JP2004054060A - Image forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming method for forming an image of high image quality such as an image of high dot-reproducibility, high line-reproducibility and high granularity by preventing the deterioration of the image due to transfer at a transfer process easily causing the image deterioration in the case of forming the image. <P>SOLUTION: As for the image forming method using an image forming apparatus provided with a photoreceptor for carrying an electrostatic latent image, a developing apparatus, a transfer apparatus equipped with a roller coming in press contact with the photoreceptor, and a heat roller fixing device, and wherein heat and pressure are applied on toner and a transfer paper through rollers at a transfer process, a transfer process and a primary fixation process are simultaneously performed, the primarily fixed transfer paper separated from the photoreceptor is fixed at a secondary fixation process, an amorphous silicon photoreceptor is used as a photoreceptor, a pressure between the transfer device and the photoreceptor is controlled to be 10 to 100N/cm<SP>2</SP>, a temperature to be imparted to the transfer material of the transfer apparatus is within the extent from glass transition temperature Tg of toner to toner softening temperature Tm, and as for developing, the image is developed by one-component developer, and magnetic one-component toner whose softening temperature Tm is 100 to 160°C is used. <P>COPYRIGHT: (C)2004,JPO

Description

【００２８】
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、下記の式（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。
【００２９】
低抵抗トナーを用いて誘導電荷で現像する方式に於いては、トナーに電荷が蓄積されにくいため、電荷による転写が難しい。従って圧力のみにより転写紙に転写と同時に定着する一次定着においては、感光体上に形成されたトナー像は画像品質を悪化させることなく転写、定着される。本発明においてはトナーの体積固有抵抗は１×１０^９Ωｃｍ以下が好ましい。１×１０^９Ωｃｍより高い場合は現像において電荷注入が発生しにくくなるため、画像品質が悪化する。
トナーの体積固有抵抗の測定は、トナー３．０ｇを６ｔ／ｃｍ^２の荷重をかけ直径４０ｍｍの円盤状のペレットにしたものをＴＲ−１０Ｃ型誘電体損測定器（安藤電気株式会社）にて測定する。なお周波数は１ＫＨｚ、ＲＡＴＩＯは１１×１０^−９である。
【００３０】
本発明におけるトナーは平均円形度が０．９２以上であることが好ましい。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。
【００３１】
本発明における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。
【００３２】
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。
【００３３】
本発明はトナーのゆるみ見掛け密度が０．２７ｇ／ｃｃ以上であることが好ましい。０．２７ｇ／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。
【００３４】
次に本発明で用いるトナーを構成する各成分について説明する。
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。
【００３５】
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。
【００３６】
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。
【００３７】
また本発明においてトナーに用いる磁性体は、酸化鉄、マグネタイト、フェライトなどの従来より使用されている全ての公知磁性微粉末を添加することができる。
該磁性体の添加量は、結着樹脂１００重量部に対して、通常５〜６０重量部、好ましくは１５〜４５重量部である。
【００３８】
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、通常１〜２０重量部、好ましくは３〜１０重量部である。
【００３９】
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。
【００４０】
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。
【００４１】
本発明のトナー（現像剤）は、必要に応じて帯電制御剤を含有してもよい。帯電制御剤としては公知のものが全て使用でき、例えばニグロシン系染料、トリフェニルメタン系染料、クロム含有金属錯体染料、モリブデン酸キレート顔料、ローダミン系染料、アルコキシ系アミン、４級アンモニウム塩（フッ素変性４級アンモニウム塩を含む）、アルキルアミド、燐の単体または化合物、タングステンの単体または化合物、フッ素系活性剤、サリチル酸金属塩及び、サリチル酸誘導体の金属塩等である。
【００４２】
具体的にはニグロシン系染料のボントロン０３、第四級アンモニウム塩のボントロンＰ−５１、含金属アゾ染料のボントロンＳ−３４、オキシナフトエ酸系金属錯体のＥ−８２、サリチル酸系金属錯体のＥ−８４、フェノール系縮合物のＥ−８９（以上、オリエント化学工業社製）、第四級アンモニウム塩モリブデン錯体のＴＰ−３０２、ＴＰ−４１５（以上、保土谷化学工業社製）、第四級アンモニウム塩のコピーチャージＰＳＹ　ＶＰ２０３８、トリフェニルメタン誘導体のコピーブルーＰＲ、第四級アンモニウム塩のコピーチャージ　ＮＥＧ　ＶＰ２０３６、コピーチャージ　ＮＸ　ＶＰ４３４（以上、ヘキスト社製）、ＬＲＡ−９０１、ホウ素錯体であるＬＲ−１４７（日本カーリット社製）、銅フタロシアニン、ペリレン、キナクリドン、アゾ系顔料、その他スルホン酸基、カルボキシル基、四級アンモニウム塩等の官能基を有する高分子系の化合物が挙げられる。
【００４３】
本発明においてトナーに使用される着色剤としては、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。
着色剤の使用量は、結着樹脂１００重量部に対して、通常１〜１０重量部、好ましくは３〜７重量部である。
【００４４】
本発明のトナーの製造方法は、従来公知の方法でよく、結着樹脂、離型剤、着色剤、その他場合によっては帯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した後、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。
【００４５】
【実施例】
以下、本発明を実施例により具体的に説明する。
【００４６】
実施例及び比較例における画像形成の条件を表２に示す。また評価方法は下記のとおりである。
評価結果を表２に示す。
＜評価方法＞
実施例の評価方法にについて述べる。評価機はリコーＩｍａｇｉｏＭＦ７０７０の転写、定着部を改造して行った。ユニット構成は図１の装置の概略図と同じである。現像として一成分方式は図２の現像装置を用いた。
◎評価機
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を用いた。
◎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。
【００４７】
実施例１
＜トナー処方＞
ポリエステル樹脂　　　　　　　　　　　　　　　　　　　　８５重量部
（重量平均分子量：１９００００、Ｔｍ：１１３℃）
ポリエチレンワックス（分子量９００）　　　　　　　　　　　５重量部
マグネタイト微粒子　　　　　　　　　　　　　　　　　　　５０重量部
カーボンブラック（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）　　　　　　　　２重量部
帯電制御剤（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、気流式粉砕機により粉砕、分級し、重量平均粒径１１．０μｍ（重量平均粒径／個数平均粒径１．４５）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）０．１５重量％を混合しトナーを得た。
このトナーの体積固有抵抗は１．２×１０^９Ωｃｍ、また平均円形度は０．８８、Ｔｇは７８℃、溶融粘度が１０００ＰａＳとなる温度は１１５℃、ゆるみ見掛密度は０．２６ｇ／ｃｃであった。
【００４８】
実施例２
＜トナー処方＞
ポリエステル樹脂　　　　　　　　　　　　　　　　　　　　８５重量部
（重量平均分子量：３６７０００、Ｔｍ：１５７℃）
ポリエチレンワックス（分子量９００）　　　　　　　　　　　５重量部
マグネタイト微粒子　　　　　　　　　　　　　　　　　　　５０重量部
カーボンブラック（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）　　　　　　　　２重量部
帯電制御剤（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１１．０μｍ（重量平均粒径／個数平均粒径１．５０）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％を混合しトナーを得た。
このトナーの体積固有抵抗は１．２×１０^９Ωｃｍ、また平均円形度は０．８８、Ｔｇは７８℃、溶融粘度が１０００ＰａＳとなる温度は１６５℃、ゆるみ見掛密度は０．２６ｇ／ｃｃであった。
【００４９】
比較例１
＜トナー処方＞
ポリエステル樹脂　　　　　　　　　　　　　　　　　　　　９２重量部
（重量平均分子量：２０００００、Ｔｍ：９５℃）
ポリエチレンワックス（平均粒径：９００μｍ）　　　　　　　５重量部
マグネタイト微粒子　　　　　　　　　　　　　　　　　　　５０重量部
カーボンブラック（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）　　　　　　　　２重量部
