JP2004053918A - Intermediate transfer device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an excellent intermediate transfer device in which problems such as toner scattering, toner releasability, friction coefficient, are improved and to provide an image forming apparatus using the intermediate transfer device. <P>SOLUTION: The intermediate transfer body 11 has at least a surface layer which contains a polyimide modified silicone resin and needlelike conductive particles with a major axis length of less than 1 μm. The content of the needlelike conductive particles is equal to or less than 50 parts by weight based on 100 parts by weight of polyimide modified silicone resin. Also, it is preferable that the needlelike conductive particles are surface-treated with a silane coupling agent. It is also preferable that the volume resistivity of its surface layer is in the range of 10<SP>8</SP>Ωcm to 10<SP>12</SP>Ωcm. Additionally, the intermediate transfer body 11 preferably has a volume resistivity of 10<SP>12</SP>Ωcm or less, and an underlayer made of a rubber base material which has 95 or less in effective hardness JISA. <P>COPYRIGHT: (C)2004,JPO

Description

（式中、Ｘは４価の芳香族環若しくは脂肪族環基、Ｒ_１、Ｒ_６は２価の有機基、Ｒ_２〜Ｒ_５はアルケニル基、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層に含むことで中間転写体の耐摩耗性、トナー離型性を満足することが可能になる。
【００１４】
ポリイミド変性シリコーン樹脂の構造中、Ｒ_２〜Ｒ_５はメチル基が好適である。シロキサン構造の側鎖によって、表面特性特に摩擦係数を低減することが可能で、中間転写体の場合前述したように多くの当接部材があるために、駆動トルク等を小さくするにはその摩擦係数は０．２〜０．４の範囲であることが好ましい。ポリイミド変性シリコーン樹脂においては、シロキサンユニットとしてＲ_２〜Ｒ_５にメチル基を導入した、ジメチルシロキサンモノマー成分を用いることでそれが可能になる。
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。
【００１５】
シロキサンジアミン化合物としては、下記の一般式（２）で表すことが出来る。
Ｈ_２Ｎ−Ｒ_１−（−ＳｉＲ_２Ｒ_３−Ｏ−）ｎ−ＳｉＲ_４Ｒ_５−Ｒ_６−ＮＨ_２　…（２）
（式中、Ｒ_１、Ｒ_６は２価の有機基、Ｒ_２〜Ｒ_５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）
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。
【００１６】
ポリイミド変性シリコーン樹脂に用いる芳香族ジアミンは、例えば、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や、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や、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。
【００１７】
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。
【００１８】
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、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’−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。
【００１９】
本発明で用い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。
【００２０】
本発明で用いるポリイミド変性シリコーン樹脂は、シリコーンポリマーを架橋可能な架橋剤を適宜添加して使用することも可能である。架橋剤としては、特に限定するものではなく従来公知のものが用いられる。例えば、ベンゾイルパーオキサイド、２，４−ジクロロベンゾイルパーオキサイド、ジクミルパーオキサイド、ｔ−ブチルクミルパーオキサイド、１，１−ビス（ｔ−ブチルペロキシ）３，３，５−トリメチルシクロヘキサン等のパーオキサイド系架橋剤があげられる。これらは単独でもしくは２種以上併せて用いられる。なかでも、架橋性という観点からベンゾイルパーオキサイドを用いることが好ましい。
架橋剤の添加量は、ポリイミド変性シリコーン樹脂１００重量部に対して０．５重量部以上１０重量部以下が好ましい。添加量が０．５重量部を下回ると架橋性が十分ではなくなり、１０重量部を越えると余剰の架橋剤が中間転写体の離型性に悪影響を及ぼす。
【００２１】
中間転写体の表面層に含有する針状導電性粒子は、前述のポリイミド変性シリコーン樹脂１００重量部に対して５０重量部以下にすることで、中間転写体の摩擦係数をより良好なものに制御することが可能である。摩擦係数が大きくなると中間転写体の表面に当接するクリーニングブレードの摩耗量が増大し、その交換頻度が増えることになる。
針状導電粒子とポリイミド変性シリコーン樹脂を含む表面層は、その体積抵抗率を１０^８Ω・ｃｍ以上１０^１２Ω・ｃｍ以下の範囲に制御することで転写率を改良することが出来る。転写率が悪いと感光体や中間転写体のクリーニングへの負担が増大したり、トナーのロスが多くなったりといった不具合がある。なお、中間転写装置に要望されるトナー転写率は、一次、二次転写共に９０％以上である。
【００２２】
体積抵抗率を制御するための抵抗制御剤は、前記針状導電粒子を使用する以外にも通常の一般的な導電粒子を併用できる。具体的には、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、酸化錫、酸化チタン、酸化亜鉛等の金属酸化物や異原子（例えばアンチモンなど）ドープ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を用いることが出来る。
【００２３】
更に、針状導電粒子をシランカップリング剤で表面処理することにより、体積抵抗のバラツキを改善することができる。針状導電粒子の表面処理に使用できるシランカップリング剤としては、従来からある市販のものが使用できる。例えばＳＨ６０２０（γ−（２−アミノエチル）アミノプロピルトリメトキシシラン）、ＳＺ６０２３（γ−（２−アミノエチル）アミノプロピルメチルジメトキシシラン）、ＳＨ６０２６（アミノシラン）、ＳＺ６０３２（Ｎ−β−（Ｎ−ビニルベンジルアミノエチル）−γ−アミノプロピルトリメトキシシラン・塩酸塩）、ＳＺ６０５０（アミノシラン）、ＳＺ６０８３（γ−アニリノプロピルトリメトキシシラン）、ＡＹ４３−０２１（オクタデシルジメチル［３−（トリメトキシシリル）プロピル］アンモニウムクロライド）、ＡＹ４３−０３１（γ−ウレイドプロピルトリエトキシシラン）、ＳＺ６０３０（γ−メタクリロキシプロピルトリメトキシシラン）、ＳＨ６０４０（γ−グリシドキシプロピルトリメトキシシラン）等（いずれも東レ・ダウコーニング・シリコーン（株）製）を挙げることができる。
シランカップリング剤による針状導電粒子の表面処理は、例えば次のようにして行うことができる。針状導電粒子１００重量部に対してシランカップリング剤１重量部を添加し高速ミキサーにて５〜１０分間撹拌し、酸化錫の表面にシランカップリング剤を付着させる。次に高速ミキサーから取り出し１００〜１５０℃で１時間乾燥させる。この表面処理品は本発明に係る中間転写体を製造時（後述する）、未処理品と全く同様に取り扱うことが可能である。
【００２４】
また、表面層は、針状導電粒子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。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。
【００２５】
本発明に係る中間転写体は、針状導電粒子及び／またはポリイミド変性シリコーン樹脂を含む表面層の下層として、導電性のゴム層が設置されることが好ましい。これにより中間転写体に柔軟性が付与され、特にＯＨＰなどの硬質な転写材などにも安定な当接が確保されることで、トナーの中抜け現象等の発生が防止出来る。
ゴム層に使用する材料は一般的なものを使用することが出来る。具体的には、ポリウレタン、ブチルゴム、ニトリルブタジエンゴム、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、トナー転写率を改善出来ることから、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。その場合、ゴム層の体積抵抗は１０^１２Ω・ｃｍ以下が好ましく、更に１０^８Ω・ｃｍ以上１０^１２Ω・ｃｍ以下が最も好ましい。ゴム層の実効硬度はＪＩＳＡ９５度以下が良い。実効硬度とは中間転写体の硬度を直接硬度計で測定した値と定義され、実効硬度がＪＩＳＡ９５度を越えると十分な柔軟性が発現せずトナーの中抜け現象等が発生する。材料自体の抵抗が低く、抵抗制御剤を用いずに安定して導電性を確保できるという理由から、特に好ましくはニトリルブタジエンゴム、エピクロルヒドリンゴムである。これらのどちらか一方を用いても良いし、両者を混合して用いても構わない。
【００２６】
次に、本発明に係る中間転写体の形態について説明する。これまで説明上ドラム状の中間転写体を用いてきたが、本発明の中間転写装置はこれに制約されるものではなく、どのような形態も使用することが出来る。
図２はベルト状の中間転写体を用いた中間転写装置の一例を示す図である。ベルト状の中間転写体１１はレイアウトの自由度が大きく、装置の小型化が図れるという長所がある。なお、ベルト状の中間転写体１１の場合、層構成はポリイミド変性シリコーン樹脂を含む層単独でも構わないし、ゴムや樹脂で構成されるベルト基材の表面層にポリイミド変性シリコーン樹脂を含む層を設置しても構わない。
【００２６】
本発明に係る中間転写体の製造方法について説明する。
ポリイミド変性シリコーン樹脂に針状導電粒子を添加する方法は、樹脂の種類、形態に応じて一般的な方法を用いることが出来る。例えば、ボールミル混練、ペイントシェイカー、サンドミル、ビーズミル、バンバリー、スタチィックミキサ、２本ロール等の装置を用いることが出来る。
【００２７】
ポリイミド変性シリコーン樹脂を溶剤に溶解する成形方法の場合は、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。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、導電性樹脂製、ゴム製のローラやベルト、などを挙げることができる。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。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重量％、好ましくは１〜５０重量％、より好ましくは５〜４５重量％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。
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。
【００２８】
また、ベルト基体を作製する代表的な方法として遠心成形法がある。これは、溶剤に溶解した樹脂溶液を回転する円筒形状の成形型内部にスプレーやノズルからベルト素材としての原料溶液（以下塗布液ということがある。）を流し込んで、この成形型を高速回転させながらその遠心力により塗布液を拡げて均一な膜としてこの膜を固化させることにより無端状成形体を成形する方法（いわゆる遠心成形法）により無端ベルトを製造する方法で、この方法に従えば、塗布された塗布液は遠心力により拡げられるので、比較的均一な厚みの塗布層が得られやすい。
この遠心成形によるベルト作製は、筒状の成形型の内面に流動性の塗布液を塗布した後、膜厚を均一にするために高速の遠心力で回転して塗布液の凝集の表面エネルギーに打ち勝つ力で塗布膜を押し広げて膜の均一化を行うものである。そして、その塗布液には原料ワニスを溶剤で希釈したものが成形型に塗布される。そのため、この塗布液は、高速回転しているときは、型の内面に均一に塗布されているが、回転を止めたり、回転数を緩くするとだんだん成形型の底部に溜まってくる。したがって、この遠心成形法によれば、一定の均一な溶液膜になった状態を保ちつつ、溶剤を除去して固化させなければならない。
【００２９】
次に、図面を参照しつつ、本発明の中間転写装置を用いた画像形成装置の一例を具体的に説明する。
図３は、ベルト状中間転写体を用いたフルカラー電子写真方式の画像形成装置を示す概要構成図である。感光体１８は帯電装置２０により帯電されて露光装置２１により例えば像様に露光される。感光体１８上に形成された潜像は、現像装置１９にて１色めの現像ユニットＢｋにより顕像化され、次に中間転写体１１との当接部にて中間転写体１１へ一次転写される。一方、顕像が中間転写ベルト１１に一次転写された後、感光体１８は除電装置２４で除電され、感光体クリーニング装置２５でクリーニングされて除電ランプ２６で全面露光により残留電荷が除電された後、２色めの画像形成工程に供される。フルカラーの場合、この工程を３色或いは４色繰り返し、中間転写体１１にフルカラートナー像を形成する。中間転写体１１に形成されたフルカラートナー像は、二次転写として紙等の転写材１５上に一括転写される。ここで、転写バイアス電圧は二次転写ローラ２３により印加され、転写材１５はその後定着工程を経てフルカラー画像として出力される。
無端状の中間転写体１１は、バックアップローラ１２ａ、バイアスローラ１２ｂ、接地ローラ１２ｃ、テンションローラ１２ｄ、駆動ローラ１２ｅ等の各ローラ間に架け渡されており、図中矢印方向に回動する。図中、符号２２は電位センサ、符号２３はＰセンサである。
【００３０】
【実施例】
次に、本発明の実施形態を説明するための実施例について説明する。
（表面層）
ポリイミド変性シリコーン樹脂（信越化学工業製　Ｘ−２２−８９０４）１００重量部に対し、アンチモン（Ｓｂ）をドープした酸化錫で表面処理した針状の酸化チタン導電粒子Ａ（石原産業社製、ＨＩ−２：直径（短軸）０．０４〜０．０７μｍ、長さ（長軸）０．２〜０．３μｍ）１０重量部を添加し、ボールミルで７２時間分散した。これを実施例１とする。
実施例１に用いたポリイミド変性シリコーン樹脂（信越化学工業製　Ｘ−２２−８９０４）の代わりに、フッ素樹脂（旭硝子社製　ルミフロン６０１）を用いた。これを実施例２とする。
実施例１に用いたポリイミド変性シリコーン樹脂（信越化学工業製　Ｘ−２２−８９０４）の代わりに、シリコーン樹脂（信越化学工業製　ＫＲ３１１）を用いた。これを実施例３とする。
【００３０】
次に、実施例１〜３と同様の材料で、針状導電粒子を添加しなかった。これを順に比較例１〜３とする。
また、実施例１〜３と同様の材料で、針状の酸化チタン導電粒子Ａの代わりに針状酸化チタン導電粒子Ｂ（石原産業社製、ＦＴ２０００：直径（短軸）０．２１μｍ、長さ（長軸）２．８６μｍ）１０重量部を同様の方法で添加した。これを比較例４〜６とする。
以下の表１に上記成分の一覧を示す。
【表１】

