JP4276796B2 - Developing unit and image forming apparatus - Google Patents

Description

（式中、Ｘは４価の芳香族環若しくは脂肪族環基、Ｒは２価の有機基、ｎは５以上の整数を表す）
一般的にポリイミドは高強度で剛直な樹脂として知られるが、主鎖にシロキサン構造が導入されることで柔軟性が付与され、更に離型性も向上するという利点も生まれる。従って、上記材料を少なくとも表面に含むことで現像ローラの耐摩耗性、トナー離型性を満足することが可能になる。
【００４８】
このようなポリイミド変性シリコーン樹脂は、シロキサンジアミン、芳香族ジアミン、テトラカルボン酸二無水物とからなる混合物を原料として製造することが出来る。
【００４９】
シロキサンジアミン化合物としては、
H₂N-R₁-(-SiR₂R₃-O-)n-SiR₄R₅-R₆-NH₂
(R₁,R₆は２価の有機基、R₂〜R₅はアルキル基、フェニル基、又は置換フェニル基を示し、nは５〜５０の整数を示す)
が一般式として示され、具体的には、ビス（３−アミノプロピル）テトラメチルジシロキサン、ビス（１０−アミノデカメチレン）テトラメチルジシロキサン、アミノプロピル末端基を有するジメチルシロキサン４量体、８量体、ビス（３−アミノフェノキシメチル）テトラメチルジシロキサン等が挙げられる。
【００５０】
本発明に用いられる芳香族ジアミンは例えば、（１） ビフェニル系ジアミン化合物、ジフェニルエーテル系ジアミン化合物、ベンゾフェノン系ジアミン化合物、ジフェニルスルホン系ジアミン化合物、ジフェニルメタン系ジアミン化合物、２，２−ビス（フェニル）プロパンなどのジフェニルアルカン系ジアミン化合物、２，２−ビス（フェニル）ヘキサフルオロプロパン系ジアミン系化合物、ジフェニレンスルホン系ジアミン化合物、（２） ジ（フェノキシ）ベンゼン系ジアミン化合物、ジ（フェニル）ベンゼン系ジアミン化合物、（３） ジ（フェノキシフェニル）ヘキサフルオロプロパン系ジアミン系化合物、ビス（フェノキシフェニル）プロパン系ジアミン系化合物物などの「芳香族環（ベンゼン環など）を２個以上、特に２〜５個有する芳香族ジアミン化合物」を主として含有する芳香族ジアミンを挙げることができ、それらを単独、あるいは、混合物として使用することができる。
【００５１】
前記芳香族ジアミンとしては、特に、１，４−ジアミノジフェニルエーテル、１，３−ジアミノジフェニルエーテルなどのジフェニルエーテル系ジアミン化合物、１，３−ジ（４−アミノフェノキシ）ベンゼン、１，４−ビス（４−アミノフェノキシ）ベンゼンなどのジ（フェノキシ）ベンゼン系ジアミン化合物、２，２−ビス〔４−（４−アミノフェノキシ）フェニル〕プロパン、２，２−ビス〔４−（３−アミノフェノキシ）フェニル〕プロパン等のビス（フェノキシフェニル）プロパン系ジアミン系化合物を挙げることが出来る。
【００５２】
次に本発明に用いるテトラカルボン酸二無水物を具体的に挙げると、テトラカルボン酸二無水物としてピロメリト酸二無水物、３，３‘、４，４’−ジフェニルスルホンテトラカルボン酸二無水物、３，３‘，４，４’−ベンゾフェノンテトラカルボン酸二無水物、３，３‘，４，４’−ビフェニルテトラカルボン酸二無水物、２，３‘，３，４’−ビフェニルテトラカルボン酸二無水物、ビス（３，４−ジカルボキシフェニル）エーテル二無水物、４，４‘−ビス（３，４−ジカルボキシフェノキシ）ジフェニルスルホン二無水物、エチレングリコールビストリメリテート二無水物、２，２−ビス［４−（３，４−ジカルボキシフェノキシ）フェニル］プロパン二無水物等を、’，４，４’−ジフェニルスルホンテトラカルボン酸二無水物、３，３’，４，４’−ビフェニルテトラカルボン酸二無水物、２，３’，３，４’−ビフェニルテトラカルボン酸二無水物等が挙げられる。
【００５３】
本発明で用いられるポリイミド変性シリコーン樹脂は、上記に挙げた化合物を用いて公知の方法により製造することが出来る。例えばこれらを有機溶媒中、必要に応じてトリブチルアミン、トリエチルアミン、亜リン酸トリフェニル等の触媒存在下で加熱し直接ポリイミドを得る方法、テトラカルボン酸二無水物とジアミンとを有機溶媒中反応させポリイミドの前駆体であるポリアミド酸を得た後、必要に応じてｐ−トルエンスルホン酸等の脱水触媒を加え、加熱によりイミド化を行うことでポリイミドを得る方法、或いはこのポリアミド酸を、無水酢酸、無水プロピオン酸、無水安息香酸等の酸無水物、ジシクロヘキシルカルボジイミド等のカルボジイミド化合物等の脱水閉環剤と必要に応じてピリジン、イソキノリン、イミダゾール、トリエチルアミン等の閉環触媒を添加して化学閉環させる方法等がある。
【００５４】
本発明の現像ローラは少なくとも表面にポリイミド変性シリコーン樹脂が構成されていれば良く、必要に応じて適宜他の有機又は無機材料と混合して用いることが出来る。その例を具体的に述べる。
[抵抗制御剤の添加]
本発明の現像ローラは導電性にすることで、現像後に現像ローラ表面近傍に残留する摩擦帯電電荷を速やかに消失することが可能である。図５には例として負帯電トナーの場合を示した。この場合、トナーとの摩擦帯電で発生した対向電荷は、トナーの現像後現像ローラの表面近傍に残留する。これが次回の現像迄滞留し続けると（ネガ）残像として現れてしまう。この残留電荷を解消するために除電部材を現像ローラの表面に当接してリークする手段もあるが、トナー薄層や表面層の摩耗等に悪影響を及ぼす不具合があった。
【００５５】
本発明は現像ローラのポリイミド変性シリコーン樹脂を含む表面層の体積抵抗を１０^１２Ω・cm以下にする事により容易に残留電荷の消失を可能にし、残像の発生を防止した。体積抵抗が１０^１２Ω・cmを越えると、残留電荷の速やかな消失が行えず、残像が発生する。
【００５６】
本発明の現像ローラに用いる抵抗制御剤は通常の一般的なものが使用できる。具体的に挙げればケッチェンブラック、アセチレンブラック等のカーボンブラックやＮｉパウダー等の金属微粉末、酸化チタン、酸化亜鉛等の金属酸化物などの材料や第４級アンモニウム塩基、カルボン酸基、スルホン酸基、硫酸エステル基、リン酸エステル基などを含有する有機化合物もしくは重合体、エーテルエステルアミドもしくはエーテルアミドイミド重合体、エチレンオキサイド−エピハロヒドリン共重合体、メトキシポリエチレングリコールアクリレートなどで代表される導電性ユニットを有する化合物または高分子化合物などの有機帯電防止剤などの有機帯電防止剤等が用いることが出来る。
[帯電制御剤の添加]
本発明の現像ローラは、トナーの帯電極性に適した帯電制御剤を添加することでトナーの帯電特性を改善することが出来る。例えば、正帯電性トナー用に使用される電荷制御剤としては、アゾ−クロム錯塩染料に代表される金属錯塩染料、ヒドロキシ安息香酸誘導体や芳香族ジカルボン酸、アントラニル酸誘導体の金属錯塩化合物や金属塩化合物、有機ホウ素化合物及びビフェノール化合物あるいはオリゴマー型である。
【００５７】
本発明に用いるポリイミド変性シリコーン樹脂は、構造中にシロキサン成分を含有するところから摩擦帯電系列上若干負帯電性に位置する。従って、負帯電性トナーを使用する場合、正帯電性の帯電制御剤を添加してトナー帯電性を増大する事が特に有効である。正帯電性の帯電制御剤とはポリイミド変性シリコーン樹脂に対して摩擦帯電系列上正帯電性側に位置していることを意味し、摩擦帯電系列は両者を摩擦帯電させ、環状ポリオレフィンの帯電極性（及び帯電電位）を表面電位計で測定することにより簡便に知ることが出来る。
【００５８】
例えば、使用する材料がポリマーの場合、ポリイミド変性シリコーン樹脂を表面に設けたローラを図２に代表される現像装置に設置し、表面に使用する材料を塗布若しくは貼付したりしたブレードと摺接回転させ、ローラの帯電極性（電位）を測定することにより分かる。（その時トナー、供給ローラ等現像ローラには他部材は摺接させない）又、粉体や液体の場合は現像ローラに用いた環状ポリオレフィンに材料を添加し、ブレード表面に設置した後前述の方法と同様にローラ帯電極性を測定することにより、知ることが出来る。好適に用いられる負帯電性トナー用に使用される電荷制御剤の例としては、ニグロシンに代表されるアジン系染料、トリフェニルメタン染料に代表される塩基性染料、塩基性染料のレーキ化顔料、母骨格に４級アンモニウム残基を導入した金属錯塩染料等である。
【００５９】
特に好ましい添加剤は、下記の代表例で示される４級アンモニウム塩基含有マレイミド樹脂、４級アンモニウム塩基含有メタクリルイミド樹脂、等である。
【００６０】
【化２】

