JP2004184721A - Manufacturing method of dry type toner, and dry type toner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To form an image well matching with an image forming device and having a high resolution and a high definition. <P>SOLUTION: This dry type toner is manufactured through at least a dispersion process of preparing a polymerizable monomer composition including a polymerizable monomer and a colorant; a granulating process of performing suspension as oil droplets of the composition in a water-based dispersion medium; and a polymarizing process of manufacturing polymeric particles by polymerlizing the composition by using a polymer initiator. In this dry toner, (1) the initiator is a redox-based polymerlizing initiator composed of a nonaromatic organic peroxide and a nonaromatic reducer, (2) the peroxide is added into the composition in the dispersion process and/or the granulating process, and (3) the reducer is added with precedence into the dispersion medium separately from the peroxide in the granulating process and/or the polymarizing process, and additionally added after a polymerization conversion rate of the polymerizable monomer proceeds up to ≥10%. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

【００７２】
上記の如きスルホン酸基を含有する重合体は、トナー製造時にアルカリ金属及び／又はアルカリ土類金属を含有する無機化合物を添加することによって、スルホン酸基の部分に塩構造が形成されるので、特に上記の如きスルホン酸基含有（メタ）アクリルアミド系モノマーを用いた高分子型化合物の場合、分子内でのスルホベタイン構造の生成を抑制することによって、水和を防止しながらオキシカルボン酸との相互作用を確保することができるので、環境変動に対するトナーの帯電性が一層良好なものとなる。特に、懸濁重合法によってトナーを製造する際、後述するようなアルカリ金属及び／又はアルカリ土類金属を含有する分散安定剤を用いると、スルホン酸基との塩構造を容易に形成することが出来るので好ましい。
【００７３】
上記の如きスルホン酸基と塩構造を形成し得るアルカリ金属、もしくはアルカリ土類金属としては、例えば、リチウム、ナトリウム、カリウム、カルシウム、バリウム、ベリリウム、マグネシウム等が挙げられ、中でもカルシウムが好ましい。
【００７４】
本発明に用いられるその他の荷電制御剤としては、公知のものが利用出来るが、特に重合阻害性が低く、水系分散媒体への可溶化物が実質的になく、且つ一定の帯電量を安定して維持できる荷電制御剤が好ましい。具体的な化合物としては、ネガ系荷電制御剤としてサリチル酸、アルキルサリチル酸、ジアルキルサリチル酸、ナフトエ酸、ダイカルボン酸の如き芳香族カルボン酸の金属化合物、アゾ染料あるいはアゾ顔料の金属塩または金属錯体、スルホン酸又はカルボン酸基を側鎖に持つ高分子型化合物、ホウ素化合物、尿素化合物、ケイ素化合物、カリックスアレーン等が挙げられる。ポジ系荷電制御剤として四級アンモニウム塩、該四級アンモニウム塩を側鎖に有する高分子型化合物、グアニジン化合物、ニグロシン系化合物、イミダゾール化合物等が挙げられる。
【００７５】
荷電制御剤をトナーに含有させる方法としては、トナー粒子に内部添加する方法と外部添加する方法がある。これらの電荷制御剤の使用量としては、結着樹脂の種類、他の添加剤の有無、分散方法を含めたトナー製造方法によって決定されるもので、一義的に限定されるものではないが、内部添加する場合は、好ましくは結着樹脂１００質量部に対して０．１〜１０質量部、より好ましくは０．１〜５質量部の範囲で用いられる。また、外部添加する場合、トナー１００質量部に対し、好ましくは０．００５〜１．０質量部、より好ましくは０．０１〜０．３質量部である。
【００７６】
本発明に係る重合性単量体組成物にポリエステル樹脂やポリカーボネート樹脂等の極性を有する樹脂（以下、「極性樹脂」と称す）を含有することによりトナーの内部構造や表面性を改質することが出来る。例えば、トナー製造において、分散工程から重合工程に至る重合反応時に上記の如き極性樹脂を添加すると、トナー粒子となる重合性単量体組成物と水系分散媒体の呈する極性のバランスに応じて、添加した極性樹脂がトナー粒子の表面に薄層を形成したり、トナー粒子表面から中心に向け傾斜性をもって存在するように制御することが出来る。特に、トナーの内部構造や表面性を積極的に設計し、好ましい特性を付与する為には、酸価が１〜４０ｍｇＫＯＨ／ｇを呈する極性樹脂を用いることが好ましい。
【００７７】
上記極性樹脂の添加量は、結着樹脂１００質量部に対して１〜２５質量部使用するのが好ましく、より好ましくは２〜１５質量部である。１質量部未満ではトナー粒子中での極性樹脂の存在状態が不均一となり、逆に２５質量部を超えるとトナー粒子表面に形成される極性樹脂の薄層が厚くなる為、何れの場合も他のトナー構成材料の含有状態を制御するのが困難になり、その機能を十分に発現することが出来ない。
【００７８】
また、上記の如き極性樹脂はそれぞれ１種類の重合体に限定されるわけではなく、例えば反応性ポリエステル樹脂を同時に２種類以上用いることや、ビニル系重合体を２種類以上用いることが可能であり、さらに全く種類の異なる重合体、例えば反応性の無いポリエステル樹脂、エポキシ樹脂、ポリカーボネート樹脂、ポリオレフィン、ポリ酢酸ビニル、ポリ塩化ビニル、ポリアルキルビニルエーテル、ポリアルキルビニルケトン、ポリスチレン、ポリ（メタ）アクリルエステル、メラミンホルムアルデヒド樹脂、ポリエチレンテレフタレート、ナイロン、ポリウレタン等様々な重合体を必要に応じてバインダー樹脂に添加することが出来る。
【００７９】
本発明に係る水系分散媒体には、分散安定剤として公知の界面活性剤や有機分散剤・無機分散剤が使用できる。中でも無機分散剤は、有害な超微粉を生じ難く、その立体障害性により分散安定性を得ているので反応温度を変化させても安定性が崩れ難く、洗浄も容易でトナーに悪影響を与え難いので、好ましく使用できる。こうした無機分散剤の例としては、燐酸カルシウム、燐酸マグネシウム、燐酸アルミニウム、燐酸亜鉛等の燐酸多価金属塩、炭酸カルシウム、炭酸マグネシウム等の炭酸塩、メタ硅酸カルシウム、硫酸カルシウム、硫酸バリウム等の無機塩、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、シリカ、ベントナイト、アルミナ等の無機酸化物が挙げられる。
【００８０】
これら無機分散剤を用いる場合には、そのまま使用しても良いが、より細かい粒子を得るため、水系媒体中にて該無機分散剤粒子を生成させて用いることが出来る。例えば、燐酸カルシウムの場合、高速撹拌下、燐酸ナトリウム水溶液と塩化カルシウム水溶液とを混合して、水不溶性の燐酸カルシウムを生成させることが出来、より均一で細かな分散が可能となる。この時、同時に水溶性の塩化ナトリウム塩が副生するが、水系媒体中に水溶性塩が存在すると、重合性単量体の水への溶解が抑制されて、乳化重合に依る超微粒トナーが発生し難くなるので、より好都合である。無機分散剤は、重合終了後酸あるいはアルカリで溶解して、ほぼ完全に取り除くことが出来る。
【００８１】
また、これらの無機分散剤は、重合性単量体１００質量部に対して、０．２〜２０質量部を単独で使用することが望ましいが、超微粒子を発生し難いもののトナーの微粒化はやや苦手であるので、０．００１〜０．１質量部の界面活性剤を併用しても良い。
【００８２】
界面活性剤としては、例えばドデシルベンゼン硫酸ナトリウム、テトラデシル硫酸ナトリウム、ペンタデシル硫酸ナトリウム、オクチル硫酸ナトリウム、オレイン酸ナトリウム、ラウリル酸ナトリウム、ステアリン酸ナトリウム、ステアリン酸カリウム等が挙げられる。
【００８３】
重合工程終了後、重合体粒子を公知の方法によって濾過、洗浄、乾燥を行い、必要により無機微粉体を混合し表面に付着させることで、乾式トナーを得ることが出来る。また、トナーの製造工程に分級工程を入れ、トナー粗粒や微粉を除去することも、本発明の望ましい形態の一つである。
【００８４】
（乾式トナー）
本発明の乾式トナーは、少なくとも、重合性単量体と着色剤を含有する重合性単量体組成物を油滴状に懸濁させた後、該重合性単量体組成物を非芳香族系有機過酸化物と非芳香族系還元剤からなるレドックス系重合開始剤により重合させることにより得られた乾式トナーであって、該トナーは、個数基準の粒度頻度分布における円相当個数平均径が２〜６μｍで、円形度頻度分布における平均円形度が０．９６５〜０．９９５であり、該トナー中の着色剤含有量に対し、該トナー中に存在する６３５メッシュの篩い（開口径＝２０μｍ）を通過しないトナー粗粒中の着色剤の相対含有率が０．９０〜１．１０であることを特徴とする。
【００８５】
本発明者等は、トナー粒子の粒径頻度分布と円形度頻度分布が現像性と転写性に及ぼす影響を検討したところ、非常に深い関わりがあることを見出した。
【００８６】
即ち、トナーの個数基準の粒径頻度分布における円相当個数平均径を２〜６μｍ、好ましくは３〜５μｍと小粒径化することにより画像の輪郭部分、特に文字画像やラインバターンの現像での再現性が良好なものとなる。しかし、一般にトナー粒子を小粒径化すると、必然的に微小粒径のトナーの存在率が高くなるため、トナーを均一に帯電させることが困難となり画像カブリを生じるばかりか、静電潜像担持体表面への付着力が高くなり、結果として転写残トナーの増加を招いていた。
【００８７】
しかし、本発明のトナーは、円形度頻度分布の平均円形度を０．９６５〜０．９９５、好ましくは０．９７０〜０．９９５、特に好ましくは０．９８０〜０．９９５とすることで現像性や転写性の環境変動に対する安定性、更には耐久性が良好なものとなる。
【００８８】
その理由として本発明者らは、現像工程においてトナー担持体上にトナーの薄層を形成する際に、トナー層厚規制部材の規制力を通常よりも強くしても十分なトナーコート量を保つことができるため、トナー担持体に対するダメージを与えることなくトナー担持体上のトナーの帯電量を通常よりも高くすることが可能となるからだと考えている。
【００８９】
また、従来では困難であった小粒径を呈するトナーの転写性が大幅に改善されると共に低電位潜像に対する現像能力も格段に向上する。特にデジタル方式の微小スポット潜像を現像する場合に有効である。平均円形度が０．９６５未満の場合、転写性が悪化するばかりか、現像性が低下する。また、平均円形度が０．９９５を超えるとトナー表面の劣化が著しいものとなり耐久性等に問題を生じる様になる。
【００９０】
本発明におけるトナーの円相当径、円形度及びそれらの頻度分布とは、トナー粒子の形状を定量的に表現する簡便な方法として用いたものであり、本発明ではフロー式粒子像測定装置ＦＰＩＡ−１０００型（東亜医用電子社製）を用いて測定を行い、次式を用いて算出した。
【００９１】
【数１】

【００９２】
ここで、「粒子投影面積」とは二値化されたトナー粒子像の面積であり、「粒子投影像の周囲長」とは該トナー粒子像のエッジ点を結んで得られる輸郭線の長さと定義する。
【００９３】
本発明における円形度はトナー粒子の凹凸の度合いを示す指標であり、トナー粒子が完全な球形の場含に１．０００を示し、表面形状が複雑になる程、円形度は小さな値となる。
【００９４】
本発明において、トナーの個数基準の粒径頻度分布の平均値を意味する円相当個数平均径と粒径標準偏差ＳＤｄは、粒度分布の分割点ｉでの粒径（中心値）をｄｉ、頻度をｆｉとすると次式から算出される。
【００９５】
【数２】

【００９６】
また、円形度頻度分布の平均値を意味する平均円形度と円形度標準偏差ＳＤｃは、粒度分布の分訊点ｉでの円形度（中心値）をｃｉ、頻度をｆｃｉとすると、次式から算出される。
【００９７】
【数３】

【００９８】
具体的な測定方法としては、容器中に予め不純固形物などを除去したイオン交換水１０ｍｌを用意し、その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ホン酸塩を加えた後、更に測定試料を０．０２ｇを加え、均一に分散させる、分散させる手段としては、超音波分散機ＵＨ−５０型（エスエムテー社製）に振動子として５ｍｍφのチタン合金チップを装着したものを用い、５分間分散処理を用い、測定用の分散液とする、その際、該分散液の温度が４０℃以上とならない様に適宜冷却する。
【００９９】
トナー粒子の形状測定には、前記フロー式粒子像測定装置を用い、測定時のトナー粒子濃度が３０００〜１万個／μｌとなる様に該分散液濃度を再調整し、トナー粒子を１０００個以上計測する。計測後、このデータを用いて、トナーの円相当径や円形度頻度分布等を求める。
【０１００】
本発明の乾式トナーは、重合性単量体組成物を懸濁後、非芳香族系有機過酸化物と非芳香族系還元剤とを有するレドックス系重合開始剤により重合させることによって製造されるが、レドックス化のタイミングによっては得られるトナー粒子の形状や内部構造の制御が困難となる。また、著しい場合には、重合性単量体の一部が気化したり、ワックス成分が該油滴外に滲み出したりする為、トナー粒子中に着色剤やワックス成分が偏析した２０μｍを超えるトナー粗粒を生じる。この様なトナー粗粒は扁平状の形状をしていることが多く、通常の分級や篩い掛けでは容易に除去することが出来ず、トナー性能や画像形成装置とのマッチングに重大な問題を及ぼす。しかしながら、本発明の乾式トナーは、トナー中の着色剤含有率（Ｐａ）に対する該トナー中に存在する６３５メッシュの篩い（開口径＝２０μｍ）を通過しないトナー粗粒中の着色剤含有率（Ｐｂ）の相対比（Ｐｂ／Ｐａ、以下、「トナー粗粉着色剤相対比」と称す）を０．９０〜１．１０とすることによって上記の如き問題点を未然に防止することが出来る。
【０１０１】
更に、トナー中にワックス成分を含有する場合には、該トナー中のワックス成分含有率（Ｗａ）に対する該トナー中に存在する６３５メッシュの篩い（開口径＝２０μｍ）を通過しないトナー粗粒中のワックス成分含有率（Ｗｂ）の相対比（Ｗｂ／Ｗａ、以下、「トナー粗粉ワックス成分相対比」と称す）を０．８５〜１．２０、より好ましくは０．９０〜１．１０とすることにより一層好ましい状態となる。
【０１０２】
本発明において、トナー中の着色剤の定量には、蛍光Ｘ線分析やプラズマ発光分析（ＩＣＰ）等の公知の分析方法を用いることができる。分析方法の一例としては、蛍光Ｘ線分析装置「ＳＹＳＴＥＭ３０８０」（理学電機工業（株）社製）を使用し、「ＪＩＳ Ｋ０１１９」に記載されている蛍光Ｘ線分析通則に準じて定量する方法が挙げられる。また、カーボンブラックの定量は、加熱時の質量減少率等から求めることが出来る。
【０１０３】
一方、トナー中のワックス成分の定量は、トナー中からワックス成分を抽出し、その質量を直接測定しても良く、また、上述の如きワックス成分の融点測定時に得られるＤＳＣ曲線を用い、ワックス成分の溶解熱から含有量を求めることも出来る。
【０１０４】
本発明に係るトナーに無機微粉体を添加することは、現像性、転写性、帯電安定性、流動性、及び耐久性向上の為に好ましい実施形態である。無機微粉体としては公知のものが使用可能であるが、特にシリカ、アルミナ、チタニア、或いはそれらの複酸化物の中から選ばれることが好ましく、更にはシリカであることがより好ましい。例えば、係るシリカ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所謂乾式法、又はヒュームドシリカと称される乾式シリカ、及びアルコキシドや水ガラス等から製造されるいわゆる湿式シリカの両者が使用可能であるが、シリカ微粉体の表面や内部にあるシラノール基が少なく、Ｎａ_２ＯやＳＯ_３ ^２−等の製造残渣の少ない乾式シリカの方が好ましい。尚、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，塩化チタン等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包含する。
【０１０５】
本発明に用いられる無機微粉体は、ＢＥＴ法で測定した窒素吸着による比表面積が３０ｍ^２／ｇ以上、特に５０〜４００ｍ^２／ｇの範囲のものが良好な結果を与え、トナー１００質量部に対して０．３〜８質量部使用され、好ましくは０．５〜５質量部である。
【０１０６】
更に、比表面積が５０〜１５０ｍ^２／ｇを呈する無機微粉体と１７０ｍ^２／ｇ以上を呈する無機微粉体を上記範囲で５：９５〜５０：５０の質量比率で併用することにより、トナー粒子間に適度な空隙と流動性を付与されるので、トナーの帯電挙動が良好となる。
【０１０７】
無機微粉末の比表面積が３０ｍ^２／ｇ未満の場合には、トナーに適度な流動性を付与することが困難であり、また、着色剤に起因するトナー担時体の汚染への防止効果が小さくなってしまう。一方、比表面積が４００ｍ^２／ｇを超える場合には、連続して多数枚プリントアウト時に該無機微粉末がトナー粒子表面に埋め込まれるために、トナーの流動性が低下する場合がある。
【０１０８】
また、無機微粉末の添加量が０．３質量部未満の場合には、添加効果が発現されず、８質量部を超えるとトナーの帯電性や定着性に問題を生じるだけでなく、遊離した無機微粉体により画像形成装置とのマッチングが著しく悪化する。
【０１０９】
