JP4035249B2 - Method for producing toner for developing electrostatic image - Google Patents

Description

【００４２】
【外２】

【００４３】
有機金属化合物は、重合性単量体１００重量部当り０．４５〜１３．５重量部、好ましくは０．５〜１０重量用いられる。
【００４４】
さらに、本発明者らは、単量体組成物に極性基を有する樹脂としてアニオン性の重合体であるポリエステル樹脂を添加して重合を行なうことにより、帯電速度のさらなる向上が可能となることを見出した。
【００４５】
ポリエステル樹脂は、カルボニル基が吸水サイトとなるため、吸水量の高い樹脂であり、さらに、立上がりの早い負帯電性を示す。さらに、極性樹脂である為、水系媒体中で粒子を形成し重合トナーを製造する場合、トナー表面に局在し、他の組成物を包み込む様に存在する。こうして得られたトナー粒子は、所謂コア／シェル構造をとり、安定した摩擦帯電能を発現する。
【００４６】
本発明に用いるポリエステル樹脂としては、５〜５０ｍｇＫＯＨ／ｇの酸価、好ましくは５〜３５ｍｇＫＯＨ／ｇ、より好ましくは５〜３０ｍｇＫＯＨ／ｇの酸価を有するものが良い結果をもたらすため好ましい。
【００４７】
本発明に使用されるポリエステル樹脂の酸価が５ｍｇＫＯＨ／ｇに満たない場合、トナー表面への局在化が不十分となり、良好な帯電の立上がりが得られず、この酸価が５０ｍｇＫＯＨ／ｇを超える場合は、重合性単量体への溶解が不十分になることから、良好な造粒性が得られなくなる。
【００４８】
本願発明において用いられるポリエステル樹脂は、全成分中４５〜５５モル％がアルコール成分であり、５５〜４５モル％が酸成分であることが好ましい。
【００４９】
アルコール成分としては、エチレングリコール、プロピレングリコール、１，３−ブタンジオール、１，４−ブタンジオール、２，３−ブタンジオール、ジエチレングリコール、トリエチレングリコール、１，５−ペンタンジオール、１，６−ヘキサンジオール、ネオペンチルグリコール、２−エチル−１，３−ヘキサンジオール、水素化ビスフェノールＡ、また下式で表わされるビスフェノール誘導体；
【００５０】
【外３】

〔式中、Ｒはエチレン又はプロピレン基であり、ｘ，ｙはそれぞれ１以上の整数であり、かつｘ＋ｙの平均値は２〜１０である。〕
【００５１】
また下式で示されるジオール；
【００５２】
【外４】

