JP4040432B2 - Toner, image forming method and image forming apparatus - Google Patents

Description

【００８５】
また、本発明に使用される結着樹脂は、酸価が０．１〜１００（より好ましくは１〜５０）ｍｇＫＯＨ／ｇであることが好ましい。結着樹脂の酸価を上記範囲とすることで結着樹脂とワックスとの極性の差が大きくなり、トナー表面にワックス成分が溶け出し易くなり、加圧部材汚れや端部濃度薄、コールドオフセットの防止に効果を発揮する。また、結着樹脂の極性が大きくなることで、加圧部材と結着樹脂との離型性も向上し、加圧部材汚れを発生しにくくする。
【００８６】
結着樹脂の酸価が０．１ｍｇＫＯＨ／ｇより小さいとトナー表面にワックス成分が溶け出しにくく、加圧部材汚れや端部濃度薄、コールドオフセットの防止に効果が得られにくい。また酸価が１００ｍｇＫＯＨ／ｇより大きいとトナーの帯電性が安定しなくなり、高湿環境での現像性や低湿環境でのカブリが悪化しやすい。
【００８７】
本発明において結着樹脂の酸価（ＪＩＳ酸価）は以下の方法により求める。
【００８８】
〈酸価（ＪＩＳ酸価）の測定〉
１）試料の粉砕品０．１〜２．０ｇを精秤し、その重さをＷ（ｇ）とする。
【００８９】
２）２０ｃｃ三角フラスコに試料を入れ、トルエン／エタノール（２：１）の混合溶液１０ｃｃを加え溶解する。
【００９０】
３）指示薬としてフェノールフタレインのアルコール溶液を数滴加える。
【００９１】
４）０．１ｍｏｌ／ｌのＫＯＨのアルコール溶液を用いてフラスコ内の溶液をビュレットを用いて滴定する。この時のＫＯＨ溶液の使用量をＳ（ｍｌ）とする。同時にブランクテストをし、この時のＫＯＨ溶液の量をＢ（ｍｌ）とする。
【００９２】
５）下記式（２）により酸価を計算する（下記式（２）においてｆはＫＯＨ溶液のファクターを表す）。
【００９３】
【数２】
酸価 ＝ （Ｓ−Ｂ）×ｆ×５．６１／Ｗ （２）
【００９４】
結着樹脂の酸価を調整するモノマーとしては、例えば、アクリル酸、メタクリル酸、α−エチルアクリル酸、クロトン酸などのアクリル酸及びそのα−或いはβ−アルキル誘導体や、フマル酸、マレイン酸、シトラコン酸などの不飽和ジカルボン酸及びそのモノエステル誘導体、又は無水マレイン酸などがあり、このようなモノマーを単独、或いは混合して、他のモノマーと共重合させることにより所望の重合体を作ることができる。この中でも、特に不飽和ジカルボン酸のモノエステル誘導体を用いることが酸価をコントロールする上で好ましい。
【００９５】
より具体的には、例えば、マレイン酸モノメチル、マレイン酸モノエチル、マレイン酸モノブチル、マレイン酸モノオクチル、マレイン酸モノアリル、マレイン酸モノフェニル、フマル酸モノメチル、フマル酸モノエチル、フマル酸モノブチル、フマル酸モノフェニルなどのようなα，β−不飽和ジカルボン酸のモノエステル類；ｎ−ブテニルコハク酸モノブチル、ｎ−オクテニルコハク酸モノメチル、ｎ−ブテニルマロン酸モノエチル、ｎ−ドデセニルグルタル酸モノメチル、ｎ−ブテニルアジピン酸モノブチルなどのようなアルケニルジカルボン酸のモノエステル類；フタル酸モノメチルエステル、フタル酸モノエチルエステル、フタル酸モノブチルエステルなどのような芳香族ジカルボン酸のモノエステル類；などが挙げられる。
【００９６】
以上のようなカルボキシル基含有モノマーは、結着樹脂を構成する全モノマーに対し０．１〜３０ｗｔ％添加すればよい。
【００９７】
上記のようなジカルボン酸のモノエステルモノマーが選択される理由は、懸濁重合によりトナーを製造する際、水系の懸濁液に対して溶解度の高い酸モノマーの形で使用するのは適切でなく、溶解度の低いエステルの形で用いるのが好ましいからである。
【００９８】
本発明のトナーは、１２０℃における粘度が１×１０³〜５×１０⁵Ｐａ・ｓであることが好ましい。トナーの１２０℃における粘度を上記範囲に設定することにより、ワックス成分がトナー表面に溶け出し易くなり、低温オフセットや加圧部材汚れ、端部濃度薄の防止により効果を発揮する。
【００９９】
トナーの１２０℃における粘度が１×１０³Ｐａ・ｓより小さい場合には、結着樹脂がワックス成分によって可塑化され易く、加圧部材汚れや端部濃度薄が悪化し易い。一方、上記粘度が５×１０⁵Ｐａ・ｓより大きい場合には、トナーの低温定着性を悪化させ易いうえに、定着時にトナーが加熱されても、トナーの弾性が大きすぎるためにトナー粒子個々を繋ぎ止める力が働きにくく、低温オフセットや端部濃度薄が悪化し易い。
【０１００】
トナーの１２０℃における粘度は以下の方法により求める。
【０１０１】
〈トナーの粘度の測定〉
トナーの粘度測定は高架式フローテスター（島津フローテスターＣＦＴ−５００形）を用い、加圧成形器を用いて成形した約１．５ｇの試料を、一定温度下でプランジャーにより９８．０Ｎの荷重をかけ、直径１ｍｍ、長さ１ｍｍのノズルより押し出す。これによりフローテスターのプランジャー降下量（流出速度）を測定する。この流出速度を各温度（１００℃〜１８０℃の温度範囲を５℃間隔）で測定し、この値より本発明における粘度としての見掛粘度η'を下記式（３）により求める。
【０１０２】
【数３】
η'（Ｐａ・ｓ）＝ ＴＷ'／ＤＷ' ＝ πＰＲ４／８ＬＱ （３）
但し、上記式において
ＴＷ' ＝ ＰＲ／２Ｌ（Ｎ／ｍ²）
ＤＷ' ＝ ４Ｑ／πＲ³（ｓｅｃ^-1）
η'：見掛けの粘度（Ｐａ・ｓ）
ＴＷ'：管壁の見掛けのずり応力（Ｎ／ｍ²）
ＤＷ'：管壁の見掛けのずり速度（ｓｅｃ^-1）
Ｑ：流出速度（ｍ³／ｓｅｃ）
Ｐ：押出圧力（Ｎ／ｍ²）
Ｒ：ノズルの半径（ｍ）
Ｌ：ノズルの長さ（ｍ）
【０１０３】
本発明の結着樹脂は、保存性の観点から、ガラス転移温度（Ｔｇ）が５０〜７０℃であることが好ましく、５５〜６５℃であることがより好ましい。Ｔｇが５０℃より低いと高温雰囲気下でトナーが劣化しやすく、また定着時に高温オフセットが発生しやすくなる。また、Ｔｇが７０℃を超えると、低温定着性が低下する傾向にある。
【０１０４】
本発明で用いられる結着樹脂を製造する方法としては、溶液重合法により高分子量重合体と低分子量重合体を別々に合成した後にこれらを溶液状態で混合し、次いで脱溶剤する溶液ブレンド法、または押出機等により溶融混練するドライブレンド法等が挙げられる。しかしながら、ドライブレンド法では、均一な分散、相溶の点で問題があるため、溶液ブレンド法が最も好適である。また、低分子量重合体に所定の酸価を導入する方法としては、水系の重合法に比べ酸価の設定が容易である溶液重合が好ましい。
【０１０５】
高分子量重合体の合成方法として本発明に用いることの出来る重合法として、溶液重合法、乳化重合法や懸濁重合法が挙げられる。
【０１０６】
乳化重合法は、水にほとんど不溶の単量体（モノマー）を乳化剤を用いて小さい粒子として水相中に分散させ、水溶性の重合開始剤を用いて重合を行う方法である。この方法では反応熱の調節が容易であり、重合の行われる相（重合体と単量体からなる油相）と水相とが別であるから停止反応速度が小さく、その結果重合濃度が大きく、高重合度のものが得られる。更に、重合プロセスが比較的簡単であること、及び重合生成物が微細粒子であるために、トナー製造時において着色剤及び荷電制御剤その他の添加物との混合が容易であるという、トナー用結着樹脂の製造方法として有利な点がある。
【０１０７】
しかしながら、上記乳化重合法では添加される乳化剤のために重合体が不純になり易く、重合体を取り出すには塩析などの操作が必要である。この不便を避けるためには懸濁重合が好都合である。
【０１０８】
懸濁重合は、水系溶媒１００質量部に対してモノマー１００質量部以下（好ましくは１０〜９０質量部）を用いて行うのが良い。使用可能な分散剤としては、ポリビニルアルコール、ポリビニルアルコール部分ケン化物、リン酸カルシウム等が挙げられ、一般に水系溶媒１００質量部に対して０．０５〜１質量部が用いられる。重合温度は５０〜９５℃が適当であるが、使用する開始剤、目的とするポリマーによって適宜選択される。
【０１０９】
結着樹脂の調製に使用される高分子量重合体は、本発明の目的を達成する為に以下に例示する様な多官能性重合開始剤を単独で用いるか、あるいは単官能性重合開始剤と併用して生成することが好ましい。
【０１１０】
多官能構造を有する多官能性重合開始剤の具体例としては、１，１−ジ−ｔ−ブチルパーオキシ−３，３，５−トリメチルシクロヘキサン、１，３−ビス−（ｔ−ブチルパーオキシイソプロピル）ベンゼン、２，５−ジメチル−２，５−（ｔ−ブチルパーオキシ）ヘキサン、２，５−ジメチル−２，５−ジ−（ｔ−ブチルパーオキシ）ヘキシン−３、トリス−（ｔ−ブチルパーオキシ）トリアジン、１，１−ジ−ｔ−ブチルパーオキシシクロヘキサン、２，２−ジ−ｔ−ブチルパーオキシブタン、４，４−ジ−ｔ−ブチルパーオキシバレリックアシッド−ｎ−ブチルエステル、ジ−ｔ−ブチルパーオキシヘキサハイドロテレフタレート、ジ−ｔ−ブチルパーオキシアゼレート、ジ−ｔ−ブチルパーオキシトリメチルアジペート、２，２−ビス−（４，４−ジ−ｔ−ブチルパーオキシシクロヘキシル）プロパン、２，２−ｔ−ブチルパーオキシオクタン及び各種ポリマーオキサイド等の１分子内に２つ以上のパーオキサイド基などの重合開始機能を有する官能基を有する多官能性重合開始剤、及びジアリルパーオキシジカーボネート、ｔ−ブチルパーオキシマレイン酸、ｔ−ブチルパーオキシアリルカーボネート及びｔ−ブチルパーオキシイソプロピルフマレート等の１分子内に、パーオキサイド基などの重合開始機能を有する官能基と重合性不飽和基の両方を有する多官能性重合開始剤が挙げられる。
【０１１１】
これらの内、より好ましいものは、１，１−ジ−ｔ−ブチルパーオキシ−３，３，５−トリメチルシクロヘキサン、１，１−ジ−ｔ−ブチルパーオキシシクロヘキサン、ジ−ｔ−ブチルパーオキシヘキサハイドロテレフタレート、ジ−ｔ−ブチルパーオキシアゼレート、２，２−ビス−（４，４−ジ−ｔ−ブチルパーオキシシクロヘキシル）プロパン、及びｔ−ブチルパーオキシアリルカーボネートである。
【０１１２】
これらの多官能性重合開始剤は、トナー用バインダーとして要求される種々の性能を満足する結着樹脂を得る為には、単官能性重合開始剤と併用されることが好ましい。特に該多官能性重合開始剤の半減期１０時間を得る為の分解温度よりも低い半減期１０時間を有する重合開始剤と併用することが好ましい。
【０１１３】
具体的には、ベンゾイルパーオキシド、１，１−ジ（ｔ−ブチルパーオキシ）−３，３，５−トリメチルシクロヘキサン、ｎ−ブチル−４，４−ジ（ｔ−ブチルパーオキシ）バレレート、ジクミルパーオキシド、α，α'−ビス（ｔ−ブチルパーオキシジイソプロピル）ベンゼン、ｔ−ブチルパーオキシクメン、ジーｔ−ブチルパーオキシド等の有機過酸化物；アゾビスイソブチロニトリル、ジアゾアミノアゾベンゼン等のアゾおよびジアゾ化合物等が挙げられる。
【０１１４】
これらの単官能性重合開始剤は、前記多官能性重合開始剤と同時にモノマー中に添加しても良いが、該多官能性重合開始剤の効率を適正に保つ為には、重合工程において該多官能性重合開始剤の示す半減期を経過した後に添加するのが好ましい。
【０１１５】
これらの開始剤は、効率の点から結着樹脂を構成するモノマー１００質量部に対して０．０５〜２質量部用いるのが好ましい。
【０１１６】
高分子量重合体は、本発明の目的を良好に達成する為に以下に例示する様な架橋性モノマーで架橋されていることが好ましい。
【０１１７】
架橋性モノマーとしては主として２個以上の重合可能な二重結合を有するモノマーが用いられる。架橋性モノマーのうち単官能のものとしては、芳香族ジビニル化合物（例えば、ジビニルベンゼン、ジビニルナフタレン等）；アルキル鎖で結ばれたジアクリレート化合物類（例えば、エチレングリコールジアクリレート、１，３−ブチレングリコールジアクリレート、１，４−ブタンジオールジアクリレート、１，５−ペンタンジオールアクリレート、１，６−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）；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（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クリレートに代えたもの）；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（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）；ポリエステル型ジアクリレート化合物類（例えば、商品名ＭＡＮＤＡ（日本化薬））が挙げられる。
【０１１８】
多官能の架橋性モノマーとしては、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、テトラメチロールプロパントリアクリレート、テトラメチロールメタンテトラアクリレート、オリゴエステルアクリレート、及び以上の化合物のアクリレートをメタアクリレートに代えたもの；トリアリルシアヌレート、トリアリルトリメリテート等が挙げられる。
【０１１９】
これらの架橋性モノマーは、他のモノマー成分１００質量部に対して１質量部以下、好ましくは０．００１〜０．０５質量部の範囲で用いることが好ましい。
【０１２０】
これらの架橋性モノマーのうち、定着性、耐オフセット性の点からトナー用結着樹脂に好適に用いられるものとして、芳香族ジビニル化合物（特にジビニルベンゼン）、芳香族基及びエーテル結合を含む鎖で結ばれたジアクリレート化合物類が挙げられる。
【０１２１】
低分子量重合体の合成方法としては、公知の方法を用いることが出来る。しかしながら、塊状重合法は、高温で重合させて停止反応速度を速めることで、低分子量の重合体を得ることが出来るが、反応をコントロールしにくいという問題点がある。その点、溶液重合法は、溶媒によるラジカルの連鎖移動の差を利用して、また開始剤量や反応温度を調整して、低分子量重合体を温和な条件で容易に得ることが出来るため、結着樹脂中の低分子量重合体を得るには特に好ましい。特に、重合開始剤の使用量を最小限に抑え、開始剤残渣の影響を極力抑えるという点から、加圧条件下での溶液重合法も好ましい。
【０１２２】
高分子量重合体を得る為のモノマー及び、低分子量重合体を得る為のモノマーとしては、次のようなものが挙げられる。
【０１２３】
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ようなスチレン誘導体；エチレン、プロピレン、ブチレン、イソブチレンのようなエチレン不飽和モノオレフィン類；ブタジエン、イソプレンのような不飽和ポリエン類；塩化ビニル、臭化ビニル、沸化ビニルのような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ようなビニルエステル類；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ような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ような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ようなビニルエーテル類；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ようなビニルケトン類；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ような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、アクリルアミドのようなアクリル酸誘導体またはメタクリル酸誘導体が挙げられる。これらのビニルモノマーは単独もしくは２つ以上のモノマーを混合して用いられる。
【０１２４】
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。
【０１２５】
前述したように、本発明のトナーは、ＤＳＣにより測定される昇温時の吸熱ピークにおける最大吸熱ピークのピークトップ温度が７０〜１２０℃であるワックスを含有することを特徴としている。このワックスのピークトップ温度は好ましくは７０〜１００℃、より好ましくは７０〜９０℃、更に好ましくは７０〜８０℃である。このようなワックス成分は、加圧部材汚れや端部濃度薄、低温オフセットが発生し易い状況でトナー表面に溶け出しやすく、金属製スリーブに対する離型剤を向上することができるため効果を示す。
【０１２６】
最大吸熱ピークのピークトップ温度が７０℃より低い場合には、トナーの保存性、現像耐久性、高温オフセット性等が悪化し易い。また、最大吸熱ピークのピークトップ温度が１２０℃より高すぎる場合には、ワックス成分がトナー表面に溶け出しにくくなり、加圧部材汚れや端部濃度薄、低温オフセットの発生防止の効果が望めなくなる。
【０１２７】
また、本発明で用いられるワックスは、ＤＳＣで測定される昇温時の吸熱ピークにおいて、最大吸熱ピークのピーク半値幅が１２℃以下であることが好ましく、１０℃以下であることがより好ましく、８℃以下であることがさらに好ましい。
【０１２８】
このような半値幅を持つワックスはトナー表面に溶け出し易い性質があるため、少ない添加量でも優れた効果が得られる。また、添加量を増やしてもトナーの保存性に悪影響を及ぼさないため、更に効果を増すことも可能となる。半値幅が１２℃より大きいと、保存性が悪化する場合がある。
【０１２９】
さらに、本発明で用いられるワックスは、ＤＳＣで測定される昇温時の吸熱ピークにおいて、始点オンセット温度が５０℃以上（より好ましくは６０℃以上）であり、終点オンセット温度が１００℃以下（より好ましくは９０℃以下）であることが好ましい。このようなワックスはトナーの弾性を維持しながらトナー表面に溶け出すために、加圧部材汚れや端部濃度薄、低温オフセット発生防止に効果がある。
【０１３０】
上記始点オンセット温度が５０℃以下であるとトナーの保存性が悪化しやすい。また、上記終点オンセット温度が１００℃以上であると、トナー表面にワックス成分が溶け出しにくくなり、ワックスの効果が減少することがある。
【０１３１】
本発明におけるワックスのＤＳＣの測定方法を以下に示す。
【０１３２】
〈ＤＳＣ測定法〉
本発明におけるＤＳＣ測定では、ＤＳＣ−７（パーキンエルマー社製）またはＤＳＣ２９２０（ＴＡインスルツルメンツジャパン社製）が利用できる。測定方法はＡＳＴＭ Ｄ３４１８−８２に準じて行う。本発明に用いられるＤＳＣ曲線は、１回昇温させ前履歴をとった後、温度速度１０℃／ｍｉｎで降温し、２度目の昇温時に測定されるＤＳＣ曲線を用いる。各温度の定義は次のように定める。
【０１３３】
・最大吸熱ピークのピークトップ温度
ベースラインからの高さが最も高いピークのピークトップ温度。
【０１３４】
・最大吸熱ピークの半値幅
ベースラインからの高さが最も高いピークの、ベースラインからピークトップまでの高さの２分の１の高さにおける温度幅。
【０１３５】
・吸熱ピークの始点オンセット温度
昇温時曲線の微分値が最大となる点における曲線の接線とベースラインとの交点の温度。
【０１３６】
・吸熱ピークの終点オンセット温度
昇温時曲線の微分値が最小となる点における曲線の接線とベースラインとの交点の温度。
【０１３７】
さらに本発明で用いられるワックスは、Ｅ型粘度計で測定される１２０℃における溶融粘度が１００ｍＰａ・ｓ以下（好ましくは１〜５０ｍＰａ・ｓ、より好ましくは１〜３０ｍＰａ・ｓ、更に好ましくは１〜１５ｍＰａ・ｓ）であることが好ましい。このような粘度の低いワックスはトナーが加熱されワックスが溶融した際に結着樹脂中を移動し易く、トナー表面に溶け出しやすいため効果を発揮しやすい。溶融粘度が１００ｍＰａ・ｓより大きい場合には、本発明で用いる定着装置においては十分な効果を発揮しにくく、加圧部材汚れや端部濃度薄、低温オフセットの発生防止に対する効果が得られにくい。
【０１３８】
本発明におけるワックスの溶融粘度の測定方法を以下に示す。
〈ワックスの溶融粘度の測定〉
ワックス成分の溶融粘度はＥ型回転粘度計を用いて測定される。粘度計としては、ＶＴ−５００（ＨＡＡＫＥ社製）を利用する。後述する実施例においては、ＶＴ−５００を用い、温度レギュレータ付きオイルバスにより測定温度を１２０℃に温度調整し、センサーにＰＫ１，０．５°を使用し、シェアレート６，０００ｓ^-1で測定した。
【０１３９】
本発明に用いられるワックスとして、次のようなものが利用できる。例えばポリオレフィンワックス、ポリエチレンワックス、マイクロクリスタリンワックス、カルナバワックス、フィッシャートロプシュワックス、パラフィンワックス、高級アルコール系ワックス、エステルワックス等の化合物、及びこれらの酸化物やグラフト変性物が挙げられる。
【０１４０】
好ましく用いられるワックスとしては、オレフィンを高圧化でラジカル重合したポリオレフィン；高分子量ポリオレフィン重合時に得られる低分子量副生成物を精製したポリオレフィン；低圧化でチーグラー触媒、メタロセン触媒等の触媒を用いて重合したポリオレフィン；放射線、電磁波、光等を利用して重合したポリオレフィン；高分子量ポリオレフィンを熱分解して得られる低分子量ポリオレフィン；パラフィンワックス；マイクロクリスタリンワックス；フィッシャートロプシュワックス；ジントール法、ヒドロコール法、アーゲ法等により合成される合成炭化水素ワックス；炭素数１個の化合物をモノマーとする合成ワックス；水酸基、カルボキシル基などの官能基を有する炭化水素系ワックス；炭化水素系ワックスと官能基を有する炭化水素系ワックスとの混合物などがある。
【０１４１】
また、これらのワックスを、プレス発汗法、溶剤法、再結晶法、真空蒸留法、超臨界ガス抽出法、融液晶析法等を用いて分子量分布をシャープにしたものや低分子量固形脂肪酸、低分子量固形アルコール、低分子量固形化合物、その他の不純物を除去したものが好ましく用いられる。
【０１４２】
特に好ましく用いられるのは、パラフィンワックス、フィッシャートロプシュワックス、メタロセン触媒を用いて合成されたポリエチレン、ポリエチレン重合時に得られる低分子量副生物の蒸留生成物等である。
【０１４３】
本発明のトナーにおいては、これらのワックスの含有量は、結着樹脂１００質量部に対して０．１〜２０質量部、好ましくは０．５〜１０質量部で用いるのが良い。
【０１４４】
また、本発明のトナーはタップ密度から求めた空隙率が０．４〜０．７（好ましくは０．４５〜０．６５、より好ましくは０．５０〜０．６０）であることを特徴とする。空隙率がこの範囲にあると、記録材上にトナー粒子が密に詰まった状態（記録材単位面積当たりに現像されているトナー質量が同じでも、トナー像の高さが低い）で現像されているため、定着装置のニップ部で多少こすられてもトナー像の乱れが起こりにくく、端部濃度薄の発生防止に効果がある。また、記録材上にトナー粒子が密に詰まった状態で現像されるため、定着時に小さな加圧力でトナーと記録材の接着力を高めることが出来、本発明で用いる定着装置においても低温オフセットの発生を抑制することが出来る。
【０１４５】
上記空隙率が０．４より小さいとトナーが均一に帯電しにくくなり、画像濃度が低くなったり、カブリが多くなることがある。また、上記空隙率が０．７より大きいと端部濃度薄、低温オフセットの発生防止に効果がなくなることがある。
【０１４６】
空隙率は、トナー粒子の粒度分布や、シリカなどの外部添加剤の量や種類を変化させることで調節できる（外部添加剤については後述する）。具体的には、トナーの粒径を小さく、微粉量を多くするほど空隙率は大きくなり易く、逆にトナーの粒径を大きく、微粉量を少なくするほど空隙率は小さくなり易い。また、シリカなどの外部添加剤の量を多くしてトナーの流動性を良くすると空隙率は小さくなり易い。
【０１４７】
本発明における空隙率は以下の式で求められる。
【０１４８】
【数４】
空隙率 ＝ （真密度−タップ密度）／真密度
【０１４９】
真密度及びタップ密度の測定法を以下に示す。
【０１５０】
〈真密度の測定〉
トナー１ｇをＩＲ測定用錠剤成型器に入れ、約１．９６ＭＰａ（２００ｋｇｆ／ｃｍ²）の圧力で１分間加圧し成型する。このサンプルの体積及び質量を測定し真密度を求める。
【０１５１】
〈タップ密度の測定〉
ホソカワミクロン（株）製のパウダーテスターを用い、該パウダーテスターに付属している容器を使用して、該パウダーテスターの取扱説明書の手順にしたがって測定した値を言う。すなわち、パウダーテスターの測定用カップ（内容積：Ｖｃｍ³）にトナーをすり切り一杯入れ、タッピングを行う。タッピング終了後、余分なトナーをブレードですり切った後トナーの質量（Ｗｇ）を測定し、次の式によりタップ密度を得ることができる。
【０１５２】
【数５】
タップ密度 ＝ Ｗ／Ｖ（ｇ／ｃｍ³）
【０１５３】
本発明のトナーは、キャリアと併用して二成分現像剤として用いても良いし、トナーのみからなる（キャリアを用いない）一成分現像剤として用いても良い。本発明のトナーを二成分現像剤として用いる場合のキャリアとしては、従来知られているものがすべて使用可能であるが、具体的には、表面酸化または未酸化の鉄、ニッケル、コバルト、マンガン、クロム、希土類等の金属及びそれらの合金または酸化物などの平均粒径２０〜３００μｍの粒子が使用される。
【０１５４】
また、それらキャリア粒子の表面に、スチレン系樹脂、アクリル系樹脂、シリコーン系樹脂、フッ素系樹脂、ポリエステル樹脂等の物質を付着または被覆させたものが好ましく使用される。
【０１５５】
本発明のトナーは更に磁性材料を含有させて、磁性トナーとしても使用しうる。この場合、磁性材料は着色剤の役割をかねることもできる。本発明において、磁性トナー中に含まれる磁性材料としては、マグネタイト、マグヘマイト、フェライト等の酸化鉄；鉄、コバルト、ニッケルのような金属或いはこれらと金属アルミニウム、コバルト、銅、鉛、マグネシウム、スズ、亜鉛、アンチモン、ベリリウム、ビスマス、カドミウム、カルシウム、マンガン、セレン、チタン、タングステン、バナジウムのような金属の合金及びその混合物等が挙げられる。
【０１５６】
これらの強磁性体は平均粒子径が２μｍ以下、好ましくは０．１〜０．５μｍのものが好ましい。トナー中に含有させる量としては結着樹脂１００質量部に対して約２０〜２００質量部、特に好ましくは結着樹脂１００質量部に対し４０〜１５０質量部が良い。
【０１５７】
本発明のトナーに使用し得る着色剤としては、任意の適当な顔料又は染料があげられる。トナーの着色剤としては、例えば顔料としてカーボンブラック、アニリンブラック、アセチレンブラック、ナフトールイエロー、ハンザイエロー、ローダミンレーキ、アリザリンレーキ、ベンガラ、フタロシアニンブルー、インダンスレンブルー等がある。これらは定着画像の光学濃度を維持するのに必要充分な量が用いられ、結着樹脂１００質量部に対し０．１〜２０質量部、好ましくは０．２〜１０質量部の添加量が良い。また同様の目的で、更に染料が用いられる。例えばアゾ系染料、アントラキノン系染料、キサンテン系染料、メチン系染料があり、結着樹脂１００質量部に対して０．１〜２０質量部、好ましくは０．３〜１０質量部の添加量が良い。
【０１５８】
本発明のトナーは荷電制御剤をさらに有していても良い。トナーを負荷電性に制御するものとして下記物質がある。
【０１５９】
例えば有機金属錯体、キレート化合物が有効であり、モノアゾ金属錯体、アセチルアセトン金属錯体、芳香族ハイドロキシカルボン酸、芳香族ダイカルボン酸系の金属錯体がある。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、無水物、エステル類、ビスフェノール等のフェノール誘導体類などがある。
【０１６０】
また、次に示した一般式（１）で表されるアゾ系金属錯体が好ましい。
【０１６１】
【化１】

