JP4318378B2 - Electrostatic latent image developing toner, image forming method and image forming apparatus - Google Patents

Description

【００６６】
【化２】

【００６７】
添加量は、トナー全体の１〜３０質量％、好ましくは２〜２０質量％、さらに好ましくは３〜１５質量％である。
【００６８】
本発明のトナーは、モノマー中に離型剤を溶解させたものを水中に分散し、重合させ、樹脂粒子中にエレクトール等の離型剤を内包させた粒子を形成させ、着色剤粒子ととも塩析／融着することでトナーとする。
【００６９】
前記した如く、トナー画像はセミグロスを基本とするため、これを作るに好適なトナー結着樹脂の分子量分布としては、ＧＰＣによる分子量測定において、１００，０００〜１，０００，０００の領域にピークもしくは肩を有する高分子量成分と、１，０００〜２０，０００の領域にピークもしくは肩を有する低分子量成分の両成分を含有するのがよい。
【００７０】
本発明におけるＧＰＣ（ゲルパーミエーションクロマトグラフィー）による樹脂の分子量測定方法は、ＴＨＦ（テトロヒドロフラン）を溶媒としてＧＰＣ測定した。すなわち、測定試料０．５〜５ｍｇ、より具体的には１ｍｇに対してＴＨＦを１ｍｌ加え、室温にてマグネチックスターラーなどを用いて撹拌を行い、充分に溶解させる。ついで、ポアサイズ０．４５〜０．５０μｍのメンブランフィルターで処理した後に、ＧＰＣへ注入する。ＧＰＣの測定条件は、４０℃にてカラムを安定化させ、ＴＨＦを毎分１ｍｌの流速で流し、１ｍｇ／ｍｌの濃度の試料を約１００μｌ注入して測定する。カラムは、市販のポリスチレンジェルカラムを組み合わせて使用することが好ましい。
【００７１】
例えば、昭和電工社製のＳｈｏｄｅｘ ＧＰＣ ＫＦ−８０１、８０２、８０３、８０４、８０５、８０６、８０７の組合せや、東ソー社製のＴＳＫｇｅｌＧ１０００Ｈ、Ｇ２０００Ｈ、Ｇ３０００Ｈ、Ｇ４０００Ｈ、Ｇ５０００Ｈ、Ｇ６０００Ｈ、Ｇ７０００Ｈ、ＴＳＫ ｇｕａｒｄ ｃｏｌｕｍｎの組合せなどを挙げることができる。また、検出器としては、屈折率検出器（ＩＲ検出器）、あるいはＵＶ検出器を用いるとよい。試料の分子量測定では、試料の有する分子量分布を単分散のポリスチレン標準粒子を用いて作成した検量線を用いて算出する。検量線作成用のポリスチレンとしては１０点程度用いるとよい。
【００７２】
本発明の如く、塩析／融着したトナーはトナー製造時から表面に凹凸がある形状を有しており、さらに、水系媒体中で融着するため、粒子間の形状や表面性に差がでることも少なく、結果として表面性が均一となりやすいためにトナー間での定着性に差異を生じにくく、定着性も良好に保つことができるものである。
【００７３】
水系媒体中で融着させる方法として、例えば特開昭６３−１８６２５３号公報、同６３−２８２７４９号公報、特開平７−１４６５８３号公報等に記載されている方法や、樹脂粒子を塩析／融着させて形成する方法等をあげることができる。
【００７４】
本発明のトナーの製造に用いる離型剤を内包した樹脂粒子は質量平均粒径５０〜２０００ｎｍが好ましく、これらの樹脂粒子は乳化重合、懸濁重合、シード重合等のいずれの造粒重合法によっても良い。
【００７５】
以下、樹脂粒子の材料及び製造方法の例について記述する。
《材料》
単量体
重合性単量体としては、ラジカル重合性単量体を必須の構成成分とし、必要に応じて架橋剤を使用することができる。また、以下の酸性基を有するラジカル重合性単量体または塩基性基を有するラジカル重合性単量体を少なくとも１種類含有させることが好ましい。
【００７６】
（１）ラジカル重合性単量体
ラジカル重合性単量体成分としては、特に限定されるものではなく従来公知のラジカル重合性単量体を用いることができる。また、要求される特性を満たすように、１種または２種以上のものを組み合わせて用いることができる。
【００７７】
具体的には、芳香族系ビニル単量体、（メタ）アクリル酸エステル系単量体、ビニルエステル系単量体、ビニルエーテル系単量体、モノオレフィン系単量体、ジオレフィン系単量体、ハロゲン化オレフィン系単量体等を用いることができる。
【００７８】
芳香族系ビニル単量体としては、例えば、スチレン、ｏ−メチルスチレン、ｍ−メチルスチレン、ｐ−メチルスチレン、ｐ−メトキシスチレン、ｐ−フェニルスチレン、ｐ−クロロスチレン、ｐ−エチルスチレン、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、２，４−ジメチルスチレン、３，４−ジクロロスチレン等のスチレン系単量体およびその誘導体が挙げられる。
【００７９】
（メタ）アクリル酸エステル系単量体としては、アクリル酸メチル、アクリル酸エチル、アクリル酸ブチル、アクリル酸−２−エチルヘキシル、アクリル酸シクロヘキシル、アクリル酸フェニル、メタクリル酸メチル、メタクリル酸エチル、メタクリル酸ブチル、メタクリル酸ヘキシル、メタクリル酸−２−エチルヘキシル、β−ヒドロキシアクリル酸エチル、γ−アミノアクリル酸プロピル、メタクリル酸ステアリル、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等が挙げられる。
【００８０】
ビニルエステル系単量体としては、酢酸ビニル、プロピオン酸ビニル、ベンゾエ酸ビニル等が挙げられる。
【００８１】
ビニルエーテル系単量体としては、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、ビニルフェニルエーテル等が挙げられる。
【００８２】
モノオレフィン系単量体としては、エチレン、プロピレン、イソブチレン、１−ブテン、１−ペンテン、４−メチル−１−ペンテン等が挙げられる。
【００８３】
ジオレフィン系単量体としては、ブタジエン、イソプレン、クロロプレン等が挙げられる。
【００８４】
ハロゲン化オレフィン系単量体としては、塩化ビニル、塩化ビニリデン、臭化ビニル等が挙げられる。
【００８５】
（２）架橋剤
架橋剤としては、トナーの特性を改良するためにラジカル重合性架橋剤を添加しても良い。ラジカル重合性架橋剤としては、ジビニルベンゼン、ジビニルナフタレン、ジビニルエーテル、ジエチレングリコールメタクリレート、エチレングリコールジメタクリレート、ポリエチレングリコールジメタクリレート、フタル酸ジアリル等の不飽和結合を２個以上有するものが挙げられる。
【００８６】
（３）酸性基を有するラジカル重合性単量体または塩基性基を有するラジカル重合性単量体
酸性基を有するラジカル重合性単量体または塩基性基を有するラジカル重合性単量体としては、例えば、カルボキシル基含有単量体、スルホン酸基含有単量体、第１級アミン、第２級アミン、第３級アミン、第４級アンモニウム塩等のアミン系の化合物を用いることができる。
【００８７】
酸性基を有するラジカル重合性単量体としては、カルボン酸基含有単量体として、アクリル酸、メタクリル酸、フマール酸、マレイン酸、イタコン酸、ケイ皮酸、マレイン酸モノブチルエステル、マレイン酸モノオクチルエステル等が挙げられる。
【００８８】
スルホン酸基含有単量体としては、スチレンスルホン酸、アリルスルホコハク酸、アリルスルホコハク酸オクチル等が挙げられる。
【００８９】
これらは、ナトリウムやカリウム等のアルカリ金属塩あるいはカルシウムなどのアルカリ土類金属塩の構造であってもよい。
【００９０】
塩基性基を有するラジカル重合性単量体としては、アミン系の化合物があげられ、ジメチルアミノエチルアクリレート、ジメチルアミノエチルメタクリレート、ジエチルアミノエチルアクリレート、ジエチルアミノエチルメタクリレート、および上記４化合物の４級アンモニウム塩、３−ジメチルアミノフェニルアクリレート、２−ヒドロキシ−３−メタクリルオキシプロピルトリメチルアンモニウム塩、アクリルアミド、Ｎ−ブチルアクリルアミド、Ｎ，Ｎ−ジブチルアクリルアミド、ピペリジルアクリルアミド、メタクリルアミド、Ｎ−ブチルメタクリルアミド、Ｎ−オクタデシルアクリルアミド；ビニルピリジン、ビニルピロリドン；ビニルＮ−メチルピリジニウムクロリド、ビニルＮ-エチルピリジニウムクロリド、Ｎ，Ｎ−ジアリルメチルアンモニウムクロリド、Ｎ，Ｎ−ジアリルエチルアンモニウムクロリド等を挙げることができる。
【００９１】
本発明に用いられるラジカル重合性単量体としては、酸性基を有するラジカル重合性単量体または塩基性基を有するラジカル重合性単量体が単量体全体の０．１〜１５質量％使用することが好ましく、ラジカル重合性架橋剤はその特性にもよるが、全ラジカル重合性単量体に対して０．１〜１０質量％の範囲で使用することが好ましい。
【００９２】
連鎖移動剤
分子量を調製することを目的として、一般的に用いられる連鎖移動剤を用いることが可能である。
【００９３】
連鎖移動剤としては、特に限定されるものではなく例えばオクチルメルカプタン、ドデシルメルカプタン、ｔｅｒｔ−ドデシルメルカプタン等のメルカプタン、四臭化炭素およびスチレンダイマー等が使用される。
【００９４】
重合開始剤
本発明に用いられるラジカル重合開始剤は水溶性であれば適宜使用が可能である。例えば過硫酸塩（過硫酸カリウム、過硫酸アンモニウム等）、アゾ系化合物（４，４′−アゾビス４−シアノ吉草酸及びその塩、２，２′−アゾビス（２−アミジノプロパン）塩等）、パーオキシド化合物等が挙げられる。
【００９５】
更に上記ラジカル性重合開始剤は、必要に応じて還元剤と組み合わせレドックス系開始剤とする事が可能である。レドックス系開始剤を用いる事で、重合活性が上昇し重合温度の低下が図れ、更に重合時間の短縮が期待できる。
【００９６】
重合温度は、重合開始剤の最低ラジカル生成温度以上であればどの温度を選択しても良いが例えば５０℃から９０℃の範囲が用いられる。但し、常温開始の重合開始剤、例えば過酸化水素−還元剤（アスコルビン酸等）の組み合わせを用いる事で、室温またはそれ以上の温度で重合する事も可能である。
【００９７】
界面活性剤
前述のラジカル重合性単量体を使用して重合を行うためには、界面活性剤を使用して水系媒体中に油滴分散を行う必要がある。この際に使用することのできる界面活性剤としては特に限定されるものでは無いが、下記のイオン性界面活性剤を好適なものの例として挙げることができる。
【００９８】
イオン性界面活性剤としては、スルホン酸塩（ドデシルベンゼンスルホン酸ナトリウム、アリールアルキルポリエーテルスルホン酸ナトリウム、３，３−ジスルホンジフェニル尿素−４，４−ジアゾ−ビス−アミノ−８−ナフトール−６−スルホン酸ナトリウム、オルト−カルボキシベンゼン−アゾ−ジメチルアニリン、２，２，５，５−テトラメチル−トリフェニルメタン−４，４−ジアゾ−ビス−β−ナフトール−６−スルホン酸ナトリウム等）、硫酸エステル塩（ドデシル硫酸ナトリウム、テトラデシル硫酸ナトリウム、ペンタデシル硫酸ナトリウム、オクチル硫酸ナトリウム等）、脂肪酸塩（オレイン酸ナトリウム、ラウリン酸ナトリウム、カプリン酸ナトリウム、カプリル酸ナトリウム、カプロン酸ナトリウム、ステアリン酸カリウム、オレイン酸カルシウム等）が挙げられる。
【００９９】
また、ノニオン性界面活性剤も使用することができる。具体的には、ポリエチレンオキサイド、ポリプロピレンオキサイド、ポリプロピレンオキサイドとポリエチレンオキサイドの組み合わせ、ポリエチレングリコールと高級脂肪酸とのエステル、アルキルフェノールポリエチレンオキサイド、高級脂肪酸とポリエチレングリコールのエステル、高級脂肪酸とポリプロピレンオキサイドのエステル、ソルビタンエステル等をあげることができる。
【０１００】
本発明において、これらは、主に乳化重合時の乳化剤として使用されるが、他の工程または使用目的で使用してもよい。
【０１０１】
着色剤
着色剤としては無機顔料、有機顔料、染料を挙げることができる。
【０１０２】
無機顔料としては、従来公知のものを用いることができる。具体的な無機顔料を以下に例示する。
【０１０３】
黒色の顔料としては、例えば、ファーネスブラック、チャンネルブラック、アセチレンブラック、サーマルブラック、ランプブラック等のカーボンブラック、更にマグネタイト、フェライト等の磁性粉も用いられる。
【０１０４】
これらの無機顔料は所望に応じて単独または複数を選択併用する事が可能である。また顔料の添加量は重合体に対して２〜２０質量％であり、好ましくは３〜１５質量％が選択される。
【０１０５】
磁性トナーとして使用する際には、前述のマグネタイトを添加することができる。この場合には所定の磁気特性を付与する観点から、トナー中に２０〜６０質量％添加することが好ましい。
【０１０６】
有機顔料及び染料としても従来公知のものを用いることができる。具体的な有機顔料及び染料を以下に例示する。
【０１０７】
マゼンタまたはレッド用の顔料としては、Ｃ．Ｉ．ピグメントレッド２、Ｃ．Ｉ．ピグメントレッド３、Ｃ．Ｉ．ピグメントレッド５、Ｃ．Ｉ．ピグメントレッド６、Ｃ．Ｉ．ピグメントレッド７、Ｃ．Ｉ．ピグメントレッド１５、Ｃ．Ｉ．ピグメントレッド１６、Ｃ．Ｉ．ピグメントレッド４８：１、Ｃ．Ｉ．ピグメントレッド５３：１、Ｃ．Ｉ．ピグメントレッド５７：１、Ｃ．Ｉ．ピグメントレッド１２２、Ｃ．Ｉ．ピグメントレッド１２３、Ｃ．Ｉ．ピグメントレッド１３９、Ｃ．Ｉ．ピグメントレッド１４４、Ｃ．Ｉ．ピグメントレッド１４９、Ｃ．Ｉ．ピグメントレッド１６６、Ｃ．Ｉ．ピグメントレッド１７７、Ｃ．Ｉ．ピグメントレッド１７８、Ｃ．Ｉ．ピグメントレッド２２２等が挙げられる。
【０１０８】
オレンジまたはイエロー用の顔料としては、Ｃ．Ｉ．ピグメントオレンジ３１、Ｃ．Ｉ．ピグメントオレンジ４３、Ｃ．Ｉ．ピグメントイエロー１２、Ｃ．Ｉ．ピグメントイエロー１３、Ｃ．Ｉ．ピグメントイエロー１４、Ｃ．Ｉ．ピグメントイエロー１５、Ｃ．Ｉ．ピグメントイエロー１７、Ｃ．Ｉ．ピグメントイエロー９３、Ｃ．Ｉ．ピグメントイエロー９４、Ｃ．Ｉ．ピグメントイエロー１３８、Ｃ．Ｉ．ピグメントイエロー１８０、Ｃ．Ｉ．ピグメントイエロー１８５、Ｃ．Ｉ．ピグメントイエロー１５５、Ｃ．Ｉ．ピグメントイエロー１５６、等が挙げられる。
【０１０９】
グリーンまたはシアン用の顔料としては、Ｃ．Ｉ．ピグメントブルー１５、Ｃ．Ｉ．ピグメントブルー１５：２、Ｃ．Ｉ．ピグメントブルー１５：３、Ｃ．Ｉ．ピグメントブルー１６、Ｃ．Ｉ．ピグメントブルー６０、Ｃ．Ｉ．ピグメントグリーン７等が挙げられる。
【０１１０】
また、染料としてはＣ．Ｉ．ソルベントレッド１、同４９、同５２、同５８、同６３、同１１１、同１２２、Ｃ．Ｉ．ソルベントイエロー１９、同４４、同７７、同７９、同８１、同８２、同９３、同９８、同１０３、同１０４、同１１２、同１６２、Ｃ．Ｉ．ソルベントブルー２５、同３６、同６０、同７０、同９３、同９５等を用いる事ができ、またこれらの混合物も用いる事ができる。
【０１１１】
これらの有機顔料及び染料は所望に応じて単独または複数を選択併用する事が可能である。また顔料の添加量は重合体に対して２〜２０質量％であり、好ましくは３〜１５質量％が選択される。
【０１１２】
着色剤は表面改質して使用することもできる。その表面改質剤としては、従来公知のものを使用することができ、具体的にはシランカップリング剤、チタンカップリング剤、アルミニウムカップリング剤等が好ましく用いることができる。
【０１１３】
《製造工程》
本発明の重合トナーの製造工程は、離型剤を溶解したモノマー溶液を水系媒体中に分散し、ついで重合法により離型剤を内包した樹脂粒子を調製する工程、前記樹脂粒子分散液を用いて水系媒体中で樹脂粒子を融着させる工程、得られた粒子を水系媒体中より濾過し界面活性剤などを除去する洗浄工程、得られた粒子を乾燥させる工程、さらに乾燥させて得られた粒子に外添剤などを添加する外添剤添加工程などから構成される。ここで樹脂粒子としては着色された粒子であってもよい。また、非着色粒子を樹脂粒子として使用することもできる、この場合には、樹脂粒子の分散液に着色剤粒子分散液などを添加した後に水系媒体中で融着させることで着色粒子とすることができる。
【０１１４】
特に、融着の方法としては、重合工程によって生成された樹脂粒子を用いて塩析／融着する方法が好ましい。また、非着色の樹脂粒子を使用した場合には、樹脂粒子と着色剤粒子を水系媒体中で塩析／融着させることができる。
【０１１５】
また、着色剤や離型剤に限らず、トナーの構成要素である荷電制御剤等も本工程で粒子として添加することができる。
【０１１６】
なお、ここで水系媒体とは主成分として水からなるもので、水の含有量が５０質量％以上であるものを示す。水以外のものとしては、水に溶解する有機溶媒を挙げることができ、例えば、メタノール、エタノール、イソプロパノール、ブタノール、アセトン、メチルエチルケトン、テトラヒドロフランなどをあげることができる。好ましくは樹脂を溶解しない有機溶媒である、メタノール、エタノール、イソプロパノール、ブタノールのようなアルコール系有機溶媒が特に好ましい。
【０１１７】
本発明での好ましい重合法としては、モノマー中に離型剤を溶解したモノマー溶液を臨界ミセル濃度以下の界面活性剤を溶解させた水系媒体中に機械的エネルギーによって油滴分散させた分散液に、水溶性重合開始剤を加え、ラジカル重合させる方法をあげることができる。この場合、モノマー中に油溶性の重合開始剤を加えて使用してもよい。
【０１１８】
この油滴分散を行うための分散機としては特に限定されるものでは無いが、例えばクレアミックス、超音波分散機、機械式ホモジナイザー、マントンゴーリンや圧力式ホモジナイザー等をあげることができる。
【０１１９】
着色剤自体は表面改質して使用してもよい。着色剤の表面改質法は、溶媒中に着色剤を分散し、その中に表面改質剤を添加した後昇温し反応を行う。反応終了後、ろ過し同一の溶媒で洗浄ろ過を繰り返し乾燥させ表面改質剤で処理された顔料を得る。
【０１２０】
着色剤粒子は着色剤を水系媒体中に分散して調製される方法がある。この分散は、水中で界面活性剤濃度を臨界ミセル濃度（ＣＭＣ）以上にした状態で行われる。
【０１２１】
顔料分散時の分散機は特に限定されないが、好ましくはクレアミックス、超音波分散機、機械的ホモジナイザー、マントンゴーリンや圧力式ホモジナイザー等の加圧分散機、サンドグラインダー、ゲッツマンミルやダイヤモンドファインミル等の媒体型分散機が挙げられる。
