JP3984757B2 - Yellow toner, method for producing the toner, and image forming method - Google Patents

Description

【００３１】
＜エステルワックスの構造式（２）＞
【化２】

【００３２】
＜エステルワックスの構造式（３）＞
【化３】

【００３３】
＜エステルワックスの構造式（４）＞
【化４】

【００３４】
＜エステルワックスの構造式（５）＞
【化５】

【００３５】
上記したような構造を有するエステルワックスの中でも、本発明のイエロートナーに特に好ましく用いられるのは、その硬度が０．５〜５．０であるものである。ここでいうエステルワックスの硬度とは、直径２０ｍｍφで厚さが５ｍｍの円筒形状のサンプルを作成した後、かかるサンプルについて、島津製作所製ダイナミック超微小硬度計（ＤＵＨ−２００）を用いて測定したビッカース硬度の値である。この際の測定条件は、０．５ｇの荷重で、負荷速度が９．６７ｍｍ／秒の条件で１０μｍ変位させた後に１５秒間保持し、この時に得られた打痕形状を測定してビッカース硬度を求める。このようにして求めた硬度が、０．５〜５．０の値を示すエステルワックスが、本発明のイエロートナーに好ましく用いられる。即ち、硬度が０．５未満の低軟化点物質（エステルワックス）を使用すると、トナーが、定着器の圧力依存性及びプロセススピード依存性が大きいものとなり易く、高温オフセット効果の発現が不充分となり易い。他方、その硬度が５．０を超えるものを使用すると、トナーが保存安定性に乏しいものとなり易く、又、離型剤自身の自己凝集力も小さいため、上記の場合と同様に、高温オフセット効果が不充分となり易い。
【００３６】
本発明のイエロートナーに使用する好ましいエステルワックスの具体例としては、下記化合物が挙げられる。
【００３７】
【化６】

