JP3948714B2 - Image forming method - Google Patents

Description

【００２４】
画像品質については、トナー像の転写後、定着後の体積及び面積が変化し画像品質が悪化する。この現象はデジタル現像の場合が特に顕著であり、独立したドットの再現性が大きく影響を受ける。
ハーフトーンの濃度は一様であるべきだが、ミクロな濃度むらが生じていると、肉眼で見たときにざらついた印象をあたえる。
ざらつきの物理的評価値は粒状度（ｇｒａｎｕｌａｒｉｔｙ）である。
ノイズは濃度変動の周波数特性であるウィナースペクトラム（Ｗｉｅｎｅｒ Ｓｐｅｃｔｒｕｍ）によって測定できる。
平均値が０である濃度変動成分をｆ（ｘ）とすると
Ｆ（ｕ）＝∫ｆ（ｘ）ｅｘｐ（−２πｉｕｘ）ｄｘ （１）
ＷＳ（ｕ）＝Ｆ（ｕ）^２ （２）
（ここでｕは空間周波数である。）
粒状度（ＧＳ）は、ＷＳと視覚の周波数特性（Ｖｉｓｕａｌ Ｔｒａｎｓｆｅｒ Ｆｕｎｃｔｉｏｎ： ＶＴＦ）の積を積分した値で、下記式（３）で表される。
ＧＳ＝ｅｘｐ(−１．８＜Ｄ＞)∫ＷＳ(ｕ)^1/2ＶＴＦ(ｕ)ｄｕ （３）
Ｅｘｐ（−１．８＜Ｄ＞）は濃度と人の知覚する明るさの差を補正するための係数である。＜Ｄ＞は濃度の平均値を表す。
粒状度は画像のなめらかさの主観評価と高い相関がある。
粒状度の値が小さいほど滑らかな高画質となり、逆に大きいとざらついたプアな画像品質となる。
【００２５】
本発明はトナーの平均円形度が０．９２以上であることが好ましく、０．９２〜０．９９が特に好ましい。平均円形度が０．９２未満の場合、トナー粒子が不定形となり感光体上でのトナー像の集合状態が不均一となり、一次定着での転写、定着性が悪化する。
平均円形度の測定は（株）ＳＹＳＭＥＸ製フロー式粒子像分析装置ＦＰＩＡ−２１００を用いて測定することができる。測定は、１級塩化ナトリウムを用いて１％ＮａＣｌ水溶液に調整した後０．４５μｍのフィルターを通した液５０〜１００ｍｌに分散剤として界面活性剤、好ましくはアルキルベンゼンスルフォン酸塩を０．１〜５ｍｌ加え、試料を１〜１０ｍｇ加える。これを、超音波分散機で１分間の分散処理を行い、粒子濃度を５０００〜１５０００個／μｌに調整した分散液を用いて測定を行なう。ＣＣＤカメラで撮像した２次元の画像面積と、同一の面積を有する円の直径を円相当径として、円相当径で０．６μｍ以上をＣＣＤの画素の精度から有効とし平均円形度の算出に用いる。平均円形度は、各粒子の円形度の算出を行い、この各粒子の円形度を足し合わせ、全粒子数で割り算することによって得ることができる。各粒子の平均円形度は、粒子像と同じ投影面積をもつ円の周囲長を粒子投影像の周囲長で割ることにより算出することができる。
平均円形度が０．９２以上のトナーは、機械的な衝撃による粉砕や、熱処理による方法などで作ることができる。
【００２６】
本発明はトナーのガラス転移温度Ｔｇが５０〜７０℃であることが好ましい。Ｔｇが５０℃より低い場合、トナーの保存性が悪化する。また７０℃より高い場合、二次定着における熱定着性が悪化する。
Ｔｇの測定はＡＳＴＭ Ｄ３４１８−８２に準じて行う。ＤＳＣ曲線は一度昇温、降温させた後、昇温速度１０℃／ｍｉｎで測定されたＤＳＣ曲線を用いる。
【００２７】
本発明はトナーの軟化温度Ｔｍが１００〜１６０℃であることが好ましい。Ｔｍが１００℃より低い場合、Ｔｇと同様に保存性が悪化する。また１６０℃より高い場合もＴｇと同様に二次定着における熱定着性が悪化する。
軟化温度Ｔｍの測定はフローテスターＣＦＴ−５００Ｃ（島津製作所）で測定する。測定条件は、押出圧力：１．９６１２ＭＰａ、昇温速度：６℃／ｍｉｎ、ダイ径：１．０ｍｍ、ダイ長さ：１．０ｍｍの条件下にて１／２流出した時の温度をＴｍとする。
【００２８】
本発明はトナーの溶融粘度が１０００ＰａＳとなる温度が１２０〜１７０℃であることが好ましい。１２０℃より低い場合、二次定着においてホットオフセット現象が発生し易くなる。また１７０℃より高い場合、二次定着における熱定着性が悪化する。
溶融粘度の測定はフローテスターＣＦＴ−５００Ｃ（島津製作所）で測定した値であり、測定条件は、押出圧力：１．９６１２ＭＰａ、昇温速度：６℃／ｍｉｎ、ダイ径：１．０ｍｍ、ダイ長さ：１．０ｍｍの条件下にて測定する。
なお、溶融粘度ηは下記の式により求める。
溶融粘度η＝τ／γ＝πＤ^４Ｐ／１２８ＬＱ
ただし、Ｐ：押出圧力（Ｐａ）Ｑ＝Ｘ／１０×Ａ／ｔ
Ｄ：ダイ径（ｍｍ）
Ｌ：ダイ長さ（ｍｍ）
ｔ：計測時間（ｓ）
Ｘ：計測時間ｔに対するピストンの移動量（ｍｍ）
Ａ：ピストンの断面積（ｍｍ^２）
溶融粘度ηが１０００ＰａＳとなる温度を求める。
【００２９】
本発明はトナーのゆるみ見掛け密度が０．３ｇ／ｃｃ以上であることが好ましい。０．３ｇ／ｃｃ未満の場合、トナーの凝集性が強くなり、感光体上でのトナー像厚みが不均一となり一次定着での転写、定着性が悪化する。
ゆるみ見掛け密度はパウダーテスター（ＰＴＮ型：ホソカワミクロン社製）を用い測定する。
【００３０】
本発明は感光体の表面摩擦係数が０．７０以下の有機光半導体であることが好ましい。該表面摩擦係数が０．７０より高い場合、一次定着で転写、定着する際に感光体との離型性が悪くなり、一次定着での画像品質が悪化する。
感光体の表面摩擦係数を低くする方法として、例えばステアリン酸亜鉛、ステアリン酸カルシウムなど脂肪酸金属塩を感光体表面に均一に塗布することや、感光体の電荷輸送層中にシリコーンオイルを含有させること等により可能であり、また最も一般的な手段はトナー中に添加する方法である。
表面摩擦係数の測定は協和界面化学（株）社製、全自動摩擦摩耗解析装置を用い測定する。この時接触子として３ｍｍステンレス球を用いる。
【００３１】
また、本発明は感光体が導電性支持体上に感光層と金属酸化物を含有した保護層を設けた感光体であることが好ましい。
金属酸化物を含有した保護層を設けた感光体を用いた場合、一次定着で加圧ロールによる圧力が加わっても機械的強度が強いため、感光体の膜削れが少なく、安定した画像品質を得ることができる。
また、感光体の保護層中に含有する金属酸化物としては、アルミナ、酸化チタン、シルカの中から選ばれる一種であることが望ましい。
保護層は耐摩耗性を向上する目的で、フッ素樹脂、シリコーン樹脂等の樹脂中にシリカ、アルミナ、酸化チタン、チタン酸バリウム、チタン酸マグネシウム、チタン酸カルシウム、チタン酸ストロンチウム、酸化亜鉛、酸化スズなどの各種金属酸化物を添加したものが用いられるが、特に膜削れ防止効果が高いアルミナ、酸化チタン、シリカが好ましい。
【００３２】
次に本発明に使用するトナーの材料について説明する。
本発明で使用される結着樹脂としては従来公知の樹脂が全て使用可能である。例えば、ポリスチレン、ポリ−α−メチルスチレン、スチレン−クロロスチレン共重合体、スチレン−プロピレン共重合体、スチレン−ブタジェン共重合体、スチレン−塩化ビニル共重合体、スチレン−酢酸ビニル共重合体、スチレン−マレイン酸共重合体、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−クロルアクリル酸メチル共重合体、スチレン−アクリロニトリル−アクリル酸エステル共重合体等のスチレン系樹脂（スチレンまたはスチレン置換体を含む単重合体または共重合体）、ポリエステル樹脂、エポキシ樹脂、塩化ビニル樹脂、ロジン変性マレイン酸樹脂、フェノール樹脂、ポリエチレン樹脂、ポリプロピレン樹脂、石油樹脂、ポリウレタン樹脂、ケトン樹脂、エチレン−エチルアクリレート共重合体、キシレン樹脂、ポリビニルブチラート樹脂などが挙げられる。
【００３３】
本発明では特にポリエステル樹脂が好ましい。ポリエステル樹脂は、アルコール成分とカルボン酸成分との縮重合によって得られる。使用されるアルコール成分としては、例えばエチレングリコール、ジエングリコール、トリエチレングリコール、プロピレングリコール等のグリコール類、１，４−ビス（ヒドロキシメタ）シクロヘキサン、及びビスフェノールＡ等のエーテル化ビスフェノール類、その他二価のアルコール単量体、三価以上の多価アルコール単量体を挙げることができる。また、カルボン酸成分としては、例えばマレイン酸、フマール酸、フタル酸、イソフタル酸、テレフタル酸、コハク酸、マロン酸等の二価の有機酸単量体、１，２，４−ベンゼントリカルボン酸、１，２，５−ベンゼントリカルボン酸、１，２，４−シクロヘキサントリカルボン酸、１，２，４−ナフタレントリカルボン酸、１，２，５−ヘキサントリカルボン酸、１，３−ジカルボキシル−２−メチレンカルボキシプロパン、１，２，７，８−オクタンテトラカルボン酸等の三価以上の多価カルボン酸単量体を挙げることができる。
【００３４】
また上記の樹脂は単独使用も可能であるが、二種類以上併用しても良い。
また、これら樹脂の製造方法も特に限定されるものではなく、塊状重合、溶液重合、乳化重合、懸濁重合いずれも使用できる。
【００３５】
本発明においてトナーに使用される離型剤として公知のものが全て使用できるが、特に脱遊離脂肪酸型カルナウバワックス、モンタンワックス及び酸化ライスワックスを単独又は組み合わせて使用することができる。
カルナウバワックスとしては、微結晶のものが良く、酸価が５以下であり、トナーバインダー中に分散した時の粒子径が１μｍ以下の粒径であるものが好ましい。
モンタンワックスについては、一般に鉱物より精製されたモンタン系ワックスを指し、カルナウバワックス同様、微結晶であり、酸価が５〜１４であることが好ましい。
酸化ライスワックスは、米ぬかワックスを空気酸化したものであり、その酸価は１０〜３０が好ましい。その他の離型剤としては、固形シリコーンワニス、高級脂肪酸高級アルコール、モンタン系エステルワックス、低分子量ポリプロピレンワックス等、従来公知のいかなる離型剤をも混合して使用できる。
これらの離型剤の使用量は、トナー樹脂成分１００重量部に対し、１〜２０重量部、好ましくは３〜１０重量部である。
【００３６】
また外添剤としては、無機微粒子を好ましく用いることができる。この無機微粒子の一次粒子径は、５ｍμ〜２μｍであることが好ましく、特に５ｍμ〜５００ｍμであることが好ましい。また、ＢＥＴ法による比表面積は、２０〜５００ｍ^２／ｇであることが好ましい。この無機微粒子の使用割合は、トナーの０．０１〜５重量％であることが好ましく、特に０．０１〜２．０重量％であることが好ましい。
無機微粒子の具体例としては、例えばシリカ、アルミナ、酸化チタン、チタン酸バリウム、チタン酸マグネシウム、チタン酸カルシウム、チタン酸ストロンチウム、酸化亜鉛、酸化スズ、ケイ砂、クレー、雲母、ケイ灰石、ケイソウ土、酸化クロム、酸化セリウム、ベンガラ、三酸化アンチモン、酸化マグネシウム、酸化ジルコニウム、硫酸バリウム、炭酸バリウム、炭酸カルシウム、炭化ケイ素、窒化ケイ素などを挙げることができる。
この他、高分子系微粒子たとえばソープフリー乳化重合や懸濁重合、分散重合によって得られるポリスチレン、メタクリル酸エステルやアクリル酸エステル共重合体やシリコーン、ベンゾグアナミン、ナイロンなどの重縮合系、熱硬化性樹脂による重合体粒子が挙げられる。
【００３７】
このような流動化剤は表面処理を行って、疎水性を上げ、高湿度下においても流動特性や帯電特性の悪化を防止することができる。例えばシランカップリング剤、シリル化剤、フッ化アルキル基を有するシランカップリング剤、有機チタネート系カップリング剤、アルミニウム系のカップリング剤などが好ましい表面処理剤として挙げられる。
【００３８】
本発明に使用するトナーには荷電制御剤をトナー粒子に内添、またはトナー粒子に外添して用いることが好ましい。荷電制御剤によって、現像システムに応じた最適の荷電量コントロールが可能となり、特に本発明では荷電制御剤を用いることにより前記のトナー濃度を制御しない現像方法に用いた場合、有効である。
トナーに用いられる荷電制御剤としては従来より公知の物でよく、正極性制御剤としては、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−ナフトスルフォン酸塩、テトラブチルアンモニウムテトラフルオロボレートなどの四級アンモニウム塩；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など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などのジオルガノスズボレートを単独あるいは２種類以上組み合わせて用いることができる。これらの中でも、ニグロシン系化合物、有機四級アンモニウム塩の如き極性制御剤が特に好ましく用いられる。
【００３９】
負極性制御剤としては、例えば有機金属化合物、キレート化合物が有効である。その例としてはアルミニウムアセチルアセトナート、鉄（II）アセチルアセトナート、３，５−ジタ−シャリ−ブチルサリチル酸クロム等があり、特にアセチルアセトン金属錯体、モノアゾ金属錯体、ナフトエ酸あるいはサリチル酸系の金属錯体または塩が好ましく、特にサリチル酸系金属錯体、モノアゾ金属錯体またはサリチル酸系金属塩が好ましい。
【００４０】
前記の荷電制御剤は、微粒子状として用いることが好ましく、具体的には、３μｍ以下の個数平均粒径が好ましい。
トナーに使用される荷電制御剤の使用量は、結着樹脂の種類、必要に応じて使用される添加剤の有無、分散方法を含めたトナー製造方法によって決定されるもので、一義的に限定されるものではないが、好ましくは結着樹脂１００重量部に対して、通常０．１〜２０重量部の範囲、好ましくは０．２〜１０重量部で用いられる。０．１重量部未満では、トナーの帯電量が不足し実用的でない。また２０重量部を越える場合にはトナーの帯電量が大きすぎ、キャリアとの静電的吸引力の増大のため、現像剤の流動性低下や、画像濃度の低下を招く。
【００４１】
本発明に用いるトナーの着色剤としては、従来からトナー用着色剤として使用されてきた顔料及び染料の全てが適用される。具体的には、カーボンブラック、ランプブラック、鉄黒、群青、ニグロシン染料、アニリンブルー、カルコオイルブルー、オイルブラック、アゾオイルブラックなど特に限定されないが、特にアセチレンブラックやケッチェンブラック等の導電性カーボンブラックを用いることによって、本発明に使用するトナーの体積固有抵抗値を制御するは可能である。
着色剤の使用量は、一般に結着樹脂１００重量部に対し１〜２０重量部、好ましくは３〜１０重量部である。
【００４２】
本発明のトナーの製造方法は、従来公知の方法でよく、粉砕法としては例えば結着樹脂、離型剤、着色剤、その他場合によっては荷電制御剤等をミキサー等を用いて混合し、熱ロール、エクストルーダー等の混練機を用い混練する。ここで、練り温度、練り速度等の混練条件を変更し、カーボンブラックの分散性を変えることにより、本発明に使用するトナーの体積固有抵抗値を制御することは可能である。混練後は冷却固化し、これをジェットミル、ターボジェット、クリプトロン等の粉砕機で粉砕し、その後分級し得られる。
上記トナーに無機無粉末を添加するにはスーパーミキサー、ヘンシェルミキサーなどの混合機を用いる。
【００４３】
本発明の画像形成方法は、一成分現像方式でも、また二成分現像方式でも行なうことができる。
二成分現像方式の場合、本発明において現像剤を構成するキャリアの核体粒子としては、公知のものでよく例えば鉄、コバルト、ニッケル等の強磁性金属；マグネタイト、ヘマタイト、フェライトなどの合金や化合物；前記強磁性体微粒子と樹脂との複合体等が挙げられる。