【０１２２】
ここで使用される界面活性剤は、前述の界面活性剤を使用することができる。
塩析／融着を行う工程は、樹脂粒子及び着色剤粒子が存在している水中にアルカリ金属塩やアルカリ土類金属塩等からなる塩析剤を臨界凝集濃度以上の凝集剤として添加し、ついで樹脂粒子のガラス転移点以上に加熱することで塩析を進行させると同時に融着を行う工程である。
【０１２３】
ここで、塩析剤であるアルカリ金属塩及びアルカリ土類金属塩は、アルカリ金属として、リチウム、カリウム、ナトリウム等が挙げられ、アルカリ土類金属として、マグネシウム、カルシウム、ストロンチウム、バリウムなどが挙げられ、好ましくはカリウム、ナトリウム、マグネシウム、カルシウム、バリウムが挙げられる。また塩を構成するものとしては、塩素塩、臭素塩、沃素塩、炭酸塩、硫酸塩等が挙げられる。
【０１２４】
本発明の融着を塩析／融着で行う場合、塩析剤を添加した後に放置する時間をできるだけ短くすることが好ましい。この理由として明確では無いが、塩析した後の放置時間によって、粒子の凝集状態が変動し、粒径分布が不安定になったり、融着させたトナーの表面性が変動したりする問題が発生する。この塩析剤を添加する温度は特に限定されない。
【０１２５】
また、本発明では、樹脂粒子の分散液をできるだけ速やかに昇温し、樹脂粒子のガラス転移温度以上に加熱する方法を使用することが好ましい。この昇温までの時間としては３０分未満、好ましくは１０分未満である。さらに、昇温を速やかに行う必要があるが、昇温速度としては、１℃／分以上が好ましい。上限としては特に明確では無いが、急速な塩析／融着の進行により粗大粒子の発生を抑制する観点で、１５℃／分以下が好ましい。特に好ましい形態としては、塩析／融着をガラス転移温度以上になった時点でも継続して進行させる方法をあげることができる。この方法とすることで、粒子の成長とともに融着が効果的に進行させることができ、最終的なトナーとしての耐久性を向上させることができる。
【０１２６】
ここで、本発明の融着されて得られたトナーの粒径は、体積平均粒径で３〜９μｍである。これらのトナーの体積平均粒径は、コールターカウンターＴＡ−II、コールターマルチサイザー、ＳＬＡＤ１１００（島津製作所社製レーザー回折式粒径測定装置）等を用いて測定することができる。コールターカウンターＴＡ−II及びコールターマルチサイザーではアパーチャー径＝１００μｍのアパーチャーを用いて２．０〜４０μｍの範囲における粒径分布を用いて測定されたものを示す。
【０１２７】
さらに、トナーとしては、３．０μｍ以下の微粉トナー量が個数分布で全体の２０個数％以下、さらに好ましくは２．０μｍ以下の微粉トナー量が１０個数％以下であるのがよい。この微粉トナー量は大塚電子社製・電気泳動光散乱光度計ＥＬＳ−８００を用いて測定することができる。この範囲に粒径分布を調製するためには、塩析／融着段階での温度制御を狭くすることがよい。具体的にはできるだけすばやく昇温する、すなわち、昇温温度を早くすることである。この条件としては、前述の条件に示したものであり、昇温までの時間としては３０分未満、好ましくは１０分未満、さらに、昇温速度としては、１〜１５℃／分が好ましい。
【０１２８】
又、融着によって得られたトナーの形状は、下記式で示される形状係数の平均値（平均円形度）が０．９３０〜０．９８０、好ましくは０．９４０〜０．９７５である。
【０１２９】
形状係数＝（円相当径から求めた円の周囲長）／（粒子投影像の周囲長）
形状係数の分布がシャープであることが好ましく、円形度の標準偏差は０．１０以下がよく、下記式で算出されるＣＶ値は２０％未満が好ましく、さらに１０％未満が好ましい。
【０１３０】
ＣＶ値＝（円形度の標準偏差）／（平均円形度）×１００
この平均円形度を０．９３０〜０．９８０とすることで、トナーが有する形状をある程度不定形化することができ、熱の伝達を効率化することができ、定着性をより向上することができる。すなわち、平均円形度を０．９８０以下とすることで定着性を向上することができる。また、０．９３０以上の平均円形度とすることで、粒子の不定形度合いを抑制し、長期に亘る使用時のストレスによる粒子の破砕性を抑制することができる。
【０１３１】
さらに、形状係数の分布がシャープであることが好ましく、円形度の標準偏差は０．１０以下とすることで形状が揃ったトナーとすることができ、トナー間での定着性能差を少なくすることができるため、定着率の向上及びオフセット性の低減による定着装置の汚染防止効果がより発揮される。また、ＣＶ値も２０％未満とすることで、同様にシャープな形状分布とすることができ、定着性向上効果をより顕著に発揮することができる。
【０１３２】
なお、上記形状係数の測定方法は限定されるものではないが、例えばトナー粒子を電子顕微鏡で５００倍に拡大した写真を撮影し、画像解析装置を使用し、５００個のトナーについて円形度を測定し、その算術平均値を求めることで、平均円形度を算出することができる。また、簡便な測定方法としては、ＦＰＩＡ−１０００（東亜医用電子株式会社製）により測定することができる。
【０１３３】
トナー粒子は、着色剤、離型剤以外にトナー用材料として種々の機能を付与することのできる材料を加えてもよい。具体的には荷電制御剤等が挙げられる。これらの成分は前述の塩析／融着段階で樹脂粒子と着色剤粒子と同時に添加し、トナー中に包含する方法、樹脂粒子自体に添加する方法等種々の方法で添加することができる。
【０１３４】
荷電制御剤も同様に種々の公知のもので、且つ水中に分散することができるものを使用することができる。具体的には、ニグロシン系染料、ナフテン酸または高級脂肪酸の金属塩、アルコキシル化アミン、第４級アンモニウム塩化合物、アゾ系金属錯体、サリチル酸金属塩あるいはその金属錯体等が挙げられる。
【０１３５】
《外添剤》
本発明のトナーには、流動性、帯電性の改良およびクリーニング性の向上などの目的で、いわゆる外添剤を添加して使用することができる。これら外添剤としては特に限定されるものでは無く、種々の無機微粒子、有機微粒子及び滑剤を使用することができる。
【０１３６】
無機微粒子としては、従来公知のものを使用することができる。具体的には、シリカ、チタン、アルミナ微粒子等が好ましく用いることができる。これら無機微粒子としては疎水性のものが好ましい。具体的には、シリカ微粒子として、例えば日本アエロジル社製の市販品Ｒ−８０５、Ｒ−９７６、Ｒ−９７４、Ｒ−９７２、Ｒ−８１２、Ｒ−８０９、ヘキスト社製のＨＶＫ−２１５０、Ｈ−２００、キャボット社製の市販品ＴＳ−７２０、ＴＳ−５３０、ＴＳ−６１０、Ｈ−５、ＭＳ−５等が挙げられる。
【０１３７】
チタン微粒子としては、例えば、日本アエロジル社製の市販品Ｔ−８０５、Ｔ−６０４、テイカ社製の市販品ＭＴ−１００Ｓ、ＭＴ−１００Ｂ、ＭＴ−５００ＢＳ、ＭＴ−６００、ＭＴ−６００ＳＳ、ＪＡ−１、富士チタン社製の市販品ＴＡ−３００ＳＩ、ＴＡ−５００、ＴＡＦ−１３０、ＴＡＦ−５１０、ＴＡＦ−５１０Ｔ、出光興産社製の市販品ＩＴ−Ｓ、ＩＴ−ＯＡ、ＩＴ−ＯＢ、ＩＴ−ＯＣ等が挙げられる。
【０１３８】
アルミナ微粒子としては、例えば、日本アエロジル社製の市販品ＲＦＹ−Ｃ、Ｃ−６０４、石原産業社製の市販品ＴＴＯ−５５等が挙げられる。
【０１３９】
また、有機微粒子としては数平均一次粒子径が１０〜２０００ｎｍ程度の球形の有機微粒子を使用することができる。このものとしては、スチレンやメチルメタクリレートなどの単独重合体やこれらの共重合体を使用することができる。
【０１４０】
滑剤には、例えばステアリン酸の亜鉛、アルミニウム、銅、マグネシウム、カルシウム等の塩、オレイン酸の亜鉛、マンガン、鉄、銅、マグネシウム等の塩、パルミチン酸の亜鉛、銅、マグネシウム、カルシウム等の塩、リノール酸の亜鉛、カルシウム等の塩、リシノール酸の亜鉛、カルシウムなどの塩等の高級脂肪酸の金属塩が挙げられる。
【０１４１】
これら外添剤の添加量は、トナーに対して０．１〜５質量％が好ましい。
外添剤の添加方法としては、タービュラーミキサー、ヘンシェルミキサー、ナウターミキサー、Ｖ型混合機などの種々の公知の混合装置を使用することができる。
【０１４２】
《現像剤》
本発明のトナーは、一成分現像剤でも二成分現像剤として用いてもよい。
【０１４３】
一成分現像剤として用いる場合は、非磁性一成分現像剤があげられる。
又、キャリアと混合して二成分現像剤として用いることができる。この場合は、キャリアの磁性粒子として、鉄、フェライト、マグネタイト等の金属、それらの金属とアルミニウム、鉛等の金属との合金等の従来から公知の材料を用いることが出来る。特にフェライト粒子が好ましい。上記磁性粒子は、その体積平均粒径としては１５〜１００μｍ、より好ましくは２５〜８０μｍのものがよい。
【０１４４】
キャリアの体積平均粒径の測定は、代表的には湿式分散機を備えたレーザ回折式粒度分布測定装置「ヘロス（ＨＥＬＯＳ）」（シンパティック（ＳＹＭＰＡＴＥＣ）社製）により測定することができる。
【０１４５】
キャリアは、磁性粒子が更に樹脂により被覆されているもの、あるいは樹脂中に磁性粒子を分散させたいわゆる樹脂分散型キャリアが好ましい。コーティング用の樹脂組成としては、特に限定は無いが、例えば、オレフィン系樹脂、スチレン系樹脂、スチレン−アクリル系樹脂、シリコーン系樹脂、エステル系樹脂或いはフッ素含有重合体系樹脂等が用いられる。また、樹脂分散型キャリアを構成するための樹脂としては、特に限定されず公知のものを使用することができ、例えば、スチレン−アクリル系樹脂、ポリエステル樹脂、フッ素系樹脂、フェノール樹脂等を使用することができる。
【０１４６】
【実施例】
次に、本発明を実施例にて更に具体的に説明する。
【０１４７】
（ラテックス調製例１）
撹拌装置、温度センサー、冷却管、窒素導入装置を付けた５０００ｍｌのセパラブルフラスコに予めアニオン系活性剤（ドデシルベンゼンスルフォン酸ナトリウム：ＳＤＳ）７．０８ｇをイオン交換水（２７６０ｇ）に溶解させた溶液を添加する。窒素気流下２３０ｒｐｍの撹拌速度で撹拌しつつ、内温を８０℃に昇温させた。一方で例示化合物（１９）７２．０ｇをスチレン１１５．１ｇ、ｎ−ブチルアクリレート４２．０ｇ、メタクリル酸１０．９ｇからなるモノマーに加え、８０℃に加温し溶解させ、モノマー溶液を作製した。ここで循環経路を有する機械式分散機により上記の加熱溶液を混合分散させ、均一な分散粒子径を有する乳化粒子を作製した。ついで、重合開始剤（過硫酸カリウム：ＫＰＳ）０．８４ｇをイオン交換水２００ｇに溶解させた溶液を添加し８０℃にて３時間加熱、撹拌することでラテックス粒子を作製した。引き続いて更に重合開始剤（ＫＰＳ）７．７３ｇをイオン交換水２４０ｍｌに溶解させた溶液を添加し、１５分後、８０℃でスチレン３８３．６ｇ、ｎ−ブチルアクリレート１４０．０ｇ、メタクリル酸３６．４ｇ、ｔ−ドデシルメルカプタン１３．７ｇの混合液を１２６分かけて滴下した。滴下終了後６０分加熱撹拌させた後４０℃まで冷却しラテックス粒子を得た。
【０１４８】
このラテックス粒子をラテックス１とする。
（ラテックス調製例２）
ラテックス調製例１において、例示化合物（１９）の添加量を６０．０ｇとした他は同様にしてラテックスを得た。これをラテックス２とする。
【０１４９】
（ラテックス調製例３）
ラテックス調製例１において、例示化合物（１９）の添加量を９６．０ｇとした他は同様にしてラテックスを得た。これをラテックス３とする。
【０１５０】
（ラテックス調製例４）
ラテックス調製例１において、例示化合物（１９）の添加量を１２０．０ｇとした他は同様にしてラテックスを得た。これをラテックス４とする。
【０１５１】
（ラテックス調製例５）
ラテックス調製例１において、例示化合物（１９）の代わりに例示化合物（１８）を使用した他は同様にしてラテックスを得た。これをラテックス５とする。
【０１５２】
（ラテックス調製例６）
ラテックス調製例１において、例示化合物（１９）の代わりに例示化合物（１７）を使用した他は同様にしてラテックスを得た。これをラテックス６とする。
【０１５３】
（ラテックス調製例７）
ラテックス調製例１において、例示化合物（１９）の代わりに例示化合物（８）を使用し、添加量を１２０．０ｇとした他は同様にしてラテックスを得た。これをラテックス７とする。
【０１５４】
（ラテックス調製例８）
ラテックス調製例１において、高分子量体製造時（初期の重合時）に添加する過硫酸カリウムの添加量を０．４２ｇとした他は同様にしてラテックスを得た。これをラテックス８とする。
【０１５５】
（ラテックス調製例９）
ラテックス調製例１において、低分子量体製造時（二段目の重合時）に添加する過硫酸カリウムの添加量を９．２７６ｇとした他は同様にしてラテックスを得た。これをラテックス９とする。
【０１５６】
（ラテックス調製例１０）
ラテックス調製例１において、低分子量体製造時（二段目の重合時）に添加するｔ−ドデｓジルメルカプタンの添加量を１６．４４ｇとした他は同様にしてラテックスを得た。これをラテックス１０とする。
【０１５７】
（ラテックス調製例１１）
撹拌装置、温度センサー、冷却管、窒素導入装置を付けた５０００ｍｌのセパラブルフラスコに予めアニオン系活性剤（ドデシルベンゼンスルフォン酸ナトリウム：ＳＤＳ）８．４ｇをイオン交換水（２７６０ｇ）に溶解させた溶液を添加する。窒素気流下２３０ｒｐｍの撹拌速度で撹拌しつつ、内温を８０℃に昇温させた。一方で例示化合物（１９）８６．４ｇをスチレン１３８．１ｇ、ｎ−ブチルアクリレート５０．４ｇ、メタクリル酸１３．１ｇからなるモノマーに加え、８０℃に加温し溶解させ、モノマー溶液を作製した。ここで循環経路を有する機械式分散機により上記の加熱溶液を混合分散させ、均一な分散粒子径を有する乳化粒子を作製した。ついで、重合開始剤（過硫酸カリウム：ＫＰＳ）０．８４ｇをイオン交換水２００ｇに溶解させた溶液を添加し８０℃にて３時間加熱、撹拌することでラテックス粒子を作製した。引き続いて更に重合開始剤（ＫＰＳ）６．０ｇをイオン交換水２４０ｍｌに溶解させた溶液を添加し、１５分後、８０℃でスチレン３０６．９ｇ、ｎ−ブチルアクリレート１１２．０ｇ、メタクリル酸２９．１２ｇ、ｔ−ドデシルメルカプタン１０．９６ｇの混合液を１２０分かけて滴下した。滴下終了後６０分加熱撹拌させた後４０℃まで冷却しラテックス粒子を得た。
【０１５８】
このラテックス粒子をラテックス１１とする。
（ラテックス調製例１２）
撹拌装置、温度センサー、冷却管、窒素導入装置を付けた５０００ｍｌのセパラブルフラスコに予めアニオン系活性剤（ドデシルベンゼンスルフォン酸ナトリウム：ＳＤＳ）５．６ｇをイオン交換水（２７６０ｇ）に溶解させた溶液を添加する。窒素気流下２３０ｒｐｍの撹拌速度で撹拌しつつ、内温を８０℃に昇温させた。一方で例示化合物（１９）５７．６ｇをスチレン９２．１ｇ、ｎ−ブチルアクリレート３３．６ｇ、メタクリル酸８．７ｇからなるモノマーに加え、８０℃に加温し溶解させ、モノマー溶液を作製した。ここで循環経路を有する機械式分散機により上記の加熱溶液を混合分散させ、均一な分散粒子径を有する乳化粒子を作製した。ついで、重合開始剤（過硫酸カリウム：ＫＰＳ）０．６ｇをイオン交換水２００ｇに溶解させた溶液を添加し８０℃にて３時間加熱、撹拌することで目的とするラテックス粒子を作製した。引き続いて更に重合開始剤（ＫＰＳ）９．１ｇをイオン交換水２４０ｍｌに溶解させた溶液を添加し、１５分後、８０℃でスチレン４９８．７ｇ、ｎ−ブチルアクリレート１８２．０ｇ、メタクリル酸４７．３ｇ、ｔ−ドデシルメルカプタン１７．８ｇの混合液を１２０分かけて滴下した。滴下終了後６０分加熱撹拌させた後４０℃まで冷却しラテックス粒子を得た。
【０１５９】
このラテックス粒子をラテックス１２とする。
（トナー調製例）
着色粒子１Ｂｋの製造
ｎ−ドデシル硫酸ナトリウム＝９．２ｇをイオン交換水１６０ｍｌに撹拌溶解する。この液に、撹拌下、リーガル３３０Ｒ（キャボット社製カーボンブラック）２０ｇを徐々に加え、ついで、クレアミックスを用いて分散した。大塚電子社製の電気泳動光散乱光度計ＥＬＳ−８００を用いて、上記分散液の粒径を測定した結果、質量平均径で１１２ｎｍであった。この分散液を「着色剤分散液１」とする。
【０１６０】
前述の「ラテックス１」１２５０ｇとイオン交換水２０００ｍｌ及び「着色剤分散液１」を、温度センサー、冷却管、窒素導入装置、攪拌装置を付けた５リットルの四つ口フラスコに入れ撹拌する。３０℃に調製した後、この溶液に５ｍｏｌ／ｌの水酸化ナトリウム水溶液を加え、ｐＨを１０．０に調整した。ついで、塩化マグネシウム６水和物５２．６ｇをイオン交換水７２ｍｌに溶解した水溶液を攪拌下、３０℃にて１０分間で添加した。その後、３分間放置した後に、昇温を開始し、液温度９０℃まで６分で昇温する（昇温速度＝１０℃／分）。その状態で粒径をコールターカウンターＴＡ−IIにて測定し、体積平均粒径が６．５μｍになった時点で塩化ナトリウム１１５ｇをイオン交換水７００ｍｌに溶解した水溶液を添加し粒子成長を停止させ、さらに継続して液温度９０℃±２℃にて、６時間加熱撹拌し、塩析／融着させる。その後、６℃／ｍｉｎの条件で３０℃まで冷却し、塩酸を添加し、ｐＨを２．０に調整し、撹拌を停止した。生成した着色粒子を濾過し、イオン交換水で繰り返し洗浄し、その後、４０℃の温風で乾燥し、着色粒子を得た。以上のようにして得られた着色粒子を「着色粒子１Ｂｋ」とする。
【０１６１】
なお、「ラテックス１」を使用し、以下に示すごとくカーボンブラックをその他の着色剤に変更した他は同様にして「着色粒子１Ｙ」〜「着色粒子１Ｃ」を得た。これらを着色粒子１群「１Ｂｋ／１Ｙ／１Ｍ／１Ｃ」とする。
【０１６２】
着色粒子１Ｙ
カーボンブラックの代わりにＣ．Ｉ．ピグメントイエロー１８５を使用した他は同様にして着色粒子を得た。これを「着色粒子１Ｙ」とする。
【０１６３】
着色粒子１Ｍ
カーボンブラックの代わりにＣ．Ｉ．ピグメントレッド１２２を使用した他は同様にして着色粒子を得た。これを「着色粒子１Ｍ」とする。
【０１６４】
着色粒子１Ｃ
カーボンブラックの代わりにＣ．Ｉ．ピグメントブルー１５：３を使用した他は同様にして着色粒子を得た。これを「着色粒子１Ｃ」とする。
【０１６５】
着色粒子２群はラテックス２を使用し、以下ラテックス１２まで使用して全体として表１に示すごとく着色粒子１群「１Ｂｋ／１Ｙ／１Ｍ／１Ｃ」〜着色粒子１２群「１２Ｂｋ／１２Ｙ／１２Ｍ／１２Ｃ」を調製した。
【０１６６】
【表１】