帯電制御剤（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８０℃で混練後、気流式粉砕機により粉砕、分級し、重量平均粒径１１．０μｍ（重量平均粒径／個数平均粒径１．４５）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）０．３重量％を混合しトナーを得た。
このトナーの体積固有抵抗は１．２×１０^９Ωｃｍ、また平均円形度は０．８９、Ｔｇは５０℃、溶融粘度が１０００ＰａＳとなる温度は１００℃、ゆるみ見掛密度は０．２９ｇ／ｃｃであった。
【００５０】
比較例２
＜トナー処方＞
ポリエステル樹脂　　　　　　　　　　　　　　　　　　　　９２重量部
（重量平均分子量：４０００００、Ｔｍ：１８５℃）
ポリエチレンワックス（平均粒径：９００μｍ）　　　　　　　５重量部
マグネタイト微粒子　　　　　　　　　　　　　　　　　　　５０重量部
カーボンブラック（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）　　　　　　　　２重量部
帯電制御剤（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１７０℃で混練後、気流式粉砕機により粉砕、分級し、重量平均粒径１１．０μｍ（重量平均粒径／個数平均粒径１．４１）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）０．１５重量％を混合しトナーを得た。
このトナーの体積固有抵抗は１．２×１０^９Ωｃｍ、また平均円形度は０．８９、Ｔｇは７５℃、溶融粘度が１０００ＰａＳとなる温度は１８５℃、ゆるみ見掛密度は０．２９ｇ／ｃｃであった。
【００５１】
比較例３
実施例１のトナーを用い、評価時にＯＰＣ感光体（有機光半導体）を用いたこと以外は実施例１と同様にした。
【００５２】
比較例４
実施例１のトナーを用い、評価時に転写装置と感光体間圧力が１０５Ｎ／ｃｍ^２にしたこと以外は同様にした。
【００５３】
実施例３
＜トナー処方＞
ポリエステル樹脂　　　　　　　　　　　　　　　　　　　　９３重量部
（重量平均分子量：３０５０００、Ｔｍ：１４５℃）
ポリプロピレンワックス（分子量８０００）　　　　　　　　　３重量部
マグネタイト微粒子　　　　　　　　　　　　　　　　　　　５０重量部
カーボンブラック（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
帯電制御剤（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９．０μｍ（重量平均粒径／個数平均粒径１．４５）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％を混合しトナーを得た。
このトナーの体積固有抵抗は１．２×１０^９Ωｃｍ、また平均円形度は０．８７、Ｔｇは７２℃、溶融粘度が１０００ＰａＳとなる温度は１７０℃、ゆるみ見掛密度は０．２５ｇ／ｃｃであった。
【００５４】
実施例４
実施例３のトナーを用い、評価機において下記のように改造した以外は実施例３と同様にした。
評価機の改造においては、転写ユニットとクリーニングユニットを作像形成時以外は離して置く場合と、常に当接して使用する条件で経時での特性を確認した。
その結果、常に接触して稼働した機械では、クリーニングのブレード先端にトナーは固着し、クリーニング不良が発生し、感光体の汚れ、画像上地汚れ、黒スジなどが５０千枚程度からわずかであるが発生した。
一方、作像時以外は転写ユニットとクリーニングユニットを離して置く条件で、同じテストでも問題の発生は無く、正常な画像が得られた。
【００５５】
実施例５
＜トナー処方＞
ポリエステル樹脂　　　　　　　　　　　　　　　　　　　　９３重量部
（重量平均分子量：２８５０００、Ｔｍ：１４５℃）
ポリプロピレンワックス（分子量８０００）　　　　　　　　　３重量部
マグネタイト微粒子　　　　　　　　　　　　　　　　　　　５０重量部
カーボンブラック（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
帯電制御剤（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１．４５）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％を混合しトナーを得た。
このトナーの体積固有抵抗は９×１０^８Ωｃｍ、また平均円形度は０．８７、Ｔｇは７２℃、溶融粘度が１０００ＰａＳとなる温度は１７０℃、ゆるみ見掛密度は０．２５ｇ／ｃｃであった。
【００５６】
実施例６
＜トナー処方＞
スチレン−ｎ−ブチルアクリレート共重合体　　　　　　　　９１重量部
（重量平均分子量：１２５０００、Ｔｍ：１２５℃）
ライスワックス　　　　　　　　　　　　　　　　　　　　　　５重量部
マグネタイト微粒子　　　　　　　　　　　　　　　　　　　５０重量部
カーボンブラック（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
帯電制御剤（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９０℃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１．３６）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％を混合しトナーを得た。
このトナーの体積固有抵抗は８×１０^８Ωｃｍ、また平均円形度は０．９１、Ｔｇは７２℃、溶融粘度が１０００ＰａＳとなる温度は１１５℃、ゆるみ見掛密度は０．２６ｇ／ｃｃであった。
【００５７】
実施例７
＜トナー処方＞
ポリエステル樹脂　　　　　　　　　　　　　　　　　　　　９１重量部
（重量平均分子量：２５００００、Ｔｍ：１５０℃）
カルナウバワックス（平均粒径：３００μｍ）　　　　　　　　５重量部
マグネタイト微粒子　　　　　　　　　　　　　　　　　　　５０重量部
カーボンブラック（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
帯電制御剤（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９．５μｍ（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）０．７５重量％を混合しトナーを得た。
このトナーの体積固有抵抗は８×１０^８Ωｃｍ、また平均円形度は０．９５、Ｔｇは７２℃、溶融粘度が１０００ＰａＳとなる温度は１７２℃、ゆるみ見掛密度は０．２５ｇ／ｃｃであった。
【００５８】
実施例８
＜トナー処方＞
ポリエステル樹脂　　　　　　　　　　　　　　　　　　　　６１重量部
（重量平均分子量：３１００００、Ｔｍ：１４５℃）
スチレン−ｎ−ブチルアクリレ−ト重合体
（重量平均分子量：８５０００、Ｔｍ：１１５℃）　　　　３０重量部
カルナウバワックス（平均粒径：３００μｍ）　　　　　　　　５重量部
マグネタイト微粒子　　　　　　　　　　　　　　　　　　　５０重量部
カーボンブラック（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
帯電制御剤（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１３０℃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）０．７５重量％を混合しトナーを得た。
このトナーの体積固有抵抗は８×１０^８Ωｃｍ、また平均円形度は０．９５、Ｔｇは６５℃、溶融粘度が１０００ＰａＳとなる温度は１１８℃、ゆるみ見掛密度は０．２５ｇ／ｃｃであった。
【００５９】
実施例９
＜トナー処方＞
ポリエステル樹脂　　　　　　　　　　　　　　　　　　　　５１重量部
（重量平均分子量：３１００００、Ｔｍ：１５５℃）
スチレン−ｎ−ブチルアクリレート共重合体　　　　　　　　４０重量部
（重量平均分子量：８５０００、Ｔｍ：１２０℃）
カルナウバワックス　　　　　　　　　　　　　　　　　　　　５重量部
マグネタイト微粒子　　　　　　　　　　　　　　　　　　　５０重量部
カーボンブラック（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
帯電制御剤（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１４５℃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）０．７５重量％を混合しトナーを得た。
このトナーの体積固有抵抗は６×１０^８Ωｃｍ、また平均円形度は０．９５、Ｔｇは６５℃、溶融粘度が１０００ＰａＳとなる温度は１４０℃、ゆるみ見掛密度は０．２６ｇ／ｃｃであった。
【００６０】
実施例１０
＜トナー処方＞
ポリエステル樹脂　　　　　　　　　　　　　　　　　　　　４５重量部
（重量平均分子量：３１００００、Ｔｍ：１５５℃）
スチレン−ｎ−ブチルアクリレート共重合体　　　　　　　　４６重量部
（重量平均分子量：８５０００、Ｔｍ：１２０℃）
カルナウバワックス　　　　　　　　　　　　　　　　　　　　５重量部
マグネタイト微粒子　　　　　　　　　　　　　　　　　　　５０重量部
カーボンブラック（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
帯電制御剤（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１．２６）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）０．７５重量％を混合しトナーを得た。
このトナーの体積固有抵抗は９×１０^８Ωｃｍ、また平均円形度は０．９５、Ｔｇは６５℃、溶融粘度が１０００ＰａＳとなる温度は１３５℃、ゆるみ見掛密度は０．３３ｇ／ｃｃであった。
【００６１】
【表２】

【００６２】
【発明の効果】
本発明は、転写と一次定着を同時に行い、次いで二次定着する画像形成方法であって、アモルファスシリコーン感光体を用い、感光体の静電潜像を一成分現像の低抵抗トナーの静電誘導で現像し、転写装置と感光体間圧力を１０〜１００Ｎ／ｃｍ^２とし、転写装置の転写材に加える温度をトナーのガラス転移温度Ｔｇとトナーの軟化温度Ｔｍの範囲とし、かつトナーとして軟化温度Ｔｍが１００〜１６０℃の磁性一成分トナーを選択することにより、画像形成の際に、画像劣化の生じやすい転写工程において画像劣化を防止し、最終画像として、従来より改良されたドット再現性、ライン再現性が得られ、粒状度の良い高画質の画像を形成することができる。
【図面の簡単な説明】
【図１】本発明の画像形成装置でデジタルモノクロの実施形態を示す概略構成図である。
【図２】一成分低抵抗磁性トナーを用いた現像装置の構成概要図である。
【符号の説明】
１：ドラム状感光体
２：帯電器
３：露光手段
３１：スキャナー
３２：ポリゴンモータ
３３：ミラー
４：現像手段
４１：現像スリーブ
５：転写手段
５２：転写ローラ（一次定着ローラ）
５３：転写ベルト
５４：テンションローラ
５５：転写ベルトクリーニング手段
５６：加熱手段
５７：温度探知手段
６：クリーニング手段
６１：ブレード
６２：ブラシ
６３：ステアリン酸亜鉛
７：定着手段
７１：定着ローラ
７２：加圧ローラ
７３：加熱手段
７４：加熱手段
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：紙搬送ガイド手段
１０６：転写材バンク
１０７：給紙ローラ
１０８：給紙コロ[0001]
TECHNICAL FIELD 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 employing the image forming method.