本発明で用いられるキャリアはより耐久性を長くする目的で、表面を樹脂で被覆する構成になっていてもよい。
被覆層を形成する樹脂としては、例えばポリエチレン、ポリプロピレン、塩素化ポリエチレン、クロロスルホン化ポリエチレン等のポリオレフィン系樹脂；ポリスチレン、アクリル系樹脂（例えばポリメチルメタクリレート）、ポリアクリロニトリル、ポリビニルアセテート、ポリビニルアルコール、ポリビニルブチラール、ポリ塩化ビニル、ポリビニルカルバゾール、ポリビニルエーテル、ポリビニルケトン等のポリビニル及びポリビニリデン系樹脂；塩化ビニル−酢酸ビニル共重合体；オルガノシロキサン結合からなるシリコーン樹脂又はその変成品（例えばアルキッド樹脂、ポリエステル樹脂、エポキシ樹脂、ポリウレタン等による変成品）；ポリテトラフルオロエチレン、ポリ弗化ビニル、ポリ弗化ビニリデン、ポリクロロトリフルオロエチレン等の弗素系樹脂；ポリアミド；ポリエステル；ポリウレタン；ポリカーボネート；尿素−ホルムアルデヒド樹脂等のアミノ樹脂；エポキシ樹脂等が挙げられるが、中でも本発明で使用する被覆樹脂としてはトナースペントに対する余裕度が高いシリコーン樹脂又はその変成品が好ましい。
【００４４】
シリコーン系樹脂としては、従来から知られているいずれのシリコーン系樹脂であってもよく、下記式（１）で示されるオルガノシロキサン結合のみからなるストレートシリコーン及びアルキド、ポリエステル、エポキシ、ウレタンなどで変成したシリコーン樹脂が挙げられる。
【化１】

（式中、Ｒ_１は水素原子、炭素原子数１〜４のアルキル基又はフェニル基、Ｒ_２及びＲ_３は水素原子、炭素原子数１〜４のアルコキシ基、フェニル基、フェノキシ基、炭素原子数２〜４のアリケニル基、炭素原子数２〜４のアルケニルオキシ基、ヒドロキシ基、カルボキシル基、エチレンオキシド基、グリシジル基又は下記式（２）で示される基である。
【化２】

上記式中Ｒ_４、Ｒ_５はヒドロキシ基、カルボキシル基、炭素原子数１〜４のアルキル基、炭素原子数１〜４のアルコキシ基、炭素原子数２〜４のアルケニル基、炭素原子数２〜４のアルケニルオキシ基、フェニル基、フェノキシ基、ｋ、ｌ、ｍ、ｎ、ｏ、ｐは１以上の整数を示す。
上記各置換基は未置換のもののほか、例えばアミノ基、ヒドロキシ基、カルボキシル基、メルカプト基、アルキル基、フェニル基、エチレンオキサイド基、グリシジル基、ハロゲン原子のような置換基を有してもよい。）
【００４５】
また本発明で用いられるキャリアは、その体積固有抵抗を制御するために被覆層中に導電性付与材料を分散しても良い。分散される導電性付与材料は従来より公知の物でよく、例えば鉄、金、銅等の金属；フェライト、マグネタイト等の酸化鉄；カーボンブラック等の顔料が挙げられる。
この中でも特にカーボンブラックの一つであるファーネスブラックとアセチレンブラックの混合物を用いることにより、少量の導電性微粉末の添加で効果的に導電性の調整が可能で、更に被覆層の耐摩耗性に優れたキャリアを得ることが可能である。これらの導電性微粉末は、粒径０．０１〜１０μｍ程度のものが好ましく、被覆樹脂１００重量部に対して２〜３０重量部添加されることが好ましく、さらには５〜２０重量部が好ましい。
【００４６】
また、キャリア被覆層中には核体粒子との接着性を向上させたり導電性付与剤の分散性を向上させる目的でシランカップリング剤、チタンカップリング剤等を添加しても良い。
本発明で用いるシランカップリング剤としては、下記一般式で示される化合物である。
【化３】
ＹＲＳｉＸ_３
（式中、Ｘはけい素原子に結合している加水分解基で、例えばクロル基、アルコキシ基、アセトキシ基、アルキルアミノ基、プロペノキシ基、Ｙは有機マトリックスと反応する有機官能基で、例えばビニル基、メタクリル基、エポキシ基、グリシドキシ基、アミノ基、メルカプト基などが挙げられる。Ｒは炭素原子数１〜２０のアルキル基又はアルキレン基である。）
前記シランカップリング剤の中でも、特に負帯電性を有する現像剤を得るにはＹにアミノ基を有するアミノシランカップリング剤が好ましく、正帯電性を有する現像剤を得るにはＹにエポキシ基を有するエポキシシランカップリング剤が好ましい。
【００４７】
被覆層の形成法としては、従来と同様、キャリア核体粒子の表面に被覆層形成液を噴霧法、浸漬法等の手段で塗布すればよい。被覆層の厚さは０．１〜２０μｍが好ましい。
また、現像剤として使用する際は通常キャリア１００重量部に対してトナーが２〜１０重量部の割合で混合し、現像剤として用いることが好ましい。
【００４８】
次に本発明において用いられる電子写真感光体について説明する。
本発明においては、導電性基体上に感光層を設けてなる電子写真感光体として広く一般に知られたものを使用することができるが、低価格、生産性及び無公害等の利点を有する有機系の感光材料を用いたものが好ましく、中でも電荷発生物質と電荷移動物質とを組み合わせて用いる機能分離型の感光体が性能面から最も好ましく用いられる。
本発明において用いることのできるドラム状の導電性支持体としては、Ａｌ、Ｎｉ、Ｆｅ、Ｃｕ、Ａｕ等の金属または合金；ポリエステル、ポリカーボネート、ポリイミド等のプラスチック又はガラス等の絶縁性基板上にＡｌ、Ａｇ、Ａｕ等の金属膜又はＩｎ_２Ｏ_３、ＳｎＯ_２等の金属酸化物膜を設けたもの等が例示できる。
機能分離型の感光体は、これらの導電性支持体上に電荷発生層と電荷輸送層とを積層して形成される。電荷発生層は電荷発生物質のみから形成されていても、あるいは電荷発生物質がバインダー樹脂中に均一に分散されて形成されていてもよい。電荷発生層はこれらの成分を適当な溶媒中に分散し、これを導電性支持体上に塗布、乾燥することにより形成される。
【００４９】
電荷発生物質としては、例えばシーアイピグメントブルー２５（カラーインデックス（ＣＩ）２１１８０）、シーアイピグメントレッド５２（ＣＩ４５１００）、シーアイベーシックレッド３（ＣＩ４５２１０）等の他に、ポルフィリン骨格を有するフタロシアニン系顔料、カルバゾール骨格を有するアゾ顔料（特開昭５３−９５０３３号に記載）、スチルベン骨格を有するアゾ顔料（特開昭５３−１３８２２９号に記載）、ジスチリルベンゼン骨格を有するアゾ顔料（特開昭５３−１３３４５５号に記載）、トリフェニルアミン骨格を有するアゾ顔料（特開昭５３−１３２５４７号に記載）、ジベンゾチオフェン骨格を有するアゾ顔料（特開昭５４−２１７２８号に記載）、オキサジアゾール骨格を有するアゾ顔料（特開昭５４−１２７４２号に記載）、フルオレノン骨格を有するアゾ顔料（特開昭５４−２２８３４号に記載）、ビススチルベン骨格を有するアゾ顔料（特開昭５４−１７７３３号に記載）、ジスチリルオキサジアゾール骨格を有するアゾ顔料（特開昭５４−２１２９号に記載）、ジスチリルカルバゾール骨格を有するアゾ顔料（特開昭５４−１７７３４号に記載）、カルバゾール骨格を有するトリスアゾ顔料（特開昭５７−１９５７６７号、同５７−１９５７５８号に記載）、等、更にはシーアイピグメントブルー１６（ＣＩ７４１００）等のフタロシアニン系顔料、シーアイバットブラウン５（ＣＩ１７３４１０）等のインジゴ顔料、アルゴスカーレッドＢ（バイオレット社製）インダンスレンスカーレットＲ（バイエル社製）等のペリレン系顔料、スクエアリック顔料等の有機顔料：Ｓｅ、Ｓｅ合金、ＣｄＳ、アモルファスＳｉ等の無機顔料を使用することができる。
【００５０】
バインダー樹脂としては、ポリアミド、ポリウレタン、ポリエステル、エポキシ樹脂、ポリケトン、ポリカーボネート、シリコーン樹脂、アクリル樹脂、ポリビニルブチラール、ポリビニルホルマール、ポリビニルケトン、ポリスチレン、ポリ−Ｎ−ビニルカルバゾール、ポリアクリルアミド等が用いられる。
バインダー樹脂の量は、電荷発生物質１００重量部に対して通常５〜１００重量部、好ましくは１０〜５０重量部が適当である。
ここで用いられる溶媒としてはテトラヒドロフラン、シクロヘキサノン、ジオキサン、ジクロロエタン、シクロヘキサン、メチルエチルケトン、１，１，２−トリクロロエタン、１，１，２，２−テトラクロロエタン、ジクロロメタン、エチルセルソルブ等の単独溶媒または混合溶媒が好ましい。
電荷発生層の平均膜厚は、通常０．０１〜２μｍ、好ましくは０．１〜１μｍである。
【００５１】
電荷輸送層は電荷輸送物質、バインダー樹脂及び必要ならば可塑剤、レベリング剤を適当な溶媒に溶解し、これを電荷発生層上に塗布し乾燥することにより形成される。
電荷輸送物質としては、ポリ−Ｎ−ビニルカルバゾール及びその誘導体、ポリ−γ−カルバゾリルエチルグルタメート及びその誘導体、ピレン−ホルムアルデヒド縮合物及びその誘導体、ポリビニルピレン、ポリビニルフェナントレン、オキサゾール誘導体、イミダゾール誘導体、トリフェニルアミン誘導体、９−（ｐ−ジエチルアミノスチリル）アントラセン、１，１−ビス（４−ジベンジルアミノフェニル）プロパン、スチリルアントラセン、スチリルピラゾリン、フェニルヒドラゾン類、α−スチルベン誘導体等の電子供与性物質が挙げられる。
【００５２】
バインダー樹脂としては、ポリスチレン、スチレン−アクリロニトリル共重合体、スチレン−ブタジエン共重合体、スチレン−無水マレイン酸共重合体、ポリエステル、ポリ塩化ビニル、塩化ビニル−酢酸ビニル共重合体、ポリ酢酸ビニル、ポリ塩化ビニル、ポリ塩化ビニリデン、ポリアクリレート樹脂、フェノキシ樹脂、ポリカーボネート、酢酸セルロース樹脂、エチルセルロース樹脂、ポリビニルブチラール、ポリビニルホルマール、ポリビニルトルエン、ポリ−Ｎ−ビニルカルバゾール、アクリル樹脂、シリコーン樹脂、エポキシ樹脂、メラミン樹脂、ウレタン樹脂、フェノール樹脂、アルキッド樹脂等の熱可塑性または熱硬化性樹脂が挙げられる。
電荷輸送層を形成するための溶媒としては、テトラヒドロフラン、ジオキサン、トルエン、モノクロルベンゼン、１，２−ジクロロエタン、シクロヘキサノン、ジクロロメタン、１，１，２−トリクロロエタン、１，１，２，２−テトラクロロエタン及びこれらの混合溶媒が望ましい。
電荷輸送層の膜厚は、通常１０〜１００μｍ、好ましくは２０〜４０μｍである。
【００５３】
尚、本発明においては、接着性、電荷ブロッキング性を向上させるために、必要に応じて導電性支持体と電荷発生層との間に中間層を設けてもよい。また、導電性基体上に電荷輸送層、電荷発生層の順に積層された逆層構造をとっていても良く、また最表面層が耐摩耗性向上等の目的で設けられた保護層であっても良い。
【００５４】
本発明においては、感光体の電荷輸送層中にシリコーンオイルを含有させることによって、感光体の表面摩擦係数を任意に制御できる。
本発明において用いることのできるシリコーンオイルとしては一般に上市されているものであれば何でも良く、例えばジメチルシリコーンオイル、メチルフェニ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などのストレートシリコーンオイルの他に、アルキル変性、アミノ変性、カルボキシル変性、高級脂肪酸変性、エポキシ変性、アルコール変性、ポリエーテル変性、アルキル・ポリエーテル変性、フッ素変性等に代表される各種変性シリコーンオイルのいずれも好ましく用いることができる。
また、本発明におけるこれらのシリコーンオイルの添加量は、電荷輸送層中の樹脂に対して０．０１重量％以上が好ましく、より好ましくは０．０１〜５重量％の範囲が良い。０．０１重量％未満である場合には、シリコーンオイルによる摩擦係数低減の効果が十分に発揮されず、本発明の効果を得ることができない。また、添加量が５重量％より多くなると、逆に感光体表面の付着力が増し、良好な転写特性を維持することが難しくなる。
【００５５】
【実施例】
以下実施例を用いて本発明を具体的に説明するが、本発明はこれらに限定されるものではない。
【００５６】
参考例１
＜トナー処方＞
ポリエステル樹脂 ８９重量部
（重量平均分子量：３２５０００、Ｔｇ：６７．５℃）
ポリエチレンワックス（分子量９００） ５重量部
カーボンブラック（三菱化成 ＃４４） ５重量部
荷電制御剤（スピロンブラックＴＲ−Ｈ：保土谷化学） １重量部
以上の処方で２軸エクストルーダーを用いて１５０℃で混練後、気流式粉砕機により粉砕、分級し、重量平均粒径７．０μｍ（重量平均粒径／個数平均粒径１．４０）とした後、ヘンシェルミキサーを用い、シリカ（Ｒ−９７２ 日本アエロジル）０．５重量％を混合して表２に示す物性を有するトナーＡを得た。
キャリアとしては平均粒径５０μｍのマグネタイト粒子にメチルメタクリレート樹脂（ＭＭＡ）をコート（膜厚０．５μｍ）したものを用い、トナー濃度５．０重量％の割合で混合し参考例１の現像剤を得た。
【００５７】
参考例２
＜トナー処方＞
ポリエステル樹脂 ８９重量部
（重量平均分子量：３２５０００、Ｔｇ：６７．５℃）
ポリエチレンワックス（平均粒径：９００μｍ） ５重量部
カーボンブラック（三菱化成 ＃４４） ８重量部
荷電制御剤（スピロンブラックＴＲ−Ｈ：保土谷化学） １重量部
以上の処方で２軸エクストルーダーを用いて１２０℃で混練後、気流式粉砕機により粉砕、分級し、重量平均粒径５．０μｍ（重量平均粒径／個数平均粒径１．２０）とした後、ヘンシェルミキサーを用い、シリカ（Ｒ−９７２ 日本アエロジル）０．５重量％を混合して表２に示す物性を有するトナーＢを得た。
キャリアとしては平均粒径５０μｍのマグネタイト粒子にメチルメタクリレート樹脂（ＭＭＡ）をコート（膜厚０．５μｍ）したものを用い、トナー濃度５．０重量％の割合で混合し参考例２の現像剤を得た。
【００５８】
実施例１
＜トナー処方＞
スチレン−ｎ−ブチルアクリレート共重合体 ８８重量部
（重量平均分子量：５５０００、Ｔｇ：５２℃）
ポリエチレンワックス（平均粒径：９００μｍ） ５重量部
カーボンブラック（三菱化成 ＃４４） １０重量部
荷電制御剤（スピロンブラックＴＲ−Ｈ：保土谷化学） １重量部
以上の処方で２軸エクストルーダーを用いて１２０℃で混練後、機械式粉砕機により粉砕、分級し、重量平均粒径４．５μｍ（重量平均粒径／個数平均粒径１．２９）とした後、ヘンシェルミキサーを用い、シリカ（Ｒ−９７２ 日本アエロジル）０．５重量％を混合して表２に示す物性を有するトナーＣを得た。
キャリアとしては平均粒径５０μｍのマグネタイト粒子にメチルメタクリレート樹脂（ＭＭＡ）をコート（膜厚０．５μｍ）したものを用い、トナー濃度５．０重量％の割合で混合し実施例１の現像剤を得た。
【００５９】
実施例２
＜トナー処方＞
ポリエステル樹脂 ８９重量部
（重量平均分子量：２８００００、Ｔｇ：６１℃）
カルナウバワックス（平均粒径：３００μｍ） ５重量部
カーボンブラック（三菱化成 ＃４４） ６重量部
荷電制御剤（スピロンブラックＴＲ−Ｈ：保土谷化学） １重量部
以上の処方で２軸エクストルーダーを用いて１８０℃で混練後、機械式粉砕機により粉砕、分級し、重量平均粒径９．５μｍ（重量平均粒径／個数平均粒径１．１０）とした後、ヘンシェルミキサーを用い、シリカ（Ｒ−９７２ 日本アエロジル）０．５重量％を混合して表２に示す物性を有するトナーＤを得た。
キャリアとしては平均粒径５０μｍのマグネタイト粒子にメチルメタクリレート樹脂（ＭＭＡ）をコート（膜厚０．５μｍ）したものを用い、トナー濃度５．０重量％の割合で混合し実施例２の現像剤を得た。
【００６０】
実施例３
＜トナー処方＞
ポリエステル樹脂 ４０重量部
（重量平均分子量：３１００００、Ｔｇ：６８℃）
スチレン−ｎ−ブチルアクリレート共重合体 ４８重量部