のジオールが挙げられる。
【００５３】
全酸成分中５０ｍｏｌ％以上を含む２価のカルボン酸としてはフタル酸、テレフタル酸、イソフタル酸、無水フタル酸の如きベンゼンジカルボン酸又はその無水物：こはく酸、アジビン酸、セバシン酸、アゼライン酸の如きアルキルジカルボン酸又はその無水物、またさらに炭素数６〜１８のアルキル基又はアルケニル基で置換されたこはく酸もしくはその無水物；フマル酸、マレイン酸、シトラコン酸、イタコン酸の如き不飽和ジカルボン酸又はその無水物等が挙げられる。
【００５４】
さらに、アルコール成分としてグリセリン、ペンタエリスリトール、ソルビット、ソルビタン、ノボラック型フェノール樹脂のオキシアルキレンエーテルの如き多価アルコールが挙げられ、酸成分としてトリメリット酸、ピロメリット酸、ベンゾフェノンテトラカルボン酸やその無水物の如き多価カルボン酸が挙げられる。
【００５５】
好ましいポリエステル樹脂のアルコール成分としては前記式で示されるビスフェノール誘導体であり、酸成分としては、フタル酸、テレフタル酸、イソフタル酸又はその無水物、こはく酸、ｎ−ドデセニルコハク酸、又はその無水物、フマル酸、マレイン酸、無水マレイン酸の如きジカルボン酸類が挙げられる。架橋成分としては、無水トリメリット酸、ベンゾフェノンテトラカルボン酸、ペンタエリスリトール、ノボラック型フェノール樹脂のオキシアルキレンエーテルが好ましいものとして挙げられる。
【００５６】
前記ポリエステル樹脂の添加量は、使用される重合性単量体の重量を基準にして、０．１〜１５重量％、好ましくは０．５〜１２重量％、より好ましくは１〜１０重量％が良い。ポリエステル樹脂の添加量が重合性単量体の重量を基準にして０．１重量％に満たない場合には、帯電速度の向上の効果が得られにくく、この添加量が重合性単量体の重量を基準にして１５重量％を超えた場合には、着色剤の分散不良を招くことから造粒性が不良となり易い。
【００５７】
さらに、本発明に用いられるポリエステル樹脂は、好ましくは５０００〜５００００、より好ましくは５０００〜３５０００の重量平均分子量（Ｍｗ）を有していることが良い。
【００５８】
ポリエステル樹脂の重量平均分子量が５０００に満たない場合には、低分子量のポリエステル樹脂がトナー表面に局在化しやすいため、得られるトナーの耐ブロッキング性が不良となりやすく、重量平均分子量が５００００を超える場合には、着色剤の分散性が低下し、造粒性が不良となりやすい。
【００５９】
さらに、本発明においては、重合性単量体組成物中に、前述の特定のポリエステル樹脂と組合わせて、他の極性重合体（極性基を有する樹脂）を添加して重合しても良い。本発明に使用できる他の極性重合体を以下に例示する。
【００６０】
カチオン性重合体としては、メタクリル酸ジメチルアミノエチル、メタクリル酸ジエチルアミノエチルの如き含窒素単量体の重合体もしくはこの含窒素単量体とスチレン単量体又は不飽和カルボン酸エステル単量体との共重合体が挙げられる。
【００６１】
アニオン性重合体としては、ポリエステル樹脂が最も好ましく、他にアクリロニトリルの如きニトリル系単量体；塩化ビニルの如き含ハロゲン系単量体；アクリル酸、メタクリル酸の如き不飽和カルボン酸単量体；不飽和二塩基酸単量体；不飽和二塩基酸無水物単量体；ニトロ系単量体の如き単量体の単独重合体及び共重合体もしくはそれらの単量体とスチレン系単量体との共重合体が挙げられる。
【００６２】
このような他の極性重合体は、重合性単量体の重量を基準にして、好ましくは０．１〜１５重量％、より好ましくは０．５〜１２重量％、更に好ましくは１〜１０重量％が良い。
【００６３】
本発明においては、定着性及び耐オフセット性を高めるためにワックスを含有させても良い。
【００６４】
本発明に用いられるワックスとして炭化水素系ワックスが挙げられる。例えば、アルキレンを高圧下でラジカル重合した低分子量アルキレンポリマー、低圧下でチーグラー触媒で重合した低分子量アルキレンポリマー、高分子量のアルキレンポリマーを熱分解して得られる低分子量アルキレンポリマー；一酸化炭素及び水素を含有する合成ガスからアーゲ法により得られる炭化水素の蒸留残分を水素添加して得られる低分子量ポリメチレンが挙げられる。これらの炭化水素ワックスのうち、特定の成分を抽出分別した炭化水素ワックスが特に適している。プレス発汗法、溶剤法、真空蒸留、分別結晶方式などの方法によって、ワックスから低分子量成分を除去したもの、ワックスから低分子量成分を抽出したものが好ましい。
【００６５】
さらに、他のワックスとして、マイクロクリスタリンワックス、カルナバワックス、サゾールワックス、パラフィンワックス、エステルワックス等が挙げられる。
【００６６】
ワックスはポリエチレン換算の数平均分子量（Ｍｎ）が５００〜１２００であり、重量平均分子量（Ｍｗ）が８００〜３６００のものが好ましい。分子量が上記範囲より小さくなると耐ブロッキング性、現像性に劣るようになり、上記範囲より分子量が大きくなると、良好な定着性、耐オフセット性が得にくくなる。
【００６７】
ワックスのＭｗ／Ｍｎは５．０以下が良く、より好ましくは３．０以下が良い。
【００６８】
ワックスは、重合性単量体１００重量部に対し３〜２０重量部、好ましくは５〜１５重量部用いるのが効果的である。
【００６９】
トナー粒子がコア／シェル構造をとっていることは、トナー粒子の断層面を調べることにより確認することができる。具体的には、常温硬化性のエポキシ樹脂中にトナー粒子を十分分散させた後、温度４０℃の雰囲気中で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た後、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、そのサンプルを透過型電子顕微鏡（ＴＥＭ）で測定することによりトナーの断層形態を確認することができる。後記の実施例で得られたトナー粒子は、コア／シェル構造をとっていることが確認された。
【００７０】
また本発明にかかるトナー粒子は、重量平均粒径で３〜１０μｍの粒径を有していることが好ましく、高画質化のためには４〜９μｍの粒径を有していることが好ましい。
【００７１】
本発明のトナー製造方法の一例を以下に示す。重合性単量体中に、着色剤，荷電制御剤，重合開始剤、特定のポリエステル樹脂及び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又は分散せしめた単量体組成物を、分散安定剤を含有するｐＨ４．５〜８．５の水相中に通常の撹拌機またはホモミキサー，ホモジナイザー等により分散せしめる。好ましくは単量体組成物からなる液滴が所望のトナー粒子のサイズを有するように撹拌速度・時間を調整し、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、且つ粒子の沈降が防止される程度の撹拌を行えば良い。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。また、重合反応後半に昇温しても良く、未反応の重合性単量体、副生成物等を除去するために反応後半、又は、反応終了後に一部水系媒体を留去しても良い。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。この方法においては、通常単量体系１００重量部に対して水３００〜３０００重量部を分散媒として使用するのが好ましい。
【００７２】
本発明の懸濁重合工程に用いる分散安定剤として、例えば無機系化合物としては、リン酸三カルシウム、ヒドロキシアパタイト、リン酸マグネシウム、リン酸アルミニウム、リン酸亜鉛、炭酸カルシウム、炭酸マグネシウム、水酸化カルシウム、水酸化マグネシウム、水酸化アルミニウム、メタケイ酸カルシウム、硫酸カルシウム、硫酸バリウム、ベントナイト、シリカ、アルミナ、磁性体、フェライトが挙げられる。有機系化合物としては、例えばポリビニルアルコール、ゼラチン、メチルセルロース、メチルヒドロキシプロピルセルロース、エチルセルロース、カルボキシメチルセルロースのナトリウム塩、デンプンが水相に分散させて使用される。これら分散安定剤は、重合性単量体１００重量部に対して０．２〜１０重量部を使用することが好ましい。
【００７３】
これら分散安定剤は、市販のものをそのまま用いても良いが、細かい均一な粒度を有す分散粒子を得るために、分散媒中にて高速撹拌下にて該無機化合物を生成されることも出来る。例えば、リン酸三カルシウムの場合、高速撹拌下において、リン酸ナトリウム水溶液と塩化カルシウム水溶液を混合することで懸濁重合法に好ましい分散安定剤を得ることが出来る。
【００７４】
本発明のトナーに用いられる重合性単量体は、少なくとも重合性ビニル系単量体を有しており、重合性ビニル系単量体としてはスチレン，ｏ（ｍ−、ｐ−）−メチルスチレン，ｍ（ｐ−）−エチルスチレンの如きスチレン系単量体；（メタ）アクリル酸メチル，（メタ）アクリル酸エチル，（メタ）アクリル酸プロピル，（メタ）アクリル酸ブチル，（メタ）アクリル酸オクチル，（メタ）アクリル酸ドデシル，（メタ）アクリル酸ステアリル，（メタ）アクリル酸ベヘニル，（メタ）アクリル酸２−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如き（メタ）アクリル酸エステル系単量体；ブタジエン，イソプレン，シクロヘキセン，（メタ）アクリロニトリル，アクリル酸アミドの如き単量体が好ましく用いられる。
【００７５】
本発明で懸濁重合する際に使用する重合開始剤としては、例えば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の如きアゾ系重合開始剤；ベンゾイルペルオキシド、メチルエチルケトンペルオキシド、ジイソプロピルペルオキシカーボネート、クメンヒドロペルオキシド、２，４−ジクロロベンゾイルペルオキシド、ラウロイルペルオキシドの如き過酸化物系重合開始剤が用いられる。
【００７６】
該重合開始剤の添加量は、目的とする重合度により変化するが一般的には重合性単量体に対し０．５〜２０重量％添加され用いられる。開始剤の種類は、重合方法により若干異なるが、十時間半減期温度を参考に、単独又は混合し利用される。
【００７７】
重合度を制御するための公知の架橋剤・連鎖移動剤・重合禁止剤等を更に添加し用いることも可能である。
【００７８】
本発明のトナーに用いられる着色剤は、黒色着色剤としてはカーボンブラック、磁性体、以下に示すイエロー／マゼンタ／シアン着色剤を用い黒色に調色されたものが利用される。
【００７９】
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が好適に用いられる。
【００８０】
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、１２２、１４６、１６６、１６９、１７７、１８４、１８５、２０２、２０６、２２０、２２１、２５４が特に好ましい。
【００８１】
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が特に好適に利用できる。
【００８２】
これらの着色剤は、単独又は混合し更には固溶体の状態で用いることができる。該着色剤の添加量は、重合性単量体１００重量部に対し１〜２０重量部添加して用いられる。
【００８３】
なお、着色剤の持つ重合阻害性や水相移行性に注意を払う必要があり、前記着色剤を好ましくは表面改質、たとえば重合阻害のない疎水化処理を施したほうが良い。特に染料系やカーボンブラックは、重合阻害性を有しているものが多いので使用の際に注意を要する。染料系を表面処理する好ましい方法としては、これら染料の存在下に重合性単量体をあらかじめ重合せしめる方法が挙げられ、得られた着色重合体を単量体系に添加する。また、カーボンブラックについては、上記染料と同様の処理のほか、カーボンブラックの表面官能基と反応する物質、たとえば、ポリオルガノシロキサンなどで処理を行っても良い。
【００８４】
本発明に使用できる外添剤としては、例えば、アルミナ，酸化チタン，シリカ，酸化ジルコニウム，酸化マグネシウムの如き酸化物の他に、炭化ケイ素，チッ化ケイ素，チッ化ホウ素，チッ化アルミニウム，炭酸マグネシウム，有機ケイ素化合物が挙げられる。
【００８５】
さらに、上記微粉体は疎水化処理されていることが、トナーの帯電量の温度や湿度の如き環境依存性を少なくするため及びトナー粒子表面からの遊離を防止するために好ましい。この疎水化処理剤としては、例えばシランカップリング剤，チタンカップリング剤，アルミニウムカップリング剤の如きカップリング剤、シリコーンオイル，フッ素系オイル，各種変性オイルの如きオイルが挙げられる。
【００８６】
これら公知の外添剤の中では、帯電安定性，現像性，流動性，保存性向上のため、シリカ，アルミナ，酸化チタンあるいはその複酸化物を選ぶことが好ましい。なかでも、シリカが、出発材料あるいは温度等の酸化条件により、ある程度任意に、一次粒子の合一をコントロールできる点でより好ましい。かかるシリカとしては硅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又はヒュームドシリカと称され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、表面及びシリカ微粉体の内部にあるシラノール基が少なく、また、Ｎａ₂ Ｏ，ＳＯ₃ ^2-等の製造残滓の少ない乾式シリカの方が好ましい。また乾式シリカにおいては、製造工程において例えば、塩化アルミニウム，塩化チタンの如き他の金属ハロゲン化合物を硅素ハロゲン化合物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りそれらも用いることができる。
【００８７】
外添剤の添加量は、トナー粒子１００重量部に対して、トナーの帯電量の安定化、かさ密度の安定化、高湿下での放置安定性を高めるために０．１〜３重量部添加することが好ましく、これら外添剤は複数種組合せて使用することができる。以下に、さらに別個に組合せて使用することが好ましい外添剤について述べる。
【００８８】
転写性および／またはクリーニング性向上のために一次粒径５０ｎｍ以上（好ましくは比表面積が５０ｍ² ／ｇ未満）の無機又は有機の球状に近い微粒子をさらに添加することも好ましい形態の一つである。例えば球状シリカ粒子，球状ポリメチルシルセスキオキサン粒子，球状樹脂粒子が好ましく用いられる。
【００８９】
更に他の添加剤、例えばテフロン粉末、ステアリン酸亜鉛粉末、ポリフッ化ビニリデン粉末の如き滑剤粉末；酸化セリウム粉末、炭化硅素粉末、チタン酸ストロンチウム粉末の如き研磨剤；例えば酸化チタン粉末、酸化アルミニウム粉末の如きケーキング防止剤、あるいは例えばカーボンブラック粉末、酸化亜鉛粉末、酸化スズ粉末の如き導電性付与剤、また、逆極性の有機微粒子及び無機微粒子を現像性向上剤として少量用いることもできる。
【００９０】
さらに本発明の製造方法によるトナーは、磁性材料を含有させ磁性トナーとしても使用しうる。この場合、磁性材料は着色剤の役割をかねることもできる。本発明において、磁性トナー中に含まれる磁性材料としては、マグネタイト、ヘマタイト、フェライトの如き酸化鉄；鉄、コバルト、ニッケルの如き金属或はこれらとアルミニウム、コバルト、銅、鉛、マグネシウム、スズ、亜鉛、アンチモン、ベリリウム、ビスマス、カドミウム、カルシウム、マンガン、セレン、チタン、タングステン、バナジウムの如き金属と合金及びその混合物が挙げられる。
【００９１】
これらの磁性体は平均粒子が２μｍ以下、好ましくは０．１〜０．５μｍのものが好ましい。トナー中に含有させる量としては重合性単量体１００重量部に対し２０〜２００重量部、特に好ましくは重合性単量体１００重量部に対し４０〜１５０重量部が良い。
【００９２】
また、１０ｋエルステッド印加での磁気特性が保磁力（Ｈｃ）２０〜３００エルステッド、飽和磁化（σｓ）５０〜２００ｅｍｕ／ｇ、残留磁化（σｒ）２〜２０ｅｍｕ／ｇのものが好ましい。
【００９３】
本発明の製造方法によるトナーは、一成分及び二成分系現像剤として、いずれの現像剤にも使用できる。
【００９４】
たとえば、一成分系現像剤として、磁性体をトナー中に含有せしめた磁性トナーの場合には、現像スリーブ内に内蔵せしめたマグネットを利用し、磁性トナーを搬送及び帯電せしめる方法がある。また、磁性体を含有しない非磁性トナーを用いる場合には、ブレード及びファーブラシを用い、現像スリーブにて強制的に摩擦帯電しスリーブ上にトナーを付着せしめることで搬送せしめる方法がある。
【００９５】
一方、一般的に利用されている二成分系現像剤として用いる場合には、本発明のトナーと共に、キャリアを用い現像剤として使用する。本発明に使用されるキャリアとしては特に限定されるものではないが、主として、鉄、銅、亜鉛、ニッケル、コバルト、マンガン、クロム元素からなる単独及び複合フェライトや、キャリアコア粒子を樹脂でコートしたものが用いられる。飽和磁化、電気抵抗を広範囲にコントロールできる点からキャリア形状も重要であり、たとえば球状、扁平、不定形などを選択し、更にキャリア表面状態の微細構造、たとえば表面凸凹性をもコントロールすることが好ましい。樹脂コートキャリアとしては、一般的には、上記無機酸化物を焼成、造粒することにより、あらかじめ、キャリアコア粒子を生成した後、樹脂にコーティングする方法が用いられているが、キャリアのトナーへの負荷を軽減する意味合いから、無機酸化物と樹脂を混練後、粉砕、分級して低密度分散キャリアを得る方法や、さらには、直接無機酸化物とモノマーとの混練物を水系媒体中にて懸濁重合せしめ真球状分散キャリアを得る重合キャリアを得る方法なども利用することが可能である。
【００９６】
キャリアコア粒子の表面を樹脂の如き被覆材で被覆する系は、特に好ましい。被覆する方法としては、被覆材を溶剤中に溶解もしくは懸濁せしめて塗布しキャリアに付着せしめる方法、単に粉体で混合する方法等、従来公知の方法がいずれも適用できる。
【００９７】
キャリア表面への被覆物質としてはトナー材料により異なるが、例えばポリテトラフルオロエチレン、モノクロロトリフルオロエチレン重合体、ポリフッ化ビニリデン、シリコーン樹脂、ポリエステル樹脂、ジターシャーリーブチルサリチル酸の金属化合物、スチレン系樹脂、アクリル系樹脂、ポリアシド、ポリビニルブチラール、ニグロシン、アミノアクリレート樹脂、塩基性染料及びそのレーキ物、シリカ微粉末、アルミナ微粉末を単独或は複数で用いるのが適当であるが、必ずしもこれに制約されない。
【００９８】
上記化合物の処理量は、一般には総量でキャリア１００重量部に対し０．１〜３０重量部、好ましくは０．５〜２０重量部である。
【００９９】
これらキャリアの平均粒径は１０〜１００μｍ、好ましくは２０〜５０μｍを有することが好ましい。
【０１００】
特に好ましい態様としては、Ｃｕ−Ｚｎ−Ｆｅの３元系のフェライトであり、その表面をフッ素系樹脂とスチレン系樹脂の如き樹脂の組み合わせ、例えばポリフッ化ビニリデンとスチレン−メチルメタクリレート樹脂；ポリテトラフルオロエチレンとスチレン−メチルメタクリレート樹脂；フッ素系共重合体とスチレン系共重合体；を９０：１０〜２０：８０、好ましくは７０：３０〜３０：７０の比率の混合物としたもので、０．０１〜５重量％、好ましくは０．１〜１重量％コーティングし、２５０メッシュパス、４００メッシュオンのキャリア粒子が７０重量％以上ある上記平均粒径を有するコートフェライトキャリアであるものが挙げられる。該フッ素系共重合体としてはフッ化ビニリデン−テトラフルオロエチレン共重合体（１０：９０〜９０：１０）が例示され、スチレン系共重合体としてはスチレン−アクリル酸２−エチルヘキシル（２０：８０〜８０：２０）、スチレン−アクリル酸２−エチルヘキシル−メタクリル酸メチル（２０〜６０：５〜３０：１０〜５０）が例示される。
【０１０１】
上記コートフェライトキャリアは粒径分布がシャープであり、本発明のトナーに対し好ましい摩擦帯電性が得られ、さらに電子写真特性を向上させる効果がある。
【０１０２】
本発明におけるトナーと混合して二成分現像剤を調製する場合、その混合比率は現像剤中のトナー濃度として、２重量％〜１５重量％、好ましくは４重量％〜１３重量％にすると通常良好な結果が得られる。トナー濃度が２重量％未満では画像濃度が低くなりやすく、１５重量％を超えるとカブリや機内飛散を増加せしめ、現像剤の耐用寿命が短くなりやすい。
【０１０３】
さらに、該キャリアの磁気特性は以下のものが良い。磁気的に飽和させた後の１０００エルステッドにおける磁化の強さ（σ₁₀₀₀）は３０乃至３００ｅｍｕ／ｃｍ³ であることが好ましい。さらに高画質化を達成するために、好ましくは１００乃至２５０ｅｍｕ／ｃｍ³ であることがよい。３００ｅｍｕ／ｃｍ³ より大きい場合には、高画質なトナー画像が得られにくくなる。３０ｅｍｕ／ｃｍ³ 未満であると、磁気的な拘束力が減少するためにキャリア付着を生じやすい。
【０１０４】
以下に本発明において使用する上記トナーの特性値に係る各測定法について述べる。
【０１０５】
（１）粒度分布測定：
測定装置としてはコールターカウンターＴＡ−ＩＩ型あるいはコールターマルチサイザー（コールター社製）等を用い、個数分布，体積分布を出力するインターフェイス（日科機製）及びＰＣ９８０１パーソナルコンピュータ（ＮＥＣ製）を接続し、電解液は１級塩化ナトリウムを用いて１％ＮａＣｌ水溶液を調製する。たとえば、ＩＳＯＴＯＮ Ｒ−ＩＩ（コールターサイエンテイフィックジャパン社製）が使用できる。測定法としては、前記電解水溶液１００〜１５０ｍｌ中に分散剤として界面活性剤（好ましくはアルキルベンゼンスルフォン酸塩）を０．１〜５ｍｌ加え、更に測定資料を２〜２０ｍｇ加える。試料を懸濁した電解液は超音波分散器で約１〜３分間分散処理を行い前記コールターカウンターＴＡ−ＩＩ型によりアパーチャーとして１００μｍアパーチャーを用いて、２μｍ以上のトナーの体積，個数を測定して体積分布と個数分布とを算出する。それから、体積分布から求めた体積基準の重量平均粒径（Ｄ４）、個数分布から求めた個数基準の長さ平均粒径（Ｄ１）を得る。
【０１０６】
尚、本発明においてはＤ４／Ｄ１も計算したが、この値が１に近い程粒度分布がシャープであるということを表す。
【０１０７】
（２）２μｍ以下の粒子数の測定：
測定装置としては、東亜医用電子製フロー式粒子像分析装置ＦＰＩＡ−１０００を用いる。ノニオン型界面活性剤０．１ｍｇを溶解している水１０ｍｌにトナー５ｍｇを分散して分散液を調製し、超音波（２０ｋＨｚ、５０Ｗ）を分散液に５分間照射し、フロー式粒子像分析装置で測定し、粒径０．６〜２．０μｍの粒子数の個数％を得る。
【０１０８】
（３）酸価の測定
本発明におけるポリエステルの酸価は以下の方法で求められる。
【０１０９】
試料２〜１０ｇを２００ｍｌの三角フラスコに秤量していれ、更にこの中にメタノール：トルエン＝３０：７０の混合溶媒約５０ｍｌを加えてトナーを溶解させる。溶解性が悪いようであれば少量のアセトンを加えてもよい。そして、０．１重量％ブロムチモールブルーとフェノールレッドの混合試薬を用い、予め標定された０．１Ｍ−水酸化カリウム／エタノール溶液で滴定し、水酸化カリウム／エタノール溶液の消費量から次の計算で酸価を求める。
【０１１０】
酸価（ｍｇＫＯＨ／ｇ）＝ＫＯＨ（ｍｌ）×ｆ×５６．１／試料重量（ｇ）
（上記式中ｆは、０．１Ｍ−水酸化カリウム／エタノール溶液のファクターである）
【０１１１】
本発明においては、上記の方法により行った２回の測定の平均を酸価とした。
【０１１２】
（４）ポリエステル重量平均分子量の測定
本発明においては、ゲルパーミエーションクロマトグラフィー（ＧＰＣ）により重量平均分子量を測定した。以下に詳細な測定法方を示す。
【０１１３】
４０℃のヒートチャンバ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（テトラハイドロフラン）を毎分１ｍｌの流速で流し、ＴＨＦ試料溶液を約１００μｌ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成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、たとえば、東ソー社製あるいは、昭和電工社製の分子量が１０２〜１０７程度のものを用い、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。検出器にはＲＩ（屈折率）検出器を用いる。カラムとしては、市販のポリスチレンジェルカラムを複数本組み合わせるのが良く、たとえば昭和電工社製のｓｈｏｄｅｘ ＧＰＣ ＫＦ−８０１，８０２，８０３，８０４，８０５，８０６，８０７，８００Ｐの組み合わせや、東ソー社製のＴＳＫｇｅｌ Ｇ１０００Ｈ（Ｈ ＸＬ），Ｇ２０００Ｈ（Ｈ ＸＬ），Ｇ３０００Ｈ（Ｈ ＸＬ），Ｇ４０００Ｈ（Ｈ ＸＬ），Ｇ５０００Ｈ（Ｈ ＸＬ）、Ｇ６０００Ｈ（Ｈ ＸＬ），Ｇ７０００Ｈ（Ｈ ＸＬ）ＴＳＫｇｕａｒｄｃｏｌｕｍｎの組み合わせが挙げられる。
【０１１４】
試料は以下のようにして作製する。
【０１１５】
試料をテトラヒドロフラン（ＴＨＦ）中に入れ、数時間放置した後、十分振とうしＴＨＦと良く混ぜ（試料の合一体がなくなるまで）、更に１２時間以上静置する。このときＴＨＦ中への放置時間が２４時間以上となるようにする。その後、サンプル処理フィルター（ポアサイズ０．４５〜０．５μｍ、たとえば、マイショリディスクＨ−２５−５ 東ソー社製、エキクロディスク２５ＣＲ ゲルマン サイエンス ジャパン社製などが利用できる）を通過させたものを、ＧＰＣの試料とする。試料濃度は、樹脂成分が０．５〜５ｍｇ／ｍｌとなるように調整する。
【０１１６】
【実施例】
以下、本発明を実施例により具体的に説明するが、これは、本発明をなんら限定するものではない。なお、以下の配合における部数は、特に説明のない場合は重量部である。
【０１１７】
（実施例１）
イオン交換水１０００重量部に、０．１Ｍ−Ｎａ₃ ＰＯ₄ 水溶液５００重量部及びＣａＣｌ₂ 添加後のｐＨが４．９になるように１Ｍ−ＨＣ１水溶液を適当量投入し、６０℃に加温した後、ＴＫ式ホモミキサー（特殊機化工業製）を用いて、１２０００ｒｐｍにて撹拌した。これに１．０Ｍ−ＣａＣｌ₂ 水溶液７４重量部を徐々に添加し、Ｃａ₃ （ＰＯ₄ ）₂ を含む水系媒体を得た。添加が終了した後、３０分間撹拌を続け、該水系媒体のｐＨを測定したところｐＨは４．９であった。
【０１１８】
一方、
スチレン １６０部
ｎ−ブチルアクリレート ４０部
酸成分としてテレフタル酸を用い、アルコール成分としてプロピレンオキサイド変性のビスフェノールＡを用いて製造した飽和ポリエステル樹脂 １０部
（Ｍｗ＝１万、酸価１０ｍｇＫＯＨ／ｇ）
カーボンブラック １６部
前述の化学式〔Ｉ〕で表されるジ−ｔｅｒｔ−ブチルサリチル酸アルミニウム化合物 ２部
ジ−ｔｅｒｔ−ブチルサリチル酸 ０．５部
ジビニルベンゼン ０．４部
パラフィンワックス（ｍ．ｐ．７０℃） ３０部
【０１１９】
上記処方を６０℃に加温にし、ＴＫ式ホモミキサー（特殊機化工業製）を用いて、１２０００ｒｐｍにて均一に溶解、分散した。これに、重合開始剤２，２′−アゾビス（２，４−ジメチルバレロニトリル）１０重量部を溶解し、重合性単量体組成物を調製した。
【０１２０】
前記水系媒体中に上記重合性単量体組成物を投入し、６０℃，Ｎ₂ 雰囲気下において、ＴＫ式ホモミキサーにて１００００ｒｐｍで１０分間撹拌し、重合性単量体組成物を造粒した。その後、パドル撹拌翼で撹拌しつつ、８０℃に昇温し、１０時間反応させた。重合反応終了後、減圧下で残存モノマーを留去し、冷却後、塩酸を加えリン酸カルシウムを溶解させた後、ろ過、水洗、乾燥をして、Ｄ１＝６．１μｍ、Ｄ４＝７．２μｍ、Ｄ４／Ｄ１＝１．１８である粒度分布の非常にシャープな重合体粒子を得た。その時の２μｍ以下の微小粒子は、９％であった。
【０１２１】
得られた粒子９８．５重量部に対して、ＢＥＴ法による比表面積が、２００ｍ² ／ｇである疎水性シリカを１．５重量部外添し、トナーＡを得た。このトナー５重量部に対し、アクリル樹脂コートされたフェライトキャリア９５重量部を混合し、現像剤とした。
【０１２２】
（実施例２，３及び比較例１，２）
実施例１において、Ｃａ₃ （ＰＯ₄ ）₂ を含む水系媒体のｐＨを、表１のごとく変更して重合体粒子を製造した。なお、比較例２は、１Ｍ−ＨＣｌ水溶液によるｐＨの調整を行わなかった。さらに実施例１と同様に疎水性シリカを外添し、トナーＢ〜Ｅを得、このトナー５重量部に対し、アクリル樹脂コートされたフェライトキャリア９５重量部を混合し、現像剤とした。
【０１２３】
（実施例４）
実施例１のジ−ｔｅｒｔ−ブチルサリチル酸アルミニウム化合物の代わりに２−ヒドロキシナフタレン−３−カルボン酸アルミニウムを、ジ−ｔｅｒｔ−ブチルサリチル酸の代わりに２−ヒドロキシナフタレン−３−カルボン酸を用いる以外は、実施例１と同様にして重合体粒子を得た。さらに実施例１と同様に疎水性シリカを外添し、トナーＦを得、このトナー５重量部に対し、アクリル樹脂コートされたフェライトキャリア９５重量部を混合し、現像剤とした。
【０１２４】
（実施例５，６及び比較例３，４）
実施例４において、Ｃａ₃ （ＰＯ₄ ）₂ を含む水系媒体のｐＨを、表１のごとく変更して重合体粒子を製造した。なお、比較例４は、１Ｍ−ＨＣｌ水溶液によるｐＨの調整を行わなかった。さらに実施例１と同様に疎水性シリカを外添し、トナーＧ〜Ｊを得、このトナー５重量部に対し、アクリル樹脂コートされたフェライトキャリア９５重量部を混合し、現像剤とした。
【０１２５】
（実施例７）
実施例１の着色剤を、カーボンブラックの代わりに銅フタロシアニン顔料を用いる以外は、実施例１と同様にして重合体粒子を得た。さらに実施例１と同様に疎水性シリカを外添し、トナーＫを得、このトナー５重量部に対し、アクリル樹脂コートされたフェライトキャリア９５重量部を混合し、現像剤とした。
【０１２６】
（実施例８，９及び比較例５，６）
実施例７において、Ｃａ₃ （ＰＯ₄ ）₂ を含む水系媒体のｐＨを表１のごとく変更して重合体粒子を製造した。なお、比較例６は、１Ｍ−ＨＣｌ水溶液によるｐＨの調整を行わなかった。さらに実施例１と同様に疎水性シリカを外添し、トナーＬ〜Ｏを得、このトナー５重量部に対し、アクリル樹脂コートされたフェライトキャリア９５重量部を混合し、現像剤とした。
【０１２７】
（実施例１０）
実施例１で用いたジ−ｔｅｒｔ−ブチルサリチル酸の代わりにナフトエ酸を用いる以外は、実施例１と同様にして重合体粒子を得た。さらに実施例１と同様に疎水性シリカを外添し、トナーＰを得、このトナー５重量部に対し、アクリル樹脂コートされたフェライトキャリア９５重量部を混合し、現像剤とした。
【０１２８】
（実施例１１，１２及び比較例７，８）
実施例１０において、Ｃａ₃ （ＰＯ₄ ）₂ を含む水系媒体のｐＨを、表１のごとく変更して重合体粒子を製造した。なお、比較例８は、１Ｍ−ＨＣｌ水溶液によるｐＨの調整を行わなかった。さらに実施例１と同様に疎水性シリカを外添し、トナーＱ〜Ｔを得、このトナー５重量部に対し、アクリル樹脂コートされたフェライトキャリア９５重量部を混合し、現像剤とした。
【０１２９】
上記の実施例及び比較例で製造されたトナーを用いて、以下の通り評価を行った評価結果を表１に示す。なお、各評価においては、フルカラー複写機ＣＬＣ７００（キヤノン製）を用いた。
【０１３０】
評価項目は、▲１▼転写効率、▲２▼常温常湿下での、初期と５０，０００枚耐久後の帯電量の変化、▲３▼その時のキャリア汚染、▲４▼低温低湿下及び高温高湿下での１０００枚複写時の帯電の立ち上がり特性である。
【０１３１】
▲１▼転写効率
転写効率は、常温常湿下（２３℃／６０％）において、感光体ドラム上に形成されたトナー像（画像濃度１．４）を透明な粘着テープで採取し、その画像濃度（Ｄ₁ ）をマクベス濃度計またはカラー反射濃度計（例えばＣｏｌｏｒ ｒｅｆｌｅｃｔｉｏｎ ｄｅｎｓｉｔｏｍｅｔｅｒ Ｘ−ＲＩＴＥ ４０４Ａ ｍａｎｕｆａｃｔｕｒｅｄ ｂｙ Ｘ−Ｒｉｔｅ Ｃｏ．）で測定する。次に再度トナー像を感光体ドラム上に形成し、トナー像を記録材へ転写し、記録材上に転写されたトナー像を透明な粘着テープで採取し、その画像濃度（Ｄ₂ ）を同様に測定する。得られた画像濃度（Ｄ₁ ）及び（Ｄ₂ ）から以下の如く算出する。
【０１３２】
転写効率（％）＝（Ｄ₂ ／Ｄ₁ ）×１００
【０１３３】
▲２▼帯電量変化
帯電量変化は、常温常湿下（２３℃／６０％）で５０，０００枚の複写テストを行い、初期及び５０，０００枚終了後の現像剤の帯電量を測定し、その差により評価した。帯電量の測定には図１に示す装置を用いた。
【０１３４】
摩擦帯電量を測定しようとする現像剤を５０〜１００ｍｌ容量のポリエチレン製のビンに入れ、５〜１０分間手で震盪した後、現像剤約０．５〜１．５ｇを、底に５００メッシュのスクリーン３のある金属製の測定容器２に入れ、金属性のフタ４をする。この時の測定容器２全体の重量を測りＷ₁ （ｇ）とする。次に、吸引機１（測定容器２と接する部分は少なくとも絶縁体）において、吸引口７から吸引し風量調節弁６を調整して真空計５の圧力を２５０ｍｍＡｑとする。この状態で充分、好ましくは２分間吸引を行いトナーを吸引除去する。この時の電位計９の電位をＶ（ボルト）とする。ここで８はコンデンサーであり容量をＣ（μＦ）とする。また、吸引後の測定容器全体の重量を測りＷ₂ （ｇ）とする。このトナーの帯電量（μＣ／ｇ）は下式の如く計算される。
【０１３５】
【外５】

