JP4392946B2 - Toner and method for producing non-magnetic toner particles - Google Patents

Description

【００２５】
【数２】

また、モード円形度とは、円形度を０．４０から１．００までを、０．４００以上０．４１０未満、０．４１０以上０．４２０未満、．．．、０．９９０以上１．０００未満及び１．０００の如くに、０．０１毎に６１分割し、測定した各粒子の円形度を円形度に応じて各分割範囲に割り振り、円形度頻度分布において頻度値が最大となる分割範囲の下限値である。
【００２６】
なお、本発明で用いている測定装置である「ＦＰＩＡ−１０００」は、各粒子の円形度を算出後、平均円形度の算出に当たって、粒子を得られた円形度によって、円形度０．４０〜１．００を６１分割したクラスに分け、分割点の中心値と頻度を用いて平均円形度の算出を行う算出を行う算出法を用いている。しかしながら、この算出式で算出される平均円形度の各値との誤差は、非常に少なく、実質的に無視出来る程度のものであり、本発明においては、算出時間の短縮化や算出演算式の簡略化の如きデータの取り扱い上の理由で、上述した各粒子の円形度を直接用いる算出式の概念を利用し、一部変更したこのような算出式を用いても良い。
【００２７】
測定手段としては以下の通りである。界面活性剤を約０．１ｍｇ溶解している水１０ｍｌに現像剤５ｍｇを分散させて分散液を調製し、超音波（２０ｋＨｚ、５０Ｗ）を分散液に５分間照射し、分散液濃度を５０００〜２万個／μｌとして前記装置により測定を行い、現像剤の平均円形度及びモード円形度を求める。
本発明における平均円形度とは、現像剤の凹凸の度合いの指標であり、現像剤が完全な球形の場合１．０００を示し、表面形状が複雑になるほど円形度は小さな値となる。
【００２８】
また、平均円形度が高い場合でも主として存在する粒子の円形度が低いと効果が不十分な場合もあるため、特にモード円形度が０．９９０以上であると、円形度が０．９９０以上の粒子が主として存在することから、上記に効果が顕著に現れれるので好ましい。
【００２９】
本発明のトナーの構成材料である結着樹脂は、主としてスチレン系結着樹脂を含有しており、このスチレン系結着樹脂は過酸化物系重合開始剤を用いて、スチレンを含む単量体を重合させて得られたものである。一般に使用されている重合開始剤としてはアゾ系重合開始剤もあるが、アゾ系重合開始剤のみを用いた場合には本発明の効果は得られない。すなわち、アゾ系重合開始剤は開始剤効率が低く、生成したラジカル種がラジカルカップリングを起こして多量の開始剤分解物を副生し、この分解物は高沸点の液状物または低融点の結晶物であるため製造工程で除去することが非常に困難であり、この分解物はトナー中に多量に残留することになる。この分解物はある程度の極性を有しているため、例えば重合法によりトナーを製造した場合には、トナー粒子の表面近くに存在しやすく、トナー中の顔料やワックス成分の分散不良、定着性の悪化、トナーの帯電性能や耐保存性に大きな問題が生じさせたり、プリントアウト時に分解物の不快な臭気が発生するといった問題がある。また、トナーに残留するスチレンモノマーについても、過酸化物系重合開始剤を使用した場合に比較して非常に多くなり、充分な精製工程を行わないと、プリントアウト時にモノマー臭を発生することがある。その点、過酸化物系重合開始剤を用いた場合には、開始剤分解物の生成量が少なく、また、分解物のトナーからの除去は比較的容易で、残留スチレンも非常に低く抑えることが可能となる。このため過酸化物系重合開始剤を用いた場合には、本発明の効果である環境変動によらず安定した帯電性、優れた定着性が達成され、スチレンモノマーや分解物の臭気が発生することもない。
【００３０】
本発明で使用される過酸化物系重合開始剤としては、パーオキシエステル、ジアシルパーオキサイドなどがあり、これらのうちでは、パーオキシエステルが特に残留スチレンの抑制には効果的であり、また、過酸化物の水素引き抜き反応による結着樹脂のゲル化も抑制されるため、低温定着性の観点から有利であり好ましい。パーオキシエステルの中では、ｔ−ブタノールのパーオキシエステルが更に好ましい。また、パーオキシエステルとジアシルパーオキサイドとを混合して使用してもよい。
本発明で使用できるパーオキシエステルとしては、例えば、ｔ−ブチルパーオキシアセテート、ｔ−ブチルパーオキシラウレート、ｔ−ブチルパーオキシピバレート、ｔ−ブチルパーオキシ−２−エチルヘキサノエート、ｔ−ブチルパーオキシイソブチレート、ｔ−ブチルパーオキシネオデカノエート、ｔ−ヘキシルパーオキシアセテート、ｔ−ヘキシルパーオキシラウレート、ｔ−ヘキシルパーオキシピバレート、ｔ−ヘキシルパーオキシ−２−エチルヘキサノエート、 ｔ−ヘキシルパーオキシイソブチレート、ｔ−ヘキシルパーオキシネオデカノエート、ｔ−ブチルパーオキシベンゾエート、α，α’−ビス（ネオデカノイルパーオキシ）ジイソプロピルベンゼン、クミルパーオキシネオデカノエート、１，１，３，３−テトラメチルブチルパーオキシ−２−エチルヘキサノエート、１，１，３，３−テトラメチルブチルパーオキシネオデカノエート、１−シクロヘキシル−１−メチルエチルパーオキシネオデカノエート、２，５−ジメチル−２，５−ビス（２−エチルヘキサノイルパーオキシ）ヘキサン、１−シクロヘキシル−１−メチルエチルパーオキシ−２−エチルヘキサノエート、ｔ−ヘキシルパーオキシイソプロピルモノカーボネート、ｔ−ブチルパーオキシイソプロピルモノカーボネート、ｔ−ブチルパーオキシ２−エチルヘキシルモノカーボネート、ｔ−ヘキシルパーオキシベンゾエート、２，５−ジメチル−２，５−ビス（ベンゾイルパーオキシ）ヘキサン、ｔ−ブチルパーオキシ−ｍ−トルオイルベンゾエート、ビス（ｔ−ブチルパーオキシ）イソフタレート、ｔ−ブチルパーオキシマレイックアシッド、ｔ−ブチルパーオキシ−３，５，５−トリメチルヘキサノエート、２，５−ジメチル−２，５−ビス（ｍ−トルオイルパーオキシ）ヘキサンなどのパーオキシエステル、ベンゾイルパーオキサイド、ラウロイルパーオキサイド、イソブチリルパーオキサイド、スクシニックパーオキサイドなどのジアシルパーオキサイド、その他としてｔ−ブチルパーオキシアリルモノカーボネート等が挙げられる。これらのうちでは、残留スチレンの削減、低温定着性（結着樹脂のゲル化の抑制）に好適なものは、パーオキシエステルである。尚、必要に応じてこれら過酸化物を２種以上用いることもできるし、本発明の効果を損なわない範囲で、２，２’−アゾビス−（２，４−ジメチルバレロニトリル）、２，２’−アゾビスイソブチロニトリル、１，１’−アゾビス（シクロヘキサン−１−カルボニトリル）、２，２’−アゾビス−４−メトキシ−２，４−ジメチルバレロニトリル、アゾビスイソブチロニトリル等のアゾ系重合開始剤を併用することも可能である。
【００３１】
本発明で使用される過酸化物系重合開始剤は、単量体１００質量部に対して０．５〜２０質量部の添加量で重合反応を行なうと、分子量１万〜１０万の間に極大を有する重合体を得ることができ、トナーに望ましい強度と適当な溶融特性を与えることが出来る。
【００３２】
また、本発明で用いられる有機過酸化物系の重合開始剤の理論活性酸素量は４．０〜１２．０％の範囲にあることが好ましい。この理論活性酸素量が、４．０％よりも小さいと重合開始剤を多量に使用しなければならない傾向があり経済的に不利であり、１２．０％を超えると取り扱いおよび重合反応の制御が困難となる場合がある。
また、本発明に用いる過酸化物系重合開始剤の１０時間半減期温度は３０〜１００℃が好ましい。この半減期温度が３０℃より低いと取り扱いが困難となり、１００℃よりも高いと非常に高い温度での重合反応が必要になったり、所望の分子量とすることが困難で、低温定着性の観点から好ましくない。
【００３３】
本発明のトナーは、前記有機過酸化物に起因して生成するカルボン酸の含有量が、２０００ｐｐｍ未満であることが必須である。これは、本発明者らによる以下の知見によるものである。
有機過酸化物であるパーオキシエステルが熱分解を起こすと、対応するアルコールラジカルとカルボン酸ラジカルにまず分解し、その後これらのラジカル、およびカルボン酸ラジカルが脱炭酸して生成するアルキルラジカル等がモノマーへ付加することにより重合反応が進行する。同様に、ジアシルパーオキサイドが熱分解を起こすと、カルボン酸ラジカルにまず分解し、その後これらのラジカル、およびカルボン酸ラジカルが脱炭酸して生成するアルキルラジカルがモノマーへ付加することにより重合反応が進行する。しかし、重合トナーの製造においては、従来ほとんど副生しないと考えられてきたカルボン酸（このものはカルボン酸ラジカルが荷電制御剤、着色剤、モノマー、ポリマー等から水素を引き抜くことにより生成する）が多量に副生することが本発明者らの検討で判明した。また、このカルボン酸は、トナー中の荷電制御剤やワックス成分の分散性を高める傾向があり、安定した帯電性が得られやすく、低温定着性に優れることも本発明者らの検討で判明した。一方で、このカルボン酸は極性基を持つ親水性化合物であり、トナー中に２０００ｐｐｍを超えて含有されていると、トナーの環境安定性に影響を与え、高湿下では帯電性の低下、低湿下ではチャージアップを生じるということも本発明者らの検討により判明した。したがって、製造時にはこのようなカルボン酸は存在した方が好ましいが、製造後に除去を行い、２０００ｐｐｍ未満とすることではじめて環境変動によらず安定した帯電性を有し、優れた定着性のトナーが得られる。また、このカルボン酸の含有量が少ない方が、定着時の臭気は少なく、また、より安定した帯電性が得られるので、１０００ｐｐｍ以下とするのが好ましく、５００ｐｐｍ以下とすることが更にこのましい。
【００３４】
過酸化物系重合開始剤の分解により生成するカルボン酸としては様々なものがあり、重合開始剤の酸構造成分の種類により異なるが、２−エチルヘキサン酸、ネオデカン酸、ピバリン酸、イソ吉草酸、コハク酸、安息香酸、オクタン酸、ステアリン酸、ラウリン酸などが例示できる。
【００３５】
尚、トナー中の残留スチレンや前記したカルボン酸の定量は、ガスクロマトグラフィーにより次の様にして行うことができる。サンプル瓶にトナー約２５０ｍｇを精秤し、これに精秤した約１０ｇのアセトンを加えた後よく混合し、超音波洗浄機にて超音波を３０分間照射する。その後メンブランフィルター（例えばアドバンテック東洋（株）製 ディスポーザブルメンブランフィルター ２５ＪＰ０２０ＡＮ）を用いて濾過を行い、濾液２μｌをガスクロマトグラフィーで分析する。そして、予めスチレンやカルボン酸を用いて作成した検量線により、残留スチレンやカルボン酸の残存量を算出する。本願発明では、下記の条件により分析を行った。
【００３６】
ＧＣ：ＨＰ社 ６８９０ＧＣ
カラム：ＨＰ社 ＩＮＮＯＷａｘ（２００μｍ ×０．４０μｍ×２５ｍ）
キャリアーガス：Ｈｅ（コンスタントプレッシャーモード：２０ｐｓｉ）
オーブン：５０℃、１０ｍｉｎホールド、１０℃／ｍｉｎで２００℃まで昇温、２００℃、５ｍｉｎホールド。
ＩＮＪ：２００℃、パルスドスプリットレスモード（２０→４０ｐｓｉ、ｕｎｔｉｌ ０．５ｍｉｎ）
スプリット比：５．０：１．０
ＤＥＴ：２５０℃（ＦＩＤ）
本発明においては、トナー中の前記カルボン酸含有量を低く抑えることで、特に定着性が良好で、環境変動によらず安定した帯電性を有したトナーが得られる。トナー中のカルボン酸を除去するためには、トナー粒子を製造した後に真空乾燥や加熱乾燥により除去する方法、トナー粒子を懸濁させた水の蒸留を行い、水とともに留去する方法、トナーを懸濁した水をアルカリ性に調整して（必要により加熱や撹拌処理を行い）トナー粒子と前記カルボン酸の塩を含む水を分離する方法などがある。これらの方法の中では、最も効率が良く容易に実施できるという点で、アルカリ処理による方法を用いるのが好ましい。例えば、重合トナーの場合、重合が実質的に終了した後の水媒体に、炭酸ナトリウム、水酸化ナトリウム等のアルカリを加え、ｐＨ８〜１４、好ましくは９〜１３、さらに好ましくは１０〜１２に調整して加熱撹拌を行う。この操作により、トナー粒子中のカルボン酸を対応する水溶性のカルボン酸塩として水に溶出させることが可能である。この後に、懸濁液を例えば濾過すれば、カルボン酸塩は廃水へと流されてトナー中のカルボン酸は除去可能となる。ここで、ｐＨを１０〜１２の範囲とするとさらに好ましい理由は、カルボン酸の完全な中和を行うためと、結着樹脂中の官能基（例えばアクリル酸のエステル）の加水分解が抑制できるためである。また、アルカリ性とした重合懸濁液を、アルカリ性の状態のままでトナー粒子と水媒体とを実質的に分離することが非常に重要である。これは、例えば特開平１０−０２０５４８号公報に記載されているように、水媒体の分離工程を経ずに水媒体のｐＨを酸性にしてしまうと、水に溶けていたカルボン酸塩は再び水不溶性のカルボン酸に戻ってしまうため、カルボン酸のトナー粒子からの除去は非常に不完全なものとなるためである。尚、トナー粒子と水媒体との分離は、濾過、遠心分離など従来から公知の方法を適宜選択して行うことができる。
【００３７】
また、分散安定剤を用いた場合には、トナー製造後にこの分散剤を除去することが望ましく、分散剤がトナー表面に残存していると帯電性、特に環境安定性に大きな問題が生じる場合が多いので、できるかぎり除去を行うことが好ましい。例えばリン酸三カルシウムを分散剤として用いた場合には、該分散剤が酸性で水に溶解する性質を利用して、重合が修了した懸濁液に酸を添加することによりリン酸三カルシウムをほぼ完全に除去することが可能である。リン酸三カルシウムを溶解する際には、トナー粒子の懸濁している水系媒体のｐＨを４未満、より好ましくは２未満とすることで短時間にリン酸三カルシウムの除去が可能である。
【００３８】
本発明に用いられるワックス成分としては、例えばパラフィンワックス及びその誘導体、マイクロクリスタリンワックス及びその誘導体、フィッシャートロプシュワックス及びその誘導体、ポリオレフィンワックス及びその誘導体、カルナバワックス及びその誘導体などが挙げられる。ここで、誘導体には酸化物や、ビニル系モノマーとのブロック共重合物、グラフト変性物等が含まれる。更に、ワックス成分としては、高級脂肪酸およびその金属塩、高級脂肪族アルコール、高級脂肪族エステル、脂肪族アミドワックス、ケトン、硬化ヒマシ油及びその誘導体、植物系ワックス、動物性ワックス、鉱物系ワックス、ペトロラクタムなどが挙げられる。
【００３９】
これらのワックス成分は、示差走差熱量計により測定されるＤＳＣ曲線において、昇温時に４０〜１１０℃の領域に最大吸熱ピークを有するものが好ましい。この領域に最大吸熱ピークを有することにより、低温定着に大きく貢献しつつ、離型性をも効果的に発現することができるからである。最大吸熱ピークが４０℃未満であるとワックス成分の自己凝集力が弱くなり、結果として耐高温オフセット性が悪化するとともに、グロスが高くなりすぎてしまう。一方、最大吸熱ピークが１１０℃を越えると定着温度が高くなるとともに、定着画像表面を適度に平滑化せしめることが困難となるため、特にカラートナーに用いた場合には混色性低下の点から好ましくない。さらに、水系媒体中で造粒／重合を行い重合方法により直接トナーを得る場合、この最大吸熱ピーク温度が高いと主に造粒中にワックス成分が析出する等の問題を生じ好ましくない。従って、吸熱ピークが４０〜１１０℃の範囲にあるワックスを用いることが、低温定着性と高品位な画像が得られる点で好ましく、この吸熱ピークが４５〜９０℃の範囲にあるワックスを用いることが更に好ましい。
【００４０】
ワックス成分の最大吸熱ピーク温度の測定は、「ＡＳＴＭ Ｄ ３４１８−８」に準じて行う。測定には、例えばパーキンエルマー社製ＤＳＣ−７を用いる。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、熱量の補正についてはインジウムの融解熱を用いる。測定サンプルにはアルミニウム製のパンを用い、対照用に空パンをセットし、昇温速度１０℃／ｍｉｎで測定を行う。
本発明においては、これらのワックス成分の添加量は特に限定されないが、一般に結着樹脂に対して０．５〜５０質量％が好ましい。
【００４１】
本発明のトナーの構成材料である結着樹脂は、少なくともスチレン系結着樹脂を含有することが必須である。この際スチレン系結着樹脂は公知の方法を適宜選択して製造すればよく、スチレンモノマーと他の単量体を共重合することにより得ることができる。他の単量体としては、ｏ−メチルスチレン、ｍ−メチルスチレン、ｐ−メチルスチレン、ｍ−エチルスチレン、ｐ−エチルスチレンのようなスチレン系単量体、アクリル酸メチル、アクリル酸エチル、アクリル酸プロピル、アクリル酸ブチル、アクリル酸オクチル、アクリル酸ドデシル、アクリル酸ステアリル、アクリル酸ベヘニル、アクリル酸２−エチルヘキシル、アクリル酸ジメチルアミノエチル、アクリル酸ジエチルアミノエチルのようなアクリル酸エステル系単量体、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−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のような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、アクリルアミドのようにエン系単量体が好ましく用いられる。これらは出版物ポリマーハンドブック第２版ＩＩＩ−ｐ１３９〜１９２（Ｊｏｈｎ Ｗｉｌｅｙ＆Ｓｏｎｓ社製）に記載の理論ガラス転移温度（Ｔｇ）が、４０〜７５℃を示すように単量体を適宜混合して用いられる。理論ガラス転移温度が４０℃未満の場合にはトナーの保存安定性や耐久安定性の面から問題が生じやすく、一方７５℃を超える場合にはトナーの定着点の上昇をもたらす。特にフルカラー画像を形成するためのカラートナーの場合においては、各色トナーの定着時における混色性が低下して色再現性が乏しくなり、さらにＯＨＰ画像の透明性が低下するため好ましくない。