これは４級アンモニウムを含有することで優れた正帯電性を示すばかりでなく、電気特性が導電性であるという特徴を有する。又本発明に用いるポリイミド変性シリコーン樹脂と同様のイミド系材料なので親和性があり有機導電剤として好適に用いることが出来る。これらの材料を使用することで抵抗のバラツキが無く均一に導電性を制御することが出来る。
【００６１】
上記の材料はポリイミド変性シリコーン樹脂１００質量部に対して１５質量部以上添加することが好ましい。添加量が１５質量部未満であると充分に抵抗が低下しない。
【００６２】
本発明の少なくともポリイミド変性シリコーン樹脂を含む層には抵抗制御剤、帯電制御剤の他に必要に応じて各種の有機・無機材料と混合し用いることが出来る。
【００６３】
混合することの出来る他の有機樹脂材料としては、アルキド樹脂、塩素化ポリエーテル、塩素化ポリエチレン、エポキシ樹脂、フッ素樹脂、フェノール樹脂、ポリアミド、ポリカーボネート、ポリエチレン、メタクリル樹脂、ポリプロピレン、ポリスチレン系樹脂、ポリウレタン、ポリ塩化ビニル、ポリ塩化ビニリデン、シリコーン樹脂等が挙げられる。これらは溶剤に溶解して用いたり、どちらか一方を樹脂微粒子の状態で混合したりすることも可能である。
【００６４】
弾性層用材料は一般的なものを使用することが出来る。
【００６５】
具体的には、ポリウレタン、ブチルゴム、ニトリルゴム、エピクロルヒドリンゴム、ポリイソプレンゴム、ポリブタジエンゴム、シリコーンゴム、フッ素ゴム、スチレン−ブタジエンゴム、エチレン−プロピレンゴム、エチレン−プロピレン−ジエンゴム、クロロプレンゴム、アクリルゴム、及びこれらの混合物等を使用することが出来る。これらのゴム材料は一部を除き通常絶縁性であるが、前述の様にバイアス電圧を付与する場合前記した抵抗制御剤を添加して導電性にして使用することも可能である。
【００６６】
つぎに、本発明の現像ローラの製造方法について説明する。
[導電層の成型方法]
本発明の現像ローラの成形にあたっては、導電性支持体と弾性層形成用のゴム組成物を金型内で同時に加熱、加圧するプレス成形方法、導電性支持体とゴム組成物を押出機でクロスヘッドを用いて一体に分出しした後、ギヤーオーブンまたは赤外線炉で一次加硫する押出成形方法、導電性支持体を成形金型内にセットした後、この金型内に上記組成物を注入し加熱する射出成形方法等が用いられ、必要に応じて表面を研磨することも可能である。
[ポリイミド変性シリコーン樹脂を溶剤に溶解して塗工成型する方法]
ポリイミド変性シリコーン樹脂を溶剤に溶解後現像ローラを作成する場合は、常法に従って行うことができ、例えば、前述した各成分を溶媒に溶解または分散させた液状組成物を、適当なキャリアー（支持体）上に流延し、次いで、溶剤を乾燥除去することで行うことができる。
【００６７】
キャリアーとしては、格別制限はなく、一般的な溶液流延法で用いられるものが使用され、例えば、ＳＵＳ、Ａｌ等の金属製ローラ、導電性樹脂ローラ、ゴムローラ、などを挙げることができる。
【００６８】
溶剤としては、例えば、Ｎ−メチル−２−ピロリドン、Ｎ，Ｎ−ジメチルアセトアミド、Ｎ，Ｎ−ジメチルホルムアミド、ジメチルスルホキシド、スルホラン、ヘキサメチルリン酸トリアミド、１，３−ジメチル−２−イミダゾリドン、ヘキサン、ベンゼン、トルエン、キシレン、メチルエチルケトン、アセトン、ジエチルエーテル、テトラヒドロフラン、ジオキサン、１,２−ジメトキシメタン、ジエチレングリコールジメチルエーテル、メチルセロソルブ、セロソルブアセテート、メタノール、エタノール、プロパノール、イソプロパノール、酢酸メチル、酢酸エチル、アセトニトリル、塩化メチレン、クロロホルム、四塩化炭素、クロロベンゼン、ジクロロベンゼン、ジクロロエタン、トリクロロエタン等が挙げられ、これらの中から、各成分が溶解・分散するように種類と量を適宜選択して使用する。
【００６９】
溶剤中のポリイミド変性シリコーン樹脂の濃度は、製造する膜厚に応じて適宜選択されるが、通常０．１〜６０質量％、好ましくは１〜５０質量％、より好ましくは５〜４５質量％の範囲である。環状オレフィン系ポリマーの濃度がこの範囲にあるときに、膜厚調製が容易でかつ製膜性にも優れ好適である。
【００７０】
液状組成物をキャリアー上に流延する方法としては、格別制限されないが、例えば、ドクターナイフ、メイア・バー、ロール・コートなどを用いて行うことができる。液状組成物の流延は、スプレー、ハケ、ロール、スピンコート、ディッピングなどで塗布することにより行える。１回の塗布で所望の膜厚が得られない場合は、繰り返し塗布することができる。
【００７１】
【実施例】
実施例および比較例を挙げて、本発明をさらに説明する。なお、本発明は、以下に説明する実施例に限定されるものではない。
[実施例１]
＜現像ローラ表面層形成成分＞
ポリイミド変性シリコーン樹脂（Ｘ−２２−８９１７；信越化学工業）
１００質量部
シクロヘキサノン １００質量部
メチルエチルケトン １００質量部
上記塗布液をＳＵＳ板（０．１mm厚）にディッピングコートし、２００℃／１時間恒温槽中に放置し、試料板とした（膜厚２０μm）。
＜薄層規制部材の評価＞
▲１▼トナー離型性試験
試料板を図９に示した様にトナー（リコーシアントナー タイプ4100）と接触し、実験室用簡易プレス成型機を用い９８０ｋＰａ，５０℃，１ｈｒの条件で加熱、加圧した。試験後、２９４ｋＰａのエアーでトナーをブローオフし、トナー残留状態を下記のように目視ランク評価した。
【００７２】
離型性ランク
ランク８ 極めて容易にトナーが除去される
７ 若干時間を要するが完全にトナーが除去される
６ 僅かに（数％以下）トナーが残留する
５ 数％〜１／３程度のトナーが残留する
４ １／３〜２／３程度のトナーが残留する
３ ２／３以上トナーが残留する
２ 全面にトナーが残留する（トナー粒子として存在）
１ 全面にトナーが残留する
（トナー粒子として存在せず、粒子同士融着）
▲２▼空回し試験
同様の現像ローラ表面層形成成分を１６ｍｍφＡｌ芯金にスプレー塗工し、２００℃／１時間恒温槽中に放置した後取り出し、徐冷した後表面を研磨し、現像ローラとした。これを図２に示した現像装置に装着し、１００時間の空回し試験を行った。現像装置の各部材には次のものを用いた。
【００７３】
トナー リコーシアントナー タイプ4100
薄層ブレード ＳＵＳ製１００μm厚
供給ローラ 導電ウレタンスポンジ
線速 現像ローラ＝１００ｍｍ／ｓｅｃ、
供給ローラ＝１２０ｍｍ／ｓｅｃ
電位 現像ローラ＝接地、供給ローラ＝−１５０Ｖ、
薄層規制部材＝フロート
空回し中はトナーの薄層状態を観察した。空回し後現像ローラ上のトナーをエアーブローし、表面上の残留トナーをテープ転写し、これを白紙に貼付し、その画像濃度を測定した（測定装置；Ｘ−Ｒｉｔｅ ９３８ Ｓｐｅｃｔｒｏｄｅｎｓｉｔｏｍｅｔｅｒ）。ブランクの濃度も測定し、その差をフィルミングトナー量の指標値ΔＩＤ（フィルミング）とした。
【００７４】
次に、現像ローラ径をレーザーマイクロケージ（ＬＳ３１００；キーエンス社製）で測定し、空回し前後の差から摩耗量（μm）を算出した。
[実施例２]
実施例１で用いたポリイミド変性シリコーン樹脂（Ｘ−２２−８９１７）をポリイミド変性シリコーン樹脂（Ｘ−２２−８９０４；信越化学）にした以外は全て同様に試料、ローラを作製し、同様の評価を行った。
[実施例３]
＜ポリイミド変性シリコーン樹脂の合成＞
乾燥窒素ガス導入管、冷却器、温度計、撹拌機を備えた四口フラスコに、脱水精製したＮ−メチル−２−ピロリドン(ＮＭＰ)７９１ｇを入れ、窒素ガスを流しながら１０分間激しく撹拌した後、２，２−ビス（４−（４−アミノフェノキシ）フェニル）プロパン（ＢＡＰＰ）０．１０ｍｏｌ、ジアミノポリジメチルシロキサン（Ｘ−２２−１６１ＡＳ；信越化学）０．１０ｍｏｌを投入し、系を６０℃に加熱し、均一になるまで撹拌した。次に系を氷水浴で５℃以下に冷却し、無水トリメリット酸０．４２ｍｏｌを添加し、その後３時間撹拌を続けた。この間フラスコは５℃以下に保った。その後、窒素ガス導入管と冷却器を外し、キシレンを満たしたディーン・スターク管をフラスコに装着し、系にキシレン１９８ｇを添加した。油浴にかえて系を約１７５℃に加熱し発生する水を系外に除いた。４時間加熱して系からの水の発生は認められなくなった後、冷却し、この反応溶液を大量のメタノール中に投入して、樹脂を析出させた。固形分を濾過後、８０℃で１２時間減圧乾燥し溶剤を除き、シリコーン変性ポリイミド樹脂Ａを得た。
【００７５】
得られた樹脂を実施例１と同様に試料、ローラを作製し、同様の評価を行った。
[比較例１]
＜現像ローラ表面層形成成分＞
ポリイミド樹脂（ユーピレックスＳ：宇部興産（株）） １００質量部
Ｎメチル２ピロリドン ５００質量部
上記材料を実施例１と同様に試料、ローラを作製し、同様の評価を行った。
[比較例２]
＜現像ローラ表面層形成成分＞
シリコーン樹脂（ＳＲ２４１１；トーレシリコーン） １００質量部
トルエン １００質量部
上記材料を実施例１と同様に試料、ローラを作製し、同様の評価を行った。
[比較例３]