【０１３６】
評価は、初期の帯電量と５０，０００枚終了時の帯電量の変化幅を、初期の帯電量を基準として「％」で表すことにより行った。なお、実用上Ｃ以上であることが好ましい。
Ａ：０〜１０％
Ｂ：１１〜２０％
Ｃ：２１〜３０％
Ｄ：３１〜４０％
Ｅ：４１〜５０％
Ｆ：５１％以上
【０１３７】
▲３▼キャリア汚染
キャリア汚染は、常温常湿下（２３℃／６０％）で５０，０００枚耐久後のキャリアの表面を電子顕微鏡で観察し、汚染の度合いを以下の基準で評価した。なお、実用上Ｂ以上であることが好ましい。
Ａ：汚染は発生していない。
Ｂ：汚染がわずかに発生している。
Ｃ：汚染が発生している。
Ｄ：汚染がひどく発生している。
【０１３８】
▲４▼帯電の立ち上がり特性
帯電の立ち上がり特性に関しては、低温低湿下（２３℃／５％）及び高温高湿下（３０℃／８０％）において、画出し試験を行い、耐久初期（１０００枚目）の複写画像におけるカブリを測定することにより評価した。
【０１３９】
紙上のカブリは、反射式濃度計（ＴＯＫＹＯ ＤＥＮＳＨＯＫＵ ＣＯ．，ＬＴＤ社製 ＲＥＦＬＥＣＴＯＭＥＴＥＲ ＯＤＥＬ ＴＣ−６ＤＳ）を用いて測定（プリント後の白地部反射濃度最悪値をＤｓ、プリント前の用紙の反射濃度平均値をＤｒとした時のＤｓ−Ｄｒを紙上カブリ量とした）した。カブリが３％以下では実質的に紙上カブリの無い良好な画像であり、５％を超えるとカブリのやや目立つ不鮮明な画像である。
Ａ：０〜３％
Ｂ：３〜５％
Ｃ：６〜９％
Ｄ：１０％以上
【０１４０】
【表１】