【００３１】
上記材料を用い、試験を行った。
離型性ランク評価
　実施例１〜３及び比較例１〜６の材料をアルミニウムシート（１ｍｍ厚）に塗布して所定の温度、時間加熱した後、サンプルシートとした。これらのサンプルシートを、図４に示す様にトナー（リコー社製シアントナー　タイプ４１００）と接触させ、実験室用簡易プレス成型機を用い、１０ｋｇ／ｃｍ^２、５０℃、１ｈｒの条件で加熱、加圧した。試験後、３ｋｇ／ｃｍ^２のエアーでトナーをブローオフし、トナー残留状態を目視ランク評価した。評価結果を以下の表２に示す。
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）
なお、離型の許容はランク７以上である。
【００３２】
転写チリ評価
　アルミニウム製ドラム素管に、実施例１〜３、比較例１〜６の材料をそれぞれスプレー塗布し、所定の条件で硬化させ、単層（１５μｍ厚）のドラム状中間転写体を作製した。これを画像形成装置に装着し、一次転写（１ｄｏｔライン画像）後に中間手転写体上のトナー像を観察し（キーエンス社製　超深度形状拡大顕微鏡ＶＫ８５００）、転写チリの状態をランクＡ〜Ｅの５段階評価を行った。評価結果を表２に示す。
なお、転写チリの許容範囲はランクＡ、Ｂである。
【００３３】
【表２】

【００３４】
摩耗性試験
　実施例１に用いたポリイミド変性シリコーン樹脂（信越化学工業製　Ｘ−２２−８９０４）の代わりに、ポリイミド変性シリコーン樹脂（信越化学工業製　Ｘ−２２−８９１７）を用いたものを実施例４、ポリイミド変性シリコーン樹脂（信越化学工業製　Ｘ−２２−８９８８）を用いたものを実施例５とし、サンプルシートを作製した。
これらのサンプルシートを用い、テーバー摩耗試験（摩耗輪ＣＳ５、１ｋｇ荷重で３０００回転後試験前後の重量差）により耐摩耗性の比較を行った。上記成分と評価結果を表３に示す。
なお、テーバー摩耗量の許容範囲は上記条件で１０ｍｇ以下、好ましくは５ｍｇ以下である。
【表３】

【００３５】
摩耗係数測定
　実施例１で用いた針状導電粒子、ポリイミド変性シリコーン樹脂を用い、ポリイミド変性シリコーン樹脂１００重量部に対する針状導電粒子の添加量を、実施例１が１０重量部であるのに対し、３０重量部、５０重量部、５５重量部、６０重量部とし、順に実施例６〜９とした。
アルミニウム製ドラム素管に、実施例１、６〜９、比較例１の材料をそれぞれスプレー塗布し、所定の条件で硬化させ、単層（１５μｍ厚）のドラム状中間転写体を作製した。
この中間転写体の摩擦係数をオイラーベルト方式（荷重１００ｇ、摩擦相手：リコー製　ＰＰＣペーパータイプ６０００）で測定し、次式で算出した。針状導電粒子の添加量と摩擦係数の算出結果を表４に示す。
μ（摩擦係数）＝（π／２）×ｌｎ（測定値／荷重）
なお、摩擦係数の許容は０．６以下であり、好ましくは０．３以下である。
【表４】