（重量平均分子量：８５０００、Ｔｇ：６０℃）
カルナウバワックス ４重量部
カーボンブラック（三菱化成 ＃４４） ５重量部
荷電制御剤（スピロンブラックＴＲ−Ｈ：保土谷化学） １重量部
以上の処方で２軸エクストルーダーを用いて１００℃で混練後、機械式粉砕機により粉砕、分級し、重量平均粒径８．５μｍ（重量平均粒径／個数平均粒径１．１５）とした後、ヘンシェルミキサーを用い、シリカ（Ｒ−９７２ 日本アエロジル）０．５重量％を混合して表２に示す物性を有するトナーＥを得た。
キャリアとしては平均粒径５０μｍのマグネタイト粒子にメチルメタクリレート樹脂（ＭＭＡ）をコート（膜厚０．５μｍ）したものを用い、トナー濃度５．０重量％の割合で混合し実施例３の現像剤を得た。
【００６１】
実施例４
＜トナー処方＞
ポリエステル樹脂 ８０重量部
（重量平均分子量：３１００００、Ｔｇ：６８℃）
スチレン−ｎ−ブチルアクリレート共重合体 ２０重量部
（重量平均分子量：８５０００、Ｔｇ：６０℃）
カルナウバワックス ４重量部
カーボンブラック（三菱化成 ＃４４） ８重量部
荷電制御剤（スピロンブラックＴＲ−Ｈ：保土谷化学） １重量部
以上の処方で２軸エクストルーダーを用いて１２０℃で混練後、機械式粉砕機により粉砕、分級し、重量平均粒径８．５μｍ（重量平均粒径／個数平均粒径１．２０）とした後、ヘンシェルミキサーを用い、シリカ（Ｒ−９７２ 日本アエロジル）０．５重量％を混合して表２に示す物性を有するトナーＦを得た。
キャリアとしては平均粒径５０μｍのマグネタイト粒子にメチルメタクリレート樹脂（ＭＭＡ）をコート（膜厚０．５μｍ）したものを用い、トナー濃度５．０重量％の割合で混合し実施例４の現像剤を得た。
【００６２】
実施例５
＜トナー処方＞
ポリエステル樹脂 ５０重量部
（重量平均分子量：３１００００、Ｔｇ：６８℃）
スチレン−ｎ−ブチルアクリレート共重合体 ４５重量部
（重量平均分子量：８５０００、Ｔｇ：６０℃）
カルナウバワックス ５重量部
カーボンブラック（三菱化成 ＃４４） ６重量部
荷電制御剤（スピロンブラックＴＲ−Ｈ：保土谷化学） １重量部
以上の処方で２軸エクストルーダーを用いて１４０℃で混練後、機械式粉砕機により粉砕、分級し、重量平均粒径９．０μｍ（重量平均粒径／個数平均粒径１．２５）とした後、ヘンシェルミキサーを用い、シリカ（Ｒ−９７２ 日本アエロジル）０．８重量％を混合して表２に示す物性を有するトナーＧを得た。
キャリアとしては平均粒径５０μｍのマグネタイト粒子にメチルメタクリレート樹脂（ＭＭＡ）をコート（膜厚０．５μｍ）したものを用い、トナー濃度５．０重量％の割合で混合し実施例５の現像剤を得た。
【００６３】
実施例６
＜トナー処方＞
ポリエステル樹脂 ３０重量部
（重量平均分子量：３１００００、Ｔｇ：６８℃）
スチレン−ｎ−ブチルアクリレート共重合体 ５９重量部
（重量平均分子量：８５０００、Ｔｇ：６０℃）
カルナウバワックス ５重量部
カーボンブラック（三菱化成 ＃４４） ５重量部
荷電制御剤（スピロンブラックＴＲ−Ｈ：保土谷化学） １重量部
以上の処方で２軸エクストルーダーを用いて１００℃で混練後、機械式粉砕機により粉砕、分級し、重量平均粒径９．０μｍ（重量平均粒径／個数平均粒径１．２０）とした後、ヘンシェルミキサーを用い、シリカ（Ｒ−９７２ 日本アエロジル）１．０重量％、ステアリン酸亜鉛微粉末０．２重量％を混合し、を混合して表２に示す物性を有するトナーＨを得た。
キャリアとしては平均粒径５０μｍのマグネタイト粒子にメチルメタクリレート樹脂（ＭＭＡ）をコート（膜厚０．５μｍ）したものを用い、トナー濃度５．０重量％の割合で混合し実施例６の現像剤を得た。
【００６４】
実施例７
実施例６において、感光体としてシリカを１５重量％含有する保護層を設けた有機感光体を使用した以外は実施例６と同様にした。
【００６５】
比較例１
＜トナー処方＞
ポリエステル樹脂 ８９重量部
（重量平均分子量：３２５０００、Ｔｇ：６７．５℃）
ポリエチレンワックス ５重量部
（平均粒径：９００μｍ）
ケッチェンブラック（ケッチェンブラックＥＣ
：ケッチェンブラックインターナショナル） ３重量部
荷電制御剤（スピロンブラックＴＲ−Ｈ：保土谷化学） １量量部
以上の処方で２軸エクストルーダーを用いて１００℃で混練後、機械式粉砕機により粉砕、分級し、重量平均粒径８．５μｍ（重量平均粒径／個数平均粒径１．３３）とした後、ヘンシェルミキサーを用い、シリカ（Ｒ−９７２ 日本アエロジル）０．８重量％を混合して表２に示す物性を有するトナーＪを得た。
キャリアとしては平均粒径５０μｍのマグネタイト粒子にメチルメタクリレート樹脂（ＭＭＡ）をコート（膜厚０．５μｍ）したものを用い、トナー濃度５．０重量％の割合で混合し比較例１の現像剤を得た。
【００６６】
比較例２
＜トナー処方＞
ポリエステル樹脂 ８９重量部
（重量平均分子量：３２５０００、Ｔｇ：６７．５℃）
ポリエチレンワックス（平均粒径：９００μｍ） ５重量部
カーボンブラック（三菱化成 ＃４４） １０重量部
荷電制御剤（スピロンブラックＴＲ−Ｈ：保土谷化学） １重量部
以上の処方で２軸エクストルーダーを用いて１００℃で混練後、機械式粉砕機により粉砕、分級し、重量平均粒径２．５μｍ（重量平均粒径／個数平均粒径１．２０）とした後、ヘンシェルミキサーを用い、シリカ（Ｒ−９７２ 日本アエロジル）０．５重量％を混合して表２に示す物性を有するトナーＫを得た。
キャリアとしては平均粒径５０μｍのマグネタイト粒子にメチルメタクリレート樹脂（ＭＭＡ）をコート（膜厚０．５μｍ）したものを用い、トナー濃度５．０重量％の割合で混合し比較例２の現像剤を得た。
【００６７】
比較例３
比較例２のトナーを、重量平均粒径１０．５μｍ（重量平均粒径／個数平均粒径１．４０）とした後、ヘンシェルミキサーを用い、シリカ（Ｒ−９７２ 日本アエロジル）１．０重量％を混合して表２に示す物性を有するトナーＬを得た。
キャリアとしては平均粒径５０μｍのマグネタイト粒子にメチルメタクリレート樹脂（ＭＭＡ）をコート（膜厚０．５μｍ）したものを用い、トナー濃度５．０重量％の割合で混合し比較例３の現像剤を得た。
【００６８】
（評価法）
ｉｍａｇｉｏＭＦ７０７０（リコー製複写機）の転写、定着部を改造して図１のユニット構成にした試験機（一次定着圧：１５０Ｎ／ｃｍ^２、二次定着圧：９．３Ｎ／ｃｍ^２、温度１６５℃）にてプリントしたサンプルを得る。次にプリント画像のドットで作られたグレークケール（ハーフトーン部）を、大日本スクリーン社のＧｅｎａＳｃａｎ５０００スキャナで１０００ｄｐｉにて読み込み、画像データを得る。この画像データから、濃度分布に変換し、前記式（３）にて粒状度を評価する。また画像データから１次定着時および２次定着時の定着性を評価した。評価方法は以下の通りである。また初期の感光体摩擦係数をそれぞれ測定した。
◎定着性の評価方法
一次定着性：一次定着後の画像にメンデイングテープ（３Ｍ社製）を貼り、重量１Ｋｇのスチール製ローラを用い、幅２．５ｃｍの画像上を一往復させる。その後テープを、ゆっくり引き剥がす。その前後の画像濃度をマクベス濃度計により測定し、下記式にて定着率を算出する。
二次定着性：一次定着を行わず、別のプリンタのチャージャーにより転写して、二次定着定着のみ行った画像にメンデイングテープ（３Ｍ社製）を貼り、重量１Ｋｇのスチール製ローラを用い、幅２．５ｃｍの画像上を一往復させる。その後テープを、ゆっくり引き剥がす。その前後の画像濃度をマクベス濃度計により測定し、下記式にて定着率を算出する。
定着率（％）＝（テープ付着引き剥がし後の画像濃度／テープ付着引き剥がし前の画像濃度）×１００
◎画像品質
粒状度の評価
ｉｍａｇｉｏＭＦ７０７０（リコー製複写機）の転写、定着部を改造して図１のユニット構成にした試験機にてプリントしたサンプルを得る。次にプリント画像のドットで作られたグレークケール（ハーフトーン部）を、大日本スクリーン社のＧｅｎａＳｃａｎ５０００スキャナで１０００ｄｐｉにて読み込み、画像データを得る。画像データから、濃度分布に変換し、前記式（３）にて粒状度を評価する。
評価結果は表３に示す。
【００６９】
【表２】

【００７０】
【表３】

【００７１】
【発明の効果】
本発明は、感光体上のトナー像を転写紙に対して圧力のみで転写同時定着する一次定着後、更に一次定着した転写紙上のトナー像を定着ローラで加熱加圧定着する二次定着を行なう画像形成方法において、トナーとして体積個有抵抗が１×１０^９Ω・ｃｍ以上で、重量平均粒径が３．０〜１０．０μｍの非磁性トナーを用いることによって、転写時に画像劣化を生じない高品位の画質の画像を得ることができる画像形成方法を提供することができる。
【図面の簡単な説明】
【図１】本発明で用いる画像形成装置全体の概略構成図。
【符号の説明】
１ 感光体
２ 帯電手段
３ 露光手段
３１ スキャナー
３２ レーザー光
３３ ミラー
４ 現像手段（現像装置）
４１ 現像スリーブ
５ 転写手段
５２ 転写ローラ
５３ 転写ベルト
５４ ベルト駆動用ローラ
５５ クリーニングブレード
６ クリーニング手段
６１ クリーニングブレード
６２ ファーブラシ
６３ ファーブラシクリーニング部材
７ 定着手段
７１ 定着ローラ
７２ 加圧ローラ
７３ 加熱手段（ヒータ）
７４ 加熱手段（ヒータ）
１０１ 転写材バンク
１０２ 給紙ローラ
１０３ 給紙コロ
１０４ レジストコロ
１０５ 排紙コロ
１０６ 転写材バンク
１０７ 給紙ローラ
１０８ 給紙コロ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electrophotographic image forming method, and more particularly to an image forming method using an image forming apparatus such as a printer or a copier that employs the image forming method.
[0002]
[Prior art]
An electrophotographic image forming method requires many steps. That is, the document is converted into an electric signal by a scanner or an optical system. In the case of a printer, input directly with a plotter signal. Next, an electric signal is written on the photosensitive member as an optical image by writing an electric signal with a laser or the like, and an electrostatic latent image is formed on the charged photosensitive member. A colored fine powder represented by toner is electrostatically attached to the latent image in the development process. Further, it is electrostatically transferred to transfer paper in the transfer process. Recently, in the color field, a system in which toner images of 3 to 4 colors are transferred onto an intermediate transfer member and transferred onto a transfer paper is often used. Then, the toner is melted and fixed on the transfer paper by heat or the like to form an image.
[0003]
Deterioration of an image (including a latent image) occurs in all the steps described above. As is well known, image deterioration is particularly significant in the development, transfer, and fixing steps.
Among these, the development process has been improved by reducing the diameter of the toner, making it spherical, and reducing the diameter of the carrier. Currently, image degradation due to dust, smudges, etc. in the transfer process is large. In the fixing process, the toner may be deteriorated due to the spread of the toner image due to the melting of the toner in the process of fusing the toner to the transfer paper.
Due to the above deterioration phenomenon, image deterioration is particularly large in the transfer process.
[0004]
Therefore, it has been proposed to perform the transfer process and the fixing process simultaneously.
For example, Japanese Patent Application Laid-Open No. 55-87156 proposes a method of simultaneously transferring and fixing to a sheet using a heat fixing roll using an amorphous silicone photoreceptor. Japanese Laid-Open Patent Publication No. 6-175512 also proposes a method of simultaneously transferring and fixing with thermal energy using a polymerized toner.
Japanese Patent Application Laid-Open No. 7-5776 proposes a method of applying a transfer bias to a pressure roller using an amorphous silicone photoreceptor and using a capsule toner as a toner. As a method using a capsule toner, many proposals such as Japanese Patent Application Laid-Open Nos. 5-107796 and 6-230599 have been proposed.
