JP2004117957A - Dry toner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dry toner in which the rising of the toner charge amount is fast even in a high-speed developing system, the degradation of image quality and reduction in image density are not caused even after a long-term use, and which has excellent environmental stability. <P>SOLUTION: The dry toner includes at least a polyester resin-base binder resin and magnetic iron oxide containing Si and at least one element α selected from Mg, Cu, Zn, Ti, and Al, wherein the content of Si is 0.1 to 2.0% by mass with respect to the magnetic iron oxide, a content of the element α is 0.1 to 4.0% by mass, an atomic concentration of the element α on an outermost surface of the magnetic iron oxide is 1.00 to 7.00%, and when the wettability of the toner to a methanol-water mixed solvent is measured with transmittance of light with 780nm wavelength, in the case of 80% transmittance, the concentration of methanol is in a range of 45 to 65% by volume, and in the case of 10% transmittance, the concentration of methanol is in a range of 45 to 65% by volume. <P>COPYRIGHT: (C)2004,JPO

Description

【００８４】
【化２】

【００８５】
また、酸成分としてはカルボン酸が好ましくは例示することができ、二価のカルボン酸としてはフタル酸、テレフタル酸、イソフタル酸、無水フタル酸の如きベンゼンジカルボン酸類又はその無水物；コハク酸、アジピン酸、セバシン酸、アゼライン酸の如きアルキルジカルボン酸類又はその無水物；フマル酸、マレイン酸、シトラコン酸、イタコン酸の如き不飽和ジカルボン酸又はその無水物等が挙げられ、また、三価以上のカルボン酸としてはトリメリット酸、ピロメリット酸、ベンゾフェノンテトラカルボン酸やその無水物等が挙げられる。
【００８６】
特に好ましいポリエステル樹脂のアルコール成分としては前記（Ｂ）式で示されるビスフェノール誘導体であり、酸成分としては、フタル酸、テレフタル酸、イソフタル酸又はその無水物、コハク酸、ｎ−ドデセニルコハク酸又はその無水物、フマル酸、マレイン酸、無水マレイン酸の如きジカルボン酸類；トリメリット酸又はその無水物のトリカルボン酸類が挙げられる。
【００８７】
これらの酸成分及びアルコール成分から得られたポリエステル樹脂を結着樹脂として使用することが、画像の定着において熱ローラ定着を用いる画像形成プロセスに本発明の乾式トナーを用いたときに、良好な定着性と優れた耐オフセット性とを実現する上で好ましい。
【００８８】
本発明に用いられるポリエステル樹脂の酸価は１０〜５０ｍｇＫＯＨ／ｇであることが好ましく、１０〜４５ｍｇＫＯＨ／ｇであることがより好ましく、１０〜４０ｍｇＫＯＨ／ｇであることがさらに好ましい。ポリエステル樹脂の酸価が５０ｍｇＫＯＨ／ｇより大きい場合、乾式トナーの帯電特性において環境依存性が大きくなり、乾式トナーの流動性、静電付着性、乾式トナーの表面抵抗（吸着水の影響）が変動し、画質の低下を生じる場合がある。樹脂の酸価が１０ｍｇＫＯＨ／ｇよりも小さい場合、磁性酸化鉄表面に存在するＭｇ、Ｃｕ、Ｚｎ、Ｔｉ、及びＡｌから選ばれる少なくとも一つの元素αとの相互作用が弱まるため、乾式トナー中での原材料の分散性が悪化し、乾式トナーの帯電量の分布が広がるため、不均一に帯電したトナー粒子が存在することとなり、画像濃度の一様性やドット再現性等画質が悪化することがある。ポリエステル樹脂の酸価は、ＪＩＳ　Ｋ　００７０に準じて公知の方法により測定することができる。
【００８９】
また、本発明では結着樹脂として、従来より結着樹脂として知られている種々の樹脂化合物をポリエステル樹脂と併用することができ、このような樹脂化合物としては、例えばビニル系樹脂、フェノール樹脂、天然樹脂変性フェノール樹脂、天然樹脂変性マレイン酸樹脂、アクリル樹脂、メタクリル樹脂、ポリ酢酸ビニル、シリコーン樹脂、ポリエステル樹脂、ポリウレタン、ポリアミド樹脂、フラン樹脂、エポキシ樹脂、キシレン樹脂、ポリビニルブチラール、テルペン樹脂、クマロインデン樹脂、石油系樹脂等が挙げられる。
【００９０】
また本発明に用いられる結着樹脂のガラス転移温度は、５０〜７５℃であることが好ましく、５５〜６５℃であることがより好ましくい。さらに前記結着樹脂の数平均分子量（Ｍｎ）は、１，５００〜５０，０００であることが好ましく、２，０００〜２０，０００であることがより好ましくい。また前記結着樹脂の重量平均分子量（Ｍｗ）は、６，０００〜１００，０００であることが好ましく、１０，０００〜９０，０００であることがより好ましい。
【００９１】
結着樹脂のガラス転移温度が上記範囲よりも小さいと乾式トナーの保存安定性が不十分となることがあり、結着樹脂のガラス転移温度が上記範囲よりも大きいと乾式トナーの定着性が不十分となることがある。結着樹脂のガラス転移温度は、後述する示差走査熱量計を用いて測定することができる。
【００９２】
また結着樹脂の数平均分子量及び重量平均分子量は、ＴＨＦ（テトラヒドロフラン）を溶媒としたＧＰＣ（ゲルパーミエションクロマトグラフィー）によって測定することができる。本発明において、トナー及び結着樹脂のＴＨＦ（テトラヒドロフラン）を溶媒としたＧＰＣによる分子量分布は次の条件で測定される。
【００９３】
試料は以下のようにして作製する。
まず試料をＴＨＦ中に入れ、数時間放置した後、十分振とうしＴＨＦとよく混ぜ（試料の合一体が無くなるまで）、さらに１２時間以上静置する。その時ＴＨＦ中への放置時間が２４時間以上となるようにする。その後、サンプル処理フィルター（ポアサイズ０．２〜０．５μｍ、例えばマイショリディスクＨ−２５−２（東ソー社製）など使用できる。）を通過させたものをＧＰＣの試料とする。又、試料濃度は、樹脂成分が０．５〜５ｍｇ／ｍｌとなるように調整する。
【００９４】
検出器にはＲＩ（屈折率）検出器を用いる。またカラムとしては市販のポリスチレンジェルカラムを複数本組み合わせるのが良く、例えば昭和電工社製のｓｈｏｄｅｘ　ＧＰＣ　ＫＦ−８０１、８０２、８０３、８０４、８０５、８０６、８０７、８００Ｐの組み合わせや、東ソー社製のＴＳＫｇｅｌ　Ｇ１０００Ｈ（Ｈ_ＸＬ）、Ｇ２０００Ｈ（Ｈ_ＸＬ）、Ｇ３０００Ｈ（Ｈ_ＸＬ）、Ｇ４０００Ｈ（Ｈ_ＸＬ）、Ｇ５０００Ｈ（Ｈ_ＸＬ）、Ｇ６０００Ｈ（Ｈ_ＸＬ）、Ｇ７０００Ｈ（Ｈ_ＸＬ）、ＴＳＫｇｕｒｄ　ｃｏｌｕｍｎの組み合せを挙げることができる。
【００９５】
４０℃のヒートチャンバー中でカラムを安定化させ、この温度におけるカラムに溶媒としてＴＨＦを毎分１ｍｌの流速で流し、ＴＨＦ試料溶液を約１００μｌ注入して測定する。
【００９６】
試料の分子量測定にあたっては試料の有する分子量分布を数種の単分散ポリスチレン標準試料により作成された検量線の対数値とカウント値との関係から算出する。検量線作成用の標準ポリスチレン試料としては例えば、東ソー社製あるいは昭和電工社製の分子量が１０^２〜１０^７程度のものを用い、少なくとも１０点程度の標準ポリスチレン試料を用いるのが適当である。
【００９７】
本発明の乾式トナーは、示差走査熱量計（ＤＳＣ）により測定される昇温時のＤＳＣ曲線に少なくとも一つの吸熱ピークが存在し、前記吸熱ピークが６０〜１２０℃に存在することが好ましい。この吸熱ピークは、６５〜１２０℃に存在することがより好ましく、７０〜１１５℃に存在することがさらに好ましい。吸熱ピークは二つ以上存在していてもよいが、その場合は６０〜１２０℃に少なくとも一つの吸熱ピークを有することが好ましい。
【００９８】
昇温時のＤＳＣ曲線からは、乾式トナーの吸熱に伴う融解挙動を見ることができる。吸熱ピークが６０〜１２０℃に存在すると、乾式トナーを加熱溶融混練したときに十分に粘度が下がり、磁性酸化鉄が良好に分散することができ、乾式トナーの帯電性を安定させる上で好ましい。
【００９９】
本発明の乾式トナーの吸熱ピークは、適当なワックスを選択して乾式トナーに含有させることによって所望の吸熱ピークを得ることができる。このような吸熱ピークを乾式トナーに付与することができるワックスは、その溶融特性から、乾式トナー表面において高い疎水性を乾式トナーに付与しやすく、本発明の特徴とする濡れ性を乾式トナーに付与する上で効果的である。
【０１００】
本発明においては、乾式トナーのＤＳＣ曲線は、示差走査熱量計（ＤＳＣ測定装置）、例えばＤＳＣ−７（パーキンエルマー社製）やＤＳＣ２９２０（ＴＡインスツルメンツジャパン社製）を用い、ＡＳＴＭ　Ｄ３４１８−８２に準じて測定することができる。ＤＳＣ曲線は、一回昇温、降温させ、前履歴を取った後、昇温速度１０℃／ｍｉｎで昇温させたときに測定されるＤＳＣ曲線を用いる。結着樹脂のガラス転移点に伴うピークは、例えば結着樹脂のみを測定するなどして区別することができる。
【０１０１】
本発明の乾式トナーは、前述した結着樹脂及び磁性酸化鉄以外の材料として種々の材料を含有していても良い。このよう他の材料として、前述したワックスや荷電制御剤等が挙げられる。
【０１０２】
本発明に用いられるワックスとしては様々なワックスが挙げられ、例えば低分子量ポリエチレン、低分子量ポリプロピレン、ポリオレフィン共重合物、ポリオレフィンワックス、マイクロクリスタリンワックス、パラフィンワックス、フィッシャートロプシュワックスの如き脂肪族炭化水素系ワックス；酸化ポリエチレンワックスの如き脂肪族炭化水素系ワックスの酸化物；又は、それらのブロック共重合物；キャンデリラワックス、カルナバワックス、木ろう、ホホバろうの如き植物系ワックス；みつろう、ラノリン、鯨ろうの如き動物系ワックス；オゾケライト、セレシン、ペトロラクタムの如き鉱物系ワックス；モンタン酸エステルワックス、カスターワックスの如き脂肪族エステルを主成分とするワックス類；脱酸カルナバワックスの如き脂肪族エステルを一部又は全部を脱酸化したものが挙げられる。
【０１０３】
さらに前記ワックスとしては、例えばパルミチン酸、ステアリン酸、モンタン酸、或いはさらに長鎖のアルキル基を有する長鎖アルキルカルボン酸類の如き飽和直鎖脂肪酸；ブラシジン酸、エレオステアリン酸、バリナリン酸の如き不飽和脂肪酸；ステアリルアルコール、エイコシルアルコール、ベヘニルアルコール、カウナビルアルコール、セリルアルコール、メリシルアルコール、或いはさらに長鎖のアルキル基を有するアルキルアルコールの如き飽和アルコール；ソルビトールの如き多価アルコール；リノール酸アミド、オレイン酸アミド、ラウリン酸アミドの如き脂肪族アミド；メチレンビスステアリン酸アミド、エチレンビスカプリン酸アミド、エチレンビスラウリン酸アミド、ヘキサメチレンビスステアリン酸アミドの如き飽和脂肪族ビスアミド；エチレンビスオレイン酸アミド、ヘキサメチレンビスオレイン酸アミド、Ｎ，Ｎ’−ジオレイルアジピン酸アミド、Ｎ，Ｎ’−ジオレイルセバシン酸アミドの如き不飽和脂肪酸アミド類；ｍ−キシレンビスステアリン酸アミド、Ｎ，Ｎ’−ジステアリルイソフタル酸アミドの如き芳香族系ビスアミド；ステアリン酸カルシウム、ラウリン酸カルシウム、ステアリン酸亜鉛、ステアリン酸マグネシウムの如き脂肪族金属塩（一般に金属石けんといわれているもの）；脂肪族炭化水素系ワックスにスチレンやアクリル酸の如きビニル系モノマーを用いてグラフト化させたワックス；ベヘニン酸モノグリセリドの如き脂肪酸と多価アルコールの部分エステル化物；植物性油脂を水素添加することによって得られるヒドロキシル基を有するメチルエステル化合物等が挙げられる。
【０１０４】
また、これらのワックスを、プレス発汗法、溶剤法、再結晶法、真空蒸留法、超臨界ガス抽出法又は融液晶析法を用いて分子量分布をシャープにしたものや低分子量固形脂肪酸、低分子量固形アルコール、低分子量固形化合物、その他の不純物を除去したものも好ましく用いられる。
【０１０５】
また、本発明においては、荷電制御剤を添加して使用することが好ましい。本発明では、荷電制御剤として負荷電性及び正荷電性のいずれの荷電制御剤も用いることができる。
【０１０６】
負荷電制御剤の具体例としては、特公昭４１−２０１５３号公報、特公昭４２−２７５９６号公報、特公昭４４−６３９７号公報、特公昭４５−２６４７８号公報等に記載されているモノアゾ染料の金属錯体、さらには特開昭５０−１３３８３８号公報に記載されているニトロフミン酸及びその塩或いはＣ．Ｉ．１４６４５等の染顔料、特公昭５５−４２７５２号公報、特公昭５８−４１５０８号公報、特公昭５８−７３８４号公報、特公昭５９−７３８５号公報等に記載されているサリチル酸、ナフトエ酸、ダイカルボン酸のＺｎ、Ａｌ、Ｃｏ、Ｃｒ、Ｆｅ、及びＺｒ等の金属錯体、スルホン化した銅フタロシアニン顔料、ニトロ基、ハロゲンを導入したスチレンオリゴマー、塩素化パラフィン等を挙げることができる。
【０１０７】
特に分散性に優れ、画像濃度の安定性やカブリの低減に効果のある、一般式（Ｉ）で表されるアゾ系金属錯体や一般式（ＩＩ）で表される塩基性有機酸金属錯体が好ましい。
【０１０８】
【化３】

【０１０９】
【化４】

【０１１０】
そのうち上記式（Ｉ）で表されるアゾ系金属錯体がより好ましく、とりわけ、中心金属がＦｅである下記式（ＩＩＩ）あるいは（ＩＶ）で表されるアゾ系鉄錯体が最も好ましい。
【０１１１】
【化５】