更に、本発明に用いられる無機微粉体は、必要に応じ、疎水化，帯電性制御等の目的でシリコーンワニス、各種変性シリコーンワニス、シリコーンオイル、各種変性シリコーンオイル、シランカップリング剤、官能基を有するシランカップリング剤、その他有機硅素化合物、有機チタン化合物等の処理剤、或いは種々の処理剤を併用して処理されていることも可能であり好ましい。
【０１１０】
比表面積の測定には、比表面積測定装置「オートソーブ１」（湯浅アイオニクス社製）を用いて試料表面に窒素ガスを吸着させ、ＢＥＴ多点法により比表面積を算出した。
【０１１１】
特に本発明に係るトナーに用いられる無機微粉体は、高い帯電量を維持し、高転写率と画像形成装置への良好なマッチングを達成する為に、少なくともシリコーンオイルで処理されることが好ましい。
【０１１２】
本発明の乾式トナーは、実質的な悪影響を与えない範囲内で更に他の添加剤、例えばポリフッ化エチレン粉末、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などの研磨剤；例えば酸化チタン粉末、酸化アルミニウム粉末などの流動性付与剤；ケーキング防止剤、或いは例えばカーボンブラック粉末、酸化亜鉛粉末、酸化スズ粉末等の導電性付与剤、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出来る。
【０１１３】
本発明に係る乾式トナーは、そのまま一成分系現像剤として、或いはキャリアと混合して二成分系現像剤として使用することができる。
【０１１４】
二成分系現像剤として用いる場合、例えば、トナーと混合させる磁性キャリアとしては、鉄、銅、亜鉛、ニッケル、コバルト、マンガン、クロム等より選ばれる元素から、単独又は複合フェライト状態で構成される。この際に使用する磁性キャリアの形状は、球状、扁平、不定形等のものがあり、更に、磁性キャリアの表面状態の微細構造（例えば、表面凹凸性）を適宜に制御したものを用いることも出来る。また、表面を樹脂で被覆した樹脂被覆キャリアも好適に用いることが出来る。使用するキャリアの平均粒径は、好ましくは１０〜１００μｍ、より好ましくは２０〜５０μｍである。また、これらのキャリアとトナーを混合して二成分系現像剤を調製する場合の現像剤中のトナー濃度は、好ましくは２〜１５質量％である。
【０１１５】
（画像形成方法）
次に、本発明に係る画像形成方法の一例として、複数の画像形成部にて各々異なった色のトナー像を形成し、これらを同一転写材上に順次重ね合わせて転写することで多色画像を形成する画像形成方法について、図１に示すフルカラー画像形成装置の概略的説明図を用いて説明する。
【０１１６】
フルカラー画像形成装置本体には、第１の画像形成ユニットＰａ、第２の画像形成ユニットＰｂ、第３の画像形成装置ユニットＰｃ、及び第４の画像形成装置ユニットＰｄが併設されており、各々の画像形成装置ユニットで異なった色のトナー像が現像された後、転写材搬送ベルトによって搬送される転写材上に転写され、更に加熱加圧定着されることによってフルカラー画像が得られる。
【０１１７】
上記画像形成装置に併設される各画像形成ユニットの構成について、第１の画像形成ユニットＰａを例に挙げて説明する。
【０１１８】
第１の画像形成ユニットＰａには、静電潜像担持体として直径２４ｍｍφの感光体ドラム１９ａを具備し、感光体ドラム１９ａは矢印の方向に回転移動する。
【０１１９】
帯電手段として、直径１２ｍｍφの一次帯電ローラー１６ａが感光体ドラム１９ａの表面に接するように配設されている。一次帯電ローラー１６ａにより均一に一次帯電された感光体ドラム１９ａには、露光装置１３ａより画像信号に応じて照射されるレーザー光１４ａによって静電潜像が形成される。
【０１２０】
現像装置１７ａは、感光体ドラム１９ａの表面上に形成された静電潜像を現像してトナー像を形成する為の現像手段を有しており、第１色目のトナーと該トナーの薄層を表面に担持した直径１８ｍｍφの現像ローラー１５ａがトナーの薄層を介して感光体ドラム１９ａに接するように配設されており、第１色目のトナー像が現像される。
【０１２１】
感光体ドラム１９ａ上に現像された第１色目のトナー像は、ベルト状の転写材担持体２０によって搬送されてくる転写材Ｓの表面に転写手段としての転写ブレード１１ａによって転写される。この転写ブレード１１ａは、転写材担持体２１０の裏面に当接して、バイアス印加手段１２ａによって転写バイアスを印加し得るものである。
【０１２２】
転写が終了した感光体ドラム１９ａの表面は、クリーニング装置１８ａにより転写残余のトナーが除去され、引き続き行われる次の静電潜像形成の為に供せられる。
【０１２３】
本発明に係る画像形成装置は、第１の画像形成ユニットＰａと同様の構成で、現像装置に保有されるトナーの色が異なる第２の画像形成装置ユニットＰｂ、第３の画像形成装置ユニットＰｃ、及び第４の画像形成装置ユニットＰｄの４つの画像形成装置ユニットを併設するものである。例えば、第１の画像形成装置ユニットＰａにはイエロートナー、第２の画像形成装置ユニットＰｂにはマゼンタトナー、第３の画像形成装置ユニットＰｃにはシアントナー、更に第４の画像形成装置ユニットＰｄにはブラックトナーを各々用い、各画像形成装置ユニットの転写部で各色トナー像が転写材上に順次転写される。この際、この工程中にレジストレーションを合わせつつ転写材を移動させ、同一転写材上に各色トナーは重ね合わされ、終了すると分離帯電器２１によって転写材担持体２０上から転写材Ｓが分離され、搬送ベルトの如き搬送手段によって定着器２３に送られ、ただ一回の定着によって所望のフルカラー画像が得られる。
【０１２４】
図１において、転写材担持体２０は無端のベルト状部材であり、このベルト部材は画像形成の進行に伴い、駆動ローラー８０によって矢印の方向に移動する。転写材担持体２０の周囲には、ベルト従動ローラー８１、ベルト除電装置８２、及びベルトクリーニング装置８３が配設され、また、一対のレジストローラー２４が転写材ホルダー内の転写材Ｓを転写材担持体に搬送する為に設けられている。
【０１２５】
上記の如き画像形成装置において、転写手段としては、転写材担持体の裏面側に当接する転写ブレードに代えて、ローラー状の転写ローラーを用いたり、コロナ帯電器の如き非接触の帯電手段を用いることも可能である。
【０１２６】
また、転写材を搬送する為の搬送手段としては、加工の容易性や耐久性の観点からテトロン繊維のメッシュを用いた搬送ベルトやポリエチレンテレフタレート系樹脂、ポリイミド系樹脂、及びウレタン系樹脂の如き薄い誘電体シートを用いた搬送ベルトが用いられるが、ドラム式の搬送手段を有する構成としても良い。
【０１２７】
上記の如き画像形成装置では、各画像形成装置ユニットの転写部において、同一転写材上に各色トナー像を順次転写する為、先に転写されたトナー像が後から転写されてくるトナー像を担持する感光体ドラムと接する。この際、先に転写が完了している転写材上のトナー像を形成するトナー粒子中に不安定な帯電状態にあるものが存在する場合、続いて転写が行われる感光体ドラムに引き戻される所謂「再転写現象」を生じ、画質低下を招く発端となる。しかしながら、本発明においては、有彩色現像剤の各々のトナー粒子中の着色剤の種類と含有量を特定することで、上記の如き画像不良を未然に防止することが出来る。
【０１２８】
【実施例】
以下、本発明を具体的製造例、及び実施例によって説明するが、本発明は何らこれらに限定されるものではない。
【０１２９】
〈トナーの製造実施例１〉
分散工程
下記成分からなる混合物をアトライター（三井金属社製）を用いて３時間分散させた。
・スチレン ８３質量部
・ｎ−ブチルアクリレート １７質量部
・ジビニルベンゼン ０．１質量部
・着色剤（Ｃ．Ｉ．ピグメントブルー１５：３） ５質量部
・ポリエステル樹脂（ピーク分子量＝５０００） ５質量部
・スルホン酸基を有する重合体 ２質量部
［２−アクリルアミド−２−メチルプロパンスルホン酸（上記式（２）で示されるスルホン酸基含有モノマー）５．８質量％を含有するスチレン重合体、Ｔｇ＝６０℃］
【０１３０】
得られた分散物を６０℃に加温し、そこにワックス成分としてエステルワックス（融点＝７０℃）１０質量部を混合溶解し、更に非芳香族系有機過酸化物としてｔ−ブチルパーオキシイソプロピルモノカーボネート（１０時間半減期温度９８．７℃）５質量部を添加し、重合性単量体組成物を調製した。
【０１３１】
造粒工程
高速撹拌装置クレアミックス（エムテクニック社製）を具備した反応容器中に、イオン交換水７００質量部と０．１ｍｏｌ／Ｌ−Ｎａ_３ＰＯ_４水溶液８００質量部を投入し、高速撹拌装置の回転数を１５０００ｒｐｍに設定し、６０℃に加温せしめた。ここに１．０ｍｏｌ／Ｌ−ＣａＣｌ_２水溶液７０質量部を添加し、微小な難水溶性分散剤Ｃａ_３（ＰＯ_４）_２を含む水系分散媒体を調製した。
【０１３２】
次いで、該水系媒体中に前記重合性単量体組成物を投入し、内温６０℃のＮ_２雰囲気下で、高速撹拌装置の回転数を１５０００ｒｐｍに維持しつつ、１０分間撹拌し、該重合性単量体組成物を水系媒体中に油滴状に懸濁させ、造粒した。
【０１３３】
重合工程
その後、撹拌装置をパドル撹拌翼を具備したものに換え、８０ｒｐｍの回転数で撹拌しながら６０℃に保持した。これに非芳香族系還元剤であるアスコルビン酸ナトリウム２．５質量部（有機過酸化物の添加量基準で４４ｍｏｌ％）を溶解させた水溶液を先行添加し、重合反応を開始させた。
【０１３４】
重合性単量体の重合転化率が３０％を超えた時点でアスコルビン酸ナトリウム１．２５質量部を溶解させた水溶液を追加添加（累計３．７５質量部、有機過酸化物の添加量基準で６７ｍｏｌ％）し、重合温度を８０℃（＞エステルワックスの融点＝７０℃）に昇温した。
【０１３５】
更に、重合性単量体の重合転化率が６０％を超えた時点でアスコルビン酸ナトリウム１．２５質量部を溶解させた水溶液を再度追加添加（累計５質量部、有機過酸化物の添加量基準で１００ｍｏｌ％）し、重合転化率がほぼ１００％に達したところで重合工程を完了した。尚、重合反応に要した時間は６時間であった。
【０１３６】
重合終了後、加熱減圧下で重合体粒子中に残存する揮発成分を留去し、次いで、冷却後に希塩酸を添加して難水溶性分散剤を溶解せしめた。更に、水洗浄を数回繰り返した後、乾燥処理を行い、個数基準の粒度頻度分布における円相当個数平均径（以下、「平均粒径」と称す）が４．５μｍの重合体粒子（Ａ）を得た。
【０１３７】
該重合体粒子（Ａ）１００質量部とシリコーンオイル処理疎水性シリカ微粉体１質量部とシリコーンオイル処理酸化チタン微粉体０．５質量部をヘンシェルミキサー（三井金属社製）で乾式混合して、平均粒径が４．５μｍで、円形度頻度分布における平均円形度（以下、「平均円形度」と称す）が０．９８１であるシアントナー（Ａ）とした。また、シアントナー（Ａ）中に残留していたスチレンモノマー量は非常に微量であり、５０ｐｐｍ以下であった。
【０１３８】
シアントナー（Ａ）中の着色剤含有率に対し、シアントナー（Ａ）中に存在する６３５メッシュの篩い（東京スクリーン社製、開口径＝２０μｍ、「ＪＩＳ Ｚ ８８０１」対応品）を通過しないトナー粗粒中の着色剤含有率の相対比は１．００であった。
【０１３９】
また、シアントナー（Ａ）中のワックス成分含有率に対し、シアントナー（Ａ）中に存在する６３５メッシュの篩いを通過しないトナー粗粒中のワックス成分含有率の相対比も１．００であった。
【０１４０】
更に、重合体粒子（Ａ）の製造を連続５回繰り返して行った。各製造毎に得られたシアントナーの平均粒径の平均値は４．５μｍ（標準偏差＝０．０２）、平均円形度の平均値は０．９８０（標準偏差＝０．００２）で、トナー粗粉着色剤相対比の平均値は１．００（標準偏差＝０．４９）、トナー粗粉ワックス成分相対比の平均値は１．００（標準偏差＝０．５０）であり、非常に好ましい連続生産性を示した。
【０１４１】
また、重合体粒子製造後、反応容器の内壁やパドル撹拌翼を観察したところ、それらの汚れ具合は水流により大部分の汚れを洗い落とすことが出来る程度の軽微なものであった。
【０１４２】
〈トナーの製造実施例２〉
造粒工程において、難水溶性分散剤Ｃａ_３（ＰＯ_４）_２の生成量、高速撹拌装置の回転数と撹拌時間を変更することにより、重合性単量体組成物をより微細に油滴状に懸濁させ、造粒したことを除いては、トナーの製造実施例１と同様にして平均粒径が３．２μｍの重合体粒子（Ｂ）を製造し、シアントナー（Ｂ）を調製した。
【０１４３】
得られたシアントナー（Ｂ）の平均粒径は３．２μｍ、平均円形度は０．９８２で、トナー粗粒着色剤相対比は１．００、トナー粗粉ワックス成分相対比は０．９９であった。また、シアントナー（Ｂ）中に残留していたスチレンモノマー量は５０ｐｐｍ以下であった。
【０１４４】
この時、重合反応に要した時間は４時間で、トナーの製造実施例１で重合体粒子（Ａ）を製造した時と比較して６５％に短縮されており、また、反応容器内等の汚れ具合も同程度の状態であった。トナー（Ａ）と同様な設備により微粒子状のトナーを製造したにも拘わらず、生産性の大幅な向上が認められた。
【０１４５】
〈トナーの製造実施例３〉
重合工程において、アスコルビン酸ナトリウム２．５質量部（有機過酸化物の添加量基準で４４ｍｏｌ％）を溶解させた水溶液を添加して重合反応を開始させた後、重合性単量体の重合転化率が２５％を超えた時点からアスコルビン酸ナトリウム２．５質量部を溶解させた水溶液を定量ポンプを用いて少量ずつ連続的に添加したことを除いては、トナーの製造実施例１と同様にして重合体粒子（Ｃ）を得た後、ブラックトナー（Ｃ）を調製した。
【０１４６】
得られたブラックトナー（Ｃ）の平均粒径は４．６μｍ、平均円形度は０．９７８で、トナー粗粒着色剤相対比は１．００、トナー粗粒ワックス成分相対比は０．９９であった。また、ブラックトナー（Ｃ）中に残留していたスチレンモノマー量は５０ｐｐｍ以下であった。
【０１４７】
〈トナーの製造実施例４〉
造粒工程において、難水溶性分散剤Ｃａ_３（ＰＯ_４）_２の生成後の水系分散媒体にアスコルビン酸ナトリウム１質量部（有機過酸化物の添加量基準で１８ｍｏｌ％）を溶解させた水溶液を添加した後、重合性単量体組成物を造粒させると共に、重合工程において、重合性単量体の重合転化率が３０％を超えた時点でアスコルビン酸ナトリウム２質量部を溶解させた水溶液を追加添加（累計３質量部、有機過酸化物の添加量基準で５３ｍｏｌ％）し、重合温度を８０℃に昇温し、更に、重合性単量体の重合転化率が６０％を超えた時点でアスコルビン酸ナトリウム２質量部を溶解させた水溶液を再度追加添加（累計５質量部、有機過酸化物の添加量基準で１００ｍｏｌ％）することを除いては、トナーの製造実施例１と同様にして重合体粒子（Ｄ）を得た後、シアントナー（Ｄ）を調製した。
【０１４８】
得られたシアントナー（Ｄ）の平均粒径は４．９μｍ、平均円形度は０．９７２で、トナー粗粒着色剤相対比は０．９８、トナー粗粒ワックス成分相対比は０．９８であった。また、シアントナー（Ｄ）中に残留していたスチレンモノマー量は５０ｐｐｍ以下であった。
【０１４９】
〈トナーの製造実施例５〉
造粒工程において、水系媒体中に重合性単量体組成物を投入し、高速撹拌機の回転数を１５０００ｒｐｍに維持し、２分間撹拌後、ｔ−ブチルパーオキシイソプロピルモノカーボネート５質量部を添加することを除いては、トナーの製造実施例１と同様にして重合体粒子（Ｅ）を得た後、シアントナー（Ｅ）を調製した。
【０１５０】
得られたシアントナー（Ｅ）の平均粒径は４．７μｍ、平均円形度は０．９７０で、トナー粗粒着色剤含有比は０．９７、トナー粗粒ワックス成分相対比は０．９６であった。また、シアントナー（Ｅ）中に残留していたスチレンモノマー量は５０ｐｐｍ以下であった。
【０１５１】
〈トナーの製造実施例６〉
下記成分からなる混合物をアトライター（三井金属社製）を用いて３時間分散させた。
・スチレン ７８質量部
・２−エチルヘキシルアクリレート ２２質量部
・ジビニルベンゼン ０．１質量部
・着色剤（カーボンブラック、粒径＝５５ｎｍ） ６質量部
・ポリエステル樹脂（ピーク分子量＝６０００） ５質量部
・スルホン酸基を有する重合体 ２質量部
［２−アクリルアミド−２−メチルフェニルエタンスルホン酸（上記式（３）で示されるスルホン酸基含有モノマー）７．９質量％を含有するスチレン−２−エチルヘキシルアクリレート共重合体、Ｔｇ＝６５℃］
【０１５２】
得られた分散物を６０℃に加温し、そこにワックス成分として酸変性ポリエチレンワックス（融点＝１１５℃）５質量部を混合溶解し、更に非芳香族系有機過酸化物としてｔ−ブチルパーオキシイソプロピルモノカーボネート５質量部を添加し、重合性単量体組成物を調製した後、非芳香族系還元剤としてアスコルビン酸ナトリウムに換えてエリソルビン酸（水へ溶解度＝５３）５質量部を同様な添加方法で用いたことを除いては、トナーの製造実施例１と同様にして重合体粒子（Ｆ）を得た後、ブラックトナー（Ｆ）を調製した。
【０１５３】
得られたブラックトナー（Ｆ）の平均粒径は４．３μｍ、平均円形度は０．９７７で、トナー粗粒着色剤相対比は１．００、トナー粗粒ワックス成分相対比は１．００であった。また、ブラックトナー（Ｆ）中に残留していたスチレンモノマー量は５０ｐｐｍ以下であった。
【０１５４】
〈トナーの製造実施例７〉
重合性単量体組成物にＣｕフタロシアニン（Ｃ．Ｉ．ピグメントブルー１５：３）１質量部を追加添加することを除いては、トナーの製造実施例６と同様にして重合体粒子（Ｇ）を得た後、ブラックトナー（Ｇ）を調製した。
【０１５５】
得られたトナー（Ｇ）の平均粒径は４．１μｍ、平均円形度は０．９８５で、トナー粗粒着色剤相対比は１．００、ワックス成分相対比は１．００であった。また、ブラックトナー（Ｇ）中に残留していたスチレンモノマー量は５０ｐｐｍ以下であった。
【０１５６】
この時、重合反応に要した時間は重合体粒子（Ｆ）を製造した時と比較して、８０％に短縮されており、また、反応容器内等の汚れ具合も同程度の状態であったことから、生産性の向上が認められた。
【０１５７】
〈トナーの製造実施例８〉
着色剤として「Ｃ．Ｉ．ピグメントレッド２３８」５質量部、非芳香族系有機過酸化物としてｐ−メンタンハイドロパーオキサイド（１０時間半減期温度＝１２８．０℃）５質量部、及び非芳香族系還元剤としてエリソルビン酸を用いることを除いては、トナーの製造実施例１と同様にして重合体粒子（Ｈ）を得た後、マゼンタトナー（Ｈ）を調製した。
【０１５８】
得られたマゼンタトナー（Ｈ）の平均粒径は４．４μｍ、平均円形度は０．９８０で、トナー粗粒着色剤相対比は１．００、トナー粗粒ワックス成分相対比は１．００であった。また、マゼンタトナー（Ｈ）中に残留していたスチレンモノマー量は５０ｐｐｍ以下であった。
【０１５９】
〈トナーの製造実施例９〉
着色剤として「Ｃ．Ｉ．ピグメントイエロー１５５」６質量部、及び非芳香族系有機過酸化物としてｔ−ヘキシルパーオキシイソプロピルモノカーボネート（１０時間半減期温度＝９５．０℃）５質量部、及び非芳香族系還元剤としてアスコルビン酸（水への溶解度＝３３）５質量部を用いることを除いては、トナーの製造実施例１と同様にして重合体粒子（Ｉ）を得た後、イエロートナー（Ｉ）を調製した。
