problem of dispersion in the machine under high temperature and high humidity, fogging problem, and the specific complex oxide system that constitutes the colorant or colorant particles. This is achieved by employing the following pigment, that is, calcined black.
[0027]
Hereinafter, the present invention will be described in detail.
[1] Toner for developing electrostatic latent image (also simply referred to as toner)
(1) Colorant
In the present invention, calcined black is particularly used as the colorant or the colorant particles.
・ Baking black
Firing black is a (black) pigment obtained by mixing a plurality of types of (metal) oxides. Examples of such pigments include copper-chromium (Pigment Black 28) and copper-iron-manganese (Pigment). Black 27) and cobalt-iron-chromium (Pigment Black 26). In particular, in the present invention, an iron-manganese composite oxide composed of iron oxide and manganese oxide is preferably used. The iron-manganese composite oxide particularly preferably used in the present invention as the baked black is Fe from the viewpoint of obtaining a black color without redness or blueness.₂O_ThreeAnd the mass ratio of MnO is preferably in the range of 40:60 to 80:20, particularly preferably 55:45 to 65:35.
[0028]
The method for producing the iron-manganese composite oxide first prepares a raw material composed of an oxide or hydroxide of iron and manganese (Fe and Mn) containing a phase having a spinel structure, and then 500 to 1,000 ° C. The firing is preferably performed in an oxidizing atmosphere at a temperature in the range of 600 to 800 ° C.
[0029]
The fired black used in the present invention has a spinel structure phase in its structure, and in order to impart this structure phase, iron and manganese (Fe and Mn) containing the spinel structure phase are included. It is necessary to prepare a raw material consisting of oxide or hydroxide.
[0030]
The phase of the structure of the spinel in the present invention is a chemical formula AB which is also referred to as a sericite-type structure, as described in the chemical dictionary published by Tokyo Chemical Doujinsha and the Iwanami Chemical Dictionary (5th edition).₂X_Four(A and B are positive elements, and X is a negative element). The details of the spinel structure are omitted here, but the crystal structure described in the above document. The fired black used in the present invention may have a hematite structure phase in its structure.
[0031]
Basically, the raw material is roughly composed of Fe_3-xMn_xO_FourIn particular, 0 <X <3 is particularly suitable. The raw material is preferably prepared by a precipitation method in which iron and manganese salts are oxidized in the presence of an alkali.
[0032]
As a trade name of baked black, for example, Bayferrox R303T (a product of Bayer AG) can be mentioned.
[0033]
  The fired black used in the present invention preferably has weak acidity. The calcined black has a saturation magnetization of 25.1 × 10^-7~ 31.38 × 10^-6W・bm / kg is preferably used, more preferably 50.1 × 10^-7~ 10.2 × 10^-6W・bm / kg. The saturation magnetization was 3000 Oe (2.39 × 10 6) by using BHU-60 manufactured by Riken Denshi Co., Ltd.^FiveA / m) measured magnetization.
[0034]
The calcined black has a volume average particle size of 0.01 to 1.0 μm, preferably 0.03 to 0.6 μm.
[0035]
The preferred range of volume resistivity of the fired black is 1 × 10^Five~ 1x10^TenΩcm, more preferably 1 × 10⁶~ 1x10⁸Ωcm.
[0036]
The volume resistivity measurement method indicates a value measured in a powder state under a condition where a certain pressure is applied. In this measurement, the volume resistivity measured in a normal temperature and humidity environment is shown. The calcined black measured in the present invention was measured by the following method under conditions of a temperature of 20 to 25 ° C. and a humidity of 50 ± 5%.
[0037]
That is, for the volume resistivity of the fired black, the static resistance of each fired black was measured using a resistance measuring apparatus as shown in FIG. In the figure, 1 is a measurement particle layer (sample layer), 2 is an insulating pipe, 3 is a weight made of brass, 4 is a bottom plate made of brass, and 5 is a resistance meter. Reading R (Ω) of the resistance measuring device, cross-sectional area S (cm²) And the thickness t (cm) of the sample layer, the static resistance of each fired black was determined by the following equation. In this measurement, 500 g / cm²Is applied to the sample layer.
[0038]
Static resistance (Ω · cm) = R × S / t
The amount added to the toner is preferably 5 to 50% by mass, more preferably 15 to 35% by mass. When the addition amount is less than 5% by mass, blackness and image density cannot be obtained, and when it exceeds 50% by mass, the fixing property may be lowered.
[0039]
  Further, the saturation magnetization of the toner of the present invention containing baked black is 12.6 × 10 6.^-7-18.84 × 10^-6Wb・m / kg, more preferably 37.8 × 10^-7~ 10.08 × 10^-6Wb・m / kg. 12.6 × 10^-7Wb・If it is less than m / kg, there is no effect of suppressing toner scattering, and 18.84 × 10^-6Wb・If it exceeds m / kg, developability may be lowered.
[0040]
By using calcined black as a toner colorant, moderate magnetization, that is, weak magnetism is generated, so that the mixing with the carrier is improved, and as a result, charge rise is quickened and the image density is not lowered. Further, since the magnetic attraction force of the developing roll is applied to the weakly charged toner, toner scattering and fog do not occur.
[0041]
According to the developer employing the toner of the present invention, the baked black colorant is well dispersed in the toner, and has a higher resistance than carbon black and magite. Even in long-term specifications, there is no occurrence of toner spent and charging failure, and it imparts moderate magnetism to the toner, thus maintaining the high image density and preventing the scattering and fogging of weakly charged toner. As a result, a good image can be obtained.
(2) Binder resin
The binder resin (essential component of the toner) used to obtain the toner of the present invention is not particularly limited, and various conventionally known resins such as styrene resins, acrylic resins, styrene / acrylic resins, A polyester resin or the like can be used.
(3) Internal additive
The internal additive (optional component of the toner) used to obtain the toner of the present invention includes a negatively chargeable charge control agent such as an azo metal complex, a salicylic acid metal complex, or a calixarene compound; a nigrosine dye, a quaternary ammonium salt And positively chargeable charge control agents such as triphenyl compounds and triphenylmethane compounds. A mold release agent can also be used as an internal additive, such as olefins such as low molecular weight polypropylene, low molecular weight polyethylene, ethylene-propylene copolymer, microcrystalline wax, carnauba wax, rice wax, montan wax, Examples thereof include those conventionally used such as sazol wax, paraffin wax, amide wax and the like. The addition amount of these release agents is preferably 1 to 15% by mass in the toner.
(4) External additive
As the external additive constituting the toner of the present invention (optional component of the toner), conventionally known inorganic fine particles and organic fine particles can be used, but inorganic fine particles are used from the viewpoint of imparting fluidity to the colored particles. It is preferable to do.