上記材料を実施例１と同様に試料、ローラを作製し、同様の評価を行った。
【００７６】
結果を表１に示した。
【００７７】
【表１】

[実施例４]

実施例２で用いた表面層形成成分に上記カーボンブラックを添加、７２時間ボールミル分散した。これをスプレー塗工し、実施例２と同様に現像ローラを得た。表面層の膜厚は１５μmである。
【００７８】
この現像ローラの体積抵抗をＤＣ１００Ｖで１分後の抵抗値から次式を用いて算出した。
【００７９】
体積抵抗Ｒ（Ω・cm）＝（抵抗測定値Ｒ´）×ｌｎ｛（２πＬ）／（ａ／ｂ）｝
Ｌ；主電極巾、ａ；現像ローラ径、ｂ；芯金径
カーボンブラック添加量と体積抵抗の結果を図６に示す。
【００８０】
次に実施例１と同様の現像装置にこれを装着し、ベルト感光体を使用した画像形成装置を用い、残像度を測定した。
【００８１】
残像性の評価
図７に示すようなパターン画像を出力し残像性を評価した。すなわち、図７中黒ベタ帯（図中梨地で示す。）を現像後、網点を現像し、黒ベタ帯の位置に相当する網点の画像濃度（ＩＤ_l）と黒ベタ帯相当部以外の網点の画像濃度（ＩＤ_h）をマクベス濃度計により測定し、その比（ＩＤ_l／ＩＤ_h）により残像性を評価した。すなわち、比が１であれば残像は発生しておらず良好であるが、１よりはずれるほど残像の程度が悪いことになる。残像度の許容範囲は１±０．１である。
【００８２】
抵抗と残像度の結果を図８に示した。
[実施例５]
＜弾性層形成成分＞
シリコーンゴム（ＳＨ８３１Ｕ；トーレシリコーン） １００質量部
カーボンブラック・サーマルブラック（旭カーボン社製） １２質量部
加硫剤（Ｃ８；信越化学） ２質量部
上記成分を２本ロールで混練し、予め接着プライマーを塗布した８φＳＵＳ芯金と共に成型用金型で175℃、10分間、前記芯金と加硫接着成形した。その後、オーブン中で 200℃、４時間二次加硫を行い、円筒研削盤で研磨して層厚４ｍｍの導電弾性層を得た。（電気抵抗約１０^５Ω）
実施例４で用いた現像ローラ表面層形成成分（カーボンブラック含有量３０質量部品）を上記弾性層にスプレー塗工し、同様の方法で現像ローラを得た。表面層の膜厚は１０μmである。これを図１に示したドラム感光体を用いた画像形成装置に装着し、１０万枚の通紙試験を行った。試験前後の残像度、試験後のΔＩＤ離型性、摩耗量、ワレ（マイクロスコープによる観察）を測定した
結果を表２に示す。
【００８３】
【表２】

[実施例６]

実施例５と同様に弾性層に上記表面層形成成分を形成し、体積抵抗及びΔＩＤ（地汚れ）、トナー帯電量、付着量、残像度を測定した。結果を表３に示した。
【００８４】
【表３】

