JP3671840B2 - Seamless belt, belt for image forming apparatus and image forming apparatus - Google Patents

Description

【００７８】
一方、化２の如くＰＣのＢＰＡと結合したＰＢＴのＴＰＡ中のベンゼン環水素は、化学シフトが変化し、水素（ｂ）は８．２５にダブレット，（ｃ）は８．１３にダブレットピークを示す。
【００７９】
【化２】

【００８０】
（ｄ）：｛（ｂ）＋（ｃ）｝の面積比により、ＰＢＴ分子中のＴＰＡと、ＰＣと結合しているＴＰＡの比を求めることができる。
【００８１】
本例では面積比は（ｄ）：｛（ｂ）＋（ｃ）｝＝１００：｛０．４６５４＋０．５６３５｝≒９９．０１：０．９９となるので、ＰＢＴ構成単位１００ｍｏｌあたり、０．９９ｍｏｌのＴＰＡ（ＰＢＴ由来）−ＢＰＡ（ＰＣ由来）結合を有していることが解る。また、本樹脂組成物中には同量のブタンジオール（ＰＢＴ由来）−炭素（ＰＣ）結合が存在することが容易に推測できるので、合計でＰＢＴ構成単位１００ｍｏｌあたり１．９８ｍｏｌのＰＢＴ−ＰＣ結合が存在することが解る。
【００８２】
化３の通り、ＰＢＴ構成単位（ブタンジオール＋ＴＰＡ）の式量は２２０なので、ＰＢＴ２２０００（２２０×１００ｍｏｌ）ｇあたり、１．９８ｍｏｌのＰＢＴ−ＰＣ結合が存在する。
【００８３】
ＰＢＴ−ＰＣ結合１ｍｏｌあたりのＰＢＴの質量は約１１０００（２２０００／１．９８）と計算できる。
【００８４】
本例ではＰＢＴとＰＣの重量比が７／３なので、ＰＢＴ−ＰＣ結合１ｍｏｌあたりの樹脂分（ＰＢＴ質量＋ＰＣ質量）は１６０００ｇ（１１０００／０．７）と求めることができる。
【００８５】
【化３】

【００８６】
（分子量）
本発明においては、結晶性樹脂、非晶性樹脂、重合触媒、キレーター及び導電性物質を加熱混練し、結晶性樹脂の分子鎖と、非晶性樹脂の分子鎖間に化学結合を生成し、且つ、樹脂組成物としての総合の分子量を維持あるいは増加させることで、得られるシームレスベルトの物性向上が図れると考えられるので、分子量は高い方が好ましい。
【００８７】
分子量の測定方法であるが、本発明のように共重合体が存在する場合には分子量の真値を求めることが難しい。
【００８８】
そこで本発明では全ての樹脂をＧＰＣにより同一条件で測定し、ＰＳ換算重量平均分子量として得た値を共通の代表値として用いることとした。
【００８９】
測定条件としては、試料２０ｍｇを０．５ｍｌの１，１，１，３，３，３−ヘキサフルオロ−２−プロパノールと０．２ｍｌのクロロホルムで一晩溶解し、更に移動相の溶媒２５ｍｌを加え、０．２２μｍのフィルターにて濾過し、ＳＥＣ測定溶液とした。移動相を加えてから測定終了まで１２時間以内に行った。
【００９０】
ＳＥＣ測定条件
溶媒 クロロホルム／酢酸：９９．５：０．５（ｖｏｌ／ｖｏｌ）
流速 １．０ｍｌ／分
注入量 ０．０２ｍｌ
カラム ＡＤ８０６Ｍ／Ｓ ２本（昭和電工社製）
カラム温度 ３０℃
検出器 ＵＶ ２５４ｎｍ
【００９１】
分子量５００（Ａ−５００）から２，８９０，０００（Ｆ−２８８）までの分子量の異なる単分散標準ポリスチレン（東ソー社製）１２試料用い、較正曲線を作成し、ポリスチレン換算の分子量を計算した。
【００９２】
本手法でした、結晶性樹脂と、非晶性樹脂と、重合触媒、キレーター及び導電性物質を加熱混練した後に得られる樹脂組成物のＰＳ換算重量平均分子量（Ｍｗ_３とする）の値としては、具体的には、結晶性樹脂の配合比率をＸ重量部，ポリスチレン（ＰＳ）換算重量平均分子量をＭｗ_１、非晶性樹脂の配合比率をＹ重量部，ＰＳ換算重量平均分子量をＭｗ_２として、
【数２】

