JP4135532B2 - Electrostatic latent image developing toner and image forming method - Google Patents

Description

ここで、相当円とは、トナー粒子投影像と同じ面積を有する円のことであり、円相当径とは、該相当円の直径のことである。
【０１００】
なお、上記円形度の測定方法としては、ＦＰＩＡ−２０００（シスメック社製）により測定することができる。この時、円相当径は下式で定義される。
【０１０１】
円相当径＝２×（粒子の投影面積／π）^1/2
又、本発明のトナーの形状は、円相当径の平均値が、２．６〜７．４μｍにあり、円相当径に対する円形度の傾きが−０．０５０〜−０．０１０であることを特徴とする。より好ましくは、円相当径の平均値が３．４〜６．６μｍにあり、円相当径に対する円形度の傾きが−０．０４０〜−０．０２０であるのがよい。
【０１０２】
円相当径の傾きの測定は、フロー式粒子像分析装置ＦＰＩＡ−２０００でトナー粒子の円相当径を測定し、それに対応する円形度との関係を、横軸：円相当径（μｍ）−縦軸：円形度として描き、その一次の相関（ｙ＝αｘ＋ｂ）をみれば、αが円相当径の傾きとなる。
【０１０３】
この時、帯電の均一性、ハーフトーンの均一性を高める観点からＲ²（Ｒの２乗）は０．３５〜０．９５が好ましい。ここにおいてＲは下記式（Ｉ）で表される。
【０１０４】
式（Ｉ） Ｒ＝Ａ／Ｂ
式中、Ａ、Ｂは各々下記式を表す。
【０１０５】
Ａ＝ｎΣＸＹ−（ΣＸΣＹ）
Ｂ＝（ｎΣＸ²−（ΣＸ）²）×（（ｎΣＹ²）−（ΣＹ）²）
Ｘは円相当径（μｍ）、Ｙは円形度を表す。
【０１０６】
また、円相当径の傾きを有するトナーを造るには、小粒径の球形トナー粒子にやや粒径の大きい異形のトナー粒子を混合しても良い。或いは、樹脂粒子を会合してトナー粒子を造るとき、会合工程で凝集剤を添加した後、撹拌羽根形状を適宜選択し、撹拌強度を制御し、大きめの粒子に剪断力がかかり易い条件として、濾過、乾燥工程に移行する方法でもよい。好ましくは、トナー製造装置と前述のフロー式粒子像分析装置をインライン接続し、傾きαをモニタリングしつつ、適宜条件を調整しながら製造する。
【０１０７】
好ましくは塩析／融着を停止させる停止剤を投入した後、例えば塩析剤の再添加や界面活性剤の追加により、トナー粒子をさらに０．２〜１．０μｍ成長させると、上記の範囲内に入るよう制御することが出来る。
【０１０８】
又、本発明において、トナーの帯電量分布を好適にする観点から、トナー粒子の小粒径側から累積で１０個数％における円相当径ｄ₁₀と累積で９０個数％における円相当径ｄ₉₀との比、ｄ₉₀／ｄ₁₀が１．２〜２．０であることが好ましい。特に好ましくは１．３〜１．８である。この範囲にあれば、ドットのチリを制御することが出来、ハーフトーンの均一性が高く、高品位な画像を得ることが出来る。
【０１０９】
〔現像剤〕
本発明のトナーは、一成分現像剤、或いは二成分現像剤として用いることができる。
【０１１０】
一成分現像剤として用いる場合は、非磁性一成分現像剤、或いはトナー中に０．１〜０．５μｍの磁性粒子を含有させ磁性一成分現像剤としたものが挙げられ、いずれも用いることができる。
【０１１１】
又、本発明のトナーは、磁性粒子であるキャリアと混合して二成分現像剤として用いることができる。キャリアとしては、例えば、鉄、フェライト、マグネタイト等の金属、それらの金属とアルミニウム、鉛等の金属との合金等の従来から公知の材料を用いることが出来る。これらの中ではフェライト粒子が好ましい。上記キャリアの体積平均粒径としては１５〜１００μｍのものが好ましく、２５〜８０μｍのものがより好ましい。
【０１１２】
キャリアの体積平均粒径の測定は、代表的には湿式分散機を備えたレーザ回折式粒度分布測定装置「ヘロス」（シンパティック社製）により測定することができる。
【０１１３】
又、キャリアとしては、磁性粒子を樹脂でコーティングしたもの、あるいは樹脂中に磁性粒子を分散させたいわゆる樹脂分散型キャリアを用いることもできる。コーティング用の樹脂としては、例えば、オレフィン系樹脂、スチレン系樹脂、スチレン−アクリル系樹脂、シリコーン系樹脂、エステル系樹脂或いはフッ素含有重合体系樹脂等を挙げることができる。又、樹脂分散型キャリアを構成するための樹脂としては、例えば、スチレン−アクリル系樹脂、ポリエステル樹脂、フッ素系樹脂、フェノール樹脂等を挙げることができる。
【０１１４】
〔画像形成方法〕
次に本発明のトナーを用いる画像形成方法に用いる画像形成装置について説明する。
【０１１５】
図１は本発明の画像形成方法に用いる装置の一例を示す構成図である。３４は被帯電体である感光体ドラムであり、アルミニウム製のドラム基体の外周面に感光体層である有機光導電体（ＯＰＣ）を形成してなるもので矢印方向に所定の速度で回転する。
【０１１６】
図１において、図示しない原稿読み取り装置にて読み取った情報に基づき、半導体レーザ光源３１から露光光が発せられる。これをポリゴンミラー３２により、図１の紙面と垂直方向に振り分け、画像の歪みを補正するｆθレンズ３３を介して、感光体面上に照射され静電潜像を形成する。感光体ドラム３４は、予め帯電器３５により一様帯電され、像露光のタイミングにあわせて時計方向に回転を開始している。
【０１１７】
感光体ドラム面上の静電潜像は、現像器３６により現像され、形成された現像像はタイミングを合わせて搬送されてきた記録媒体（転写材、転写紙、記録紙ともいう）Ｐに転写器３７の作用により転写される。更に感光体ドラム３４と転写材３８は分離器（分離極）３９により分離されるが、現像像は転写材３８に転写担持されて、定着器４０へと導かれ定着される。
【０１１８】
感光体面に残留した未転写のトナー等は、クリーニングブレード方式のクリーニング器４１にて清掃され、帯電前露光（ＰＣＬ）４２にて残留電荷を除き、次の画像形成のため再び帯電器３５により、一様帯電される。
【０１１９】
なお、前記露光は、本発明ではデジタル像露光が特に好ましいものであるが、アナログによる像露光を行うものであってもよい。
【０１２０】
本発明は、電子写真法による画像形成装置、特にコンピュータ等からのデジタル画像データで変調した変調ビームにより感光体上に静電潜像を形成する装置に使用することもできる。
【０１２１】
図２は、本発明のトナーに適用されるデジタル画像形成装置を示す構成断面図である。
【０１２２】
図２において、画像形成装置１０１は、自動原稿搬送装置（通称ＡＤＦ）Ａと、自動原稿搬送装置により搬送される原稿の画像を読み取るための原稿画像読取部Ｂと、読み取った原稿画像を処理する画像制御基板Ｃと、画像処理後のデータに従って像担持体としての感光体ドラム３４上に書き込みを行う書き込みユニット１１２を含む書き込み部Ｄと、感光体ドラム３４及びその周囲に帯電器３５、磁気ブラシ型現像装置からなる現像器３６、転写器３７、分離器３９、クリーニング器４１等の画像形成手段を含む画像形成部Ｅと、記録紙Ｐを収納する給紙トレイ１２２、１２４のための収納部Ｆを有している。
【０１２３】
自動原稿搬送装置Ａは、原稿載置台１２６と、ローラＲ１を含むローラ群および原稿の移動通路を適宜切り替えるための切換手段等（参照記号なし）を含む原稿搬送処理部１２８とを主要素とする。
【０１２４】
原稿画像読取部Ｂは、プラテンガラスＧの下にあり、光路長を保って往復移動できる２つのミラーユニット１３０、１３１、固定の結像レンズ（以下、単にレンズという）１３３、ライン状の撮像素子（以下、ＣＣＤという）１３５等からなり、書き込み部Ｄは、レーザ光源３１、ポリゴンミラー（偏光器）３２等からなる。
【０１２５】
転写材としての記録紙Ｐの移動方向からみて、転写器３７の手前側に示すＲ１０はレジストローラであり、分離器３９の下流側に４０で示してあるのは定着器である。
【０１２６】
定着器４０は、実施の形態においては、加熱源を内蔵するローラと、当該ローラに圧接しながら回転する圧接ローラとで構成してある。
【０１２７】
また、Ｚは定着器４０のためのクリーニング手段で、巻き取り可能に設けたクリーニングウェブを主要素とする。
【０１２８】
原稿載置台１２６上に載置される原稿（図示せず）の１枚が原稿搬送処理部１２８によって搬送され、ローラＲ１の下を通過中に、露光手段Ｌによる露光が行われる。
【０１２９】
原稿からの反射光は、固定位置にあるミラーユニット１３０、１３１およびレンズ１３３を経てＣＣＤ１３５上に結像され、読み取られる。
【０１３０】
原稿画像読取部Ｂで読み取られた画像情報は、画像処理手段により処理され、符号化されて画像制御基板Ｃ上に設けてあるメモリーに格納される。
【０１３１】
また、画像データは画像形成に応じて呼び出され、当該画像データに従って、書き込み部Ｄにおけるレーザ光源３１が駆動され、感光体ドラム３４上に露光が行われる。
【０１３２】
近年、感光体上に静電潜像を形成し、この潜像を現像して可視画像を得る電子写真等の分野において、画質の改善、変換、編集等が容易で高品質の画像形成が可能なデジタル方式を採用した画像形成方法の研究開発が盛んになされている。
【０１３３】
この画像形成方法及び装置に採用されるコンピュータまたは複写原稿からのデジタル画像信号により光変調する走査光学系として、レーザ光学系に音響光学変調器を介在させ、当該音響光学変調器により光変調する装置、半導体レーザを用い、レーザ強度を直接変調する装置があり、これらの走査光学系から一様に帯電した感光体上にスポット露光してドット状の画像を形成する。
【０１３４】
前述の走査光学系から照射されるビームは、裾が左右に広がった正規分布状に近似した丸状や楕円状の輝度分布となり、例えばレーザビームの場合、通常、感光体上で主走査方向あるいは副走査方向の一方あるいは両者が２０〜１００μｍという極めて狭い丸状あるいは楕円状である。
【０１３５】
本発明では、モノクロ画像だけではなく、カラー画像を得るための画像形成にも適用されるもので、例えば複数個の画像形成ユニットを備え、各画像形成ユニットにてそれぞれ色の異なる可視画像（トナー画像）を形成してトナー画像を形成する画像形成方法である。
【０１３６】
本発明のトナーは、トナー像が形成された画像形成支持体を、定着装置を構成する加熱ローラーと加圧ローラーとの間に通過させて定着する工程を含む画像形成方法に好適に使用される。
【０１３７】
図３は、本発明のトナーを用いた画像形成方法において使用する定着装置の一例を示す断面図であり、図３に示す定着器４０は、加熱ローラー７１と、これに当接する加圧ローラー７２とを備えている。なお、図３において、Ｔは記録媒体Ｐ上に形成されたトナー像である。
【０１３８】
加熱ローラー７１は、フッ素樹脂または弾性体からなる被覆層８２が芯金８１の表面に形成されてなり、線状ヒーターよりなる加熱部材７５を内包している。
【０１３９】
芯金８１は、金属から構成され、その内径は１０〜７０ｍｍである。芯金８１を構成する金属としては特に限定されるものではないが、例えば鉄、アルミニウム、銅等の金属あるいはこれらの合金を挙げることができる。
【０１４０】
芯金８１の肉厚は０．１〜１５ｍｍであり、省エネルギーの要請（薄肉化）と、強度（構成材料に依存）とのバランスを考慮して決定される。例えば、０．５７ｍｍの鉄よりなる芯金と同等の強度を、アルミニウムよりなる芯金で保持するためには、その肉厚を０．８ｍｍとする必要がある。
【０１４１】
被覆層８２を構成するフッ素樹脂としては、ＰＴＦＥ（ポリテトラフルオロエチレン）およびＰＦＡ（テトラフルオロエチレン−パーフルオロアルキルビニルエーテル共重合体）などを例示することができる。
【０１４２】
フッ素樹脂からなる被覆層８２の厚みは１０〜５００μｍであり、好ましくは２０〜４００μｍである。
【０１４３】
加熱部材７５としては、ハロゲンヒーターを好適に使用することができる。
加圧ローラー７２は、弾性体からなる被覆層８４が芯金８３の表面に形成されてなる。被覆層８４を構成する弾性体としては特に限定されるものではなく、ウレタンゴム、シリコーンゴムなどの各種軟質ゴムおよびスポンジゴムを挙げることができ、被覆層８４を構成するものとして例示したシリコーンゴムおよびシリコーンスポンジゴムを用いることが好ましい。
【０１４４】
被覆層８４を構成する弾性体のアスカーＣ硬度は、８０°未満であり、好ましくは７０°未満、更に好ましくは６０°未満である。
【０１４５】
また、被覆層８４の厚みは０．１〜３０ｍｍであり、好ましくは０．１〜２０ｍｍである。
【０１４６】
芯金８３を構成する材料としては特に限定されるものではないが、アルミニウム、鉄、銅などの金属またはそれらの合金を挙げることができる。
【０１４７】
加熱ローラー７１と加圧ローラー７２との当接荷重（総荷重）としては、通常４０〜３５０Ｎであり、好ましくは５０〜３００Ｎ、さらに好ましくは５０〜２５０Ｎである。この当接荷重は、加熱ローラー７１の強度（芯金８１の肉厚）を考慮して規定され、例えば０．３ｍｍの鉄よりなる芯金を有する加熱ローラーにあっては、２５０Ｎ以下とすることが好ましい。
【０１４８】
また、耐オフセット性および定着性の観点から、ニップ幅としては４〜１０ｍｍであることが好ましく、当該ニップの面圧は０．６×１０⁵Ｐａ〜１．５×１０⁵Ｐａであることが好ましい。
【０１４９】
図３に示した定着装置による定着条件の一例を示せば、定着温度（加熱ローラー７１の表面温度）が１５０〜２１０℃であり、定着線速が２３０〜９００ｍｍ／ｓｅｃである。
【０１５０】
上記定着器にはクリーニング機構を付与して使用してもよい。クリーニング方式としては、各種シリコーンオイルを定着用フィルムに供給する方式や各種シリコーンオイルを含浸させたパッド、ローラー、ウェッブ等でクリーニングする方式が用いられる。
【０１５１】
なお、シリコーンオイルとしては、ポリジメチルシロキサン、ポリメチルフェニルシロキサン、ポリジフェニルシロキサン等を使用することが出来る。更に、フッ素を含有するシロキサンも好適に使用することが出来る。
【０１５２】
また、本発明で用いられる画像形成装置では、感光体表面に残留した未転写トナーをリサイクル使用するトナーリサイクルを行う機構を有するものであってもよい。トナーリサイクルを行うための方式としては特に限定されるものではないが、たとえばクリーニング部で回収されたトナーを搬送コンベアあるいは搬送スクリューにより補給用トナーホッパー、現像器あるいは補給用トナーと中間室によって混合して現像器へ供給する方法等を挙げることができる。好ましくは現像器へ直接戻す方式あるいは中間室にて補給用トナーとリサイクルトナーを混合して供給する方式を挙げることができる。
【０１５３】
次に、本発明に係わる非磁性一成分現像方法について具体的に説明する。
図４は非磁性一成分現像の画像形成方法に用いる現像器３６の概要断面図である。
【０１５４】
図４においてトナータンク４１７に内蔵された非磁性一成分トナー４１６は、トナー補給補助部材としての撹拌羽根４１５により、同じくトナー補給補助部材としてのスポンジローラー４１４上に強制的に搬送供給される。こうしてスポンジローラー上に組込まれたトナーはこのローラー４１４の矢印方向の回転によりトナー搬送部材としてのゴムローラー４１２上に搬送され、このローラー４１２との摩擦によりその表面に静電的、且つ物理的に吸着される。一方、こうしてゴムローラー４１２上に付着したトナーはこのローラー４１２の矢印方向の回転及びトナー層厚規制部材としてのスチール製弾性ブレード４１３により均一に薄層化されると共に摩擦帯電する。次にゴムローラー４１２上のトナー薄層は静電潜像担持体としての感光体ドラム３４の表面と接触または近接により潜像が現像される。
【０１５５】
なお本発明方法で用いられる非磁性一成分現像器は図４に示すものに限定されないことは勿論である。
【０１５６】
【実施例】