[0002]
[Prior art]
An electrophotographic image forming method requires many steps. In the case of copying, the original is converted into an electric signal by a scanner or an optical system. In the case of a printer, the signal is directly input to the plotter.
An electric signal is applied to the photosensitive member as an optical image by writing with a laser or the like, and an electrostatic latent image is formed on the charged photosensitive member. A colored fine powder represented by a toner is electrostatically attached to the latent image in a developing step. Further, in a transfer step, the image is electrostatically transferred to transfer paper. Recently, in the field of color, a method of transferring a toner image of three to four colors on an intermediate transfer member and transferring the toner image to transfer paper has been often used. Then, the toner is melted and fixed on the transfer paper by heat or the like to form an image.
[0003]
When image quality is considered, image degradation occurs in all of the above steps. In particular, it is well known that the image is greatly deteriorated in each of the development, transfer and fixing steps.
In the developing process, the toner is electrostatically attached to the electrostatic latent image on the photoreceptor by an electric field around the toner on the photoreceptor. And the image is deteriorated with respect to the electrostatic latent image. Recent technologies have been improved by reducing the diameter and spheroid of the toner, reducing the diameter of the carrier, reducing the resistance, and applying an AC bias.
[0004]
On the other hand, in the transfer step, the transfer paper conveyed in synchronization with the photoreceptor to which the developed toner adheres is brought into contact with the photoreceptor, and is electrostatically transferred to transfer from the photoreceptor by an electric field. However, in this transfer process, in a process in which the transfer paper and the photoreceptor come close to each other before and after close contact, electrostatic image deterioration due to dust, bleeding, and the like becomes large, but this has not been solved.
[0005]
There is also a problem in the fixing step. If the toner is completely melted to improve the fixability, the toner image spreads. If there is a variation in the amount of toner adhered on the transfer paper or if there is a transfer dust, the variation in the dot diameter and the line width after fixing becomes large, and the image often deteriorates.
As described above, the deterioration phenomenon is particularly large in the transfer process. As a result, the image deteriorates in terms of blur, sharpness, resolution, and the like.
[0006]
Therefore, it has been conventionally proposed to perform the transfer step and the fixing step at the same time. A well-known example of a system that simultaneously performs transfer and heat fixing is Japanese Patent Laid-Open No. 55-87156. However, since the heating element comes into contact with the photoconductor to perform transfer and complete fixing at the same time, even if a cooling device is provided, the photoconductor, the toner on the photoconductor, and the developing device are damaged by heat. Can not be avoided.
Further, in order to eliminate the adverse effect of heat on the system, a method of performing simultaneous transfer and fixing only by pressure without heating has been proposed. For example, in JP-A-03-186879, 1470 to 2450 N / cm ² There has been proposed a method of fixing at a pressure of 0.1 mm. In Japanese Patent Application Laid-Open Nos. 5-216354 and 6-35341, an amorphous silicon photoconductor and a capsule toner are used to simultaneously transfer toner formed on a photoconductor by a transfer fixing device facing the photoconductor by pressure transfer. A fixing method has been proposed. However, in any case, the pressure is large, the mechanism, the transfer paper transfer, and the system become large, which poses a practical problem and has not been put to practical use.
[0007]
As described above, the method of fixing simultaneously with transfer by heat and pressure has been proposed as a technique for complete fixing. In the method in which transfer and fixing are performed simultaneously by heat, the temperature around the photosensitive member becomes higher than the melting point of the toner, and a large stress is applied to the toner in a developing and cleaning device, which poses a serious problem in practical use.
Further, in the method in which transfer and fixing are performed only by pressure, 980 N / cm ² There are disadvantages, such as the necessity of the above, such as an increase in the size of the apparatus, weight and generation of fixing wrinkles on the transfer paper.
[0008]
Also, a method using a capsule toner as a toner has been proposed in JP-A-7-5776, JP-A-5-107796, JP-A-6-230599, and the like.
However, capsule toner has many problems in practical use, and in particular, it has not been compatible with development and fixing, and has problems such as high cost, and is currently not used for general purposes.
[0009]
[Problems to be solved by the invention]
In view of the above problems, an object of the present invention is to use a conventionally known general-purpose toner without using a capsule toner, and to reduce the conventionally reported transfer-fixing pressure to a lower pressure. In an image forming apparatus that uses pressure that is widely used in thermal fixing, the primary fixing method is used, in which transfer is performed simultaneously with primary fixing at a low temperature without using static electricity at the time of transfer, and light fixing is used to reduce image deterioration. An object of the present invention is to provide an image forming method capable of obtaining high-quality image quality.
[0010]
[Means for Solving the Problems]
The present inventors, as an image forming apparatus, include an amorphous photoconductor drum, a transfer unit including a transfer conveyance belt, and the like, and transfer a toner image formed on the photoconductor drum between the photoconductor and the transfer unit. A temperature in the range of toner glass transition temperature to toner softening temperature (for example, 70 to 120 ° C.) on paper and 10 to 100 N / cm ² Is applied to transfer paper to perform primary fixing of the toner on the transfer paper at the same time as the transfer, and the toner image on the transfer paper that is primarily fixed at the same time as the transfer is transferred by the low-temperature heat and pressure. It has been found that by fixing by passing through a fixing means by heat provided in the process, it is possible to obtain a high quality image without electrostatic image deterioration occurring at the time of transfer.
Here, the primary fixing refers to a state in which the toner is fixed by being entangled in the transfer paper by plastic deformation of the toner, and is not transferred or deteriorated by the transfer of the transfer paper in a machine, vibration, or the like.
As described above, latent image formation, development, transfer, separation, image deterioration occurs in each of the steps of fixing, the present invention, the toner is primarily fixed to transfer paper at the same time as the transfer by the transfer means of the largest deterioration, Then, the transfer paper is conveyed to a fixing device to obtain a final fixed image, thereby preventing deterioration of images such as dust and bleeding due to the influence of electrostatic discharge, and forming a high quality image. And completed the present invention.