であることが好ましく、
【数３】

であるとさらに好ましく、
【数４】

であると、十分に高い物性を得られるので特に好ましい。
【００９３】
また、本発明においてはＭｗ_３が加熱混合によりＭｗ_１とＭｗ_２の算術平均値よりも高くなっていることが重要で、初めから高いＭｗ_１やＭｗ_２の樹脂を用いても、加熱混合時に分子量低下していては最終的なＭｗ_３が高くても良好な物性は期待できないと考えられるので、Ｍｗ_３の絶対値に特に制限はないが、それでも総合的観点からは高い方が好ましく、具体的にはＰＳ換算重量平均分子量で１３０，０００以上が好ましく、１４０，０００以上であるとさらに好ましく、１５０，０００以上であると特に好ましい。
【００９４】
なお、重量平均分子量真値とＰＳ換算重量平均分子量の相関の例を挙げると、重量平均分子量４０，０００のＰＢＴを上記手法で測定するとＰＳ換算重量平均分子量１２２，０００の値が得られ、重量平均分子量２８，０００のＰＣを上記手法で測定するとＰＳ換算重量平均分子量６４，０００の値が得られることがわかっている。
【００９５】
（分散形態）
一般に２種類の熱可塑性樹脂を溶融混合しても完全には混じり合わず、流動構造をとることが知られている。両熱可塑性樹脂の体積分率に大きな差がある場合は体積分率の大きい方が海で体積分率が小さい方が島の構造をとりやすく、体積分率の差が小さい場合は溶融粘度差が海島構造に影響をあたえ、溶融粘度の小さい方が海に、大きい方が島になりやすいと言われている。
【００９６】
一般的な溶融混合では分散粒径が１００ｎｍ程度にまでしかならないが、本発明においては条件を適正化することにより分散粒径を数ｎｍ以下にまで微細化することが可能で、これにより事実上シームレスベルトを透明化することができる。
【００９７】
一般にＰＢＴなどの結晶性樹脂を含むシームレスベルトは透明性を有さないことで知られるが、本発明による手法を用いれば、驚くべきことに透明なシームレスベルトを得ることもできるのである。
【００９８】
分散状態の確認手法に特に制限はなく、ＲｕＯ_４で染色後、超薄切片を作成しＴＥＭで観察するなど公知の方法を用いることができる。
【００９９】
なかでも寸法精度，耐屈曲性，引張破断伸など要求物性の厳しいＯＡ機器分野、特に機能部材には好適に用いることができ、例えばシームレスベルト形状として、割れ，伸びなど不具合が少ないので好適である。
【０１００】
（シームレスベルト）
本発明のシームレスベルトは、電子写真式複写機、レーザービームプリンター、ファクシミリ機等の画像形成装置に中間転写ベルト，搬送転写ベルト，感光体ベルトなどとして用いられる。
【０１０１】
シームレスベルトを得るには、結晶性樹脂、非晶性樹脂、重合触媒を例えば二軸混練押出機により混合し、ペレット化した後にシームレスベルトとなるように成形する手法が特に好ましく用いられる。
【０１０２】
成形方法については、特に限定されるものではなく、連続溶融押出成形法、射出成形法、ブロー成形法、あるいはインフレーション成形法など公知の方法を採用して得ることができるが、特に望ましいのは、連続溶融押出成形法である。特に押し出したチューブの内径を高精度で制御可能な下方押出方式の内部冷却マンドレル方式あるいはバキュームサイジング方式が好ましく、内部冷却マンドレル方式が最も好ましい。
【０１０３】
また、この成形時の温度，滞留時間適正化により、より良好な物性のシームレスベルトを得ることができるので各配合にあわせて条件を調整することが好ましい。
【０１０４】
（シームレスベルトの物性）
本発明によれば、以下のような物性を有するシームレスベルトを得ることができる。
・物性；耐折回数
本発明に用いるシームレスベルトを例えば中間転写ベルトとして画像形成装置に用いる場合には、耐屈曲性が悪いとクラックが発生して画像が得られなくなるので耐屈曲性の良好なシームレスベルトが好ましい。
【０１０５】
耐屈曲性の程度は、ＪＩＳ Ｐ−８１１５の耐折回数の測定方法に従うことで定量的に評価でき、耐折回数の大きいシームレスベルトほどクラックが入りにくく、耐屈曲性に優れていると判断することができる。
【０１０６】
具体的な数値としては、５００回以上あれば一応シームレスベルトとして機能を発揮して使用することができるが、実用的には５０００回以上が好ましく、１００００回以上であれば更に好ましく、３００００回以上であれば、特にクラックが発生しにくくなるので特に好ましい。
【０１０７】
・引張弾性率
シームレスベルトの引張弾性率が低いと、例えば中間転写ベルトとして画像形成装置に用いる場合に張力により少し伸びが発生してしまい、色ズレなど不具合を発生することがあるので引張弾性率が高い方が好ましく、具体的には１０００ＭＰａ以上が好ましく、１５００ＭＰａ以上だとさらに好ましく、２０００ＭＰａ以上だとさらに好ましく、２５００ＭＰａ以上であれば色ズレなどの不具合を大幅に抑えることができるので特に好ましい。
【０１０８】
一般に柔らかいプラスチックは耐折回数が高いが引張弾性率が低くなりやすく、逆に硬いプラスチックは高い引張弾性率を得られるが脆くなりやすく耐折回数は低いものしか得られないことが多い。本発明ではＰＢＴやＰＣの有する固有の高い引張弾性率の特性を維持したまま、高い耐折回数を得ることができる意味で有用であると言える。
【０１０９】
・物性；表面抵抗率
本発明に用いるシームレスベルトは導電性フィラーあるいは導電性を発現する物質を配合することにより導電性を得ることができる。
【０１１０】
抵抗領域は目的により異なるが、表面抵抗率１〜１×１０^１６Ωの範囲から選定することが好ましい。
【０１１１】
更に好ましい範囲は用途により異なるが、例えば感光体ベルトとして用いる場合には必要に応じて外表面の電荷を内表面に逃がせるように１〜１×１０^９Ωと低い表面抵抗率が好ましく、中間転写ベルトとして用いる場合には帯電−転写の容易にできる１×１０^６〜１×１０^１３Ωが好ましく、搬送転写ベルトとして用いる場合には帯電しやすく高電圧でも破損しにくい１×１０^１０〜１×１０^１６Ωと高い領域が好ましい。
【０１１２】
また、シームレスベルト１本中の表面抵抗率の分布は狭い方が好ましく、それぞれの好ましい表面抵抗率領域において、１本中の最大値と最小値の差が２桁以内であること（最大値が最小値の１００倍以内であること）が好ましい。
【０１１３】
フィルムの表面抵抗率は例えばダイヤインスツルメント（株）製ハイレスタ，ロレスタやアドバンテスト（株）製Ｒ８３４０Ａなどにより容易に測定することができる。
【０１１４】
・シームレスベルトの厚み
シームレスベルトの厚みは５０〜１０００μｍが好ましく、８０〜５００μｍが更に好ましく、１００〜２００μｍであれば特に好ましい。
【０１１５】
・シームレスベルトの用途
シームレスベルトはそのままベルトとして使用しても良いし、ドラムあるいはロール等に巻き付けて使用しても良い。
【０１１６】
更に蛇行防止や端面補強等の目的のために、所定の寸法のシームレスベルトの内側及び／又は外側端部近傍に耐熱テープを貼り付けたり、或いはウレタンゴムやシリコンゴム等のテープをベルト内側の端部近傍に貼り合わせても良い。
【０１１７】
【実施例】
本発明を実施例、比較例を用いて、より具体的に説明する。
【０１１８】
（原料）
原料は下記のものを用い、配合割合は表１又は表２の通りとした。
ＰＢＴ；重量平均分子量４０，０００；ＰＳ換算重量平均分子量１２２，０００
ＰＣ ；重量平均分子量２８，０００；ＰＳ換算重量平均分子量 ６４，０００
重合触媒；チタニウム(IV)ブトキシド
酢酸マグネシウム
キレーター；リン酸化酸化防止剤ＰＥＰＱ クラリアントジャパン（株）社製
カーボンブラック；デンカブラック；電気化学（株）製
【０１１９】
（加熱混練）
各原料を、二軸混練押出機（ＩＫＧ（株）製 ＰＭＴ３２）を用いて材料ペレット化した。
【０１２０】
（シームレスベルトの成形方法）
この材料ペレットを乾燥し、直径φ１８０ｍｍ、リップ幅１ｍｍの６条スパイラル型環状ダイ付き４０ｍｍφの押出機により、環状ダイ下方に溶融チューブ状態で押し出し、押し出した溶融チューブを、環状ダイと同一軸線上に支持棒を介して装着した外径１７０ｍｍの冷却マンドレルの外表面に接しめて冷却固化させつつ、次に、シームレスベルトの中に設置されている中子と外側に設置されているロールにより、シームレスベルトを円筒形に保持した状態で引き取りつつ３４０ｍｍ長の長さで輪切りにして所定の厚み、各表記載の滞留時間となるよう押出量、引き取り速度を調整し、直径１６９ｍｍの樹脂製シームレスベルトとした。なお、厚みは１４０μｍを目標とし、±１４μｍを許容範囲とした。
【０１２１】
成形温度，滞留時間などの条件は各表１又は２の通りとした。
【０１２２】
（評価）
評価は必要に応じ、シームレスベルトを必要な大きさに切り開いて実施した。
・厚み
東京精密（株）製のマイクロメーターを用いてシームレスベルトの円周方向２０ｍｍピッチで測定
・耐折回数
ＪＩＳ Ｐ−８１１５準拠
・表面抵抗率 Ω
表面抵抗率は測定器により好適に測定できる領域が異なるので以下のように使い分けた。
１〜１×１０^６Ωとなるサンプル ダイヤインスツルメント（株）製 ロレスタを使用し、２０ｍｍピッチでベルト円周方向を測定した。
１０^６〜１×１０^１３Ωとなるサンプル ダイヤインスツルメント（株）製 ハイレスタ（ＨＡ端子）を使用し、５００Ｖ、１０秒の条件にて２０ｍｍピッチでベルト円周方向を測定した。
１０^１３〜１×１０^１６Ωとなるサンプル アドバンテスト（株） 微小電流測定器Ｒ８３４０Ａ（ＪＩＳ電極）を使用し、５００Ｖ、１０秒の条件にて１００ｍｍピッチにてベルト円周方向を測定した。
測定時間 １０秒値
【０１２３】
・シームレスベルトとしての耐久性の評価
得られたシームレスベルトを中間転写ベルト、搬送転写ベルト、あるいは感光体ベルトとして画像形成装置に搭載し、連続で画像出力をし、何枚出力した段階でシームレスベルトにクラックが発生するかを評価した。
【０１２４】
・引張り弾性率
ＩＳＯ Ｒ１１８４−１９７０に準拠し、試験片を幅１５ｍｍ、長さ１５０ｍｍに切断し、引張り速度１ｍｍ／ｍｉｎ、つかみ具間距離を１００ｍｍとした。
【０１２５】
・引張り破断伸び率
ＪＩＳＺ１７０２−６２に準拠し、試験片を幅１５ｍｍ、長さ１５０ｍｍに切断し、引張り速度５０ｍｍ／ｍｉｎ、つかみ具間距離を１００ｍｍ、標線間隔を５０ｍｍとした。
【０１２６】
〔実施例１〕
ＰＢＴ，ＰＣ，テトラブチルチタネート，酢酸マグネシウム，キレーターを事前に１３０℃程度で予備乾燥し、その後に加熱混練し、材料ペレットを得た。
【０１２７】
このときの加熱混練条件は、樹脂温度と混練機内での滞留時間を調節し、混練機内での反応は抑制するようにした。
【０１２８】
この材料ペレットを押出成形し、透明なフィルムを得ることができた。
【０１２９】
なお、この押出成形機内で反応が好ましい程度に促進し、透明なシームレスベルトが得られるように、押出成形条件は、樹脂温度と滞留時間を調節した。
【０１３０】
表１にフィルムの形態、特性、外観を示す。
【０１３１】
更に、得られたシームレスベルトを８０℃で１０分間熱処理したところ引張り弾性率が５％向上した。
【０１３２】
〔比較例１〕
重合触媒を削除した以外は実施例１と同じ条件で得たシームレスベルト。
【０１３３】
ＰＢＴは不純物としての樹脂中の金属分の影響を除去するために一度溶剤に溶解してカラムを用いて濾過し、しかる後に溶剤を除去したものを用いた。
【０１３４】
実施例１と異なり、押出成形条件（成形温度，滞留時間）をいくら調整しても透明なシームレスベルトは得られなかった。
【０１３５】
表１にフィルムの形態、特性、外観を示す。
【０１３６】
【表１】