［式中、Ｍは配位中心金属を表し、Ｓｃ、Ｔｉ、Ｖ、Ｃｒ、Ｃｏ、Ｎｉ、Ｍｎ、Ｆｅ等があげられる。Ａｒはアリール基であり、フェニル基、ナフチル基などがあげられ、置換基を有してもよい。この場合の置換基としては、ニトロ基、ハロゲン基、カルボキシル基、アニリド基および炭素数１〜１８のアルキル基、アルコキシ基などがある。Ｘ，Ｘ'、Ｙ，Ｙ'は−Ｏ−、−ＣＯ−、−ＮＨ−、−ＮＲ−（Ｒは炭素数１〜４のアルキル基）である。Ａ⁺は水素、ナトリウム、カリウム、アンモニウム、脂肪族アンモニウムあるいはなしを示す。］
【０１６２】
上記一般式（１）中の配位中心金属としては、Ｆｅ又はＣｒが特に好ましく、置換基としてはハロゲン、アルキル基、アニリド基が好ましく、カウンターイオンとしては水素、アルカリ金属アンモニウム、脂肪族アンモニウムが好ましい。またカウンターイオンの異なる錯塩の混合物も好ましく用いられる。
【０１６３】
あるいは、次の一般式（２）に示した塩基性有機酸金属錯体も負帯電性を与えるものであり、本発明に使用できる。
【０１６４】
【化２】

【０１６５】
上記一般式（２）において、中心金属としてはＦｅ、Ｃｒ、Ｓｉ、Ｚｎ、Ａｌが特に好ましく、置換基としてはアルキル基、アニリド基、アリール基、ハロゲンが好ましく、カウンターイオンは水素、アンモニウム、脂肪族アンモニウムが好ましい。
【０１６６】
上記負帯電性の荷電制御剤の中でも、上記一般式（１）で表されるアゾ系金属錯体がより好ましく、とりわけ、下記式（３）で表されるアゾ系鉄錯体が最も好ましい。
【０１６７】
【化３】

【０１６８】
次に、該錯体の具体例を示す。
【０１６９】
【化４】

【０１７０】
【化５】

【０１７１】
【化６】

【０１７２】
また、トナーを正荷電性に制御する荷電制御剤として下記の物質がある。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−ナフトスルフォン酸塩、テトラブチルアンモニウムテトラフルオロボレートなどの四級アンモニウム塩、及びこれらの類似体であるホスホニウム塩等のオニウム塩及びこれらのレーキ顔料、トリフェニルメタン染料及びこれらのレーキ顔料（レーキ化剤としては、りんタングステン酸、りんモリブデン酸、りんタングステンモリブデン酸、タンニン酸、ラウリン酸、没食子酸、フェリシアン化物、フェロシアン化物など）、高級脂肪酸の金属塩；ジブチルスズオキサイド、ジオクチルスズオキサイド、ジシクロヘキシルスズオキサイドなどのジオルガノスズオキサイド；ジブチルスズボレート、ジオクチルスズボレート、ジシクロヘキシルスズボレートなどのジオルガノスズボレート類；グアニジン化合物、イミダゾール化合物。これらを単独で或いは２種類以上組み合わせて用いることができる。これらの中でも、トリフェニルメタン化合物、カウンターイオンがハロゲンでない四級アンモニウム塩が好ましく用いられる。また、一般式（４）
【０１７３】
【化７】

［式中、Ｒ₁はＨまたはＣＨ₃を示し、Ｒ₂及びＲ₃は置換または未置換のアルキル基（好ましくは、Ｃ₁〜Ｃ₄）を示す］
【０１７４】
で表されるモノマーの単重合体；前述したスチレン、アクリル酸エステル、メタクリル酸エステルのような重合性モノマーとの共重合体を正荷電性制御剤として用いることができる。この場合、これらの荷電制御剤は、結着樹脂（の全部または一部）としての作用をも有する。
【０１７５】
特に下記一般式（５）で表される化合物が本発明の構成においては好ましい。
【０１７６】
【化８】