[0011]
That is, according to the present invention, the following image forming methods (1) to (9) are provided.
(1) Using a photoreceptor carrying an electrostatic latent image, a developing device, a transfer device having a roller pressed against the photoreceptor, and an image forming apparatus having a heat roller fixing device, a toner and transfer paper are transferred in a transfer step. An image forming method in which transfer and primary fixing are performed simultaneously by applying heat and pressure via a roller, and the primary-fixed transfer paper separated from the photoconductor is fixed by secondary fixing. Using a photoreceptor, the pressure between the transfer device and the photoreceptor is 10 to 100 N / cm ² The temperature applied to the transfer material of the transfer device is in the range from the glass transition temperature Tg of the toner to the toner softening temperature Tm. The development is performed by one-component development, and the softening temperature Tm of the toner is 100 to 160. An image forming method comprising using a magnetic one-component toner at a temperature of ° C.
(2) The image forming apparatus further includes a cleaning unit, and the developing device, the transfer device, and the cleaning unit are provided with a mechanism for contacting / separating from the photosensitive member. The image forming method according to the above (1), wherein the image forming apparatus is maintained in a separated state.
(3) The image forming method according to (1) or (2), wherein the toner has a weight average particle diameter of 3.0 to 10.0 μm.
(4) The image forming apparatus according to any one of (1) to (3), wherein the degree of dispersion of the particle diameter of the toner (weight average particle diameter / number average particle diameter) is 1.4 or less. Method.
(5) Volume resistivity of the toner is 1 × 10 ⁹ The image forming method according to any one of the above (1) to (4), which is equal to or less than Ωcm.
(6) The image forming method according to any one of (1) to (5), wherein the toner has an average circularity of 0.92 to 0.99.
(7) The image forming method according to any one of (1) to (6), wherein the glass transition temperature Tg of the toner is 50 to 70 ° C.
(8) The image forming method according to any one of (1) to (7), wherein the temperature at which the melt viscosity of the toner becomes 1000 PaS is 120 to 170 ° C. (9) The image forming method according to any one of (1) to (8), wherein the loose apparent density of the toner is 0.27 g / cc or more.
[0012]
According to the image forming method of the present invention, as described above, the pressure between the transfer material and the photoconductor is set to 10 to 100 N / cm. ² By setting the temperature applied to the transfer material of the transfer device in the range from the glass transition temperature Tg of the toner to the softening temperature Tm of the toner, simultaneous simultaneous and temporary fixing of the transfer can be ensured.
Further, by using a magnetic one-component toner having a softening temperature Tm of 100 to 160 ° C. as the toner used in the above-described image forming method, the storage stability of the image and the heat fixing property in the secondary fixing can be improved.
Further, for example, when a temperature of 70 to 120 ° C. is given to the transfer, the temperature of each unit is higher than that of the electrostatic transfer method. However, the image forming apparatus used is provided with a cleaning unit, and a developing device, a transfer device, a cleaning device, The unit is provided with a contact / separation mechanism with the photoconductor, and is configured to stand apart from the photoconductor when it is not in operation, so that a margin due to a rise in temperature can be secured.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 is a schematic diagram of the entire image forming apparatus used in the present invention.
The image forming apparatus includes a drum-shaped photosensitive member 1 as a recording medium inside using a well-known electrophotographic method. Around the photoreceptor 1, a charger 2, an exposing unit 3, a developing unit 4, a transferring 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. I have.
[0014]
The exposure means 3 converts the data read by the scanner 31 and the image signal sent from the PC (not shown), scans the laser light with the polygon motor 32, and scans the photosensitive member 1 based on the image signal read through the mirror 33. To form an electrostatic latent image. The photosensitive member 1 uses an amorphous silicone photosensitive member.
A toner image is formed on the electrostatic latent image formed on the photoreceptor 1 by a developing unit 4 provided so as to be able to contact and separate, and a transfer material for transferring the toner image is stored in the transfer material. Paper is fed from the material banks 101 and 106 by paper feed rollers 102 and 107 and fed by paper feed rollers 103 and 108. The rollers 104 are resist rollers 104 for transporting the transfer material in synchronization with the toner image on the photoconductor, and the transfer material is sent to the transfer unit 5 and thermally transferred. The transfer material on which the toner image is placed is conveyed by the transfer belt 53, conveyed to the fixing unit 7 and fixed, and then discharged out of the apparatus.
On the other hand, the untransferred portion and the contaminated photosensitive member 1 are cleaned by the cleaning means 6 which is detachably disposed, and the next image forming step is started.
In the present invention, since a heat application method is used for transfer, it is more advantageous to arrange the units that are in contact with the photoreceptor so that they can be separated from and separated from the photoreceptor except when creating an image. .
[0015]
The fixing unit 7 is necessary in the present invention to completely fix the toner primarily fixed by the transfer unit 5 (described later).
The basic configuration includes a fixing roller 71 having a heating means 74 (hereinafter, referred to as a “heater”) such as a halogen lamp, and a pressing roller 72 pressed against the fixing roller 71.
The fixing roller 71 is provided with an elastic layer of, for example, silicone rubber having a rubber hardness of about 42 HS (Asuka C) on the surface of a core metal (not shown) having an outer diameter of φ50 to a thickness of 100 to 500 μm, preferably 400 μm. For the purpose of preventing adhesion due to viscosity, a resin surface layer such as fluororesin having good releasability is formed. 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. Temperature detecting means 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 substantially constant within a range of, for example, about 160 to 200 (165) ° C. I have.
The pressure roller 72 has a core metal surface coated with an offset prevention layer such as tetrafluoroethylene-perfluoroalkylvinyl ether (PFA) or polytetrafluoroethylene (PTFE). Similar to the fixing roller 71, an elastic layer such as silicone rubber may be provided on the surface of a core (not shown), or a heater 73 may be provided.
[0016]
In the fixing device having such a configuration, the fixing roller 71 and the pressure roller 72 are, for example, configured to have a surface pressure of 5 to 10 (9.3) N / cm. ² The fixing nip has a width of about 10 mm and is controlled to a predetermined temperature. The toner image on the transfer material melts while receiving pressure when passing between the two rollers. After being cooled out of the roller pair, it is fixed on the transfer material as a permanent image.
[0017]
Next, a characteristic configuration of the present invention will be described.
The feature of the present invention resides in the transfer unit 5. The conventional transfer process is an electrostatic transfer method using static electricity. However, the present invention resides in that an electrophotographic method transfers by using low-temperature heat. Pressure is applied between the photoconductor and the transfer roller so that heat transfer is performed more efficiently. This is a new transfer method using heat and weak pressure in combination.
[0018]
The transfer device includes, for example, a belt, a primary fixing roller 52, and a tension roller 54.
The transfer roller 52 is made of, for example, a core metal such as iron, aluminum, or stainless steel having an outer diameter of φ40, and is made of an elastic body having a hardness of 60 Hs (by an Asuka C hardness meter) and a contact width of about 1.5 mm. The pressing force is 10 to 100 N / cm in surface pressure. ² It has become. Considering the close contact between the transfer paper and the photoreceptor, the surface pressure is determined by the hardness and the contact width of the roller, and is about 20 to 50 N / cm. ² Is a preferable range. The transfer roller 52 is an important roller for performing primary fixing transfer, and has an elastic body structure having the above hardness, and obtains necessary surface pressure and contact width. Further, in order not to lower the heat so as to supply heat to the belt, the surface of the metal cylinder is coated with, for example, silicon rubber having a thermal conductivity of 0.5 × (1/1000) [cal / cm · sec · ° C.] or less by 3 mm. It has a thickness of 60 Hs. Inside, a heater 56 for heating is provided, and a belt (described later) is stretched. A temperature detecting means 57 is provided on the outer peripheral surface of the transfer roller 52, and the heater 56 is controlled to keep the temperature substantially constant within a range from the glass transition temperature of the toner using the surface temperature of the transfer roller 52 to the toner softening temperature. Have been. As an example, a temperature of 70 to 120 ° C. is used for a normal toner.