【０１３７】
〔実施例２〕
ＰＢＴ，ＰＣ，テトラブチルチタネート，酢酸マグネシウム，キレーター，カーボンブラックを事前に予備乾燥し、その後に加熱混練し、材料ペレットを得た。
【０１３８】
その後、この材料ペレットを押出成形機にてシームレスベルトに成形した。
【０１３９】
表２の通り、得られた成形品は耐折回数が５８，０００回と著しく高く引張弾性率も高く良好な物性であった。
【０１４０】
表面抵抗率は平均値で１×１０^１０Ωで体積抵抗率は平均値で１×１０^１０Ω・ｃｍであり中間転写ベルトとして画像形成装置に搭載したところ良好に画像を得ることができた。また、この状態で１０万枚画像出力してもクラックが発生することは無かった。
【０１４１】
本実施例では成形時の加熱混練で、適切な滞留時間と成形温度を設定することで、良好な物性の成形品を得ることができたと考えられる。
【０１４２】
更に、得られたシームレスベルトを８０℃で２０分間熱処理したところ引張り弾性率が８％向上した。
【０１４３】
〔実施例３〕
ＰＢＴとＰＣの重量比を変えた点、成形時に滞留時間を長くした点以外は実施例１と同じ条件でシームレスベルトを得た。この実施例３によっても、表２の通り実施例１同様良好な物性を得た。
【０１４４】
滞留時間を長くしたのは、ＰＢＴ／ＰＣ比率を変えたことで系の適切な反応条件のポイントが変化したためと考えられる。
【０１４５】
更に、得られたシームレスベルトを８０℃で１０分間熱処理したところ引張り弾性率が７％向上した。
【０１４６】
〔実施例４〕
カーボン濃度を低くして表面抵抗率の高い、シームレスベルトを得た。表２の通り、本実施例４でも均一分散状態を得、物性が良好であった。このシームレスベルトを搬送転写ベルトとして画像形成装置に搭載したところ、良好な画像を得ることができた。
【０１４７】
更に、得られたシームレスベルトを８０℃で１０分間熱処理したところ引張り弾性率が５％向上した。
【０１４８】
〔実施例５〕
カーボン濃度を高くして表面抵抗率の低いシームレスベルトを得た。表２の通り、本実施例５でも均一分散状態を得、物性が良好であった。このシームレスベルトを感光体ベルトとして用い、その表面に感光層を設けて画像形成装置に搭載したところ、良好な画像を得ることができた。
【０１４９】
更に、得られたシームレスベルトを８０℃で１０分間熱処理したところ引張り弾性率が５％向上した。
【０１５０】
〔比較例２〕
重合触媒を削除した以外は実施例２と同じ条件でシームレスベルトを製造した。
【０１５１】
ＰＢＴは不純物としての樹脂中の金属分の影響を除去するために一度溶剤に溶解してカラムを用いて濾過し、しかる後に溶剤を除去したものを用いた。
【０１５２】
引張弾性率は実施例１とほぼ同等であったが、耐折回数が低かった。また形態観察したところ、ＰＣが島となる２相分離構造をとっていることが分かった。中間転写ベルトとして画像形成装置に搭載したところ良好に画像を得ることができたが、この状態で画像出力を続けたところ、８０００枚出力した時点でクラックが発生した。
【０１５３】
【表２】