［式中、Ｒ₁、Ｒ₂、Ｒ₃、Ｒ₄、Ｒ₅及びＲ₆は、各々互いに同一でも異なっていてもよい水素原子、置換もしくは未置換のアルキル基または、置換もしくは未置換のアリール基を表し、Ｒ₇、Ｒ₈及びＲ₉は、各々互いに同一でも異なっていてもよい水素原子、ハロゲン原子、アルキル基、アルコキシ基を表し、Ａ^-は、硫酸イオン、硝酸イオン、ほう酸イオン、りん酸イオン、水酸イオン、有機硫酸イオン、有機スルホン酸イオン、有機りん酸イオン、カルボン酸イオン、有機ほう酸イオン又はテトラフルオロボレートから選択される陰イオンを示す。］
【０１７７】
荷電制御剤をトナーに含有させる方法としては、トナー内部に添加する方法とトナー粒子に外部添加（外添）する方法とがある。これらの電荷制御剤の使用量は結着樹脂の種類、他の添加剤の有無、分散方法を含めたトナーの製造方法によって決定されるもので、一義的に限定されるものではないが、好ましくは結着樹脂１００質量部に対して０．１〜１０質量部、より好ましくは０．１〜５質量部の範囲で用いられる。
【０１７８】
本発明のトナーにおいては、帯電安定性、現像性、流動性、耐久性向上の為、シリカ微粉末を外部添加剤として添加することが好ましい。
【０１７９】
本発明に用いられるシリカ微粉末は、ＢＥＴ法で測定した窒素吸着による比表面積が２０ｍ²／ｇ以上（特に３０〜４００ｍ²／ｇ）の範囲内のものが良好な結果を与える。トナー粒子１００質量部に対してシリカ微粉体０．０１〜８質量部、好ましくは０．１〜５質量部使用するのが良い。
【０１８０】
また、上記シリカ微粉末は、必要に応じ、疎水化、帯電性コントロールなどの目的でシリコーンワニス、各種変性シリコーンワニス、シリコーンオイル、各種変性シリコーンオイル、シランカップリング剤、シリル化剤、その他の有機ケイ素化合物等の処理剤で、あるいは種々の処理剤で併用して処理されていることも好ましい。
【０１８１】
また、現像性、耐久性を向上させるために次の無機粉体を外部添加剤として添加することも好ましい。マグネシウム、亜鉛、アルミニウム、セリウム、コバルト、鉄、ジルコニウム、クロム、マンガン、ストロンチウム、錫、アンチモンなどの金属酸化物；チタン酸カルシウム、チタン酸マグネシウム、チタン酸ストロンチウムなどの複合金属酸化物；炭酸カルシウム、炭酸マグネシウム、炭酸アルミニウム等の金属塩；カオリンなどの粘土鉱物；アパタイトなどのリン酸化合物；炭化ケイ素、窒化ケイ素などのケイ素化合物；カーボンブラックやグラファイトなどの炭素粉末が挙げられる。なかでも、酸化亜鉛、酸化アルミニウム、酸化コバルト、二酸化マンガン、チタン酸ストロンチウム、チタン酸マグネシウムなどが好ましい。
【０１８２】
更に次のような滑剤粉末を外部添加剤として添加することもできる。テフロン（登録商標）、ポリフッ化ビニリデンなどのフッ素樹脂；フッ化カーボンなどのフッ素化合物；ステアリン酸亜鉛等の脂肪酸金属塩；脂肪酸、脂肪酸エステル等の脂肪酸誘導体；硫化モリブデン、アミノ酸およびアミノ酸誘導体が挙げられる。
【０１８３】
本発明のトナーを作製するには結着樹脂、ワックス、必要に応じて着色剤としての顔料又は染料、磁性体、荷電制御剤、その他の添加剤等を、ヘンシェルミキサー、ボールミル等の混合機により充分混合してから、加熱ロール、ニーダー、エクストルーダーのような熱混練機を用いて溶融混練して樹脂類を互いに相溶させる。その中に顔料、染料、磁性体等を分散又は溶解させ、冷却固化後粉砕及び分級を行ってトナー粒子を得る。さらに必要に応じ、シリカ微粉末や他の無機粉体等の所望の添加剤をヘンシェルミキサー等の混合機により充分混合することによって本発明のトナーを得ることができる。
【０１８４】
トナー製造装置としては、例えば混合機としては、ヘンシェルミキサー（三井鉱山社製）；スーパーミキサー（カワタ社製）；リボコーン（大川原製作所社製）；ナウターミキサー、タービュライザー、サイクロミックス（ホソカワミクロン社製）；スパイラルピンミキサー（太平洋機工社製）；レーディゲミキサー（マツボー社製）が挙げられ、混練機としては、ＫＲＣニーダー（栗本鉄工所社製）；ブス・コ・ニーダー（Ｂｕｓｓ社製）；ＴＥＭ型押し出し機（東芝機械社製）；ＴＥＸ二軸混練機（日本製鋼所社製）；ＰＣＭ混練機（池貝鉄工所社製）；三本ロールミル、ミキシングロールミル、ニーダー（井上製作所社製）；ニーデックス（三井鉱山社製）；ＭＳ式加圧ニーダー、ニダールーダー（森山製作所社製）；バンバリーミキサー（神戸製鋼所社製）が挙げられ、粉砕機としては、カウンタージェットミル、ミクロンジェット、イノマイザ（ホソカワミクロン社製）；ＩＤＳ型ミル、ＰＪＭジェット粉砕機（日本ニューマチック工業社製）；クロスジェットミル（栗本鉄工所社製）；ウルマックス（日曹エンジニアリング社製）；ＳＫジェット・オー・ミル（セイシン企業社製）；クリプトロン（川崎重工業社製）；ターボミル（ターボ工業社製）；スーパーローター（日清エンジニアリング社製）が挙げられ、分級機としては、クラッシール、マイクロンクラッシファイアー、スペディッククラシファイアー（セイシン企業社製）；ターボクラッシファイアー（日新エンジニアリング社製）；ミクロンセパレータ、ターボプレックス（ＡＴＰ）、ＴＳＰセパレータ（ホソカワミクロン社製）；エルボージェット（日鉄鉱業社製）、ディスパージョンセパレータ（日本ニューマチック工業社製）；ＹＭマイクロカット（安川商事社製）が挙げられ、粗粒などをふるい分けるために用いられる篩い装置としては、ウルトラソニック（晃栄産業社製）；レゾナシーブ、ジャイロシフター（徳寿工作所社）；バイブラソニックシステム（ダルトン社製）；ソニクリーン（新東工業社製）；ターボスクリーナー（ターボ工業社製）；ミクロシフター（槙野産業社製）；円形振動篩い等が挙げられる。
【０１８５】
以下、上記本発明のトナーを用いた本発明の画像形成方法および画像形成装置について説明する。
【０１８６】
本発明の画像形成方法は、記録材上に形成された未定着トナー画像を、上記本発明で用いられる定着手段によって定着させる工程を含む。また、本発明の画像形成装置は上記本発明で用いられる定着手段を有し、上記本発明のトナーを用いて画像形成を行う装置である。
【０１８７】
本発明で用いられる定着手段は、可撓性の円筒状金属素管を基層とする加熱用金属製スリーブと、この加熱用金属製スリーブの内面に接触配置され上記加熱用金属製スリーブを加熱する加熱用部材と、上記加熱用金属製スリーブを介して加熱用部材に圧接され且つ前記加熱用金属製スリーブと平行な軸を有する円筒形状の加圧部材と、を少なくとも有する加熱定着装置である。上記本発明の加熱定着装置において、上記加熱用金属製スリーブ（以下、単に「金属製スリーブ」ということがある）と上記加圧部材とが互いに圧接されることにより所定の温度に維持された定着ニップ部が形成され、未定着トナー画像が形成された記録材がこのニップ部を通過することにより、上記未定着トナー画像が記録材上に定着される。
【０１８８】
本発明で用いられる金属製スリーブを構成する金属素管の厚さは２０〜１００μｍであることが好ましい。また、この金属製スリーブ内面は加熱用部材との接触熱抵抗を低く抑え、定着ニップ部への伝熱を良好にするために、表面粗さＲｚ＝３μｍ以下とすることが好ましい。さらに金属製スリーブ外面の表面粗さをＲｚ＝３μｍ以下とし、この金属製スリーブ上に、接着層としてのプライマー層を含めた離型性層を厚さ２０μｍ以下で形成することも好ましい構成である。
【０１８９】
このように本発明で用いられる加熱定着装置では、熱伝導性が良好な金属製スリーブ内面から加熱用部材により接触加熱することで、画像形成装置の高速化に対応した加熱定着を高い熱効率で実施できる。よって、画像形成装置がプリント信号を受信していない状態のスタンバイ中にヒータへの通電をシャットダウンしておくことができ、省エネルギーの加熱定着が実現できる。
【０１９０】
また、室温状態から画像形成装置の電源をＯＮにした場合でも、即座にプリント信号受信可能になるため、ユーザーを待たせることがない。よって画像形成装置が高速化した場合でも、クイックスタート性に優れ、ファーストプリントタイムも速い加熱定着装置を提供することが可能となる。
【０１９１】
また、樹脂製フィルムに比べ剛性の高い金属製スリーブを使用することで、加圧力を高く設定することが可能になり、さらに画像形成装置の高速化に対応することが可能になる。
【０１９２】
また、金属製スリーブ内面に接触して定着ニップ部を加熱する表面に、耐熱性を有するポリイミド樹脂等の樹脂部材を設けることが好ましい。これにより、金属製スリーブ内面と加熱用部材との摺動をスムーズにすることができるため、さらに高耐久の加熱定着が可能となる。
【０１９３】
また、金属製スリーブに上記表面粗さ内の周方向のスジ加工を施すことにより金属スリーブの回転をスムーズにし、上記加熱用部材表面を傷つけにくくすることができる。
【０１９４】
また、未定着トナー像を記録材上に固着させる加熱定着装置においてトナーと逆極性のバイアスを加圧ローラ側に印加し、金属製スリーブを接地あるいはダイオード接続することで、紙粉、トナー等が金属製スリーブに吸着されることを防止する。これにより耐久的な使用によって金属製スリーブが汚れる等の問題もなく、高耐久の加熱定着装置を提供できる。
【０１９５】
このように、上記加熱定着装置と本発明のトナーとを組み合わせて用いることにより、電源投入直後に定着可能な、待機中の予備加熱を必要としない、消費電力の大幅な低下を実現するオンデマンドタイプの加熱定着装置による高速定着を可能とし、同時に低温オフセット、高温オフセットを発生することなく充分な定着性を有し、さらには加圧部材汚れおよび端部濃度薄をこれまで以上に改善できる画像形成方法を提供できる。
【０１９６】
本発明の画像形成方法は、公知の部材及び手段等を適宜組み合わせて実現することができる。より具体的には、本発明の画像形成方法は、前述した定着工程を実現する定着手段を搭載する改造を、公知の画像形成装置に施すことによって実現することが可能である。以下に、本発明の画像形成方法を実現する上で好適な画像形成装置である本発明の画像形成装置の具体的一例を、図面を参照して説明する。
【０１９７】
（Ａ）画像形成装置の例
図１は本発明の画像形成装置の一例を示す概略構成図である。１は感光ドラムであり、ＯＰＣ、アモルファスＳｅ、アモルファスＳｉ等の感光材料がアルミニウムやニッケルなどのシリンダ状の基盤上に形成されている。感光ドラム１は矢印の方向に回転駆動され、まず、その表面は帯電装置としての帯電ローラ２によって一様帯電される（帯電工程）。
【０１９８】
次に、画像情報に応じてＯＮ／ＯＦＦ制御されたレーザビーム３による走査露光が施され、静電潜像が形成される（潜像形成工程）。この静電潜像は現像装置４で現像、可視化され、トナー画像となる（現像工程）。現像方法としては、ジャンピング現像法、２成分現像法、ＦＥＥＤ現像法などが用いられ、イメージ露光と反転現像とを組み合わせて用いられることが多い。
【０１９９】
可視化されたトナー画像は、転写装置としての転写ローラ５により、所定のタイミングで搬送された転写材としての記録材Ｐ上に感光ドラム１上より転写される（転写工程）。ここで感光ドラム１上のトナー像の画像形成位置と記録材の先端の書き出し位置が合致するようにセンサ８にて記録材Ｐの先端を検知し、搬送のタイミングを合わせている。所定のタイミングで搬送された記録材Ｐは感光ドラム１と転写ローラ５に一定の加圧力で挟持搬送される。
【０２００】
この未定着のトナー画像が転写された記録材Ｐは加熱定着装置６へと搬送され定着される（定着工程）。一方、感光ドラム１上に残存する転写残りの残留トナーは、クリーニング装置７により感光ドラム１表面より除去される（クリーニング工程）。
【０２０１】
（Ｂ）加熱定着装置６
図２は加熱定着装置６の概略構成図である。図２において、１０は定着部材、２０は加圧部材である。定着部材１０は加熱用部材としてのヒータ１１、断熱ステイホルダー１２、定着スリーブとして用いられる金属製スリーブ１３等からなる。加圧部材２０は耐熱性弾性加圧ローラであり、金属製スリーブ１３に圧接されている。すなわち、金属製スリーブ１３と加圧部材２０とが互いに圧接されることにより、定着ニップ部Ｎが形成されている。
【０２０２】
ａ）加熱用金属製スリーブ１３
定着スリーブとして用いられる加熱用金属製スリーブ１３は熱容量の小さなスリーブであり、クイックスタートを可能にするために厚さが１００μｍ以下であり、耐熱性、高熱伝導性を有するＳＵＳ、Ａｌ、Ｎｉ、Ｃｕ、Ｚｎ等の金属の単独あるいは合金からなる可撓性の円筒状の金属素管を基層とした金属製スリーブ（フィルム）である。
【０２０３】
この金属製スリーブ１３は、長寿命の加熱定着装置を構成するために充分な強度を持ち、耐久性に優れた金属製スリーブとするために、２０μｍ以上の厚さが必要である。よって金属製スリーブ１３の厚さとしては２０μｍ以上１００μｍ以下が最適である。
【０２０４】
さらにオフセット防止や記録材の分離性を確保するために、金属製スリーブ１３の表層は、ＰＴＦＥ（ポリテトラフルオロエチレン）、ＰＦＡ（テトラフルオロエチレン−パーフルオロアルキルビニルエーテル共重合体）、ＦＥＰ（テトラフルオロエチレン−ヘキサフルオロプロピレン共重合体）、ＥＴＦＥ（エチレン−テトラフルオロエチレン共重合体）、ＣＴＦＥ（ポリクロロトリフルオロエチレン）、ＰＶＤＦ（ポリビニリデンフルオライド）等のフッ素樹脂、シリコーン樹脂等の離型性の良好な耐熱樹脂が単独でまたは２種以上が混合されてなる離型性層（図示せず）によって被覆されている。
【０２０５】
金属製スリーブ１３表面を上記離型性層により被覆する方法としては、金属製スリーブ基層の外表面に接着層としてのプライマー層を塗布した後に、上記離型性層を形成する。離型性層の形成はディッピング、粉体スプレー等の塗布によるものであっても良いし、チューブ状に形成されたものを金属製スリーブの表面に被せる方式のものであっても良い。
【０２０６】
なお、金属製スリーブの内外面の表面性状および離型性層の厚さ等については後記ｅ）項で詳述する。
【０２０７】
ｂ）加熱用ヒータ１１
加熱用部材としての加熱用ヒータ１１は金属製スリーブ１３の内面に接触配置され、記録材Ｐ上のトナー像を溶融、定着させるニップ部の加熱を行うべく金属製スリーブ１３を加熱する。
【０２０８】
図３は、図２の定着ニップ部Ｎ近傍の部分的拡大図である。また、図４は図２のＩ−Ｉ線に沿った模式的断面図である。図３において、加熱用ヒータ１１は、アルミナ、ＡｌＮ（チッ化アルミ）等の高絶縁性のセラミックスやポリイミド、ＰＰＳ、液晶ポリマー等の耐熱性樹脂からなる基板１１ａの表面に長手方向（図面と直交する方向）に沿って、例えばＡｇ／Ｐｄ（銀パラジウム）、ＲｕＯ₂、Ｔａ₂Ｎ等の通電発熱抵抗層１１ｂをスクリーン印刷等により、厚さ１０μｍ程度、幅１〜５ｍｍ程度の線状もしくは細帯状に塗工して形成してなる通電加熱用部材である。通電発熱抵抗層１１ｂの表面には、金属製スリーブ１３との摺擦に耐えることが可能な薄層のフッ素樹脂層、ポリイミド、ポリアミドイミド、ＰＥＥＫ等の耐熱性樹脂層からなる摺動層１１ｃが設けられている。
【０２０９】
上記基板１１ａの背面（定着ニップ部Ｎと反対側の面）には通電発熱抵抗層１１ｂの発熱に応じて昇温した加熱用ヒータ１１の温度を検知するためのサーミスタ等の温度検知素子１４が配設されている。この温度検知素子１４の信号に応じて、図４に示す長手方向（図４中芯金２１に平行な方向）端部にある電極部１１ｆおよび１１ｇから通電発熱抵抗層１１ｂに印加される電圧のデューティー比や波数等を適切に制御することで、定着ニップ部Ｎ内での温度を略一定に保ち、記録材Ｐ上のトナー像を定着するのに必要な加熱を行う。温度検知素子１４から不図示の温度制御部へのＤＣ通電は不図示のＤＣ通電部およびＤＣ電極部を介して不図示のコネクターにより達成している。
【０２１０】
加熱用ヒータの他の実施形態を図５に示す。この図５も、図３と同様に加熱定着装置の加熱ヒーター近傍を示す部分的断面図である。図５に示すように、ヒータ基板１１ａとして熱伝導性の良好なＡｌＮ（チッ化アルミ）等を用いた場合には、通電発熱抵抗層１１ｂを基板１１ａの定着ニップ部Ｎと反対側に形成してあっても良い。図５において、１１ｄは基板１１ａ上に形成された通電発熱抵抗層１１ｄと温度検知素子１４の間の耐電圧を満足するために設けたガラスコート、フッ素樹脂層等の保護層である。また、１１ｅは上述の１１ｃと同様に金属製スリーブとの摺擦に耐えることが可能な薄層のフッ素樹脂層、ポリイミド、ポリアミドイミド、ＰＥＥＫ等の耐熱性樹脂層からなる摺動層である。
【０２１１】
また、上記金属製スリーブ１３の内面において、加熱用ヒータ１１の定着ニップ部Ｎ側の形状を曲面とすることで、金属製スリーブ１３に屈曲負荷を与えないようにした方が長寿命の定着部材が形成される。あるいは、基板（１１ａ）を金属製のものとし、この金属製基板の上の定着ニップ部の反対側に絶縁層、通電発熱抵抗層を順次積層してなり、上記金属製基板は定着ニップ部側が金属製スリーブと同方向に湾曲した形状を有する金属製の加熱用ヒータを用いてもよい。
【０２１２】
ｃ）断熱ステイホルダー１２
断熱ステイホルダー１２は、加熱用ヒータ１１を保持し、定着ニップ部Ｎと反対方向への放熱を防ぐための断熱部材であり、液晶ポリマー、フェノール樹脂、ＰＰＳ、ＰＥＥＫ等により形成される。この断熱ステイホルダー１２には金属製スリーブ１３が余裕をもってルーズに外嵌されており、金属製スリーブ１３は矢印の方向に回転自在に配置されている。
【０２１３】
また、金属製スリーブ１３は内部の加熱用ヒータ１１および断熱ステイホルダー１２と摺擦しながら回転するため、加熱用ヒータ１１および断熱ステイホルダー１２と金属製スリーブ１３の間の摩擦抵抗を小さく抑える必要がある。このため加熱用ヒータ１１および断熱ステイホルダー１２の表面に耐熱性グリース等の潤滑剤が少量介在されている。これにより金属製スリーブ１３はスムーズに回転することが可能となる。
【０２１４】
ｄ）加圧部材２０
加圧部材２０は、芯金２１の外側に、シリコーンゴムやフッ素ゴム等の耐熱ゴムあるいはシリコーンゴムを発泡して形成された弾性層２２からなるローラ部材であり、弾性層２２の上にＰＦＡ、ＰＴＦＥ、ＦＥＰ等からなる離型性層２３が形成されていてもよい。
【０２１５】
図４に示すように、定着部材１０は、断熱ステイホルダー１２の一部に直接、または断熱ステイホルダーに嵌合等により取り付けられた部材を介して設けられたバネ等の加圧手段１７により、加熱定着に必要な定着ニップ部Ｎを形成するべく長手方向両端部から加圧部材２０に対して十分に加圧されている。また、加圧部材２０の芯金２１の端部に取り付けられた駆動ギア１６により加圧部材２０を回転駆動し、加圧ローラ表面と金属製スリーブ１３表面の摩擦により該金属製スリーブ１３を所定の速度で従動回転させる。
【０２１６】
以上が加熱定着装置６の構成であるが、図２において記録材Ｐは不図示の供給手段によって適宜供給され、耐熱性の定着入口ガイド１５に沿って加熱部材１０と加圧部材２０によって形成される定着ニップ部Ｎに搬送される。そして、加圧部材２０および金属製スリーブ１３の回転によって記録材Ｐが定着ニップ部Ｎを通過することにより、記録材Ｐ上に未定着画像が定着され、定着画像が得られる。
【０２１７】
ｅ）金属製スリーブ１３の内外面の表面粗さ等について
ここで金属製スリーブ１３の内外面の表面粗さ、離型性層の厚さ等に関して以下に説明する。
【０２１８】
まず、金属製スリーブ１３の内面は上記加熱用ヒータ１１と所定の接触幅をもって接触することで加熱用ヒータ１１より発生した熱を定着ニップ部Ｎへ伝熱する必要があり、従来使用されてきた輻射熱による加熱を行う熱ローラ定着装置（図１０参照）とは思想が異なる。よって加熱用ヒータ１１と接触伝熱する金属製スリーブ１３内面の表面粗さは、熱効率に大いに影響する。特に加熱用ヒータ１１の摺動層（図３の１１ｃまたは図５の１１ｅ）の表面と金属製スリーブ１３の内面との接触熱抵抗が大きくなると、熱効率が悪化し、定着不良を起こしてしまう。仮に熱伝導グリース等を介在させた場合でも熱効率の高い加熱定着装置を構成するためには、所定以下の表面粗さに抑えることが好ましい。
【０２１９】
また、上述したように、金属製スリーブ１３の外面には離型性層が形成されているが、離型性層は一般にフッ素樹脂より形成されるため、その熱伝導性は金属製スリーブ１３の熱伝導性に比べて極端に低い。よって、離型性層をあまり厚く形成すると、熱伝導の悪化を招き画像形成装置の高速化に対し、定着ニップ部Ｎで記録材Ｐ上のトナー像に対し十分な熱供給ができなくなる。よって薄い離型性層を金属製スリーブ１３上に形成する必要がある。このとき、金属製スリーブ１３外面の表面粗さは所定以下に抑えることが好ましい。すなわち、離型性層を薄くした場合には、金属製スリーブ１３外面の表面粗さを離型性層によって緩和する効果が得られないため、金属製スリーブ１３外面に離型性層を塗布形成した後の表面粗さは金属スリーブ１３素管の表面粗さと同等か若干小さい粗さのものとなる。よって、金属製スリーブ１３素管の表面粗さが大きいと離型性層を塗布形成後も大きな表面粗さとなり、定着ニップ部Ｎで記録材Ｐとの密着力が得られず、定着不良を引き起こす可能性が大きくなる。
【０２２０】
以上のことから、金属製スリーブ１３の外面の表面粗さを所定以下とし、且つ接着層としてのプライマー層を含み離型性層を所定以下の厚みで塗布形成することにより、十分な定着性能が得られ、画像形成装置の高速化に対応可能となる。
【０２２１】
また、金属製スリーブ１３に周方向に所定以下の表面粗さを有する凹凸形状を施すことにより、金属製スリーブ１３の回転をよりスムーズにすると共に加熱用ヒータ１１の表面にコーティングした離型性層を傷つけにくくする。これによりさらに高耐久の高速対応可能な加熱定着用金属製スリーブ１３を提供することができる。
【０２２２】
以下、図６〜図８を参照して、周方向に適度な凹凸を有する金属製スリーブ１３の製法を示す。まず、図６において、３１は金属製スリーブ１３の基材であり、０．１〜０．５ｍｍ程度のＳＵＳ、Ａｌ、Ｎｉ、Ｃｕ、Ｚｎ等が単独ないしは２種以上の合金状態で形成される金属平板（プランク）である。３２は一般的な深絞り製法における円形内型（ポンチ）、３３は円筒容器状の外型（ダイス）であり、それぞれ金属材料の表面に超硬メッキ等を施した金型である。図６において、金属平板３１を内型３２と外型３３の間に挟み矢印の方向に内型３２を外型３３の方向へ押し込む。また、金属平板３１と外型３３の間には粘度の高い潤滑油、あるいは黒鉛、二硫化モリブデン等の固体潤滑剤を介在させ、絞り性を良くしてある。以上の工程を通常は２〜４回程度、異なる金型で深絞り加工することにより、図７に示すようなカップ状の金属製円筒部材３４を製造する。
【０２２３】
次に、この金属製円筒部材３４が所定の厚みに形成されるようにしごき加工を施す。しごき加工としては、圧延加工、引き抜き加工、絞り加工等どのような加工を途中に経緯してもよいが、最終加工としては、以下に示すような加工方法により金属製スリーブの周方向に所定以下の凹凸を有する加工を施す。例えば、図８の（ａ）および（ｂ）に示すような加工方法が用いられる。
【０２２４】
まず、図８の（ａ）は一般的な絞りスピニング加工を示すものである。図８（ａ）において、固定台３６ｃに取り付けられた軸３６ｂに回転自在に取り付けられた押し当てローラ３６ａを、金属製内型３５と所定の距離だけ常に離間した状態で金属製内型３５方向へ押し付けられるようになっている。金属製内型３５に、上記カップ状に深絞り加工を施した金属製円筒部材３４がはめ込まれ、押さえ部材３７によって金属製円筒部材３４のカップ形状底部が金属製内型３５に密着状態で固定される。この状態で金属製内型３５、金属製円筒部材３４、押さえ部材３７を図の矢印Ａの方向に回転させながら、紙面右方（図８の矢印Ｂ方向）へ徐々に送り込む。端部からは金属製内型３５と所定距離を保って回転自在のローラ３６ａが押し当てられる。
【０２２５】
これにより、金属製円筒部材３４がしごき加工により端部から徐々に薄肉化され、最終的には図８（ｃ）に示すように本実施例における金属製スリーブ１３の所定厚さにまで加工されたカップ状の金属製円筒部材３９が形成される。
【０２２６】
金属製円筒部材３９には、周方向に絞りスピニング加工時のローラ押し当ての凹凸跡３９ａが残る。最終的には、金属製円筒部材３９のカップ形状底部を切り落とすことにより、周方向に適度な凹凸を有する金属製スリーブ１３を得る。
【０２２７】
また、図８（ｂ）に示すように、押し当てローラ３６ａの代わりに段階的に内径が小さく形成された連続ダイス３８ａ、３８ｂ、３８ｃを用い、金属製内型３５と押さえ部材３７により固定された金属製円筒部材３４を回転させながら送り込みしごき加工を行って、金属製円筒部材３４を薄肉化しながら周方向の凹凸形状を付与させる方式であっても良い。
【０２２８】
その他、へら絞り加工等、金属製スリーブ１３の周方向に所定量以下の凹凸を形成できる方法であれば、どのようなしごき加工の加工方法であっても構わない。
【０２２９】
以上の製法で製造した金属製スリーブ１３を用いて、未定着トナー画像が形成された記録材Ｐを加熱定着する場合、熱伝導の観点から、上記周方向の凹凸は３μｍ以下に抑えることが好ましい。
【０２３０】
金属製スリーブ１３の周方向に３μｍ以下の凹凸を形成し、好ましくは、長手方向の表面粗さＲｚを３μｍ以下とし、周方向の表面粗さＲｚ'との関係をＲｚ＞Ｒｚ'とすることで、加熱定着装置の回転駆動を低く抑え、回転をスムーズにすると共に、耐久的な使用による金属製スリーブ内面に接触する加熱用ヒータの樹脂コートを傷つけにくくし、加熱定着装置のさらなる高耐久、高速化を達成することが可能になる。
【０２３１】
さらに、金属製スリーブ１３と加圧部材である加圧ローラ２０の間に電位差を形成し、かつ金属製スリーブ１３を接地状態、もしくはダイオードを介して接地状態とすることで金属製スリーブ１３に紙粉やトナーを付着しにくい構成とすることで、耐久使用を通じて離型性を維持する加熱定着装置を提供することが可能になる。
【０２３２】
金属製スリーブ１３と加圧ローラ２０の間に電位差が設けられた加熱定着装置の模式的断面図を図９（ａ）に、図９（ａ）のII−II線に沿った模式的断面図を図９（ｂ）に、それぞれ示す。図９において、加圧部材である加圧ローラ２０の導電性弾性層２２は、導電性シリコーンゴム、導電性シリコーンスポンジ等からなる導電性が付与された弾性層であり、加圧ローラ芯金２１または導電性弾性層２２に、導電性カーボンチップ等よりなるチップ電極２５を介してバイアス印加手段２４によってトナー像と逆極性のバイアスを印加する。
【０２３３】
図では、トナーが現像部でマイナス帯電される画像形成装置を元に図示しており、加圧ローラ芯金部２１には、プラスバイアスが印加される構成となっている。
【０２３４】
よってトナーが現像部でプラス帯電される画像形成装置の場合、加圧ローラ芯金２１には、マイナスバイアスが印加される構成となる。
【０２３５】
また、金属製スリーブ１３の端部では、接着層としてのプライマー層、フッ素樹脂層からなる離型性層がコーティングされていない金属製スリーブ素材がむき出しになっている部位１３ａを設け、この部位１３ａよりアモルファス導電繊維よりなる導電ブラシ１８を介して接地状態に構成されている。
【０２３６】
または、トナー像と同電位の電荷が金属製スリーブ１３に保持されるようにダイオード接続されていても良い。
【０２３７】
以上の構成により、加圧ローラ２０側に積極的にバイアス印加する構成とすることで、金属製スリーブ１３には紙粉、トナー等が吸着されにくくなる。よってパルプ材を主原料とするカット紙等に形成されたトナー像を加熱定着する場合の上記加熱定着装置においては、表面粗さＲｚ＝３μｍ以下とした金属製スリーブ１３の表面の離型性層には、静電気的にも紙粉やトナーの汚染が発生しづらく、耐久的な使用によって離型性が損なわれることがないため、長寿命の加熱定着装置が提供される。
【０２３８】
なお、本発明に用いられる定着手段は、定着部材の離型性を維持するためのオイルを定着部材に塗布するオイル塗布方式の定着手段であっても良いし、オイルレス系の定着手段であっても良く、これらの方式の違いによらず同様に効果を奏する。
【０２３９】
また、本発明に用いられる定着手段において、加熱用部材は、通電により発熱するものであれば、通電時の抵抗によって発熱するものに限定されず、例えば通電時の電磁誘導によって発熱する電磁誘導発熱性部材によって形成することもできる。
【０２４０】
また、本発明に用いられる定着手段は、記録材上のトナーの加熱に広く適用することが可能であり、例えば記録材上の画像を仮定着処理する像加熱装置、つや等の画像表面性を改質する像加熱装置等にも適用することができる。
【０２４１】
また、前述した実施の形態では、定着部材１０を加圧部材２０に向けて付勢する構成を示したが、本発明はこの構成に限定されず、加圧部材２０を定着部材１０に向けて付勢しても良く、また定着部材１０および加圧部材２０の両方を互いに接近する方向に付勢しても良い。
【０２４２】
また、前述した実施の形態では、バネに代表されるような、充分な付勢力を発現する加圧手段１７による付勢によって定着ニップ部Ｎを形成する構成を示したが、本発明はこの構成に限定されず、定着部材１０と加圧部材２０の位置を固定して所望の定着ニップＮを形成しても良い。
【０２４３】
【実施例】
以下に、実施例を挙げて本発明を具体的に説明するが、本発明はこれらの実施例にのみ限定されるものではない。
【０２４４】
〈ワックス〉
実施例及び比較例で使用した各ワックスＡ〜Ｉの物性を表１に示す。また、ワックスＡのＤＳＣ測定により得られた昇温曲線を図１２に示す。
【０２４５】
【表１】

【０２４６】
次に、トナーに用いられる結着樹脂を以下のように調製した。
【０２４７】
〈結着樹脂の製造例１〉
［低分子量重合体（Ｌ−１）の合成］
４つ口フラスコ内にキシレン３００質量部を投入し、攪拌しながら容器内を充分に窒素で置換した後、昇温して還流させた。この還流下で、スチレン７５質量部、アクリル酸−ｎ−ブチル１８質量部、マレイン酸モノブチル７質量部及びジ−ｔｅｒｔ−ブチルパーオキサイド２質量部の混合液を４時間かけて滴下した後、２時間保持して重合を完了し、低分子量重合体（Ｌ−１）溶液を得た。
【０２４８】
［高分子量重合体（Ｈ−１）の合成］
４つ口フラスコ内に脱気水１８０質量部とポリビニルアルコールの２質量％水溶液２０質量部を投入した後、スチレン７０質量部、アクリル酸−ｎ−ブチル２５質量部、マレイン酸モノブチル５質量部、ジビニルベンゼン０．００５質量部、及び２，２−ビス（４，４−ジ−ｔｅｒｔ−ブチルパーオキシシクロヘキシル）プロパン（半減期１０時間、温度；９２℃）０．１質量部の混合液を加え、攪拌して懸濁液とした。
【０２４９】
フラスコ内を十分に窒素で置換した後、８５℃まで昇温して重合を開始した。同温度に２４時間保持した後、ベンゾイルパーオキサイド（半減期１０時間、温度；７２℃）０．１質量部を追加添加した。さらに、１２時間保持して重合を完了した。その後、得られた高分子量重合体（Ｈ−１）を濾別し、水洗、乾燥させた。
【０２５０】
［結着樹脂の製造例１］
４つ口フラスコ内に、キシレン１００質量部、上記高分子量重合体（Ｈ−１）２５質量部を投入し、昇温して還流下で攪拌し、予備溶解を行った。この状態で１２時間保持し、予備溶解液（Ｙ−１）を得た。
【０２５１】
一方、別容器に上記低分子量重合体（Ｌ−１）の均一溶液３００質量部を投入し、還流させた。上記予備溶解液（Ｙ−１）と低分子量重合体（Ｌ−１）溶液を還流下で混合した後、有機溶剤を留去し、得られた樹脂を冷却、固化後粉砕してトナー用結着樹脂（Ｉ）を得た。
【０２５２】
上記結着樹脂（Ｉ）を分析したところ、ＧＰＣにより得られた分子量分布におけるメインピークはＭｗ（重量平均分子量）＝１５６００、サブピークがＭｗ＝１１４万、ＴＨＦ不溶分は２．１質量％、酸価は２１ｍｇＫＯＨ／ｇであった。結着樹脂（Ｉ）の分子量分布等の物性を表２に示す。
【０２５３】
［低分子量重合体（Ｌ−２）の合成］
４つ口フラスコ内にキシレン３００質量部を投入し、攪拌しながら容器内を充分に窒素で置換した後、昇温して還流させた。この還流下で、スチレン７５質量部、アクリル酸−ｎ−ブチル１８質量部、マレイン酸モノブチル７質量部及びジ−ｔｅｒｔ−ブチルパーオキサイド２．５質量部の混合液を４時間かけて滴下した後、２時間保持して重合を完了し、低分子量重合体（Ｌ−２）溶液を得た。
【０２５４】
［低分子量重合体（Ｌ−３）の合成］
４つ口フラスコ内にキシレン３００質量部を投入し、攪拌しながら容器内を充分に窒素で置換した後、昇温して還流させた。この還流下で、スチレン７５質量部、アクリル酸−ｎ−ブチル１８質量部、マレイン酸モノブチル７質量部及びジ−ｔｅｒｔ−ブチルパーオキサイド１．５質量部の混合液を４時間かけて滴下した後、２時間保持して重合を完了し、低分子量重合体（Ｌ−３）溶液を得た。
【０２５５】
［高分子量重合体（Ｈ−２）の合成］
４つ口フラスコ内に脱気水１８０質量部とポリビニルアルコールの２質量％水溶液２０質量部を投入した後、スチレン７０質量部、アクリル酸−ｎ−ブチル２５質量部、マレイン酸モノブチル５質量部、ジビニルベンゼン０．００３質量部、及び２，２−ビス（４，４−ジ−ｔｅｒｔ−ブチルパーオキシシクロヘキシル）プロパン（半減期１０時間、温度；９２℃）０．１５質量部の混合液を加え、攪拌して懸濁液とした。
【０２５６】
フラスコ内を十分に窒素で置換した後、８５℃まで昇温して重合を開始した。同温度に２４時間保持した後、ベンゾイルパーオキサイド（半減期１０時間、温度；７２℃）０．１５質量部を追加添加した。さらに、１２時間保持して重合を完了した。その後、得られた高分子量重合体（Ｈ−２）を濾別し、水洗、乾燥させた。
【０２５７】
［高分子量重合体（Ｈ−３）の合成］
４つ口フラスコにスチレン８５質量部、メタアクリル酸ブチル１５質量部を投入し、塊状重合させた後、キシレンを添加して溶媒存在下で溶液重合を完了し、高分子量重合体（Ｈ−３）を得た。
【０２５８】
［結着樹脂の製造例２〜４］
結着樹脂の製造例１において、高分子量重合体Ｈ−１〜Ｈ−３と低分子量重合体Ｌ−１〜Ｌ−３を表２に示すように組み合わせた以外は、上記製造例１と同様の方法を用いて結着樹脂II〜IVを得た。得られた結着樹脂II〜IVの分子量分布等の物性を表２に示す。
【０２５９】
［結着樹脂の製造例５］
結着樹脂の製造例１の低分子量重合体（Ｌ−１）の合成において、マレイン酸モノブチルを使用せず、ジビニルベンゼンを用い且つ開始剤量を調整した以外は上記Ｌ−１の合成方法と同様の方法を用いてＧＰＣ測定による分子量分布におけるピークが一つの結着樹脂（Ｖ）を得た。得られた結着樹脂Ｖの分子量分布等の物性を表２に示す。
【０２６０】
【表２】