【０１６０】
得られたイエロートナー（Ｉ）の平均粒径は４．２μｍ、平均円形度は０．９７７で、トナー粗粒着色剤相対比は１．００、トナー粗粒ワックス成分相対比は１．００であった。また、残留スチレンモノマー量は５０ｐｐｍ以下であった。
【０１６１】
〈トナーの製造実施例１０〉
非芳香族系有機過酸化物としてｔ−ブチルパーオキシイソブチレート（１０時間半減期温度＝７７．３℃）５質量部を用いることを除いては、トナーの製造実施例９と同様にして重合体粒子（Ｊ）を得た後、イエロートナー（Ｊ）を調製した。
【０１６２】
得られたイエロートナー（Ｊ）の平均粒径は４．３μｍ、平均円形度は０．９７１で、トナー粗粒着色剤相対比は１．００、トナー粗粒ワックス成分相対比は１．００であった。また、残留スチレンモノマー量は５０ｐｐｍ以下であった。
【０１６３】
〈トナーの比較製造例１〉
重合工程には、アスコルビン酸ナトリウム５．０質量部（有機過酸化物の添加量基準で１００ｍｏｌ％）を溶解させた水溶液を一括添加し、添加直後から始まった著しい発熱を利用して、重合性単量体の重合添加率は３０％に達する前に重合温度を８０℃に昇温することを除いては、トナーの製造実施例１と同様にして平均粒径が４．７μｍの比較用重合体粒子（ａ）を得た後、比較用シアントナー（ａ）を調製した。
【０１６４】
得られた比較用シアントナー（ａ）の平均粒径は４．７μｍ、平均円形度は０．９６２で、トナー粗粒着色剤相対比は０．８７、トナー粗粒ワックス成分相対比は０．８０であった。
【０１６５】
〈トナーの比較製造例２〉
重合工程において、アスコルビン酸ナトリウム５．０質量部（有機過酸化物の添加量基準で１００ｍｏｌ％）を溶解させた水溶液を一括添加することを除いては、トナーの製造実施例１と同様にして比較用重合体粒子（ｂ）を得た後、比較用ブラックトナー（ｂ）を調製した。
【０１６６】
得られた比較用ブラックトナー（ｂ）の平均粒径は５．８μｍ、平均円形度は０．９６４で、トナー粗粒着色剤相対比は０．８８、トナー粗粒ワックス成分相対比は１．１２であった。
【０１６７】
〈トナーの比較製造例３〉
分散工程において、非芳香族系有機過酸化物に代え、アゾ系重合開始剤である２，２’−アゾビス（２，４−ジメチルバレロニトリル）５質量部を重合性単量体組成物の調製時に添加することを除いては、トナーの製造実施例８と同様にして平均粒径が４．２μｍ比較用重合体粒子（ｃ）を得た後、比較用マゼンタトナー（ｃ）を調製した。
【０１６８】
得られた比較用マゼンタトナー（ｃ）の平均粒径は４．２μｍ、平均円形度は０．９７２で、トナー粗粒着色剤相対比は０．８８、トナー粗粒ワックス成分相対比は１．１２であった。
【０１６９】
一方、重合開始剤をアゾ系重合開始剤にしたことで、開始剤分解生成物であるＮ_２ガスの発生により、重合工程中に水系分散媒体表面で発泡が起こり、重合体粒子の浮き上がりによる撹拌不良や合一が見られた。また、反応容器の内壁やパドル撹拌翼を観察したところ、水流により洗い落とすことが困難な汚れが付着していた。特に反応容器上部の汚れが著しかった。
【０１７０】
〈トナーの比較製造例４〉
造粒工程において、難水溶性分散剤Ｃａ_３（ＰＯ_４）_２の生成量、高速撹拌装置の回転数と撹拌時間を変更することにより、重合性単量体組成物をより微細に油滴状に懸濁させ、造粒したことを除いては、トナーの比較製造例３と同様にして平均粒径が２．９μｍの比較用重合体粒子（ｄ）を製造し、比較用マゼンタトナー（ｄ）を調製した。
【０１７１】
得られた比較用マゼンタトナー（ｄ）の平均粒径は２．７μｍ、平均円形度は０．９７４で、トナー粗粒着色剤相対比は０．８９、トナー粗粒ワックス成分相対比は１．１０％あった。
【０１７２】
この時、比較用重合体粒子（ｃ）を製造した時と比較して、微粒子トナーが製造できたものの、重合反応に要した時間は同程度であり、難水溶性分散剤Ｃａ_３（ＰＯ_４）_２の生成量や高速撹拌装置の回転数と撹拌時間を変更に際して、原材料や電力消費の増加を要した。
【０１７３】
更に、比較用重合体粒子（ｄ）の製造を連続５回繰り返して行った後、反応容器の内壁やパドル撹拌翼を観察したところ、水流により洗い落とすことが困難な汚れが付着しており、特に反応容器上部の汚れが著しく、清掃等のメンテナンスを要し、生産性の低下を招いた。
【０１７４】
〈トナーの比較製造例５〉
重合開始剤として、レドックス系重合開始剤に代え、分散工程において、重合性単量体組成物の調製時に、芳香族系有機過酸化物であるベンゾイルパーオキサイド５質量部を添加することを除いては、トナーの製造実施例９と同様にして平均粒径が４．１μｍの比較用重合体粒子（ｅ）を得た後、比較用イエロートナー（ｅ）を調製した。
【０１７５】
得られた比較用イエロートナー（ｅ）の平均粒径は４．７μｍ、平均円形度は０．９６３で、トナー粗粒着色剤相対比は０．８８、トナー粗粒ワックス成分相対比は１．１５であった。
【０１７６】
〈トナーの比較製造例６〉
下記成分からなる混合物をアトライター（三井金属社製）を用いて３時間分散させ、重合性単量体組成物を調製した。
・スチレン ７０質量部
・ｎ−ブチルメタクリレート ３０質量部
・着色剤（カーボンブラック、粒径＝５５ｎｍ） ７質量部
・Ｃｒ系染料（保土ヶ谷化学社製、商品名ＴＲＨ） ２質量部
・低分子量ポリプロピレン（融点＝１２０℃） ２質量部
・ｔ−ブチルパーオキシイソブチレート ６．８質量部
（１０時間半減期温度＝７７．３℃）
【０１７７】
次いで、造粒工程において、難水溶性分散剤Ｃａ_３（ＰＯ_４）_２の生成量、水系分散媒体のｐＨ、高速撹拌装置の回転数と撹拌時間を変更することにより、上記重合性単量体組成物を油滴状に懸濁させた後、９５℃で６時間の重合反応を行ったことを除いては、トナーの製造実施例１と同様にして平均粒径が６．５μｍの比較用重合体粒子（ｆ）を製造し、比較用ブラックトナー（ｆ）を調製した。
【０１７８】
得られた比較用ブラックトナー（ｆ）の平均粒径は６．４μｍ、平均円形度は０．９６０で、トナー粗粒着色剤相対比は０．８５、トナー粗粒ワックス成分相対比は０．８２であった。また、トナー中に残留していたスチレンモノマー量は３００ｐｐｍであった。
【０１７９】
一方、水の沸点に近い温度で重合反応を行った為、重合工程中に水系媒体表面で発泡が起こり、重合体粒子の浮き上がりによる撹拌不良や合一が見られた。また、重合反応に要した時間はトナーの製造実施例１で重合体粒子（Ａ）を製造した時と同程度であったにも拘わらず、反応容器の内壁やパドル撹拌翼を観察したところ、非常に強固な汚れが付着していた。特に反応容器上部の汚れが著しかった。
【０１８０】
〈トナーの比較製造例７〉
下記成分からなる混合物をアトライター（三井金属社製）を用いて分散処理を３時間行い、スチレン中に微細に粉砕されたワックス成分が分散するワックス成分分散液を調製した。
・スチレン ３６質量部
・パラフィンワックス（融点＝７０℃） ４質量部
【０１８１】
次いで、下記成分をワックス成分分散液が入ったアトライターに追加投入し、分散処理を更に３時間行い、重合性単量体組成物を調製した。
・スチレン ４７質量部
・２−ブチルアクリレート １７質量部
・ジビニルベンゼン ０．３質量部
・着色剤（カーボンブラック、粒径＝５５ｎｍ） ７質量部
・ｔ−ドデシルメルカプタン １質量部
【０１８２】
次いで、難水溶性分散剤Ｃａ_３（ＰＯ_４）_２を含有する水系分散媒体中に上記重合性単量体組成物投入して油滴状に懸濁させた後、ｔ−ブチルパーオキシネオデカノエート（１０時間半減期温度＝４６．４℃）７質量部を添加し、高速撹拌装置で撹拌して造粒を行った。更に内温を６０℃に昇温して重合反応を開始し、重合転化率が８０％に達した時点でソディウムホルムアルデヒドスルホキシレート５質量部とエチレンジアミン４酢酸鉄ナトリウム０．５質量部を含有する水溶液を投入し、更に加熱撹拌を６時間継続して重合反応を行ったことを除いては、トナーの製造実施例１と同様にして平均粒径が５．０μｍの比較用重合体粒子（ｇ）を製造し、比較用ブラックトナー（ｇ）を調製した。
【０１８３】
得られた比較用ブラックトナー（ｇ）の平均粒径は４．８μｍ、平均円形度は０．９７０で、トナー粗粒着色剤相対比は０．８３、トナー粗粒ワックス成分相対比は１．２５であった。また、トナー中に残留していたスチレンモノマー量は５００ｐｐｍであった。
【０１８４】
一方、重合反応に要した時間は１０時間であり、トナーの製造実施例１で重合体粒子（Ａ）を製造した時と比較し、約１．５倍の時間を要した。また、重合性単量体を留去する為に蒸留工程にも時間を要した為、反応容器の内壁やパドル撹拌翼に非常に強固な汚れが付着した。特に反応容器上部の汚れが著しかった。
【０１８５】
更に難水溶性分散剤Ｃａ_３（ＰＯ_４）_２を含有する水系分散媒体の製造条件を変更したことを除いては上記と同様にして平均粒径が３．５μｍの比較用重合体粒子（ｈ）を製造したが、比較用重合体粒子（ｈ）中に残留していたスチレンモノマー量は３５０ｐｐｍで、重合に要した時間は１０時間のままで、生産性を改善するには至らなかった。
【０１８６】
〈トナーの参考製造例〉
分散工程
下記成分からなる混合物を７０℃に加温して、アトライター（三井金属社製）を用いて３時間分散させ、重合性単量体組成物とした。
・スチレン ９０質量部
・ｎ−エチルヘキシルアクリレート １０質量部
・エチレングリコールジアクリレート ０．０５質量部
・着色剤（Ｃ．Ｉ．ピグメントブルー１５：３） ４質量部
・ポリエステル樹脂 ５質量部
（重量平均分子量＝１万、酸価＝８ｍｇＫＯＨ／ｇ）
・エステルワックス（融点＝６５℃） １０質量部
・ジ−ｔ−ブチルサリチル酸金属錯体 １質量部
【０１８７】
造粒工程
トナーの製造実施例１と同様にして微小な難水溶性分散剤Ｃａ_３（ＰＯ_４）_２を含む水系分散媒体を調製した後、該水系分散媒体中に希塩酸を加え、ｐＨを５．５に調整した後、前記重合性単量体組成物を投入し、内温７０℃のＮ_２雰囲気下で、高速撹拌装置の回転数を１５０００ｒｐｍに維持しつつ、１０分間撹拌し、該重合性単量体組成物を水系媒体中に油滴状に懸濁させ、造粒した。次いで、ｔ−ブチルハイドロパーオキサイド（１０時間半減期温度１６６．５℃）５質量部を添加し、更に造粒を５分間行った。
【０１８８】
重合工程
造粒終了直後にアスコルビン酸ナトリウム６質量部（有機過酸化物の添加量基準で５５ｍｏｌ％）を一括添加し、重合反応を開始させ、更に撹拌装置をパドル撹拌翼を具備したものに換え、８０ｒｐｍの回転数で撹拌しながら７０℃に保持した。重合時間が３時間を経過した時点で重合温度を８０℃に昇温し、更に加熱撹拌を５時間継続した後、重合工程を終了した。
【０１８９】
重合終了後、トナーの製造実施例１と同様にして参考用重合体粒子を得た後、参考用シアントナーを調製した。
【０１９０】
得られた参考用シアントナーの平均粒径は６．２μｍ、平均円形度は０．９８２で、トナー粗粒中の着色剤相対含有率は１．１５、ワックス成分相対含有率は１．１０であった。
【０１９１】
〈実施例１〉
画像形成装置として図１に示したフルカラー画像形成装置を用いた。この時、現像ローラー表面の回転周速が感光体ドラム表面との接触部分において、感光体ドラムの回転駆動に対して同方向に１４０％となるように設定した。
【０１９２】
該画像形成装置の第３の画像形成ユニットには、トナーの製造実施例１で得られたシアントナー（Ａ）を投入し、モノカラーモードにより３２枚（Ａ４サイズ）／分のプリントアウト速度で１万枚分をプリントアウトし、その際に得られたプリントアウト画像の評価を行った。
【０１９３】
これらの評価結果を表１にまとめて示した。
【０１９４】
〈実施例２〜１０〉
シアントナー（Ｂ）〜（Ｅ）は第３の画像形成ユニット、ブラックトナー（Ｆ）と（Ｇ）は第４の画像形成ユニット、マゼンタトナー（Ｈ）は第２の画像形成ユニット、及びイエロートナー（Ｉ）と（Ｊ）は第１の画像形成ユニットの各々に投入した用いることを除いては、実施例１と同様に評価した。
これらの評価結果を表１にまとめて示した。
【０１９５】
〈比較例１〜７〉
比較用シアントナー（ａ）は第３の画像形成ユニット、比較用ブラックトナー（ｂ）と（ｆ）と（ｇ）は第４の画像形成ユニット、比較用マゼンタトナー（ｃ）と（ｄ）は第２の画像形成ユニット、及び比較用イエロートナー（ｅ）は第１の画像形成ユニットの各々に投入して用いることを除いては、実施例１と同様に評価した。
【０１９６】
これらの評価結果を表１にまとめて示した。
【０１９７】
〈参考例〉
参考用シアントナーを第３の画像形成ユニットに投入して用いることを除いては、実施例１と同様に評価した。
【０１９８】
これらの評価結果を表１にまとめて示した。
【０１９９】
上記実施例、及び比較例中に記載の評価項目の説明とその評価基準について述べる。
【０２００】
［評価項目］
〈１〉画像濃度
通常の複写機用普通紙（７５ｇ／ｍ^２）に一辺が５ｍｍの正方形のベタ黒画像をプリントアウトし、「マクベス反射濃度計ＲＤ９１８」（マクベス社製）を用いて、原稿濃度が０．００の白地部分のプリントアウト画像に対する相対濃度を測定した。
Ａ： １．４０以上
Ｂ： １．３５以上、１．４０未満
Ｃ： １．００以上、１．３５未満
Ｄ： １．００未満
【０２０１】
〈２〉画像カブリ
ベタ白画像形成時、現像工程後から転写工程に移行する間に感光体ドラム上に存在するトナーをマイラーテープによってテーピングして剥ぎ取り、それを紙上に貼ったものの反射濃度を「マクベス反射濃度計ＲＤ９１８」で測定する。得られた反射濃度から、マイラーテープをそのまま紙上に貼った時の反射濃度を差し引いた数値を用いて評価した。数値が小さい程、画像カブリが抑制されていることになる。
Ａ： ０．０３未満
Ｂ： ０．０３以上、０．０７未満
Ｃ： ０．０７以上、１．００未満
Ｄ： １．００以上
【０２０２】
〈３〉細線の再現性
グラフィカルな画像の画質や階調性に関わる評価であり、図２に示す様なプリントアウト画像の細線の再現性を評価した。
Ａ： 良好な細線の再現性を示す
Ｂ： 軽微な細線の幅の変動が見られる
Ｃ： 細線の細りや飛び散りが目立つ
Ｄ： 所々で細線の断裂が見られ、再現性に劣る
【０２０３】
〈４〉ドット再現性
潜像電界によって電界が閉じ易く、再現しにくい図３に示す様な小径（４０μｍ）の孤立ドットパターンの画像をプリントアウトし、そのドット再現性を評価した。
Ａ： １００個中の欠損が２個以下
Ｂ： １００個中の欠損が３〜５個
Ｃ： １００個中の欠損が６〜１０個
Ｄ： １００個中の欠損が１１個以上
【０２０４】
〈５〉画像白抜け
円形画像（直径２０ｍｍ）を５箇所に配した画像をプリントアウトし、該画像上に発生した１００μｍ以上の画像白抜けの発生箇所を計測して評価した。
Ａ： 未発生
Ｂ： 画像白抜けが５個以下
Ｃ： ６〜１０個
Ｄ： １１個以上
【０２０５】
〈６〉現像ローラーとのマッチング
プリントアウト試験終了後、現像ローラー表面と該ローラー表面のトナー薄層の様子、及びプリントアウト画像への影響を目視で評価した。
Ａ： ローラー表面やトナー薄層の状態は良好である
Ｂ： ローラー表面に汚染が発生しているが、固着はほとんど発生せず
Ｃ： ローラー表面に軽微な固着があるが、画像への影響が少ない
Ｄ： ローラー表面に固着を生じ、縦スジ状の画像欠陥が発生
【０２０６】
【表１】

【０２０７】
〈実施例１１〉
画像形成装置として図１に示したフルカラー画像形成装置の第１の画像形成ユニットにはイエロートナー（Ｉ）と（Ｊ）、第２の画像形成ユニットにはマゼンタトナー（Ｈ）、第３の画像形成ユニットにはシアントナー（Ａ）〜（Ｅ）、及び第４の画像形成ユニットにはブラックトナー（Ｆ）と（Ｇ）の各々のトナーを順次投入し、３２枚（Ａ４サイズ）／分のプリントアウト速度でグラフィック画像をフルカラーモードによりプリントアウト試験を行った。
【０２０８】
得られたグラフィック画像は、何れのトナーの組合せにおいても色再現性や細線の再現性に優れると共に、画像白抜けの発生もなく、良好な結果を得た。
【０２０９】
〈比較例８〉
第１の画像形成ユニットには比較用イエロートナー（ｅ）、第２の画像形成ユニットにはマゼンタトナー（ｃ）と（ｄ）、第３の画像形成ユニットにはシアントナー（ａ）、及び第４の画像形成ユニットにはブラックトナー（ｂ）の各々のトナーを順次投入し、実施例１１と同様にしてフルカラーモードによりプリントアウト試験を行った。
【０２１０】
得られたフルカラー画像は、色再現性や細線の再現性に劣るだけでなく、画像白抜けや現像ローラーへのトナー固着に起因する縦スジ状の画像欠陥が発生したものもあった。
【０２１１】
【発明の効果】
以上に説明したように、本発明によれば、少なくとも、重合性単量体と着色剤を含有する重合性単量体組成物を水系分散媒体中に油滴状に懸濁させ、重合することにより重合体粒子を製造することにより製造される乾式トナーの製造方法において、重合開始剤として、非芳香族系有機過酸化物と非芳香族系還元剤からなるレドックス系重合開始剤を選択し、該非芳香族系還元剤の添加時期を特定することにより、画像形成装置とのマッチングに優れ、高解像度で高精細の画像形成を行うことが出来るトナーを製造することが出来る。
【０２１２】
また、既存の設備を大幅に改造することなく、生産性を高め、より微粒子径のトナーを製造することが出来る。
【図面の簡単な説明】
【図１】本発明の実施例に用いたフルカラー画像形成装置を示す概略的説明図である。
【図２】細線の再現性と定着状態を評価する為のライン画像の説明図である。
【図３】解像度を評価する為の小径孤立ドットパターンの説明図である。
【符号の説明】
１６ａ〜１６ｄ 帯電ローラー
１７ａ〜１７ｄ 現像ローラー
１８ａ〜１８ｄ クリーニング装置
１９ａ〜１９ｄ 感光体ドラム
２０ 転写材搬送ベルト
Ｐａ 第１色目の現像ユニット
Ｐｂ 第２色目の現像ユニット
Ｐｃ 第３色目の現像ユニット
Ｐｄ 第４色目の現像ユニット
Ｓ 転写材[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for producing a dry toner used in a recording method using an electrophotographic method, an electrostatic recording method, a magnetic recording method, a toner jet method, and the like, and a dry toner. More specifically, the present invention relates to a method for producing a dry toner used in an image recording apparatus that can be used in a copying machine, a printer, a facsimile, a plotter, and the like, and a dry toner.