【０１５４】
【発明の効果】
以上の実施例及び比較例からも明らかな通り、本発明によると、耐屈曲性や耐薬品性及び成形寸法安定性に優れ、溶融混合時の反応による物性劣化を抑えたシームレスベルトと、このシームレスベルトを用いた画像形成装置用ベルトと、この画像形成装置用ベルトを用いた画像形成装置が提供される。
【図面の簡単な説明】
【図１】 ＰＢＴとＰＣとの混合反応物のＮＭＲチャートである。
【図２】 図１のII部分の拡大図である。
【図３】 従来の中間転写装置の側面図である。
【符号の説明】
１ 感光ドラム
２ 帯電器
３ 露光光学系
４ 現像器
５ クリーナー
６ 導電性シームレスベルト
７，８，９ 搬送ローラ[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to a seamless belt excellent in physical properties such as molding dimensional stability and bending resistance, and an intermediate transfer belt used in an electrophotographic copying machine, a laser beam printer, a facsimile machine, and the like using the seamless belt, The present invention relates to an image forming apparatus belt such as a transfer belt and a photosensitive belt, and an image forming apparatus including the image forming apparatus belt.
[0002]
[Prior art]
  Conventionally, seamless belts (endless belts) have been frequently used in intermediate transfer devices, transfer separation devices, charging devices and the like such as electrophotographic copying machines. FIG. 3 is a side view of a conventional intermediate transfer apparatus. In the figure, 1 is a photosensitive drum, and 6 is a conductive seamless belt. 1 is an electrophotographic process unit including a charging device 2, an exposure optical system 3 using a semiconductor laser as a light source, a developing device 4 containing toner, and a cleaner 5 for removing residual toner. Is arranged. The conductive seamless belt 6 is wound around the transport rollers 7, 8, and 9 and moves in the direction of the arrow in synchronization with the photosensitive drum rotating in the direction of the arrow.
[0003]
  Next, the operation will be described. First, the surface of the photosensitive drum 1 rotating in the direction of arrow A is uniformly charged by the charger 2. Next, an electrostatic latent image corresponding to an image obtained by an image reading device (not shown) is formed on the photosensitive drum 1 by the optical system 3. The electrostatic latent image is developed into a toner image by the developing device 4. This toner image is electrostatically transferred to the conductive seamless belt 6 by the electrostatic transfer machine 10 and transferred to the recording paper 11 between the conveying roller 9 and the pressing roller 12.
[0004]
  By the way, in the case of a conductive seamless belt such as an electrophotographic copying machine, sufficient durability is required because it is driven with high tension for a long time by two or more rolls. Further, when used in an intermediate transfer device or the like, an image is formed with toner on a belt and transferred to paper, and if the belt is loosened or stretched during driving, image misalignment may occur. Further, since toner is transferred electrostatically, a certain degree of conductivity is also required.
[0005]
  Such a seamless belt is an important part that determines a toner image, and is considered to be one of the three important parts together with the photoreceptor and toner.
[0006]
  Therefore, the intermediate transfer belt(1)~(7)Is required.
(1)  Having a predetermined surface resistivity and volume resistivity in the semiconductor region.
(2)  Toner releasability.
(3)  The thickness is thin and uniform.
(Four)  Strong mechanical strength (hard to break).
(Five)  Less variation in resistance due to the environment (temperature and humidity).
(6)  Low cost.
(7)  The belt must be seamless and round.
[0007]
  In addition, the following methods are considered as a manufacturing method of a seamless belt.
  (i) Rotational molding method (or sometimes expressed as centrifugal molding method)
  Put the resin in which the solution is dissolved on the inner peripheral surface of the cylindrical mold, apply temperature while rotating the mold, volatilize the solvent by half or more, and then remove the seamless tube from the mold. And a step of attaching a seamless tube to the outside of the cylindrical mold and applying a temperature to cause a thermosetting reaction (JP-A-60-170862).
  (ii) Extrusion method
  In this method, a resin compounded with a conductive filler is melt-extruded in a ring shape.
  (iii) Dipping method
  In this method, the resin solution is applied to the outer surface of a cylindrical or columnar mold by dipping or the like to form a fixed thickness, and after heating to form a film, the tubular film formed from the mold is pulled out.
[0008]
  Conventionally, as such a conductive seamless belt, one formed by blending a thermosetting resin or a thermoplastic resin with a conductive filler such as carbon black has been used. Among them, those mainly composed of a thermoplastic resin are easy to continuously form and have been widely used. Among the thermoplastic resins, the thermoplastic amorphous resin is more excellent in dimensional accuracy than the thermoplastic crystalline resin. As such a thermoplastic amorphous resin seamless belt, for example, a conductive carbon black is blended with a thermoplastic resin such as a polycarbonate resin, and is extruded into a cylindrical film using a cylindrical die. Is known (Japanese Patent Laid-Open No. 3-89357, etc.).
[0009]
  However, the thermoplastic resin amorphous resin has better dimensional accuracy than the thermoplastic crystalline resin, but is inferior in bending resistance. For example, when used in electrophotography as an intermediate transfer belt, cracks occur during use. Cheap.
[0010]
  In order to solve this problem, a seamless belt formed by blending polycarbonate and polyalkylene terephthalate such as polybutylene terephthalate has been proposed (Japanese Patent Laid-Open Nos. 4-313757 and 6-149083).
[0011]
  However, a seamless belt formed by blending polycarbonate (hereinafter sometimes referred to as PC) and polyalkylene terephthalate (hereinafter sometimes referred to as PAT) such as polybutylene terephthalate (hereinafter sometimes referred to as PBT). Although the bending resistance is improved as compared with the above-described seamless belt made of polycarbonate, the effect of the improvement is still insufficient. Moreover, since polyalkylene terephthalate resin has high crystallinity, if the compounding quantity is increased, the dimensional accuracy of a seamless belt will become low.
[0012]
  As a general knowledge, thermoplastic resins can be broadly classified into crystalline thermoplastic resins and amorphous thermoplastic resins. Crystalline thermoplastic resins are excellent in bending resistance and chemical resistance, but have high molding shrinkage. Therefore, dimensional stability is poor and it does not have transparency, and on the contrary, amorphous thermoplastic resin has excellent dimensional stability and transparency, but has problems such as poor bending resistance and poor chemical resistance. It has been said that
[0013]
  However, in many cases, it is required to have excellent bending resistance, chemical resistance, and molding dimensional stability.
[0014]
  In order to satisfy these requirements, various studies have been made on improving physical properties by alloying a crystalline thermoplastic resin and an amorphous thermoplastic resin, and certain results have been achieved.
[0015]
  In these studies, for example, in the field of thermoplastic ester resins, it has been reported that crystalline ester resins and amorphous ester resins can be finely dispersed by promoting transesterification (copolymerization). . However, in the conventional technology, when transesterification (copolymerization) is promoted, the generation of low molecular weight by depolymerization is accompanied by foaming of the seamless belt, or the chain chain breakage proceeds and the mechanical properties of the seamless belt are lowered. It has not practically been put to practical use for reasons such as a reduction (such as a decrease in tensile elongation at break).
[0016]
  Actually, resin products that prevent deterioration of physical properties by suppressing the transesterification reaction have been used as practical products.
[0017]
[Problems to be solved by the invention]
  In an image forming apparatus such as an OA apparatus, electrical characteristics are very important in addition to mechanical characteristics such as price, bending resistance, and Young's modulus, and the electrical resistance value must be uniformly controlled within a certain range. For that purpose, various conductive fillers such as carbon black and metal oxides have been studied. However, if the conductive filler is mixed with the resin, there is a lack of affinity with the resin, and bending resistance is increasing. There was a problem that the mechanical properties of the machine deteriorated.
[0018]
  Thus, the present situation is that the seamless belt which satisfies the mechanical property represented by price, bending resistance, Young's modulus, etc., and the electrical property represented by electrical resistance has not yet been found.
[0019]
  An object of the present invention is to provide a seamless belt, a belt for an image forming apparatus, and an image forming apparatus that are excellent in bending resistance, chemical resistance, and molding dimensional stability, and suppress deterioration of physical properties due to a reaction during melt mixing. .
[0020]
[Means for Solving the Problems]
  The seamless belt of the present invention includes a crystalline resin having at least one of a hydroxyl group, a carboxylic acid and an ester bond, and an amorphous resin having at least one of a hydroxyl group, a carboxylic acid and an ester bond.,Polymerization catalyst, Chelators and conductive materialsIs heated and mixed and molded.A seamless belt, wherein the crystalline resin is selected from PBT (polybutylene terephthalate), PET (polyethylene terephthalate), and PEN (polyethylene naphthalate), and the amorphous resin is PC (polycarbonate), PAr ( Polyarylate) and PMMA (polymethylmethacrylate), and the blending amount of the polymerization catalyst is 50 to 500 ppm based on the mass of the metal in the polymerization catalyst, and the blending amount of the chelator is 100 parts by weight of the resin. 0.1 to 3 parts by weight with respect to the conductive material content of 3 to 30% by weightIt is characterized by this.
[0021]
  As a result of intensive investigations for the above purpose, the present inventors have found that a crystalline resin having at least one of a hydroxyl group, a carboxylic acid and an ester bond and an amorphous material having at least one of a hydroxyl group, a carboxylic acid and an ester bond. Resin and polymerization catalystAnd chelator and conductive materialThe seamless belt obtained by heating and kneading was found to be superior to the seamless belt obtained by the method for suppressing the reaction such as the transesterification reaction, and to have excellent physical properties such as bending resistance and transparency depending on the conditions. Reached.
[0022]
  The belt for an image forming apparatus of the present invention is an intermediate transfer belt, a conveyance transfer belt, or a photoreceptor belt made of this seamless belt.
[0023]
  The image forming apparatus of the present invention comprises this image forming apparatus belt.
[0024]
DETAILED DESCRIPTION OF THE INVENTION
  The present invention will be described in detail below.
[0025]
  (Crystalline resin having at least one of hydroxyl group, carboxylic acid and ester bond)
  The crystalline resin used for the seamless belt of the present invention has at least one of a hydroxyl group, a carboxylic acid and an ester bond, and has a crystallinity of 10% or more and 100% or less.Below, PBT (polybutylene terephthalate), PET (polyethylene terephthalate), PEN (polyethylene naphthalate)Is used.PBT is particularly preferable because it has a high crystal acceleration and therefore has little change in crystallinity due to molding conditions and is generally stable at a crystallinity of about 30%.
[0026]
  Moreover, a copolymerization component can also be introduce | transduced in the crystalline resin used for this invention in the range which does not impair the effect of this invention remarkably. Specific examples include those in which an ester bond is the main chain and an ester bond such as polymethylene glycol is introduced.
[0027]
  There is no particular limitation on the molecular weight of the crystalline resin used in the seamless belt of the present invention. For example, a resin having a general molecular weight such as a weight average molecular weight of 10,000 to 100,000 can be used. When there is a high demand, a high molecular weight is preferable. Specifically, it is preferably 20,000 or more, more preferably 25,000 or more, and particularly preferably 30,000 or more.
[0028]
  (Amorphous resin having at least one of hydroxyl group, carboxylic acid and ester bond)
  The amorphous resin used in the seamless belt of the present invention has at least one of a hydroxyl group, a carboxylic acid and an ester bond, and has a crystallinity of 0% or more and 10% or less.Full of PC (polycarbonate) and PAr (polyarylate)) AndPMMA (Polymethylmethacrylate)Is used.inAlso,PC can be used particularly preferably.
[0029]
  In addition, a copolymer component can be introduced into the amorphous resin used in the seamless belt of the present invention as long as the effects of the present invention are not significantly impaired. Specific examples include those in which an ester bond is the main chain and an ester bond such as polymethylene glycol is introduced.
[0030]
  The molecular weight of the amorphous resin used in the seamless belt of the present invention is not particularly limited. For example, a resin having a general molecular weight such as a weight average molecular weight of 10,000 to 100,000 can be used. When there is a demand for high physical properties, those having a high molecular weight are preferred. Specifically, it is preferably 20,000 or more, more preferably 25,000 or more, and particularly preferably 30,000 or more.
[0031]
  (Weight ratio of crystalline resin to amorphous resin)
  There is no restriction | limiting in particular in the weight ratio of the crystalline resin used for the seamless belt of this invention, and an amorphous resin. However, in general, a crystalline resin is excellent in chemical resistance and flex resistance, and an amorphous resin is excellent in molding dimensional stability. Therefore, any ratio can be set according to the purpose of use. 1/99 to 99/1 is preferable, 40/60 to 97/3 is more preferable, 60/40 to 95/5 is further preferable, and 70/30 to 90/10 is preferable. Is particularly preferred.
[0032]
  The reason why the ratio of the crystalline resin is selected as a particularly preferable ratio is that the amorphous resin can be expected to sufficiently improve the molding dimensional stability with a small amount of blending, and the amorphous resin is slightly blended excessively. This is due to the fact that the effects of chemical resistance such as solvents during painting may be noticeable.
[0033]
  (Difference in viscosity between crystalline resin and amorphous resin)