以下実施例により本発明をさらに説明するが、本発明はこれに限定されるものではない。以下の記載において「部」は質量部、「％」は質量％を示す。
【０１５７】
実施例１
〔樹脂溶液１（ポリエステル樹脂）の作製〕
冷却管、撹拌機および窒素導入管の付いた反応容器中に、ビスフェノールＡエチレンオキサイド２モル付加物３４３部、イソフタル酸１６６部およびジブチルチンオキサイド２部を入れ、常圧で２３０℃で８時間反応し、さらに１．３３〜１．９９Ｐａ（１０〜１５ｍｍＨｇ）の減圧条件下で５時間反応した後、１１０℃まで冷却し、トルエン中にてイソホロンジイソシアネート１７部を入れて１１０℃で５時間反応を行い、次いで脱溶剤し、重量平均分子量７２，０００、遊離イソシアネート含量０．７％の［ウレタン変性ポリエステル（１）］を得た。
【０１５８】
上記と同様に、ビスフェノールＡエチレンオキサイド２モル付加物５７０部、テレフタル酸２１７部を常圧下、２３０℃で６時間重縮合し、数平均分子量２，４００、水酸基価５１、酸価５の変性されていない［ポリエステル（２）］を得た。
【０１５９】
［ウレタン変性ポリエステル（１）］２００部と［ポリエステル（２）］８００部を酢酸エチル２，０００部に溶解、混合し、［樹脂溶液１］を得た。なお、樹脂溶液１中の樹脂成分のＴｇは６４℃であった。
【０１６０】
〔トナーの製造〕
［樹脂溶液１］（樹脂成分のＴｇ６４℃） １００部
Ｐｉｇｍｅｎｔ Ｂｌｕｅ １５：３ 含水ケーキ
（含水ケーキ中の固形分５０％） １２部
荷電制御剤（スピロンブラックＴＲＨ 保土ケ谷化学社製） １部
カルナウバワックス １０部
上記材料をトルエン２００部中でジルコニアビーズの充填されたボールミルを転動させることによって溶解分散し、分散相となる油相を調製した。
【０１６１】
別途、
イオン交換水 ７００部
ドデシルベンゼンスルホン酸ナトリウム １部
を撹拌分散し連続相となる水相を調製した。水相中にホモミキサー（特殊機化工業社製）で撹拌しながら油相を投入し、撹拌回転数を調整することにより体積平均粒径約１μｍの油滴を作製した。その後、５０℃で減圧溜去してトルエンを除去し、青灰色の乳濁液を得た。
【０１６２】
インぺラーの備わった撹拌タンクに得られた分散液を移し、硫酸アルミニウム１０部をイオン交換水９０部に溶解した水溶液を低速で撹拌しながら徐々に滴下することにより、凝集粒子を形成させ、その後液温を９０℃に保ち、凝集が合一融解したのを一部サンプリングして走査型電子顕微鏡により確認した。
【０１６３】
その後９５℃で８時間撹拌し、トナーの円形度が表１の値になったところで、４０℃まで冷却し、撹拌を停止した。
【０１６４】
その後、水洗とろ過を繰り返し、得られたケーキを減圧乾燥してシアン色の着色粒子を得た。得られた着色粒子１００部と針状酸化チタン（長径１２０ｎｍ、ｎ−デシルトリメトキシシラン処理）０．８質量部、球形単分散シリカ（ゾルゲル法で得られたシリカゾルにヘキサメチルジシラザン処理を行い、乾燥、粉砕処理を施した、粒子径１３７ｎｍ）１．８質量部、さらに気相法で製造しオクチルメトキシシラン処理したシリカ粒子（粒子径１４ｎｍ）０．３質量部を、ヘンシェルミキサーにより混合し、目開き５０μｍの篩を通過させることにより粗大粒子や凝集物を取り除くことにより、電子写真用トナーＴ１−Ｃを得た。
【０１６５】
トナーＴ１−Ｋの作製
トナーＴ１−Ｃの製造工程におけるＰｉｇｍｅｎｔ Ｂｌｕｅ １５：３ 含水ケーキ（含水ケーキ中の固形分５０％）を、着色剤としてフタロシアニングリーン含水ケーキ（固形分３０％）２部とカーボンブラック（ＭＡ６０ 三菱化学社製）１０部を用いてトナーＴ１−Ｋを得た。
【０１６６】
トナーＴ２−ＣおよびＴ２−Ｋの作製
［ウレタン変性ポリエステル（１）］２４０部と［ポリエステル（２）］４０部を酢酸エチル２，０００部に溶解、混合し、他はトナーＴ１−ＣおよびＴ１−Ｋと同様にして、トナーＴ２−ＣおよびＴ２−Ｋを作製した。
【０１６７】
トナーＴ３−ＣおよびＴ３−Ｋの作製
［ポリエステル（２）］２８０部を用いて、酢酸エチル２，０００部に溶解、混合し、他はトナーＴ１−ＣおよびＴ１−Ｋと同様にして、いずれも比較用のトナーＴ３−ＣおよびＴ３−Ｋを作製した。
【０１６８】
下記にトナーＴ１−Ｃ〜Ｔ３−Ｋの各トナーの円相当径の平均値（μｍ）、円形度の平均値、円相当径に対する円形度の傾きを示す。
【０１６９】
【表１】

【０１７０】
〔キャリアの作製〕
シリコーン樹脂（２０％） １００部
γ−（２−アミノエチル）アミノプロピルトリメトキシシラン １．０部
カーボンブラック ０．１部
トルエン ６０部
これらの処方をホモミキサーで２０分分散して被覆層形成液を調製した。これをフェライト１０００部（体積平均粒径５５μｍ、飽和磁化７２ｅｍｕ／ｇ）の表面に、流動床型塗布装置を用いて被覆層を形成した後、電気炉にて焼成してキャリアを作製した。
【０１７１】
〔現像剤の作製〕
キャリア１００部に対し各々トナー５部を容器が転動して撹拌される形式のターブラーミキサーを用い、５０ｒｐｍ、１５分間均一混合し帯電させ、現像剤を作製した。
【０１７２】
〔特性評価〕
得られた現像剤について、下記に記載される評価を行った。評価を実施するにあたり、図２に記載されるデジタル露光器を有する画像形成装置を用い、現像剤単独使用での評価を行った。また、画像形成に使用した定着装置の構成は図３に示すものと同様な装置構成とした。
【０１７３】
（定着性）
極厚用紙における定着性
ハート社製の喪中はがき（厚さ０．４ｍｍ）５００枚を用い、図２に記載の画像形成装置を評価機として使用して連続プリントを行った。
【０１７４】
なお、はがきの枠部に相対濃度０．５のグレー枠をつけた。得られたプリントを下記の様にランク評価した。
【０１７５】
◎：グレー枠上につけペンで文字を強く書いても全くトナーが剥落しない
○：グレー枠上につけペンで文字を強く書いた時にトナーが剥落するが、ボールペン使用時にはトナーの剥離が起きない
×：定着が不十分でグレー枠を手に持っただけで、トナーが剥落して手が汚れる
オフセット印刷用紙への定着性
大王製紙社製の文庫本用紙（６０．２ｇ紙、オフセット印刷用、中質：非塗工紙）に印字を行い、片手親指で１０回めくり、文字周辺のにじみ状汚れを目視及びルーペ（倍率１０倍）で観察し、下記の様にランク評価を行った。
【０１７６】
◎：にじみ状の汚れが全く発生していない
○：目視ではにじみ状の汚れが観察されないが、ルーペ観察で僅かに汚れが検知できる程度で実用上問題がない
×：親指の跡が黒くにじんだ様に汚れている。
【０１７７】
（トナーブリスタ発生）
普通紙（６４ｇ／ｃｍ²）上のトナー付着量が１．６ｍｇ／ｃｍ²となる様に画像形成を行い、画像上に０．１〜０．５μｍ程度の孔、すなわち、トナーブリスタの有無を目視で観察し、下記の様にランク評価した。
【０１７８】
◎：トナーブリスタの発生が全く見られない
○：４ｃｍ²あたり１〜２個のトナーブリスタが存在するが、実用上問題のないレベル
×：４ｃｍ²あたり３個以上の明瞭なトナーブリスタの存在が認められ、実用不可のレベル
（ライン幅再現性）
２ドットラインの画像信号に対応するライン画像のライン幅を印字評価システム「ＲＴ２０００」（ヤーマン社製）によって測定した。１枚目の形成画像のライン幅および２００００枚目の形成画像のライン幅の何れもが２００μｍ以下であり、かつ、ライン幅の変化が１０μｍ未満であれば、細線再現性は問題ないといえ「○」、それ以外を「×」とした。
【０１７９】
（微細ドットのチリ）
二次色（レッド、ブルー、グリーン）画像全面に１０％網点画像を形成し、ルーペにてドット周辺のチリを観察した。チリがほとんど検知できないモノを「◎」、微かにチリがあるが、注視しなければ気づかない程度を「○」、チリが容易に検知できるものを「×」とした。
【０１８０】
〔評価結果〕
下記表２に示した。
【０１８１】
【表２】

【０１８２】
表２から明らかな如く、本発明内のトナーＴ１−ＫおよびＴ１−Ｃと、トナーＴ２−ＫおよびＴ２−Ｃはいずれの特性もよいが、本発明外のトナーＴ３−ＫおよびＴ３−Ｃは特性に問題が出ることがわかる。
【０１８３】
実施例２
実施例１で用いた本発明内のトナーＴ１−Ｋと本発明外のトナーＴ３−Ｋを用いて、非磁性一成分現像方式（基本構成は図４と同一）の画像形成装置を用い、非磁性一成分トナーとしての特性を調べた。
【０１８４】
トナー帯電は、ソフトな現像ローラ面に０．２ｍｍ厚の金属板ブレードをトレイル方式で現像ローラ全幅にわたり均等に当接させることにより与えた。
【０１８５】
本発明内のトナーＴ１−ＫおよびＴ１−Ｃを用いたものは、１０，０００コピーまで良好な画像が得られたが、本発明外のトナーＴ３−ＫおよびＴ３−Ｃを用いたものは３，０００コピーあたりから、トナーのチリが目立つ画像となった。また、中間濃度画像の濃度ムラが目立つようになった。分解して現像ローラ表面を肉眼で観察したところ、トナーＴ３−Ｋでは、ブレードにより破砕されたトナー微粉の付着が目立った。
【０１８６】
【発明の効果】
本発明により、厚い紙に画像形成を行った時に優れた定着性を発現し、特にグレーのハーフトーン画像を確実に定着させることの可能なトナーと画像形成方法を提供することが出来る。
【０１８７】
また、本発明により、非磁性現像トナーの帯電時や、厚い紙面上への画像形成時に作用する負荷に耐えられる高い粒子強度を有するトナーと画像形成方法を提供することが出来る。
【０１８８】
また、本発明により、印刷用紙に形成されたトナー画像が、印刷物に劣ることのないすべり性や定着強度を発現することの可能なトナーと画像形成方法を提供することが出来る。
【０１８９】
さらに、本発明により、トナーブリスタと呼ばれるトナー画像上の高濃度部分における画像欠陥を発生しないトナーと画像形成方法を提供することが出来る。
【図面の簡単な説明】
【図１】画像形成装置の一例を示す構成図。
【図２】デジタル画像形成装置を示す構成断面図。
【図３】定着装置の一例を示す断面図。
【図４】非磁性一成分現像の画像形成方法に用いる現像器の概要断面図。
【符号の説明】
３４ 感光体ドラム
３６ 現像器
３７ 転写器
３９ 分離器
４０ 定着器
４１ クリーニング器
１０１ 画像形成装置
１２２、１２４ 給紙トレイ
１３０、１３１ ミラーユニット
１３５ ＣＣＤ
４１４ スポンジローラー
４１５ 撹拌羽根
４１７ トナータンク
Ａ 自動原稿搬送装置（通称ＡＤＦ）
Ｂ 原稿画像読取部
Ｅ 画像形成部[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electrostatic latent image developing toner (also simply referred to as toner) used for digital image formation and an image forming method using the same.
[0002]
[Prior art]
Image formation by electrophotography is now shifting to digital. In the image formation by the digital method, excellent thin line reproducibility and high resolution are manifested in order to visualize a dot image with a small level of 1200 dpi (number of dots per 2.54 cm), which has recently been highly demanded. In order to form an image by electrophotography, it is essential to use a toner for developing an electrostatic latent image having a small diameter.
[0003]
In Patent Document 1 and Patent Document 2 described below, as an example of producing such a small-diameter toner, a raw material for toner including a polyester resin is emulsified and dispersed in an aqueous medium, and the resin particles in the emulsified dispersion are dispersed in a toner size. A method for producing toner to be agglomerated is disclosed.
[0004]
By the way, as an embodiment of the above-described digital image formation, there is a print-on-demand image forming method for performing printing “only as many copies as necessary”. Image formation by this method eliminates the need for plate printing by conventional printing, and can issue several hundreds of publications or create direct mails and invitations while changing the address. Therefore, it has been attracting attention as an effective image forming means replacing light printing.
[0005]
However, it has been found that the use of electrophotographic image formation has a problem in creating mails and guide letters with different addresses. That is, when image formation is performed on thick paper such as wedding invitations, mourning postcards, and funeral letters, sufficient fixing cannot be obtained. In particular, it has been found that a postcard or funeral card with a gray frame specification is not sufficiently fixed in the gray frame portion, and the user's hand is soiled by unfixed toner and causes paper contamination.
[0006]
In addition, when a toner image is formed on a thick paper surface, a large load is applied to the toner particles that cannot be compared with the case of outputting to a copy paper or the like. It may cause the problem of contaminating the paper surface with fine powder.