【００３６】
転写率測定
　実施例１の針状導電粒子、ポリイミド変性シリコーン樹脂に加えて、カーボンブラック（デグサ社　Ｐｒｉｎｔｅｘ９０）を添加して、体積抵抗を変化させたドラム状中間転写体を作製した。体積抵抗は、実施例１の中間転写体が６．４×１０^１５Ω・ｃｍ、比較例１が１．２×１０^１６Ω・ｃｍであるのに対し、２．７×１０^１３Ω・ｃｍ、５．８×１０^１２Ω・ｃｍ、８．７×１０^１０Ω・ｃｍ、１．５×１０^８Ω・ｃｍ、８．５×１０^７Ω・ｃｍである中間転写体を順に実施例１０〜１４とした。
これらの中間転写体を転写チリ評価に用いた画像形成装置に装着し、一次転写における転写率を測定した。転写率は次式で算出した。算出結果を表５に示す。転写率％＝（中間転写ドラム上の単位面積当たりトナー付着量／ＯＰＣ上の単位面積当たりトナー付着量）×１００
トナー付着量は吸引法で測定した。
なお、転写率の許容範囲は９０％以上で、好ましくは９５％以上である。
【００３７】
体積抵抗値算出
　また、これらの中間転写体のＤＣ１００Ｖ／１分体積抵抗値を次式を用いて算出した（７ヶ所の平均値）。算出結果を表５に示す。
体積抵抗Ｒ（Ω・ｃｍ）＝（抵抗測定値Ｒ’）×ｌｎ｛（２πＬ）／（ａ／ｂ）｝
Ｌ：主電極巾（１ｃｍ）
ａ：中間転写体径
ｂ：素管径
【表５】

【００３８】
表面層形成成分
　針状導電粒子の重量部と中間転写体の体積抵抗との関係を測定した。
ポリイミド変性シリコーン樹脂（信越化学工業製　Ｘ−２２−８９０４）１００重量部、シクロヘキサノン５００重量部、メチルエチルケトン５００重量部に対し、針状導電粒子Ａ（実施例１と同様）１０、２０、３０、４０重量部をそれぞれ添加し、７２時間ボールミル分散した。これをアルミニウム製ドラム素管にスプレー塗工し、中間転写体を得た。表面層の膜厚は１５μｍである。
次に、上記針状導電粒子Ａ１００重量部に対してシランカップリング剤（トーレシリコーン社製　ＳＨ６０２０）１重量部を添加し高速ミキサーにて５分間撹拌し、酸化錫の表面にシランカップリング剤を付着させた後、高速ミキサーから取り出して１５０℃で１時間乾燥させ、シランカップリング処理針状導電粒子Ａとして、同様に中間転写体を作製した。
これらの中間転写体の体積抵抗を実施例１０〜１４と同様に測定した。又体積抵抗のバラツキの指標として（ｌｏｇ最大値−ｌｏｇ最小値）を算出した。結果を図５のグラフに示す。
なお、体積抵抗のバラツキは１．５オーダー以内が良く、１．２オーダー以内が特に好ましい。
【００３９】
（下層）
次に、下層による異常画像の有無について評価した。
ゴム層Ａとして、シリコーンゴム（トーレシリコーン社製　ＳＨ８３１Ｕ）１００重量部、カーボンブラック・サーマルブラック（旭カーボン社製）２５重量部、加硫剤（信越化学工業製　Ｃ８）２重量部、これらのゴム層成分を所定の方法で混練したのち、蒸気加硫法によりアルミニウム素管上にゴム層を成型した。層厚は２ｍｍとした。
ゴム層Ｂとして、ブチルゴム（日本合成ゴム製　Ｂｕｔｙｌ２６８（商品名））１００重量部、カーボンブラック・サーマルブラック（旭カーボン社製）３５重量部、亜鉛華５重量部、ステアリン酸１重量部、加硫用添加剤（硫黄を含む）７．５重量部を、ゴム層Ａと同様にして成型した。層厚は２ｍｍと０．２ｍｍのものを成型した。
ゴム層Ｃとして、ＥＰＤＭ（日本合成ゴム製　ＥＰ２１（商品名））１００重量部、カーボンブラック・サーマルブラック（旭カーボン社製）３５重量部、亜鉛華５重量部、ステアリン酸１重量部、加硫用添加剤（硫黄を含む）７．５重量部を、ゴム層Ａと同様にして成型した。層厚は１ｍｍと０．２ｍｍのものを成型した。
ゴム層Ｄとして、ニトリルブタジエンゴム　（日本合成ゴム製　Ｎ２２０Ｓ（商品名））１００重量部、亜鉛華５重量部、ステアリン酸１重量部、加硫用添加剤（硫黄を含む）７．５重量部をゴム層Ａと同様にして成型した。層厚は、２ｍｍとした。
ゴム層Ｅとして、エピクロルヒドリンゴム（ダイソー製エピクロマーＣＧ）１００重量部、亜鉛華５重量部、ステアリン酸１重量部、加硫用添加剤（硫黄を含む）７．５重量部を、ゴム層Ａと同様にして成型した。層厚は２ｍｍのものを成型した。
【００４０】
前記成型されたゴム層Ａ〜Ｅ上に、表面層として、ポリイミド変性シリコーン樹脂（信越化学工業製　Ｘ−２２−８９８８）１００重量部、シクロヘキサノン５００重量部、メチルエチルケトン５００重量部、表面処理導電性粒子Ａ３０重量部を所定の方法で混練したのち、スプレー塗布して中間転写体を形成した。
得られた中間転写体の実効硬度、体積抵抗（７ヶ所の平均値）、体積抵抗の最大値−最小値（ｌｏｇ最大値−ｌｏｇ最小値）を測定した。
また、これらの中間転写体を図１に示した画像形成装置に装着し、ＯＨＰシート（リコー製　ＯＨＰフィルムタイプ２）を用いて画像出力試験を行い、１ドット黒ライン中抜け画像の有無を評価した。結果を表６に示す。
【表６】