[0002]
[Prior art]
Although many methods are known as electrophotography, generally, a photoconductive substance is used and an electrostatic latent image is formed on an electrostatic image carrier (hereinafter, referred to as a "photoconductor") by various means. Is formed, and then the latent image is developed with a toner to form a visible image.If necessary, the toner image is transferred to a recording medium such as paper, and then the toner image is fixed on the recording medium by heat or pressure. Then, a fixed image is obtained. When a step of transferring a toner image is provided, a step for removing the transfer residual toner on the photoconductor is usually provided, and the above-described steps are repeated.
[0003]
In particular, in full-color image formation, in general, an electrostatic latent image is developed using magenta toner, cyan toner, yellow toner, and black toner, and a multicolor image is reproduced by superimposing toner images of each color. ing.
[0004]
In recent years, the field of application of the image forming apparatus using the electrophotography as described above is not only a copying machine for copying an original document, but also a printer as a computer output, or a personal copy for an individual, and furthermore, It has rapidly evolved into plain paper fax and the like, and furthermore, a variety of demands are increasing. In addition, digital copiers are also becoming more sophisticated. In particular, the size, speed, and color of the image forming apparatus are remarkably reduced, and there is a strong demand for high reliability and high resolution. For example, the resolution, which was initially 200 to 300 dpi (dot per inch), is now increasing to 400 to 1200 dpi, and more than 2400 dpi.
[0005]
In response to the demands described above, image forming apparatuses have been designed with simpler components by using members having high functionality in various points. As a result, the functionality required of the toner is further enhanced, and if the performance improvement due to the high functionality of the toner, such as miniaturization and shape control of the toner particles and further optimization of the internal structure, cannot be achieved, The fact is that excellent image forming apparatuses are no longer feasible.
[0006]
Although various methods are known for producing the toner used in the image forming apparatus as described above, generally, a binder resin, a colorant, and the like are melt-kneaded by a heating / pressing kneader or the like, and then cooled. A method of finely pulverizing a kneaded product to a desired toner particle size and further classifying the finely pulverized product to adjust the particle size distribution to produce a toner (hereinafter, referred to as “pulverization method”) is widely used. However, in the pulverization method as described above, not only the production of fine particles and control of the shape of the toner particles causes a decrease in productivity, but also there is a limit in actively designing the internal structure of the toner particles.
[0007]
On the other hand, in order to overcome the problems of the toner production by the pulverization method as described above, and to further improve the performance by enhancing the functions of the toner, the toner production by the “polymerization method” has been carried out. Are roughly classified into a suspension polymerization method and an emulsion polymerization method.
[0008]
When producing a toner by a suspension polymerization method, a polymerizable monomer, a colorant, and a polymerization initiator, and if necessary, additives such as a crosslinking agent and a charge control agent are uniformly dissolved or dispersed. After forming the monomer composition, the monomer composition is suspended in an oil-based dispersion medium in an aqueous dispersion medium containing a dispersion stabilizer in advance using a suitable stirrer, and then the polymerization reaction is performed. The oil droplets are solidified to obtain toner particles having a desired particle size.
[0009]
In the suspension polymerization method as described above, not only can the toner particles be finely divided and the shape thereof controlled while maintaining high productivity, but also the polarity or non-polarity in the monomer composition forming oil droplets can be increased. The surface layer and the internal structure of the toner particles can be positively designed by appropriately adding a component exhibiting the following.
[0010]
At present, toner production by the polymerization method is mainly performed by a batch production method, and the polymerization of the monomer composition is completed to further improve the productivity without significantly modifying existing equipment. (Hereinafter, referred to as “polymerization time”).
[0011]
In general, methods for shortening the polymerization time include changing the type and amount of a polymerization initiator, changing reaction conditions such as polymerization temperature, and the like.In these cases, binding generated by the polymerization reaction is used. It has a significant effect on the molecular weight distribution and molecular structure of the resin, as well as the residual amount of initiator decomposed products and polymerizable monomers in the toner particles, so that the developability and fixability of the toner may change significantly. In the worst case, a great problem occurs in matching with the image forming apparatus.
[0012]
For example, Patent Document 1 discloses a method of producing a toner by using a non-aromatic organic peroxide having a molecular weight of 250 or less as a polymerization initiator and performing suspension polymerization at a polymerization temperature of 75 to 100 ° C. Have been. However, although the above-mentioned production methods are effective in suppressing the amount of polymerizable monomers remaining in the toner particles and odor, etc., they not only require the polymerization reaction in a relatively high temperature range but also initiate the polymerization. The rapid heat generation accompanying the decomposition reaction of the agent makes it difficult to control the shape of the toner particles. In particular, this tendency becomes more remarkable when an attempt is made to make toner particles finer or lower the melting point of the wax component for the purpose of increasing the resolution and fixing at a low temperature of the toner. Oozes out to the surface layer of the toner particles.
[0013]
Further, in Patent Document 2, after a polymerizable monomer composition containing an oil-soluble polymerization initiator is suspended in an aqueous dispersion medium to form droplets, the polymerization conversion rate of the polymerizable monomer is 30 to There is disclosed a method for producing a toner by adding a reducing agent for a redox initiator to the aqueous dispersion medium when the content is within the range of 95% and continuing suspension polymerization. However, even in the above-mentioned production methods, the addition of the redox initiator reducing agent in a situation where the polymerization conversion rate is low not only causes the above-described problems, but also in a situation where the polymerization conversion rate is high, the reduction for the redox initiator. When the agent is added, the amount of the polymerizable monomer remaining in the toner particles increases.
[0014]
None of the toners obtained by the above-described manufacturing methods have sufficient fineness and shape control of the toner particles, and further, optimization of the internal structure. It has become difficult to deal with them, and further enhancements in functionality were required.
[0015]
Further, in the above-described manufacturing method, the productivity of the toner is not considered, and improvement is required.
[0016]
[Patent Document 1]
JP-A-10-20548
[Patent Document 2]
JP-A-11-202553
[0017]
[Problems to be solved by the invention]
An object of the present invention is to solve the problems of the related art, provide a method of manufacturing a dry toner excellent in matching with an image forming apparatus, and excellent in forming a high-resolution and high-definition image, and a dry toner. It is in.
[0018]
SUMMARY OF THE INVENTION An object of the present invention is to provide a dry toner manufacturing method and a dry toner capable of increasing productivity and manufacturing a toner having a finer particle diameter without significantly modifying existing equipment.
[0019]
[Means for solving the problem]
The present invention provides a dispersion step of preparing a polymerizable monomer composition containing at least a polymerizable monomer and a colorant, and suspending the polymerizable monomer composition in an oil-based dispersion medium in an aqueous dispersion medium. Granulating step, and a method for producing a dry toner produced by passing through a polymerization step of producing polymer particles by polymerizing the polymerizable monomer composition using a polymerization initiator,
(1) The polymerization initiator is a redox polymerization initiator comprising a non-aromatic organic peroxide and a non-aromatic reducing agent,
(2) the non-aromatic organic peroxide is added to the polymerizable monomer composition during the dispersion step and / or the granulation step,
(3) The non-aromatic reducing agent is preliminarily added to the aqueous dispersion medium separately from the non-aromatic organic peroxide during the granulation step and / or the polymerization step, and the polymerization of the polymerizable monomer is further performed. It is added after the conversion rate has progressed 10% or more.
And a method for producing a dry toner.
[0020]
Further, the present invention, at least, after suspending the polymerizable monomer composition containing a polymerizable monomer and a colorant in the form of oil droplets, the polymerizable monomer composition is non-aromatic A dry toner obtained by polymerization with a redox polymerization initiator comprising an organic peroxide and a non-aromatic reducing agent, wherein the toner has a circle-equivalent number average diameter of 2 in a number-based particle size frequency distribution. ６6 μm, the average circularity in the circularity frequency distribution is 0.965 to 0.995, and the 635-mesh sieve (opening diameter = 20 μm) present in the toner relative to the content of the colorant in the toner. Wherein the relative ratio of the content of the colorant in the coarse particles of the toner that does not pass through is 0.90 to 1.10.
[0021]
Preferred embodiments of the present invention are as follows.
[0022]
The non-aromatic organic peroxide is an oil-soluble polymerization initiator having a 10-hour half-life temperature of 75 to 150 ° C., and the non-aromatic reducing agent has a solubility in water (gram soluble in 100 g of water at 25 ° C.). Wherein the number is 10 or more.
[0023]
The non-aromatic organic peroxide is an oil-soluble polymerization initiator having a 10-hour half-life temperature of 90 to 110 ° C., and the non-aromatic reducing agent has a solubility in water (grams soluble in 100 g of water at 25 ° C.). (3) is 30 or more.
[0024]
The polymerizable monomer composition contains a wax component,
(1) the melting point of the wax component is 50 to 130 ° C.,
(2) At least until the polymerization addition rate of the polymerizable monomer composition reaches 30%.
Keep the polymerization temperature below the melting point of the wax component
A method for producing the dry toner described above.
[0025]
A method for producing the dry toner, wherein the polymerizable monomer composition contains 0.1 to 3 parts by mass of Cu phthalocyanine and / or a Cu phthalocyanine derivative together with a colorant per 100 parts by mass of the polymerizable monomer. .
[0026]
A dry toner containing a wax component, wherein the content of the wax component in the coarse particles of the toner that does not pass through a 635-mesh sieve (opening diameter = 20 μm) existing in the toner with respect to the wax component content (Wa) in the toner. The dry toner according to claim 1, wherein a relative ratio (Wb / Wa) of the ratio (Wb) is 0.85 to 1.20.
[0027]
BEST MODE FOR CARRYING OUT THE INVENTION
The present inventors, as a result of intensive study, when producing a dry toner by a suspension polymerization method, while using a redox polymerization initiator having a non-aromatic organic peroxide and a non-aromatic reducing agent, By specifying their addition methods, etc., it is possible to produce dry toners with good matching with image forming equipment, high resolution and high definition image formation without significant modification of existing equipment with high productivity. The present inventors have found that it is possible to produce, and have reached the present invention.
[0028]
(Production method of dry toner)
The method for producing a dry toner according to the present invention includes at least a dispersing step of preparing a polymerizable monomer composition containing a polymerizable monomer and a colorant, and dispersing the polymerizable monomer composition in an aqueous dispersion medium. A granulation step of suspending in an oil droplet form, and a dry toner produced by passing through a polymerization step of producing polymer particles by polymerizing the polymerizable monomer composition using a polymerization initiator. In the production method, (1) the polymerization initiator is a redox polymerization initiator having a non-aromatic organic peroxide and a non-aromatic reducing agent, and (2) the non-aromatic organic peroxide Is added to the polymerizable monomer composition during the dispersion step and / or the granulation step, and (3) the non-aromatic reducing agent is non-aromatic during the granulation step and / or the polymerization step. Separately added to the aqueous dispersion medium separately from the organic peroxide, Polymerizable polymerization conversion of the monomer is characterized in that it is added added after traveling more than 10%.
[0029]
In the method for producing a toner of the present invention, by combining a non-aromatic organic peroxide with a non-aromatic reducing agent as a polymerization initiator, the temperature is lower than when using a non-aromatic organic peroxide alone. A redox-based polymerization initiator capable of generating radicals (hereinafter referred to as "redoxing") is used. However, the present inventors have proposed the addition of a non-aromatic organic peroxide and a non-aromatic reducing agent. The inventors have found that the method and the timing of addition are very important in producing a highly functional toner with high productivity, and have completed the present invention.
[0030]
The polymerizable monomer composition according to the dry toner production method of the present invention includes at least a polymerizable monomer and a colorant, and further includes a polymerization initiator, a crosslinking agent, a charge control agent, and a wax component, if necessary. It is prepared by uniformly dissolving or dispersing various additives.
[0031]
In the present invention, the non-aromatic organic peroxide is added to the polymerizable monomer composition during the dispersion step and / or the granulation step. When added after the granulation step, the non-aromatic organic peroxide is non-uniformly contained in the oil droplets of the monomer composition suspended in the aqueous dispersion medium. Differences occur in the state of polymerization between the particles. As a result, it becomes difficult to produce a uniform toner. This phenomenon occurs when redox formation is performed by adding a reducing agent after addition of an organic peroxide or when a fine particle toner in which the number of oil droplets of a monomer composition suspended in an aqueous dispersion medium increases is manufactured. It becomes remarkable.
[0032]
In the method for producing a toner according to the present invention, the non-aromatic reducing agent is preliminarily added to the aqueous dispersion medium separately from the non-aromatic organic peroxide during the granulation step and / or the polymerization step. It is additionally added after the polymerization conversion of the hydrophilic monomer composition has advanced by 10% or more. This makes it possible to safely produce high-performance toner with high productivity.
[0033]
In the dispersing step, when a non-aromatic reducing agent is contained in the polymerizable monomer composition together with the organic peroxide, redox formation is performed at an early stage. For this reason, radicals are suddenly generated by slight heating, and then the polymerization reaction proceeds in a chain, which makes it difficult to control, and as a result, oil droplets of the monomer composition suspended in the aqueous dispersion medium When the reaction heat generated therein accumulates heat, it becomes difficult to control the shape and internal structure of the obtained toner particles. Further, in a remarkable case, since a part of the polymerizable monomer is vaporized or a wax component oozes out of the oil droplet, a toner having a colorant or a wax component exceeding 20 μm in which the colorant and the wax component are segregated in the toner particles is used. Coarse particles are generated, which has a serious problem on toner performance and matching with an image forming apparatus.
