JP3869969B2 - Toner, image forming method, and apparatus unit - Google Patents

Description

（但し、Ｒ：炭素数１〜３のアルキル基、
Ｒ’：アルキル、ハロゲン変性アルキル、フェニル、変性フェニル等のシリコーンオイル変性基、
Ｒ”：炭素数１〜３のアルキル又は、アルコキシ基を示すものとする。）
【００２１】
上記一般式（Ｉ）の具体例としては、例えば、ジメチルシリコーンオイル、アルキル変性シリコーンオイル、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挙げられる。
【００２２】
本発明においては、シリコーンオイルとして、下記一般式（II）で表される構造をもつ変性シリコーンオイルを使用することもできる。
【化２】

【００２３】
上記一般式（II）中、Ｒ1 、Ｒ6 は、水素原子、アルキル基、アリール基又はアルコキシ基を表わし、Ｒ2 は、アルキレン基又はフェニレン基を表わし、Ｒ3 は、含窒素複素環をその構造に有する化合物を表わし、Ｒ4 及びＲ5 は、水素原子、アルキル基、アリール基を表わす。又、Ｒ2 はなくてもよい。但し、上記のアルキル基、アリール基アルキレン基、フェニレン基は、アミンを有してもよいし、又、帯電性を損ねない範囲でハロゲン等の置換基を有してもよい。又、ｍは１以上の数であり、ｎ、ｋは０を含む正の数である。但し、ｎ＋ｋは１以上の正の数である。
【００２４】
上記構造中最も好ましい構造は窒素原子を含む側鎖中の窒素原子の数が１か２であるものである。窒素を有する不飽和複素環として、下記にその構造の一例を挙げる。
【化３】

【００２５】
窒素を有する飽和複素環として、下記にその構造の一例を挙げる。
【化４】

但し、本発明は何ら上記化合物例に拘束されるものではないが、好ましくは５員環又は６員環の複素環を持つものが好ましい。
【００２６】
誘導体としては、上記化合物群に、炭化水素基、ハロゲン基、アミノ基、ビニル基、メルカプト基、メタクリル基、グリシドキシ基、ウレイド基等を導入した誘導体が例示される。これらは１種、又は、２種以上用いてもよい。
【００２７】
又、本発明に用いられるシリコーンワニスとしては、例えば、メチルシリコーンワニス、フェニルメチルシリコーンワニス等を挙げることができ、特に、本発明においては、メチルシリコーンワニスを用いることが好ましい。メチルシリコーンワニスは、下記構造で示されるＴ³¹単位、Ｄ³¹単位、Ｍ³¹単位よりなるポリマーであり、且つＴ³¹単位を多量に含む三次元ポリマーである。
【００２８】
【化５】

【００２９】
メチルシリコーンワニス、又は、フェニルメチルシリコーンワニスは、具体的には、下記構造式（Ａ）で示されるような化学構造を有する物質である。
【化６】

【００３０】
上記シリコーンワニスにおいて、特にＴ³¹単位は、良好な熱硬化性を付与し、三次元網状構造とするために有効な単位である。シリコーンワニス中に、上記Ｔ³¹単位が、１０〜９０モル％、特に３０〜８０モル％の範囲で含まれるものを使用することが好ましい。
【００３１】
このようなシリコーンワニスは、分子鎖の末端若しくは側鎖に水酸基を有しており、この水酸基の脱水縮合反応によって硬化することとなる。この硬化反応を促進させるために用いることができる硬化促進剤としては、例えば、亜鉛、鉛、コバルト、スズ等の脂肪酸塩；トリエタノールアミン、ブチルアミン等のアミン類等を挙げることができる。このうち特にアミン類を好ましく用いることができる。
【００３２】
上記の如きシリコーンワニスをアミノ変性シリコーンワニスとするためには、前記、Ｔ³¹単位、Ｄ³¹単位、Ｍ³¹単位中に存在する一部のメチル基或いはフェニル基を、アミノ基を有する基に置換すればよい。アミノ基を有する基としては、例えば、下記構造式で示されるものを挙げることができるが、これらに限定されるものではない。
【化７】

【００３３】
これらのシリコーンオイル又はシリコーンワニスによる原体シリカの疎水化処理方法としては、公知技術が使用できる。例えば、シリカ微粉体とシリコーンオイル又はシリコーンワニスとを混合機を用いて混合する方法、シリカ微粉体中にシリコーンオイル又はシリコーンワニスを噴霧器を用い噴霧する方法、溶剤中にシリコーンオイル又はシリコーンワニスを溶解させた後、シリカ微粉体を混合する方法等が挙げられる。
【００３４】
上記シリコーンオイル又はシリコーンワニスとしては、２５℃における粘度が１０〜２，０００センチストークスのものを、更には、３０〜１５，００センチストークスのものを使用することが好ましい。即ち、その粘度が１０センチストークス未満のものを使用した場合には、融着レベルが低下する。一方、２，０００センチストークスを超える場合も、融着レベルが低下する。
【００３５】
シリコーンオイル又はシリコーンワニスの粘度測定は、ビスコテスターＶＴ５００（ハーケ社製）を用いて行った。いくつかあるＶＴ５００用粘度センサーの一つを選び（任意）、そのセンサー用の測定セルに測定試料を入れて測定する。装置上に表示された粘度（ｐａｓ）は、ｃｓ（センチストークス）に換算した。
【００３６】
本発明で使用する疎水性シリカ微粉体の処理形態としては、シランカップリング剤等や、或いは、シリコーンオイル又はシリコーンワニス単独で処理される場合と、両者を組合わせて処理される場合がある。その中での好ましい処理形態としては、先ず、シランカップリング処理剤で処理した後、シリコーンオイル又はシリコーンワニスで処理することが挙げられる。その中でも特に、ヘキサメチルシラザンで処理した後、シリコーンオイルで処理する形態が好ましい。
【００３７】
シランカップリング剤による処理方法としては、ケイ酸微粉体を撹拌等により、グラウド状としたものに、気化したシランカップリング剤を反応させる乾式処理、又は、ケイ酸微粉体を溶媒中に分散させてシランカップリング剤を滴下反応させる湿式処理等の方法を挙げることができる。特に好ましく用いられる方法は、シランカップリング剤を水蒸気の存在下、グラウド状にしたシリカ微粉体と接触させて反応させる乾式法によるものである。
【００３８】
シリコーンオイル及び／又はシリコーンワニスによる原体シリカ表面の疎水化処理方法には、公知の技術が用いられ、例えば、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させてもよいし、原体シリカへシリコーンオイルを噴霧する方法によってもよい。或いは、適当な溶剤に、シリコーンオイルを溶解或いは分散せしめた後、ベースのシリカ微粉体とを混合した後、溶剤を除去して作製してもよい。
【００３９】
本発明で使用する疎水性シリカ微粉体の作製に良好に用いられる方法としては、シランカップリング剤で処理後、シリコーンオイルを噴霧した後、２００℃以上で加熱処理する方法が好適に用いられる。この際、シランカップリング剤を、原体シリカ１００重量部に対して、５乃至６０重量部、更に好ましくは、１０乃至５０重量部の範囲で添加して処理するとよい。５重量部より少ない場合には、ドラム融着が発生し易くなり、６０重量部よりも多い場合には、製造上困難になる場合が生ある。
【００４０】
シリコーンオイル又はシリコーンワニスは、原体シリカ又は処理シリカ１００重量部に対して５乃至４０重量部、より好ましくは、７乃至３５重量部の範囲で使用する。５重量部より少ない場合は、ドラム融着が発生し易くなり、４０重量部よりも多い場合には、画像流れ等の弊害が生じ易くなる。
【００４１】
更に、本発明で使用する疎水性シリカ微粉体は、その最終的なカーボン含有量が３．０乃至１３．０重量％の範囲内にあるもの、より好ましくは、４．５乃至１２．０重量％の範囲内にあるものを使用するとよい。尚、本発明においては、かかるカーボンの含有量の分析には、微量炭素分析装置（堀場社製 ＥＭＩＡ−１００型）を用いて行った。
【００４２】
次に、本発明のトナーの第二の構成要件は、その重量平均粒径（Ｄ４）が３．５乃至６．５μｍであり、粒径１０．１μｍ以上の粒子の含有量が３．０体積％以下であることである。
本発明のトナーは、その大前提として、高画質、所謂飛び散りのない、潜像に忠実な文字等の形成を可能とすることを目的としており、このためにはトナーの粒度分布が上記に規定する範囲内にあることを要する。先ず本発明のトナーは、Ｄ４が３．５以上６．５μｍ以下であることを要する。Ｄ４が６．５μｍより大きい場合は、文字の飛び散りが悪化して好ましくない。一方、Ｄ４が３．５μｍより小さい場合は、トナーの粒子間の凝集性が上昇し、カブリの弊害が発生しやすくなる。
更に、粒径１０．１μｍ以上の粒子の含有量が３．０体積％以下でなければならない。粒径１０．１μｍ以上の粒子の含有量が３．０体積％より多い場合は、先述の文字の飛び散りの悪化が顕著となるからである。
しかし、この様な粒度分布を有するトナーを使用した場合には、確かに先述の高画質が達成されるが、トナーの粒径が小さいためにトナーの感光体への付着力が上昇し、ドラム融着問題が顕在化するために、高画質の達成とドラム融着抑制の問題を同時に解決することが困難であった。しかしながら、本発明のトナーは、トナーの感光体への付着力に影響を与える要素であるトナーの疎水特性を前述の如く特定の条件を満たすようにコントロールしたことから、高画質の達成とドラム融着発生の抑制を同時に解決可能とするものである。
【００４３】
本発明においてトナーの重量平均粒径の測定は、通常用いられるコールターカウンターＴＡ−II（コールター社製）を用いて行うが、コールターマルチサイダー（コールター社製）を用いることも可能であるが、下記の方法によって測定した。
電解質水溶液は１級塩化ナトリウムを用いて１％ＮａＣｌ水溶液を調製する。例えば、ＩＳＯＴＯＮ Ｒ−II（コールターサイエンティフィックジャパン社製）が使用できる。測定法としては、前記電解質水溶液１００〜１５０ｍｌ中に分散剤として界面活性剤剤、好ましくはアルキルベンゼンスルフォン酸塩を０．１〜５ｍｌ加え、更に測定対象の試料を２〜２０ｍｇ加える。試料を懸濁した電解質水溶液は超音波分散器で約１〜３分間分散処理を行い、前記測定装置によりアパーチャーとして１００μｍアパーチャーを用いて、２．００μｍ以上のトナーの体積、個数を測定して、これらの値から体積分布と個数分布とを算出した。
【００４４】
そして、体積分布から重量基準の重量平均粒径（Ｄ４）（各チャンネルの中央値をチャンネル毎の代表値とする）を求め、更に体積分布から体積基準の粒径を求め、１０．１μｍ以上の粒子の割合を求めた。
チャンネルとしては、２．００〜２．５２μｍ未満：２．５２〜３．１７μｍ未満：３．１７〜４．００μｍ未満：４．００〜５．０４μｍ未満：５．０４〜６．３５μｍ未満：６．３５〜８．００μｍ未満：８．００〜１０．０８μｍ未満：１０．０８〜１２．７０μｍ未満：１２．７０〜１６．００μｍ未満：１６．００〜２０．２０μｍ未満：２０．２０〜２５．４０μｍ未満：２５．４０〜３２．００μｍ未満：３２．００〜４０．３０μｍ未満の１３チャンネルを用いた。
【００４５】
本発明のトナーにおいては、先に述べたように、トナーの外添剤として特定の疎水特性を有する疎水性シリカ微粉体を使用することが好ましいが、この場合の疎水性シリカ微粉体の粒径としては、個数平均粒子径（長さ平均）が０．１μｍ以下、更には、５乃至５０ｎｍのものを使用することが好ましい。又、本発明で用いる高疎水性シリカ微粉体は、窒素吸着法で測定した場合の比表面積が、１０乃至５５０ｍ²／ｇ、更には５０乃至５００ｍ²／ｇであることが好ましい。
【００４６】
更に、本発明で使用する疎水性シリカ微粉体としては、その帯電量が、鉄粉に対して−３０乃至−４００μｇ／ｇの負摩擦帯電性を有するものを使用することが好ましく、更には、鉄粉に対して−５０乃至−３００μｇ／ｇのものを使用することが好ましい。
【００４７】
又、本発明で用いる上記のような特性を有する高疎水性シリカ微粉体は、トナー粒子１００重量部に対して、０．６〜３．０重量部の割合で添加されて使用されることが好ましい。即ち、添加量が０．６重量部より少ない場合は、充分な画像濃度を得ることが困難であり、３．０重量部より少ない場合には、ドラム融着等の弊害が生じるので好ましくない。より好ましくは、２．０重量部より少ない場合に、本発明の目的を好適に達成することが可能となる。
【００４８】
本発明のトナーにおいては、その所期の目的をより充分に解決するために、上記に説明した疎水性シリカ微粉体の他に、更に、第２の無機微粉体を添加することが望ましい。第２の無機微粉体としては、例えば、酸化鉄、酸化クロム、チタン酸カルシウム、チタン酸ストロンチウム、チタン酸ケイ素、チタン酸バリウム、チタン酸マグネシウム、酸化セリウム、酸化ジルコニウム、酸化アルミニウム、酸化チタン、酸化亜鉛、酸化カルシウム等が挙げられる。本発明においては、これらの中でも特に、複合酸化物を用いることが好ましく、例えば、チタン酸ストロンチウム微粉体、チタン酸カルシウム微粉体、或いはチタン酸ケイ素微粉体を用いることが好ましい。
【００４９】
又、これらの第２の無機微粉体としては、その一次粒子の個数平均粒径が、０．１２〜３．０μｍのものを使用することが好ましい。一次粒子の個数平均粒径が０．１２μｍより小さい場合は、画像流れ防止効果に対して好ましくない影響があり、一方、３．０μｍよりも大きい場合は、ドラム表面へ傷をつけ易くなるので好ましくない。
【００５０】
上記の本発明で使用する疎水性シリカ微粉体や、必要に応じて添加させる上記した第２の無機微粒子の個数平均粒径とは、以下の方法で測定した値である。
電子顕微鏡Ｓ−８００（日立製作所社製）を用いて、先ず、本発明のトナーを構成する疎水性シリカ微粉体については１０，０００〜２０，０００倍、第２の無機微粒子については１，０００〜２０，０００倍の倍率で写真撮影を行う。次に、撮影された微粒子から、疎水性シリカ微粉体については０．００１μｍ以上の粒子を、第２の無機微粒子については０．００５μｍ以上の粒子を、夫々ランダムに１００乃至２００個を抽出し、ノギス等の測定機器を用いて夫々の直径を測定し、平均化したものを各無機微粒子の個数平均粒径とする。
【００５１】
本発明のトナーへの第２の無機微粉体の添加量としては、本発明の課題をより良好に解決するために、トナー粒子１００重量部に対して、０．３乃至５．０重量部程度を添加することが好ましい。即ち、０．３重量部より少ない場合は、画像流れが発生し易くなり好ましくなく、５．０重量部より多い場合は、ドラム融着が発生し易くなるので好ましくない。
【００５２】
本発明のトナーは、少なくとも上記したような特性を有する疎水性シリカ微粉体とトナー粒子とから構成されるが、トナー粒子としては、一般に用いられている構成のトナー粒子が用いられる。トナー粒子は、通常、結着樹脂及び着色剤等を有する着色樹脂組成物からなるが、以下、これについて説明する。
先ず、トナー粒子に用いられる結着樹脂の種類としては、例えば、ポリスチレン；ポリ−ｐ−クロルスチレン、ポリビニルトルエン等のスチレン置換体の単重合体；スチレン−ｐ−クロルスチレン共重合体、スチレン−ビニルトルエン共重合体、スチレン−ビニルナフタリン共重合体、スチレン−アクリル酸エステル共重合体、スチレン−メタクリル酸エステル共重合体、スチレン−α−クロルメタクリル酸メチル共重合体、スチレン−アクリロニトリル共重合体、スチレン−ビニルメチルエーテル共重合体、スチレン−ビニルエチルエーテル共重合体、スチレン−ビニルメチルケトン共重合体、スチレン−ブタジエン共重合体、スチレン−イソプレン共重合体、スチレン−アクリロニトリル−インデン共重合体等のスチレン系共重合体；ポリ塩化ビニル、フェノール樹脂、天然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、クマロンインデン樹脂、石油系樹脂等が使用できる。また、架橋されたスチレン系樹脂も好ましい結着樹脂である。これらの中でも、本発明の特定の疎水特性を有するトナーに好適に用いられるのは、スチレン系の結着樹脂である。
【００５３】
スチレン系共重合体のスチレンモノマーに対するコモノマーとしては、例えば、アクリル酸、アクリル酸メチル、アクリル酸エチル、アクリル酸ブチル、アクリル酸ドデシル、アクリル酸オクチル、アクリル酸−２−エチルヘキシル、アクリル酸フェニル、メタクリル酸、メタクリル酸メチル、メタクリル酸エチル、メタクリル酸ブチル、メタクリル酸オクチル、アクリロニトリル、メタクリロニトリル、アクリルアミド等のような二重結合を有するモノカルボン酸もしくはその置換体；例えば、マレイン酸、マレイン酸ブチル、マレイン酸メチル、マレイン酸ジメチル等のような二重結合を有するジカルボン酸及びその置換体；例えば、塩化ビニル、酢酸ビニル、安息香酸ビニル等のようなビニルエステル類；例えば、エチレン、プロピレン、ブチレン等のようなエチレン系オレフィン類；例えば、ビニルメチルケトン、ビニルヘキシルケトン等のようなビニルケトン類；例えば、ビニルメチルエーテル、ビニルエチルエーテル、ビニルイソブチルエーテル等のようなビニルエーテル類等のビニル単量体が単独もしくは組み合わせて用いられる。
【００５４】
ここで架橋剤としては、主として２個以上の重合可能な二重結合を有する化合物が用いられ、例えば、ジビニルベンゼン、ジビニルナフタレン等のような芳香族ジビニル化合物；例えば、エチレングリコールジアクリレート、エチレングリコールジメタクリレート、１，３−ブタンジオールジメタクリレート等のような二重結合を２個有するカルボン酸エステル；ジビニルアニリン、ジビニルエーテル、ジビニルスルフィド、ジビニルスルホン等のジビニル化合物；及び３個以上のビニル基を有する化合物；が単独もしくは混合物として使用できる。
【００５５】
更に、本発明のトナーを構成する場合に用いられるスチレン系の結着樹脂としては、ゲルパーミエーションクロマトグラフィー（ＧＰＣ）において、少なくとも０．５×１０⁴〜５×１０⁴及び１．０×１０⁵〜５．０×１０⁶の領域にメインピーク及びサブピークを有するものが好ましい。更に、このようなスチレン系樹脂の中でも、テトラヒドロフラン（ＴＨＦ）不溶分を有さないものが好ましく、又、重量平均分子量（Ｍｗ）が、１．５×１０⁵〜３．５×１０⁵、より好ましくは、１．８×１０⁵〜３．２×１０⁵であるものを用いることが好ましい。
【００５６】
本発明のトナーにおいては、トナー粒子中にワックスが含有されていることが好ましい。この際に使用するワックスとしては、パラフィンワックス及びその誘導体、マイクロクリスタリンワックス及びその誘導体、フィッシャートロプシュワックス及びその誘導体、ポリオレフィンワックス及びその誘導体、カルナバワックス及びその誘導体等が挙げられるが、誘導体には酸化物や、ビニル系モノマーとのブロック共重合体、グラフト変性物を含む。
【００５７】
特に、本発明で好ましく用いられるワックスとしては、一般式Ｒ−Ｙ（式中、Ｒは、炭化水素基を示し、Ｙは水酸基、カルボキシル基、アルキルエーテル基、エステル基又はスルホニル基を示す。）で表されるものが挙げられる。更に、上記一般式Ｒ−Ｙで示されるワックスの中でも、ゲルパーミエーションクロマトグラフィー（ＧＰＣ）による重量平均分子量（Ｍｗ）が３，０００以下であるものを好ましく用いることができる。
【００５８】
上記のような要件を満足する具体的な化合物としては、下記（Ａ）、（Ｂ）及び（Ｃ）等が挙げられる。
【化８】