【００３８】
【化７】

【００３９】
【化８】

【００４０】
【化９】

【００４１】
本発明のイエロートナー中には、荷電制御剤を含有させていてもよい。
トナーを負荷電性に制御する荷電制御剤としては下記の物質があり、いずれも本発明のイエロートナーを作製する場合に使用することができる。例えば、有機金属化合物、キレート化合物が有効であり、例えば、モノアゾ金属化合物、アセチルアセトン金属化合物、芳香族ハイドロキシカルボン酸、芳香族ダイカルボン酸系の金属化合物が挙げられる。他には、芳香族ハイドロキシカルボン酸、芳香族モノ及びポリカルボン酸及びその金属塩、無水物、エステル類、ビスフェノール等のフェノール誘導体類等が挙げられる。更に、尿素誘導体、含金属サリチル酸系化合物、含金属ナフトエ酸系化合物、ホウ素化合物、カリックスアレーン、ケイ素化合物、スチレン−アクリル酸共重合体、スチレン−メタクリル酸共重合体、スチレン−アクリル−スルホン酸共重合体、ノンメタルカルボン酸系化合物等が挙げられる。
【００４２】
又、トナーを正荷電性に制御する荷電制御剤としては下記の物質があり、いずれも本発明のイエロートナーを作製する場合に使用することができる。例えば、ニグロシン、及び、脂肪酸金属塩等による変性物、グアニジン化合物、イミダゾール化合物、トリブチルベンジルアンモニウム−１−ヒドロキシ−４−ナフトスルフォン酸塩、テトラブチルアンモニウムテトラフルオロボレート等の４級アンモニウム塩、及び、これらの類似体であるホスホニウム塩等のオニウム塩及びこれらのレーキ顔料、トリフェニルメタン染料及びこれらのレーキ顔料（レーキ化剤としては、リンタングステン酸、リンモリブデン酸、リンタングステンモリブデン酸、タンニン酸、ラウリン酸、没食子酸、フェリシアン化合物、フェロシアン化物等使用）、高級脂肪酸の金属塩；ジブチルスズオキサイド、ジオクチルスズオキサイド、ジシクロヘキシルスズオキサイド等のジオルガノスズオキサイド；ジブチルスズボレート、ジオクチルスズボレート、ジシクロヘキシルスズボレート等のジオルガノスズボレート類；が挙げられ、これらを単独で、或いは２種類以上を組み合わせて用いることができる。これらの中でも、特に、ニグロシン系、４級アンモニウム塩の如き荷電制御剤を好ましく用いることができる。
これらの荷電制御剤は、結着樹脂成分１００重量部に対して、０．０１〜２０重量部、より好ましくは０．５〜１０重量部の範囲で使用するのがよい。
【００４３】
上記のような構成を有する本発明のイエロートナーは、下記に説明する重合性単量体を含有する重合性単量体系を重合してトナーを得る本発明のイエロートナーの製造方法によって容易に得られる。本発明のイエロートナーの製造方法では、少なくとも１種以上の黄色顔料と少なくとも１種以上の黄色染料が含有された重合性単量体系を重合してトナーを製造する場合に、黄色顔料として、先に説明したような、白色紙上展色における色度が、Ｌ^*の値が６０．０乃至９５．０、ａ^*の値が−２５．０乃至−８．０、及びｂ^*の値が＋６０．０乃至＋１１５．０である黄色顔料を使用し、且つ、黄色染料として、白色紙上展色における色度が、Ｌ^*の値が６０．０乃至９５．０、ａ^*の値が−１２．０乃至＋１０．０、及びｂ^*の値が＋６０．０乃至＋１１５．０である黄色染料を使用する。
【００４４】
又、重合性単量体系を重合する具体的な方法としては、水系媒体中で重合性単量体を直接重合してトナーを得ることが好ましい。例えば、特公昭３６−１０２３１号公報、特公昭４３−１０７９９号公報及び特公昭５１−１４８９５号公報等に記載されているように、重合性単量体、上記の黄色顔料及び黄色染料を含む着色剤、重合開始剤、更に必要に応じて、架橋剤、荷電制御剤、その他添加剤を均一に溶解又は分散せしめて重合性単量体組成物とした後、この単量体組成物を分散安定剤を含有する連続相、例えば、水相中に適当な撹拌機を用いて分散させて、同時に重合反応を行わせることによって、直接、所望の粒径を有するトナー粒子が得られる。
上記のような重合法により得られたトナー粒子は、その形状が球状となるので、低光沢度の画像を得ようとする場合でも、光散乱を最小限に抑えることができ（つまりは色相変化を抑えることができ）、しかも透過性を損なうことが少ないので、本発明が目的とする効果をより向上させたトナーが得られる。
更に、水系媒体中で重合性単量体を直接重合させると、トナー粒子中に含有されるトナーの形成材料である着色剤や帯電制御剤等が、一端、単量体中に均一に分散或いは溶解した後、トナー粒子が形成されるため、着色剤のトナー粒子表面への露出が抑えられ、トナー粒子表面において、粉砕法よって得られたトナー粒子に比べ、均一な帯電挙動を示すようになる。
【００４５】
加えて、本発明で使用する上記した黄色の顔料や染料、更に、その好ましい形態において使用する低軟化点物質（離型剤）、更には、荷電制御剤等を重合性単量体中に分散させると、他の黄色の着色剤を使用した場合と比較して単量体系中における分散が特に安定しているため、同一の着色力を得るために必要な着色剤の添加量が少なくて済むため、結果として、透明性により優れたシャープな帯電を有するトナーが得られる。
【００４６】
又、粉砕法によってトナーを作製した場合においては、コールターカウンターにより測定した平均粒度が９μｍ以下になるに従って、従来では問題にならなかった使用原材料の均一分散性や効率のよい粉砕性、更には、シャープな粒度分布にトナーを分級することが極めて難しくなる傾向にある。これに対し、本発明のイエロートナーの製造方法では、従来の粉砕法を利用したトナーの製造方法では使用することができなかった低軟化点物質を多量に使用することができる等の材料の選択幅が広がる等の特徴を有しており、この点からも好ましい。
【００４７】
本発明で使用する先に挙げたような特定の色度を有する黄色顔料を用い、重合法によってトナーを製造する場合には、これらの顔料の重合性単量体中における解砕を容易にすることが好ましいが、このためには、単量体系中に分散させる前の黄色顔料の粒度を、先に説明したトナー粒子中における黄色顔料の好ましい分散粒径、即ち、個数平均径が０．０１〜０．７０μｍの範囲内にあるものを使用することが好ましい。具体的には、本発明のイエロートナーを重合法によって製造する場合に使用する黄色顔料としては、アルコール系有機溶媒中での粒度分布が、個数平均径で０．０１〜０．５０μｍの範囲内にあるものを使用することが好ましく、より好ましくは０．０１〜０．３０μｍの範囲内にあるものを使用する。
【００４８】
ここで使用するアルコール系有機溶媒中での粒度分布としては、具体的には、下記の方法で測定した。測定装置には、コールターカウンターＬＳ型（コールター社製）を用い、エタノール中へ、濃度が約２０〜４００ｐｐｍとなるような割合で測定対象の黄色顔料を添加し、超音波で６０秒分散後、測定して得られる個数分布を使用した。
【００４９】
本発明のイエローの製造方法では、上記したような黄色顔料と共に、下記に挙げるような結着樹脂を形成するための重合性単量体を使用する。即ち、重合法によって直接トナーを得る方法においては、従来公知の重合性単量体を好ましく用いることができるが、具体的には、例えば、スチレン、ｏ（ｍ−、ｐ−）−メチルスチレン、ｍ（ｐ−）−エチルスチレン等のスチレン系単量体；（メタ）アクリル酸メチル、（メタ）アクリル酸エチル、（メタ）アクリル酸プロピル、（メタ）アクリル酸ブチル、（メタ）アクリル酸オクチル、（メタ）アクリル酸ドデシル、（メタ）アクリル酸ステアリル、（メタ）アクリル酸ベヘニル、（メタ）アクリル酸２ーエチルヘキシル、（メタ）アクリル酸ジメチルアミノエチル、（メタ）アクリル酸ジエチルアミノエチル等の（メタ）アクリル酸エステル系単量体；ブタジエン、イソプレン、シクロヘキセン、（メタ）アクリロニトリル、アクリル酸アミド等のエン系単量体が好ましく用いられる。
【００５０】
そして、これらは、単独で、又は、一般的には、形成した樹脂の、出版物ポリマーハンドブック第２版III−Ｐ１３９〜１９２（Ｊｏｈｎ Ｗｉｌｅｙ＆Ｓｏｎｓ社製）に記載されている理論ガラス温度（Ｔｇ）が４０〜８５℃を示すように、上記したような重合性単量体を適宜に混合して用いる。即ち、理論ガラス転移温度が４０℃未満の樹脂を用いた場合には、トナーの保存安定性や現像剤の耐久安定性の面から問題が生じ、一方、理論ガラス転移温度が８５℃を超える樹脂を用いた場合は、トナー画像を定着させる際に、結晶性部分の残存による粒塊が画像上に生じてしまい、特にフルカラートナーの場合においては、ＯＨＰ画像の透明性を著しく低下させる傾向があり、高画質画像を形成するという目的を実現するという面からは、好ましくない。
【００５１】
本発明のイエロートナーは、重合法によって製造することが好ましいが、勿論、粉砕法によって製造することもできる。この場合に好適に用いられる結着樹脂としては、上記に挙げた単量体成分を組み合わせて得られるスチレン−アクリル系樹脂やマレイン酸共重合体、ポリエステル樹脂、エポキシ樹脂等の公知の材料が使用できる。特に、粉砕法を用いて本発明のイエロートナーを製造する場合には、本発明で目的とする分散性の維持や帯電特性の向上を図る等のため、ポリエステル樹脂を用いることが好ましい。
【００５２】
トナーを構成する結着樹脂の分子量は、ＧＰＣ（ゲルパーミエーションクロマトグラフィー）により測定できる。具体的なＧＰＣの測定方法としては、予め、測定対象のトナーをソックスレー抽出器を用いてトルエン溶剤で２０時間抽出を行った後、ロータリーエバポレーターでトルエンを留去せしめ、更に、低軟化点物質は溶解するが外殻樹脂は溶解し得ない有機溶剤、例えば、クロロホルム等を加えて充分に洗浄を行った後、ＴＨＦ（テトラヒドロフラン）に溶解した溶液をポア径が、０．３μｍの耐溶剤性メンブランフィルターでろ過して測定用サンプルを調製する。そして、上記で得られたサンプルを、ＧＰＣとしてウォーターズ社製の１５０Ｃを用い、カラム構成は、昭和電工製Ａ−８０１、８０２、８０３、８０４、８０５、８０６、８０７を連結したものを用い、標準ポリスチレン樹脂の検量線を用いて分子量分布を測定する。本発明のイエロートナーにおいては、上記のようにして得られるトナー中の樹脂成分の数平均分子量（Ｍｎ）が、５，０００〜１，０００，０００であり、重量平均分子量（Ｍｗ）と数平均分子量（Ｍｎ）との比（Ｍｗ／Ｍｎ）が、２〜１００であるような樹脂を用いることが好ましい。
【００５３】
本発明のイエロートナーにおいては、外殻樹脂中に、先に挙げたような多量に含有させる低軟化点物質を重合法によって内包化せしめ、コア−シェル構造を有するトナー粒子を形成させるために、先に挙げた重合性単量体成分の他に、更に極性樹脂を添加せしめてもよい。この際に用いられる極性樹脂としては、スチレンと（メタ）アクリル酸の共重合体、マレイン酸共重合体、ポリエステル樹脂、エポキシ樹脂等が好ましく用いられる。
【００５４】
本発明のイエロートナーにおいては、更に離型作用を付与するために、結着樹脂中に、先に述べたような構造式を有するエステルワックスに加えて、別の低軟化点物質を添加せしめてもよい。この際に用いられる低軟化点物質としては、特に、ＡＳＴＭ Ｄ３４１８−８に準拠して測定された熱分析の主体極大ピーク値が５０〜１８０℃を示す化合物が好ましい。即ち、極大ピーク値が５０℃未満であると低軟化点物質の自己凝集力が弱くなり、結果として、トナーの高温オフセット性が弱くなる。特に、フルカラー現像剤に用いるトナーの場合には好ましくない。一方、極大ピーク値が１８０℃を超えると、現状のところ、軟化点物質の結晶性や分散性が劣化するため、トナーの定着性や、画像の透明性の面から好ましくない。
【００５５】
この場合の低軟化点物質の極大ピーク値の温度測定は、例えば、パーキンエルマー社製のＤＳＣ−７を用い、装置検出部の温度補正はインジウムと亜鉛の融点を用いて行ない、熱量の補正については、インジウムの融解熱を用いて行なう。測定にあたっては、サンプルをアルミニウム製パンにセットし、対照用に同様の空パンをセットして、昇温速度１０℃／ｍｉｎ．で測定を行う。
【００５６】
上記のような熱特性を有する低軟化点物質としては、具体的には、例えば、パラフィンワックス、ポリオレフィンワックス、フィッシャートロピッシュワックス、アミドワックス、エステルワックス、高級脂肪酸、及びこれらのグラフト／ブロック化合物等を利用することができる。
【００５７】
本発明のイエロートナーの製造方法において直接重合方法を利用する場合には、重合性単量体系に重合開始剤を含有させることが好ましい。この際に使用する重合開始剤として、例えば、２，２’−アゾビスー（２，４−ジメチルバレロニトリル）、２，２’−アゾビスイソブチロニトリル、１，１’−アゾビス（シクロヘキサン−１−カルボニトリル）、２，２’−アゾビス−４−メトキシ−２，４−ジメチルバレロニトリル、アゾビスイソブチロニトリル等のアゾ系重合開始剤、ベンゾイルペルオキシド、メチルエチルケトンペルオキシド、ジイソプロピルペルオキシカーボネート、クメンヒドロペルオキシド、２，４−ジクロロベンゾイルペルオキシド、ラウロイルペルオキシド等の過酸化物系重合開始剤等を用いることができる。
【００５８】
これらの重合開始剤の添加量は、目的とする重合度により変化するが、一般的には、単量体に対し０．５〜２０重量％添加され用いられる。又、用いる重合開始剤の種類は、重合方法により若干異なるが、十時間半減期温度を参考に、上記に挙げたものを単独で、又は混合して利用すればよい。更に、重合度を適宜に制御するために、公知の架橋剤、連鎖移動剤、重合禁止剤等を更に添加して用いることも可能である。
【００５９】
本発明のイエロートナーの製造方法に、水性媒体中での重合法を利用する場合には、下記に挙げるような無機系及び有機系の化合物からなる分散剤を用いることができる。例えば、無機系の分散剤としては、リン酸三カルシウム、リン酸マグネシウム、リン酸アルミニウム、リン酸亜鉛、炭酸カルシウム、炭酸マグネシウム、水酸化カルシウム、水酸化マグネシウム、水酸化アルミニウム、メタケイ酸カルシウム、硫酸カルシウム、硫酸バリウム、ベントナイト、シリカ、アルミナ、磁性体、フェライト等が挙げられる。又、有機系化合物としは、例えば、ポリビニルアルコール、ゼラチン、メチルセルロース、メチルヒドロキシプロピルセルロース、エチルセルロース、カルボキシメチルセルロースのナトリウム塩、デンプン等が挙げられ、これらを水相に分散させて使用することができる。これらの分散剤は、重合性単量体１００重量部に対して０．２〜２．０重量部の範囲で使用することが好ましい。
【００６０】
更に、これら分散剤は、市販のものをそのまま用いてもよいが、細かい均一な粒度を有す分散粒子を得るために、分散媒中にて高速撹拌下にて、上記したような無機化合物を生成させて用いることもできる。例えば、リン酸三カルシウムのを用いる場合に、高速撹拌下において、リン酸ナトリウム水溶液と塩化カルシウム水溶液を混合することで、懸濁重合方法に好ましく用いることのできる均一に分散された微細な分散剤を得ることができる。又、上記において、生成させる分散剤の微細化のために、０．００１〜０．１重量部の界面活性剤を併用してもよい。この際に使用できる界面活性剤としては、具体的には、市販のノニオン、アニオン、カチオン型の界面活性剤を利用することができる。例えば、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、オレイン酸ナトリウム、ラウリル酸ナトリウム、ステアリン酸カリウム、オレイン酸カルシウム等が好ましく用いられる。
【００６１】
本発明のイエロートナーの製造方法に、直接重合方法を利用する場合には、以下の如き製造方法によって具体的にトナーを製造することが可能である。即ち、先ず、重合性単量体中に、特定の色度を有する黄色顔料及び黄色染料を含む着色剤、必要に応じて適宜に添加する低軟化物質からなる離型剤、荷電制御剤、重合開始剤その他の添加剤を加え、ホモジナイザーや超音波分散機等によって均一に溶解又は分散せしめた単量体系を、分散安定剤を含有する水系媒体中に、通常の撹拌機又はホモミキサー、ホモジナイザー等を用いて分散せしめる。この際、好ましくは、重合性単量体組成物の液滴が所望のトナー粒子のサイズとなるように、撹拌速度及び時間を調整して造粒する。更に、その後は、分散安定剤の作用により、粒子状態が維持され、且つ、粒子の沈降が防止される程度の撹拌を行えばよい。又、重合温度は４０℃以上、一般的には、５０〜９０℃の温度に設定して重合を行えばよい。又、重合反応後半に昇温してもよく、更に、トナー定着時の臭いの原因等となる未反応の重合性単量体、副生成物等を除去するために、反応後半、又は、反応終了後に一部水系媒体を留去してもよい。反応終了後、生成したトナー粒子を、洗浄・ろ過により回収し、乾燥してトナー粒子を得る。上記の懸濁重合法においては、通常、単量体系１００重量部に対して、水３００〜３，０００重量部を水系分散媒として使用することが好ましい。
【００６２】
各種のトナー特性付与を目的とした添加剤は、トナー中に、或いはトナーに添加した時の耐久性の点から、トナー粒子の体積平均径の１／５以下の粒径のものであることが好ましい。この場合の添加剤の粒径とは、電子顕微鏡におけるトナー粒子の表面観察により求めた平均粒径を意味する。これら特性付与を目的とした添加剤として、例えば、以下のようなものが挙げられる。
【００６３】
先ず、流動性付与剤としては、例えば、酸化ケイ素、酸化アルミニウム、酸化チタン等の金属酸化物、カーボンブラック、フッ化カーボン、シリカ等が挙げられるが、夫々、疎水化処理を行ったものがより好ましい。
【００６４】
研磨剤としては、チタン酸ストロンチウム、酸化セリウム、酸化アルミニウム、酸化マグネシウム、酸化クロム等の金属酸化物；窒化ケイ素等の窒化物；炭化ケイ素等の炭化物；硫酸カルシウム、硫酸バリウム、炭酸カルシウム等の金属塩が挙げられる。
【００６５】
滑剤としては、フッ化ビニリデン、ポリテトラフルオロエチレン等のフッ素系樹脂粉末：ステアリン酸亜鉛、ステアリン酸カルシウム等の脂肪酸金属塩；等が挙げられる。
【００６６】
荷電制御性粒子としては、酸化錫、酸化チタン、酸化亜鉛、酸化ケイ素、酸化アルミニウム等の金属酸化物；カーボンブラック等が挙げられる。
これら添加剤は、トナー粒子１００重量部に対して０．１〜１０重量部の範囲で用ることが好ましいが、更に好ましくは、０．１〜５重量部の範囲で用いるとよい。これら添加剤は、単独でも、又、複数併用してもよい。
【００６７】
上記で説明したような構成を有する本発明のイエロートナーは、一成分系現像剤として、或いは二成分系現像剤として使用することができる。例えば、一成分系現像剤として利用する場合には、例えば、磁性体をトナー中に含有せしめて磁性トナーとして用い、かかる磁性トナーを、現像スリーブ中に内蔵せしめたマグネットを利用して搬送及び帯電せしめて、静電潜像の現像に用いることができる。又、磁性体を含有しない非磁性トナーを用いたる一成分系現像剤の場合には、ブレード及びファーブラシを用いて、現像スリーブにて強制的に摩擦帯電し、スリーブ上にトナーを付着せしめることで搬送せしめる方法がある。
【００６８】
一方、一般的に利用されている二成分系現像剤として用いる場合には、本発明のイエロートナーをキャリアと混合して現像剤とする。この際に使用されるキャリアとしては特に限定されるものではないが、主として、鉄、銅、亜鉛、ニッケル、コバルト、マンガン、クロム元素からなる単独及び複合フェライト状態で構成される。飽和磁化、電気抵抗を広範囲にコントロールできる点からキャリア形状も重要であり、例えば、球状、扁平、不定形等のものを選択することが好ましい。更に、キャリア表面状態の微細構造、例えば、表面凸凹性をもコントロールしたものを使用することが好ましい。
【００６９】
従って、キャリアを作製する場合には、一般的に、上記に挙げたような無機酸化物を焼成、造粒することにより、予め、キャリアコア粒子を生成した後、粒子表面を樹脂によってコーティングする方法が用いられている。キャリアのトナーへの負荷を軽減する意味合いから、無機酸化物と樹脂を混練後、粉砕、分級して低密度分散キャリアを得る方法や、更には、直接、無機酸化物とモノマーとの混練物を水系媒体中にて懸濁重合せしめ、真球状分散キャリアを得る重合キャリアを得る方法等も利用することが可能である。
上記の中でも、キャリア粒子表面を樹脂等で被覆する系は、特に好ましい。その方法としては、樹脂等の被覆材を溶剤中に溶解、若しくは懸濁せしめて塗布してキャリア粒子表面に付着せしめる方法、単に粉体で混合する方法等、従来公知の方法がいずれも適用できる。
【００７０】
キャリア表面への固着物質としてはトナー材料により異なるが、例えば、ポリテトラフルオロエチレン、モノクロロトリフルオロエチレン重合体、ポリフッ化ビニリデン、シリコーン樹脂、ポリエステル樹脂、ジターシャーリーブチルサリチル酸の金属化合物、スチレン系樹脂、アクリル系樹脂、ポリアミド、ポリビニルブチラール、ニグロシン、アミノアクリレート樹脂、塩基性染料及びそのレーキ、シリカ微粉末、アルミナ微粉末等を、単独で或いは複数で用いるのが適当であるが、必ずしもこれに制約されない。
上記化合物の処理量は、一般には総量でキャリアに対して０．１〜３０重量％、好ましくは０．５〜２０重量％がよい。これらキャリアの平均粒径は、１０〜１００μｍ、好ましくは２０〜５０μｍを有することが好ましい。
【００７１】
キャリアの特に好ましい態様としては、Ｃｕ−Ｚｎ−Ｆｅの３元系のフェライトでキャリアコア粒子を作製し、その粒子表面をフッ素系樹脂とスチレン系樹脂の如き樹脂の組み合せ、例えば、ポリフッ化ビニリデンとスチレン−メチルメクアクリレート樹脂；ポリテトラフルオロエチレンとスチレン−メチルメタアクリレート樹脂、フッ素系共重合体とスチレン系共重合体；等を９０：１０〜２０：８０、好ましくは７０：３０〜３０：７０の比率の混合物としたもので、０．０１〜５重量％、好ましくは０．１〜１重量％程度の量コーティングし、２５０メッシュパス、４００メッシュオンのキャリア粒子が７０重量％以上ある上記平均粒径を有するコートフェライトキャリアであるものが挙げられる。フッ素系共重合体としては、フッ化ビニリデン−テトラフルオロエチレン共重合体（１０：９０〜９０：１０）が例示され、スチレン系共重合体としては、スチレン−アクリル酸２−エチルヘキシル（２０：８０〜８０：２０）、スチレン−アクリル酸２−エチルヘキシルメタクリル酸メチル（２０〜６０：５〜３０：１０〜５０）が例示される。
上記したコートフェライトキャリアは、粒径分布がシャープであり、本発明のイエロートナーに対して好ましい摩擦帯電性を与え、更に、電子写真特性を向上させる効果がある。
【００７２】
本発明のイエロートナーと上記したようなキャリアとを混合して二成分現像剤を調製する場合には、その混合比率を、現像剤中のトナー濃度として、２〜１５重量％、好ましくは４〜１３重量％にすると、通常良好な結果が得られる。トナー濃度が２重量％未満では画像濃度が低く実用不可となり、１５重量％を超える場合は、カブリや機内飛散を増加せしめ、現像剤の耐用寿命を短める。
【００７３】
更に、磁性特性が以下のようなキャリアを使用することが好ましい。磁気的に飽和させた後の１０００エルステッドにおける磁化の強さ（σ₁₀₀₀）が３０乃至３００ｅｍｕ／ｃｍ³であることが必要である。更に、高画質化を達成するためには、好ましくは１００乃至２５０ｅｍｕ／ｃｍ³のものを使用することが好ましい。磁化の強さが３００ｅｍｕ／ｃｍ³より大きい場合には、高画質なトナー画像が得られにくくなる。一方、３０ｅｍｕ／ｃｍ³未満であると、磁気的な拘束力も減少するためにキャリア付着を生じ易い。
【００７４】
次に、本発明の画像形成方法に用いる定着手段について説明する。
図２は、本発明で好適に使用し得る定着器の構成例を示す図である。図中の２３は定着ローラーであり、該定着ローラー２３には加圧ローラー２４が圧接しており、定着ローラー２３との間にニップ部を形成しつつ従動回転を行うようになっている。該定着ローラー２３は中空筒体の形態をなし、中空空間にはハロゲンヒータ２５が内臓されおり、定着に必要な熱供給がなされる。加圧ローラー２４はハロゲンヒータ２５により加熱される。ローラーの温度制御は、温度検知素子としてのサーミスタ２８を、定着ローラー２３の非通紙領域に、若しくは加圧ローラー２４にサーミスタ２８を接触配置させ、その検知温度に伴う抵抗値変化によりローラーの表面温度を検知し、制御装置（図示せず）により、ローラー表面温度が所定値となるようにハロゲンヒータ２５の電流制御を行っている。
【００７５】
以上のような装置において、未定着転写材はガイド６２により案内されて右方よりニップ部に進入し、定着ローラー２３の表面により加圧及び加熱を受け、定着された後、排紙される。２９は、定着された転写材と定着ローラー２３又は加圧ローラー２４との分離爪である。
【００７６】
定着ローラー２３の構成は、カラー画像の単色〜４色の多重トナー１の厚み（数〜数十μｍ）に追従するために、アルミニウム等の芯軸に弾性層を数十μｍ以上設けることが必要である。弾性が小さいとトナー凹部の未定着やトナーのつぶれによる解像低下をもたらす。上記弾性層の材質としては、メチル系、メチルビニル系の液体シリコーンゴムＲＴＶ、ＬＴＶタイプのものが弾性を備えているので好適である。表層には、上記のＲＴＶ、ＬＴＶを用いて、その下層に熱に強いＨＴＶの層を設け、表層裏面の熱劣化や剥がれを防いだ多層構成としたものを用いてもてもよい。
後述する本発明の実施例及び比較例では、アルミニウム芯金２１上に、ゴム硬度（アスカーＣ）１５度のジメチルシリコーンゴムのＬＴＶタイプの弾性層２２を２．５ｍｍ設け、その上にＰＦＡチューブ層６３を５０μｍ設けたものを４６ｍｍφに成形して用いた。この時、定着ローラー２３の製品硬度はアスカーＣで６０度であった。尚、弾性層材料に、メチルフェニル系シリコーンゴムを用いることもできる。
【００７７】
加圧ローラー２４の構成は、上記の定着ローラー２３に比べて弾性が小さくてもよいので単純化することが可能であり、アルミニウム芯軸にＨＴＶ、フッ素ゴム等の層を設けるのみでもよい。勿論、定着ローラーと略同一の構成のものを用いてもよい。
後述する本発明の実施例及び比較例では、加圧ローラー２４として、アルミニウム芯金２１上に、ゴム硬度（アスカーＣ）１５度のジメチルシリコーンゴムのＬＴＶタイプの弾性層を２２を１．５ｍｍ設け、その上にＰＦＡチューブ層６３を５０μｍ設けたものを、４６ｍｍφに成形して用いた。この時、製品硬度はアスカーＣで６０度であった。尚、定着ローラー、加圧ローラーの構成材料であるゴムとしては、メチルフェニル系シリコーンゴムを用いたものでもよい。
【００７８】
後述する本発明の実施例及び比較例では、上記のような構成を有する定着器を用い、その定着温度を１８０℃でリップル±３℃以内とし、加圧力は４０〜６０ｋｇｆとした。
【００７９】
次に、本発明で使用した各種測定方法について述べる。
［顔料及び染料の帯電量測定］
顔料及び染料の帯電量は、顔料又は染料０．５重量部に対し、樹脂コーティングされたフェライトキャリア９９．５重量部を混合したものを、常温常圧下に２４時間放置後、やよい振とう機により２分間振とうした後、下記の要領で測定した。尚、この際に使用したフェライトキャリアとしては、Ｃｕ−Ｚｎ−Ｆｅの三元系のフェライトコア（Ｆｅ約５０％、Ｃｕ約１０％、Ｚｎ約１０％）に対して、ポリフッ化ビニリデンとスチレン−メチルメタクリレート共重合体を５０：５０の割合で混合したものを約１重量％コートして作製し、２５０メッシュパス、３５０メッシュオンが７０重量％以上になるようにしたものを使用した。
【００８０】
図１に、トナーのトリボ電荷量を測定する帯電量測定装置の説明図を示した。先ず、底に５００メッシュのスクリーン１０３のある金属製の測定容器１０２に、摩擦帯電量を測定しようとするトナーとキャリアの混合物を５０〜１００ｍｌ容量のポリエチレン製のビンに入れ、５〜１０分間手で振とうし、該混合物（現像剤）約０．５〜１．５ｇを入れ、金属製のフタ１０４をする。このときの測定容器１０２全体の重量を秤り、その値をＷ₁（ｇ）とする。次に、吸引機１０１（測定容器１０２と接する部分は少なくとも絶縁体）において、吸引口から吸引し、風量調節弁１０６を調整して真空計１０５の圧力を２５０ｍｍＡｑとする。この状態で充分、好ましくは２分間吸引を行ってトナーを吸引除去する。このときの電位計１０９の電位をＶ（ボルト）とする。ここで１０８は、コンデンサーであり、容量をＣ（μＦ）とする。次に、吸引後の測定容器全体の重量を秤りＷ_２（ｇ）とする。このトナーの摩擦帯電量（ｍＣ／ｋｇ）は、上記で測定した値を用いて下式の如く計算される。測定結果を、表１に示した。
【００８１】
【数１】