  If the viscosity difference between the two resins is too large, good dispersion may not be obtained even if the production conditions are adjusted, and uniform dispersion may not be achieved. Therefore, it is preferable that the viscosity difference is small.
[0034]
  Specifically, MFR measurement is performed on both resins under the same conditions, and the value is preferably within a range of about 1/20 to 20/1, and more preferably within a range of 1/10 to 10/1.
[0035]
  The measurement method is based on JIS K-7210, and it is preferable to select a measurement temperature condition close to the processing temperature of the resin.
[0036]
  For example, when PBT and PC are selected, it is preferable to set a processing temperature of 260 ° C. as the measurement temperature and compare the viscosity difference between the two resins. Moreover, it can measure suitably by selecting 2.16 kg, for example as a load.
[0037]
  (Polymerization catalyst)
  The polymerization catalyst is not particularly limited as long as it has an ability to polymerize a crystalline resin and an amorphous resin.
[0038]
  There is no particular limitation as long as it has an ability to condense an organic acid and a hydroxyl group, and a polyester polymerization catalyst can be used.
[0039]
  Of the polymerization catalysts, Ti-based polymerization catalysts are preferred, and alkyl titanates can be suitably used.
[0040]
  Among the alkyl titanates, tetrabutyl titanate or tetrakis (2-ethylhexyl) orthotitanate is preferable, and these are easily available as TYZOR TOT (manufactured by DuPont) or TYZOR TBT (manufactured by DuPont).
[0041]
  In addition, the Ti-based polymerization catalyst is preferably combined with an alkali metal, alkaline earth metal-containing compound or zinc-containing compound because it works more effectively, and it is particularly preferable to have an Mg-containing compound as the polymerization catalyst.
[0042]
  Although there is no restriction | limiting in particular as a compound containing Mg, Organic acid Mg salt is especially preferable, and Mg acetate is especially preferable.
[0043]
  As the content of the polymerization catalyst, if it is too small, it may not work effectively, so it is preferable that the content is high to some extent.50ppm or moreAndOn the other hand, ester resins are known to cause depolymerization in the presence of a large amount of heavy metals.500ppm or lessAnd
[0044]
  (Chelator)
  In the present invention, if the activity of the polymerization catalyst is too high, the depolymerization of the resin is promoted and mechanical properties are reduced due to a decrease in molecular weight, and foaming associated with the generation of a low molecular weight product may cause problems.
[0045]
  In the present invention, there exists a chelator having the ability to chelate the metal in the polymerization catalyst.For, Depolymerization can be suppressed.
[0046]
  There is no restriction | limiting in particular as a kind of chelator, A well-known chelator can be used.
[0047]
  Examples include phosphites, phosphates, phosphates and hydrazines, such as Irgafos 168 (manufactured by Ciba Geigy Japan), PEP36 (manufactured by Asahi Denka Kogyo Co., Ltd.). PEPQ (manufactured by Clariant Japan Co., Ltd.), IRGANOX MD1024 (manufactured by Nippon Ciba Geigy Co., Ltd.), CDA-6 (manufactured by Asahi Denka Kogyo Co., Ltd.), and hydrazines are easily obtained from the market. be able to.
[0048]
  KiIf the amount of the accelerator is too large, the polymerization catalyst may lose its activity and a seamless belt with good physical properties may not be obtained, so it is preferable not to add too much.Yes.
[0049]
  BookinventionThenAdd a large amount of polymerization catalyst as 50-500ppm, chelatorFor 100 parts by weight of resinWhen the molding conditions (temperature, residence time, etc.) for obtaining a seamless belt are further optimized by using 0.1 to 3 parts by weight, preferably 0.3 to 1 part by weight and higher than common sense, a crystalline resin In addition, the formation of chemical bonds and an increase in molecular weight of the amorphous resin can be promoted while depolymerization can be suppressed, and a seamless belt having excellent physical properties that has never been obtained can be obtained.
[0050]
  (Conductive substance)
  In the present inventionContains conductive materialAdjust electrical resistanceTheIn particular, in a seamless belt or the like used in an image forming apparatus, it is necessary to adjust the surface resistance value and the volume resistance value according to the application in order to electrically adsorb and transfer toner or paper.
[0051]
  The conductive material to be blended is not particularly limited as long as it satisfies the performance required for the application, and various materials can be used. Specifically, as the conductive filler, carbon black or carbon fiber can be used. Carbon-based fillers such as graphite, metal-based conductive fillers, metal oxide-based conductive fillers, and the like are used. In addition to the conductive fillers, ion conductive substances such as quaternary ammonium salts are exemplified.
[0052]
  A particularly preferable conductive material is carbon black having excellent dispersibility.
[0053]
  As the type of carbon black, acetylene black, furnace black, channel black and the like can be suitably used, and among these, acetylene black which has few functional groups as impurities and hardly causes poor appearance due to carbon aggregation can be particularly suitably used. Furthermore, the primary particle diameter is 10 to 100 nm, the specific surface area is 10 to 200 m.²/ G, those having a pH value of 3 to 11 are more preferred.
[0054]
  Moreover, the carbon black to be used may be one type or two types. Furthermore, there is no problem even if carbon black subjected to a known post-treatment process such as carbon black coated with resin, carbon black subjected to graphitization, or carbon black subjected to acid treatment is used as the carbon black.
[0055]
  Further, for the purpose of improving the dispersibility of the conductive filler, a conductive filler such as carbon black treated with a coupling agent such as silane, aluminate, titanate, or zirconate may be used.
[0056]
  The blending amount of such carbon black is 3 to 30% by weight in the belt.TheA particularly preferred range within the above range is 10 to 25% by weight. When the above range is exceeded, the appearance of the product is deteriorated, and the material strength is lowered, which is not preferable.
[0057]
  (Additional ingredients; optional ingredients)
  In the seamless belt of the present invention, arbitrary blending components can be blended according to various purposes.
[0058]
  Specifically, irgafos 168, irganox 1010, antioxidants such as phosphorus antioxidants, heat stabilizers, various plasticizers, light stabilizers, ultraviolet absorbers, neutralizers, lubricants, antifogging agents, anti Various additives such as a blocking agent, a slip agent, a crosslinking agent, a crosslinking aid, a colorant, a flame retardant, and a dispersant can be added.
[0059]
  Furthermore, compounding materials such as various thermoplastic resins, various elastomers, thermosetting resins, and fillers can be blended as the second and third components within a range that does not significantly impair the effects of the present invention.
[0060]
  Thermoplastic resins include polypropylene, polyethylene (high density, medium density, low density, linear low density), propylene ethylene block or random copolymer, rubber or latex components such as ethylene / propylene copolymer rubber, styrene Butadiene rubber, styrene-butadiene-styrene-styrene block copolymer or its hydrogenated derivatives, polybutadiene, polyisobutylene, polyamide, polyamideimide, polyacetal, polyarylate, polycarbonate, polyimide, liquid crystalline polyester, polysulfone, polyphenylene sulfide, poly Bisamidotriazole, polyetherimide, polyetheretherketone, acrylic, polyfluorinated vinylidene, polyfluorinated vinyl, polychlorotrifluoroethylene, ethylene Tetrafluoroethylene copolymer, hexafluoropropylene tetrafluoroethylene copolymer, tetrafluoroethylene perfluoroalkyl vinyl ether copolymer, alkyl acrylate ester copolymer, polyester ester copolymer, polyether ester copolymer, poly What consists of 1 type, such as an etheramide copolymer and a polyurethane copolymer, or these mixtures can be used. As a thermosetting resin, what consists of 1 type, such as an epoxy resin, a melamine resin, a phenol resin, unsaturated polyester resin, or these mixtures, for example can be used. Examples of various fillers include calcium carbonate (heavy and light), talc, mica, silica, alumina, aluminum hydroxide, zeolite, wollastonite, diatomaceous earth, glass fiber, glass beads, bentonite, asbestos, and hollow. Glass ball, graphite, molybdenum disulfide, titanium oxide, carbon fiber, aluminum fiber, styrene steel fiber, brass fiber, aluminum powder, wood powder, rice husk, metal powder, conductive metal oxide, organometallic compound, organometallic salt In addition to fillers such as antioxidants as additives (phenolic, sulfur, phosphate ester, etc.), lubricants, various organic and inorganic pigments, UV inhibitors, antistatic agents, dispersants, neutralizing agents, Examples thereof include a foaming agent, a plasticizer, a copper damage inhibitor, a flame retardant, a crosslinking agent, and a flow improver.
[0061]
  (Heat kneading)
  In the present invention, crystalline resin, amorphous resin, polymerization catalyst, Chelators and conductive materialsA seamless belt can be formed after heating and kneading to form a resin composition, or a seamless belt can be obtained as it is by heating and kneading a crystalline resin, an amorphous resin, and a polymerization catalyst.
[0062]
  In this case, the conditions should be adjusted so that a bond between the crystalline resin and the amorphous resin can be generated either by heat kneading at the stage of obtaining the resin composition or by heat kneading at the stage of molding the resin composition into a seamless belt. It ’s fine. In any case, since the heating temperature cannot be sufficiently dispersed unless it is in a molten state, it is preferable that the heating temperature is higher to some extent. Is preferable, and it is further more preferable that it is melting | fusing point +10 degreeC or more. In addition, if the heating temperature is too high, thermal decomposition may be caused and physical properties may be deteriorated. Therefore, it is preferable that the heating temperature is low to some extent. Specifically, the melting point of the crystalline resin is used as a guideline. The following is preferable, and it is more preferable that it is melting | fusing point +60 degrees C or less.
[0063]
  Moreover, since a seamless belt with better physical properties may be obtained by drying the raw material before heating and kneading, it is preferable to perform drying.
[0064]
  In some cases, after heat-kneading to obtain a resin composition, heat treatment is performed at a melting point or lower to form an ester bond, and then a seamless belt can be formed.
[0065]
  In the present invention, it is considered that the polymerization catalyst promotes the reaction of the crystalline resin and the amorphous resin to obtain a seamless belt having excellent physical properties. Since the reaction to be promoted is important for the temperature during heat kneading and the time for receiving heat, it is necessary to set the heat kneading conditions while grasping the dispersion form of the obtained seamless belt. Care must be taken because a low molecular weight product is generated as a by-product during this reaction, and if it cannot be removed from the system, this will cause a decrease in molecular weight and foaming of the molded product. On the other hand, since it is considered that the reaction state immediately before the occurrence of foaming of these products is considered to be the best reaction state, for example, various investigations are made on the residence time, the residence time at which foaming occurs is determined, and the residence time is a little shorter than that time. Setting the time is preferable because the best heat-kneading conditions can be obtained.
[0066]
  Although it is a means for heat kneading, there is no particular limitation on this, and a known technique can be used. For example, crystalline resin, amorphous resin, polymerization catalyst, Chelators and conductive materialsCan be heated and kneaded to obtain a resin composition, a single-screw extruder, a twin-screw kneading extruder, a Banbury mixer, a roll, a Brabender, a plastograph, a kneader, or the like can be used. Moreover, even when obtaining a seamless belt from the resin composition obtained in this way, a well-known technique can be used. For example, an injection molding machine or an extrusion molding machine.
[0067]
  (Heat treatment)
  By heat-treating the obtained seamless belt, it becomes possible to obtain a molded member having further improved physical properties.
[0068]
  Although the heat treatment conditions depend on the raw material resin used, the temperature is usually 60 to 200 ° C., preferably 70 to 120 ° C. for 5 to 60 minutes, preferably about 10 to 30 minutes.
[0069]
  In particular, in the case of a seamless belt, which will be described later, the number of folding resistance and the tensile elastic modulus are improved.
[0070]
  (Chemical bond between molecular chain of crystalline resin and molecular chain of amorphous resin)
  In the seamless belt of the present invention, by forming a chemical bond between the molecular chain of the crystalline resin and the molecular chain of the amorphous resin, the affinity between both resins is increased, and the fine dispersion of the form is promoted. A seamless belt having both high bending resistance of the resin, dimensional stability of the amorphous resin, and (depending on conditions) can be obtained.
[0071]
  The abundance ratio of the chemical bond is not particularly limited, but is basically preferably larger. Specifically, the crystallinity per mol of chemical bond between the molecular chain of the crystalline resin and the molecular chain of the amorphous resin. The total mass of the resin and the amorphous resin is preferably 300,000 g or less, particularly preferably 100,000 g or less.
[0072]
  Although there is no restriction | limiting in particular in the measuring method of the quantity of a chemical bond, For example, it can measure by NMR.
[0073]
  A measurement example in the case of using PBT as the crystalline resin and PC as the amorphous resin is shown below.
  Measurement model JEOLGSSX400
  Solvent 1,1,1,2,2,2-hexafluoroisopropanol /
            d-chloroform = 3/7 (VOL)
  Accumulation count 128 times
  Standard TMS
[0074]
  By this measurement, the charts shown in FIGS. FIG. 2 is an enlarged view of the portion II in FIG.
[0075]
  The chemical shift of benzene ring hydrogen of terephthalic acid (TPA) differs between when carboxylic acid is bonded to butanediol and bisphenol A (BPA).
[0076]
  In general, four TPA benzene ring hydrogens (d) in the PBT molecule are equivalent as shown in Chemical formula 1, and show a singlet peak at a chemical shift of 8.07.
[0077]
[Chemical 1]