In any case, the pressure is large, the mechanism and the transfer paper are large as a system, and it has become a practical problem and has not been put into practical use.
[0005]
As described above, the method of fixing at the same time as transfer with heat or pressure has been proposed as a technique for complete fixing. However, in the system in which transfer and fixing are performed simultaneously with heat, the temperature around the photosensitive member becomes high, and a large stress is applied to the toner in a developing and cleaning device, and there is a great practical problem.
In addition, in the method in which transfer fixing is performed only by pressure, 980 N / cm from the viewpoint of transfer fixing property.²There are disadvantages such as an increase in the size of the apparatus and occurrence of wrinkles on the transfer paper.
In addition, although the capsule toner is used in the above-mentioned publications, the capsule toner has many problems in practical use, in particular, there is a problem that development and fixing are not compatible, and the cost is too high. It is currently not used for general purposes.
[0006]
[Problems to be solved by the invention]
In view of these problems, the present invention provides an image forming apparatus that can use a generally manufactured toner obtained by a conventionally known pulverization method or polymerization method without using a capsule toner. Transfer without image degradation due to image quality, that is, a method of fixing toner to transfer paper at the time of transfer, and by lowering the pressure at the time of transfer and fixing that has been reported so far, high quality image quality without image degradation. An object is to provide an image forming method capable of obtaining an image.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, the inventors of the present invention include an image forming apparatus including a photosensitive drum, a transfer unit including a transfer conveyance belt, and the toner image formed on the photosensitive drum is a photosensitive member. By applying pressure to the transfer paper sandwiched between the transfer means, the toner adheres to the transfer paper simultaneously with the transfer, and the toner image on the transfer paper fixed simultaneously with the transfer only by the pressure is conveyed by the transfer belt. In addition, the present inventors have found that a high-quality image without image deterioration can be obtained at the time of transfer by fixing by passing through a heat fixing means provided in a downstream process, and the present invention has been completed.
[0008]
  That is, according to the present invention, the following (1) to (7) Image forming method.
(1) A development process for developing the electrostatic latent image formed on the photoreceptor with dry toner, a primary fixing process for simultaneously transferring and fixing the formed toner image to the transfer paper only with pressure, and a primary process An image forming method having a secondary fixing step of fixing a toner image on a fixed transfer paper by passing it through a heat and pressure fixing device having a fixing roller,The surface pressure in the primary fixing step is 100 to 200 N / cm. ² AndThe toner has a volume resistivity of 1 × 10⁹Ω · cm or more, weight average particle size of 3.0 to 10.0 μm,Dispersion degree of particle diameter (weight average particle diameter / number average particle diameter) is 1.3 or less, and average circularity is 0.92 to 0.99.An image forming method using a non-magnetic toner.
(2The glass transition temperature Tg of the toner is 50 to 65 ° C. (1)InThe image forming method described.
(3The toner has a softening temperature Tm of 100 to 160 ° C. (1)Or (2)The image forming method described.
(4The temperature at which the melt viscosity of the toner becomes 1000 PaS is 120 to 170 ° C.3The image forming method according to any one of the above.
(5(1) The apparent density of loosening of the toner is 0.3 g / cc or more.4The image forming method according to any one of the above.
(6) The photoconductor is an organic optical semiconductor having a surface friction coefficient of 0.70 or less.5The image forming method according to any one of the above.
(7(1) to (1), wherein the photoconductor is an organic photoconductor provided with a protective layer containing a photoconductive layer and a metal oxide on a conductive support.6The image forming method according to any one of the above.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a schematic view of the entire image forming apparatus used in the present invention.
The image forming apparatus includes a drum-shaped photoreceptor 1 that is a recording medium using a known electrophotographic system. Around the photosensitive member 1, a charger 2, an exposure unit 3, a developing unit 4, a transfer unit 5, a cleaning unit 6, and a fixing unit 7 for performing an electrophotographic copying process are arranged along a rotation direction indicated by an arrow. Yes.
[0010]
The exposure means 3 converts the data read by the scanner 31 and an image signal sent from the outside such as a PC (not shown), scans the laser beam 32 with a polygon motor, and based on the image signal read through the mirror 33, the photosensitive member. An electrostatic latent image is formed on 1. As the photoconductor 1, an existing photoconductor such as an amorphous material can be used in addition to the organic photoconductor.
The electrostatic latent image formed on the photoreceptor 1 is supplied with toner images formed by the developing unit 4 from transfer material banks 101 and 106 in which transfer materials for transferring the toner images are stored. Paper is fed by paper rollers 102 and 107 and fed by paper feed rollers 103 and 108. A roller 104 is a resist roller 104 for conveying a transfer material in synchronization with the toner image on the photosensitive member. The transfer material is sent to the transfer means 5 and electrostatically transferred. The transfer material on which the toner image is placed is conveyed and fixed to the fixing means 7 through the transfer belt 53 and then discharged outside the apparatus.
On the other hand, the untransferred portion and the photosensitive member 1 with dirt are cleaned by the cleaning means 6 and enters the next image forming step.
[0011]
The fixing unit 7 is necessary in the present invention in order to completely fix the toner semi-dissolved by the transfer unit 5 (described later).