【０１１２】
【化６】

【０１１３】
上記式（ＩＩＩ）で示されるアゾ系鉄錯体の具体例である下記式（１）〜（６）の化合物を示す。
【０１１４】
【化７】

【０１１５】
【化８】

【０１１６】
【化９】

【０１１７】
【化１０】

【０１１８】
【化１１】

【０１１９】
【化１２】

また、上記式（Ｉ）、（ＩＩ）、（ＩＶ）で示される荷電制御剤の具体例である下記式（７）〜（１３）の化合物を示す。
【０１２０】
【化１３】

【０１２１】
【化１４】

【０１２２】
【化１５】

【０１２３】
【化１６】

【０１２４】
【化１７】

【０１２５】
【化１８】

【０１２６】
【化１９】

【０１２７】
これらの金属錯化合物は、単独でも或いは二種以上組み合わせて用いることが可能である。
【０１２８】
これらの荷電制御剤の使用量は、荷電制御剤の種類によっても異なるが、トナーの帯電量の点から、結着樹脂１００質量部当たり０．１〜５．０質量部が一般に好ましい。
【０１２９】
一方、乾式トナーを正荷電性に制御する荷電制御剤としては、例えばニグロシン及び脂肪酸金属塩等による変性物、トリブチルベンジルアンモニウム−１−ヒドロキシ−４−ナフトスルホン酸塩、テトラブチルアンモニウムテトラフルオロボレート等の四級アンモニウム塩、及びこれらの類似体であるホスホニウム塩等のオニウム塩及びこれらのレーキ顔料、トリフェニルメタン染料及びこれらのレーキ顔料、（レーキ化剤としては、リンタングステン酸、リンモリブデン酸、リンタングステンモリブデン酸、タンニン酸、ラウリン酸、没食子酸、フェリシアン化物、フェロシアン化物等）高級脂肪酸の金属塩；ジブチルスズオキサイド、ジオクチルスズオキサイド、ジシクロヘキシルスズオキサイド等のジオルガノスズオキサイド；ジブチルスズボレート、ジオクチルスズボレート、ジシクロヘキシルスズボレート等のジオルガノスズボレート類；これらを単独で或いは二種類以上組み合わせて用いることができる。
【０１３０】
また、本発明の乾式トナーには、前述した結着樹脂や磁性酸化鉄等の材料で構成されるトナー粒子に外添剤を添加することが好ましい。このような外添剤としては、例えば無機微粉体及び疎水性無機微粉体等が挙げられ、特に好ましい外添剤としてはシリカ微粉末が挙げられる。
【０１３１】
本発明に用いられるシリカ微粉体は、ケイ素ハロゲン化合物の蒸気相酸化により生成されたいわゆる乾式法又はヒュームドシリカと称される乾式シリカ及び水ガラス等から製造されるいわゆる湿式シリカの両方が使用可能であるが、表面及び内部にあるシラノール基が少なく、製造残渣のない乾式シリカの方が好ましい。
【０１３２】
さらに本発明に用いるシリカ微粉体は、疎水化処理されているものが好ましい。疎水化処理には、シリカ微粉体と反応あるいは物理吸着する有機ケイ素化合物等の疎水性の化合物で化学的に処理する方法が好ましい方法として挙げられる。より好ましい方法としては、ケイ素ハロゲン化合物の蒸気相酸化により生成された乾式シリカ微粉体を、シラン化合物で処理した後、あるいはシラン化合物で処理すると同時に、シリコーンオイルの如き有機ケイ素化合物で処理する方法が挙げられる。
【０１３３】
疎水化処理に使用されるシラン化合物としては、例えばヘキサメチルジシラザン、トリメチルシラン、トリメチルクロルシラン、トリメチルエトキシシラン、ジメチルジクロルシラン、メチルトリクロルシラン、アリルジメチルクロルシラン、アリルフェニルジクロルシラン、ベンジルジメチルクロルシラン、ブロムメチルジメチルクロルシラン、α−クロルエチルトリクロルシラン、β−クロルエチルトリクロルシラン、クロルメチルジメチルクロルシラン、トリオルガノシランメルカプタン、トリメチルシリルメルカプタン、トリオルガノシリルアクリレート、ビニルジメチルアセトキシシラン、ジメチルエトキシシラン、ジメチルジメトキシシラン、ジフェニルジエトキシシラン、ヘキサメチルジシロキサン、１，３−ジビニルテトラメチルジシロキサン、１，３−ジフェニルテトラメチルジシロキサン等が挙げられる。
【０１３４】
有機ケイ素化合物としては、シリコーンオイルが挙げられる。シリコーンオイルとしては、２５℃における粘度がおよそ３×１０^−５〜１×１０^−３ｍ^２／ｓのものが好ましく、例えばジメチルシリコーンオイル、メチルハイドロジェンシリコーンオイル、メチルフェニルシリコーンオイル、α−メチルスチレン変性シリコーンオイル、クロルフェニルシリコーンオイル、フッ素変性シリコーンオイル等が好ましい。
【０１３５】
シリコーンオイルを用いる外添剤の表面疎水化処理の方法としては、例えばシラン化合物で処理されたシリカ微粉体とシリコーンオイルとをヘンシェルミキサー等の混合機を用いて直接混合しても良いし、ベースとなるシリカへシリコーンオイルを噴射する方法によっても良い。あるいは適当な溶剤にシリコーンオイルを溶解あるいは分散せしめた後、ベースのシリカ微粉体とを混合し、溶剤を除去する方法であっても良い。
【０１３６】
前記無機微粉体及び疎水性無機微粉体の添加量は、その種類や所期の機能等によっても異なるが、トナー粒子１００質量部に対して０．１〜５質量部（好ましくは、０．１〜３質量部）であることが好ましい。
【０１３７】
本発明の乾式トナーには、シリカ微粉体等の前記無機微粉体以外の外添剤を必要に応じて添加してもよい。このような他の外添剤としては、例えば帯電補助剤、導電性付与剤、流動性付与剤、ケーキング防止剤、滑剤、研磨剤等の働きをする樹脂微粒子や無機微粒子である。
【０１３８】
より具体的には、例えばフッ素系樹脂、ステアリン酸亜鉛、ポリフッ化ビニリデンの如き滑剤、中でもポリフッ化ビニリデンが好ましい。或いは酸化セリウム、炭化ケイ素、チタン酸ストロンチウム等の研磨剤、中でもチタン酸ストロンチウムが好ましい。或いは例えば酸化チタン、酸化アルミニウム等の流動性付与剤、中でも特に疎水性のものが好ましい。ケーキング防止剤、或いは例えばカーボンブラック、酸化亜鉛、酸化アンチモン、酸化スズ等の導電性付与剤、また逆極性の白色微粒子及び黒色微粒子を現像性向上剤として少量用いることもできる。
【０１３９】
本発明の乾式トナーは、静電荷像を現像する為に使用されるトナー粒子を生成する通常の方法を用いて製造することが可能である。本発明の乾式トナーの材料としては、前述した結着樹脂及び磁性酸化鉄を少なくとも用い、さらに必要に応じて着色剤、ワックス、荷電制御剤等の他の材料が用いられる。より具体的には、本発明の乾式トナーは、これらの材料をヘンシェルミキサー又はボールミルの如き混合機により十分混合してから、ロール、ニーダー及びエクストルーダーの如き熱混練機を用いて溶融、捏和及び混練して樹脂類を互いに相溶せしめた中に、顔料又は染料を分散又は溶解せしめ、冷却固化後、粉砕及び分級を行うことにより製造することができる。
【０１４０】
本発明の乾式トナーの製造には、公知の装置を用いることができ、例えば混合機としては、ヘンシェルミキサー（三井鉱山社製）；スーパーミキサー（カワタ社製）；リボコーン（大川原製作所社製）；ナウターミキサー、タービュライザー、サイクロミックス（ホソカワミクロン社製）；スパイラルピンミキサー（太平洋機工社製）；レーディゲミキサー（マツボー社製）が挙げられる。
【０１４１】
また混練機としては、例えばＫＲＣニーダー（栗本鉄工所社製）；ブス・コ・ニーダー（Ｂｕｓｓ社製）；ＴＥＭ型押し出し機（東芝機械社製）；ＴＥＸ二軸混練機（日本製鋼所社製）；ＰＣＭ混練機（池貝鉄工所社製）；三本ロールミル、ミキシングロールミル、ニーダー（井上製作所社製）；ニーデックス（三井鉱山社製）；ＭＳ式加圧ニーダー、ニダールーダー（森山製作所社製）；バンバリーミキサー（神戸製鋼所社製）が挙げられる。
【０１４２】
また粉砕機としては、例えばカウンタージェットミル、ミクロンジェット、イノマイザ（ホソカワミクロン社製）；ＩＤＳ型ミル、ＰＪＭジェット粉砕機（日本ニューマチック工業社製）；クロスジェットミル（栗本鉄工所社製）；ウルマックス（日曹エンジニアリング社製）；ＳＫジェット・オー・ミル（セイシン企業社製）；クリプトロン（川崎重工業社製）；ターボミル（ターボ工業社製）；スーパーローター（日清エンジニアリング）が挙げられる。
【０１４３】
また分級機としては、例えばクラッシール、マイクロンクラッシファイアー、スペディッククラシファイアー（セイシン企業社製）；ターボクラッシファイアー（日新エンジニアリング社製）；ミクロンセパレータ、ターボプレックス（ＡＴＰ）、ＴＳＰセパレータ（ホソカワミクロン社製）；エルボージェット（日鉄鉱業社製）、ディスパージョンセパレータ（日本ニューマチック工業社製）；ＹＭマイクロカット（安川商事社製）が挙げられる。
【０１４４】
また粗粒等をふるい分けるために用いられる篩い装置としては、例えばウルトラソニック（晃栄産業社製）；レゾナシーブ、ジャイロシフター（徳寿工作所社）；バイブラソニックシステム（ダルトン社製）；ソニクリーン（新東工業社製）；ターボスクリーナー（ターボ工業社製）；ミクロシフター（槙野産業社製）；円形振動篩い等が挙げられる。
【０１４５】
本発明の乾式トナーは、前述したような公知の方法及び公知の装置によって製造することができるが、本発明の特徴の一つであるトナーの透過率とメタノール濃度との関係、すなわち濡れ性を達成する製造法としての一つとして、本発明においては、図２、図３及び図４に示したような機械式粉砕機を用いることが、粉体原料の粉砕処理及び表面処理を行い、かつ効率向上を図る観点から好ましい。
【０１４６】
この粉砕機において、粉砕時の温度を調整し、結着樹脂の主成分としてポリエステル樹脂を用い、かつ本発明の組成を有する磁性酸化鉄を用いることで、乾式トナーの表面の磁性酸化鉄の表面状態を制御できる。
以下、図２、図３及び図４に示す機械式粉砕機について説明する。
【０１４７】
図２は、本発明の乾式トナーを製造する際に使用される機械式粉砕機の一例の概略断面図を示しており、図３は図２におけるＤ−Ｄ’面での概略的断面図を示しており、図４は図２に示す回転子３１４の斜視図を示している。前記装置は、図２に示されているように、ケーシング３１３、ジャケット３１６、ディストリビュータ２２０、ケーシング３１３内にあって中心回転軸３１２に取り付けられた回転体で表面に多数の溝が設けられている回転子３１４、表面に多数の溝が設けられており回転子３１４の外周に一定間隔を保持して配置されている固定子３１０、さらに、被処理原料を導入するための原料投入口３１１、処理後の粉体を排出する為の原料排出口３０２とから構成されている。
【０１４８】
通常、粉砕原料を機械式粉砕機で粉砕する際には機械式粉砕機の渦巻き室２１２の温度Ｔ１や後室３２０の温度Ｔ２の温度を制御し、樹脂のＴｇ以下で粉砕を行い、表面改質を行わない方法を選択している。しかし、本発明の乾式トナーを製造する場合では、本発明の特徴とする性質の乾式トナーを得るために、原料排出口３０２の温度をＴｇに対して−２５〜−５℃の範囲となる温度に設定し、実際の粉砕状態ではＴｇの−２０〜±０℃の温度にして、粉砕後乾式トナー表面に存在する磁性酸化鉄の一部を樹脂が覆う状態となるように粉砕を行う。それにより、乾式トナー表面での原材料の存在分布が適正な値となりやすく、このような粉砕を行うことが、本発明の特徴とする疎水特性を乾式トナーに付与する上で好ましい。
【０１４９】
【実施例】
本発明の基本的な構成と特色について以上に述べたが、実施例に基づき具体的に本発明について以下に説明する。しかしながら本発明は、以下の実施例によって何ら限定されるものではない。実施例中の部数は質量部である。実施例に用いられる結着樹脂を表１に、ワックスを表２に、磁性酸化鉄粒子を表３に記す。表１に記載された結着樹脂としてのポリエステル樹脂は脱水縮合法により合成した。磁性酸化鉄粒子の製造方法については以下のとおりである。
【０１５０】
【表１】