[0034]
The addition amount of the non-aromatic reducing agent according to the present invention is preferably from 30 to 150 mol%, particularly preferably from 50 to 100 mol%, based on the addition amount of the organic peroxide used in the form of redox. . When the addition amount of the non-aromatic reducing agent is less than 30 mol%, not only the effect obtained by redox formation is reduced, but also the non-aromatic reducing agent is uniformly dispersed throughout the oil droplets suspended in the aqueous dispersion medium. This is not preferable because the agent is not supplied and a difference occurs in polymerization between toner particles. Further, even if it is added in excess of 150 mol%, the effect on redox formation is not further enhanced, and conversely, the residual amount in the toner particles after the reaction is completed becomes considerable, which may affect the charging characteristics of the toner. Not only that, it becomes difficult to remove the toner during the production of the toner, leading to a decrease in productivity.
[0035]
On the other hand, the non-aromatic reducing agent according to the present invention is preliminarily added to the aqueous dispersion medium separately from the non-aromatic organic peroxide during the granulation step and / or the polymerization step, and the polymerization is further performed. The non-aromatic reducing agent is added in advance after the polymerization conversion rate of the hydrophilic monomer progresses by 10% or more, but the amount of the organic peroxide used in the form of redox with the non-aromatic reducing agent is used. It is preferably limited to 20 to 70 mol%, more preferably 30 to 60 mol%, based on the amount (hereinafter referred to as “the basis of the added amount of organic peroxide”), and the remaining non-aromatic reducing agent is polymerized. It is added sequentially after the conversion has progressed 10% or more, or added continuously.
[0036]
When the amount of the non-aromatic reducing agent added in advance in the aqueous dispersion medium during the granulation step and / or the polymerization step is less than 20 mol% (based on the amount of the organic peroxide), redox formation is performed. Not only the obtained effect is not sufficiently obtained, but also the non-aromatic reducing agent is not uniformly supplied to the entire oil droplets suspended in the aqueous dispersion medium, which causes a difference in polymerization between toner particles. Not preferred. On the other hand, if it is added in excess of 60 mol%, it becomes difficult to control the polymerization reaction, and it becomes difficult to control the shape of the obtained toner particles.
[0037]
The non-aromatic reducing agent added beforehand to the aqueous dispersion medium during the granulation step and / or the polymerization step is added before the polymerization conversion rate exceeds 30% in consideration of the productivity of the toner. Is preferred. Even if a non-aromatic reducing agent is added after the polymerization conversion rate exceeds 30% and redox conversion is performed, productivity cannot be significantly improved. The present inventors have found that, even though the non-aromatic reducing agent is absorbed in the oil droplets of the polymerizable monomer composition, the polymerization reaction has already been started from inside the polymer particles, for the reason of the above phenomenon. For this reason, it is considered that the diffusion of the non-aromatic reducing agent in the oil droplets becomes difficult and is not reflected in the improvement of the productivity of the toner.
[0038]
According to the method for producing a toner of the present invention, the non-aromatic reducing agent added to the aqueous dispersion medium is a polymerizable monomer containing a non-aromatic organic peroxide suspended in oil droplets. It is absorbed by the composition, redoxed, and participates in the polymerization reaction. Therefore, when the oil droplets of the polymerizable monomer composition are made finer by a high-speed stirrer or a dispersant formulation for the purpose of making the toner particles finer, the absorption of the non-aromatic reducing agent becomes more frequent. As a result, the polymerization reaction is promoted, and the productivity is improved. That is, it is possible to manufacture a toner having a finer particle diameter while increasing productivity without significantly modifying existing equipment. This is a great feature not found in the conventional toner manufacturing method, in which it was not possible to achieve both toner fineness and productivity.
[0039]
Furthermore, it is one of the preferred embodiments of the present invention that the polymerizable monomer composition contains 0.1 to 10 parts by mass of a conventionally known phthalocyanine or a phthalocyanine derivative per 100 parts by mass of the polymerizable monomer. Yes, this can increase the polymerization rate and increase productivity.
[0040]
The non-aromatic organic peroxide according to the present invention is preferably selected from the group of peroxydicarbonates, peroxyesters, hydroperoxides and the like.
[0041]
Among these, a toner having a 10-hour half-life temperature of 75 to 150 ° C., particularly preferably 90 to 110 ° C., can impart desirable properties to the toner. When an organic peroxide having a 10-hour half-life temperature of less than 75 ° C. is used as a redox initiator in combination with a reducing agent, the polymerization reaction is difficult to control because of high reactivity, and it is difficult to obtain a good toner. It becomes. Further, when an organic peroxide having a 10-hour half-life temperature exceeding 150 ° C. is used, it is difficult to complete the suspension polymerization reaction sufficiently, and the amount of the polymerizable monomer remaining in the toner particles increases. And so on.
[0042]
Examples of the non-aromatic organic peroxide preferably used in the present invention include t-butylperoxyisobutyrate (10-hour half-life temperature = 77.3 ° C.), t-hexylperoxyisopropyl monocarbonate (10 Time half-life temperature = 95.0 ° C.), t-butylperoxyisopropyl monocarbonate (10-hour half-life temperature = 98.7 ° C.), p-menthane hydroperoxide (10-hour half-life temperature = 128.0 ° C.) And the like.
[0043]
In the present invention, in addition to the polymerization initiator as described above, a conventionally known azo initiator or peroxide initiator is used in combination within a range that does not adversely affect the toner performance and productivity, and the polymerization reaction is performed. Can be controlled.
[0044]
On the other hand, the non-aromatic reducing agent according to the present invention is preferably water-soluble, and has a solubility in water (the number of grams soluble in 100 g of water at 25 ° C.) of 10 or more, preferably 30 or more. By using the group-based reducing agent, the control of the polymerization reaction is facilitated, and a good toner can be obtained. If the solubility in water is less than 10, it becomes difficult to uniformly supply the reducing agent into the oil droplets of the monomer composition suspended in the aqueous dispersion medium. A difference occurs in the polymerization state, and it becomes impossible to produce a uniform toner.
[0045]
Non-aromatic reducing agents preferably used in the present invention include, for example, sodium ascorbate (solubility in water = 89), ascorbic acid (solubility in water = 33), sodium erythorbate (solubility in water = 16) ), Erythorbic acid (solubility in water = 53), and the like.
[0046]
The water-soluble non-aromatic reducing agent is also preferable in that it can be easily removed from the surface of the toner particles after the reaction.
[0047]
As the polymerizable monomer according to the present invention, a polymerizable vinyl monomer is particularly preferably used. Specifically, styrene; styrene-based monomers such as o- (m-, p-) methylstyrene and m- (p-) ethylstyrene; methyl (meth) acrylate, ethyl (meth) acrylate, (meth) ) Propyl acrylate, butyl (meth) acrylate, octyl (meth) acrylate, dodecyl (meth) acrylate, stearyl (meth) acrylate, behenyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, (Meth) acrylate monomers such as dimethylaminoethyl (meth) acrylate and diethylaminoethyl (meth) acrylate; ene monomers such as butadiene, isoprene, cyclohexene, (meth) acrylonitrile and acrylamide It is preferably used. These may be used alone or generally in such a way that the theoretical glass transition temperature (Tg) described in the published Polymer Handbook, 2nd edition III-P139-192 (manufactured by John Wiley & Sons) indicates 40-75 ° C. The monomers are appropriately mixed and used. If the theoretical glass transition temperature is lower than 40 ° C., problems tend to occur in terms of storage stability and durability stability of the toner. This leads to poor reproducibility. In particular, when a color toner for forming a full-color image is manufactured, the color mixing property of each color toner at the time of fixing is reduced, the color reproducibility is poor, and the transparency of the OHP image is further reduced.
[0048]
For example, “DSC-7” (manufactured by PerkinElmer) is used to measure the glass transition temperature (Tg) of the toner, and is measured according to “ASTM D3418-82”. Specifically, the melting point of iridium and zinc was used for the temperature correction of the device detection unit, and the heat of fusion of iridium was used for the correction of the calorific value.The measurement sample was placed in an aluminum pan and the control sample was made of aluminum for comparison. A bread-only one (empty bread) was set, and the measurement range of 20 to 180 ° C. was raised and lowered at 10 ° C./min to remove the previous history, and then measured again at a temperature rising rate of 10 ° C./min. From the DSC curve obtained by the midpoint method.
[0049]
Further, in the present invention, it is preferable to use a crosslinking agent at the time of synthesizing the binder resin in order to enhance the mechanical strength and color reproducibility of the toner particles.
[0050]
As the crosslinking agent used in the present invention, divinylbenzene, bis (4-acryloxypolyethoxyphenyl) propane, ethylene glycol diacrylate, 1,3-butylene glycol diacrylate, 1,4- Butanediol diacrylate, 1,5-pentanediol diacrylate, 1,6-hexanediol diacrylate, neopentyl glycol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, tetraethylene glycol diacrylate, polyethylene glycol # 200, # 400 and # 600 diacrylate, dipropylene glycol diacrylate, polypropylene glycol diacrylate, polyester diacrylate (MANDA Kayaku), and those obtained by changing the methacrylates of the above diacrylate.
[0051]
Examples of polyfunctional crosslinking agents include pentaerythritol triacrylate, trimethylolethane triacrylate, trimethylolpropane triacrylate, tetramethylolmethanetetraacrylate, oligoester acrylate and its methacrylate, 2,2-bis (4-methacryloxy, polyethoxy). Phenyl) propane, diallyl phthalate, triallyl cyanurate, triallyl isocyanurate and triallyl trimellitate.
[0052]
These crosslinking agents are preferably used in an amount of preferably 0.05 to 10 parts by mass, more preferably 0.1 to 5 parts by mass, based on 100 parts by mass of the other vinyl monomer.
[0053]
As the colorant according to the present invention, carbon black, a magnetic material, and a black color tone using a yellow / magenta / cyan colorant shown below are used as the black colorant. In particular, it is necessary to select a material that does not cause polymerization inhibition or water phase migration during toner production. Further, the surface of the colorant may be subjected to a modification treatment (for example, a hydrophobic treatment without inhibiting polymerization) before use.
[0054]
As the yellow colorant, compounds represented by a condensed azo compound, an isoindolinone compound, an anthraquinone compound, an azo metal complex, a methine compound, and an allylamide compound are used. Specifically, C.I. I. Pigment Yellow 12, 13, 14, 15, 17, 62, 74, 83, 93, 94, 95, 109, 110, 111, 128, 129, 147, 168, 180 and the like are preferably used.
[0055]
As the magenta colorant, a condensed azo compound, a diketopyrrolopyrrole compound, an anthraquinone, a quinacridone compound, a basic dye lake compound, a naphthol compound, a benzimidazolone compound, a thioindigo compound, and a perylene compound 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 and 254 are preferably used.
[0056]
As the cyan coloring agent, a copper phthalocyanine compound and its derivative, an anthraquinone compound, a basic dye lake compound and the like can be used. Specifically, C.I. I. Pigment Blue 1, 7, 15, 15: 1, 15: 2, 15: 3, 15: 4, 60, 62, 66 and the like are suitably used.
[0057]
These colorants can be used alone or as a mixture, or in the form of a solid solution. The colorant used in the present invention is selected from the viewpoints of hue angle, saturation, lightness, weather resistance, OHP transparency, and dispersibility in toner. The amount of the coloring agent to be added is 1 to 10 parts by mass based on 100 parts by mass of the binder resin.
[0058]
Further, the toner of the present invention may contain a magnetic material as a coloring agent and be used as a magnetic toner. 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 aluminum, cobalt, copper, lead, magnesium, and tin of these metals. And alloys of metals such as zinc, antimony, beryllium, bismuth, cadmium, calcium, manganese, selenium, titanium, tungsten, and vanadium, and mixtures thereof.
[0059]
The magnetic material used in the present invention is more preferably a surface-modified magnetic material, and when used in a polymerization toner, is subjected to a hydrophobic treatment with a surface modifier which is a substance having no polymerization inhibition. Are preferred. Examples of such a surface modifier include a silane coupling agent and a titanium coupling agent.
[0060]
The average particle size of these magnetic materials is preferably from 0.1 to 0.5 μm. The amount added to the toner particles is 40 to 200 parts by mass, preferably 50 to 150 parts by mass, per 100 parts by mass of the binder resin.
[0061]
Specific examples of the wax component according to the present invention include paraffin wax, microcrystalline wax, petroleum wax such as petrolactam and derivatives thereof, montan wax and derivatives thereof, hydrocarbon wax and derivatives thereof by Fischer-Tropsch method, and polyethylene. Natural waxes such as polyolefin waxes and derivatives thereof, carnauba wax, candelilla wax, and derivatives thereof, and the like. Derivatives also include oxides, block copolymers with vinyl monomers, and graft-modified products. It is. In addition, alcohols such as higher aliphatic alcohols; fatty acids such as stearic acid and palmitic acid or compounds thereof; acid amides, esters, ketones, hydrogenated castor oil and derivatives thereof, vegetable waxes, and animal waxes. These can be used alone or in combination.
[0062]
Among these, when polyolefin, hydrocarbon wax by petroleum wax, petroleum-based wax, higher alcohol, or higher ester is used, the effect of improving developability and transferability is further enhanced. Incidentally, an antioxidant may be added to these wax components as long as the chargeability of the toner is not affected. Further, it is preferable to use 1 to 30 parts by mass of these wax components with respect to 100 parts by mass of the binder resin.
[0063]
When the wax component according to the present invention is an ester wax having an ester compound having a structure represented by the following formula (1), the wax component exhibits good fixability, and exhibits a phase after being heat-fixed to the monoazo pigment composition as described above. Since it is excellent in solubility, it is possible to improve the color reproducibility of a printout image and the transparency when a transmission image is formed by an overhead projector.
R_a-COO-R_b        … Equation (1)
[R_aAnd R_bRepresents an alkyl group having 15 to 45 carbon atoms. ]
[0064]
The wax component used in the present invention preferably has a melting point in the range of 50 to 130 ° C.
[0065]
By using a wax component having the above-described thermal characteristics, not only good fixability of the obtained toner but also a releasing effect by the wax component is efficiently exhibited, and a sufficient fixing region is ensured. A color image exhibiting excellent color reproducibility can be obtained, and the development properties, blocking resistance and adverse effects on the image forming apparatus due to conventionally known wax components can be eliminated.
[0066]
When a wax component exhibiting the above-mentioned thermal characteristics is contained in the toner, the polymerization temperature is maintained at or below the melting point of the wax component at least until the polymerization conversion of the polymerizable monomer composition reaches 30%. However, it is preferable from the viewpoints of controlling the shape and internal structure of the toner particles, preventing generation of coarse toner particles, and preventing contamination in the reaction vessel.
[0067]
The melting point of the wax component is determined from the main endothermic peak temperature in the DSC curve measured according to “ASTM D3418-82”. For example, using “DSC-7” (manufactured by Perkin Elmer) as described above, The main endothermic peak temperature is determined from the DSC curve obtained when the temperature of the measurement region of -180 ° C is increased at a temperature increasing rate of 10 ° C / min, and this is defined as the melting point. When only the wax component is measured, the measurement is started after the temperature is increased and decreased under the same conditions as the measurement and the previous history is removed. When the wax component contained in the toner is measured, the measurement is performed as it is without performing the operation of removing the previous history.
[0068]
The incorporation of a charge control agent into the polymerizable monomer composition according to the present invention is one of the preferred embodiments, and in particular, a polymer having a sulfonic acid group is useful for producing a toner using a redox polymerization initiator. Desirable chargeability can be imparted to the toner without adversely affecting the toner.
[0069]
Examples of the polymer having a sulfonic acid group preferably used in the present invention include a polymer type compound having a sulfonic acid group in a side chain, and in particular, a sulfonic acid group-containing (meth) acrylamide monomer having a copolymerization ratio of 2 The styrene and / or styrene (meth) acrylate copolymer having a glass transition temperature (Tg) of 40 to 90 ° C. containing at least 5% by mass, preferably at least 5% by mass has a more excellent toner particle and surface structure. As a result, the developability and the chargeability can be preferably improved.
[0070]
As the sulfonic acid group-containing (meth) acrylamide-based monomer as described above, those represented by the following formulas (2) and (3) are preferable. Specifically, 2-acrylamido-2-methylpropanesulfonic acid and Methacrylamide-2-methylpropanesulfonic acid and the like.
[0071]
Embedded image

[0072]
The above-mentioned polymer containing a sulfonic acid group forms a salt structure at a portion of the sulfonic acid group by adding an inorganic compound containing an alkali metal and / or an alkaline earth metal during toner production. In particular, in the case of a high molecular compound using a sulfonic acid group-containing (meth) acrylamide-based monomer as described above, the formation of a sulfobetaine structure in the molecule is suppressed, thereby preventing hydration while preventing hydration. Since the interaction can be ensured, the chargeability of the toner with respect to environmental changes is further improved. In particular, when a dispersion stabilizer containing an alkali metal and / or an alkaline earth metal as described below is used when producing a toner by a suspension polymerization method, a salt structure with a sulfonic acid group can be easily formed. It is preferable because it is possible.
[0073]
Examples of the alkali metal or alkaline earth metal capable of forming a salt structure with the sulfonic acid group as described above include lithium, sodium, potassium, calcium, barium, beryllium, magnesium and the like, with calcium being preferred.
[0074]
As other charge control agents used in the present invention, known charge control agents can be used, but in particular, the polymerization inhibitory property is low, there is substantially no solubilized substance in the aqueous dispersion medium, and a constant charge amount is stabilized. A charge control agent that can be maintained at a constant level is preferred. Specific compounds include salicylic acid, alkyl salicylic acid, dialkyl salicylic acid, naphthoic acid, metal compounds of aromatic carboxylic acids such as dicarboxylic acids, metal salts or metal complexes of azo dyes or azo pigments, and sulfones as negative charge control agents. Examples thereof include a high molecular compound having an acid or carboxylic acid group in a side chain, a boron compound, a urea compound, a silicon compound, and calixarene. Examples of the positive charge control agent include a quaternary ammonium salt, a polymer compound having the quaternary ammonium salt in the side chain, a guanidine compound, a nigrosine compound, and an imidazole compound.