【０２６１】
〈実施例１〉
結着樹脂（Ｉ） １００質量部
マグネタイト（平均粒径０．２５μｍ） １００質量部
モノアゾ鉄錯体 ２質量部
ワックスＡ ３質量部
上記原材料をヘンシェルミキサーで予備混合した後、１２０℃に設定した二軸混練押し出し機によって混練した。得られた混練物を冷却し、カッターミルで粗粉砕した後、ジェット気流を用いた粉砕機を用いて微粉砕した。得られた微粉砕物をコアンダ効果を利用した多分割分級機を用いて分級し、重量平均径６．８μｍの負帯電性磁性トナーを得た。このトナー１００質量部に負帯電性疎水性シリカ０．８質量部をヘンシェルミキサーで外添混合してトナー１を得た。トナー１のＴＨＦ不溶分量、ＴＨＦ可溶成分のＧＰＣ測定により得られる分子量分布におけるピーク分子量、１２０℃における溶融粘度、タップ密度から求めた空隙率を表３に示す。
【０２６２】
この磁性トナー１の定着試験、オフセット試験、保存性試験、現像耐久試験、加圧部材汚れ及び端部濃度薄の評価を以下の方法により行った。
【０２６３】
実験に用いた加熱定着装置の基本的構成として、加熱用ヒータ１１としては、図５に示す構成のものを用いた。即ち、ＡｌＮからなる基板１１ａを用い、このヒータ基板１１ａの定着ニップ部Ｎが形成される面の反対側の面に、通電発熱抵抗層１１ｂを形成した。この通電発熱抵抗層としては、Ａｇ／Ｐｄの導電剤とマトリックス成分としての燐酸系ガラスの混合物を有機溶剤、バインダー、分散剤等と混合してペースト状にしたものをスクリーン印刷して６００℃で焼成したものを用いた。また、ＡｌＮのヒータ基板１１ａの定着ニップ部Ｎ側の面には摺動性の良好なポリイミドからなる摺動層１１ｅを１０μｍの厚さでスクリーン印刷して形成した。
【０２６４】
また、金属製スリーブ１３（図２参照）として、内径３０ｍｍ、厚み５０μｍの円筒状ステンレス鋼にプライマー層を５μｍ、ＰＦＡ樹脂を１０μｍディッピングによって塗布し、外径３０．１３ｍｍの円筒状に形成したものを用いた。金属製スリーブ１３の内面の表面粗さＲｚを２μｍ、外面の表面粗さＲｚを２μｍとした。
【０２６５】
また、加圧ローラ２０（図２参照）は、φ２０ｍｍのＡｌ芯金２１に、シリコーンゴム層を厚み５ｍｍで形成し、さらに外層にＰＦＡチューブを被覆したものを用いた。
【０２６６】
［定着性及びオフセット試験］
実験では、画像形成装置の記録材搬送スピードが２００ｍｍ／ｓｅｃとなるように調整して、加熱用ヒータ１１による温度調節を任意に設定できるようにし、加熱用ヒータ１１の通電発熱抵抗層１１ｂへの通電を開始してから６秒後に未定着トナー像が形成された記録材Ｐを定着ニップ部Ｎに挿入し、各項目に対して確認した。
【０２６７】
定着試験は、１１０〜２２０℃の範囲で金属製スリーブ中心部の温度を５℃おきに調節し、それぞれの温度で７５ｇ／ｍ²紙を用いた未定着画像の定着を行い、得られた画像を４．９ｋＰａの荷重をかけたシルボン紙で５往復摺擦し、摺擦前後の画像濃度の濃度低下率が５％以下になる点を定着温度とした。この温度が低いほど低温定着性に優れたトナーである。
【０２６８】
高温オフセット性については、上記定着試験で画像上にオフセット現象による汚れが発生した温度を目視で確認した。この温度が高いほど高温オフセット性に優れたトナーである。
【０２６９】
低温オフセット性については、上記定着試験で画像上にオフセット現象による汚れが発生した温度を目視で確認した。この温度が低いほど低温オフセット性に優れたトナーである。
【０２７０】
［耐久現像試験］
市販のレーザービームプリンタＬａｓｅｒＪｅｔ ４０００（Ａ４、１６枚／分：Ｈｅｗｌｅｔｔ Ｐａｃｋａｒｄ社製）を改造して上記定着方式による定着装置を組み込み、Ａ４サイズの画像面積率５％の原稿を用い、Ａ４サイズの７５ｇ／ｍ²の転写紙に低温低湿（１５℃、１０％ＲＨ）、高温高湿（３２．５℃、８０％ＲＨ）環境でそれぞれ５０００枚の画出し試験を行い、試験後のベタ黒画像の画像濃度を測定した。低温低湿環境についてはベタ白画像のカブリも測定を行った。画像濃度はマクベス濃度計（マクベス社製）でＳＰＩフィルターを使用して反射濃度の測定を行い、５点平均で算出した。カブリは反射濃度計（リフレクトメーター モデル ＴＣ−６ＤＳ 東京電色社製）を用いて測定し、ベタ白部反射濃度の最悪値から、画像形成前の転写材の反射平均濃度を引いたものをカブリ量とした。
【０２７１】
［保存性］
トナー１０ｇを５０ｍｌのポリカップに入れ、５０℃の恒温槽に５日間安置し、その時のトナーのブロッキング程度を評価した。
【０２７２】
Ａ：トナーの流動性は変わらない
Ｂ：流動性は悪化しているがすぐ回復する
Ｃ：凝集体がある
Ｄ：ブロッキングしている
【０２７３】
［加圧部材汚れ］
耐久現像試験で用いた改造機を使用し、７５ｇ／ｍ²のＡ４サイズの転写紙に画像面積率５％の原稿を低温低湿環境で３枚連続プリント後１０分間停止するというプリントモードで、１０００枚の画出し試験を行い、試験後の定着器の加圧部材の汚れの程度と、転写紙に黒ポチ等の汚れが出ているかを目視で評価した。
【０２７４】
Ａ：加圧部材に汚れが全く無い
Ｂ：加圧部材にわずかに汚れがあるが、転写紙には汚れは出ていない
Ｃ：転写紙１枚あたりに１〜３点の汚れが出ている
Ｄ：転写紙１枚あたりに４〜６点の汚れが出ている
Ｅ：転写紙１枚あたりに７〜１０点の汚れが出ている
Ｆ：転写紙全体にひどい汚れがある
【０２７５】
［端部濃度薄］
定着性及びオフセット試験で用いた上記定着方式による外部定着装置を用い、定着温度１９０℃、プロセススピードを２００ｍｍ／ｓｅｃ、加圧力を７８Ｎ、ニップが６ｍｍとなるように設定し、７５ｇ／ｍ²紙を用いた均一なベタ黒未定着画像の定着を行い、得られた画像の両端から１ｃｍの部分の画像濃度６点の平均を端部濃度とし、中央部の画像濃度３点の平均から引いた濃度差を端部濃度薄として評価した。
【０２７６】
画像濃度はマクベス濃度計（マクベス社製）でＳＰＩフィルターを使用して反射濃度の測定を行った。濃度差が小さいほど濃度均一性に優れたトナーである。
【０２７７】
Ａ：濃度差 ０以上０．０２未満
Ｂ：濃度差 ０．０２以上０．０５未満
Ｃ：濃度差 ０．０５以上０．１０未満
Ｄ：濃度差 ０．１０以上０．１５未満
Ｅ：濃度差 ０．１５以上０．２０未満
Ｆ：濃度差 ０．２０以上
【０２７８】
各試験の評価結果を表４に示す。表４から分かるように、良好な定着特性、耐久特性、保存性が得られ、加圧部材汚れ及び端部濃度薄の発生もなかった。
【０２７９】
〈実施例２〜１０〉
実施例１において、結着樹脂とワックスを表３に示す様に変えた以外は実施例１と同様の方法を用いてトナー２〜１０を得た。得られたトナー２〜１０について実施例１と同様に評価を行った。評価結果を表４に示す。
【０２８０】
〈実施例１１〉
実施例１のトナー製造時の粉砕、分級条件を変更して重量平均径１０．２μｍの負帯電性磁性トナーを得た。このトナー１００質量部に負帯電性疎水性シリカ０．６質量部をヘンシェルミキサーで外添混合してトナー１１を得た。得られたトナー１１について実施例１と同様に評価を行った。評価結果を表４に示す。
【０２８１】
〈実施例１２〉
実施例１のトナー製造時の粉砕、分級条件を変更して重量平均径４．１μｍの負帯電性磁性トナーを得た。このトナー１００質量部に負帯電性疎水性シリカ１．２質量部をヘンシェルミキサーで外添混合してトナー１２を得た。得られたトナー１２について実施例１と同様に評価を行った。評価結果を表４に示す。
【０２８２】
〈比較例１〜３〉
実施例１において、結着樹脂とワックスを表３に示す様に変えた以外は実施例１と同様にして、トナー１３〜１５を得た。得られたトナー１３〜１５について実施例１と同様に評価を行った。評価結果を表４に示す。
【０２８３】
【表３】