【０１６７】
尚、以下に比較用着色粒子製造例を示す。
比較用着色粒子製造例１：懸濁重合法の例
比較用着色粒子１Ｂｋ
高速攪拌装置（ＴＫホモミキサー）を備えた４つ口フラスコにイオン交換水７１０質量部と０．１モル／リットルの燐酸三ナトリウム水溶液４５０質量部を加え、６５℃に加温し、回転数１２０００ｒｐｍの攪拌条件下に１．０モル／リットルの塩化カルシウム水溶液６８質量部を徐々に加え、コロイド状燐酸三カルシウムを含む分散液を含む水系分散媒体を調製した。ついで、スチレンモノマー１６５質量部、ｎ−ブチルアクリレート３５質量部にカーボンブラック（リーガル３３０Ｒ）１４質量部を加えサンドグラインダーで分散した分散液に例示化合物（１９）を６０質量部加え、８０℃にて溶解させた。この溶液に重合開始剤として、２，２′−アゾビス（２，４−ジメチルバレロニトリル）１０質量部を加えたものを前記水系分散媒体中に回転数１２０００ｒｐｍの攪拌条件下で徐々に加え、水中にモノマーを含む溶液を分散させた。ついで、通常の攪拌羽根にＴＫホモミキサーを交換し、窒素気流下、６５℃、２００ｒｐｍ攪拌条件下で１０時間重合反応を行った。重合反応終了時に塩酸を加え、分散安定剤である燐酸三カルシウムを除去し、濾過、洗浄乾燥し、着色粒子を調製した。このものを「比較用着色粒子１Ｂｋ」とする。
【０１６８】
比較用着色粒子１Ｙ
カーボンブラックの代わりにＣ．Ｉ．ピグメントイエロー１８５を使用した他は同様にして着色粒子を得た。これを「比較用着色粒子１Ｙ」とする。
【０１６９】
比較用着色粒子１Ｍ
カーボンブラックの代わりにＣ．Ｉ．ピグメントレッド１２２を使用した他は同様にして着色粒子を得た。これを「比較用着色粒子１Ｍ」とする。
【０１７０】
比較用着色粒子１Ｃ
カーボンブラックの代わりにＣ．Ｉ．ピグメントブルー１５：３を使用した他は同様にして着色粒子を得た。これを「比較用着色粒子１Ｃ」とする。
【０１７１】
比較用着色粒子製造例２：粉砕法の例
比較用着色粒子２Ｂｋ
スチレンアクリル樹脂 ：１００質量部
カーボンブラック（リーガル３３０Ｒ）： １０質量部
例示化合物（１９） ： １０質量部
上記組成をヘンシェルミキサーにて乾式混合した後に、二軸押し出し機にて溶融混練し、ついで機械式粉砕機で粉砕し、気流分級機で分級し、着色粒子をえた。このものを「比較用着色粒子２Ｂｋ」とする。
【０１７２】
比較用着色粒子２Ｙ
カーボンブラックの代わりにＣ．Ｉ．ピグメントイエロー１８５を使用した他は同様にして着色粒子を得た。これを「比較用着色粒子２Ｙ」とする。
【０１７３】
比較用着色粒子２Ｍ
カーボンブラックの代わりにＣ．Ｉ．ピグメントレッド１２２を使用した他は同様にして着色粒子を得た。これを「比較用着色粒子２Ｍ」とする。
【０１７４】
比較用着色粒子２Ｃ
カーボンブラックの代わりにＣ．Ｉ．ピグメントブルー１５：３を使用した他は同様にして着色粒子を得た。これを「比較用着色粒子２Ｃ」とする。
【０１７５】
これら着色粒子の円形度、その標準偏差およびＣＶ値と体積平均粒径等を下記一覧表に示す。
【０１７６】
【表２】