The basic configuration includes a fixing roller 71 having heating means 74 (hereinafter referred to as “heater”) such as a halogen lamp, and a pressure roller 72 that is in pressure contact.
In the fixing roller 71, for example, an elastic layer such as silicone rubber having a rubber hardness of about 42 HS (Asuka C) is provided on the surface of a core metal (not shown) having an outer diameter of φ50, preferably 400 μm thick, and further adhered due to the viscosity of the toner. In order to prevent this, a resin surface layer having good releasability such as a fluororesin is formed. The thickness of the elastic layer is usually preferably about 100 to 500 μm in consideration of image quality and heat transfer efficiency during fixing. The resin surface layer is composed of a PFA tube or the like, and its thickness is preferably about 10 to 50 μm in consideration of mechanical deterioration. By using the fixing roller having such a configuration, the image quality in fixing is remarkably improved. A temperature detector is provided on the outer peripheral surface of the fixing roller 71, and the heater 74 is controlled so as to keep the surface temperature of the fixing roller 71 at, for example, approximately 165 ° C. substantially constant.
In the pressure roller 72, for example, an offset prevention layer such as tetrafluoroethylene-perfluoroalkyl vinyl ether (PFA) or polytetrafluoroethylene (PTFE) is coated on the surface of a metal core having an outer diameter of φ38. Similar to the fixing roller 71, a heater 73 is provided in the cored bar. This heater is an important component in the thermal transfer described later in addition to the stabilizing action in the fixing means 7. Details will be described later. An elastic layer such as silicone rubber may be provided on the surface of the core metal (not shown), but in this example, it is not arranged in consideration of the stability of the belt temperature.
[0012]
In the fixing device having such a configuration, the fixing roller 71 and the pressure roller 72 have, for example, a surface pressure of 9.3 N / cm.²The fixing nip width is about 10 mm. The fixing unit 7 is driven in synchronism with a photosensitive member driving unit (not shown), and sandwiches and conveys the transfer material. At this time, the fixing roller 71 is controlled to a predetermined temperature by the heater 74, and when the toner image on the transfer material passes between both rollers, the toner image is thermally melted while receiving pressure, and is discharged from the roller pair and cooled. As a result, the image is fixed on the transfer material as a permanent image.
By providing an elastic layer on the fixing roller, the surface of the toner image and the contact point with the transfer paper are more closely attached, fixing property, micro density unevenness and gloss non-uniformity are reduced, and a high-quality fixed image can be obtained. I can do it.
[0013]
Next, a characteristic configuration of the present invention will be described.
A feature of the present invention resides in the transfer means 5. The conventional transfer process is an electrostatic transfer system using static electricity, but the present invention is in a point of transferring using pressure. Further, in combination with a toner to be described later, transfer and hypothetical fixing (toner image in a composition deformed state) are performed with a smaller pressing force than in the past. If transfer / fixing is performed using a large pressure as in the past, the transfer roller is restricted and a sufficient transfer mechanism cannot be easily created, and the image is degraded by strong pressing force, and the transfer material is torn off. Have. Furthermore, the photoconductor must be composed of a high-hardness photoconductor such as A-Si, which not only makes the entire image forming apparatus expensive, but also allows the photoconductor to be used to be of a type that can withstand pressure. General versatility is lost. By using the toner of the present invention, the transfer system of the present invention can be used in combination with a general-purpose photoconductor such as an organic photoconductor not only by the conventional electrostatic transfer effect but also in combination with a weak pressure. This is a new transfer method.
[0014]
The transfer roller 52 is made of a silicon rubber material having a hardness of 1 mm on the surface of a metal cylinder, for example, having a hardness of about 80 Hs (as Ask C hardness tester) and has an elastic structure. This is not an important structure of the present invention, but it is convenient because it absorbs the surface pressure variation on the transfer belt 53 well and it is easy to secure the surface pressure. For example, the contact width is about 0.8 mm, and the pressing force is 150 N / cm in terms of surface pressure.²It has become. Surface pressure is 300 N / cm²If it is above, the transfer rate is improved, but the pressure is high and the toner on the photoconductor is crushed, leading to deterioration of the image. 80 N / cm²If it is below, sufficient transfer characteristics and fixability (composition deformation state) cannot be obtained. The surface pressure is determined by the hardness and contact width of the roller, and is about 100 to 200 N / cm.²Is a preferred range. If the fixing property to the transfer material (composition deformation state) can be ensured to be about 35% or more and the transfer rate is determined to be about 89% or more, the effect of the present invention can be sufficiently exerted. In this example, 150 N / cm²The transfer rate is about 93% and the fixing property is 40%. In addition to being an important roller for pressure transfer, the transfer roller 52 is driven in synchronism with the photoconductor so that the photoconductor and the transfer belt 53 have substantially the same speed in the pressure contact area.
[0015]
The transfer belt 53 is not a feature of the present invention, but the effect of the present invention can be obtained as long as the material and shape do not damage the pressure and the surface of the photosensitive member such as pressure flaws. Here, the base material is made of, for example, a seamless polyimide film, and a silicon rubber material having a hardness of about 80 Hs (with an Asuka C hardness meter) is provided on the outside thereof with a thickness of 500 μm, and a fluororesin layer is further provided thereon.
By mounting the transfer belt having such a configuration, it is possible to suppress fluctuations in the speed with the photosensitive member while easily securing the required pressure, and to prevent toner contamination on the transfer belt 53.
The transfer belt 53 is stretched between the roller 54 and an appropriate tension is applied.
[0016]
The photoreceptor used in the present invention has, for example, a surface hardness of 20 kg / mm.²If it is (Vickers hardness) or more, the effect of the present invention can be obtained. As described above, the toner has a pressing force during transfer: about 80 to 300 N / cm.²Therefore, when the photoconductor hardness is lowered, the photoconductor is broken and does not show good electrostatic characteristics.
Here, the transfer rate and the fixing rate can be expressed by the following equations.
Transfer rate = [toner weight on transfer material / toner weight on photoconductor after development] × 100 (%)
Fixing rate = [image density after clock meter test / image density before clock meter test] × 100 (%)
The clock meter test is performed according to JIS L 0823 friction tester type I. Friction piece diameter: φ15 mm, measurement cloth: white cotton cloth (JIS L 0803) is rubbed 10 times (reciprocating) with a load of 8.8 N. At this time, before reflection (image density before the clock meter test) and after (image density after the clock meter test) are measured with a reflection densitometer (X-Rite 508 spectral densitometer: manufactured by X-Rite).
In this example, surface hardness: 30 kg / mm²An organic photoreceptor made mainly of polycarbonate was used for the charge transport layer having (Vickers hardness), but usually 20 to 40 kg / mm.²It is. If this is coated with a thin film of about several μm of amorphous carbon, it will be improved to about 300. In the case of Se-Te photoconductor, about 60 kg / mm.²Degree, As₂Se₃150 kg / mm when a coat layer in which polyester and silica are kneaded is provided on the photoreceptor.²Showed the degree. Of course, the effects of the present invention can be expected in all of these photoreceptors.
[0017]
In the fixing means 7, since the toner on the transfer material is already inputted in a composition deformed state, the original fixing performance can be obtained with the temperature of the fixing roller 71 being lower than that of the prior art or lower pressure. In addition, the heater disposed on the pressure roller 72 can prevent the temperature of the pressure roller from dropping when the transfer paper passes, and can be fixed efficiently, so that a stable and uniform image can be obtained.
[0018]
In this way, it is important for the effect of the present invention to compositionally deform the toner at the time of transfer using pressure, but in order to obtain the effect of the present invention, the physical properties of the toner are also important. In other words, it is important that the toner sinks into the transfer material with a transfer pressure as low as possible, and that adhesiveness is obtained between the toners. As described above, the Vickers hardness of the photoreceptor is 20 kg / mm.²As described above, the surface pressure during transfer is 300 N / cm.²The following is preferable when the transfer means of the present invention is used because a sufficient effect is exhibited.
[0019]
The present invention relates to a primary fixing device that develops an electrostatic latent image formed on a photosensitive member with dry toner, and then simultaneously transfers and fixes the formed toner image to a transfer paper only by pressure, and further primary fixing. In the image forming method using an image forming apparatus having a secondary fixing device for fixing the toner image on the transfer paper by passing it through a heat and pressure fixing device having a fixing roller, the toner has a volume specific resistance as the toner. 1 × 10⁹A non-magnetic toner having Ω · cm or more and a weight average particle size of 3.0 to 10.0 μm is used, and the fixing property of the toner to the transfer paper is primary fixing <secondary fixing. It is characterized by this.
[0020]
In primary fixing in which fixing is performed on transfer paper by pressure at the same time as transfer, it is important that the toner image formed on the photoreceptor is developed densely. If it is not densely developed, the pressure becomes non-uniform during transfer and the primary fixability varies. In order to develop a toner image densely, it is preferable that the charge amount is high and uniform, and in order to hold the charge (charge amount) in the toner, it is necessary that the volume specific resistance of the toner is high. × 10⁹It is important that it is Ω · cm or more. 1 × 10⁹When it is less than Ω · cm, the toner image is developed sparsely, the pressure becomes nonuniform during transfer, and the fixing property during transfer varies. The volume resistivity of the toner is 1 × 10¹⁰~ 5x10¹¹Ω · cm is preferred.
The volume resistivity of the toner is measured by measuring 3.0 g of toner at 6 t / cm²A disk-shaped pellet having a diameter of 40 mm is measured with a TR-10C type dielectric loss measuring instrument (Ando Electric Co., Ltd.). The frequency is 1 KHz and RATIO is 11 × 10^-9Ωcm.
[0021]
Further, it is important that the weight average particle diameter of the toner is 3.0 to 10.0 μm. The smaller the toner particle size, the better the image quality. If it is larger than 10.0 μm, the image quality may deteriorate, which is not preferable. On the other hand, when the particle size is less than 3.0 μm, the productivity of the toner is deteriorated and the fluidity is remarkably deteriorated.
[0022]
In the present invention, the degree of dispersion of the particle size of the toner (weight average particle size / number average particle size) is preferably 1.3 or less. When the degree of dispersion is 1.3 or more, it is difficult to uniformly apply transfer and fixing pressure in the primary fixing, which is not preferable because variations in pressure fixing properties occur.
Measurement of weight average particle size and number average particle size is Coulter MULTISIZER
IIe was used.
Table 1 shows an example of the particle size distribution of the toner used in the present invention. The aperture diameter is 100 μm.
[0023]
[Table 1]

[0024]
Regarding the image quality, after the transfer of the toner image, the volume and area after the fixing change, and the image quality deteriorates. This phenomenon is particularly remarkable in the case of digital development, and the reproducibility of independent dots is greatly affected.
The density of the halftone should be uniform, but if there is micro-density unevenness, it gives a rough impression when viewed with the naked eye.
The physical evaluation value of the roughness is granularity.
Noise can be measured by a Wiener Spectrum, which is a frequency characteristic of density fluctuation.
If the density fluctuation component whose average value is 0 is f (x)
F (u) = ∫f (x) exp (−2πiux) dx (1)
WS (u) = F (u)²                                 (2)
(Where u is the spatial frequency)
The granularity (GS) is a value obtained by integrating the product of WS and visual frequency characteristics (VTF), and is expressed by the following equation (3).
GS = exp (−1.8 <D>) ∫WS (u)^1/2VTF (u) du (3)
Exp (−1.8 <D>) is a coefficient for correcting a difference between density and brightness perceived by a person. <D> represents an average value of density.
The granularity has a high correlation with the subjective evaluation of the smoothness of the image.
The smaller the granularity value, the smoother the image quality becomes, and vice versa.
[0025]
In the present invention, the average circularity of the toner is preferably 0.92 or more, particularly preferably 0.92 to 0.99. When the average circularity is less than 0.92, the toner particles are indefinite, the toner image is not uniformly gathered on the photoreceptor, and the transfer and fixability in the primary fixing are deteriorated.
The average circularity can be measured using a flow type particle image analyzer FPIA-2100 manufactured by Sysmex Corporation. Measurement is carried out by adjusting a 1% NaCl aqueous solution using primary sodium chloride and then passing through a 0.45 μm filter to 50 to 100 ml of a surfactant as a dispersant, preferably 0.1 to 5 ml of alkylbenzene sulfonate. In addition, add 1-10 mg of sample. This is subjected to a dispersion treatment for 1 minute with an ultrasonic disperser, and measurement is performed using a dispersion liquid in which the particle concentration is adjusted to 5000 to 15000 particles / μl. The diameter of a circle having the same area as a two-dimensional image imaged by a CCD camera is assumed to be a circle equivalent diameter, and an equivalent circle diameter of 0.6 μm or more is effective from the accuracy of CCD pixels and is used for calculating the average circularity. . The average circularity can be obtained by calculating the circularity of each particle, adding up the circularity of each particle, and dividing by the total number of particles. The average circularity of each particle can be calculated by dividing the circumference of a circle having the same projected area as the particle image by the circumference of the particle projection image.
A toner having an average circularity of 0.92 or more can be produced by pulverization by mechanical impact or a method by heat treatment.