[0019]
The transfer belt 53 has a base material made of, for example, a seamless polyimide film. A fluororesin layer is provided on the outside. If necessary, a silicone rubber layer may be provided on the fill layer, and a fluororesin layer may be provided thereon. A belt driving and tension roller 54 is provided inside the transfer belt, and tension is applied to the transfer belt 53 by the roller 54 (not shown) in this example. The use of a belt is an essential requirement of the present invention, but the effect can be obtained by selecting various heat-resistant materials. In this example, the fluororesin layer is provided on the outside of the base material, but this is for preventing the heat of the belt from lowering, and is not a feature of the present invention. In the present invention, since a transfer method using heat is used as described later, it is not preferable to use a rubber material as a base material as in a conventional transfer belt.
[0020]
A technique of transferring by utilizing heating is disclosed, but the present invention is different from the conventional technique in that the heating temperature is as low as possible. If the temperature is high, the transferability is improved, but a technique for preventing thermal destruction of the photoreceptor, the developing means 4 and the cleaning means 6 is required. In addition, a peeling effect for peeling off the toner on the photoreceptor from the photoreceptor must be given to the photoreceptor. The photoreceptor is an amorphous silicone photoreceptor. If the temperature is low, the transfer is not performed efficiently. The temperature is generally above 80 ° C. The present invention achieves stable primary fixing toner and transfer by heating the belt at a temperature in the range from the toner glass transition temperature to the toner softening temperature (for example, 70 to 120 ° C.) and using the above-mentioned pressure in combination. It is. As a result, thermal stress is not applied to the photosensitive member, the developing unit 4 and the cleaning unit 6 described above, and sufficient transfer performance is achieved.
[0021]
As described above, half-fixing the toner is important for the effect of the present invention, but the physical properties of the toner are also important for obtaining the effect of the present invention. In other words, in order to obtain a semi-fixed toner stably, by applying a temperature in the range from the glass transition point to the softening point of the toner to the toner, the toner is plastically deformed and unevenness on the surface of the transfer paper having poor releasability is obtained. Attach by the anchor effect and transfer from the photoreceptor to the transfer paper, and the primary fixing and transfer are completed.
Further, in order to stably obtain the primary fixing at a low temperature, the surface roughness of the photosensitive member and the surface roughness of the transfer paper become important. As the conditions, when the toner particle diameter is a, it is preferable that the roughness Rz of the photoreceptor is “a / 2” or less and the roughness Rz of the transfer paper is “3 × a” or more.
The toners described below have easy characteristics for achieving the present invention.
[0022]
<Toner characteristics>
The toner described below is an important property for achieving the present invention.
In the present invention, an amorphous silicone photoconductor is used as the photoconductor, and the pressure between the transfer device and the photoconductor is 10 to 100 N / cm. ² The temperature applied to the transfer material of the transfer device is in the range from the toner glass transition temperature to the toner softening temperature, and development is performed by one-component development, and the toner has a softening temperature Tm of 100 to 160 ° C. It is characterized by using a one-component toner.
[0023]
In the primary fixing, in which the toner image is fixed on the transfer paper simultaneously with the transfer by pressure, it is important that the toner image formed on the photoreceptor is developed densely. If the image is not densely developed, the pressure becomes non-uniform at the time of transfer, and the primary fixing property varies. The softening temperature Tm of the toner of the present invention is 100 to 160 ° C., and if Tm is lower than 100 ° C., the storage stability is deteriorated. On the other hand, when the temperature is higher than 160 ° C., the heat fixing property in the secondary fixing deteriorates.
The softening temperature Tm is measured with a flow tester CFT-500C (Shimadzu Corporation). The measurement conditions were as follows: Extrusion pressure: 1.9612 MPa, heating rate: 6 ° C./min, die diameter: 1.0 mm, die length: 1.0 mm. I do.
[0024]
The weight average particle diameter of the toner is preferably from 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 thickness is smaller than 3.0 μm, the productivity of the toner is deteriorated and the flowability is significantly deteriorated, which is not preferable.
[0025]
In the present invention, the degree of dispersion of the particle diameter of the toner (weight average particle diameter / number average particle diameter) is preferably 1.4 or less. If the degree of dispersion is larger than 1.4, it is difficult to uniformly apply the transfer and fixing pressures in the primary fixing, so that the pressure fixing property varies, which is not preferable.
For the measurement of the weight average particle size and the number average particle size, see Coulter MULTISIZER.
IIe was used. The aperture diameter is 100 μm.
[0026]
Table 1 shows an example of the particle size distribution of the toner used in the present invention. The measurement used Coulter MULTISIZER IIe. The aperture diameter is 100 μm.
[0027]
[Table 1]

[0028]
As for the image quality, the volume and area after the transfer of the toner image and 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.
Halftone densities should be uniform, but micro-density irregularities can give a rough impression to the naked eye.
The physical evaluation value of the roughness is the granularity.
The noise can be measured by a Wiener Spectrum, which is a frequency characteristic of the 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 function (Visual Transfer Function: VTF), and is expressed by the following equation (3).
GS = exp (−1.8 <D>) ∫WS (u) ^1/2 VTF (u) du (3)
Exp (-1.8 <D>) is a coefficient for correcting the difference between the density and the brightness perceived by a person. <D> represents the average value of the density.
The granularity has a high correlation with the subjective evaluation of the smoothness of the image.
The smaller the value of the granularity, the smoother the image quality becomes, and the larger the value of the granularity, the rougher the image quality becomes.
[0029]
In a method of developing with an induced charge using a low-resistance toner, charge is not easily accumulated in the toner, so that transfer by the charge is difficult. Therefore, in the primary fixing in which the toner image is fixed on the transfer paper at the same time as the transfer only by the pressure, the toner image formed on the photoconductor is transferred and fixed without deteriorating the image quality. In the present invention, the volume resistivity of the toner is 1 × 10 ⁹ Ωcm or less is preferable. 1 × 10 ⁹ When it is higher than Ωcm, charge injection is less likely to occur during development, so that image quality deteriorates.
The volume resistivity of the toner was measured by measuring 3.0 g of the toner at 6 t / cm. ² Is applied and measured by a TR-10C type dielectric loss measuring device (Ando Electric Co., Ltd.). The frequency is 1 KHz, RATIO is 11 × 10 ^-9 It is.
[0030]
The toner according to the present invention preferably has an average circularity of 0.92 or more. When the average circularity is less than 0.92, the toner particles are irregular in shape and the aggregated state of the toner images on the photoreceptor is not uniform, so that the transfer and fixability in the primary fixing are deteriorated.
The average circularity can be measured using a flow particle image analyzer FPIA-2100 manufactured by SYSMEX CORPORATION. The measurement is performed by adjusting a 1% NaCl aqueous solution using primary sodium chloride, and then adding 0.1 to 5 ml of a surfactant, preferably an alkylbenzene sulfonate, as a dispersant to 50 to 100 ml of a 0.45 μm-filtered liquid. In addition, add 1-10 mg of sample. This is subjected to a dispersion treatment for 1 minute by an ultrasonic disperser, and the 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 area captured by a CCD camera is defined as a circle equivalent diameter, and a circle equivalent diameter of 0.6 μm or more is effective from the accuracy of CCD pixels and used for calculating the average circularity. . The average circularity can be obtained by calculating the circularity of each particle, adding 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 perimeter of a circle having the same projected area as the particle image by the perimeter of the particle projected image.
The toner having an average circularity of 0.92 or more can be produced by pulverization by mechanical impact, a method by heat treatment, or the like.
[0031]
The glass transition temperature Tg of the toner according to the invention is preferably 50 to 70 ° C. When Tg is lower than 50 ° C., the storage stability of the toner deteriorates. On the other hand, when the temperature is higher than 70 ° C., the heat fixing property in the secondary fixing deteriorates.
The Tg is measured according to ASTM D3418-82. As the DSC curve, a DSC curve measured once at a temperature rising rate of 10 ° C./min after the temperature is once increased and decreased.