ΔＩＤ（地汚れ）；測定装置；Ｘ−Ｒｉｔｅ ９３８ Ｓｐｅｃｔｒｏｄｅｎｓｉｔｏｍｅｔｅｒで地汚れ濃度を測定
トナー帯電量、付着量；吸引法
【発明の効果】
本発明によれば表面に少なくともポリイミド変性シリコーン樹脂を含有することで、トナー離型性、耐摩耗性の優れた現像ローラを有する現像ユニット（現像装置）が提供される。
【００８５】
また、本発明の現像装置を使用した画像形成装置は残像のない高画質な画像を長期にわたって提供することが出来る。
【図面の簡単な説明】
【図１】 本実施の形態に係る電子写真装置の概略図である。
【図２】 本実施の形態に係る現像装置の概略図である。
【図３】 本実施の形態に係る現像ローラの一例の概略図である。
【図４】 本実施の形態に係る現像ローラの他の一例の概略図である。
【図５】 トナーの挙動を説明するための図である。
【図６】 カーボンブラック添加量と体積抵抗の関係を示すグラフ図である。
【図７】 残像性を評価するために出力するパターン画像を示す図である。
【図８】 抵抗と残像度との関係を示すグラフ図である。
【図９】 トナー離型性試験に用いるトナーと接触させた試験板を示した図である。
【符号の説明】
１０ 電子写真装置
１２ 感光体
１４ 除電ランプ
１６ 帯電チャージャ
２０ 画像露光部
２２ 現像装置
２６ 転写チャージャ
３４ ファーブラシ
３６ クリーニングブラシ
４０ 現像ローラ
４２ 供給ローラ
４４ 薄層規制部材
４６ 軸
４８ 芯金
５０ 表面層
５２ ゴム層[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a one-component developing device and an image forming apparatus used in an image forming apparatus such as a copying machine, a facsimile machine, and a printer.
[0002]
[Prior art]
A so-called electrophotographic image forming apparatus performs printing by the following process.
[0003]
That is, the surface of the photoreceptor is uniformly charged by the charging device, and an electrostatic latent image based on image information by the optical system is formed on the surface. Next, when the electrostatic latent image passes through the opposite position of the developing device, the latent image is visualized by adhesion of toner, superimposed on the recording material conveyed at the same time, and transferred using a transfer device. The toner image is transferred to a recording material. The transferred toner image is fixed on the recording material by passing through the fixing device. On the other hand, the residual toner is removed from the photoconductor after the transfer process by a cleaning device, and the residual charge on the photoconductor is neutralized by a static elimination device.
[0004]
As one of the developing devices used in such an image forming apparatus, a one-component developing system using a one-component toner is generally used.
[0005]
A typical example of this one-component development method will be described.
[0006]
First, the one-component toner frictionally charged at the contact portion between the developing roller and the replenishing roller rotating in the same direction or in the opposite direction while being pressed against the developing roller with a predetermined amount of biting is caused by sliding friction between the developing roller and the replenishing roller. Adheres to the developing roller. Further, the one-component toner adhered to the developing roller is further frictionally charged at the contact portion between the developing roller and the thin layer forming member provided in contact with the surface of the developing roller, and the thickness of the toner layer is regulated. A uniform toner thin layer is formed on the developing roller. The toner thin layer is supplied to the photosensitive member side while being held by the developing roller. Thereafter, at the facing portion between the developing roller and the photoreceptor, the one-component toner supplied from the developing roller is developed and developed by being attracted to the electrostatic latent image on the surface of the photoreceptor by the potential difference between the developing roller and the photoreceptor. Imaged.
[0007]
The one-component development method is roughly classified into a contact development method and a non-contact development method depending on the contact state between the developing roller and the photosensitive member.
[0008]
In the case of the former method, in order to stably contact the developing roller and the photosensitive member, it is particularly necessary to impart flexibility to one or both of the structures or materials. For this reason, an endless or endless belt is used as the photosensitive member, and a flexible material or structure such as rubber or sponge has been used as the developing roller.
[0009]
However, from the viewpoint of the apparatus cost, since it is possible to reduce the cost by using a drum rather than a belt for the photosensitive member, it has been required to give the developing roller more flexibility.
[0010]
Since the developing roller surface member used in the developing device is in constant contact with the toner, it is required to have excellent releasability from the toner and wear resistance and little deterioration in physical properties, and several materials have been proposed in the past.
[0011]
Examples of using materials having excellent wear resistance include dispersion strengthened carbon fibers (Japanese Patent Laid-Open No. 61-23171), examples containing glass powder in ceramic paint (Japanese Patent Laid-Open No. 4-7568), Many materials have been proposed, such as silicone rubber containing specific silica (Japanese Patent Laid-Open No. 9-292768) and an example in which the surface is coated with polyamide (Japanese Patent Laid-Open No. 6-149031).
[0012]
Further, as an example of improving the releasability, a phenolic resin surface coating film containing conductive carbon and graphite was formed (Japanese Patent Laid-Open No. 3-12676), and a titanate coupling agent was used. Examples used (JP-A-4-19761), examples containing a fluorine-based surfactant (JP-A-4-22979), examples using a solid lubricant (JP-A-8-21726), etc. There is.
[0013]
Further, as an example of trying to solve both characteristics, there is an example in which crystallinity and amorphous polyamide resin are mixed (Japanese Patent Laid-Open No. 4-247478).
[0014]
[Problems to be solved by the invention]
However, in the above conventional example, the toner having excellent toner releasability has a surface that prevents the toner from adhering due to the gradual wear of the surface, and it is difficult to achieve both the mold release and wear characteristics. It was.
[0015]
The present invention is intended to solve the problems that the conventional techniques cannot solve.
[0016]
That is, a first object of the present invention is to provide a developing unit and an image forming apparatus that can satisfy the toner releasability and the abrasion resistance of the developing roller at the same time and can obtain a stable toner thin layer.
[0017]
A second object of the present invention is to provide a developing unit and an image forming apparatus that can obtain a high-quality image with no afterimage.
[0018]
A third object of the present invention is to provide an image forming apparatus with high image quality and high durability.
[0019]
[Means for Solving the Problems]
  To achieve the above objective,
  According to a first aspect of the present invention, there is provided a developing roller that moves while carrying toner on a surface thereof and conveys the toner onto an image carrier, and the developing roller via the toner carried on the developing roller. And a carrying thickness regulating member (thin layer regulating member) that contacts the toner and regulates the carrying thickness of the toner, and visualizes the latent image on the image carrier using the toner conveyed by the developing roller. In the one-component developing unit, at least the surface of the developing roller is made of a material containing a polyimide-modified silicone resin.
  Further, in the invention of the developing unit according to claim 1, the volume resistance of the portion made of the material containing the polyimide-modified silicone resin is 10 ¹² It is characterized by being Ω · cm or less. Here, the part comprised from the material containing a polyimide modified silicone resin means the surface or surface layer comprised from the material containing a polyimide modified silicone resin, or the inside or inner layer comprised from the material containing a polyimide modified silicone resin. .
[0020]
  By using the polyimide-modified silicone resin having excellent releasability and wear resistance on the surface of the developing roller according to the above configuration of the invention of claim 1, toner adhesion does not occur and wear resistance is good. It is possible to obtain a developing unit in which toner chargeability and thin layer uniformity are stable.
  In addition, according to the above-described configuration of the invention of claim 1, after the development, the triboelectric charge existing in the vicinity of the surface of the developing roller disappears rapidly, the afterimage caused by the residual charge is eliminated, and a developing unit capable of providing a high-quality image is obtained. be able to.
[0021]
According to a second aspect of the present invention, the developing roller is composed of a plurality of layers, at least a surface layer is composed of a material containing the polyimide-modified silicone resin, and an elastic layer is formed on a layer other than the surface layer. It is characterized by having.
[0022]