[0042]
Examples of the compound constituting the inorganic fine particles include various inorganic oxides, nitrides, borides and the like. Specific examples thereof include silica, alumina, titania, zirconia, barium titanate, aluminum titanate, Strontium titanate, magnesium titanate, zinc oxide, chromium oxide, cerium oxide, antimony oxide, tungsten oxide, tin oxide, tellurium oxide, manganese oxide, boron oxide, silicon carbide, boron carbide, titanium carbide, silicon nitride, titanium nitride, Examples thereof include boron nitride.
[0043]
The number average primary particle diameter (number average primary particle diameter observed by transmission electron microscope observation and measured by image analysis) of the inorganic fine particles used as the external additive is preferably 10 to 500 nm. The surface of these inorganic fine particles is preferably hydrophobized.
[0044]
Examples of the surface treatment agent include various titanium coupling agents, so-called coupling agents such as silane coupling agents, and silicone oil.
[0045]
As the titanium coupling agent, tetrabutyl titanate, tetraoctyl titanate, isopropyl triisostearoyl titanate, isopropyl tridecylbenzenesulfonyl titanate, bis (dioctyl pyrophosphate) oxyacetate titanate, or the like can be used. As silane coupling agents, γ- (2-aminoethyl) aminopropyltrimethoxysilane, γ- (2-aminoethyl) aminopropylmethyldimethoxysilane, γ-methacryloxypropyltrimethoxysilane, N-β- (N-vinylbenzylaminoethyl) γ-aminopropyltrimethoxysilane hydrochloride, hexamethyldisilazane, methyltrimethoxysilane, butyltrimethoxysilane, isobutyltrimethoxysilane, hexyltrimethoxysilane, octyltrimethoxysilane, decyltri Methoxysilane, dodecyltrimethoxysilane, phenyltrimethoxysilane, o-methylphenyltrimethoxysilane, p-methylphenyltrimethoxysilane and the like can be used. Further, as the silicone oil, dimethyl silicone oil, methylphenyl silicone oil, amino-modified silicone oil, or the like can be used.
[0046]
The degree of hydrophobicity is preferably 25 to 90%. Here, the degree of hydrophobicity is shown by the following formula.
[0047]
Formula: Hydrophobization degree (%) = {a / (a + 50)} × 100
In the formula, a is a value obtained by the following (i) to (ii).
i) After putting 50 ml of distilled water in a 250 ml beaker, inorganic fine particles weighed to 0.2 g are added.
ii) While slowly stirring the system, methanol is dropped from a burette whose tip is immersed in distilled water, and the amount of methanol dropped until the inorganic fine particles are completely wetted is defined as a (ml).
[0048]
When the degree of hydrophobicity of the inorganic fine particles is less than 25%, moisture is adsorbed on the metal powder particles themselves, and it becomes difficult to suppress the occurrence of image blur. In addition, inorganic fine particles having a degree of hydrophobicity exceeding 90% are excessively charged, which causes a decrease in density in continuous printing.
[0049]
As the silicone oil, dimethyl silicone oil, methylphenyl silicone oil, amino-modified silicone oil and the like can be used. As fatty acids, undecyl acid, lauric acid, tridecyl acid, dodecyl acid, myristic acid, palmitic acid, pentadecylic acid, stearic acid, heptadecyl acid, arachidic acid, montanic acid, oleic acid, linoleic acid, arachidonic acid, etc. Chain fatty acids can be used. In addition, as the fatty acid metal salt, a salt of the above long chain fatty acid and a metal (for example, zinc, iron, magnesium, aluminum, calcium, sodium, lithium) can be used, among these, aluminum stearate, Zinc stearate and calcium stearate are preferred.
(5) Toner manufacturing method
The toner of the present invention can be produced by either a pulverization method or a polymerization method, but among them, it is preferably produced by a polymerization method.
[0050]
As the particle diameter of the colored particles constituting the toner of the present invention, the volume average particle diameter measured by Coulter Counter TA-II or Coulter Multisizer is preferably 2 to 10 μm, and more preferably 3.0 to 9 0.0 μm. The particle diameter of the colored particles can be controlled by the production conditions.
[0051]
As a method for adding the baked black, the polymer particles prepared by the emulsion polymerization method are added at the stage of adding and aggregating the flocculant, and the polymer is colored, or the baked black at the stage of polymerizing the monomer. The method of adding and polymerizing to form colored particles can be employed.
[0052]
Furthermore, a low molecular weight polypropylene (number average molecular weight = 1500 to 9000), a low molecular weight polyethylene, or the like as a fixability improver may be added. A preferable fixability improver is an ester compound represented by the following formula.
[0053]
R₁-(OCO-R₂)_n
Where R₁, R₂Represents a hydrocarbon group which may have a substituent, R₁, R₂Is an integer of 1 to 4 carbon atoms and n is 1 to 4. R₁Is preferably 1-20, more preferably 2-5, R₂Is preferably 16 to 30, more preferably 18 to 26, n is 2 to 4, more preferably 3 or 4, and particularly preferably 4.
[0054]
Preferred examples of the ester compound include the following compounds.
[0055]
[Chemical 1]

[0056]
[Chemical 2]

[0057]
The addition amount is 1 to 30% by mass, preferably 2 to 20% by mass, and more preferably 3 to 15% by mass with respect to the whole toner.
[0058]
The toner of the present invention is obtained by dispersing a monomer obtained by dissolving a fixing improver in water and polymerizing it to form particles in which the above exemplary compounds are encapsulated in resin particles. A fused one is preferred.
[0059]
In the toner used in the present invention, it is preferable to fuse resin particles containing a release agent in an aqueous medium. As described above, the resin particles in which the release agent is encapsulated in the resin particles are salted out / fused together with the baked black particles in an aqueous medium, whereby a toner in which the release agent is finely dispersed can be obtained.
[0060]
The toner has a shape with irregularities on the surface from the time of toner production, and furthermore, since it is fused in an aqueous medium, there is little difference in the shape and surface property between particles, and as a result, the surface property is low. Because it tends to be uniform, it can produce deep blackish black.