【００４１】
（シームレスベルト）
押出成型によりポリカーボネート樹脂（カーボンブラック１５重量％添加）シームレスベルトを作製した。膜厚は１５０μｍ、体積抵抗は２．８×１０^１２Ω・ｃｍであった。このシームレスベルト上に、表面層として、ポリイミド変性シリコーン樹脂（信越化学工業製　Ｘ−２２−８９８８）１００重量部、シクロヘキサノン５００重量部、メチルエチルケトン５００重量部、表面処理導電性粒子Ａ３０重量部を所定の方法で混練したのち、スプレー塗布して１２０℃／３時間硬化し、ベルト状中間転写体とした。これを図３の画像形成装置に装着し、１０万枚の連続通紙試験を行った。その結果、転写チリは試験前後で変わらずランクＡであり、トナーフィルミングも発生しなかった。
【００４２】
【発明の効果】
以上説明したように、少なくとも中間転写体の表面層に長軸長さ１μｍ未満の針状導電粒子を含有させることで、従来の欠点が改良され優れた転写率とトナー離型性の中間転写装置が得られる。又、耐摩耗性、摩擦係数、転写率、抵抗バラツキ等の改良が行われ、それらの優れた特性が長期に維持された中間転写装置を搭載する画像形成装置が得られる。
【図面の簡単な説明】
【図１】本発明の中間転写装置の一例であり、ドラム状の中間転写体を用いた概略構成図である。
【図２】本発明の中間転写装置の一例であり、ベルト状の中間転写体を用いた概略構成図である。
【図３】ベルト状中間転写体を用いたフルカラー電子写真方式の画像形成装置を示す概要構成図である。
【図４】本発明の実施例における離型性評価試験の様子を示す図である。
【図５】本発明の実施例における針状導電粒子重量部と中間転写体体積抵抗との関係を示すグラフである。
【符号の説明】
１１　中間転写体
１２　中間転写体支持ローラ
１３　中間転写クリーニング装置
１５　転写材
１８　感光体
１９　現像装置
２０　帯電装置
２１　露光装置
２２　電位センサ
２３　二次転写ローラ
２４　除電装置
２５　感光体クリーニング装置
２６　除電ランプ
２７　トナー
２８　用紙除電装置
２９　Ｐセンサ
Ａ　一次転写部
Ｂ　二次転写部[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an intermediate transfer device used in an electrophotographic image forming apparatus such as a copying machine, a printer, and a facsimile, and more specifically, an intermediate transfer drum, an intermediate transfer body such as a belt, and the like, to perform primary and secondary transfer processes. The present invention relates to an associated transfer type intermediate transfer device.
[0002]
[Prior art]
In recent years, electrophotographic image forming apparatuses capable of copying and printing full-color images have been put into practical use. As a method of transferring a full-color image to a transfer material, an intermediate transfer body double transfer method has a paper-free property. It is advantageously used because full copying is possible. The intermediate transfer body double transfer method is an intermediate transfer of yellow (Y), magenta (M), cyan (C), and black (Bk) color images formed for each color on an image carrier such as a photoconductor. This is a system in which images are sequentially superimposed and transferred on a body, and the transferred full-color toner images are collectively transferred to a transfer material, which is also simply referred to as an intermediate transfer system.
Conventionally, as an abnormal image related to the intermediate transfer method, there has been a problem of so-called toner scattering at the time of transfer (hereinafter, referred to as transfer dust). Here, the transfer dust means that at the time of the primary transfer, the visible image formed on the image carrier is not transferred to the position where it should be originally transferred, but is diffused and transferred to the peripheral portion thereof. As a result, This is a phenomenon in which an image is blurred, and particularly, the sharpness of the image is impaired in a thin line portion.
[0003]
As a typical prior art for solving the above-mentioned problem, a high-resistance toner is non-electrostatically transferred to an intermediate transfer medium according to Japanese Patent Application Laid-Open No. 63-34570 and then heated by a heating roll via a recording sheet. Japanese Patent Application Laid-Open No. 63-34571 discloses a technique of pressing and transferring and fixing a conductive toner onto an intermediate transfer medium in a non-electrostatic manner, and then performing a press transfer and fixing with a heating roll with a recording sheet interposed. Japanese Patent Application Laid-Open No. 1-282571 discloses a technique for removing static electricity of a toner image transferred by a paper peeling charger every time a toner image is transferred to an intermediate transfer medium. A technique of applying a predetermined voltage to the intermediate transfer medium during the transfer to each transfer step by making the potential higher than the immediately preceding transfer potential, according to Japanese Patent Application Laid-Open No. 4-147170, Technical like to provide means for neutralizing the previous intermediate transfer member charges leading to means for transferring an image.
[0004]
However, among these prior arts, JP-A-63-34570 and JP-A-63-34571 require a recording sheet that can be pressed and fixed by a heating roll. There is no way to take advantage of the paper-free nature. Further, in JP-A-1-282571, JP-A-2-183276, and JP-A-4-147170, in any case, it is necessary to provide a means for static elimination and voltage application and / or a control means for this. Not only does the machine control mechanism become complicated, but it also hinders downsizing of the machine.
[0005]
On the other hand, as disclosed in Japanese Patent Application Laid-Open No. 8-320622, a technique for controlling electric characteristics of an intermediate transfer member to prevent transfer dust has been proposed, and various techniques for controlling the electric characteristics of the intermediate transfer member have been proposed. There are many proposals to add a conductive agent. For example, JP-A-5-200904, JP-A-8-184981, and the like disclose techniques for adding carbon black, JP-A-8-179584, JP-A-9-50192, and JP-A-2001-201946. And the like, there is a technique of adding a conductive metal oxide, a technique of adding an ionic conductive agent in JP-A-2000-275980, and the like, a technique of adding carbon fluoride in JP-A-2000-267451, and the like. However, none of them is sufficient to prevent transfer dust, and further improvement has been demanded.
[0006]
[Problems to be solved by the invention]
An object of the present invention is to improve the above-mentioned problems. More specifically, it is an object of the present invention to provide an intermediate transfer body having an improved transfer dust by adding a specific acicular conductive agent. Another object of the present invention is to provide an excellent intermediate transfer device having improved toner releasability and friction coefficient.
Another object of the present invention is to provide a high quality image forming apparatus using the intermediate transfer device.
[0007]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present invention according to claim 1 is to sequentially superimpose a plurality of visible color developed images sequentially formed on an image carrier with toner on an intermediate transfer body running endlessly. Primary transfer together, in an intermediate transfer device that collectively and secondarily transfer the primary transfer image on the intermediate transfer body to a transfer material, the intermediate transfer body has at least a surface layer, the surface layer is long The intermediate transfer device according to the above, wherein the intermediate transfer device contains needle-like conductive particles having a shaft length of less than 1 μm.
The invention according to claim 2 is the intermediate transfer device according to claim 1, wherein the surface layer contains a polyimide-modified silicone resin.
According to a third aspect of the present invention, in the surface layer, the content of the acicular conductive particles is 50 parts by weight or less based on 100 parts by weight of the polyimide-modified silicone resin. Is an intermediate transfer device.
In the invention according to claim 4, the surface layer has a volume resistivity of 10%.⁸Ω · cm or more 10¹²The intermediate transfer device according to any one of claims 1 to 3, wherein the intermediate transfer device is in a range of Ω · cm or less.
The present invention according to claim 5 is the intermediate transfer device according to any one of claims 1 to 4, wherein the acicular conductive particles are surface-treated with a silane coupling agent.
[0008]
The present invention according to claim 6 is the intermediate transfer device according to any one of claims 1 to 5, wherein the intermediate transfer member is a seamless belt.
In the present invention according to claim 7, the intermediate transfer member has at least the surface layer and a lower layer, and the lower layer has a volume resistivity of 10%.¹²The intermediate transfer device according to any one of claims 1 to 6, wherein the intermediate transfer device is a rubber base material having a range of Ω · cm or less and an effective hardness of 95 degrees or less according to JISA.
The present invention according to claim 8 is the intermediate transfer device according to claim 7, wherein the rubber base material is nitrile-butadiene rubber and / or shrimp chlorohydrin rubber.
An image forming apparatus according to a ninth aspect of the present invention includes at least a charging device, an exposure device, a developing device, an intermediate transfer device, a cleaning device, a static elimination device, and an electrophotographic photosensitive member. The image forming apparatus according to claim 1, wherein the intermediate transfer device is the intermediate transfer device according to any one of claims 1 to 8.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
The intermediate transfer device of the present invention will be described. FIG. 1 shows a typical example of the intermediate transfer device of the present invention, and shows an example using a drum-shaped intermediate transfer member as an example.
First, the operation of the primary transfer will be described.
The toner 27 developed on the photoreceptor 18 as an image carrier by a developing device (not shown) comes into contact with the intermediate transfer body 11 rotated synchronously with the photoreceptor 18 in the primary transfer portion A, and is given a predetermined bias potential. The image is transferred to the intermediate transfer member 11. The respective toner images developed into the respective colors of black, yellow, magenta, and cyan are transferred from the photoreceptor 18 to the intermediate transfer drum 11, and the color toner images are superimposed on the intermediate transfer body 11.
[0010]
Next, the operation of the secondary transfer will be described.
The secondary transfer roller 23 is usually separated from the intermediate transfer body 11, but is closely attached to the intermediate transfer body 11 at the time of the secondary transfer. The transfer material 15 is transported in synchronization with the intermediate transfer member 11 and passes between the intermediate transfer member 11 and the secondary transfer roller 23. At this time, a bias voltage having a polarity opposite to the charging polarity of the toner is applied to the secondary transfer roller 23, and the toner 27 is secondarily transferred to the transfer material 15. Thereafter, the transfer material 15 is given a predetermined charge by the paper discharging device 28, and the remaining charge is removed, so that the transfer material 15 can be easily separated from the intermediate transfer body 11.
Thereafter, the transfer material 15 moves to a fixing step. Further, the toner 27 remaining on the intermediate transfer member 11 is removed by a predetermined intermediate transfer cleaning device 13 in contact with the intermediate transfer member 11 and is initialized. Examples of the intermediate transfer cleaning device 13 include a brush and a roller.
[0011]
Next, the configuration of the intermediate transfer member will be described.
In the drum-shaped intermediate transfer body 11, for example, a cylindrical aluminum tube is coated with various materials for improving surface characteristics and the like.
The present invention is characterized in that the intermediate transfer body 11 has at least a surface layer, and the surface layer is made of a material containing a polyimide-modified silicone resin and acicular conductive particles having a major axis length of less than 1 μm. I do.
As the acicular conductive particles, use is made of acicular tin oxide-based conductive particles, acicular titanium oxide, potassium titanate whisker, or aluminum borate whisker-based conductive particles having a tin oxide-based conductive layer adhered to the surface thereof. be able to. As a tin oxide-based conductive layer covering the surface, SnO 2₂/ Sb is preferred.
[0012]
The volume resistivity of the acicular conductive particles is several Ω · cm to 10⁸Ω · cm is preferred.
The method for measuring the volume resistivity (also referred to as specific resistance) of the conductive metal oxide particles themselves is as follows. First, conductive metal oxide particles were collected and evenly sandwiched between a pair of parallel electrodes having a diameter of dcm, and 100 kg / cm²Pressure is applied uniformly to the sample. Next, the electric resistance between the pair of plate electrodes is measured. The sample thickness of the compacted sample of the conductive metal oxide particles was measured, and the sample thickness tcm and the sample area S (cm²) And the resistance value R (Ω) previously obtained, the volume resistivity p (Ω · cm) is calculated by the following formula.
p = R · S / t (where S = πd²/ 4)
The intermediate transfer member of the present invention reduces transfer dust by including the acicular conductive particles in at least the surface layer. In this case, it is necessary that the average length of the long axis is 1 μm or less in order to ensure the toner releasability of the intermediate transfer member. Although the average particle size of the toner is several μm, the particle size distribution shows that a large number of small particle size toners of about 1 μm are contained. If the average length of the major axis of the acicular conductive particles is 1 μm, the toner is May cause adhesion. Once the toner adheres, it becomes a nucleus and the toner adhesion increases. By setting the average length of the major axis to 1 μm or less, it is possible to reduce the transfer dust and maintain the toner releasability in a good condition.
[0013]
In the present invention, a polyimide-modified silicone resin can be used on at least the surface together with the acicular conductive particles. The polyimide-modified silicone resin used in the present invention can be represented by the following general formula (1).
Embedded image