[0007]
Thick paper such as mourning postcards described above is one of the recording media that are most likely to cause problems, but there are other problems in disseminating electrophotography as a print-on-demand image forming means. For example, printing paper is often used instead of plain paper developed for electrophotography as a recording medium. It is necessary that the toner image can be stably formed on the printing paper, and this condition may not be completely cleared.
[0008]
For example, in printed materials, commuter passengers often see the reading of a paperback book with one hand while hanging on a leather at rush hour. It is required that the toner has a “fixing strength” that does not rub the paper and characters due to the toner being rubbed. However, a toner image by an electrophotographic method is inferior in slipperiness and fixing strength as compared with a normal printed matter.
[0009]
The above-described problems are not solved just by using the toner disclosed in Patent Document 1 and Patent Document 2, and the application of the electrophotographic method to the image formation of the print-on-demand method is as follows. It was hard to accept from the printing industry.
[0010]
Furthermore, when image formation is performed using toner obtained through the cleaning methods disclosed in Patent Document 1 and Patent Document 2, a toner blister in which white granular image defects are generated at high density portions on the toner image; There was a problem called. In particular, this tendency was noticeable when continuous printing of 100,000 or more is performed or when images are continuously formed in a low humidity environment.
[0011]
This is because the moisture taken in by the impurities such as the aggregating agent remaining on the surface of the resin particles forming the toner is discharged as water vapor by heating in the fixing process, and the toner layer is destroyed at the time of discharge, resulting in image defects. Presumed to be generated.
[0012]
As described above, there has been a problem in smoothly performing on-demand image formation instead of light printing with toner particles produced through a process of aggregating resin particles in an aqueous medium.
[0013]
[Patent Document 1]
JP 2002-296839 A
[0014]
[Patent Document 2]
JP 2002-351140 A
[0015]
[Problems to be solved by the invention]
SUMMARY OF THE INVENTION A first object of the present invention is to provide a toner and an image forming method capable of exhibiting excellent fixability when an image is formed on a thick paper and particularly capable of reliably fixing a gray halftone image. And
[0016]
It is a second object of the present invention to provide a toner having a high particle strength that can withstand a load that acts when a nonmagnetic developing toner is charged or when an image is formed on a thick paper surface, and an image forming method. .
[0017]
A third object of the present invention is to provide a toner and an image forming method in which a toner image formed on a printing paper can exhibit slipperiness and fixing strength that are not inferior to printed matter.
[0018]
Furthermore, a fourth object of the present invention is to provide a toner and an image forming method which do not cause an image defect in a high density portion on a toner image called a toner blister.
[0019]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present inventor obtained agglomeration of amorphous polyester resin particles from an aqueous medium in which resin particles containing urethane-modified amorphous polyester were dispersed after repeated investigations. The present inventors have found that the above problems can be solved by toner.
[0020]
  That is, the object of the present invention is achieved by adopting the following configuration.
  [1] A toner obtained by a process of aggregating amorphous polyester resin particles in an aqueous medium using a dispersion obtained by dispersing amorphous polyester resin particles in an aqueous medium, the amorphous polyester resin particles Contains urethane-modified polyesterFurther, the average value of the circularity of the toner is 0.94 to 0.99, the average value of the equivalent circle diameter is 2.6 to 7.4 μm, and the inclination of the circularity with respect to the equivalent circle diameter is inclined. -0.050 to -0.010A toner for developing an electrostatic latent image.
[0022]
  [2The toner is silica having an average primary particle size of 50 to 200 nm orOxidationTitanium fine particles are externally added [1]The toner for developing an electrostatic latent image.
[0023]
  [3] [1]Or [2]An image forming method comprising forming an image using the toner for developing an electrostatic latent image according to the item.
[0024]
That the amorphous polyester resin particles of the present invention contain urethane-modified polyester means that the resin that forms the resin particles contains urethane-modified polyester more than the degree that the effect is manifested. Also included are those in which the resin of the resin particles is all urethane-modified polyester. The specific structure of the urethane-modified polyester will be described later.
[0025]
The step of aggregating the amorphous polyester resin particles in the aqueous medium using a dispersion obtained by dispersing the amorphous polyester resin particles in the aqueous medium will be described in detail later.
[0026]
The toner particles obtained according to the present invention have extremely high crushing strength, and therefore do not break or deform the particle shape even when subjected to a physical impact. The problem of the conventional emulsion association type toner can be solved. Therefore, the durability of the developer is high, and since the crushed fine powder does not adhere to surrounding equipment such as a developing roller, the durability of the developer is also increased. In addition, scattering of toner fine powder hardly occurs. As in the non-magnetic one-component development system, it can be suitably used for a development system that receives a considerable physical impact by a developing roller and a charging member (blade or the like) that contacts the developing roller when the toner is charged.
[0027]
On the other hand, urethane-modified polyester has a high elastic modulus at the time of heat melting, and toner containing it is difficult to offset, so that it can be suitably used for an oilless fixing method. Conventionally, the crosslinkable polyester which has been attracting attention as a resin having such a high elastic modulus is insoluble in a solvent and is not suitable for the production method of the present invention. However, it was found that the urethane-modified polyester is soluble in a solvent, and the treatment such as dispersing the resin in an aqueous medium is easier.