[0061]
Other production methods include suspension polymerization and emulsion polymerization of the monomer in a liquid to which the necessary additive emulsion is added to produce fine polymer particles, followed by an organic solvent, a flocculant It can manufacture by the method of adding and associating. In the case of association, a method of preparing by mixing with a dispersion liquid such as a release agent and baking black necessary for toner composition, and a toner component such as a release agent and baking black are dispersed in the monomer. And a method of emulsion polymerization. Here, the association means that a plurality of resin particles and fired black particles are fused. In addition, the aqueous medium as used in the field of this invention shows what contained 50 mass% or more of water at least. That is, various constituent materials such as calcined black and a release agent, a charge control agent, and a polymerization initiator are added to the polymerizable monomer, and a homogenizer, a sand mill, a sand grinder, an ultrasonic disperser, etc. Various constituent materials are dissolved or dispersed in the polymerizable monomer. The polymerizable monomer in which these various constituent materials are dissolved or dispersed is dispersed in oil droplets of a desired size as a toner in an aqueous medium containing a dispersion stabilizer using a homomixer or a homogenizer. Thereafter, the stirring mechanism is transferred to a reaction apparatus which is a stirring blade described later, and the polymerization reaction is advanced by heating. After completion of the reaction, the dispersion stabilizer is removed, filtered, washed, and dried to prepare the toner of the present invention.
[0062]
In addition, it is preferable to use a plurality of resins having different molecular weights from the viewpoint of improving the fixing property. In particular, the presence of both a high molecular weight component and a low molecular weight component makes it possible to achieve both improvement in offset property and adhesion to an image forming support such as paper. The molecular weight of the toner resin includes both a high molecular weight component having a peak or shoulder in the region of 160,000 to 1,000,000 and a low molecular weight component having a peak or shoulder in the region of 1,000 to less than 50,000. The resin contains at least the component. It is preferable to use an intermediate molecular weight resin having a peak or shoulder at a peak molecular weight of 15,000 to 100,000. More preferably, it is preferable to use an intermediate molecular weight resin having a peak or shoulder at a portion of 25,000 to 75,000.
[0063]
The resin molecular weight measurement method by GPC is measurement by GPC (gel permeation chromatography) using THF as a solvent. That is, 1 ml of THF is added to 0.5 to 5 mg of a measurement sample, more specifically 1 mg, and stirred at room temperature using a magnetic stirrer or the like to be sufficiently dissolved. Subsequently, after processing with a membrane filter having a pore size of 0.45 to 0.50 μm, the solution is injected into GPC. The measurement conditions of GPC are measured by stabilizing the column at 40 ° C., flowing THF at a flow rate of 1 ml / min, and injecting about 100 μl of a sample having a concentration of 1 mg / ml. The column is preferably used in combination with a commercially available polystyrene gel column. For example, Shodex GPC KF-801, 802, 803, 804, 805, 806, 807 made by Showa Denko KK, TSKgel G1000H, G2000H, G3000H, G4000H, G5000H, G6000H, G7000H, TSK guard column manufactured by Tosoh Corporation Combinations can be mentioned. As a detector, a refractive index detector (IR detector) or a UV detector may be used. In the measurement of the molecular weight of a sample, the molecular weight distribution of the sample is calculated using a calibration curve prepared using monodisperse polystyrene standard particles. About 10 points may be used as polystyrene for preparing a calibration curve.
[0064]
As the polymerizable monomer constituting the resin, styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-chlorostyrene, 3,4-dichlorostyrene, p-phenylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, p-tert-butylstyrene, pn-hexylstyrene, pn-octylstyrene, pn-nonylstyrene, pn-decyl Styrene, styrene or styrene derivatives such as pn-dodecylstyrene, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isopropyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, n-octyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, Methacrylic acid ester derivatives such as lauryl acrylate, phenyl methacrylate, diethylaminoethyl methacrylate, dimethylaminoethyl methacrylate, methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, t-butyl acrylate, acrylic Acrylates such as isobutyl acid, n-octyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, lauryl acrylate, phenyl acrylate, olefins such as ethylene, propylene, isobutylene, vinyl chloride, vinylidene chloride, Halogenated vinyls such as vinyl bromide, vinyl fluoride, vinylidene fluoride, vinyl esters such as vinyl propionate, vinyl acetate, vinyl benzoate, vinyl methyl ether, vinyl ethyl ether Vinyl ethers such as vinyl, vinyl ketones such as vinyl methyl ketone, vinyl ethyl ketone, vinyl hexyl ketone, N-vinyl compounds such as N-vinyl carbazole, N-vinyl indole, N-vinyl pyrrolidone, vinyl naphthalene, vinyl pyridine, etc. Acrylic acid or methacrylic acid derivatives such as vinyl compounds, acrylonitrile, methacrylonitrile, acrylamide and the like can be mentioned, and these vinyl monomers can be used alone or in combination.
[0065]
Further, it is more preferable to use a combination of monomers having an ionic dissociation group as the polymerizable monomer constituting the resin. For example, it has a substituent such as a carboxyl group, a sulfonic acid group, and a phosphoric acid group as a constituent group of the monomer. Specifically, acrylic acid, methacrylic acid, maleic acid, itaconic acid, cinnamic acid, fumaric acid , Maleic acid monoalkyl ester, itaconic acid monoalkyl ester, styrene sulfonic acid, allyl sulfosuccinic acid, 2-acrylamido-2-methylpropane sulfonic acid, acid phosphooxyethyl methacrylate, 3-chloro-2-acid phosphooxypropyl And methacrylate.
[0066]
Furthermore, multifunctional such as divinylbenzene, ethylene glycol dimethacrylate, ethylene glycol diacrylate, diethylene glycol dimethacrylate, diethylene glycol diacrylate, triethylene glycol dimethacrylate, triethylene glycol diacrylate, neopentyl glycol dimethacrylate, neopentyl glycol diacrylate, etc. It is also possible to use a crosslinkable resin by using a functional vinyl.
[0067]
These polymerizable monomers can be polymerized using a radical polymerization initiator. In this case, an oil-soluble polymerization initiator can be used in the suspension polymerization method. Examples of the oil-soluble polymerization initiator include 2,2′-azobis- (2,4-dimethylvaleronitrile), 2,2′-azobisisobutyronitrile, 1,1′-azobis (cyclohexane-1-carboxyl). Nitriles), 2,2'-azobis-4-methoxy-2,4-dimethylvaleronitrile, azo- or diazo-based polymerization initiators such as azobisisobutyronitrile, benzoyl peroxide, methyl ethyl ketone peroxide, diisopropyl peroxycarbonate , Cumene hydroperoxide, t-butyl hydroperoxide, di-t-butyl peroxide, dicumyl peroxide, 2,4-dichlorobenzoyl peroxide, lauroyl peroxide, 2,2-bis- (4,4- t-butylperoxycyclohexyl) propane, tris- Peroxide polymerization initiator or a peroxide such as t- butylperoxy) triazine and the like polymeric initiator having a side chain.
[0068]
Moreover, when using an emulsion polymerization method, a water-soluble radical polymerization initiator can be used. Examples of the water-soluble polymerization initiator include persulfates such as potassium persulfate and ammonium persulfate, azobisaminodipropane acetate, azobiscyanovaleric acid and its salts, hydrogen peroxide and the like.