(Wherein X is a tetravalent aromatic or aliphatic ring group, R₁, R₆Is a divalent organic group, R₂~ R₅Represents an alkenyl group, an alkyl group, a phenyl group, or a substituted phenyl 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 into the main chain provides flexibility, and also has the advantage of further improving the releasability. Therefore, by including at least the above material in the surface layer, it becomes possible to satisfy the abrasion resistance and the toner release property of the intermediate transfer member.
[0014]
In the structure of the polyimide-modified silicone resin, R₂~ R₅Is preferably a methyl group. The surface properties, especially the friction coefficient, can be reduced by the side chains of the siloxane structure. In the case of the intermediate transfer member, as described above, since there are many contact members, the friction coefficient is required to reduce the driving torque and the like. Is preferably in the range of 0.2 to 0.4. In the polyimide-modified silicone resin, R is a siloxane unit.₂~ R₅This can be achieved by using a dimethylsiloxane monomer component in which a methyl group has been introduced.
Such a polyimide-modified silicone resin can be produced using a mixture of siloxane diamine, aromatic diamine, and tetracarboxylic dianhydride as a raw material.
[0015]
The siloxane diamine compound can be represented by the following general formula (2).
H₂NR₁-(-SiR₂R₃-O-) n-SiR₄R₅-R₆-NH₂… (2)
(Where R₁, R₆Is a divalent organic group, R₂~ R₅Represents an alkyl group, a phenyl group, or a substituted phenyl group, and n represents an integer of 5 to 50.
More specifically, bis (3-aminopropyl) tetramethyldisiloxane, bis (10-aminodecamethylene) tetramethyldisiloxane, tetramer, octameric dimethylsiloxane having an aminopropyl terminal group, bis (3- (Aminophenoxymethyl) tetramethyldisiloxane and the like.
[0016]
The aromatic diamine used for the polyimide-modified silicone resin includes, for example, a biphenyl-based diamine compound, a diphenylether-based diamine compound, a benzophenone-based diamine compound, a diphenylsulfone-based diamine compound, a diphenylmethane-based diamine compound, and 2,2-bis (phenyl) propane. Diphenylalkane diamine compound, 2,2-bis (phenyl) hexafluoropropane diamine compound, diphenylene sulfone diamine compound, di (phenoxy) benzene diamine compound, di (phenyl) benzene diamine compound, (Phenoxyphenyl) hexafluoropropane-based diamine compound, bis (phenoxyphenyl) propane-based diamine-based compound, etc. have two or more aromatic rings (such as benzene rings), particularly 2 to 5 The aromatic diamine compound "having primarily mention may be made of aromatic diamines containing them alone or can be used as a mixture.
[0017]
As the aromatic diamine, 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-based 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.
[0018]
Next, specific examples of the tetracarboxylic dianhydride used in the present invention include pyromellitic dianhydride and 3,3 ′, 4,4′-diphenylsulfonetetracarboxylic dianhydride as tetracarboxylic dianhydrides. 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, 3,3 ′, 4,4′-diphenylsulfonetetracarboxylic dianhydride , 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride, 2,3', 3,4'-biphenyltetracarboxylic dianhydride, and the like.
[0019]
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 the presence of a catalyst such as tributylamine, triethylamine, and triphenyl phosphite in an organic solvent, if necessary, to directly obtain polyimide, by reacting tetracarboxylic dianhydride and diamine in an organic solvent. After obtaining a polyamic acid which is a precursor of the polyimide, a method of obtaining a polyimide by adding a dehydration catalyst such as Δp-toluenesulfonic acid as necessary and performing imidization by heating, or a method of obtaining the polyamic acid by acetic anhydride A method of chemically closing a ring by adding an acid anhydride such as propionic anhydride or benzoic anhydride, a dehydrating ring-closing agent such as a carbodiimide compound such as dicyclohexylcarbodiimide and a ring-closing catalyst such as pyridine, isoquinoline, imidazole or triethylamine if necessary. There is.
[0020]
The polyimide-modified silicone resin used in the present invention can be used by appropriately adding a crosslinking agent capable of crosslinking a silicone polymer. The crosslinking agent is not particularly limited, and a conventionally known crosslinking agent may be used. For example, peroxides such as benzoyl peroxide, 2,4-dichlorobenzoyl peroxide, dicumyl peroxide, t-butylcumyl peroxide, and 1,1-bis (t-butylperoxy) 3,3,5-trimethylcyclohexane Crosslinking agents. These may be used alone or in combination of two or more. Above all, it is preferable to use benzoyl peroxide from the viewpoint of crosslinkability.
The amount of the crosslinking agent added is preferably 0.5 part by weight or more and 10 parts by weight or less based on 100 parts by weight of the polyimide-modified silicone resin. If the amount is less than 0.5 part by weight, the crosslinkability is not sufficient. If the amount exceeds 10 parts by weight, the excess crosslinking agent adversely affects the releasability of the intermediate transfer member.
[0021]
The needle-like conductive particles contained in the surface layer of the intermediate transfer body are controlled to be 50 parts by weight or less based on 100 parts by weight of the above-mentioned polyimide-modified silicone resin, so that the friction coefficient of the intermediate transfer body is controlled to be better. It is possible to do. When the coefficient of friction increases, the amount of wear of the cleaning blade in contact with the surface of the intermediate transfer member increases, and the frequency of replacement thereof increases.
The surface layer containing the acicular conductive particles and the polyimide-modified silicone resin has a volume resistivity of 10⁸Ω · cm or more 10¹²The transfer ratio can be improved by controlling the resistance to the range of Ω · cm or less. If the transfer rate is poor, there are disadvantages such as an increase in the load on cleaning of the photoconductor and the intermediate transfer body and an increase in toner loss. The toner transfer rate required for the intermediate transfer device is 90% or more for both primary and secondary transfer.
[0022]
As the resistance controlling agent for controlling the volume resistivity, ordinary general conductive particles can be used in addition to using the acicular conductive particles. Specifically, carbon black such as Ketjen black and acetylene black, metal fine powder such as Ni powder, metal oxide such as tin oxide, titanium oxide and zinc oxide, and metal oxide doped with a different atom (for example, antimony). Organic compounds or polymers containing quaternary ammonium bases, carboxylic acid groups, sulfonic acid groups, sulfate groups, phosphate groups, etc., ether ester amide or ether amide imide polymers, ethylene oxide-epihalohydrin An organic antistatic agent such as an organic antistatic agent such as a polymer, a compound having a conductive unit represented by methoxypolyethylene glycol acrylate, or a high molecular compound can be used.
[0023]
Furthermore, the surface treatment of the acicular conductive particles with a silane coupling agent can improve the variation in volume resistance. As the silane coupling agent that can be used for the surface treatment of the acicular conductive particles, a conventionally available silane coupling agent can be used. For example, SH6020 (γ- (2-aminoethyl) aminopropyltrimethoxysilane), SZ6023 (γ- (2-aminoethyl) aminopropylmethyldimethoxysilane), SH6026 (aminosilane), SZ6032 (N-β- (N-vinyl) (Benzylaminoethyl) -γ-aminopropyltrimethoxysilane.hydrochloride), SZ6050 (aminosilane), SZ6083 (γ-anilinopropyltrimethoxysilane), AY43-021 (octadecyldimethyl [3- (trimethoxysilyl) propyl]) Ammonium chloride), AY43-031 (γ-ureidopropyltriethoxysilane), SZ6030 (γ-methacryloxypropyltrimethoxysilane), SH6040 (γ-glycidoxypropyltrimethoxysilane), etc. Also manufactured by Dow Corning Toray Silicone Co., Ltd.).
The surface treatment of the acicular conductive particles with the silane coupling agent can be performed, for example, as follows. 1 part by weight of the silane coupling agent is added to 100 parts by weight of the acicular conductive particles, and the mixture is stirred for 5 to 10 minutes with a high-speed mixer to attach the silane coupling agent to the surface of the tin oxide. Next, it is taken out of the high-speed mixer and dried at 100 to 150 ° C. for 1 hour. This surface-treated product can be handled in exactly the same way as the untreated product when the intermediate transfer member according to the present invention is manufactured (described later).
[0024]
The surface layer can be used by mixing with various organic and inorganic materials as required in addition to the acicular conductive particles. Other organic resin materials that can be mixed include alkyd resin, chlorinated polyether, chlorinated polyethylene, epoxy resin, fluororesin, phenolic resin, polyamide, polycarbonate, polyethylene, methacrylic resin, polypropylene, polystyrene resin, and polyurethane. , Polyvinyl chloride, polyvinylidene chloride, silicone resin and the like. These can be used by dissolving them in a solvent, or one of them can be mixed in the state of fine resin particles.
[0025]
The intermediate transfer member according to the present invention is preferably provided with a conductive rubber layer as a lower layer of a surface layer containing acicular conductive particles and / or a polyimide-modified silicone resin. As a result, flexibility is imparted to the intermediate transfer member, and in particular, a stable contact with a hard transfer material such as OHP is ensured, so that the occurrence of a toner drop-in phenomenon can be prevented.
General materials can be used for the rubber layer. Specifically, polyurethane, butyl rubber, nitrile butadiene 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 mixtures thereof. These rubber materials are usually insulative except for a part thereof, but since they can improve the toner transfer rate, they can be made conductive by adding a resistance control agent. In that case, the volume resistance of the rubber layer is 10¹²Ω · cm or less, preferably 10⁸Ω · cm or more 10¹²Most preferably Ω · cm or less. The effective hardness of the rubber layer is preferably 95 degrees or less according to JISA. The effective hardness is defined as a value obtained by directly measuring the hardness of the intermediate transfer member with a hardness meter. When the effective hardness exceeds JISA 95 degrees, sufficient flexibility is not exhibited, and a toner drop-in phenomenon occurs. Nitrile butadiene rubber and epichlorohydrin rubber are particularly preferred because the resistance of the material itself is low and conductivity can be stably secured without using a resistance control agent. Either of these may be used, or both may be used as a mixture.
[0026]
Next, the form of the intermediate transfer member according to the present invention will be described. Although a drum-shaped intermediate transfer member has been used for the explanation so far, the intermediate transfer device of the present invention is not limited to this, and any form can be used.
FIG. 2 is a diagram illustrating an example of an intermediate transfer device using a belt-shaped intermediate transfer member. The belt-shaped intermediate transfer member 11 has advantages in that the degree of freedom in layout is large and the size of the apparatus can be reduced. In the case of the belt-shaped intermediate transfer member 11, the layer structure may be a layer containing the polyimide-modified silicone resin alone, or a layer containing the polyimide-modified silicone resin may be provided on the surface layer of the belt base made of rubber or resin. It does not matter.
[0026]
The method for producing an intermediate transfer member according to the present invention will be described.
As a method of adding the acicular conductive particles to the polyimide-modified silicone resin, a general method can be used according to the type and form of the resin. For example, a device such as a ball mill kneading, a paint shaker, a sand mill, a bead mill, a banbury, a static mixer, and a two-roll mill can be used.
[0027]
In the case of a molding method in which the polyimide-modified silicone resin is dissolved in a solvent, the molding can be carried out according to a conventional method. And then drying and removing the solvent. The carrier is not particularly limited, and those used in a general solution casting method are used. For example, SUS, a metal such as Al, a conductive resin, a rubber roller or belt, and the like can be mentioned. Can be. Examples of the solvent include N-methyl-2-pyrrolidone, N, N-dimethylacetamide, N, N-dimethylformamide, dimethylsulfoxide, sulfolane, hexamethylphosphoric triamide, 1,3-dimethyl-2-imidazolidone, 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, Methylene chloride, chloroform, carbon tetrachloride, chlorobenzene, dichlorobenzene, dichloroethane, trichloroethane, and the like. Each component uses the type and amount to dissolve and disperse appropriately selecting. The concentration of the polyimide-modified silicone resin in the solvent is appropriately selected depending on the film thickness to be produced, but is usually 0.1 to 60% by weight, preferably 1 to 50% by weight, more preferably 5 to 45% by weight. Range. When the concentration of the cyclic olefin-based polymer is in this range, the film thickness can be easily adjusted and the film-forming property is excellent, which is preferable.
The method of casting the liquid composition on the carrier is not particularly limited, and for example, can be performed using a doctor knife, a Meyer bar, a 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 one coating, the coating can be repeated.
[0028]
A typical method for producing a belt base is a centrifugal molding method. In this method, a raw material solution (hereinafter, sometimes referred to as a coating liquid) as a belt material is poured from a spray or a nozzle into a cylindrical mold that rotates a resin solution dissolved in a solvent, and the mold is rotated at a high speed. A method of manufacturing an endless belt by a method of forming an endless molded body by spreading the coating liquid by the centrifugal force and solidifying this film as a uniform film (so-called centrifugal molding method), according to this method, Since the applied coating liquid is spread by centrifugal force, a coating layer having a relatively uniform thickness is easily obtained.
In this belt production by centrifugal molding, after applying a flowable coating liquid to the inner surface of a cylindrical mold, it is rotated with high speed centrifugal force to make the film thickness uniform, and the surface energy of the aggregation of the coating liquid is reduced. The coating film is spread by the force of overcoming and the film is made uniform. Then, a solution obtained by diluting the raw material varnish with a solvent is applied to the molding die. Therefore, this coating liquid is uniformly applied to the inner surface of the mold when rotating at high speed, but gradually accumulates at the bottom of the mold when the rotation is stopped or the number of rotations is reduced. Therefore, according to this centrifugal molding method, the solvent must be removed and solidified while maintaining a uniform solution film.
[0029]
Next, an example of an image forming apparatus using the intermediate transfer device of the present invention will be specifically described with reference to the drawings.
FIG. 3 is a schematic configuration diagram showing a full-color electrophotographic image forming apparatus using a belt-shaped intermediate transfer member. The photoreceptor 18 is charged by a charging device 20 and is exposed imagewise, for example, by an exposure device 21. The latent image formed on the photoreceptor 18 is visualized by a first-color developing unit Bk in a developing device 19, and then primary-transferred to the intermediate transfer body 11 at a contact portion with the intermediate transfer body 11. Is done. On the other hand, after the developed image is primary-transferred to the intermediate transfer belt 11, the photosensitive member 18 is neutralized by the neutralizing device 24, is cleaned by the photosensitive member cleaning device 25, and after the residual charges are neutralized by the entire surface exposure by the neutralizing lamp 26. And subjected to a second color image forming process. In the case of full color, this process is repeated for three or four colors, and a full-color toner image is formed on the intermediate transfer body 11. The full-color toner image formed on the intermediate transfer body 11 is collectively transferred onto a transfer material 15 such as paper as secondary transfer. Here, the transfer bias voltage is applied by the secondary transfer roller 23, and the transfer material 15 is output as a full-color image through a fixing process thereafter.
The endless intermediate transfer body 11 is bridged between rollers such as a backup roller 12a, a bias roller 12b, a ground roller 12c, a tension roller 12d, and a drive roller 12e, and rotates in the direction of the arrow in the figure. In the figure, reference numeral 22 denotes a potential sensor, and reference numeral 23 denotes a P sensor.
[0030]
【Example】
Next, an example for describing an embodiment of the present invention will be described.
(Surface layer)
Needle-shaped titanium oxide conductive particles A (HI-Ishihara Sangyo Co., Ltd.) surface-treated with tin oxide doped with antimony (Sb) with respect to 100 parts by weight of a polyimide-modified silicone resin (X-22-8904 manufactured by Shin-Etsu Chemical Co., Ltd.) 2: 10 parts by weight of a diameter (short axis) of 0.04 to 0.07 μm and a length (long axis) of 0.2 to 0.3 μm were added, and dispersed by a ball mill for 72 hours. This is referred to as Example 1.
A fluororesin (Lumiflon 601 manufactured by Asahi Glass Co., Ltd.) was used instead of the polyimide-modified silicone resin (X-22-8904 manufactured by Shin-Etsu Chemical Co., Ltd.) used in Example 1. This is referred to as Example 2.
A silicone resin (KR311 manufactured by Shin-Etsu Chemical Co., Ltd.) was used instead of the polyimide-modified silicone resin (X-22-8904 manufactured by Shin-Etsu Chemical Co., Ltd.) used in Example 1. This is Example 3.
[0030]
Next, the same materials as in Examples 1 to 3 were used, and no acicular conductive particles were added. These are referred to as Comparative Examples 1 to 3 in order.
Further, the same material as in Examples 1 to 3 was used, and instead of the acicular titanium oxide conductive particles A, acicular titanium oxide conductive particles B (manufactured by Ishihara Sangyo Co., Ltd., FT2000: 0.21 μm in diameter (short axis), length) (Long axis) 2.86 μm) 10 parts by weight were added in the same manner. This is referred to as Comparative Examples 4 to 6.
Table 1 below shows a list of the above components.
[Table 1]