[0075]
As a method for incorporating the charge control agent into the toner, there are a method of adding internally to the toner particles and a method of adding it externally. The use amount of these charge control agents is determined by the type of the binder resin, the presence or absence of other additives, the toner manufacturing method including the dispersion method, and is not limited to a specific one. When added internally, it is preferably used in an amount of 0.1 to 10 parts by mass, more preferably 0.1 to 5 parts by mass, based on 100 parts by mass of the binder resin. When added externally, the amount is preferably 0.005 to 1.0 part by mass, more preferably 0.01 to 0.3 part by mass, based on 100 parts by mass of the toner.
[0076]
Improving the internal structure and surface properties of the toner by including a polar resin such as a polyester resin or a polycarbonate resin (hereinafter referred to as “polar resin”) in the polymerizable monomer composition according to the present invention. Can be done. For example, in the production of a toner, when the above-mentioned polar resin is added during the polymerization reaction from the dispersion step to the polymerization step, the addition is performed according to the balance between the polarity of the polymerizable monomer composition that becomes the toner particles and the polarity of the aqueous dispersion medium. It can be controlled such that the polar resin forms a thin layer on the surface of the toner particles or exists with a gradient from the surface of the toner particles toward the center. In particular, in order to positively design the internal structure and surface properties of the toner and to impart preferable characteristics, it is preferable to use a polar resin having an acid value of 1 to 40 mgKOH / g.
[0077]
The amount of the polar resin to be added is preferably 1 to 25 parts by mass, more preferably 2 to 15 parts by mass with respect to 100 parts by mass of the binder resin. If the amount is less than 1 part by mass, the existence state of the polar resin in the toner particles becomes non-uniform, and if it exceeds 25 parts by mass, the thin layer of the polar resin formed on the surface of the toner particles becomes thick. It is difficult to control the content state of the toner constituent material, and the function cannot be sufficiently exhibited.
[0078]
Further, the polar resins as described above are not limited to one kind of polymer, respectively. For example, two or more kinds of reactive polyester resins can be used at the same time, and two or more kinds of vinyl polymers can be used. And completely different kinds of polymers such as non-reactive polyester resin, epoxy resin, polycarbonate resin, polyolefin, polyvinyl acetate, polyvinyl chloride, polyalkyl vinyl ether, polyalkyl vinyl ketone, polystyrene, poly (meth) acrylic ester Various polymers such as melamine formaldehyde resin, polyethylene terephthalate, nylon and polyurethane can be added to the binder resin as required.
[0079]
In the aqueous dispersion medium according to the present invention, known surfactants, organic dispersants, and inorganic dispersants can be used as dispersion stabilizers. Above all, inorganic dispersants are unlikely to generate harmful ultrafine powders, and because of their steric hindrance, have obtained dispersion stability, so that they do not easily lose stability even when the reaction temperature is changed, are easy to wash, and do not adversely affect the toner. Therefore, it can be preferably used. Examples of such inorganic dispersants include polyphosphate metal salts such as calcium phosphate, magnesium phosphate, aluminum phosphate and zinc phosphate, carbonates such as calcium carbonate and magnesium carbonate, calcium metasilicate, calcium sulfate and barium sulfate. Examples thereof include inorganic salts, inorganic oxides such as calcium hydroxide, magnesium hydroxide, aluminum hydroxide, silica, bentonite, and alumina.
[0080]
When these inorganic dispersants are used, they may be used as they are, but in order to obtain finer particles, the inorganic dispersant particles can be generated and used in an aqueous medium. For example, in the case of calcium phosphate, a water-insoluble calcium phosphate can be produced by mixing an aqueous solution of sodium phosphate and an aqueous solution of calcium chloride under high-speed stirring, and more uniform and fine dispersion can be achieved. At this time, a water-soluble sodium chloride salt is simultaneously produced as a by-product, but if the water-soluble salt is present in the aqueous medium, dissolution of the polymerizable monomer in water is suppressed, and the ultrafine toner due to emulsion polymerization is formed. This is more convenient because it hardly occurs. The inorganic dispersant can be almost completely removed by dissolving with an acid or alkali after completion of the polymerization.
[0081]
It is preferable that these inorganic dispersants are used alone in an amount of 0.2 to 20 parts by mass with respect to 100 parts by mass of the polymerizable monomer. Since it is somewhat weak, a surfactant of 0.001 to 0.1 parts by mass may be used in combination.
[0082]
Examples of the surfactant include sodium dodecylbenzene sulfate, sodium tetradecyl sulfate, sodium pentadecyl sulfate, sodium octyl sulfate, sodium oleate, sodium laurate, sodium stearate, potassium stearate and the like.
[0083]
After completion of the polymerization step, the polymer particles are filtered, washed and dried by a known method, and if necessary, an inorganic fine powder is mixed and adhered to the surface, whereby a dry toner can be obtained. It is also a desirable embodiment of the present invention to include a classification step in the toner manufacturing process to remove coarse particles and fine powder of the toner.
[0084]
(Dry toner)
The dry toner of the present invention is obtained by suspending at least a polymerizable monomer composition containing a polymerizable monomer and a colorant in the form of oil droplets, and then converting the polymerizable monomer composition to a non-aromatic liquid. A dry toner obtained by polymerizing with a redox polymerization initiator comprising a system organic peroxide and a non-aromatic reducing agent, wherein the toner has a circle-equivalent number average diameter in a number-based particle size frequency distribution. The average circularity in the circularity frequency distribution is 0.965 to 0.995, and the amount of the colorant in the toner is 635 mesh sieve (opening diameter = 20 μm). ), Wherein the relative content of the colorant in the coarse particles of the toner not passing through is in the range of 0.90 to 1.10.
[0085]
The present inventors have examined the effects of the particle size frequency distribution and the circularity frequency distribution on the developing property and the transfer property of the toner particles, and have found that they have a very deep relationship.
[0086]
That is, by reducing the average particle diameter equivalent to a circle in the particle size frequency distribution based on the number of toners to 2 to 6 μm, preferably 3 to 5 μm, the outline portion of an image, particularly a character image or a line pattern, is developed. Good reproducibility is obtained. However, in general, when the particle size of the toner particles is reduced, the existence ratio of the toner having a small particle size necessarily increases, so that it becomes difficult to uniformly charge the toner, and not only image fog occurs but also the electrostatic latent image carrying Adhesion to the body surface is increased, resulting in an increase in transfer residual toner.
[0087]
However, the toner of the present invention is developed by setting the average circularity of the circularity frequency distribution to 0.965 to 0.995, preferably 0.970 to 0.995, and particularly preferably 0.980 to 0.995. The stability to the environmental change of transferability and transferability, and the durability are further improved.
[0088]
The reason is that when forming a thin layer of toner on the toner carrier in the developing step, the present inventors maintain a sufficient amount of toner coating even if the regulating force of the toner layer thickness regulating member is made stronger than usual. It is considered that the charge amount of the toner on the toner carrier can be made higher than usual without damaging the toner carrier.
[0089]
Further, the transferability of a toner having a small particle diameter, which has been difficult in the related art, is greatly improved, and the developing ability for a low-potential latent image is significantly improved. It is particularly effective when developing a digital minute spot latent image. When the average circularity is less than 0.965, not only the transferability deteriorates, but also the developability decreases. On the other hand, when the average circularity exceeds 0.995, the surface of the toner deteriorates remarkably, causing problems in durability and the like.
[0090]
The circle equivalent diameter, circularity, and frequency distribution of the toner in the present invention are used as a simple method for quantitatively expressing the shape of the toner particles. In the present invention, the flow type particle image measuring device FPIA- The measurement was performed using Model 1000 (manufactured by Toa Medical Electronics Co., Ltd.), and calculated using the following equation.
[0091]
(Equation 1)

[0092]
Here, the “particle projection area” is the area of the binarized toner particle image, and the “perimeter of the particle projection image” is the length of the contour obtained by connecting the edge points of the toner particle image. Is defined.
[0093]
The circularity in the present invention is an index indicating the degree of unevenness of the toner particles, and is 1.000 when the toner particles are perfectly spherical, and the circularity becomes smaller as the surface shape becomes more complicated.
[0094]
In the present invention, the circle-equivalent number average diameter and the particle diameter standard deviation SDd, which mean the average value of the particle number frequency distribution based on the number of toners, are represented by di, the particle diameter (center value) at the dividing point i of the particle distribution, and Is calculated from the following equation.
[0095]
(Equation 2)

[0096]
Further, the average circularity and the circularity standard deviation SDc, which mean the average value of the circularity frequency distribution, are given by the following equation, where the circularity (center value) at the interrogation point i of the particle size distribution is ci and the frequency is fci. Is calculated.
[0097]
(Equation 3)

[0098]
As a specific measuring method, 10 ml of ion-exchanged water from which impurity solids and the like have been removed in advance is prepared in a container, and a surfactant, preferably an alkylbenzene sulfonate, is added as a dispersant therein, and then further measured As a means for adding 0.02 g of a sample and uniformly dispersing the same, a means of dispersing an ultrasonic disperser UH-50 type (manufactured by SMT Corporation) using a titanium alloy chip of 5 mmφ as a vibrator for 5 minutes is used. Using a dispersion treatment, a dispersion for measurement is prepared. At this time, the dispersion is appropriately cooled so that the temperature of the dispersion does not become 40 ° C. or more.
[0099]
To measure the shape of the toner particles, the flow particle image measuring apparatus was used, and the concentration of the dispersion was readjusted so that the concentration of the toner particles at the time of measurement was 3000 to 10,000 particles / μl. Measure above. After the measurement, using this data, the equivalent circle diameter and circularity frequency distribution of the toner are obtained.
[0100]
The dry toner of the present invention is produced by suspending a polymerizable monomer composition and then polymerizing the suspension with a redox polymerization initiator having a non-aromatic organic peroxide and a non-aromatic reducing agent. However, depending on the timing of redox formation, it is difficult to control the shape and internal structure of the obtained toner particles. Further, in a remarkable case, since a part of the polymerizable monomer is vaporized or a wax component oozes out of the oil droplet, a toner having a colorant or a wax component exceeding 20 μm in which the colorant and the wax component are segregated in the toner particles is used. This produces coarse grains. Such coarse toner particles often have a flattened shape, and cannot be easily removed by ordinary classification or sieving, and cause serious problems in toner performance and matching with an image forming apparatus. . However, the dry toner of the present invention has a colorant content (Pb) in the toner coarse particles which does not pass through a 635-mesh sieve (opening diameter = 20 μm) existing in the toner with respect to the colorant content (Pa) in the toner. ) Can be prevented beforehand by setting the relative ratio (Pb / Pa) to 0.90 to 1.10.
[0101]
Further, when a wax component is contained in the toner, the coarse particles in the toner that do not pass through a 635 mesh sieve (opening diameter = 20 μm) existing in the toner with respect to the wax component content (Wa) in the toner. The relative ratio of the wax component content (Wb) (Wb / Wa, hereinafter referred to as “relative ratio of toner coarse wax component”) is 0.85 to 1.20, and more preferably 0.90 to 1.10. Thereby, a more preferable state is obtained.
[0102]
In the present invention, a known analysis method such as fluorescent X-ray analysis or plasma emission analysis (ICP) can be used for quantifying the colorant in the toner. As an example of the analysis method, there is a method using an X-ray fluorescence analyzer “SYSTEM 3080” (manufactured by Rigaku Denki Kogyo Co., Ltd.) and quantifying according to the general rules of X-ray fluorescence analysis described in “JIS K0119”. No. The amount of carbon black can be determined from the rate of mass reduction during heating.
[0103]
On the other hand, the amount of the wax component in the toner may be determined by extracting the wax component from the toner and directly measuring the mass thereof, or using the DSC curve obtained at the time of measuring the melting point of the wax component as described above. The content can also be determined from the heat of dissolution.
[0104]
The addition of an inorganic fine powder to the toner according to the present invention is a preferred embodiment for improving developability, transferability, charging stability, fluidity, and durability. As the inorganic fine powder, known ones can be used, but it is particularly preferable to be selected from silica, alumina, titania, or a double oxide thereof, and it is more preferable to use silica. For example, as the silica, both a so-called dry method produced by vapor phase oxidation of a silicon halide and an alkoxide, or a dry silica called a fumed silica, and a so-called wet silica produced from an alkoxide, water glass, or the like are used. Although it is possible, there are few silanol groups on the surface and inside of the silica fine powder,₂O or SO₃ ^2-Dry silica with a small production residue such as is preferred. In the case of fumed silica, a composite fine powder of silica and another metal oxide can be obtained by using another metal halide such as aluminum chloride and titanium chloride together with a silicon halide in the manufacturing process. Yes, they are included.
[0105]
The inorganic fine powder used in the present invention has a specific surface area of 30 m by nitrogen adsorption measured by the BET method.²/ G or more, especially 50 to 400 m²/ G gives good results, and is used in an amount of 0.3 to 8 parts by mass, preferably 0.5 to 5 parts by mass, per 100 parts by mass of the toner.
[0106]
Furthermore, the specific surface area is 50-150m²/ G inorganic fine powder and 170m²/ G / g or more in the above range at a mass ratio of 5:95 to 50:50, whereby an appropriate space and fluidity are provided between the toner particles, so that the charging behavior of the toner is good. It becomes.
[0107]
Specific surface area of inorganic fine powder is 30m²If it is less than / g, it is difficult to impart appropriate fluidity to the toner, and the effect of preventing the toner carrier from being contaminated by the colorant is reduced. On the other hand, the specific surface area is 400m²/ G, the inorganic fine powder is embedded in the surface of the toner particles during continuous printing of a large number of sheets, so that the fluidity of the toner may decrease.
[0108]
When the amount of the inorganic fine powder is less than 0.3 parts by mass, the effect of the addition is not exhibited. When the amount exceeds 8 parts by mass, not only a problem occurs in the chargeability and the fixability of the toner, but also the toner is liberated. The matching with the image forming apparatus is significantly deteriorated by the inorganic fine powder.
[0109]
Further, the inorganic fine powder used in the present invention may contain, if necessary, a silicone varnish, various modified silicone varnishes, silicone oil, various modified silicone oils, a silane coupling agent, a functional group for the purpose of hydrophobization, charge control, and the like. It is possible and preferable to use a silane coupling agent, a treating agent such as an organosilicon compound or an organotitanium compound, or a combination of various treating agents.
[0110]
To measure the specific surface area, nitrogen gas was adsorbed on the sample surface using a specific surface area measuring apparatus “Autosorb 1” (manufactured by Yuasa Ionics), and the specific surface area was calculated by the BET multipoint method.
[0111]
In particular, the inorganic fine powder used in the toner according to the present invention is preferably treated with at least silicone oil in order to maintain a high charge amount and achieve a high transfer rate and good matching with an image forming apparatus.
[0112]
The dry toner of the present invention may further contain other additives within a range that does not substantially adversely affect the powder, such as a lubricant powder such as a polyfluoroethylene powder, a zinc stearate powder and a polyvinylidene fluoride powder; a cerium oxide powder and a silicon carbide powder. , A polishing agent such as strontium titanate powder; a fluidity imparting agent such as titanium oxide powder and aluminum oxide powder; a caking inhibitor; or a conductivity imparting agent such as carbon black powder, zinc oxide powder and tin oxide powder; In addition, organic and inorganic fine particles of opposite polarity can be used in a small amount as a developing property improver.
[0113]
The dry toner according to the present invention can be used as it is as a one-component developer or as a two-component developer by mixing with a carrier.
[0114]
When used as a two-component developer, for example, the magnetic carrier mixed with the toner is composed of an element selected from iron, copper, zinc, nickel, cobalt, manganese, chromium and the like, alone or in a composite ferrite state. The shape of the magnetic carrier used at this time includes a spherical shape, a flat shape, an irregular shape, and the like. In addition, a shape in which the fine structure (for example, surface unevenness) of the surface state of the magnetic carrier is appropriately controlled may be used. I can do it. Also, a resin-coated carrier whose surface is coated with a resin can be suitably used. The average particle size of the carrier used is preferably 10 to 100 μm, more preferably 20 to 50 μm. When the carrier and the toner are mixed to prepare a two-component developer, the toner concentration in the developer is preferably 2 to 15% by mass.
[0115]
(Image forming method)
Next, as an example of the image forming method according to the present invention, a multi-color image is formed by forming toner images of different colors in a plurality of image forming units and sequentially superposing these on the same transfer material. An image forming method for forming an image will be described with reference to the schematic explanatory view of the full-color image forming apparatus shown in FIG.
[0116]
In the full-color image forming apparatus main body, a first image forming unit Pa, a second image forming unit Pb, a third image forming apparatus unit Pc, and a fourth image forming apparatus unit Pd are provided side by side. After a toner image of a different color is developed in the image forming apparatus unit, the toner image is transferred onto a transfer material conveyed by a transfer material conveyance belt, and further heated and pressed to obtain a full-color image.
[0117]
The configuration of each image forming unit provided in the image forming apparatus will be described by taking the first image forming unit Pa as an example.
[0118]
The first image forming unit Pa includes a photosensitive drum 19a having a diameter of 24 mm as an electrostatic latent image carrier, and the photosensitive drum 19a rotates in the direction of the arrow.
[0119]
As a charging unit, a primary charging roller 16a having a diameter of 12 mm is disposed so as to be in contact with the surface of the photosensitive drum 19a. An electrostatic latent image is formed on the photosensitive drum 19a, which is uniformly primary charged by the primary charging roller 16a, by a laser beam 14a emitted from the exposure device 13a in accordance with an image signal.
[0120]
The developing device 17a has developing means for developing the electrostatic latent image formed on the surface of the photosensitive drum 19a to form a toner image, and includes a first color toner and a thin layer of the toner. Is disposed so as to be in contact with the photosensitive drum 19a via a thin layer of toner, and the first color toner image is developed.
[0121]
The first color toner image developed on the photosensitive drum 19a is transferred to the surface of the transfer material S conveyed by the belt-shaped transfer material carrier 20 by a transfer blade 11a as a transfer unit. The transfer blade 11a comes into contact with the back surface of the transfer material carrier 210 and can apply a transfer bias by the bias applying unit 12a.
[0122]
The surface of the photosensitive drum 19a after the transfer is removed from the transfer residual toner by the cleaning device 18a, and is used for the subsequent formation of the next electrostatic latent image.