【０２８４】
【表４】

【０２８５】
【発明の効果】
本発明によれば、現像性、低温定着性、高温オフセット性、低温オフセット性に優れ、かつ加圧部材汚れや端部濃度薄の発生の防止に特に優れた性能を示すトナー及び画像形成方法を提供することが出来る。
【図面の簡単な説明】
【図１】 本発明の画像形成装置の一例を示す概略構成図
【図２】 加熱定着装置６の概略構成図（横断面模型図）
【図３】 図２の定着ニップ部近傍の部分的拡大図
【図４】 加熱定着装置の縦断面図（図２のＩ−Ｉ線に沿った模式的断面図）
【図５】 加熱用ヒータの他の実施形態を表す部分的模式図
【図６】 金属製スリーブ製造方法である深絞り加工の説明図
【図７】 製造途中の金属製スリーブの形状を説明する図
【図８】 （ａ）と（ｂ）は金属製スリーブ製造方法であるしごき加工の説明図、（ｃ）はしごき加工終了時の金属製スリーブ形状の説明図
【図９】 金属製スリーブ１３と加圧ローラ２０の間に電位差が設けられた加熱定着装置の模式的断面図
【図１０】 従来技術の加熱定着装置（定着ローラ方式）の概略構成図
【図１１】 従来の加熱定着装置（定着フィルム方式）の概略構成図
【図１２】 ワックスＡのＤＳＣ測定図
【符号の説明】
１１ 加熱用ヒータ
１２ 断熱ステイホルダー
１３ 金属製スリーブ
１４ 温度検知素子
２０ 加圧部材
２４ バイアス印加手段[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a toner used in an image forming method such as electrophotography, electrostatic recording, electrostatic printing, and toner jet, an image forming method using the toner, and an image forming apparatus.
[0002]
[Prior art]
Conventionally, as a fixing device provided in an image forming apparatus that employs an electrophotographic system, an electrostatic recording system, etc., a fixing roller and a pressure roller that rotate a recording material carrying an unfixed toner image in pressure contact with each other are provided. A so-called heat fixing apparatus is widely used in which fixing is performed on a recording material by passing through a nip portion formed by the above method.
[0003]
An example of a conventional heat fixing apparatus is shown in FIG. Reference numeral 40 denotes a fixing roller provided with a heating means, and a halogen lamp 41 is disposed inside an aluminum hollow core 42 having a thickness of about 1 to 4 mm so as to satisfy mechanical strength. The halogen lamp 41 is heated sufficiently to melt the toner on the recording material P from the inside of the hollow core metal 42 by energization from a power source (not shown).
[0004]
In order to improve the absorption of radiant heat by the halogen lamp 41, the inside of the hollow core metal 42 is generally coated with a black substance (for example, Okitsumo) having an absorption rate of 90% or more on the entire surface. The inner surface of the hollow metal core 42 is rough for the purpose of preventing reflection of the radiant heat and increasing the absorption rate, and Rz = 10 μm or more.
[0005]
Further, in order to fix the toner on the recording material P onto the recording material P without offset, polytetrafluoroethylene (PTFE), perfluoro, which exhibits excellent releasability on the outside of the hollow core metal 42. A release layer 43 such as an alkoxytetrafluoroethylene copolymer (PFA) is formed. The releasable layer 43 is formed in the shape of a tube on the hollow core metal 42 whose surface roughness is Rz = 5 μm or more by blasting or etching, or electrostatic spraying, dipping coating, etc. And has an adhesive force to the hollow core metal 42. In some cases, a conductive member such as carbon black is mixed in the releasable layer 43 in order to prevent an offset that occurs because the surface of the fixing roller 40 is charged up by the conveyance of the recording material P.
[0006]
Further, the hollow core metal 42 of the fixing roller 40 is electrically grounded or grounded via a diode element, or biased by bias applying means (not shown), and the surface of the fixing roller is charged up so that an offset image is obtained. Is prevented from occurring.
[0007]
A thermistor 44 is in contact with the surface of the fixing roller 40. The fixing roller 40 detects the temperature of the surface of the fixing roller and performs on / off control of power supply to the halogen lamp 41 so as to heat the toner image on the recording material P at an appropriate temperature.
[0008]
On the other hand, reference numeral 50 denotes a pressure roller for nipping and conveying the recording material P while being pressed against the fixing roller 40 at both ends in the longitudinal direction of the roller by a pressure spring (not shown). The pressure roller 50 is formed of an elastic layer formed of silicon rubber or a sponge elastic layer 52 formed by foaming silicon rubber, and a PTFE, PFA, FEP or the like similar to the fixing roller 40 on the outer layer. The releasable layer 53 is formed in a tube shape or by coating. Therefore, the fixing nip portion N having a sufficient nip width can be formed between the rollers 40 and 50 due to the elasticity of the pressure roller 50. The toner image on the recording material P is fixed by the recording material P being nipped and conveyed by the fixing nip portion N and heated from the fixing roller 40.
[0009]
In particular, a method of suppressing power consumption as much as possible without supplying power to the heat fixing device during standby, specifically fixing a toner image on a recording material through a thin film between a heater portion and a pressure roller. One example of a heat fixing method using a film heating method has been proposed (see, for example, Patent Documents 1 to 4).
[0010]
FIG. 11 shows a schematic configuration of an example of a film heating type fixing device. This fixing device includes a stay holder (support body) 62, a heating member (heating body, hereinafter referred to as a heater) 61 fixedly supported by the stay holder 62, and a heat-resistant thin film (hereinafter referred to as an outer peripheral surface). A fixing roller 60 having 63). The fixing device has an elastic pressure roller 50. By fixing the fixing film 63 between the elastic pressure roller 50 and the heater 61, a fixing nip portion N having a predetermined nip width is formed.
[0011]
The heater 61 is heated and adjusted to a predetermined temperature by energization. The fixing film 63 is transported and moved in the direction of the arrow while being in close contact with and sliding on the surface of the heater 61 in the fixing nip portion N by a driving means (not shown) or the rotational force of the pressure roller 50. Or it is a roll-shaped end-web-shaped member.
[0012]
In a state where the heater 61 is heated and adjusted to a predetermined temperature and the fixing film 63 is transported and moved in the direction of the arrow, the heater 61 is used as a material to be heated between the fixing film 63 and the pressure roller 50 in the fixing nip N. When the recording material P on which an unfixed toner image is formed and supported is introduced, the recording material P is brought into close contact with the outer peripheral surface of the fixing film 63 and is nipped and conveyed together with the fixing film 63 through the fixing nip portion N. In the fixing nip portion N, the recording material / toner image is heated by the heater 61 through the fixing film 63, and the toner image on the recording material P is heated and fixed. The recording material portion that has passed through the fixing nip N is peeled off from the surface of the fixing film 63 and conveyed.
[0013]
A ceramic heater is generally used as the heater 61 as the heating member. For example, silver palladium (Ag / Ag) is formed along the substrate length (direction perpendicular to the drawing) on the surface (surface facing the fixing film 63) of an electrically insulating / good heat conductive / low heat capacity ceramic substrate such as alumina. Pd) ・ Ta₂An energizing heat generating resistance layer such as N is formed by screen printing or the like, and the surface on which the heat generating resistance layer is formed is covered with a thin glass protective layer.
[0014]
When the ceramic heater 61 is energized to the energized heat generating resistor layer, the energized heat generating resistor layer generates heat, and the entire heater including the ceramic substrate / glass protective layer is rapidly heated. The temperature rise of the heater 61 is detected by a temperature detecting means 64 installed on the back surface of the heater and fed back to an energization control unit (not shown). The energization control unit controls power feeding to the energization heating resistor layer so that the heater temperature detected by the temperature detection unit 64 is maintained at a predetermined substantially constant temperature (fixing temperature). That is, the heater 61 is heated and adjusted to a predetermined fixing temperature.
[0015]
The fixing film 63 has a thickness as thin as 20 to 70 μm in order to efficiently apply the heat of the heater 61 to the recording material P as the material to be heated at the fixing nip portion N. The fixing film 63 has a three-layer structure of a film base layer, a conductive primer layer, and a releasable layer. The film base layer side is a heater side, and the releasable layer is a pressure roller side. The film base layer is made of polyimide, polyamideimide, PEEK or the like having high insulating properties, has heat resistance and high elasticity, and has a flexible thickness of about 15 to 60 μm. Further, the mechanical strength such as the tear strength of the entire fixing film 63 is maintained by the film base layer. The conductive primer layer is formed as a thin layer having a thickness of about 2 to 6 μm, and is electrically connected to the ground in order to prevent the entire fixing film from being charged up. The releasable layer is a toner offset prevention layer for the fixing film 63, and is formed by coating a fluororesin such as PFA, PTFE, FEP or the like having good releasability to a thickness of about 5 to 14 μm. Further, like the fixing roller 40 in FIG. 10, in order to reduce the charge-up on the surface of the fixing film 63 and prevent electrostatic offset, a specific resistance is 10 in the release layer.^ThreeΩcm to 10⁶Conductive members such as carbon black of about Ωcm are mixed.
[0016]
The stay holder 62 is formed of a heat-resistant plastic member, for example, and holds the heater 61 and also serves as a conveyance guide for the fixing film 63. Therefore, in order to improve the slidability with the fixing film 63, grease having high heat resistance or the like is interposed between the fixing film 63 and the outer peripheral surface of the heater 61 or the stay holder 62. The pressure member 50 has the same configuration as the pressure roller of the above-described fixing roller type heat fixing device.
[0017]
Further, the stay holder 62 forms a fixing nip portion N necessary for heat fixing between the fixing film 63 and the pressure roller 50, so that the pressure roller 50 is pressed from both ends of the stay holder 62 by a pressure spring (not shown). Pressurized to the side. As a result, the heater 61 attached to the stay holder 62 is in close contact with the fixing film 63 over a part of the pressure roller 50 in the circumferential direction and over the entire longitudinal direction.
[0018]
When the pressure roller 50 is driven to rotate, the fixing film 63 is driven and rotated by the surface of the pressure roller 50 accordingly. In this state, power is supplied to the energization heat generating resistance layer formed on the heater 61 through an electrode portion formed on both ends of the heater 61 by a connector (not shown). As a result, the energization heating resistor layer is heated and heated, and the toner image on the recording material held and conveyed by the fixing nip is heated and fixed.
[0019]
However, when the heat fixing apparatus as described above is used, there are the following problems.
[0020]
First, in the case of a heat fixing device using the fixing roller 40, the thickness of the fixing roller core 42 satisfies the mechanical strength, and therefore requires about 1 to 4 mm, and has a large heat capacity. For this reason, it is necessary to preheat the fixing roller 40 to a predetermined temperature before the image forming apparatus receives a print signal. That is, it is difficult to heat up the fixing roller 40 from room temperature to a fixable temperature in a short time until the recording material P on which the unfixed toner image is formed is conveyed to the heat fixing device. It is necessary to raise the temperature to some extent in the standby state before receiving the signal.
[0021]
For this reason, when the power of the image forming apparatus is turned on after the fixing roller 40 has been cooled to the room temperature, the temperature of the fixing roller 40 needs to be raised until the image forming apparatus can receive a print signal. there were. Further, since it is necessary to heat the fixing roller 40 to a predetermined temperature by energizing the heater 41 during standby, energy is wasted.
[0022]
Even if it is intended to cope with the above problem by reducing the thickness of the cored bar 42, the heat efficiency is not good when the fixing roller is heated by the radiant heat of the heater 41 as in the above-described conventional example. Similarly, when the recording material conveyance speed is increased by increasing the speed of the forming apparatus, preheating is required.
[0023]
In addition, when attempting to increase the heating speed by reducing the thickness of the cored bar 42, the cored bar 42 is not strong enough so that it is greatly bent and cracked when pressed with a strong pressure. There was a problem with sex. When pressurization is performed with a weak pressure in consideration of durability, toner fixability is insufficient.
[0024]
On the other hand, the film heating type heating and fixing apparatus does not require energization of the heater 61 during standby as described above, and recording is performed even when the image forming apparatus receives a print signal and then energizes the heater 61. The material P can be heated before reaching the heat fixing device. Therefore, from the viewpoint of energy saving, a film heating type heat fixing device is an excellent heat fixing device that does not waste energy.
[0025]
However, the fixing film 63 is formed of a resin layer having poor thermal conductivity, and is not suitable for increasing the speed of the image forming apparatus. That is, when the speed of the image forming apparatus is increased, the speed at which the heat from the heater 61 is applied to the recording material P through the fixing film 63 must be increased corresponding to the increase in the speed of the apparatus. In 63, there is a limit even if measures such as mixing a thermally conductive filler are taken, and it becomes impossible to cope with further speeding up.
[0026]
Further, when the pressure roller 50 is pressed against the fixing film 63 with a high pressure, the toner image can be pressed against the recording material P with a strong adhesion force, and the fixing performance is improved. However, the resin film is durable. In some cases, the inner surface could be scraped and damaged, and it was difficult to achieve both high speed and durability.
[0027]
Further, when a large amount of thermally conductive filler is added to the resin fixing film 63, mechanical strength such as tear strength is lost. For example, when the position in the thrust direction is regulated by a regulating member or the like at the end. Since the end portion of the fixing film 63 is rotated in a state where it is close to the end face of the regulating member or the like, problems such as tearing of the end portion of the fixing film 63 occur, and the durability is deteriorated. Further, when trying to control the shift to the end, the structure becomes complicated, leading to an increase in size and cost of the apparatus.
[0028]
Therefore, a system using a resin film is unsuitable for increasing the speed of a heat fixing device that has a simple configuration and satisfies both securing of fixing property and securing of durability.
[0029]
Further, when a film heating type fixing device is used, the following problems also exist. CaCO_ThreeThe recording material containing is very commonly used, but when such a recording material is used, CaCO that falls off from the recording material is used._ThreeAs a result of adhering to the rotating member, dirt on the rotating member is likely to occur, and image defects may occur due to this dirt.
[0030]
In addition, when a solid image is printed, the recording material slips in the nip portion between the rotary heating member and the rotary pressure member, so that the image density at the edge of the image becomes lighter than that at the central portion. There is also a problem that a low concentration occurs.
[0031]
On the other hand, a toner that can be fixed at a lower temperature is desired in order to save energy and increase the speed. However, too much pursuing low-temperature fixability causes a problem that the offset property at high temperatures deteriorates.
[0032]
In view of this, various toners have been proposed in order to achieve both low-temperature fixability and high-temperature offset resistance. As a technique for improving the binder resin of toner, for example, in the molecular weight distribution by GPC, the molecular weight is 1 × 10^Three~ 8x10^FourAnd molecular weight 1 × 10^Five~ 2x10⁶A toner containing a binder resin component having at least one maximum value in each of the regions has been proposed (see, for example, Patent Document 5). However, further improvements in low-temperature fixability and offset resistance are required.
[0033]
Further, it contains 10 to 60% by mass of the THF-insoluble content based on the binder resin, and in the molecular weight distribution by GPC of the THF-soluble content, the weight average molecular weight / number average molecular weight (Mw / Mn) is 5 or more, and the molecular weight 2 × 10^Three~ 1x10^FourAnd has a molecular weight of 1.5 × 10^Four~ 1x10^FiveWith a peak or shoulder in the region of 1 and a molecular weight of 1 × 10^FourA toner containing 10 to 50% by mass of the following components in a binder resin has been proposed (see, for example, Patent Document 6).
[0034]
In this case, the grindability, fixability, filming and fusion to the photoconductor, image quality, and offset resistance (especially offset resistance on the high temperature side) are excellent, but further low temperature fixability and offset resistance. Improvement is required.
[0035]
In addition, by controlling the molecular weight, mixing ratio, acid value and ratio of the low and high molecular weight components in the binder resin, the fixability, offset resistance, image characteristics and blocking resistance, and charge rise characteristics are improved. Although a toner binder composition and a toner have been proposed, further improvements in low-temperature fixability and offset resistance are required (see, for example, Patent Documents 7 to 10).
[0036]
On the other hand, as a technique for imparting offset resistance to a toner, means for containing a low softening point release agent (wax) made of polyolefin or the like is known. For example, as a release agent, addition to toner such as solid silicone varnish, higher fatty acid wax, higher alcohol wax, plant natural wax (carnauba wax, rice wax), montan ester wax, etc. is known. Only using conventional waxes does not sufficiently achieve both low-temperature fixability and offset resistance (see, for example, Patent Documents 11 to 16).
[0037]
Generally, when such a low softening point release agent is contained in the toner, the fluidity is lowered, so that the developability and transferability are lowered, and the charging characteristics, durability and storage stability may be adversely affected.
[0038]
[Patent Document 1]
JP-A-63-313182
[Patent Document 2]
Japanese Patent Laid-Open No. 2-157878
[Patent Document 3]
JP-A-4-44075
[Patent Document 4]
JP-A-4-204980
[Patent Document 5]
JP-A-56-16144
[Patent Document 6]
Japanese Unexamined Patent Publication No. 63-223661
[Patent Document 7]
JP-A-2-168264
[Patent Document 8]
Japanese Patent Laid-Open No. 2-235069
[Patent Document 9]
JP-A-5-173363
[Patent Document 10]
JP-A-5-241371
[Patent Document 11]
Japanese Patent Laid-Open No. 51-14333
[Patent Document 12]
JP 57-14875 A
[Patent Document 13]
JP 58-97056 A
[Patent Document 14]
JP 60-247250 A
[Patent Document 15]
JP-A-4-362953
[Patent Document 16]
JP-A-6-230600
[0039]
[Problems to be solved by the invention]
The present invention has been made in view of the above problems, and a heating member is disposed in contact with the inner surface of the metal sleeve in a portion corresponding to the heating nip formed between the metal sleeve and the pressure member. In the film heating type heat fixing device characterized by the above, it exhibits good low temperature fixability, high temperature offset resistance, low temperature offset resistance, and does not cause stains on rotating pressure members or thin end density, and excellent developability An object is to provide a toner, an image forming method using the toner, and an image forming apparatus.
[0040]
That is, an object of the present invention is to provide a toner corresponding to high-speed on-demand fixing that achieves fixing performance and quick start performance, and an image forming method using the toner.
[0041]
[Means for Solving the Problems]
As a result of intensive studies, the present inventors have paid attention to the physical properties of the binder resin and wax constituting the toner and the porosity of the toner, and by using these values as specific values, the film heating type heat fixing device is used. The present invention has found that excellent fixing properties can be realized and excellent image formation can be achieved.
[0042]
That is, the present invention is as follows.
[0043]
(1)An image forming method for forming an image on a recording material by forming an unfixed toner image made of toner on the recording material and fixing the toner image on the recording material,
A fixing step of fixing the unfixed toner image on the recording material by fixing means;
The fixing means isA metal sleeve for heating based on a flexible cylindrical metal tube;TheA heating member that is disposed in contact with the inner surface of the heating metal sleeve and heats the heating metal sleeve, and is pressed against the heating member via the heating metal sleeve and is parallel to the heating metal sleeve. A rotatable pressure member having a rotating shaftHaving at least
The surface roughness Rz in the longitudinal direction of the metal sleeve for heating is 3 μm or less, the surface roughness Rz ′ in the circumferential direction is 3 μm or less, and the relationship between Rz and Rz ′ is Rz> Rz ′,
The metal sleeve for heating and the pressure member are pressed against each other.A fixing nip is formed,
The heating metal sleeve rotates in conjunction with the rotation of the pressure member, and passes the recording material on which the unfixed toner image is formed through the fixing nip portion,Fix the unfixed toner image on the recording materialLet
Constructing the unfixed toner imageThe toner contains at least a binder resin and a wax,
In the chromatogram obtained by gel permeation chromatography of the tetrahydrofuran-soluble content of the toner, the molecular weight is 3.0 × 10³~ 3.0 × 10⁴With a main peak and a molecular weight of 1.0 × 10⁵~ 3.0 × 10⁶Have sub-peaks or shoulders in the area of
The peak top temperature of the maximum endothermic peak in the endothermic peak at the time of temperature rise measured by differential thermal analysis of the wax is 70 to 120 ° C,
The porosity determined from the tap density of the toner is 0.4 to 0.7.Image forming method.
[0044]
(2) The melt viscosity at 120 ° C. measured with an E-type viscometer of the wax is 100 mPa · s or less, as described in (1)Image forming method.
[0045]
(3) The melt viscosity at 120 ° C. measured with an E-type viscometer of the wax is 1 to 50 mPa · s.Image forming method.
[0046]
(4) The viscosity at 120 ° C. is 1 × 10³~ 5x10⁵As described in any one of (1) to (3), which is Pa · sImage forming method.
[0047]
(5) The peak top temperature of the maximum endothermic peak in the endothermic peak at the time of temperature rise measured by differential thermal analysis of the wax is 70 to 100 ° C. Any one of (1) to (4) Described inImage forming method.
[0048]
(6)The peak top temperature of the maximum endothermic peak in the endothermic peak at the time of temperature rise measured by differential thermal analysis of the wax is 70 to 80 ° C., according to any one of (1) to (4), Image forming method.
[0049]
(7)The image according to any one of (1) to (6), wherein the peak half-value width of the endothermic peak at the time of temperature rise measured by differential thermal analysis of the wax is 12 ° C. or less. Forming method.
[0050]
(8)The peak half value width of the maximum endothermic peak in the endothermic peak at the time of temperature rise measured by differential thermal analysis of the wax is 8 ° C. or less, The image according to any one of (1) to (6) Forming method.
[0051]
(9)(1) to (8), wherein the starting point onset temperature at the endothermic peak at the time of temperature rise measured by differential thermal analysis of the wax is 50 ° C. or higher and the end point onset temperature is 100 ° C. or lower. The image forming method according to any one of the above.
[0052]
(10)(1) to (8), wherein the starting point onset temperature at the endothermic peak at the time of temperature rise measured by differential thermal analysis of the wax is 60 ° C. or higher and the end point onset temperature is 90 ° C. or lower. The image forming method according to any one of the above.
[0053]
(11)The image forming method according to any one of (1) to (10), wherein the porosity determined from the tap density is 0.45 to 0.65.
[0054]
(12)The image forming method according to any one of (1) to (11), wherein an acid value of the binder resin is 0.1 to 100 mgKOH / g.
[0060]
DETAILED DESCRIPTION OF THE INVENTION
The toner of the present invention includes a heating metal sleeve having a flexible cylindrical metal base as a base layer, and a heating member that is disposed in contact with the inner surface of the heating metal sleeve and heats the heating metal sleeve And a fixing means having at least a rotatable pressure member that is in pressure contact with the heating member via the heating metal sleeve and has a rotation axis parallel to the heating metal sleeve. The recording material on which the unfixed toner image is formed is passed through a fixing nip portion formed by press-contacting the metal sleeve for pressure and the pressure member, whereby the unfixed toner image is placed on the recording material. A toner used in an image forming method having a fixing step for fixing to a toner, comprising at least a binder resin and a wax; In the chromatogram obtained by Activation chromatography, molecular weight 3.0 × 10^Three~ 3.0 × 10^FourWith a main peak and a molecular weight of 1.0 × 10^Five~ 3.0 × 10⁶(B) the peak top temperature of the maximum endothermic peak in the endothermic peak at the time of temperature rise measured by differential thermal analysis of the wax is 70 to 120 ° C., and (C) the toner The porosity determined from the tap density is 0.4 to 0.7.
[0061]
The image forming method of the present invention uses the toner of the present invention, and forms an unfixed toner image made of toner on the recording material and fixes the toner image on the recording material. An image forming method comprising: (a) a fixing step of fixing an unfixed toner image on the recording material by fixing means; and (b) a fixing means comprising a flexible cylindrical metal element. A heating metal sleeve having a tube as a base layer, a heating member that is disposed in contact with the inner surface of the heating metal sleeve and heats the heating metal sleeve, and is pressed against the heating member via the heating metal sleeve And a rotatable pressure member having a rotation axis parallel to the heating metal sleeve, and (c) the heating metal sleeve and the pressure member are pressed against each other to form a fixing nip. Formation (D) The heating metal sleeve rotates in conjunction with the rotation of the pressure member, and passes the recording material on which the unfixed toner image is formed between the fixing nips, thereby transferring the unfixed toner image to the recording material. It is to fix on top.
[0062]
By combining the image forming method and the toner described above, the present inventors have excellent developability, low-temperature fixability, high-temperature offset resistance, and low-temperature offset resistance, and the rotating pressure member dirt and edge density are low. It has been found that it exhibits particularly excellent performance in preventing occurrence.
[0063]
It has been found that the pressure member contamination is likely to occur when a relatively small number of prints of about 5 sheets or less are continuously printed at intervals of 10 to 20 minutes or more in a low temperature environment. The mechanism of this phenomenon is considered as follows.
[0064]
In the fixing device using the heating and fixing method, the temperature of the heating metal sleeve, which is a rotating heating member, rises quickly, and printing is performed in a very short preheating time as compared with the hot roll fixing method. In the number of sheets, the time for transferring heat to the pressure member is short, and the surface temperature of the pressure member does not rise so much, so the temperature difference from the heated metal sleeve for heating becomes very large. Therefore, the toner slightly offset from the toner image on the recording material to the heating metal sleeve has a low pressure at the nip portion between the heating metal sleeve and the pressure member after the recording material passes through the fixing device. Transition to the surface. If there is an interval of 10 to 20 minutes or more until the next printing, the surface temperature of the pressure member again decreases to near the initial temperature in a low temperature environment. The same phenomenon is repeated by printing about 5 sheets or less at the interval, and toner is accumulated on the pressure member surface.
[0065]
When the amount of toner accumulated in the pressure member reaches a certain amount, the toner adheres to the pressure member surface as a mass of toner. Then, the accumulated toner lump is peeled off from the surface of the pressure member and transferred to the heating metal sleeve or directly transferred to the recording material, causing image defects such as black spots.
[0066]
When printing about 10 sheets or more at a time, or when the next printing is performed without taking a long time, the pressure member surface is sufficiently heated to raise the temperature. The temperature difference becomes smaller. In such a situation, even if the toner is offset from the toner image on the recording material to the heating metal sleeve in the fixing step, the offset toner does not move to the pressing member, and the recording material is not transferred from the heating metal sleeve. It is considered that the image is not defective because the toner is discharged little by little.
[0067]
Unlike the so-called low-temperature offset and high-temperature offset, most of the toner that is offset slightly to the metal sleeve for heating here is electrostatically offset toner, and fixing performance such as low-temperature fixability and high-temperature offset property of the toner It has been experimentally found that there is basically nothing to do. Therefore, in order to improve the pressure member contamination with toner, it is necessary to design the toner from a viewpoint different from the fixing performance.
[0068]
Furthermore, the metal fixing film used in the present invention is stronger than the fixing film made of resin such as polyimide, polyamideimide, PEEK and the like that has been conventionally used, so the film is not easily bent, The film hardly adheres to the heater at the portion where the inner surface of the fixing nip and the heater are in contact with each other. Therefore, the part where the recording material enters and exits the nip has a large gap between the heater and the film, and the central part of the nip has a small gap between the heater and the fixing nip is uneven with respect to the recording material traveling direction. Since this is not a smooth surface, the pressure member contamination is more likely to deteriorate. In order to suppress pressure member contamination while achieving excellent fixing properties and high-temperature offset resistance, it is important to combine toners suitable for the configuration of the fixing device.
[0069]
Accordingly, the present inventors have studied how to discharge toner onto the recording material without accumulating the toner offset to the heating metal sleeve on the pressure member, and as described above, as described above, (A) Toner In a chromatogram obtained by gel permeation chromatography (GPC) of a tetrahydrofuran (THF) soluble content of^Three~ 3.0 × 10^FourWith a main peak and a molecular weight of 1.0 × 10^Five~ 3.0 × 10⁶(B) a toner having a peak top temperature of 70 to 120 ° C. of the maximum endothermic peak in the endothermic peak at the time of temperature rise measured by differential thermal analysis (DSC) of the wax. It was found that the pressure member contamination can be greatly improved. This mechanism can be inferred as follows.
[0070]
When printing on about 5 sheets or less in a low temperature environment with an interval of 10 to 20 minutes or more, the surface temperature of the pressure member rises only up to about 120 ° C., but it is used for the toner of the present invention. The wax whose peak end temperature of the endothermic peak at the endothermic peak at the time of temperature rise measured by DSC is 70 to 120 ° C. is sufficiently melted even at this temperature.
[0071]
The molecular weight distribution of the THF soluble component of the toner of the present invention substantially represents the molecular weight distribution of the binder resin contained in the toner. That is, since the binder resin having the above molecular weight distribution maintains sufficient elasticity even at this temperature, the wax component is easily dissolved on the toner surface without excessively plasticizing the binder resin. As a result, sufficient releasability can be exerted even on a pressure member having a low temperature, so that the toner adhering to the heating metal sleeve is prevented from moving to the surface of the pressure member and the contamination of the pressure member is suppressed. It seems to do.
[0072]
On the other hand, when printing a solid image, the image density at the edge of the image is lighter than the center, and the problem of low edge density is that the unfixed image before entering the fixing device is a uniform solid image. However, when the unfixed image is passed through the fixing device and the toner image on the recording material is fixed, only the image density at the edge of the recording material becomes thin. It was found that this phenomenon tends to occur when the applied pressure is reduced. When the fixing speed is fast and the applied pressure is small, the recording material easily slips at the nip portion between the heating metal sleeve and the pressure member, and the fixing speed slightly deviates between the central portion and the end portion of the recording material. For this reason, it was found that the toner image at the edge of the recording material was slightly rubbed at the fixing nip, the image was disturbed and uneven, and the density at the edge was reduced.
[0073]
Thus, as a result of investigations by the present inventors, it has been found that controlling the porosity determined from the (C) toner tap density to 0.4 to 0.7 is effective in improving the edge density thinness. It was.
[0074]
When the toner porosity is 0.4 to 0.7, the toner constituting the toner image on the recording material exists in a densely packed state, so that the fixing is performed at the end portion and the central portion of the recording material at the fixing nip portion. Even if there is a slight speed shift, image distortion is less likely to occur. Further, at this time, as described above, in the toner of the present invention, the wax component easily dissolves on the toner surface even at a relatively low temperature. Therefore, the wax dissolved on the toner surface plays a role of holding individual toner particles on the recording material. Therefore, it is considered that the image becomes stronger against image disturbance due to fixing speed shift, and the edge density thinness is prevented.
[0075]
In addition, for the same reason, since the force to hold the individual toner particles to the recording material works, the adhesive force between the developed toner and the recording material can be increased, and printing can be performed from a state where the fixing device is cooled. Even if the operation is performed, it is possible to make it difficult to generate a low temperature offset.
[0076]
In other words, in the present invention, by making the molecular weight distribution obtained by GPC of the toner soluble in THF, the peak top temperature of the DSC curve when the wax is heated, and the porosity within the above ranges, energy saving and quick start performance can be achieved. It is possible to achieve excellent fixability in an image forming method using an excellent film heating type fixing method, and the toner on the rotating member adheres when printing a small number of sheets with a time interval. It is possible to prevent image defects and edge density thinning caused by an increase in fixing speed.
[0077]
As described above, the toner of the present invention has a molecular weight of 3.0 × 10 in the chromatogram obtained by GPC of THF-soluble matter.^Three~ 3.0 × 10^Four(Preferably molecular weight 5.0 × 10^Three~ 2.0 × 10^Four, More preferably molecular weight 1.0 × 10^Four~ 2.0 × 10^Four) Having a main peak and a molecular weight of 1.0 × 10^Five~ 3.0 × 10⁶(Preferably 5.0 × 10^Five~ 1.0 × 10⁶, More preferably molecular weight 6.0 × 10^Five~ 9.0 × 10^Five) Have sub-peaks or shoulders.
[0078]
The main peak has a molecular weight of 3.0 × 10^ThreeWhen it is in a smaller region, the high temperature offset property, developability and storage stability are likely to deteriorate, and the main peak has a molecular weight of 3.0 × 10.^FourIf it is in a larger area, the low-temperature fixability tends to deteriorate. Subpeak or shoulder has a molecular weight of 1.0 × 10^FiveIf it is in a smaller area, the high temperature offset property deteriorates and the binder resin is easily plasticized by the wax and the wax is difficult to dissolve on the toner surface. May get worse. Subpeak or shoulder has a molecular weight of 3.0 × 10⁶If it is in a larger area, the low-temperature fixability tends to deteriorate.
[0079]
Generally, the THF soluble content of the toner substantially corresponds to the THF soluble content of the binder resin contained in the toner. Therefore, the toner of the present invention having the above-mentioned peak can be obtained by controlling the molecular weight distribution of the THF-soluble component of the binder resin within the above range.
In the present invention, the molecular weight distribution of the toner is measured under the following conditions by GPC (gel permeation chromatography).
[0080]
<GPC measurement conditions>
Apparatus: GPC-150C (manufactured by Waters)
Column: 7 columns of KF801-7 (manufactured by Shodex)
Temperature: 40 ° C
Solvent: THF (tetrahydrofuran)
Flow rate: 1.0 ml / min
Sample: 0.1 ml of a sample having a concentration of 0.05 to 0.6% by mass is injected.
[0081]
The binder resin used in the toner of the present invention preferably has a THF-insoluble content of 0 to 10% by mass based on the resin composition. The binder insoluble content of the binder resin is more preferably 0 to 5% by mass, and still more preferably 0 to 3% by mass.
[0082]
The THF-insoluble content of the binder resin in the present invention refers to the mass ratio of the polymer component (substantially crosslinked polymer) that has become insoluble in the THF solvent in the toner, and the crosslinking of the resin composition containing the crosslinking component. It can be used as a parameter indicating the degree of. The THF-insoluble content is defined as a value measured as follows.
[0083]
A toner sample of 0.5 to 1.0 g is weighed (w1 g), put into a cylindrical filter paper (for example, No. 86R manufactured by Toyo Roshi), passed through a Soxhlet extractor, extracted with 200 ml of THF as a solvent, and extracted for 10 hours. After evaporating the soluble component, vacuum drying is performed at 100 ° C. for several hours, and the amount of the THF-soluble resin component is weighed (w2 g). The mass of components other than the resin component such as a magnetic substance and a pigment in the toner is (w3 g). The THF-insoluble matter can be obtained from the following formula (1).
[0084]
[Expression 1]