【００４２】
また、前記結着樹脂と併用して他の結着樹脂を用いることもでき、その材料によってはトナー粒子の最表層を他の結着樹脂で覆い、保存安定性や耐久性を向上させることも可能である。但し、他の結着樹脂を併用する場合でも、好ましくはスチレン−アクリル系樹脂の含有量が全結着樹脂に対して５０〜１００質量％、より好ましくは８０〜１００質量％の範囲で使用する。５０質量％よりも含有量が少ないと低温定着性と現像性のバランスを取るのが困難になるためである。
【００４３】
本発明のトナーを製造する場合には、得られたトナー粒子中の結着樹脂のＧＰＣにおける主たるピークの分子量は３，０００〜１００，０００であり、特に好ましくは５，０００〜５０，０００である。
【００４４】
本発明に係わるトナーを重合法により製造する場合には、単量体組成物に樹脂を添加して重合しても良い。例えば、単量体では水溶性のため水性懸濁液中では溶解して乳化重合を起こすため使用できないアミノ基、カルボキシル基、水酸基、スルホン酸基、グリシジル基、ニトリル基等の親水性官能基含有の単量体成分をトナー中に導入したい時には、これらとスチレンあるいはエチレン等ビニル化合物とのランダム共重合体、ブロック共重合体、あるいはグラフト共重合体等、共重合体の形にして、あるいはポリエステル、ポリアミド等の重縮合体、ポリエーテル、ポリイミン等の重付加重合体の形で使用が可能である。こうした極性官能基を含む高分子重合体をトナー中に共存させると、前述のワックス成分を相分離させ、より内包化が強力となり、耐オフセット性、耐ブロッキング性、低温定着性の良好なトナーを得ることができる。このような極性官能基を含む高分子重合体を使用する場合、その重合平均分子量は、５，０００以上が好ましく用いられる。分子量５，０００未満、とくに４，０００以下では、本重合体が表面付近に集中し易い事から、現像性、耐ブロッキング性等に悪い影響が起こり易くなり好ましくない。
また、材料の分散性や定着性、あるいは画像特性の改良等を目的として上記以外の樹脂を単量体系中に添加しても良く、用いられる樹脂としては、例えば、ポリスチレン、ポリビニルトルエンなどのスチレン及びその置換体の単重合体；スチレン−プロピレン共重合体、スチレン−ビニルトルエン共重合体、スチレン−ビニルナフタリン共重合体、スチレン−アクリル酸メチル共重合体、スチレン−アクリル酸エチル共重合体、スチレン−アクリル酸ブチル共重合体、スチレン−アクリル酸オクチル共重合体、スチレン−アクリル酸ジメチルアミノエチル共重合体、スチレン−メタアクリル酸メチル共重合体、スチレン−メタアクリル酸エチル共重合体、スチレン−メタアクリル酸ブチル共重合体、スチレン−メタクリル酸ジメチルアミノエチル共重合体、スチレン−ビニルメチルエーテル共重合体、スチレン−ビニルエチルエーテル共重合体、スチレン−ビニルメチルケトン共重合体、スチレン−イソプレン共重合体、スチレン−マレイン酸共重合体、スチレン−マレイン酸エステル共重合体などのスチレン−マレイン酸共重合体；ポリメチルメタクリレート、ポリブチルメタクリレート、ポリ酢酸ビニル、ポリエチレン、ポリプロピレン、ポリビニルブチラート、シリコン樹脂、ポリエステル樹脂、ポリアミド樹脂、エポキシ樹脂、ポリアクリル酸樹脂、ロジン、変性ロジン、テンペル樹脂、フェノール樹脂、脂肪族または脂環族炭化水素樹脂、芳香族系石油樹脂などが単独或いは混合して使用できる。
これらの樹脂の添加量としては、単量体１００質量部に対し１〜２０質量部が好ましい。１質量部未満では添加効果が小さく、一方２０質量部を超えて添加すると重合トナーの種々の物性設計が難しくなる。
【００４５】
本発明においては、ＧＰＣ（ゲルパーミエーションクロマトグラフイー）によるクロマトグラムのピークの分子量は次の条件で測定することができる。
すなわち、４０℃のヒートチャンバー中でカラムを安定化させ、この温度におけるカラムに、溶媒としてＴＨＦ（テトラヒドロフラン）に毎分１ｍｌの流速で流し、試料濃度として、０．０５〜０．１質量％に調整した樹脂のＴＨＦ試料溶液を５０〜２００μｌ注入して測定する。試料の分子量測定にあたっては、試料の有する分子量分布を、数種の単分散ポリスチレン標準試料により作製された検量線の対数値とカウント数との関係から算出する。検量線作成用の標準ポリスチレン試料としては、例えば、Ｐｒｅｓｓｕｒｅ Ｃｈｅｍｉｃａｌ Ｃｏ製または東洋ソーダ工業社製の分子量が、６×１０²、２．１×１０³、４×１０³、１．７５×１０⁴、５．１×１０⁴、１．１×１０⁵、３．９×１０⁵、８．６×１０⁵、２×１０⁶、４．４８×１０⁶のものを用い、少なくとも１０点程度の標準ポリスチレン試料を用いるのが適当である。また、検出器にはＲＩ（屈折率）検出器を用いる。
なお、カラムとしては、市販のポリスチレンゲルカラムを複数組み合わせるのが良く、例えば、Ｗａｔｅｒｓ社製のμ−ｓｔｙｖａｇｅ１５００、１０３、１０４、１０５の組み合わせや、ＫＦ−８０２、８０３、８０４、８０５の組み合わせ、または、東ソー社製のＴＳＫｇｅｌ Ｇ１０００Ｈ、Ｇ２０００Ｈ、Ｇ２５００Ｈ、Ｇ３０００Ｈ、Ｇ４０００Ｈ、Ｇ５０００Ｈ、Ｇ６０００Ｈ、Ｇ７００Ｈ、ＧＨＭの組み合わせが好ましい。
【００４６】
本発明に用いられる着色剤は、以下に示すイエロー着色剤、マゼンタ着色剤およびシアン着色剤が挙げられ、黒色着色剤としてカーボンブラック、磁性体または以下に示すイエロー着色剤／マゼンタ着色剤／シアン着色剤を混合して黒色に調色されたものが利用される。
イエロー着色剤としては、縮合アゾ化合物、イソインドリノン化合物、アンスラキノン化合物、アゾ金属錯体、メチン化合物、アリルアミド化合物に代表される化合物等が用いられる。具体的には、Ｃ．Ｉ．ピグメントイエロー１２、１３、１４、１５、１７、６２、７４、８３、９３、９４、９５、１０９、１１０、１１１、１２８、１２９、１４７、１６８、１８０等が好適に用いられる。
【００４７】
マゼンタ着色剤としては、縮合アゾ化合物、ジケトピロロピロール化合物、アンスラキノン、キナクリドン化合物、塩基染料レーキ化合物、ナフトール化合物、ベンズイミダゾロン化合物、チオインジゴ化合物、ペリレン化合物等が用いられる。具体的には、Ｃ．Ｉ．ピグメントレッド２、３、５、６、７、２３、４８；２、４８；３、４８；４、５７；１、８１；１、１４４、１４６、１６６、１６９、１７７、１８４、１８５、２０２、２０６、２２０、２２１、２５４が特に好ましい。
シアン着色剤としては、銅フタロシアニン化合物及びその誘導体、アンスラキノン化合物、塩基染料レーキ化合物等が利用できる。具体的には、Ｃ．Ｉ．ピグメントブルー１、７、１５、１５：１、１５：２、１５：３、１５：４、６０、６２、６６等が特に好適に利用できる。
【００４８】
これらの着色剤は、単独又は２種類以上を混合し更には固溶体の状態で用いることができる。着色剤は、色相、彩度、明度、耐候性、ＯＨＰ透明性、分散性の点から選択される。この着色剤の添加量は、樹脂成分１００質量部に対して１〜２０質量部使用することが好ましい。
【００４９】
また、本発明のトナーは荷電制御剤を含むものでもよい。本発明に用いられる荷電制御剤としては、公知のものを適宜選択して利用することができるが、特に帯電スピードが速く、かつ、一定の帯電量を安定して維持できる荷電制御剤を使用するのが好ましい。さらに、トナー粒子を直接重合法を用いて製造する場合には、重合阻害性が低く、水系分散媒体への可溶化物が実質的にない荷電制御剤が特に好ましい。具体的な化合物としては、ネガ系荷電制御剤としてサリチル酸、ナフトエ酸、ダイカルボン酸のような芳香族カルボン酸の金属化合物、スルホン酸又はカルボン酸基を側鎖に持つ高分子型化合物、ホウ素化合物、尿素化合物、ケイ素化合物、カリックスアレーン、モノアゾ系の鉄錯体、クロム錯体等が挙げられる。ポジ系荷電制御剤として四級アンモニウム塩、その四級アンモニウム塩を側鎖に有する高分子型化合物、グアニジン化合物、イミダゾール化合物等が挙げられる。
この荷電制御剤は樹脂１００質量部に対して０．１〜１０質量部使用することが好ましい。しかしながら、本発明において荷電制御剤の添加は必須ではなく、二成分現像方法を用いた場合においては、キャリアとの摩擦帯電を利用し、非磁性一成分ブレードコーティング現像方法を用いた場合においては、ブレード部材やスリーブ部材との摩擦帯電を積極的に利用することでトナー粒子中に必ずしも荷電制御剤を含む必要はない。
【００５０】
本発明において、トナーの断層面の観察は、具体的には以下のように行う。まず、常温硬化性のエポキシ樹脂中にトナーまたはトナー粒子を充分分散させた後、４０℃の雰囲気下で２日間硬化させ得られた硬化物を四三酸化ルテニウム、必要により四三酸化オスミウムを併用し染色を施し、その後、ダイヤモンド歯を備えたミクロトームを用い薄片状のサンプルを切り出して透過電子顕微鏡を用いトナーの断層面を観察する。本発明においては、用いるワックス成分と外殻を構成する結着樹脂との若干の結晶化度の違いを利用して材料間のコントラストをつけるため四三酸化ルテニウム染色法を用いることが好ましい。代表的な一例を示す模式図を図１に示す。以下に説明する実施例１および比較例１で得られたトナーＡおよびＫを透過型電子顕微鏡（ＴＥＭ）を用いて断層面観察したところ、トナーＡの場合には、ワックス成分が結着樹脂中に実質的に球状および紡錘形の島状に分散されている様子が観察され、トナーＫの場合には、ワックス成分が結着樹脂中に微分散されている様子が観察された。したがって、透過型電子顕微鏡（ＴＥＭ）を用いて断層面観察した際に、ワックス成分が結着樹脂中に実質的に球状および紡錘形の島状に分散されている様子が観察されるトナーを使用するのが好ましい。
【００５１】
本発明のトナーは、さらに流動性向上剤として非磁性トナー粒子の表面に無機微粉体を有する。無機微粉体としては、例えば、シリカ微粉末、酸化チタン微粉末、アルミナ微粉末、これらの微粉末の表面を疎水化処理したもの等を単体で、または２種以上を併用して用いることができる。これらの中では、シリカを使用することが好ましい。例えば、ここで使用するシリカは、ケイ素ハロゲン化物やアルコキシドの蒸気相酸化により生成されたいわゆる乾式法により製造さる乾式シリカ、及びアルコキシド水ガラス等から製造されるいわゆる湿式シリカの両者が使用可能であるが、シリカ表面及びシリカ微粉末の内部にあるシラノール基が少なく、またＮａ₂Ｏ、ＳＯ₃ ^2-等の製造残滓の少ない点で、乾式シリカを使用するのが更に好ましい。また、製造工程において例えば、塩化アルミニウム、塩化チタン等他の金属ハロゲン化合物をケイ素ハロゲン化合物をシリカと共に用いることによって、シリカと他の金属酸化物の複合微粉体を得ることも可能である。そして、上記乾式シリカには、このような複合微粉体も含まれる。トナーに用いられる無機微粉体は、ＢＥＴ法で測定した窒素吸着による比表面積が３０ｍ²／ｇ以上のもの、特に５０〜４００ｍ²／ｇの範囲のものが良好な結果を与えることができるため好ましい。シリカ微粉体の配合量は、トナー粒子１００質量部に対して、０．１〜８質量部であるのが好ましく、０．５〜５質量部であるのがさらに好ましく、０．５〜３．０質量部の範囲であるのが特に好ましい。また、本発明で用いられる無機微粉体は、必要に応じ、疎水化や帯電性制御等の目的でシリコーンワニス、各種変性シリコーンワニス、シリコーンオイル、各種変性シリコーンオイル、シランカップリング剤、官能基を有するシランカップリング剤、その他の有機硅素化合物、有機チタン化合物等の処理剤により、または、種々の処理剤と併用して処理されていることが好ましい。したがって、無機微粉体の中では、シリコーンオイルで処理されているもの、特に疎水性シリカが、トナー粒子の摩擦帯電性及び転写性の改良効果が高いため好ましい。
トナー粒子の粒度分布制御や粒径の制御は、難水溶性の無機塩や保護コロイド作用をする分散剤の種類や添加量を変える方法や機械的装置条件（例えばローターの周速、パス回数、攪拌羽根形状等の攪拌条件や容器形状）または、水溶液中での固形分濃度等を制御することにより所定のトナー粒子を得ることができる。
【００５２】
本発明のトナーの製造法としては、懸濁重合法、分散重合法、乳化会合重合法等の各種の重合方法を使用することできるが、懸濁重合法を使用するのが好ましい。この際、分散安定剤を使用することもできる。
トナーの製造法として分散安定剤を用いた懸濁重合法を利用する場合、用いる分散安定剤としては、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、アルミナ等が挙げられ、特にリン酸三カルシウムを用いると粒度のシャープなトナーが得られるので好ましい。これらの分散安定剤は、重合性単量体１００質量部に対して０．２〜２０質量部を使用することが好ましい。
【００５３】
分散安定剤は市販のものをそのまま用いても良いが、細かい粒子を得るために、分散媒体中にて微粒子を生成させて用いても良い。例えば、リン酸三カルシウムの場合、高速攪拌下において、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と良い。
微細な分散のために、０．００１〜０．１質量部の界面活性剤を併用してもよい。これは上記分散安定剤の作用を促進するためのものであり、例えば、ドデシルベンゼン硫酸ナトリウム、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挙げられる。
【００５４】
本発明で使用するトナーの製造方法として重合法を用いる場合においては、以下のような製造方法が可能である。
重合性単量体中に、ワックス成分、着色剤、重合開始剤、必要により荷電制御剤、その他の添加剤を加え、ホモジナイザー、超音波分散機等によって均一に溶解または分散した単量体組成物を、分散安定剤を含有する水相中に通常の攪拌機またはホモミキサー、ホモジナイザー等により分散させる。好ましくは単量体組成物の液滴が所望のトナー粒子のサイズを有するように攪拌速度、攪拌時間を調整して造粒する。その後は分散安定剤の作用により、粒子状態が維持され、かつ、粒子の沈降が防止される程度の攪拌を行えばよい。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うのがよい。重合反応の後半に昇温をしてもよく、さらに、本発明における画像形成方法では耐久性の向上の目的で、未反応の重合性単量体、副生成物等を除去するためのに、反応後半または反応終了後に一部水系媒体を反応系から留去してもよい。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、乾燥する。懸濁重合法においては、通常単量体組成物１００質量部に対して水３００〜３０００質量部を分散媒体として使用するのが好ましい。
【００５５】
また、分散安定剤を用いた場合には、トナー製造後にこの分散剤を除去することが望ましく、分散剤がトナー表面に残存していると帯電性、特に環境安定性に大きな問題が生じる場合が多いので、できるかぎり除去を行うことが好ましい。例えばリン酸三カルシウムを分散剤として用いた場合には、該分散剤が酸性で水に溶解する性質を利用して、重合が修了した懸濁液に酸を添加することによりリン酸三カルシウムをほぼ完全に除去することが可能である。リン酸三カルシウムを溶解する際には、トナー粒子の懸濁している水系媒体のｐＨを４未満、より好ましくは２未満とすることで短時間にリン酸三カルシウムの除去が可能である。
【００５６】
また、本発明の非磁性重合法トナー粒子の製造方法は、単量体と、着色剤と、ワックス成分とを含む単量体組成物を水系媒体中に懸濁し、少なくとも重合開始剤として有機過酸化物を用いて重合し、懸濁重合後にトナー粒子とアルカリ性の水系媒体を実質的に分離することを特徴とする。すなわち、単量体組成物を水系媒体中に懸濁させる工程、重合開始剤として有機過酸化物を用いて重合させる工程、そしてトナー粒子とアルカリ性の水系媒体を分離する工程を含むことを特徴とするものである。
【００５７】
【実施例】
以下、本発明について、実施例及び比較例を挙げてより具体的に説明する。
以下、具体的実施例によって本発明を説明するが、本発明は何らこれに限定されるものではない。
【００５８】
＜実施例１＞
高速攪拌装置ＴＫ式ホモミキサー（特殊機化工業製）を備えた２ｌ用４つ口セパラブルフラスコ中にイオン交換水３２５質量部と０．１ｍｏｌ／ｌ−Ｎａ₃ＰＯ₄水溶液２５０質量部を投入し、回転数を１２０００ｒｐｍに調整し、８０℃に加温した。ここに１．０ｍｏｌ／ｌ−ＣａＣｌ₂水溶液３５質量部を徐々に添加し、微少な難水溶性分散安定剤Ｃａ₃（ＰＯ₄）₂を含む水系連続相を調製した。
【００５９】
一方、分散質として、
・スチレン ８３質量部
・ｎ−ブチルアクリレート １７質量部
・ジビニルベンゼン（純度５５％） ０．１質量部
・カーボンブラック（ＢＥＴ比表面積＝９６ｍ²／ｇ） ５質量部
・最大吸熱ピーク７５℃のエステルワックス ５質量部
・負荷電性制御剤（モノアゾ染料系のＦｅ化合物） ２質量部
・ｔ−ブチルパーオキシ−２−エチルヘキサノエート ６質量部
を均一に混合した。
【００６０】