[0031]
A test was performed using the above materials.
Releasability rank evaluation
(4) The materials of Examples 1 to 3 and Comparative Examples 1 to 6 were applied to an aluminum sheet (1 mm thick) and heated at a predetermined temperature for a predetermined time to prepare a sample sheet. These sample sheets were brought into contact with a toner (Cyan Toner (Type 4100, manufactured by Ricoh Co., Ltd.)) as shown in FIG.², 50 ° C, 1 hr. After the test, 3kg / cm²The toner was blown off with the air, and the toner remaining state was visually evaluated. The evaluation results are shown in Table 2 below.
Rank 8: toner is removed very easily
7 It takes some time but the toner is completely removed
6 Slight (less than several%) toner remains
5 Several% to 1/3 of the toner remains
4 About 1/3 to 2/3 of the toner remains
3 2/3 or more toner remains
2 The toner remains on the entire surface (exists as toner particles)
1 Toner remains on the entire surface (not present as toner particles, particles fused together)
Note that the release of the mold is rank 7 or higher.
[0032]
Transcript evaluation
The materials of Examples 1 to 3 and Comparative Examples 1 to 6 were spray-coated on aluminum drum tubes, respectively, and cured under predetermined conditions to produce a single-layer (15 μm thick) drum-shaped intermediate transfer body. This was mounted on an image forming apparatus, and after the primary transfer (1 dot line image), the toner image on the intermediate hand transfer body was observed (manufactured by KEYENCE CORPORATION, ultra-depth shape enlarged microscope VK8500), and the state of the transfer dust was ranked A to E. A five-point evaluation was performed. Table 2 shows the evaluation results.
The allowable range of the transfer dust is ranks A and B.
[0033]
[Table 2]