[0069]
Dispersion stabilizers include tricalcium phosphate, magnesium phosphate, zinc phosphate, aluminum phosphate, calcium carbonate, magnesium carbonate, calcium hydroxide, magnesium hydroxide, aluminum hydroxide, calcium metasilicate, calcium sulfate, barium sulfate, bentonite, silica And alumina. Furthermore, those generally used as surfactants such as polyvinyl alcohol, gelatin, methylcellulose, sodium dodecylbenzenesulfonate, ethylene oxide adduct, and higher alcohol sodium sulfate can be used as the dispersion stabilizer.
[0070]
As the resin excellent in the present invention, those having a glass transition point of 20 to 90 ° C. are preferred, and those having a softening point of 80 to 220 ° C. are preferred. The glass transition point is measured by a differential calorimetric analysis method, and the softening point can be measured by a Koka flow tester. Further, these resins preferably have a molecular weight measured by GPC of 1,000 to 100,000 in terms of number average molecular weight (Mn) and 2000 to 1,000,000 in terms of weight average molecular weight (Mw). Further, the molecular weight distribution is preferably such that Mw / Mn is 1.5 to 100, particularly 1.8 to 70.
[0071]
The flocculant used is not particularly limited, but those selected from metal salts are preferably used. Specifically, as a monovalent metal, for example, an alkali metal salt such as sodium, potassium or lithium, as a divalent metal, for example, an alkaline earth metal salt such as calcium or magnesium, or a divalent metal such as manganese or copper. And salts of trivalent metals such as iron and aluminum, and specific salts include sodium chloride, potassium chloride, lithium chloride, calcium chloride, zinc chloride, copper sulfate, magnesium sulfate, manganese sulfate, etc. Can be mentioned. These may be used in combination. These flocculants are preferably added in an amount equal to or higher than the critical aggregation concentration. The critical flocculation concentration is an index relating to the stability of the aqueous dispersion, and indicates a concentration at which flocculation occurs when a flocculant is added. This critical aggregation concentration varies greatly depending on the emulsified components and the dispersant itself. For example, it is described in Seizo Okamura et al., “Polymer Chemistry 17, 601 (1960) edited by the Japanese Society of Polymer Science”, and the like, and a detailed critical aggregation concentration can be obtained. As another method, a desired salt is added to the target particle dispersion at different concentrations, the ζ (zeta) potential of the dispersion is measured, and the salt concentration at which this value changes is defined as the critical aggregation concentration. You can ask for it.
[0072]
The addition amount of the flocculant may be not less than the critical aggregation concentration, but is preferably 1.2 times or more, more preferably 1.5 times or more the critical aggregation concentration. The infinitely soluble solvent means a solvent that is infinitely soluble in water, and this solvent is selected in the present invention so as not to dissolve the formed resin. Specific examples include alcohols such as methanol, ethanol, propanol, isopropanol, t-butanol, methoxyethanol, and butoxyethanol, nitriles such as acetonitrile, and ethers such as dioxane. In particular, ethanol, propanol, and isopropanol are preferable. The addition amount of the infinitely soluble solvent is preferably 1 to 100% by volume with respect to the polymer-containing dispersion to which the flocculant is added.
[0073]
The toner of the present invention contains at least a resin and a baked black, but may contain a release agent, a charge control agent, or the like, which is a fixing property improving agent, if necessary. Further, an external additive composed of inorganic fine particles, organic fine particles, or the like may be added to the toner particles mainly composed of the resin and the calcined black.
[0074]
The shape factor of the toner of the present invention is represented by the following formula and indicates the degree of roundness of the toner particles.
[0075]
Shape factor = ((maximum diameter / 2)²× π) / projection area
Here, the maximum diameter refers to the width of a particle that maximizes the interval between the parallel lines when the projected image of the toner particles on the plane is sandwiched between two parallel lines. The projected area refers to the area of the projected image of the toner particles on the plane.
[0076]
In the present invention, this shape factor is obtained by taking a photograph in which the toner particles are magnified 2000 times with a scanning electron microscope, and then using “SCANNING IMAGE ANALYZER” (manufactured by JEOL Ltd.) based on this photograph. It was measured by performing analysis. At this time, the shape factor of the present invention was measured by the above formula using 100 toner particles.
[0077]
In the present invention, the number of toner particles having a shape factor in the range of 1.0 to 1.6 is preferably 65% by number or more, and more preferably 70% by number or more. More preferably, the number of toner particles having a shape factor in the range of 1.2 to 1.6 is 65% by number or more, and more preferably 70% by number or more. When the number of toner particles having a shape factor in the range of 1.0 to 1.6 is 65% by number or more, the triboelectric charging property on the developer conveying member or the like becomes more uniform, and excessively charged toner is accumulated. In addition, since it becomes easier to replace the toner from the surface of the developer conveying member, problems such as development ghost are less likely to occur. Further, the toner particles are less likely to be crushed, the contamination of the carrier or the charging member is reduced, and the chargeability of the toner is stabilized.
[0078]
The method for controlling the shape factor is not particularly limited. For example, a method in which toner particles are sprayed into a hot air stream, a method in which toner particles are repeatedly applied with mechanical energy due to impact force in a gas phase, a method in which toner particles are added in a solvent that does not dissolve toner, and a swirl flow is applied. To prepare a toner having a shape factor of 1.0 to 1.6, or 1.2 to 1.6, and adding this to a normal toner so as to be within the range of the present invention. There is. Also, the overall shape is controlled at the stage of adjusting the so-called polymerization method toner, and the toner whose shape factor is adjusted to 1.0 to 1.6 or 1.2 to 1.6 is added to the normal toner in the same manner. There is a way to adjust.
[2] Developer
The toner of the present invention may be either (1) a toner used alone in a so-called non-magnetic one-component developing method that does not use a magnet roll, or (2) a toner used as a two-component developer mixed with a carrier. The use mode (2) above is preferable.
[0079]
The carrier to be mixed with the toner of the present invention is any one of (1) a carrier composed only of magnetic material particles such as iron and ferrite, and (2) a resin-coated carrier in which the surface of core material particles is coated with a resin. However, it is preferable to use the resin-coated carrier of the above (2) from the viewpoint of durability and the like.
[0080]
The particle diameter of the carrier is 15 to 100 μm, preferably 60 to 80 μm, in terms of volume average particle diameter.
[0081]
  As the magnetization characteristics of the carrier, saturation magnetization is 18.8 × 10^-6~ 10.0 × 10^-FiveW・bm / kg is preferred.