次いで、前記水系媒体中に上記単量体組成物を投入し、８０℃、Ｎ₂ 雰囲気下においてＴＫ式ホモミキサー（特殊機化工業（株））にて１０，０００ｒｐｍで１０分間撹拌し、造粒した。その後パドル撹拌翼で撹拌しつつ、８０℃で４時間反応させ、無水炭酸ナトリウム４質量部を系内に添加した後、さらに２時間反応を継続した（反応終了後の懸濁液のｐＨは１０．５であった）。反応終了後、懸濁液を冷却し、連続式ベルトフィルター（住友重機械工業社製、商品名「イーグルフィルター」）」）を用いて以下のような操作を行った。
【００６１】
まず、アルカリ性の懸濁液の脱水をベルト上で行い、次いで合計量１０００質量部の水をシャワーリングして水洗を行い、懸濁液中に含まれる２−エチルヘキサン酸ナトリウム（これは重合開始剤であるｔ−ブチルパーオキシ−２−エチルヘキサノエートの分解により副生した２−エチルヘキサン酸が、炭酸ナトリウムにより中和されたものである）の除去を行った。さらに、ベルト上で１０００質量部の希塩酸（ｐＨ１．０）での洗浄、１０００質量部の水での水洗、そして脱水を行なうことで、２−エチルヘキサン酸および分散剤として使用したリン酸カルシウムが実質的に除去されたトナー粒子を得た。
【００６２】
その後、この含水トナー粒子を４０℃、４８時間熱風乾燥して質量平均粒径６．８μｍのトナー粒子を得た。この乾燥トナー粒子を熱天秤で１２０℃にて恒量となるまで加熱して揮発分を測定したところ、０．２％であった。
次にトナー粒子１００質量部と、ヘキサメチルジシラザンで表面を処理した後シリコーンオイルで処理し、処理後のＢＥＴ値が２００ｍ²／ｇの疎水性シリカ微粉体２．０質量部とをヘンシェルミキサー（三井三池化工機（株））で混合して、トナーＡを調製した。
【００６３】
＜実施例２＞
希塩酸洗浄前の水洗浄に用いた水の量を、１０００質量部から１００質量部に減らした以外は実施例１と同様にしてトナーＢを得た。
＜実施例３＞
無水炭酸ナトリウムの量を４質量部から０．４質量部に減らした以外は実施例１と同様にしてトナーＣを得た。尚、反応終了後のｐＨは９．２であった。
＜実施例４＞
希塩酸洗浄の前に水洗浄を行わない以外は実施例１と同様にしてトナーＤを得た。
＜実施例５＞
エステルワックスの使用量を５１質量部とする以外は製造例１と同様にして、トナーＥを得た。
＜実施例６＞
エステルワックスの使用量を０．４質量部とする以外は製造例１と同様にして、トナーＦを得た。
＜実施例７＞
ｔ−ブチルパーオキシ−２−エチルヘキサノエートに代えてｔ−ブチルパーオキシネオデカノエート８質量部を用いる他は実施例１と同様にして、トナーＧを得た。
【００６４】
＜参考例８＞
高速攪拌装置ＴＫ式ホモミキサー（特殊機化工業製）を備えた２ｌ用４つ口セパラブルフラスコ中にイオン交換水３２５質量部と０．１ｍｏｌ／ｌ−Ｎａ_３ＰＯ_４水溶液２５０質量部を投入し、回転数を１２０００ｒｐｍに調整し、８０℃に加温した。ここに１．０ｍｏｌ／ｌ−ＣａＣｌ₂水溶液３５質量部を徐々に添加し、微少な難水溶性分散安定剤Ｃａ_３（ＰＯ_４）_２を含む水系連続相を調製した。
【００６５】
一方、分散質として、
・スチレン ８３質量部
・ｎ−ブチルアクリレート １７質量部
・ジビニルベンゼン（純度５５％） ０．１質量部
・カーボンブラック（ＢＥＴ比表面積＝９６ｍ²／ｇ） ５質量部
・最大吸熱ピーク１２０℃の低分子量ポリプロピレン ２質量部
・Ｃｒ系染料（保土ケ谷化学社、商品名ＴＲＨ） １質量部
・サクシニックアシッドパーオキサイド ６質量部
を均一に混合した。
【００６６】
次いで、前記水系媒体中に上記単量体組成物を投入し、８０℃、Ｎ₂雰囲気下においてＴＫ式ホモミキサー（特殊機化工業（株））にて１０，０００ｒｐｍで１０分間撹拌し、造粒した。その後パドル撹拌翼で撹拌しつつ、８０℃で４時間反応させ、無水炭酸ナトリウム４質量部を系内に添加した後、さらに２時間反応を継続した（反応終了後の懸濁液のｐＨは１０．５であった）。反応終了後、懸濁液を冷却し、フィルタープレス（栗田機械製作所製）を用いて以下のような操作を行った。
【００６７】
まず、アルカリ性の懸濁液をフィルタープレス内に導入してトナー粒子の濾過を行う。次いでトータル量１０００質量部の水を濾枠内に流し、懸濁液中のコハク酸ナトリウム（これは重合開始剤であるサクシニックアシッドパーオキサイドの分解により副生したコハク酸が、炭酸ナトリウムにより中和されたものである）を洗浄除去する。さらに、ｐＨ１．０の希塩酸を濾枠内に流し、トナー粒子表面に付着しているリン酸カルシウムを溶解除去する。その後、濾枠内に水を流し、充分に洗浄を行う。そして圧搾、エアーブローを行なうことで、コハク酸および分散剤として使用したリン酸カルシウムが実質的に除去されたトナー粒子を得た。その後、実施例１と同様にしてトナーＨを得た。
＜参考例９＞
サクシニックアシッドパーオキサイドの代わりにベンゾイルパーオキサイド８質量部を用いる以外は参考例８と同様にしてトナーＩを得た。
＜参考例１０＞
サクシニックアシッドパーオキサイドの代わりに１−シクロヘキシル−１−メチルエチルパーオキシ−２−エチルヘキサノエート６質量部を用いる以外は参考例８と同様にしてトナーＪを得た。
【００６８】
＜比較例１＞
反応容器にキシレン２００質量部を入れ還流温度まで昇温した。これにスチレン８３質量部、アクリル酸−ｎ−ブチル１７質量部、及び、ジ―ｔｅｒｔ―ブチルパーオキサイド２．０質量部の混合液を滴下後、キシレン還流下、７時間で溶液重合を完了し、低分子量樹脂溶液を得た。
一方、スチレン６７質量部、アクリル酸ブチル２５質量部、マレイン酸モノブチル８質量部、ポリビニルアルコール０．２質量部、脱気水２００質量部、過酸化ベンゾイル０．３質量部を混合懸濁分散させた。上記懸濁分散溶液を加熱し、窒素雰囲気下において８５℃に２４時間保持して重合を完結させ、高分子量樹脂を得た。
【００６９】
この高分子量樹脂２５質量部を前記の低分子量樹脂７５質量部を含有する溶液重合終了時の溶液中に投入し、溶媒中に完全に溶解せしめ混合を行い、その後、溶媒を留去して結着樹脂（１）を得た。
次に、下記の各材料をブレンダーにて混合し、これを１５０℃に加熱した二軸エクストルーダーで溶融混練し、冷却した混練物をハンマーミルで粗粉砕した後、粗粉砕物をジェットミルで微粉砕した。
【００７０】
・結着樹脂（１） １００質量部
・カーボンブラック（ＢＥＴ比表面積＝９６ｍ²／ｇ） ５質量部
・最大吸熱ピーク１１５℃の低分子量ポリエチレン ２質量部
その後分級し、分級粉１００質量部と疎水性シリカ微粉体（ＢＥＴ：１６０ｍ²／ｇ）２質量部をヘンシェルミキサーで乾式混合して、比較用トナーＫとした。
【００７１】
＜比較例２＞
高速攪拌装置ＴＫ式ホモミキサー（特殊機化工業製）を備えた２ｌ用４つ口セパラブルフラスコ中にイオン交換水３２５質量部と０．１ｍｏｌ／ｌ−Ｎａ₃ＰＯ₄水溶液２５０質量部を投入し、回転数を１２０００ｒｐｍに調整し、８０℃に加温した。ここに１．０ｍｏｌ／ｌ−ＣａＣｌ₂水溶液３５質量部を徐々に添加し、微少な難水溶性分散安定剤Ｃａ₃（ＰＯ₄）₂を含む水系連続相を調製した。
一方、分散質として、

前記水系媒体中に上記単量体組成物を投入し、８０℃、Ｎ₂雰囲気下においてＴＫ式ホモミキサー（特殊機化工業（株））にて１０，０００ｒｐｍで１０分間撹拌し、造粒した。その後パドル撹拌翼で撹拌しつつ、８０℃で６時間反応させた（反応終了後の懸濁液のｐＨは９．１であった）。反応終了後、懸濁液を冷却し、希塩酸を加えてｐＨ１．０として１時間撹拌した。その後、懸濁液を連続ベルトフィルターにより濾過、水洗し、乾燥して質量平均粒径６．６μｍのトナー粒子を得た。
このトナー粒子１００質量部と、製造例１で使用した疎水性シリカ微粉体１．１質量部とをヘンシェルミキサー（三井三池化工機（株））で混合して、トナーＬを調製した。
【００７２】
＜比較例３＞
ｔ−ブチルパーオキシ−２−エチルヘキサノエートのかわりにスクシニックアシッドパーオキサイド６質量部を用いる以外は比較例２と同様にしてトナーＭを得た。
上記のトナーＡ〜Ｊ、および比較用トナーＫ〜Ｍについての分析値を下記の表１に示す。
【００７３】
【表１】

【００７４】
ここで用いる感光体としては、直径３０ｍｍ、２５４ｍｍのＡｌシリンダーを基体としたもので、これに、以下にに示すような構成の層を順次浸漬塗布により積層して、感光体を作成した。
（１）導電性被覆層：酸化錫及び酸化チタンの粉末をフェノール樹脂に分散したものを主体とする。膜厚１５μｍ。
（２）下引き層：変性ナイロン、及び共重合ナイロンを主体とする。膜厚０．６μｍ。
（３）電荷発生層：長波長域に吸収を持つチタニルフタロシアニン顔料をブチラール樹脂に分散したものを主体とする。膜厚０．６μｍ。
（４）電荷輸送層：ホール搬送性トリフェニルアミン 化合物をポリカーボネート樹脂（オストワルド粘度法による分子量２万）に８：１０の質量比で溶解したものを主体とする。膜厚４０μｍ。
【００７５】
トナー担持体にトナーを塗布する手段として、現像器内に発泡ウレタンゴムからなる塗布ローラを設け、このトナー担持体に当接させた。塗布ローラには、約−５５０Ｖの電圧を印加する。さらに、このトナー担持体上トナーのコート層制御のために樹脂をコートしたステンレス製ブレードを、トナー担持体との接触圧が線圧約２０ｇ／ｃｍとなるように取付けた。また、現像時の印加電圧をＤＣ成分（−４５０Ｖ）のみとした。
これらのプロセスカートリッジの改造に適合するよう電子写真装置に以下のように改造及びプロセス条件設定を行った。
改造された装置はローラー帯電器（直流のみを印加）を用い像担持体を一様に帯電する。帯電に次いで、レーザー光で画像部分を露光することにより静電潜像を形成し、トナーにより可視画像とした後に、電圧を＋７００Ｖ印加したローラーによりトナー像を転写材に転写するプロセスを持つ。また、感光体帯電電位は、暗部電位を−５８０Ｖとし、明部電位を−１５０Ｖとした。
【００７６】
次に現像器内にトナーＡ〜Ｊ、および比較用トナーＫ〜Ｍの各々を充填し、現像器を画像形成装置にセットした。常温常湿（２５℃、６０％ＲＨ）環境下、１４枚／分（Ａ４サイズ）のプリントアウト速度で、「電驚」文字パターンを連続１００枚、ベタ黒画像、ベタ白画像を各２枚、その後再び「電驚」文字パターンを連続１００枚プリントアウトした。その後、画像形成装置ごと低温低湿（１５℃、１５％ＲＨ）環境下でベタ白画像を５枚、ベタ黒画像を１枚プリントアウトした。さらに、画像形成装置ごと高温高湿（３３℃、９０％ＲＨ）環境下にセットし、ベタ黒画像１００枚、ベタ白画像を１枚をプリントアウトした。そして、得られたプリントアウト画像等について、後述の項目について評価した。
以上の評価結果を以下の表２に示す。
【００７７】
【表２】

本発明の実施例、並びに比較例中に記載の評価項目の説明とその評価基準について述べる。
１）画像濃度
常温常湿環境下におけるベタ黒画像について、マクベス反射濃度計ＲＤ９１８（マクベス社製）により、原稿濃度が０．００の白地部分のプリントアウト画像に対する相対濃度を測定した。
【００７８】
Ａ：非常に良好（１．４０以上）
Ｂ：良好（１．３５以上、１．４０未満）
Ｃ：普通（１．００以上、１．３５未満）
Ｄ：悪い（１．００未満）
２）帯電安定性
低温低湿下および高温高湿下でのベタ黒画像の画像濃度差をトナーの帯電安定性の指標とした。
【００７９】
Ａ：非常に良好（０．０５未満）
Ｂ：良好（０．０５以上、０．１０未満）
Ｃ：普通（０．１０以上、０．２０未満）
Ｄ：悪い（０．２０以上）
３）転写性
常温常湿下でのベタ黒画像形成時の感光体上の転写残トナーを、マイラーテープによりテーピングしてはぎ取り、はぎ取ったマイラーテープを紙上に貼ったもののマクベス濃度から、マイラーテープのみを紙上に貼ったもののマクベス濃度を差し引いた数値で評価した。
【００８０】
Ａ：非常に良好（０．０５未満）
Ｂ：良好（０．０５以上、０．１未満）
Ｃ：普通（０．１以上、０．２未満）
Ｄ：悪い（０．２以上）
４）カブリ
高温高湿下でのベタ白画像について、「リフレクトメーター」（東京電色社製）により測定した白色度と転写紙の白色度の差から、カブリ濃度（％）を算出し、画像カブリを評価した。
【００８１】
Ａ：非常に良好（１．５％未満）
Ｂ：良好（１．５％以上、３．０％未満）
Ｃ：普通（３．０％以上、５．０％未満）
Ｄ：悪い（５．０％以上）
５）定着性
低温低湿下でのベタ黒画像について、５０ｇ／ｃｍ²の荷重をかけ、柔和な薄紙により定着画像を摺擦し、摺擦前後での画像濃度の低下率（％）で評価した。
【００８２】
Ａ：非常に良好（５％未満）
Ｂ：良好（５％以上、１０％未満）
Ｃ：普通（１０％以上、２０％未満）
Ｄ：悪い（２０％以上）
また、画像形成装置とのマッチング評価は以下の評価基準により行った。
１）感光体とのマッチング
プリントアウト試験終了後、感光体ドラム表面の傷や残留トナーの固着の発生状況とプリントアウト画像への影響を目視で評価した。
【００８３】
Ａ： 未発生
Ｂ： わずかに傷の発生が見られる
Ｃ： 固着や傷がある
Ｄ： 固着が多い
２）定着器とのマッチング
プリントアウト試験終了後、定着フィルム表面の傷や残留トナーの固着状況を目視で評価した。
【００８４】
Ａ： 未発生
Ｂ： わずかに固着が見られる
Ｃ： 固着や傷がある
Ｄ： 固着が多い
【図面の簡単な説明】
【図１】 （ａ）トナーＡのＴＥＭによる断層面観察写真の模式図。
（ｂ）トナーＫのＴＥＭによる断層面観察写真の模式図。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a toner for developing an electrostatic charge image in an image forming method such as electrophotography, electrostatic printing, and magnetic recording, and a toner particle manufacturing method. In particular, the present invention relates to a dry toner used in a fixing method in which a visible image formed with toner is fixed on a recording material by heating.
[0002]
[Prior art]
Conventionally, as an electrophotographic method, many methods are known as described in U.S. Pat. No. 2,297,691, Japanese Patent Publication No. 42-23910, Japanese Patent Publication No. 43-24748, etc. Uses a photodielectric material, forms an electrical image on the photoreceptor by various means, and then develops the electrostatic charge image with toner, using direct or indirect means as necessary. After transferring the toner image to a transfer material such as paper, it is fixed by heating, pressing, or solvent vapor to obtain a copy, etc., and the untransferred toner remaining without being transferred onto the photoconductor It is cleaned in various ways and the above steps are repeated.
[0003]
An example of a general method for forming a full-color image will be described. The photoconductor (electrostatic charge image carrier) of the photoconductor drum is uniformly charged by a primary charger and modulated by a magenta image signal of an original. Image exposure is performed by laser light to form an electrostatic charge image on the photosensitive drum, and the electrostatic charge image is developed by a magenta developer having magenta toner to form a magenta toner image. Next, the magenta toner image developed on the photosensitive drum by the transfer charger is transferred directly or indirectly to the conveyed transfer material.
[0004]