[0078]
  On the other hand, the benzene ring hydrogen in TPA of PBT bonded to BPA of PC as shown in Chemical formula 2 changes chemical shift, hydrogen (b) has a doublet at 8.25, and (c) has a doublet peak at 8.13. Show.
[0079]
[Chemical 2]

[0080]
  The area ratio of (d): {(b) + (c)} can determine the ratio of TPA in the PBT molecule to TPA bound to PC.
[0081]
  In this example, the area ratio is (d): {(b) + (c)} = 100: {0.4654 + 0.5635} ≈99.01: 0.99, so 0.99 mol per 100 mol of PBT structural unit. It can be seen that it has a TPA (derived from PBT) -BPA (derived from PC) bond. In addition, since it can be easily estimated that the same amount of butanediol (derived from PBT) -carbon (PC) bond is present in the resin composition, 1.98 mol of PBT-PC bonds per 100 mol of PBT structural units in total. Is understood to exist.
[0082]
  As shown in Chemical formula 3, since the formula amount of the PBT structural unit (butanediol + TPA) is 220, there is 1.98 mol of PBT-PC bond per g of PBT22000 (220 × 100 mol).
[0083]
  The mass of PBT per mol of PBT-PC bond can be calculated as about 11000 (22000 / 1.98).
[0084]
  In this example, since the weight ratio of PBT to PC is 7/3, the resin content (PBT mass + PC mass) per 1 mol of PBT-PC bond can be determined to be 16000 g (11000 / 0.7).
[0085]
[Chemical 3]