[0032]
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., the hot offset phenomenon is likely to occur in the secondary fixing. On the other hand, when the temperature is higher than 170 ° C., the heat fixing property in the secondary fixing deteriorates.
The measurement of the melt viscosity is a value measured by a flow tester CFT-500C (Shimadzu Corporation), and the measurement conditions are: extrusion pressure: 1.9612 MPa, heating rate: 6 ° C./min, die diameter: 1.0 mm, die length Length: Measured under the condition of 1.0 mm.
The melt viscosity η is determined by the following equation.
Melt viscosity η = τ / γ = πD ⁴ P / 128LQ
Here, P: extrusion pressure (Pa) Q = X / 10 × A / t
D: Die diameter (mm)
L: Die length (mm)
t: Measurement time (s)
X: the amount of movement of the piston with respect to the measurement time t (mm)
A: Piston cross-sectional area (mm ² )
The temperature at which the melt viscosity η becomes 1000 PaS is determined.
[0033]
In the present invention, the loose apparent density of the toner is preferably 0.27 g / cc or more. If it is less than 0.27 g / cc, the cohesiveness of the toner becomes strong, the thickness of the toner image on the photoreceptor becomes uneven, and the transfer and fixability in the primary fixing deteriorate.
The loose apparent density is measured using a powder tester (PTN type: manufactured by Hosokawa Micron Corporation).
[0034]
Next, each component constituting the toner used in the present invention will be described.
As the binder resin used in the present invention, all conventionally known resins can be used. 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-chloromethyl acrylate copolymer, styrene-acrylonitrile-acrylic acid ester copolymer Resin (mono- or copolymer containing styrene or styrene substituent), polyester resin, epoxy resin, vinyl chloride resin, rosin-modified maleic resin, phenol resin, polyethylene resin, polypropylene resin, petroleum resin, polyurethane resin, Ketone resin, ethylene- Ethyl acrylate copolymer, xylene resin, polyvinyl butyrate resin and the like can be mentioned.
[0035]
In the present invention, a polyester resin is particularly preferred. 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 (hydroxymeth) cyclohexane, and bisphenol A, and other divalent compounds. And polyhydric alcohol monomers having three or more valences. 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 include trivalent or higher polyvalent carboxylic acid monomers such as carboxypropane and 1,2,7,8-octanetetracarboxylic acid.
[0036]
The above resins can be used alone or in combination of two or more.
Also, the method for producing these resins is not particularly limited, and any of bulk polymerization, solution polymerization, emulsion polymerization, and suspension polymerization can be used.
[0037]
In the present invention, as the magnetic material used for the toner, all conventionally known magnetic fine powders such as iron oxide, magnetite, and ferrite can be added.
The amount of the magnetic substance to be added is generally 5 to 60 parts by weight, preferably 15 to 45 parts by weight, based on 100 parts by weight of the binder resin.
[0038]
As the release agent used for the toner in the present invention, all known release agents can be used. In particular, a free fatty acid type carnauba wax, montan wax and rice oxide wax can be used alone or in combination.
The carnauba wax is preferably a microcrystalline wax, and preferably has an acid value of 5 or less and a particle diameter of 1 μm or less when dispersed in a toner binder.
The montan wax generally refers to a montan-based wax refined from a mineral, and is preferably a microcrystal and has an acid value of 5 to 14 like carnauba wax.
The oxidized rice wax is obtained by oxidizing rice bran wax with air, and preferably has an acid value of 10 to 30.
As other release agents, any conventionally known 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 the release agent used is usually 1 to 20 parts by weight, preferably 3 to 10 parts by weight, based on 100 parts by weight of the toner resin component.
[0039]
As the external additive, inorganic fine particles can be preferably used. The primary particle size of the inorganic fine particles is preferably from 5 μm to 2 μm, and particularly preferably from 5 μm to 500 μm. The specific surface area by the BET method is 20 to 500 m. ² / G. The use ratio of the inorganic fine particles is preferably from 0.01 to 5% by weight of the toner, and particularly preferably from 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, silica sand, clay, mica, wollastonite, and diatomaceous Examples include earth, chromium oxide, cerium oxide, red iron oxide, 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, or dispersion polymerization, polycondensation systems such as methacrylate and acrylate copolymers, silicone, benzoguanamine, and nylon, and thermosetting resins Polymer particles.
[0040]
Such a fluidizing agent can be subjected to a surface treatment to increase hydrophobicity and prevent deterioration of fluidity and charging properties 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-based coupling agent, an aluminum-based coupling agent, and the like are preferable surface treatment agents.
[0041]
The toner (developer) of the present invention may contain a charge control agent as needed. As the charge control agent, any known charge control agents can be used. For example, nigrosine dyes, triphenylmethane dyes, chromium-containing metal complex dyes, molybdate chelate pigments, rhodamine dyes, alkoxy amines, quaternary ammonium salts (fluorine-modified) Quaternary ammonium salts), alkyl amides, phosphorus alone or compounds, tungsten alone or compounds, fluorine-based activators, salicylic acid metal salts, and salicylic acid derivative metal salts.
[0042]
Specifically, bontron 03 of a nigrosine dye, bontron P-51 of a quaternary ammonium salt, bontron S-34 of a metal-containing azo dye, E-82 of an oxynaphthoic acid metal complex, and E-82 of a salicylic acid metal complex 84, phenolic condensate E-89 (all manufactured by Orient Chemical Industries), quaternary ammonium salt molybdenum complex TP-302, TP-415 (all manufactured by Hodogaya Chemical Industry), quaternary ammonium Salt copy charge PSY VP2038, triphenylmethane derivative copy blue PR, quaternary ammonium salt copy charge NEG VP2036, copy charge NX VP434 (all from Hoechst), LRA-901, LR-147, a boron complex (Nippon Carlit), copper phthalocyanine, perylene, quinacridone Azo pigments, sulfonate group, carboxyl group, and polymer compounds having a functional group such as a quaternary ammonium salt.
[0043]
As the colorant used in the toner of the present invention, all pigments and dyes conventionally used as colorants for toner are applied. Specifically, carbon black, lamp black, iron black, ultramarine, nigrosine dye, aniline blue, calco oil blue, oil black, azo oil black and the like are not particularly limited.
The amount of the colorant to be used is generally 1 to 10 parts by weight, preferably 3 to 7 parts by weight, based on 100 parts by weight of the binder resin.
[0044]
The method for producing the toner of the present invention may be a conventionally known method, in which 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, and a hot roll, an extruder, or the like is used. After kneading using a kneading machine, the mixture is cooled and solidified, pulverized by pulverization using a jet mill, turbojet, kryptron or the like, and then classified.
A mixer such as a super mixer or a Henschel mixer is used to add the inorganic powder to the toner.
[0045]
【Example】
Hereinafter, the present invention will be described specifically with reference to examples.
[0046]
Table 2 shows image forming conditions in the examples and the comparative examples. The evaluation method is as follows.
Table 2 shows the evaluation results.
<Evaluation method>
The evaluation method of the embodiment will be described. The evaluation was performed by modifying the transfer and fixing portions of Ricoh Imageio MF7070. The unit configuration is the same as the schematic diagram of the apparatus in FIG. In the one-component system, the developing device shown in FIG. 2 was used for development.
◎ Evaluation machine
A tester having a transfer and fixing unit of imageio MF7070 (copier made by Ricoh) modified to have the unit configuration shown in FIG. 1 was used.
◎ Image quality
Evaluation of granularity
A sample printed by a testing machine having a unit configuration shown in FIG. 1 by modifying a transfer and fixing unit of imageio MF7070 (copier made by Ricoh) is obtained. Next, the grayscale (halftone portion) formed by the dots of the print image is read at 1000 dpi by a GenaScan 5000 scanner manufactured by Dainippon Screen to obtain image data. The image data is converted into a density distribution, and the granularity is evaluated by the above equation (3).