On the other hand, the photosensitive drum after the development of the electrostatic charge image is neutralized by a neutralizing charger, cleaned by a cleaning unit, charged again by a primary charger, and similarly the cyan toner image The cyan toner image is formed on the transfer material onto which the magenta toner image has been transferred, and the toner images of four colors are transferred to the transfer material in the same manner as yellow and black. The transfer material having the four color toner images is fixed by the action of heat and pressure by a fixing roller, thereby forming a full color image.
[0005]
In recent years, such devices have been used not only in office copy machines for copying original documents, but also in the fields of laser beam printers (LBP) as computer output or personal copy (PC) for individuals. I'm starting to break.
In addition to the fields represented by LBP and PC, the development of a plain paper fax machine using a basic configuration is also rapidly developing.
[0006]
Therefore, there is a demand for smaller, lighter, faster, higher image quality, and higher reliability than conventional ones, and image forming apparatuses are configured with simpler elements in various respects. ing. As a result, the performance required for the toner becomes higher, and if the improvement in the performance of the toner cannot be achieved, the toner cannot be realized as an excellent image forming apparatus. In recent years, the demand for color copying has been increasing rapidly due to various copying needs. In order to copy original color images more faithfully, higher image quality and higher resolution are desired. Furthermore, there is an increasing demand for copying original color originals on both sides.
[0007]
From these viewpoints, the toner used in such a color image forming method must have good meltability and color mixing properties when heated, and has a low softening point and a low melt viscosity. It is preferable to use a toner having a high melt property. That is, by using such a sharp melt toner, the color reproduction range of a copy can be expanded and a color copy faithful to the original image can be obtained.
However, such a color toner having a high sharp melt property generally has a high affinity with the fixing roller, and tends to be offset to the fixing roller during fixing. In particular, in the case of a fixing device in a color image forming apparatus, since a plurality of toner layers of magenta, cyan, yellow, and black are formed on a transfer material, an offset tends to easily occur due to an increase in toner layer thickness.
[0008]
Conventionally, for the purpose of preventing toner from adhering to the surface of the fixing roller, for example, the roller surface is coated with a material excellent in releasability from toner such as silicone rubber and fluorine resin, and further, the surface is prevented from being offset, and the roller. In order to prevent surface fatigue, the roller surface is coated with a thin film of a liquid having high releasability such as silicone oil and fluorine oil. However, this method is extremely effective in preventing toner offset, but has a problem that the fixing device is complicated because an apparatus is required to supply the liquid for preventing offset. Further, this method has a problem that the oil application causes peeling between the layers constituting the fixing roller, and as a result, the adverse effect of promoting the shortening of the life of the fixing roller is caused.
[0009]
Therefore, instead of using a silicone oil supply device, instead of supplying an offset prevention liquid from the toner during heating, a method of adding a release agent such as low molecular weight polyethylene or low molecular weight polypropylene to the toner is available. Proposed.
It is known to contain a wax as a release agent in a toner. For example, techniques are disclosed in Japanese Patent Publication No. 52-3304, Japanese Patent Publication No. 52-3305, Japanese Patent Laid-Open No. 57-52574, and the like.
Also, JP-A-3-50559, JP-A-2-79860, JP-A-1-109359, JP-A-62-1166, JP-A-61-227354, JP-A-61-94062. JP-A-61-138259, JP-A-60-252361, JP-A-60-252360, JP-A-60-217366, etc. disclose techniques for containing waxes. Yes.
[0010]
Waxes are used to improve the offset resistance of toner at low and high temperatures, and to improve fixability at low temperatures. When exposed to heat due to temperature rise or the like, or when the toner is left for a long time, the wax migrates to the toner surface and developability deteriorates.
[0011]
In view of these problems, the expectation for development of a new toner has been great.
A suspension polymerization toner has been proposed for the above problem (Japanese Patent Publication No. 36-10231). In this suspension polymerization method, a monomer composition is prepared by uniformly dissolving or dispersing a polymerizable monomer and a colorant (and, if necessary, a polymerization initiator, a crosslinking agent, a charge control agent, and other additives). Then, the monomer composition is dispersed in a continuous phase (for example, an aqueous phase) containing a dispersion stabilizer by using an appropriate stirrer, and a polymerization reaction is simultaneously performed to obtain toner particles having a desired particle size. To get.
[0012]
In this suspension polymerization method, droplets of the monomer composition are generated in a dispersion medium having a high polarity such as water, so that the component having a polar group contained in the monomer composition is an interface with the aqueous phase. Therefore, it is possible to form a so-called core / shell structure in which a non-polar component is easily present in the surface layer portion and hardly exists in the surface layer portion.
By embedding the wax component, which is a mold release agent, the toner by this polymerization method can achieve the conflicting performances of low-temperature fixability, blocking resistance and high-temperature offset resistance, and the fixing roller can be made of oil or the like. High temperature offset can be prevented without applying a release agent.
[0013]
On the other hand, JP-A-10-20548 discloses a method for producing a polymerized toner using a non-aromatic organic peroxide having a molecular weight of 250 or less as a polymerization initiator. According to this publication, it is possible to obtain a toner having a relatively low odor during printing, in which the decomposition amount of the polymerization initiator and the amount of residual monomer are suppressed. However, in this publication, the decomposition product of the polymerization initiator is removed by drying, and among the initiator decomposition products by-produced when the polymerization initiator described in the examples of this publication is used. For example, decomposition products such as succinic acid and 2-ethylhexanoic acid have a very high boiling point. Therefore, when removing them by drying, heat treatment must be performed so that the toner deteriorates. Impossible. Therefore, a relatively low-boiling initiator decomposition product such as t-butanol can be removed to some extent according to this publication, but a high-boiling decomposition product cannot be removed. In addition, when treated in accordance with this publication, not only the odor when the toner melts (fixing time) but also the charging stability of the toner due to environmental changes is reduced due to residual decomposition products, and in some cases there is a problem with the fixability. Produce.