【０１４１】
【発明の効果】
上記の結果から、本発明の如く、有機金属化合物及び芳香族カルボン酸を含有する重合トナーにおいて、ｐＨ４．５〜８．５の水系媒体中で重合性単量体組成物の粒子を生成し、重合することにより、粒度分布が非常にシャープで、微小な粒子を生成することなしに、各環境下で良好な帯電特性が得られ、転写特性が良好なトナーが製造できることを見出したものである。
【図面の簡単な説明】
【図１】トナーの摩擦帯電性を測定する装置の概略的説明図である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing an electrostatic charge image developing toner used in electrophotography.
[0002]
[Prior art]
As an electrophotographic method, many methods are known as described in US Pat. No. 2,297,691, etc. Generally, a photoconductive substance is used and a photoconductor is obtained by various means. An electric latent image is formed thereon, developed with toner, and the toner image is transferred to a recording material such as paper as necessary, and then fixed by heating and / or pressure or solvent vapor. It is a method of obtaining a copy. Various methods have been conventionally proposed as a method of developing using toner or a method of fixing a toner image, and methods suitable for the respective image forming processes are employed. In recent years, high-speed copying and high image quality have been demanded for electrophotography.
[0003]
Conventionally, toners used for these purposes have generally been produced by melt-mixing a colorant composed of a dye / pigment in a thermoplastic resin and uniformly dispersing it, and then producing a toner having a desired particle size using a pulverizer and classifier. It was.
[0004]
While this method of manufacture can produce fairly good toners, it has certain limitations, i.e., limited choice of toner materials. For example, the resin colorant dispersion must be sufficiently brittle and capable of being finely pulverized with economically possible production equipment. However, if the resin colorant dispersion is made brittle to meet these requirements, the particle size range of the particles formed when the powder is actually pulverized at high speed is likely to be widened. The problem of being included arises. Further, such a highly brittle material is susceptible to further pulverization or powdering when used for development in a copying machine or the like. Also, with this method, it is difficult to completely disperse solid fine particles such as a colorant in the resin. Depending on the degree of dispersion, an increase in fog, a decrease in image density, color mixing, and transparency Care must be taken to disperse as it will cause defects. Further, exposure of the colorant to the fracture surface may cause a change in development characteristics.
[0005]
On the other hand, in order to overcome the problems of the toner due to the pulverization method, a toner production method by suspension polymerization is disclosed in Japanese Patent Publication Nos. 36-10231, 43-10799, and 51-14895. Proposed. In the suspension polymerization method, a monomer composition is obtained by uniformly dissolving or dispersing a polymerizable monomer, a colorant, a polymerization initiator and, if necessary, a crosslinking agent, a charge control agent, and other additives. The monomer composition is dispersed in a continuous phase containing a dispersion stabilizer, such as an aqueous phase, using a suitable stirrer, and simultaneously subjected to a polymerization reaction to obtain toner particles having a desired particle size.
[0006]
In this method, since the pulverization step is not included at all, the toner does not need to be brittle, a soft material can be used as the resin, and the colorant is not exposed to the surface of the particles, and uniform friction is obtained. There is an advantage that a toner having chargeability can be obtained. Further, since the particle size distribution of the obtained toner is relatively sharp, even if the classification step is omitted or classified, the toner can be obtained in a high yield. Further, since a large amount of a low softening point substance can be encapsulated in the toner as a release agent, there is an advantage that the obtained toner has excellent offset resistance.
[0007]
As an example using a polymerized toner, secondary toner obtained by fusing primary polymerized particles is used in JP-A-5-19662, and photoconductor exposure light is disclosed in JP-A-4-296766. In Japanese Patent Laid-Open No. 5-188637, a toner that defines volume average diameter, number average diameter, toner charge amount, toner projected image area, toner BET specific surface area, etc. is used. Although it has been disclosed to do so, it was not fully satisfactory.
[0008]
In addition, a toner having a spherical and smooth surface such as a polymerized toner has a problem that the contact point with the charging member is small, the charging property is lowered, and the charging property is significantly lowered under high humidity. Has occurred. In order to solve this problem, it is necessary to make the charging property better than that of the conventional toner.
[0009]
Conventionally, in order to retain the charge in the toner, it is possible to use the triboelectric chargeability of the resin that is a component of the toner. However, since the chargeability of the toner is small in this method, an image obtained by development is easily fogged. It tends to be unclear. Therefore, in order to impart desired triboelectric chargeability to the toner, a dye or pigment imparting chargeability, and further a charge control agent is added.
[0010]
Since the toner containing the charge control agent easily contaminates a toner carrier such as a developing sleeve, the triboelectric charge amount decreases with an increase in the number of copies, and the image density tends to decrease. Also, certain charge control agents are insufficient in triboelectric charge and are easily affected by temperature and humidity, and are therefore likely to cause image density fluctuations due to environmental fluctuations. In addition, since a certain type of charge control agent has poor dispersibility in the resin, a toner using the charge control agent tends to have a non-uniform frictional charge amount between toner particles and easily cause fogging. Also, certain charge control agents have poor storage stability, and the triboelectric charge amount tends to decrease during long-term storage.
[0011]
In the case of a polymerized toner, the charge control agent tends to have an adverse effect when granulated in an aqueous medium. For example, problems such as occurrence of poor dispersion of pigments and the like, and generation of fine particles due to dissolution of a part of the charge control agent are likely to occur. In particular, when very fine particles such as emulsified particles are produced, the toner performance is greatly impaired, such as contamination of the charging member and inhibition of the chargeability of the toner.
[0012]
Today, charge control agents known in the art include, as negative triboelectric charging properties, metal complexes of monoazo dyes, metal complexes of salicylic acid, naphthoic acid, dicarboxylic acids, copper phthalocyanine pigments, or resins containing acid components. Are known. Further, as the positive triboelectric charging property, a resin having a nigrosine dye, an azine dye, a triphenylmethane dye / pigment, a quaternary ammonium salt, or a quaternary ammonium salt in the side chain is known.
[0013]
Among these, various metal complexes have been proposed as negative charge control agents in JP-B-43-17955, JP-B-55-42752, JP-A-61-155464, JP-B-63-1994, and the like. ing. Although these certainly show good chargeability, it has not been considered sufficient when used in polymerized toners, and improvements have been desired.
[0014]
[Problems to be solved by the invention]
An object of the present invention is to propose a method for producing a toner for developing an electrostatic charge image that solves the above-mentioned problems.
[0015]
An object of the present invention is to propose a method for producing a toner for developing an electrostatic charge image that has good chargeability in each environment, can provide a high-quality image, and is free from contamination of a charging member or the like.
[0016]
An object of the present invention is to propose a method for producing a toner for developing an electrostatic image having good transfer characteristics.
[0017]
An object of the present invention is to propose a method for producing a toner for developing an electrostatic image having a very sharp particle size distribution and few fine particles.
[0018]
[Means for Solving the Problems]
  The present inventionSodium phosphate (Na ₃ PO ₄ ) After adding acid to the aqueous solution, calcium chloride (CaCl ₂ ) By adding aqueous solution, the pH is 4.5-8.5, Ca ₃ (PO ₄ ) ₂ An aqueous medium containingPolymerizability containing at least a polymerizable monomer containing a polymerizable vinyl monomer, a colorant, an organometallic compound, an aromatic carboxylic acid, a polyester resin having an acid value of 5 to 50 mgKOH / g, and a polymerization initiator Monomer compositionTheDispersing in an aqueous medium and producing particles of the polymerizable monomer composition in the aqueous medium; having a step of polymerizing the polymerizable vinyl monomer in the particles of the polymerizable monomer composition The present invention relates to a method for producing a toner for developing an electrostatic charge image.
[0019]
As a result of intensive studies, the present inventors have found that a polymerizable monomer composition containing a specific polyester resin, an organometallic compound and an aromatic carboxylic acid in an aqueous medium having a pH of 4.5 to 8.5. By producing and polymerizing particles, it is possible to produce a toner with excellent charge characteristics and excellent transfer characteristics in each environment without generating fine particles with a very sharp particle size distribution. I found.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
As a result of intensive studies, the inventors have concluded that the chargeability in each environment can be greatly improved by simultaneously containing an organometallic compound and an aromatic carboxylic acid as a charge control agent in the polymerized toner. Reached.
[0021]
In general, a toner using a metal compound of an organic acid used as a charge control agent may exhibit a relatively high chargeability, but a decrease in charge amount is observed under high humidity, and a decrease in charge rate under low humidity. Is seen.
[0022]
The cause of this is thought to be the adsorption and desorption of moisture near the metal, and the amount of water adsorbed to the metal compound increases under high humidity, which reduces the charge amount, while the amount of adsorbed water in the metal compound decreases under low humidity, causing resistance. It is considered that the charging speed decreases and the charging speed decreases.
[0023]
As a result of studies by the present inventors, it is possible to suppress a decrease in charge amount under high humidity and a decrease in charge rate under low humidity by including an aromatic carboxylic acid in addition to the organometallic compound in the polymerized toner. found.
[0024]
The reason for this is not clear, but it is thought that the adsorption of water to the metal compound is blocked because the coexisting aromatic carboxylic acid is bound to or exists in the vicinity of the metal compound in an attempt to stabilize electrostatically.
[0025]
Among aromatic carboxylic acids, when an carboxylic acid having a low negative charge density on the carboxyl group oxygen such as oxycarboxylic acid is used, a high charge amount can be obtained even under high humidity. In this regard, when the negative charge density on the carboxyl group oxygen is small, the electron density on the metal atom does not increase so much even when bonded to a metal, and the negative charging ability of the metal compound is considered to be high.
[0026]
Further, according to the study by the present inventors, the organic acid constituting the organometallic compound is preferably an aromatic oxycarboxylic acid, in particular, because a stable charge amount is obtained.
[0027]
However, by including an organometallic compound and an aromatic carboxylic acid in the polymerizable monomer composition, the chargeability as a toner is ensured, but when generating toner particles in an aqueous medium, In addition to toner particles having a desired particle size, a large number of fine particles of 2 μm or less are likely to be generated. If a developer containing such fine particles is used, the charging member and the like are contaminated, and charging failure occurs for a long period of use. It became clear that this could cause problems.
[0028]
In addition, the fine particles deteriorate the fluidity of the toner and cause a bad influence on the transfer characteristics.
[0029]
The present inventors solved this problem by controlling the pH of the aqueous medium. In other words, by generating particles of the polymerizable monomer composition in an aqueous medium having a pH of 4.5 to 8.5, the particle size distribution is very sharp, contaminating the charging member and the like, and causing the transfer characteristics to deteriorate. A toner having significantly improved chargeability in each environment could be obtained without generation of particles.
[0030]
The reason is not clear, but it is thought as follows. In the present invention, since granulation is performed in an aqueous medium having a pH of 4.5 to 8.5, elution of the organometallic compound and the aromatic carboxylic acid into the aqueous system is suppressed. When the organometallic compound or aromatic carboxylic acid is eluted in an aqueous system, the eluted organometallic compound or aromatic carboxylic acid functions as a surfactant, which causes generation of fine particles. However, in the toner manufacturing method of the present invention, since the elution of these is suppressed, it is considered that the generation of fine particles is also suppressed.
[0031]
The pH of the aqueous medium is preferably 4.5 to 8.5, more preferably 4.5 to 7.0, and even more preferably 4.5 to 6.0.
[0032]
When the pH is 4.5 or more, the particles in the aqueous medium can exist stably, so that aggregation and coalescence of the particles can be suppressed.
[0033]
If the pH exceeds 8.5, a very sharp particle size distribution cannot be obtained, and it becomes difficult to suppress the generation of fine particles.
[0034]
As a method of adjusting the pH, a method of adjusting by adding an acid such as hydrochloric acid, sulfuric acid, nitric acid or phosphoric acid immediately before granulating the polymer particles, or when generating a dispersion stabilizer in a dispersion medium, A method of obtaining an intended pH by adding an acid to the raw material before production is used.
[0035]
For example, when tricalcium phosphate is used as a dispersion stabilizer, an appropriate amount of acid is added before mixing the aqueous calcium chloride solution with the aqueous sodium phosphate solution, and then the desired pH is adjusted by adding the aqueous calcium chloride solution. The method obtained is preferably used.
[0036]
As the aromatic carboxylic acid used in the present invention, benzoic acid, naphthoic acid and derivatives thereof can be used, and aromatic oxycarboxylic acid is particularly preferable. For example, salicylic acid, alkylsalicylic acid having an alkyl group having 5 or less carbon atoms, and 3,5-dialkylsalicylic acid, and 3,5-dialkylsalicylic acid is particularly preferred as the aromatic oxycarboxylic acid. As the alkyl group, a t-butyl group is most preferably used.
[0037]
Further, as another compound, 2-hydroxy-3-naphthoic acid, alkyl-2-hydroxy-3-naphthoic acid having 5 or less carbon atoms, 5,6,7,8-tetrahalogen-2-hydroxy-3- Naphthoic acid is used.
[0038]
The aromatic carboxylic acid is used in an amount of 0.01 to 1.5 parts by weight per 100 parts by weight of the polymerizable monomer. Preferably it is 0.02-1.3 weight part, More preferably, 0.05-1.1 weight part is used.
[0039]
As the organometallic compound, the above aromatic oxycarboxylic acid compounds of aluminum, zinc, chromium, cobalt, nickel, copper, and iron are preferably used.
[0040]
Specific examples of the metal compound include the following compounds.
[0041]
[Outside 1]