【００５９】
上記化合物（Ｂ）及び（Ｃ）は化合物（Ａ）の誘導体であり、主鎖は直鎖状の飽和炭化水素である。上記化合物（Ａ）から誘導される化合物であれば、上記例に示したもの以外のものでも使用できる。本発明で使用し得る特に好ましいワックスとしては、ＣＨ₃(ＣＨ₂)_nＯＨ（ｎ＝２０〜３００）で表される長鎖アルキルアルコール、及びこれらを主成分とする混合物が挙げられる。
【００６０】
本発明のトナーを構成するトナー粒子中には荷電制御剤が含まれていてもよいが、荷電制御剤として有機金属化合物を用いることが好ましい。更に、有機金属化合物の中でも、特に気化性や昇華性に富む有機化合物を配位子や対イオンとして含有するものが有用である。
【００６１】
このような金属錯体としては、次に示した一般式で表わされるアゾ系金属錯体がある。
【化９】

【００６２】
上記式中、式中Ｍは配位中心金属を表し、配位数６のＣｒ、Ｃｏ、Ｎｉ、Ｍｎ、Ｆｅ、Ａｌ、Ｔｉ、Ｓｃ、Ｖ等を示す。Ａｒは、フェニル基、ナフチル基の如きアリール基であり、置換基を有していてもよい。この場合の置換基としては、ニトロ基、ハロゲン基、カルボキシル基、アニリド基及び、炭素数１〜１８のアルキル基やアルコキシル基がある。Ｘ、Ｘ’、Ｙ、Ｙ’は、−Ｏ−、−ＣＯ−、−ＮＨ−、−ＮＲ−（Ｒは炭素数１〜４のアルキル基）である。Ａ^＋は、水素イオン、ナトリウムイオン、カリウムイオン、アンモニウムイオン又は、脂肪族アンモニウムイオン或いは、これらいずれかの混合イオンを示す。）
【００６３】
下記に、本発明のトナーを形成する場合に良好に利用できる上記一般式で表わされるアゾ系金属錯体の具体例（ａ）〜（ｃ）を示す。
【化１０】