[0047]
Example 1
<Toner formulation>
85 parts by weight of polyester resin
(Weight average molecular weight: 190000, Tm: 113 ° C)
5 parts by weight of polyethylene wax (molecular weight 900)
Magnetite fine particles 50 parts by weight
Carbon black (Ketjen Black EC:
Ketchen Black International) 2 parts by weight
1 part by weight of charge control agent (Spiron Black TR-H: Hodogaya Chemical)
After kneading at 100 ° C. using a twin-screw extruder with the above formulation, the mixture is pulverized and classified by an air-flow type pulverizer to obtain a weight average particle diameter of 11.0 μm (weight average particle diameter / number average particle diameter 1.45). Thereafter, using a Henschel mixer, 0.15% by weight of silica (R-972 Nippon Aerosil) was mixed to obtain a toner.
The volume resistivity of this toner is 1.2 × 10 ⁹ Ωcm, the average circularity was 0.88, the Tg was 78 ° C., the temperature at which the melt viscosity was 1000 PaS was 115 ° C., and the loose apparent density was 0.26 g / cc.
[0048]
Example 2
<Toner formulation>
85 parts by weight of polyester resin
(Weight average molecular weight: 367000, Tm: 157 ° C)
5 parts by weight of polyethylene wax (molecular weight 900)
Magnetite fine particles 50 parts by weight
Carbon black (Ketjen Black EC:
Ketchen Black International) 2 parts by weight
1 part by weight of charge control agent (Spiron Black TR-H: Hodogaya Chemical)
After kneading at 150 ° C. using a twin-screw extruder with the above formulation, the mixture is pulverized and classified by an air-flow type pulverizer to obtain a weight average particle diameter of 11.0 μm (weight average particle diameter / number average particle diameter 1.50). Then, using a Henschel mixer, 0.5% by weight of silica (R-972 Nippon Aerosil) was mixed to obtain a toner.
The volume resistivity of this toner is 1.2 × 10 ⁹ Ωcm, the average circularity was 0.88, the Tg was 78 ° C., the temperature at which the melt viscosity was 1000 PaS was 165 ° C., and the loose apparent density was 0.26 g / cc.
[0049]
Comparative Example 1
<Toner formulation>
92 parts by weight of polyester resin
(Weight average molecular weight: 200000, Tm: 95 ° C)
5 parts by weight of polyethylene wax (average particle size: 900 μm)
Magnetite fine particles 50 parts by weight
Carbon black (Ketjen Black EC:
Ketchen Black International) 2 parts by weight
1 part by weight of charge control agent (Spiron Black TR-H: Hodogaya Chemical)
After kneading at 80 ° C. using a twin-screw extruder with the above formulation, the mixture is pulverized and classified by an air-flow type pulverizer to obtain a weight average particle diameter of 11.0 μm (weight average particle diameter / number average particle diameter 1.45). Thereafter, using a Henschel mixer, 0.3% by weight of silica (R-972 Nippon Aerosil) was mixed to obtain a toner.
The volume resistivity of this toner is 1.2 × 10 ⁹ Ωcm, the average circularity was 0.89, the Tg was 50 ° C., the temperature at which the melt viscosity became 1000 PaS was 100 ° C., and the loose apparent density was 0.29 g / cc.
[0050]
Comparative Example 2
<Toner formulation>
92 parts by weight of polyester resin
(Weight average molecular weight: 400,000, Tm: 185 ° C)
5 parts by weight of polyethylene wax (average particle size: 900 μm)
Magnetite fine particles 50 parts by weight
Carbon black (Ketjen Black EC:
Ketchen Black International) 2 parts by weight
1 part by weight of charge control agent (Spiron Black TR-H: Hodogaya Chemical)
After kneading at 170 ° C. using a twin-screw extruder with the above formulation, the mixture is pulverized and classified by an air-flow type pulverizer to obtain a weight average particle diameter of 11.0 μm (weight average particle diameter / number average particle diameter 1.41). Thereafter, using a Henschel mixer, 0.15% by weight of silica (R-972 Nippon Aerosil) was mixed to obtain a toner.
The volume resistivity of this toner is 1.2 × 10 ⁹ Ωcm, the average circularity was 0.89, the Tg was 75 ° C., the temperature at which the melt viscosity became 1000 PaS was 185 ° C., and the loose apparent density was 0.29 g / cc.
[0051]
Comparative Example 3
The procedure of Example 1 was repeated, except that the toner of Example 1 was used and an OPC photoconductor (organic optical semiconductor) was used at the time of evaluation.
[0052]
Comparative Example 4
Using the toner of Example 1, the pressure between the transfer device and the photoconductor at the time of evaluation was 105 N / cm. ² Same as above except
[0053]
Example 3
<Toner formulation>
93 parts by weight of polyester resin
(Weight average molecular weight: 305000, Tm: 145 ° C)
3 parts by weight of polypropylene wax (molecular weight 8000)
Magnetite fine particles 50 parts by weight
Carbon black (Ketjen Black EC:
Ketchen Black International) 3 parts by weight
1 part by weight of charge control agent (Spiron Black TR-H: Hodogaya Chemical)
After kneading at 120 ° C. using a twin-screw extruder with the above formulation, the mixture is pulverized and classified by an air-flow type pulverizer to obtain a weight average particle size of 9.0 μm (weight average particle size / number average particle size 1.45). Thereafter, using a Henschel mixer, 1.0% by weight of silica (R-972 Nippon Aerosil) was mixed to obtain a toner.
The volume resistivity of this toner is 1.2 × 10 ⁹ Ωcm, the average circularity was 0.87, the Tg was 72 ° C., the temperature at which the melt viscosity was 1000 PaS was 170 ° C., and the loose apparent density was 0.25 g / cc.
[0054]
Example 4
The procedure of Example 3 was repeated, except that the toner of Example 3 was used and the evaluation machine was modified as described below.
In the remodeling of the evaluation machine, the characteristics over time were confirmed when the transfer unit and the cleaning unit were separated apart from each other except when an image was formed, and when the transfer unit and the cleaning unit were always in contact and used.
As a result, in a machine that has been in constant contact with the machine, the toner sticks to the tip of the cleaning blade, causing poor cleaning. Smear of the photoreceptor, image background smear, black streaks, etc. are small from about 50,000 sheets. There has occurred.
On the other hand, under the condition that the transfer unit and the cleaning unit were separated apart from the time of image formation, no problem occurred even in the same test, and a normal image was obtained.
[0055]
Example 5
<Toner formulation>
93 parts by weight of polyester resin
(Weight average molecular weight: 285000, Tm: 145 ° C)
3 parts by weight of polypropylene wax (molecular weight 8000)
Magnetite fine particles 50 parts by weight
Carbon black (Ketjen Black EC:
Ketchen Black International) 3 parts by weight
1 part by weight of charge control agent (Spiron Black TR-H: Hodogaya Chemical)
After kneading at 120 ° C. using a twin-screw extruder with the above formulation, the mixture is pulverized and classified by an air-flow type pulverizer to obtain a weight average particle size of 5.0 μm (weight average particle size / number average particle size 1.45). Thereafter, using a Henschel mixer, 1.0% by weight of silica (R-972 Nippon Aerosil) was mixed to obtain a toner.
The volume resistivity of this toner is 9 × 10 ⁸ Ωcm, the average circularity was 0.87, the Tg was 72 ° C., the temperature at which the melt viscosity was 1000 PaS was 170 ° C., and the loose apparent density was 0.25 g / cc.
[0056]
Example 6
<Toner formulation>
91 parts by weight of styrene-n-butyl acrylate copolymer
(Weight average molecular weight: 125000, Tm: 125 ° C)
5 parts by weight of rice wax
Magnetite fine particles 50 parts by weight
Carbon black (Ketjen Black EC:
Ketchen Black International) 3 parts by weight
1 part by weight of charge control agent (Spiron Black TR-H: Hodogaya Chemical)
After kneading at 90 ° C. using a twin-screw extruder with the above formulation, the mixture is pulverized and classified by a mechanical pulverizer to obtain a weight average particle size of 4.5 μm (weight average particle size / number average particle size 1.36). Thereafter, using a Henschel mixer, 1.0% by weight of silica (R-972 Nippon Aerosil) was mixed to obtain a toner.