According to the above construction of the invention of claim 2, particularly when the photosensitive member is a drum, the developing roller can be provided with flexibility so that a developing nip necessary for contact development can be secured, and stable contact development can be performed. A developing unit capable of being obtained can be obtained.
[0025]
  Claims3In the invention of the development unit of the present invention, the portion composed of the material containing the polyimide-modified silicone resin may be any one or both of a quaternary ammonium salt-containing maleimide resin and a quaternary ammonium base-containing methacrylimide resin. It contains 15 mass parts or more with respect to 100 mass parts.
[0026]
  Claim3With the above configuration of the invention, it is possible to obtain a developing unit that not only can control the resistance uniformly, but also can control the toner charging property of the developing roller at the same time.
[0027]
  Claims4The image forming apparatus according to the present invention is characterized by comprising the above-described developing unit, charging unit, exposure unit, transfer unit, cleaning unit, and electrophotographic photosensitive member as an image carrier.
[0028]
  Claim4With the above configuration of the invention, an image forming apparatus having high image quality and high durability can be obtained.
[0029]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment in which the present invention is applied to an electrophotographic apparatus which is an image forming apparatus will be described.
[0030]
First, a schematic configuration of the electrophotographic apparatus according to the present embodiment will be described with reference to FIG.
[0031]
An electrophotographic apparatus (image forming apparatus) 10 is disposed on the upper surface of a drum-shaped photosensitive member (electrophotographic photosensitive member) 12, close to the circumference, and counterclockwise in a counterclockwise direction. Charger (charge unit) 16, eraser 18, image exposure unit (exposure unit) 20, developing device (development unit) 22, pre-transfer charger 24, transfer charger (transfer unit) 26, separation charger 28, separation claw 30, before cleaning A charger 32, a fur brush 34, and a cleaning brush 36 are sequentially provided. Further, a registration roller 38 for feeding the transfer paper 38 between the photosensitive member 12 and the transfer charger 26 and the separation charger 28 is provided.
[0032]
In the electrophotographic method using the electrophotographic apparatus 10 described above, the photosensitive member 12 rotates counterclockwise, is negatively (or positively) charged by the charging charger 16, and is electrostatically charged by exposure from the image exposure unit 20. A latent image is formed on the photoreceptor 12.
[0033]
The photoconductor 12 includes a drum-shaped conductive support and a photoconductive layer in close contact with the upper surface thereof.
[0034]
As the transfer means, the above charger can be generally used, but a combination of a transfer charger and a separation charger as shown in FIG. 1 is effective.
[0035]
Further, as a light source used in the image exposure unit 20, the static elimination lamp 14, etc., a fluorescent lamp, a tungsten lamp, a halogen lamp, a mercury lamp, a sodium lamp, a light emitting diode (LED), a semiconductor laser (LD), an electroluminescence (EL), etc. Can be used. Various types of filters such as a sharp cut filter, a band pass filter, a near infrared cut filter, a dichroic filter, an interference filter, and a color temperature conversion filter can be used to irradiate only light in a desired wavelength range. Such a light source or the like can also be used when light is irradiated onto the photosensitive member by providing a transfer process, a cleaning process, or a pre-exposure process using light irradiation together.
[0036]
In the developing device 22, the electrostatic latent image is developed by attaching toner onto the photosensitive member 12, the charged state of the toner image is adjusted by the pre-transfer charger 24, and then the toner image is transferred onto the transfer paper 38 by the transfer charger 26. Then, the electrostatic charge between the photosensitive member 12 and the transfer paper 38 is eliminated by the separation charger 28, and the transfer paper 38 is separated from the photosensitive member 12 by the separation claw 30. After the transfer paper 38 is separated, the surface of the photoreceptor 1 is cleaned by the pre-cleaning charger 32, the fur brush 34, and the cleaning brush 36 (cleaning unit). This cleaning can also be performed by removing the remaining toner using only the cleaning brush 36.
[0037]
When image exposure is performed by negatively (or positively) charging the photoreceptor 12, a negative (or positive) electrostatic latent image is formed on the photoreceptor 12. A positive image can be obtained by developing the toner with positively (or negatively) charged toner (electric detection fine particles), and a negative image can be obtained by developing the toner with a negatively (or positively) charged toner. A known method can be applied to the developing unit, and a known method is also used for the charge eliminating unit.
[0038]
In this example, the conductive support of the photoreceptor is shown as a drum, but a sheet or endless belt can be used. As the pre-cleaning charger, known charging means such as a corotron, a scorotron, a solid state charger (solid state charger), a charging roller and the like can be used. In addition, the above charging means can be normally used for the transfer charger and the separation charger, and a charger in which the transfer charger and the separation charger are integrated is efficient and preferable. As the cleaning brush, known brushes such as a fur brush and a mag fur brush can be used.
[0039]
The internal structure of the developing device 22 will be further described with reference to FIG. 2 shows a state in which the apparatus of FIG. 1 is viewed from the back side of the drawing.
[0040]
The toner is sent to the developing roller 40 side by an agitator (not shown). That is, it moves as indicated by the white arrow in FIG. 2 and moves to the toner reservoir formed at the pressure contact portion between the supply roller 42 and the developing roller 40. The supply roller 42 rotates in contact with the developing roller 40 to perform frictional charging of the toner. The charged toner is carried on the developing roller 40 and is transferred to a thin layer regulating member (carrying thickness regulating member) 44. Moving. Then, the thin layer regulating member 44 comes into contact with the developing roller 40 with respect to the rotation of the developing roller 40 and is conveyed to the developing area after being adjusted to an appropriate and uniform toner layer thickness (carrying thickness). Development is performed by transferring toner to the photosensitive drum 12 on which the latent image has been written by the exposure device (image exposure unit 20).
[0041]
In FIG. 2, the photosensitive drum 12 and the developing roller 40 are in a non-contact state, but it is also possible for both to contact and develop. In this case, by making the photosensitive member into a belt instead of a drum, or using an elastic body for the developing roller, one or both of them is flexible and can be bent and deformed to have a flexible structure and material. It is common to secure a development area.
[0042]
The surface of the supply roller 42 is preferably formed of a foamed elastic body. As the foamed elastic body, for example, foamed polyurethane having a cell diameter of 50 μm and an Asker C hardness of 30 ° can be used. Carbon black or the like can be added to make it conductive. In that case, by forming a bias electric field with the developing roller 40, the toner supply property to the developing roller 40, the charging property, and the like can be controlled.
[0043]
Next, the developing roller 40 of the present invention will be described.
[0044]
FIG. 3 shows an example in which the surface layer 50 of the present invention is placed on a conductive support represented by a metal such as Al or SUS (a shaft indicated by reference numeral 46 and a cored bar indicated by reference numeral 48). FIG. 4 shows an example in which an elastic layer 50 is further provided on the core metal 48 and the surface layer 50 of the present invention is installed on the elastic layer 50. The conductive support may have a hollow structure for weight reduction.
[0045]
The developing roller 40 may be provided with a special functional layer such as an oil resistant layer or an adhesive layer between the layers as necessary.
[0046]
The polyimide-modified silicone resin used on at least the surface of the developing roller 40 can be represented by the following general formula.
[0047]
[Chemical 1]