【０１７７】
【表３】

【０１７８】
上記円形度はＦＰＩＡ−１０００を使用し、試料分析量＝０．３μリットル、検出粒子数１５００〜５０００個の条件で測定したものである。
【０１７９】
ついで上記着色粒子１群「着色粒子１Ｂｋ／１Ｙ／１Ｍ／１Ｃ」〜着色粒子１２群「着色粒子１２Ｂｋ／１２Ｙ／１２Ｍ／１２Ｃ」にそれぞれ疎水性シリカ（数平均一次粒子径＝１２ｎｍ、疎水化度＝６８）を１質量％及び疎水性酸化チタン（数平均一次粒子径＝２０ｎｍ、疎水化度＝６３）添加し、ヘンシェルミキサーにより混合してトナーを得た。
【０１８０】
これらをトナー１群「トナー１Ｂｋ／１Ｙ／１Ｍ／１Ｃ」〜トナー１２群「トナー１２Ｂｋ／１２Ｙ／１２Ｍ／１２Ｃ」とする。又、同様にして比較トナー１群「比較トナー１Ｂｋ／１Ｙ／１Ｍ／１Ｃ」と比較トナー２群「比較トナー２Ｂｋ／２Ｙ／２Ｍ／２Ｃ」を作製した。
【０１８１】
なお、形状及び粒径等の物性に関しては着色粒子及びトナーのいずれも差異は無い。
【０１８２】
【表４】

【０１８３】
上記トナーの各々に対してシリコーン樹脂を被覆した体積平均粒径６０μｍのフェライトキャリアを混合し、トナー濃度が６％の現像剤を調製した。これらをトナーに対応して、「現像剤１Ｂｋ／１Ｙ／１Ｍ／１Ｃ」〜「現像剤１２Ｂｋ／１２Ｙ／１２Ｍ／１２Ｃ」及び「比較現像剤１Ｂｋ／１Ｙ／１Ｍ／１Ｃ」と「比較現像剤２Ｂｋ／２Ｙ／２Ｍ／２Ｃ」を作製した。
【０１８４】
ここで調製した現像剤を使用し、図１に示すデジタルカラー複写機を使用して評価を実施した。
【０１８５】
定着方式としては図３に示すごとき圧接方式の加熱定着装置を用いた。
具体的構成は下記の如くである。
【０１８６】
表面をスポンジ状シリコーンゴム（アスカーＣ硬度＝３０：厚み８ｍｍ）で被覆した内径３０ｍｍで全幅が３１０ｍｍの、ヒーターを中央部に内蔵した円柱状の厚み１．０ｍｍのアルミ合金を定着ローラ（上ローラ）として有し、表面が同様にスポンジ状シリコーンゴム（アスカーＣ硬度＝３０：厚み２ｍｍ）で構成された内径４０ｍｍの肉厚２．０ｍｍの鉄芯金を有する加圧ローラ（下ローラ）を有している。ニップ幅は５．８ｍｍとした。この定着装置を使用して、印字の線速を１８０ｍｍ／ｓｅｃに設定した。ニップ幅は６．６ｍｍである。なお、定着ローラは表面をＰＦＡのチューブ（５０μｍ）で被覆してある。
【０１８７】
また、定着装置のクリーニング機構としてポリジフェニルシリコーン（２０℃の粘度が１０Ｐａ・ｓのもの）を含浸したウェッブ方式の供給方式を使用した。
【０１８８】
定着の温度は上ローラの表面温度で制御し、１７５℃の設定温度とした。なお、シリコーンオイルの塗布量は、０．６ｍｇ／Ａ４とした。
【０１８９】
現像剤としては、先に記した現像剤１群「現像剤１Ｂｋ／１Ｙ／１Ｍ／１Ｃ」〜現像剤１２群「現像剤１２Ｂｋ／１２Ｙ／１２Ｍ／１２Ｃ」及び比較現像剤１群「比較現像剤１Ｂｋ／１Ｙ／１Ｍ／１Ｃ」と比較現像剤２群「比較現像剤２Ｂｋ／２Ｙ／２Ｍ／２Ｃ」の組み合わせで用い、それぞれを実施例１〜１２、比較例１及び２とした。
【０１９０】
〔特性評価〕
上記評価において、フルカラー画像（画素率＝５０％）の画像を形成し、グリーンの二次色のクロマを評価した。測定器は「マクベスカラーアイ」を使用し、光源視野ＡＳＴＭ−Ｄ６５ ２°、ＳＣＥモードで評価した。また、画像上の標準光沢度を測定した。
【０１９１】
【表５】