[0014]
Further, Japanese Patent Publication No. 4-73442 discloses that a resin for toner is subjected to suspension polymerization using partially saponified polyvinyl alcohol as a dispersant, and then an alkali metal hydroxide is added to the polymerization system, followed by heating, and subsequently. A method of removing acidic impurities derived from raw materials or by-produced during polymerization by performing filtration is disclosed. However, the toner described in this publication is a toner obtained by a pulverization method and has a drawback that its transferability is insufficient due to its shape. In addition, it is completely unclear what effect is exhibited when this alkali treatment is applied to a polymerized toner.
[0015]
As mentioned above, in recent years, there has been a great demand for users to copy originals on both sides or to copy originals on both sides, and for that reason, higher-quality, more reliable double-sided images are required. ing.
There are various problems in the conventional technology for copying color originals on both sides. Among these, one of the most important issues is paper curl that occurs after fixing one side of the transfer paper with toner. When the paper curl is large, the transportability of the fixed image is remarkably inferior, and an image with high image quality and high reliability cannot be obtained. The performance required for the toner is, for example, how a high-quality image satisfying image density, color reproducibility, etc. can be obtained in a state where the amount of toner transferred to the transfer material is small. For this purpose, it is necessary to improve the coloring power of the toner itself. In addition, when copying a double-sided document, an image that passes through the fixing device twice is generated, so that further improvement in high-temperature offset resistance is required.
[0016]
Conventionally, in a full-color copying machine, four photoreceptors and a belt-like transfer belt are used, and an electrostatic charge image formed on each photoreceptor is developed using cyan, magenta, yellow, and black toners, and then the photoreceptor and the belt. After transferring the transfer material between transfer bodies and transferring between straight paths, a full color image is formed, or the transfer material is wound around the surface of the transfer body facing the photoconductor by mechanical action such as electrostatic force or gripper, and developed. -A method of obtaining a full-color image as a result of performing the transfer process four times is generally used.
[0017]
In recent years, as full-color copying materials, there has been an increasing need for copying on various materials such as ordinary paper and overhead projector film (OHP), such as small paper such as cardboard, cards, and postcards. ing. In the method using the four photoconductors described above, since the transfer material is conveyed straight, the application range to various transfer materials is wide. However, it is necessary to accurately superimpose a plurality of toner images on the position of a predetermined transfer material. is there. For this reason, it is difficult to obtain a high-quality image with good reproducibility even with a slight difference in registration, and there is a problem that the transfer material transport mechanism becomes complicated, leading to an increase in reliability and the number of parts. In addition, if thick paper with a large amount of weight is used for the method of adsorbing and winding the transfer material on the surface of the transfer material, the rear end of the transfer material causes poor adhesion due to the stiffness of the transfer material, resulting in image defects based on transfer. Wake up is not preferable. Similarly, image defects may occur on small-size paper.
[0018]
Further, as a toner mounted on a normal full-color copying machine, it is necessary that the color toners are sufficiently mixed in the fixing process, and improvement in color reproducibility and transparency of the OHP image are important due to this color mixing. Considering this point, it is generally preferable to use a sharp melt and low molecular weight resin for the color toner as compared with the black toner. For normal black toner, a release agent having relatively high crystallinity represented by polyethylene wax or polypropylene wax is used in order to improve high temperature offset resistance during fixing. However, in the full color toner, the transparency of the toner image on the OHP paper is remarkably hindered due to the crystallinity of the release agent. For this reason, the high temperature offset resistance is improved as a result of uniformly applying silicone oil or the like to the heat-fixing roller without adding a release agent as a constituent of the toner normally used for color copying. However, the transfer material having the toner-fixed image obtained in this manner is not preferable because it causes an uncomfortable feeling when used by the user because extra silicone oil or the like adheres to the surface of the transfer material. As described above, full-color image formation using an intermediate transfer member having many contact portions has many problems that are difficult at present. Japanese Patent Application Laid-Open Nos. 59-15739 and 59-5046 do not propose any device for the toner or the intermediate transfer member in this regard.
[0019]
[Problems to be solved by the invention]
An object of the present invention is to provide a toner that does not generate an unpleasant odor at the time of fixing, has a stable chargeability regardless of environmental fluctuations, has excellent transferability, and a method for producing non-magnetic toner particles. .
[0020]
[Means for Solving the Problems]
As a result of intensive investigations to solve the above problems, the inventors of the present invention specified toner particles by using a specific polymerization initiator, keeping the residual monomer amount and the content of carboxylic acid as a decomposition product of the initiator within a certain range. In order to complete the present invention, it has been found that a toner having excellent circularity can be obtained without causing an unpleasant odor at the time of fixing, having a stable chargeability regardless of environmental fluctuations, and having excellent transferability. It came.
[0021]
  That is, the present invention is a dry nonmagnetic toner having inorganic fine powder on the surface of a nonmagnetic toner particle containing a styrene-based binder resin, a colorant, and a wax component,
Monomers including styrene monomersAnd a colorant,Wax formationMinutesThe monomer composition containing is dispersed in an aqueous medium containing a dispersion stabilizer soluble in acid, granulated,With polymerization initiatorSuspension polymerizationAnd obtainedIt was obtained by dissolving and removing the dispersion stabilizer on the particle surface with acid.Toner particlesAndThe polymerization initiator is an organic peroxide;The content of the carboxylic acid, which is a decomposition product of the organic peroxide contained in the toner, is less than 2000 ppm, and the residual styrene monomer in the toner is less than 300 ppm.Dry non-magneticIt relates to toner. The present invention also provides such aDry non-magnetic tonerIt is related with the manufacturing method.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be described in detail below.
First, the circularity of the toner will be described.
A toner composed of toner having a circularity of 0.970 or more (powder composed of toner particle groups) is very excellent in transferability. This is presumably because the contact area between the toner particles and the photoconductor is small, and the adhesion force of the toner particles to the photoconductor due to mirror image force, van der Waals force, or the like is reduced. Therefore, if such a toner is used, the transfer rate is high and the residual toner is greatly reduced. Therefore, the toner in the pressure contact portion between the charging member and the photosensitive member is very little, toner fusion is prevented, and image defects are prevented. It is considered to be significantly suppressed.
Further, since toner particles having a circularity of 0.970 or more have almost no edge portion on the surface, friction is reduced at the pressure contact portion between the charging member and the photosensitive member, and the surface of the photosensitive member can be prevented from being scraped. .
These effects are more prominent in an image forming method including a contact transfer process in which transfer loss is likely to occur.
[0023]
The average circularity and mode circularity of the developer of the present invention will be described below.
The average circularity in the present invention is used as a simple method for quantitatively expressing the shape of the particles. In the present invention, the average circularity is measured using a flow type particle image analyzer “FPIA-1000” manufactured by Toa Medical Electronics. The circularity of the measured particles was calculated by the following formula (1), and the value obtained by dividing the total roundness of all particles measured by the following formula (2) by the total number of particles was averaged. Defined as circularity.
[0024]
[Expression 1]

[0025]
[Expression 2]

The mode circularity means that the circularity is 0.40 to 1.00, 0.400 or more and less than 0.410, 0.410 or more and less than 0.420,. . . , 0.990 or more and less than 1.000 and 1.000, 61 divisions are made every 0.01, and the measured circularity of each particle is assigned to each divided range according to the circularity, This is the lower limit value of the division range where the frequency value is maximum.
[0026]
In addition, “FPIA-1000”, which is a measuring apparatus used in the present invention, calculates the circularity of each particle, and then calculates the average circularity. A calculation method is used in which 1.00 is divided into 61 classes, and the average circularity is calculated using the center value and frequency of the dividing points. However, the error from each value of the average circularity calculated by this calculation formula is very small and is substantially negligible. In the present invention, the calculation time can be shortened and the calculation formula For reasons of handling data such as simplification, such a calculation formula partially modified by using the concept of the calculation formula that directly uses the circularity of each particle described above may be used.
[0027]
Measuring means are as follows. A dispersion is prepared by dispersing 5 mg of a developer in 10 ml of water in which about 0.1 mg of a surfactant is dissolved, and the dispersion is irradiated with ultrasonic waves (20 kHz, 50 W) for 5 minutes. Measurement is performed with the above apparatus at 20,000 / μl, and the average circularity and mode circularity of the developer are obtained.
The average circularity in the present invention is an index of the degree of unevenness of the developer, and is 1.000 when the developer is a perfect sphere, and the circularity becomes smaller as the surface shape becomes more complicated.
[0028]
In addition, even when the average circularity is high, the effect may be insufficient if the circularity of the existing particles is low. Therefore, when the mode circularity is 0.990 or more, the circularity is 0.990 or more. Since the particles mainly exist, the above effect is remarkably exhibited, which is preferable.
[0029]
The binder resin that is a constituent material of the toner of the present invention mainly contains a styrene-based binder resin. This styrene-based binder resin is a monomer containing styrene using a peroxide-based polymerization initiator. It was obtained by polymerizing. As a polymerization initiator generally used, there is an azo polymerization initiator. However, when only an azo polymerization initiator is used, the effect of the present invention cannot be obtained. That is, the azo polymerization initiator has low initiator efficiency, and the generated radical species causes radical coupling to produce a large amount of initiator decomposition products, which are high-boiling liquids or low-melting crystals. Since it is a product, it is very difficult to remove in the manufacturing process, and this decomposed product remains in a large amount in the toner. Since this decomposed product has a certain degree of polarity, for example, when a toner is produced by a polymerization method, it tends to be present near the surface of the toner particles, causing poor dispersion of the pigment and wax components in the toner, and fixing properties. There are problems such as deterioration, major problems in toner charging performance and storage resistance, and unpleasant odors of decomposition products during printout. Also, the amount of styrene monomer remaining in the toner is very large compared to the case where a peroxide polymerization initiator is used, and if a sufficient purification process is not performed, a monomer odor may be generated at the time of printout. is there. In that regard, when a peroxide polymerization initiator is used, the amount of initiator decomposition products is small, the removal of the decomposition products from the toner is relatively easy, and the residual styrene is also kept very low. Is possible. For this reason, when a peroxide-based polymerization initiator is used, stable chargeability and excellent fixability are achieved regardless of environmental fluctuations, which is an effect of the present invention, and the odor of styrene monomer and decomposition products is generated. There is nothing.
[0030]
Examples of peroxide polymerization initiators used in the present invention include peroxyesters and diacyl peroxides. Among these, peroxyesters are particularly effective for suppressing residual styrene, Since the gelation of the binder resin due to the hydrogen abstraction reaction of the peroxide is also suppressed, it is advantageous and preferable from the viewpoint of low-temperature fixability. Among the peroxyesters, t-butanol peroxyester is more preferable. Further, peroxyester and diacyl peroxide may be mixed and used.
Examples of peroxyesters that can be used in the present invention include t-butyl peroxyacetate, t-butyl peroxylaurate, t-butyl peroxypivalate, t-butyl peroxy-2-ethylhexanoate, t -Butyl peroxyisobutyrate, t-butyl peroxyneodecanoate, t-hexyl peroxyacetate, t-hexyl peroxylaurate, t-hexyl peroxypivalate, t-hexyl peroxy-2-ethyl Hexanoate, t-hexylperoxyisobutyrate, t-hexylperoxyneodecanoate, t-butylperoxybenzoate, α, α'-bis (neodecanoylperoxy) diisopropylbenzene, cumylperoxyneo Decanoate, 1,1,3,3-tetramethylbu Luperoxy-2-ethylhexanoate, 1,1,3,3-tetramethylbutylperoxyneodecanoate, 1-cyclohexyl-1-methylethylperoxyneodecanoate, 2,5-dimethyl-2, 5-bis (2-ethylhexanoylperoxy) hexane, 1-cyclohexyl-1-methylethylperoxy-2-ethylhexanoate, t-hexylperoxyisopropyl monocarbonate, t-butylperoxyisopropyl monocarbonate, t-butylperoxy 2-ethylhexyl monocarbonate, t-hexylperoxybenzoate, 2,5-dimethyl-2,5-bis (benzoylperoxy) hexane, t-butylperoxy-m-toluoylbenzoate, bis ( t-Butylperoxy) isophthalate , T-butylperoxymaleic acid, t-butylperoxy-3,5,5-trimethylhexanoate, 2,5-dimethyl-2,5-bis (m-toluoylperoxy) hexane, etc. Diacyl peroxides such as oxyesters, benzoyl peroxide, lauroyl peroxide, isobutyryl peroxide, and succinic peroxide, and t-butyl peroxyallyl monocarbonate and the like can be given. Of these, peroxyesters are suitable for reduction of residual styrene and low-temperature fixability (inhibition of binder resin gelation). If necessary, two or more of these peroxides can be used, and 2,2′-azobis- (2,4-dimethylvaleronitrile), 2,2 as long as the effects of the present invention are not impaired. '-Azobisisobutyronitrile, 1,1'-azobis (cyclohexane-1-carbonitrile), 2,2'-azobis-4-methoxy-2,4-dimethylvaleronitrile, azobisisobutyronitrile, etc. It is also possible to use an azo polymerization initiator in combination.
[0031]
The peroxide polymerization initiator used in the present invention has a molecular weight of 10,000 to 100,000 when the polymerization reaction is carried out at an addition amount of 0.5 to 20 parts by mass with respect to 100 parts by mass of the monomer. A polymer having a maximum can be obtained, and the toner can be provided with desirable strength and suitable melting characteristics.
[0032]
The theoretically active oxygen content of the organic peroxide polymerization initiator used in the present invention is preferably in the range of 4.0 to 12.0%. If the theoretical active oxygen amount is less than 4.0%, a large amount of polymerization initiator tends to be used, which is economically disadvantageous. If it exceeds 12.0%, handling and control of the polymerization reaction are difficult. It can be difficult.
The 10-hour half-life temperature of the peroxide polymerization initiator used in the present invention is preferably 30 to 100 ° C. When this half-life temperature is lower than 30 ° C., handling becomes difficult, and when it is higher than 100 ° C., a polymerization reaction at a very high temperature is required, or it is difficult to obtain a desired molecular weight. Is not preferable.
[0033]
In the toner of the present invention, it is essential that the content of carboxylic acid generated due to the organic peroxide is less than 2000 ppm. This is due to the following findings by the present inventors.