【０１５１】
【表２】

【０１５２】
【表３】

【０１５３】
＜磁性酸化鉄粒子の製造例１＞
硫酸第一鉄水溶液中に、鉄元素に対しケイ素元素の含有量が０．４８％となるようにケイ酸ソーダを添加した後、苛性ソーダ溶液を混合し、水酸化第一鉄を含む水溶液を調製した。水溶液のｐＨを１０に調整しながら空気を吹き込み、８０乃至９０℃で酸化反応を行い、種晶を生成させるスラリー液を調製した。
【０１５４】
種晶の生成が確認されたら、このスラリー液にさらに硫酸第一鉄水溶液を適宜加え、スラリー液のｐＨを１０に調整しながら空気を吹き込み酸化反応を進めた。その間に、未反応の水酸化第一鉄濃度を調べながら反応の進行率を調べつつ、適宜硫酸亜鉛を加え、さらに水溶液のｐＨを酸化反応の初期はｐＨを９に、反応中期にはｐＨを８に、反応後期にはｐＨを６にというように段階的に調整することで磁性酸化鉄内での金属元素の分布を制御し、酸化反応を完結させた。生成した磁性酸化鉄粒子を常法により洗浄、ろ過乾燥した。得られた磁性酸化鉄粒子の一次粒子は、凝集して凝集体を形成しているので、ミックスマーラーを使用して磁性酸化鉄粒子の凝集体に圧縮力及びせん断力を付与して、前記凝集体を解砕して磁性酸化鉄粒子を一次粒子にすると共に、磁性酸化鉄粒子の表面を平滑にし、表３に示すような特性を有する磁性酸化鉄１を得た。
【０１５５】
＜磁性酸化鉄粒子の製造例２〜５＞
ケイ酸ソーダの添加量、他種元素αの塩の添加量、添加時期、及び種類の少なくともいずれかを変えた以外は製造例１と同様にして、表３に示す物性を有する磁性酸化鉄２〜５を得た。
【０１５６】
＜磁性酸化鉄粒子の製造例６＞
硫酸第一鉄水溶液中に、鉄元素に対しケイ素元素の含有量が０．４０％となるようにケイ酸ソーダを添加した後、苛性ソーダ溶液を混合し、水酸化第一鉄を含む水溶液を調製した。水溶液のｐＨを１０に調整しながら空気を吹き込み、８０乃至９０℃で酸化反応を行い、種晶を生成させるスラリー液を調製した。
【０１５７】
種晶の生成が確認されたら、このスラリー液にさらに硫酸第一鉄水溶液を適宜加え、スラリー液のｐＨを１０に調整しながら空気を吹き込み酸化反応を進めた。その間に、未反応の水酸化第一鉄濃度を調べながら反応の進行率を調べつつ、適宜硫酸マグネシウムを加え、さらに水溶液のｐＨを８に調整しながら酸化反応を完結させた。生成した磁性酸化鉄粒子を常法により洗浄、ろ過乾燥した。得られた磁性酸化鉄粒子の一次粒子は、凝集して凝集体を形成しているので、ミックスマーラーを使用して磁性酸化鉄粒子の凝集体に圧縮力及びせん断力を付与して、前記凝集体を解砕して磁性酸化鉄粒子を一次粒子にすると共に、磁性酸化鉄粒子の表面を平滑にし、表３に示すような特性を有する磁性酸化鉄６を得た。
【０１５８】
＜実施例１＞
・結着樹脂Ａ　　　　　　　　　　　　　　　　　　　　　　　１００質量部
・磁性酸化鉄１　　　　　　　　　　　　　　　　　　　　　　　９０質量部
・ワックスｄ　　　　　　　　　　　　　　　　　　　　　　　　　４質量部
・下記構造式に示す荷電制御剤Ａ　　　　　　　　　　　　　　　　２質量部
上記混合物を、１４０℃に加熱された二軸エクストルーダで溶融混練し、冷却した混練物をハンマーミルで粗粉砕し、得られた粗粉砕物をターボミル（ターボ工業社製）で機械式粉砕により微粉砕し、得られた微粉砕粉を固定壁型風力分級機で分級して分級粉を得た。さらに、得られた分級粉を、コアンダ効果を利用した多分割分級装置（日鉄鉱業社製エルボジェット分級機）で分級し、超微粉及び粗粉を同時に厳密に分級除去して、重量平均粒径（Ｄ４）６．５μｍの負帯電性トナー粒子を得た。
【０１５９】
【化２０】

【０１６０】
この得られたトナー粒子１００質量部に対し、ヘキサメチルジシラザン１５ｗｔ％とジメチルシリコーン１５ｗｔ％で疎水化処理したメタノールウェッタビリティ８０％、ＢＥＴ比表面積１２０ｍ^２／ｇの疎水性シリカ微粉体を１．３質量部とチタン酸ストロンチウム１．０質量部とを外添混合してトナー１を調整した。トナー内添処方及び物性を表４に、トナー１の、７８０ｎｍの波長の光の透過率に対するメタノール濃度のグラフを図１に示す。
【０１６１】
このトナー１を、市販のＬＢＰプリンタ（ＬｅｓｅｒＪｅｔ　４１００、ＨＰ社製）を１．５倍のプリントスピードに改造し、これを画出し試験機として、１５℃、１０％ＲＨの環境、２３℃、６０％ＲＨの環境と３０℃、８０％ＲＨの環境で１万枚のプリント試験を行った。この際、ページ内の画像濃度一様性については、高温高湿環境下でのプリントアウト画像内での、画像濃度の最高値と最低値の差によりページ内の画像濃度一様性を判断した。
【０１６２】
画像濃度は、マクベス濃度計（マクベス社製）でＳＰＩフィルターを使用して、５ｍｍ角の画像を反射濃度測定することにより測定した。カブリは、反射濃度計（リフレクトメーター　モデル　ＴＣ−６ＤＳ　東京電色社製）を用いて画像形成前後の転写材を測定し、画像形成後の白地部反射濃度最悪値をＤｓ、画像形成前の転写材の反射平均濃度をＤｒとし、Ｄｓ−Ｄｒを求め、これをカブリ量として評価した。数値の少ない方がカブリが抑制されていることを示す。これらの評価を、初期、１００００枚時、機外に一日放置した後のそれぞれの時期に行った。
【０１６３】
帯電量の立ち上がりの評価については、上記画出し試験機を用いて１５℃、１０％ＲＨの環境で４ドットの横ラインを１７６ドットスペースおきに印字した横ラインパターンを、１０秒に１枚の間隔で画出しする間欠プリント試験を行い、１枚目、３枚目、７枚目、１５枚目、５０枚目、１００枚時に５ｍｍ角の画像をサンプリングし、画像濃度を測定した。画出し枚数の早いうちから高い画像濃度が得られているものほど帯電量の立ち上がりが早いと言える。
【０１６４】
画質の評価については、上記画出し試験機を用いて、常温常湿環境（２３℃、６０％ＲＨ）で１２００ｄｐｉの孤立した１ドットのパターンを画出しし、光学顕微鏡で画像を観察してドット再現性を以下の基準により評価した。
Ａ：潜像からのトナーのはみ出しが全くなく、ドットを完全に再現している
Ｂ：潜像からのトナーのはみ出しが少しある
Ｃ：潜像からのトナーのはみ出しが多い
【０１６５】
尾引きについては、上記画出し試験機を用いて、４ドットの横ラインを２０ドットスペースに印字したパターンを画出しし、ライン上で尾を引いた数を数え、以下の基準により評価した。
Ａ：発生なし
Ｂ：３個未満
Ｃ：３〜７個未満
Ｄ：７〜１５個未満
Ｅ：１５個以上
【０１６６】
画像飛び散りについては、上記画出し試験機を用いて、４ドットの横ラインを１７６ドットスペースおきに印字した横ラインパターンを、１０秒に１枚の間隔で画出しする間欠プリント試験を行い、１００００枚目の画像飛び散りを以下の基準により評価した。
Ａ：拡大観察によっても画像飛び散りの少ない画像
Ｂ：拡大観察により飛び散りが見られるが、目視では見えない
Ｃ：飛び散りにより、文字が多少にじむ
Ｄ：飛び散りにより、ラインの太さにむらが出る
Ｅ：飛び散りにより、細かな文字の一部につぶれが見られる
【０１６７】
また、得られたトナーを温度４０℃、湿度９０％ＲＨの環境下に３０日間放置し、その後通常環境下（温度２３℃、湿度６０％ＲＨ）で、上記画出し試験機を用いて５００枚の画出し試験を行った。そのときの５００枚目の画像濃度及びカブリの評価を表６に示す。
【０１６８】
＜実施例２〜７、比較例１＞
表４に記載の処方で実施例１と同様にトナー２〜８を作製した。表中の荷電制御剤Ｂ及び荷電制御剤Ｃの構造式を以下に示す。またこれらのトナーを用いて実施例１と同様の試験を行った。結果を表５、６、７、８、９に示す。
【０１６９】
【化２１】

【０１７０】
【化２２】

【０１７１】
＜比較例２＞
分級後に得られたトナー粒子を、３００℃の熱風中を瞬間的に通過させる処理を行った以外は、表４に記載の処方で実施例１と同様にトナー９を作製した。このトナー９を用いて実施例１と同様の試験を行った。結果を表５、６、７、８、９に示す。
【０１７２】
＜比較例３＞
粉砕工程では、衝突式気流粉砕による微粉砕機を用いた以外は、表４に記載の処方で実施例１と同様にトナー１０を作製した。このトナー１０を用いて実施例１と同様の試験を行った。結果を表５、６、７、８、９に示す。
【０１７３】
【表４】