[0028]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a toner composition component, an image forming method and the like constituting the toner according to the present invention will be described.
[0029]
[Urethane-modified polyester resin]
The amorphous polyester resin used in the present invention is modified by having a urethane bond in a molecular structure called urethane-modified polyester.
[0030]
Hereinafter, the urethane-modified polyester will be described.
Examples of the polyester modified with a urethane bond include a reaction product of a polyester prepolymer (A) having an isocyanate group and amines (B). Examples of the polyester prepolymer (A) having an isocyanate group include those obtained by polycondensation of a polyvalent carboxylic acid and a polyhydric alcohol, and a polyester having an active hydrogen group further reacted with a polyisocyanate. It is done.
[0031]
Examples of the active hydrogen group possessed by the polyester include hydroxyl groups (alcoholic hydroxyl groups and phenolic hydroxyl groups), amino groups, carboxyl groups, mercapto groups, and the like. Among these, alcoholic hydroxyl groups are preferred.
[0032]
Polyisocyanates include aliphatic polyisocyanates (tetramethylene diisocyanate, hexamethylene diisocyanate, 2,6-diisocyanatomethylcaproate, etc.); alicyclic polyisocyanates (isophorone diisocyanate, cyclohexylmethane diisocyanate, etc.); aromatic diisocyanates ( Tolylene diisocyanate, diphenylmethane diisocyanate, etc.); araliphatic diisocyanates (α, α, α ′, α′-tetramethylxylylene diisocyanate, etc.); isocyanurates; And combinations of two or more of these.
[0033]
The ratio of the polyisocyanate is usually 5/1 to 1/1, preferably 4/1 to 1 as an equivalent ratio [NCO] / [OH] of the isocyanate group [NCO] and the hydroxyl group [OH] of the polyester having a hydroxyl group. .2 / 1, more preferably 2.5 / 1 to 1.5 / 1. If [NCO] / [OH] exceeds 5, the low-temperature fixability may deteriorate.
[0034]
When the molar ratio of [NCO] is less than 1, the urethane content in the modified polyester becomes low, and the hot offset resistance may be deteriorated. The content of the polyisocyanate component in the prepolymer (A) having an isocyanate group at the terminal is usually 0.5 to 40% by mass, preferably 1 to 30% by mass, and more preferably 2 to 20% by mass.
[0035]
The number of isocyanate groups contained per molecule in the prepolymer (A) having an isocyanate group is usually 1 or more, preferably 1.5 to 3 on average, more preferably 1.8 to 2.5 on average. It is.
[0036]
As amines (B), diamine (B1), trivalent or higher polyamine (B2), aminoalcohol (B3), aminomercaptan (B4), amino acid (B5), and amino acids B1-B5 blocked (B6) etc. are mentioned.
[0037]
Examples of the diamine (B1) include aromatic diamines (phenylenediamine, diethyltoluenediamine, 4,4′-diaminodiphenylmethane, etc.); alicyclic diamines (4,4′-diamino-3,3′-dimethyldicyclohexylmethane, diamines). Cyclohexane, isophoronediamine, etc.); and aliphatic diamines (ethylenediamine, tetramethylenediamine, hexamethylenediamine, etc.) and the like. Examples of the trivalent or higher polyamine (B2) include diethylenetriamine and triethylenetetramine. Examples of amino alcohol (B3) include ethanolamine and hydroxyethylaniline. Examples of amino mercaptan (B4) include aminoethyl mercaptan and aminopropyl mercaptan. Examples of the amino acid (B5) include aminopropionic acid and aminocaproic acid. Examples of the B1 to B5 amino group blocked (B6) include ketimine compounds and oxazoline compounds obtained from the B1 to B5 amines and ketones (acetone, methyl ethyl ketone, methyl isobutyl ketone, etc.). Among these amines (B), preferred are B1 and a mixture of B1 and a small amount of B2.
[0038]
Furthermore, if necessary, the molecular weight of the urethane-modified polyester can be adjusted using an elongation terminator. Examples of the elongation terminator include monoamines (diethylamine, dibutylamine, butylamine, laurylamine, etc.), and those obtained by blocking them (ketimine compounds).
[0039]
The ratio of amines (B) is the equivalent ratio [NCO] / [NHx] of isocyanate groups [NCO] in the prepolymer (A) having isocyanate groups and amino groups [NHx] in amines (B). The ratio is usually 1/2 to 2/1, preferably 1.5 / 1 to 1 / 1.5, more preferably 1.2 / 1 to 1 / 1.2.
[0040]
The urethane-modified polyester (i) of the present invention is produced by a one-shot method, a prepolymer method or the like. The weight average molecular weight of the urethane-modified polyester (i) is usually 10,000 or more, preferably 20,000 to 10,000,000, more preferably 30,000 to 1,000,000. If it is less than 10,000, the hot offset resistance may be deteriorated. The number average molecular weight of the urethane-modified polyester is not particularly limited when the unmodified polyester (ii) is used, and may be a number average molecular weight that can be easily obtained to obtain the weight average molecular weight. (I) When used alone, the number average molecular weight is usually 20000 or less, preferably 1000 to 10000, and more preferably 2000 to 8000. If it exceeds 20000, the low-temperature fixability and glossiness when used in a full-color device may be deteriorated.
[0041]
In the present invention, a polyester resin not modified with a urethane bond and a polyester (i) modified with such a urethane bond may be used in combination as a binder resin. By using (ii) in combination, the low-temperature fixability and the glossiness when used in a full-color apparatus are improved, which may be preferable to single use.
[0042]
Examples of (ii) include the same polycondensates of polyol (1) and polycarboxylic acid (2) as in the polyester component (i) above, and preferred ones are also the same as (i). (Ii) is not limited to unmodified polyester, but may be modified with a chemical bond other than a urethane bond. It is preferable that (i) and (ii) are at least partially compatible with each other in terms of low-temperature fixability and hot offset resistance. Accordingly, the polyester component (i) and (ii) preferably have similar compositions.
[0043]
That is, examples of the polyvalent carboxylic acids used in the polyester resin include terephthalic acid, isophthalic acid, orthophthalic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, diphenic acid, sulfoterephthalic acid, 5-sulfoisophthalic acid, 4-sulfophthalic acid, 4-sulfonaphthalene-2,7 dicarboxylic acid, 5 [4-sulfophenoxy] isophthalic acid, sulfoterephthalic acid, and / or aromatic salts such as metal salts and ammonium salts thereof Acids, p- (oxyethoxy) benzoic acid aromatic oxycarboxylic acids such as p- (hydroxyethoxy) benzoic acid, succinic acid, adipic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid and other aliphatic dicarboxylic acids, fumaric acid, maleic acid , Itaconic acid, hexahydrophthalic acid, tetrahydride Unsaturated aliphatics such as phthalic acid and alicyclic dicarboxylic acids, etc., and polyvalent carboxylic acids such as trimellitic acid, trimesic acid, pyromellitic acid and other trivalent or higher polyvalent carboxylic acids It can be illustrated.
[0044]
Examples of the polyhydric alcohol used in the polyester resin include aliphatic polyhydric alcohols, alicyclic polyhydric alcohols, aromatic polyhydric alcohols, and the like. Aliphatic polyhydric alcohols include ethylene glycol, propylene glycol, 1,3-propanediol, 2,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, Neopentyl glycol, diethylene glycol, dipropylene glycol, 2,2,4-trimethyl-1,3-pentanediol, aliphatic diols such as polyethylene glycol, polypropylene glycol, polytetramethylene glycol, trimethylolethane, trimethylolpropane, Examples include triols and tetraols such as glycerin and pentaelsitol. Examples of alicyclic polyhydric alcohols include 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, spiroglycol, hydrogenated bisphenol A, ethylene oxide adduct and propylene oxide adduct of hydrogenated bisphenol A, tricyclodecane Examples include diol and tricyclodecane dimethanol.
[0045]
As aromatic polyhydric alcohols, para-xylene glycol, meta-xylene glycol, ortho-xylene glycol, 1,4-phenylene glycol, ethylene oxide adduct of 1,4-phenylene glycol, bisphenol A, ethylene oxide adduct of bisphenol A And propylene oxide adducts. Furthermore, examples of polyester polyols include lactone polyester polyols obtained by ring-opening polymerization of lactones such as ε-caprolactone.
[0046]
In order to obtain a low-oxidation resin, that is, in order to block the polar group at the end of the polyester polymer, it is preferable to introduce a monofunctional monomer into the polyester.
[0047]
Monofunctional monomers include benzoic acid, chlorobenzoic acid, bromobenzoic acid, parahydroxybenzoic acid, sulfobenzoic acid monoammonium salt, sulfobenzoic acid monosodium salt, cyclohexylaminocarbonylbenzoic acid, n-dodecylaminocarbonylbenzoic acid Acid, tertiary butylbenzoic acid, naphthalenecarboxylic acid, 4-methylbenzoic acid, 3-methylbenzoic acid, salicylic acid, thiosalicylic acid, phenylacetic acid, acetic acid, propionic acid, butyric acid, isobutyric acid, octanecarboxylic acid, lauric acid, stearyl Acids and monocarboxylic acids such as lower alkyl esters thereof, or monoalcohols such as aliphatic alcohols, aromatic alcohols and alicyclic alcohols can be used.
[0048]
When (ii) is contained, the mass ratio of (i) to (ii) is usually 5/95 to 80/20, preferably 5/95 to 30/70, more preferably 5/95 to 25/75. Particularly preferred is 7/93 to 20/80. When the mass ratio of (i) is less than 5%, the hot offset resistance is deteriorated, and it is disadvantageous in terms of both the crushing strength and the low-temperature fixability.
[0049]
The peak molecular weight of (ii) is usually 1000-30000, preferably 1500-10000, more preferably 2000-8000.
[0050]
The hydroxyl value of (ii) is preferably 5 or more, more preferably 10 to 120, and particularly preferably 20 to 80 from the viewpoint of achieving both crushing strength and low temperature fixability.
[0051]
The acid value of (ii) is usually 1-30, preferably 5-20. By having an acid value, it tends to be negatively charged.
[0052]
[Other binder resins that can be used in combination]
The binder resin, which is another constituent component of the toner used in the present invention, may be any resin that can form a dispersion of resin particles together with urethane-modified polyester in an aqueous medium. Any of curable resins may be used.
[0053]
For example, in addition to the above-described polyester resin, polyaddition or condensation resin typified by polyurethane resin, epoxy resin, polyol resin, and vinyl resin can be used.
[0054]
[Method for producing liquid in which resin particles are dispersed in aqueous medium]
Although the method of producing the dispersion liquid which disperse | distributes the resin particle performed by this invention in an aqueous medium is not specifically limited, The following method is mentioned.
[0055]
(1) When using a precursor (monomer, oligomer, etc.), the following methods are mentioned.
(A) A precursor (monomer, oligomer, etc.) or a solvent solution thereof is dispersed in an aqueous medium in the presence of an appropriate dispersant, and then cured by heating or adding a curing agent to obtain resin particles (A For producing an aqueous dispersion of
(B) A suitable emulsifier is dissolved in a precursor (monomer, oligomer, etc.) or a solvent solution thereof (preferably a liquid. It may be liquefied by heating), and then water is added to perform phase inversion emulsification. Method
(2) A method of directly producing an aqueous dispersion of the obtained resin particles by producing resin particles by a polymerization reaction such as a suspension polymerization method, an emulsion polymerization method, a seed polymerization method or a dispersion polymerization method using a monomer as a starting material
(3) A method in which a resin prepared in advance by a polymerization reaction (which may be any polymerization reaction mode such as polyaddition or condensation polymerization) is dispersed in an aqueous medium by the following method.