【０１９２】
本発明内の実施例１〜１２は、何れも特性がよいことがわかる。
【０１９３】
【発明の効果】
本発明により、タンデム方式を使用した画像形成方式で、長期に亘って安定した色再現性の高いカラー画像形成方法と画像形成装置、それに用いられる静電潜像現像用トナーを提供することが出来る。
【図面の簡単な説明】
【図１】カラー電子写真画像形成装置の一例を示す概略構成図。
【図２】画像形成部における現像手段（現像器又は現像装置）の断面図。
【図３】本発明において使用する定着装置（定着器）の一例を示す断面図。
【符号の説明】
ｌａ、ｌｂ、ｌｃ、ｌｄ 静電潜像担持体（電子写真感光体ドラム又は感光体ドラム）
２ａ、２ｂ、２ｃ、２ｄ 帯電器
６ 画像支持体
７ 定着部
１７ レーザビーム露光装置
２ｌａ、２ｌｂ、２ｌｃ、２ｌｄ 除電露光ランプ
２２ａ、２２ｂ、２２ｃ、２２ｄ 電位センサー
Ｐａ、Ｐｂ、Ｐｃ、Ｐｄ 画像形成部[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a multicolor image forming method, an image forming apparatus, and an electrostatic latent image developing toner used therefor.
[0002]
[Prior art]
As a method for forming a multicolor image, there is a method in which a latent image corresponding to a color is formed on one electrostatic latent image carrier, and a development / transfer process is repeated for each color to form a multicolor image. is there. However, in this method, the electrostatic latent image carrier needs to repeat the development / transfer process for the number of times of development of each color, and the image formation speed is slower than that of a single-color image, and is 1/4 or less for a full-color image. Become.
[0003]
Therefore, with this method, it is difficult to increase the full-color image formation speed.
[0004]
On the other hand, as a method capable of forming a full-color image at high speed, an electrostatic latent image carrier corresponding to each color is provided, and the image formed thereon is transferred onto the image support for each color, so that the full-color image is formed. There is a method called normal tandem system.
[0005]
In this method, since the latent image forming process and the development / transfer process are formed for each color, the monochrome image forming speed and the full-color image forming speed do not change, and there is an advantage that it can cope with high-speed image formation of a full-color image. is doing.
[0006]
However, in this method, since each color image is formed using a separate electrostatic latent image carrier, it is necessary to stabilize the development amount of each color in order to control the color balance. In addition, since the toner image formed on each electrostatic latent image carrier is transferred to the image support and then fixed, the image is formed. If the adhesion on the image support differs between the colors, the image is fixed. There is a problem that image stability at the time is lost.
[0007]
The electrostatic latent image carrier is usually an electrophotographic photosensitive member, and may hereinafter be simply referred to as a photosensitive member or an electrophotographic photosensitive member.
[0008]
On the other hand, as a fixing method, a so-called hot roll fixing method is preferably used due to the simplicity of the apparatus and the like. In this fixing method, since the fixing roller and the toner are in contact with each other, it is preferable to add a release agent to the toner in order to ensure releasability.
[0009]
However, in the toner prepared by the conventional pulverization method, the material dispersed in the toner is unevenly present on the fracture surface, and in particular, the material that sharply melts such as a release agent tends to be unevenly distributed on the surface. The surface property between them is difficult to be constant. For this reason, it is difficult to stabilize the development amount and to make the adhesion between the colors uniform, and there is a problem that the variation tends to occur and the color reproducibility as a color image is lowered.
[0010]
On the other hand, a so-called polymerized toner prepared by a polymerization method is known, and among these polymerized toners, a suspension polymerization method toner can form a spherical toner having a uniform surface property. Is expected to be higher. However, the shape tends to be spherical, and the adhesion to the electrostatic latent image carrier or the image support is increased, so that the transferability is lowered, and problems such as image repelling at the time of fixing tend to occur.
[0011]
As a result, it is difficult to obtain a stable image over a long period of time by the image forming method using the tandem method.
[0012]
[Problems to be solved by the invention]
An object is to provide a color image forming method and an image forming apparatus having high color reproducibility that are stable over a long period of time and an image forming apparatus using the tandem method, and an electrostatic latent image developing toner used therefor.
[0013]
[Means for Solving the Problems]
As a result of diligent studies, the present inventors have found that by specifying a specific toner structure, it is possible to stabilize an image even in a tandem system using a highly releasable toner. Was able to be completed.
[0014]
  That is, the object of the present invention is achieved by adopting one of the following configurations.
  [1] A latent image is formed on a plurality of electrostatic latent image carriers, and the latent image formed on each electrostatic latent image carrier is developed containing toner of a different color for each electrostatic latent image carrier. In a toner for developing an electrostatic latent image used in an image forming method including a step of forming a visible image by developing with an agent, transferring the visible image onto an image support and then fixing the image, A toner comprising at least a binder resin, a colorant, and a release agent, and obtained by dispersing and polymerizing a radical polymerizable monomer in which a release agent is dissolved in water.It was obtained by polymerizing a radical polymerizable monomer to the particles,A toner obtained by salting out / fusing a resin particle in which a release agent is encapsulated in a binder resin and a colorant, wherein the release agent is a compound represented by the following general formula An electrostatic latent image developing toner.
    General formula: R₁-(OCO-R₂)_n
(In the formula, n is an integer of 2 to 4, R₁, R₂Represents a hydrocarbon group which may have a substituent, and R₁Is a hydrocarbon group having 1 to 40 carbon atoms, R₂Represents a hydrocarbon group having 16 to 30 carbon atoms. )
[0015]
  [2] Developing latent images formed on a plurality of electrostatic latent image carriers, and developing the latent images formed on the electrostatic latent image carriers with different color toners for each electrostatic latent image carrier In an image forming method comprising a step of developing with an agent to form a visible image, a step of transferring the visible image onto an image support, and a step of fixing the transferred visible image, the toner comprises at least a binder resin A toner comprising a colorant and a release agent, and obtained by dispersing and polymerizing a radical polymerizable monomer in which the release agent is dissolved in waterIt was obtained by polymerizing a radical polymerizable monomer to the particles,A toner obtained by salting out / fusing a resin particle in which a release agent is encapsulated in a binder resin and a colorant, wherein the release agent is a compound represented by the following general formula An image forming method.
    General formula: R₁-(OCO-R₂)_n
(In the formula, n is an integer of 2 to 4, R₁, R₂Represents a hydrocarbon group which may have a substituent, and R₁Is a hydrocarbon group having 1 to 40 carbon atoms, R₂Represents a hydrocarbon group having 16 to 30 carbon atoms. )
[0016]
[3] The image forming method according to [2], wherein the visible image obtained by the development is transferred to an intermediate transfer member and then transferred onto an image support.
[0017]
  [4] A latent image is formed on a plurality of electrostatic latent image carriers, and the latent image formed on each electrostatic latent image carrier is developed with toners of different colors for each electrostatic latent image carrier. In an image forming apparatus for performing an image forming method comprising a step of developing with an agent to form a visible image, a step of transferring the visible image onto an image support, and a step of fixing the transferred visible image, The toner is a toner composed of at least a binder resin, a colorant, and a release agent, and obtained by dispersing and polymerizing a radical polymerizable monomer in which the release agent is dissolved in water.It was obtained by polymerizing a radical polymerizable monomer to the particles,A toner obtained by salting out / fusing a resin particle in which a release agent is encapsulated in a binder resin and a colorant, wherein the release agent is a compound represented by the following general formula An image forming apparatus.
    General formula: R₁-(OCO-R₂)_n
(In the formula, n is an integer of 2 to 4, R₁, R₂Represents a hydrocarbon group which may have a substituent, and R₁Is a hydrocarbon group having 1 to 40 carbon atoms, R₂Represents a hydrocarbon group having 16 to 30 carbon atoms. )
[0018]
The inventors of the present invention have studied the various toners that can suppress the fixing property, particularly the offset to the fixing roller, while maintaining the surface uniformity characteristic of the so-called polymerization toner, and have completed the invention. It is.
[0019]
In the present invention, a toner obtained by salting out / fusion-bonding resin particles encapsulating a release agent and a colorant is used as the toner.
[0020]
The reason why the constitution of the present invention brings about the effects of the present invention is not clear. However, unlike the so-called suspension polymerization toner, the release agent itself is contained in the resin particles, and the particles are mixed with the colorant and the salt. Since the toner is formed by depositing and fusing, the toner surface has a uniform structure despite the presence of the release agent in the vicinity of the surface of the toner, without impairing the transferability. It is presumed that the releasability could be exhibited.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be further described. First, a so-called tandem image forming method and apparatus according to the present invention will be described.
[0022]
FIG. 1 is a schematic configuration diagram showing an example of a color electrophotographic apparatus of the present invention.
In the main body of the color electrophotographic image forming apparatus, first, second, third and fourth image forming portions Pa, Pb, Pc and Pd are installed in parallel. Each image forming unit has the same configuration, and forms visible images (toner images) of different colors.
[0023]
The image forming portions Pa, Pb, Pc, and Pd include dedicated electrostatic latent image carriers (electrophotographic photosensitive drums) la, lb, lc, and ld, respectively. Electrophotographic photosensitive drums formed by the image forming portions Pa, Pb, Pc and Pd (sometimes abbreviated as photosensitive drums) la, lb, lc and ld are adjacent to the image forming portions. The image is transferred onto the image support 6 that is carried and conveyed on the image support carrier 8 that moves. Further, the image on the image support 6 is fixed by heating and pressurizing at the fixing unit 7, and the image support is discharged to the tray 61.
[0024]
Next, the latent image forming unit in each image forming unit will be described. Disposed on the outer periphery of each of the photosensitive drums la, lb, lc, and ld are static elimination exposure lamps 2la, 2lb, 2lc, and 2ld, drum chargers 2a, 2b, 2c, and 2d, a laser beam exposure device 17 as an image exposure unit, and a potential. Sensors 22a, 22b, 22c, and 22d are provided. The photosensitive drums la, lb, lc, and ld that have been neutralized by the charge eliminating exposure lamps 2la, 2lb, 2lc, and 2ld are uniformly charged by the drum chargers 2a, 2b, 2c, and 2d, and then the laser beam exposure device 17 As a result of the exposure, a color-separated electrostatic latent image corresponding to the image signal is formed on the photosensitive drums la, lb, lc, and ld. In the image forming apparatus of the present invention, as the image exposure means, in addition to the laser beam exposure apparatus 17 described above, a light quantity level other than OFF in a basic image unit (pixel) such as an LED array exposure apparatus is used. Well-known multi-value exposure means that can irradiate can be suitably employed.
[0025]
The electrostatic latent image on the photosensitive drum is developed by a developing unit to become a visible image. That is, the developing means includes developing devices 3a, 3b, 3c, and 3d filled with a predetermined amount of cyan, magenta, yellow, and black developers, for example, two-component developers having toner and carrier. The electrostatic latent images formed on the photosensitive drums la, lb, lc, and ld are developed to obtain visible images (toner images).
[0026]
Next, the transfer part will be described. The image support 6 held in the image support cassette 60 is fed to the image support carrier 8 through the registration roller 13.
[0027]
Here, the image support carrier 8 is a dielectric resin film such as a polyethylene terephthalate resin film sheet (PET sheet), a polyvinylidene fluoride resin film sheet, or a polyurethane resin film sheet. A belt that is overlapped and joined to form an endless shape or has no seam (seamless) is used. In the case of a belt having a seam, it is preferable to provide a means (not shown) for detecting the position of the seam so that transfer is not performed on the seam.
[0028]
When the image support carrier 8 starts to rotate, the image support 6 is conveyed from the registration roller 13 onto the image support carrier 8. At this time, the image writing signal is turned ON, and an image is formed on the first electrophotographic photosensitive drum la at an appropriate timing.
[0029]
A transfer charger 4a and a transfer pressing member 41a are provided below the first electrophotographic photosensitive drum la, and a uniform pressing force is applied to the photosensitive drum by the transfer pressing member 4la. Then, the transfer charger 4 a applies an electric field to transfer the toner image on the photosensitive drum la onto the image support 6. At this time, the image support 6 is held on the image support carrier 8 by electrostatic attraction, and the image support 6 is conveyed to the second image forming portion Pb, and the next transfer is performed. Thereafter, the image support 6 to which the toner images formed by the third and fourth image forming portions Pc and Pd are transferred by the same method as described above is discharged by the separation charger 14 and the electrostatic adsorption force is attenuated. Is separated from the image support carrier 8 and conveyed to the fixing unit 7.
[0030]
The fixing unit 7 includes a fixing roller 71, a pressure roller 72, heat resistant cleaning members 73 and 74 for cleaning the rollers 71 and 72, heaters 75 and 76 for heating the rollers 71 and 72, and a release agent such as dimethyl silicone. An oil application roller 77 for applying oil to the fixing roller 71, an oil reservoir 78 for supplying the oil, and a thermistor 79 for fixing temperature control are included.
[0031]
After the transfer, the toner remaining on the photosensitive drums la, lb, lc, and ld is removed by the photosensitive member cleaning units 5a, 5b, 5c, and 5d, and is prepared for the subsequent latent image formation. Further, the toner and the like remaining on the image support 8 are removed by the belt static eliminator 12 and the electrostatic adsorption force is removed, and then removed by the cleaning device 62 having a nonwoven fabric in this example. As the cleaning device 62, a rotating fur brush, a blade, or a device using these in combination is also used.
[0032]
Next, developing means that can be employed in the image forming apparatus of the present invention will be described in more detail with reference to FIG. Since the developing units in the image forming units Pa, Pb, Pc, and Pd have the same configuration, only the developing unit in the image forming unit Pa will be described.
[0033]
FIG. 2 is a schematic sectional view of the developing means (developing device or developing device) in the image forming portion Pa. The developing device 3a disposed opposite to the photosensitive drum 1a includes a developing container 30 containing a two-component developer, a developing sleeve 31 as a developer carrying member, and a head cutting from the developer supply position by the developing sleeve 31. A developer return member (a developer accumulation amount regulating member on the developing sleeve 31) 32 that regulates the developer conveyed to the position, and a blade 33 as a developer spike height (layer thickness) regulating member, Further, an optical toner density sensor (not shown) is provided as developer density detecting means for detecting the toner density of the two-component developer.
[0034]
The interior of the developer container 30 is divided into a developing chamber 30A and a stirring chamber 30B by a partition wall 37 extending in a substantially vertical direction. The developing chamber 30A and the stirring chamber 30B contain a two-component developer containing nonmagnetic toner and a magnetic carrier. The upper part of the partition wall 37 is released, and the two-component developer which is excessive in the developing chamber 30A is collected on the stirring chamber 30B side. Screw type first and second developer agitating / conveying means 34, 35 are disposed in the developing chamber 30A and the agitating chamber 30B, respectively. The first agitating / conveying means 34 agitates and conveys the developer in the developing chamber 30A, and the second agitating / conveying means 35 is a toner replenishing tank (see FIG. The toner supplied to the upstream side of the agitating / conveying means 35 and the developer already in the agitating chamber 30B are agitated and conveyed to make the toner density uniform. The partition wall 37 is formed with a developer passage (not shown) that allows the developing chamber 30A and the stirring chamber 30B to communicate with each other at the front and back end portions. By the transporting force of the stirring and transporting means, The developer in the developing chamber 30A in which the toner is consumed by the development and the toner density is lowered is configured to move from one passage into the stirring chamber 30B.
[0035]
The developing chamber 30A of the developing unit has an opening at a position corresponding to the developing area facing the photosensitive drum 3a, and the developing sleeve 31 is rotatably arranged so as to be partially exposed to the opening. Yes. The developing sleeve 31 is made of a non-magnetic material, and rotates in the direction of the arrow in the drawing during the developing operation, and a magnet 36 that is a magnetic field generating means is fixed therein.
[0036]
The two-component developer supplied to the surface of the developing sleeve 31 by the agitating / conveying means is held in the state of a magnetic brush on the surface of the developing sleeve 31 by the magnetic force of the magnet 36, and the photoconductor as the developing sleeve 31 rotates. While being transported to the developing area facing the drum 1a, the magnetic brush on the developer sleeve 31 is cut off by the developer returning member 32 and the blade 33 in the course of transporting, and an appropriate amount of developer is transported to the developing area. Maintained.
[0037]
The developer thus transported to the development area by the developing sleeve 31 is supplied to the photosensitive drum 3a to develop the electrostatic latent image formed thereon. In order to improve the development efficiency, that is, the toner application rate to the latent image, the development sleeve 31 is applied with a development bias in which a DC voltage and an alternating voltage are superimposed from the power source, or one of the development bias voltages. As a result, the toner of the two-component developer moves to the electrostatic latent image side on the photosensitive drum 1a, and the electrostatic latent image is visualized as a toner image.
[0038]
In the above description, the toner image is transferred by transferring each color toner image to an image support (usually referred to as transfer paper because it is paper such as plain paper) conveyed on the image support carrier. I explained with the method of doing. However, instead of the image support carrier, an intermediate transfer member may be used instead, and the toner image may be once transferred to the intermediate transfer member and then retransferred to the image support. The image support carrier and the intermediate transfer member are usually belt-shaped or drum-shaped.
[0039]
Further, if a long electrophotographic photosensitive member is used, the number of electrophotographic photosensitive members is not limited to one but can be dealt with by one.
[0040]
Next, the fixing unit will be described. FIG. 3 shows the configuration of the fixing device preferably used in the present invention.
[0041]
FIG. 3 is a cross-sectional view illustrating an example of a fixing device (also referred to as a fixing device) used in the present invention, and includes a fixing roller 71 and a pressure roller 72 that contacts the fixing roller 71. In FIG. 3, T is a toner image formed on the image support 6.
[0042]
The fixing roller 71 has a coating layer 82 made of a fluororesin formed on the surface of a cored bar 81 and includes a heating member 83 made of a linear heater.
[0043]
The metal core 81 is made of a metal selected from aluminum, iron and copper, or an alloy thereof, and has an inner diameter of 10 to 70 mm.
[0044]
The thickness of the cored bar 81 is set to 0.1 to 2 mm, and is determined in consideration of a balance between a request for energy saving (thinning) and strength (depending on constituent materials). For example, in order to maintain the same strength as that of a cored bar made of iron of 0.57 mm with a cored bar made of aluminum, the wall thickness needs to be 0.8 mm.
[0045]
Examples of the fluororesin constituting the coating layer 82 include PTFE (polytetrafluoroethylene) and PFA (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer). In this case, the thickness of the coating layer 82 is 10 to 500 μm. Preferably it is 20-400 micrometers. If the thickness is less than 10 μm, the durability of the fixing device may not be ensured because the fluororesin is not durable. Further, when the resin layer is thick, there is a problem that scratches due to paper dust are easily caused, and adhesion of toner or the like occurs in the scratched portion, resulting in image smearing. In the case of silicone rubber, for example, LTV, RTV, and HTV silicone rubber or sponge can be used. The thickness of the coating layer 82 is 0.1 to 30 mm. Preferably it is 0.1-20 mm. If the thickness is less than 0.1 mm, the fixing nip cannot be enlarged and the effect of soft fixing may not be exhibited.
[0046]
As the heating member 83, a halogen heater can be preferably used.
The pressure roller 72 is formed by forming a coating layer 92 made of rubber on the surface of the cored bar 91. The rubber of the coating layer is not particularly limited, and urethane rubber, silicone rubber, and the like can be used, but heat resistant silicone rubber is more preferable. For example, LTV, RTV, and HTV silicone rubber or sponge, and the same material as the coating layer 82 can be used.
[0047]
The cored bar 91 is made of a metal such as aluminum or iron or an alloy thereof.
[0048]
The thickness of the coating layer 92 is 0.1 to 30 mm. Preferably it is 0.1-20 mm. If the thickness is less than 0.1 mm, the fixing nip cannot be enlarged and the effect of soft fixing may not be exhibited.
[0049]
The silicone rubber or rubber constituting the coating layers 82 and 92 has an Asker C hardness of 80 degrees, preferably less than 60 degrees, and a silicone sponge rubber can be preferably used.
[0050]
The contact load (total load) between the heating roller 71 and the pressure roller 72 is usually 40 to 350 N, preferably 50 to 300 N, and more preferably 50 to 250 N. This contact load is defined in consideration of the strength of the heating roller 71 (thickness of the cored bar 81). For example, in a fixing roller having a cored bar made of 0.3 mm iron, the contact load should be 250 N or less. Is preferred.
[0051]
From the viewpoint of offset resistance and fixing property, the nip width is preferably 4 to 8 mm, and the surface pressure of the nip is 0.6 to 1.5 × 10.^FivePa is preferred.
[0052]
An example of fixing conditions by the fixing device shown in FIG. 3 is that the fixing temperature (surface temperature of the fixing roller 71) is 150 to 210 ° C., and the fixing linear velocity is 80 to 640 mm / sec.
[0053]
The fixing unit used in the present invention may be provided with a fixing device cleaning mechanism, if necessary. In this case, as a method of supplying silicone oil to the fixing roller of the fixing unit, a method of supplying and cleaning with a pad, roller, web or the like impregnated with silicone oil can be used.
[0054]
As the silicone oil, one having high heat resistance is used, and polydimethyl silicone, polyphenylmethyl silicone, polydiphenyl silicone and the like are used. Since a low-viscosity thing will have a large outflow at the time of use, those having a viscosity at 20 ° C. of 1 to 100 Pa · s are preferably used.
[0055]
In particular, the present invention is remarkably effective in a system that does not use or hardly requires silicone oil. In this case, the supply amount of the silicone oil is not particularly limited, but is preferably 2 mg / A4 or less. As a result, the amount of silicon oil attached to the paper after fixing can be reduced, and there is no difficulty in filling in an oil pen such as a ballpoint pen with the silicone oil attached to the paper, while the problem of fixing offset does not occur. preferable.
[0056]
Furthermore, the degree of surface gloss of the finished image is preferably a so-called semi-gloss image, that is, finished at 17 to 37 degrees in standard gloss measurement. By setting this range, it is possible to simultaneously satisfy the non-glossiness desirable for office documents and the glossiness required for color images.
[0057]
In order to ensure color reproducibility of the color, surface gloss is required, and this depends on the balance between the lower layer color and the upper layer color, but the color reproducibility is improved as the image has higher smoothness. However, if the smoothness is high, the gloss becomes high, and the light is reflected on the image surface, resulting in a difficult-to-see image that is categorized. In an office document, it is preferable that characters can be read more easily and color reproducibility of a color image formed simultaneously is high. As a range in which this can be achieved, there is a 17-37 degree semi-gloss image in standard glossiness measurement.
[0058]
Note that the standard glossiness measurement method uses an image in which the image support is coated with 90% or more (image area) of the image support material (toner), and an incident angle of 75 is measured according to JIS-Z8741-1983 method 2. A value measured by a gloss meter VGS-1D (manufactured by Nippon Denshoku Industries Co., Ltd.) is shown at °. In the present invention, the coating ratio of the image forming material on the image support was measured using a high-speed color image analyzer SPICCA (manufactured by Nippon Avionics).
[0059]
Next, the toner and developer of the present invention will be described.
As will be described in detail later, the toner used in the present invention is a toner obtained by fusing resin particles encapsulating a release agent in an aqueous medium. In this way, the resin particles in which the release agent is encapsulated in the resin particles are salted out / fused in the aqueous medium with the colorant particles, whereby a toner in which the release agent is finely dispersed can be obtained.
[0060]
The release agent of the present invention preferably has the following constitution mainly composed of an electol system.
[0061]
      R₁-(OCO-R₂)_n
  nIs an integer from 2 to 4,Preferably it is 3-4, Most preferably, it is 4.
[0062]
R₁, R₂Represents a hydrocarbon group which may have a substituent.
R₁: Carbon number is 1-40 hydrocarbon group, Preferably it is C1-C20, More preferably, it is 2-5.
[0063]
R₂: A hydrocarbon group having 1 to 40 carbon atoms, preferably 16 to 30 carbon atoms, more preferably 18 to 26 carbon atoms.
[0064]
The specific structure is given as an exemplary compound below.
[0065]
[Chemical 1]

[0066]
[Chemical formula 2]