【００６４】
本発明のトナーは磁性トナーとすることもできるが、この場合に好適に用いられる磁性体としては、鉄、コバルト、ニッケル、銅、マグネシウム、マンガン、アルミニウム、ケイ素等の元素を含む磁性金属酸化物等が挙げられる。中でも、四三酸化鉄、γ−酸化鉄等の酸化鉄を主成分とするものが好ましい。更に、トナーの流動性向上及び帯電性コントロールの観点から、ケイ素原子を含有するものであることが好ましい。特に、磁性トナー粒子が小径になると、トナー粒子母体の流動性が低下するため、前述した本発明で使用する疎水性シリカ微粉体を添加するだけでは充分な流動性が得られず、良好な帯電性を得られなくなり、本発明の目的を達成することが困難な場合が生ずる。ケイ素原子の含有量は磁性体に対して０．２乃至２．０重量％含有されていることが好ましく、０．２重量％より少ない場合は充分な流動性が得られず、文字シャープ性の悪化、ベタ黒濃度薄等の弊害が生ずる。２．０重量％より多く含有させると、特に高温高湿環境において画像濃度低下を生じ易くなる。ケイ素原子の含有量は、より好ましくは０．３乃至１．７重量％の場合である。特に、磁性体の表面にケイ素原子が０．０５乃至０．５重量％存在する場合がより好ましい。
【００６５】
ケイ素原子は水溶性ケイ素化合物の形で磁性体生成時に添加してもよく、磁性体の生成、ろ過、乾燥後、ケイ酸化合物の形で添加し、ミックスマーラー等で表面に固着させてもよい。これら磁性体の粒子としては、窒素吸着法によるＢＥＴ比表面積が、好ましくは、２乃至３０ｍ²／ｇ、特に３乃至２８ｍ²／ｇのものを使用することが好ましい。更に、モース硬度が５乃至７の磁性粒子を用いることが好ましい。
【００６６】
又、使用する磁性粒子の形状としては、８面体、６面体、球形、針状、鱗片状等があるが、８面体、６面体、球形、不定型等の異方性の少ないものが好ましい。特に、磁性粒子の球形度Ψが０．８以上であることが、画像濃度を高める上で好ましい。磁性粒子の平均粒径としては、０．０５乃至１．０μｍが好ましく、更に好ましくは、０．１乃至０．６μｍ、特に、０．１乃至０．４μｍが好ましい。
【００６７】
本発明のトナーにおけるこれらの磁性体の含有量は、結着樹脂１００重量部に対して３０乃至２００重量部、好ましくは６０乃至２００重量部、更には、７０乃至１５０重量部がよい。３０重量部未満では搬送性の点で劣り、現像剤担持体上のトナー層にムラが生じて画像ムラとなる傾向があり、更に、磁性トナーのトリボの上昇に起因する画像濃度低下が生じ易い傾向がある。一方、磁性体の含有量が２００重量部を超えると、定着性が低下する可能性がある。
【００６８】
本発明のトナーを作製する方法としては、公知の方法が用いられる。例えば、トナー原料として、結着樹脂、及び、ワックス、金属塩或いはは金属錯体、着色剤としての顔料、染料、又は磁性体、必要に応じて荷電制御剤、その他の添加剤等を適宜に用い、原料中の樹脂類を、ヘンシェルミキサー、ボールミル等の混合器により充分混合してから、加熱ロール、ニーダー、エクストルーダーの如き熱混練機を用いて溶融混練して樹脂類をお互いに相溶せしめ、この中に、金属化合物、顔料、染料、磁性体等を分散又は溶解せしめ、冷却固化後、粉砕、分級を行なってトナー粒子を得る。上記分級工程においては、生産効率上、多分割分級機を用いて所望の粒度分布を有するトナー粒子を得ることが好ましい。
【００６９】
更に、上記分級工程で得られたトナー粒子１００重量部に対して、疎水性シリカ微粉体を含む外添剤を、約０．６〜３．０重量部の範囲で添加し、混合させて本発明のトナーを得る。かかる外添混合工程に使用する装置の好ましいものとしては、ＦＭ−５００、−３００、−７５、−１０等の名称を有する三井三池化工機製のヘンシェルミキサーを挙げることができる。
【００７０】
次に、図３に、上記で説明したような構成を有する本発明のトナーを好適に用いることのできる画像形成装置の一例の概略を示したが、それに基づき本発明の画像形成方法について説明する。
図中の１は回転ドラム状の静電潜像担持体であり、その周囲には一次帯電装置である帯電ローラー（帯電部材）２、露光光学系３、トナー担持体５を有する現像装置４、転写装置９、クリーニング装置１１が配置されている。
【００７１】
この画像形成装置においては、先ず、一次帯電装置としての帯電ローラー２によって感光体である静電潜像担持体１の表面が一様に帯電され、次に、露光光学系３により像露光されて静電潜像担持体１の表面に静電潜像が形成される。
ここで、本発明の画像形成方法において好適に用いられる静電潜像担持体の帯電部材としては、静電荷像担持体に接触配置される接触帯電部材が挙げられるが、その形状については特に限定されるものではなく、図３に示したようなローラー状であってもよいし、ブレード状やブラシ状等、いずれのものでもよい。これらの帯電部材に印加される電圧は、直流電圧は絶対値で２００〜２，０００Ｖであることが好ましく、交流電圧は、ピーク間電圧が４００〜４，０００Ｖで、周波数が２００〜３，０００Ｈｚであることが好ましい。
【００７２】
次いで、磁石を内包する（不図示）トナー担持体５の表面上に、トナー層厚規制部材６によりトナーコート層が形成され、トナー担持体５によって現像部に担持・搬送される。本発明の画像形成方法においては、この際に先に説明した本発明のトナーを用いることを特徴とする。そして、現像部おいて、静電潜像担持体１の導電性基体とトナー担持体５との間のバイアス印加手段８により、交互バイアス、パルスバイアス及び／又は直流バイアスを印加しながら、静電潜像担持体１上に形成されている静電潜像を、本発明のトナーによって現像してトナー画像が形成される。
【００７３】
次に、上記のようにして現像されたトナー画像は、転写紙Ｐを搬送し転写装置としての転写ローラー９及び電圧印加手段１０により、転写紙Ｐの背面からトナーと逆極性の電荷が加えられて、転写紙Ｐ上へと静電転写される。更に、トナー画像が転写された転写紙Ｐを、加熱加圧ローラー定着器１２を透過させることによって、転写紙Ｐ上に定着画像が得られる。
上記転写工程後の静電潜像担持体上に残留したトナーは、クリーニング装置としてのクリーニングブレード１１により除去されて、クリーナー１４に回収され、その後、再び一次帯電以下の工程が繰り返されて画像形成が行なわれる。
【００７４】
上述の感光ドラムの如き静電荷像担持体や現像装置、クリーニング手段等の構成要素のうち、複数のものを装置ユニットとして一体に結合してプロセスカートリッジを構成し、このプロセスカートリッジを装置本体に対して着脱可能に構成することもできる。例えば、帯電部材及び現像装置を感光体ドラムとともに一体に支持してプロセスカートリッジを形成し、装置本体に着脱自在の単一ユニットとし、装置本体のレール等の案内手段を用いて着脱自在の構成にしてもよい。この時、上記のプロセスカートリッジの方にクリーニング手段を伴って構成してもよい。
【００７５】
図４は、本発明の装置ユニットであるプロセスカートリッジの一実施例を示したものである。本実施例では、現像装置４、ドラム状の静電荷像担持体（感光体ドラム）１、クリーニングブレード１１を有するクリーナ１４、一次帯電部材２を一体としたプロセスカートリッジ１６が例示される。このようなプロセスカートリッジにおいては、現像装置４の磁性トナー１３が無くなった時に、新たなカートリッジと交換される。
図４に示した例では、現像装置４のトナー容器１５中には磁性トナー１３が収納されており、現像時には、感光体ドラム１とトナー担持体としての現像スリーブ５との間に所定の電界が形成され、現像工程が好適に実施されるためには、感光体ドラム１と現像スリーブ５との間の距離は非常に大切である。
【００７６】
図４に示したプロセスカートリッジにおいて、現像装置４は磁性トナー１３を収容するためのトナー容器１５と、トナー容器１５内の磁性トナー１３をトナー容器１５から静電荷像担持体１に対向している現像域へと担持・搬送する現像スリーブ５と、現像スリーブ５にて担持され、現像域へと搬送される磁性トナーを所定厚さに規制し、現像スリーブ上にトナー薄層を形成するためのトナー層厚規制部材としての弾性ブレード６とを有する。
【００７７】
前記現像スリーブ５は、任意の構造とし得る。通常は、図示しない磁石を内蔵した非磁性の現像スリーブ５から構成される。現像スリーブ５は、図示されているように円筒状の回転体とすることもできる。循環移動するベルト状とすることも可能である。その材質としては、通常、アルミニウムやＳＵＳが用いられることが好ましい。
【００７８】
又、前記弾性ブレード６は、ウレタンゴム、シリコーンゴム、ＮＢＲの如きゴム弾性体；リン青銅、ステンレス板の如き金属弾性体；ポリエチレンテレフタレート、高密度ポリエチレン等の如き樹脂弾性体で形成された弾性板で構成される。弾性ブレード６は、その部材自体の持つ弾性により現像スリーブ５に当接され、鉄の如き剛体から成るブレード支持部材にてトナー容器１５に固定される。弾性ブレード６は、線圧５〜８０ｇ／ｃｍで現像スリーブ５の回転方向に対してカウンター方向に当接することが好ましい。このような弾性ブレード６の代わりに、鉄の如き磁性ドクターブレードを用いることも可能である。
【００７９】
上記した例では、一次帯電手段として、接触帯電部材として帯電ローラー２を用いて説明したが、本発明はこれに限定されず、帯電ブレード、帯電ブラシの如き接触帯電手段でもよい。この接触帯電部材は、帯電によるオゾンの発生が少ない点で好ましい。転写手段としては、転写ローラー９を用いて説明したが、転写ブレードの如き接触帯電手段でもよく、更に、非接触のコロナ転写手段でもよい。しかしながら、こちらも転写によるオゾンの発生が少ない点で接触帯電手段の方が好ましい。
【００８０】
【実施例】
以下、実施例及び比較例により本発明を具体的に説明するが、これは本発明をなんら限定するものではない。尚、「部」は重量部を意味する。
疎水性シリカ微粉体の製造及びその物性
先ず、本発明の実施例及び比較例で使用する疎水性シリカ微粉体Ｉ〜VIを下記のようにして調製した。
（シリカＩ）
比表面積２００ｍ²／ｇの原体シリカ１００部に対し、ヘキサメチルジシラザン１６部を水蒸気の存在下において反応させた。その後、処理後の疎水性シリカ微粉体１００部に対して、粘度１００ｃｓのシリコーンオイル１０部を噴霧処理した後、２５０℃で加熱して疎水処理されたシリカＩを得た。表１に、シリカＩについての製造条件と、透過率以外の物性値を示した。又、表２に、シリカＩについてのメタノール滴下透過率曲線における透過率（％）のデータを示した。
【００８１】
（シリカII）
シリコーンオイルの処理量を１５部にした以外は、シリカＩと同様の方法でシリカIIを得た。シリカＩと同様に、製造条件、物性値及び透過率等を表１及び表２に示した。
【００８２】
（シリカIII）
ヘキサメチルジシラザン添加量を２４部にした以外は、シリカＩと同様の方法でシリカIIIを得た。シリカＩの場合と同様に、製造条件、物性値及び透過率等を表１及び表２に示した。
【００８３】
（シリカIV）
ヘキサメチルジシラザン添加量を３２部にした以外は、シリカＩと同様の方法でシリカIVを得た。シリカＩの場合と同様に、製造条件、物性値及び透過率等を表１及び表２に示した。
【００８４】
（シリカＶ）
シリコーンオイルの処理量を１５部にする以外は、シリカIVと同様の方法でシリカＶを得た。シリカＩの場合と同様に、製造条件、物性値及び透過率等を表１及び表２に示した。
【００８５】
（シリカVI）
比表面積２００ｍ²／ｇの原体シリカ１００部に対して、ヘキサメチルジシラザンを噴霧反応させた。その後、処理後の疎水性シリカ微粉体１００部に対して、ｎ−ヘキサンに溶解させた粘度１００ｃｓのシリコーンオイル１０部を噴霧処理した後、３５０℃で加熱して、シリカVIを得た。シリカＩの場合と同様に、製造条件、物性値及び透過率等を表１及び表２に示した。
【００８６】
【表１】
表１：疎水性シリカ微粉体製造上の特徴及び物性