[0123]
The image forming apparatus according to the present invention has the same configuration as the first image forming unit Pa, and has a second image forming apparatus unit Pb and a third image forming apparatus unit Pc having different colors of toner held in the developing device. , And a fourth image forming apparatus unit Pd. For example, the first image forming apparatus unit Pa has yellow toner, the second image forming apparatus unit Pb has magenta toner, the third image forming apparatus unit Pc has cyan toner, and the fourth image forming apparatus unit Pd. Each of the image forming apparatus units is sequentially transferred a toner image of each color onto a transfer material at a transfer unit of each image forming apparatus unit. At this time, the transfer material is moved while adjusting the registration during this process, and the toners of the respective colors are superimposed on the same transfer material. When the transfer is completed, the transfer material S is separated from the transfer material carrier 20 by the separation charger 21. The sheet is conveyed to the fixing device 23 by conveying means such as a conveying belt, and a desired full-color image is obtained by a single fixing.
[0124]
In FIG. 1, the transfer material carrier 20 is an endless belt-shaped member, and this belt member is moved in the direction of an arrow by a driving roller 80 as the image formation proceeds. A belt driven roller 81, a belt neutralization device 82, and a belt cleaning device 83 are provided around the transfer material carrier 20, and a pair of registration rollers 24 carry the transfer material S in the transfer material holder. It is provided for transport to the body.
[0125]
In the image forming apparatus as described above, as the transfer unit, a roller-shaped transfer roller or a non-contact charging unit such as a corona charger is used instead of the transfer blade abutting on the back side of the transfer material carrier. It is also possible.
[0126]
Further, as a transporting means for transporting the transfer material, a transport belt using a mesh of tetron fiber or polyethylene terephthalate-based resin, polyimide-based resin, and urethane-based resin from the viewpoint of easiness of processing and durability. Although a transport belt using a dielectric sheet is used, a configuration having a drum type transport unit may be used.
[0127]
In the image forming apparatus as described above, since the toner images of each color are sequentially transferred onto the same transfer material in the transfer section of each image forming apparatus unit, the previously transferred toner image carries the toner image to be transferred later. In contact with the photosensitive drum. At this time, if there is an unstable charged state among the toner particles forming the toner image on the transfer material to which the transfer has been completed, the so-called toner is returned to the photosensitive drum where the transfer is subsequently performed. A "retransfer phenomenon" occurs, and this is a starting point that causes deterioration in image quality. However, in the present invention, by specifying the type and content of the colorant in each toner particle of the chromatic color developer, the above-described image defects can be prevented.
[0128]
【Example】
Hereinafter, the present invention will be described with reference to specific production examples and examples, but the present invention is not limited thereto.
[0129]
<Production Example 1 of Toner>
Dispersion process
A mixture comprising the following components was dispersed for 3 hours using an attritor (manufactured by Mitsui Kinzoku Co., Ltd.).
・ Styrene 83 parts by mass
・ 17 parts by mass of n-butyl acrylate
・ Divinylbenzene 0.1 parts by mass
-5 parts by mass of colorant (CI Pigment Blue 15: 3)
・ 5 parts by mass of polyester resin (peak molecular weight = 5000)
.2 parts by mass of a polymer having a sulfonic acid group
[Styrene polymer containing 5.8% by mass of 2-acrylamide-2-methylpropanesulfonic acid (sulfonic acid group-containing monomer represented by the above formula (2)], Tg = 60 ° C.]
[0130]
The obtained dispersion was heated to 60 ° C., and 10 parts by mass of an ester wax (melting point = 70 ° C.) was mixed and dissolved therein as a wax component, and further, t-butyl peroxyisopropyl was used as a non-aromatic organic peroxide. 5 parts by mass of monocarbonate (10-hour half-life temperature 98.7 ° C.) was added to prepare a polymerizable monomer composition.
[0131]
Granulation process
In a reaction vessel equipped with a high-speed stirrer CLEARMIX (manufactured by M Technique Co., Ltd.), 700 parts by mass of ion-exchanged water and 0.1 mol / L-Na₃PO₄800 parts by mass of the aqueous solution was charged, the rotation speed of the high-speed stirring device was set to 15,000 rpm, and the mixture was heated to 60 ° C. Here, 1.0 mol / L-CaCl₂70 parts by mass of an aqueous solution is added, and a fine hardly water-soluble dispersant Ca is added.₃(PO₄)₂The aqueous dispersion medium containing was prepared.
[0132]
Next, the polymerizable monomer composition was charged into the aqueous medium, and N 2 at an internal temperature of 60 ° C.₂Under an atmosphere, the mixture was stirred for 10 minutes while maintaining the rotation speed of the high-speed stirring device at 15000 rpm, and the polymerizable monomer composition was suspended in an aqueous medium in the form of oil droplets and granulated.
[0133]
Polymerization process
Thereafter, the stirring device was replaced with one equipped with a paddle stirring blade, and the temperature was maintained at 60 ° C. while stirring at a rotation speed of 80 rpm. An aqueous solution in which 2.5 parts by mass of sodium ascorbate as a non-aromatic reducing agent (44 mol% based on the amount of the organic peroxide added) was added in advance, and the polymerization reaction was started.
[0134]
When the polymerization conversion of the polymerizable monomer exceeds 30%, an aqueous solution in which 1.25 parts by mass of sodium ascorbate is dissolved is additionally added (total of 3.75 parts by mass, based on the amount of organic peroxide added). 67 mol%), and the polymerization temperature was raised to 80 ° C. (> melting point of ester wax = 70 ° C.).
[0135]
Further, when the polymerization conversion rate of the polymerizable monomer exceeds 60%, an aqueous solution in which 1.25 parts by mass of sodium ascorbate is dissolved is again added again (total 5 parts by mass, based on the amount of organic peroxide added). ), And the polymerization step was completed when the polymerization conversion reached almost 100%. The time required for the polymerization reaction was 6 hours.
[0136]
After completion of the polymerization, volatile components remaining in the polymer particles were distilled off under heating and reduced pressure, and then, after cooling, dilute hydrochloric acid was added to dissolve the poorly water-soluble dispersant. Further, after repeating water washing several times, a drying treatment is carried out, and polymer particles (A) having a circle-equivalent number average diameter (hereinafter referred to as “average particle diameter”) of 4.5 μm in a number-based particle size frequency distribution. Got.
[0137]
100 parts by mass of the polymer particles (A), 1 part by mass of silicone oil-treated hydrophobic silica fine powder and 0.5 parts by mass of silicone oil-treated titanium oxide fine powder were dry-mixed with a Henschel mixer (manufactured by Mitsui Kinzoku Co., Ltd.). Cyan toner (A) having an average particle size of 4.5 μm and an average circularity in the circularity frequency distribution (hereinafter, referred to as “average circularity”) of 0.981 was used. The amount of the styrene monomer remaining in the cyan toner (A) was extremely small, and was 50 ppm or less.
[0138]
A toner that does not pass through a 635-mesh sieve (manufactured by Tokyo Screen Co., Ltd., opening diameter = 20 μm, “JIS Z 8801”) that exists in the cyan toner (A) with respect to the colorant content in the cyan toner (A). The relative ratio of the colorant content in the coarse particles was 1.00.
[0139]
Further, the relative ratio of the wax component content in the coarse toner particles not passing through the 635-mesh sieve present in the cyan toner (A) to the wax component content in the cyan toner (A) was 1.00. Was.
[0140]
Further, the production of the polymer particles (A) was repeated 5 times continuously. The average value of the average particle diameter of the cyan toner obtained for each production is 4.5 μm (standard deviation = 0.02), the average value of the average circularity is 0.980 (standard deviation = 0.002), and the toner The average value of the relative ratio of the coarse powder colorant is 1.00 (standard deviation = 0.49), and the average value of the relative ratio of the toner coarse powder wax component is 1.00 (standard deviation = 0.50), which is very preferable. It showed continuous productivity.
[0141]
When the inner wall of the reaction vessel and the paddle stirring blade were observed after the production of the polymer particles, the degree of such dirt was small enough to remove most of the dirt by the water flow.
[0142]
<Example 2 of toner production>
In the granulation step, the poorly water-soluble dispersant Ca₃(PO₄)₂Except that the polymerizable monomer composition was finely suspended in oil droplets and granulated by changing the amount of Polymer particles (B) having an average particle size of 3.2 μm were produced in the same manner as in Example 1, and a cyan toner (B) was prepared.
[0143]
The average particle diameter of the obtained cyan toner (B) was 3.2 μm, the average circularity was 0.982, the relative ratio of the toner coarse colorant was 1.00, and the relative ratio of the toner coarse powder wax component was 0.99. there were. The amount of the styrene monomer remaining in the cyan toner (B) was 50 ppm or less.
[0144]
At this time, the time required for the polymerization reaction was 4 hours, which was reduced to 65% as compared with the time when the polymer particles (A) were produced in Production Example 1 of the toner. The degree of dirt was in the same level. Although fine particles of toner were produced using the same equipment as toner (A), a significant improvement in productivity was observed.
[0145]
<Example 3 of toner production>
In the polymerization step, an aqueous solution in which 2.5 parts by mass of sodium ascorbate (44 mol% based on the added amount of organic peroxide) is added to start the polymerization reaction, and then the polymerization conversion of the polymerizable monomer is started. The toner was manufactured in the same manner as in Example 1 except that an aqueous solution in which 2.5 parts by mass of sodium ascorbate was dissolved was continuously added little by little using a metering pump from the time when the ratio exceeded 25%. After obtaining polymer particles (C), a black toner (C) was prepared.
[0146]
The average particle size of the obtained black toner (C) was 4.6 μm, the average circularity was 0.978, the relative ratio of the toner coarse-grain colorant was 1.00, and the relative ratio of the toner coarse-grain wax component was 0.99. there were. The amount of the styrene monomer remaining in the black toner (C) was 50 ppm or less.
[0147]
<Production Example 4 of Toner>
In the granulation step, the poorly water-soluble dispersant Ca₃(PO₄)₂After adding an aqueous solution in which 1 part by mass of sodium ascorbate (18 mol% based on the amount of the organic peroxide added) is dissolved in the aqueous dispersion medium after the production of the above, the polymerizable monomer composition is granulated, In the polymerization step, when the polymerization conversion of the polymerizable monomer exceeds 30%, an aqueous solution in which 2 parts by mass of sodium ascorbate is dissolved is additionally added (total 3 parts by mass, based on the amount of organic peroxide added). (53 mol%), the polymerization temperature was raised to 80 ° C., and when the polymerization conversion of the polymerizable monomer exceeded 60%, an aqueous solution in which 2 parts by mass of sodium ascorbate was dissolved was again added ( Polymer particles (D) were obtained in the same manner as in Production Example 1 of the toner, except that the total amount was 5 parts by mass, and 100 mol% based on the added amount of the organic peroxide. Was prepared.
[0148]
The average particle size of the obtained cyan toner (D) was 4.9 μm, the average circularity was 0.972, the relative ratio of the toner coarse-grain colorant was 0.98, and the relative ratio of the toner coarse-grain wax component was 0.98. there were. The amount of the styrene monomer remaining in the cyan toner (D) was 50 ppm or less.
[0149]
<Production Example 5 of Toner>
In the granulation step, the polymerizable monomer composition is charged into the aqueous medium, the rotation speed of the high-speed stirrer is maintained at 15,000 rpm, and after stirring for 2 minutes, 5 parts by mass of t-butylperoxyisopropyl monocarbonate is added. Except for the following, polymer particles (E) were obtained in the same manner as in Production Example 1 of the toner, and then a cyan toner (E) was prepared.
[0150]
The resulting cyan toner (E) had an average particle size of 4.7 μm, an average circularity of 0.970, a toner coarse-grain colorant content ratio of 0.97, and a toner coarse-grain wax component relative ratio of 0.96. there were. The amount of the styrene monomer remaining in the cyan toner (E) was 50 ppm or less.
[0151]
<Production Example 6 of Toner>
A mixture comprising the following components was dispersed for 3 hours using an attritor (manufactured by Mitsui Kinzoku Co., Ltd.).
・ Styrene 78 parts by mass
・ 22 parts by mass of 2-ethylhexyl acrylate
・ Divinylbenzene 0.1 parts by mass
・ Coloring agent (carbon black, particle size = 55 nm) 6 parts by mass
-5 parts by mass of polyester resin (peak molecular weight = 6000)
.2 parts by mass of a polymer having a sulfonic acid group
[Styrene-2-ethylhexyl acrylate copolymer containing 7.9% by mass of 2-acrylamido-2-methylphenylethanesulfonic acid (sulfonic acid group-containing monomer represented by the above formula (3)], Tg = 65 ° C.]
[0152]
The obtained dispersion was heated to 60 ° C., and 5 parts by mass of an acid-modified polyethylene wax (melting point = 115 ° C.) was mixed and dissolved therein as a wax component. After adding 5 parts by mass of oxyisopropyl monocarbonate to prepare a polymerizable monomer composition, 5 parts by mass of erythorbic acid (solubility in water = 53) was replaced with sodium ascorbate as a non-aromatic reducing agent. A polymer toner (F) was obtained in the same manner as in Production Example 1 of the toner except that the toner was used in a simple addition method, and then a black toner (F) was prepared.
[0153]
The average particle size of the obtained black toner (F) was 4.3 μm, the average circularity was 0.977, the relative ratio of the toner coarse-grain colorant was 1.00, and the relative ratio of the toner coarse-grain wax component was 1.00. there were. The amount of the styrene monomer remaining in the black toner (F) was 50 ppm or less.
[0154]
<Production Example 7 of Toner>
Except for adding 1 part by mass of Cu phthalocyanine (CI Pigment Blue 15: 3) to the polymerizable monomer composition, polymer particles (G) were produced in the same manner as in Production Example 6 of the toner. After that, a black toner (G) was prepared.
[0155]
The average particle size of the obtained toner (G) was 4.1 μm, the average circularity was 0.985, the relative ratio of the toner coarse colorant was 1.00, and the relative ratio of the wax component was 1.00. The amount of the styrene monomer remaining in the black toner (G) was 50 ppm or less.
[0156]
At this time, the time required for the polymerization reaction was reduced to 80% as compared with the time when the polymer particles (F) were produced, and the degree of dirt in the reaction vessel and the like was almost the same. Therefore, improvement in productivity was recognized.
[0157]
<Production Example 8 of Toner>
5 parts by mass of “CI Pigment Red 238” as a coloring agent, 5 parts by mass of p-menthane hydroperoxide (10-hour half-life temperature = 128.0 ° C.) as a non-aromatic organic peroxide, and non-aromatic A magenta toner (H) was prepared after obtaining polymer particles (H) in the same manner as in Production Example 1 of the toner except that erythorbic acid was used as the group-based reducing agent.
[0158]
The average particle size of the obtained magenta toner (H) was 4.4 μm, the average circularity was 0.980, the relative ratio of the toner coarse colorant was 1.00, and the relative ratio of the toner coarse particle wax component was 1.00. there were. The amount of the styrene monomer remaining in the magenta toner (H) was 50 ppm or less.
[0159]
<Production Example 9 of Toner>
6 parts by mass of “CI Pigment Yellow 155” as a coloring agent, and 5 parts by mass of t-hexylperoxyisopropyl monocarbonate (10-hour half-life temperature = 95.0 ° C.) as a non-aromatic organic peroxide; After obtaining polymer particles (I) in the same manner as in Production Example 1 of the toner except that 5 parts by mass of ascorbic acid (solubility in water = 33) is used as the non-aromatic reducing agent, A yellow toner (I) was prepared.
[0160]
The average particle size of the obtained yellow toner (I) was 4.2 μm, the average circularity was 0.977, the relative ratio of the toner coarse-grain colorant was 1.00, and the relative ratio of the toner coarse-grain wax component was 1.00. there were. The residual styrene monomer amount was 50 ppm or less.
[0161]
<Example 10 of toner production>
Except that 5 parts by mass of t-butylperoxyisobutyrate (10-hour half-life temperature = 77.3 ° C.) is used as the non-aromatic organic peroxide, the same as in Production Example 9 of the toner, except that 5 parts by mass is used. After obtaining the polymer particles (J), a yellow toner (J) was prepared.
[0162]
The resulting yellow toner (J) had an average particle size of 4.3 μm, an average circularity of 0.971, a relative ratio of toner coarse-grain colorant of 1.00, and a relative ratio of toner coarse-grain wax component of 1.00. there were. The residual styrene monomer amount was 50 ppm or less.
[0163]
<Comparative Production Example 1 of Toner>
In the polymerization step, an aqueous solution in which 5.0 parts by mass of sodium ascorbate (100 mol% based on the amount of the organic peroxide added) was dissolved was added all at once, and the remarkable heat generated immediately after the addition was used to make the polymerizable polymer. Except for increasing the polymerization temperature to 80 ° C. before the polymerization addition rate of the monomer reaches 30%, a comparative weight having an average particle diameter of 4.7 μm was prepared in the same manner as in Production Example 1 of the toner. After obtaining the coalesced particles (a), a comparative cyan toner (a) was prepared.
[0164]
The average particle diameter of the obtained comparative cyan toner (a) is 4.7 μm, the average circularity is 0.962, the relative ratio of the toner coarse-grain colorant is 0.87, and the relative ratio of the toner coarse-grain wax component is 0.1. 80.
[0165]
<Comparative Production Example 2 of Toner>
In the polymerization step, a toner was manufactured in the same manner as in Example 1 of the toner production except that an aqueous solution in which 5.0 parts by mass of sodium ascorbate (100 mol% based on the amount of the organic peroxide added) was dissolved was added all at once. After obtaining the comparative polymer particles (b), a comparative black toner (b) was prepared.
[0166]
The average particle size of the obtained comparative black toner (b) is 5.8 μm, the average circularity is 0.964, the relative ratio of the toner coarse colorant is 0.88, and the relative ratio of the toner coarse particle wax component is 1. It was 12.