(A) A method in which the prepared resin is pulverized using a mechanical rotary type or jet type fine pulverizer and then classified to obtain resin particles and then dispersed in water in the presence of an appropriate dispersant.
(B) A method in which a resin solution obtained by dissolving a prepared resin in a solvent is sprayed in a mist to obtain resin particles, and then the resin particles are dispersed in water in the presence of an appropriate dispersant.
(C) Add a poor solvent to the resin solution obtained by dissolving the prepared resin in a solvent, or cool the resin solution previously dissolved in the solvent to precipitate resin particles, and then remove the solvent to remove the resin particles. A method of dispersing the resin particles in water in the presence of a suitable dispersant after being obtained
(D) A method in which a resin solution obtained by dissolving a prepared resin in a solvent is dispersed in an aqueous medium in the presence of an appropriate dispersant, and the solvent is removed by heating or reducing pressure.
(E) A method in which a suitable emulsifier is dissolved in a resin solution obtained by dissolving the prepared resin in a solvent, and then water is added to perform phase inversion emulsification.
As the emulsifier or dispersant used in combination with the above method, known surfactants, water-soluble polymers and the like can be used. Moreover, a solvent, a plasticizer, etc. can be used together as an auxiliary agent for emulsification or dispersion. Specific examples include those disclosed in paragraphs 0036 to 0062 of JP-A-2002-284881.
[0056]
[Method for producing toner particles (colored particles)]
Next, a toner manufacturing method according to the present invention will be described. In the present invention, toner constituents such as a binder resin, a colorant, a release agent, or a charge control agent are dispersed in an aqueous medium to produce a fine particle dispersion of each toner constituent, and the fine particles in the fine particle dispersion are produced. The toner particles are formed through a step of aggregating the toner particles.
[0057]
Aggregated particles produced by these methods are referred to as colored particles, and those obtained by adding an external additive to the particles may be referred to as toner particles or toner. However, in the description of the present invention, when there is no need to distinguish between them, toner particles or toner including the colored particles may be referred to.
[0058]
As a specific method for atomizing each toner component in an aqueous medium, as described above for the binder resin, other toner components are also dissolved in an organic solvent, and the dispersed phase is dissolved in the aqueous medium. The thing which passes through the process of forming the oil phase which becomes.
[0059]
The solution dissolved in the organic solvent is stirred with a normal impeller, heat-treated as necessary, dissolved and dispersed with a ball mill, sand mill, homogenizer, etc., and emulsified and dispersed in an aqueous medium. . At that time, an emulsifier such as a homomixer (manufactured by Special Machine Engineering Co., Ltd.), Ebara Milder (manufactured by Ebara Seisakusho), Claremix (manufactured by M Technique Co., Ltd.) or the like is used.
[0060]
By controlling the concentration of the emulsifier, the concentration of the toner component with respect to the organic solvent, the ratio of the oily phase in which the aqueous medium and the toner component are dispersed, the number of revolutions and the time during emulsification dispersion, the desired droplet size And particle size distribution. It is preferable to emulsify and disperse to 1/2 to 1/100 of the target toner particle diameter.
[0061]
The mass ratio between each toner component and the organic solvent is preferably selected between 1:10 and 1: 1, and the mass ratio between the aqueous medium and the oily phase in which the solution is dispersed is preferably selected between 10: 1 and 1: 1. Of course, it may be outside this range.
[0062]
As an aqueous medium, water or an organic solvent such as methanol or ethanol that can be partially mixed with water, ethanol such as ethanol, ketone such as acetone or methyl ethyl ketone, or ester such as ethyl acetate is used in combination with water. be able to.
[0063]
The organic solvent for dissolving and dispersing each toner component is not particularly limited as long as it is insoluble or hardly soluble in water and partially soluble and dissolves the toner component. For example, toluene, xylene, Methyl acetate, ethyl acetate, methyl ethyl ketone, methyl isobutyl ketone and the like can be used alone or in combination of two or more. In particular, aromatic solvents such as toluene and xylene and acetates are preferred.
[0064]
Anionic surfactants such as alkylbenzene sulfonates, α-olefin sulfonates, phosphates, etc. as dispersants for emulsifying and dispersing the oily phase, which is a toner component, in an aqueous medium to a desired particle size Can also be used.
[0065]
Further, the dispersed droplets may be stabilized by a polymer protective colloid. For example, acrylic acid, methacrylic acid, α-cyanoacrylic acid, α-cyanomethacrylic acid, itaconic acid, crotonic acid, fumaric acid, maleic acid or maleic anhydride and other (meth) acrylic monomers containing hydroxyl groups Such as β-hydroxyethyl acrylate, β-hydroxyethyl methacrylate, β-hydroxypropyl acrylate, β-hydroxypropyl methacrylate, γ-hydroxypropyl acrylate, γ-hydroxypropyl methacrylate, 3-chloroacrylate 2-hydroxypropyl, 3-chloro-2-hydroxypropyl methacrylate, diethylene glycol monoacrylate, diethylene glycol monomethacrylate, glycerol monoacrylate, glycerol monomethacrylate, N -Methylol acrylamide, N-methylol methacrylamide, etc., vinyl alcohol or ethers with vinyl alcohol, such as vinyl methyl ether, vinyl ethyl ether, vinyl propyl ether, etc., or esters of compounds containing vinyl alcohol and carboxyl groups, such as Vinyl acetate, vinyl propionate, vinyl butyrate, acrylamide, methacrylamide, diacetone acrylamide or their methylol compounds, acid chlorides such as acrylic acid chloride, methacrylic acid chloride, pinylpyridine, vinylpyrrolidone, vinylimidazole, ethyleneimine, etc. Homopolymers or copolymers such as those having nitrogen atoms or heterocyclic rings thereof, polyoxyethylene, polyoxypropylene, polymers Oxyethylene alkylamine, polyoxypropylene alkylamine, polyoxyethylene alkylamide, polyoxypropylene alkylamide, polyoxyethylene nonyl phenyl ether, polyoxyethylene lauryl phenyl ether, polyoxyethylene stearyl phenyl ester, polyoxyethylene nonylphenyl Polyoxyethylenes such as esters, celluloses such as methyl cellulose, hydroxyethyl cellulose, and hydroxypropyl cellulose can be used.
[0066]
Next, in order to remove the organic solvent from the emulsified dispersion, it is possible to employ a method in which the entire system is gradually heated to completely evaporate and remove the organic solvent in the droplets. At that time, it is preferable to carry out under reduced pressure because the heating temperature can be lowered. This is to prevent toner components such as a release agent from dissolving in an organic solvent and to prevent abnormal aggregation, association and coalescence of the emulsified dispersion due to heating.
[0067]
The organic solvent removal step may be performed before the aggregation step or after the aggregation step. If the organic solvent is removed before the aggregation step, fusion and coalescence of the fine particles after aggregation can be promoted.
[0068]
Another treatment method for those dissolved in an organic solvent is to spray the emulsified dispersion into a dry atmosphere to completely remove the water-insoluble organic solvent in the droplets to form toner fine particles, which are combined with an aqueous dispersion. There is a method of evaporating and removing the agent.
[0069]
As a dry atmosphere in which the emulsified dispersion is sprayed, a gas obtained by heating air, nitrogen, carbon dioxide gas, combustion gas, or the like, particularly various air streams heated to a temperature equal to or higher than the boiling point of the highest boiling solvent used are generally used. Sufficient quality can be obtained with a short processing time such as spray dryer, belt dryer, rotary kiln.
[0070]
As agglomeration methods, when fine particles are dispersed in water in a charged state, a method of agglomerating particles by compressing the electric double layer by pouring electrolyte or the like, adsorbing high molecular weight water-soluble polymer between particles A method of aggregating the particles, a method of charging the surface active agent or dispersant that is oppositely charged to neutralize the surface charge of the fine particles and aggregating the particles, and counteracting the adsorbed surfactant or dispersant For example, a method of changing the solubility of the surfactant or dispersant in the aqueous medium to weaken dispersion stability and agglomerating may be employed.
[0071]
At that time, it is agglomerated with a release agent (wax) emulsion and resin fine particles having polar groups to give the manufactured toner a release property at the time of fixing, to enhance triboelectric chargeability, and to a glass transition point. By disposing the high-resin fine particles relatively outside the toner, blocking of the toners during high-temperature storage can be prevented.
[0072]
Examples of the flocculant used include sodium sulfate, ammonium sulfate, potassium sulfate, magnesium sulfate, sodium phosphate, sodium dihydrogen phosphate, disodium hydrogen phosphate, ammonium chloride, calcium chloride, cobalt chloride, and strontium chloride. General inorganic or organic water-soluble salts represented by cesium chloride, barium chloride, nickel chloride, magnesium chloride, rubidium chloride, sodium chloride, potassium chloride, sodium acetate, ammonium acetate, potassium acetate, sodium benzoate, etc. Can be used.
[0073]
The concentration of these electrolytes ranges from 0.01 to 2.0 mol / l, more preferably from 0.1 to 1.0 mol / l, and even more preferably from 0.2 to 0.8 mol / l when a monovalent electrolyte is used. preferable. Furthermore, when a polyvalent electrolyte is used, the amount added may be smaller.
[0074]
In the case of a surfactant, those exemplified above, and in the case of a polymer-based aggregating agent, among those that form the above-mentioned polymer protective colloid, those of ultra high molecular weight are particularly suitable. In addition, as a substance to coagulate by coexisting in an aqueous medium, it is possible to use water-soluble organic compounds such as ethanol, butanol, isopropanol, ethyl cellosolve, butyl cellosolve, dioxane, tetrahydrofuran, acetone, methyl ethyl ketone, etc. it can.
[0075]
Furthermore, by heating the dispersion after aggregation, the fine particles can be fused together to adjust the shape of the toner to be produced. The particles are spheroidized by the interfacial tension, and the particle shape can be arbitrarily adjusted from spherical to indeterminate depending on the heating temperature, toner viscosity, presence of organic solvent, and the like.
[0076]
The obtained dispersion of aggregated particles is sprayed in a dry atmosphere to completely remove the water-insoluble organic solvent remaining in the aggregated particles to form toner fine particles, and the aqueous dispersant is evaporated together. It is also possible to remove it. As a dry atmosphere in which a dispersion of aggregated particles is sprayed, a gas obtained by heating air, nitrogen, carbon dioxide gas, combustion gas, etc., in particular, various air currents heated to a temperature higher than the boiling point of the highest boiling solvent used are generally used. To do. Sufficient quality can be obtained with a short processing time such as spray dryer, belt dryer, rotary kiln. If the operation of re-dispersing (reslurry) is repeated by separating the liquid into solid and liquid before drying and redispersing (reslurry), the used dispersant and emulsifier can be almost removed.
[0077]
Generally, the particle size distribution after the aggregation operation is narrow and can be used as a toner as it is. However, when coarse particles are slightly mixed, classification operation may be performed after obtaining a powder after drying, and it is preferable in terms of efficiency to perform in a liquid.
[0078]
By mixing the resulting dried toner powder with dissimilar particles such as release agent fine particles, charge control fine particles, fluidizing agent fine particles, and colorant fine particles, or by giving mechanical impact force to the mixed powder By immobilizing and fusing on the surface, it is possible to prevent detachment of the foreign particles from the surface of the resulting composite particle.
[0079]
Specific means include a method of applying an impact force to the mixture by blades rotating at high speed, a method of injecting and accelerating the mixture in a high-speed air stream, and causing particles or composite particles to collide with an appropriate collision plate, etc. is there. As equipment, Ong mill (manufactured by Hosokawa Micron Co., Ltd.), I-type mill (manufactured by Nippon Pneumatic Co., Ltd.) has been modified to reduce pulverization air pressure, hybridization system (manufactured by Nara Machinery Co., Ltd.), kryptron system (Made by Kawasaki Heavy Industries, Ltd.), automatic mortar and the like.