【００８２】
［顔料及び染料の展色及び色度測定方法］
測定対象の顔料又は染料０．５重量部をトルエン３０重量部に混合し、１ｍｍ径のガラスビーズ３０重量部の存在下、ペイントシェーカーを用い、１２時間分散を行った。その後、Ｓｔ／ＢＡ樹脂（Ｓｔ／ＢＡ比が８０／２０、Ｔｇ７０度、Ｍｗ＝１０万、Ｍｎ＝２万）１０重量部を添加した後、再度、３時間の分散を行った。このようにして得られた分散溶液を、標準隠ぺい率試験紙（日本テストパネル工業社製）にＮｏ．１６バーコーターを用いて塗布して、測定用の試験紙を作成した。
得られた試験紙の白色部展色画像の明度Ｌ^*、ａ^*、ｂ^*、彩度Ｃ^*、色相角ｈ^*を、Ｘ−ＲＩＴＥ ＳＰ６８（Ｄ６５、視野角２度；Ｘ−ＲＩＴＥ社製）を使用し測定した。その結果を、表１に示した。
【００８３】
［低光沢画像の色彩評価方法］
トナー７重量部に対し、アクリル樹脂コーティングされたフェライトキャリア９３重量部を混合して現像剤を作成する。次に、得られた現像剤を用いて、定着器部分を図２に示すような定着器に変更して改造したキヤノン製フルカラー複写機ＣＬＣ７００改造機にて、具体的には、定着器の定着温度を可変とし、上下ローラーの材質をフッ素系とし、定着オイル塗布機構を省くよう改造した改造機で潜像を転写材上に転写し、画像を得た。
このときの定着条件は、転写材として光沢度４の坪量９９ｇ／ｍ²の紙を用い、トナーのり量０．５〜０．７ｍｇ／ｃｍ²の単色ベタ画像を得て、得られた画像を入射角７５度で測定した光沢度が１５〜２０になるよう定着温度を調整した。
又、各色の濃度条件は、コダック社製のグレースケールとカラーパッチを原稿とし、フルカラーコピー画像でグレースケールがなるべく忠実に再現できるように調整し、イエロー（Ｙ）単色コピーの最高濃度が１．１以上となるように濃度調節した。
そして、上記状態のキヤノン製フルカラー複写機ＣＬＣ７００改造機で、イエロー（Ｙ）シアン（Ｃ）の重ね合わせ画像であるグリーン（Ｇ）、及び、イエロー（Ｙ）マゼンタ（Ｍ）の重ね合わせであるレッド（Ｒ）について光沢度２０〜２５の定着条件で出し、このとき各色の最高濃度で重なり合った部分をコダック社製のカラーパッチとの色調差で評価した。
【００８４】
評価については５段階で行い、画像の明度Ｌ^*、彩度Ｃ^*、色相角ｈ^*についてＣＭＣ（１：１）の色度差式を導入し、比較例１の値を１００としたときのΔＥ（色度差）の値を求め、下記の基準で評価した。得られた結果を、表２−１に示した。
× ：ΔΕ＞１００
△ ：９０＜ΔＥ≦１００
○△：７０＜ΔＥ≦９０
○ ：ΔＥ≦７０
ＣＭＣの式とはＪｏｕｒｎａｌ ｏｆ ｔｈｅ Ｓｏｃｉｅｔｙ ｏｆ Ｄｙｅｒｓ ａｎｄ Ｃｏｌｏｕｒｉｓｔｓ、１００、１２８（１９８４）に提案されている色度式であり、明度Ｌ^*、彩度Ｃ^*、色相角ｈ^*に視感の補正を加えて評価するものであり、下記式で示される。
【００８５】
【数２】

尚、画像の明度Ｌ^*、彩度Ｃ^*、色相角ｈ^*の測定は、Ｘ−ＲＩＴＥ ＳＰ６８（Ｄ６５、視野角２度；Ｘ−ＲＩＴＥ社製）を使用した。
【００８６】
又、着色力については、入射角７５度で測定した光沢度１５〜２０のべた画像部を反射濃度計ＲＤ−９１８（マクベス社製）で測定した。光沢度計に、ＰＧ−３Ｇ（日本電色工業社製；入射角７５度）を用いて測定した。
耐光性については、フェードメーター（カーボンアーク灯）で６３度６０時間の照射後、退色度合いを観察してランク付けを行った。
【００８７】
［トランスペアレンシー透過画像評価方法］
トランスペアレンシーシート画像の透過率は以下の如く評価する。
フルカラー複写機（ＣＬＣ７００；キヤノン社製）改造機を使用して、トランスペアレンシーシート上（ＣＧ３７００：３Ｍ製）に温度２３度／湿度６０％ＲＨの環境下で、現像コントラスト３２０Ｖにて現像転写し、階調を有する未定着トナー画像を得た。得られたトナー画像を、定着ローラーの表面がフッ素系樹脂である外部定着器（図２に記載の構成）（オイル塗布機能なし；ローラー径４０φ）にて、定着温度１８０度、プロセススピード３０ｍｍ／ｓｅｃで定着し、定着画像を得た。そして、得られた定着画像の画像濃度０．４〜０．６の箇所の透過率を測定した。
【００８８】
透過率の測定には、島津自己分光光度計ＵＶ２２００（島津製作所社製）を使用した。トランスペアレンシーシート単独の透過率を１００％とし、６００ｎｍでの最大吸収波長における透過率を測定した。尚、下記の基準で評価し、その結果を、表２−１に示した。
○：透過率が、７５％以上
◯△：透過率が、６５％以上７５％未満
△：透過率が、５５％以上６５％未満
×：透過率が、５５％未満
【００８９】
又、透過光の色空間測定については、得られた画像をオーバーヘッドプロジェクター（ＯＨＰ：３Ｍ社製 ９５５０）にて透過画像とし、白色壁面に投影した画像を、分光放射輝度計（フォトリサーチ社製 ＰＲ６５０）にて測定した。そして、その白色壁面に投影した画像の色相角ｈ^*（ＯＨＰ）と、先に測定した紙上におけるべた部の色相角ｈ^*（紙）との色相角差Δｈ^*を下記に示すように定義して、５段階評価して、表２−１に示した。
× ：Δｈ^*＞２０
△×：１５＜Δｈ^*≦２０
△ ：１０＜Δｈ^*≦１５
○△：５＜Δｈ^*≦１０
○ ：Δｈ^*≦５
【００９０】
［連続通紙の画像評価方法］
フルカラー複写機（ＣＬＣ７００；キヤノン社製）改造機を使用して、高温高湿Ｈ／Ｈ（温度３０度／湿度８０％ＲＨ）及び常温低湿Ｎ／Ｌ（温度２３度／湿度５％ＲＨ）の環境下で、転写材であるＣＬＣ用紙（８０ｇ紙）上に、現像コントラスト３２０Ｖにて現像転写し、画像面積比率５％画像を形成させ５万枚連続通紙をした後に、初期画像と耐久画像において、画像濃度と、白べた部の紙上かぶりの測定、及び現像剤の帯電量を、下記の方法で測定し、評価を行なった。
【００９１】
（画像濃度について）
上述の着色力測定の方法に準拠して測定し、その測定値を表２−２及び表２−３に示した。
【００９２】
（かぶりの測定について）
カブリの測定は、ＲＥＦＬＥＣＴＯＭＥＴＥＲ ＭＯＤＥＬ ＴＣ−６ＤＳ（東京電色社製）を用い測定した。イエロートナー画像ではブルーフィルターを使用し、下記式により算出し、その測定値を表２−２及び表２−３に示した。かぶり値は少ない方が良好であることを意味している。
【数３】