[0082]
Examples of the core particles constituting the resin-coated carrier include iron powder, magnetite, and various ferrites. Among these, magnetite and ferrite are preferable.
[0083]
Here, the ferrite contains ferrite containing heavy metals such as copper, zinc, nickel, manganese, alkali metals (eg, Li, Na) and / or alkaline earth metals (eg, Mg, Ca, Sr, Ba). It is preferable to use light metal ferrite, and it is particularly preferable to use the light metal ferrite.
[0084]
The light metal ferrite has a composition represented by the following formula (1) or formula (2).
[0085]
Formula (1) (M₂O)_x(Fe₂O_Three)_1-x
Formula (2) (MO)_x(Fe₂O_Three)_1-x
In the formula, M represents an alkali metal or an alkaline earth metal. M₂O and / or Fe₂O_ThreeA part of may be substituted with an alkaline earth metal oxide. Further, x is 30 mol% or less, preferably 18 mol% or less, and the substituted alkaline earth metal and / or alkali metal oxide is preferably 1 to 15 mol%, more preferably 3 to 15 mol. %.
[0086]
The reason why the light metal ferrite and magnetite are preferable is not only the problem of contamination of waste, which has become popular in recent years, but in addition to these, the carrier itself can be reduced in weight and stress on the toner can be reduced. This is because it has advantages.
[0087]
The resin constituting the resin-coated carrier is not particularly limited, and examples thereof include silicone resins, styrene-acrylic resins, vinylidene fluoride resins, and fluorine resins other than vinylidene fluoride.
[0088]
Although it does not specifically limit as said silicone resin, The condensation reaction type silicone resin hardened | cured by heating dehydration condensation reaction, the room temperature moisture hardening reaction shown below, etc. is used preferably.
[0089]
[Chemical 3]

[0090]
In the above reaction formula, R₁, R₂Represents a substituent such as an alkyl group, and OX represents a group such as an alkoxy group, a ketoxy group, an acetoxy group, or an aminoxy group.
[0091]
Among these, those in which the substituent is a methyl group can provide a dense carrier and a carrier having good durability.
[0092]
Examples of silicone resins preferably used in the present invention include “SR-2411” (manufactured by Toray Silicon), “SR-2410” (manufactured by Toray Silicon), “KR-255” (manufactured by Shin-Etsu Chemical), “KR-”. 271 "(manufactured by Shin-Etsu Chemical Co., Ltd.).
[0093]
Examples of styrene-acrylic resins include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-chlorostyrene, 3,4-dichlorostyrene, p-phenylstyrene, p- Ethyl styrene, 2,4-dimethyl styrene, pt-butyl styrene, pn-hexyl styrene, pn-octyl styrene, pn-nonyl styrene, pn-decyl styrene, pn-dodecyl Styrene or styrene derivatives such as styrene and methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isopropyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, n-octyl methacrylate, 2-ethylhexyl methacrylate, Stearyl methacrylate, lauryl methacrylate Methacrylic acid ester derivatives such as phenyl methacrylate, diethylaminoethyl methacrylate, dimethylaminoethyl methacrylate, methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, t-butyl acrylate, isobutyl acrylate, acrylic Examples include copolymers with acrylic acid ester derivatives such as n-octyl acid, 2-ethylhexyl acrylate, stearyl acrylate, lauryl acrylate, phenyl acrylate, dimethylaminoethyl acrylate, and diethylaminoethyl acrylate. . The content of styrene (derivative) in this copolymer is preferably 20 to 90% by mass from the viewpoint of improving durability.
[0094]
The vinylidene fluoride resin is preferably a copolymer of vinylidene fluoride, tetrafluoroethylene, hexafluoropropylene, monochlorotrifluoroethylene, monofluoroethylene, trifluoroethylene, or the like and a copolymer component. It is particularly preferable that 20% by mass or more of vinylidene chloride is contained in the copolymer.
[0095]
As a copolymer component for obtaining a vinylidene fluoride resin, in addition to the halogen-containing monomer described above, styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p -Chlorostyrene, 3,4-dichlorostyrene, p-phenylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, pt-butylstyrene, pn-hexylstyrene, pn-octylstyrene, p Styrene or styrene derivatives such as -n-nonyl styrene, pn-decyl styrene, pn-dodecyl styrene, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isopropyl methacrylate, isobutyl methacrylate, T-butyl methacrylate, n-octyl methacrylate, 2-ethylhexyl methacrylate , Methacrylic acid ester derivatives such as stearyl methacrylate, lauryl methacrylate, phenyl methacrylate, diethylaminoethyl methacrylate, dimethylaminoethyl methacrylate, methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, acrylic Acrylic acid ester derivatives such as t-butyl acid, isobutyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, lauryl acrylate, phenyl acrylate, dimethylaminoethyl acrylate, diethylaminoethyl acrylate, etc. And a copolymer thereof.
[0096]
As a method of coating the resin on the core material particles, (1) a method in which a resin solution is sprayed on the core material particles and dried, and (2) after the coated resin particles are electrostatically attached to the core material particles. (3) A method of coating by applying mechanical energy, (3) A method of electrostatically adhering the coated resin particles to the core material particles and then heating to a temperature higher than the melting temperature of the resin, and (4) In the resin solution Various methods can be used, such as a method of immersing the core particles, and (5) a method of heating and curing after coating a resin containing a curing agent.
[0097]
The coating amount of the resin may be an amount sufficient to uniformly coat the surface of the core particle, and specifically, 0.1 to 5.0% by mass with respect to the core particle, preferably It is 0.5-3.0 mass%. If the coating amount is too small, the effect cannot be exhibited, and if the coating amount is excessive, the coating resin is liberated and image defects may occur.
[0098]
【Example】
  Examples of the present invention will be described below, but the present invention is not limited thereto.
(1) Production of calcined black
“Firing Black 1”
  After the black pigment Bayferrox R303T (product of Bayer AG) was ground to a volume average particle size of 0.2 μm by a vibrating ball mill (using a medium agate ball) and surface-treated with γ- (2-aminoethyl) aminopropyltrimethoxysilane, Again, it was pulverized by a vibrating ball mill to a volume average particle size of 0.2 μm. Diffraction analysis confirmed that the raw material contained a phase with a spinel structure. The volume average particle size was measured using a laser diffraction particle size analyzer SALD-1000. Analysis shows Fe₂O_Three: MnO ratio was 60:40. The obtained powder particles are designated as fired black 1.