[0026]
In the present invention, the glass transition temperature Tg of the toner is preferably 50 to 70 ° C. When Tg is lower than 50 ° C., the storage stability of the toner is deteriorated. On the other hand, when the temperature is higher than 70 ° C., the heat fixing property in the secondary fixing is deteriorated.
Tg is measured according to ASTM D3418-82. The DSC curve is a DSC curve measured at a rate of temperature increase of 10 ° C./min after once raising and lowering the temperature.
[0027]
In the present invention, the toner softening temperature Tm is preferably 100 to 160 ° C. When Tm is lower than 100 ° C., the storage stability is deteriorated similarly to Tg. Also, when the temperature is higher than 160 ° C., the heat fixing property in the secondary fixing is deteriorated similarly to Tg.
The softening temperature Tm is measured with a flow tester CFT-500C (Shimadzu Corporation). The measurement conditions were: extrusion pressure: 1.9612 MPa, temperature increase rate: 6 ° C./min, die diameter: 1.0 mm, die length: 1.0 mm, and the temperature when 1/2 flowed out was Tm. To do.
[0028]
In the present invention, the temperature at which the melt viscosity of the toner becomes 1000 PaS is preferably 120 to 170 ° C. When the temperature is lower than 120 ° C., a hot offset phenomenon easily occurs in the secondary fixing. On the other hand, when the temperature is higher than 170 ° C., the heat fixing property in the secondary fixing is deteriorated.
The measurement of melt viscosity is a value measured with a flow tester CFT-500C (Shimadzu Corporation). The measurement conditions are extrusion pressure: 1.9612 MPa, heating rate: 6 ° C./min, die diameter: 1.0 mm, die length Measured under conditions of 1.0 mm.
In addition, melt viscosity (eta) is calculated | required by the following formula.
Melt viscosity η = τ / γ = πD⁴P / 128LQ
P: Extrusion pressure (Pa) Q = X / 10 × A / t
D: Die diameter (mm)
L: Die length (mm)
t: Measurement time (s)
X: Movement amount of piston with respect to measurement time t (mm)
A: Cross-sectional area of piston (mm²)
The temperature at which the melt viscosity η is 1000 PaS is determined.
[0029]
In the present invention, the loose apparent density of the toner is preferably 0.3 g / cc or more. If it is less than 0.3 g / cc, the toner cohesiveness becomes strong, the toner image thickness on the photoreceptor becomes non-uniform, and the transfer and fixability in primary fixing deteriorate.
The loose apparent density is measured using a powder tester (PTN type: manufactured by Hosokawa Micron).
[0030]
The present invention is preferably an organic optical semiconductor having a photoreceptor surface friction coefficient of 0.70 or less. When the surface friction coefficient is higher than 0.70, the releasability from the photosensitive member is deteriorated when transferring and fixing in the primary fixing, and the image quality in the primary fixing is deteriorated.
As a method for reducing the surface friction coefficient of the photoreceptor, for example, a fatty acid metal salt such as zinc stearate or calcium stearate is uniformly coated on the surface of the photoreceptor, or a silicone oil is contained in the charge transport layer of the photoreceptor. The most common means is a method of adding it to the toner.
The surface friction coefficient is measured using a fully automatic friction and wear analyzer manufactured by Kyowa Interface Chemical Co., Ltd. At this time, a 3 mm stainless steel sphere is used as the contact.
[0031]
In the present invention, it is preferable that the photoreceptor is a photoreceptor in which a protective layer containing a photosensitive layer and a metal oxide is provided on a conductive support.
When a photoconductor provided with a protective layer containing a metal oxide is used, the mechanical strength is strong even when pressure is applied by a pressure roll in primary fixing, so that the photoconductor has little film scraping and stable image quality. Obtainable.
Further, the metal oxide contained in the protective layer of the photoreceptor is preferably one kind selected from alumina, titanium oxide, and silka.
The protective layer is for the purpose of improving the abrasion resistance, and in the resin such as fluororesin and silicone resin, silica, alumina, titanium oxide, barium titanate, magnesium titanate, calcium titanate, strontium titanate, zinc oxide, tin oxide A material added with various metal oxides such as alumina, titanium oxide, and silica, which have a particularly high effect of preventing film abrasion, is preferable.
[0032]
Next, the toner material used in the present invention will be described.
Any conventionally known resin can be used as the binder resin used in the present invention. For example, polystyrene, poly-α-methylstyrene, styrene-chlorostyrene copolymer, styrene-propylene copolymer, styrene-butadiene copolymer, styrene-vinyl chloride copolymer, styrene-vinyl acetate copolymer, styrene -Styrene such as maleic acid copolymer, styrene-acrylic acid ester copolymer, styrene-methacrylic acid ester copolymer, styrene-α-chloroacrylic acid methyl copolymer, styrene-acrylonitrile-acrylic acid ester copolymer Resin (monopolymer or copolymer containing styrene or styrene-substituted product), polyester resin, epoxy resin, vinyl chloride resin, rosin-modified maleic acid resin, phenol resin, polyethylene resin, polypropylene resin, petroleum resin, polyurethane resin, Ketone resin, ethylene Examples include ethyl acrylate copolymer, xylene resin, and polyvinyl butyrate resin.
[0033]
In the present invention, a polyester resin is particularly preferable. The polyester resin is obtained by condensation polymerization of an alcohol component and a carboxylic acid component. Examples of the alcohol component used include glycols such as ethylene glycol, diene glycol, triethylene glycol and propylene glycol, etherified bisphenols such as 1,4-bis (hydroxymeta) cyclohexane and bisphenol A, and other divalent compounds. And trihydric or higher polyhydric alcohol monomers. Examples of the carboxylic acid component include divalent organic acid monomers such as maleic acid, fumaric acid, phthalic acid, isophthalic acid, terephthalic acid, succinic acid, and malonic acid, 1,2,4-benzenetricarboxylic acid, 1,2,5-benzenetricarboxylic acid, 1,2,4-cyclohexanetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,3-dicarboxyl-2-methylene Examples thereof include trivalent or higher polyvalent carboxylic acid monomers such as carboxypropane and 1,2,7,8-octanetetracarboxylic acid.
[0034]
Moreover, although said resin can be used individually, you may use 2 or more types together.
Moreover, the manufacturing method of these resin is not specifically limited, either bulk polymerization, solution polymerization, emulsion polymerization, and suspension polymerization can be used.
[0035]
In the present invention, all known release agents for use in the toner can be used, and in particular, de-free fatty acid type carnauba wax, montan wax and oxidized rice wax can be used alone or in combination.
The carnauba wax is preferably a microcrystalline one, having an acid value of 5 or less and a particle size of 1 μm or less when dispersed in a toner binder.
The montan wax generally refers to a montan wax refined from minerals, and like a carnauba wax, it is microcrystalline and preferably has an acid value of 5 to 14.
The oxidized rice wax is obtained by air-oxidizing rice bran wax, and the acid value is preferably 10-30. As other mold release agents, any conventionally known mold release agents such as solid silicone varnish, higher fatty acid higher alcohol, montan ester wax, and low molecular weight polypropylene wax can be mixed and used.
The amount of these release agents used is 1 to 20 parts by weight, preferably 3 to 10 parts by weight, based on 100 parts by weight of the toner resin component.
[0036]
As the external additive, inorganic fine particles can be preferably used. The primary particle diameter of the inorganic fine particles is preferably 5 mμ to 2 μm, and particularly preferably 5 mμ to 500 mμ. The specific surface area according to the BET method is 20 to 500 m.²/ G is preferable. The proportion of the inorganic fine particles used is preferably 0.01 to 5% by weight of the toner, and particularly preferably 0.01 to 2.0% by weight.
Specific examples of the inorganic fine particles include, for example, silica, alumina, titanium oxide, barium titanate, magnesium titanate, calcium titanate, strontium titanate, zinc oxide, tin oxide, quartz sand, clay, mica, wollastonite, diatomaceous earth. Examples include soil, chromium oxide, cerium oxide, bengara, antimony trioxide, magnesium oxide, zirconium oxide, barium sulfate, barium carbonate, calcium carbonate, silicon carbide, and silicon nitride.
In addition, polymer fine particles such as polystyrene obtained by soap-free emulsion polymerization, suspension polymerization and dispersion polymerization, methacrylic acid ester and acrylic acid ester copolymer, polycondensation system such as silicone, benzoguanamine and nylon, thermosetting resin And polymer particles.
[0037]
Such a fluidizing agent can be surface-treated to increase hydrophobicity and prevent deterioration of flow characteristics and charging characteristics even under high humidity. For example, a silane coupling agent, a silylating agent, a silane coupling agent having a fluorinated alkyl group, an organic titanate coupling agent, an aluminum coupling agent and the like are preferable surface treatment agents.
[0038]
In the toner used in the present invention, it is preferable to use a charge control agent added internally to the toner particles or externally added to the toner particles. The charge control agent makes it possible to control the optimum charge amount according to the development system. In particular, the present invention is effective when used in the development method in which the toner concentration is not controlled by using the charge control agent.
The charge control agent used in the toner may be a conventionally known charge control agent. Examples of the positive polarity control agent include modified products of nigrosine and fatty acid metal salts; tributylbenzylammonium-1-hydroxy-4-naphthosulfonate, tetra Quaternary ammonium salts such as butylammonium tetrafluoroborate; diorganotin oxides such as dibutyltin oxide, dioctyltin oxide and dicyclohexyltin oxide; diorganotin borates such as dibutyltin borate, dioctyltin borate and dicyclohexyltin borate alone or in two types These can be used in combination. Among these, polar controlling agents such as nigrosine compounds and organic quaternary ammonium salts are particularly preferably used.
[0039]
As the negative polarity control agent, for example, organometallic compounds and chelate compounds are effective. Examples thereof include aluminum acetylacetonate, iron (II) acetylacetonate, chromium 3,5-di-tert-butyl-salicylate, and in particular, acetylacetone metal complex, monoazo metal complex, naphthoic acid or salicylic acid metal complex or A salt is preferable, and a salicylic acid metal complex, a monoazo metal complex, or a salicylic acid metal salt is particularly preferable.
[0040]
The charge control agent is preferably used in the form of fine particles, and specifically, a number average particle diameter of 3 μm or less is preferable.
The amount of charge control agent used in the toner is uniquely determined by the type of binder resin, the presence or absence of additives used as required, and the toner production method including the dispersion method. However, it is preferably used in the range of usually 0.1 to 20 parts by weight, preferably 0.2 to 10 parts by weight with respect to 100 parts by weight of the binder resin. If it is less than 0.1 part by weight, the charge amount of the toner is insufficient, which is not practical. On the other hand, when the amount exceeds 20 parts by weight, the charge amount of the toner is too large, and the electrostatic attraction force with the carrier is increased, leading to a decrease in developer fluidity and a decrease in image density.
[0041]
As the colorant for the toner used in the present invention, all of the pigments and dyes conventionally used as toner colorants are applied. Specifically, carbon black, lamp black, iron black, ultramarine, nigrosine dye, aniline blue, chalcoil blue, oil black, azo oil black, etc. are not particularly limited, but conductive carbon such as acetylene black and ketjen black in particular. By using black, it is possible to control the volume resistivity of the toner used in the present invention.
The amount of the colorant used is generally 1 to 20 parts by weight, preferably 3 to 10 parts by weight with respect to 100 parts by weight of the binder resin.
[0042]
The toner production method of the present invention may be a conventionally known method. As a pulverization method, for example, a binder resin, a release agent, a colorant, and in some cases, a charge control agent and the like are mixed using a mixer or the like. Kneading is performed using a kneader such as a roll or an extruder. Here, the volume specific resistance value of the toner used in the present invention can be controlled by changing the kneading conditions such as kneading temperature and kneading speed and changing the dispersibility of the carbon black. After kneading, the mixture is cooled and solidified, and is pulverized with a pulverizer such as a jet mill, a turbojet, or a kryptron, and then classified.
To add inorganic non-powder to the toner, a mixer such as a super mixer or a Henschel mixer is used.
[0043]
The image forming method of the present invention can be carried out by a one-component development system or a two-component development system.
In the case of the two-component development method, the carrier core particles constituting the developer in the present invention may be known particles such as ferromagnetic metals such as iron, cobalt and nickel; alloys and compounds such as magnetite, hematite and ferrite And a composite of the ferromagnetic fine particles and a resin.
The carrier used in the present invention may be configured to cover the surface with a resin for the purpose of increasing durability.
Examples of the resin for forming the coating layer include polyolefin resins such as polyethylene, polypropylene, chlorinated polyethylene, and chlorosulfonated polyethylene; polystyrene, acrylic resins (for example, polymethyl methacrylate), polyacrylonitrile, polyvinyl acetate, polyvinyl alcohol, polyvinyl Polyvinyl and polyvinylidene resins such as butyral, polyvinyl chloride, polyvinyl carbazole, polyvinyl ether, and polyvinyl ketone; vinyl chloride-vinyl acetate copolymer; silicone resin composed of organosiloxane bond or a modified product thereof (for example, alkyd resin, polyester resin) , Epoxy resin, modified products by polyurethane, etc.); polytetrafluoroethylene, polyvinyl fluoride, polyvinylidene fluoride, polychlorotrifluor Examples include fluorine resins such as polyethylene; polyamides; polyesters; polyurethanes; polycarbonates; amino resins such as urea-formaldehyde resins; and epoxy resins. Among them, the coating resin used in the present invention has a high margin for toner spent. A resin or a modified product thereof is preferred.