[0167]
<Comparative Production Example 3 of Toner>
In the dispersion step, 5 parts by mass of 2,2′-azobis (2,4-dimethylvaleronitrile), which is an azo polymerization initiator, is used instead of the non-aromatic organic peroxide to prepare a polymerizable monomer composition. A comparative magenta toner (c) was prepared after obtaining comparative polymer particles (c) having an average particle diameter of 4.2 μm in the same manner as in Production Example 8 of the toner, except that it was occasionally added.
[0168]
The average particle size of the obtained magenta toner for comparison (c) was 4.2 μm, the average circularity was 0.972, the relative ratio of the toner coarse colorant was 0.88, and the relative ratio of the toner coarse particle wax component was 1. It was 12.
[0169]
On the other hand, by using the azo-based polymerization initiator as the polymerization initiator, N₂Due to the generation of gas, foaming occurred on the surface of the aqueous dispersion medium during the polymerization step, and poor stirring and coalescence due to floating of the polymer particles were observed. In addition, when the inner wall of the reaction vessel and the paddle stirring blade were observed, dirt that was difficult to wash off due to the flow of water was attached. In particular, the upper portion of the reaction vessel was significantly contaminated.
[0170]
<Comparative Production Example 4 of Toner>
In the granulation step, the poorly water-soluble dispersant Ca₃(PO₄)₂Except that the polymerizable monomer composition was finely suspended in oil droplets by changing the amount of In the same manner as in Production Example 3, comparative polymer particles (d) having an average particle size of 2.9 μm were produced, and comparative magenta toner (d) was prepared.
[0171]
The average particle size of the obtained comparative magenta toner (d) is 2.7 μm, the average circularity is 0.974, the relative ratio of the toner coarse colorant is 0.89, and the relative ratio of the toner coarse particle wax component is 1. 10%.
[0172]
At this time, as compared with the case where the comparative polymer particles (c) were produced, although the fine particle toner could be produced, the time required for the polymerization reaction was about the same, and the poorly water-soluble dispersant Ca was used.₃(PO₄)₂In order to change the amount of slag, the number of revolutions of the high-speed stirrer, and the stirring time, it was necessary to increase raw materials and power consumption.
[0173]
Further, after the production of the comparative polymer particles (d) was repeated five times in a row, the inner wall of the reaction vessel and the paddle stirring blade were observed. The upper part of the reaction vessel was extremely contaminated, requiring maintenance such as cleaning, and reduced productivity.
[0174]
<Comparative Production Example 5 of Toner>
Except for adding 5 parts by mass of benzoyl peroxide, which is an aromatic organic peroxide, at the time of preparing the polymerizable monomer composition in the dispersing step, in place of the redox polymerization initiator, as the polymerization initiator. A comparative yellow toner (e) was prepared after obtaining comparative polymer particles (e) having an average particle diameter of 4.1 μm in the same manner as in Production Example 9 of the toner.
[0175]
The average particle size of the obtained comparative yellow toner (e) is 4.7 μm, the average circularity is 0.963, the relative ratio of the toner coarse-grain colorant is 0.88, and the relative ratio of the toner coarse-grain wax component is 1. It was 15.
[0176]
<Comparative Production Example 6 of Toner>
A mixture comprising the following components was dispersed for 3 hours using an attritor (manufactured by Mitsui Kinzoku Co., Ltd.) to prepare a polymerizable monomer composition.
・ Styrene 70 parts by mass
・ N-butyl methacrylate 30 parts by mass
・ 7 parts by mass of colorant (carbon black, particle size = 55 nm)
・ 2 parts by mass of Cr-based dye (trade name: TRH, manufactured by Hodogaya Chemical Co., Ltd.)
・ 2 parts by mass of low molecular weight polypropylene (melting point = 120 ° C)
・ 6.8 parts by mass of t-butyl peroxyisobutyrate
(10 hour half-life temperature = 77.3 ° C)
[0177]
Next, in the granulation step, the poorly water-soluble dispersant Ca₃(PO₄)₂The polymerizable monomer composition was suspended in oil droplets by changing the production amount of the aqueous dispersion medium, the pH of the aqueous dispersion medium, the number of revolutions of the high-speed stirring device, and the stirring time. Except that the polymerization reaction was carried out, comparative polymer particles (f) having an average particle size of 6.5 μm were produced in the same manner as in Production Example 1 of the toner, and a comparative black toner (f) was prepared. did.
[0178]
The average particle size of the obtained comparative black toner (f) is 6.4 μm, the average circularity is 0.960, the relative ratio of the toner coarse-grain colorant is 0.85, and the relative ratio of the toner coarse-grain wax component is 0.1. 82. The amount of the styrene monomer remaining in the toner was 300 ppm.
[0179]
On the other hand, since the polymerization reaction was performed at a temperature close to the boiling point of water, foaming occurred on the surface of the aqueous medium during the polymerization step, and poor stirring and coalescence due to floating of the polymer particles were observed. Further, although the time required for the polymerization reaction was substantially the same as when the polymer particles (A) were produced in Production Example 1 of the toner, the inner wall of the reaction vessel and the paddle stirring blade were observed. Very strong dirt had adhered. In particular, the upper portion of the reaction vessel was significantly contaminated.
[0180]
<Comparative Production Example 7 of Toner>
A mixture comprising the following components was subjected to a dispersion treatment for 3 hours using an attritor (manufactured by Mitsui Kinzoku Co., Ltd.) to prepare a wax component dispersion in which a finely ground wax component was dispersed in styrene.
・ Styrene 36 parts by mass
・ 4 parts by mass of paraffin wax (melting point = 70 ° C)
[0181]
Next, the following components were additionally added to the attritor containing the wax component dispersion, and the dispersion treatment was further performed for 3 hours to prepare a polymerizable monomer composition.
・ Styrene 47 parts by mass
・ 17 parts by mass of 2-butyl acrylate
・ Divinylbenzene 0.3 parts by mass
・ 7 parts by mass of colorant (carbon black, particle size = 55 nm)
・ 1 part by mass of t-dodecyl mercaptan
[0182]
Then, a poorly water-soluble dispersant Ca₃(PO₄)₂And then suspended in an oil droplet form in an aqueous dispersion medium containing tert-butyl peroxy neodecanoate (10-hour half-life temperature = 46.4 ° C.) 7 parts by mass were added, and the mixture was stirred with a high-speed stirring device to perform granulation. Furthermore, the internal temperature was raised to 60 ° C. to start the polymerization reaction, and when the polymerization conversion reached 80%, 5 parts by weight of sodium formaldehyde sulfoxylate and 0.5 parts by weight of sodium ethylenediaminetetraacetate were contained. The comparative polymer particles having an average particle size of 5.0 μm (g) were prepared in the same manner as in Production Example 1 of the toner, except that the aqueous solution was charged, and the polymerization reaction was further performed by continuing heating and stirring for 6 hours. ) Was prepared to prepare a comparative black toner (g).
[0183]
The average particle size of the obtained comparative black toner (g) was 4.8 μm, the average circularity was 0.970, the relative ratio of the toner coarse colorant was 0.83, and the relative ratio of the toner coarse particle wax component was 1. 25. The amount of the styrene monomer remaining in the toner was 500 ppm.
[0184]
On the other hand, the time required for the polymerization reaction was 10 hours, which was about 1.5 times as long as the time when the polymer particles (A) were produced in Production Example 1 of the toner. In addition, since a long time was required for the distillation step for distilling off the polymerizable monomer, very strong dirt adhered to the inner wall of the reaction vessel and the paddle stirring blade. In particular, the upper portion of the reaction vessel was significantly contaminated.
[0185]
Furthermore, a poorly water-soluble dispersant Ca₃(PO₄)₂The comparative polymer particles (h) having an average particle size of 3.5 μm were produced in the same manner as described above except that the production conditions of the aqueous dispersion medium containing The amount of styrene monomer remaining in ()) was 350 ppm, and the time required for polymerization remained at 10 hours, which did not improve the productivity.
[0186]
<Reference toner production example>
Dispersion process
A mixture comprising the following components was heated to 70 ° C., and dispersed for 3 hours using an attritor (manufactured by Mitsui Kinzoku Co., Ltd.) to obtain a polymerizable monomer composition.
・ Styrene 90 parts by mass
・ N-ethylhexyl acrylate 10 parts by mass
・ Ethylene glycol diacrylate 0.05 parts by mass
Colorant (CI Pigment Blue 15: 3) 4 parts by mass
・ 5 parts by mass of polyester resin
(Weight average molecular weight = 10000, acid value = 8 mg KOH / g)
・ Ester wax (melting point = 65 ° C) 10 parts by mass
・ Di-t-butylsalicylic acid metal complex 1 part by mass
[0187]
Granulation process
Preparation of Toner Minute water-insoluble dispersant Ca in the same manner as in Example 1.₃(PO₄)₂Is prepared, dilute hydrochloric acid is added to the aqueous dispersion medium to adjust the pH to 5.5, and then the polymerizable monomer composition is added thereto.₂Under an atmosphere, the mixture was stirred for 10 minutes while maintaining the rotation speed of the high-speed stirring device at 15000 rpm, and the polymerizable monomer composition was suspended in an aqueous medium in the form of oil droplets and granulated. Next, 5 parts by mass of t-butyl hydroperoxide (10-hour half-life temperature 166.5 ° C.) was added, and granulation was further performed for 5 minutes.
[0188]
Polymerization process
Immediately after the completion of granulation, 6 parts by mass of sodium ascorbate (55 mol% based on the added amount of organic peroxide) was added at a time to start the polymerization reaction. Further, the stirring device was changed to one equipped with paddle stirring blades, and the rotation speed was changed to 80 rpm. The temperature was maintained at 70 ° C. while stirring at a rotation speed of. When the polymerization time passed 3 hours, the polymerization temperature was raised to 80 ° C., and heating and stirring were continued for 5 hours, and then the polymerization step was terminated.
[0189]
After completion of the polymerization, reference polymer particles were obtained in the same manner as in Production Example 1 of the toner, and then a reference cyan toner was prepared.
[0190]
The average particle diameter of the obtained reference cyan toner was 6.2 μm, the average circularity was 0.982, the relative content of the colorant in the toner coarse particles was 1.15, and the relative content of the wax component was 1.10. there were.
[0191]
<Example 1>
The full-color image forming apparatus shown in FIG. 1 was used as the image forming apparatus. At this time, the rotational peripheral speed of the surface of the developing roller was set to 140% in the same direction with respect to the rotational driving of the photosensitive drum at the contact portion with the surface of the photosensitive drum.
[0192]
Into the third image forming unit of the image forming apparatus, the cyan toner (A) obtained in the toner production example 1 is charged, and the printout speed is 32 sheets (A4 size) / min in the mono color mode. 10,000 prints were printed out, and the printout images obtained at that time were evaluated.
[0193]
These evaluation results are summarized in Table 1.
[0194]
<Examples 2 to 10>
Cyan toners (B) to (E) are third image forming units, black toners (F) and (G) are fourth image forming units, magenta toner (H) is a second image forming unit, and yellow toner. (I) and (J) were evaluated in the same manner as in Example 1 except that they were used in each of the first image forming units.
These evaluation results are summarized in Table 1.
[0195]
<Comparative Examples 1 to 7>
Comparative cyan toner (a) is the third image forming unit, comparative black toners (b), (f) and (g) are the fourth image forming unit, and comparative magenta toners (c) and (d) are The evaluation was performed in the same manner as in Example 1 except that the second image forming unit and the comparative yellow toner (e) were used by being charged into each of the first image forming units.
[0196]
These evaluation results are summarized in Table 1.
[0197]
<Reference example>
The evaluation was performed in the same manner as in Example 1 except that the reference cyan toner was charged into the third image forming unit and used.
[0198]
These evaluation results are summarized in Table 1.
[0199]
The description of the evaluation items described in the above Examples and Comparative Examples and the evaluation criteria will be described.
[0200]
[Evaluation item]
<1> Image density
Plain paper for ordinary copiers (75 g / m²), A solid black image having a side of 5 mm is printed out, and the relative density of the white background portion having a document density of 0.00 is measured using a “Macbeth reflection densitometer RD918” (manufactured by Macbeth). did.
A: 1.40 or more
B: 1.35 or more and less than 1.40
C: 1.00 or more and less than 1.35
D: less than 1.00
[0201]
<2> Image fog
At the time of forming a solid white image, during the transition from the development process to the transfer process, the toner present on the photoreceptor drum is taped off with a Mylar tape and peeled off, and the reflection density of the product pasted on paper is referred to as "Macbeth reflection densitometer". RD918 ". The evaluation was performed using a numerical value obtained by subtracting the reflection density when the Mylar tape was stuck on paper as it was from the obtained reflection density. The smaller the numerical value, the more the image fog is suppressed.
A: Less than 0.03
B: 0.03 or more and less than 0.07
C: 0.07 or more and less than 1.00
D: 1.00 or more
[0202]
<3> Reproducibility of fine lines
This is an evaluation relating to the image quality and gradation of a graphical image, and the reproducibility of a fine line of a printout image as shown in FIG. 2 was evaluated.
A: Good reproducibility of fine lines
B: Slight variations in the width of fine lines are observed
C: Thin lines and splattering are conspicuous
D: Fine wire tears are observed in some places, resulting in poor reproducibility
[0203]
<4> dot reproducibility
An image of an isolated dot pattern having a small diameter (40 μm) as shown in FIG. 3 in which the electric field is easily closed by the latent image electric field and is difficult to reproduce was printed out, and the dot reproducibility was evaluated.
A: No more than 2 defects in 100
B: 3 to 5 defects in 100
C: 6 to 10 defects in 100
D: 11 or more defects in 100
[0204]
<5> Image blank
An image in which a circular image (diameter: 20 mm) was arranged at five locations was printed out, and the occurrence of white spots of 100 μm or more on the image was measured and evaluated.
A: Not generated
B: Image whiteout is 5 or less
C: 6-10
D: 11 or more
[0205]
<6> Matching with developing roller
After completion of the printout test, the state of the surface of the developing roller and the thin toner layer on the surface of the roller and the effect on the printout image were visually evaluated.
A: The condition of the roller surface and the thin toner layer is good
B: Contamination occurred on the roller surface, but hardly any sticking occurred
C: There is slight adhesion on the roller surface, but there is little effect on the image
D: Adhesion occurs on the roller surface, causing vertical streak-like image defects
[0206]
[Table 1]

[0207]
<Example 11>
In the full-color image forming apparatus shown in FIG. 1, the first image forming unit shown in FIG. 1 has yellow toners (I) and (J), the second image forming unit has magenta toner (H), and the third image. Cyan toners (A) to (E) are sequentially supplied to the forming unit, and black toners (F) and (G) are sequentially supplied to the fourth image forming unit, and 32 sheets (A4 size) / min. A printout test was performed on a graphic image at a printout speed in a full color mode.
[0208]
The obtained graphic images were excellent in color reproducibility and fine line reproducibility in any combination of toners, and free from image white spots, and obtained good results.
[0209]
<Comparative Example 8>
The first image forming unit has a comparative yellow toner (e), the second image forming unit has magenta toners (c) and (d), the third image forming unit has a cyan toner (a), and a third toner. Each of the black toners (b) was sequentially charged into the image forming unit No. 4, and a printout test was performed in the full color mode in the same manner as in Example 11.
[0210]
The obtained full-color image was not only inferior in color reproducibility and reproducibility of fine lines, but also had image defects in the form of vertical stripes due to image white spots and toner adhesion to the developing roller.
[0211]
【The invention's effect】
As described above, according to the present invention, at least a polymerizable monomer composition containing a polymerizable monomer and a colorant is suspended in an oil-based dispersion medium in an aqueous dispersion medium and polymerized. In the method for producing a dry toner produced by producing polymer particles by, as a polymerization initiator, a redox-based polymerization initiator consisting of a non-aromatic organic peroxide and a non-aromatic-based reducing agent is selected, By specifying the timing of adding the non-aromatic reducing agent, it is possible to manufacture a toner which is excellent in matching with an image forming apparatus and can form a high-resolution and high-definition image.
[0212]
Further, the productivity can be increased and a toner having a finer particle diameter can be manufactured without significantly modifying existing equipment.
[Brief description of the drawings]
FIG. 1 is a schematic explanatory view showing a full-color image forming apparatus used in an embodiment of the present invention.
FIG. 2 is an explanatory diagram of a line image for evaluating reproducibility of a fine line and a fixing state.
FIG. 3 is an explanatory diagram of a small-diameter isolated dot pattern for evaluating resolution.
[Explanation of symbols]
16a to 16d charging roller
17a-17d Developing roller
18a-18d cleaning device
19a to 19d photosensitive drum
20 Transfer material transport belt
Pa First color developing unit
Pb Second color developing unit
Pc Third color developing unit
Pd 4th color developing unit
S transfer material

Claims (2)

At least a dispersion step of preparing a polymerizable monomer composition containing a polymerizable monomer and a colorant, and a granulation step of suspending the polymerizable monomer composition in an aqueous dispersion medium in an oil droplet form. And a method for producing a dry toner produced by passing through a polymerization step of producing polymer particles by polymerizing the polymerizable monomer composition using a polymerization initiator,
(1) The polymerization initiator is a redox polymerization initiator having a non-aromatic organic peroxide and a non-aromatic reducing agent,
(2) the non-aromatic organic peroxide is added to the polymerizable monomer composition during the dispersion step and / or the granulation step,
(3) The non-aromatic reducing agent is preliminarily added to the aqueous dispersion medium separately from the non-aromatic organic peroxide during the granulation step and / or the polymerization step, and the polymerization of the polymerizable monomer is further performed. A method for producing a dry toner, which is additionally added after the conversion has progressed by 10% or more. After suspending at least a polymerizable monomer composition containing a polymerizable monomer and a colorant in the form of oil droplets, the polymerizable monomer composition is mixed with a non-aromatic organic peroxide. A dry toner obtained by polymerization with a redox polymerization initiator having an aromatic reducing agent,
The toner has a circle-equivalent number average diameter of 2 to 6 μm in a number-based particle size frequency distribution, an average circularity of 0.965 to 0.995 in a circularity frequency distribution, and a colorant content in the toner ( Pa), the relative ratio (Pb / Pa) of the colorant content (Pb) in the coarse particles of the toner that does not pass through the 635-mesh sieve (opening diameter = 20 μm) present in the toner is 0.90 to 1.10. A dry toner.

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