[0042]
[Outside 2]

[0043]
The organometallic compound is used in an amount of 0.45 to 13.5 parts by weight, preferably 0.5 to 10 parts by weight, per 100 parts by weight of the polymerizable monomer.
[0044]
Furthermore, the present inventors have found that the charging rate can be further improved by adding a polyester resin, which is an anionic polymer, as a resin having a polar group to the monomer composition. I found it.
[0045]
The polyester resin is a resin having a high water absorption amount because the carbonyl group serves as a water absorption site, and further exhibits a negative charging property with a quick rise. Furthermore, since it is a polar resin, when a polymerized toner is produced by forming particles in an aqueous medium, it exists on the surface of the toner and wraps around other compositions. The toner particles thus obtained have a so-called core / shell structure and exhibit a stable triboelectric charging ability.
[0046]
As the polyester resin used in the present invention, one having an acid value of 5 to 50 mgKOH / g, preferably 5 to 35 mgKOH / g, more preferably 5 to 30 mgKOH / g is preferable because it gives good results.
[0047]
When the acid value of the polyester resin used in the present invention is less than 5 mgKOH / g, localization on the toner surface becomes insufficient, and a good rise of charge cannot be obtained, and this acid value is less than 50 mgKOH / g. When exceeding, since the melt | dissolution to a polymerizable monomer will become inadequate, favorable granulation property will no longer be obtained.
[0048]
In the polyester resin used in the present invention, 45 to 55 mol% of all components are preferably alcohol components, and 55 to 45 mol% are preferably acid components.
[0049]
As alcohol components, ethylene glycol, propylene glycol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, diethylene glycol, triethylene glycol, 1,5-pentanediol, 1,6-hexane Diol, neopentyl glycol, 2-ethyl-1,3-hexanediol, hydrogenated bisphenol A, and bisphenol derivatives represented by the following formula:
[0050]
[Outside 3]

[Wherein, R is an ethylene or propylene group, x and y are each an integer of 1 or more, and the average value of x + y is 2 to 10. ]
[0051]
A diol represented by the following formula;
[0052]
[Outside 4]