"Firing Black 2"
  In a 30 L stirring tank equipped with an aeration stirrer, FeSO_FourFeSO with a concentration of 200 g / L_Four10.1 L of solution and MnSO_Four・ H₂MnSO with O concentration of 600g / L_Four0.9 L of the solution was combined and purged with nitrogen. Thereafter, 2.3 L of an aqueous sodium hydroxide solution having a NaOH concentration of 656 g / L was added over 15 minutes and heated to 85 ° C. with stirring. Thereafter, 300 L / hour of air was passed at 85 ° C. for 5.5 hours. The black suspension was washed with about 20 L of water on the suction funnel and dried at 80 ° C. in an air circulation drying chamber to obtain a calcined black raw material. The specific surface area of the obtained raw material is 5.3 m as a result of measurement.²/ G. Diffraction analysis confirmed that the raw material contained a phase with a spinel structure. 300 g of the raw material was baked at 700 ° C. for 4 hours in a rotary kiln, and 500 L / hour of air was passed therethrough to obtain baked black. When the obtained fired black was analyzed, Fe₂O_Three: MnO ratio was 80:20. The X-ray diffraction pattern of the pigment shows only the diffraction line of hematite. Grind to 0.3 μm in a vibrating ball mill. The obtained powder particles are designated as fired black 2.
“Firing Black 3”
  For production of raw materials, FeSO_FourFeSO with a concentration of 200 g / L_FourSolution 11.39L and MnSO_Four・ H₂MnSO with O concentration of 600g / L_FourOther than using 4.50L solution and 2.32L sodium hydroxide aqueous solution (656g / L), calcined black2The same method was used. Diffraction analysis confirmed that the raw material contained a phase with a spinel structure. The raw material was calcined at 700 ° C. for 4 hours, and pulverized in a steam jet mill at a steam: product ratio of 3: 1 to obtain calcined black. When the obtained fired black was analyzed, Fe₂O_Three: MnO ratio is 46:54 and includes a phase of hematite structure. The obtained powder particles are designated as fired black 3.
“Firing Black 4”
  Mn_ThreeO_FourProduction: 600 g MnSO / L in a heatable stirring vessel equipped with a gas inlet_Four・ H₂MnSO with a concentration of O_FourSolution 2m^Three7.5m^ThreeDiluted with water. The pH was adjusted to 11 by adding 395 L of 45% sodium hydroxide solution. Then this Mn (OH)₂The suspension is heated to 80 ° C. and 70 m per 6 hours^ThreeWas supplied with air. The obtained solid substance was separated by filtration, washed, and dried at 130 ° C. Mn obtained as described above_ThreeO_Four660kg of filter cake is replaced with 365kg of Cr₂O_ThreeGN (Product of Bayer AG), 332 kg of CuCO_Three・ Cu (OH)₂XH₂O (46% Cu, product of Th. Goldschmidt AG), 9 kg Na₂B_FourO₇・ 5H₂Treated with a rotor-stator mixer with O and 1000 L of water to produce a uniform suspension. After drying this mixture, it was fired in an oxidizing atmosphere at 800 ° C. for 6 hours using a rotary drum furnace. The size of the furnace clinker was first reduced in a ball mill while wet, and then pulverized to 0.4 μm in a cascade of pearl mills to obtain calcined black 4. The composition is Cu: Cr: Mn = 16.5: 27.0: 28.6. According to X-ray diffraction analysis, it was confirmed that this calcined black 4 contained a phase having a spinel structure.
(2) Latex adjustment
(Latex 1)
  A solution prepared by dissolving 7.08 g of an anionic active agent (sodium dodecyl sulfonate: SDS) in ion-exchanged water (3010 g) in a 5000 ml separable flask equipped with a stirrer, temperature sensor, condenser, and nitrogen introduction device. Added. The internal temperature was raised to 80 ° C. while stirring at a stirring speed of 230 rpm under a nitrogen stream. On the other hand, a monomer solution consisting of 70.1 g of styrene, 19.9 g of n-butyl acrylate and 10.9 g of methacrylic acid was prepared. Next, a solution in which 9.2 g of a polymerization initiator (potassium persulfate: KPS) was dissolved in 200 g of ion-exchanged water was added, and then the temperature was raised to 75 ° C., and the monomer solution was added dropwise over 1 hour. Latex particles were prepared by heating and stirring for 2 hours. The process so far is referred to as the HP process. The obtained latex particles are designated as Latex HP.
[0099]
Separately, Exemplified Compound 19) 72. In a solution of 105.6 g of styrene, 30.0 g of n-butyl acrylate, 6.4 g of methacrylic acid, and 5.6 g of n-octyl-3-mercaptopropionic acid ester in a flask having a stirrer. 0 g is heated to 80 ° C. and dissolved. Next, a solution in which SDS = 1.6 g is dissolved in 2700 ml of water is heated to 80 ° C., and the latex particles obtained in the above-mentioned HP step, 28 g corresponding to the solid content are added, and there is a circulation path to the aqueous SDS solution. A solution in which Exemplified Compound 19) was heated to the above monomer was mixed and dispersed by a mechanical disperser (CLEAMIX) to prepare an emulsified liquid containing emulsified particles having a uniform dispersed particle size.
[0100]
Subsequently, a solution obtained by dissolving 5.1 g of a polymerization initiator (kps) in 240 ml of ion exchange water is added to the dispersion having the latex particles, and further 750 ml of water is added, heated to 80 ° C., and heated at 80 ° C. The reaction was performed for 3 hours to prepare a latex in which the intermediate molecular weight was encapsulated using the high molecular weight as a nucleus. This process is referred to as MP process. Further, a solution in which KPS = 7.4 g was dissolved in 200 ml of water was added to the latex, and styrene = 300 g, butyl acrylate = 95 g, methacrylic acid = 15.3 g, and n-octyl-3-butyl in a state kept at 80 ° C. A solution mixed with mercaptopropionic acid ester = 10.4 g was added dropwise over 1 hour. Subsequently, it was made to react for 2 hours and the target latex particle was obtained. This reaction process is called LP process. This latex particle is designated as Latex 1.
(Latex 2)
In a flask having a stirrer, 102.0 g of styrene, 30.0 g of n-butyl acrylate, 6.4 g of methacrylic acid, 72.0 g of Exemplified Compound 19) are heated to 80 ° C. and dissolved. Next, a solution in which SDS = 1.6 g is dissolved in 2700 ml of water is heated to 80 ° C., 28 g of latex particles obtained in the above-described HP step are added in an amount corresponding to the solid content, and a machine having a circulation path to the SDS aqueous solution. A solution in which Exemplified Compound 19) was heated to the above monomer was mixed and dispersed by a type disperser (CLEAMIX) to prepare an emulsified liquid containing emulsified particles having a uniform dispersed particle diameter.