【００８７】
【表２】
表２：メタノール滴下透過率曲線から読み取ったシリカ微粉体の疎水特性の測定用サンプル中のメタノール含有量(体積％)に対する透過率（％）の値

【００８８】
トナーの作成及び評価結果
＜実施例１＞
・結着樹脂（スチレン系樹脂、ＧＰＣにおいて、分子量１．５万にメインピー
ク、分子量６５万にサブピークを有する） １００重量部
・磁性体（Ｆｅ₃Ｏ₄） １００重量部
・荷電制御剤（モノアゾ鉄錯体） ２重量部
・ワックス（高分子アルコール系ワックス） ５重量部
上記混合物を、１３０℃に加熱された２軸エクストルーダーで溶融混練し、冷却した混練物をハンマーミルで粗粉砕し、粗粉砕物をジェットミルで微粉砕し、更に、エルボージェット分級機で重量平均径（Ｄ４）５．８μｍのトナー粒子を得た。
【００８９】
上記で得られたトナー粒子１００部に、比表面積１１０（ｍ²／ｇ）の疎水性シリカ微粉体Ｉを１．５部加えて、ヘンシェルミキサーで混合して本実施例のトナーを得た。表３に、得られたトナーについてのエタノール滴下透過率曲線から読み取った透過率（％）のデータを示した。
【００９０】
図４に示すプロセスカートリッジを装着した図３に示した構成の画像形成装置を用い、以下の画像評価方法に従い評価を行った。その際、プロセスカートリッジとしてヒューレットパッカード社製「ＬＢＰ−５Ｌ」を用いた。そして、この「ＬＪ−５Ｌ」のプロセスカートリッジに上記で得た本実施例のトナーをセットして画像形成を行なった。得られた結果を表４に示した。
上記「ＬＪ−５Ｌ」は、一次帯電部材として、感光体表面に当接する接触帯電ローラーを用い、この帯電ローラーに、直流電圧：−６２５Ｖ、交流電圧：ピーク間電圧１．８ｋＶ、周波数３７０Ｈｚの帯電電圧を印加して、感光体に一次帯電を行うものである。又、転写ローラーには、２．３ｋＶの電圧を印加して転写を行った。
【００９１】
（１）ドラム融着の評価
画像面積比率約３％の画像を、高温・高湿環境（３３．０℃、９５％ＲＨ）下で２，５００枚連続してプリントアウトした後、Ａ４サイズの記録紙全面にベタ黒画像を形成し、ベタ黒画像上に生ずる白点の発生の程度を評価した。評価は、下記の基準によって行なった。
Ａ：Ａ４サイズの記録紙上に白点が全く発生しない。
ＡＢ：ＡとＢの中間レベル。
Ｂ：ＡとＣの中間レベル。
Ｃ：Ａ４サイズの記録紙上に白点が１０点程度みられる。
Ｄ：ＣとＥの中間レベル。
Ｅ：Ａ４サイズの記録紙上に白点が１００点以上見られる。
【００９２】
（２）画像流れ
画像面積比率約３％の画像を高温・高湿環境（３３．０℃、９５％ＲＨ）下で２，５００枚連続プリントアウトした後、２，５００枚後の画像流れの程度により評価した。本評価においては、経験上、画像流れが発生し易いタルクを填料として用いている紙（３３．０℃、９５％ＲＨで吸湿量１０％にしたもの）を評価用紙とした。尚、紙の吸湿量は、Ｉｎｆｒａｒｅｄ Ｅｎｇｉｎｅｅｒｉｎｇ製ＭＯＩＳＴＲＥＸ ＭＸ ５０００を用いて測定した。評価は、下記の基準によって行なった。
Ａ：画像流れが全く発生しない。
ＡＢ：ＡとＢの中間レベル。
Ｂ：ＡとＣの中間レベル。
Ｃ：画像流れが発生しているが、文字が何か判別できる。
Ｄ：ＣとＥの中間レベル。
Ｅ：画像流れが発生し、文字が何か判別できない。
【００９３】
（３）ドラム削れ
画像面積比率約３％の画像を低温・低湿環境（１５．０℃、１０％ＲＨ）下で３，０００枚連続プリントアウトした後、ドラムの削れ量を測定し、１，０００枚の値に換算した値を用いた。測定は、フィッシャー社製の膜厚測定機を用いて行った。
【００９４】
（４）転写効率
常温常湿環境（２５．０℃、６０％ＲＨ）において、ドラム上に形成されたベタ黒画像から転写効率を調査した。転写効率の値は、転写後の転写紙上に存する単位面積あたりのトナー量に転写後のドラム上に残った単位面積あたりのトナー量を加えた値で、転写後の転写紙上に存する単位面積あたりのトナー量を割った値である。
【００９５】
＜実施例２＞
シリカ微粉体IIを用いる以外は、実施例１と同様にして本実施例のトナーを得た。表３に、得られたトナーについてのエタノール滴下透過率曲線から読み取った透過率（％）のデータを示した。又、実施例１と同様の方法で評価し、その結果を表４に示した。
【００９６】
＜実施例３＞
シリカ微粉体IIIを用いる以外は、実施例１と同様にして本実施例のトナーを得た。表３に、得られたトナーについてのエタノール滴下透過率曲線における透過率（％）のデータを示した。又、実施例１と同様の方法で評価し、その結果を表４に示した。
【００９７】
＜実施例４＞
シリカ微粉体IVを用いる以外は、実施例１と同様にして本実施例のトナーを得た。表３に、得られたトナーについてのエタノール滴下透過率曲線から読み取った透過率（％）のデータを示し、図１に、エタノール滴下透過率曲線を示した。又、実施例１と同様の方法で評価し、その結果を表４に示した。
【００９８】
＜実施例５＞
シリカ微粉体Ｖを用いる以外は、実施例１と同様にして本実施例のトナーを得た。表３に、得られたトナーについてのエタノール滴下透過率曲線から読み取った透過率（％）のデータを示した。又、実施例１と同様の方法で評価し、その結果を表４に示した。
【００９９】
＜比較例１＞
本発明で規定する特有の疎水特性を有さない疎水性シリカ微粉体であるシリカVIを使用する以外は、実施例１と同様にして、本比較例のトナーを得た。表３に、得られたトナーについてのエタノール滴下透過率曲線から読み取った透過率（％）のデータを示し、図２に、エタノール滴下透過率曲線を示した。又、実施例１と同様の方法で評価し、その結果を表４に示した。
【０１００】
＜比較例２＞
結着樹脂がスチレン系樹脂で、ＧＰＣによる分子量分布で、６，５００にメインピークを有するのみで、他にピークを有さず、ゲル分を４０％有するものを使用し、ワックスとしてはポリプロピレン４部を使用する以外は、実施例１と同様にして、Ｄ４が７．２μｍのトナー粒子を得た。疎水性シリカVIをトナー粒子１００部に対して、１．２部加えてトナーを得た。表３に、得られたトナーについてのエタノール滴下透過率曲線から読み取った透過率（％）のデータを示した。又、実施例１と同様の方法で評価し、その結果を表４に示した。
【０１０１】
【表３】
表３：エタノール滴下透過率曲線から読み取ったトナーの疎水特性の測定用サンプル中のエタノール含有量（体積％）に対する透過率（％）の値

【０１０２】
【表４】
表４：評価結果

【０１０３】
【発明の効果】
以上説明したように、本発明によれば、特有の疎水特性を有する超微粒径トナーとすることで、画像形成に使用した場合に、高温高湿下においてもドラム融着及び画像流れの発生を防止でき、しかも転写効率が高く、ドラム削れ量が減少できるのでドラムの長寿命化を達成できる優れた特性のトナーが提供される。
【図面の簡単な説明】
【図１】実施例４のトナーについて得られたエタノール滴下透過率曲線である。
【図２】比較例４のトナーについて得られたエタノール滴下透過率曲線である。
【図３】本発明の画像形成方法を適用した画像形成装置の一例の概略図である。
【図４】本発明のプロセスカートリッジの一実施例を示す説明図である。
【符号の説明】
１：潜像担持体
２：一次帯電装置
３：露光光学系
４：現像装置
５：トナー担持体
６：トナー層厚規制部材
７：トナー攪拌手段
８：現像バイアス電源
９：転写装置
１０：転写電流発生装置
１１：クリーニング手段
１２：定着装置
１３：トナー
１４：クリーナー
１５：トナー容器
１６：プロセスカートリッジ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a toner for developing an electrostatic latent image latent image such as an electrophotographic method, an image forming method using the toner, and an apparatus unit having the toner.
[0002]
[Prior art]
In recent years, demand for image forming apparatuses using electrophotographic technology such as copying machines and laser printers has been diversified, and images with higher definition and higher image quality have been demanded. Accordingly, toner used for image formation tends to be used with a finer particle diameter than before. Furthermore, today, in consideration of environmental problems, a method of charging a photosensitive member with a contact charging member without using a corona charger that generates ozone has been adopted.
However, in the case of a method in which the photosensitive member is charged by the contact charging member, particularly in a high temperature / high humidity (humidity) environment, toner fine particles that are not cleaned well by the cleaning member may be pressed by the charging member. In addition, a phenomenon (hereinafter referred to as “drum fusion”) that adheres to the surface of the photosensitive drum, which is an electrostatic charge image carrier, is likely to occur. On the other hand, if the function of the cleaning member is strengthened to enhance the cleaning characteristics, the amount of scraping of the drum increases, and as a result, adverse effects such as drum potential changes are likely to occur. Therefore, as one of the fundamental countermeasures for these problems, it is desired to improve the transfer efficiency of the toner image and to keep the toner as little as possible on the drum.
[0003]
As a means for improving the transfer rate of toner and solving the above problems, an additive (hereinafter referred to as “external additive”) is applied to the surface of the toner particles, which has been studied from this viewpoint. Examples of the external additive include the following. For example, as described in JP-A-61-287174, a hydrophobic silica fine powder obtained by oil treatment after treatment with a coupling agent comprising hexamethyldisilazane (HMDS), or JP-A-5 There are hydrophobic silica fine powders described in Japanese Patent No. 805844, and it has been found that the use of these materials can improve to some extent. However, due to the recent demand for higher image quality, the toner particle size has been further reduced, and the above phenomenon has become more prominent. All of these problems can be solved by using hydrophobic silica fine powder that has been subjected to the above treatment. It is a difficult situation to do.
[0004]
Furthermore, when the toner is used in a high-temperature and high-humidity environment, the electrostatic latent image formed on the surface of the photoreceptor is remarkably formed by a low electrical resistance substance formed by paper dust, ozone, etc. generated during printing. The phenomenon of damage (hereinafter referred to as “image flow”) tends to occur. As means for preventing this image flow, JP-A-60-3260 discloses a toner containing inorganic fine powders having two types of BET specific surface areas. However, as a result of studies by the present inventors, for the purpose of preventing drum fusion, for example, hydrophobicity obtained by oil treatment after HMDS treatment disclosed in the above-mentioned JP-A-61-287171. When silica fine powder is used as an external additive for the above toner, satisfactory image flow prevention effect cannot be obtained, and drum fusion prevention and image flow suppression effects cannot be achieved simultaneously. I understood.
[0005]
Another problem is that the above-described toner having a high image flow prevention effect is usually a toner that easily scrapes the drum. When such a toner is used, the life of the drum is reduced. Problems arise. Further, in this case, the surface of the drum is rough, resulting in a decrease in transfer efficiency, which causes problems such as drum cleaning failure and charging roller contamination.
[0006]
[Problems to be solved by the invention]
Accordingly, an object of the present invention is to provide a toner that does not cause drum fusion under all circumstances.
Another object of the present invention is to provide a toner that does not cause image flow even in a high temperature and high humidity environment.
Another object of the present invention is to provide a toner having good transfer efficiency.
Another object of the present invention is to provide a toner capable of suppressing drum scraping and extending the life of the drum.
Furthermore, an object of the present invention is to provide an image forming method capable of obtaining an excellent effect by using the toner.
It is a further object of the present invention to provide an apparatus unit that can provide an excellent effect of being filled with the toner.
[0007]
[Means for Solving the Problems]
  The above object is achieved by the present invention described below. That is, according to the present invention, in a toner having at least toner particles and hydrophobic silica fine powder, the hydrophobic characteristics of the toner are precisely weighed in a container holding 70 ml of a water-containing ethanol solution composed of 25% by volume of ethanol and 75% by volume of water. Ethanol was added to a measurement sample solution prepared by adding 0.025 g of toner to 0.5 ml / min. When represented by an ethanol drop transmittance curve prepared by measuring transmittance with light having a wavelength of 780 nm while adding at a dropping rate of
  (1)The transmittance of the measurement sample solution at an ethanol content of 25 to 37% by volume is 90% or more, and
  (2)The transmittance of the measurement sample solution at an ethanol content of 38% by volume is 85% or more, and
  (3)The transmittance of the sample solution for measurement at an ethanol content of 40% by volume is 60% or more,
The toner has a weight average particle diameter (D4) of 3.5 to 6.5 μm and a content of particles having a particle diameter of 10.1 μm or more is 3.0% by volume or less.
[0008]
Further, according to the present invention, an electrostatic charge image is formed on the electrostatic charge image bearing member, the electrostatic charge image is developed by a developing means using toner, and a toner image is formed on the electrostatic charge image bearing member. In the image forming method of transferring a toner image onto a transfer material with or without an intermediate transfer member, and further fixing the toner image on the transfer material with a fixing means to obtain a fixed image, the toner for developing an electrostatic charge image Is an image forming method.
[0009]
Furthermore, the present invention provides an apparatus unit in which at least the electrostatic charge image carrier and the developing unit are integrally provided and configured to be detachable from the image forming apparatus main body, wherein the developing unit includes toner particles and hydrophobic silica. An apparatus unit comprising a storage unit for storing toner having at least fine powder, wherein the toner stored in the storage unit is the toner for developing an electrostatic image.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in more detail with reference to preferred embodiments of the present invention.
The present inventors pay attention to the surface characteristics of the toner as a powder, and if the toner has a certain wetting characteristic (hydrophobic characteristic) with respect to a specific solvent, it prevents drum fusing and prevents image flow. The present inventors have found that the problems of the present invention can be solved at the same time, such as being able to achieve the suppression effect at the same time. That is, in the present invention, an ethanol drop transmittance curve under a specific condition is used for measuring the hydrophobic characteristics of the toner surface, and the toner is in a state where the curve satisfies a specific requirement. Achieve superior effects of the invention.
[0011]
The above transmission curve shows a sample solution for measuring the hydrophobic properties of a toner by adding a specific amount of toner to a water-containing ethanol solution of a specific concentration, and adding the ethanol solution to this at a constant drop rate. In such a case, the change in the transmittance of the sample solution is measured by using an apparatus configured to be able to continuously measure. The toner having the hydrophobic characteristics in which the transmittance curve thus obtained satisfies the specific requirements is the toner of the present invention, and the drum fusion problem and the image flow which are the intended objects of the present invention are included. A toner that can solve the problem at the same time is identified.
The wettability of the toner with respect to the ethanol solution varies depending on the types of raw materials constituting the toner. For example, it varies depending on the types and properties of the binder resin, the release agent, the external additive and the like. Further, in the magnetic toner, it is considered that the magnetic toner changes depending on the exposed state of the magnetic material on the toner particle surface. In particular, it is considered that the fine particles of silica used as the binder resin and the external additive have a great influence on the wettability of the toner defined in the present invention. Therefore, when the toner is manufactured, the toner of the present invention can be easily obtained by appropriately designing these types and properties.
[0012]
First, the ethanol dropping transmittance curve for specifying the hydrophobic characteristics of the toner, which is the first constituent requirement of the toner of the present invention, will be described.
In the toner of the present invention, the ethanol dropping transmittance curve obtained by the method for measuring the hydrophobic property of a specific toner needs to have a transmittance of 90% or more at an ethanol content of 37 vol%. If the transmittance in this case is less than 90%, drum fusion or the like deteriorates, which is not preferable. Further, the transmittance at an ethanol content of 38% by volume is required to be 85% or more. Even when the transmittance in this case is less than 85%, the transfer efficiency and the like are deteriorated. Furthermore, in order to solve the problem of the present invention more reliably, the transmittance at an ethanol content of 40% by volume is required to be 60% or more. That is, when it is less than 60%, the effect of preventing drum scraping is reduced, which is not preferable.
[0013]
In the present invention, as described above, the hydrophobic characteristics are selected using an ethanol dropping transmittance curve in order to specify a toner that can obtain an excellent effect. Specifically, as the measuring apparatus, for example, Using a powder wettability tester WET-100P manufactured by Reska Co., Ltd., an ethanol dropping transmittance curve measured under the following conditions and procedures is used.
First, a water-containing ethanol solution composed of 25% by volume of ethanol and 75% by volume of water is placed in a 70 ml container, and 0.025 g of the sample toner is precisely weighed and added thereto, and the hydrophobic characteristics of the toner are measured. Prepare a sample solution for use. Next, ethanol was added to the measurement sample solution at 0.5 ml / min. The transmittance is measured with light having a wavelength of 780 nm while continuously adding at a dropping rate of 1 to prepare an ethanol dropping transmittance curve as shown in FIG. In this case, ethanol was used as the titration solvent because the reduction in transmittance that may occur due to elution of dyes, pigments, charge control agents and the like contained in the toner was taken into consideration.
[0014]
  The toner of the present invention is configured to have at least toner particles and hydrophobic silica fine powder. As described above, particularly for the hydrophobic characteristics of the toner, the silica fine powder constituting the toner is used. Since the hydrophobic properties of the body have an influence, the present invention described aboveofToner sparseWaterIn order to realize the properties, it is effective to control the hydrophobic characteristics of the silica fine powder. In the toner of the present invention, for example, hydrophobic silica fine powder having the following hydrophobic characteristics is preferably used.
  That is, the methanol drop permeability curve for the hydrophobic silica fine powder,rearWhen measured and expressed as described, its hydrophobic properties are
  (1)The transmittance of the sample liquid for measurement at a methanol content of 60 to 72% by volume is 95% or more, and
  (2)Hydrophobic silica fine powder having a transmittance of 90% or more at a methanol content of 74% by volume is preferably used.
  More preferably, a hydrophobic silica fine powder having a transmittance of 90% or more for the measurement sample solution at a methanol content of 75% by volume is suitable. Furthermore, a hydrophobic silica fine powder having a transmittance of 85% or more for the measurement sample solution at a methanol content of 76% by volume is preferably used.
[0015]
That is, when the hydrophobic characteristics of the hydrophobic silica fine powder are specified by a methanol drop transmittance curve, the transmittance at a methanol content of 60 to 72% by volume is 95% or more and the permeability at a methanol content of 74% by volume. If a hydrophobic silica fine powder whose rate does not exceed 90% is used as an external toner additive, all of drum fusing, image flow, and transfer efficiency tend to deteriorate, and the amount of drum scraping may increase. I found out.
The measurement method of the methanol dropping transmittance curve for measuring the hydrophobic characteristics of the hydrophobic silica fine powder will be described. That is, a water-containing methanol solution composed of 60% by volume of methanol and 40% by volume of water is placed in a 70 ml container, 0.06 g of hydrophobic silica fine powder is precisely weighed and added thereto, and the hydrophobic silica fine powder is added. A sample solution for measuring hydrophobic characteristics was prepared, and methanol was added to 1.3 ml / min. A methanol dropping transmittance curve is prepared by measuring the transmittance with light having a wavelength of 780 nm while continuously adding at a dropping speed of. In the case of preparing a methanol dropping transmittance curve, it can be obtained using a powder wettability tester WET-100P manufactured by Reska Co., Ltd. in the same manner as in the case of creating an ethanol dropping transmittance curve in the hydrophobic characteristics of the toner. That's fine.
In the present invention, when measuring the hydrophobic properties of hydrophobic silica fine powder, methanol was used as a titration solvent, and the silica hydrophobic properties were conventionally used in consideration of the fact that methanol solutions were conventionally used. This is because the difference in hydrophobic properties between the hydrophobic silica and the hydrophobic silica used in the present invention can be clarified.
[0016]
A hydrophobic silica fine powder having a specific hydrophobic property suitable as a constituent material of the toner of the present invention specified as described above will be described. First, as the raw material before the hydrophobization treatment, the following silicic acid fine powder (hereinafter referred to as raw silica) can be used favorably.
That is, the silicate fine powder used as the raw silica is a dry process produced by vapor phase oxidation of a silicon halide or so-called dry silica called fumed silica, so-called wet silica produced from water glass or the like. Both silicas can be used, but in particular there are few silanol groups on the surface and inside the silica fine powder, and Na₂O, SO^3-It is preferable to use dry silica with little production residue such as. In dry silica, it is also possible to obtain composite fine powders of silica and other metal oxides in the production process by using other metal halogen compounds such as aluminum chloride and titanium chloride together with silicon halogen compounds. However, the raw silica used in the present invention is also included.
[0017]
In the toner of the present invention, as an external additive, a fine silica fine powder as described above is used as a base, and a hydrophobic silica fine powder whose surface is uniformly and highly hydrophobized is used. Hereinafter, the hydrophobizing agent used in this case will be described.
An organosilicon compound is preferably used as a hydrophobizing agent for hydrophobizing the above-described base silica. As the organosilicon compound used in this case, for example, silicone oil and / or silane coupling agent can be preferably used.
[0018]
Examples of the silane coupling agent include hexamethyldisilazane, trimethylsilane, trimethylchlorosilane, trimethylethoxysilane, dimethyldichlorosilane, methyltrichlorosilane, allyldimethylchlorosilane, allylphenyldichlorosilane, benzyldimethylchlorosilane, Bromomethyldimethylchlorosilane, α-chloroethyltrichlorosilane, β-chloroethyltrichlorosilane, chloromethyldimethylchlorosilane, triorganosilylmercaptan, trimethylsilylmercaptan, triorganosilylacrylate, vinyldimethylacetoxysilamen, dimethyldiethoxysilane, Dimethyldimethoxysilane, diphenyldiethoxysilane, hexamethyldisiloxane, 1,3-divinyltetramethyldisi Loxane, 1,3-diphenyltetramethyldisiloxane, and dimethylpolysiloxane having 2 to 12 siloxane units per molecule, each containing a hydroxyl group bonded to each silicon atom in the terminal unit Etc.
[0019]
In the present invention, silicone oil or silicone varnish can also be suitably used as the hydrophobizing agent for the active silica. As the silicone oil, those represented by the following general formula (I) are preferable.
[0020]
[Chemical 1]