[0044]
As the silicone resin, any conventionally known silicone resin may be used, and it may be modified with straight silicone and alkyd, polyester, epoxy, urethane, etc. composed only of an organosiloxane bond represented by the following formula (1). And silicone resin.
[Chemical 1]

(Wherein R₁Is a hydrogen atom, an alkyl group having 1 to 4 carbon atoms or a phenyl group, R₂And R₃Is a hydrogen atom, an alkoxy group having 1 to 4 carbon atoms, a phenyl group, a phenoxy group, an alkenyl group having 2 to 4 carbon atoms, an alkenyloxy group having 2 to 4 carbon atoms, a hydroxy group, a carboxyl group, an ethylene oxide group, A glycidyl group or a group represented by the following formula (2).
[Chemical 2]

R in the above formula₄, R₅Is a hydroxy group, a carboxyl group, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, an alkenyl group having 2 to 4 carbon atoms, an alkenyloxy group having 2 to 4 carbon atoms, a phenyl group , Phenoxy group, k, l, m, n, o, p represents an integer of 1 or more.
Each of the above substituents may have a substituent such as an amino group, a hydroxy group, a carboxyl group, a mercapto group, an alkyl group, a phenyl group, an ethylene oxide group, a glycidyl group, or a halogen atom in addition to an unsubstituted one. . )
[0045]
Further, in the carrier used in the present invention, a conductivity imparting material may be dispersed in the coating layer in order to control its volume resistivity. The conductivity imparting material to be dispersed may be a conventionally known material, and examples thereof include metals such as iron, gold, and copper; iron oxides such as ferrite and magnetite; and pigments such as carbon black.
Among these, in particular, by using a mixture of furnace black and acetylene black, which is one of the carbon blacks, it is possible to effectively adjust the conductivity by adding a small amount of conductive fine powder, and to further improve the wear resistance of the coating layer. It is possible to obtain an excellent carrier. These conductive fine powders preferably have a particle size of about 0.01 to 10 μm, preferably 2 to 30 parts by weight, more preferably 5 to 20 parts by weight, based on 100 parts by weight of the coating resin. .
[0046]
In addition, a silane coupling agent, a titanium coupling agent, or the like may be added to the carrier coating layer for the purpose of improving the adhesion with the core particles or improving the dispersibility of the conductivity imparting agent.
The silane coupling agent used in the present invention is a compound represented by the following general formula.
[Chemical 3]
YRSiX₃
(In the formula, X is a hydrolyzable group bonded to a silicon atom, for example, a chloro group, an alkoxy group, an acetoxy group, an alkylamino group, a propenoxy group, and Y is an organic functional group that reacts with an organic matrix, such as vinyl. Group, methacryl group, epoxy group, glycidoxy group, amino group, mercapto group, etc. R is an alkyl or alkylene group having 1 to 20 carbon atoms.)
Among the silane coupling agents, an aminosilane coupling agent having an amino group in Y is preferable for obtaining a negatively charged developer, and Y has an epoxy group for obtaining a positively charged developer. Epoxy silane coupling agents are preferred.
[0047]
As a method for forming the coating layer, the coating layer forming liquid may be applied to the surface of the carrier core particle by means of a spraying method, a dipping method, or the like, as in the past. The thickness of the coating layer is preferably 0.1 to 20 μm.
Further, when used as a developer, it is preferable that the toner is usually mixed at a ratio of 2 to 10 parts by weight with respect to 100 parts by weight of the carrier and used as a developer.
[0048]
Next, the electrophotographic photosensitive member used in the present invention will be described.
In the present invention, a widely known electrophotographic photosensitive member having a photosensitive layer provided on a conductive substrate can be used, but an organic system having advantages such as low cost, productivity and pollution-free property. A photosensitive material using the above-mentioned photosensitive material is preferable, and among them, a function-separated type photoconductor using a combination of a charge generation material and a charge transfer material is most preferable in terms of performance.
Examples of the drum-like conductive support that can be used in the present invention include metals or alloys such as Al, Ni, Fe, Cu, and Au; plastics such as polyester, polycarbonate, and polyimide, or an insulating substrate such as glass. , Ag, Au or other metal film or In₂O₃, SnO₂Examples thereof include those provided with a metal oxide film.
The function-separated type photoreceptor is formed by laminating a charge generation layer and a charge transport layer on these conductive supports. The charge generation layer may be formed only from the charge generation material or may be formed by uniformly dispersing the charge generation material in the binder resin. The charge generation layer is formed by dispersing these components in a suitable solvent, and applying and drying this on a conductive support.
[0049]
Examples of the charge generating substance include CIP Pigment Blue 25 (Color Index (CI) 21180), CIG Pigment Red 52 (CI45100), CII Basic Red 3 (CI45210), etc., phthalocyanine pigments having a porphyrin skeleton, and carbazole skeleton. Azo pigments (described in JP-A-53-95033), azo pigments having a stilbene skeleton (described in JP-A-53-138229), azo pigments having a distyrylbenzene skeleton (JP-A-53-133455) Azo pigments having a triphenylamine skeleton (described in JP-A-53-132547), azo pigments having a dibenzothiophene skeleton (described in JP-A-54-21728), azo pigments having an oxadiazole skeleton Pigment (Japanese Patent Laid-Open No. 54-1274) Azo pigments having a fluorenone skeleton (described in JP-A-54-22834), azo pigments having a bis-stilbene skeleton (described in JP-A-54-17733), and having a distyryloxadiazole skeleton Azo pigments (described in JP-A No. 54-2129), azo pigments having a distyrylcarbazole skeleton (described in JP-A No. 54-17734), trisazo pigments having a carbazole skeleton (JP-A 57-195767, No. 57-195758), etc., phthalocyanine pigments such as CI Pigment Blue 16 (CI74100), indigo pigments such as CI Eye Brown 5 (CI173410), Argo Scar Red B (manufactured by Violet) Perylene pigments such as R (manufactured by Bayer), square Tsu organic pigments click pigments: Se, Se alloys, can be used CdS, inorganic pigments amorphous Si or the like.
[0050]
As the binder resin, polyamide, polyurethane, polyester, epoxy resin, polyketone, polycarbonate, silicone resin, acrylic resin, polyvinyl butyral, polyvinyl formal, polyvinyl ketone, polystyrene, poly-N-vinylcarbazole, polyacrylamide and the like are used.
The amount of the binder resin is usually 5 to 100 parts by weight, preferably 10 to 50 parts by weight with respect to 100 parts by weight of the charge generating material.
Solvents used here are single solvents or mixed solvents such as tetrahydrofuran, cyclohexanone, dioxane, dichloroethane, cyclohexane, methyl ethyl ketone, 1,1,2-trichloroethane, 1,1,2,2-tetrachloroethane, dichloromethane, and ethyl cellosolve. Is preferred.
The average film thickness of the charge generation layer is usually 0.01 to 2 μm, preferably 0.1 to 1 μm.
[0051]
The charge transport layer is formed by dissolving a charge transport material, a binder resin and, if necessary, a plasticizer and a leveling agent in a suitable solvent, coating the charge transport layer on the charge generation layer, and drying.
Examples of the charge transport material include poly-N-vinylcarbazole and derivatives thereof, poly-γ-carbazolylethyl glutamate and derivatives thereof, pyrene-formaldehyde condensates and derivatives thereof, polyvinylpyrene, polyvinylphenanthrene, oxazole derivatives, imidazole derivatives, Electron donating properties such as triphenylamine derivatives, 9- (p-diethylaminostyryl) anthracene, 1,1-bis (4-dibenzylaminophenyl) propane, styrylanthracene, styrylpyrazolin, phenylhydrazones, α-stilbene derivatives Substances.
[0052]
Binder resins include polystyrene, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, poly Vinyl chloride, polyvinylidene chloride, polyacrylate resin, phenoxy resin, polycarbonate, cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral, polyvinyl formal, polyvinyl toluene, poly-N-vinyl carbazole, acrylic resin, silicone resin, epoxy resin, melamine resin And thermoplastic or thermosetting resins such as urethane resin, phenol resin, and alkyd resin.
Solvents for forming the charge transport layer include tetrahydrofuran, dioxane, toluene, monochlorobenzene, 1,2-dichloroethane, cyclohexanone, dichloromethane, 1,1,2-trichloroethane, 1,1,2,2-tetrachloroethane and These mixed solvents are desirable.
The film thickness of the charge transport layer is usually 10 to 100 μm, preferably 20 to 40 μm.
[0053]
In the present invention, an intermediate layer may be provided between the conductive support and the charge generation layer as necessary in order to improve adhesion and charge blocking properties. Further, it may have a reverse layer structure in which a charge transport layer and a charge generation layer are laminated in this order on a conductive substrate, and the outermost surface layer is a protective layer provided for the purpose of improving wear resistance or the like. Also good.
[0054]
In the present invention, the surface friction coefficient of the photoreceptor can be arbitrarily controlled by incorporating silicone oil in the charge transport layer of the photoreceptor.
The silicone oil that can be used in the present invention is not particularly limited as long as it is generally marketed. For example, in addition to straight silicone oils such as dimethyl silicone oil, methylphenyl silicone oil, and methylhydrogen silicone oil, alkyl modification, Any of various modified silicone oils represented by amino modification, carboxyl modification, higher fatty acid modification, epoxy modification, alcohol modification, polyether modification, alkyl / polyether modification, fluorine modification and the like can be preferably used.
Further, the amount of these silicone oils added in the present invention is preferably 0.01% by weight or more, more preferably in the range of 0.01 to 5% by weight with respect to the resin in the charge transport layer. When it is less than 0.01% by weight, the effect of reducing the friction coefficient by silicone oil is not sufficiently exhibited, and the effect of the present invention cannot be obtained. On the other hand, when the addition amount is more than 5% by weight, the adhesion force on the surface of the photoreceptor is increased, and it becomes difficult to maintain good transfer characteristics.
[0055]
【Example】
EXAMPLES The present invention will be specifically described below using examples, but the present invention is not limited to these examples.
[0056]
referenceExample 1
<Toner prescription>
Polyester resin 89 parts by weight
(Weight average molecular weight: 325,000, Tg: 67.5 ° C.)
Polyethylene wax (molecular weight 900) 5 parts by weight
Carbon black (Mitsubishi Kasei # 44) 5 parts by weight
Charge control agent (Spiron Black TR-H: Hodogaya Chemical) 1 part by weight
  After kneading at 150 ° C. using a biaxial extruder with the above formulation, pulverizing and classifying with an airflow type pulverizer to obtain a weight average particle size of 7.0 μm (weight average particle size / number average particle size 1.40). Thereafter, using a Henschel mixer, 0.5% by weight of silica (R-972 Nippon Aerosil) was mixed to obtain toner A having physical properties shown in Table 2.
  As the carrier, magnetite particles having an average particle diameter of 50 μm coated with methyl methacrylate resin (MMA) (film thickness: 0.5 μm) are mixed at a toner concentration of 5.0% by weight.referenceThe developer of Example 1 was obtained.
[0057]
referenceExample 2
<Toner prescription>
Polyester resin 89 parts by weight
(Weight average molecular weight: 325,000, Tg: 67.5 ° C.)
5 parts by weight of polyethylene wax (average particle size: 900 μm)
Carbon black (Mitsubishi Kasei # 44) 8 parts by weight
Charge control agent (Spiron Black TR-H: Hodogaya Chemical) 1 part by weight
  After kneading at 120 ° C. using a biaxial extruder with the above formulation, pulverizing and classifying with an airflow type pulverizer to obtain a weight average particle diameter of 5.0 μm (weight average particle diameter / number average particle diameter 1.20). Thereafter, using a Henschel mixer, 0.5% by weight of silica (R-972 Nippon Aerosil) was mixed to obtain toner B having physical properties shown in Table 2.
  As the carrier, magnetite particles having an average particle diameter of 50 μm coated with methyl methacrylate resin (MMA) (film thickness: 0.5 μm) are mixed at a toner concentration of 5.0% by weight.referenceThe developer of Example 2 was obtained.
[0058]
Example1
<Toner prescription>
88 parts by weight of styrene-n-butyl acrylate copolymer
(Weight average molecular weight: 55000, Tg: 52 ° C.)
5 parts by weight of polyethylene wax (average particle size: 900 μm)
Carbon black (Mitsubishi Kasei # 44) 10 parts by weight
Charge control agent (Spiron Black TR-H: Hodogaya Chemical) 1 part by weight
  After kneading at 120 ° C. using a biaxial extruder with the above formulation, pulverizing and classifying with a mechanical pulverizer to give a weight average particle size of 4.5 μm (weight average particle size / number average particle size 1.29). Thereafter, using a Henschel mixer, 0.5% by weight of silica (R-972 Nippon Aerosil) was mixed to obtain toner C having physical properties shown in Table 2.
  As the carrier, magnetite particles having an average particle diameter of 50 μm coated with methyl methacrylate resin (MMA) (film thickness: 0.5 μm) were used and mixed at a toner concentration of 5.0% by weight.1Developer was obtained.