[0067]
The addition amount is 1 to 30% by mass, preferably 2 to 20% by mass, and more preferably 3 to 15% by mass with respect to the whole toner.
[0068]
The toner of the present invention is obtained by dispersing a polymer in which a release agent is dissolved in water and polymerizing it to form particles in which a release agent such as electol is encapsulated in resin particles, together with the colorant particles. The toner is formed by salting out / fusion.
[0069]
As described above, since the toner image is based on semi-gloss, the molecular weight distribution of the toner binder resin suitable for making the toner image has a peak or peak in the region of 100,000 to 1,000,000 in GPC molecular weight measurement. It is preferable to contain both a high molecular weight component having a shoulder and a low molecular weight component having a peak or shoulder in the region of 1,000 to 20,000.
[0070]
The resin molecular weight measurement method by GPC (gel permeation chromatography) in the present invention was measured by GPC using THF (tetrohydrofuran) as a solvent. That is, 1 ml of THF is added to 0.5 to 5 mg of a measurement sample, more specifically 1 mg, and the mixture is sufficiently dissolved by stirring at room temperature using a magnetic stirrer or the like. Subsequently, after processing with a membrane filter having a pore size of 0.45 to 0.50 μm, the solution is injected into GPC. The measurement conditions of GPC are measured by stabilizing the column at 40 ° C., flowing THF at a flow rate of 1 ml / min, and injecting about 100 μl of a sample having a concentration of 1 mg / ml. The column is preferably used in combination with a commercially available polystyrene gel column.
[0071]
For example, Shodex GPC KF-801, 802, 803, 804, 805, 806, 807 made by Showa Denko KK, TSKgel G1000H, G2000H, G3000H, G4000H, G5000H, G6000H, G7000H, TSK guard column manufactured by Tosoh Corporation Combinations can be mentioned. As a detector, a refractive index detector (IR detector) or a UV detector may be used. In the measurement of the molecular weight of a sample, the molecular weight distribution of the sample is calculated using a calibration curve created using monodisperse polystyrene standard particles. About 10 points may be used as polystyrene for preparing a calibration curve.
[0072]
As in the present invention, the salted-out / fused toner has a shape with irregularities on the surface from the time of toner production, and further, the toner is fused in an aqueous medium. As a result, the surface property tends to be uniform, so that it is difficult to cause a difference in fixability between toners, and the fixability can be kept good.
[0073]
As a method for fusing in an aqueous medium, for example, methods described in JP-A-63-186253, JP-A-63-282749, JP-A-7-146582, etc. For example, a method of forming it by wearing can be given.
[0074]
The resin particles encapsulating the release agent used in the production of the toner of the present invention preferably have a mass average particle size of 50 to 2000 nm. These resin particles can be obtained by any granulation polymerization method such as emulsion polymerization, suspension polymerization, and seed polymerization. Also good.
[0075]
Hereinafter, examples of resin particle materials and manufacturing methods will be described.
"material"
Monomer
As the polymerizable monomer, a radically polymerizable monomer is an essential component, and a crosslinking agent can be used as necessary. Moreover, it is preferable to contain at least one radical polymerizable monomer having the following acidic group or radical polymerizable monomer having a basic group.
[0076]
(1) Radical polymerizable monomer
The radical polymerizable monomer component is not particularly limited, and a conventionally known radical polymerizable monomer can be used. Moreover, it can be used combining 1 type (s) or 2 or more types so that the required characteristic may be satisfy | filled.
[0077]
Specifically, aromatic vinyl monomers, (meth) acrylic acid ester monomers, vinyl ester monomers, vinyl ether monomers, monoolefin monomers, diolefin monomers , Halogenated olefin monomers and the like can be used.
[0078]
Examples of the aromatic vinyl monomer include styrene, o-methyl styrene, m-methyl styrene, p-methyl styrene, p-methoxy styrene, p-phenyl styrene, p-chloro styrene, p-ethyl styrene, p. -N-butyl styrene, p-tert-butyl styrene, pn-hexyl styrene, pn-octyl styrene, pn-nonyl styrene, pn-decyl styrene, pn-dodecyl styrene, 2, Examples thereof include styrene monomers such as 4-dimethylstyrene and 3,4-dichlorostyrene and derivatives thereof.
[0079]
Examples of (meth) acrylic acid ester monomers include methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, phenyl acrylate, methyl methacrylate, ethyl methacrylate, and methacrylic acid. Examples include butyl, hexyl methacrylate, 2-ethylhexyl methacrylate, ethyl β-hydroxyacrylate, propyl γ-aminoacrylate, stearyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, and the like.
[0080]
Examples of vinyl ester monomers include vinyl acetate, vinyl propionate, and vinyl benzoate.
[0081]
Examples of the vinyl ether monomer include vinyl methyl ether, vinyl ethyl ether, vinyl isobutyl ether, vinyl phenyl ether and the like.
[0082]
Examples of the monoolefin monomer include ethylene, propylene, isobutylene, 1-butene, 1-pentene, 4-methyl-1-pentene and the like.
[0083]
Examples of the diolefin monomer include butadiene, isoprene, chloroprene and the like.
[0084]
Examples of the halogenated olefin monomer include vinyl chloride, vinylidene chloride, vinyl bromide and the like.
[0085]
(2) Cross-linking agent
As the crosslinking agent, a radical polymerizable crosslinking agent may be added in order to improve the properties of the toner. Examples of the radical polymerizable crosslinking agent include those having two or more unsaturated bonds such as divinylbenzene, divinylnaphthalene, divinyl ether, diethylene glycol methacrylate, ethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, and diallyl phthalate.
[0086]
(3) Radical polymerizable monomer having an acidic group or radical polymerizable monomer having a basic group
Examples of the radical polymerizable monomer having an acidic group or the radical polymerizable monomer having a basic group include a carboxyl group-containing monomer, a sulfonic acid group-containing monomer, a primary amine, and a secondary group. Amine-based compounds such as amines, tertiary amines, and quaternary ammonium salts can be used.
[0087]
Examples of the radical polymerizable monomer having an acidic group include carboxylic acid group-containing monomers such as acrylic acid, methacrylic acid, fumaric acid, maleic acid, itaconic acid, cinnamic acid, maleic acid monobutyl ester, and maleic acid monoester. An octyl ester etc. are mentioned.
[0088]
Examples of the sulfonic acid group-containing monomer include styrene sulfonic acid, allyl sulfosuccinic acid, octyl allyl sulfosuccinate and the like.
[0089]
These may have a structure of an alkali metal salt such as sodium or potassium or an alkaline earth metal salt such as calcium.
[0090]
Examples of the radical polymerizable monomer having a basic group include amine compounds, dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, diethylaminoethyl acrylate, diethylaminoethyl methacrylate, and quaternary ammonium salts of the above four compounds, 3-dimethylaminophenyl acrylate, 2-hydroxy-3-methacryloxypropyltrimethylammonium salt, acrylamide, N-butylacrylamide, N, N-dibutylacrylamide, piperidylacrylamide, methacrylamide, N-butylmethacrylamide, N-octadecylacrylamide Vinyl pyridine, vinyl pyrrolidone; vinyl N-methylpyridinium chloride, vinyl N-ethylpyridinium chloride, N, N-diallyl Examples thereof include methylammonium chloride and N, N-diallylethylammonium chloride.
[0091]
As the radical polymerizable monomer used in the present invention, a radical polymerizable monomer having an acidic group or a radical polymerizable monomer having a basic group is used in an amount of 0.1 to 15% by mass based on the whole monomer. The radical polymerizable crosslinking agent is preferably used in the range of 0.1 to 10% by mass with respect to the total radical polymerizable monomer, although it depends on its properties.
[0092]
Chain transfer agent
For the purpose of adjusting the molecular weight, it is possible to use a commonly used chain transfer agent.
[0093]
The chain transfer agent is not particularly limited, and for example, mercaptans such as octyl mercaptan, dodecyl mercaptan, tert-dodecyl mercaptan, carbon tetrabromide and styrene dimer are used.
[0094]
Polymerization initiator
The radical polymerization initiator used in the present invention can be appropriately used as long as it is water-soluble. For example, persulfates (potassium persulfate, ammonium persulfate, etc.), azo compounds (4,4′-azobis-4-cyanovaleric acid and its salts, 2,2′-azobis (2-amidinopropane) salts, etc.), peroxides Compounds and the like.
[0095]
Furthermore, the radical polymerization initiator can be combined with a reducing agent as necessary to form a redox initiator. By using a redox initiator, the polymerization activity is increased, the polymerization temperature is lowered, and the polymerization time can be further shortened.
[0096]
The polymerization temperature may be any temperature as long as it is equal to or higher than the lowest radical generation temperature of the polymerization initiator, but for example, a range of 50 ° C. to 90 ° C. is used. However, it is possible to perform polymerization at room temperature or higher by using a polymerization initiator that starts at room temperature, for example, a combination of hydrogen peroxide and a reducing agent (ascorbic acid or the like).
[0097]
Surfactant
In order to perform polymerization using the above-mentioned radical polymerizable monomer, it is necessary to perform oil droplet dispersion in an aqueous medium using a surfactant. Although it does not specifically limit as surfactant which can be used in this case, The following ionic surfactant can be mentioned as an example of a suitable thing.
[0098]
Examples of ionic surfactants include sulfonates (sodium dodecylbenzenesulfonate, sodium arylalkylpolyethersulfonate, 3,3-disulfonediphenylurea-4,4-diazo-bis-amino-8-naphthol-6 Sodium sulfonate, ortho-carboxybenzene-azo-dimethylaniline, 2,2,5,5-tetramethyl-triphenylmethane-4,4-diazo-bis-β-naphthol-6-sodium sulfonate, etc.), sulfuric acid Ester salts (sodium dodecyl sulfate, sodium tetradecyl sulfate, sodium pentadecyl sulfate, sodium octyl sulfate, etc.), fatty acid salts (sodium oleate, sodium laurate, sodium caprate, sodium caprylate, sodium caproate, potassium stearate) Beam, calcium oleate and the like).
[0099]
Nonionic surfactants can also be used. Specifically, polyethylene oxide, polypropylene oxide, combination of polypropylene oxide and polyethylene oxide, ester of polyethylene glycol and higher fatty acid, alkylphenol polyethylene oxide, ester of higher fatty acid and polyethylene glycol, ester of higher fatty acid and polypropylene oxide, sorbitan ester Etc.
[0100]
In the present invention, these are mainly used as an emulsifier at the time of emulsion polymerization, but may be used for other processes or purposes.
[0101]
Colorant
Examples of the colorant include inorganic pigments, organic pigments, and dyes.
[0102]
A conventionally well-known thing can be used as an inorganic pigment. Specific inorganic pigments are exemplified below.
[0103]
Examples of the black pigment include carbon black such as furnace black, channel black, acetylene black, thermal black, and lamp black, and magnetic powder such as magnetite and ferrite.
[0104]
These inorganic pigments can be used alone or in combination as required. Moreover, the addition amount of a pigment is 2-20 mass% with respect to a polymer, Preferably 3-15 mass% is selected.
[0105]
When used as a magnetic toner, the above-mentioned magnetite can be added. In this case, it is preferable to add 20 to 60% by mass in the toner from the viewpoint of imparting predetermined magnetic properties.
[0106]
Conventionally known organic pigments and dyes can also be used. Specific organic pigments and dyes are exemplified below.
[0107]
Examples of pigments for magenta or red include C.I. I. Pigment red 2, C.I. I. Pigment red 3, C.I. I. Pigment red 5, C.I. I. Pigment red 6, C.I. I. Pigment red 7, C.I. I. Pigment red 15, C.I. I. Pigment red 16, C.I. I. Pigment red 48: 1, C.I. I. Pigment red 53: 1, C.I. I. Pigment red 57: 1, C.I. I. Pigment red 122, C.I. I. Pigment red 123, C.I. I. Pigment red 139, C.I. I. Pigment red 144, C.I. I. Pigment red 149, C.I. I. Pigment red 166, C.I. I. Pigment red 177, C.I. I. Pigment red 178, C.I. I. And CI Pigment Red 222.
[0108]
Examples of the orange or yellow pigment include C.I. I. Pigment orange 31, C.I. I. Pigment orange 43, C.I. I. Pigment yellow 12, C.I. I. Pigment yellow 13, C.I. I. Pigment yellow 14, C.I. I. Pigment yellow 15, C.I. I. Pigment yellow 17, C.I. I. Pigment yellow 93, C.I. I. Pigment yellow 94, C.I. I. Pigment yellow 138, C.I. I. Pigment yellow 180, C.I. I. Pigment yellow 185, C.I. I. Pigment yellow 155, C.I. I. Pigment yellow 156, and the like.
[0109]
Examples of pigments for green or cyan include C.I. I. Pigment blue 15, C.I. I. Pigment blue 15: 2, C.I. I. Pigment blue 15: 3, C.I. I. Pigment blue 16, C.I. I. Pigment blue 60, C.I. I. And CI Pigment Green 7.
[0110]
As the dye, C.I. I. Solvent Red 1, 49, 52, 58, 63, 111, 122, C.I. I. Solvent Yellow 19, 44, 77, 79, 81, 82, 93, 98, 103, 104, 112, 162, C.I. I. Solvent Blue 25, 36, 60, 70, 93, 95 etc. can be used, and a mixture thereof can also be used.
[0111]
These organic pigments and dyes can be used alone or in combination as desired. Moreover, the addition amount of a pigment is 2-20 mass% with respect to a polymer, Preferably 3-15 mass% is selected.
[0112]
The colorant can also be used after surface modification. As the surface modifier, conventionally known ones can be used, and specifically, silane coupling agents, titanium coupling agents, aluminum coupling agents and the like can be preferably used.
[0113]
"Manufacturing process"
In the production process of the polymerized toner of the present invention, a monomer solution in which a release agent is dissolved is dispersed in an aqueous medium, and then a resin particle containing the release agent is prepared by a polymerization method, and the resin particle dispersion is used. Obtained by fusing resin particles in an aqueous medium, washing the obtained particles from the aqueous medium to remove the surfactant, drying the obtained particles, and further drying. It consists of an external additive addition step for adding an external additive to the particles. Here, the resin particles may be colored particles. In addition, non-colored particles can also be used as resin particles. In this case, colored particles are formed by adding a colorant particle dispersion or the like to the resin particle dispersion and then fusing it in an aqueous medium. Can do.
[0114]
In particular, the method of fusing is preferably a method of salting out / fusing using resin particles produced by the polymerization step. When non-colored resin particles are used, the resin particles and the colorant particles can be salted out / fused in an aqueous medium.
[0115]
In addition to the colorant and the release agent, a charge control agent that is a component of the toner can be added as particles in this step.
[0116]
In addition, an aqueous medium here consists of water as a main component, and shows content whose water content is 50 mass% or more. Examples of substances other than water include organic solvents that dissolve in water, such as methanol, ethanol, isopropanol, butanol, acetone, methyl ethyl ketone, and tetrahydrofuran. Alcohol organic solvents such as methanol, ethanol, isopropanol, and butanol, which are preferably organic solvents that do not dissolve the resin, are particularly preferable.
[0117]
As a preferable polymerization method in the present invention, a monomer solution in which a release agent is dissolved in a monomer is dispersed in an aqueous medium in which a surfactant having a critical micelle concentration or less is dissolved, and dispersed in oil droplets by mechanical energy. And a method of radical polymerization by adding a water-soluble polymerization initiator. In this case, an oil-soluble polymerization initiator may be added to the monomer.
[0118]
The disperser for performing the oil droplet dispersion is not particularly limited, and examples thereof include CLEARMIX, ultrasonic disperser, mechanical homogenizer, manton gourin, and pressure homogenizer.
[0119]
The colorant itself may be used after surface modification. In the surface modification method of the colorant, the colorant is dispersed in a solvent, and after the surface modifier is added therein, the temperature is raised and the reaction is performed. After completion of the reaction, the mixture is filtered, washed with the same solvent, repeatedly filtered and dried to obtain a pigment treated with a surface modifier.
[0120]
There is a method in which the colorant particles are prepared by dispersing a colorant in an aqueous medium. This dispersion is performed in a state where the surfactant concentration in water is equal to or higher than the critical micelle concentration (CMC).
[0121]
The disperser at the time of pigment dispersion is not particularly limited, but preferably a medium such as CLEARMIX, ultrasonic disperser, mechanical homogenizer, pressure disperser such as Manton Gorin or pressure homogenizer, sand grinder, Getzmann mill, diamond fine mill, etc. Type disperser.
[0122]
As the surfactant used here, the aforementioned surfactants can be used.
In the salting out / fusion process, a salting-out agent composed of an alkali metal salt or an alkaline earth metal salt is added as a flocculant having a critical coagulation concentration or more in water in which resin particles and colorant particles are present, Next, it is a step of performing fusion at the same time as salting-out proceeds by heating the resin particles to the glass transition point or higher.
[0123]
Here, the alkali metal salt and the alkaline earth metal salt which are salting-out agents include lithium, potassium, sodium and the like as the alkali metal, and examples of the alkaline earth metal include magnesium, calcium, strontium and barium. Preferably, potassium, sodium, magnesium, calcium, and barium are used. Examples of the salt include chlorine salt, bromine salt, iodine salt, carbonate salt, sulfate salt and the like.
[0124]
When the fusion of the present invention is carried out by salting out / fusion, it is preferable to make the time allowed to stand after adding the salting-out agent as short as possible. The reason for this is not clear, but there are problems that the aggregation state of the particles fluctuates depending on the standing time after salting out, the particle size distribution becomes unstable, and the surface property of the fused toner fluctuates. appear. The temperature at which the salting-out agent is added is not particularly limited.
[0125]
Moreover, in this invention, it is preferable to use the method of heating up the dispersion liquid of a resin particle as quickly as possible, and heating it more than the glass transition temperature of a resin particle. The time until this temperature rise is less than 30 minutes, preferably less than 10 minutes. Further, although it is necessary to quickly raise the temperature, the rate of temperature rise is preferably 1 ° C./min or more. The upper limit is not particularly clear, but is preferably 15 ° C./min or less from the viewpoint of suppressing the generation of coarse particles due to rapid progress of salting out / fusion. As a particularly preferred embodiment, there can be mentioned a method in which salting-out / fusion is continued even when the glass transition temperature is reached. By adopting this method, fusion can be effectively advanced as the particles grow, and the durability as a final toner can be improved.
[0126]
Here, the particle diameter of the toner obtained by fusing according to the present invention is 3 to 9 μm in terms of volume average particle diameter. The volume average particle diameter of these toners can be measured using a Coulter Counter TA-II, Coulter Multisizer, SLAD1100 (Laser Diffraction Particle Size Measuring Device manufactured by Shimadzu Corporation), or the like. For Coulter Counter TA-II and Coulter Multisizer, those measured using a particle size distribution in the range of 2.0 to 40 μm using an aperture with an aperture diameter of 100 μm are shown.
[0127]
Further, as the toner, it is preferable that the amount of fine powder toner of 3.0 μm or less is 20% by number or less, more preferably the amount of fine powder toner of 2.0 μm or less is 10% by number or less. The amount of fine powder toner can be measured using an electrophoretic light scattering photometer ELS-800 manufactured by Otsuka Electronics Co., Ltd. In order to adjust the particle size distribution within this range, it is preferable to narrow the temperature control in the salting-out / fusion stage. Specifically, the temperature is raised as quickly as possible, that is, the temperature is raised. As this condition, it is shown in the above-mentioned conditions. The time until the temperature rise is less than 30 minutes, preferably less than 10 minutes, and the temperature rise rate is preferably 1 to 15 ° C./min.
[0128]
The toner obtained by fusing has an average shape factor (average circularity) of 0.930 to 0.980, preferably 0.940 to 0.975, represented by the following formula.
[0129]
Shape factor = (circle circumference obtained from equivalent circle diameter) / (perimeter of particle projection image)
The distribution of the shape factor is preferably sharp, the standard deviation of the circularity is preferably 0.10 or less, and the CV value calculated by the following formula is preferably less than 20%, and more preferably less than 10%.
[0130]
CV value = (standard deviation of circularity) / (average circularity) × 100
By setting the average circularity to 0.930 to 0.980, the shape of the toner can be made amorphous to some extent, the heat transfer can be made more efficient, and the fixability can be further improved. it can. That is, the fixing property can be improved by setting the average circularity to 0.980 or less. Moreover, by setting it as an average circularity of 0.930 or more, the irregularity degree of particle | grains can be suppressed and the friability of the particle | grains by the stress at the time of use for a long term can be suppressed.
[0131]
Furthermore, it is preferable that the distribution of the shape factor is sharp, and the toner having a uniform shape can be obtained by setting the standard deviation of the circularity to 0.10 or less, and the difference in fixing performance between the toners is reduced. Therefore, the effect of preventing fouling of the fixing device by improving the fixing rate and reducing the offset property is more exhibited. Further, when the CV value is also less than 20%, a sharp shape distribution can be obtained similarly, and the effect of improving the fixability can be exhibited more remarkably.
[0132]
The method of measuring the shape factor is not limited. For example, a photograph obtained by enlarging a toner particle 500 times with an electron microscope is taken, and the circularity of 500 toners is measured using an image analyzer. The average circularity can be calculated by obtaining the arithmetic average value. Moreover, as a simple measuring method, it can measure by FPIA-1000 (made by Toa Medical Electronics Co., Ltd.).
[0133]
In addition to the colorant and the release agent, the toner particles may be added with a material capable of imparting various functions as a toner material. Specific examples include charge control agents. These components can be added simultaneously with the resin particles and the colorant particles in the salting out / fusion step described above, and can be added by various methods such as a method included in the toner and a method of adding to the resin particles themselves.
[0134]
Similarly, various known charge control agents and those that can be dispersed in water can be used. Specific examples include nigrosine dyes, naphthenic acid or higher fatty acid metal salts, alkoxylated amines, quaternary ammonium salt compounds, azo metal complexes, salicylic acid metal salts or metal complexes thereof.
[0135]
<External additive>
To the toner of the present invention, so-called external additives can be added and used for the purpose of improving fluidity, chargeability and cleaning property. These external additives are not particularly limited, and various inorganic fine particles, organic fine particles and lubricants can be used.
[0136]
A conventionally well-known thing can be used as an inorganic fine particle. Specifically, silica, titanium, alumina fine particles and the like can be preferably used. These inorganic fine particles are preferably hydrophobic. Specifically, as silica fine particles, for example, commercially available products R-805, R-976, R-974, R-972, R-812, R-809 manufactured by Nippon Aerosil Co., Ltd., HVK-2150, H manufactured by Hoechst -200, commercially available products TS-720, TS-530, TS-610, H-5, MS-5 and the like manufactured by Cabot Corporation.
[0137]
Examples of the titanium fine particles include commercial products T-805 and T-604 manufactured by Nippon Aerosil Co., Ltd., commercial products MT-100S, MT-100B, MT-500BS, MT-600, MT-600SS, and JA- 1. Commercial products TA-300SI, TA-500, TAF-130, TAF-510, TAF-510T manufactured by Fuji Titanium Co., Ltd. Commercial products IT-S, IT-OA, IT-OB, IT- manufactured by Idemitsu Kosan Co., Ltd. OC etc. are mentioned.
[0138]
Examples of the alumina fine particles include commercial products RFY-C and C-604 manufactured by Nippon Aerosil Co., Ltd. and commercial products TTO-55 manufactured by Ishihara Sangyo Co., Ltd.
[0139]
As the organic fine particles, spherical organic fine particles having a number average primary particle diameter of about 10 to 2000 nm can be used. As this, a homopolymer such as styrene or methyl methacrylate or a copolymer thereof can be used.
[0140]
Examples of lubricants include, for example, zinc stearate, aluminum, copper, magnesium, calcium, etc., zinc oleate, manganese, iron, copper, magnesium, etc., zinc palmitate, copper, magnesium, calcium, etc. And salts of higher fatty acids such as zinc of linoleic acid, salts of calcium, etc., zinc of ricinoleic acid, salts of calcium, etc.
[0141]
The amount of these external additives added is preferably 0.1 to 5% by mass with respect to the toner.
As a method for adding the external additive, various known mixing apparatuses such as a Turbuler mixer, a Henschel mixer, a Nauter mixer, and a V-type mixer can be used.
[0142]
<Developer>
The toner of the present invention may be used as a one-component developer or a two-component developer.
[0143]
When used as a one-component developer, a non-magnetic one-component developer can be used.
Further, it can be mixed with a carrier and used as a two-component developer. In this case, conventionally known materials such as metals such as iron, ferrite and magnetite, and alloys of these metals with metals such as aluminum and lead can be used as the magnetic particles of the carrier. Ferrite particles are particularly preferable. The magnetic particles preferably have a volume average particle size of 15 to 100 μm, more preferably 25 to 80 μm.
[0144]
The volume average particle diameter of the carrier can be typically measured by a laser diffraction particle size distribution measuring apparatus “HELOS” (manufactured by SYMPATEC) equipped with a wet disperser.
[0145]
The carrier is preferably a carrier in which magnetic particles are further coated with a resin, or a so-called resin dispersion type carrier in which magnetic particles are dispersed in a resin. The resin composition for coating is not particularly limited, and for example, olefin resin, styrene resin, styrene-acrylic resin, silicone resin, ester resin, or fluorine-containing polymer resin is used. In addition, the resin for constituting the resin-dispersed carrier is not particularly limited, and a known resin can be used. For example, a styrene-acrylic resin, a polyester resin, a fluorine resin, a phenol resin, or the like is used. be able to.
[0146]
【Example】
Next, the present invention will be described more specifically with reference to examples.
[0147]
(Latex Preparation Example 1)
A solution prepared by dissolving 7.08 g of an anionic active agent (sodium dodecylbenzenesulfonate: SDS) in ion-exchanged water (2760 g) in a 5000 ml separable flask equipped with a stirrer, temperature sensor, condenser, and nitrogen introducing device. Add. The internal temperature was raised to 80 ° C. while stirring at a stirring speed of 230 rpm under a nitrogen stream. On the other hand, 72.0 g of the exemplified compound (19) was added to a monomer composed of 115.1 g of styrene, 42.0 g of n-butyl acrylate, and 10.9 g of methacrylic acid, and heated to 80 ° C. and dissolved to prepare a monomer solution. Here, the above heated solution was mixed and dispersed by a mechanical disperser having a circulation path to produce emulsified particles having a uniform dispersed particle size. Subsequently, a solution in which 0.84 g of a polymerization initiator (potassium persulfate: KPS) was dissolved in 200 g of ion-exchanged water was added, and the mixture was heated and stirred at 80 ° C. for 3 hours to prepare latex particles. Subsequently, a solution obtained by further dissolving 7.73 g of a polymerization initiator (KPS) in 240 ml of ion-exchanged water was added, and after 15 minutes, 383.6 g of styrene, 140.0 g of n-butyl acrylate, 36. A mixed solution of 4 g and 13.7 g of t-dodecyl mercaptan was added dropwise over 126 minutes. After completion of dropping, the mixture was heated and stirred for 60 minutes and then cooled to 40 ° C. to obtain latex particles.
[0148]
This latex particle is designated as Latex 1.
(Latex Preparation Example 2)
Latex was obtained in the same manner as in Latex Preparation Example 1 except that the amount of Example Compound (19) added was 60.0 g. This is called latex 2.
[0149]
(Latex Preparation Example 3)
Latex was obtained in the same manner as in Preparation Example 1 except that the amount of Example Compound (19) added was 96.0 g. This is designated as Latex 3.
[0150]
(Latex Preparation Example 4)
A latex was obtained in the same manner as in Latex Preparation Example 1 except that the amount of Example Compound (19) added was 120.0 g. This is latex 4.
[0151]
(Latex Preparation Example 5)
Latex was obtained in the same manner as in Preparation Example 1 except that Exemplified Compound (18) was used instead of Exemplified Compound (19). This is designated as Latex 5.
[0152]
(Latex Preparation Example 6)
Latex was obtained in the same manner as in Preparation Example 1 except that Exemplified Compound (17) was used instead of Exemplified Compound (19). This is designated as latex 6.
[0153]
(Latex Preparation Example 7)
Latex was obtained in the same manner as in Preparation Example 1 except that Exemplified Compound (8) was used instead of Exemplified Compound (19) and the addition amount was 120.0 g. This is designated as Latex 7.
[0154]
(Latex Preparation Example 8)
A latex was obtained in the same manner as in Latex Preparation Example 1 except that the amount of potassium persulfate added during the production of the high molecular weight product (at the initial polymerization) was 0.42 g. This is designated as Latex 8.
[0155]
(Latex Preparation Example 9)
Latex was obtained in the same manner as in Preparation Example 1 except that the amount of potassium persulfate added during the production of the low molecular weight product (during the second stage polymerization) was 9.276 g. This is designated as latex 9.
[0156]
(Latex Preparation Example 10)
Latex was obtained in the same manner as in Preparation Example 1 except that the amount of t-dodesil mercaptan added during production of the low molecular weight product (during the second stage polymerization) was 16.44 g. This is latex 10.
[0157]
(Latex Preparation Example 11)
A solution prepared by previously dissolving 8.4 g of an anionic active agent (sodium dodecylbenzenesulfonate: SDS) in ion-exchanged water (2760 g) in a 5000 ml separable flask equipped with a stirrer, temperature sensor, condenser, and nitrogen introducing device. Add. The internal temperature was raised to 80 ° C. while stirring at a stirring speed of 230 rpm under a nitrogen stream. On the other hand, 86.4 g of the exemplified compound (19) was added to a monomer composed of 138.1 g of styrene, 50.4 g of n-butyl acrylate, and 13.1 g of methacrylic acid, and heated to 80 ° C. to dissolve, thereby preparing a monomer solution. Here, the above heated solution was mixed and dispersed by a mechanical disperser having a circulation path to produce emulsified particles having a uniform dispersed particle size. Subsequently, a solution in which 0.84 g of a polymerization initiator (potassium persulfate: KPS) was dissolved in 200 g of ion-exchanged water was added, and the mixture was heated and stirred at 80 ° C. for 3 hours to prepare latex particles. Subsequently, a solution obtained by dissolving 6.0 g of a polymerization initiator (KPS) in 240 ml of ion-exchanged water was added, and after 15 minutes, 306.9 g of styrene, 112.0 g of n-butyl acrylate, 29. A mixed liquid of 12 g and 10.96 g of t-dodecyl mercaptan was dropped over 120 minutes. After completion of dropping, the mixture was heated and stirred for 60 minutes and then cooled to 40 ° C. to obtain latex particles.
[0158]
This latex particle is designated as Latex 11.
(Latex Preparation Example 12)
A solution prepared by dissolving 5.6 g of an anionic active agent (sodium dodecylbenzenesulfonate: SDS) in ion-exchanged water (2760 g) in a 5000 ml separable flask equipped with a stirrer, temperature sensor, condenser, and nitrogen introducing device. Add. The internal temperature was raised to 80 ° C. while stirring at a stirring speed of 230 rpm under a nitrogen stream. On the other hand, 57.6 g of the exemplary compound (19) was added to a monomer composed of 92.1 g of styrene, 33.6 g of n-butyl acrylate, and 8.7 g of methacrylic acid, and heated to 80 ° C. to dissolve, thereby preparing a monomer solution. Here, the above heated solution was mixed and dispersed by a mechanical disperser having a circulation path to produce emulsified particles having a uniform dispersed particle size. Next, a solution in which 0.6 g of a polymerization initiator (potassium persulfate: KPS) was dissolved in 200 g of ion-exchanged water was added, and the mixture was heated and stirred at 80 ° C. for 3 hours to produce the desired latex particles. Subsequently, a solution in which 9.1 g of a polymerization initiator (KPS) was further dissolved in 240 ml of ion-exchanged water was added, and 15 minutes later, 498.7 g of styrene, 182.0 g of n-butyl acrylate, 47. A mixed solution of 3 g and 17.8 g of t-dodecyl mercaptan was added dropwise over 120 minutes. After completion of dropping, the mixture was heated and stirred for 60 minutes and then cooled to 40 ° C. to obtain latex particles.
[0159]
This latex particle is designated as latex 12.
(Toner preparation example)
Production of colored particles 1Bk
Sodium n-dodecyl sulfate = 9.2 g is dissolved in 160 ml of ion-exchanged water with stirring. Under stirring, 20 g of Legal 330R (carbon black manufactured by Cabot Corporation) was gradually added, and then dispersed using CLEARMIX. As a result of measuring the particle diameter of the dispersion using an electrophoretic light scattering photometer ELS-800 manufactured by Otsuka Electronics Co., Ltd., the mass average diameter was 112 nm. This dispersion is referred to as “colorant dispersion 1”.
[0160]
1250 g of the above-mentioned “Latex 1”, 2000 ml of ion-exchanged water, and “Colorant dispersion 1” are placed in a 5-liter four-necked flask equipped with a temperature sensor, a cooling tube, a nitrogen introducing device, and a stirring device and stirred. After adjusting to 30 ° C., 5 mol / l aqueous sodium hydroxide solution was added to this solution to adjust the pH to 10.0. Subsequently, an aqueous solution in which 52.6 g of magnesium chloride hexahydrate was dissolved in 72 ml of ion-exchanged water was added at 30 ° C. for 10 minutes with stirring. Thereafter, after standing for 3 minutes, temperature increase is started and the temperature is increased to 90 ° C. in 6 minutes (temperature increase rate = 10 ° C./min). In that state, the particle size was measured with a Coulter Counter TA-II, and when the volume average particle size reached 6.5 μm, an aqueous solution in which 115 g of sodium chloride was dissolved in 700 ml of ion-exchanged water was added to stop particle growth. Further, the mixture is heated and stirred at a liquid temperature of 90 ° C. ± 2 ° C. for 6 hours to cause salting out / fusion. Then, it cooled to 30 degreeC on the conditions of 6 degreeC / min, hydrochloric acid was added, pH was adjusted to 2.0, and stirring was stopped. The produced colored particles were filtered, washed repeatedly with ion-exchanged water, and then dried with hot air at 40 ° C. to obtain colored particles. The colored particles obtained as described above are referred to as “colored particles 1Bk”.
[0161]
“Latex 1” was used, and “colored particles 1Y” to “colored particles 1C” were obtained in the same manner except that carbon black was changed to other colorants as shown below. These are designated as “1Bk / 1Y / 1M / 1C” as a group of colored particles.
[0162]
Colored particles 1Y
C. instead of carbon black I. Colored particles were obtained in the same manner except that CI Pigment Yellow 185 was used. This is designated as “colored particles 1Y”.
[0163]
Colored particles 1M
C. instead of carbon black I. Colored particles were obtained in the same manner except that CI Pigment Red 122 was used. This is designated as “colored particles 1M”.
[0164]
Colored particles 1C
C. instead of carbon black I. Colored particles were obtained in the same manner except that CI Pigment Blue 15: 3 was used. This is designated as “colored particles 1C”.
[0165]
As the colored particles 2 group, latex 2 is used, and latex 12 is used as a whole, as shown in Table 1 as a whole, colored particles 1 group “1Bk / 1Y / 1M / 1C” to colored particles 12 group “12Bk / 12Y / 12M /”. 12C "was prepared.
[0166]
[Table 1]