[0080]
[Colorant]
As the colorant used in the toner according to the present invention, all known dyes and pigments can be used. Specifically, carbon black, nigrosine dye, iron black, naphthol yellow S, Hansa yellow (10G, 5G, G), yellow iron oxide, ocher, titanium yellow, polyazo yellow, oil yellow, Hansa yellow (GR, A, RN, R), pigment yellow L, benzidine yellow (G, GR), permanent yellow (NCG), Vulcan Fast Yellow (5G, R), Tartrazine Lake, Quinoline Yellow Lake, Anthrazan Yellow BGL, Isoindolinone Yellow, Bengala, Permanent Red 4R, Para Red, Faise Red, Parachlor Ortho Nitroaniline Red, Resole Fast Scarlet G, Brilliant Fass Scarlet, Brilliant Carmine BS, Permanent Red (F2R, F4R, FRL, FRLL, F4RH), Fast Scarlet VD, Belkan Fast Rubin B, Brilliant Scarlet G, Resol Rubin GX, Permanent Red F5R, Brilliant Carmine 6B, Pigment Scarlet 3B, Bordeaux 5B, Toluidine Maroon, Permanent Bordeaux F2K, Helio Bordeaux BL, Bordeaux 10B, Bon Maroon Light, Bon Maroon Medium, Eosin Lake, Rhodamine Lake B, Rhodamine Lake Y, Alizarin Lake, Thioindigo Red B, Thioindigo Maroon, Oil Red, quinacridone red, pyrazolone red, polyazo red, chrome vermillion, benzidine orange, perinone Range, Oil Orange, Cobalt Blue, Cerulean Blue, Alkaline Blue Lake, Peacock Blue Lake, Victoria Blue Lake, Metal Free Phthalocyanine Blue, Phthalocyanine Blue, Fast Sky Blue, Indanthrene Blue (RS, BC), Indigo, Ultramarine Blue, Bituminous Blue , Anthraquinone Blue, Fast Violet B, Methyl Violet Lake, Cobalt Purple, Manganese Purple, Dioxane Violet, Anthraquinone Violet, Chrome Green, Zinc Green, Chromium Oxide, Pyridian, Emerald Green, Pigment Green B, Naphthol Green B, Green Gold, Acid Green lake, malachite green lake, phthalocyanine green, anthraquinone green, titanium oxide, zinc white, litho Bonn and mixtures thereof can be used.
[0081]
The amount used is generally 1 to 20 parts by mass with respect to 100 parts by mass of the binder resin (binder resin).
[0082]
[Release agent (wax)]
In the present invention, it is preferable to include a wax in the toner in order to impart an appropriate release property to the developer. The wax has a melting point of 40 to 120 ° C., and preferably 50 to 110 ° C.
[0083]
It has been confirmed that by having the melting point within the above range, good fixability can be obtained even when the fixing temperature is set to a low temperature, and good offset resistance and durability can be obtained.
[0084]
The melting point of the wax can be obtained by differential scanning calorimetry (DSC). That is, the melting peak value when a sample of several mg is ripened at a constant temperature increase rate, for example, (10 ° C./min) is defined as the melting point.
[0085]
Examples of the release agent (wax) that can be used in the present invention include solid paraffin wax, microcrystalline wax, rice wax, fatty acid amide wax, fatty acid wax, aliphatic monoketone, fatty acid metal salt wax, and fatty acid. Examples thereof include ester waxes, partially saponified fatty acid ester waxes, silicone varnishes, higher alcohols, and carnauba waxes.
[0086]
Furthermore, the synthetic ester compound represented by following General formula (2) is mentioned.
General formula (2): R₁-(OCO-R₂)_n
(Wherein R₁And R₂Each represents a hydrocarbon group having 1 to 40 carbon atoms which may have a substituent, and n is an integer of 1 to 4. )
In the present invention, toner particles may be formed using a dispersion obtained by heating and stirring a wax in an aqueous medium using a surfactant or a dispersant described later. In this case, for example, a wax emulsion prepared by emulsifying wax can be prepared and added together with the colorant dispersion when the resin particles are aggregated.
[0087]
[Charge control agent]
The toner of the present invention may contain a charge control agent as necessary.
[0088]
As the charge control agent, all known ones can be used, for example, fluorine activators, salicylic acid metal salts, metal salts of salicylic acid derivatives, and the like. Specifically, Bontron 03 of a nigrosine dye, Bontron P-51 of a quaternary ammonium salt, Bontron S-34 of an azo metal complex compound, E-82 of an oxynaphthoic acid metal complex, E of a salicylic acid metal complex -84, phenolic condensate E-89 (above, Orient Chemical Industries), quaternary ammonium salt molybdenum complex TP-302, TP-415 (above, Hodogaya Chemical Co., Ltd.), quaternary Copy charge PSY VP 2038 of ammonium salt, copy blue PR of triphenylmethane derivative, copy charge of quaternary ammonium salt NEGVP 2036, copy charge NX VP434 (manufactured by Hoechst), LRA-901, LR-147 which is a boron complex (Nippon Carlit), copper phthalocyanine, perylene, kina Pyrrolidone, azo pigments, sulfonate group, carboxyl group, and polymer compounds having a functional group such as a quaternary ammonium salt. Among these, azo metal complex compounds are preferable, and for example, those disclosed in paragraphs 0009 to 0012 of JP-A-2002-351150 are preferably used.
[0089]
In the present invention, the amount of charge control agent used is determined uniquely by the type of binder resin, the presence or absence of additives used as necessary, and the toner production method including the dispersion method, and is uniquely limited. Although it is not a thing, Preferably it is used in 0.1-20 mass parts with respect to 100 mass parts of binder resin. Preferably, the range of 0.2-5 mass parts is good.
[0090]
In the present invention, it is preferable to add a charge control agent in the vicinity of the toner particle surface. That is, by adding the toner particles in the vicinity of the toner particle surface, the toner particles can be effectively charged, and the charge control agent can be added so as not to expose the toner particle surface to ensure the fluidity of the toner. is there.
[0091]
As a specific content method, for example, there is a method of controlling the amount of charge control agent added to the resin particles constituting the toner particles. That is, a method in which a large amount of charge control agent is added to the resin particles constituting the vicinity of the surface of the toner particles, and the resin particles are aggregated so as to form the toner particle surface with the resin particles to which no charge control agent is added, And a method in which the resin particles containing the charge control agent are aggregated and then encapsulated with a resin component not containing the charge control agent on the surface of the aggregated particles.
[0092]
As a method of addition into the resin particles, it is preferable to add the binder resin into the solution when dissolved in an organic solvent, but when emulsified in an aqueous medium, the oil phase is eluted from the dispersed phase to the aqueous phase side. When it is removed or detached, it may be added to the aqueous phase side and incorporated into the toner during the aggregation process or drying process.
[0093]
(External additive)
As the external additive for assisting the fluidity, developability and chargeability of the toner particles obtained in the present invention, inorganic fine particles can be preferably used. The primary particle diameter of the inorganic fine particles is preferably 5 to 2000 nm, and particularly preferably 50 to 200 nm. The specific surface area according to the BET method is 20 to 500 m.²/ G is preferable.
[0094]
The use ratio of the inorganic fine particles is preferably 0.01 to 5% by mass of the toner, and particularly preferably 0.01 to 2.0% by mass. Specific examples of the inorganic fine particles include, for example, silica, alumina, titanium oxide, barium titanate, magnesium titanate, calcium titanate, strontium titanate, zinc oxide, tin oxide, quartz sand, clay, mica, wollastonite, diatomaceous earth. Soil, chromium oxide, cerium oxide, pengala, antimony trioxide, magnesium oxide, zirconium oxide, barium sulfate, barium carbonate, calcium carbonate, silicon carbide, silicon nitride, etc. Fine particles are preferred.
[0095]
In addition, polymer fine particles, such as polystyrene obtained by soap-free emulsion polymerization, suspension polymerization, and dispersion polymerization, methacrylic acid ester, acrylic acid ester copolymer, polycondensation system such as silicone, benzoguanamine, nylon, thermosetting Examples thereof include polymer particles made of a resin.
[0096]
Such a fluidizing agent performs surface treatment to increase hydrophobicity, and can prevent deterioration of fluidity characteristics and charging characteristics even under high humidity. For example, silane coupling agents, silylating agents, silane coupling agents having an alkyl fluoride group, organic titanate coupling agents, aluminum coupling agents, silicone oils, modified silicone oils and the like are preferable surface treatment agents. .
[0097]
Examples of the cleaning property improver for removing the developer after transfer remaining on the photoreceptor or the primary transfer medium include, for example, zinc stearate, calcium stearate, stearic acid and other fatty acid metal salts such as polymethyl methacrylate fine particles, polystyrene fine particles, etc. And polymer fine particles produced by soap-free emulsion polymerization. The polymer fine particles preferably have a relatively narrow particle size distribution and a volume average particle size of 0.01 to 1 μm.
[0098]
[Toner shape]
As for the shape of the toner of the present invention, when 2000 or more toner particles having a particle diameter of 1 μm or more are measured, the average value of circularity (shape factor) represented by the following formula is preferably 0.94 to 0.98, and more Preferably it is 0.94-0.97.
[0099]

Here, the equivalent circle is a circle having the same area as the toner particle projection image, and the equivalent circle diameter is the diameter of the equivalent circle.
[0100]
In addition, as a measuring method of the said circularity, it can measure by FPIA-2000 (made by Sysmec). At this time, the equivalent circle diameter is defined by the following equation.
[0101]
Equivalent circle diameter = 2 × (projection area of particle / π)^1/2
The toner of the present invention has an average equivalent circle diameter of 2.6 to 7.4 μm, and an inclination of circularity with respect to the equivalent circle diameter is −0.050 to −0.010. Features. More preferably, the average value of the equivalent circle diameter is 3.4 to 6.6 μm, and the inclination of the circularity with respect to the equivalent circle diameter is −0.040 to −0.020.
[0102]
The inclination of the equivalent circle diameter is measured by measuring the equivalent circle diameter of the toner particles with a flow particle image analyzer FPIA-2000, and the relationship with the corresponding circularity is represented by the horizontal axis: equivalent circle diameter (μm) -vertical. Axis: Draw as a degree of circularity, and see the linear correlation (y = αx + b), α is the slope of the equivalent circle diameter.
[0103]
At this time, from the viewpoint of improving the uniformity of charging and the uniformity of halftone, R²(R squared) is preferably 0.35 to 0.95. Here, R is represented by the following formula (I).
[0104]
Formula (I) R = A / B
In the formula, A and B each represent the following formula.
[0105]
A = nΣXY− (ΣXΣY)
B = (nΣX²-(ΣX)²) × ((nΣY²)-(ΣY)²)
X represents an equivalent circle diameter (μm), and Y represents circularity.
[0106]
In order to produce a toner having an equivalent circle diameter gradient, small-sized spherical toner particles may be mixed with irregularly-shaped toner particles having a slightly larger particle diameter. Alternatively, when making toner particles by associating resin particles, after adding an aggregating agent in the associating step, the shape of the stirring blade is appropriately selected, the stirring strength is controlled, and a condition in which shearing force is easily applied to larger particles, A method of shifting to a filtration and drying process may also be used. Preferably, the toner production apparatus and the flow type particle image analysis apparatus described above are connected in-line, and production is performed while adjusting the conditions as appropriate while monitoring the inclination α.
[0107]
Preferably, after adding a stopping agent for stopping salting out / fusion, the toner particles are further grown by 0.2 to 1.0 μm, for example, by re-adding the salting-out agent or adding a surfactant. It can be controlled to enter.
[0108]
Further, in the present invention, from the viewpoint of making the toner charge amount distribution suitable, the equivalent circle diameter d at 10% by number is accumulated from the small particle diameter side of the toner particles._TenAnd the equivalent circle diameter d at 90% by number.₉₀Ratio to d₉₀/ D_TenIs preferably 1.2 to 2.0. Especially preferably, it is 1.3-1.8. If it is within this range, it is possible to control the dustiness of the dots, the halftone uniformity is high, and a high-quality image can be obtained.