[0059]
Example2
<Toner prescription>
Polyester resin 89 parts by weight
(Weight average molecular weight: 280000, Tg: 61 ° C.)
Carnauba wax (average particle size: 300 μm) 5 parts by weight
Carbon black (Mitsubishi Kasei # 44) 6 parts by weight
Charge control agent (Spiron Black TR-H: Hodogaya Chemical) 1 part by weight
  After kneading at 180 ° C. using a biaxial extruder with the above formulation, the mixture was pulverized and classified by a mechanical pulverizer to obtain a weight average particle size of 9.5 μm (weight average particle size / number average particle size 1.10). Thereafter, using a Henschel mixer, 0.5% by weight of silica (R-972 Nippon Aerosil) was mixed to obtain toner D having physical properties shown in Table 2.
  As the carrier, magnetite particles having an average particle diameter of 50 μm coated with methyl methacrylate resin (MMA) (film thickness: 0.5 μm) were used and mixed at a toner concentration of 5.0% by weight.2Developer was obtained.
[0060]
Example3
<Toner prescription>
40 parts by weight of polyester resin
(Weight average molecular weight: 310000, Tg: 68 ° C.)
48 parts by weight of styrene-n-butyl acrylate copolymer
(Weight average molecular weight: 85000, Tg: 60 ° C.)
Carnauba wax 4 parts by weight
Carbon black (Mitsubishi Kasei # 44) 5 parts by weight
Charge control agent (Spiron Black TR-H: Hodogaya Chemical) 1 part by weight
  After kneading at 100 ° C. using a biaxial extruder with the above formulation, pulverizing and classifying with a mechanical pulverizer to give a weight average particle size of 8.5 μm (weight average particle size / number average particle size 1.15). Thereafter, using a Henschel mixer, 0.5% by weight of silica (R-972 Nippon Aerosil) was mixed to obtain a toner E having physical properties shown in Table 2.
  As the carrier, magnetite particles having an average particle diameter of 50 μm coated with methyl methacrylate resin (MMA) (film thickness: 0.5 μm) were used and mixed at a toner concentration of 5.0% by weight.3Developer was obtained.
[0061]
Example4
<Toner prescription>
80 parts by weight of polyester resin
(Weight average molecular weight: 310000, Tg: 68 ° C.)
20 parts by weight of styrene-n-butyl acrylate copolymer
(Weight average molecular weight: 85000, Tg: 60 ° C.)
Carnauba wax 4 parts by weight
Carbon black (Mitsubishi Kasei # 44) 8 parts by weight
Charge control agent (Spiron Black TR-H: Hodogaya Chemical) 1 part by weight
  After kneading at 120 ° C. using a biaxial extruder with the above formulation, the mixture was pulverized and classified by a mechanical pulverizer to obtain a weight average particle size of 8.5 μm (weight average particle size / number average particle size 1.20). Thereafter, using a Henschel mixer, 0.5% by weight of silica (R-972 Nippon Aerosil) was mixed to obtain toner F having physical properties shown in Table 2.
  As the carrier, magnetite particles having an average particle diameter of 50 μm coated with methyl methacrylate resin (MMA) (film thickness: 0.5 μm) were used and mixed at a toner concentration of 5.0% by weight.4Developer was obtained.
[0062]
Example5
<Toner prescription>
50 parts by weight of polyester resin
(Weight average molecular weight: 310000, Tg: 68 ° C.)
45 parts by weight of styrene-n-butyl acrylate copolymer
(Weight average molecular weight: 85000, Tg: 60 ° C.)
Carnauba wax 5 parts by weight
Carbon black (Mitsubishi Kasei # 44) 6 parts by weight
Charge control agent (Spiron Black TR-H: Hodogaya Chemical) 1 part by weight
  After kneading at 140 ° C. using a biaxial extruder with the above formulation, pulverized and classified with a mechanical pulverizer to give a weight average particle size of 9.0 μm (weight average particle size / number average particle size 1.25). Thereafter, 0.8% by weight of silica (R-972 Nippon Aerosil) was mixed using a Henschel mixer to obtain a toner G having physical properties shown in Table 2.
  As the carrier, magnetite particles having an average particle diameter of 50 μm coated with methyl methacrylate resin (MMA) (film thickness: 0.5 μm) were used and mixed at a toner concentration of 5.0% by weight.5Developer was obtained.
[0063]
Example6
<Toner prescription>
30 parts by weight of polyester resin
(Weight average molecular weight: 310000, Tg: 68 ° C.)
59 parts by weight of styrene-n-butyl acrylate copolymer
(Weight average molecular weight: 85000, Tg: 60 ° C.)
Carnauba wax 5 parts by weight
Carbon black (Mitsubishi Kasei # 44) 5 parts by weight
Charge control agent (Spiron Black TR-H: Hodogaya Chemical) 1 part by weight
  After kneading at 100 ° C. using a biaxial extruder with the above formulation, the mixture was pulverized and classified by a mechanical pulverizer to obtain a weight average particle size of 9.0 μm (weight average particle size / number average particle size 1.20). Then, using a Henschel mixer, 1.0% by weight of silica (R-972 Nippon Aerosil) and 0.2% by weight of zinc stearate fine powder were mixed and mixed to obtain toner H having physical properties shown in Table 2. It was.
  As the carrier, magnetite particles having an average particle diameter of 50 μm coated with methyl methacrylate resin (MMA) (film thickness: 0.5 μm) were used and mixed at a toner concentration of 5.0% by weight.6Developer was obtained.
[0064]
Example7
  Example6In Example 1, except that an organic photoreceptor provided with a protective layer containing 15% by weight of silica was used as the photoreceptor.6And so on.
[0065]
Comparative Example 1
<Toner prescription>
Polyester resin 89 parts by weight
(Weight average molecular weight: 325,000, Tg: 67.5 ° C.)
5 parts by weight of polyethylene wax
(Average particle size: 900 μm)
Ketjen Black (Ketjen Black EC
: Ketjen Black International) 3 parts by weight
Charge control agent (Spiron Black TR-H: Hodogaya Chemical) 1 part by weight
After kneading at 100 ° C. using a biaxial extruder with the above formulation, the mixture was pulverized and classified by a mechanical pulverizer to obtain a weight average particle size of 8.5 μm (weight average particle size / number average particle size 1.33). Thereafter, 0.8% by weight of silica (R-972 Nippon Aerosil) was mixed using a Henschel mixer to obtain a toner J having physical properties shown in Table 2.
As a carrier, a magnetite particle having an average particle diameter of 50 μm coated with methyl methacrylate resin (MMA) (film thickness 0.5 μm) was used, and the developer of Comparative Example 1 was mixed by mixing at a toner concentration of 5.0% by weight. Obtained.
[0066]
Comparative Example 2
<Toner prescription>
Polyester resin 89 parts by weight
(Weight average molecular weight: 325,000, Tg: 67.5 ° C.)
5 parts by weight of polyethylene wax (average particle size: 900 μm)
Carbon black (Mitsubishi Kasei # 44) 10 parts by weight
Charge control agent (Spiron Black TR-H: Hodogaya Chemical) 1 part by weight
After kneading at 100 ° C. using a biaxial extruder with the above formulation, the mixture was pulverized and classified by a mechanical pulverizer to obtain a weight average particle size of 2.5 μm (weight average particle size / number average particle size 1.20). Thereafter, using a Henschel mixer, 0.5% by weight of silica (R-972 Nippon Aerosil) was mixed to obtain toner K having physical properties shown in Table 2.
As a carrier, a magnetite particle having an average particle diameter of 50 μm coated with methyl methacrylate resin (MMA) (film thickness 0.5 μm) is used, and the developer of Comparative Example 2 is mixed at a toner concentration of 5.0% by weight. Obtained.
[0067]
Comparative Example 3
The toner of Comparative Example 2 was adjusted to a weight average particle diameter of 10.5 μm (weight average particle diameter / number average particle diameter of 1.40), and then silica (R-972 Nippon Aerosil) 1.0% by weight using a Henschel mixer. Were mixed to obtain a toner L having the physical properties shown in Table 2.
As the carrier, magnetite particles having an average particle diameter of 50 μm coated with methyl methacrylate resin (MMA) (film thickness 0.5 μm) were used, and the developer of Comparative Example 3 was mixed by mixing at a toner concentration of 5.0% by weight. Obtained.
[0068]
(Evaluation method)
A testing machine (primary fixing pressure: 150 N / cm) with the unit configuration shown in FIG. 1 modified from the transfer / fixing unit of imagio MF7070 (Ricoh copier).²Secondary fixing pressure: 9.3 N / cm²And a sample printed at a temperature of 165 ° C. is obtained. Next, the gray scale (halftone part) made by the dots of the print image is read at 1000 dpi with a Genascan 5000 scanner manufactured by Dainippon Screen, and image data is obtained. The image data is converted into a density distribution, and the granularity is evaluated by the equation (3). Further, the fixability at the time of primary fixing and secondary fixing was evaluated from the image data. The evaluation method is as follows. The initial photoconductor friction coefficient was also measured.
◎ Fixability evaluation method
Primary fixing property: A fixing tape (manufactured by 3M) is applied to the image after the primary fixing, and a steel roller having a weight of 1 kg is used to reciprocate once on an image having a width of 2.5 cm. Then peel off the tape slowly. The image density before and after that is measured with a Macbeth densitometer, and the fixing rate is calculated by the following equation.
Secondary fixability: Without primary fixing, transfer with a charger of another printer, apply a fixing tape (manufactured by 3M) to an image that has only been subjected to secondary fixing, and use a steel roller with a weight of 1 kg. One round trip is performed on an image having a width of 2.5 cm. Then peel off the tape slowly. The image density before and after that is measured with a Macbeth densitometer, and the fixing rate is calculated by the following equation.
Fixing rate (%) = (image density after peeling off tape / image density before peeling off tape) × 100
◎ Image quality
Evaluation of granularity
A sample printed by a testing machine having a unit configuration shown in FIG. 1 is obtained by remodeling the transfer / fixing unit of imgioMF7070 (Ricoh Copier). Next, the gray scale (halftone part) made by the dots of the print image is read at 1000 dpi with a Genascan 5000 scanner manufactured by Dainippon Screen, and image data is obtained. The image data is converted into a density distribution, and the granularity is evaluated by the equation (3).
The evaluation results are shown in Table 3.
[0069]
[Table 2]

[0070]
[Table 3]

[0071]
【The invention's effect】
In the present invention, after the primary fixing in which the toner image on the photosensitive member is transferred and fixed to the transfer paper only by pressure, the toner image on the transfer paper on which the primary fixing has been performed is further fixed by heating and pressing with a fixing roller. In the image forming method, the volume resistivity as the toner is 1 × 10⁹Provided is an image forming method capable of obtaining a high-quality image without causing image deterioration during transfer by using a non-magnetic toner having a weight average particle diameter of 3.0 to 10.0 μm and having an Ω · cm or more. can do.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of an entire image forming apparatus used in the present invention.
[Explanation of symbols]
1 Photoconductor
2 Charging means
3 Exposure means
31 Scanner
32 Laser light
33 Mirror
4 Development means (developing device)
41 Development sleeve
5 Transfer means
52 Transfer roller
53 Transfer belt
54 Belt drive roller
55 Cleaning blade
6 Cleaning means
61 Cleaning blade
62 Fur Brush
63 Fur brush cleaning member
7 Fixing means
71 Fixing roller
72 Pressure roller
73 Heating means (heater)
74 Heating means (heater)
101 Transfer material bank
102 Paper feed roller
103 Feed roller
104 resist roller
105 Discharge roller
106 Transfer material bank
107 Feed roller
108 Feed roller

Claims (7)

A development process for developing the electrostatic latent image formed on the photosensitive member with dry toner, a primary fixing process for simultaneously transferring and fixing the formed toner image to the transfer paper only with pressure, and a transfer with further primary fixing. an image forming method having a secondary fixing step of fixing by passage through a heat-pressure fixing device having a fixing roller and toner image on the paper, the surface pressure of the primary fixing step, be 100-200 N / cm ² The toner has a volume resistivity of 1 × 10 ⁹ Ω · cm or more, a weight average particle size of 3.0 to 10.0 μm, and a degree of particle size dispersion (weight average particle size / number average particle size). An image forming method using a non-magnetic toner having an average circularity of 0.92 or less and an average circularity of 0.92 to 0.99 . The image forming method according to claim 1 , wherein the toner has a glass transition temperature Tg of 50 to 65 ° C. The image forming method according to claim 1 or 2 softening temperature Tm of the toner is characterized in that it is a 100 to 160 ° C.. The image forming method according to any one of claims 1 to 3, the melt viscosity of the toner is the temperature at which the 1000PaS is characterized in that it is a 120 to 170 ° C.. The image forming method according to any one of claims 1 to 4, loose apparent density of the toner is equal to or is 0.3 g / cc or more. The photoreceptor, image forming method according to any one of claims 1 to 5, the surface coefficient of friction, characterized in that 0.70 the following organic optical semiconductor. The photoreceptor, image forming method according to any one of claims 1 to 6, characterized in that an organic photoreceptor having a protective layer containing a photosensitive layer and a metal oxide on a conductive support.

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