When peroxyester, which is an organic peroxide, undergoes thermal decomposition, it is first decomposed into the corresponding alcohol radical and carboxylic acid radical, and then these radicals and alkyl radicals generated by decarboxylation of the carboxylic acid radical are monomers. The polymerization reaction proceeds by the addition. Similarly, when diacyl peroxide undergoes thermal decomposition, it is first decomposed into carboxylic acid radicals, and then these radicals, and alkyl radicals generated by decarboxylation of the carboxylic acid radicals, are added to the monomer, and the polymerization reaction proceeds. To do. However, in the production of polymerized toners, carboxylic acids that have been considered to be hardly by-produced in the past (this is produced by the extraction of hydrogen from carboxylic acid radicals from charge control agents, colorants, monomers, polymers, etc.). It became clear by the present inventors that a large amount of by-product was produced. In addition, the present inventors have found that this carboxylic acid tends to enhance the dispersibility of the charge control agent and the wax component in the toner, and it is easy to obtain stable chargeability and is excellent in low-temperature fixability. . On the other hand, this carboxylic acid is a hydrophilic compound having a polar group, and if it is contained in the toner in an amount exceeding 2000 ppm, it will affect the environmental stability of the toner. The inventors have also found that charge-up occurs below. Therefore, it is preferable that such a carboxylic acid is present at the time of production. However, it is not until 2000 ppm is removed after the production that the toner has stable chargeability regardless of environmental changes and has excellent fixability. can get. In addition, when the content of the carboxylic acid is small, the odor at the time of fixing is small and more stable chargeability is obtained. Therefore, the content is preferably 1000 ppm or less, and more preferably 500 ppm or less. .
[0034]
There are various carboxylic acids produced by the decomposition of the peroxide polymerization initiator, and it varies depending on the type of acid structural component of the polymerization initiator, but 2-ethylhexanoic acid, neodecanoic acid, pivalic acid, isovaleric acid Succinic acid, benzoic acid, octanoic acid, stearic acid, lauric acid and the like.
[0035]
The residual styrene and the carboxylic acid in the toner can be quantified by gas chromatography as follows. About 250 mg of toner is precisely weighed in a sample bottle, and about 10 g of acetone precisely weighed is added thereto and mixed well. Ultrasonic waves are irradiated for 30 minutes with an ultrasonic cleaner. Thereafter, filtration is performed using a membrane filter (for example, disposable membrane filter 25JP020AN manufactured by Advantech Toyo Co., Ltd.), and 2 μl of the filtrate is analyzed by gas chromatography. Then, the residual amount of residual styrene or carboxylic acid is calculated using a calibration curve prepared in advance using styrene or carboxylic acid. In the present invention, analysis was performed under the following conditions.
[0036]
GC: HP 6890GC
Column: HP INNOWax (200 μm × 0.40 μm × 25 m)
Carrier gas: He (constant pressure mode: 20 psi)
Oven: 50 ° C., 10 min hold, temperature rise to 200 ° C. at 10 ° C./min, 200 ° C., 5 min hold.
INJ: 200 ° C., pulsed splitless mode (20 → 40 psi, until 0.5 min)
Split ratio: 5.0: 1.0
DET: 250 ° C (FID)
In the present invention, by controlling the content of the carboxylic acid in the toner to a low level, a toner having particularly good fixability and stable chargeability regardless of environmental changes can be obtained. In order to remove the carboxylic acid in the toner, a method of removing the toner particles by vacuum drying or heat drying after manufacturing the toner particles, a method of distilling the water in which the toner particles are suspended and distilling the water together with the water, There is a method in which suspended water is adjusted to be alkaline (by heating or stirring as necessary) to separate toner particles and water containing the carboxylic acid salt. Among these methods, it is preferable to use an alkali treatment method because it is most efficient and can be carried out easily. For example, in the case of a polymerized toner, an alkali such as sodium carbonate or sodium hydroxide is added to the aqueous medium after the polymerization is substantially completed to adjust the pH to 8 to 14, preferably 9 to 13, and more preferably 10 to 12. Then, heat and stir. By this operation, the carboxylic acid in the toner particles can be eluted in water as the corresponding water-soluble carboxylate. Thereafter, if the suspension is filtered, for example, the carboxylic acid salt is allowed to flow into the waste water and the carboxylic acid in the toner can be removed. Here, when the pH is in the range of 10 to 12, it is more preferable that the neutralization of the carboxylic acid is performed and the hydrolysis of the functional group (for example, ester of acrylic acid) in the binder resin can be suppressed. It is. In addition, it is very important to substantially separate the toner particles and the aqueous medium while maintaining the alkaline polymerization suspension in an alkaline state. For example, as described in JP-A-10-020548, if the pH of the aqueous medium is acidified without going through the separation step of the aqueous medium, the carboxylic acid salt dissolved in the water becomes water again. This is because the removal of the carboxylic acid from the toner particles becomes very incomplete because it returns to the insoluble carboxylic acid. The toner particles and the aqueous medium can be separated by appropriately selecting a conventionally known method such as filtration and centrifugation.
[0037]
In addition, when a dispersion stabilizer is used, it is desirable to remove the dispersant after the production of the toner, and if the dispersant remains on the toner surface, there may be a serious problem in chargeability, particularly environmental stability. Since there are many, it is preferable to remove as much as possible. For example, when tricalcium phosphate is used as a dispersant, the tricalcium phosphate is added by adding an acid to the suspension after polymerization by utilizing the property of the dispersant being acidic and soluble in water. Almost complete removal is possible. When tricalcium phosphate is dissolved, tricalcium phosphate can be removed in a short time by setting the pH of the aqueous medium in which the toner particles are suspended to less than 4, more preferably less than 2.
[0038]
Examples of the wax component used in the present invention include paraffin wax and derivatives thereof, microcrystalline wax and derivatives thereof, Fischer-Tropsch wax and derivatives thereof, polyolefin wax and derivatives thereof, carnauba wax and derivatives thereof, and the like. Here, the derivatives include oxides, block copolymers with vinyl monomers, graft modified products, and the like. Furthermore, as the wax component, higher fatty acids and metal salts thereof, higher aliphatic alcohols, higher aliphatic esters, aliphatic amide waxes, ketones, hydrogenated castor oil and derivatives thereof, plant waxes, animal waxes, mineral waxes, Examples include petrolactam.
[0039]
These wax components preferably have a maximum endothermic peak in the region of 40 to 110 ° C. when the temperature rises in a DSC curve measured by a differential differential calorimeter. This is because by having the maximum endothermic peak in this region, the mold releasability can be effectively expressed while greatly contributing to low-temperature fixing. When the maximum endothermic peak is less than 40 ° C., the self-aggregation force of the wax component becomes weak, resulting in deterioration of the high temperature offset resistance and excessive gloss. On the other hand, when the maximum endothermic peak exceeds 110 ° C., the fixing temperature becomes high and it becomes difficult to appropriately smooth the surface of the fixed image. Absent. Further, in the case where granulation / polymerization is carried out in an aqueous medium and a toner is directly obtained by the polymerization method, if this maximum endothermic peak temperature is high, problems such as precipitation of a wax component mainly during granulation are undesirable. Therefore, it is preferable to use a wax having an endothermic peak in the range of 40 to 110 ° C. from the viewpoint of obtaining low-temperature fixability and a high-quality image, and using a wax having an endothermic peak in the range of 45 to 90 ° C. Is more preferable.
[0040]
The maximum endothermic peak temperature of the wax component is measured according to “ASTM D 3418-8”. For the measurement, for example, DSC-7 manufactured by PerkinElmer is used. The temperature correction of the device detection unit uses the melting points of indium and zinc, and the correction of heat uses the heat of fusion of indium. An aluminum pan is used as a measurement sample, an empty pan is set as a control, and measurement is performed at a heating rate of 10 ° C./min.
In the present invention, the addition amount of these wax components is not particularly limited, but is generally preferably 0.5 to 50% by mass with respect to the binder resin.
[0041]
The binder resin that is a constituent material of the toner of the present invention must contain at least a styrene-based binder resin. In this case, the styrene binder resin may be produced by appropriately selecting a known method, and can be obtained by copolymerizing a styrene monomer and another monomer. Other monomers include styrene monomers such as o-methyl styrene, m-methyl styrene, p-methyl styrene, m-ethyl styrene, p-ethyl styrene, methyl acrylate, ethyl acrylate, acrylic Acrylic acid ester monomers such as propyl acid, butyl acrylate, octyl acrylate, dodecyl acrylate, stearyl acrylate, behenyl acrylate, 2-ethylhexyl acrylate, dimethylaminoethyl acrylate, diethylaminoethyl acrylate, Methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, octyl methacrylate, dodecyl methacrylate, stearyl methacrylate, behenyl methacrylate, 2-ethylhexyl methacrylate, methacrylic acid The Chill aminoethyl, methacrylic acid ester monomers such as methacrylic acid diethylaminoethyl, butadiene, isoprene, cyclohexene, (meth) acrylonitrile, ene monomer is preferably used as acrylamide. These are used by appropriately mixing the monomers so that the theoretical glass transition temperature (Tg) described in the publication Polymer Handbook 2nd edition III-p139-192 (John Wiley & Sons) is 40-75 ° C. . When the theoretical glass transition temperature is less than 40 ° C., problems are likely to occur from the viewpoint of storage stability and durability stability of the toner, whereas when it exceeds 75 ° C., the fixing point of the toner is increased. In particular, in the case of a color toner for forming a full-color image, the color mixing property at the time of fixing each color toner is deteriorated and the color reproducibility becomes poor, and further, the transparency of the OHP image is deteriorated.
[0042]
In addition, other binder resins can be used in combination with the binder resin, and depending on the material, the outermost layer of the toner particles may be covered with another binder resin to improve storage stability and durability. Is possible. However, even when other binder resins are used in combination, the content of styrene-acrylic resin is preferably 50 to 100% by mass, more preferably 80 to 100% by mass with respect to the total binder resin. . This is because if the content is less than 50% by mass, it becomes difficult to balance low-temperature fixability and developability.
[0043]
When the toner of the present invention is produced, the molecular weight of the main peak in GPC of the binder resin in the obtained toner particles is 3,000 to 100,000, particularly preferably 5,000 to 50,000. is there.
[0044]
When the toner according to the present invention is produced by a polymerization method, a resin may be added to the monomer composition for polymerization. For example, it contains hydrophilic functional groups such as amino groups, carboxyl groups, hydroxyl groups, sulfonic acid groups, glycidyl groups, and nitrile groups that cannot be used because monomers are water soluble and dissolve in aqueous suspension to cause emulsion polymerization. When it is desired to introduce the monomer component into the toner, a random copolymer of these with a vinyl compound such as styrene or ethylene, a block copolymer, a graft copolymer, or the like, or a polyester It can be used in the form of a polycondensate such as polyamide, or a polyaddition polymer such as polyether or polyimine. When such a polymer containing a polar functional group is allowed to coexist in the toner, the above-mentioned wax component is phase-separated and the encapsulation becomes stronger, and a toner having good offset resistance, blocking resistance, and low-temperature fixability can be obtained. Obtainable. In the case of using a polymer having such a polar functional group, the polymerization average molecular weight is preferably 5,000 or more. If the molecular weight is less than 5,000, especially 4,000 or less, the present polymer is likely to concentrate in the vicinity of the surface.
In addition, resins other than those described above may be added to the monomer system for the purpose of improving the dispersibility and fixing properties of the material or image characteristics. Examples of the resin used include styrene such as polystyrene and polyvinyltoluene. And styrene-propylene copolymer, styrene-vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, Styrene-butyl acrylate copolymer, styrene-octyl acrylate copolymer, styrene-dimethylaminoethyl acrylate copolymer, styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene -Butyl methacrylate copolymer, styrene-dimethyl methacrylate Copolymer, styrene-vinyl methyl ether copolymer, styrene-vinyl ethyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-isoprene copolymer, styrene-maleic acid copolymer, styrene-maleic Styrene-maleic acid copolymers such as acid ester copolymers; polymethyl methacrylate, polybutyl methacrylate, polyvinyl acetate, polyethylene, polypropylene, polyvinyl butyrate, silicone resin, polyester resin, polyamide resin, epoxy resin, polyacrylic acid Resin, rosin, modified rosin, temper resin, phenol resin, aliphatic or alicyclic hydrocarbon resin, aromatic petroleum resin and the like can be used alone or in combination.
As addition amount of these resin, 1-20 mass parts is preferable with respect to 100 mass parts of monomers. If it is less than 1 part by mass, the effect of addition is small, while if it exceeds 20 parts by mass, it becomes difficult to design various physical properties of the polymerized toner.
[0045]
In the present invention, the molecular weight of the peak of the chromatogram by GPC (gel permeation chromatography) can be measured under the following conditions.
That is, the column was stabilized in a heat chamber at 40 ° C., and the column at this temperature was passed through THF (tetrahydrofuran) as a solvent at a flow rate of 1 ml / min. To a sample concentration of 0.05 to 0.1% by mass. Measurement is performed by injecting 50 to 200 μl of a THF sample solution of the prepared resin. In measuring the molecular weight of a sample, the molecular weight distribution of the sample is calculated from the relationship between the logarithmic value of a calibration curve prepared from several types of monodisperse polystyrene standard samples and the number of counts. As a standard polystyrene sample for preparing a calibration curve, for example, a molecular weight manufactured by Pressure Chemical Co or Toyo Soda Industry Co., Ltd. is 6 × 10.²2.1 × 10^Three4 × 10^Three1.75 × 10^Four5.1 × 10^Four1.1 × 10^Five3.9 × 10^Five8.6 × 10^Five2 × 10⁶4.48 × 10⁶It is appropriate to use at least about 10 standard polystyrene samples. An RI (refractive index) detector is used as the detector.
As the column, it is preferable to combine a plurality of commercially available polystyrene gel columns. For example, a combination of μ-stilage 1500, 103, 104, 105 manufactured by Waters, a combination of KF-802, 803, 804, 805, or A combination of TSKgel G1000H, G2000H, G2500H, G3000H, G4000H, G5000H, G6000H, G700H, GHM manufactured by Tosoh Corporation is preferable.
[0046]
Examples of the colorant used in the present invention include the following yellow colorant, magenta colorant, and cyan colorant. As the black colorant, carbon black, magnetic substance, or yellow colorant / magenta colorant / cyan color shown below. What was mixed with the agent and was toned to black is used.
As the yellow colorant, compounds represented by condensed azo compounds, isoindolinone compounds, anthraquinone compounds, azo metal complexes, methine compounds, allylamide compounds, and the like are used. Specifically, C.I. I. Pigment Yellow 12, 13, 14, 15, 17, 62, 74, 83, 93, 94, 95, 109, 110, 111, 128, 129, 147, 168, 180, etc. are preferably used.
[0047]
As the magenta colorant, condensed azo compounds, diketopyrrolopyrrole compounds, anthraquinones, quinacridone compounds, basic dye lake compounds, naphthol compounds, benzimidazolone compounds, thioindigo compounds, perylene compounds, and the like are used. Specifically, C.I. I. Pigment Red 2, 3, 5, 6, 7, 23, 48; 2, 48; 3, 48; 4, 57; 1, 81; 1, 144, 146, 166, 169, 177, 184, 185, 202, 206, 220, 221, 254 are particularly preferred.