(However, R: an alkyl group having 1 to 3 carbon atoms,
R ′: silicone oil-modified group such as alkyl, halogen-modified alkyl, phenyl, modified phenyl,
R ″: An alkyl or alkoxy group having 1 to 3 carbon atoms.
[0021]
Specific examples of the general formula (I) include dimethyl silicone oil, alkyl-modified silicone oil, α-methylstyrene-modified silicone oil, chlorophenyl silicone oil, and fluorine-modified silicone oil.
[0022]
In the present invention, a modified silicone oil having a structure represented by the following general formula (II) can also be used as the silicone oil.
[Chemical 2]

[0023]
In the general formula (II), R1 and R6 each represents a hydrogen atom, an alkyl group, an aryl group or an alkoxy group, R2 represents an alkylene group or a phenylene group, and R3 has a nitrogen-containing heterocyclic ring in its structure. Represents a compound, and R4 and R5 each represents a hydrogen atom, an alkyl group or an aryl group. R2 may be omitted. However, the alkyl group, aryl group alkylene group, and phenylene group described above may have an amine, or may have a substituent such as halogen as long as the chargeability is not impaired. M is a number of 1 or more, and n and k are positive numbers including 0. However, n + k is a positive number of 1 or more.
[0024]
The most preferable structure among the above structures is one in which the number of nitrogen atoms in the side chain containing nitrogen atoms is 1 or 2. An example of the structure of an unsaturated heterocyclic ring having nitrogen is given below.
[Chemical Formula 3]

[0025]
An example of the structure is given below as a saturated heterocyclic ring having nitrogen.
[Formula 4]

However, the present invention is not limited to the above compound examples, but those having a 5-membered or 6-membered heterocyclic ring are preferred.
[0026]
Examples of the derivatives include derivatives in which a hydrocarbon group, a halogen group, an amino group, a vinyl group, a mercapto group, a methacryl group, a glycidoxy group, a ureido group, or the like is introduced into the above compound group. These may be used alone or in combination of two or more.
[0027]
Examples of the silicone varnish used in the present invention include methyl silicone varnish and phenylmethyl silicone varnish. In particular, in the present invention, it is preferable to use methyl silicone varnish. Methyl silicone varnish has T shown by the following structure³¹Unit, D³¹Unit, M³¹A polymer comprising units and T³¹A three-dimensional polymer containing a large amount of units.
[0028]
[Chemical formula 5]

[0029]
Specifically, the methyl silicone varnish or the phenyl methyl silicone varnish is a substance having a chemical structure as shown by the following structural formula (A).
[Chemical 6]

[0030]
In the above silicone varnish, particularly T³¹The unit is an effective unit for imparting a good thermosetting property to a three-dimensional network structure. In the silicone varnish, the above T³¹It is preferable to use those whose units are contained in the range of 10 to 90 mol%, particularly 30 to 80 mol%.
[0031]
Such a silicone varnish has a hydroxyl group at the end or side chain of the molecular chain, and is cured by a dehydration condensation reaction of the hydroxyl group. Examples of the curing accelerator that can be used to accelerate the curing reaction include fatty acid salts such as zinc, lead, cobalt, and tin; amines such as triethanolamine and butylamine. Of these, amines can be preferably used.
[0032]
In order to make the silicone varnish as described above an amino-modified silicone varnish,³¹Unit, D³¹Unit, M³¹A part of the methyl group or phenyl group present in the unit may be substituted with a group having an amino group. Examples of the group having an amino group include those represented by the following structural formulas, but are not limited thereto.
[Chemical 7]