[0034]
Abrasion test
Instead of the polyimide-modified silicone resin (Shin-Etsu Chemical Co., Ltd. X-22-8904) used in Example 1, a polyimide-modified silicone resin (Shin-Etsu Chemical Co., Ltd. X-22-8917) was used in Example 4, polyimide A sample sheet was prepared using a modified silicone resin (Shin-Etsu Chemical Co., Ltd. X-22-8988) as Example 5.
Using these sample sheets, a comparison of wear resistance was made by a Taber abrasion test (wear wheel CS5, weight difference before and after the test after 3000 rotations under a load of 1 kg and a rotation of 3000). Table 3 shows the above components and evaluation results.
The allowable range of the Taber abrasion amount is 10 mg or less, preferably 5 mg or less under the above conditions.
[Table 3]

[0035]
Wear coefficient measurement
Using the needle-shaped conductive particles used in Example 1 and the polyimide-modified silicone resin, the amount of the needle-shaped conductive particles added to 100 parts by weight of the polyimide-modified silicone resin was 30 parts by weight compared to 10 parts by weight in Example 1. Parts, 50 parts by weight, 55 parts by weight, and 60 parts by weight, and Examples 6 to 9 were taken in that order.
The materials of Examples 1, 6 to 9 and Comparative Example 1 were spray-coated on aluminum drum tubes, respectively, and cured under predetermined conditions to produce a single-layer (15 μm thick) drum-shaped intermediate transfer body.
The friction coefficient of this intermediate transfer member was measured by an Euler belt method (load: 100 g, friction partner: Ricoh PPC paper type 6000), and calculated by the following equation. Table 4 shows the addition amount of the acicular conductive particles and the calculation results of the coefficient of friction.
μ (coefficient of friction) = (π / 2) × ln (measured value / load)
The allowable coefficient of friction is 0.6 or less, preferably 0.3 or less.
[Table 4]

[0036]
Transfer rate measurement
ド ラ ム In addition to the needle-shaped conductive particles of Example 1 and the polyimide-modified silicone resin, carbon black (Printex 90, Degussa) was added to produce a drum-shaped intermediate transfer body having a changed volume resistance. The volume resistance of the intermediate transfer member of Example 1 was 6.4 × 10^FifteenΩ · cm, Comparative Example 1 was 1.2 × 10¹⁶2.7 × 10¹³Ω · cm, 5.8 × 10¹²Ω · cm, 8.7 × 10¹⁰Ω · cm, 1.5 × 10⁸Ω · cm, 8.5 × 10⁷Intermediate transfer members of Ω · cm were designated as Examples 10 to 14 in that order.
These intermediate transfer members were mounted on an image forming apparatus used for evaluation of transfer dust, and the transfer rate in primary transfer was measured. The transfer rate was calculated by the following equation. Table 5 shows the calculation results. Transfer rate% = (toner adhesion amount per unit area on intermediate transfer drum / toner adhesion amount per unit area on OPC) × 100
The toner adhesion amount was measured by a suction method.
The allowable range of the transfer rate is 90% or more, preferably 95% or more.
[0037]
Volume resistance value calculation
体積 Further, the DC100V / 1 minute volume resistance value of these intermediate transfer members was calculated using the following formula (average value at seven locations). Table 5 shows the calculation results.
Volume resistance R (Ω · cm) = (measured resistance value R ′) × ln {(2πL) / (a / b)}
L: Main electrode width (1 cm)
a: Intermediate transfer member diameter
b: pipe diameter
[Table 5]