【００９３】
（帯電量について）
上述の帯電量測定の方法に準拠して測定し、その測定値を表２−２及び表２−３に示した。
【００９４】
【実施例】
以下、実施例、参考例及び比較例を挙げて、本発明を更に具体的に説明する。
＜実施例１＞
先ず、０．１ＭのＮａ₃ＰＯ₄水溶液と１．０ＭのＣａＣｌ₂水溶液を用意する。高速撹拌装置ホモミキサーを備えた２リットル用四つ口フラスコ中に、イオン交換水７１０重量部と、０．１Ｍ−Ｎａ₃ＰＯ₄水溶液５５０重量部を添加した後、回転数を１０，０００回転に調整しつつ６５℃に加温せしめた。次に、この中に、１．０Ｍ−ＣａＣｌ₂水溶液８０重量部を徐々に添加していき、微細な難水溶性分散剤Ｃａ₃(ＰＯ₄)₂を含む水系分散媒を調製した。
【００９５】
一方、分散質系は、下記のようにして調製した。
・スチレン単量体 １６０重量部
・ｎ−ブチルアクリレート単量体 ４０重量部
・着色剤１ クロモフタルイエロー３Ｇ チバスペシャリティーケミカルズ社製
［Ｃ．Ｉ．ピグメントイエロー９３（平均粒径０．０９μｍ）］ ８重量部
・着色剤２ オラセットイエローＧＨＳ チバスペシャリティーケミカルズ社製
［Ｃ．Ｉ．ソルベントイエロー１６３］ ６重量部
・飽和ポリエステル ８重量部
・サリチル酸金属化合物 ４重量部
・ジビニルベンゼン ０．２重量部
・離型剤＜モノエステルワックス：Ｍｗ＝６５０、Ｍｎ＝５００、ＳＰ値＝
９．０、融点６５℃、溶融粘度９．２（ｍ・ｐａ・ｓ）＞ ３０重量部
上記組成からなる混合物を、アトライターを用いて３時間分散させた後、重合開始剤である２，２’−アゾビス（２，４−ジメチルバレロニトリル）５重量部を添加して、分散物を調製した。
【００９６】
上記で調製した分散物を、先に調製した水系分散媒中に投入して、回転を１０，０００ｒｐｍに調節しつつ１５分間造粒した。その後、高速撹拌器からプロペラ撹拌羽根に撹拌器を変え、３５０ｒｐｍで撹拌しつつ、内温を７０℃で重合反応を計８時間継続させてスラリーを得た。重合終了後、スラリーを冷却し、希塩酸を添加して分散剤を除去せしめた。更に、洗浄した後、乾燥を行うことで本実施例のイエロートナーを得た。次に、得られたトナーに疎水化処理酸化チタンを２％の割合で外添し、流動性に優れた本実施例のイエロートナーを得た。
【００９７】
上記で得られたトナー７重量部に対し、アクリル樹脂コーティングされたフェライトキャリア９３重量部を混合して、二成分系現像剤を調製した。先に述べたような構成のキヤノン製フルカラー複写機ＣＬＣ７００改造機にて、画像及びトランスペアレンシー画像を得た。
得られた画像について評価を行ったところ、表２−１に示したように、紙上の画像とトランスペアレンシー透過画像との間に色相角の変化は殆どなく、又、ＯＨＰ透明性にも優れたものであった。
【００９８】
又、上記で行なった分散系を調製する際に添加する着色剤を１種類にし、Ｃ．Ｉ．ピグメントブルー１５：３を１４重量部に変更した以外は上記と同様の方法でシアントナーを製造した。得られたシアントナーと本実施例のイエロートナーを用い、これらの２次色であるグリーン画像を形成し、グリーン画像の再現性を確認したところ、鮮明なグリーン画像及びトランスペアレンシー透過画像が得られた。
【００９９】
更に、添加する着色剤をＣ．Ｉ．ピグメントレッド１２２を１４重量部に変更した以外は、同様の方法でマゼンタトナーを製造した。得られたマゼンタトナーと本実施例のイエロートナーを用い、これらの２次色であるレッドの再現性を確認したところ、鮮明なレッド画像及びトランスペアレンシー透過画像が得られた。
【０１００】
＜実施例２＞
実施例１で用いた処方の中で、着色剤の処方を下記のように変更した以外は総て実施例１と同様にして、本実施例のイエロートナーを製造した。
・着色剤１ クロモフタルイエロー８GN チバスペシャリティーケミカルズ社製
［Ｃ．Ｉ．ピグメントイエロー１２８（平均粒径０．１４μｍ）］６重量部
・着色剤２ オラセットイエローＧＨＳ チバスペシャリティーケミカルズ社製
［Ｃ．Ｉ．ソルベントイエロー１６３］ ８重量部
上記で得られた本実施例のイエロートナーについて、実施例１と同様の方法で画像を形成し、各評価を行なった。この結果、表１〜表２に示したように良好な結果が得られた。
【０１０１】
＜実施例３＞
実施例１で用いた処方の中で、着色剤の処方を下記のように変更した以外は総て実施例１と同様にして、本実施例のイエロートナーを製造した。
・着色剤１ ＰＶファーストイエローＨ２Ｇ クラリアント社製
［Ｃ.Ｉ.ピグメントイエロー１２０(平均粒径０．２６μｍ)］ １０重量部
・着色剤２ オラセットイエローＧＨＳ チバスペシャリティーケミカルズ社製
［Ｃ．Ｉ．ソルベントイエロー１６３］ ４重量部
【０１０２】
＜実施例４＞
実施例１で用いた処方の中で、着色剤の処方を下記のように変更した以外は総て実施例１と同様にして、本実施例のイエロートナーを製造した。
・着色剤１ クラリアント社製
［Ｃ.Ｉ.ピグメントイエロー１７３（平均粒径０．１７μｍ）］ ８重量部
・着色剤２ オラセットイエローＧＨＳ チバスペシャリティーケミカルズ社製
［Ｃ．Ｉ．ソルベントイエロー１６３］ ６重量部
上記で得られた本実施例のイエロートナーについて、実施例１と同様の方法で画像を形成し、各評価を行なった。この結果、表１〜表２に示したように良好な結果が得られた。
【０１０３】
＜実施例５＞
実施例１で用いた処方の中で、（顔料）を粒径０．６０μｍに伸張させた化合物に変更した以外は総て実施例１と同様にして、本実施例のイエロートナーを製造した。
上記で得られた本実施例のイエロートナーについて、実施例１と同様の方法で画像を形成し、各評価を行なった。この結果、表１〜表２に示したように良好な結果が得られた。
【０１０４】
＜実施例６＞
実施例１で用いた処方の中で、添加するエステルワックスの添加量を３０重量部から１１０重量部に変更した以外は総て実施例１と同様にして、本実施例のイエロートナーを製造した。
上記で得られた本実施例のイエロートナーについて、実施例１と同様の方法で画像を形成し、各評価を行なった。この結果、表１〜表２に示したように良好な結果が得られた。
【０１０５】
＜実施例７＞
実施例１で用いた処方の中で、着色剤１をＣ．Ｉ．ピグメントイエロー１９９に変更し、サリチル酸金属化合物を４級アンモニウム塩の荷電制御剤に変更した以外は総て実施例１と同様にして、本実施例のイエロートナーを製造した。
上記で得られた本実施例のイエロートナーについて、実施例１と同様の方法で画像を形成し、各評価を行なった。この結果、表１〜表２に示したように良好な結果が得られた。
【０１０６】
＜参考例１＞
実施例１で用いた処方の中で、離型剤をエステルワックスからポリプロピレンワックスに変更した以外は総て実施例１と同様にして、本参考例のイエロートナーを製造した。
上記で得られた本参考例のイエロートナーについて、実施例１と同様の方法で画像を形成し、各評価を行なった。この結果、表１〜表２に示したように、良好な結果が得られた。
【０１０７】
＜実施例９＞
ポリエステル樹脂（ビスフェノールＡ系ジオール−テレフタル酸−トリメリット酸縮合物、モノマー混合重量比＝５０：４５：５、ＭＷ＝５５，０００）１００重量部に対して、２種類の着色剤、荷電制御剤及び離型剤を夫々下記の配合で加えて、溶融・混練・粉砕・分級を行って、本実施例のイエロートナーを製造した。
・着色剤１ クロモフタルイエロー３Ｇ チバスペシャリティーケミカルズ社製
［Ｃ．Ｉ．ピグメントイエロー９３（平均粒径０．０９μｍ）］ ４重量部
・着色剤２ オラセットイエローＧＨＳ チバスペシャリティーケミカルズ社製
［Ｃ．Ｉ．ソルベントイエロー１６３］ ３重量部
・サリチル酸金属化合物 ２重量部
・離型剤＜モノエステルワックス：Ｍｗ＝６５０、Ｍｎ＝５００、ＳＰ値＝
９．０、融点６５℃、溶融粘度９．２（ｍ・ｐａ・ｓ）＞ ５重量部
上記で得られた本実施例のイエロートナーについて、実施例１と同様の方法で画像を形成し、各評価を行なった。この結果、表１〜表２に示したように、良好な結果が得られた。
【０１０８】
＜比較例１＞
実施例１で用いた処方の中で、着色剤として下記の処方の顔料のみを使用した以外は総て実施例１と同様にして、本比較例のイエロートナーを製造した。
・着色剤 クロモフタルイエロー８ＧＮ チバスペシャリティーケミカルズ社製
［Ｃ.Ｉ.ピグメントイエロー１２８(平均粒径０．１４μｍ)］ １４重量部
【０１０９】
＜比較例２＞
実施例１で用いた処方の中で、着色剤として下記の処方の染料のみを使用した以外は総て実施例１と同様にして、本比較例のイエロートナーを製造した。
・着色剤 オラセットイエローＧＨＳ チバスペシャリティーケミカルズ社製
［Ｃ．Ｉ．ソルベントイエロー１６３］ １４重量部
【０１１０】
＜比較例３＞
実施例１で用いた処方の中で、着色剤として下記の処方を使用した以外は総て実施例１と同様にして、本比較例のイエロートナーを製造した。
・着色剤１ ＰＶファーストイエローＨ２Ｇ クラリアント社製
［Ｃ.Ｉ.ピグメントイエロー１２０(平均粒径０．２６μｍ)］ ８重量部
・着色剤２［Ｃ．Ｉ．ソルベントイエロー１５］ ６重量部
【０１１１】
＜比較例４＞
実施例１で用いた処方の中で、着色剤として下記の処方を使用した以外は総て実施例１と同様にして、本比較例のイエロートナーを製造した。
・着色剤１
［Ｃ.Ｉ.ピグメントイエロー１３９(平均粒径０．３１μｍ)］ ８重量部
・着色剤２ オラセットイエローＧＨＳ チバスペシャリティーケミカルズ社製
［Ｃ．Ｉ．ソルベントイエロー１６３］ ６重量部
【０１１２】
【表１】