[0033]
As a method for hydrophobizing the active silica using these silicone oils or silicone varnishes, known techniques can be used. For example, a method of mixing silica fine powder and silicone oil or silicone varnish using a mixer, a method of spraying silicone oil or silicone varnish into a silica fine powder using a sprayer, and dissolving silicone oil or silicone varnish in a solvent Examples thereof include a method of mixing silica fine powder after the treatment.
[0034]
As the silicone oil or silicone varnish, those having a viscosity at 25 ° C. of 10 to 2,000 centistokes, more preferably 30 to 15,000 centistokes are preferably used. That is, when the viscosity is less than 10 centistokes, the fusion level is lowered. On the other hand, if it exceeds 2,000 centistokes, the fusion level is lowered.
[0035]
The viscosity of the silicone oil or the silicone varnish was measured using a Bisco Tester VT500 (manufactured by HAAKE). One of several viscosity sensors for VT500 is selected (arbitrary), and a measurement sample is put in a measurement cell for the sensor and measured. The viscosity (pas) displayed on the apparatus was converted to cs (centistokes).
[0036]
As a processing form of the hydrophobic silica fine powder used in the present invention, there are a case of processing with a silane coupling agent or the like, or a silicone oil or a silicone varnish alone, or a combination of both. As a preferable treatment form, first, treatment with a silane coupling treatment agent and then treatment with silicone oil or silicone varnish can be mentioned. Among these, the form of treating with silicone oil after treating with hexamethylsilazane is particularly preferable.
[0037]
As a treatment method using a silane coupling agent, a dry treatment in which a vaporized silane coupling agent is reacted with a silicate fine powder that has been made into a ground shape by stirring or the like, or a dispersion of the silicate fine powder in a solvent. Examples thereof include a wet treatment method in which a silane coupling agent is dropped. A particularly preferably used method is a dry method in which a silane coupling agent is brought into contact with a fine powder of silica in the presence of water vapor and reacted.
[0038]
A known technique is used for the method of hydrophobizing the active silica surface with silicone oil and / or silicone varnish. For example, silica fine powder and silicone oil are directly mixed using a mixer such as a Henschel mixer. Alternatively, a method of spraying silicone oil onto the raw silica may be used. Alternatively, the silicone oil may be dissolved or dispersed in an appropriate solvent, and then mixed with the base silica fine powder, and then the solvent may be removed.
[0039]
As a method that can be favorably used for the production of the hydrophobic silica fine powder used in the present invention, a method in which a silicone oil is sprayed after treatment with a silane coupling agent, followed by heat treatment at 200 ° C. or higher is suitably used. At this time, the silane coupling agent may be added and treated in an amount of 5 to 60 parts by weight, more preferably 10 to 50 parts by weight with respect to 100 parts by weight of the raw silica. When the amount is less than 5 parts by weight, drum fusion is likely to occur. When the amount is more than 60 parts by weight, it may be difficult to manufacture.
[0040]
The silicone oil or silicone varnish is used in an amount of 5 to 40 parts by weight, more preferably 7 to 35 parts by weight, based on 100 parts by weight of the raw silica or treated silica. When the amount is less than 5 parts by weight, drum fusion is likely to occur. When the amount is more than 40 parts by weight, adverse effects such as image flow are likely to occur.
[0041]
Further, the fine hydrophobic silica powder used in the present invention has a final carbon content in the range of 3.0 to 13.0% by weight, more preferably 4.5 to 12.0% by weight. It is good to use what is in the range of%. In the present invention, the analysis of the carbon content was performed using a trace carbon analyzer (EMIA-100 type manufactured by Horiba).
[0042]
Next, the second constituent requirement of the toner of the present invention is that the weight average particle diameter (D4) is 3.5 to 6.5 μm, and the content of particles having a particle diameter of 10.1 μm or more is 3.0 volume. % Or less.
The toner of the present invention has the main premise that it is possible to form high-quality images, so-called scatter-free characters that are faithful to the latent image, and for this purpose, the toner particle size distribution is defined above. It is necessary to be within the range. First, the toner of the present invention requires that D4 is 3.5 or more and 6.5 μm or less. When D4 is larger than 6.5 μm, the scattering of characters deteriorates, which is not preferable. On the other hand, when D4 is smaller than 3.5 μm, the cohesiveness between toner particles increases, and fogging is liable to occur.
Furthermore, the content of particles having a particle size of 10.1 μm or more must be 3.0% by volume or less. This is because when the content of particles having a particle size of 10.1 μm or more is more than 3.0% by volume, the above-mentioned deterioration of the scattering of characters becomes remarkable.
However, when the toner having such a particle size distribution is used, the above-mentioned high image quality is surely achieved. However, since the toner particle size is small, the adhesion force of the toner to the photosensitive member is increased, and the drum Since the fusion problem has become apparent, it has been difficult to simultaneously solve the problem of achieving high image quality and suppressing drum fusion. However, in the toner of the present invention, the hydrophobic characteristics of the toner, which is an element that affects the adhesion of the toner to the photoreceptor, are controlled so as to satisfy specific conditions as described above. It is possible to solve the suppression of the occurrence of wearing at the same time.
[0043]
In the present invention, the weight average particle diameter of the toner is measured using a commonly used Coulter Counter TA-II (manufactured by Coulter), but a Coulter Multisider (manufactured by Coulter) can also be used. It measured by the method of.
As the electrolyte aqueous solution, 1% NaCl aqueous solution is prepared using primary sodium chloride. For example, ISOTON R-II (manufactured by Coulter Scientific Japan) can be used. As a measuring method, 0.1 to 5 ml of a surfactant, preferably alkylbenzene sulfonate is added as a dispersant to 100 to 150 ml of the aqueous electrolyte solution, and 2 to 20 mg of a sample to be measured is further added. The aqueous electrolyte solution in which the sample is suspended is subjected to a dispersion treatment with an ultrasonic disperser for about 1 to 3 minutes, and the volume and number of toners of 2.00 μm or more are measured using the 100 μm aperture as the aperture by the measuring device. From these values, the volume distribution and the number distribution were calculated.
[0044]
Then, a weight-based weight average particle diameter (D4) is obtained from the volume distribution (the median value of each channel is a representative value for each channel), and a volume-based particle diameter is obtained from the volume distribution, and is 10.1 μm or more. The proportion of particles was determined.
The channel is as follows: 2.00 to less than 2.52 μm: 2.52 to less than 3.17 μm: 3.17 to less than 4.00 μm: 4.00 to less than 5.04 μm: 5.04 to less than 6.35 μm: 6 35 to less than 8.00 μm: 8.00 to less than 10.08 μm: 10.08 to less than 12.70 μm: 12.70 to less than 16.00 μm: 16.00 to less than 20.20 μm: 20.20 to 25. Less than 40 μm: 25.40 to less than 32.00 μm: 13 channels of 32.00 to less than 40.30 μm were used.
[0045]
In the toner of the present invention, as described above, it is preferable to use a hydrophobic silica fine powder having specific hydrophobic properties as an external additive of the toner. In this case, the particle size of the hydrophobic silica fine powder is used. The number average particle diameter (length average) is preferably 0.1 μm or less, more preferably 5 to 50 nm. Further, the highly hydrophobic silica fine powder used in the present invention has a specific surface area of 10 to 550 m as measured by a nitrogen adsorption method.²/ G, and 50 to 500m²/ G is preferable.
[0046]
Furthermore, as the hydrophobic silica fine powder used in the present invention, it is preferable to use those having a negative frictional charging property of −30 to −400 μg / g with respect to the iron powder, It is preferable to use -50 to -300 μg / g of iron powder.
[0047]
In addition, the highly hydrophobic silica fine powder having the above-described characteristics used in the present invention may be used by being added at a ratio of 0.6 to 3.0 parts by weight with respect to 100 parts by weight of the toner particles. preferable. That is, when the addition amount is less than 0.6 parts by weight, it is difficult to obtain a sufficient image density. When the addition amount is less than 3.0 parts by weight, adverse effects such as drum fusion occur, which is not preferable. More preferably, when the amount is less than 2.0 parts by weight, the object of the present invention can be suitably achieved.
[0048]
In the toner of the present invention, in order to more fully solve the intended purpose, it is desirable to add a second inorganic fine powder in addition to the hydrophobic silica fine powder described above. Examples of the second inorganic fine powder include iron oxide, chromium oxide, calcium titanate, strontium titanate, silicon titanate, barium titanate, magnesium titanate, cerium oxide, zirconium oxide, aluminum oxide, titanium oxide, and oxide. Examples include zinc and calcium oxide. Among these, in the present invention, it is particularly preferable to use a composite oxide. For example, strontium titanate fine powder, calcium titanate fine powder, or silicon titanate fine powder is preferably used.
[0049]
Moreover, as these 2nd inorganic fine powder, it is preferable to use that whose number average particle diameter of the primary particle is 0.12-3.0 micrometers. When the number average particle size of the primary particles is smaller than 0.12 μm, there is an unfavorable influence on the image blur prevention effect. On the other hand, when the number average particle size is larger than 3.0 μm, it is easy to damage the drum surface. Absent.
[0050]
The hydrophobic silica fine powder used in the present invention and the number average particle diameter of the second inorganic fine particles to be added as necessary are values measured by the following method.
Using an electron microscope S-800 (manufactured by Hitachi, Ltd.), first, the hydrophobic silica fine powder constituting the toner of the present invention is 10,000 to 20,000 times, and the second inorganic fine particle is 1,000. Take a photo at a magnification of ~ 20,000. Next, from the photographed fine particles, 100 to 200 particles of 0.001 μm or more are extracted randomly for the hydrophobic silica fine powder, and 100 to 200 particles are randomly extracted for the second inorganic fine particles, Each diameter is measured using a measuring instrument such as a vernier caliper, and the average is obtained as the number average particle diameter of each inorganic fine particle.
[0051]
The amount of the second inorganic fine powder added to the toner of the present invention is about 0.3 to 5.0 parts by weight with respect to 100 parts by weight of the toner particles in order to better solve the problems of the present invention. Is preferably added. That is, when the amount is less than 0.3 parts by weight, image flow tends to occur, which is not preferable. When the amount exceeds 5.0 parts by weight, drum fusion tends to occur, which is not preferable.
[0052]
The toner of the present invention is composed of at least hydrophobic silica fine powder having the above-mentioned characteristics and toner particles. As the toner particles, generally used toner particles are used. The toner particles are usually composed of a colored resin composition having a binder resin and a colorant, which will be described below.
First, the types of binder resins used for the toner particles include, for example, polystyrene; homopolymers of styrene substitution products such as poly-p-chlorostyrene and polyvinyltoluene; styrene-p-chlorostyrene copolymers, styrene- Vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, styrene-acrylic acid ester copolymer, styrene-methacrylic acid ester copolymer, styrene-α-chloromethyl methacrylate copolymer, styrene-acrylonitrile copolymer Styrene-vinyl methyl ether copolymer, styrene-vinyl ethyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-acrylonitrile-indene copolymer Styrene copolymers such as Vinyl chloride, phenolic resin, natural modified phenolic resin, natural resin modified maleic acid resin, acrylic resin, methacrylic resin, polyvinyl acetate, silicone resin, polyester resin, polyurethane, polyamide resin, furan resin, epoxy resin, xylene resin, polyvinyl butyral Terpene resin, coumarone indene resin, petroleum resin and the like can be used. A cross-linked styrene resin is also a preferable binder resin. Among these, styrene-based binder resins are preferably used for the toner having specific hydrophobic characteristics of the present invention.
[0053]
Examples of the comonomer for the styrene monomer of the styrene copolymer include acrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, dodecyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, phenyl acrylate, methacrylic acid. Monocarboxylic acid having a double bond such as acid, methyl methacrylate, ethyl methacrylate, butyl methacrylate, octyl methacrylate, acrylonitrile, methacrylonitrile, acrylamide and the like; for example, maleic acid, butyl maleate , Dicarboxylic acids having a double bond such as methyl maleate, dimethyl maleate and the like; and substituted products thereof; for example, vinyl esters such as vinyl chloride, vinyl acetate, vinyl benzoate, etc .; Ethylene olefins such as butylene, etc .; vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone, etc .; vinyl units such as vinyl ethers such as vinyl methyl ether, vinyl ethyl ether, vinyl isobutyl ether, etc. The monomers are used alone or in combination.
[0054]
Here, as the crosslinking agent, compounds having two or more polymerizable double bonds are mainly used. For example, aromatic divinyl compounds such as divinylbenzene and divinylnaphthalene; for example, ethylene glycol diacrylate, ethylene glycol A carboxylic acid ester having two double bonds, such as dimethacrylate, 1,3-butanediol dimethacrylate; a divinyl compound such as divinylaniline, divinyl ether, divinyl sulfide, divinyl sulfone; and three or more vinyl groups. Can be used alone or as a mixture.
[0055]
Furthermore, as the styrene-based binder resin used for constituting the toner of the present invention, at least 0.5 × 10 5 in gel permeation chromatography (GPC).^Four~ 5x10^FourAnd 1.0 × 10^Five~ 5.0 × 10⁶Those having a main peak and a sub peak in the region are preferred. Further, among these styrene resins, those having no tetrahydrofuran (THF) insoluble content are preferable, and the weight average molecular weight (Mw) is 1.5 × 10 5.^Five~ 3.5 × 10^Five, More preferably 1.8 × 10^Five~ 3.2 × 10^FiveIt is preferable to use what is.
[0056]
In the toner of the present invention, it is preferable that the toner particles contain a wax. Examples of the wax used in this case include paraffin wax and derivatives thereof, microcrystalline wax and derivatives thereof, Fischer-Tropsch wax and derivatives thereof, polyolefin wax and derivatives thereof, carnauba wax and derivatives thereof, etc. Products, block copolymers with vinyl monomers, and graft modified products.
[0057]
In particular, the wax preferably used in the present invention is represented by the general formula RY (wherein R represents a hydrocarbon group, and Y represents a hydroxyl group, a carboxyl group, an alkyl ether group, an ester group or a sulfonyl group). The thing represented by is mentioned. Furthermore, among the waxes represented by the general formula RY, those having a weight average molecular weight (Mw) of 3,000 or less by gel permeation chromatography (GPC) can be preferably used.
[0058]
Specific compounds satisfying the above requirements include the following (A), (B) and (C).
[Chemical 8]

[0059]
The compounds (B) and (C) are derivatives of the compound (A), and the main chain is a linear saturated hydrocarbon. Any compound other than those shown in the above examples can be used as long as it is a compound derived from the above compound (A). Particularly preferred waxes that can be used in the present invention include CH_Three(CH₂)_nExamples thereof include long-chain alkyl alcohols represented by OH (n = 20 to 300) and mixtures containing these as main components.
[0060]
The toner particles constituting the toner of the present invention may contain a charge control agent, but an organometallic compound is preferably used as the charge control agent. Further, among organic metal compounds, those containing an organic compound rich in vaporization and sublimation properties as a ligand or counter ion are particularly useful.
[0061]
As such a metal complex, there is an azo metal complex represented by the following general formula.
[Chemical 9]