[0109]
(Developer)
The toner of the present invention can be used as a one-component developer or a two-component developer.
[0110]
When used as a one-component developer, a non-magnetic one-component developer or a magnetic one-component developer containing 0.1 to 0.5 μm magnetic particles in the toner can be used. it can.
[0111]
The toner of the present invention can be used as a two-component developer by mixing with a carrier that is magnetic particles. As the carrier, conventionally known materials such as metals such as iron, ferrite, and magnetite, and alloys of these metals with metals such as aluminum and lead can be used. Among these, ferrite particles are preferable. The volume average particle size of the carrier is preferably 15 to 100 μm, more preferably 25 to 80 μm.
[0112]
The volume average particle diameter of the carrier can be typically measured by a laser diffraction type particle size distribution measuring apparatus “Heros” (manufactured by Sympathic) equipped with a wet disperser.
[0113]
As the carrier, one obtained by coating magnetic particles with a resin, or a so-called resin-dispersed carrier in which magnetic particles are dispersed in a resin can also be used. Examples of the coating resin include olefin resins, styrene resins, styrene-acrylic resins, silicone resins, ester resins, and fluorine-containing polymer resins. Examples of the resin for constituting the resin-dispersed carrier include styrene-acrylic resin, polyester resin, fluorine resin, and phenol resin.
[0114]
(Image forming method)
Next, an image forming apparatus used in the image forming method using the toner of the present invention will be described.
[0115]
FIG. 1 is a block diagram showing an example of an apparatus used in the image forming method of the present invention. Reference numeral 34 denotes a photosensitive drum as a member to be charged, which is formed by forming an organic photoconductor (OPC) as a photosensitive layer on the outer peripheral surface of an aluminum drum base, and rotates at a predetermined speed in the direction of the arrow. .
[0116]
In FIG. 1, exposure light is emitted from a semiconductor laser light source 31 based on information read by a document reading device (not shown). This is distributed in a direction perpendicular to the paper surface of FIG. 1 by the polygon mirror 32 and irradiated onto the surface of the photoreceptor through an fθ lens 33 that corrects image distortion to form an electrostatic latent image. The photosensitive drum 34 is uniformly charged in advance by a charger 35 and starts rotating clockwise in accordance with the timing of image exposure.
[0117]
The electrostatic latent image on the surface of the photosensitive drum is developed by the developing unit 36, and the formed developed image is transferred to a recording medium (also referred to as a transfer material, transfer paper, or recording paper) P that has been conveyed in time. Transfer is performed by the action of the vessel 37. Further, the photosensitive drum 34 and the transfer material 38 are separated by a separator (separation pole) 39, and the developed image is transferred and supported on the transfer material 38, and is guided to the fixing device 40 and fixed.
[0118]
Untransferred toner or the like remaining on the surface of the photosensitive member is cleaned by a cleaning device 41 of a cleaning blade method, the residual charge is removed by pre-charge exposure (PCL) 42, and again by the charger 35 for the next image formation. Uniformly charged.
[0119]
The exposure is particularly preferably digital image exposure in the present invention, but may be analog image exposure.
[0120]
The present invention can also be used in an electrophotographic image forming apparatus, particularly an apparatus for forming an electrostatic latent image on a photosensitive member with a modulated beam modulated with digital image data from a computer or the like.
[0121]
FIG. 2 is a structural sectional view showing a digital image forming apparatus applied to the toner of the present invention.
[0122]
In FIG. 2, an image forming apparatus 101 processes an automatic document feeder (commonly called ADF) A, a document image reading unit B for reading a document image conveyed by the automatic document feeder, and a read document image. An image control board C, a writing unit D including a writing unit 112 for writing on a photosensitive drum 34 as an image carrier in accordance with data after image processing, a charging drum 35 and a magnetic brush around the photosensitive drum 34 Image forming unit E including image forming means such as developing unit 36, transfer unit 37, separator 39, and cleaning unit 41, and a storage unit for paper feed trays 122 and 124 for storing recording paper P F.
[0123]
The automatic document feeder A has a document placing table 126, and a document transport processing unit 128 including a roller group including a roller R1 and a switching unit for appropriately switching a document moving path (no reference symbol). .
[0124]
The document image reading unit B is below the platen glass G, and is provided with two mirror units 130 and 131 that can reciprocate while maintaining the optical path length, a fixed imaging lens (hereinafter simply referred to as a lens) 133, and a line-shaped image sensor. The writing unit D includes a laser light source 31, a polygon mirror (polarizer) 32, and the like.
[0125]
When viewed from the moving direction of the recording paper P as a transfer material, R10 shown on the front side of the transfer device 37 is a registration roller, and 40 is shown on the downstream side of the separator 39 and is a fixing device.
[0126]
In the embodiment, the fixing device 40 includes a roller having a built-in heating source and a pressure roller that rotates while being pressed against the roller.
[0127]
Z is a cleaning means for the fixing device 40, and a cleaning web provided so as to be able to be wound is a main element.
[0128]
One of the documents (not shown) placed on the document table 126 is conveyed by the document conveyance processing unit 128, and exposure by the exposure means L is performed while passing under the roller R1.
[0129]
The reflected light from the document is imaged on the CCD 135 through the mirror units 130 and 131 and the lens 133 at a fixed position and read.
[0130]
The image information read by the document image reading unit B is processed by the image processing means, encoded, and stored in a memory provided on the image control board C.
[0131]
The image data is called in response to image formation, and the laser light source 31 in the writing unit D is driven according to the image data, and exposure is performed on the photosensitive drum 34.
[0132]
In recent years, in the field of electrophotography where an electrostatic latent image is formed on a photosensitive member and the latent image is developed to obtain a visible image, image quality can be improved, converted, edited, etc., and high-quality image formation is possible. Research and development of image forming methods adopting various digital methods have been actively conducted.
[0133]
As a scanning optical system that optically modulates with a digital image signal from a computer or a copy original employed in the image forming method and apparatus, an optical optical modulator is interposed in the laser optical system, and the optical modulation is performed by the acoustooptic modulator. There is an apparatus that directly modulates the laser intensity using a semiconductor laser, and forms a dot image by spot exposure on a uniformly charged photoconductor from these scanning optical systems.
[0134]
The beam irradiated from the scanning optical system described above has a circular or elliptical luminance distribution that approximates a normal distribution with a skirt extending from side to side. For example, in the case of a laser beam, the main scanning direction or One or both in the sub-scanning direction is an extremely narrow circle or ellipse of 20 to 100 μm.
[0135]
The present invention is applied not only to monochrome images but also to image formation for obtaining color images. For example, a plurality of image forming units are provided, and each image forming unit has a visible image (toner having a different color). An image forming method for forming a toner image by forming an image.
[0136]
The toner of the present invention is suitably used in an image forming method including a step of fixing an image forming support on which a toner image is formed between a heating roller and a pressure roller constituting a fixing device. .
[0137]
FIG. 3 is a cross-sectional view showing an example of a fixing device used in the image forming method using the toner of the present invention. The fixing device 40 shown in FIG. 3 includes a heating roller 71 and a pressure roller 72 in contact with the heating roller 71. And. In FIG. 3, T is a toner image formed on the recording medium P.
[0138]
The heating roller 71 has a coating layer 82 made of a fluororesin or an elastic body formed on the surface of the cored bar 81 and includes a heating member 75 made of a linear heater.
[0139]
The cored bar 81 is made of metal and has an inner diameter of 10 to 70 mm. Although it does not specifically limit as a metal which comprises the metal core 81, For example, metals, such as iron, aluminum, copper, or these alloys can be mentioned.
[0140]
The thickness of the cored bar 81 is 0.1 to 15 mm, and is determined in consideration of the balance between the demand for energy saving (thinning) and the strength (depending on the constituent materials). For example, in order to maintain the same strength as that of a cored bar made of iron of 0.57 mm with a cored bar made of aluminum, the wall thickness needs to be 0.8 mm.
[0141]
Examples of the fluororesin constituting the coating layer 82 include PTFE (polytetrafluoroethylene) and PFA (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer).
[0142]
The thickness of the coating layer 82 made of a fluororesin is 10 to 500 μm, preferably 20 to 400 μm.
[0143]
As the heating member 75, a halogen heater can be preferably used.
The pressure roller 72 is formed by forming a coating layer 84 made of an elastic body on the surface of the cored bar 83. The elastic body constituting the covering layer 84 is not particularly limited, and examples thereof include various soft rubbers and sponge rubbers such as urethane rubber and silicone rubber. The silicone rubber exemplified as constituting the covering layer 84 and It is preferable to use silicone sponge rubber.
[0144]
The Asker C hardness of the elastic body constituting the coating layer 84 is less than 80 °, preferably less than 70 °, and more preferably less than 60 °.
[0145]
Moreover, the thickness of the coating layer 84 is 0.1-30 mm, Preferably it is 0.1-20 mm.
[0146]
Although it does not specifically limit as a material which comprises the metal core 83, Metals, such as aluminum, iron, copper, or those alloys can be mentioned.
[0147]
The contact load (total load) between the heating roller 71 and the pressure roller 72 is usually 40 to 350 N, preferably 50 to 300 N, and more preferably 50 to 250 N. This contact load is defined in consideration of the strength of the heating roller 71 (thickness of the cored bar 81). For example, in a heating roller having a cored bar made of iron of 0.3 mm, the contact load should be 250 N or less. Is preferred.
[0148]
From the viewpoint of offset resistance and fixing property, the nip width is preferably 4 to 10 mm, and the surface pressure of the nip is 0.6 × 10 6.^FivePa ~ 1.5 × 10^FivePa is preferred.
[0149]
An example of fixing conditions by the fixing device shown in FIG. 3 is that the fixing temperature (surface temperature of the heating roller 71) is 150 to 210 ° C., and the fixing linear velocity is 230 to 900 mm / sec.
[0150]
The fixing device may be used with a cleaning mechanism. As a cleaning method, a method of supplying various silicone oils to the fixing film, or a method of cleaning with a pad, roller, web or the like impregnated with various silicone oils is used.
[0151]
As the silicone oil, polydimethylsiloxane, polymethylphenylsiloxane, polydiphenylsiloxane, or the like can be used. Furthermore, siloxane containing fluorine can also be suitably used.
[0152]
Further, the image forming apparatus used in the present invention may have a mechanism for toner recycling that recycles and uses untransferred toner remaining on the surface of the photoreceptor. Although the method for recycling the toner is not particularly limited, for example, the toner collected by the cleaning unit is mixed with a replenishing toner hopper, a developing device or a replenishing toner by an intermediate chamber by a conveying conveyor or a conveying screw. And a method of supplying to the developing device. Preferably, a method of returning directly to the developing device or a method of supplying the replenishing toner and the recycled toner in the intermediate chamber and supplying them can be exemplified.
[0153]
Next, the nonmagnetic one-component developing method according to the present invention will be specifically described.
FIG. 4 is a schematic cross-sectional view of the developing unit 36 used in the image forming method of nonmagnetic one-component development.
[0154]
In FIG. 4, the nonmagnetic one-component toner 416 built in the toner tank 417 is forcibly conveyed and supplied onto a sponge roller 414 as a toner replenishment auxiliary member by a stirring blade 415 as a toner replenishment auxiliary member. The toner thus incorporated on the sponge roller is conveyed onto a rubber roller 412 as a toner conveying member by the rotation of the roller 414 in the direction of the arrow, and electrostatically and physically on the surface by friction with the roller 412. Adsorbed. On the other hand, the toner adhering to the rubber roller 412 is uniformly thinned and frictionally charged by the rotation of the roller 412 in the arrow direction and the steel elastic blade 413 as a toner layer thickness regulating member. Next, the latent image is developed on the toner thin layer on the rubber roller 412 by contacting or approaching the surface of the photosensitive drum 34 as an electrostatic latent image carrier.