【０１７４】
【表５】

【０１７５】
【表６】

【０１７６】
【表７】

【０１７７】
【表８】

【０１７８】
【表９】

【０１７９】
【発明の効果】
本発明によれば、少なくとも結着樹脂及び磁性酸化鉄を有するトナーにおいて、結着樹脂は、ポリエステル樹脂を主成分として含有し、磁性酸化鉄は、Ｓｉと、Ｍｇ、Ｃｕ、Ｚｎ、Ｔｉ、及びＡｌから選ばれる少なくとも一つの元素である元素αとを含有し、磁性酸化鉄におけるＳｉの含有量は、磁性酸化鉄を基準として０．１〜２．０質量％であり、磁性酸化鉄における元素αの含有量は、磁性酸化鉄を基準として０．１〜４．０質量％であり、Ｘ線光電子分光法によって測定される磁性酸化鉄の最表面における元素αの原子濃度が１．００〜７．００％であり、メタノール及び水の混合溶媒に対するトナーの濡れ性を７８０ｎｍの波長の光の透過率で測定した場合、透過率が８０％のときのメタノール濃度が４５〜６５体積％の範囲内で、また、透過率が１０％のときのメタノール濃度が４５〜６５体積％の範囲内であることから、高温高湿、低温低湿のような厳しい環境下における高速現像においても長期の使用において高い現像性を維持し、帯電量の立ち上がりの速い、高画質でありかつ、良好な現像性、環境安定性を持つことができるトナーを得ることができる。
【０１８０】
また本発明では、メタノール及び水の混合溶媒に対するトナーの濡れ性を７８０ｎｍの波長の光の透過率で測定した場合、透過率が８０％のときのメタノール濃度が５０〜６５体積％の範囲内で、また、透過率が１０％のときのメタノール濃度が５０〜６５体積％の範囲内であると、乾式トナーの帯電量を適正に保ち、カブリを防止し、かつ画像濃度の高い良好な画像を形成する上でより一層効果的である。
【０１８１】
また本発明では、示差走査熱量計により測定されるトナーの昇温時のＤＳＣ曲線に少なくとも一つの吸熱ピークが存在し、吸熱ピークが６０℃〜１２０℃に存在すると、トナー粒子中に磁性酸化鉄を良好に分散させ、乾式トナーの帯電性を安定させる上でより一層効果的である。
【０１８２】
また本発明では、ポリエステル樹脂の酸価が１０〜５０ｍｇＫＯＨ／ｇであると、乾式トナーの帯電性を安定させ、かつ環境変化によらない安定した良好な画像を形成する上でより一層効果的である。
【０１８３】
また本発明では、磁性酸化鉄におけるＳｉの含有量は、磁性酸化鉄を基準として０．３〜１．８質量％であると、乾式トナーを適度にかつすばやく帯電させる上でより一層効果的である。
【０１８４】
また本発明では、磁性酸化鉄における元素αの含有量は、磁性酸化鉄を基準として０．１〜２．０質量％であると、環境変化によらず乾式トナーを十分に帯電させ、高画質及び高画像濃度の良好な画像を形成する上でより一層効果的である。
【０１８５】
また本発明では、元素αがＭｇ、Ａｌ、及びＺｎから選ばれる元素であると、環境変化によらず乾式トナーを十分に帯電させ、高画質及び高画像濃度の良好な画像を形成する上でより一層効果的である。
【０１８６】
また本発明では、Ｘ線光電子分光法によって測定される磁性酸化鉄の最表面におけるＳｉ原子の原子濃度が１２．５〜１７．５％であり、Ｆｅ原子の原子濃度が７０．００〜８５．００％であると、磁性酸化鉄の通電性と電気抵抗のバランスをとり、乾式トナーの帯電量を制御し、その結果、環境によらず高画像濃度、高画質な現像性を得る上でより一層効果的である。
【０１８７】
また本発明では、Ｘ線光電子分光法によって測定される磁性酸化鉄の最表面の原子濃度において、Ｓｉ原子に対する元素αの比が０．０５〜０．５であり、Ｓｉ原子に対するＦｅ原子の比が３．００〜７．００であり、元素αに対するＦｅ原子の比が１０．０〜７０．０であると、磁性酸化鉄の通電性と電気抵抗のバランスをとり、乾式トナーの帯電量を制御し、その結果、環境によらず高画像濃度、高画質な現像性を得る上でより一層効果的である。
【０１８８】
また本発明では、磁性酸化鉄を結着樹脂１００質量部に対して３０〜１５０質量部含有していると、良好な帯電性と現像性とを両立させ、良好な画像を形成する上でより一層効果的である。
【図面の簡単な説明】
【図１】本発明の実施例１におけるトナー１の、メタノール濃度に対する波長の光７８０ｎｍの透過率を示したグラフである。
【図２】本発明の乾式トナーを製造する際に使用され得る機械式粉砕機の概略断面図である。
【図３】図２に示す機械式粉砕機をＤ−Ｄ’面に沿って切断して示す概略的断面図である。
【図４】図２に示す回転子の斜視図である。
【符号の説明】
２１２　渦巻き室
２１９　パイプ
２２０　ディストリビュータ
２２２　バグフィルター
２２４　吸引ブロワ
２２９　捕集サイクロン
３０１　機械式粉砕機
３１０　固定子
３１１　原料投入口
３１２　中心回転軸
３１３　ケーシング
３１４　回転子
３１５　定量供給機
３１６　ジャケット
３２０　後室[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an electrophotographic method, an image forming method for visualizing an electrostatic image, and a developing toner used for a toner jet.
[0002]
[Prior art]
Devices using electrophotography are widely used not only in copiers for copying original documents, but also in fields such as printers and facsimile machines as computer outputs.
[0003]
In recent years, improvements such as smaller, lighter, faster, and more reliable have been rigorously pursued in such devices, and such devices are composed of simpler elements in various respects. Tend to be. As a result, the performance required of the toner becomes higher, and if the performance of the toner cannot be improved, it tends to be difficult to establish a better device.
[0004]
In addition, various developing methods have been put into practical use in the electrophotographic developing method. Among them, a developing device having a simple structure has few troubles, has a long life, and is easy to maintain. Component development is preferably used. In such a developing method, the quality of image formation largely depends on the performance of the magnetic toner. In a magnetic toner, the magnetic iron oxide imparts magnetism to the toner by containing the magnetic iron oxide, so that the magnetic iron oxide affects the developability and durability of the magnetic toner.
[0005]
From such a technical background, various techniques for improving the performance of the toner have been proposed in recent years. As such a technique, a toner is dispersed in a mixed solution of ethanol and water, the absorbance at that time is measured, and the amount of magnetic iron oxide present on the surface of the magnetic toner is known, so that a charging roller caused by the magnetic toner can be obtained. There is known a technology that can easily determine the degree of contamination of the toner and fusion of the magnetic toner to the photosensitive drum (for example, see Patent Document 1). However, although the toner having a small amount of magnetic iron oxide on the surface is effective for the above-described contamination and fusing, the existence state of the magnetic iron oxide on the surface of the magnetic toner cannot be said to be appropriate, There are problems such as poor charging of the magnetic toner due to too little magnetic iron oxide on the toner surface and deterioration in image quality due to uneven charging distribution of the magnetic toner.
[0006]
As for the toner, a technique relating to a toner having a certain wetting property with respect to ethanol is known (for example, see Patent Document 2). The wetting property is obtained by expressing the hydrophobic property of the toner by an ethanol drop transmittance curve, and is determined by measuring the transmittance with respect to the ethanol content. Although the toner having such characteristics is effective in preventing drum fusion and suppressing image flow, the dispersion state of raw materials on the surface of the toner is not sufficiently controlled, and is caused by the surface state of the toner. There is room for improvement in controlling the charge amount of the toner.
[0007]
The magnetic iron oxide used in the magnetic toner contains 1.7 to 4.5 atomic% of silicon with respect to Fe in terms of Si, and as metal elements other than iron, Mn, Zn, Ni, Cu, Al, Magnetite particles containing one or more metal elements selected from Ti in an amount of 0 to 10 atomic% with respect to Fe are known (for example, see Patent Documents 3 and 4). According to the magnetite particles, the magnetic properties and the charging properties of the magnetic toner are improved, but there is still room for improvement in terms of compatibility between the developability and the image quality in a high-speed developing system by simply adding the above-mentioned metal. Have been.
[0008]
Further, as the magnetite particles, the silicon component is continuously contained from the center of the magnetite particles to the surface, the silicon component is exposed on the particle surface, and Zn, Mn, Cu, Ni, Co, Cr, 2. Description of the Related Art Magnetite particles in which the outer shell of a particle is coated with a metal compound comprising at least one metal component selected from Cd, Al, Sn, Mg, and Ti are known (for example, see Patent Document 5). However, the use of such magnetite particles has not yet been improved in image quality and developability due to long-term use, particularly in a high-speed development system, and has further points to be improved.
[0009]
Further, as the magnetic iron oxide, based on the iron element, the content of one or more metal elements selected from the group consisting of Mn, Zn, Ni, Cu, Co, Cr, Cd, Al, Sn and Mg, and Magnetic iron oxides are known in which the content of silicon elements, the content of silicon elements present up to a dissolution rate of iron of up to 20% by mass, and the content of silicon elements present up to a dissolution rate of iron of up to 10% are defined. (See, for example, Patent Documents 6, 7, and 8). According to such a magnetic iron oxide, while various metals are contained in the magnetic iron oxide and the distribution of Si in the magnetic iron oxide is regulated, the effect of improving environmental stability can be seen. Further improvement in durability is desired.
[0010]
Further, as the magnetite particles, the silicon component and the aluminum component are continuously contained from the center of the magnetite particle to the surface, and these components are exposed on the particle surface, and Zn, Mn, Cu, which are combined with the silicon component and the aluminum component, Magnetite particles in which the outer shell of a particle is coated with a metal compound comprising at least one metal component selected from Ni, Co, Cr, Cd, Al, Sn, Mg, and Ti are known (for example, Patent Document 9). reference.). However, the use of the magnetite particles has not yet provided sufficient charge stability to the magnetic toner.
[0011]
Regarding the magnetic properties of the toner, a method of reducing the saturation magnetization of the toner by, for example, replacing divalent iron of magnetite with a divalent metal such as zinc or copper is known (for example, Patent Documents 10 and 11). reference.). However, in such a method, it is not enough to control the charge amount of the toner in the high-speed developing system only by controlling the magnetic properties of the magnetic substance and the toner.
[0012]
[Patent Document 1]
JP-A-11-194533
[Patent Document 2]
JP-A-2000-242027
[Patent Document 3]
JP-A-9-59024
[Patent Document 4]
JP-A-9-59025
[Patent Document 5]
JP-A-11-157843
[Patent Document 6]
JP-A-11-316474
[Patent Document 7]
JP-A-11-249335
[Patent Document 8]
JP-A-11-282201
[Patent Document 9]
JP-A-11-189420
[Patent Document 10]
JP-A-4-184354
[Patent Document 11]
JP-A-4-223487
[0013]
[Problems to be solved by the invention]
SUMMARY OF THE INVENTION An object of the present invention is to provide a toner that solves the above-mentioned problems, and the charge amount of the toner quickly rises even in a high-speed developing system, and the image quality and the image density do not deteriorate even in long-term use. Another object of the present invention is to provide a toner having excellent environmental stability.
[0014]
[Means for Solving the Problems]
The present invention relates to a toner having at least a binder resin and a magnetic iron oxide, wherein the binder resin contains a polyester resin as a main component, and the magnetic iron oxide is formed of Si, Mg, Cu, Zn, Ti, and Al. At least one selected element, the content of Si in the magnetic iron oxide is 0.1 to 2.0% by mass based on the magnetic iron oxide; The content is 0.1 to 4.0% by mass based on the magnetic iron oxide, and the atomic concentration of the element α at the outermost surface of the magnetic iron oxide measured by X-ray photoelectron spectroscopy is 1.00 to 7.0. When the wettability of the toner with respect to the mixed solvent of methanol and water is measured by the transmittance of light having a wavelength of 780 nm, the methanol concentration is within the range of 45 to 65% by volume when the transmittance is 80%. ,Also, Methanol concentration when the excessive rate of 10% related to dry toner is in the range of 45 to 65 vol%.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
The present inventors have developed a magnetic toner having a polyester resin by controlling the wettability of the magnetic toner with respect to a specific solvent, and controlling the atomic concentration of a specific metal element present on the outermost surface of the magnetic iron oxide. It has been found that they are extremely excellent in properties, durability and fluidity, and that excellent developability can be obtained even in high-speed development.
[0016]
In the dry toner of the present invention, when the wettability of the toner with respect to a mixed solvent of methanol and water is measured by the transmittance of light having a wavelength of 780 nm, the methanol concentration when the transmittance is 80% is in the range of 45 to 65% by volume. And the methanol concentration when the transmittance is 10% is in the range of 45 to 65% by volume. According to such a feature, a dry toner having stable charging characteristics and excellent developing properties even in low-temperature, low-humidity, high-temperature, and high-humidity environments can be obtained.
[0017]
FIG. 1 is a graph showing the relationship between the transmittance of light having a wavelength of 780 nm and the methanol concentration of the dry toner of Example 1 to be described later of the present invention. The region where the transmittance exceeds 80% indicates that the dry toner is hardly wet with methanol, and the region where the transmittance is lower than 10% indicates that the dry toner is almost completely wet.
[0018]
The wettability of the dry toner of the present invention with respect to a mixed solvent of methanol and water (hereinafter also referred to as a “methanol-water mixed solvent”) is greatly affected by the surface material composition of toner particles and the state of their existence. The less the magnetic iron oxide is exposed on the surface of the toner particles, that is, the greater the ratio of the surface of the toner particles covered with the binder resin component, the more the toner particles become wet with a higher methanol concentration. As the ratio of the binder resin component on the surface of the toner particles increases, the chargeability of the dry toner improves, and higher developability can be obtained. However, if the exposure of the magnetic iron oxide is too small, the dry toner of the present invention cannot obtain proper charging performance, which is not preferable.
[0019]
Further, the more the magnetic iron oxide is exposed, that is, the smaller the ratio of the surface of the toner particles covered with the binder resin component, the more the toner particles become wet at a lower methanol concentration. As the ratio of the magnetic iron oxide on the surface of the toner particles increases, the charge leakage sites of the dry toner of the present invention increase, so that it is difficult to maintain the charge amount and it is difficult to obtain good developability.
[0020]
That is, as shown in FIG. 1, the transmittance reaches 80% when the methanol concentration of the mixed solvent is 45 to 65% by volume, and the transmittance reaches 10% when the methanol concentration is 45 to 65% by volume. It means that the particles have moderate wettability to methanol (hydrophobicity to water), meaning that the surface material composition and the state of existence in the toner particles are uniform, and that the dry toner has excellent charging characteristics. It means there is.
[0021]
When the wettability of the dry toner of the present invention with respect to a mixed solvent of methanol and water is measured by the transmittance of light having a wavelength of 780 nm, the methanol concentration when the transmittance is 80% is 45 to 65% by volume, preferably 50%. To 65% by volume, more preferably 55 to 65% by volume. The fact that the methanol concentration of the mixed solvent is within the above range indicates that the ratio of the binder resin and the magnetic iron oxide exposed on the surface of the toner particles is within an appropriate range, and that the dry toner of the present invention has an appropriate charge. It indicates that the quantity can be kept.
[0022]
That is, the fact that the ratio of the exposed binder resin to the magnetic iron oxide is within an appropriate range means that the binder resin component is sufficiently and appropriately present on the surface of the toner particles to enhance the charging ability of the dry toner, and furthermore, the magnetic iron oxide This indicates that excessive exposure of the dry toner is prevented by appropriately exposing the toner.
[0023]
If the methanol concentration at a transmittance of 80% is lower than 45% by volume, a large number of toner particles having a large amount of magnetic iron oxide exposed on the surface are present, and the number of charge leakage sites increases, and the dry type The chargeability of the toner becomes insufficient, and the developability becomes poor. When the methanol concentration exceeds 65% by volume when the transmittance is 80%, it means that there are a large number of toner particles that are less exposed to the surface of the magnetic iron oxide, and the dry toner tends to be excessively charged. If a large amount of charge cannot be maintained, the image density may decrease and fog may increase.
[0024]
Further, when the wettability of the dry toner of the present invention with respect to a methanol-water mixed solvent is measured by the transmittance of light having a wavelength of 780 nm, the methanol concentration when the transmittance is 10% is 45 to 65% by volume, and is preferable. Is from 50 to 65% by volume, more preferably from 55 to 65% by volume. The fact that the methanol concentration of the mixed solvent is within the above range indicates that the exposure ratio of the binder resin and the magnetic iron oxide on the surface of most of the toner particles is within an appropriate range, and that the dry toner has an appropriate charge amount. It is shown that can be maintained.
[0025]
If the methanol concentration at a transmittance of 10% is lower than 45% by volume, most of the toner particles in the dry toner have a large proportion of magnetic iron oxide exposed on the surface, and the dry toner is charged. Becomes insufficient, and the developability becomes poor. If the methanol concentration exceeds 65% by volume when the transmittance is 10%, the proportion of toner particles having the magnetic iron oxide properly exposed on the surface is small, and the dry toner tends to be excessively charged, and Since the charge amount cannot be maintained, the image density may decrease and fog may increase.
[0026]
In the present invention, the relationship between the transmittance and the methanol concentration, that is, the wettability of the dry toner, that is, the hydrophobic property of the dry toner is measured using a methanol drop transmittance curve. Specifically, as the measuring device, for example, a powder wettability tester WET-100P manufactured by Resca Co., Ltd. is mentioned, and as a specific measuring operation, a method exemplified below is mentioned.
[0027]
First, 70 ml of a hydrated methanol solution composed of 40% by volume of methanol and 60% by volume of water is placed in a container, and dispersed for 5 minutes by an ultrasonic disperser in order to remove bubbles and the like in the measurement sample. To this, 0.5 g of a dry toner as a specimen is precisely weighed and added to prepare a sample liquid for measuring the hydrophobic property of the dry toner.
[0028]
Next, this measurement sample solution was used for 6.67 seconds. ^-1 While stirring at a speed of 1.3 ml / min. , And the transmittance is measured with light having a wavelength of 780 nm to prepare a methanol drop transmittance curve as shown in FIG. In this case, methanol was used as the titration solvent because various toner materials such as dyes, pigments, and charge control agents contained in the toner particles are less likely to elute, and the surface state of the dry toner can be more accurately observed. It is. In this measurement, a cylindrical glass beaker having a bottom diameter of 5 cm and a thickness of 1.75 mm was used as a container, and a magnetic stirrer was a spindle type having a length of 25 mm and a maximum diameter of 8 mm, and was made of fluorine. Those coated with resin were used.
[0029]
When the dry toner is wet with a methanol concentration of less than 40% by volume, the transmittance of light having a wavelength of 780 nm is rapidly reduced to approach 0% by simply adding the dry toner to the mixed solvent and stirring the mixture. .
[0030]
The dry toner of the present invention has a magnetic iron oxide. This magnetic iron oxide contains Si and an element α which is at least one element selected from Mg, Cu, Zn, Ti, and Al, and the content of Si in the magnetic iron oxide is based on the magnetic iron oxide. Is 0.1 to 2.0% by mass, the content of the element α in the magnetic iron oxide is 0.1 to 4.0% by mass based on the magnetic iron oxide, and X-ray photoelectron spectroscopy (XPS) Is characterized in that the atomic concentration of the element α at the outermost surface of the magnetic iron oxide measured by the method described above is 1.00 to 7.00%.
[0031]
The element α is at least one element selected from Mg, Cu, Zn, Ti, and Al, and is preferably an element selected from Mg, Zn, and Al. The content of the element α is 0.1 to 4.0% by mass, more preferably 0.1 to 2.0% by mass, based on the magnetic iron oxide.
[0032]
The magnetic iron oxide containing the element α has an excellent balance of the degree of exposure of the magnetic iron oxide particles to the surface of the toner particles and the like, and can maintain a high charge amount of the toner regardless of the environment. Further, it has a function of controlling the distribution of the charge amount of the toner to be narrow. As a result, thin and short ears can be densely formed on the developer carrying member, and high image quality (dot reproducibility, etc.) and high image density performance can be obtained.
[0033]
When the content of the element α is less than 0.1% by mass, the electric resistance of the magnetic iron oxide itself decreases, and it becomes difficult to maintain the charge amount of the toner in an environment such as high temperature and high humidity. May lead to a decrease in concentration. When the content of the element α is less than 0.1% by mass, it is difficult to expose the magnetic iron oxide on the surface of the toner particles, which may cause a decrease in concentration due to charge-up and an increase in fog.
[0034]
When the content of the element α is more than 4.0% by mass, the electric resistance of the magnetic iron oxide itself becomes too high, and fog may increase. In addition, since the rising speed of the charge amount of the toner is slow, the distribution of the charge amount as the toner is likely to be broad, and the spikes of the toner on the developer carrier are not uniform, and the dot reproducibility and the dot reproducibility on the paper are reduced. Splattering is likely to be worse.
[0035]
Further, the magnetic iron oxide used in the present invention contains at least Si. The content of Si in the magnetic iron oxide is 0.1 to 2.0% by mass, more preferably 0.3 to 1.8% by mass, based on the magnetic iron oxide.
[0036]
If the content of Si is less than 0.1% by mass, the toner cannot obtain a desired charge amount, and the rise of the charge amount becomes slow, so that the image density may decrease. If the content of Si is more than 2.0% by mass, the charge amount of the toner is too high, which may cause a decrease in density due to charge-up and an increase in fog.
[0037]
The magnetic iron oxide used in the present invention has an atomic concentration of the element α at the outermost surface measured by X-ray photoelectron spectroscopy (XPS) of 1.00 to 7.00%, more preferably 1.00. ~ 6.00%.
[0038]
When the atomic concentration of the element α is less than 1.00%, the surface electric resistance of the magnetic iron oxide itself decreases, and it becomes difficult to maintain the charge amount of the dry toner in an environment such as high temperature and high humidity. Image density may be reduced. If the atomic concentration of the element α on the outermost surface is less than 1.00%, it becomes difficult to expose the magnetic iron oxide on the surface of the toner particles, which may cause a decrease in concentration due to charge-up and an increase in fog. When the concentration of the element α on the outermost surface is more than 7.00%, the surface electric resistance of the magnetic iron oxide itself becomes too high, and fog may increase.