[0062]
In the above formula, M represents a coordination center metal, and represents Cr, Co, Ni, Mn, Fe, Al, Ti, Sc, V or the like having a coordination number of 6. Ar is an aryl group such as a phenyl group or a naphthyl group, and may have a substituent. Examples of the substituent in this case include a nitro group, a halogen group, a carboxyl group, an anilide group, an alkyl group having 1 to 18 carbon atoms, and an alkoxyl group. X, X ′, Y, and Y ′ are —O—, —CO—, —NH—, and —NR— (R represents an alkyl group having 1 to 4 carbon atoms). A⁺Represents hydrogen ion, sodium ion, potassium ion, ammonium ion, aliphatic ammonium ion, or any mixed ion thereof. )
[0063]
Specific examples (a) to (c) of the azo metal complexes represented by the above general formula that can be used well when forming the toner of the present invention are shown below.
Embedded image

[0064]
The toner of the present invention can also be a magnetic toner. In this case, magnetic materials suitably used include magnetic metal oxides containing elements such as iron, cobalt, nickel, copper, magnesium, manganese, aluminum, and silicon. Etc. Especially, what has iron oxides, such as a triiron tetroxide and (gamma) -iron oxide, as a main component is preferable. Further, from the viewpoint of improving the fluidity of the toner and controlling the chargeability, it is preferable to contain a silicon atom. In particular, when the magnetic toner particles have a small diameter, the fluidity of the toner particle matrix decreases, so that sufficient fluidity cannot be obtained simply by adding the above-described hydrophobic silica fine powder used in the present invention. In some cases, it becomes difficult to achieve the object of the present invention. The content of silicon atoms is preferably 0.2 to 2.0% by weight based on the magnetic material, and if it is less than 0.2% by weight, sufficient fluidity cannot be obtained, and character sharpness is reduced. Defects such as deterioration and solid black density thin occur. If it is contained in an amount of more than 2.0% by weight, the image density tends to be lowered particularly in a high temperature and high humidity environment. The silicon atom content is more preferably 0.3 to 1.7% by weight. In particular, the case where 0.05 to 0.5% by weight of silicon atoms is present on the surface of the magnetic material is more preferable.
[0065]
Silicon atoms may be added in the form of a water-soluble silicon compound at the time of production of the magnetic substance, or after the production of the magnetic substance, filtration and drying, it may be added in the form of a silicate compound and fixed to the surface with a mix muller or the like. . These magnetic particles preferably have a BET specific surface area of 2 to 30 m by nitrogen adsorption.²/ G, especially 3 to 28m²/ G is preferred. Furthermore, it is preferable to use magnetic particles having a Mohs hardness of 5 to 7.
[0066]
The shape of the magnetic particles to be used includes octahedrons, hexahedrons, spheres, needles, scales, etc., but those having low anisotropy such as octahedrons, hexahedrons, spheres, and irregular shapes are preferred. In particular, the sphericity Ψ of the magnetic particles is preferably 0.8 or more from the viewpoint of increasing the image density. The average particle size of the magnetic particles is preferably 0.05 to 1.0 μm, more preferably 0.1 to 0.6 μm, and particularly preferably 0.1 to 0.4 μm.
[0067]
The content of these magnetic materials in the toner of the present invention is 30 to 200 parts by weight, preferably 60 to 200 parts by weight, and more preferably 70 to 150 parts by weight with respect to 100 parts by weight of the binder resin. If it is less than 30 parts by weight, the transportability is inferior, the toner layer on the developer carrying member tends to be uneven and tends to cause image unevenness, and further, the image density is likely to decrease due to an increase in the magnetic toner tribo. Tend. On the other hand, when the content of the magnetic material exceeds 200 parts by weight, the fixability may be lowered.
[0068]
As a method for producing the toner of the present invention, a known method is used. For example, binder resin, wax, metal salt or metal complex, pigment as coloring agent, dye, or magnetic substance, toner as necessary, charge control agent, other additives, etc. are used as appropriate. After mixing the resins in the raw material thoroughly with a mixer such as a Henschel mixer or a ball mill, the resins are melted and kneaded using a heat kneader such as a heating roll, kneader or extruder to make the resins compatible with each other. In this, a metal compound, a pigment, a dye, a magnetic substance and the like are dispersed or dissolved, cooled and solidified, and then pulverized and classified to obtain toner particles. In the classification step, it is preferable to obtain toner particles having a desired particle size distribution using a multi-division classifier in terms of production efficiency.
[0069]
Further, an external additive containing hydrophobic silica fine powder is added in a range of about 0.6 to 3.0 parts by weight with respect to 100 parts by weight of the toner particles obtained in the above classification step, and the mixture is mixed. The toner of the invention is obtained. Preferable examples of the apparatus used in the external addition mixing step include Henschel mixers manufactured by Mitsui Miike Chemical Industries, Ltd. having names such as FM-500, -300, -75, and -10.
[0070]
Next, FIG. 3 shows an outline of an example of an image forming apparatus that can suitably use the toner of the present invention having the above-described configuration. The image forming method of the present invention will be described based on the outline. .
In the figure, reference numeral 1 denotes a rotating drum-shaped electrostatic latent image carrier, around which a charging roller (charging member) 2 as a primary charging device, an exposure optical system 3, and a developing device 4 having a toner carrier 5; A transfer device 9 and a cleaning device 11 are arranged.
[0071]
In this image forming apparatus, first, the surface of the electrostatic latent image carrier 1 as a photosensitive member is uniformly charged by a charging roller 2 as a primary charging device, and then the image is exposed by an exposure optical system 3. An electrostatic latent image is formed on the surface of the electrostatic latent image carrier 1.
Here, the charging member of the electrostatic latent image carrier suitably used in the image forming method of the present invention includes a contact charging member arranged in contact with the electrostatic image carrier, but the shape thereof is particularly limited. However, it may be in the form of a roller as shown in FIG. 3, or may be in the form of a blade or brush. The voltage applied to these charging members is preferably a DC voltage of 200 to 2,000 V in absolute value, and the AC voltage has a peak-to-peak voltage of 400 to 4,000 V and a frequency of 200 to 3,000 Hz. It is preferable that
[0072]
Next, a toner coat layer is formed by the toner layer thickness regulating member 6 on the surface of the toner carrier 5 including a magnet (not shown), and is carried and conveyed to the developing unit by the toner carrier 5. The image forming method of the present invention is characterized in that the toner of the present invention described above is used at this time. In the developing section, electrostatic bias is applied while applying an alternating bias, a pulse bias and / or a DC bias by the bias applying means 8 between the conductive substrate of the electrostatic latent image carrier 1 and the toner carrier 5. The electrostatic latent image formed on the latent image carrier 1 is developed with the toner of the present invention to form a toner image.
[0073]
Next, the toner image developed as described above is conveyed with the transfer paper P and charged with a reverse polarity to the toner from the back surface of the transfer paper P by the transfer roller 9 and voltage application means 10 as a transfer device. Thus, electrostatic transfer is performed on the transfer paper P. Furthermore, a fixed image is obtained on the transfer paper P by allowing the transfer paper P on which the toner image has been transferred to pass through the heat and pressure roller fixing device 12.
The toner remaining on the latent electrostatic image bearing member after the transfer step is removed by a cleaning blade 11 as a cleaning device and collected by a cleaner 14, and then the steps of primary charging and lower are repeated again to form an image. Is done.
[0074]
Among the constituent elements such as the electrostatic charge image carrier, the developing device, and the cleaning unit such as the photosensitive drum described above, a plurality of components are integrally coupled as an apparatus unit to form a process cartridge, and the process cartridge is attached to the apparatus main body. It can also be configured to be detachable. For example, a charging cartridge and a developing device are integrally supported together with a photosensitive drum to form a process cartridge, which is a single unit that is detachable from the apparatus main body, and is configured to be detachable using guide means such as a rail of the apparatus main body. May be. At this time, the process cartridge may be configured with a cleaning means.
[0075]
FIG. 4 shows an embodiment of a process cartridge which is an apparatus unit of the present invention. In this embodiment, a process cartridge 16 in which a developing device 4, a drum-shaped electrostatic charge image carrier (photosensitive drum) 1, a cleaner 14 having a cleaning blade 11, and a primary charging member 2 are integrated is exemplified. Such a process cartridge is replaced with a new cartridge when the magnetic toner 13 of the developing device 4 runs out.
In the example shown in FIG. 4, magnetic toner 13 is stored in the toner container 15 of the developing device 4, and at the time of development, a predetermined electric field is generated between the photosensitive drum 1 and the developing sleeve 5 as a toner carrier. The distance between the photosensitive drum 1 and the developing sleeve 5 is very important in order for the developing process to be performed properly.
[0076]
In the process cartridge shown in FIG. 4, the developing device 4 has a toner container 15 for containing the magnetic toner 13 and the magnetic toner 13 in the toner container 15 facing the electrostatic charge image carrier 1 from the toner container 15. A developing sleeve 5 that is carried and conveyed to the developing zone, and a magnetic toner that is carried by the developing sleeve 5 and that is conveyed to the developing zone is regulated to a predetermined thickness, and a toner thin layer is formed on the developing sleeve. And an elastic blade 6 as a toner layer thickness regulating member.
[0077]
The developing sleeve 5 can have an arbitrary structure. Usually, it comprises a non-magnetic developing sleeve 5 containing a magnet (not shown). The developing sleeve 5 may be a cylindrical rotating body as illustrated. It is also possible to form a belt that circulates. As the material, it is usually preferable to use aluminum or SUS.
[0078]
The elastic blade 6 is made of a rubber elastic body such as urethane rubber, silicone rubber or NBR; a metal elastic body such as phosphor bronze or stainless steel; an elastic plate formed of a resin elastic body such as polyethylene terephthalate or high density polyethylene. Consists of. The elastic blade 6 is brought into contact with the developing sleeve 5 by the elasticity of the member itself, and is fixed to the toner container 15 by a blade support member made of a rigid body such as iron. The elastic blade 6 is preferably in contact with the rotation direction of the developing sleeve 5 in the counter direction at a linear pressure of 5 to 80 g / cm. Instead of such an elastic blade 6, a magnetic doctor blade such as iron may be used.
[0079]
In the example described above, the charging roller 2 is used as the contact charging member as the primary charging unit, but the present invention is not limited to this, and a contact charging unit such as a charging blade or a charging brush may be used. This contact charging member is preferable in that ozone generation due to charging is small. Although the transfer means has been described using the transfer roller 9, it may be a contact charging means such as a transfer blade, and may further be a non-contact corona transfer means. However, the contact charging means is also preferable in that it generates less ozone due to transfer.
[0080]
【Example】
EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention concretely, this does not limit this invention at all. “Part” means part by weight.
Production of hydrophobic silica fine powder and its physical properties
First, hydrophobic silica fine powders I to VI used in Examples and Comparative Examples of the present invention were prepared as follows.
(Silica I)
Specific surface area 200m²16 parts of hexamethyldisilazane were reacted in the presence of water vapor with 100 parts of / g of raw silica. Thereafter, 10 parts of silicone oil having a viscosity of 100 cs was sprayed on 100 parts of the treated hydrophobic silica fine powder, and then heated at 250 ° C. to obtain hydrophobically treated silica I. Table 1 shows production conditions for silica I and physical property values other than the transmittance. Table 2 shows the transmittance (%) data in the methanol dropping transmittance curve for silica I.
[0081]
(Silica II)
  Silica except that the amount of silicone oil treated was 15 partsIIn the same manner, silica II was obtained. As in the case of silica I, the production conditions, physical property values, transmittance and the like are shown in Tables 1 and 2.
[0082]
(Silica III)
  Silica except that the amount of hexamethyldisilazane added was 24 parts.IIn the same manner, silica III was obtained. As in the case of silica I, the production conditions, physical property values, transmittance and the like are shown in Tables 1 and 2.
[0083]
(Silica IV)
  Silica except that the amount of hexamethyldisilazane added was 32 partsISilica IV was obtained in the same manner as above. As in the case of silica I, the production conditions, physical property values, transmittance and the like are shown in Tables 1 and 2.
[0084]
(Silica V)
Silica V was obtained in the same manner as Silica IV, except that the amount of silicone oil treated was 15 parts. As in the case of silica I, the production conditions, physical property values, transmittance and the like are shown in Tables 1 and 2.
[0085]
(Silica VI)
Specific surface area 200m²Hexamethyldisilazane was spray-reacted with respect to 100 parts of / g of raw silica. Thereafter, 10 parts of silicone oil having a viscosity of 100 cs dissolved in n-hexane was sprayed on 100 parts of the treated hydrophobic silica fine powder, and then heated at 350 ° C. to obtain silica VI. As in the case of silica I, the production conditions, physical property values, transmittance and the like are shown in Tables 1 and 2.
[0086]
[Table 1]
Table 1: Characteristics and physical properties in the production of hydrophobic silica fine powder