[0101]
Subsequently, a solution obtained by dissolving 5.1 g of a polymerization initiator (KPS) in 240 ml of ion exchange water is added to the dispersion having the latex particles, and further 750 ml of water is added, heated to 80 ° C., and heated at 80 ° C. The reaction was performed for 3 hours to prepare a latex in which the intermediate molecular weight was encapsulated using the high molecular weight as a nucleus.
[0102]
Further, a solution of KPS = 14.8 g dissolved in 400 ml of water was added to the latex, and styrene = 600 g, butyl acrylate = 190 g, methacrylic acid = 30.0 g, and n-octyl-3- (3) were kept at 80 ° C. A solution mixed with mercaptopropionic acid = 20.8 g is added dropwise over 1 hour. Subsequently, it was made to react for 2 hours and the target latex particle was obtained. This latex particle is designated as Latex 2.
(3) Preparation of colored particles Bk
“Colorant dispersion Bk1”
Sodium n-dodecyl sulfate = 5.9 g is dissolved with stirring in 160 ml of ion-exchanged water. While stirring, 1 = 126 g of calcined black 1 was gradually added to this liquid, and then dispersed using CLEARMIX. This dispersion is designated as a colorant dispersion Bk1.
"Colorant dispersion Bk2"
A colorant dispersion Bk2 was obtained in the same manner as in the preparation of the colorant dispersion Bk1, except that calcined black 2 was used.
"Colorant dispersion Bk3"
A colorant dispersion Bk3 was obtained in the same manner as in the preparation of the colorant dispersion Bk1, except that calcined black 3 was used.
"Colorant dispersion Bk4"
In the adjustment of the colorant dispersion Bk1, a colorant dispersion Bk4 was obtained in the same manner except that the calcined black 4 was used.
"Comparative colorant dispersion Bk1"
Sodium n-dodecyl sulfate = 5.9 g is dissolved with stirring in 160 ml of ion-exchanged water. Under stirring, 42 g of carbon black (Regal 330 manufactured by Capot Co., Ltd.) was gradually added, and then dispersed using CLEARMIX. This dispersion is referred to as a comparative colorant dispersion Bk1.
“Comparative Colorant Dispersion Bk2”
Sodium n-dodecyl sulfate = 5.9 g is dissolved with stirring in 160 ml of ion-exchanged water. To this liquid, 126 g of magnetite (MAT305, particle size: 0.3 μm, manufactured by Toda Kogyo Co., Ltd.) was gradually added with stirring, and then dispersed using CLEARMIX. This dispersion is referred to as a comparative colorant dispersion Bk1.
“Comparative Colorant Dispersion Bk3”
Sodium n-dodecyl sulfate = 5.9 g is dissolved with stirring in 160 ml of ion-exchanged water. Under stirring, 42 g of carbon black (Regal 330, manufactured by Capot Co., Ltd.) and 21 g of magnetite (MAT305, particle size: 0.3 μm, manufactured by Toda Kogyo Co., Ltd.) were gradually added, and then dispersed using CLEARMIX. This dispersion is referred to as a comparative colorant dispersion Bk3.
(4) Example of toner production
Toner production example 1
420.7 g of latex 1 described above corresponding to the solid content, 900 ml of ion-exchanged water, and colorant dispersion Bk1 are placed in a 5 L four-necked flask equipped with a temperature sensor, a cooling tube, a nitrogen introducing device, and a stirring device and stirred. . After adjusting to 30 degreeC, 5 mol / L sodium hydroxide aqueous solution was added to this solution, and pH was adjusted to 11.0. Next, an aqueous solution obtained by dissolving 12.1 g of magnesium chloride hexahydrate in 1000 ml of ion-exchanged water was added at 30 ° C. for 10 minutes with stirring. Thereafter, after standing for 3 minutes, temperature increase is started and the temperature is increased to 90 ° C. in 6 minutes (temperature increase rate = 10 ° C./min). In this state, the particle size was measured with a Coulter Counter TAII. When the volume average particle size reached 6.5 μm or more, an aqueous solution in which 80.4 g of sodium chloride was dissolved in 1000 ml of ion-exchanged water was added to stop particle growth. Further, the solution was salted out / fused by changing the liquid temperature in the range of 80 to 95 ° C. and changing the stirring time from 1 hour to 10 hours. Then, it cooled to 30 degreeC on the conditions of 8 degreeC / min, hydrochloric acid was added, pH was adjusted to 2.0, and stirring was stopped. The produced colored particles were filtered, washed repeatedly with ion-exchanged water, then dried at an intake air temperature of 60 ° C. using a flash jet dryer, and then dried at a temperature of 40 ° C. using a fluidized bed dryer. To 100 parts by weight of the obtained colored particles, 0.8 parts by weight of silica fine particles were externally added and mixed with a Henschel mixer to obtain “Toner 1”.
Toner production example 2
“Toner 2” was obtained in the same manner as in Toner Production Example 1 except that colorant dispersion Bk2 was used instead of colorant dispersion Bk1.
Toner production example 3
“Toner 3” was obtained in the same manner as in Toner Production Example 1, except that latex 2 was used instead of latex 1 and colorant dispersion Bk3 was used instead of colorant dispersion Bk1.
Toner production example 4
“Toner 4” was obtained in the same manner as in Toner Production Example 3 except that colorant dispersion Bk4 was used instead of colorant dispersion Bk3.
Toner production example 5 (example of suspension polymerization method)
Styrene = 165 g, n-butyl acrylate = 35 g, calcined black 1 = 27 g, di-t-butyl salicylic acid metal compound = 2 g, styrene-methacrylic acid copolymer = 8 g, paraffin wax (mp = 70 ° C.) = 20 g 60 The mixture was heated to 0 ° C., and uniformly dissolved and dispersed at 12000 rpm with a TK homomixer (manufactured by Tokushu Kika Kogyo Co., Ltd.). To this was added 2,2′-azobis (2,4-valeronitrile) = 10 g as a polymerization initiator and dissolved therein to prepare a polymerizable monomer composition. Next, 450 g of a 0.1 mol / L sodium phosphate aqueous solution was added to 710 g of ion-exchanged water, and 68 g of 1.0 mol / L calcium chloride was gradually added while stirring at 13,000 rpm with a TK homomixer to disperse the tricalcium phosphate. A suspension was prepared. The polymerizable monomer composition was added to this suspension, and stirred at 10,000 rpm for 20 minutes with a TK homomixer to granulate the polymerizable monomer composition. Then, it was made to react at 75-95 degreeC for 5 to 15 hours using the reaction apparatus with a stirring blade. Tricalcium phosphate was dissolved and removed with hydrochloric acid, and then classified in the liquid by centrifugal sedimentation using a centrifugal separator, and then filtered, washed and dried. To 100 parts by mass of the obtained colored particles, 1 part by mass of silica fine particles was externally added and mixed with a Henschel mixer to obtain “Toner 5” by suspension polymerization.