[0039]
Here, the dry toner of the present invention will be described from the viewpoint of the charge amount distribution.
In continuous development in a high-speed development system, it is particularly required that magnetic toner regulated by a regulation blade on a developer carrier, a so-called developing sleeve, be charged quickly and uniformly. As a result, a good image can always be provided even in a high-speed developing system.However, if the magnetic toner is non-uniformly charged and the distribution of the amount of charge is uneven, when the toner is continuously developed, When developing an image, the variation in the amount of charge of the magnetic toner supplied onto the developing sleeve and the amount of charge of the magnetic toner on the developing sleeve becomes large, and an image with much scattering may be generated. Further, the ears of the toner on the developing sleeve are not uniform, and the dot reproducibility tends to deteriorate.
[0040]
The charge amount distribution of the magnetic toner is greatly affected by the material dispersibility of the surface of the magnetic toner, and the more uniform the material dispersibility, the more uniform the charge amount distribution. In the present invention, the material dispersibility of the surface of the dry toner can be determined by measuring the wettability behavior of the dry toner with respect to the methanol-water mixed solvent. The more uniform the material dispersibility on the surface, the smaller the difference in methanol concentration from when the dry toner starts to wet the methanol-water mixed solvent until it ends.
[0041]
In the present invention, when the wettability of the toner with respect to the mixed solvent of methanol and water is measured by the transmittance of light having a wavelength of 780 nm, the methanol concentration is within the range of 45 to 65% by volume when the transmittance is 80%. The methanol concentration when the transmittance is 10% is in the range of 45 to 65% by volume. As described above, in the dry toner of the present invention, the difference between the methanol concentration when the transmittance is 80% and the methanol concentration when the transmittance is 10% is small. This means that the charge amount distribution of the dry toner is made uniform. This shows that a uniform and high chargeability can be quickly imparted to the dry toner. The magnetic iron oxide used in the present invention can further promote this effect.
[0042]
In addition, the magnetic toner having high chargeability has poor fluidity, and the magnetic toner tends to locally aggregate fine powder on the developing sleeve, resulting in a nonuniform coating state of the developing sleeve. However, in the present invention, since at least the atomic concentration and the atomic ratio of the element α on the surface of the magnetic iron oxide are controlled, the magnetic iron oxide on the dry toner surface may be reduced. Promotes uniform charging and can prevent this phenomenon.
[0043]
In the present invention, the magnetic iron oxide is in a state of being uniformly exposed on the surface of the dry toner because it has an appropriate methanol wettability. That is, the ratio of exposure of the magnetic iron oxide on the dry toner surface is small, but by controlling the atomic concentration and atomic ratio of iron, silica, and zinc on the outermost surface of the magnetic iron oxide, it is more effective with a small exposure amount. Can be demonstrated. In addition, by doing so, it is possible to impart good fluidity to the dry toner without impairing the high and uniform chargeability of the dry toner. Even when it has begun, developability can be maintained and image deterioration can be effectively prevented.
[0044]
In addition, this makes it possible to impart good fluidity to the dry toner without deteriorating the high and uniform chargeability of the dry toner, and raises the internal temperature of the image forming apparatus and exposes the dry toner to stress. Therefore, even when toner deterioration starts, the present invention can maintain good developability and can effectively prevent image deterioration.
[0045]
Referring to the charge amount distribution of the toner in the present invention, when the methanol concentration at the transmittance of 80% is lower than 45% by volume, or when the transmittance is 10%, the methanol concentration is lower than 45% by volume. In addition, the charge amount distribution of the dry toner becomes broad, the developability is poor, the scattering and the dot reproducibility of minute parts may be deteriorated. If the methanol concentration at a transmittance of 80% exceeds 65% by volume, or the methanol concentration at a transmittance of 10% exceeds 65% by volume, the dry toner becomes excessively charged or the dry toner is charged. The amount distribution becomes broad, and non-uniformly charged toner particles are present, and image quality such as image density uniformity and dot reproducibility may deteriorate.
[0046]
In the present invention, the presence of at least one element α and Si selected from Mg, Cu, Zn, Ti, and Al at the same time on the outermost surface of the magnetic iron oxide, And electric resistance are balanced to control the charge amount of the toner. As a result, it is preferable to obtain high image density and high image quality developability regardless of the environment.
[0047]
That is, in the present invention, the atomic concentration of Si atoms on the outermost surface of the magnetic iron oxide measured by X-ray photoelectron spectroscopy (XPS) is 12.5 to 17.5% (more preferably 12.50 to 17.5%). 00%), and the atomic concentration of Fe atoms is preferably 70.00 to 85.00% (more preferably 75.00 to 85.00%).
[0048]
In the present invention, the ratio of the element α to Si atoms, that is, the element α / Si is 0.05 to 0.5 (at the outermost surface of the magnetic iron oxide measured by X-ray photoelectron spectroscopy (XPS)). More preferably 0.05 to 0.40), and the ratio of Fe atoms to Si atoms, that is, Fe / Si is 3.00 to 7.00 (more preferably 4.00 to 7.00). It is preferable that the ratio of Fe atoms to the element α, that is, the ratio of Fe / element α is 10.0 to 70.0 (more preferably 10.00 to 65.00).
[0049]
If the concentration of Si atoms on the outermost surface is less than 12.50%, the dry toner cannot obtain a desired amount of charge, and the rise of the amount of charge becomes slow, so that an image is formed with such a toner. May cause a decrease in image density. If the concentration of Si atoms on the outermost surface is higher than 17.50%, the charge amount of the toner is too high, which may cause a decrease in concentration due to charge-up and an increase in fog.
[0050]
If the concentration of Fe atoms on the outermost surface is less than 70.00%, the electric resistance of the surface of the magnetic iron oxide itself decreases, and it becomes difficult to maintain the charge amount of the dry toner in an environment such as high temperature and high humidity. As a result, the image density may be reduced in the morning. If the concentration of Fe atoms on the outermost surface is higher than 85.00%, the rising speed of the charge amount of the dry toner becomes slow, so that the charge amount distribution as the toner tends to be broad, and the toner is The ears become uneven, and the dot reproducibility and scattering on paper may be deteriorated.
[0051]
When the element α / Si is less than 0.05, the charge amount of the dry toner increases, but the surface electric resistance of the magnetic iron oxide itself decreases. Is difficult to maintain in an environment such as high temperature and high humidity, and as a result, the image density may decrease in the morning. When the element α / Si is larger than 0.50, not only does the rise of the charge amount of the dry toner become slow, but also the surface electric resistance of the magnetic iron oxide itself becomes too high and fog may increase.
[0052]
When the Fe / Si ratio is less than 3.00, the charge amount of the dry toner is increased, but the surface electric resistance of the magnetic iron oxide itself is reduced. It becomes difficult to maintain the charge amount in an environment such as high temperature and high humidity, and as a result, the image density may decrease in the morning. When the Fe / Si ratio is larger than 7.00, the dry toner cannot obtain a desired charge amount, and the rise of the charge amount becomes slow, which may cause a decrease in image density. Furthermore, since the rising speed of the charge amount of the dry toner becomes slower, the distribution of the charge amount as the dry toner tends to be broad, the toner ears become uneven on the developer carrier, and dot reproducibility and paper Scattering may worsen.
[0053]
If the ratio of Fe / element α is less than 10.00, the surface electric resistance of the magnetic iron oxide itself may be too high, and fog may increase. When the ratio of Fe / element α is larger than 70.00, the electric resistance of the magnetic iron oxide itself decreases, and it becomes difficult to maintain the charge amount of the dry toner in an environment such as high temperature and high humidity. As a result, the image density decreases in the morning. May lead to Further, the magnetic iron oxide is less likely to be exposed on the surface of the toner particles, which may cause a decrease in density due to charge-up and an increase in fog.
[0054]
When the composition state of the atoms on the outermost surface of the magnetic iron oxide is out of the above range, the electric resistance and the chargeability of the magnetic iron oxide itself cannot be balanced, and the image density is reduced, the fog is deteriorated, the dot reproducibility and the like are reduced. It is not preferable because it may lead to deterioration of scattering on paper.
[0055]
The magnetic iron oxide used in the present invention uses a suitable salt containing a Si atom and a suitable salt containing the element α, and appropriately adjusts the pH in the reaction system when producing a normal magnetic iron oxide. It is possible to manufacture with. The method for producing the magnetic iron oxide used in the present invention will be described below, taking as an example the case where zinc is used as the element α.
[0056]
The magnetic iron oxide according to the present invention is obtained by adding a predetermined amount of a metal salt of Zn and a silicate to an aqueous ferrous salt solution, and then adding an alkali such as sodium hydroxide in an equivalent amount or more to the iron component, An aqueous solution containing ferrous oxide is prepared. Air is blown in while maintaining the pH of the prepared aqueous solution at pH 7 or more (preferably pH 8 to 10), and while the aqueous solution is heated to 70 ° C. or more, an oxidation reaction of ferrous hydroxide is performed to obtain a core of magnetic iron oxide particles. First, a seed crystal is produced.
[0057]
Next, an aqueous solution containing the first equivalent of ferrous sulfate based on the amount of the alkali added previously is added to the slurry-like liquid containing the seed crystals. Thereafter, the reaction of ferrous hydroxide is advanced while blowing air while maintaining the pH of the solution at 6 to 10, and magnetic iron oxide particles are grown with the seed crystal as a core, as in the present invention. In the magnetic iron oxide characterized by keeping the composition ratio of the element on the outermost surface of the magnetic iron oxide constant, the progress of the oxidation reaction proceeds step by step in combination with the adjustment of pH. For example, the oxidation reaction progresses stepwise according to the pH, such that the pH is 9 to 10 at the beginning of the reaction, 8 to 9 at the middle of the reaction, and 6 to 8 at the late stage of the reaction. This makes it possible to more easily control the composition ratio of the outermost surface of the magnetic iron oxide. Further, the pH of the liquid shifts to the acidic side as the oxidation reaction proceeds, but it is preferable that the pH of the liquid is not less than 6.
[0058]
Examples of the metal salt containing silicon or element α to be added include sulfates, nitrates, and chlorides of silicon or element α. In addition, silicon may be used as a silicate, and examples of the silicate to be added include sodium silicate and potassium silicate.
[0059]
As the ferrous salt, it is generally possible to use iron sulfate produced as a by-product in the production of titanium sulfate and iron sulfate produced as a by-product of cleaning the surface of a copper plate, and further use iron chloride or the like. Is possible.
[0060]
In a method for producing a magnetic iron oxide by an aqueous solution method, an iron salt is generally used at an iron concentration of about 0.5 to 2 mol / liter from the viewpoint of preventing the viscosity from increasing during the reaction and the solubility of iron sulfate. . In general, the smaller the concentration of iron sulfate, the smaller the particle size of the product. In the reaction, the larger the amount of air and the lower the reaction temperature, the more easily the particles are atomized.
[0061]
According to the above-described manufacturing method, observation by a transmission electron microscope photograph shows that the magnetic iron oxide particles are mainly composed of spherical particles formed with a curved surface having no plate-like surface, and hardly contain octahedral particles. Iron oxide can be produced, and in the present invention, it is preferable to use magnetic iron oxide having such a particle shape.
[0062]
Further, in the present invention, the magnetic iron oxide has a bulk density of 0.3 to 2.0 g / cm. ³ And preferably 0.5 to 1.3 g / cm ³ Is more preferable. Bulk density is 0.3g / cm ³ If the ratio is less than the above range, the physical miscibility of the toner with other constituent materials during the production of the toner tends to be adversely affected, and the dispersibility of the magnetic iron oxide in the dry toner may deteriorate.
[0063]
Further, in the present invention, the magnetic iron oxide has a number average particle diameter of 0.05 to 1.00 μm in terms of dispersibility of the magnetic iron oxide in the binder resin and uniformity of charging of the dry toner. More preferably, it is 0.10 to 0.40.
[0064]
Further, in the present invention, the magnetic iron oxide has a BET specific surface area of 15.0 m. ² / G or less, and 12.0 m ² / G or less. BET specific surface area of magnetic iron oxide particles is 15.0 m ² / G, the moisture adsorption of the magnetic iron oxide particles increases, which affects the hygroscopicity and chargeability of the dry toner containing the magnetic iron oxide particles.
[0065]
Further, in the present invention, the magnetic iron oxide has a magnetic property of a saturation magnetization of 10 to 200 Am under a magnetic field of 795.8 kA / m. ² / Kg (more preferably 70-100 Am ² / Kg), and the residual magnetization is 1 to 100 Am ² / Kg (more preferably 2 to 20 Am ² / Kg), and the coercive force is preferably 1 to 30 kA / m (more preferably 2 to 15 kA / m). It is preferable for the magnetic iron oxide to have the above-described magnetic properties in order to obtain a dry toner having good developability in which image density and fog are well balanced.
[0066]
Further, the dry toner of the present invention preferably contains 30 to 150 parts by mass of magnetic iron oxide based on 100 parts by mass of the binder resin. If the content of the magnetic iron oxide is less than 30 parts by mass, the dry toner transportability during development is insufficient, and unevenness occurs in the dry toner layer on the developer carrier, which may result in image unevenness. . Further, since the degree of exposure of the magnetic iron oxide to the toner surface is reduced, the dry toner is excessively charged so that an appropriate charge amount cannot be maintained, so that the image density may be reduced and fog may be increased. When the content of the magnetic iron oxide exceeds 150 parts by mass, there are a lot of toner particles having a large amount of the magnetic iron oxide exposed on the surface, so that charge leakage sites increase, and the dry toner cannot be sufficiently charged. It becomes inferior in developability.
[0067]
In the present invention, the magnetic iron oxide may be treated with a surface treating agent such as a silane coupling agent, a titanium coupling agent, titanate, aminosilane or an organosilicon compound.
[0068]
Preferred methods for measuring various physical property data relating to the magnetic iron oxide used in the present invention will be described in detail below.
[0069]
(1) Analysis of the outermost surface of magnetic iron oxide by X-ray photoelectron spectroscopy (XPS)
In the present invention, the composition ratio of the metal element on the outermost surface of the magnetic iron oxide can be determined by the following method. For example, magnetic iron oxide powder is pressurized at 9.807 MPa using a tablet molding machine to form a pellet. The pellet is fixed on a carbon sheet on a sample holder, and measured by, for example, a measuring device and a measuring method described below.
[0070]
Apparatus used: ULVAC-PHI 1600S X-ray photoelectron spectrometer Measurement conditions: X-ray source MgKα (400 W) analysis area 0.8 × 2.0 mm
[0071]
The atomic concentration on the surface of the magnetic iron oxide can be determined by estimating the surface atomic concentration from the measured peak intensity of each element and calculating the ratio of each atom from the estimated atomic concentration. The surface atom concentration was calculated using a relative sensitivity factor provided by ULVAC-PHI, and the surface metal atom concentration was calculated by converting the atom concentration of all metal atoms detected by the above measurement to 100%. A method of calculating the concentration of each metal atom can be used.
[0072]
(2) Determination of the amount of metal elements present in magnetic iron oxide
In the present invention, the content of metal elements other than iron in the magnetic iron oxide (based on the magnetic iron oxide) can be determined by the following method. For example, about 3 liters of deionized water is placed in a 5 liter beaker and heated in a water bath to 45 to 50 ° C. About 25 g of magnetic iron oxide slurried with about 400 ml of deionized water is added to the 5 liter beaker with the above deionized water while washing with about 300 ml of deionized water.
[0073]
Next, the temperature was about 50 ° C and the stirring speed was about 3.33s. ^-1 While maintaining the temperature, add a special grade hydrochloric acid or a mixed acid of hydrochloric acid and hydrofluoric acid to start dissolution. At this time, the hydrochloric acid aqueous solution is adjusted to about 3 mol / liter. Approximately 20 ml of the solution that has completely dissolved and become transparent is sampled, filtered through a 0.1 μm membrane filter, and the filtrate is collected. The filtrate is measured by plasma emission spectroscopy (ICP) to quantify the iron element and metal elements other than iron element. The content of the metal element other than the iron element based on the magnetic iron oxide is calculated by the following equation.
[0074]
(Equation 1)
Content (% by mass) of metal element based on magnetic iron oxide = {(c × d) / (e × 1000)} × 100
(Where c is the metal element concentration (mg / l) in the sample collected, d is the amount of sample collected (l), and e is the weight (g) of magnetic iron oxide.)
[0075]
(3) Bulk density of magnetic iron oxide
The bulk density of the magnetic iron oxide used in the present invention can be measured according to the pigment test method of JIS K 5101.
[0076]
(4) Number average particle size of magnetic iron oxide
The number average particle diameter of the magnetic iron oxide used in the present invention is obtained by randomly selecting 100 particles on a photograph from a transmission electron microscope photograph (magnification: 30,000 times), measuring the particle diameter, and calculating from the average value. Can be.
[0077]
(5) Specific surface area of magnetic iron oxide
The specific surface area of the magnetic iron oxide used in the present invention is determined by adsorbing nitrogen gas on the sample surface using a specific surface area measuring device Autosoap 1 (manufactured by Yuasa Ionics) according to the BET method, and using the BET multipoint method. Can be calculated.
[0078]
(6) Magnetic properties of magnetic iron oxide
The magnetic properties of the magnetic iron oxide used in the present invention can be measured under an external magnetic field of 795.8 kA / m using, for example, a “vibrating sample magnetometer VSM-3S-15” (manufactured by Toei Kogyo Co., Ltd.). it can.
[0079]
The dry toner of the present invention contains a binder resin. The present invention is characterized in that the binder resin contains a polyester resin as a main component. Here, “containing a polyester resin as a main component” means that the polyester resin is used in 60% by mass or more of the binder resin. As the auxiliary component, various resin compounds conventionally known as a binder resin can be used.
[0080]
As is known, the polyester resin is obtained by polycondensation between a dihydric or higher polyhydric alcohol and a dihydric or higher polyhydric organic acid, and generally has a polar carboxyl group at its terminal. In, the carboxyl group interacts with at least one element α selected from Mg, Cu, Zn, Ti and Al in the magnetic iron oxide to improve the dispersion state of the raw materials in the dry toner. That is, by using a polyester resin as the binder resin in the present invention, the dispersibility of the raw materials is synergistically enhanced, the distribution of the charge amount becomes uniform, and a dry toner having excellent developability even in a high-speed development system is obtained. You can do it.
[0081]
The polyester resin used in the present invention will be specifically described below. It is preferable that 45 to 55 mol% of the polyester resin is an alcohol component and 55 to 45 mol% of an acid component is an acid component.
[0082]
Examples of the alcohol component include ethylene glycol, propylene glycol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, diethylene glycol, triethylene glycol, 1,5-pentanediol, and 1,6-hexane. Diol, neopentyl glycol, 2-ethyl-1,3-hexanediol, hydrogenated bisphenol A, bisphenol derivative represented by the following formula (B); diols represented by the following formula (C); and glycerin, sorbit And trihydric or higher polyhydric alcohols such as sorbitan.
[0083]
Embedded image