These diols are mentioned.
[0053]
Divalent carboxylic acids containing 50 mol% or more of the total acid component include benzene dicarboxylic acids such as phthalic acid, terephthalic acid, isophthalic acid, and phthalic anhydride, or anhydrides thereof: succinic acid, adivic acid, sebacic acid, azelaic acid Alkyl dicarboxylic acids or anhydrides thereof, and succinic acid or anhydrides further substituted with alkyl or alkenyl groups having 6 to 18 carbon atoms; unsaturated dicarboxylic acids such as fumaric acid, maleic acid, citraconic acid, itaconic acid Or the anhydride etc. are mentioned.
[0054]
In addition, polyhydric alcohols such as glycerin, pentaerythritol, sorbit, sorbitan, and oxyalkylene ethers of novolak type phenolic resins can be cited as the alcohol component, and trimellitic acid, pyromellitic acid, benzophenone tetracarboxylic acid and its anhydride as the acid component. And polyvalent carboxylic acids such as
[0055]
The alcohol component of the preferred polyester resin is a bisphenol derivative represented by the above formula, and the acid component is phthalic acid, terephthalic acid, isophthalic acid or its anhydride, succinic acid, n-dodecenyl succinic acid, or its anhydride, fumaric acid. Examples thereof include dicarboxylic acids such as acid, maleic acid, and maleic anhydride. Preferred crosslinking components include trimellitic anhydride, benzophenone tetracarboxylic acid, pentaerythritol, and oxyalkylene ethers of novolac type phenol resins.
[0056]
The addition amount of the polyester resin is 0.1 to 15% by weight, preferably 0.5 to 12% by weight, more preferably 1 to 10% by weight, based on the weight of the polymerizable monomer used. good. When the addition amount of the polyester resin is less than 0.1% by weight based on the weight of the polymerizable monomer, it is difficult to obtain the effect of improving the charging rate. If it exceeds 15% by weight based on the weight, the colorant tends to be poor because it causes poor dispersion of the colorant.
[0057]
Furthermore, the polyester resin used in the present invention preferably has a weight average molecular weight (Mw) of 5,000 to 50,000, more preferably 5,000 to 35,000.
[0058]
When the weight average molecular weight of the polyester resin is less than 5,000, the low molecular weight polyester resin is likely to be localized on the toner surface, so that the resulting toner tends to have poor blocking resistance, and the weight average molecular weight exceeds 50,000. In this case, the dispersibility of the colorant is lowered and the granulation property tends to be poor.
[0059]
Furthermore, in this invention, you may superpose | polymerize by adding another polar polymer (resin which has a polar group) in combination with the above-mentioned specific polyester resin in a polymerizable monomer composition. Other polar polymers that can be used in the present invention are exemplified below.
[0060]
Examples of the cationic polymer include a polymer of a nitrogen-containing monomer such as dimethylaminoethyl methacrylate and diethylaminoethyl methacrylate, or a combination of this nitrogen-containing monomer and a styrene monomer or an unsaturated carboxylic acid ester monomer. A copolymer is mentioned.
[0061]
As the anionic polymer, a polyester resin is most preferable, and other nitrile monomers such as acrylonitrile; halogen-containing monomers such as vinyl chloride; unsaturated carboxylic acid monomers such as acrylic acid and methacrylic acid; Unsaturated dibasic acid monomers; unsaturated dibasic acid anhydride monomers; homopolymers and copolymers of monomers such as nitro monomers or their monomers and styrene monomers And a copolymer.
[0062]
Such other polar polymer is preferably 0.1 to 15% by weight, more preferably 0.5 to 12% by weight, still more preferably 1 to 10% by weight, based on the weight of the polymerizable monomer. % Is good.
[0063]
In the present invention, a wax may be contained in order to improve the fixing property and the offset resistance.
[0064]
Examples of the wax used in the present invention include hydrocarbon waxes. For example, low molecular weight alkylene polymer obtained by radical polymerization of alkylene under high pressure, low molecular weight alkylene polymer polymerized by Ziegler catalyst under low pressure, low molecular weight alkylene polymer obtained by thermally decomposing high molecular weight alkylene polymer; carbon monoxide and hydrogen And low molecular weight polymethylene obtained by hydrogenating the distillation residue of hydrocarbons obtained from the synthesis gas containing Of these hydrocarbon waxes, hydrocarbon waxes obtained by extracting and fractionating specific components are particularly suitable. Those obtained by removing low molecular weight components from wax and those obtained by extracting low molecular weight components from wax by a method such as press sweating, solvent method, vacuum distillation, fractional crystallization, etc. are preferred.
[0065]
Further, examples of other waxes include microcrystalline wax, carnauba wax, sazol wax, paraffin wax, and ester wax.
[0066]
The wax preferably has a polyethylene-equivalent number average molecular weight (Mn) of 500 to 1200 and a weight average molecular weight (Mw) of 800 to 3600. When the molecular weight is smaller than the above range, the blocking resistance and developability are inferior, and when the molecular weight is larger than the above range, good fixability and offset resistance are difficult to obtain.
[0067]
The Mw / Mn of the wax is preferably 5.0 or less, more preferably 3.0 or less.
[0068]
It is effective to use 3 to 20 parts by weight, preferably 5 to 15 parts by weight of the wax with respect to 100 parts by weight of the polymerizable monomer.
[0069]
Whether the toner particles have a core / shell structure can be confirmed by examining the tomographic plane of the toner particles. Specifically, after sufficiently dispersing the toner particles in a room temperature curable epoxy resin, the cured product obtained by curing in an atmosphere at a temperature of 40 ° C. for 2 days is ruthenium tetroxide and, if necessary, osmium tetroxide. After the dye is dyed together, a sliced sample is cut out using a microtome equipped with diamond teeth, and the tomographic form of the toner can be confirmed by measuring the sample with a transmission electron microscope (TEM). It was confirmed that the toner particles obtained in Examples described later have a core / shell structure.
[0070]
The toner particles according to the present invention preferably have a weight average particle diameter of 3 to 10 μm, and preferably have a particle diameter of 4 to 9 μm for high image quality. .
[0071]
An example of the toner manufacturing method of the present invention is shown below. A monomer composition in which a colorant, a charge control agent, a polymerization initiator, a specific polyester resin, and other additives are added to the polymerizable monomer and uniformly dissolved or dispersed by a homogenizer, an ultrasonic disperser, or the like. The product is dispersed in an aqueous phase containing a dispersion stabilizer and having a pH of 4.5 to 8.5 using an ordinary stirrer, homomixer, homogenizer or the like. Preferably, granulation is performed by adjusting the stirring speed and time so that droplets of the monomer composition have a desired toner particle size. Thereafter, stirring may be performed to such an extent that the particle state is maintained and the sedimentation of the particles is prevented by the action of the dispersion stabilizer. Polymerization is carried out at a polymerization temperature of 40 ° C. or higher, generally 50 to 90 ° C. Further, the temperature may be raised in the latter half of the polymerization reaction, and a part of the aqueous medium may be distilled off in the latter half of the reaction in order to remove unreacted polymerizable monomers, by-products or the like. . After completion of the reaction, the produced toner particles are recovered by washing and filtration and dried. In this method, it is usually preferable to use 300 to 3000 parts by weight of water as a dispersion medium with respect to 100 parts by weight of the monomer system.
[0072]
Examples of the dispersion stabilizer used in the suspension polymerization process of the present invention include, for example, tricalcium phosphate, hydroxyapatite, magnesium phosphate, aluminum phosphate, zinc phosphate, calcium carbonate, magnesium carbonate, calcium hydroxide. , Magnesium hydroxide, aluminum hydroxide, calcium metasilicate, calcium sulfate, barium sulfate, bentonite, silica, alumina, magnetic substance, and ferrite. As the organic compound, for example, polyvinyl alcohol, gelatin, methyl cellulose, methyl hydroxypropyl cellulose, ethyl cellulose, sodium salt of carboxymethyl cellulose, and starch are used dispersed in an aqueous phase. These dispersion stabilizers are preferably used in an amount of 0.2 to 10 parts by weight based on 100 parts by weight of the polymerizable monomer.
[0073]
Commercially available dispersion stabilizers may be used as they are, but in order to obtain dispersed particles having a fine and uniform particle size, the inorganic compound may be produced in a dispersion medium under high-speed stirring. I can do it. For example, in the case of tricalcium phosphate, a dispersion stabilizer preferable for the suspension polymerization method can be obtained by mixing an aqueous sodium phosphate solution and an aqueous calcium chloride solution under high-speed stirring.
[0074]
The polymerizable monomer used in the toner of the present invention has at least a polymerizable vinyl monomer, and examples of the polymerizable vinyl monomer include styrene, o (m-, p-)-methylstyrene. , Styrene-based monomers such as m (p-)-ethylstyrene; methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, (meth) acrylic acid Octyl, dodecyl (meth) acrylate, stearyl (meth) acrylate, behenyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate (Meth) acrylic acid ester monomers; butadiene, isoprene, cyclohexene, (meth) acrylonitrile, acrylic acid Such monomers are preferably used.
[0075]
Examples of the polymerization initiator used for suspension polymerization in the present invention include 2,2′-azobis- (2,4-dimethylvaleronitrile), 2,2′-azobisisobutyronitrile, 1,1. Azo polymerization initiators such as' -azobis (cyclohexane-1-carbonitrile), 2,2'-azobis-4-methoxy-2,4-dimethylvaleronitrile, azobisisobutyronitrile; benzoyl peroxide, methyl ethyl ketone peroxide, Peroxide polymerization initiators such as diisopropyl peroxycarbonate, cumene hydroperoxide, 2,4-dichlorobenzoyl peroxide, lauroyl peroxide are used.
[0076]
The addition amount of the polymerization initiator varies depending on the desired degree of polymerization, but generally 0.5 to 20% by weight is added to the polymerizable monomer. The kind of the initiator is slightly different depending on the polymerization method, but can be used alone or mixed with reference to the 10-hour half-life temperature.
[0077]
A known crosslinking agent, chain transfer agent, polymerization inhibitor and the like for controlling the degree of polymerization can be further added and used.
[0078]
As the colorant used in the toner of the present invention, as a black colorant, carbon black, a magnetic material, and a color tone adjusted to black using a yellow / magenta / cyan colorant shown below are used.
[0079]
As the yellow colorant, compounds typified by condensed azo compounds, isoindolinone compounds, anthraquinone compounds, azo metal complexes, methine compounds, and allylamide compounds 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 are preferably used.
[0080]
As the magenta colorant, condensed azo compounds, diketopyrrolopyrrole compounds, anthraquinones, quinacridone compounds, basic dye lake compounds, naphthol compounds, benzimidazolone compounds, thioindigo compounds, and perylene compounds are used. Specifically, C.I. I. Pigment Red 2, 3, 5, 6, 7, 23, 48: 2, 48: 3, 48: 4, 57: 1, 81: 1, 122, 146, 166, 169, 177, 184, 185, 202, 206, 220, 221, 254 are particularly preferred.
[0081]
As the cyan colorant, copper phthalocyanine compounds and derivatives thereof, anthraquinone compounds, basic dye lake compounds can be used. Specifically, C.I. I. Pigment Blue 1, 7, 15, 15: 1, 15: 2, 15: 3, 15: 4, 60, 62, and 66 can be particularly preferably used.
[0082]
These colorants can be used alone or in combination and further in the form of a solid solution. The colorant is added in an amount of 1 to 20 parts by weight based on 100 parts by weight of the polymerizable monomer.
[0083]
It is necessary to pay attention to the polymerization inhibitory property and water phase migration property of the colorant, and the colorant is preferably subjected to surface modification, for example, a hydrophobic treatment without polymerization inhibition. In particular, dyes and carbon blacks have a polymerization inhibition property, so care must be taken when using them. A preferable method for surface-treating the dye system includes a method of polymerizing a polymerizable monomer in the presence of these dyes in advance, and the obtained colored polymer is added to the monomer system. Carbon black may be treated with a substance that reacts with the surface functional group of carbon black, such as polyorganosiloxane, in addition to the same treatment as the above dye.
[0084]
Examples of the external additive that can be used in the present invention include oxides such as alumina, titanium oxide, silica, zirconium oxide, and magnesium oxide, as well as silicon carbide, silicon nitride, boron nitride, aluminum nitride, and magnesium carbonate. , Organosilicon compounds.
[0085]
Further, it is preferable that the fine powder is subjected to a hydrophobization treatment in order to reduce the dependency of the toner charge amount on the environment such as temperature and humidity, and to prevent the toner particles from being separated from the surface. Examples of the hydrophobizing agent include coupling agents such as silane coupling agents, titanium coupling agents, and aluminum coupling agents, and oils such as silicone oils, fluorine oils, and various modified oils.
[0086]
Among these known external additives, it is preferable to select silica, alumina, titanium oxide or a double oxide thereof in order to improve charging stability, developability, fluidity and storage stability. Among these, silica is more preferable in that the coalescence of primary particles can be controlled arbitrarily to some extent depending on the starting material or oxidation conditions such as temperature. As such silica, both a so-called dry process produced by vapor phase oxidation of silicon halide or alkoxide, or a so-called wet silica produced from alkoxide, water glass, etc. can be used. However, there are few silanol groups on the surface and in the silica fine powder, and Na₂ O, SO_Three ^2-For example, dry silica with less production residue is preferred. In dry silica, it is also possible to obtain composite fine powders 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. They can also be used.
[0087]
The amount of the external additive is 0.1 to 3 parts by weight with respect to 100 parts by weight of the toner particles in order to stabilize the charge amount of the toner, stabilize the bulk density, and increase the stability when left under high humidity. It is preferable to add these external additives, and a plurality of these external additives can be used in combination. In the following, external additives that are preferably used in combination separately will be described.
[0088]
Primary particle size of 50 nm or more (preferably a specific surface area of 50 m for improving transferability and / or cleaning properties² It is also one of preferred modes to add inorganic or organic fine particles close to spherical shape (less than / g). For example, spherical silica particles, spherical polymethylsilsesquioxane particles, and spherical resin particles are preferably used.
[0089]
Still other additives such as lubricant powders such as Teflon powder, zinc stearate powder and polyvinylidene fluoride powder; abrasives such as cerium oxide powder, silicon carbide powder and strontium titanate powder; for example titanium oxide powder and aluminum oxide powder A small amount of such an anti-caking agent, or a conductivity imparting agent such as carbon black powder, zinc oxide powder or tin oxide powder, or organic fine particles and inorganic fine particles of reverse polarity can be used in small amounts.
[0090]
Furthermore, the toner according to the production method of the present invention can be used as a magnetic toner containing a magnetic material. In this case, the magnetic material can also serve as a colorant. In the present invention, the magnetic material contained in the magnetic toner includes iron oxides such as magnetite, hematite and ferrite; metals such as iron, cobalt and nickel or these and aluminum, cobalt, copper, lead, magnesium, tin and zinc. , Antimony, beryllium, bismuth, cadmium, calcium, manganese, selenium, titanium, tungsten, vanadium, alloys and mixtures thereof.
[0091]
These magnetic materials preferably have an average particle size of 2 μm or less, preferably 0.1 to 0.5 μm. The amount contained in the toner is 20 to 200 parts by weight, particularly preferably 40 to 150 parts by weight, based on 100 parts by weight of the polymerizable monomer.
[0092]
Further, it is preferable that the magnetic properties when applied with 10 k Oersted are those having a coercive force (Hc) of 20 to 300 Oersted, saturation magnetization (σs) of 50 to 200 emu / g, and residual magnetization (σr) of 2 to 20 emu / g.
[0093]
The toner according to the production method of the present invention can be used in any developer as a one-component or two-component developer.
[0094]
For example, in the case of a magnetic toner in which a magnetic material is contained in the toner as a one-component developer, there is a method of transporting and charging the magnetic toner using a magnet built in the developing sleeve. When non-magnetic toner containing no magnetic material is used, there is a method in which a blade and a fur brush are used to forcibly frictionally charge with a developing sleeve, and the toner is adhered to the sleeve and conveyed.
[0095]
On the other hand, when used as a two-component developer that is generally used, a carrier is used as a developer together with the toner of the present invention. The carrier used in the present invention is not particularly limited, but mainly single and composite ferrites composed of iron, copper, zinc, nickel, cobalt, manganese, and chromium elements, and carrier core particles are coated with a resin. Things are used. The carrier shape is also important from the viewpoint that the saturation magnetization and electric resistance can be controlled in a wide range. For example, it is preferable to select a spherical shape, a flat shape, an indeterminate shape, etc., and also to control the fine structure of the carrier surface state, for example, the surface unevenness. . As a resin-coated carrier, generally, a method is used in which carrier core particles are generated in advance by baking and granulating the inorganic oxide, and then coated on the resin. In order to reduce the load of the inorganic oxide, a method of obtaining a low-density dispersion carrier by kneading and classifying the inorganic oxide and the resin, and further, a kneaded product of the inorganic oxide and the monomer directly in an aqueous medium. A method for obtaining a polymerized carrier for obtaining a true spherical dispersion carrier by suspension polymerization can also be used.
[0096]
A system in which the surface of the carrier core particles is coated with a coating material such as a resin is particularly preferable. As a method for coating, any of conventionally known methods such as a method in which a coating material is dissolved or suspended in a solvent and applied and adhered to a carrier, or a method of simply mixing with a powder can be applied.
[0097]
The coating material on the carrier surface varies depending on the toner material. For example, polytetrafluoroethylene, monochlorotrifluoroethylene polymer, polyvinylidene fluoride, silicone resin, polyester resin, metal compound of ditertiary butylsalicylic acid, styrene resin, acrylic It is appropriate to use one or more of a resin, polyacid, polyvinyl butyral, nigrosine, aminoacrylate resin, basic dye and its lake, silica fine powder, and alumina fine powder, but it is not necessarily limited thereto.
[0098]
The treatment amount of the above compound is generally 0.1 to 30 parts by weight, preferably 0.5 to 20 parts by weight with respect to 100 parts by weight of the carrier as a total amount.
[0099]
The average particle size of these carriers is 10 to 100 μm, preferably 20 to 50 μm.
[0100]
A particularly preferred embodiment is a ternary ferrite of Cu—Zn—Fe, the surface of which is a combination of a resin such as a fluorine resin and a styrene resin, for example, polyvinylidene fluoride and a styrene-methyl methacrylate resin; A mixture of ethylene and styrene-methyl methacrylate resin; fluorine copolymer and styrene copolymer; in a ratio of 90:10 to 20:80, preferably 70:30 to 30:70, 0.01 The coated ferrite carrier having the above average particle diameter of ˜5% by weight, preferably 0.1 to 1% by weight, coated with 250 mesh pass and 400 mesh on carrier particles of 70% by weight or more. Examples of the fluorine-based copolymer include vinylidene fluoride-tetrafluoroethylene copolymer (10:90 to 90:10), and examples of the styrene-based copolymer include styrene-2-ethylhexyl acrylate (20:80 to 80:20), styrene-2-ethylhexyl acrylate-methyl methacrylate (20-60: 5-30: 10-50).
[0101]
The coated ferrite carrier has a sharp particle size distribution, provides a preferable triboelectric chargeability for the toner of the present invention, and has an effect of improving electrophotographic characteristics.
[0102]
When a two-component developer is prepared by mixing with the toner in the present invention, the mixing ratio is usually good when the toner concentration in the developer is 2 to 15% by weight, preferably 4 to 13% by weight. Results. If the toner concentration is less than 2% by weight, the image density tends to be low, and if it exceeds 15% by weight, fogging and in-machine scattering increase, and the useful life of the developer tends to be shortened.
[0103]
Further, the magnetic properties of the carrier are preferably as follows. Magnetization strength at 1000 oersted after magnetic saturation (σ₁₀₀₀) Is 30 to 300 emu / cm^Three It is preferable that In order to achieve higher image quality, preferably 100 to 250 emu / cm^Three It is good that it is. 300 emu / cm^Three If it is larger, it becomes difficult to obtain a high-quality toner image. 30 emu / cm^Three If it is less than this, the magnetic binding force is reduced, and carrier adhesion is likely to occur.
[0104]
Hereinafter, each measuring method related to the characteristic value of the toner used in the present invention will be described.
[0105]
(1) Particle size distribution measurement:
As a measuring device, a Coulter Counter TA-II type or Coulter Multisizer (manufactured by Coulter Co., Ltd.) is used, and an interface (manufactured by Nikkiki) that outputs number distribution and volume distribution and a PC9801 personal computer (manufactured by NEC) are connected to perform electrolysis. Prepare 1% NaCl aqueous solution using primary sodium chloride. For example, ISOTON R-II (manufactured by Coulter Scientific Japan) can be used. As a measurement method, 0.1 to 5 ml of a surfactant (preferably alkylbenzene sulfonate) is added as a dispersant to 100 to 150 ml of the electrolytic aqueous solution, and 2 to 20 mg of measurement data is further added. The electrolyte in which the sample is suspended is dispersed for about 1 to 3 minutes with an ultrasonic disperser, and the volume and number of toners of 2 μm or more are measured using the Coulter Counter TA-II with a 100 μm aperture as an aperture. Volume distribution and number distribution are calculated. Then, a volume-based weight average particle diameter (D4) obtained from the volume distribution and a number-based length average particle diameter (D1) obtained from the number distribution are obtained.
[0106]
In the present invention, D4 / D1 was also calculated. The closer this value is to 1, the sharper the particle size distribution is.
[0107]
(2) Measurement of the number of particles of 2 μm or less:
As a measuring device, Toa Medical Electronics' flow type particle image analyzer FPIA-1000 is used. A flow type particle image analyzer is prepared by dispersing 5 mg of toner in 10 ml of water in which 0.1 mg of a nonionic surfactant is dissolved to prepare a dispersion, and irradiating the dispersion with ultrasonic waves (20 kHz, 50 W) for 5 minutes. To obtain the number% of the number of particles having a particle size of 0.6 to 2.0 μm.
[0108]
(3) Measurement of acid value
The acid value of the polyester in the present invention is determined by the following method.
[0109]
Samples 2 to 10 g are weighed into a 200 ml Erlenmeyer flask, and about 50 ml of a mixed solvent of methanol: toluene = 30: 70 is further added to dissolve the toner. If solubility is poor, a small amount of acetone may be added. Then, using a mixed reagent of 0.1% by weight bromthymol blue and phenol red, titrating with a pre-standardized 0.1M potassium hydroxide / ethanol solution, and calculating from the consumption of the potassium hydroxide / ethanol solution as follows: Find the acid value with
[0110]
Acid value (mgKOH / g) = KOH (ml) × f × 56.1 / sample weight (g)
(In the above formula, f is a factor of 0.1 M potassium hydroxide / ethanol solution)
[0111]
In the present invention, the average of the two measurements performed by the above method is taken as the acid value.
[0112]
(4) Measurement of polyester weight average molecular weight
In the present invention, the weight average molecular weight was measured by gel permeation chromatography (GPC). The detailed measurement method is shown below.
[0113]
The column is stabilized in a 40 ° C. heat chamber, and THF (tetrahydrofuran) as a solvent is allowed to flow through the column at this temperature at a flow rate of 1 ml per minute, and about 100 μl of a THF sample solution is injected and measured. 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 standard polystyrene sample having a molecular weight of about 102 to 107 manufactured by Tosoh Corporation or Showa Denko is used, and at least about 10 standard polystyrene samples are suitably used. 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 shodex GPC KF-801, 802, 803, 804, 805, 806, 807, 800P manufactured by Showa Denko, A combination of TSKgel G1000H (H XL), G2000H (H XL), G3000H (H XL), G4000H (H XL), G5000H (H XL), G6000H (H XL), and G7000H (H XL) TSK guardcolumn is given.
[0114]
The sample is prepared as follows.
[0115]
Place the sample in tetrahydrofuran (THF) and let it stand for several hours, then shake well and mix well with THF (until the sample is no longer united), and let stand for more than 12 hours. At this time, the standing time in THF is set to be 24 hours or longer. Thereafter, a sample processing filter (pore size 0.45 to 0.5 μm, for example, Mysori Disc H-25-5 manufactured by Tosoh Corporation, Excro Disc 25CR manufactured by Gelman Science Japan Co., Ltd., etc.) can be used. A sample of GPC is used. The sample concentration is adjusted so that the resin component is 0.5 to 5 mg / ml.
[0116]
【Example】
EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this does not limit this invention at all. In addition, the number of parts in the following composition is part by weight unless otherwise specified.
[0117]
Example 1
To 1000 parts by weight of ion exchange water, 0.1M Na_Three PO_Four 500 parts by weight of aqueous solution and CaCl₂ An appropriate amount of 1M-HC1 aqueous solution was added so that the pH after addition was 4.9, and the mixture was heated to 60 ° C. and then stirred at 12000 rpm using a TK homomixer (manufactured by Tokushu Kika Kogyo) . To this, 1.0M-CaCl₂ Gradually add 74 parts by weight of aqueous solution and add Ca._Three (PO_Four )₂ An aqueous medium containing was obtained. After completion of the addition, stirring was continued for 30 minutes, and the pH of the aqueous medium was measured and found to be 4.9.
[0118]
on the other hand,
160 parts of styrene
40 parts of n-butyl acrylate
10 parts of saturated polyester resin produced using terephthalic acid as the acid component and propylene oxide-modified bisphenol A as the alcohol component
(Mw = 10,000, acid value 10 mgKOH / g)
16 parts of carbon black
2 parts of di-tert-butylsalicylate compound represented by the aforementioned chemical formula [I]
Di-tert-butylsalicylic acid 0.5 part
0.4 parts of divinylbenzene
30 parts of paraffin wax (mp 70 ° C.)
[0119]
The above formulation was heated to 60 ° C., and uniformly dissolved and dispersed at 12000 rpm using a TK homomixer (manufactured by Tokushu Kika Kogyo). In this, 10 parts by weight of a polymerization initiator 2,2′-azobis (2,4-dimethylvaleronitrile) was dissolved to prepare a polymerizable monomer composition.
[0120]
The polymerizable monomer composition is charged into the aqueous medium, 60 ° C., N₂ Under an atmosphere, the mixture was stirred at 10,000 rpm for 10 minutes with a TK homomixer to granulate the polymerizable monomer composition. Then, while stirring with a paddle stirring blade, the temperature was raised to 80 ° C. and reacted for 10 hours. After completion of the polymerization reaction, the residual monomer was distilled off under reduced pressure. After cooling, hydrochloric acid was added to dissolve calcium phosphate, followed by filtration, washing with water and drying. D1 = 6.1 μm, D4 = 7.2 μm, D4 Very sharp polymer particles with a particle size distribution of /D1=1.18 were obtained. At that time, the fine particles of 2 μm or less were 9%.
[0121]
The specific surface area by the BET method is 200 m with respect to 98.5 parts by weight of the obtained particles.² Toner A was obtained by externally adding 1.5 parts by weight of hydrophobic silica of / g. To 5 parts by weight of the toner, 95 parts by weight of an acrylic resin-coated ferrite carrier was mixed to obtain a developer.
[0122]
(Examples 2 and 3 and Comparative Examples 1 and 2)
In Example 1, Ca_Three (PO_Four )₂ Polymer particles were produced by changing the pH of the aqueous medium containing, as shown in Table 1. In Comparative Example 2, the pH was not adjusted with a 1M-HCl aqueous solution. Further, in the same manner as in Example 1, hydrophobic silica was externally added to obtain toners B to E, and 95 parts by weight of an acrylic resin-coated ferrite carrier was mixed with 5 parts by weight of this toner to obtain a developer.
[0123]
Example 4
Except for using aluminum 2-hydroxynaphthalene-3-carboxylate instead of the aluminum di-tert-butylsalicylate compound of Example 1 and using 2-hydroxynaphthalene-3-carboxylic acid instead of di-tert-butylsalicylic acid, In the same manner as in Example 1, polymer particles were obtained. Further, hydrophobic silica was externally added in the same manner as in Example 1 to obtain toner F, and 95 parts by weight of an acrylic resin-coated ferrite carrier was mixed with 5 parts by weight of this toner to obtain a developer.
[0124]
(Examples 5 and 6 and Comparative Examples 3 and 4)
In Example 4, Ca_Three (PO_Four )₂ Polymer particles were produced by changing the pH of the aqueous medium containing, as shown in Table 1. In Comparative Example 4, the pH was not adjusted with a 1M HCl aqueous solution. Further, hydrophobic silica was externally added in the same manner as in Example 1 to obtain toners G to J, and 95 parts by weight of an acrylic resin-coated ferrite carrier was mixed with 5 parts by weight of this toner to obtain a developer.
[0125]
(Example 7)
Polymer particles were obtained in the same manner as in Example 1 except that the colorant of Example 1 was replaced with a copper phthalocyanine pigment instead of carbon black. Further, hydrophobic silica was externally added in the same manner as in Example 1 to obtain toner K, and 95 parts by weight of an acrylic resin-coated ferrite carrier was mixed with 5 parts by weight of this toner to obtain a developer.
[0126]
(Examples 8 and 9 and Comparative Examples 5 and 6)
In Example 7, Ca_Three (PO_Four )₂ Polymer particles were produced by changing the pH of the aqueous medium containing, as shown in Table 1. In Comparative Example 6, the pH was not adjusted with a 1M HCl aqueous solution. Further, in the same manner as in Example 1, hydrophobic silica was externally added to obtain toners L to O, and 95 parts by weight of an acrylic resin-coated ferrite carrier was mixed with 5 parts by weight of the toner to obtain a developer.
[0127]
(Example 10)
Polymer particles were obtained in the same manner as in Example 1 except that naphthoic acid was used instead of di-tert-butylsalicylic acid used in Example 1. Further, hydrophobic silica was externally added in the same manner as in Example 1 to obtain toner P, and 95 parts by weight of an acrylic resin-coated ferrite carrier was mixed with 5 parts by weight of the toner to obtain a developer.
[0128]
(Examples 11 and 12 and Comparative Examples 7 and 8)
In Example 10, Ca_Three (PO_Four )₂ Polymer particles were produced by changing the pH of the aqueous medium containing, as shown in Table 1. In Comparative Example 8, the pH was not adjusted with a 1M HCl aqueous solution. Further, hydrophobic silica was externally added in the same manner as in Example 1 to obtain toners Q to T, and 95 parts by weight of an acrylic resin-coated ferrite carrier was mixed with 5 parts by weight of the toner to obtain a developer.
[0129]
Table 1 shows the evaluation results of the following evaluations using the toners produced in the above Examples and Comparative Examples. In each evaluation, a full-color copying machine CLC700 (manufactured by Canon) was used.
[0130]
The evaluation items are (1) transfer efficiency, (2) change in charge amount after initial and 50,000 sheet durability under normal temperature and humidity, (3) carrier contamination at that time, and (4) low temperature and low humidity and high temperature. This is a rising characteristic of charging at the time of copying 1000 sheets under high humidity.
[0131]
(1) Transfer efficiency
The transfer efficiency was determined by taking a toner image (image density of 1.4) formed on the photosensitive drum with a transparent adhesive tape at room temperature and normal humidity (23 ° C./60%), and measuring the image density (D₁ ) Is measured with a Macbeth densitometer or a color reflection densitometer (for example, Color reflection densitometer X-RITE 404A manufactured by X-Rite Co.). Next, a toner image is again formed on the photosensitive drum, the toner image is transferred to a recording material, the toner image transferred onto the recording material is collected with a transparent adhesive tape, and the image density (D₂ ) Is measured in the same manner. Obtained image density (D₁ ) And (D₂ ) To calculate as follows.
[0132]
Transfer efficiency (%) = (D₂ / D₁ ) × 100
[0133]
(2) Charge amount change
The change in charge amount was evaluated by the difference in the charge amount of the developer measured at the initial stage and after completion of 50,000 sheets by performing a copy test of 50,000 sheets at room temperature and normal humidity (23 ° C./60%). . The apparatus shown in FIG. 1 was used for the measurement of the charge amount.
[0134]
The developer to be measured for triboelectric charge is placed in a polyethylene bottle of 50-100 ml capacity, shaken by hand for 5-10 minutes, and then about 0.5-1.5 g of developer is added to the bottom of 500 mesh. Place in a metal measuring container 2 with a screen 3 and a metallic lid 4. Weigh the entire measurement container 2 at this time W₁ (G). Next, in the suction device 1 (at least the portion in contact with the measurement container 2) is suctioned from the suction port 7 and the air volume control valve 6 is adjusted to set the pressure of the vacuum gauge 5 to 250 mmAq. In this state, the toner is removed by suction for 2 minutes. The potential of the electrometer 9 at this time is set to V (volt). Here, 8 is a capacitor, and the capacity is C (μF). Also, measure the weight of the entire measurement container after suction.₂ (G). The charge amount (μC / g) of the toner is calculated as follows.
[0135]
[Outside 5]