(Wherein X represents a tetravalent aromatic ring or aliphatic ring group, R represents a divalent organic group, and n represents an integer of 5 or more)
In general, polyimide is known as a high-strength and rigid resin, but the introduction of a siloxane structure in the main chain gives flexibility and further improves the releasability. Therefore, it is possible to satisfy the wear resistance and toner releasability of the developing roller by including the above material on at least the surface.
[0048]
Such a polyimide-modified silicone resin can be produced using a mixture of siloxane diamine, aromatic diamine, and tetracarboxylic dianhydride as a raw material.
[0049]
As a siloxane diamine compound,
H₂N-R₁-(-SiR₂R_Three-O-) n-SiR_FourR_Five-R₆-NH₂
(R₁, R₆Is a divalent organic group, R₂~ R_FiveRepresents an alkyl group, a phenyl group, or a substituted phenyl group, and n represents an integer of 5 to 50)
Are represented by the general formula, specifically, bis (3-aminopropyl) tetramethyldisiloxane, bis (10-aminodecamethylene) tetramethyldisiloxane, dimethylsiloxane tetramer having aminopropyl end groups, 8 And bis (3-aminophenoxymethyl) tetramethyldisiloxane.
[0050]
Examples of the aromatic diamine used in the present invention include (1) biphenyl diamine compounds, diphenyl ether diamine compounds, benzophenone diamine compounds, diphenyl sulfone diamine compounds, diphenylmethane diamine compounds, 2,2-bis (phenyl) propane, and the like. Diphenylalkane diamine compounds, 2,2-bis (phenyl) hexafluoropropane diamine compounds, diphenylenesulfone diamine compounds, (2) di (phenoxy) benzene diamine compounds, di (phenyl) benzene diamine compounds (3) Two or more “aromatic rings (benzene ring etc.) such as di (phenoxyphenyl) hexafluoropropane diamine compound, bis (phenoxyphenyl) propane diamine compound, etc., especially 2-5 The aromatic diamine compound "having primarily mention may be made of aromatic diamines containing them alone or can be used as a mixture.
[0051]
Examples of the aromatic diamine include diphenyl ether diamine compounds such as 1,4-diaminodiphenyl ether and 1,3-diaminodiphenyl ether, 1,3-di (4-aminophenoxy) benzene, 1,4-bis (4- Di (phenoxy) benzene diamine compounds such as aminophenoxy) benzene, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 2,2-bis [4- (3-aminophenoxy) phenyl] propane And bis (phenoxyphenyl) propane-based diamine-based compounds.
[0052]
Next, specific examples of the tetracarboxylic dianhydride used in the present invention include pyromellitic dianhydride, 3,3 ′, 4,4′-diphenylsulfone tetracarboxylic dianhydride as the tetracarboxylic dianhydride. 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 2,3 ′, 3,4′-biphenyltetracarboxylic Acid dianhydride, bis (3,4-dicarboxyphenyl) ether dianhydride, 4,4′-bis (3,4-dicarboxyphenoxy) diphenylsulfone dianhydride, ethylene glycol bistrimellitate dianhydride, 2,2-bis [4- (3,4-dicarboxyphenoxy) phenyl] propane dianhydride or the like is converted into ', 4,4'-diphenylsulfonetetracarboxylic dianhydride. 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride, 2,3', 3,4'-biphenyltetracarboxylic dianhydride, and the like.
[0053]
The polyimide-modified silicone resin used in the present invention can be produced by a known method using the compounds listed above. For example, these are heated in an organic solvent in the presence of a catalyst such as tributylamine, triethylamine, or triphenyl phosphite as necessary, and a polyimide is obtained directly. Tetracarboxylic dianhydride and diamine are reacted in an organic solvent. After obtaining polyamic acid which is a precursor of polyimide, a method of obtaining polyimide by adding a dehydration catalyst such as p-toluenesulfonic acid as necessary and imidizing by heating, or this polyamic acid, acetic anhydride Dehydrating and ring-closing agents such as acid anhydrides such as propionic anhydride and benzoic anhydride, and carbodiimide compounds such as dicyclohexylcarbodiimide, and a method of chemically ring-closing such as adding a ring-closing catalyst such as pyridine, isoquinoline, imidazole and triethylamine as necessary There is.
[0054]
The developing roller of the present invention only needs to have a polyimide-modified silicone resin formed on at least the surface thereof, and can be appropriately mixed with other organic or inorganic materials as necessary. The example is described concretely.
[Addition of resistance control agent]
By making the developing roller of the present invention conductive, it is possible to quickly eliminate the triboelectric charge remaining in the vicinity of the surface of the developing roller after development. FIG. 5 shows the case of negatively charged toner as an example. In this case, the counter charge generated by frictional charging with the toner remains in the vicinity of the surface of the developing roller after the toner is developed. If this stays until the next development (negative), it will appear as an afterimage. In order to eliminate this residual charge, there is a means for causing the discharging member to come into contact with the surface of the developing roller to leak, but there is a problem that adversely affects the wear of the toner thin layer or the surface layer.
[0055]
In the present invention, the volume resistance of the surface layer containing the polyimide-modified silicone resin of the developing roller is 10¹²Residual charges can be easily lost by setting the resistance to Ω · cm or less, preventing the occurrence of afterimages. Volume resistance is 10¹²If it exceeds Ω · cm, the residual charge cannot be quickly lost and an afterimage occurs.
[0056]
As the resistance control agent used in the developing roller of the present invention, an ordinary general agent can be used. Specifically, carbon black such as ketjen black and acetylene black, fine metal powder such as Ni powder, metal oxide such as titanium oxide and zinc oxide, quaternary ammonium base, carboxylic acid group, sulfonic acid Group, sulfate group, phosphoric ester group-containing organic compound or polymer, ether ester amide or ether amide imide polymer, ethylene oxide-epihalohydrin copolymer, conductive unit represented by methoxy polyethylene glycol acrylate, etc. An organic antistatic agent such as an organic antistatic agent such as a compound having high molecular weight or a polymer compound can be used.
[Addition of charge control agent]
The developing roller of the present invention can improve the charging characteristics of the toner by adding a charge control agent suitable for the charging polarity of the toner. For example, charge control agents used for positively chargeable toners include metal complex dyes represented by azo-chromium complex dyes, metal complexes of hydroxybenzoic acid derivatives, aromatic dicarboxylic acids, anthranilic acid derivatives, and metal salts. Compound, organoboron compound and biphenol compound or oligomer type.
[0057]
The polyimide-modified silicone resin used in the present invention is slightly negatively charged in the triboelectric charging series because it contains a siloxane component in the structure. Therefore, when using a negatively chargeable toner, it is particularly effective to increase the toner chargeability by adding a positively chargeable charge control agent. The positively chargeable charge control agent means that the polyimide-modified silicone resin is positioned on the positively chargeable side in the triboelectric charging series. The triboelectric charging series frictionally charges both, and the charging polarity of the cyclic polyolefin ( And charging potential) can be easily determined by measuring with a surface potential meter.
[0058]
For example, when the material to be used is a polymer, a roller having a polyimide-modified silicone resin provided on the surface is installed in a developing device represented by FIG. 2, and is rotated in sliding contact with a blade on which the material to be used is applied or pasted. It can be found by measuring the charging polarity (potential) of the roller. (At that time, other members are not brought into sliding contact with the developing roller such as toner, supply roller, etc.) In the case of powder or liquid, the material is added to the cyclic polyolefin used for the developing roller and placed on the blade surface. Similarly, it can be known by measuring the roller charging polarity. Examples of charge control agents used for negatively charged toners that are suitably used include azine dyes typified by nigrosine, basic dyes typified by triphenylmethane dyes, lake dyes of basic dyes, Metal complex dyes having a quaternary ammonium residue introduced into the mother skeleton.
[0059]
Particularly preferred additives are a quaternary ammonium base-containing maleimide resin and a quaternary ammonium base-containing methacrylimide resin shown in the following representative examples.
[0060]
[Chemical formula 2]