[0167]
In the following, examples for producing colored particles for comparison will be shown.
Comparative Colored Particle Production Example 1: Example of Suspension Polymerization Method
Colored particles for comparison 1Bk
To a four-necked flask equipped with a high-speed stirrer (TK homomixer), 710 parts by mass of ion-exchanged water and 450 parts by mass of a 0.1 mol / liter trisodium phosphate aqueous solution are added, heated to 65 ° C., and rotated at 12,000 rpm. Under the above stirring conditions, 68 parts by mass of 1.0 mol / liter calcium chloride aqueous solution was gradually added to prepare an aqueous dispersion medium containing a dispersion containing colloidal tricalcium phosphate. Next, 165 parts by mass of styrene monomer, 35 parts by mass of n-butyl acrylate, 14 parts by mass of carbon black (Regal 330R) were added, and 60 parts by mass of the exemplified compound (19) was added to the dispersion dispersed with a sand grinder, at 80 ° C. Dissolved. A solution obtained by adding 10 parts by mass of 2,2′-azobis (2,4-dimethylvaleronitrile) as a polymerization initiator to this solution is gradually added to the aqueous dispersion medium under stirring conditions at a rotational speed of 12000 rpm. A solution containing the monomer was dispersed in Next, the TK homomixer was replaced with a normal stirring blade, and a polymerization reaction was performed for 10 hours under a nitrogen stream at 65 ° C. and 200 rpm stirring conditions. At the end of the polymerization reaction, hydrochloric acid was added to remove tricalcium phosphate as a dispersion stabilizer, followed by filtration, washing and drying to prepare colored particles. This is referred to as “comparative colored particle 1Bk”.
[0168]
Colored particles for comparison 1Y
C. instead of carbon black I. Colored particles were obtained in the same manner except that CI Pigment Yellow 185 was used. This is referred to as “comparative colored particles 1Y”.
[0169]
Colored particles for comparison 1M
C. instead of carbon black I. Colored particles were obtained in the same manner except that CI Pigment Red 122 was used. This is referred to as “comparative colored particles 1M”.
[0170]
Colored particles for comparison 1C
C. instead of carbon black I. Colored particles were obtained in the same manner except that CI Pigment Blue 15: 3 was used. This is referred to as “comparative colored particles 1C”.
[0171]
Comparative colored particle production example 2: Example of grinding method
Colored particles for comparison 2Bk
Styrene acrylic resin: 100 parts by mass
Carbon black (Regal 330R): 10 parts by mass
Exemplary compound (19): 10 parts by mass
The above composition was dry-mixed with a Henschel mixer, melt-kneaded with a twin-screw extruder, then pulverized with a mechanical pulverizer, and classified with an airflow classifier to obtain colored particles. This is referred to as “comparative colored particle 2Bk”.
[0172]
Colored particles for comparison 2Y
C. instead of carbon black I. Colored particles were obtained in the same manner except that CI Pigment Yellow 185 was used. This is designated as “Comparison Colored Particle 2Y”.
[0173]
Colored particles for comparison 2M
C. instead of carbon black I. Colored particles were obtained in the same manner except that CI Pigment Red 122 was used. This is referred to as “comparative colored particles 2M”.
[0174]
Colored particles for comparison 2C
C. instead of carbon black I. Colored particles were obtained in the same manner except that CI Pigment Blue 15: 3 was used. This is designated as “Comparison Colored Particle 2C”.
[0175]
The circularity, standard deviation, CV value, volume average particle diameter, and the like of these colored particles are shown in the following list.
[0176]
[Table 2]