【０１１３】
【表２】

【０１１４】
【表３】

【０１１５】
【表４】

【０１１６】
【表５】

【０１１７】
【発明の効果】
以上説明したように、本発明によれば、着色剤に、特定の色相範囲の顔料と染料を使用し、更に、好ましくは、顔料と染料の帯電量差を特定の範囲に制御して構成することにより、現像性に優れ、且つ、低光沢度の画像を形成した場合においても着色力が高く、更に、オーバーヘッドプロジェクター用フィルムにしても透過性に優れた画像を得ることができるイエロートナー及び該トナーを使用した画像形成装置が提供される。更に、本発明によれば、上記の優れた特性を有するイエロートナーが容易に得られるイエロートナーの製造方法が提供される。
【図面の簡単な説明】
【図１】トナーの帯電量を測定するための装置の説明図である。
【図２】本発明の画像形成方法で使用できる画像加熱定着装置の概略説明図である。
【符号の説明】
２３：定着ローラー
２４：加圧ローラー
２５：ハロゲンヒーター
２８：サーミスタ
２９：分離爪
６２：ガイド
１０１：吸引機
１０５：真空計
１０６：風量調節弁[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a yellow toner for developing an electrostatic image formed by electrophotography, electrostatic printing, and the like, a method for producing the toner, and an image forming method using the toner.
[0002]
[Prior art]
In recent years, digital full-color copiers and printers have been put into practical use, and it has become possible to obtain high-quality images with excellent color reproducibility without color unevenness as well as resolution and gradation. In a digital full-color copying machine, a color image original is color-separated with B (blue), G (green), and R (red) color filters, and then a latent image having a dot diameter of 20 to 70 μm corresponding to the original image. Are developed using each color developer of Y (yellow), M (magenta), C (cyan), and B (black) by utilizing a subtractive color mixing action. For this reason, it is necessary to transfer a large amount of developer from the photosensitive member onto the transfer material as compared with the black-and-white copying machine, and it is possible to cope with the development of fine dots in order to cope with further higher image quality in the future. In order to make a developer, it is expected that the toner particles of each color constituting the developer have a minute particle size.
[0003]
However, if the particle size of the toner particles is reduced in accordance with the demand for higher image quality, the resolution and sharpness of a full-color image will surely be satisfactory, but there are various effects associated with finer particles. I understand. In addition, when the toner particle size is reduced, there is a problem that the charging characteristics are easily affected by the uneven distribution of the colorant constituting the toner.
Accordingly, there is a need for a toner that has a better dispersion of colorant in the color toner than before, a well-balanced hue and spectral reflection characteristic, and sufficient saturation.
[0004]
Next, if the toner particle size is reduced, light is more likely to be scattered, so the chromaticity, lightness, density, etc. of the image changes, and a problem arises that a color configuration different from that of the conventional technique is required. is there. Furthermore, with the recent spread of printers, there is a tendency to prefer images that are similar to other non-glossy printed materials such as new user orientation, that is, photoengraving printing. In such a case, the above problem becomes more prominent.
That is, in the conventional technology, the fixed toner is required to be in a state of nearly complete melting so that the shape of the toner particles cannot be discriminated so as not to disturb the color reproduction by irregular reflection with respect to light. In a color image in which several types of toner layers are superimposed, the upper toner layer needs to have transparency so as not to interfere with the lower toner layer. Based on this idea, for example, JP-A-59-26757, JP-A-63-70271, JP-A-1-230072, JP-A-2-293860, JP-A-6-11898, etc. In addition, various proposals have been made for each yellow / magenta / cyan / black toner and other configurations.
[0005]
On the other hand, according to the new user orientation described above, if an image with a small difference in glossiness that does not fatigue the eyes of the user is to be obtained, the toner must be fixed to a value close to the glossiness of the paper. An image is formed in a state where the particles are not completely melted (a state in which the shape of the toner particles remains). In such an image, the influence of scattered light due to the roughness of the surface of the fixed printed surface tends to be inferior and tends to be inferior in coloring power. Therefore, in order to increase the coloring power, coloring such as pigments contained in the toner The need to increase the amount of agent added has arisen.
[0006]
However, increasing the amount of colorant added to the toner tends to cause poor dispersion of the colorant, and the hue angle, particularly the chromaticity of the transparency image, changes, making it impossible to obtain the desired color. It was. In particular, for yellow toner, human sensitivity to changes in hue angle is remarkable, and changes in the color angle of transmitted light are not preferred. Further, when the toner resin is designed so that the toner particles are not completely melted when the toner image is fixed, the toner particles cannot be completely melted even on the transparency film. It was found that the transmitted light was scattered and the color reproduction area was reduced.
[0007]
In addition to the demand for higher image quality, a toner having excellent heat resistance and light resistance is desired from the viewpoint of image quality. For the purpose of improving this, yellow pigments excellent in heat resistance and light resistance have been proposed in JP-A-2-136865 and JP-A-2-2088662.
However, as described above, in low gloss images, the image density does not increase due to light scattering, and the amount of pigment added must be increased. When toner is prepared by a conventional method, it is exposed on the surface of the toner particles. The amount of pigment to be increased increases, and charging and fixing defects are likely to occur. Further, when the amount of the pigment added is increased, there is a problem that the conventional manufacturing method is insufficiently dispersed, and in particular, when an image is formed, the transparency of the transparency image is not satisfied.
[0008]
For the purpose of improving the transparency as described above, in JP-A-61-112160, JP-A-3-276161, etc., a dye is used as a colorant, or a dye and a pigment are used in combination. A method is disclosed. However, when a dye is used alone, a problem arises in the light resistance of the formed image. Even when a dye and a pigment are used in combination, the hue design and charge amount design of the secondary color are not always satisfactory. There is nothing to do.
As described above, there are no known color toners that can satisfy all of the problems necessary for obtaining printed materials with low gloss, and the development of such toners is awaited. ing.
[0009]
[Problems to be solved by the invention]
Accordingly, an object of the present invention is to solve the above-mentioned problems of the prior art and provide a yellow toner capable of obtaining an extremely clear image and an image forming method using the toner.
That is, an object of the present invention is to provide a balanced hue that is not affected by the level of glossiness in yellow toner containing at least a yellow pigment and a yellow dye (specifically, the chromaticity difference between the hue on the transfer paper and the transparency of the transparency image). In addition, a yellow toner capable of obtaining an image having excellent transparency and an image forming method using the toner is provided.
Another object of the present invention is to provide a yellow toner excellent in charging stability and an image forming method using the toner.
Furthermore, another object of the present invention is to provide a method for producing a yellow toner, in which a yellow toner having excellent image characteristics as described above can be easily obtained.
[0010]
[Means for Solving the Problems]
The above object is achieved by the present invention described below. That is, the present invention provides at least one yellow pigment and a yellow dye. C. I. Solvent Yellow 163 A toner containing The yellow pigment is C.I. I. Selected from the group consisting of CI Pigment Yellow 93, 120, 128, 173, and 199; The chromaticity of the yellow pigment on the white paper is L ^* Value of 60.0 to 95.0, a ^* Value of -25.0 to -8.0, and b ^* Is +60.0 to +115.0, and the chromaticity of the yellow dye in the color development on white paper is L ^* Value of 60.0 to 95.0, a ^* Values between -12.0 and +10.0, and b ^* The yellow toner has a value of +60.0 to +115.0, a method for producing the toner, and an image forming method using the toner.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in more detail with reference to preferred embodiments of the present invention.
As a result of intensive studies on the above-described problems of the prior art, the present inventors have found that the chromaticity in the transmitted light of the transparency image is higher than the chromaticity on the transfer paper as the amount of yellow pigment added in the toner resin increases. As a result of various investigations in view of the tendency to red shift, X-rite SP68 (D65) in color developed on white paper (after being dispersed in styrene (St) / butyl acrylate (BA) resin and bar coated on color developed paper). , The viewing angle is 2 degrees) ^* Value of 60.0 to 95.0, a ^* Value of -25.0 to -8.0, and b ^* The chromaticity of the yellow pigment having a value of +60.0 to +115.0 and the same color developed on white paper is L ^* Value of 60.0 to 95.0, a ^* Values between -12.0 and +10.0, and b ^* If a yellow toner containing a yellow dye having a value of +60.0 to +115.0 is used, both single color and secondary color reproducibility are excellent, and the chromaticity difference between the hue on the transfer paper and the transparency of the transparent transmission image As a result, the inventors have found that an image having a small transparency and excellent transparency can be obtained.
[0012]
That is, when an image with a small difference in gloss between the transfer paper and the image is obtained, the influence of scattered light due to the roughness of the fixed printing surface becomes remarkable because the toner particles are not completely melted. In order to increase the power, it is necessary to increase the amount of colorant such as pigment, but even with a pigment alone, even if a greenish yellow pigment is used, the improvement in the chromaticity difference between the transfer paper and the transmitted light is not improved. was difficult. On the other hand, in the yellow toner of the present invention, the coloring power of the toner is increased by adding a yellow dye in addition to the yellow pigment, and the chromaticity of the pigment and dye constituting the toner is within a specific range. By controlling as described above, it is possible to obtain an image having excellent transparency transparency in which both single color and secondary color reproducibility are excellent and the chromaticity difference between the hue on the transfer paper and the transparency transmission image hue is small. Make it possible. On the other hand, when a chromaticity dye is used that is greener than that within a specific range, the difference in chromaticity between the transfer paper and transmitted light can be reduced, but the hue is green, so a full-color image When used in a forming apparatus, red reproducibility may not be satisfactory depending on the hue of magenta toner.
In the yellow toner of the present invention, since a yellow pigment and a yellow dye are used in combination as the colorant, an image having excellent transparency can be obtained as compared with the case of the pigment alone. Since it is used, an image having excellent light resistance as compared with the case of using a dye alone can be obtained.
[0013]
As the yellow pigment used in the yellow toner of the present invention, known materials can be used, but from the viewpoint of the hue of transmitted light, in the color development on white paper (after being dispersed in St / BA resin, the color paper is bar coated). In chromaticity measurement by X-rite SP68, L ^* Value of 60.0 to 95.0, a ^* Value of -25.0 to -8.0, and b ^* It is necessary to have chromaticity in the range of +60.0 to +115.0. Specific examples of yellow pigments include C.I. I. Pigment Yellow 12, 13, 14, 17, 62, 74, 83, 93, 94, 95, 109, 110, 111, 120, 128, 129, 147, 151, 154, 155, 166, 167, 168, 180, 185, 191 and 199.
[0014]
On the other hand, in the present invention, the yellow dye used together with the yellow pigment as described above is used in chromaticity measurement by X-rite SP68 in white paper color development (dispersed in St / BA resin and then bar coat on color paper). , L ^* Value of 60.0 to 95.0, a ^* Values between -12.0 and +10.0, and b ^* It is necessary to have chromaticity in the range of +60.0 to +115.0. Any dye can be used as long as it has a chromaticity within this range. However, from the viewpoint of hue, it is preferable to use a dye having an anthraquinone derivative structure in order to make the effects of the present invention more apparent. Specifically, C.I. I. It is more preferable to use a dye classified as Solvent Yellow 163.
[0015]
The amount of yellow pigment added as described above is preferably 1 to 6 parts by weight with respect to 100 parts by weight of the toner binder resin. When the amount added is less than 1 part by weight, the obtained image tends to be inferior in light resistance. On the other hand, when the amount added is more than 6 parts by weight, the transparency of the image is deteriorated or the hue on the transfer paper is increased. There is a risk that a chromaticity difference from the transparency transparent image hue will occur.
The amount of yellow dye added to the yellow toner of the present invention is preferably 1 to 6 parts by weight with respect to 100 parts by weight of the toner binder resin. If the amount added is less than 1 part by weight, there may be a problem of insufficient coloring power, and if it is more than 6 parts by weight, there may be a problem in chargeability.
[0016]
As another preferred embodiment of the yellow toner of the present invention, in addition to the above-described configuration, a two-component tribo at room temperature and normal humidity with a yellow pigment ferrite carrier and a yellow dye ferrite carrier at room temperature and normal humidity. Examples thereof include a yellow toner configured so that the difference from the two-component tribo is 10.0 (mC / kg) to 150.0 (mC / kg). As a result of investigations by the present inventors, it has been found that such a configuration makes it possible to obtain a yellow toner in a form in which the toner is controlled with good chargeability. This will be described below.
[0017]
Some commonly used yellow pigments have a strong polarity due to their structure and are charged to a strong negative or a strong positive by friction with a carrier or the like. In this case, if a strong negative pigment is used as it is to obtain a negatively chargeable toner, problems such as charging up under low humidity and rising at high humidity may occur. Conversely, when a positively chargeable toner is used by using a strong positive pigment as it is, the same problem as described above may occur.
As a result of intensive studies on this problem by the present inventors, the above problem can be solved if a weak negative or weak positive dye is allowed to coexist with the above-mentioned strong negative or strong positive yellow pigment. I understood. That is, although the mechanism is not clear, it is considered that the addition of a dye offsets the polarity of the pigment, resulting in a toner having good charging characteristics.
[0018]
In the yellow toner of the present invention, as described above, the difference between the two-component tribo of the yellow pigment ferrite carrier and the two-component tribo of the yellow dye ferrite carrier used together is 10.0 (mC / kg). ) To 150.0 (mC / kg). That is, when the difference in charge amount is less than 10.0 (mC / kg), for example, when the tribo is high for both the pigment and the dye, the above effects cannot be obtained. On the contrary, when both are small, the reversal component increases in the toner, and fogging or the like may occur. When the difference in charge amount is larger than 150.0 (mC / kg), the amount of dye added to control the charge amount increases, which is not satisfactory from the viewpoint of chromaticity and light resistance.
In the yellow toner of the present invention, it is more preferable that the difference in triboelectric charge amount between the ferrite carrier of each pigment and dye is 30.0 (mC / kg) to 150.0 (mC / kg).
[0019]
Furthermore, as a result of examining the conditions under which the hue angle does not change most in the transmitted light of a transparency image whose surface is not completely melted, the present inventors have selected a pigment having a specific primary particle size. I found out that it would be possible to suppress it to some extent. This will be described below.
Conventionally, as a description from such a viewpoint, for example, in JP-A-4-342265, the primary particle diameter of a quinacridone pigment is described, and as an example for the purpose of producing gradation, JP-A-4-204547 discloses carbon black. However, when such a pigment is simply applied to a transparency image in which the surface is not completely melted as in the present invention, the change in hue angle can be suppressed as compared with the conventional case. It was found that the hue angle and color gamut change in transmitted light.
[0020]
On the other hand, the present inventors preferably control the shape of the yellow pigment contained in the yellow toner particles within the range of 0.01 to 0.70 μm in terms of number average diameter. Has been found to be able to suppress changes in hue angle and color gamut if controlled within the range of 0.01 to 0.40 μm. That is, if the particle size of the pigment is less than 0.01 μm, not only the light resistance is extremely lowered but also the handling property and the charging property during production are adversely affected. On the other hand, when the primary particle size of the pigment exceeds 0.70 μm, the colorant is likely to aggregate during the production, and even in a system using a dye together with the yellow toner of the present invention, the transmitted light of the transparency image is transmitted. It was found that the hue angle and color gamut tend to change compared to those on paper. Also, the transmission image becomes dark.
[0021]
The number average diameter of the pigment was specifically measured by the following method.
First, after sufficiently dispersing the toner to be measured in an epoxy resin curable at room temperature, the cured product obtained by curing in an atmosphere of 40 ° C. for 2 days is converted to ruthenium tetroxide, and if necessary, quaternary tetroxide. After dyeing together with osmium, a flaky sample is cut out using a microtome with diamond teeth. Thereafter, the cut-out flaky sample was observed using a transmission electron microscope (TEM), and the tomographic form of the toner was measured. 100 obtained toner cross-sectional images are randomly sampled to obtain image information of pigment particles dispersed in the toner cross-sectional image, and the image information is sent to an image analysis apparatus (Luxex 3) manufactured by Nireco through an interface. The value obtained as the particle size distribution was taken as the average particle size of the pigment.
[0022]
Another preferred form of the yellow toner of the present invention is one in which the toner contains 5 to 30% by weight of a low softening point substance. Such a low softening point substance functions as a release agent having the function of a colorant dispersion aid in the toner, but it is particularly preferable to add an ester wax having a specific structure described later. In addition to the structure of the yellow toner of the present invention described above, if such a wax having an ester group is combined, further improvement in charging characteristics can be achieved. Such an effect is caused by the fact that the functional group in the yellow pigment and the yellow dye constituting the yellow toner of the present invention has an affinity for the ester group in the wax. This is presumably because the toner is buried in the toner as a result of being easily incorporated into the wax having hydrophobicity.
[0023]
Further, the addition of a wax having an ester group as described above as a constituent component of the yellow toner of the present invention also improves the light resistance of the pigment contained in the toner. Although the mechanism is not clear, it is thought that the interaction between the wax, the pigment, and the dye prevents the pigment from decomposing.
As a result of investigations from the above viewpoints, the present inventors have more preferably one having at least one long-chain ester moiety having 15 or more carbon atoms as the ester wax used in this case. It is particularly preferred to have one or more long-chain ester moieties having 15 to 30 carbon atoms.
[0024]
That is, when an ester wax having a carbon number of less than 15 is added to the toner, the surface of the pigment is modified, but the colorant tends to migrate to the fixing roller surface due to the amount of heat of the fixing machine. Therefore, show-through to paper is likely to occur during fixing, and roller durability is reduced. On the other hand, if the number of carbons exceeds 30, the plastic effect of the wax on the binder resin becomes too great, and the fixability is lowered.
[0025]
In recent years, the need for full-color double-sided images has increased, but when double-sided images are formed, the toner image on the transfer paper first formed on the front side is also fixed when the next image is formed on the back side. Therefore, it is necessary to fully consider the high temperature offset property of the toner. Therefore, it is preferable that the yellow toner of the present invention is constituted by adding a large amount of ester wax.
Therefore, the ester wax used in the present invention is intended to impart releasability / transparency to the toner in addition to the modification of the pigment. Therefore, the ester wax should be added to the toner in the range of 5 to 30% by weight. Is preferred. That is, when the amount is less than 5% by weight, the pigment is not sufficiently modified, and further, the image on the back side tends to exhibit an offset phenomenon when fixing a double-sided image. On the other hand, when the amount exceeds 30% by weight, for example, when the toner is manufactured, fusion to a manufacturing apparatus or toner particles tends to occur, and the impact resistance against the drum is reduced. Ming easily occurs.
[0026]
In the production of the yellow toner of the present invention, as a means for modifying the ester wax by adding an ester wax to the pigment, a known means such as a master batch can be used in advance. In order to obtain effects such as property / dispersibility / re-aggregation at the same time, it is preferable to add 100 to 3,000 parts by weight of ester wax with respect to 100 parts by weight of the yellow pigment.
[0027]
As the ester wax used in the yellow toner of the present invention, it is preferable to use a compound having a main maximum peak value of thermal analysis of 40 to 90 ° C. when measured according to ASTM D3418-8. That is, when an ester wax having a maximum peak of less than 40 ° C. is added, the self-aggregation force of the low softening point material is weakened, and as a result, the high temperature offset property of the toner is weakened. It is not preferable for use. On the other hand, when the maximum peak exceeds 90 ° C., the fixing temperature of the toner becomes high, and it becomes difficult to appropriately smooth the surface of the fixed image, which is not preferable from the viewpoint of color mixing.
[0028]
The measurement of the maximum peak value temperature by thermal analysis of the ester wax used in the present invention was performed using, for example, DSC-7 manufactured by Perkin Elmer. And the temperature correction of the apparatus detection part was performed using melting | fusing point of indium and zinc, and correction | amendment of the calorie | heat amount was performed using the melting heat of indium. The sample was set in an aluminum pan, a similar empty pan was set on the control side, and the heating rate was 10 ° C./min. The measurement was performed.
[0029]
Specific examples of preferable ester wax used in the yellow toner of the present invention include the following compounds. The structural formulas of typical compounds of ester wax that can be suitably used in the present invention are shown by the general structural formulas (1) to (5) below.
[0030]
<General structural formula (1) of ester wax>
[Chemical 1]

[0031]
<Structural formula (2) of ester wax>
[Chemical 2]

[0032]
<Structural formula (3) of ester wax>
[Chemical 3]

[0033]
<Structural formula (4) of ester wax>
[Formula 4]

[0034]
<Structural formula (5) of ester wax>
[Chemical formula 5]

[0035]
Among the ester waxes having the structure as described above, those having a hardness of 0.5 to 5.0 are particularly preferably used for the yellow toner of the present invention. Here, the hardness of the ester wax was measured using a dynamic ultra-micro hardness meter (DUH-200) manufactured by Shimadzu Corporation after making a cylindrical sample having a diameter of 20 mmφ and a thickness of 5 mm. It is a value of Vickers hardness. The measurement conditions at this time were 0.5 g load, 10 μm displacement under a load speed of 9.67 mm / sec, and held for 15 seconds, and the dent shape obtained at this time was measured to determine the Vickers hardness. Ask. An ester wax having a hardness of 0.5 to 5.0 thus obtained is preferably used for the yellow toner of the present invention. That is, when a low softening point material (ester wax) having a hardness of less than 0.5 is used, the toner tends to have a large pressure dependency and process speed dependency of the fixing device, and the high temperature offset effect is insufficiently developed. easy. On the other hand, when the toner having a hardness exceeding 5.0 is used, the toner tends to be poor in storage stability, and the self-aggregation force of the release agent itself is small. It tends to be insufficient.
[0036]
Specific examples of preferable ester wax used in the yellow toner of the present invention include the following compounds.
[0037]
[Chemical 6]

[0038]
[Chemical 7]

[0039]
[Chemical 8]

[0040]
[Chemical 9]