This not only exhibits excellent positive chargeability by containing quaternary ammonium, but also has a characteristic that electrical characteristics are conductive. Further, since it is an imide material similar to the polyimide-modified silicone resin used in the present invention, it has an affinity and can be suitably used as an organic conductive agent. By using these materials, there is no variation in resistance, and the conductivity can be controlled uniformly.
[0061]
The above material is preferably added in an amount of 15 parts by mass or more based on 100 parts by mass of the polyimide-modified silicone resin. When the addition amount is less than 15 parts by mass, the resistance is not sufficiently lowered.
[0062]
The layer containing at least the polyimide-modified silicone resin of the present invention can be used by mixing with various organic / inorganic materials as required in addition to the resistance control agent and the charge control agent.
[0063]
Other organic resin materials that can be mixed include alkyd resin, chlorinated polyether, chlorinated polyethylene, epoxy resin, fluororesin, phenol resin, polyamide, polycarbonate, polyethylene, methacrylic resin, polypropylene, polystyrene resin, polyurethane , Polyvinyl chloride, polyvinylidene chloride, silicone resin and the like. These can be used by dissolving in a solvent, or one of them can be mixed in the form of resin fine particles.
[0064]
A general material can be used for the elastic layer material.
[0065]
Specifically, polyurethane, butyl rubber, nitrile rubber, epichlorohydrin rubber, polyisoprene rubber, polybutadiene rubber, silicone rubber, fluorine rubber, styrene-butadiene rubber, ethylene-propylene rubber, ethylene-propylene-diene rubber, chloroprene rubber, acrylic rubber, And a mixture thereof can be used. These rubber materials are usually insulative except for a part, but when a bias voltage is applied as described above, the above-described resistance control agent can be added to make them conductive.
[0066]
Next, a method for producing the developing roller of the present invention will be described.
[Method of forming conductive layer]
In forming the developing roller of the present invention, the conductive support and the rubber composition for forming the elastic layer are simultaneously heated and pressed in a mold, and the conductive support and the rubber composition are crossed with an extruder. After an integral dispensing using a head, an extrusion molding method in which primary vulcanization is performed in a gear oven or an infrared furnace, a conductive support is set in a molding die, and then the above composition is injected into the die. A heating injection molding method or the like is used, and the surface can be polished as necessary.
[Method of coating and molding polyimide-modified silicone resin dissolved in solvent]
When a developing roller is prepared after dissolving the polyimide-modified silicone resin in a solvent, it can be carried out according to a conventional method. For example, a liquid composition in which each of the above-described components is dissolved or dispersed in a solvent can be prepared with an appropriate carrier (support). ) And then drying to remove the solvent.
[0067]
The carrier is not particularly limited, and those used in a general solution casting method are used. Examples thereof include metal rollers such as SUS and Al, conductive resin rollers, and rubber rollers.
[0068]
Examples of the solvent include N-methyl-2-pyrrolidone, N, N-dimethylacetamide, N, N-dimethylformamide, dimethyl sulfoxide, sulfolane, hexamethylphosphoric triamide, 1,3-dimethyl-2-imidazolidone, and hexane. , Benzene, toluene, xylene, methyl ethyl ketone, acetone, diethyl ether, tetrahydrofuran, dioxane, 1,2-dimethoxymethane, diethylene glycol dimethyl ether, methyl cellosolve, cellosolve acetate, methanol, ethanol, propanol, isopropanol, methyl acetate, ethyl acetate, acetonitrile, Examples include methylene chloride, chloroform, carbon tetrachloride, chlorobenzene, dichlorobenzene, dichloroethane, and trichloroethane. The type and amount are appropriately selected and used so that each component is dissolved and dispersed.
[0069]
Although the density | concentration of the polyimide modified silicone resin in a solvent is suitably selected according to the film thickness to manufacture, it is 0.1-60 mass% normally, Preferably it is 1-50 mass%, More preferably, it is 5-45 mass%. It is a range. When the concentration of the cyclic olefin polymer is in this range, the film thickness can be easily adjusted, and the film forming property is excellent and suitable.
[0070]
The method of casting the liquid composition on the carrier is not particularly limited, but can be performed using, for example, a doctor knife, Meir bar, roll coat or the like. The liquid composition can be cast by spraying, brushing, rolling, spin coating, dipping or the like. When a desired film thickness cannot be obtained by a single application, it can be applied repeatedly.
[0071]
【Example】
The present invention will be further described with reference to examples and comparative examples. In addition, this invention is not limited to the Example demonstrated below.
[Example 1]
<Developing roller surface layer forming component>
Polyimide-modified silicone resin (X-22-8917; Shin-Etsu Chemical)
100 parts by weight
100 parts by mass of cyclohexanone
100 parts by mass of methyl ethyl ketone
The coating solution was dipped on a SUS plate (0.1 mm thick) and left in a constant temperature bath at 200 ° C. for 1 hour to obtain a sample plate (film thickness 20 μm).
<Evaluation of thin layer regulating member>
(1) Toner releasability test
As shown in FIG. 9, the sample plate was brought into contact with toner (Ricohian toner type 4100), and heated and pressurized under the conditions of 980 kPa, 50 ° C., and 1 hr using a simple laboratory press molding machine. After the test, the toner was blown off with air of 294 kPa, and the toner remaining state was visually evaluated as follows.
[0072]
Releasability rank
Rank 8 Toner is removed very easily
7 It takes some time but the toner is completely removed
6 Slightly (less than several percent) of toner remains
5 About several to 1/3 of toner remains
4 About 1/3 to 2/3 of toner remains
3 2/3 or more toner remains
2 Toner remains on the entire surface (present as toner particles)
1 Toner remains on the entire surface
(It does not exist as toner particles, and particles are fused)
(2) Idle rotation test
The same developing roller surface layer forming component was spray-coated on a 16 mmφ Al core metal, left in a constant temperature bath at 200 ° C./1 hour, taken out, slowly cooled, and then the surface was polished to obtain a developing roller. This was mounted on the developing apparatus shown in FIG. 2 and a 100-hour idling test was conducted. The following were used for each member of the developing device.
[0073]
Toner Ricoh cyan toner type 4100
Thin blade SUS 100μm thickness
Supply roller Conductive urethane sponge
Linear speed Developing roller = 100mm / sec,
Supply roller = 120 mm / sec
Potential Developing roller = Ground, Supply roller = -150V,
Thin layer regulating member = float
During the idle rotation, the thin layer state of the toner was observed. After idling, the toner on the developing roller was blown with air, the residual toner on the surface was transferred to tape, and this was affixed to white paper, and the image density was measured (measuring device; X-Rite 938 Spectrodensitometer). The density of the blank was also measured, and the difference was used as an index value ΔID (filming) of the filming toner amount.
[0074]
Next, the developing roller diameter was measured with a laser microcage (LS3100; manufactured by Keyence Corporation), and the wear amount (μm) was calculated from the difference between before and after idling.
[Example 2]
Samples and rollers were prepared in the same manner except that the polyimide-modified silicone resin (X-22-8917) used in Example 1 was changed to a polyimide-modified silicone resin (X-22-8904; Shin-Etsu Chemical). went.
[Example 3]
<Synthesis of polyimide-modified silicone resin>
791 g of dehydrated and purified N-methyl-2-pyrrolidone (NMP) was placed in a four-necked flask equipped with a dry nitrogen gas inlet tube, a cooler, a thermometer, and a stirrer, and stirred vigorously for 10 minutes while flowing nitrogen gas. , 2,2-bis (4- (4-aminophenoxy) phenyl) propane (BAPP) 0.10 mol, diaminopolydimethylsiloxane (X-22-161AS; Shin-Etsu Chemical) 0.10 mol, and the system was heated to 60 ° C. And stirred until uniform. Next, the system was cooled to 5 ° C. or lower with an ice-water bath, 0.42 mol of trimellitic anhydride was added, and then the stirring was continued for 3 hours. During this time, the flask was kept at 5 ° C. or lower. Thereafter, the nitrogen gas inlet tube and the cooler were removed, a Dean-Stark tube filled with xylene was attached to the flask, and 198 g of xylene was added to the system. The system was changed to an oil bath and the system was heated to about 175 ° C. to remove generated water. After heating for 4 hours, generation of water from the system was not observed, and then cooling was performed. The reaction solution was poured into a large amount of methanol to precipitate a resin. After filtering solid content, it dried under reduced pressure at 80 degreeC for 12 hours, the solvent was remove | excluded, and silicone modified polyimide resin A was obtained.
[0075]
A sample and a roller were produced from the obtained resin in the same manner as in Example 1, and the same evaluation was performed.
[Comparative Example 1]
<Developing roller surface layer forming component>
Polyimide resin (Upilex S: Ube Industries, Ltd.) 100 parts by mass
500 parts by mass of N-methyl-2-pyrrolidone
Samples and rollers were produced from the above materials in the same manner as in Example 1, and the same evaluation was performed.
[Comparative Example 2]
<Developing roller surface layer forming component>
100 parts by mass of silicone resin (SR2411; Torre Silicone)
100 parts by mass of toluene
Samples and rollers were produced from the above materials in the same manner as in Example 1, and the same evaluation was performed.
[Comparative Example 3]