[0086]
  (Molecular weight)
  In the present invention, crystalline resin, amorphous resin, polymerization catalyst, Chelators and conductive materialsA seamless belt obtained by heating and kneading, generating a chemical bond between the molecular chain of the crystalline resin and the molecular chain of the amorphous resin, and maintaining or increasing the total molecular weight as the resin composition Therefore, it is preferable that the molecular weight is higher.
[0087]
  Although it is a method for measuring molecular weight, it is difficult to determine the true value of molecular weight when a copolymer is present as in the present invention.
[0088]
  Therefore, in the present invention, all resins were measured by GPC under the same conditions, and the value obtained as the PS-converted weight average molecular weight was used as a common representative value.
[0089]
  As measurement conditions, 20 mg of a sample was dissolved overnight in 0.5 ml of 1,1,1,3,3,3-hexafluoro-2-propanol and 0.2 ml of chloroform, and further 25 ml of a mobile phase solvent was added. The solution was filtered through a 0.22 μm filter to obtain a SEC measurement solution. It was performed within 12 hours from the addition of the mobile phase to the end of the measurement.
[0090]
  SEC measurement conditions
    Solvent chloroform / acetic acid: 99.5: 0.5 (vol / vol)
    Flow rate 1.0ml / min
    Injection volume 0.02ml
    2 columns AD806M / S (made by Showa Denko)
    Column temperature 30 ° C
    Detector UV 254nm
[0091]
  Using 12 samples of monodispersed standard polystyrene (manufactured by Tosoh Corp.) having different molecular weights from 500 (A-500) to 2,890,000 (F-288), a calibration curve was prepared and the molecular weight in terms of polystyrene was calculated.
[0092]
  This method, crystalline resin, amorphous resin, and polymerization catalyst, Chelators and conductive materialsPS-converted weight average molecular weight (Mw) of the resin composition obtained after heat kneading₃Specifically, as the value of X, the blending ratio of the crystalline resin is X parts by weight, and the weight average molecular weight in terms of polystyrene (PS) is Mw.₁, The blending ratio of the amorphous resin is Y parts by weight, and the weight average molecular weight in terms of PS is Mw₂As
[Expression 2]