The volume resistivity of this toner is 8 × 10 ⁸ Ωcm, the average circularity was 0.91, Tg was 72 ° C., the temperature at which the melt viscosity was 1000 PaS was 115 ° C., and the loose apparent density was 0.26 g / cc.
[0057]
Example 7
<Toner formulation>
91 parts by weight of polyester resin
(Weight average molecular weight: 250,000, Tm: 150 ° C)
5 parts by weight of carnauba wax (average particle size: 300 μm)
Magnetite fine particles 50 parts by weight
Carbon black (Ketjen Black EC:
Ketchen Black International) 3 parts by weight
1 part by weight of charge control agent (Spiron Black TR-H: Hodogaya Chemical)
After kneading at 140 ° C. using a twin-screw 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 1.20). Thereafter, using a Henschel mixer, 0.75% by weight of silica (R-972 Nippon Aerosil) was mixed to obtain a toner.
The volume resistivity of this toner is 8 × 10 ⁸ Ωcm, the average circularity was 0.95, the Tg was 72 ° C., the temperature at which the melt viscosity was 1000 PaS was 172 ° C., and the loose apparent density was 0.25 g / cc.
[0058]
Example 8
<Toner formulation>
61 parts by weight of polyester resin
(Weight average molecular weight: 310,000, Tm: 145 ° C)
Styrene-n-butyl acrylate polymer
(Weight average molecular weight: 85000, Tm: 115 ° C) 30 parts by weight
5 parts by weight of carnauba wax (average particle size: 300 μm)
Magnetite fine particles 50 parts by weight
Carbon black (Ketjen Black EC:
Ketchen Black International) 3 parts by weight
1 part by weight of charge control agent (Spiron Black TR-H: Hodogaya Chemical)
After kneading at 130 ° C. using a twin-screw extruder with the above formulation, the mixture is 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 1.15). Thereafter, using a Henschel mixer, 0.75% by weight of silica (R-972 Nippon Aerosil) was mixed to obtain a toner.
The volume resistivity of this toner is 8 × 10 ⁸ Ωcm, the average circularity was 0.95, the Tg was 65 ° C., the temperature at which the melt viscosity was 1000 PaS was 118 ° C., and the loose apparent density was 0.25 g / cc.
[0059]
Example 9
<Toner formulation>
51 parts by weight of polyester resin
(Weight average molecular weight: 310,000, Tm: 155 ° C)
Styrene-n-butyl acrylate copolymer 40 parts by weight
(Weight average molecular weight: 85000, Tm: 120 ° C)
5 parts by weight of carnauba wax
Magnetite fine particles 50 parts by weight
Carbon black (Ketjen Black EC:
Ketchen Black International) 3 parts by weight
1 part by weight of charge control agent (Spiron Black TR-H: Hodogaya Chemical)
After kneading at 145 ° C. using a twin-screw extruder with the above formulation, the mixture is 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, 0.75% by weight of silica (R-972 Nippon Aerosil) was mixed to obtain a toner.
The volume resistivity of this toner is 6 × 10 ⁸ Ωcm, the average circularity was 0.95, the Tg was 65 ° C., the temperature at which the melt viscosity became 1000 PaS was 140 ° C., and the loose apparent density was 0.26 g / cc.
[0060]
Example 10
<Toner formulation>
45 parts by weight of polyester resin
(Weight average molecular weight: 310,000, Tm: 155 ° C)
46 parts by weight of styrene-n-butyl acrylate copolymer
(Weight average molecular weight: 85000, Tm: 120 ° C)
5 parts by weight of carnauba wax
Magnetite fine particles 50 parts by weight
Carbon black (Ketjen Black EC:
Ketchen Black International) 3 parts by weight
1 part by weight of charge control agent (Spiron Black TR-H: Hodogaya Chemical)
After kneading at 140 ° C. using a twin-screw extruder with the above formulation, the mixture is 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 1.26). Thereafter, using a Henschel mixer, 0.75% by weight of silica (R-972 Nippon Aerosil) was mixed to obtain a toner.
The volume resistivity of this toner is 9 × 10 ⁸ Ωcm, the average circularity was 0.95, the Tg was 65 ° C., the temperature at which the melt viscosity became 1000 PaS was 135 ° C., and the loose apparent density was 0.33 g / cc.
[0061]
[Table 2]

[0062]
【The invention's effect】
The present invention relates to an image forming method in which transfer and primary fixing are performed simultaneously, and then secondary fixing is performed, wherein an electrostatic latent image on the photosensitive member is electrostatically induced by a low-resistance toner of one-component development using an amorphous silicone photosensitive member. And the pressure between the transfer device and the photoreceptor is 10 to 100 N / cm. ² The temperature applied to the transfer material of the transfer device is in the range of the glass transition temperature Tg of the toner and the softening temperature Tm of the toner, and the magnetic one-component toner having the softening temperature Tm of 100 to 160 ° C. is selected as the toner. During formation, image deterioration is prevented in the transfer process in which image deterioration is likely to occur. As a final image, improved dot reproducibility and line reproducibility are obtained, and a high-quality image with good granularity is formed. be able to.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram showing a digital monochrome embodiment in an image forming apparatus of the present invention.
FIG. 2 is a schematic diagram of a configuration of a developing device using a one-component low-resistance magnetic toner.
[Explanation of symbols]
1: Drum-shaped photoreceptor
2: Charger
3: Exposure means
31: Scanner
32: Polygon motor
33: Mirror
4: developing means
41: developing sleeve
5: transfer means
52: transfer roller (primary fixing roller)
53: Transfer belt
54: Tension roller
55: Transfer belt cleaning means
56: heating means
57: Temperature detection means
6: Cleaning means
61: Blade
62: Brush
63: Zinc stearate
7: fixing means
71: Fixing roller
72: pressure roller
73: heating means
74: heating means
101: Transfer material bank
102: Paper feed roller
103: Paper feed roller
104: resist roller
105: paper transport guide means
106: Transfer material bank
107: paper feed roller
108: Paper feed roller

Claims (9)

Using a photoreceptor carrying an electrostatic latent image, a developing device, a transfer device having a roller pressed against the photoreceptor, and an image forming apparatus having a heat roller fixing device, heat and pressure are applied to toner and transfer paper in a transfer process. Is provided through a roller, and the transfer and the primary fixing are performed simultaneously, and the primary fixed transfer paper separated from the photoreceptor is fixed by the secondary fixing, and an amorphous silicone photoreceptor is used as the photoreceptor. The pressure between the transfer device and the photoreceptor is 10 to 100 N / cm ² , the temperature applied to the transfer material of the transfer device is in the range from the glass transition temperature Tg of the toner to the toner softening temperature Tm. An image forming method, comprising: developing, and using a magnetic one-component toner having a softening temperature Tm of 100 to 160 ° C. as the toner. The image forming apparatus further includes a cleaning unit, and the developing device, the transfer device, and the cleaning unit are provided with a contact / separation mechanism with a photosensitive member, and are separated from the photosensitive member except during image formation. 2. The image forming method according to claim 1, wherein the image forming method is maintained. 3. The image forming method according to claim 1, wherein the weight average particle diameter of the toner is 3.0 to 10.0 [mu] m. 4. The image forming method according to claim 1, wherein the degree of dispersion of the particle diameter of the toner (weight average particle diameter / number average particle diameter) is 1.4 or less. The image forming method according to claim 1, wherein the volume resistivity of the toner is 1 × 10 ⁹ Ωcm or less. The image forming method according to claim 1, wherein the toner has an average circularity of 0.92 to 0.99. The image forming method according to claim 1, wherein the glass transition temperature Tg of the toner is 50 to 70 ° C. 8. The image forming method according to claim 1, wherein the temperature at which the melt viscosity of the toner becomes 1000 PaS is 120 to 170 ° C. 9. 9. The image forming method according to claim 1, wherein the loose apparent density of the toner is 0.27 g / cc or more.

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