Samples and rollers were produced from the above materials in the same manner as in Example 1, and the same evaluation was performed.
[0076]
The results are shown in Table 1.
[0077]
[Table 1]

[Example 4]

The above-mentioned carbon black was added to the surface layer forming component used in Example 2 and dispersed in a ball mill for 72 hours. This was spray coated to obtain a developing roller as in Example 2. The film thickness of the surface layer is 15 μm.
[0078]
The volume resistance of the developing roller was calculated from the resistance value after 1 minute at DC 100 V using the following equation.
[0079]
Volume resistance R (Ω · cm) = (Measured resistance R ′) × ln {(2πL) / (a / b)}
L: main electrode width, a: developing roller diameter, b: cored bar diameter
The results of carbon black addition amount and volume resistance are shown in FIG.
[0080]
Next, this was mounted on a developing device similar to that in Example 1, and an afterimage degree was measured using an image forming apparatus using a belt photoreceptor.
[0081]
Evaluation of afterimage
A pattern image as shown in FIG. 7 was output to evaluate the afterimage properties. That is, after developing the black solid band in FIG. 7 (shown as a satin in the figure), the halftone dot is developed, and the image density (ID_l) And halftone dot image density (ID)_h) With a Macbeth densitometer, and the ratio (ID_l/ ID_h) Was evaluated for afterimage properties. That is, if the ratio is 1, the afterimage is not generated and is good, but the degree of afterimage becomes worse as the ratio is deviated from 1. The allowable range of the afterimage is 1 ± 0.1.
[0082]
The results of the resistance and the afterimage degree are shown in FIG.
[Example 5]
<Elastic layer forming component>
100 parts by mass of silicone rubber (SH831U; Torre Silicone)
Carbon black and thermal black (Asahi Carbon Co., Ltd.) 12 parts by mass
Vulcanizing agent (C8; Shin-Etsu Chemical) 2 parts by mass
The above components were kneaded with two rolls, and vulcanized and adhesive-molded with the cored bar at 175 ° C. for 10 minutes together with an 8φ SUS cored bar previously coated with an adhesive primer. Thereafter, secondary vulcanization was performed in an oven at 200 ° C. for 4 hours, and polishing was performed with a cylindrical grinder to obtain a conductive elastic layer having a layer thickness of 4 mm. (Electrical resistance about 10⁵Ω)
The developing roller surface layer forming component (carbon black content 30 mass parts) used in Example 4 was spray-coated on the elastic layer, and a developing roller was obtained in the same manner. The film thickness of the surface layer is 10 μm. This was mounted on an image forming apparatus using the drum photoreceptor shown in FIG. 1, and 100,000 sheets were tested. The afterimage degree before and after the test, ΔID releasability after the test, wear amount, crack (observation with a microscope) were measured.
The results are shown in Table 2.
[0083]
[Table 2]

[Example 6]

In the same manner as in Example 5, the surface layer forming component was formed on the elastic layer, and volume resistance, ΔID (background stain), toner charge amount, adhesion amount, and afterimage were measured. The results are shown in Table 3.
[0084]
[Table 3]

ΔID (soil); Measuring device; Soil density measured with X-Rite 938 Spectrodensitometer
Toner charge amount, adhesion amount; suction method
【The invention's effect】
According to the present invention, there is provided a developing unit (developing apparatus) having a developing roller excellent in toner releasability and abrasion resistance by containing at least a polyimide-modified silicone resin on the surface.
[0085]
An image forming apparatus using the developing device of the present invention can provide a high-quality image without an afterimage over a long period of time.
[Brief description of the drawings]
FIG. 1 is a schematic view of an electrophotographic apparatus according to an embodiment.
FIG. 2 is a schematic diagram of a developing device according to the present embodiment.
FIG. 3 is a schematic view of an example of a developing roller according to the present embodiment.
FIG. 4 is a schematic view of another example of a developing roller according to the present embodiment.
FIG. 5 is a diagram for explaining the behavior of toner.
FIG. 6 is a graph showing the relationship between the amount of carbon black added and volume resistance.
FIG. 7 is a diagram illustrating a pattern image output for evaluating afterimage characteristics.
FIG. 8 is a graph showing the relationship between resistance and afterimage strength.
FIG. 9 is a view showing a test plate brought into contact with toner used in a toner releasability test.
[Explanation of symbols]
10 Electrophotographic equipment
12 photoconductor
14 Static elimination lamp
16 Charger charger
20 Image exposure unit
22 Development device
26 Transcription charger
34 Fur Brush
36 Cleaning brush
40 Developing roller
42 Supply roller
44 Thin layer regulating member
46 axes
48 cored bar
50 Surface layer
52 Rubber layer

Claims (4)

A developing roller that moves while carrying toner on the surface and transports the toner onto the image carrier, and abuts on the developing roller via the toner carried on the developing roller to regulate the toner carrying thickness. In a one-component developing unit that visualizes a latent image on the image carrier using the toner conveyed by the developing roller, at least the surface of the developing roller is polyimide-modified. Consists of materials containing silicone resin,
A developing unit having a volume resistance of 10 ¹² Ω · cm or less at a portion composed of a material containing the polyimide-modified silicone resin .   2. The developing roller according to claim 1, wherein the developing roller is composed of a plurality of layers, at least a surface layer is composed of a material containing the polyimide-modified silicone resin, and an elastic layer is provided in a layer other than the surface layer. Development unit. The part comprised from the material containing the said polyimide modified silicone resin is 15 parts with respect to 100 mass parts of said polyimide modified silicone resin either or both of a quaternary ammonium salt containing maleimide resin and a quaternary ammonium base containing methacrylamide resin. developing unit according to claim 1 or 2, characterized in that it contains more than parts by weight. An image forming apparatus comprising: the developing unit according to claim 1, a charging unit, an exposure unit, a transfer unit, a cleaning unit, and an electrophotographic photosensitive member as an image carrier. .

Images