[0084]
Embedded image

[0085]
Preferred examples of the acid component include carboxylic acids. Examples of the divalent carboxylic acid include benzenedicarboxylic acids such as phthalic acid, terephthalic acid, isophthalic acid, and phthalic anhydride or anhydrides thereof; succinic acid, adipine Alkyl dicarboxylic acids such as acid, sebacic acid and azelaic acid or anhydrides thereof; unsaturated dicarboxylic acids such as fumaric acid, maleic acid, citraconic acid and itaconic acid or anhydrides thereof; and trivalent or higher carboxylic acids. Examples of the acid include trimellitic acid, pyromellitic acid, benzophenonetetracarboxylic acid and anhydrides thereof.
[0086]
A particularly preferred alcohol component of the polyester resin is a bisphenol derivative represented by the formula (B), and an acidic component is phthalic acid, terephthalic acid, isophthalic acid or its anhydride, succinic acid, n-dodecenylsuccinic acid or its anhydride. And dicarboxylic acids such as fumaric acid, maleic acid and maleic anhydride; and trimellitic acid or its tricarboxylic acids as anhydrides.
[0087]
The use of a polyester resin obtained from these acid components and alcohol components as a binder resin makes it possible to achieve good fixing when the dry toner of the present invention is used in an image forming process using heat roller fixing in image fixing. It is preferable to realize the property and the excellent offset resistance.
[0088]
The acid value of the polyester resin used in the present invention is preferably 10 to 50 mgKOH / g, more preferably 10 to 45 mgKOH / g, and even more preferably 10 to 40 mgKOH / g. If the acid value of the polyester resin is greater than 50 mgKOH / g, the charging characteristics of the dry toner greatly depend on the environment, and the fluidity of the dry toner, the electrostatic adhesion, and the surface resistance of the dry toner (effect of adsorbed water) fluctuate. However, image quality may be degraded. When the acid value of the resin is less than 10 mgKOH / g, the interaction with at least one element α selected from Mg, Cu, Zn, Ti, and Al existing on the surface of the magnetic iron oxide is weakened. The dispersibility of the raw materials deteriorates, and the distribution of the charge amount of the dry toner spreads.Therefore, non-uniformly charged toner particles are present, and image quality such as image density uniformity and dot reproducibility may deteriorate. is there. The acid value of the polyester resin can be measured by a known method according to JIS K0070.
[0089]
In the present invention, as the binder resin, various resin compounds conventionally known as a binder resin can be used in combination with the polyester resin. Examples of such a resin compound include a vinyl resin, a phenol resin, and the like. Natural resin modified phenolic resin, natural resin modified maleic resin, acrylic resin, methacrylic resin, polyvinyl acetate, silicone resin, polyester resin, polyurethane, polyamide resin, furan resin, epoxy resin, xylene resin, polyvinyl butyral, terpene resin, coumaroindene Resins, petroleum resins and the like.
[0090]
Further, the glass transition temperature of the binder resin used in the present invention is preferably from 50 to 75 ° C, more preferably from 55 to 65 ° C. Further, the number average molecular weight (Mn) of the binder resin is preferably from 1,500 to 50,000, and more preferably from 2,000 to 20,000. Further, the weight average molecular weight (Mw) of the binder resin is preferably from 6,000 to 100,000, and more preferably from 10,000 to 90,000.
[0091]
If the glass transition temperature of the binder resin is lower than the above range, the storage stability of the dry toner may be insufficient, and if the glass transition temperature of the binder resin is higher than the above range, the fixability of the dry toner may be poor. May be sufficient. The glass transition temperature of the binder resin can be measured using a differential scanning calorimeter described later.
[0092]
The number average molecular weight and the weight average molecular weight of the binder resin can be measured by GPC (gel permeation chromatography) using THF (tetrahydrofuran) as a solvent. In the present invention, the molecular weight distribution of the toner and the binder resin by GPC using THF (tetrahydrofuran) as a solvent is measured under the following conditions.
[0093]
The sample is prepared as follows.
First, the sample is placed in THF, left for several hours, shaken sufficiently, mixed well with THF (until the sample is no longer united), and left still for 12 hours or more. At that time, the time of leaving in THF is set to 24 hours or more. After that, a GPC sample is passed through a sample processing filter (pore size: 0.2 to 0.5 μm, for example, Mishori Disc H-25-2 (manufactured by Tosoh Corporation)). The sample concentration is adjusted so that the resin component is 0.5 to 5 mg / ml.
[0094]
An RI (refractive index) detector is used as the detector. As the column, a combination of a plurality of commercially available polystyrene gel columns may be used. TSKgel G1000H (H _XL ), G2000H (H _XL ), G3000H (H _XL ), G4000H (H _XL ), G5000H (H _XL ), G6000H (H _XL ), G7000H (H _XL ) And TSKguard column.
[0095]
The column is stabilized in a heat chamber at 40 ° C., and THF is flowed through the column at this temperature as a solvent at a flow rate of 1 ml per minute, and about 100 μl of a THF sample solution is injected for measurement.
[0096]
In measuring the molecular weight of the sample, the molecular weight distribution of the sample is calculated from the relationship between the logarithmic value of a calibration curve prepared from several types of monodisperse polystyrene standard samples and the count value. As a standard polystyrene sample for preparing a calibration curve, for example, a molecular weight of 10 manufactured by Tosoh Corporation or Showa Denko ² -10 ⁷ It is appropriate to use at least about 10 standard polystyrene samples.
[0097]
The dry toner of the present invention preferably has at least one endothermic peak in a DSC curve at the time of temperature rise measured by a differential scanning calorimeter (DSC), and the endothermic peak exists at 60 to 120 ° C. This endothermic peak preferably exists at 65 to 120 ° C, and more preferably exists at 70 to 115 ° C. Two or more endothermic peaks may be present, but in that case, it is preferable to have at least one endothermic peak at 60 to 120 ° C.
[0098]
From the DSC curve at the time of temperature rise, the melting behavior of the dry toner due to heat absorption can be seen. When the endothermic peak exists at 60 to 120 ° C., the viscosity is sufficiently reduced when the dry toner is heated and melt-kneaded, and the magnetic iron oxide can be dispersed well, which is preferable for stabilizing the chargeability of the dry toner.
[0099]
As for the endothermic peak of the dry toner of the present invention, a desired endothermic peak can be obtained by selecting an appropriate wax and incorporating it into the dry toner. The wax capable of giving such an endothermic peak to a dry toner is easy to impart high hydrophobicity to the dry toner on the surface of the dry toner due to its melting property, and imparts the wettability characteristic of the present invention to the dry toner. It is effective in doing.
[0100]
In the present invention, the DSC curve of the dry toner is determined according to ASTM D3418-82 using a differential scanning calorimeter (DSC measuring apparatus) such as DSC-7 (manufactured by PerkinElmer) or DSC2920 (manufactured by TA Instruments Japan). Can be measured. As the DSC curve, a DSC curve measured when the temperature is raised once, lowered once, a pre-history is taken, and then the temperature is raised at a rate of 10 ° C./min. The peak accompanying the glass transition point of the binder resin can be distinguished by, for example, measuring only the binder resin.
[0101]
The dry toner of the present invention may contain various materials other than the binder resin and the magnetic iron oxide described above. Such other materials include the above-mentioned wax and charge control agent.
[0102]
Examples of the wax used in the present invention include various waxes, for example, aliphatic hydrocarbon waxes such as low molecular weight polyethylene, low molecular weight polypropylene, polyolefin copolymer, polyolefin wax, microcrystalline wax, paraffin wax, and Fischer-Tropsch wax. Oxides of aliphatic hydrocarbon waxes such as oxidized polyethylene wax; or block copolymers thereof; plant waxes such as candelilla wax, carnauba wax, wood wax, jojoba wax; beeswax, lanolin, whale wax Animal waxes such as ozokerite, ceresin, petrolactam; mineral waxes such as montanic acid ester wax and castor wax; waxes mainly containing aliphatic esters; deoxidized carnauba wax Such that de-oxidation and the like of part or all of the aliphatic esters.
[0103]
Examples of the wax include saturated linear fatty acids such as palmitic acid, stearic acid, montanic acid, and long-chain alkyl carboxylic acids having a longer-chain alkyl group; and unsaturated fatty acids such as brassic acid, eleostearic acid, and vinaric acid. Saturated fatty acids; saturated alcohols such as stearyl alcohol, eicosyl alcohol, behenyl alcohol, kaunavir alcohol, seryl alcohol, melisyl alcohol, or alkyl alcohols having longer alkyl groups; polyhydric alcohols such as sorbitol; linoleic acid amide; Aliphatic amides such as oleic acid amide and lauric acid amide; saturated such as methylene bisstearic acid amide, ethylenebiscapric acid amide, ethylenebislauric acid amide, hexamethylenebisstearic acid amide Aliphatic bisamides; unsaturated fatty acid amides such as ethylene bisoleic acid amide, hexamethylene bis oleic acid amide, N, N'-dioleyl adipamide, N, N'-dioleyl sebacic acid amide; m-xylene bis Aromatic bisamides such as stearamide and N, N'-distearylisophthalamide; aliphatic metal salts such as calcium stearate, calcium laurate, zinc stearate and magnesium stearate (commonly referred to as metal soaps) A wax obtained by grafting an aliphatic hydrocarbon wax with a vinyl monomer such as styrene or acrylic acid; a partially esterified product of a fatty acid such as behenic acid monoglyceride and a polyhydric alcohol; by hydrogenating a vegetable oil or fat With the resulting hydroxyl group Methyl ester compounds and the like that.
[0104]
In addition, these waxes are obtained by using a press sweating method, a solvent method, a recrystallization method, a vacuum distillation method, a supercritical gas extraction method or a liquid crystal precipitation method to sharpen the molecular weight distribution, or a low molecular weight solid fatty acid or a low molecular weight. Solid alcohols, low molecular weight solid compounds, and those from which other impurities have been removed are also preferably used.
[0105]
In the present invention, it is preferable to use a charge control agent by adding it. In the present invention, any of a negatively chargeable and a positively chargeable charge control agent can be used as the charge control agent.
[0106]
Specific examples of the negative charge control agent include monoazo dyes described in JP-B-41-20153, JP-B-42-27596, JP-B-44-6397, and JP-B-45-26478. Metal complexes, furthermore, nitrohumic acid and salts thereof described in JP-A-50-133838 or C.I. I. And dyes and pigments such as salicylic acid, naphthoic acid, and dicarboxylic acid described in JP-B-55-42752, JP-B-58-41508, JP-B-58-7384, and JP-B-59-7385. Examples include acid metal complexes such as Zn, Al, Co, Cr, Fe, and Zr, sulfonated copper phthalocyanine pigments, nitro groups, styrene oligomers into which halogens have been introduced, and chlorinated paraffins.
[0107]
In particular, an azo-based metal complex represented by the general formula (I) or a basic organic acid metal complex represented by the general formula (II), which has excellent dispersibility and is effective in stabilizing image density and reducing fog, preferable.
[0108]
Embedded image