[0041]
The yellow toner of the present invention may contain a charge control agent.
Examples of the charge control agent for controlling the toner to be negatively charged include the following substances, and any of them can be used for producing the yellow toner of the present invention. For example, organometallic compounds and chelate compounds are effective, and examples thereof include monoazo metal compounds, acetylacetone metal compounds, aromatic hydroxycarboxylic acids, and aromatic dicarboxylic acid metal compounds. Other examples include aromatic hydroxycarboxylic acids, aromatic mono- and polycarboxylic acids and metal salts thereof, anhydrides, esters, and phenol derivatives such as bisphenol. Furthermore, urea derivatives, metal-containing salicylic acid compounds, metal-containing naphthoic acid compounds, boron compounds, calixarene, silicon compounds, styrene-acrylic acid copolymers, styrene-methacrylic acid copolymers, styrene-acrylic-sulfonic acid copolymers Examples thereof include polymers and non-metal carboxylic acid compounds.
[0042]
In addition, as the charge control agent for controlling the toner to be positively charged, there are the following substances, and any of them can be used for producing the yellow toner of the present invention. For example, nigrosine and modified products with fatty acid metal salts, quaternary ammonium salts such as guanidine compounds, imidazole compounds, tributylbenzylammonium-1-hydroxy-4-naphthosulfonate, tetrabutylammonium tetrafluoroborate, and These analogs are onium salts such as phosphonium salts and these lake pigments, triphenylmethane dyes and these lake pigments (as rake agents, phosphotungstic acid, phosphomolybdic acid, phosphotungsten molybdic acid, tannic acid, Lauric acid, gallic acid, ferricyanide compound, ferrocyanide, etc.), metal salts of higher fatty acids; diorganotin oxides such as dibutyltin oxide, dioctyltin oxide, dicyclohexyltin oxide; dibutyl Zuboreto, dioctyl tin borate, diorgano tin borate such as dicyclohexyl tin borate; and the like, can be used in combination these alone, or two or more types. Among these, in particular, a charge control agent such as a nigrosine series or a quaternary ammonium salt can be preferably used.
These charge control agents may be used in an amount of 0.01 to 20 parts by weight, more preferably 0.5 to 10 parts by weight with respect to 100 parts by weight of the binder resin component.
[0043]
The yellow toner of the present invention having the above-described configuration can be easily obtained by the method for producing a yellow toner of the present invention in which a polymerizable monomer system containing a polymerizable monomer described below is polymerized to obtain a toner. It is done. In the method for producing a yellow toner of the present invention, when a toner is produced by polymerizing a polymerizable monomer system containing at least one kind of yellow pigment and at least one kind of yellow dye, As described in the above, the chromaticity in the color spread on the white paper is L ^* Value of 60.0 to 95.0, a ^* Value of -25.0 to -8.0, and b ^* A yellow pigment having a value of +60.0 to +115.0 and a chromaticity in a color developed on a white paper as a yellow dye is L ^* Value of 60.0 to 95.0, a ^* Values between -12.0 and +10.0, and b ^* A yellow dye having a value of +60.0 to +115.0 is used.
[0044]
Further, as a specific method for polymerizing the polymerizable monomer system, it is preferable to obtain a toner by directly polymerizing the polymerizable monomer in an aqueous medium. For example, as described in Japanese Patent Publication No. 36-10231, Japanese Patent Publication No. 43-10799, Japanese Patent Publication No. 51-14895, and the like, a coloring material containing a polymerizable monomer, the above yellow pigment and a yellow dye is used. The monomer composition is dispersed and stabilized by uniformly dissolving or dispersing the crosslinking agent, charge control agent, and other additives as necessary to obtain a polymerizable monomer composition. Toner particles having a desired particle size are obtained directly by dispersing in a continuous phase containing an agent, for example, an aqueous phase using a suitable stirrer and simultaneously carrying out a polymerization reaction.
The toner particles obtained by the polymerization method as described above have a spherical shape, so that even when trying to obtain a low gloss image, light scattering can be minimized (that is, hue change) In addition, since there is little loss of transparency, a toner with improved effects intended by the present invention can be obtained.
Further, when the polymerizable monomer is directly polymerized in the aqueous medium, the colorant, the charge control agent and the like, which are the toner forming material contained in the toner particles, are uniformly dispersed in the monomer. Since the toner particles are formed after dissolution, the exposure of the colorant to the toner particle surface is suppressed, and the toner particle surface exhibits a uniform charging behavior as compared with the toner particles obtained by the pulverization method. .
[0045]
In addition, the above-mentioned yellow pigments and dyes used in the present invention, low softening point substances (release agents) used in preferred forms thereof, and charge control agents are dispersed in the polymerizable monomer. If so, the dispersion in the monomer system is particularly stable compared to the case where other yellow colorants are used, so that it is possible to reduce the amount of colorant added to obtain the same coloring power. Therefore, as a result, a toner having a sharp charge which is superior in transparency can be obtained.
[0046]
In addition, when the toner is prepared by a pulverization method, as the average particle size measured by a Coulter counter becomes 9 μm or less, uniform dispersibility and efficient pulverization of raw materials that have not been a problem in the past, It tends to be very difficult to classify the toner into a sharp particle size distribution. On the other hand, in the yellow toner manufacturing method of the present invention, selection of materials such as a large amount of low softening point substances that could not be used in the conventional toner manufacturing method using the pulverization method is possible. It has characteristics such as widening, which is also preferable from this point.
[0047]
When a yellow pigment having a specific chromaticity as mentioned above used in the present invention is used to produce a toner by a polymerization method, crushing of these pigments in a polymerizable monomer is facilitated. However, for this purpose, the particle size of the yellow pigment before being dispersed in the monomer system is preferably set such that the preferred dispersed particle size of the yellow pigment in the toner particles described above, that is, the number average diameter is 0.01. It is preferable to use one in the range of ˜0.70 μm. Specifically, the yellow pigment used when the yellow toner of the present invention is produced by a polymerization method has a particle size distribution in an alcohol-based organic solvent within a range of 0.01 to 0.50 μm in number average diameter. It is preferable to use those in the range of 0.01 to 0.30 μm.
[0048]
Specifically, the particle size distribution in the alcohol-based organic solvent used here was measured by the following method. For the measuring device, a Coulter counter LS type (manufactured by Coulter Co.) was used, and the yellow pigment to be measured was added to ethanol at a ratio such that the concentration was about 20 to 400 ppm, and after ultrasonic dispersion for 60 seconds, The number distribution obtained by measurement was used.
[0049]
In the yellow production method of the present invention, a polymerizable monomer for forming a binder resin as described below is used together with the yellow pigment as described above. That is, in a method for directly obtaining a toner by a polymerization method, a conventionally known polymerizable monomer can be preferably used. Specifically, for example, styrene, o (m-, p-)-methylstyrene, Styrenic monomers such as m (p-)-ethylstyrene; methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, octyl (meth) acrylate , Dodecyl (meth) acrylate, stearyl (meth) acrylate, behenyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate ( (Meth) acrylic acid ester monomers; butadiene, isoprene, cyclohexene, (meth) acrylonitrile, acryl Ene-based monomers such as acid amides are preferably used.
[0050]
And these are the theoretical glass temperature (Tg) described in publication polymer handbook 2nd edition III-P139-192 (product made from John Wiley & Sons) of the formed resin independently or generally. The polymerizable monomers as described above are appropriately mixed and used so as to indicate 40 to 85 ° C. That is, when a resin having a theoretical glass transition temperature of less than 40 ° C. is used, there are problems in terms of storage stability of the toner and durability of the developer, while a resin having a theoretical glass transition temperature of more than 85 ° C. When the toner image is used, when the toner image is fixed, agglomeration due to the remaining crystalline portion is generated on the image, and particularly in the case of a full-color toner, the transparency of the OHP image tends to be remarkably reduced. From the viewpoint of realizing the purpose of forming a high-quality image, it is not preferable.
[0051]
The yellow toner of the present invention is preferably produced by a polymerization method, but can of course be produced by a pulverization method. As the binder resin suitably used in this case, a known material such as a styrene-acrylic resin, a maleic acid copolymer, a polyester resin, or an epoxy resin obtained by combining the monomer components listed above is used. it can. In particular, when the yellow toner of the present invention is produced using a pulverization method, it is preferable to use a polyester resin in order to maintain the dispersibility and improve the charging characteristics which are the object of the present invention.
[0052]
The molecular weight of the binder resin constituting the toner can be measured by GPC (gel permeation chromatography). As a specific GPC measurement method, the toner to be measured is extracted in advance with a toluene solvent using a Soxhlet extractor for 20 hours, and then toluene is distilled off with a rotary evaporator. An organic solvent that dissolves but cannot dissolve the outer shell resin, such as chloroform, is thoroughly washed, and then the solution dissolved in THF (tetrahydrofuran) is dissolved in a solvent-resistant membrane having a pore diameter of 0.3 μm. Prepare a sample for measurement by filtering with a filter. And the sample obtained above uses 150C made from Waters as GPC, and the column constitution uses what connected A-801, 802, 803, 804, 805, 806, 807 made by Showa Denko, and is standard. The molecular weight distribution is measured using a calibration curve of polystyrene resin. In the yellow toner of the present invention, the number average molecular weight (Mn) of the resin component in the toner obtained as described above is 5,000 to 1,000,000, and the weight average molecular weight (Mw) and number average It is preferable to use a resin having a ratio (Mw / Mn) to molecular weight (Mn) of 2 to 100.
[0053]
In the yellow toner of the present invention, in order to form a toner particle having a core-shell structure by encapsulating a low softening point substance contained in a large amount in the outer shell resin as described above by a polymerization method. In addition to the polymerizable monomer components listed above, a polar resin may be further added. As the polar resin used in this case, a copolymer of styrene and (meth) acrylic acid, a maleic acid copolymer, a polyester resin, an epoxy resin, or the like is preferably used.
[0054]
In the yellow toner of the present invention, in order to further impart a releasing action, in addition to the ester wax having the structural formula as described above, another low softening point substance is added to the binder resin. Also good. As the low softening point substance used in this case, a compound having a main maximum peak value of thermal analysis measured in accordance with ASTM D3418-8 of 50 to 180 ° C. is particularly preferable. That is, when the maximum peak value is less than 50 ° C., the self-cohesion force of the low softening point substance becomes weak, and as a result, the high temperature offset property of the toner becomes weak. In particular, it is not preferable in the case of a toner used for a full color developer. On the other hand, if the maximum peak value exceeds 180 ° C., the crystallinity and dispersibility of the softening point substance are deteriorated at present, which is not preferable in terms of toner fixing properties and image transparency.
[0055]
In this case, the temperature measurement of the maximum peak value of the low softening point substance is performed using, for example, DSC-7 manufactured by Perkin Elmer, and the temperature correction of the apparatus detection unit is performed using the melting points of indium and zinc. Is performed using the heat of fusion of indium. In the measurement, the sample was set in an aluminum pan, a similar empty pan was set for control, and the heating rate was 10 ° C./min. Measure with.
[0056]
Specific examples of the low softening point material having the above thermal properties include, for example, paraffin wax, polyolefin wax, Fischer tropish wax, amide wax, ester wax, higher fatty acid, and graft / block compounds thereof. Etc. can be used.
[0057]
When the direct polymerization method is used in the method for producing the yellow toner of the present invention, it is preferable to contain a polymerization initiator in the polymerizable monomer system. As a polymerization initiator used in this case, for example, 2,2′-azobis (2,4-dimethylvaleronitrile), 2,2′-azobisisobutyronitrile, 1,1′-azobis (cyclohexane-1) -Carbonitrile), 2,2′-azobis-4-methoxy-2,4-dimethylvaleronitrile, azo-based polymerization initiators such as azobisisobutyronitrile, benzoyl peroxide, methyl ethyl ketone peroxide, diisopropyl peroxycarbonate, cumene hydro Peroxide polymerization initiators such as peroxide, 2,4-dichlorobenzoyl peroxide and lauroyl peroxide can be used.
[0058]
The amount of these polymerization initiators to be added varies depending on the desired degree of polymerization, but generally 0.5 to 20% by weight is added to the monomer. The kind of the polymerization initiator to be used is slightly different depending on the polymerization method, but those mentioned above may be used alone or in combination with reference to the 10-hour half-life temperature. Furthermore, in order to appropriately control the degree of polymerization, a known crosslinking agent, chain transfer agent, polymerization inhibitor and the like can be further added and used.
[0059]
In the case of utilizing a polymerization method in an aqueous medium in the method for producing the yellow toner of the present invention, a dispersant composed of inorganic and organic compounds as described below can be used. For example, inorganic dispersants include tricalcium phosphate, magnesium phosphate, aluminum phosphate, zinc phosphate, calcium carbonate, magnesium carbonate, calcium hydroxide, magnesium hydroxide, aluminum hydroxide, calcium metasilicate, sulfuric acid Examples thereof include calcium, barium sulfate, bentonite, silica, alumina, a magnetic material, and ferrite. Examples of the organic compound include polyvinyl alcohol, gelatin, methylcellulose, methylhydroxypropylcellulose, ethylcellulose, sodium salt of carboxymethylcellulose, starch and the like, and these can be used by dispersing in an aqueous phase. These dispersants are preferably used in the range of 0.2 to 2.0 parts by weight with respect to 100 parts by weight of the polymerizable monomer.
[0060]
Further, these dispersants may be commercially available as they are, but in order to obtain dispersed particles having a fine uniform particle size, an inorganic compound as described above is used in a dispersion medium under high-speed stirring. It can also be generated and used. For example, when tricalcium phosphate is used, a uniformly dispersed fine dispersant that can be preferably used in the suspension polymerization method by mixing an aqueous solution of sodium phosphate and an aqueous solution of calcium chloride under high-speed stirring. Can be obtained. In the above, 0.001 to 0.1 parts by weight of a surfactant may be used in combination for the purpose of miniaturizing the dispersant to be generated. As the surfactant that can be used at this time, specifically, commercially available nonionic, anionic, and cationic surfactants can be used. For example, sodium dodecyl sulfate, sodium tetradecyl sulfate, sodium pentadecyl sulfate, sodium octyl sulfate, sodium oleate, sodium laurate, potassium stearate, calcium oleate and the like are preferably used.
[0061]
When the direct polymerization method is used in the method for producing the yellow toner of the present invention, the toner can be specifically produced by the following production method. That is, first, in a polymerizable monomer, a colorant containing a yellow pigment and a yellow dye having a specific chromaticity, a release agent composed of a low softening material that is appropriately added as necessary, a charge control agent, a polymerization agent Add the initiator and other additives, and uniformly dissolve or disperse the monomer system with a homogenizer, ultrasonic disperser, etc., in an aqueous medium containing a dispersion stabilizer, ordinary stirrer or homomixer, homogenizer, etc. Disperse using. At this time, the granulation is preferably performed while adjusting the stirring speed and time so that the droplets of the polymerizable monomer composition have a desired toner particle size. Furthermore, after that, stirring may be performed to such an extent that the particle state is maintained and the settling of the particles is prevented by the action of the dispersion stabilizer. The polymerization may be performed at a polymerization temperature of 40 ° C. or higher, generally 50 to 90 ° C. In addition, the temperature may be raised in the latter half of the polymerization reaction, and further, in order to remove unreacted polymerizable monomers and by-products that cause odor at the time of toner fixing, the latter half of the reaction or the reaction. A part of the aqueous medium may be distilled off after completion. After completion of the reaction, the produced toner particles are collected by washing and filtration and dried to obtain toner particles. In the above suspension polymerization method, it is usually preferable to use 300 to 3,000 parts by weight of water as the aqueous dispersion medium with respect to 100 parts by weight of the monomer system.
[0062]
Additives for imparting various toner characteristics may have a particle size of 1/5 or less of the volume average diameter of the toner particles from the viewpoint of durability in the toner or when added to the toner. preferable. The particle size of the additive in this case means an average particle size obtained by observing the surface of the toner particles with an electron microscope. Examples of additives for the purpose of imparting these properties include the following.
[0063]
First, examples of the fluidity-imparting agent include metal oxides such as silicon oxide, aluminum oxide, and titanium oxide, carbon black, carbon fluoride, silica, and the like. preferable.
[0064]
As abrasives, metal oxides such as strontium titanate, cerium oxide, aluminum oxide, magnesium oxide and chromium oxide; nitrides such as silicon nitride; carbides such as silicon carbide; metals such as calcium sulfate, barium sulfate and calcium carbonate Salt.
[0065]
Examples of the lubricant include fluorine resin powders such as vinylidene fluoride and polytetrafluoroethylene: fatty acid metal salts such as zinc stearate and calcium stearate;
[0066]
Examples of the charge controllable particles include metal oxides such as tin oxide, titanium oxide, zinc oxide, silicon oxide, and aluminum oxide; carbon black and the like.
These additives are preferably used in the range of 0.1 to 10 parts by weight with respect to 100 parts by weight of the toner particles, but more preferably in the range of 0.1 to 5 parts by weight. These additives may be used alone or in combination.
[0067]
The yellow toner of the present invention having the configuration described above can be used as a one-component developer or a two-component developer. For example, when used as a one-component developer, for example, a magnetic substance is contained in the toner and used as the magnetic toner, and the magnetic toner is transported and charged using a magnet incorporated in the developing sleeve. At least, it can be used for developing an electrostatic latent image. In the case of a one-component developer using a non-magnetic toner that does not contain a magnetic material, the toner is forced to be frictionally charged on the developing sleeve using a blade and a fur brush, and the toner is deposited on the sleeve. There is a method of transporting by.
[0068]
On the other hand, when used as a commonly used two-component developer, the yellow toner of the present invention is mixed with a carrier to obtain a developer. Although it does not specifically limit as a carrier used in this case, It is mainly comprised by the single and composite ferrite state which consists of iron, copper, zinc, nickel, cobalt, manganese, and a chromium element. The carrier shape is also important from the viewpoint that the saturation magnetization and electric resistance can be controlled over a wide range. For example, it is preferable to select a spherical shape, a flat shape, an indefinite shape, or the like. Furthermore, it is preferable to use a carrier whose surface microstructure is controlled, for example, the surface unevenness.
[0069]
Therefore, in the case of producing a carrier, generally, a method in which carrier core particles are generated in advance by firing and granulating the inorganic oxides listed above, and then the particle surface is coated with a resin. Is used. From the viewpoint of reducing the load on the toner of the carrier, a method of obtaining a low density dispersed carrier by kneading and classifying the inorganic oxide and the resin, and further, directly kneading the inorganic oxide and the monomer. It is also possible to use a method for obtaining a polymerized carrier by suspension polymerization in an aqueous medium to obtain a spherical dispersion carrier.
Among these, a system in which the carrier particle surface is coated with a resin or the like is particularly preferable. As the method, any conventionally known method such as a method in which a coating material such as a resin is dissolved or suspended in a solvent and applied to adhere to the carrier particle surface, or a method of simply mixing with a powder can be applied. .
[0070]
The substance fixed to the carrier surface varies depending on the toner material, for example, polytetrafluoroethylene, monochlorotrifluoroethylene polymer, polyvinylidene fluoride, silicone resin, polyester resin, metal compound of ditertiary butylsalicylic acid, styrenic resin, Acrylic resin, polyamide, polyvinyl butyral, nigrosine, amino acrylate resin, basic dye and its lake, silica fine powder, alumina fine powder, etc. are suitably used singly or plurally, but are not necessarily limited thereto. .
The treatment amount of the above compound is generally 0.1 to 30% by weight, preferably 0.5 to 20% by weight, based on the carrier in total amount. The average particle size of these carriers is 10 to 100 μm, preferably 20 to 50 μm.
[0071]
As a particularly preferred embodiment of the carrier, carrier core particles are prepared with Cu-Zn-Fe ternary ferrite, and the surface of the particles is a combination of a resin such as a fluorine resin and a styrene resin, for example, polyvinylidene fluoride and Styrene-methyl methacrylate resin; polytetrafluoroethylene and styrene-methyl methacrylate resin, fluorine-based copolymer and styrene-based copolymer; etc. 90:10 to 20:80, preferably 70:30 to 30:70 The above average having a coating amount of 0.01 to 5% by weight, preferably about 0.1 to 1% by weight, and a carrier particle of 250 mesh pass and 400 mesh on is 70% by weight or more. Examples thereof include a coated ferrite carrier having a particle size. Examples of the fluorine-based copolymer include vinylidene fluoride-tetrafluoroethylene copolymer (10:90 to 90:10). Examples of the styrene-based copolymer include styrene-2-ethylhexyl acrylate (20:80). -80: 20), styrene-methyl 2-ethylhexyl acrylate (20-60: 5-30: 10-50).
The above-mentioned coated ferrite carrier has a sharp particle size distribution, gives preferable triboelectric chargeability to the yellow toner of the present invention, and further has an effect of improving electrophotographic characteristics.
[0072]
When the two-component developer is prepared by mixing the yellow toner of the present invention and the carrier as described above, the mixing ratio is 2 to 15% by weight, preferably 4 to 4 as the toner concentration in the developer. When it is 13% by weight, good results are usually obtained. If the toner concentration is less than 2% by weight, the image density is low and impractical, and if it exceeds 15% by weight, fogging and in-machine scattering are increased and the useful life of the developer is shortened.
[0073]
Furthermore, it is preferable to use a carrier having the following magnetic characteristics. Magnetization strength at 1000 oersted after magnetic saturation (σ ₁₀₀₀ ) Is 30 to 300 emu / cm ^Three It is necessary to be. Furthermore, in order to achieve high image quality, preferably 100 to 250 emu / cm. ^Three Are preferably used. Magnetization strength is 300 emu / cm ^Three If it is larger, it becomes difficult to obtain a high-quality toner image. On the other hand, 30 emu / cm ^Three If it is less than this, the magnetic binding force is also reduced, and carrier adhesion is likely to occur.
[0074]
Next, a fixing unit used in the image forming method of the present invention will be described.
FIG. 2 is a diagram showing a configuration example of a fixing device that can be preferably used in the present invention. In the figure, reference numeral 23 denotes a fixing roller. A pressure roller 24 is in pressure contact with the fixing roller 23, and is driven to rotate while forming a nip portion with the fixing roller 23. The fixing roller 23 is in the form of a hollow cylinder, and a halogen heater 25 is built in the hollow space to supply heat necessary for fixing. The pressure roller 24 is heated by a halogen heater 25. The temperature control of the roller is performed by placing the thermistor 28 as a temperature detection element in a non-sheet passing area of the fixing roller 23 or the pressure roller 24 in contact with the thermistor 28 and changing the resistance value according to the detected temperature. The temperature is detected, and the current control of the halogen heater 25 is performed by a control device (not shown) so that the roller surface temperature becomes a predetermined value.
[0075]
In the apparatus as described above, the unfixed transfer material is guided by the guide 62, enters the nip portion from the right side, is pressurized and heated by the surface of the fixing roller 23, fixed, and then discharged. Reference numeral 29 denotes a separation claw between the fixed transfer material and the fixing roller 23 or the pressure roller 24.
[0076]
The configuration of the fixing roller 23 is required to provide an elastic layer of several tens of μm or more on the core shaft of aluminum or the like in order to follow the thickness (several to several tens of μm) of the single color to four colors of the multiple toner 1 of the color image. It is. If the elasticity is small, the resolution of the toner is not fixed and the resolution is lowered due to toner crushing. As the material of the elastic layer, methyl or methyl vinyl liquid silicone rubbers RTV and LTV types are suitable because they have elasticity. For the surface layer, the above-mentioned RTV or LTV may be used, and a layer having a multilayer structure in which a heat resistant HTV layer is provided in the lower layer to prevent thermal deterioration and peeling of the surface back surface may be used.
In Examples and Comparative Examples of the present invention described later, an LTV type elastic layer 22 of dimethyl silicone rubber having a rubber hardness (Asker C) of 15 degrees is provided on an aluminum core bar 21 and a PFA tube layer is provided thereon. What provided 63 micrometers 50m was shape | molded and used for 46 mm diameter. At this time, the product hardness of the fixing roller 23 was 60 degrees in Asker C. It should be noted that methylphenyl silicone rubber can also be used as the elastic layer material.
[0077]
The configuration of the pressure roller 24 can be simplified because the elasticity may be smaller than that of the fixing roller 23 described above, and the aluminum core shaft may be simply provided with a layer such as HTV or fluoro rubber. Of course, it is possible to use one having substantially the same configuration as the fixing roller.
In examples and comparative examples of the present invention to be described later, as the pressure roller 24, an LTV type elastic layer 22 of dimethyl silicone rubber having a rubber hardness (Asker C) of 15 degrees is provided on the aluminum core 21 by 1.5 mm. A PFA tube layer 63 having a thickness of 50 μm was formed into 46 mmφ and used. At this time, the product hardness was 60 degrees in Asker C. In addition, as a rubber which is a constituent material of the fixing roller and the pressure roller, a methylphenyl silicone rubber may be used.
[0078]
In examples and comparative examples of the present invention described later, the fixing device having the above-described configuration was used, the fixing temperature was 180 ° C. and the ripple was within ± 3 ° C., and the applied pressure was 40 to 60 kgf.
[0079]
Next, various measurement methods used in the present invention will be described.
[Measurement of charge amount of pigment and dye]
The charge amount of the pigment and the dye is obtained by mixing 99.5 parts by weight of a resin-coated ferrite carrier with 0.5 parts by weight of the pigment or dye, and then leaving the mixture at room temperature and normal pressure for 24 hours. After shaking for 2 minutes, the measurement was performed as follows. As the ferrite carrier used at this time, a ternary ferrite core of Cu—Zn—Fe (Fe: about 50%, Cu: about 10%, Zn: about 10%), polyvinylidene fluoride and styrene— A mixture prepared by coating about 1% by weight of a mixture of methyl methacrylate copolymer in a ratio of 50:50 was used so that 250 mesh pass and 350 mesh on would be 70% by weight or more.
[0080]
FIG. 1 is an explanatory diagram of a charge amount measuring apparatus that measures the tribo charge amount of toner. First, in a metal measuring container 102 having a 500-mesh screen 103 at the bottom, a mixture of toner and carrier to be measured for triboelectric charge is put into a polyethylene bottle having a capacity of 50 to 100 ml. And about 0.5 to 1.5 g of the mixture (developer) is added and a metal lid 104 is formed. Weigh the entire measurement container 102 at this time, and calculate its value as W ₁ (G). Next, in the suction machine 101 (at least the insulator is in contact with the measurement container 102), suction is performed from the suction port, and the air volume control valve 106 is adjusted to set the pressure of the vacuum gauge 105 to 250 mmAq. In this state, the toner is removed by suction for 2 minutes. The potential of the electrometer 109 at this time is set to V (volt). Here, reference numeral 108 denotes a capacitor having a capacity C (μF). Next, weigh the entire measurement container after suction. ₂ (G). The triboelectric charge amount (mC / kg) of the toner is calculated by the following equation using the value measured above. The measurement results are shown in Table 1.
[0081]
[Expression 1]