[0085]
The binder resin used in the present invention preferably has an acid value of 0.1 to 100 (more preferably 1 to 50) mgKOH / g. By setting the acid value of the binder resin within the above range, the difference in polarity between the binder resin and the wax increases, facilitating the dissolution of the wax component on the toner surface, dirt on the pressure member, low edge concentration, cold offset. It is effective for prevention. Further, since the polarity of the binder resin is increased, the releasability between the pressure member and the binder resin is improved, and the pressure member contamination is less likely to occur.
[0086]
When the acid value of the binder resin is less than 0.1 mgKOH / g, the wax component is difficult to dissolve on the toner surface, and it is difficult to prevent the effect of preventing pressure member contamination, edge concentration thinness, and cold offset. On the other hand, if the acid value is larger than 100 mgKOH / g, the chargeability of the toner becomes unstable, and the developability in a high humidity environment and the fogging in a low humidity environment are likely to deteriorate.
[0087]
In the present invention, the acid value (JIS acid value) of the binder resin is determined by the following method.
[0088]
<Measurement of acid value (JIS acid value)>
1) Weigh precisely 0.1 to 2.0 g of the pulverized product of the sample, and let its weight be W (g).
[0089]
2) Put a sample in a 20 cc Erlenmeyer flask and dissolve by adding 10 cc of a mixed solution of toluene / ethanol (2: 1).
[0090]
3) Add a few drops of phenolphthalein alcohol solution as an indicator.
[0091]
4) Titrate the solution in the flask with a 0.1 mol / l alcohol solution of KOH using a burette. The amount of KOH solution used at this time is S (ml). At the same time, a blank test is performed, and the amount of the KOH solution at this time is B (ml).
[0092]
5) The acid value is calculated by the following formula (2) (in the following formula (2), f represents a factor of the KOH solution).
[0093]
[Expression 2]
Acid value = (SB) × f × 5.61 / W (2)
[0094]
As a monomer for adjusting the acid value of the binder resin, for example, acrylic acid such as acrylic acid, methacrylic acid, α-ethylacrylic acid, crotonic acid, and α- or β-alkyl derivatives thereof, fumaric acid, maleic acid, There are unsaturated dicarboxylic acids such as citraconic acid and monoester derivatives thereof, or maleic anhydride, etc., and these monomers are used alone or in combination to copolymerize with other monomers to produce the desired polymer. Can do. Among these, it is particularly preferable to use a monoester derivative of an unsaturated dicarboxylic acid in order to control the acid value.
[0095]
More specifically, for example, monomethyl maleate, monoethyl maleate, monobutyl maleate, monooctyl maleate, monoallyl maleate, monophenyl maleate, monomethyl fumarate, monoethyl fumarate, monobutyl fumarate, monophenyl fumarate Monoesters of α, β-unsaturated dicarboxylic acids such as: monobutyl n-butenyl succinate, monomethyl n-octenyl succinate, monoethyl n-butenyl malonate, monomethyl n-dodecenyl glutarate, monobutyl n-butenyl adipate Monoesters of alkenyl dicarboxylic acids such as, and the like; monoesters of aromatic dicarboxylic acids such as phthalic acid monomethyl ester, phthalic acid monoethyl ester, phthalic acid monobutyl ester, and the like.
[0096]
What is necessary is just to add 0.1-30 wt% of the above carboxyl group containing monomers with respect to all the monomers which comprise binder resin.
[0097]
The reason why the monoester monomer of dicarboxylic acid as described above is selected is that it is not appropriate to use in the form of an acid monomer having high solubility in an aqueous suspension when producing a toner by suspension polymerization. This is because it is preferably used in the form of an ester having low solubility.
[0098]
The toner of the present invention has a viscosity at 120 ° C. of 1 × 10^Three~ 5x10^FivePa · s is preferred. By setting the viscosity of the toner at 120 ° C. within the above range, the wax component is easily dissolved on the toner surface, and the effect is exhibited by preventing low temperature offset, pressure member contamination, and low end density.
[0099]
The toner has a viscosity of 1 × 10 at 120 ° C.^ThreeWhen it is smaller than Pa · s, the binder resin is easily plasticized by the wax component, and the pressure member contamination and the edge density thinness are likely to deteriorate. On the other hand, the viscosity is 5 × 10^FiveIf it is greater than Pa · s, the low-temperature fixability of the toner is likely to deteriorate, and even if the toner is heated during fixing, the elasticity of the toner is too great, and the force to hold the individual toner particles is difficult to work. Offset and thin end density tend to deteriorate.
[0100]
The viscosity of the toner at 120 ° C. is determined by the following method.
[0101]
<Measurement of toner viscosity>
The viscosity of the toner is measured using an elevated flow tester (Shimadzu Flow Tester CFT-500 type), and a sample of about 1.5 g molded using a pressure molding machine is loaded with a plunger at a constant temperature of 98.0 N. And push out from a nozzle with a diameter of 1 mm and a length of 1 mm. Thereby, the plunger lowering amount (outflow speed) of the flow tester is measured. The outflow rate is measured at each temperature (temperature range of 100 ° C. to 180 ° C. at 5 ° C. intervals), and the apparent viscosity η ′ as the viscosity in the present invention is obtained from this value by the following formula (3).
[0102]
[Equation 3]
η ′ (Pa · s) = TW ′ / DW ′ = πPR4 / 8LQ (3)
However, in the above formula
TW ′ = PR / 2L (N / m²)
DW '= 4Q / πR^Three(Sec^-1)
η ′: Apparent viscosity (Pa · s)
TW ′: Apparent shear stress of the tube wall (N / m²)
DW ': Apparent shear rate of the pipe wall (sec^-1)
Q: Outflow velocity (m^Three/ Sec)
P: extrusion pressure (N / m²)
R: Nozzle radius (m)
L: Nozzle length (m)
[0103]
The binder resin of the present invention preferably has a glass transition temperature (Tg) of 50 to 70 ° C, and more preferably 55 to 65 ° C, from the viewpoint of storage stability. When Tg is lower than 50 ° C., the toner is likely to deteriorate in a high temperature atmosphere, and high temperature offset is likely to occur during fixing. On the other hand, when Tg exceeds 70 ° C., the low-temperature fixability tends to decrease.
[0104]
As a method for producing the binder resin used in the present invention, a high-molecular weight polymer and a low-molecular weight polymer are separately synthesized by a solution polymerization method, and then mixed in a solution state and then desolvated, Or the dry blend method etc. which melt-knead with an extruder etc. are mentioned. However, the dry blend method is problematic in terms of uniform dispersion and compatibility, and therefore the solution blend method is most suitable. In addition, as a method for introducing a predetermined acid value into the low molecular weight polymer, solution polymerization in which the acid value can be easily set as compared with the aqueous polymerization method is preferable.
[0105]
Examples of polymerization methods that can be used in the present invention as a method for synthesizing a high molecular weight polymer include solution polymerization, emulsion polymerization, and suspension polymerization.
[0106]
The emulsion polymerization method is a method in which a monomer (monomer) almost insoluble in water is dispersed as small particles in an aqueous phase using an emulsifier, and polymerization is performed using a water-soluble polymerization initiator. In this method, the heat of reaction can be easily adjusted, and since the phase in which the polymerization is carried out (the oil phase consisting of the polymer and the monomer) and the aqueous phase are different, the termination reaction rate is low, resulting in a high polymerization concentration. A product having a high degree of polymerization is obtained. Further, since the polymerization process is relatively simple and the polymerization product is fine particles, it is easy to mix with a colorant, a charge control agent and other additives during toner production. There is an advantage as a manufacturing method of a resin.
[0107]
However, in the above emulsion polymerization method, the polymer tends to be impure due to the added emulsifier, and an operation such as salting out is necessary to take out the polymer. Suspension polymerization is advantageous to avoid this inconvenience.
[0108]
The suspension polymerization is preferably performed using 100 parts by mass or less (preferably 10 to 90 parts by mass) of the monomer with respect to 100 parts by mass of the aqueous solvent. Examples of the dispersant that can be used include polyvinyl alcohol, partially saponified polyvinyl alcohol, and calcium phosphate. Generally, 0.05 to 1 part by mass is used with respect to 100 parts by mass of the aqueous solvent. The polymerization temperature is suitably 50 to 95 ° C., but is appropriately selected depending on the initiator used and the target polymer.
[0109]
In order to achieve the object of the present invention, the high molecular weight polymer used for the preparation of the binder resin is a polyfunctional polymerization initiator as exemplified below, or a monofunctional polymerization initiator and It is preferable to produce in combination.
[0110]
Specific examples of the polyfunctional polymerization initiator having a polyfunctional structure include 1,1-di-t-butylperoxy-3,3,5-trimethylcyclohexane, 1,3-bis- (t-butylperoxy Isopropyl) benzene, 2,5-dimethyl-2,5- (t-butylperoxy) hexane, 2,5-dimethyl-2,5-di- (t-butylperoxy) hexyne-3, tris- (t -Butylperoxy) triazine, 1,1-di-t-butylperoxycyclohexane, 2,2-di-t-butylperoxybutane, 4,4-di-t-butylperoxyvaleric acid-n- Butyl ester, di-t-butylperoxyhexahydroterephthalate, di-t-butylperoxyazelate, di-t-butylperoxytrimethyladipate, 2,2-bis (4,4-di-t-butylperoxycyclohexyl) has a polymerization initiation function such as two or more peroxide groups in one molecule such as propane, 2,2-t-butylperoxyoctane and various polymer oxides. In one molecule such as a polyfunctional polymerization initiator having a functional group, diallyl peroxydicarbonate, t-butylperoxymaleic acid, t-butylperoxyallylcarbonate and t-butylperoxyisopropyl fumarate, Examples thereof include a polyfunctional polymerization initiator having both a functional group having a polymerization initiation function such as an oxide group and a polymerizable unsaturated group.
[0111]
Of these, more preferred are 1,1-di-t-butylperoxy-3,3,5-trimethylcyclohexane, 1,1-di-t-butylperoxycyclohexane, di-t-butylperoxy. Hexahydroterephthalate, di-t-butylperoxyazelate, 2,2-bis- (4,4-di-t-butylperoxycyclohexyl) propane, and t-butylperoxyallyl carbonate.
[0112]
These polyfunctional polymerization initiators are preferably used in combination with a monofunctional polymerization initiator in order to obtain a binder resin that satisfies various performances required as a binder for toner. In particular, it is preferable to use in combination with a polymerization initiator having a half-life of 10 hours lower than the decomposition temperature for obtaining a half-life of 10 hours of the polyfunctional polymerization initiator.
[0113]
Specifically, benzoyl peroxide, 1,1-di (t-butylperoxy) -3,3,5-trimethylcyclohexane, n-butyl-4,4-di (t-butylperoxy) valerate, dichroic Organic peroxides such as milperoxide, α, α'-bis (t-butylperoxydiisopropyl) benzene, t-butylperoxycumene, di-t-butylperoxide; azobisisobutyronitrile, diazoaminoazobenzene And azo and diazo compounds.
[0114]
These monofunctional polymerization initiators may be added to the monomer at the same time as the polyfunctional polymerization initiator, but in order to keep the efficiency of the polyfunctional polymerization initiator appropriate, in the polymerization step, It is preferably added after the half-life indicated by the polyfunctional polymerization initiator has elapsed.
[0115]
These initiators are preferably used in an amount of 0.05 to 2 parts by mass with respect to 100 parts by mass of the monomer constituting the binder resin from the viewpoint of efficiency.
[0116]
In order to satisfactorily achieve the object of the present invention, the high molecular weight polymer is preferably crosslinked with a crosslinking monomer as exemplified below.
[0117]
As the crosslinkable monomer, a monomer having two or more polymerizable double bonds is mainly used. Monofunctional monomers among the crosslinkable monomers include aromatic divinyl compounds (for example, divinylbenzene, divinylnaphthalene, etc.); diacrylate compounds linked by alkyl chains (for example, ethylene glycol diacrylate, 1,3-butylene) Glycol diacrylate, 1,4-butanediol diacrylate, 1,5-pentanediol acrylate, 1,6-hexanediol diacrylate, neopentyl glycol diacrylate, and acrylates of the above compounds replaced with methacrylate); Diacrylate compounds linked by an alkyl chain containing an ether linkage (eg, diethylene glycol diacrylate, triethylene glycol diacrylate, tetraethylene glycol diacrylate, polyethylene glycol # 00 diacrylate, polyethylene glycol # 600 diacrylate, dipropylene glycol diacrylate, and acrylates of the above compounds replaced with methacrylate); 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 In which the acrylate is replaced with methacrylate); polyester-type diacrylate compounds (for example, trade name MANDA (Nippon Kayaku)).
[0118]
Polyfunctional crosslinkable monomers include pentaerythritol triacrylate, trimethylol ethane triacrylate, trimethylol propane triacrylate, tetramethylol propane triacrylate, tetramethylol methane tetraacrylate, oligoester acrylate, and acrylates of the above compounds. What replaced it with acrylate; triallyl cyanurate, triallyl trimellitate, etc. are mentioned.
[0119]
These crosslinkable monomers are used in an amount of 1 part by mass or less, preferably 0.001 to 0.05 parts by mass with respect to 100 parts by mass of other monomer components.
[0120]
Among these crosslinkable monomers, aromatic divinyl compounds (particularly divinylbenzene), chains containing aromatic groups and ether bonds are preferred for use in toner binder resins from the standpoint of fixability and offset resistance. Examples thereof include tied diacrylate compounds.
[0121]
A known method can be used as a method for synthesizing the low molecular weight polymer. However, the bulk polymerization method can obtain a low molecular weight polymer by polymerizing at a high temperature to increase the termination reaction rate, but has a problem that the reaction is difficult to control. In that respect, the solution polymerization method can easily obtain a low molecular weight polymer under mild conditions by utilizing the difference in radical chain transfer by a solvent and adjusting the initiator amount and reaction temperature. It is particularly preferable to obtain a low molecular weight polymer in the binder resin. In particular, a solution polymerization method under pressure is also preferable from the viewpoint of minimizing the amount of the polymerization initiator used and minimizing the influence of the initiator residue.
[0122]
Examples of the monomer for obtaining the high molecular weight polymer and the monomer for obtaining the low molecular weight polymer include the following.
[0123]
For example, styrene; o-methylstyrene, m-methylstyrene, p-methylstyrene, p-methoxystyrene, p-phenylstyrene, p-chlorostyrene, 3,4-dichlorostyrene, p-ethylstyrene, 2,4- Dimethyl styrene, pn-butyl styrene, p-tert-butyl styrene, pn-hexyl styrene, pn-octyl styrene, pn-nonyl styrene, pn-decyl styrene, pn-dodecyl Styrene derivatives such as styrene; Ethylene unsaturated monoolefins such as ethylene, propylene, butylene and isobutylene; Unsaturated polyenes such as butadiene and isoprene; Halogenated such as vinyl chloride, vinyl bromide and vinyl fluoride Vinyls: vinyl acetate, vinyl propionate, vinyl benzoate Esters: methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, phenyl methacrylate, Α-methylene aliphatic monocarboxylic acid esters such as dimethylaminoethyl methacrylate and diethylaminoethyl methacrylate; methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, propyl acrylate, n-acrylate Acrylic esters such as octyl, dodecyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, 2-chloroethyl acrylate, phenyl acrylate; vinyl methyl ether, vinyl Vinyl ethers such as nil 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 N-vinyl compounds such as: vinyl naphthalenes; acrylic acid derivatives or methacrylic acid derivatives such as acrylonitrile, methacrylonitrile, and acrylamide. These vinyl monomers are used alone or in admixture of two or more monomers.
[0124]
Among these, a combination of monomers that becomes a styrene copolymer or a styrene acrylic copolymer is preferable.
[0125]
As described above, the toner of the present invention is characterized by containing a wax having a peak top temperature of 70 to 120 ° C. of the maximum endothermic peak in the endothermic peak at the time of temperature rise measured by DSC. The peak top temperature of this wax is preferably 70 to 100 ° C, more preferably 70 to 90 ° C, still more preferably 70 to 80 ° C. Such a wax component is effective because it can be easily dissolved on the toner surface in a situation where pressure member contamination, edge concentration thinness, and low temperature offset are likely to occur, and the release agent for the metal sleeve can be improved.
[0126]
When the peak top temperature of the maximum endothermic peak is lower than 70 ° C., the toner storage stability, development durability, high temperature offset property and the like are likely to deteriorate. In addition, when the peak top temperature of the maximum endothermic peak is higher than 120 ° C., it is difficult for the wax component to dissolve on the toner surface, and the effect of preventing the occurrence of pressure member contamination, low edge concentration, and low temperature offset cannot be expected. .
[0127]
The wax used in the present invention preferably has a peak half-value width of the maximum endothermic peak of 12 ° C. or less, more preferably 10 ° C. or less, in the endothermic peak at the time of temperature rise measured by DSC. More preferably, it is 8 degrees C or less.
[0128]
Since the wax having such a half-value width has the property of easily dissolving on the toner surface, an excellent effect can be obtained even with a small addition amount. Further, even if the amount added is increased, the toner storage stability is not adversely affected, so that the effect can be further increased. If the full width at half maximum is greater than 12 ° C, the storage stability may be deteriorated.
[0129]
Furthermore, the wax used in the present invention has a start point onset temperature of 50 ° C. or higher (more preferably 60 ° C. or higher) and an end point onset temperature of 100 ° C. or lower at the endothermic peak at the time of temperature rise measured by DSC. (More preferably 90 ° C. or less). Such a wax dissolves on the surface of the toner while maintaining the elasticity of the toner, so that it is effective in preventing the pressure member from being stained, the edge density is thin, and the low temperature offset is prevented.
[0130]
When the starting point onset temperature is 50 ° C. or less, the storage stability of the toner tends to deteriorate. If the end point onset temperature is 100 ° C. or higher, the wax component is difficult to dissolve on the toner surface, and the effect of the wax may be reduced.
[0131]
The method for measuring the DSC of the wax in the present invention is shown below.
[0132]
<DSC measurement method>
In the DSC measurement in the present invention, DSC-7 (manufactured by PerkinElmer) or DSC2920 (manufactured by TA Instruments Japan) can be used. The measuring method is performed according to ASTM D3418-82. The DSC curve used in the present invention is the DSC curve measured at the time of the second temperature increase after the temperature is increased once and the previous history is taken and then the temperature is decreased at a temperature rate of 10 ° C./min. Each temperature is defined as follows.
[0133]
・ Peak top temperature of maximum endothermic peak
Peak top temperature of the highest peak from the baseline.
[0134]
・ Half width of maximum endothermic peak
The temperature range of the peak with the highest height from the baseline at half the height from the baseline to the peak top.
[0135]
・ End-point onset temperature of endothermic peak
The temperature at the intersection of the tangent of the curve and the baseline at the point where the differential value of the rising curve is maximum.
[0136]
・ End point onset temperature of endothermic peak
The temperature at the intersection of the tangent of the curve and the baseline at the point where the differential value of the rising curve is minimum.
[0137]
Furthermore, the wax used in the present invention has a melt viscosity at 120 ° C. of 100 mPa · s or less (preferably 1 to 50 mPa · s, more preferably 1 to 30 mPa · s, and still more preferably 1 to 1 m) measured with an E-type viscometer. 15 mPa · s) is preferable. Such a low-viscosity wax is easy to move in the binder resin when the toner is heated and the wax is melted, and is easy to be dissolved out on the toner surface, so that the effect is easily exhibited. When the melt viscosity is greater than 100 mPa · s, the fixing device used in the present invention is less likely to exhibit a sufficient effect, and it is difficult to obtain an effect for preventing the occurrence of pressure member contamination, low edge density, and low temperature offset.
[0138]
The method for measuring the melt viscosity of the wax in the present invention is shown below.
<Measurement of melt viscosity of wax>
The melt viscosity of the wax component is measured using an E-type rotational viscometer. As the viscometer, VT-500 (manufactured by HAAKE) is used. In the examples described later, VT-500 is used, the measurement temperature is adjusted to 120 ° C. using an oil bath with a temperature regulator, PK 1,0.5 ° is used for the sensor, and the share rate is 6,000 s.^-1Measured with
[0139]
The following can be used as the wax used in the present invention. Examples thereof include compounds such as polyolefin wax, polyethylene wax, microcrystalline wax, carnauba wax, Fischer-Tropsch wax, paraffin wax, higher alcohol wax, ester wax, and oxides and graft modified products thereof.
[0140]
Preferred waxes include polyolefins obtained by radical polymerization of olefins under high pressure; polyolefins obtained by purifying low molecular weight by-products obtained during polymerization of high molecular weight polyolefins; Polyolefins; polyolefins polymerized using radiation, electromagnetic waves, light, etc .; low molecular weight polyolefins obtained by thermal decomposition of high molecular weight polyolefins; paraffin wax; microcrystalline wax; Fischer-Tropsch wax; Synthetic hydrocarbon waxes synthesized by, etc .; synthetic waxes containing a compound having 1 carbon atom; hydrocarbon waxes having functional groups such as hydroxyl groups and carboxyl groups; hydrocarbon waxes and functional groups And the like a mixture of a hydrocarbon wax that.
[0141]
In addition, these waxes have a sharp molecular weight distribution using a press sweating method, a solvent method, a recrystallization method, a vacuum distillation method, a supercritical gas extraction method, a fused liquid crystal deposition method, a low molecular weight solid fatty acid, a low A molecular weight solid alcohol, a low molecular weight solid compound, and other impurities are preferably used.
[0142]
Particularly preferably used are paraffin wax, Fischer-Tropsch wax, polyethylene synthesized using a metallocene catalyst, low molecular weight by-product distillation products obtained during polyethylene polymerization, and the like.
[0143]
In the toner of the present invention, the content of these waxes is 0.1 to 20 parts by mass, preferably 0.5 to 10 parts by mass with respect to 100 parts by mass of the binder resin.
[0144]
In addition, the toner of the present invention is characterized in that the porosity determined from the tap density is 0.4 to 0.7 (preferably 0.45 to 0.65, more preferably 0.50 to 0.60). To do. When the porosity is within this range, the toner particles are densely packed on the recording material (the toner image developed per unit area of the recording material is the same, but the height of the toner image is low). Therefore, even if the nip portion of the fixing device is rubbed to some extent, the toner image is hardly disturbed, and it is effective in preventing the occurrence of low end density. In addition, since the toner particles are developed in a state where the toner particles are densely packed on the recording material, the adhesive force between the toner and the recording material can be increased with a small pressing force at the time of fixing, and the fixing device used in the present invention also has a low temperature offset. Generation can be suppressed.
[0145]
When the porosity is less than 0.4, the toner is difficult to be uniformly charged, and the image density may be lowered or fog may be increased. On the other hand, if the porosity is larger than 0.7, the effect of preventing the occurrence of low edge concentration and low temperature offset may be lost.
[0146]
The porosity can be adjusted by changing the particle size distribution of toner particles and the amount and type of external additives such as silica (external additives will be described later). Specifically, the void ratio tends to increase as the particle size of the toner decreases and the amount of fine powder increases, and conversely, the void ratio decreases as the particle size of the toner increases and the amount of fine powder decreases. Further, if the amount of the external additive such as silica is increased to improve the fluidity of the toner, the void ratio tends to be small.
[0147]
The porosity in this invention is calculated | required with the following formula | equation.
[0148]
[Expression 4]
Porosity = (true density-tap density) / true density
[0149]
The methods for measuring true density and tap density are shown below.
[0150]
<Measurement of true density>
1 g of toner is put into an IR measurement tablet molding machine and about 1.96 MPa (200 kgf / cm²) At a pressure of 1 minute for 1 minute. The volume and mass of this sample are measured to determine the true density.
[0151]
<Measurement of tap density>
The value measured according to the procedure of the instruction manual of the powder tester using a powder tester manufactured by Hosokawa Micron Co., Ltd. and using the container attached to the powder tester. That is, a measuring cup for a powder tester (internal volume: Vcm^Three) Put the toner in a cup and tap it. After tapping is completed, excess toner is scraped off with a blade, and the mass (Wg) of the toner is measured. The tap density can be obtained by the following equation.
[0152]
[Equation 5]
Tap density = W / V (g / cm^Three)
[0153]
The toner of the present invention may be used as a two-component developer in combination with a carrier, or may be used as a one-component developer composed only of toner (without using a carrier). As the carrier in the case where the toner of the present invention is used as a two-component developer, all conventionally known carriers can be used. Specifically, surface oxidized or unoxidized iron, nickel, cobalt, manganese, Particles having an average particle size of 20 to 300 μm, such as metals such as chromium and rare earth, and alloys or oxides thereof, are used.
[0154]
Further, those obtained by adhering or covering substances such as styrene resin, acrylic resin, silicone resin, fluorine resin, polyester resin on the surface of the carrier particles are preferably used.
[0155]
The toner of the present invention can be used as a magnetic toner by further containing a magnetic material. In this case, the magnetic material can also serve as a colorant. In the present invention, the magnetic material contained in the magnetic toner includes iron oxides such as magnetite, maghemite, and ferrite; metals such as iron, cobalt, and nickel; and these metals and aluminum, cobalt, copper, lead, magnesium, tin, Examples thereof include alloys of metals such as zinc, antimony, beryllium, bismuth, cadmium, calcium, manganese, selenium, titanium, tungsten, and vanadium, and mixtures thereof.
[0156]
These ferromagnetic materials have an average particle diameter of 2 μm or less, preferably 0.1 to 0.5 μm. The amount to be contained in the toner is about 20 to 200 parts by mass, particularly preferably 40 to 150 parts by mass with respect to 100 parts by mass of the binder resin.
[0157]
The colorant that can be used in the toner of the present invention includes any appropriate pigment or dye. Examples of the toner colorant include carbon black, aniline black, acetylene black, naphthol yellow, Hansa yellow, rhodamine lake, alizarin lake, Bengala, phthalocyanine blue, and indanthrene blue as pigments. These are used in an amount necessary and sufficient to maintain the optical density of the fixed image, and an addition amount of 0.1 to 20 parts by mass, preferably 0.2 to 10 parts by mass is good with respect to 100 parts by mass of the binder resin. . For the same purpose, a dye is further used. For example, there are azo dyes, anthraquinone dyes, xanthene dyes, and methine dyes, and the addition amount is preferably 0.1 to 20 parts by weight, preferably 0.3 to 10 parts by weight with respect to 100 parts by weight of the binder resin. .
[0158]
The toner of the present invention may further have a charge control agent. The following substances are used for controlling the toner to be negatively charged.
[0159]
For example, organometallic complexes and chelate compounds are effective, and there are monoazo metal complexes, acetylacetone metal complexes, aromatic hydroxycarboxylic acids, and aromatic dicarboxylic acid metal complexes. Other examples include aromatic hydroxycarboxylic acids, aromatic mono- and polycarboxylic acids and metal salts thereof, anhydrides, esters, and phenol derivatives such as bisphenol.
[0160]
Moreover, the azo metal complex represented by the following general formula (1) is preferable.
[0161]
[Chemical 1]

[Wherein M represents a coordination center metal, and examples thereof include Sc, Ti, V, Cr, Co, Ni, Mn, and Fe. Ar is an aryl group, and examples thereof include a phenyl group and a naphthyl group, which may have a substituent. Examples of the substituent in this case include a nitro group, a halogen group, a carboxyl group, an anilide group, an alkyl group having 1 to 18 carbon atoms, and an alkoxy group. X, X ′, Y, and Y ′ are —O—, —CO—, —NH—, and —NR— (R represents an alkyl group having 1 to 4 carbon atoms). A⁺Represents hydrogen, sodium, potassium, ammonium, aliphatic ammonium or none. ]
[0162]
The coordination center metal in the general formula (1) is particularly preferably Fe or Cr, the substituent is preferably a halogen, an alkyl group, or an anilide group, and the counter ion is hydrogen, alkali metal ammonium, or aliphatic ammonium. preferable. A mixture of complex salts having different counter ions is also preferably used.
[0163]
Alternatively, the basic organic acid metal complex represented by the following general formula (2) also gives negative chargeability and can be used in the present invention.
[0164]
[Chemical formula 2]

[0165]
In the general formula (2), the central metal is particularly preferably Fe, Cr, Si, Zn, or Al, the substituent is preferably an alkyl group, anilide group, aryl group, or halogen, and the counter ion is hydrogen, ammonium, or fatty acid. Group ammonium is preferred.
[0166]
Among the negatively chargeable charge control agents, an azo metal complex represented by the general formula (1) is more preferable, and an azo iron complex represented by the following formula (3) is most preferable.
[0167]
[Chemical 3]

[0168]
Next, specific examples of the complex are shown.
[0169]
[Formula 4]

[0170]
[Chemical formula 5]

[0171]
[Chemical 6]

[0172]
Further, there are the following substances as charge control agents for controlling the toner to be positively charged. Modified products with nigrosine and fatty acid metal salts; oniums such as quaternary ammonium salts such as tributylbenzylammonium-1-hydroxy-4-naphthosulfonate, tetrabutylammonium tetrafluoroborate, and phosphonium salts which are analogs thereof Salts and their lake pigments, triphenylmethane dyes and their lake pigments Russian compounds, metal salts of higher fatty acids; diorganotin oxides such as dibutyltin oxide, dioctyltin oxide, dicyclohexyltin oxide; dibutyltin borate, dioctyltin borate, dicyclohexyl Diorgano tin borate such as Suzuboreto; guanidine compounds, imidazole compounds. These can be used alone or in combination of two or more. Among these, triphenylmethane compounds and quaternary ammonium salts whose counter ions are not halogen are preferably used. Further, the general formula (4)
[0173]
[Chemical 7]

[Wherein R₁Is H or CH_ThreeR₂And R_ThreeIs a substituted or unsubstituted alkyl group (preferably C₁~ C_Four)
[0174]
A copolymer with a polymerizable monomer such as styrene, acrylic acid ester, or methacrylic acid ester described above can be used as a positive charge control agent. In this case, these charge control agents also have an action as a binder resin (all or a part thereof).
[0175]
In particular, a compound represented by the following general formula (5) is preferable in the configuration of the present invention.
[0176]
[Chemical 8]