[0109]
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[0110]
Among them, the azo-based metal complex represented by the above formula (I) is more preferable, and particularly, the azo-based iron complex represented by the following formula (III) or (IV) in which the central metal is Fe is most preferable.
[0111]
Embedded image

[0112]
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[0113]
The compounds of the following formulas (1) to (6), which are specific examples of the azo-based iron complex represented by the above formula (III), are shown.
[0114]
Embedded image

[0115]
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[0116]
Embedded image

[0117]
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[0118]
Embedded image

[0119]
Embedded image

In addition, compounds of the following formulas (7) to (13), which are specific examples of the charge control agents represented by the above formulas (I), (II) and (IV), are shown.
[0120]
Embedded image

[0121]
Embedded image

[0122]
Embedded image

[0123]
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[0124]
Embedded image

[0125]
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[0126]
Embedded image

[0127]
These metal complex compounds can be used alone or in combination of two or more.
[0128]
The amount of the charge control agent used varies depending on the type of the charge control agent, but is generally preferably 0.1 to 5.0 parts by mass per 100 parts by mass of the binder resin from the viewpoint of the charge amount of the toner.
[0129]
On the other hand, examples of the charge controlling agent for controlling the dry toner to have a positive charge include, for example, denatured products such as nigrosine and fatty acid metal salts, tributylbenzylammonium-1-hydroxy-4-naphthosulfonate, tetrabutylammonium tetrafluoroborate and the like. Quaternary ammonium salts, and onium salts thereof such as phosphonium salts and the like, and lake pigments thereof, triphenylmethane dyes and these lake pigments (as the lake-forming agent, phosphotungstic acid, phosphomolybdic acid, Metal salts of higher fatty acids such as phosphotungsten molybdic acid, tannic acid, lauric acid, gallic acid, ferricyanide, ferrocyanide; diorganotin oxides such as dibutyltin oxide, dioctyltin oxide, dicyclohexyltin oxide; Suzuboreto, dioctyl tin borate, diorgano tin borate such as dicyclohexyl tin borate; can be used in combination singly or in two or more.
[0130]
Further, in the dry toner of the present invention, it is preferable to add an external additive to toner particles composed of the above-mentioned materials such as the binder resin and magnetic iron oxide. Such external additives include, for example, inorganic fine powder and hydrophobic inorganic fine powder, and particularly preferred external additives include silica fine powder.
[0131]
As the silica fine powder used in the present invention, both a so-called dry method produced by vapor phase oxidation of a silicon halide compound or a so-called wet silica produced from water glass or the like and dry silica called fumed silica can be used. However, dry silica having few silanol groups on the surface and inside and having no production residue is preferable.
[0132]
Further, the silica fine powder used in the present invention is preferably subjected to a hydrophobic treatment. A preferred method for the hydrophobization treatment is a method of chemically treating with a hydrophobic compound such as an organosilicon compound which reacts or physically adsorbs with the silica fine powder. As a more preferable method, a method of treating a dry silica fine powder produced by vapor phase oxidation of a silicon halide compound with a silane compound or simultaneously with a silane compound, and treating with an organosilicon compound such as silicone oil. No.
[0133]
Examples of the silane compound used in the hydrophobic treatment include hexamethyldisilazane, trimethylsilane, trimethylchlorosilane, trimethylethoxysilane, dimethyldichlorosilane, methyltrichlorosilane, allyldimethylchlorosilane, allylphenyldichlorosilane, and benzyl. Dimethylchlorosilane, bromomethyldimethylchlorosilane, α-chloroethyltrichlorosilane, β-chloroethyltrichlorosilane, chloromethyldimethylchlorosilane, triorganosilanemercaptan, trimethylsilylmercaptan, triorganosilyl acrylate, vinyldimethylacetoxysilane, dimethylethoxy Silane, dimethyldimethoxysilane, diphenyldiethoxysilane, hexamethyldisiloxane, 1,3-divinyltetrame Tildisiloxane and 1,3-diphenyltetramethyldisiloxane are exemplified.
[0134]
Examples of the organosilicon compound include silicone oil. As a silicone oil, the viscosity at 25 ° C. is about 3 × 10 ^-5 ~ 1 × 10 ^-3 m ² / S, and preferred are, for example, dimethyl silicone oil, methyl hydrogen silicone oil, methyl phenyl silicone oil, α-methyl styrene modified silicone oil, chlorophenyl silicone oil, fluorine modified silicone oil and the like.
[0135]
As a method of hydrophobizing the surface of the external additive using silicone oil, for example, silica fine powder treated with a silane compound and silicone oil may be directly mixed using a mixer such as a Henschel mixer, or a base may be used. Alternatively, a method of injecting silicone oil into silica to be used may be used. Alternatively, a method of dissolving or dispersing a silicone oil in an appropriate solvent, mixing with a base silica fine powder, and removing the solvent may be used.
[0136]
The amount of the inorganic fine powder and the hydrophobic inorganic fine powder to be added varies depending on the kind and the intended function, but is 0.1 to 5 parts by mass (preferably 0.1 to 5 parts by mass) per 100 parts by mass of the toner particles. To 3 parts by mass).
[0137]
An external additive other than the inorganic fine powder such as silica fine powder may be added to the dry toner of the present invention as needed. Such other external additives include, for example, resin fine particles and inorganic fine particles that function as a charge assisting agent, a conductivity-imparting agent, a fluidity-imparting agent, a caking inhibitor, a lubricant, an abrasive, and the like.
[0138]
More specifically, for example, a lubricant such as a fluororesin, zinc stearate, and polyvinylidene fluoride, among which polyvinylidene fluoride is preferable. Alternatively, abrasives such as cerium oxide, silicon carbide, and strontium titanate, among which strontium titanate is preferable. Alternatively, for example, a fluidity-imparting agent such as titanium oxide and aluminum oxide, particularly a hydrophobic agent is preferable. A small amount of an anti-caking agent or a conductivity-imparting agent such as carbon black, zinc oxide, antimony oxide, or tin oxide, or white and black fine particles of opposite polarity can also be used as a developability improver.
[0139]
The dry toner of the present invention can be manufactured using conventional methods for producing toner particles used to develop an electrostatic image. As a material of the dry toner of the present invention, at least the binder resin and the magnetic iron oxide described above are used, and other materials such as a colorant, a wax, and a charge control agent are used as needed. More specifically, the dry toner of the present invention is prepared by thoroughly mixing these materials with a mixer such as a Henschel mixer or a ball mill, and then melting and kneading them using a hot kneader such as a roll, a kneader and an extruder. In addition, the resin can be produced by dispersing or dissolving a pigment or dye while kneading and kneading the resins to each other, solidifying it by cooling, pulverizing and classifying.
[0140]
For producing the dry toner of the present invention, a known apparatus can be used. For example, as a mixer, a Henschel mixer (manufactured by Mitsui Mining); a super mixer (manufactured by Kawata); a ribocorn (manufactured by Okawara Seisakusho); Nauta mixer, turbulizer, cyclomix (manufactured by Hosokawa Micron); spiral pin mixer (manufactured by Taiheiyo Kiko Co., Ltd.); and Ledige mixer (manufactured by Matsubo).
[0141]
Examples of the kneading machine include a KRC kneader (manufactured by Kurimoto Iron Works); a bus co-kneader (manufactured by Buss); a TEM type extruder (manufactured by Toshiba Machine Co., Ltd.); ); PCM kneader (Ikegai Iron Works); three roll mill, mixing roll mill, kneader (manufactured by Inoue Seisakusho); Kneedex (manufactured by Mitsui Mining); MS type pressure kneader, nider ruder (manufactured by Moriyama Seisakusho) ); Banbury mixer (manufactured by Kobe Steel Ltd.).
[0142]
Examples of the pulverizer include, for example, a counter jet mill, a micron jet, an innomizer (manufactured by Hosokawa Micron); an IDS-type mill, a PJM jet pulverizer (manufactured by Nippon Pneumatic), a cross jet mill (manufactured by Kurimoto Tekkosho); Max (manufactured by Nisso Engineering); SK Jet O Mill (manufactured by Seishin Enterprise); Kryptron (manufactured by Kawasaki Heavy Industries); turbo mill (manufactured by Turbo Kogyo); and super rotor (manufactured by Nisshin Engineering).
[0143]
Examples of the classifier include Classile, Micron Classifier, Spedd Classifier (manufactured by Seishin Enterprise Co., Ltd.); Turbo Classifier (manufactured by Nissin Engineering Co., Ltd.); Micron separator, Turboplex (ATP), TSP separator (Hosokawa Micron Co., Ltd.) Elbow Jet (manufactured by Nippon Steel Mining Co., Ltd.), Dispersion Separator (manufactured by Nippon Pneumatic Industries Co., Ltd.), and YM Micro Cut (manufactured by Yaskawa Corporation).
[0144]
Examples of the sieving apparatus used for sifting coarse particles and the like include Ultrasonic (manufactured by Koei Sangyo Co., Ltd.); Resona Seeb, Gyro Shifter (manufactured by Tokuju Kosakusho); Vibrasonic System (manufactured by Dalton); Shinto Kogyo Co., Ltd.); Turbo Screener (Turbo Kogyo Co., Ltd.); Micro Shifter (Makino Sangyo Co., Ltd.);
[0145]
The dry toner of the present invention can be produced by the known method and known apparatus as described above. As one of the production methods to be achieved, in the present invention, the use of a mechanical pulverizer as shown in FIGS. It is preferable from the viewpoint of improving efficiency.
[0146]
In this pulverizer, the temperature at the time of pulverization is adjusted, the polyester resin is used as a main component of the binder resin, and the magnetic iron oxide having the composition of the present invention is used, whereby the surface of the magnetic iron oxide on the surface of the dry toner is used. You can control the state.
Hereinafter, the mechanical pulverizer shown in FIGS. 2, 3 and 4 will be described.
[0147]
FIG. 2 is a schematic cross-sectional view of an example of a mechanical pulverizer used in producing the dry toner of the present invention, and FIG. 3 is a schematic cross-sectional view taken along the line DD ′ in FIG. FIG. 4 shows a perspective view of the rotor 314 shown in FIG. As shown in FIG. 2, the apparatus has a casing 313, a jacket 316, a distributor 220, and a rotating body mounted in the casing 313 and attached to a central rotating shaft 312, and has a large number of grooves on its surface. A rotor 314, a stator 310 provided with a large number of grooves on its surface and arranged at regular intervals on the outer periphery of the rotor 314, and a raw material input port 311 for introducing a raw material to be processed; And a raw material discharge port 302 for discharging the subsequent powder.
[0148]
Normally, when the pulverized raw material is pulverized by a mechanical pulverizer, the temperature of the spiral chamber 212 of the mechanical pulverizer and the temperature T2 of the rear chamber 320 are controlled, and pulverization is performed at a temperature equal to or lower than Tg of the resin. You have chosen a method that does not do quality. However, in the case of producing the dry toner of the present invention, in order to obtain the dry toner having the characteristics of the present invention, the temperature of the material outlet 302 is set to a temperature within a range of −25 to −5 ° C. with respect to Tg. In the actual pulverized state, the temperature is set to -20 to ± 0 ° C. of Tg, and the pulverization is performed so that the resin covers a part of the magnetic iron oxide present on the surface of the dry toner after the pulverization. As a result, the distribution of the raw materials on the surface of the dry toner is likely to have an appropriate value, and such pulverization is preferable for imparting the hydrophobic characteristic characteristic of the present invention to the dry toner.
[0149]
【Example】
Although the basic configuration and features of the present invention have been described above, the present invention will be specifically described below based on embodiments. However, the present invention is not limited by the following examples. The number of parts in the examples is parts by mass. Table 1 shows the binder resin used in the examples, Table 2 shows the wax, and Table 3 shows the magnetic iron oxide particles. The polyester resin as a binder resin described in Table 1 was synthesized by a dehydration condensation method. The method for producing the magnetic iron oxide particles is as follows.
[0150]
[Table 1]

[0151]
[Table 2]

[0152]
[Table 3]

[0153]
<Production example 1 of magnetic iron oxide particles>
After adding sodium silicate to the aqueous ferrous sulfate solution so that the content of silicon element with respect to iron element is 0.48%, a sodium hydroxide solution is mixed to prepare an aqueous solution containing ferrous hydroxide. did. Air was blown in while adjusting the pH of the aqueous solution to 10, and an oxidation reaction was performed at 80 to 90 ° C. to prepare a slurry liquid for generating seed crystals.
[0154]
When the formation of seed crystals was confirmed, an aqueous ferrous sulfate solution was appropriately added to the slurry solution, and while adjusting the pH of the slurry solution to 10, air was blown thereinto to proceed the oxidation reaction. In the meantime, zinc sulfate is added as appropriate while checking the progress rate of the reaction while checking the concentration of unreacted ferrous hydroxide, and further, the pH of the aqueous solution is adjusted to pH 9 at the beginning of the oxidation reaction, and to pH at the middle of the reaction. 8, the pH was adjusted stepwise to 6 at the latter stage of the reaction to control the distribution of metal elements in the magnetic iron oxide, thereby completing the oxidation reaction. The produced magnetic iron oxide particles were washed and filtered and dried by a conventional method. The primary particles of the obtained magnetic iron oxide particles are aggregated to form an aggregate. The aggregate was disintegrated to turn the magnetic iron oxide particles into primary particles, and the surface of the magnetic iron oxide particles was smoothed to obtain magnetic iron oxide 1 having the properties shown in Table 3.
[0155]
<Production Examples 2 to 5 of magnetic iron oxide particles>
Magnetic iron oxide 2 having the physical properties shown in Table 3 in the same manner as in Production Example 1 except that at least one of the amount of sodium silicate, the amount of the salt of the other element α, the time of addition, and the type was changed. ~ 5.
[0156]
<Production example 6 of magnetic iron oxide particles>
After adding sodium silicate to the aqueous ferrous sulfate solution so that the content of the silicon element with respect to the iron element is 0.40%, a sodium hydroxide solution is mixed to prepare an aqueous solution containing ferrous hydroxide. did. Air was blown while adjusting the pH of the aqueous solution to 10, and an oxidation reaction was performed at 80 to 90 ° C. to prepare a slurry liquid for generating seed crystals.
[0157]
When the formation of seed crystals was confirmed, an aqueous ferrous sulfate solution was appropriately added to the slurry solution, and while adjusting the pH of the slurry solution to 10, air was blown thereinto to proceed the oxidation reaction. In the meantime, while checking the progress rate of the reaction while checking the concentration of unreacted ferrous hydroxide, magnesium sulfate was appropriately added, and the pH of the aqueous solution was adjusted to 8 to complete the oxidation reaction. The resulting magnetic iron oxide particles were washed, filtered and dried by a conventional method. The primary particles of the obtained magnetic iron oxide particles are aggregated to form an aggregate. The aggregate was pulverized to turn the magnetic iron oxide particles into primary particles, and the surfaces of the magnetic iron oxide particles were smoothed to obtain magnetic iron oxide 6 having the properties shown in Table 3.
[0158]
<Example 1>
・ Binder resin A 100 parts by mass
・ 90 parts by mass of magnetic iron oxide
・ Wax d 4 mass parts
・ 2 parts by mass of charge control agent A represented by the following structural formula
The mixture was melt-kneaded with a twin-screw extruder heated to 140 ° C., and the cooled kneaded material was coarsely pulverized with a hammer mill, and the obtained coarsely pulverized material was finely pulverized by mechanical pulverization with a turbo mill (manufactured by Turbo Kogyo Co., Ltd.). It was pulverized, and the obtained finely pulverized powder was classified by a fixed wall type air classifier to obtain a classified powder. Further, the obtained classified powder is classified by a multi-segment classification device (Elbow jet classifier manufactured by Nippon Steel Mining Co., Ltd.) utilizing the Coanda effect, and ultrafine powder and coarse powder are simultaneously strictly classified and removed to obtain a weight average particle. Negatively chargeable toner particles having a diameter (D4) of 6.5 μm were obtained.
[0159]
Embedded image