[0136]
The evaluation was performed by expressing the change amount of the initial charge amount and the charge amount at the end of 50,000 sheets in “%” with reference to the initial charge amount. In practice, it is preferably C or more.
A: 0 to 10%
B: 11-20%
C: 21-30%
D: 31-40%
E: 41-50%
F: 51% or more
[0137]
(3) Carrier contamination
The carrier contamination was evaluated by observing the surface of the carrier after durability of 50,000 sheets with an electron microscope under normal temperature and normal humidity (23 ° C./60%), and the degree of contamination was evaluated according to the following criteria. In practice, it is preferably B or more.
A: No contamination has occurred.
B: Slight contamination has occurred.
C: Contamination has occurred.
D: Contamination has occurred severely.
[0138]
(4) Charging rise characteristics
As for the rising characteristics of charging, the image formation test was conducted under low temperature and low humidity (23 ° C./5%) and high temperature and high humidity (30 ° C./80%), and fogging was observed in a copy image in the initial durability (1000th sheet). Was evaluated by measuring.
[0139]
The fog on the paper is measured using a reflection densitometer (TOKYO DENSHOKU CO., LTD. REFECTOMETER ODEL TC-6DS). The amount of fog on paper was defined as Ds-Dr when D was taken as Dr.). If the fog is 3% or less, the image is substantially free from fog on paper, and if it exceeds 5%, the fog is slightly noticeable.
A: 0 to 3%
B: 3 to 5%
C: 6-9%
D: 10% or more
[0140]
[Table 1]