[0082]
[Method of measuring color and chromaticity of pigments and dyes]
0.5 parts by weight of the pigment or dye to be measured was mixed with 30 parts by weight of toluene, and dispersed for 12 hours using a paint shaker in the presence of 30 parts by weight of 1 mm diameter glass beads. Thereafter, 10 parts by weight of a St / BA resin (St / BA ratio of 80/20, Tg of 70 degrees, Mw = 100,000, Mn = 20,000) was added, and dispersion was performed again for 3 hours. The dispersion solution thus obtained was subjected to No. 1 on a standard concealment rate test paper (manufactured by Nippon Test Panel Industry). A test bar for measurement was prepared by coating using a 16 bar coater.
Brightness L of the white color of the obtained test paper ^* , A ^* , B ^* , Saturation C ^* , Hue angle h ^* Was measured using X-RITE SP68 (D65, viewing angle 2 degrees; manufactured by X-RITE). The results are shown in Table 1.
[0083]
[Color evaluation method for low gloss images]
A developer is prepared by mixing 93 parts by weight of an acrylic resin-coated ferrite carrier with 7 parts by weight of toner. Next, using the obtained developer, the fixing unit is changed to a fixing unit as shown in FIG. 2 and modified by a Canon full-color copier CLC700. Specifically, the fixing unit is fixed. The latent image was transferred onto a transfer material with a modified machine that was variable in temperature, made of a fluorine-based material for the upper and lower rollers, and omitted the fixing oil application mechanism, and an image was obtained.
Fixing conditions at this time were as follows: a basis weight of 99 g / m with a glossiness of 4 as a transfer material ² Of toner and the toner paste amount is 0.5 to 0.7 mg / cm. ² And the fixing temperature was adjusted so that the glossiness of the obtained image measured at an incident angle of 75 degrees was 15-20.
The density condition of each color is adjusted so that the gray scale can be reproduced as faithfully as possible in a full-color copy image using a gray scale and color patch manufactured by Kodak Co. as the original, and the maximum density of a yellow (Y) single-color copy is 1. The concentration was adjusted to be 1 or more.
Then, in the Canon full-color copier CLC700 modified in the above state, red (Y (Y) magenta (M) superposed image of green (G) and yellow (Y) magenta (M)). About (R), it was taken out under fixing conditions having a glossiness of 20 to 25, and at this time, the overlapping portion at the highest density of each color was evaluated by the color tone difference from a color patch manufactured by Kodak.
[0084]
The evaluation is performed in five stages, and the brightness L of the image ^* , Saturation C ^* , Hue angle h ^* The CMC (1: 1) chromaticity difference formula was introduced, and the value of ΔE (chromaticity difference) when the value of Comparative Example 1 was taken as 100 was determined and evaluated according to the following criteria. The obtained results are shown in Table 2-1.
×: ΔΕ> 100
Δ: 90 <ΔE ≦ 100
○ △: 70 <ΔE ≦ 90
○: ΔE ≦ 70
The CMC formula is a chromaticity formula proposed in Journal of the Society of Dyers and Colorists, 100, 128 (1984). ^* , Saturation C ^* , Hue angle h ^* Is evaluated by adding a visual correction, and is expressed by the following equation.
[0085]
[Expression 2]

The brightness L of the image ^* , Saturation C ^* , Hue angle h ^* Measurement of X-RITE SP68 (D65, viewing angle 2 degrees; manufactured by X-RITE) was used.
[0086]
The coloring power was measured with a reflection densitometer RD-918 (manufactured by Macbeth Co., Ltd.) for a solid image part having a glossiness of 15 to 20 measured at an incident angle of 75 degrees. It measured using PG-3G (Nippon Denshoku Industries Co., Ltd .; incident angle 75 degree | times) for a glossiness meter.
The light resistance was ranked by observing the degree of fading after irradiation at 63 degrees 60 hours with a fade meter (carbon arc lamp).
[0087]
[Transparency transmission image evaluation method]
The transmittance of the transparency sheet image is evaluated as follows.
Using a full color copier (CLC700; manufactured by Canon Inc.), a transfer machine is developed and transferred on a transparency sheet (CG3700: manufactured by 3M) at a development contrast of 320 V in an environment of a temperature of 23 degrees / humidity of 60% RH. An unfixed toner image having gradation was obtained. The obtained toner image was subjected to fixing at a fixing temperature of 180 degrees and a process speed of 30 mm / mm with an external fixing device (configuration shown in FIG. 2) (no oil application function; roller diameter 40φ) whose surface of the fixing roller is a fluororesin. The image was fixed in sec and a fixed image was obtained. And the transmittance | permeability of the location of the image density of 0.4-0.6 of the obtained fixed image was measured.
[0088]
A Shimadzu self-spectrophotometer UV2200 (manufactured by Shimadzu Corporation) was used for the measurement of transmittance. The transmittance of the transparency sheet alone was taken as 100%, and the transmittance at the maximum absorption wavelength at 600 nm was measured. The evaluation was made according to the following criteria, and the results are shown in Table 2-1.
○: Transmittance is 75% or more
◯: The transmittance is 65% or more and less than 75%
Δ: Transmittance is 55% or more and less than 65%
X: Transmittance is less than 55%
[0089]
As for the color space measurement of transmitted light, the obtained image was converted to a transmitted image with an overhead projector (OHP: 9550, manufactured by 3M), and the image projected on the white wall surface was converted into a spectral radiance meter (PR650, manufactured by Photo Research). ). The hue angle h of the image projected on the white wall surface ^* (OHP) and the hue angle h of the solid portion on the paper measured previously. ^* Hue angle difference Δh from (paper) ^* Were defined as shown below, and evaluated in five stages, and are shown in Table 2-1.
×: Δh ^* > 20
Δ ×: 15 <Δh ^* ≦ 20
Δ: 10 <Δh ^* ≦ 15
○ △: 5 <Δh ^* ≦ 10
○: Δh ^* ≦ 5
[0090]
[Continuous paper image evaluation method]
Using a full color copier (CLC700; manufactured by Canon Inc.), high temperature and high humidity H / H (temperature 30 degrees / humidity 80% RH) and room temperature low humidity N / L (temperature 23 degrees / humidity 5% RH) Under the environment, the image is developed and transferred at a development contrast of 320 V on CLC paper (80 g paper) as a transfer material, an image with a 5% image area ratio is formed, and 50,000 sheets are continuously fed. In the above, the image density, the measurement of the fog on the white solid portion, and the charge amount of the developer were measured and evaluated by the following methods.
[0091]
(About image density)
It measured based on the method of the above-mentioned coloring power measurement, and the measured value was shown to Table 2-2 and Table 2-3.
[0092]
(About measurement of fogging)
The fog was measured using a REFECTOMETER MODEL TC-6DS (manufactured by Tokyo Denshoku). For the yellow toner image, a blue filter was used and calculated according to the following formula. The measured values are shown in Tables 2-2 and 2-3. The smaller the fog value, the better.
[Equation 3]