[0160]
Based on 100 parts by mass of the obtained toner particles, methanol wettability 80% hydrophobically treated with 15 wt% of hexamethyldisilazane and 15 wt% of dimethyl silicone, and a BET specific surface area of 120 m ² The toner 1 was prepared by externally adding and mixing 1.3 parts by mass of a fine silica powder of 1.0 g / g and 1.0 parts by mass of strontium titanate. Table 4 shows the formulation and physical properties of the toner, and FIG. 1 shows a graph of the methanol concentration of the toner 1 with respect to the transmittance of light having a wavelength of 780 nm.
[0161]
This toner 1 was remodeled to a 1.5 times print speed with a commercially available LBP printer (LeserJet 4100, manufactured by HP) and used as an image-drawing tester at 15 ° C., 10% RH, 23 ° C. A print test of 10,000 sheets was performed in an environment of 60% RH and an environment of 30 ° C. and 80% RH. At this time, regarding the image density uniformity within the page, the image density uniformity within the page was determined based on the difference between the maximum value and the minimum value of the image density in the printout image under a high temperature and high humidity environment. .
[0162]
The image density was measured by measuring the reflection density of a 5-mm square image using an SPI filter with a Macbeth densitometer (manufactured by Macbeth). The fog was measured using a reflection densitometer (Reflectometer Model TC-6DS, manufactured by Tokyo Denshoku Co., Ltd.) before and after the image formation, and the worst value of the reflection density in the white background after the image formation was Ds, and the transfer before the image formation was Ds. The reflection average density of the material was set to Dr, Ds-Dr was obtained, and this was evaluated as the fog amount. A smaller value indicates that fog is suppressed. These evaluations were performed at the initial stage, at 10,000 sheets, and at each stage after being left outside the machine for one day.
[0163]
Regarding the evaluation of the rise of the charge amount, a horizontal line pattern in which 4-dot horizontal lines were printed at intervals of 176 dot spaces in an environment of 15 ° C. and 10% RH using the above-described image output tester was printed once every 10 seconds. An intermittent print test was performed to produce images at intervals of 1. The images of 5 mm square were sampled on the first, third, seventh, fifteenth, fifty-fifth, and 100th sheets, and the image density was measured. It can be said that the higher the image density is obtained from the earlier number of images, the earlier the rise of the charge amount.
[0164]
Regarding the evaluation of the image quality, using the above-described image output tester, an isolated 1 dot pattern of 1200 dpi was imaged in a normal temperature and normal humidity environment (23 ° C., 60% RH), and the image was observed with an optical microscope. The dot reproducibility was evaluated according to the following criteria.
A: There is no protrusion of the toner from the latent image, and the dots are completely reproduced.
B: The toner slightly protrudes from the latent image
C: Many toner protrusions from the latent image
[0165]
Regarding the tailing, a pattern in which a 4-dot horizontal line was printed in a 20-dot space was drawn using the above-described image-drawing tester, the number of trailing lines on the line was counted, and evaluated according to the following criteria. did.
A: No occurrence
B: Less than 3
C: 3 to less than 7
D: less than 7 to 15
E: 15 or more
[0166]
With respect to image scattering, an intermittent print test was performed using the above-described image output tester to output a horizontal line pattern in which 4-dot horizontal lines were printed at intervals of 176 dots at intervals of one sheet every 10 seconds. The image scattering of the 10,000th sheet was evaluated according to the following criteria.
A: Image with little image scattering even by magnifying observation
B: Scattering is observed by magnifying observation, but is not visible
C: Characters slightly blur due to scattering
D: The line thickness becomes uneven due to scattering
E: Due to scattering, some fine characters are crushed
[0167]
The obtained toner was allowed to stand in an environment of a temperature of 40 ° C. and a humidity of 90% RH for 30 days, and then was subjected to a normal environment (temperature of 23 ° C., humidity of 60% RH) for 500 days using the above-described image output tester. An image output test was performed. Table 6 shows the evaluation of the image density and fog on the 500th sheet at that time.
[0168]
<Examples 2 to 7, Comparative Example 1>
Toners 2 to 8 were prepared in the same manner as in Example 1 using the formulations shown in Table 4. The structural formulas of the charge control agents B and C in the table are shown below. A test similar to that of Example 1 was performed using these toners. The results are shown in Tables 5, 6, 7, 8, and 9.
[0169]
Embedded image

[0170]
Embedded image

[0171]
<Comparative Example 2>
A toner 9 was produced in the same manner as in Example 1 with the formulation shown in Table 4, except that the toner particles obtained after the classification were subjected to a process of instantaneously passing through hot air at 300 ° C. The same test as in Example 1 was performed using this toner 9. The results are shown in Tables 5, 6, 7, 8, and 9.
[0172]
<Comparative Example 3>
In the pulverizing step, a toner 10 was produced in the same manner as in Example 1 with the formulation shown in Table 4, except that a fine pulverizer by collision type air current pulverization was used. The same test as in Example 1 was performed using this toner 10. The results are shown in Tables 5, 6, 7, 8, and 9.
[0173]
[Table 4]

[0174]
[Table 5]

[0175]
[Table 6]

[0176]
[Table 7]

[0177]
[Table 8]

[0178]
[Table 9]

[0179]
【The invention's effect】
According to the present invention, in a toner having at least a binder resin and a magnetic iron oxide, the binder resin contains a polyester resin as a main component, and the magnetic iron oxide contains Si, Mg, Cu, Zn, Ti, and At least one element selected from Al, the content of Si in the magnetic iron oxide is 0.1 to 2.0% by mass based on the magnetic iron oxide, and the element in the magnetic iron oxide is The content of α is 0.1 to 4.0% by mass based on the magnetic iron oxide, and the atomic concentration of the element α on the outermost surface of the magnetic iron oxide measured by X-ray photoelectron spectroscopy is from 1.00 to 1.00. 7.00%, and when the wettability of the toner to a mixed solvent of methanol and water is measured by the transmittance of light having a wavelength of 780 nm, the methanol concentration when the transmittance is 80% is in the range of 45 to 65% by volume. At the inner, In addition, since the methanol concentration at a transmittance of 10% is in the range of 45 to 65% by volume, even in a high-speed development under a severe environment such as high temperature, high humidity and low temperature and low humidity, high developability can be obtained over a long period of use. Is maintained, a toner having a high charge quality, a high image quality, and good developability and environmental stability can be obtained.
[0180]
Further, in the present invention, when the wettability of the toner with respect to a mixed solvent of methanol and water is measured by the transmittance of light having a wavelength of 780 nm, the methanol concentration when the transmittance is 80% is within the range of 50 to 65% by volume. When the methanol concentration is within the range of 50 to 65% by volume when the transmittance is 10%, the charge amount of the dry toner is properly maintained, fog is prevented, and a good image having a high image density is obtained. It is even more effective in forming.
[0181]
Further, in the present invention, when at least one endothermic peak exists in the DSC curve at the time of temperature rise of the toner measured by the differential scanning calorimeter and the endothermic peak exists at 60 ° C. to 120 ° C., the magnetic iron oxide is contained in the toner particles. Is more effectively dispersed in the toner, and the chargeability of the dry toner is stabilized.
[0182]
Further, in the present invention, when the acid value of the polyester resin is 10 to 50 mgKOH / g, it is more effective in stabilizing the chargeability of the dry toner and forming a stable good image regardless of environmental changes. is there.
[0183]
Further, in the present invention, when the content of Si in the magnetic iron oxide is 0.3 to 1.8% by mass based on the magnetic iron oxide, it is more effective in appropriately and quickly charging the dry toner. is there.
[0184]
Further, in the present invention, when the content of the element α in the magnetic iron oxide is 0.1 to 2.0% by mass based on the magnetic iron oxide, the dry toner is sufficiently charged irrespective of environmental changes, and high image quality is obtained. Further, it is even more effective in forming a good image having a high image density.
[0185]
Further, in the present invention, when the element α is an element selected from Mg, Al, and Zn, the dry toner can be sufficiently charged regardless of environmental changes to form a good image with high image quality and high image density. It is even more effective.
[0186]
In the present invention, the atomic concentration of Si atoms on the outermost surface of the magnetic iron oxide measured by X-ray photoelectron spectroscopy is 12.5 to 17.5%, and the atomic concentration of Fe atoms is 70.00 to 85. When it is 00%, the balance between the electrical conductivity and the electrical resistance of the magnetic iron oxide is controlled, and the charge amount of the dry toner is controlled. As a result, high image density and high image quality developability can be obtained regardless of the environment. More effective.
[0187]
In the present invention, the ratio of the element α to the Si atom is 0.05 to 0.5, and the ratio of the Fe atom to the Si atom is the atomic concentration at the outermost surface of the magnetic iron oxide measured by X-ray photoelectron spectroscopy. Is 3.00 to 7.00 and the ratio of Fe atoms to the element α is 10.0 to 70.0, the balance between the electric conductivity and the electric resistance of the magnetic iron oxide is obtained, and the charge amount of the dry toner is reduced. Control, and as a result, is even more effective in obtaining high image density and high image quality developability regardless of the environment.
[0188]
Further, in the present invention, when the magnetic iron oxide is contained in an amount of 30 to 150 parts by mass with respect to 100 parts by mass of the binder resin, good chargeability and developability can be achieved at the same time. More effective.
[Brief description of the drawings]
FIG. 1 is a graph showing the transmittance of light of a wavelength of 780 nm with respect to the methanol concentration of toner 1 in Example 1 of the present invention.
FIG. 2 is a schematic sectional view of a mechanical pulverizer that can be used in producing the dry toner of the present invention.
FIG. 3 is a schematic cross-sectional view showing the mechanical pulverizer shown in FIG. 2 cut along a DD ′ plane.
FIG. 4 is a perspective view of the rotor shown in FIG. 2;
[Explanation of symbols]
212 spiral chamber
219 Pipe
220 distributor
222 Bag Filter
224 suction blower
229 Collection cyclone
301 mechanical crusher
310 Stator
311 Material input port
312 center rotation axis
313 Casing
314 rotor
315 Metering machine
316 jacket
320 Rear room

Claims (10)

In a toner having at least a binder resin and a magnetic iron oxide,
The binder resin contains a polyester resin as a main component,
The magnetic iron oxide contains Si and an element α that is at least one element selected from Mg, Cu, Zn, Ti, and Al,
The content of Si in the magnetic iron oxide is 0.1 to 2.0% by mass based on the magnetic iron oxide,
The content of the element α in the magnetic iron oxide is 0.1 to 4.0% by mass based on the magnetic iron oxide,
The atomic concentration of the element α at the outermost surface of the magnetic iron oxide measured by X-ray photoelectron spectroscopy is 1.00 to 7.00%,
When the wettability of the toner with respect to a mixed solvent of methanol and water is measured by the transmittance of light having a wavelength of 780 nm, when the transmittance is 80%, the methanol concentration is in the range of 45 to 65% by volume. A dry toner having a methanol concentration in the range of 45 to 65% by volume when is 10%. When the wettability of the toner with respect to a mixed solvent of methanol and water is measured by the transmittance of light having a wavelength of 780 nm, the methanol concentration is in the range of 50 to 65% by volume when the transmittance is 80%, and the transmittance is 2. The dry toner according to claim 1, wherein the methanol concentration is within a range of 50 to 65% by volume when is 10%. 3. The method according to claim 1, wherein at least one endothermic peak exists in a DSC curve of the toner at the time of temperature rise measured by a differential scanning calorimeter, and the endothermic peak exists at 60 to 120.degree. The dry toner according to claim 1. The dry toner according to any one of claims 1 to 3, wherein the polyester resin has an acid value of 10 to 50 mgKOH / g. The dry toner according to any one of claims 1 to 4, wherein the content of Si in the magnetic iron oxide is 0.3 to 1.8% by mass based on the magnetic iron oxide. 5. The dry toner according to claim 1, wherein the content of the element α in the magnetic iron oxide is 0.1 to 2.0% by mass based on the magnetic iron oxide. 6. 7. The dry toner according to claim 6, wherein the element α is an element selected from Mg, Al, and Zn. The atomic concentration of Si atoms at the outermost surface of the magnetic iron oxide measured by X-ray photoelectron spectroscopy is 12.5 to 17.5%, and the atomic concentration of Fe atoms is 70.00 to 85.00%. The dry toner according to any one of claims 1 to 4, wherein: At the atomic concentration on the outermost surface of the magnetic iron oxide measured by X-ray photoelectron spectroscopy, the ratio of element α to Si atoms is 0.05 to 0.5, and the ratio of Fe atoms to Si atoms is 3.00. The dry toner according to any one of claims 1 to 4, wherein the ratio of Fe atoms to the element α is 10.0 to 70.0. The dry toner according to any one of claims 1 to 9, wherein the magnetic iron oxide is contained in an amount of 30 to 150 parts by mass with respect to 100 parts by mass of the binder resin.

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