[0155]
Needless to say, the non-magnetic one-component developer used in the method of the present invention is not limited to that shown in FIG.
[0156]
【Example】
Hereinafter, the present invention will be further described with reference to examples, but the present invention is not limited thereto. In the following description, “part” means part by mass, and “%” means mass%.
[0157]
Example 1
[Preparation of resin solution 1 (polyester resin)]
343 parts of bisphenol A ethylene oxide 2-mole adduct, 166 parts of isophthalic acid and 2 parts of dibutyltin oxide are placed in a reaction vessel equipped with a cooling tube, a stirrer and a nitrogen introduction tube, and reacted at 230 ° C. for 8 hours at normal pressure. After further reaction under reduced pressure conditions of 1.33-1.99 Pa (10-15 mmHg) for 5 hours, the reaction mixture was cooled to 110 ° C., 17 parts of isophorone diisocyanate was added in toluene, and the reaction was performed at 110 ° C. for 5 hours. Then, the solvent was removed to obtain [urethane modified polyester (1)] having a weight average molecular weight of 72,000 and a free isocyanate content of 0.7%.
[0158]
In the same manner as above, 570 parts of bisphenol A ethylene oxide 2-mole adduct and 217 parts of terephthalic acid were polycondensed at 230 ° C. for 6 hours under normal pressure to give a number average molecular weight of 2,400, a hydroxyl value of 51, and an acid value of 5 [Polyester (2)] was obtained.
[0159]
200 parts of [urethane-modified polyester (1)] and 800 parts of [polyester (2)] were dissolved and mixed in 2,000 parts of ethyl acetate to obtain [resin solution 1]. In addition, Tg of the resin component in the resin solution 1 was 64 degreeC.
[0160]
[Production of toner]
[Resin solution 1] (Tg of resin component: 64 ° C.) 100 parts
Pigment Blue 15: 3 hydrous cake
(Solid content in water-containing cake 50%) 12 parts
Charge control agent (Spiron Black TRH, Hodogaya Chemical Co., Ltd.) 1 part
Carnauba wax 10 parts
The above material was dissolved and dispersed by rolling a ball mill filled with zirconia beads in 200 parts of toluene to prepare an oil phase serving as a dispersed phase.
[0161]
Separately
700 parts of ion exchange water
Sodium dodecylbenzenesulfonate 1 part
Was dispersed by stirring to prepare an aqueous phase to be a continuous phase. The oil phase was introduced into the aqueous phase while stirring with a homomixer (made by Tokushu Kika Kogyo Co., Ltd.), and the number of rotations of the stirring was adjusted to produce oil droplets having a volume average particle size of about 1 μm. Then, it distilled under reduced pressure at 50 degreeC and removed toluene, and obtained the bluish gray emulsion.
[0162]
Transfer the obtained dispersion to a stirring tank equipped with an impeller, and gradually add dropwise an aqueous solution obtained by dissolving 10 parts of aluminum sulfate in 90 parts of ion-exchanged water at low speed to form aggregated particles, Thereafter, the liquid temperature was kept at 90 ° C., and part of the aggregation was melted together and confirmed by a scanning electron microscope.
[0163]
Thereafter, the mixture was stirred at 95 ° C. for 8 hours, and when the circularity of the toner reached the value shown in Table 1, it was cooled to 40 ° C. and the stirring was stopped.
[0164]
Thereafter, washing with water and filtration were repeated, and the resulting cake was dried under reduced pressure to obtain cyan colored particles. 100 parts of the obtained colored particles, 0.8 parts by mass of acicular titanium oxide (major axis 120 nm, n-decyltrimethoxysilane treatment), spherical monodispersed silica (silica sol obtained by the sol-gel method is treated with hexamethyldisilazane Then, 1.8 parts by mass of dried and pulverized particles with a particle size of 137 nm) and 0.3 parts by mass of silica particles (particle size of 14 nm) manufactured by a gas phase method and treated with octylmethoxysilane were mixed with a Henschel mixer. Then, coarse particles and aggregates were removed by passing through a sieve having an opening of 50 μm to obtain toner T1-C for electrophotography.
[0165]
Preparation of toner T1-K
Pigment Blue 15: 3 in the production process of the toner T1-C, 2 parts of phthalocyanine green hydrated cake (solid content 30%) and carbon black (MA60 Mitsubishi Chemical Corporation) as a colorant. Toner T1-K was obtained using 10 parts.
[0166]
Preparation of toners T2-C and T2-K
240 parts of [Urethane-modified polyester (1)] and 40 parts of [Polyester (2)] are dissolved and mixed in 2,000 parts of ethyl acetate, and the rest is the same as in toners T1-C and T1-K. C and T2-K were made.
[0167]
Preparation of toners T3-C and T3-K
[Polyester (2)] Using 280 parts, dissolved and mixed in 2,000 parts of ethyl acetate, and the others were the same as toners T1-C and T1-K, both of which were comparative toners T3-C and T3 -K was produced.
[0168]
The average value (μm) of the equivalent circle diameter of each toner of toners T1-C to T3-K, the average value of circularity, and the inclination of the circularity with respect to the equivalent circle diameter are shown below.
[0169]
[Table 1]

[0170]
[Production of carrier]
100 parts of silicone resin (20%)
γ- (2-aminoethyl) aminopropyltrimethoxysilane 1.0 part
Carbon black 0.1 part
60 parts of toluene
These formulations were dispersed with a homomixer for 20 minutes to prepare a coating layer forming solution. A coating layer was formed on the surface of 1000 parts of ferrite (volume average particle size 55 μm, saturation magnetization 72 emu / g) using a fluidized bed coating apparatus, and then fired in an electric furnace to prepare a carrier.
[0171]
(Development of developer)
Using a tumbler mixer of a type in which a container rolls and stirs each 5 parts of toner with respect to 100 parts of a carrier, it is uniformly mixed and charged for 15 minutes at 50 rpm to prepare a developer.
[0172]
(Characteristic evaluation)
The obtained developer was evaluated as described below. In carrying out the evaluation, an image forming apparatus having a digital exposure device shown in FIG. The configuration of the fixing device used for image formation was the same as that shown in FIG.
[0173]
(Fixability)
Fixability on extra thick paper
Continuous printing was performed using 500 postcards (thickness 0.4 mm) manufactured by Hart, using the image forming apparatus shown in FIG. 2 as an evaluation machine.
[0174]
A gray frame with a relative density of 0.5 was attached to the frame of the postcard. The ranks of the obtained prints were evaluated as follows.
[0175]
◎: Toner doesn't peel off even when writing on a gray frame with a pen
○: Toner peels off when writing on a gray frame with a pen, but the toner does not peel off when using a ballpoint pen
×: Fixation is insufficient and the toner is peeled off and the hand becomes dirty just by holding the gray frame in the hand
Fixing to offset printing paper
Printed on paperback paper (60.2g paper, for offset printing, medium quality: non-coated paper) manufactured by Daio Paper Co., Ltd., turned 10 times with the thumb of one hand, visually and loupeed around the characters (magnification 10) And the rank was evaluated as follows.
[0176]
◎: No smudges occur
○: No blotting stains are observed with the naked eye, but there is no practical problem that the stains can be detected slightly with the magnifying glass.
X: The thumb mark is dirty as if it blurs black.
[0177]
(Toner blister generation)
Plain paper (64 g / cm²) The toner adhesion amount is 1.6mg / cm²An image was formed so that a hole of about 0.1 to 0.5 μm, that is, the presence or absence of a toner blister was visually observed on the image, and the rank evaluation was performed as follows.
[0178]
A: No occurrence of toner blisters
○: 4cm²There are 1 to 2 toner blisters per unit, but there is no practical problem
X: 4 cm²The presence of 3 or more distinct toner blisters per unit is recognized, making it impractical.
(Line width reproducibility)
The line width of the line image corresponding to the image signal of 2 dot lines was measured by a print evaluation system “RT2000” (manufactured by Yarman). If the line width of the first formed image and the line width of the 20000th formed image are both 200 μm or less and the change in the line width is less than 10 μm, it can be said that there is no problem with fine line reproducibility. “O”, and “X” for other cases.
[0179]
(Chile of fine dots)
A 10% halftone image was formed on the entire secondary color (red, blue, green) image, and dust around the dots was observed with a loupe. Items that can hardly be detected are marked with “◎”, while those that are slightly detected are marked with “◯”.
[0180]
〔Evaluation results〕
The results are shown in Table 2 below.
[0181]
[Table 2]

[0182]
As is apparent from Table 2, the toners T1-K and T1-C and the toners T2-K and T2-C in the present invention may have any characteristics, but the toners T3-K and T3-C outside the present invention are It can be seen that there is a problem with the characteristics.
[0183]
Example 2
Using the toner T1-K in the present invention used in Example 1 and the toner T3-K outside the present invention, a non-magnetic one-component developing system (basic configuration is the same as in FIG. 4) is used. The characteristics as a magnetic one-component toner were examined.
[0184]
The toner was charged by bringing a 0.2 mm thick metal plate blade into uniform contact with the entire surface of the developing roller by the trail method on the soft developing roller surface.
[0185]
With the toners T1-K and T1-C in the present invention, good images were obtained up to 10,000 copies, but with the toners T3-K and T3-C outside the present invention, 3 From around 1,000 copies, the toner dust was noticeable. In addition, the density unevenness of the intermediate density image is noticeable. When the toner was disassembled and the surface of the developing roller was observed with the naked eye, toner T3-K was conspicuously attached with fine toner powder crushed by the blade.
[0186]
【The invention's effect】
According to the present invention, it is possible to provide a toner and an image forming method capable of exhibiting excellent fixability when an image is formed on a thick paper and capable of fixing a gray halftone image surely.
[0187]
In addition, according to the present invention, it is possible to provide a toner having a high particle strength and an image forming method capable of withstanding a load that acts when the nonmagnetic developing toner is charged or when an image is formed on a thick paper surface.
[0188]
Further, according to the present invention, it is possible to provide a toner and an image forming method in which a toner image formed on a printing paper can exhibit slipperiness and fixing strength that are not inferior to printed matter.
[0189]
Furthermore, according to the present invention, it is possible to provide a toner and an image forming method which do not cause an image defect in a high density portion on a toner image called a toner blister.
[Brief description of the drawings]
FIG. 1 is a configuration diagram illustrating an example of an image forming apparatus.
FIG. 2 is a structural cross-sectional view showing a digital image forming apparatus.
FIG. 3 is a cross-sectional view illustrating an example of a fixing device.
FIG. 4 is a schematic cross-sectional view of a developing device used in an image forming method of nonmagnetic one-component development.
[Explanation of symbols]
34 Photosensitive drum
36 Developer
37 Transfer device
39 Separator
40 Fixing device
41 Cleaning device
101 Image forming apparatus
122, 124 Paper feed tray
130, 131 Mirror unit
135 CCD
414 sponge roller
415 Stirring blade
417 Toner tank
A Automatic document feeder (commonly known as ADF)
B Document image reader
E Image forming section

Claims (3)

A toner obtained by using a dispersion obtained by dispersing amorphous polyester resin particles in an aqueous medium and aggregating the amorphous polyester resin particles in an aqueous medium. The toner is modified with urethane. Ri Na contain polyester, further, the average value of circularity of the toner is 0.94 to 0.99, and the average value of the circle equivalent diameter is in the 2.6～7.4Myuemu, circle equivalent diameter toner for developing an electrostatic latent image slope of circularity is characterized -0.050～-0.010 der Rukoto against. 2. The electrostatic latent image developing toner according to claim 1, wherein the toner is externally added with silica or titanium oxide fine particles having an average primary particle diameter of 50 to 200 nm. An image forming method comprising forming an image using the electrostatic latent image developing toner according to claim 1.

Images