[0141]
【The invention's effect】
From the above results, as in the present invention, in a polymerized toner containing an organometallic compound and an aromatic carboxylic acid, particles of a polymerizable monomer composition were produced in an aqueous medium having a pH of 4.5 to 8.5, It has been found that, by polymerizing, a toner having good transfer characteristics can be obtained in various environments without producing fine particles with a very sharp particle size distribution, and excellent transfer characteristics. .
[Brief description of the drawings]
FIG. 1 is a schematic explanatory diagram of an apparatus for measuring the triboelectric chargeability of toner.

Claims (17)

After adding an acid to sodium phosphate _(Na 3 PO ₄₎ solution, by adding calcium chloride (CaCl ₂₎ solution, a pH4.9~6.8 from the end of the addition after stirring for 30 minutes, Ca ₃ Preparing an aqueous medium containing (PO ₄ ) ₂ ,
Polymerizability containing at least a polymerizable monomer containing a polymerizable vinyl monomer, a colorant, an organometallic compound, an aromatic carboxylic acid, a polyester resin having an acid value of 5 to 50 mgKOH / g, and a polymerization initiator A step of dispersing the monomer composition in the aqueous medium to produce particles of the polymerizable monomer composition in the aqueous medium; a polymerizable vinyl monomer in the particles of the polymerizable monomer composition; A method for producing a toner for developing an electrostatic charge image, comprising a step of polymerizing the toner.   The method for producing a toner for developing an electrostatic charge image according to claim 1, wherein the polyester resin has an acid value of 5 to 35 mg KOH / g.   3. The method for producing a toner for developing an electrostatic charge image according to claim 1, wherein the polyester resin is a polyester resin having a weight average molecular weight of 5,000 to 50,000.   The method for producing a toner for developing an electrostatic charge image according to claim 1, wherein the polyester resin is a polyester resin having a weight average molecular weight of 5000 to 35000.   2. The method for producing a toner for developing an electrostatic charge image according to claim 1, wherein the polyester resin is a polyester resin having a weight average molecular weight of 5000 to 50000 and an acid value of 5 to 35 mgKOH / g.   2. The method for producing a toner for developing an electrostatic charge image according to claim 1, wherein the polyester resin is a polyester resin having a weight average molecular weight of 5000 to 35000 and an acid value of 5 to 35 mg KOH / g.   The polymerizable vinyl monomer is a monomer selected from the group consisting of a styrene monomer, an acrylate monomer, and a methacrylate ester monomer. A method for producing a toner for developing an electrostatic charge image according to any one of claims 1 to 6.   8. The method for producing a toner for developing an electrostatic image according to claim 1, wherein the organometallic compound is a metal compound of an aromatic oxycarboxylic acid.   8. The electrostatic charge image developing toner according to claim 1, wherein the organometallic compound is a metal compound of an aromatic oxycarboxylic acid, and the contained metal is aluminum. Production method.   The method for producing a toner for developing an electrostatic charge image according to any one of claims 1 to 9, wherein the aromatic carboxylic acid is an aromatic oxycarboxylic acid.   10. The method for producing a toner for developing an electrostatic image according to claim 1, wherein the aromatic carboxylic acid is salicylic acid or an alkyl salicylic acid having an alkyl group having 5 or less carbon atoms. .   The method for producing a toner for developing an electrostatic charge image according to any one of claims 1 to 11, wherein the polymerizable monomer composition contains a wax.   The electrostatic charge image according to claim 1, wherein the polymerizable monomer composition contains 3 to 20 parts by weight of wax per 100 parts by weight of the polymerizable monomer. A method for producing a developing toner.   The electrostatic charge according to claim 1, wherein the polymerizable monomer composition contains 1 to 20 parts by weight of a colorant per 100 parts by weight of the polymerizable monomer. A method for producing a toner for image development.   The polymerizable monomer composition contains from 0.45 to 13.5 parts by weight of an organometallic compound per 100 parts by weight of the polymerizable monomer. A method for producing a toner for developing an electrostatic image as described in 1.   The polymerizable monomer composition contains 0.01 to 1.5 parts by weight of an aromatic carboxylic acid per 100 parts by weight of the polymerizable monomer. A method for producing a toner for developing an electrostatic image as described above.   The polysynthetic monomer composition contains 0.1 to 15% by weight of a polyester resin based on a polymerizable monomer, according to any one of claims 1 to 16. A method for producing a toner for developing an electrostatic image.

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