[0087]
[Table 2]
Table 2: Permeability (%) value with respect to methanol content (volume%) in a sample for measurement of hydrophobic characteristics of silica fine powder read from methanol drop permeability curve

[0088]
Toner creation and evaluation results
<Example 1>
・ Binder resin (Styrene resin, GPC has a molecular weight of 15,000
, Having a subpeak at a molecular weight of 650,000) 100 parts by weight
・ Magnetic (Fe_ThreeO_Four100 parts by weight
・ Charge control agent (monoazo iron complex) 2 parts by weight
・ Wax (polymeric alcohol wax) 5 parts by weight
The above mixture is melt-kneaded with a biaxial extruder heated to 130 ° C., the cooled kneaded product is coarsely pulverized with a hammer mill, the coarsely pulverized product is finely pulverized with a jet mill, and further weighted with an elbow jet classifier. Toner particles having an average diameter (D4) of 5.8 μm were obtained.
[0089]
To 100 parts of the toner particles obtained above, a specific surface area of 110 (m²/ G) 1.5 parts of hydrophobic silica fine powder I was added and mixed with a Henschel mixer to obtain a toner of this example. Table 3 shows the transmittance (%) data read from the ethanol dropping transmittance curve for the obtained toner.
[0090]
Evaluation was performed according to the following image evaluation method using the image forming apparatus having the configuration shown in FIG. 3 with the process cartridge shown in FIG. At that time, “LBP-5L” manufactured by Hewlett-Packard Company was used as a process cartridge. Then, the toner of the present example obtained above was set in the “LJ-5L” process cartridge to form an image. The results obtained are shown in Table 4.
The “LJ-5L” uses a contact charging roller in contact with the surface of the photoreceptor as a primary charging member. The charging roller is charged with a DC voltage of −625 V, an AC voltage of 1.8 kV between peaks, and a frequency of 370 Hz. A voltage is applied to primary charge the photoreceptor. Further, transfer was performed by applying a voltage of 2.3 kV to the transfer roller.
[0091]
(1) Evaluation of drum fusion
After printing out 2,500 sheets of images with an image area ratio of about 3% under high temperature and high humidity (33.0 ° C, 95% RH) continuously, a solid black image is printed on the entire surface of the A4 size recording paper. The degree of occurrence of white spots formed on a solid black image was evaluated. Evaluation was performed according to the following criteria.
A: No white spot occurs on A4 size recording paper.
AB: Intermediate level between A and B.
B: Intermediate level between A and C.
C: About 10 white spots are observed on A4 size recording paper.
D: Intermediate level between C and E.
E: 100 or more white spots are seen on A4 size recording paper.
[0092]
(2) Image flow
An image having an image area ratio of about 3% was continuously printed out in a high-temperature and high-humidity environment (33.0 ° C., 95% RH), and then evaluated based on the degree of image flow after 2,500 sheets. In this evaluation, paper (using 33.0 ° C., 95% RH with a moisture absorption of 10%) using talc, which is apt to cause image flow, as a filler was used as an evaluation paper. The moisture absorption of the paper was measured using MOISTREX MX 5000 manufactured by Infrared Engineering. Evaluation was performed according to the following criteria.
A: No image flow occurs.
AB: Intermediate level between A and B.
B: Intermediate level between A and C.
C: Although an image stream has occurred, it is possible to determine what character is.
D: Intermediate level between C and E.
E: An image flow occurs and characters cannot be identified.
[0093]
(3) Drum scraping
After continuously printing out 3,000 sheets of images with an image area ratio of about 3% in a low-temperature, low-humidity environment (15.0 ° C., 10% RH), the amount of scraping of the drum is measured to obtain a value of 1,000 sheets. The converted value was used. The measurement was performed using a film thickness measuring machine manufactured by Fischer.
[0094]
(4) Transfer efficiency
In a normal temperature and humidity environment (25.0 ° C., 60% RH), the transfer efficiency was examined from a solid black image formed on the drum. The transfer efficiency value is a value obtained by adding the amount of toner per unit area remaining on the transfer paper after transfer to the amount of toner per unit area remaining on the drum after transfer, and per unit area existing on the transfer paper after transfer. This is the value obtained by dividing the toner amount.
[0095]
<Example 2>
A toner of this example was obtained in the same manner as in Example 1 except that the silica fine powder II was used. Table 3 shows the transmittance (%) data read from the ethanol dropping transmittance curve for the obtained toner. The evaluation was performed in the same manner as in Example 1, and the results are shown in Table 4.
[0096]
<Example 3>
A toner of this example was obtained in the same manner as in Example 1 except that the silica fine powder III was used. Table 3 shows the transmittance (%) data in the ethanol dropping transmittance curve for the obtained toner. The evaluation was performed in the same manner as in Example 1, and the results are shown in Table 4.
[0097]
<Example 4>
A toner of this example was obtained in the same manner as in Example 1 except that the silica fine powder IV was used. Table 3 shows the transmittance (%) data read from the ethanol dropping transmittance curve for the obtained toner, and FIG. 1 shows the ethanol dropping transmittance curve. The evaluation was performed in the same manner as in Example 1, and the results are shown in Table 4.
[0098]
<Example 5>
A toner of this example was obtained in the same manner as in Example 1 except that the silica fine powder V was used. Table 3 shows transmittance (%) data read from the ethanol dropping transmittance curve of the obtained toner. The evaluation was performed in the same manner as in Example 1, and the results are shown in Table 4.
[0099]
<Comparative Example 1>
A toner of this comparative example was obtained in the same manner as in Example 1 except that silica VI, which is a hydrophobic silica fine powder not having the specific hydrophobic characteristics defined in the present invention, was used. Table 3 shows the transmittance (%) data read from the ethanol dropping transmittance curve for the obtained toner, and FIG. 2 shows the ethanol dropping transmittance curve. The evaluation was performed in the same manner as in Example 1, and the results are shown in Table 4.
[0100]
<Comparative example 2>
The binder resin is a styrene resin, and the molecular weight distribution by GPC has only a main peak at 6,500, no other peaks, and has a gel content of 40%, and the wax is polypropylene 4 A toner particle having a D4 of 7.2 μm was obtained in the same manner as in Example 1 except that the part was used. Toner was obtained by adding 1.2 parts of hydrophobic silica VI to 100 parts of toner particles. Table 3 shows the transmittance (%) data read from the ethanol dropping transmittance curve for the obtained toner. The evaluation was performed in the same manner as in Example 1, and the results are shown in Table 4.
[0101]
[Table 3]
Table 3: Permeability (%) value with respect to ethanol content (% by volume) in a sample for measurement of hydrophobic properties of toner read from ethanol drop transmittance curve

[0102]
[Table 4]
Table 4: Evaluation results

[0103]
【The invention's effect】
As described above, according to the present invention, by using an ultrafine particle toner having unique hydrophobic characteristics, drum fusion and image flow are generated even under high temperature and high humidity when used for image formation. In addition, the transfer efficiency is high, and the amount of scraping of the drum can be reduced, so that a toner having excellent characteristics capable of extending the life of the drum can be provided.
[Brief description of the drawings]
1 is an ethanol dropping transmittance curve obtained for the toner of Example 4. FIG.
2 is an ethanol dropping transmittance curve obtained for the toner of Comparative Example 4. FIG.
FIG. 3 is a schematic view of an example of an image forming apparatus to which the image forming method of the present invention is applied.
FIG. 4 is an explanatory view showing an embodiment of a process cartridge according to the present invention.
[Explanation of symbols]
1: Latent image carrier
2: Primary charging device
3: Exposure optical system
4: Development device
5: Toner carrier
6: Toner layer thickness regulating member
7: Toner stirring means
8: Development bias power supply
9: Transfer device
10: Transfer current generator
11: Cleaning means
12: Fixing device
13: Toner
14: Cleaner
15: Toner container
16: Process cartridge

Claims (8)

In a toner having at least toner particles and hydrophobic silica fine powder, 0.025 g of toner, which is precisely weighed in a container having 70 ml of a water-containing ethanol solution composed of 25% by volume of ethanol and 75% by volume of water, is added to the toner. The measurement sample solution prepared in this manner was added with ethanol at 0.5 ml / min. When represented by an ethanol drop transmittance curve prepared by measuring transmittance with light having a wavelength of 780 nm while adding at a dropping rate of
(1) The transmittance of the sample solution for measurement at an ethanol content of 25 to 37% by volume is 90% or more, and
(2) The transmittance of the sample liquid for measurement at an ethanol content of 38% by volume is 85% or more, and
(3) The transmittance of the measurement sample solution at an ethanol content of 40% by volume is 60% or more,
A toner having a weight average particle diameter (D4) of 3.5 to 6.5 μm and a content of particles having a particle diameter of 10.1 μm or more of 3.0% by volume or less.   The toner according to claim 1, wherein the transmittance of the sample liquid for measuring hydrophobic characteristics of the toner at an ethanol content of 38% by volume is 90% or more. The hydrophobic silica is silica which is hydrophobized by spraying silicone oil after reacting the raw silica with a silane coupling agent in the presence of water vapor. Toner. Measurement sample prepared by adding 0.06 g of hydrophobic silica fine powder, in which a hydrophobic property of hydrophobic silica fine powder was precisely weighed in a container holding 70 ml of a water-containing methanol solution consisting of 60 volume% methanol and 40 volume% water. In the liquid, methanol was added at 1.3 ml / min. Hydrophobic properties of the hydrophobic silica fine powder are expressed using a methanol drop transmittance curve prepared by measuring the transmittance with light having a wavelength of 780 nm while adding at a dropping rate of
(1) The transmittance of the sample liquid for measurement at a methanol content of 60 to 72% by volume is 90% or more, and
(2) The toner according to claim 1, wherein the transmittance of the measurement sample liquid is 90% or more at a methanol content of 74% by volume.   6. The toner according to claim 5, wherein the transmittance of the sample liquid for measuring hydrophobic characteristics of the hydrophobic silica fine powder at a methanol content of 71% by volume is 90% or more. The toner according to claim 5 transmittance of the sample liquid for hydrophobic properties measurement of the hydrophobic silica fine powder definitive methanol content 76% by volume is 85% or more. An electrostatic charge image is formed on the electrostatic charge image carrier, the electrostatic charge image is developed by a developing means using toner to form a toner image on the electrostatic charge image carrier, and the toner image is passed through an intermediate transfer member. In the image forming method, the toner image on the transfer material is fixed by a fixing means to obtain a fixed image.
To develop the electrostatic image, the toner has at least toner particles and hydrophobic silica fine powder, and the toner has a hydrophobic property of 70 ml of a water-containing ethanol solution containing 25% by volume of ethanol and 75% by volume of water. To a sample solution for measurement prepared by adding 0.025 g of toner precisely weighed to a container, ethanol was added at 0.5 ml / min. When represented by an ethanol drop transmittance curve prepared by measuring transmittance with light having a wavelength of 780 nm while adding at a dropping rate of
(1) The transmittance of the sample solution for measurement at an ethanol content of 25 to 37% by volume is 90% or more, and
(2) The transmittance of the sample liquid for measurement at an ethanol content of 38% by volume is 85% or more, and
(3) The transmittance of the sample solution for measurement at an ethanol content of 40% by volume is 60% or more,
Image formation using a toner having a toner weight average particle diameter (D4) of 3.5 to 6.5 μm and a content of particles having a particle diameter of 10.1 μm or more of 3.0% by volume or less. Method. A toner unit in which at least an electrostatic charge image carrier and a developing unit are integrally provided and configured to be detachable from the main body of the image forming apparatus, wherein the developing unit includes at least toner particles and hydrophobic silica fine powder. And a toner stored in the storage portion.
A toner having at least toner particles and hydrophobic silica fine powder, wherein the toner has a hydrophobic characteristic and is precisely weighed in a container having 70 ml of a water-containing ethanol solution composed of 25% by volume of ethanol and 75% by volume of water. To the measurement sample solution prepared by adding 025 g, ethanol was added at 0.5 ml / min. When represented by an ethanol drop transmittance curve prepared by measuring transmittance with light having a wavelength of 780 nm while adding at a dropping rate of
(1) The transmittance of the sample solution for measurement at an ethanol content of 25 to 37% by volume is 90% or more, and
(2) The transmittance of the sample liquid for measurement at an ethanol content of 38% by volume is 85% or more, and
(3) The transmittance of the sample solution for measurement at an ethanol content of 40% by volume is 60% or more,
An apparatus unit, wherein the toner has a weight average particle diameter (D4) of 3.5 to 6.5 μm and a content of particles having a particle diameter of 10.1 μm or more is 3.0% by volume or less.

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