As the cyan colorant, copper phthalocyanine compounds and derivatives thereof, anthraquinone compounds, basic dye lake compounds, and the like can be used. Specifically, C.I. I. Pigment Blue 1, 7, 15, 15: 1, 15: 2, 15: 3, 15: 4, 60, 62, 66 and the like can be used particularly preferably.
[0048]
These colorants can be used alone or in combination of two or more, and further in a solid solution state. The colorant is selected from the viewpoints of hue, saturation, lightness, weather resistance, OHP transparency, and dispersibility. The amount of the colorant added is preferably 1 to 20 parts by mass with respect to 100 parts by mass of the resin component.
[0049]
The toner of the present invention may contain a charge control agent. As the charge control agent used in the present invention, a known charge control agent can be appropriately selected and used. In particular, a charge control agent having a high charging speed and capable of stably maintaining a constant charge amount is used. Is preferred. Further, when the toner particles are produced using a direct polymerization method, a charge control agent having a low polymerization inhibitory property and substantially free from a solubilized product in an aqueous dispersion medium is particularly preferable. Specific compounds include, as negative charge control agents, metal compounds of aromatic carboxylic acids such as salicylic acid, naphthoic acid, dicarboxylic acid, polymer compounds having sulfonic acid or carboxylic acid groups in the side chain, boron compounds , Urea compounds, silicon compounds, calixarene, monoazo iron complexes, chromium complexes, and the like. Examples of the positive charge control agent include a quaternary ammonium salt, a polymer compound having the quaternary ammonium salt in the side chain, a guanidine compound, and an imidazole compound.
The charge control agent is preferably used in an amount of 0.1 to 10 parts by mass with respect to 100 parts by mass of the resin. However, in the present invention, the addition of a charge control agent is not essential.When a two-component development method is used, friction charging with a carrier is used, and when a non-magnetic one-component blade coating development method is used, It is not always necessary to include a charge control agent in the toner particles by actively utilizing frictional charging with the blade member or the sleeve member.
[0050]
In the present invention, the observation of the tomographic plane of the toner is specifically performed as follows. First, after fully dispersing toner or toner particles in a room temperature curable epoxy resin, the cured product obtained by curing for 2 days in an atmosphere of 40 ° C. is combined with ruthenium tetroxide and, if necessary, osmium tetroxide. Then, a sliced sample is cut out using a microtome equipped with diamond teeth, and the tomographic plane of the toner is observed using a transmission electron microscope. In the present invention, it is preferable to use a ruthenium tetroxide dyeing method in order to provide a contrast between materials by utilizing a slight difference in crystallinity between the wax component to be used and the binder resin constituting the outer shell. A schematic diagram showing a typical example is shown in FIG. When the toner A and K obtained in Example 1 and Comparative Example 1 described below are observed on a tomographic plane using a transmission electron microscope (TEM), in the case of toner A, the wax component is contained in the binder resin. In the case of toner K, it was observed that the wax component was finely dispersed in the binder resin. Therefore, a toner is used in which a wax component is observed to be dispersed in a substantially spherical and spindle-shaped island shape in a binder resin when a tomographic plane is observed using a transmission electron microscope (TEM). Is preferred.
[0051]
The toner of the present invention further has an inorganic fine powder on the surface of nonmagnetic toner particles as a fluidity improver. As the inorganic fine powder, for example, silica fine powder, titanium oxide fine powder, alumina fine powder, those obtained by subjecting the surface of these fine powders to a hydrophobic treatment, etc. can be used alone or in combination of two or more. . Among these, it is preferable to use silica. For example, the silica used here can be both dry silica produced by the so-called dry method produced by vapor phase oxidation of silicon halide or alkoxide, and so-called wet silica produced from alkoxide water glass or the like. However, there are few silanol groups on the silica surface and in the silica fine powder, and Na₂O, SO_Three ^2-It is more preferable to use dry silica in terms of a small amount of production residue such as. In addition, it is also possible to obtain a composite fine powder of silica and other metal oxides by using other metal halogen compounds such as aluminum chloride and titanium chloride together with silicon halogen compounds in the production process. The dry silica includes such composite fine powder. The inorganic fine powder used in the toner has a specific surface area of 30 m by nitrogen adsorption measured by the BET method.²/ G or more, especially 50-400m²Those in the range of / g are preferable because good results can be obtained. The compounding amount of the silica fine powder is preferably 0.1 to 8 parts by mass, more preferably 0.5 to 5 parts by mass with respect to 100 parts by mass of the toner particles, and 0.5 to 3. The range of 0 part by mass is particularly preferable. In addition, the inorganic fine powder used in the present invention has a silicone varnish, various modified silicone varnishes, silicone oil, various modified silicone oils, a silane coupling agent, and a functional group as necessary for the purpose of hydrophobicity and chargeability control. It is preferable that the silane coupling agent, other organic silicon compounds, organic titanium compounds and the like, or a combination with various treatment agents. Therefore, among the inorganic fine powders, those treated with silicone oil, particularly hydrophobic silica, are preferable because they are highly effective in improving the triboelectric chargeability and transferability of the toner particles.
The particle size distribution control and particle size control of the toner particles can be controlled by changing the type and amount of the poorly water-soluble inorganic salt and the dispersing agent that acts as a protective colloid and the mechanical device conditions (for example, the peripheral speed of the rotor, the number of passes, Predetermined toner particles can be obtained by controlling the stirring conditions such as the shape of the stirring blades and the shape of the container) or the solid content concentration in the aqueous solution.
[0052]
As a method for producing the toner of the present invention, various polymerization methods such as a suspension polymerization method, a dispersion polymerization method, and an emulsion association polymerization method can be used, but it is preferable to use a suspension polymerization method. At this time, a dispersion stabilizer can also be used.
When a suspension polymerization method using a dispersion stabilizer is used as a toner production method, the dispersion stabilizer used is tricalcium phosphate, magnesium phosphate, aluminum phosphate, zinc phosphate, calcium carbonate, magnesium carbonate, Examples include calcium hydroxide, magnesium hydroxide, aluminum hydroxide, calcium metasilicate, calcium sulfate, barium sulfate, bentonite, silica, alumina, and the like. Particularly, tricalcium phosphate is preferable because a toner having a sharp particle size can be obtained. . These dispersion stabilizers are preferably used in an amount of 0.2 to 20 parts by mass with respect to 100 parts by mass of the polymerizable monomer.
[0053]
A commercially available dispersion stabilizer may be used as it is, but fine particles may be generated in a dispersion medium to obtain fine particles. For example, in the case of tricalcium phosphate, a sodium phosphate aqueous solution and a calcium chloride aqueous solution may be mixed under high-speed stirring.
For fine dispersion, 0.001 to 0.1 parts by mass of a surfactant may be used in combination. This is for accelerating the action of the dispersion stabilizer, for example, sodium dodecylbenzene sulfate, sodium tetradecyl sulfate, sodium pentadecyl sulfate, sodium octyl sulfate, sodium oleate, sodium laurate, potassium stearate, oleic acid Examples include calcium.
[0054]
When a polymerization method is used as a method for producing the toner used in the present invention, the following production method is possible.
A monomer composition in which a wax component, a colorant, a polymerization initiator, and if necessary, a charge control agent and other additives are added to the polymerizable monomer, and the monomer composition is uniformly dissolved or dispersed by a homogenizer, an ultrasonic disperser or the like. Is dispersed in a water phase containing a dispersion stabilizer by a usual stirrer, homomixer, homogenizer or the like. Preferably, granulation is performed by adjusting the stirring speed and stirring time so that the droplets of the monomer composition have the desired toner particle size. Thereafter, 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 is preferably carried out at a polymerization temperature of 40 ° C. or higher, generally 50 to 90 ° C. The temperature may be raised in the latter half of the polymerization reaction.Further, in the image forming method of the present invention, in order to remove unreacted polymerizable monomers and by-products for the purpose of improving durability, A part of the aqueous medium may be distilled off from the reaction system in the latter half of the reaction or after the completion of the reaction. After the completion of the reaction, the produced toner particles are washed, collected by filtration, and dried. In the suspension polymerization method, it is usually preferable to use 300 to 3000 parts by mass of water as a dispersion medium with respect to 100 parts by mass of the monomer composition.
[0055]
In addition, when a dispersion stabilizer is used, it is desirable to remove the dispersant after the production of the toner, and if the dispersant remains on the toner surface, there may be a serious problem in chargeability, particularly environmental stability. Since there are many, it is preferable to remove as much as possible. For example, when tricalcium phosphate is used as a dispersant, the tricalcium phosphate is added by adding an acid to the suspension after polymerization by utilizing the property of the dispersant being acidic and soluble in water. Almost complete removal is possible. When tricalcium phosphate is dissolved, tricalcium phosphate can be removed in a short time by setting the pH of the aqueous medium in which the toner particles are suspended to less than 4, more preferably less than 2.
[0056]
In addition, the nonmagnetic polymerization method toner particle production method of the present invention suspends a monomer composition containing a monomer, a colorant, and a wax component in an aqueous medium, and at least an organic catalyst as a polymerization initiator. Polymerization is performed using an oxide, and toner particles and an alkaline aqueous medium are substantially separated after suspension polymerization. Specifically, the method includes a step of suspending a monomer composition in an aqueous medium, a step of polymerizing using an organic peroxide as a polymerization initiator, and a step of separating toner particles from an alkaline aqueous medium. To do.
[0057]
【Example】
Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples.
Hereinafter, the present invention will be described with reference to specific examples, but the present invention is not limited thereto.
[0058]
<Example 1>
In a 4-liter separable flask for 2 liters equipped with a high-speed stirring device TK type homomixer (manufactured by Special Machine Industries), 325 parts by mass of ion-exchanged water and 0.1 mol / l-Na_ThreePO_Four250 parts by mass of the aqueous solution was added, the rotation speed was adjusted to 12000 rpm, and the mixture was heated to 80 ° C. Here 1.0 mol / l-CaCl₂Gradually add 35 parts by weight of an aqueous solution and add a minute amount of poorly water-soluble dispersion stabilizer Ca_Three(PO_Four)₂An aqueous continuous phase containing was prepared.
[0059]
On the other hand, as dispersoid,
・ 83 parts by mass of styrene
・ 17 parts by mass of n-butyl acrylate
・ Divinylbenzene (purity 55%) 0.1 parts by mass
・ Carbon black (BET specific surface area = 96m²/ G) 5 parts by mass
-5 parts by mass of ester wax with a maximum endothermic peak of 75 ° C
-Negative charge control agent (monoazo dye-based Fe compound) 2 parts by mass
・ 6 parts by mass of t-butylperoxy-2-ethylhexanoate
Were mixed uniformly.
[0060]
Next, the monomer composition is charged into the aqueous medium, and the mixture is heated to 80 ° C., N₂In an atmosphere, the mixture was stirred for 10 minutes at 10,000 rpm with a TK homomixer (Special Machine Industries Co., Ltd.) and granulated. Then, while stirring with a paddle stirring blade, the mixture was reacted at 80 ° C. for 4 hours, 4 parts by mass of anhydrous sodium carbonate was added to the system, and the reaction was continued for another 2 hours (the pH of the suspension after the reaction was 10 .5). After completion of the reaction, the suspension was cooled, and the following operation was performed using a continuous belt filter (trade name “Eagle Filter” manufactured by Sumitomo Heavy Industries, Ltd.).
[0061]
First, the alkaline suspension is dehydrated on a belt, and then a total amount of 1000 parts by mass of water is showered and washed with water. Sodium 2-ethylhexanoate contained in the suspension (this is the start of polymerization) 2-ethylhexanoic acid produced as a by-product by decomposition of t-butylperoxy-2-ethylhexanoate, which is an agent, was neutralized with sodium carbonate). Furthermore, 2-ethylhexanoic acid and calcium phosphate used as a dispersant are substantially obtained by performing washing with 1000 parts by mass of diluted hydrochloric acid (pH 1.0), washing with 1000 parts by mass of water, and dehydration on the belt. The toner particles removed were obtained.
[0062]
Thereafter, the water-containing toner particles were dried with hot air at 40 ° C. for 48 hours to obtain toner particles having a mass average particle diameter of 6.8 μm. The dry toner particles were heated to a constant weight at 120 ° C. with a thermobalance and the volatile content was measured and found to be 0.2%.
Next, 100 parts by mass of toner particles and the surface were treated with hexamethyldisilazane and then with silicone oil, and the BET value after treatment was 200 m.²Toner A was prepared by mixing 2.0 parts by mass of / g hydrophobic silica fine powder with a Henschel mixer (Mitsui Miike Chemical Co., Ltd.).
[0063]
<Example 2>
Toner B was obtained in the same manner as in Example 1 except that the amount of water used for water washing before dilute hydrochloric acid washing was reduced from 1000 parts by mass to 100 parts by mass.
<Example 3>
Toner C was obtained in the same manner as in Example 1 except that the amount of anhydrous sodium carbonate was reduced from 4 parts by mass to 0.4 parts by mass. The pH after completion of the reaction was 9.2.
<Example 4>
Toner D was obtained in the same manner as in Example 1 except that water was not washed before dilute hydrochloric acid.
<Example 5>
Toner E was obtained in the same manner as in Production Example 1 except that the amount of ester wax used was 51 parts by mass.
<Example 6>
Toner F was obtained in the same manner as in Production Example 1 except that the amount of ester wax used was 0.4 parts by mass.
<Example 7>
Toner G was obtained in the same manner as in Example 1, except that 8 parts by mass of t-butylperoxyneodecanoate was used instead of t-butylperoxy-2-ethylhexanoate.
[0064]
<Reference example8>
  In a 4-liter separable flask for 2 liters equipped with a high-speed stirring device TK type homomixer (manufactured by Special Machine Industries), 325 parts by mass of ion-exchanged water and 0.1 mol / l-Na₃PO₄250 parts by mass of the aqueous solution was added, the rotation speed was adjusted to 12000 rpm, and the mixture was heated to 80 ° C. Here 1.0 mol / l-CaCl₂Gradually add 35 parts by weight of an aqueous solution and add a minute amount of poorly water-soluble dispersion stabilizer Ca₃(PO₄)₂An aqueous continuous phase containing was prepared.
[0065]
On the other hand, as dispersoid,
・ 83 parts by mass of styrene
・ 17 parts by mass of n-butyl acrylate
・ Divinylbenzene (purity 55%) 0.1 parts by mass
・ Carbon black (BET specific surface area = 96m²/ G) 5 parts by mass
-2 parts by mass of low molecular weight polypropylene with a maximum endothermic peak of 120 ° C
・ Cr-based dye (Hodogaya Chemical Co., Ltd., trade name TRH) 1 part by mass
・ Succinic acid peroxide 6 parts by mass
Were mixed uniformly.