[0177]
[Table 3]

[0178]
The above circularity is measured using FPIA-1000 under the conditions of sample analysis amount = 0.3 μL and 1500-5000 detection particles.
[0179]
Subsequently, each of the above colored particles 1 group “colored particles 1Bk / 1Y / 1M / 1C” to colored particles 12 group “colored particles 12Bk / 12Y / 12M / 12C” is hydrophobic silica (number average primary particle size = 12 nm, degree of hydrophobicity). = 68) and 1% by mass of hydrophobic titanium oxide (number average primary particle size = 20 nm, degree of hydrophobicity = 63) were added and mixed with a Henschel mixer to obtain a toner.
[0180]
These are designated as toner 1 group “toner 1Bk / 1Y / 1M / 1C” to toner 12 group “toner 12Bk / 12Y / 12M / 12C”. Similarly, a comparative toner 1 group “comparative toner 1Bk / 1Y / 1M / 1C” and a comparative toner 2 group “comparative toner 2Bk / 2Y / 2M / 2C” were produced.
[0181]
Note that there is no difference between colored particles and toner in terms of physical properties such as shape and particle size.
[0182]
[Table 4]

[0183]
Each of the above toners was mixed with a ferrite carrier having a volume average particle diameter of 60 μm coated with a silicone resin to prepare a developer having a toner concentration of 6%. Corresponding to the toner, "Developer 1Bk / 1Y / 1M / 1C" to "Developer 12Bk / 12Y / 12M / 12C" and "Comparative developer 1Bk / 1Y / 1M / 1C" and "Comparative developer 2Bk" / 2Y / 2M / 2C ".
[0184]
The developer prepared here was used for evaluation using the digital color copying machine shown in FIG.
[0185]
As the fixing method, a pressure-contact type heat fixing device as shown in FIG. 3 was used.
The specific configuration is as follows.
[0186]
Fixing roller (upper roller) is a cylindrical aluminum alloy with an inner diameter of 30 mm and a total width of 310 mm, coated with sponge silicone rubber (Asker C hardness = 30: thickness 8 mm) and having a heater with a built-in heater in the center. And a pressure roller (lower roller) having an iron cored bar with an inner diameter of 40 mm and an inner diameter of 40 mm, the surface of which is similarly composed of sponge-like silicone rubber (Asker C hardness = 30: thickness 2 mm). is doing. The nip width was 5.8 mm. Using this fixing device, the linear velocity of printing was set to 180 mm / sec. The nip width is 6.6 mm. The surface of the fixing roller is covered with a PFA tube (50 μm).
[0187]
Further, a web-type supply system impregnated with polydiphenyl silicone (having a viscosity of 10 Pa · s at 20 ° C.) was used as a cleaning mechanism of the fixing device.
[0188]
The fixing temperature was controlled by the surface temperature of the upper roller, and was set to a set temperature of 175 ° C. The amount of silicone oil applied was 0.6 mg / A4.
[0189]
As the developer, the developer 1 group “Developer 1Bk / 1Y / 1M / 1C” to the developer 12 group “Developer 12Bk / 12Y / 12M / 12C” and the comparative developer 1 group “Comparative developer” described above. 1Bk / 1Y / 1M / 1C ”and 2 groups of comparative developers“ Comparative developer 2Bk / 2Y / 2M / 2C ”were used in combination as Examples 1 to 12 and Comparative Examples 1 and 2, respectively.
[0190]
(Characteristic evaluation)
In the above evaluation, a full-color image (pixel rate = 50%) was formed, and the green secondary color chroma was evaluated. The measuring device used was “Macbeth Color Eye”, and the light source visual field ASTM-D65 2 ° was evaluated in the SCE mode. Also, the standard glossiness on the image was measured.
[0191]
[Table 5]

[0192]
It turns out that all of Examples 1 to 12 within the present invention have good characteristics.
[0193]
【The invention's effect】
According to the present invention, it is possible to provide a color image forming method, an image forming apparatus, and an electrostatic latent image developing toner used in the image forming method using a tandem method, which are stable over a long period and have high color reproducibility. .
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram illustrating an example of a color electrophotographic image forming apparatus.
FIG. 2 is a cross-sectional view of developing means (developing device or developing device) in an image forming unit.
FIG. 3 is a cross-sectional view showing an example of a fixing device (fixing device) used in the present invention.
[Explanation of symbols]
la, lb, lc, ld Electrostatic latent image carrier (electrophotographic photosensitive drum or photosensitive drum)
2a, 2b, 2c, 2d charger
6 Image support
7 Fixing part
17 Laser beam exposure equipment
2la, 2lb, 2lc, 2ld static elimination exposure lamp
22a, 22b, 22c, 22d Potential sensor
Pa, Pb, Pc, Pd Image forming unit

Claims (4)

A latent image is formed on a plurality of electrostatic latent image carriers, and the latent image formed on each electrostatic latent image carrier is developed with a developer containing toner of a different color for each electrostatic latent image carrier. In the toner for developing an electrostatic latent image used in an image forming method including a step of forming a visible image, transferring the visible image onto an image support, and fixing the image, the toner is at least bound A toner composed of a resin, a colorant, and a release agent, and further obtained by radical polymerization to particles obtained by dispersing and polymerizing a solution of a release agent in a radical polymerizable monomer in water. A toner obtained by polymerizing a monomer and obtained by salting out / fusion-bonding resin particles encapsulating a release agent in a binder resin and a colorant, An electrostatic latent image developing toner, wherein the agent is a compound represented by the following general formula.
General formula: R _1- (OCO-R ₂ ) _n
(Wherein, n is an integer from 2 to _4, R 1, _{R 2} represents a may have a substituent a hydrocarbon group, _{R 1} is a hydrocarbon group of 1 to 40 carbon atoms, _{R 2} Represents a hydrocarbon group having 16 to 30 carbon atoms.) A latent image is formed on a plurality of electrostatic latent image carriers, and the latent image formed on each electrostatic latent image carrier is developed with a developer containing toner of a different color for each electrostatic latent image carrier. In the image forming method comprising the steps of forming a visible image, transferring the visible image onto an image support, and fixing the transferred visible image, the toner comprises at least a binder resin and a colorant. A toner comprising a release agent, and particles obtained by dispersing and polymerizing a radical polymerizable monomer in which the release agent is dissolved in water and further polymerizing the radical polymerizable monomer. obtained by polymerizing, resin particles obtained by encapsulating a release agent in a binder resin, a toner obtained by the colorant is salted out / fused, the releasing agent is represented by the following general formula An image forming method, which is a compound represented by the following:
General formula: R _1- (OCO-R ₂ ) _n
(Wherein, n is an integer from 2 to _4, R 1, _{R 2} represents a may have a substituent a hydrocarbon group, _{R 1} is a hydrocarbon group of 1 to 40 carbon atoms, _{R 2} Represents a hydrocarbon group having 16 to 30 carbon atoms.)   3. The image forming method according to claim 2, wherein the visible image obtained by the development is temporarily transferred to an intermediate transfer member and further transferred onto an image support. A latent image is formed on a plurality of electrostatic latent image carriers, and the latent image formed on each electrostatic latent image carrier is developed with a developer containing toner of a different color for each electrostatic latent image carrier. In an image forming apparatus for performing an image forming method, comprising: a step of forming a visible image; a step of transferring the visible image onto an image support; and a step of fixing the transferred visible image. A toner comprising a binder resin, a colorant, and a release agent, and particles obtained by dispersing and polymerizing a radical polymerizable monomer in which the release agent is dissolved in water, A toner obtained by polymerizing a radically polymerizable monomer, obtained by salting out / fusion-bonding resin particles encapsulating a release agent in a binder resin and a colorant, An image forming apparatus, wherein the release agent is a compound represented by the following general formula.
General formula: R _1- (OCO-R ₂ ) _n
(Wherein, n is an integer from 2 to _4, R 1, _{R 2} represents a may have a substituent a hydrocarbon group, _{R 1} is a hydrocarbon group of 1 to 40 carbon atoms, _{R 2} Represents a hydrocarbon group having 16 to 30 carbon atoms.)

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