[0038]
Surface layer forming component
(4) The relationship between the weight parts of the acicular conductive particles and the volume resistance of the intermediate transfer member was measured.
Needle-shaped conductive particles A (same as in Example 1) 10, 20, 30, 40 based on 100 parts by weight of a polyimide-modified silicone resin (X-22-8904 manufactured by Shin-Etsu Chemical Co., Ltd.), 500 parts by weight of cyclohexanone, and 500 parts by weight of methyl ethyl ketone Each part by weight was added and dispersed in a ball mill for 72 hours. This was spray-coated on an aluminum drum tube to obtain an intermediate transfer member. The thickness of the surface layer is 15 μm.
Next, 1 part by weight of a silane coupling agent (SH6020 manufactured by Toray Silicone Co., Ltd.) was added to 100 parts by weight of the needle-shaped conductive particles A, and the mixture was stirred for 5 minutes with a high-speed mixer. After the attachment, the mixture was taken out of the high-speed mixer and dried at 150 ° C. for 1 hour, and an intermediate transfer member was similarly prepared as the silane-coupled needle-like conductive particles A.
The volume resistance of these intermediate transfer members was measured in the same manner as in Examples 10 to 14. In addition, (log maximum value−log minimum value) was calculated as an index of variation in volume resistance. The results are shown in the graph of FIG.
The variation of the volume resistance is preferably within 1.5 orders, and particularly preferably within 1.2 orders.
[0039]
(Underlayer)
Next, the presence or absence of an abnormal image due to the lower layer was evaluated.
As the rubber layer A, 100 parts by weight of silicone rubber (SH831U manufactured by Toray Silicone Co., Ltd.), 25 parts by weight of carbon black and thermal black (manufactured by Asahi Carbon Co., Ltd.), 2 parts by weight of a vulcanizing agent (C8 manufactured by Shin-Etsu Chemical Co., Ltd.) After kneading the layer components by a predetermined method, a rubber layer was formed on an aluminum tube by a steam vulcanization method. The layer thickness was 2 mm.
As rubber layer B, 100 parts by weight of butyl rubber (Nippon Synthetic Rubber Co., Ltd. Butyl268 (trade name)), 35 parts by weight of carbon black / thermal black (manufactured by Asahi Carbon Co., Ltd.), 5 parts by weight of zinc white, 1 part by weight of stearic acid, vulcanization 7.5 parts by weight of an additive (including sulfur) was molded in the same manner as the rubber layer A. Thicknesses of 2 mm and 0.2 mm were molded.
As rubber layer C, 100 parts by weight of EPDM (JP21 (trade name) made by Nippon Synthetic Rubber), 35 parts by weight of carbon black / thermal black (manufactured by Asahi Carbon Co., Ltd.), 5 parts by weight of zinc white, 1 part by weight of stearic acid, vulcanization 7.5 parts by weight of an additive (including sulfur) was molded in the same manner as the rubber layer A. Thicknesses of 1 mm and 0.2 mm were molded.
As the rubber layer D, 100 parts by weight of nitrile butadiene rubber (N220S (trade name) manufactured by Nippon Synthetic Rubber), 5 parts by weight of zinc white, 1 part by weight of stearic acid, 7.5 parts by weight of a vulcanizing additive (including sulfur) Was molded in the same manner as the rubber layer A. The layer thickness was 2 mm.
As the rubber layer E, 100 parts by weight of epichlorohydrin rubber (Epichromer CG manufactured by Daiso), 5 parts by weight of zinc white, 1 part by weight of stearic acid, 7.5 parts by weight of a vulcanizing additive (including sulfur), It molded similarly. A layer having a thickness of 2 mm was molded.
[0040]
On the molded rubber layers A to E, as a surface layer, 100 parts by weight of a polyimide-modified silicone resin (X-22-8988 manufactured by Shin-Etsu Chemical Co., Ltd.), 500 parts by weight of cyclohexanone, 500 parts by weight of methyl ethyl ketone, surface-treated conductive particles After kneading 30 parts by weight of A by a predetermined method, an intermediate transfer member was formed by spray coating.
The effective hardness, volume resistance (average value of seven places), and maximum value-minimum value (log maximum value-log minimum value) of the volume resistance of the obtained intermediate transfer body were measured.
Further, these intermediate transfer members are mounted on the image forming apparatus shown in FIG. 1, and an image output test is performed using an OHP sheet (ＰOHP film type 2 manufactured by Ricoh Co., Ltd.) to evaluate the presence or absence of a one-dot black line missing image. did. Table 6 shows the results.
[Table 6]

[0041]
(Seamless belt)
A seamless belt of polycarbonate resin (15% by weight of carbon black added) was produced by extrusion molding. The film thickness is 150 μm and the volume resistance is 2.8 × 10¹²Ω · cm. On this seamless belt, as a surface layer, 100 parts by weight of a polyimide-modified silicone resin (化学 X-22-8988 manufactured by Shin-Etsu Chemical Co., Ltd.), 500 parts by weight of cyclohexanone, 500 parts by weight of methyl ethyl ketone, and 30 parts by weight of the surface-treated conductive particles A were prescribed. After kneading by the method, spray coating and curing at 120 ° C. for 3 hours were performed to obtain a belt-shaped intermediate transfer member. This was mounted on the image forming apparatus of FIG. 3, and a continuous paper passing test of 100,000 sheets was performed. As a result, the transfer dust had the same rank A before and after the test, and toner filming did not occur.
[0042]
【The invention's effect】
As described above, at least the surface layer of the intermediate transfer body contains needle-like conductive particles having a major axis length of less than 1 μm, thereby improving the conventional disadvantages and improving the transfer rate and the toner release property of the intermediate transfer device. Is obtained. Further, an improvement in wear resistance, coefficient of friction, transfer rate, resistance variation, and the like is performed, and an image forming apparatus equipped with an intermediate transfer device that maintains these excellent characteristics for a long period of time can be obtained.
[Brief description of the drawings]
FIG. 1 is an example of an intermediate transfer device of the present invention, and is a schematic configuration diagram using a drum-shaped intermediate transfer body.
FIG. 2 is an example of an intermediate transfer device of the present invention, and is a schematic configuration diagram using a belt-shaped intermediate transfer body.
FIG. 3 is a schematic configuration diagram showing a full-color electrophotographic image forming apparatus using a belt-shaped intermediate transfer member.
FIG. 4 is a diagram showing a state of a releasability evaluation test in an example of the present invention.
FIG. 5 is a graph showing a relationship between a weight part of acicular conductive particles and a volume resistance of an intermediate transfer member in Examples of the present invention.
[Explanation of symbols]
11 Intermediate transfer body
12 Intermediate transfer member support roller
13 Intermediate transfer cleaning device
15 transfer material
18 photoconductor
19 mm developing device
20 charging device
21mm exposure equipment
22 ° potential sensor
23 secondary transfer roller
24 static eliminator
25 Photoconductor cleaning device
26 static elimination lamp
27 toner
28 mm paper static eliminator
29 P sensor
A Primary transfer unit
B Secondary transfer unit

Claims (9)

A plurality of visible color developed images sequentially formed on the image carrier by the toner are sequentially superimposed on an intermediate transfer body running endlessly and primary-transferred, and the primary transfer image on the intermediate transfer body is transferred to a transfer material. In the intermediate transfer device that performs the secondary transfer collectively,
The intermediate transfer member has at least a surface layer,
The intermediate transfer device, wherein the surface layer contains acicular conductive particles having a major axis length of less than 1 μm. The intermediate transfer device according to claim 1, wherein the surface layer contains a polyimide-modified silicone resin. The intermediate transfer device according to claim 2, wherein the surface layer has a content of acicular conductive particles of 50 parts by weight or less based on 100 parts by weight of the polyimide-modified silicone resin. 4. The intermediate transfer device according to claim 1, wherein the surface layer has a volume resistivity in a range from 10 ⁸ Ω · cm to 10 ¹² Ω · cm. 5. The intermediate transfer device according to any one of claims 1 to 4, wherein the acicular conductive particles are surface-treated with a silane coupling agent. The intermediate transfer device according to claim 1, wherein the intermediate transfer member is a seamless belt. The intermediate transfer member has at least the surface layer and the lower layer,
The intermediate transfer device according to any one of claims 1 to 6, wherein the lower layer is a rubber substrate having a volume resistivity in a range of 10 ¹² Ω · cm or less and an effective hardness of JISA 95 degrees or less. . The intermediate transfer device according to claim 7, wherein the rubber substrate is a nitrile-butadiene rubber and / or a shrimp chlorohydrin rubber. At least, a charging device, an exposure device, a developing device, an intermediate transfer device, a cleaning device, a static elimination device, and an image forming apparatus including an electrophotographic photosensitive member,
An image forming apparatus, wherein the intermediate transfer device is the intermediate transfer device according to claim 1.

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