[Wherein R₁, R₂, R_Three, R_Four, R_FiveAnd R₆Each represents a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group, which may be the same as or different from each other, and R₇, R₈And R₉Represents a hydrogen atom, a halogen atom, an alkyl group or an alkoxy group, which may be the same or different from each other, and A^-Is an anion selected from sulfate ion, nitrate ion, borate ion, phosphate ion, hydroxide ion, organic sulfate ion, organic sulfonate ion, organic phosphate ion, carboxylate ion, organic borate ion or tetrafluoroborate Indicates. ]
[0177]
As a method of adding a charge control agent to the toner, there are a method of adding it inside the toner and a method of adding it externally (externally) to the toner particles. The amount of these charge control agents used is determined by the type of binder resin, the presence / absence of other additives, and the toner production method including the dispersion method, and is not uniquely limited. Is used in the range of 0.1 to 10 parts by mass, more preferably 0.1 to 5 parts by mass with respect to 100 parts by mass of the binder resin.
[0178]
In the toner of the present invention, it is preferable to add silica fine powder as an external additive in order to improve charging stability, developability, fluidity and durability.
[0179]
The silica fine powder used in the present invention has a specific surface area of 20 m by nitrogen adsorption measured by the BET method.²/ G or more (especially 30 to 400 m²/ G) gives good results. The silica fine powder is used in an amount of 0.01 to 8 parts by weight, preferably 0.1 to 5 parts by weight, based on 100 parts by weight of the toner particles.
[0180]
In addition, the above silica fine powder may be used for the purpose of hydrophobization, chargeability control, etc., if necessary, silicone varnish, various modified silicone varnishes, silicone oil, various modified silicone oils, silane coupling agents, silylating agents, other organic It is also preferable to treat with a treating agent such as a silicon compound or with various treating agents.
[0181]
Moreover, it is also preferable to add the following inorganic powder as an external additive in order to improve developability and durability. Metal oxides such as magnesium, zinc, aluminum, cerium, cobalt, iron, zirconium, chromium, manganese, strontium, tin, antimony; complex metal oxides such as calcium titanate, magnesium titanate, strontium titanate; calcium carbonate, Metal salts such as magnesium carbonate and aluminum carbonate; clay minerals such as kaolin; phosphate compounds such as apatite; silicon compounds such as silicon carbide and silicon nitride; and carbon powders such as carbon black and graphite. Of these, zinc oxide, aluminum oxide, cobalt oxide, manganese dioxide, strontium titanate, magnesium titanate and the like are preferable.
[0182]
Further, the following lubricant powder can be added as an external additive. Fluorine resins such as Teflon (registered trademark) and polyvinylidene fluoride; Fluorine compounds such as carbon fluoride; Fatty acid metal salts such as zinc stearate; Fatty acid derivatives such as fatty acids and fatty acid esters; Molybdenum sulfide, amino acids and amino acid derivatives .
[0183]
In order to produce the toner of the present invention, a binder resin, a wax, a pigment or dye as a colorant as required, a magnetic material, a charge control agent, other additives, etc. are mixed with a mixer such as a Henschel mixer or a ball mill. After thorough mixing, the resins are compatible with each other by melt kneading using a heat kneader such as a heating roll, a kneader, or an extruder. A pigment, dye, magnetic substance or the like is dispersed or dissolved therein, and after cooling and solidification, pulverization and classification are performed to obtain toner particles. Further, if necessary, the toner of the present invention can be obtained by sufficiently mixing desired additives such as silica fine powder and other inorganic powders with a mixer such as a Henschel mixer.
[0184]
As a toner production apparatus, for example, as a mixer, a Henschel mixer (manufactured by Mitsui Mining Co., Ltd.); a super mixer (manufactured by Kawata Corporation); a ribocorn (manufactured by Okawara Seisakusho Co., Ltd.); a nauter mixer, a turbulizer, and a cyclomix (Hosokawa Micron Corporation) Spiral pin mixer (manufactured by Taiheiyo Kiko Co., Ltd.); Ladige mixer (manufactured by Matsubo Co., Ltd.), and KRC kneader (manufactured by Kurimoto Iron Works Co.); Bus co-kneader (manufactured by Buss) ); TEM type extruder (manufactured by Toshiba Machine Co., Ltd.); TEX twin-screw kneader (manufactured by Nippon Steel Works); PCM kneader (manufactured by Ikegai Iron Works Co., Ltd.); triple roll mill, mixing roll mill, kneader (manufactured by Inoue Seisakusho Co., Ltd.) ); Needex (Mitsui Mining Co., Ltd.); MS pressure kneader, Nider Ruder (Moriyama Seisakusho); Banbury Miki -(Made by Kobe Steel Co., Ltd.), and the pulverizers include counter jet mill, micron jet, inomizer (manufactured by Hosokawa Micron); IDS type mill, PJM jet pulverizer (manufactured by Nippon Pneumatic Industrial Co., Ltd.); cross jet Mill (manufactured by Kurimoto Iron Works); Urmax (manufactured by Nisso Engineering); SK Jet O Mill (manufactured by Seishin Enterprise); Kryptron (manufactured by Kawasaki Heavy Industries); Turbo mill (manufactured by Turbo Industry); Super Rotor (manufactured by Nissin Engineering Co., Ltd.) is listed, and classifiers include class seal, micron classifier, spedic classifier (manufactured by Seishin Enterprise Co.); turbo classifier (manufactured by Nisshin Engineering Co., Ltd.); micron separator, turbo Plex (ATP), TSP separator Hosokawa Micron Co., Ltd.); Elbow Jet (Nittetsu Mining Co., Ltd.), Dispersion Separator (Nihon Pneumatic Kogyo Co., Ltd.); YM Micro Cut (Yaskawa Shoji Co., Ltd.), and the like are used to screen coarse particles. Ultrasonic (Shoei Sangyo Co., Ltd.); Resonator Sheave, Gyroshifter (Tokusu Kosakusha Co., Ltd.); Vibrasonic System (Dalton Co.); Soniclean (Shinto Kogyo Co.); Turbo Screener (Turbo) (Industry company); Micro shifter (manufactured by Hadano Sangyo Co., Ltd.); Circular vibration sieve and the like.
[0185]
Hereinafter, the image forming method and the image forming apparatus of the present invention using the toner of the present invention will be described.
[0186]
The image forming method of the present invention includes a step of fixing an unfixed toner image formed on a recording material by the fixing means used in the present invention. The image forming apparatus of the present invention is an apparatus that has the fixing means used in the present invention and that forms an image using the toner of the present invention.
[0187]
The fixing means used in the present invention includes a heating metal sleeve having a flexible cylindrical metal base tube as a base layer, and is placed in contact with the inner surface of the heating metal sleeve and heats the heating metal sleeve. A heating fixing device having at least a heating member and a cylindrical pressure member that is in pressure contact with the heating member via the heating metal sleeve and has an axis parallel to the heating metal sleeve. In the heat-fixing apparatus of the present invention, the fixing maintained at a predetermined temperature by pressing the metal sleeve for heating (hereinafter sometimes simply referred to as “metal sleeve”) and the pressure member together. The recording material on which the nip portion is formed and the unfixed toner image is formed passes through the nip portion, whereby the unfixed toner image is fixed on the recording material.
[0188]
The thickness of the metal pipe constituting the metal sleeve used in the present invention is preferably 20 to 100 μm. The inner surface of the metal sleeve preferably has a surface roughness Rz = 3 μm or less in order to keep the contact thermal resistance with the heating member low and to improve heat transfer to the fixing nip. Furthermore, it is also preferable that the surface roughness of the outer surface of the metal sleeve is Rz = 3 μm or less, and a release layer including a primer layer as an adhesive layer is formed on the metal sleeve with a thickness of 20 μm or less. .
[0189]
As described above, in the heat fixing apparatus used in the present invention, the heat fixing is performed with high thermal efficiency corresponding to the speeding up of the image forming apparatus by performing contact heating from the inner surface of the metal sleeve having good thermal conductivity by the heating member. it can. Accordingly, the energization to the heater can be shut down during standby when the image forming apparatus is not receiving a print signal, and energy-saving heating and fixing can be realized.
[0190]
Even when the image forming apparatus is turned on from room temperature, the print signal can be received immediately, so that the user does not have to wait. Therefore, even when the speed of the image forming apparatus is increased, it is possible to provide a heat fixing apparatus that has excellent quick start characteristics and quick first print time.
[0191]
Further, by using a metal sleeve having a higher rigidity than that of a resin film, it is possible to set a high pressing force, and it is possible to cope with an increase in the speed of the image forming apparatus.
[0192]
Further, it is preferable to provide a heat-resistant resin member such as a polyimide resin on the surface that contacts the inner surface of the metal sleeve and heats the fixing nip portion. Accordingly, the sliding between the inner surface of the metal sleeve and the heating member can be made smooth, so that a more highly durable heat fixing can be achieved.
[0193]
Further, the metal sleeve is subjected to circumferential streaking within the surface roughness, whereby the metal sleeve can be smoothly rotated and the surface of the heating member can be hardly damaged.
[0194]
Also, in a heat fixing device for fixing an unfixed toner image on a recording material, a bias having a polarity opposite to that of the toner is applied to the pressure roller side, and a metal sleeve is grounded or connected to a diode so that paper dust, toner, etc. Prevents adsorption to the metal sleeve. Accordingly, there can be provided a highly durable heat fixing device without a problem such that the metal sleeve is soiled by durable use.
[0195]
As described above, by using the heat fixing device in combination with the toner of the present invention, on-demand that can be fixed immediately after the power is turned on and does not require standby preheating, and that achieves a significant reduction in power consumption. An image that enables high-speed fixing with a heat-fixing device of the type, has sufficient fixing properties without causing low-temperature offset and high-temperature offset, and can further improve pressure member contamination and edge density thinning. A forming method can be provided.
[0196]
The image forming method of the present invention can be realized by appropriately combining known members and means. More specifically, the image forming method of the present invention can be realized by applying a modification to which a fixing unit that realizes the above-described fixing process is mounted to a known image forming apparatus. A specific example of the image forming apparatus of the present invention, which is an image forming apparatus suitable for realizing the image forming method of the present invention, will be described below with reference to the drawings.
[0197]
(A) Example of image forming apparatus
FIG. 1 is a schematic configuration diagram showing an example of an image forming apparatus of the present invention. Reference numeral 1 denotes a photosensitive drum, and a photosensitive material such as OPC, amorphous Se, or amorphous Si is formed on a cylindrical substrate such as aluminum or nickel. The photosensitive drum 1 is rotationally driven in the direction of the arrow, and first, the surface thereof is uniformly charged by a charging roller 2 as a charging device (charging process).
[0198]
Next, scanning exposure is performed with the laser beam 3 that is ON / OFF controlled according to the image information, and an electrostatic latent image is formed (latent image forming step). This electrostatic latent image is developed and visualized by the developing device 4 to become a toner image (developing step). As a developing method, a jumping developing method, a two-component developing method, an FEED developing method, or the like is used, and image exposure and reversal development are often used in combination.
[0199]
The visualized toner image is transferred from the photosensitive drum 1 onto a recording material P as a transfer material conveyed at a predetermined timing by a transfer roller 5 as a transfer device (transfer process). Here, the leading end of the recording material P is detected by the sensor 8 so that the image forming position of the toner image on the photosensitive drum 1 matches the writing position of the leading end of the recording material, and the conveyance timing is adjusted. The recording material P conveyed at a predetermined timing is nipped and conveyed between the photosensitive drum 1 and the transfer roller 5 with a constant pressure.
[0200]
The recording material P onto which the unfixed toner image has been transferred is conveyed to the heat fixing device 6 and fixed (fixing step). On the other hand, the residual toner remaining on the photosensitive drum 1 is removed from the surface of the photosensitive drum 1 by the cleaning device 7 (cleaning step).
[0201]
(B) Heat fixing device 6
FIG. 2 is a schematic configuration diagram of the heat fixing device 6. In FIG. 2, 10 is a fixing member, and 20 is a pressure member. The fixing member 10 includes a heater 11 as a heating member, a heat insulating stay holder 12, a metal sleeve 13 used as a fixing sleeve, and the like. The pressure member 20 is a heat-resistant elastic pressure roller and is in pressure contact with the metal sleeve 13. In other words, the fixing nip portion N is formed by the metal sleeve 13 and the pressure member 20 being pressed against each other.
[0202]
a) Heating metal sleeve 13
The heating metal sleeve 13 used as the fixing sleeve is a sleeve having a small heat capacity, and has a thickness of 100 μm or less to enable quick start, and has heat resistance and high thermal conductivity, SUS, Al, Ni, Cu , A metal sleeve (film) based on a flexible cylindrical metal element tube made of a single metal such as Zn or an alloy.
[0203]
The metal sleeve 13 needs to have a thickness of 20 μm or more in order to obtain a metal sleeve having sufficient strength for constituting a long-life heat fixing device and having excellent durability. Therefore, the thickness of the metal sleeve 13 is optimally 20 μm or more and 100 μm or less.
[0204]
Further, in order to prevent offset and ensure separation of the recording material, the surface layer of the metal sleeve 13 is made of PTFE (polytetrafluoroethylene), PFA (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer), FEP (tetrafluoro). Release properties of fluororesins such as ethylene-hexafluoropropylene copolymer), ETFE (ethylene-tetrafluoroethylene copolymer), CTFE (polychlorotrifluoroethylene), PVDF (polyvinylidene fluoride), and silicone resins A good heat-resistant resin is coated with a release layer (not shown) formed singly or in combination of two or more.
[0205]
As a method of covering the surface of the metal sleeve 13 with the release layer, a primer layer as an adhesive layer is applied to the outer surface of the metal sleeve base layer, and then the release layer is formed. The releasable layer may be formed by application such as dipping or powder spray, or may be a system in which a tube-shaped material is covered on the surface of a metal sleeve.
[0206]
The surface properties of the inner and outer surfaces of the metal sleeve, the thickness of the releasable layer, and the like will be described in detail in section e) below.
[0207]
b) Heater 11
A heating heater 11 as a heating member is disposed in contact with the inner surface of the metal sleeve 13 and heats the metal sleeve 13 to heat the nip portion that melts and fixes the toner image on the recording material P.
[0208]
FIG. 3 is a partially enlarged view of the vicinity of the fixing nip N in FIG. FIG. 4 is a schematic cross-sectional view taken along the line II of FIG. In FIG. 3, a heater 11 is provided in the longitudinal direction (orthogonal to the drawing) on the surface of a substrate 11a made of a highly insulating ceramic such as alumina or AlN (aluminum nitride), or a heat resistant resin such as polyimide, PPS, or liquid crystal polymer. Direction), for example, Ag / Pd (silver palladium), RuO₂, Ta₂An energization heating member formed by coating the energization heat generating resistance layer 11b of N or the like into a linear or narrow strip having a thickness of about 10 μm and a width of about 1 to 5 mm by screen printing or the like. On the surface of the energization heat generating resistance layer 11b, there is a sliding layer 11c made of a heat-resistant resin layer such as a thin fluororesin layer, polyimide, polyamideimide, and PEEK that can withstand sliding against the metal sleeve 13. Is provided.
[0209]
A temperature detection element 14 such as a thermistor for detecting the temperature of the heating heater 11 raised in accordance with the heat generated by the energization heat generation resistance layer 11b is provided on the back surface (the surface opposite to the fixing nip portion N) of the substrate 11a. It is arranged. In accordance with the signal of the temperature detection element 14, the voltage applied to the energization heating resistor layer 11b from the electrode portions 11f and 11g at the end in the longitudinal direction shown in FIG. 4 (direction parallel to the cored bar 21 in FIG. 4). By appropriately controlling the duty ratio, wave number, etc., the temperature in the fixing nip N is kept substantially constant, and heating necessary for fixing the toner image on the recording material P is performed. DC energization from the temperature detecting element 14 to a temperature control unit (not shown) is achieved by a connector (not shown) via a DC energization unit and a DC electrode unit (not shown).
[0210]
Another embodiment of the heater for heating is shown in FIG. FIG. 5 is also a partial cross-sectional view showing the vicinity of the heater of the heat fixing device, as in FIG. As shown in FIG. 5, when AlN (aluminum nitride) or the like having good thermal conductivity is used as the heater substrate 11a, the energized heat generating resistance layer 11b is formed on the opposite side of the fixing nip portion N of the substrate 11a. It may be. In FIG. 5, 11d is a protective layer such as a glass coat or a fluororesin layer provided to satisfy the withstand voltage between the energization heating resistor layer 11d formed on the substrate 11a and the temperature detecting element 14. 11e is a sliding layer made of a heat-resistant resin layer such as a thin fluororesin layer, polyimide, polyamideimide, PEEK and the like that can withstand sliding against the metal sleeve as in the case of 11c described above.
[0211]
Further, the fixing member having a longer life can be obtained by forming a curved surface on the fixing nip portion N side of the heater 11 on the inner surface of the metal sleeve 13 so that a bending load is not applied to the metal sleeve 13. Is formed. Alternatively, the substrate (11a) is made of metal, and an insulating layer and an energization heating resistance layer are sequentially laminated on the opposite side of the fixing nip portion on the metal substrate. A metal heater having a shape curved in the same direction as the metal sleeve may be used.
[0212]
c) Insulated stay holder 12
The heat insulating stay holder 12 is a heat insulating member that holds the heater 11 and prevents heat dissipation in the direction opposite to the fixing nip N, and is formed of liquid crystal polymer, phenol resin, PPS, PEEK, or the like. A metal sleeve 13 is loosely fitted on the heat insulating stay holder 12 with a margin, and the metal sleeve 13 is disposed so as to be rotatable in the direction of the arrow.
[0213]
Further, since the metal sleeve 13 rotates while rubbing against the internal heating heater 11 and the heat insulating stay holder 12, the frictional resistance between the heating heater 11 and the heat insulating stay holder 12 and the metal sleeve 13 needs to be kept small. There is. Therefore, a small amount of lubricant such as heat resistant grease is interposed on the surfaces of the heater 11 and the heat insulating stay holder 12. Thereby, the metal sleeve 13 can be rotated smoothly.
[0214]
d) Pressurizing member 20
The pressure member 20 is a roller member formed of an elastic layer 22 formed by foaming heat-resistant rubber such as silicone rubber or fluorine rubber or silicone rubber on the outer side of the core metal 21, and PFA, A releasable layer 23 made of PTFE, FEP, or the like may be formed.
[0215]
As shown in FIG. 4, the fixing member 10 is pressed by a pressing means 17 such as a spring provided directly on a part of the heat insulating stay holder 12 or a member attached to the heat insulating stay holder by fitting or the like. The pressure member 20 is sufficiently pressed from both ends in the longitudinal direction so as to form a fixing nip portion N necessary for heat fixing. Further, the pressure member 20 is rotationally driven by a driving gear 16 attached to the end of the core 21 of the pressure member 20, and the metal sleeve 13 is predetermined by friction between the pressure roller surface and the metal sleeve 13 surface. Rotate the follower at the speed of.
[0216]
The above is the configuration of the heat fixing device 6. In FIG. 2, the recording material P is appropriately supplied by a supply unit (not shown), and is formed by the heating member 10 and the pressure member 20 along the heat-resistant fixing inlet guide 15. To the fixing nip N. Then, the recording material P passes through the fixing nip portion N by the rotation of the pressure member 20 and the metal sleeve 13, whereby an unfixed image is fixed on the recording material P, and a fixed image is obtained.
[0217]
e) Surface roughness of the inner and outer surfaces of the metal sleeve 13
Here, the surface roughness of the inner and outer surfaces of the metal sleeve 13, the thickness of the releasable layer, and the like will be described below.
[0218]
First, the inner surface of the metal sleeve 13 needs to transfer heat generated from the heater 11 to the fixing nip portion N by contacting the heater 11 with a predetermined contact width, which has been conventionally used. The idea is different from a heat roller fixing device (see FIG. 10) that performs heating by radiant heat. Therefore, the surface roughness of the inner surface of the metal sleeve 13 that contacts and heats the heater 11 greatly affects the thermal efficiency. In particular, when the contact thermal resistance between the surface of the sliding layer of the heater 11 (11c in FIG. 3 or 11e in FIG. 5) and the inner surface of the metal sleeve 13 is increased, the thermal efficiency is deteriorated and fixing failure occurs. In order to construct a heat-fixing device having high thermal efficiency even when heat conductive grease or the like is interposed, it is preferable to suppress the surface roughness to a predetermined level or less.
[0219]
Further, as described above, a release layer is formed on the outer surface of the metal sleeve 13, but since the release layer is generally made of a fluororesin, its thermal conductivity is that of the metal sleeve 13. Extremely low compared to thermal conductivity. Therefore, if the releasable layer is formed too thick, heat conduction is deteriorated, and sufficient heat cannot be supplied to the toner image on the recording material P at the fixing nip portion N for speeding up the image forming apparatus. Therefore, it is necessary to form a thin release layer on the metal sleeve 13. At this time, the surface roughness of the outer surface of the metal sleeve 13 is preferably suppressed to a predetermined level or less. That is, when the release layer is thinned, the effect of relaxing the surface roughness of the outer surface of the metal sleeve 13 by the release layer cannot be obtained. Therefore, the release layer is applied and formed on the outer surface of the metal sleeve 13. The resulting surface roughness is equal to or slightly smaller than the surface roughness of the metal sleeve 13 tube. Therefore, if the surface roughness of the metal sleeve 13 is large, the surface roughness becomes large even after the release layer is applied and formed, and the adhesion to the recording material P cannot be obtained at the fixing nip portion N. The possibility of causing increases.
[0220]
From the above, sufficient fixing performance can be obtained by applying and forming a release layer having a predetermined thickness or less including a primer layer as an adhesive layer with a surface roughness of the outer surface of the metal sleeve 13 being a predetermined value or less. As a result, it is possible to cope with the high speed of the image forming apparatus.
[0221]
Further, by providing the metal sleeve 13 with an uneven shape having a surface roughness of a predetermined value or less in the circumferential direction, the metal sleeve 13 can be rotated more smoothly and the release layer coated on the surface of the heater 11 for heating. Make it hard to hurt. As a result, it is possible to provide a highly durable metal sleeve 13 for heat fixing that can be applied at high speed.
[0222]
Hereinafter, with reference to FIGS. 6-8, the manufacturing method of the metal sleeve 13 which has moderate unevenness | corrugation in the circumferential direction is shown. First, in FIG. 6, 31 is a base material of the metal sleeve 13, and SUS, Al, Ni, Cu, Zn or the like of about 0.1 to 0.5 mm is formed alone or in an alloy state of two or more kinds. It is a metal flat plate. Reference numeral 32 denotes a circular inner die (punch) in a general deep drawing method, and 33 denotes a cylindrical container-like outer die (die), each of which is a die having a surface of a metal material subjected to carbide plating or the like. In FIG. 6, the metal flat plate 31 is sandwiched between the inner mold 32 and the outer mold 33, and the inner mold 32 is pushed in the direction of the outer mold 33 in the direction of the arrow. Further, a highly viscous lubricating oil or a solid lubricant such as graphite or molybdenum disulfide is interposed between the metal flat plate 31 and the outer mold 33 to improve the drawability. The cup-shaped metal cylindrical member 34 as shown in FIG. 7 is manufactured by deep drawing with the different molds usually about 2 to 4 times.
[0223]
Next, ironing is performed so that the metal cylindrical member 34 is formed to a predetermined thickness. As the ironing process, any process such as rolling process, drawing process, drawing process, etc. may be performed in the middle, but the final process is less than predetermined in the circumferential direction of the metal sleeve by the following process method The process which has the unevenness of is given. For example, a processing method as shown in FIGS. 8A and 8B is used.
[0224]
First, FIG. 8A shows a general drawing spinning process. In FIG. 8A, the pressing roller 36a rotatably attached to the shaft 36b attached to the fixed base 36c is in the direction of the metal inner die 35 in a state where it is always separated from the metal inner die 35 by a predetermined distance. Can be pushed to. A metal cylindrical member 34, which has been deep drawn in the shape of a cup, is fitted into the metal inner mold 35, and the cup-shaped bottom portion of the metal cylindrical member 34 is fixed in close contact with the metal inner mold 35 by a pressing member 37. Is done. In this state, the metal inner die 35, the metal cylindrical member 34, and the pressing member 37 are gradually fed to the right side of the paper (in the direction of arrow B in FIG. 8) while rotating in the direction of arrow A in the figure. From the end, a rotatable roller 36a is pressed against the metal inner die 35 while maintaining a predetermined distance.
[0225]
As a result, the metal cylindrical member 34 is gradually thinned from the end portion by ironing, and finally processed to the predetermined thickness of the metal sleeve 13 in this embodiment as shown in FIG. 8C. A cup-shaped metal cylindrical member 39 is formed.
[0226]
On the metal cylindrical member 39, a roller pressing unevenness mark 39a is left in the circumferential direction during drawing and spinning. Finally, the metal sleeve 13 having moderate irregularities in the circumferential direction is obtained by cutting off the cup-shaped bottom of the metal cylindrical member 39.
[0227]
Further, as shown in FIG. 8B, instead of the pressing roller 36a, continuous dies 38a, 38b, and 38c having small inner diameters are used and fixed by a metal inner die 35 and a pressing member 37. Alternatively, the metal cylindrical member 34 may be fed and ironed while being rotated, and the metal cylindrical member 34 may be thinned to give a circumferential uneven shape.
[0228]
In addition, any ironing processing method may be used as long as a predetermined amount or less of irregularities can be formed in the circumferential direction of the metal sleeve 13 such as spatula drawing.
[0229]
When the recording material P on which the unfixed toner image is formed is heat-fixed using the metal sleeve 13 manufactured by the above manufacturing method, it is preferable to suppress the circumferential unevenness to 3 μm or less from the viewpoint of heat conduction. .
[0230]
Concavities and convexities of 3 μm or less are formed in the circumferential direction of the metal sleeve 13, preferably the surface roughness Rz in the longitudinal direction is 3 μm or less, and the relationship with the surface roughness Rz ′ in the circumferential direction is Rz> Rz ′. Therefore, the rotation drive of the heat fixing device is kept low, the rotation is smooth, and the resin coat of the heater for heating that contacts the inner surface of the metal sleeve due to durable use is made less likely to be damaged. It is possible to achieve high speed.
[0231]
Further, a potential difference is formed between the metal sleeve 13 and the pressure roller 20 as a pressure member, and the metal sleeve 13 is grounded or grounded via a diode, whereby the metal sleeve 13 is made of paper. By adopting a configuration in which powder and toner do not easily adhere, it is possible to provide a heat fixing device that maintains releasability through durable use.
[0232]
FIG. 9A is a schematic cross-sectional view of a heat fixing device in which a potential difference is provided between the metal sleeve 13 and the pressure roller 20, and FIG. 9A is a schematic cross-sectional view along the line II-II. Are shown in FIG. In FIG. 9, a conductive elastic layer 22 of a pressure roller 20 as a pressure member is an elastic layer provided with conductivity made of conductive silicone rubber, conductive silicone sponge, or the like. Alternatively, a bias having a polarity opposite to that of the toner image is applied to the conductive elastic layer 22 by a bias applying unit 24 via a chip electrode 25 made of a conductive carbon chip or the like.
[0233]
In the drawing, the toner is negatively charged in the developing unit, and the image forming apparatus is illustrated, and a positive bias is applied to the pressure roller core 21.
[0234]
Therefore, in the case of an image forming apparatus in which toner is positively charged at the developing unit, a negative bias is applied to the pressure roller core metal 21.
[0235]
Further, the end portion of the metal sleeve 13 is provided with a portion 13a where a metal sleeve material that is not coated with a primer layer as a bonding layer and a release layer made of a fluororesin layer is exposed, and this portion 13a. It is constituted in a grounded state via a conductive brush 18 made of a more amorphous conductive fiber.
[0236]
Alternatively, it may be diode-connected so that a charge having the same potential as that of the toner image is held by the metal sleeve 13.
[0237]
With the above configuration, a configuration in which a bias is positively applied to the pressure roller 20 side makes it difficult for paper powder, toner, and the like to be attracted to the metal sleeve 13. Therefore, in the heating and fixing apparatus in which a toner image formed on a cut paper or the like mainly made of pulp material is heat-fixed, the release layer on the surface of the metal sleeve 13 having a surface roughness Rz = 3 μm or less. In this case, paper dust and toner are hardly contaminated electrostatically, and the releasability is not impaired by durable use, so that a long-life heat fixing device is provided.
[0238]
The fixing unit used in the present invention may be an oil application type fixing unit that applies oil for maintaining the releasability of the fixing member to the fixing member, or may be an oilless type fixing unit. The same effect can be obtained regardless of the difference between these methods.
[0239]
Further, in the fixing unit used in the present invention, the heating member is not limited to one that generates heat by energization as long as it generates heat by energization, for example, electromagnetic induction heat generation that generates heat by electromagnetic induction during energization. It can also be formed by a sex member.
[0240]
Further, the fixing means used in the present invention can be widely applied to heating of toner on a recording material. For example, an image heating device that presupposes an image on a recording material and an image surface property such as gloss. The present invention can also be applied to an image heating apparatus that is modified.
[0241]
In the above-described embodiment, the configuration in which the fixing member 10 is biased toward the pressure member 20 has been described. However, the present invention is not limited to this configuration, and the pressure member 20 is directed toward the fixing member 10. The fixing member 10 and the pressing member 20 may be biased in a direction approaching each other.
[0242]
In the above-described embodiment, the configuration in which the fixing nip portion N is formed by urging by the pressurizing unit 17 that expresses a sufficient urging force, represented by a spring, is shown in the present invention. However, the fixing member 10 and the pressure member 20 may be fixed to form a desired fixing nip N.
[0243]
【Example】
EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples.
[0244]
<wax>
Table 1 shows the physical properties of the waxes A to I used in Examples and Comparative Examples. In addition, FIG. 12 shows a temperature rise curve obtained by DSC measurement of wax A.
[0245]
[Table 1]