Toner production example 6 (example of pulverization method)
100 parts by weight of a polyester resin (binder resin), 1 = 29 parts by weight of calcined black, 4 parts by weight of polypropylene (Mw: 6600, Mn: 3000, Mw / Mn: 2.20, melting point: 80 ° C.), azo A toner raw material consisting of 1 part by weight of a dye (charge control agent) is premixed with a Henschel mixer, melt-kneaded with a twin-screw kneading extruder (set at 190 ° C.), coarsely pulverized with a hammer mill, jet The toner was pulverized by an air pulverizer and classified by an air classifier to obtain “Toner 6” as colored particles having a volume average particle diameter of 8.0 μm.
・ Production example 1 of comparative toner
A “comparative toner 1” was obtained in the same manner as in toner production example 1 except that the comparative colorant dispersion Bk1 was used instead of the colorant dispersion Bk1.
・ Production example 2 for comparison toner
A “comparative toner 2” was obtained in the same manner as in toner production example 1, except that the comparative colorant dispersion Bk2 was used instead of the colorant dispersion Bk1.
-Comparative toner production example 3
A “comparative toner 3” was obtained in the same manner as in toner production example 1, except that the comparative colorant dispersion Bk3 was used instead of the colorant dispersion Bk1.
[0103]
Details of the obtained toner are shown in Tables 1 and 2 below.
[0104]
[Table 1]

[0105]
[Table 2]

[0106]
(5) Preparation of developer
Each toner thus obtained and a silicone-coated ferrite carrier having a volume average particle diameter of 60 μm were mixed at a toner concentration of 6% by mass to prepare a developer.
(6) Live-action test
Each developer obtained was loaded into a commercially available digital copying machine Sitoos 7075 (manufactured by Konica), and a live-action test of 1 million prints was performed.
[0107]
Conditions: Temperature 30 ° C., humidity 80% RH, original image blackening area ratio 50%
(7) Evaluation
Evaluation was performed according to the following evaluation items.
・ Image density
Measurement was performed using a Sakura Densitometer (manufactured by Konica Corporation) at the beginning and end of the live-action test over 1 million times. If the image density is 1.30 or more, it is at a level where there is no practical problem.
・ Fog
In the initial and final stages of the live-action test over 1 million times, the relative density of the transfer paper relative to the white background was measured using a Sakura Densitometer (manufactured by Konica Corporation). If the fog is 0.005 or less, the level is practically acceptable.
・ In-flight scattering
In the initial and final stages of the live-action test over 1 million times, the scattering of the toner near the transfer device from the developing unit was examined and judged by the following evaluation.
[0108]
◎ ・ ・ ・ No toner scattering
○ ... Slightly scattered toner
Δ: Toner scattering is high
× ... Large amount of toner scattering
・ Toner spent
After 1 million live-action tests, the toner is washed and removed from the developer with an aqueous surfactant solution. 3 g of the resulting washed carrier was washed with 100 ml of acetone, and the spent toner was melted out to the carrier, and the transmittance was measured with a spectrophotometer (wavelength 500 nm). When the transmittance is less than 65, charging failure occurs.
[0109]
◎ ・ ・ ・ Transmittance 90% or more
○ ... Transmittance 80-90%
Δ: Transmittance 65-80%
× ... Transmittance less than 65%
[0110]
[Table 3]

[0111]
As is apparent from Table 3, the developer using the toner of the present invention has moderate magnetization, that is, weak magnetism, so that it has good miscibility with the carrier, quick charge rise, and image density decreases. Thus, it can be seen that toner scattering and fogging do not occur because the magnetic attraction force of the developing roll is applied to the weakly charged toner.
[0112]
【The invention's effect】
According to the developer employing the toner of the present invention, the baked black as the colorant is well dispersed in the toner, so there is no occurrence of spent and poor charging even in long-term use in a high temperature and high humidity environment. In addition, in order to impart appropriate magnetism to the toner, it has the effect of preventing the scattering and fogging of weakly charged toner while maintaining a high image density, and has a remarkable excellent effect that a good image can be stably obtained. .
[Brief description of the drawings]
FIG. 1 is a schematic diagram of a resistance measuring apparatus.
[Explanation of symbols]
1 Measurement particle layer (sample layer)
2 Insulating pipe
3 Weight made of brass
4 Brass bottom plate
5 Resistance meter

Claims (13)

An electrostatic latent image developing toner obtained by fusing at least resin particles and colorant particles in an aqueous medium, wherein the colorant particles contain baked black. toner. 2. The electrostatic latent image developing toner according to claim 1, wherein the fired black is an iron-manganese composite oxide. Fe in the iron-manganese composite oxide ₂ O _Three The toner for developing an electrostatic latent image according to claim 2, wherein the mass ratio of MnO to MnO is 40:60 to 80:20. The saturation magnetization of the fired black is 25.1 × 10 ^-7 ~ 31.38 × 10 ^-6 The toner for developing an electrostatic latent image according to claim 1, wherein the toner is Wb · m / kg. The fired black has a volume resistivity of 1 × 10 ⁶ ~ 1x10 ⁸ The electrostatic latent image developing toner according to claim 1, wherein the toner is Ωcm. A two-component developer obtained by mixing the electrostatic latent image developing toner according to claim 1 and a carrier. A method for producing an electrostatic latent image developing toner, comprising: fusing at least a binder resin and a calcined black as a colorant in an aqueous medium to obtain an electrostatic latent image developing toner. A method for producing an electrostatic latent image developing toner, comprising: fusing at least resin particles and colorant particles containing baked black in an aqueous medium to obtain an electrostatic latent image developing toner. 9. The method for producing a toner for developing an electrostatic latent image according to claim 7, wherein the fired black is an iron-manganese composite oxide. Fe in the iron-manganese composite oxide ₂ O _Three The method for producing a toner for developing an electrostatic latent image according to claim 9, wherein a mass ratio of MnO to MnO is 40:60 to 80:20. The saturation magnetization of the fired black is 25.1 × 10 ^-7 ~ 31.38 × 10 ^-6 The method for producing a toner for developing an electrostatic latent image according to any one of claims 7 to 10, wherein Wb · m / kg. The fired black has a volume resistivity of 1 × 10 ⁶ ~ 1x10 ⁸ The method for producing a toner for developing an electrostatic latent image according to claim 7, wherein the toner is Ωcm. A method for producing a two-component developer, wherein the toner for developing an electrostatic latent image according to any one of claims 1 to 5 and a carrier are mixed to obtain a two-component developer.

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