[0093]
(Charge amount)
The measurement was performed according to the above-described method for measuring the charge amount, and the measured values are shown in Table 2-2 and Table 2-3.
[0094]
【Example】
Examples, Reference example The present invention will be described more specifically with reference to comparative examples.
<Example 1>
First, 0.1M Na _Three PO _Four Aqueous solution and 1.0M CaCl ₂ Prepare an aqueous solution. In a 2 liter four-necked flask equipped with a high-speed stirrer homomixer, 710 parts by weight of ion-exchanged water and 0.1 M Na _Three PO _Four After adding 550 parts by weight of the aqueous solution, the solution was heated to 65 ° C. while adjusting the rotation speed to 10,000 rotations. Next, in this, 1.0M-CaCl ₂ Gradually add 80 parts by weight of an aqueous solution and add a fine, poorly water-soluble dispersant Ca _Three (PO _Four ) ₂ An aqueous dispersion medium containing was prepared.
[0095]
On the other hand, the dispersoid system was prepared as follows.
・ 160 parts by weight of styrene monomer
・ 40 parts by weight of n-butyl acrylate monomer
・ Coloring agent 1 Chromophthal yellow 3G Ciba Specialty Chemicals
[C. I. Pigment Yellow 93 (average particle size 0.09 μm)] 8 parts by weight
-Colorant 2 Oraset Yellow GHS Ciba Specialty Chemicals
[C. I. Solvent Yellow 163] 6 parts by weight
・ Saturated polyester 8 parts by weight
・ 4 parts by weight of salicylic acid metal compound
・ 0.2 parts by weight of divinylbenzene
Release agent <monoester wax: Mw = 650, Mn = 500, SP value =
9.0, melting point 65 ° C., melt viscosity 9.2 (m · pa · s)> 30 parts by weight
After the mixture having the above composition was dispersed for 3 hours using an attritor, 5 parts by weight of 2,2′-azobis (2,4-dimethylvaleronitrile) as a polymerization initiator was added, and the dispersion was dispersed. Prepared.
[0096]
The dispersion prepared above was put into the previously prepared aqueous dispersion medium and granulated for 15 minutes while adjusting the rotation to 10,000 rpm. Then, the stirrer was changed from a high-speed stirrer to a propeller stirring blade, and while stirring at 350 rpm, the polymerization reaction was continued at an internal temperature of 70 ° C. for a total of 8 hours to obtain a slurry. After completion of the polymerization, the slurry was cooled and diluted hydrochloric acid was added to remove the dispersant. Further, after washing, drying was performed to obtain a yellow toner of this example. Next, 2% of hydrophobized titanium oxide was externally added to the obtained toner to obtain a yellow toner of this example having excellent fluidity.
[0097]
A two-component developer was prepared by mixing 93 parts by weight of an acrylic resin-coated ferrite carrier with 7 parts by weight of the toner obtained above. Images and transparency images were obtained with a Canon full-color copier CLC700 modified as described above.
When the obtained image was evaluated, as shown in Table 2-1, there was almost no change in hue angle between the image on paper and the transparent transmission image, and the OHP transparency was excellent. It was a thing.
[0098]
Further, one colorant is added when preparing the dispersion system as described above, and C.I. I. A cyan toner was produced in the same manner as described above except that Pigment Blue 15: 3 was changed to 14 parts by weight. Using the obtained cyan toner and the yellow toner of this example, a green image that is a secondary color of these was formed, and when the reproducibility of the green image was confirmed, a clear green image and a transparent transmission image were obtained. It was.
[0099]
Further, the colorant to be added is C.I. I. A magenta toner was produced in the same manner except that the pigment red 122 was changed to 14 parts by weight. Using the obtained magenta toner and the yellow toner of this example, the reproducibility of red as the secondary color was confirmed. As a result, a clear red image and a transparent transmission image were obtained.
[0100]
<Example 2>
The yellow toner of this example was manufactured in the same manner as in Example 1 except that the colorant formulation was changed as described below in the formulation used in Example 1.
・ Coloring agent 1 Chromophthal yellow 8GN Ciba Specialty Chemicals
[C. I. Pigment Yellow 128 (average particle size 0.14 μm)] 6 parts by weight
-Colorant 2 Oraset Yellow GHS Ciba Specialty Chemicals
[C. I. Solvent Yellow 163] 8 parts by weight
For the yellow toner of this example obtained above, an image was formed in the same manner as in Example 1, and each evaluation was performed. As a result, good results were obtained as shown in Tables 1 and 2.
[0101]
<Example 3>
The yellow toner of this example was manufactured in the same manner as in Example 1 except that the colorant formulation was changed as described below in the formulation used in Example 1.
・ Colorant 1 PV First Yellow H2G Clariant
[CI Pigment Yellow 120 (average particle size 0.26 μm)] 10 parts by weight
-Colorant 2 Oraset Yellow GHS Ciba Specialty Chemicals
[C. I. Solvent Yellow 163] 4 parts by weight
[0102]
<Example 4>
The yellow toner of this example was manufactured in the same manner as in Example 1 except that the colorant formulation was changed as described below in the formulation used in Example 1.
・ Colorant 1 Made by Clariant
[C.I. Pigment Yellow 173 (average particle size 0.17 μm)] 8 parts by weight
-Colorant 2 Oraset Yellow GHS Ciba Specialty Chemicals
[C. I. Solvent Yellow 163] 6 parts by weight
For the yellow toner of this example obtained above, an image was formed in the same manner as in Example 1, and each evaluation was performed. As a result, good results were obtained as shown in Tables 1 and 2.
[0103]
<Example 5>
The yellow toner of this example was manufactured in the same manner as in Example 1 except that the pigment used in Example 1 was changed to a compound in which (pigment) was extended to a particle size of 0.60 μm.
For the yellow toner of this example obtained above, an image was formed in the same manner as in Example 1, and each evaluation was performed. As a result, good results were obtained as shown in Tables 1 and 2.
[0104]
<Example 6>
The yellow toner of this example was manufactured in the same manner as in Example 1 except that the amount of ester wax added in the formulation used in Example 1 was changed from 30 parts by weight to 110 parts by weight. .
For the yellow toner of this example obtained above, an image was formed in the same manner as in Example 1, and each evaluation was performed. As a result, good results were obtained as shown in Tables 1 and 2.
[0105]
<Example 7>
In the formulation used in Example 1, colorant 1 was C.I. I. The yellow toner of this example was manufactured in the same manner as in Example 1 except that the pigment was changed to CI Pigment Yellow 199 and the metal salicylic acid compound was changed to a quaternary ammonium salt charge control agent.
For the yellow toner of this example obtained above, an image was formed in the same manner as in Example 1, and each evaluation was performed. As a result, good results were obtained as shown in Tables 1 and 2.
[0106]
< reference Example 1 >
In the same manner as in Example 1 except that the release agent was changed from ester wax to polypropylene wax in the formulation used in Example 1, reference An example yellow toner was produced.
The book obtained above reference For the yellow toner of the example, an image was formed in the same manner as in Example 1, and each evaluation was performed. As a result, good results were obtained as shown in Tables 1 and 2.
[0107]
<Example 9>
Two kinds of colorants and charge control agents for 100 parts by weight of polyester resin (bisphenol A diol-terephthalic acid-trimellitic acid condensate, monomer mixing weight ratio = 50: 45: 5, MW = 55,000) And a release agent were added in the following composition, followed by melting, kneading, pulverization, and classification to produce a yellow toner of this example.
・ Coloring agent 1 Chromophthal yellow 3G Ciba Specialty Chemicals
[C. I. Pigment Yellow 93 (average particle size 0.09 μm)] 4 parts by weight
-Colorant 2 Oraset Yellow GHS Ciba Specialty Chemicals
[C. I. Solvent Yellow 163] 3 parts by weight
・ 2 parts by weight of metal salicylate
Release agent <monoester wax: Mw = 650, Mn = 500, SP value =
9.0, melting point 65 ° C., melt viscosity 9.2 (m · pa · s)> 5 parts by weight
For the yellow toner of this example obtained above, an image was formed in the same manner as in Example 1, and each evaluation was performed. As a result, good results were obtained as shown in Tables 1 and 2.
[0108]
<Comparative Example 1>
The yellow toner of this comparative example was manufactured in the same manner as in Example 1 except that only the pigment having the following formulation was used as the colorant in the formulation used in Example 1.
・ Coloring agent Chromophthal yellow 8GN Ciba Specialty Chemicals
[CI Pigment Yellow 128 (average particle size 0.14 μm)] 14 parts by weight
[0109]
<Comparative example 2>
The yellow toner of this comparative example was manufactured in the same manner as in Example 1 except that only the dye having the following formulation was used as the colorant in the formulation used in Example 1.
・ Coloring agent Oraset Yellow GHS Ciba Specialty Chemicals
[C. I. Solvent Yellow 163] 14 parts by weight
[0110]
<Comparative Example 3>
The yellow toner of this comparative example was produced in the same manner as in Example 1 except that the following formulation was used as the colorant among the formulations used in Example 1.
・ Colorant 1 PV First Yellow H2G Clariant
[CI Pigment Yellow 120 (average particle size 0.26 μm)] 8 parts by weight
Colorant 2 [C. I. Solvent Yellow 15] 6 parts by weight
[0111]
<Comparative example 4>
The yellow toner of this comparative example was produced in the same manner as in Example 1 except that the following formulation was used as the colorant among the formulations used in Example 1.
・ Colorant 1
[C.I. Pigment Yellow 139 (average particle size 0.31 μm)] 8 parts by weight
・ Coloring agent 2 Oraset Yellow GHS Ciba Specialty Chemicals
[C. I. Solvent Yellow 163] 6 parts by weight
[0112]
[Table 1]

[0113]
[Table 2]

[0114]
[Table 3]

[0115]
[Table 4]

[0116]
[Table 5]

[0117]
【The invention's effect】
As described above, according to the present invention, a pigment and a dye having a specific hue range are used as the colorant, and more preferably, the charge amount difference between the pigment and the dye is controlled within a specific range. Therefore, the yellow toner having excellent developability and high coloring power even when an image having a low glossiness is formed, and further capable of obtaining an image having excellent transparency even when used as an overhead projector film, and the yellow toner An image forming apparatus using toner is provided. Furthermore, according to the present invention, there is provided a method for producing a yellow toner from which a yellow toner having the above excellent characteristics can be easily obtained.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram of an apparatus for measuring the charge amount of toner.
FIG. 2 is a schematic explanatory diagram of an image heating and fixing apparatus that can be used in the image forming method of the present invention.
[Explanation of symbols]
23: fixing roller
24: Pressure roller
25: Halogen heater
28: Thermistor
29: Separation nail
62: Guide
101: Suction machine
105: Vacuum gauge
106: Air flow control valve

Claims (5)

C. a yellow dye and at least one yellow pigment . I. A toner containing Solvent Yellow 163 , wherein the yellow pigment is C.I. I. Selected from the group consisting of CI Pigment Yellow 93,120,128,173,199, and the chromaticity of the white paper exhibition color of the yellow pigment, L ^* value 60.0 to 95.0, a ^* value There -25.0 to -8.0, and b ^* are values to Tasu60.0 Tasu115.0, and the chromaticity of the white paper exhibition color of the yellow dye, the value of L ^* is 60.0 A yellow toner having a value of -92.0 to 95.0, a ^* value of -12.0 to +10.0, and b ^* value of +60.0 to +115.0. The yellow toner according to claim 1, wherein the yellow pigment has a number average diameter of 0.01 to 0.70 μm. The yellow toner according to claim 1 or 2 , wherein the toner contains 5 to 30% by weight of a low softening point substance. At least one or more of C. a yellow pigment and yellow dye I. In the toner production method of producing a toner by polymerizing a polymerizable monomer system containing Solvent Yellow 163 , the yellow pigment is C.I. I. Selected from the group consisting of CI Pigment Yellow 93,120,128,173,199, and, as the yellow pigment, the chromaticity of the white paper exhibition color, the value of L ^* is 60.0 to 95.0, a ^* of A yellow pigment having a value of −25.0 to −8.0 and a value of b ^* of +60.0 to +115.0 is used, and the chromaticity in the color development on white paper is L as the yellow dye. ^A yellow dye having a value of ^* of 60.0 to 95.0, a value of a ^* of -12.0 to +10.0, and a value of b ^* of +60.0 to +115.0 is used. Toner manufacturing method. The developer having toner carried on the developer carrying member is conveyed to the developing area, and the electrostatic latent image formed on the image carrying member in the developing area is developed with the developer to form a toner image on the image carrying body. A heating roller formed on the recording material to transfer the toner image onto a recording material, a heat-resistant rubber base layer, a fixing roller having a fluororesin surface layer on the surface of the base layer, and a pressure roller in pressure contact with the fixing roller; In the image forming method in which a toner image is fixed on a recording material by a pressure fixing unit, C.I. I. A yellow toner containing Solvent Yellow 163 , wherein the yellow pigment is C.I. I. Selected from the group consisting of CI Pigment Yellow 93,120,128,173,199, and the chromaticity of the white paper exhibition color of the yellow pigment, L ^* value 60.0 to 95.0, a ^* value There -25.0 to -8.0, and b ^* are values Tasu60.0 to Tasu115.0, chromaticity of white paper exhibition color of the yellow dye, L ^* value 60.0 to 95 0.0, at least a yellow toner having an a ^* value of -12.0 to +10.0, and a b ^* value of +60.0 to +115.0, and as the fixing roller and pressure roller, An image forming method using an Asker C having a product hardness of 50 to 80 degrees.

Images