[0246]
Next, a binder resin used for the toner was prepared as follows.
[0247]
<Binder Resin Production Example 1>
[Synthesis of Low Molecular Weight Polymer (L-1)]
300 parts by mass of xylene was put into a four-necked flask, and the inside of the container was sufficiently replaced with nitrogen while stirring, and then heated to reflux. Under this reflux, a mixture of 75 parts by mass of styrene, 18 parts by mass of acrylate-n-butyl, 7 parts by mass of monobutyl maleate and 2 parts by mass of di-tert-butyl peroxide was added dropwise over 4 hours. The polymerization was completed by maintaining for a while to obtain a low molecular weight polymer (L-1) solution.
[0248]
[Synthesis of High Molecular Weight Polymer (H-1)]
Into a four-necked flask, 180 parts by mass of degassed water and 20 parts by mass of a 2% by weight aqueous solution of polyvinyl alcohol were added, then 70 parts by mass of styrene, 25 parts by mass of acrylic acid-n-butyl, 5 parts by mass of monobutyl maleate, Add 0.005 parts by mass of divinylbenzene and 0.1 part by mass of 2,2-bis (4,4-di-tert-butylperoxycyclohexyl) propane (half-life 10 hours, temperature; 92 ° C.) And stirred to give a suspension.
[0249]
After sufficiently replacing the inside of the flask with nitrogen, the temperature was raised to 85 ° C. to initiate polymerization. After maintaining at the same temperature for 24 hours, 0.1 part by mass of benzoyl peroxide (half-life 10 hours, temperature; 72 ° C.) was added. Furthermore, the polymerization was completed by maintaining for 12 hours. Then, the obtained high molecular weight polymer (H-1) was separated by filtration, washed with water and dried.
[0250]
[Binder Resin Production Example 1]
Into a four-necked flask, 100 parts by mass of xylene and 25 parts by mass of the high molecular weight polymer (H-1) were added, and the temperature was raised and stirred under reflux to perform preliminary dissolution. This state was maintained for 12 hours to obtain a preliminary solution (Y-1).
[0251]
On the other hand, 300 parts by mass of the homogeneous solution of the low molecular weight polymer (L-1) was charged into another container and refluxed. After the preliminary solution (Y-1) and the low molecular weight polymer (L-1) solution were mixed under reflux, the organic solvent was distilled off, and the resulting resin was cooled, solidified, pulverized, and then combined with toner. A resin (I) was obtained.
[0252]
When the binder resin (I) was analyzed, the main peak in the molecular weight distribution obtained by GPC was Mw (weight average molecular weight) = 15600, the sub peak was Mw = 11.4 million, the THF insoluble matter was 2.1% by mass, and the acid The value was 21 mgKOH / g. Table 2 shows the physical properties such as the molecular weight distribution of the binder resin (I).
[0253]
[Synthesis of Low Molecular Weight Polymer (L-2)]
300 parts by mass of xylene was put into a four-necked flask, and the inside of the container was sufficiently replaced with nitrogen while stirring, and then heated to reflux. After this reflux, a mixture of 75 parts by mass of styrene, 18 parts by mass of acrylate-n-butyl, 7 parts by mass of monobutyl maleate and 2.5 parts by mass of di-tert-butyl peroxide was added dropwise over 4 hours. The polymerization was completed by maintaining for 2 hours to obtain a low molecular weight polymer (L-2) solution.
[0254]
[Synthesis of Low Molecular Weight Polymer (L-3)]
300 parts by mass of xylene was put into a four-necked flask, and the inside of the container was sufficiently replaced with nitrogen while stirring, and then heated to reflux. After this reflux, a mixture of 75 parts by mass of styrene, 18 parts by mass of acrylate-n-butyl, 7 parts by mass of monobutyl maleate and 1.5 parts by mass of di-tert-butyl peroxide was added dropwise over 4 hours. The polymerization was completed by holding for 2 hours to obtain a low molecular weight polymer (L-3) solution.
[0255]
[Synthesis of High Molecular Weight Polymer (H-2)]
Into a four-necked flask, 180 parts by mass of degassed water and 20 parts by mass of a 2% by weight aqueous solution of polyvinyl alcohol were added, then 70 parts by mass of styrene, 25 parts by mass of acrylic acid-n-butyl, 5 parts by mass of monobutyl maleate, Add 0.003 parts by weight of divinylbenzene and 0.15 parts by weight of 2,2-bis (4,4-di-tert-butylperoxycyclohexyl) propane (half-life 10 hours, temperature; 92 ° C.) And stirred to give a suspension.
[0256]
After sufficiently replacing the inside of the flask with nitrogen, the temperature was raised to 85 ° C. to initiate polymerization. After maintaining at the same temperature for 24 hours, 0.15 parts by mass of benzoyl peroxide (half-life 10 hours, temperature; 72 ° C.) was added. Furthermore, the polymerization was completed by maintaining for 12 hours. Thereafter, the obtained high molecular weight polymer (H-2) was filtered off, washed with water and dried.
[0257]
[Synthesis of High Molecular Weight Polymer (H-3)]
After 85 parts by mass of styrene and 15 parts by mass of butyl methacrylate were charged into a four-necked flask and bulk polymerization was performed, xylene was added to complete solution polymerization in the presence of a solvent, and a high molecular weight polymer (H-3 )
[0258]
[Binder Resin Production Examples 2 to 4]
In the production example 1 of the binder resin, the same as the production example 1 except that the high molecular weight polymers H-1 to H-3 and the low molecular weight polymers L-1 to L-3 were combined as shown in Table 2. Using these methods, binder resins II to IV were obtained. Table 2 shows the physical properties such as molecular weight distribution of the obtained binder resins II to IV.
[0259]
[Binder Resin Production Example 5]
In the synthesis of the low molecular weight polymer (L-1) in Production Example 1 of the binder resin, the synthesis method of L-1 above was used except that monobutyl maleate was not used, divinylbenzene was used, and the initiator amount was adjusted. Using the same method, a binder resin (V) having one peak in the molecular weight distribution by GPC measurement was obtained. Table 2 shows the physical properties such as molecular weight distribution of the obtained binder resin V.
[0260]
[Table 2]

[0261]
<Example 1>
Binder resin (I) 100 parts by mass
Magnetite (average particle size 0.25 μm) 100 parts by mass
Monoazo iron complex 2 parts by mass
3 parts by weight of wax A
The raw materials were premixed with a Henschel mixer and then kneaded with a biaxial kneading extruder set at 120 ° C. The obtained kneaded product was cooled, coarsely pulverized with a cutter mill, and then finely pulverized using a pulverizer using a jet stream. The resulting finely pulverized product was classified using a multi-division classifier utilizing the Coanda effect to obtain a negatively chargeable magnetic toner having a weight average diameter of 6.8 μm. Toner 1 was obtained by adding 0.8 part by mass of negatively chargeable hydrophobic silica to 100 parts by mass of this toner with a Henschel mixer. Table 3 shows the THF insoluble content of toner 1, the peak molecular weight in the molecular weight distribution obtained by GPC measurement of the THF soluble component, the melt viscosity at 120 ° C., and the porosity determined from the tap density.
[0262]
The magnetic toner 1 was subjected to a fixing test, an offset test, a storage stability test, a development durability test, a pressure member stain, and an edge density thinness evaluation by the following methods.
[0263]
As a basic configuration of the heat fixing device used in the experiment, the heater 11 having the configuration shown in FIG. 5 was used. In other words, the substrate 11a made of AlN was used, and the energized heat generating resistance layer 11b was formed on the surface of the heater substrate 11a opposite to the surface on which the fixing nip N was formed. As this energization heat generation resistance layer, a paste formed by mixing a mixture of an Ag / Pd conductive agent and a phosphate glass as a matrix component with an organic solvent, a binder, a dispersant and the like is screen-printed at 600 ° C. What was baked was used. Further, a sliding layer 11e made of polyimide having good slidability was formed on the surface of the AlN heater substrate 11a on the fixing nip portion N side by screen printing with a thickness of 10 μm.
[0264]
Also, as the metal sleeve 13 (see FIG. 2), a cylindrical stainless steel having an inner diameter of 30 mm and a thickness of 50 μm is applied by dipping a primer layer of 5 μm and PFA resin by 10 μm to form a cylindrical shape having an outer diameter of 30.13 mm. Was used. The surface roughness Rz of the inner surface of the metal sleeve 13 was 2 μm, and the surface roughness Rz of the outer surface was 2 μm.
[0265]
Further, the pressure roller 20 (see FIG. 2) was formed by forming a silicone rubber layer with a thickness of 5 mm on an Al core metal 21 with a diameter of 20 mm, and further covering the outer layer with a PFA tube.
[0266]
[Fixability and offset test]
In the experiment, the recording material conveyance speed of the image forming apparatus is adjusted to be 200 mm / sec so that the temperature adjustment by the heating heater 11 can be arbitrarily set, and the heating heater 11 is applied to the energized heating resistor layer 11b. After 6 seconds from the start of energization, the recording material P on which an unfixed toner image was formed was inserted into the fixing nip portion N and checked for each item.
[0267]
In the fixing test, the temperature of the central portion of the metal sleeve is adjusted every 5 ° C. within a range of 110 to 220 ° C., and 75 g / m at each temperature.²An unfixed image is fixed using paper, and the obtained image is rubbed 5 times with sylbon paper with a load of 4.9 kPa, and the density reduction rate of the image density before and after the rubbing becomes 5% or less. The point was taken as the fixing temperature. The lower this temperature, the better the low-temperature fixability.
[0268]
Regarding the high temperature offset property, the temperature at which the stain due to the offset phenomenon occurred on the image in the fixing test was visually confirmed. The higher this temperature, the better the high temperature offset property.
[0269]
Regarding the low temperature offset property, the temperature at which the stain due to the offset phenomenon occurred on the image in the fixing test was visually confirmed. The lower this temperature, the more excellent the low temperature offset property.
[0270]
[Durability development test]
A commercially available laser beam printer LaserJet 4000 (A4, 16 sheets / minute: manufactured by Hewlett Packard) was modified to incorporate a fixing device using the above fixing method, and an A4 size image area ratio of 5% was used. / M²Each of the transfer papers was subjected to a 5000 image printing test in a low temperature and low humidity (15 ° C., 10% RH) environment and a high temperature and high humidity (32.5 ° C., 80% RH) environment. Was measured. For low-temperature and low-humidity environments, the solid white image fog was also measured. The image density was calculated by measuring the reflection density with a Macbeth densitometer (manufactured by Macbeth) using an SPI filter, and calculating an average of five points. The fog is measured using a reflection densitometer (reflectometer model TC-6DS manufactured by Tokyo Denshoku Co., Ltd.), and is obtained by subtracting the reflection average density of the transfer material before image formation from the worst value of solid white area reflection density. The amount.
[0271]
[Preservation]
10 g of toner was placed in a 50 ml polycup and placed in a thermostatic bath at 50 ° C. for 5 days, and the degree of toner blocking at that time was evaluated.
[0272]
A: Toner fluidity does not change
B: Fluidity deteriorates but recovers immediately
C: There is an aggregate
D: Blocking
[0273]
[Pressure member dirt]
75g / m using the modified machine used in the endurance development test²In a print mode in which 3 sheets of originals with an image area ratio of 5% are printed on A4 size transfer paper in a low-temperature and low-humidity environment and stopped for 10 minutes, an image output test of 1000 sheets is performed, and the fixing device is added after the test. The degree of dirt on the pressure member and whether dirt such as black spots appeared on the transfer paper were visually evaluated.
[0274]
A: There is no dirt on the pressure member.
B: Slight dirt on the pressure member, but no dirt on the transfer paper
C: 1 to 3 stains per sheet of transfer paper
D: 4 to 6 stains per sheet of transfer paper
E: 7 to 10 stains appear on each transfer sheet
F: The transfer paper is heavily soiled
[0275]
[Low end density]
Using an external fixing device of the above-mentioned fixing method used in the fixing property and offset test, a fixing temperature of 190 ° C., a process speed of 200 mm / sec, a pressing force of 78 N, and a nip of 6 mm are set, and 75 g / m.²A uniform solid black unfixed image is fixed using paper, and the average of the image density of 6 points in the 1 cm portion from both ends of the obtained image is defined as the edge density, and is subtracted from the average of the image density of 3 points in the center. The difference in density was evaluated as thin end density.
[0276]
The image density was measured with a Macbeth densitometer (manufactured by Macbeth) using an SPI filter. The smaller the density difference, the better the density uniformity.
[0277]
A: Density difference 0 or more and less than 0.02
B: Concentration difference 0.02 or more and less than 0.05
C: Concentration difference 0.05 or more and less than 0.10
D: Concentration difference 0.10 or more and less than 0.15
E: Concentration difference 0.15 or more and less than 0.20
F: Concentration difference 0.20 or more
[0278]
Table 4 shows the evaluation results of each test. As can be seen from Table 4, good fixing characteristics, durability characteristics, and storage stability were obtained, and there was no occurrence of pressure member contamination and low edge density.
[0279]
<Examples 2 to 10>
Toners 2 to 10 were obtained in the same manner as in Example 1 except that the binder resin and wax were changed as shown in Table 3 in Example 1. The obtained toners 2 to 10 were evaluated in the same manner as in Example 1. The evaluation results are shown in Table 4.
[0280]
<Example 11>
The negatively chargeable magnetic toner having a weight average diameter of 10.2 μm was obtained by changing the pulverization and classification conditions in the production of the toner of Example 1. Toner 11 was obtained by adding 0.6 parts by mass of negatively chargeable hydrophobic silica to 100 parts by mass of this toner with a Henschel mixer. The obtained toner 11 was evaluated in the same manner as in Example 1. The evaluation results are shown in Table 4.
[0281]
<Example 12>
The negatively chargeable magnetic toner having a weight average diameter of 4.1 μm was obtained by changing the pulverization and classification conditions in the production of the toner of Example 1. Toner 12 was obtained by adding 1.2 parts by mass of negatively chargeable hydrophobic silica to 100 parts by mass of this toner with a Henschel mixer. The obtained toner 12 was evaluated in the same manner as in Example 1. The evaluation results are shown in Table 4.
[0282]
<Comparative Examples 1-3>
Toners 13 to 15 were obtained in the same manner as in Example 1 except that the binder resin and wax were changed as shown in Table 3 in Example 1. The obtained toners 13 to 15 were evaluated in the same manner as in Example 1. The evaluation results are shown in Table 4.
[0283]
[Table 3]

[0284]
[Table 4]

[0285]
【The invention's effect】
According to the present invention, there is provided a toner and an image forming method that are excellent in developability, low-temperature fixability, high-temperature offset property, and low-temperature offset property, and that exhibit particularly excellent performance in preventing the occurrence of pressure member contamination and edge density thinness. Can be provided.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram showing an example of an image forming apparatus of the present invention.
FIG. 2 is a schematic configuration diagram of a heat fixing device 6 (cross-sectional model diagram).
FIG. 3 is a partially enlarged view of the vicinity of the fixing nip portion of FIG.
4 is a longitudinal sectional view of the heat fixing device (schematic sectional view taken along line II in FIG. 2).
FIG. 5 is a partial schematic view showing another embodiment of a heater for heating.
FIG. 6 is an explanatory diagram of deep drawing that is a metal sleeve manufacturing method.
FIG. 7 is a diagram illustrating the shape of a metal sleeve that is being manufactured.
FIGS. 8A and 8B are explanatory diagrams of ironing processing that is a method of manufacturing a metal sleeve, and FIG. 8C is an explanatory diagram of metal sleeve shape at the end of ironing processing.
9 is a schematic cross-sectional view of a heat fixing apparatus in which a potential difference is provided between the metal sleeve 13 and the pressure roller 20. FIG.
FIG. 10 is a schematic configuration diagram of a conventional heat fixing device (fixing roller type).
FIG. 11 is a schematic configuration diagram of a conventional heat fixing device (fixing film type).
FIG. 12 DSC measurement diagram of wax A
[Explanation of symbols]
11 Heating heater
12 Insulated stay holder
13 Metal sleeve
14 Temperature sensing element
20 Pressure member
24 Bias applying means

Claims (12)

An image forming method for forming an image on a recording material by forming an unfixed toner image made of toner on the recording material and fixing the toner image on the recording material,
A fixing step of fixing the unfixed toner image on the recording material by fixing means;
It said fixing means includes a heating metal sleeve for the flexible cylindrical metal tube and the base layer, and a heating member disposed in contact with the inner surface of the heating metal sleeve heating the heating metallic sleeve And a rotatable pressure member that is in pressure contact with the heating member via the heating metal sleeve and has a rotation axis parallel to the heating metal sleeve ,
The surface roughness Rz in the longitudinal direction of the metal sleeve for heating is 3 μm or less, the surface roughness Rz ′ in the circumferential direction is 3 μm or less, and the relationship between Rz and Rz ′ is Rz> Rz ′,
The fixing nip portion is formed by the metal sleeve for heating and the pressure member being pressed against each other ,
The metal sleeve for heating rotates in conjunction with the rotation of the pressure member, and passes the recording material on which the unfixed toner image is formed through the fixing nip portion, whereby the unfixed toner image is transferred to the recording material. Let it settle on top ,
The toner constituting the unfixed toner image contains at least a binder resin and a wax,
In the chromatogram obtained by gel permeation chromatography of the tetrahydrofuran soluble part of the toner, the toner has a main peak in the region of molecular weight of 3.0 × 10 ^{3 to} 3.0 × 10 ⁴ and has a molecular weight of 1.0 × 10 ^5. Have sub-peaks or shoulders in the region of ~ 3.0 x 10 ⁶ ;
The peak top temperature of the maximum endothermic peak in the endothermic peak at the time of temperature rise measured by differential thermal analysis of the wax is 70 to 120 ° C,
An image forming method, wherein the porosity determined from the tap density of the toner is 0.4 to 0.7. The image forming method according to claim 1, wherein the wax has a melt viscosity at 120 ° C. measured with an E-type viscometer of 100 mPa · s or less. The image forming method according to claim 1, wherein the wax has a melt viscosity of 1 to 50 mPa · s at 120 ° C. as measured with an E-type viscometer. The image forming method according to claim 1, wherein the viscosity at 120 ° C. is 1 × 10 ^{3 to} 5 × 10 ⁵ Pa · s. The image according to any one of claims 1 to 4, wherein a peak top temperature of a maximum endothermic peak in an endothermic peak at the time of temperature rise measured by differential thermal analysis of the wax is 70 to 100 ° C. Forming method . The image according to any one of claims 1 to 4, wherein a peak top temperature of a maximum endothermic peak in an endothermic peak at the time of temperature rise measured by differential thermal analysis of the wax is 70 to 80 ° C. Forming method . The image formation according to any one of claims 1 to 6, wherein a peak half-value width of a maximum endothermic peak in the endothermic peak at the time of temperature rise measured by differential thermal analysis of the wax is 12 ° C or less. Way . The image formation according to any one of claims 1 to 6, wherein a peak half-value width of a maximum endothermic peak at an endothermic peak at a temperature rise measured by differential thermal analysis of the wax is 8 ° C or less. Way . The start point onset temperature in the endothermic peak at the time of temperature rise measured by differential thermal analysis of the wax is 50 ° C or higher, and the end point onset temperature is 100 ° C or lower. The image forming method according to claim 1. The start point onset temperature in the endothermic peak at the time of temperature rise measured by differential thermal analysis of the wax is 60 ° C or higher, and the end point onset temperature is 90 ° C or lower. The image forming method according to claim 1. 11. The image forming method according to claim 1, wherein the porosity determined from the tap density is 0.45 to 0.65. The image forming method according to claim 1, wherein an acid value of the binder resin is 0.1 to 100 mg KOH / g.

Images