[0066]
Next, the monomer composition is charged into the aqueous medium, and the mixture is heated to 80 ° C., N₂In an atmosphere, the mixture was stirred for 10 minutes at 10,000 rpm with a TK homomixer (Special Machine Industries Co., Ltd.) and granulated. Then, while stirring with a paddle stirring blade, the reaction was carried out at 80 ° C. for 4 hours, 4 parts by weight of anhydrous sodium carbonate was added to the system, and the reaction was continued for another 2 hours (the pH of the suspension after the reaction was 10 .5). After completion of the reaction, the suspension was cooled, and the following operation was performed using a filter press (manufactured by Kurita Machinery Co., Ltd.).
[0067]
  First, an alkaline suspension is introduced into a filter press to filter toner particles. Next, a total amount of 1000 parts by mass of water was poured into the filter frame, and sodium succinate in the suspension (this was by-produced succinic acid by decomposition of the succinic acid peroxide as a polymerization initiator). Washed out). Further, dilute hydrochloric acid having a pH of 1.0 is poured into the filter frame to dissolve and remove calcium phosphate adhering to the toner particle surfaces. Thereafter, water is poured into the filter frame to perform sufficient washing. By pressing and air blowing, toner particles from which succinic acid and calcium phosphate used as a dispersant were substantially removed were obtained. Thereafter, toner H was obtained in the same manner as in Example 1.
<Reference example9>
  Except for using 8 parts by mass of benzoyl peroxide instead of succinic acid peroxideReference exampleToner I was obtained in the same manner as in Example 8.
<Reference example10>
  Except for using 6 parts by mass of 1-cyclohexyl-1-methylethylperoxy-2-ethylhexanoate instead of succinic acid peroxideReference exampleIn the same manner as in No. 8, toner J was obtained.
[0068]
<Comparative Example 1>
In a reaction vessel, 200 parts by mass of xylene was added and the temperature was raised to the reflux temperature. To this was added dropwise a mixed solution of 83 parts by mass of styrene, 17 parts by mass of acrylate-n-butyl and 2.0 parts by mass of di-tert-butyl peroxide, and the solution polymerization was completed in 7 hours under reflux of xylene. A low molecular weight resin solution was obtained.
On the other hand, 67 parts by mass of styrene, 25 parts by mass of butyl acrylate, 8 parts by mass of monobutyl maleate, 0.2 parts by mass of polyvinyl alcohol, 200 parts by mass of deaerated water, and 0.3 parts by mass of benzoyl peroxide were mixed and dispersed. It was. The suspension dispersion was heated and maintained at 85 ° C. for 24 hours under a nitrogen atmosphere to complete the polymerization, thereby obtaining a high molecular weight resin.
[0069]
25 parts by mass of this high molecular weight resin is put into a solution at the end of the solution polymerization containing 75 parts by mass of the low molecular weight resin, and completely dissolved in a solvent and mixed. A resin (1) was obtained.
Next, the following materials are mixed in a blender, melted and kneaded with a biaxial extruder heated to 150 ° C., the cooled kneaded product is coarsely pulverized with a hammer mill, and the coarsely pulverized product is then mixed with a jet mill. Finely pulverized.
[0070]
・ Binder resin (1) 100 parts by mass
・ Carbon black (BET specific surface area = 96m²/ G) 5 parts by mass
・ Low molecular weight polyethylene with a maximum endothermic peak of 115 ° C. 2 parts by mass
Thereafter, classification is performed, and 100 parts by mass of the classified powder and a hydrophobic silica fine powder (BET: 160 m²/ G) 2 parts by mass were dry-mixed with a Henschel mixer to obtain a comparative toner K.
[0071]
<Comparative example 2>
In a 4-liter separable flask for 2 liters equipped with a high-speed stirring device TK type homomixer (manufactured by Special Machine Industries), 325 parts by mass of ion-exchanged water and 0.1 mol / l-Na_ThreePO_Four250 parts by mass of the aqueous solution was added, the rotation speed was adjusted to 12000 rpm, and the mixture was heated to 80 ° C. Here 1.0 mol / l-CaCl₂Gradually add 35 parts by weight of an aqueous solution and add a minute amount of poorly water-soluble dispersion stabilizer Ca_Three(PO_Four)₂An aqueous continuous phase containing was prepared.
On the other hand, as dispersoid,

The monomer composition is charged into the aqueous medium, 80 ° C., N₂In an atmosphere, the mixture was stirred for 10 minutes at 10,000 rpm with a TK homomixer (Special Machine Industries Co., Ltd.) and granulated. Thereafter, the mixture was reacted at 80 ° C. for 6 hours while stirring with a paddle stirring blade (the pH of the suspension after the reaction was 9.1). After completion of the reaction, the suspension was cooled, diluted hydrochloric acid was added to adjust the pH to 1.0, and the mixture was stirred for 1 hour. Thereafter, the suspension was filtered through a continuous belt filter, washed with water, and dried to obtain toner particles having a mass average particle diameter of 6.6 μm.
100 parts by mass of the toner particles and 1.1 parts by mass of the hydrophobic silica fine powder used in Production Example 1 were mixed with a Henschel mixer (Mitsui Miike Chemical Co., Ltd.) to prepare toner L.
[0072]
<Comparative Example 3>
Toner M was obtained in the same manner as in Comparative Example 2, except that 6 parts by mass of succinic acid peroxide was used in place of t-butylperoxy-2-ethylhexanoate.
The analysis values of the toners A to J and the comparative toners K to M are shown in Table 1 below.
[0073]
[Table 1]

[0074]
The photoconductor used here is an Al cylinder having a diameter of 30 mm and 254 mm as a base, and layers having the following constitutions are sequentially laminated by dip coating to prepare a photoconductor.
(1) Conductive coating layer: Mainly composed of a powder of tin oxide and titanium oxide dispersed in a phenolic resin. Film thickness 15 μm.
(2) Undercoat layer: Mainly composed of modified nylon and copolymer nylon. Film thickness 0.6 μm.
(3) Charge generation layer: Mainly composed of a titanyl phthalocyanine pigment having absorption in a long wavelength region dispersed in a butyral resin. Film thickness 0.6 μm.
(4) Charge transport layer: hole transportable triphenylamine Mainly composed of a compound obtained by dissolving a compound in polycarbonate resin (molecular weight 20,000 by Ostwald viscosity method) at a mass ratio of 8:10. Film thickness 40 μm.
[0075]
As a means for applying the toner to the toner carrier, an application roller made of urethane foam rubber was provided in the developing device and brought into contact with the toner carrier. A voltage of about −550 V is applied to the application roller. Further, a stainless steel blade coated with resin for controlling the coat layer of the toner on the toner carrier was attached so that the contact pressure with the toner carrier was a linear pressure of about 20 g / cm. In addition, the applied voltage at the time of development was only a DC component (−450 V).
The electrophotographic apparatus was remodeled and process conditions were set as follows in order to conform to the remodeling of these process cartridges.
The modified device uses a roller charger (applying only direct current) to uniformly charge the image carrier. Subsequent to charging, an image portion is exposed with a laser beam to form an electrostatic latent image, and a visible image is formed with toner, and then the toner image is transferred to a transfer material by a roller to which a voltage of +700 V is applied. The photosensitive member charging potential was -580V for the dark portion potential and -150V for the bright portion potential.
[0076]
Next, each of the toners A to J and the comparative toners K to M was filled in the developing unit, and the developing unit was set in the image forming apparatus. Under normal temperature and humidity (25 ° C, 60% RH) environment, printout speed of 14 sheets / minute (A4 size), 100 sheets of “Durning” character pattern, 2 solid black images, 2 solid white images each Then, 100 “Denjin” character patterns were continuously printed out. Thereafter, 5 solid white images and 1 solid black image were printed out in a low temperature and low humidity (15 ° C., 15% RH) environment together with the image forming apparatus. Further, the entire image forming apparatus was set in an environment of high temperature and high humidity (33 ° C., 90% RH), and 100 solid black images and 1 solid white image were printed out. The obtained printout image and the like were evaluated for the items described below.
The above evaluation results are shown in Table 2 below.
[0077]
[Table 2]

Descriptions of evaluation items described in Examples and Comparative Examples of the present invention and evaluation criteria thereof will be described.
1) Image density
With respect to a solid black image in a normal temperature and humidity environment, a relative density with respect to a printout image of a white background portion having a document density of 0.00 was measured by a Macbeth reflection densitometer RD918 (manufactured by Macbeth).
[0078]
A: Very good (above 1.40)
B: Good (1.35 or more and less than 1.40)
C: Normal (1.00 or more, less than 1.35)
D: Bad (less than 1.00)
2) Charging stability
The difference in image density of the solid black image under low temperature and low humidity and high temperature and high humidity was used as an index of charging stability of the toner.
[0079]
A: Very good (less than 0.05)
B: Good (0.05 or more and less than 0.10)
C: Normal (0.10 or more, less than 0.20)
D: Bad (over 0.20)
3) Transferability
Transfer residual toner on the photoconductor at the time of solid black image formation under normal temperature and humidity to tape off with Mylar tape, and paste only Mylar tape on the paper from the Macbeth concentration of the stripped Mylar tape on the paper. The value was calculated by subtracting the Macbeth concentration of the fish.
[0080]
A: Very good (less than 0.05)
B: Good (0.05 or more, less than 0.1)
C: Normal (0.1 or more, less than 0.2)
D: Bad (over 0.2)
4) fog
For solid white images under high temperature and high humidity, the fog density (%) is calculated from the difference between the whiteness measured by “Reflectometer” (manufactured by Tokyo Denshoku) and the whiteness of the transfer paper, and the image fog is evaluated. did.
[0081]
A: Very good (less than 1.5%)
B: Good (1.5% or more, less than 3.0%)
C: Normal (3.0% or more and less than 5.0%)
D: Poor (5.0% or more)
5) Fixability
For solid black images under low temperature and low humidity, 50 g / cm²The fixed image was rubbed with a soft thin paper and evaluated by the rate of decrease in image density (%) before and after rubbing.
[0082]
A: Very good (less than 5%)
B: Good (5% or more and less than 10%)
C: Normal (10% or more, less than 20%)
D: Bad (more than 20%)
The matching evaluation with the image forming apparatus was performed according to the following evaluation criteria.
1) Matching with photoconductor
After completion of the printout test, the occurrence of scratches on the surface of the photosensitive drum and the sticking of residual toner and the influence on the printout image were visually evaluated.
[0083]
A: Not generated
B: Slight scratching is observed
C: There are sticking and scratches
D: Many sticking
2) Matching with fixing unit
After completion of the printout test, scratches on the surface of the fixing film and the fixing state of the residual toner were visually evaluated.
[0084]
A: Not generated
B: Slightly fixed
C: There are sticking and scratches
D: Many sticking
[Brief description of the drawings]
FIG. 1A is a schematic diagram of a tomographic image of a toner A observed with a TEM.
(B) Schematic diagram of a tomographic image of toner K by TEM.

Claims (11)

A dry nonmagnetic toner having inorganic fine powder on the surface of nonmagnetic toner particles containing a styrene-based binder resin, a colorant, and a wax component,
The toner particles are prepared by dispersing a monomer composition containing a monomer containing a styrene monomer, a colorant, and a wax component in an aqueous medium containing a dispersion stabilizer that is soluble in acid. Toner particles obtained by suspension polymerization using a polymerization initiator and dissolving and removing the resulting dispersion stabilizer on the particle surface with an acid,
The polymerization initiator is an organic peroxide , and the organic peroxide is t-butylperoxyneodecanoate, t-butylperoxypivalate, t-butylperoxy-2-ethylhexanoate, t-butylperoxyisobutyrate, t-butylperoxymaleic acid, t-butylperoxy-3,5,5-trimethylhexanoate, t-butylperoxylaurate, t-butylperoxyisopropyl One or more selected from monocarbonate and t-butylperoxy-2-ethylhexyl monocarbonate ,
The content of carboxylic acid, which is a decomposition product of the organic peroxide contained in the toner, is less than 2000 ppm,
A dry non-magnetic toner, wherein the residual styrene monomer in the toner is less than 300 ppm.   The dry nonmagnetic toner according to claim 1, wherein the mode circularity is 0.990 or more.   The dry nonmagnetic toner according to claim 1, wherein the content of the carboxylic acid is less than 1000 ppm with respect to the toner mass.   The dry nonmagnetic toner according to claim 1 or 2, wherein the content of the carboxylic acid is less than 500 ppm with respect to the toner mass.   The DSC curve measured by a differential scanning calorimeter of the wax component has a maximum endothermic peak in the region of 40 to 110 ° C at the time of temperature rise, and is a dry method according to any one of claims 1 to 4. Non-magnetic toner. The dry nonmagnetic toner according to any one of claims 1 to 5 , wherein the organic peroxide has a 10-hour half-life temperature of 30 to 100 ° C. The toner particles are substantially separated from the aqueous medium after suspension polymerization and before acid treatment, by adding alkali to the aqueous medium and adjusting the pH of the aqueous medium to 8-14. dry non-magnetic toner according to any one of claims 1 to 6, characterized in that. 8. The dry nonmagnetic toner according to claim 7 , wherein the toner particles are separated from the aqueous medium after adjusting the pH of the aqueous medium to 10 to 12. A monomer composition containing a styrene monomer, a colorant, and a wax component is dispersed in an aqueous medium containing a dispersion stabilizer that is soluble in acid, granulated, and a polymerization initiator. This is a dry nonmagnetic toner production method in which inorganic fine powder is externally added to nonmagnetic toner particles obtained by suspension polymerization using an acid and dissolving and removing the resulting dispersion stabilizer on the particle surface with an acid. And
The toner has an inorganic fine powder on the surface of non-magnetic toner particles containing a styrene-based binder resin, a colorant, and a wax component,
The polymerization initiator is an organic peroxide, and the organic peroxide is t-butylperoxyneodecanoate, t-butylperoxypivalate, t-butylperoxy-2-ethylhexanoate , T-butylperoxyisobutyrate, t-butylperoxymaleic acid, t-butylperoxy-3,5,5-trimethylhexanoate, t-butylperoxylaurate, t-butylperoxy One or more selected from isopropyl monocarbonate and t-butylperoxy-2-ethylhexyl monocarbonate ,
The content of carboxylic acid, which is a decomposition product of the organic peroxide contained in the toner, is less than 2000 ppm,
A method for producing a dry non-magnetic toner, wherein the residual styrene monomer in the toner is less than 300 ppm. After suspension polymerization and before acid treatment, an alkali is added to the aqueous medium to adjust the pH of the aqueous medium to 8 to 14, and then the toner particles are substantially separated from the aqueous medium. The method for producing a dry nonmagnetic toner according to claim 9 . The method for producing a dry non-magnetic toner according to claim 10 , wherein the toner particles are separated from the aqueous medium after adjusting the pH of the aqueous medium to 10 to 12.

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