It is preferable that
[Equation 3]

More preferably,
[Expression 4]

It is particularly preferable because sufficiently high physical properties can be obtained.
[0093]
  In the present invention, Mw₃Mw by heating and mixing₁And Mw₂It is important that it is higher than the arithmetic average value of₁And Mw₂If the molecular weight is reduced during heating and mixing, the final Mw₃It is considered that good physical properties cannot be expected even if the₃The absolute value of is not particularly limited, but it is still preferably high from a comprehensive point of view. Specifically, the weight average molecular weight in terms of PS is preferably 130,000 or more, more preferably 140,000 or more, and 150, 000 or more is particularly preferable.
[0094]
  As an example of the correlation between the true value of the weight average molecular weight and the weight average molecular weight in terms of PS, when a PBT having a weight average molecular weight of 40,000 is measured by the above method, a value of PS equivalent weight average molecular weight of 122,000 is obtained. It is known that when a PC having an average molecular weight of 28,000 is measured by the above method, a PS-converted weight average molecular weight of 64,000 is obtained.
[0095]
  (Distributed form)
  Generally, it is known that even if two types of thermoplastic resins are melt-mixed, they are not completely mixed and have a fluid structure. If there is a large difference in volume fraction between the two thermoplastic resins, the larger the volume fraction is, the smaller the volume fraction is, and the smaller the volume fraction, the easier it is to form an island structure. It has been said that it has an influence on the sea-island structure, and the smaller melt viscosity is more likely to become the sea, and the larger is likely to become the island.
[0096]
  In general melt mixing, the dispersed particle diameter is only about 100 nm. However, in the present invention, it is possible to reduce the dispersed particle diameter to several nanometers or less by optimizing the conditions. The seamless belt can be made transparent.
[0097]
  In general, a seamless belt containing a crystalline resin such as PBT is known to have no transparency. However, if the method according to the present invention is used, a transparent seamless belt can be surprisingly obtained.
[0098]
  There is no particular limitation on the method for confirming the dispersion state.₄After staining with, a known method such as preparing an ultrathin section and observing with TEM can be used.
[0099]
  In particular, it can be suitably used in the OA equipment field where the required physical properties such as dimensional accuracy, flex resistance, and tensile elongation at break are strict, especially for functional members. For example, the seamless belt shape is suitable because it has few defects such as cracking and elongation. .
[0100]
  (Seamless belt)
  The seamless belt of the present invention is used as an intermediate transfer belt, a transfer transfer belt, a photoreceptor belt or the like in an image forming apparatus such as an electrophotographic copying machine, a laser beam printer, or a facsimile machine.
[0101]
  In order to obtain a seamless belt, a technique in which a crystalline resin, an amorphous resin, and a polymerization catalyst are mixed by, for example, a twin-screw kneading extruder and pelletized to form a seamless belt is particularly preferably used.
[0102]
  The molding method is not particularly limited, and can be obtained by employing a known method such as a continuous melt extrusion molding method, an injection molding method, a blow molding method, or an inflation molding method. This is a continuous melt extrusion method. In particular, the internal cooling mandrel method or vacuum sizing method of the downward extrusion method capable of controlling the inner diameter of the extruded tube with high accuracy is preferable, and the internal cooling mandrel method is most preferable.
[0103]
  In addition, a seamless belt with better physical properties can be obtained by optimizing the temperature and residence time during molding, so it is preferable to adjust the conditions according to each formulation.
[0104]
  (Physical properties of seamless belt)
  According to the present invention, a seamless belt having the following physical properties can be obtained.
  ・ Physical properties: Fold resistance
  When the seamless belt used in the present invention is used as an intermediate transfer belt in an image forming apparatus, for example, a crack is generated and an image cannot be obtained if the bending resistance is poor. Therefore, a seamless belt having good bending resistance is preferable.
[0105]
  The degree of bending resistance can be quantitatively evaluated by following the method for measuring the number of folding times according to JIS P-8115. It is judged that the seamless belt having the larger number of folding times is less likely to crack and has excellent bending resistance. be able to.
[0106]
  As a specific numerical value, if it is 500 times or more, it can be used as a seamless belt, but it is practically preferably 5000 times or more, more preferably 10,000 times or more, more preferably 30000 times or more. If it is, it will become difficult to generate | occur | produce a crack especially, and it is especially preferable.
[0107]
  ・ Tensile modulus
  If the tensile elastic modulus of the seamless belt is low, for example, when it is used in an image forming apparatus as an intermediate transfer belt, a slight elongation may occur due to the tension, which may cause problems such as color misalignment. More specifically, it is preferably 1000 MPa or more, more preferably 1500 MPa or more, further preferably 2000 MPa or more, and particularly preferably 2500 MPa or more, since problems such as color misregistration can be significantly suppressed.
[0108]
  In general, a soft plastic has a high folding resistance but tends to have a low tensile elastic modulus. Conversely, a hard plastic can obtain a high tensile elastic modulus but tends to become brittle and often has only a low folding resistance. In this invention, it can be said that it is useful in the meaning which can obtain a high frequency | count of folding-proof, maintaining the characteristic of the inherent high tensile elasticity modulus which PBT and PC have.
[0109]
  ・ Physical properties; surface resistivity
  Seamless belt used in the present inventionIs guidedConductivity can be obtained by blending a conductive filler or a substance that develops conductivity.
[0110]
  The resistance region varies depending on the purpose, but the surface resistivity is 1-1 × 10¹⁶It is preferable to select from the range of Ω.
[0111]
  The preferred range varies depending on the application. For example, when used as a photoreceptor belt, 1 to 1 × 10 10 so that the charge on the outer surface can escape to the inner surface as necessary.⁹A low surface resistivity of Ω is preferable, and when used as an intermediate transfer belt, 1 × 10 can be easily charged and transferred.⁶~ 1x10¹³Ω is preferable, and when used as a conveyance transfer belt, it is easily charged and is not easily damaged even at a high voltage.¹⁰~ 1x10¹⁶A high region such as Ω is preferable.
[0112]
  Further, it is preferable that the distribution of the surface resistivity in one seamless belt is narrow, and in each preferable surface resistivity region, the difference between the maximum value and the minimum value in one belt is within two digits (the maximum value is It is preferably within 100 times the minimum value).
[0113]
  The surface resistivity of the film can be easily measured by, for example, Hiresta, Loresta manufactured by Dia Instruments Co., Ltd. or R8340A manufactured by Advantest Co., Ltd.
[0114]
  ・ Thickness of seamless belt
  The thickness of the seamless belt is preferably 50 to 1000 μm, more preferably 80 to 500 μm, and particularly preferably 100 to 200 μm.
[0115]
  ・ Use of seamless belt
  The seamless belt may be used as it is, or may be wound around a drum or a roll.
[0116]
  Further, for the purpose of preventing meandering or reinforcing the end surface, a heat-resistant tape is affixed to the inside and / or the vicinity of the outside edge of the seamless belt of a predetermined size, or a tape such as urethane rubber or silicone rubber is attached to the inside edge of the belt You may affix on the part vicinity.
[0117]
【Example】
  The present invention will be described more specifically with reference to examples and comparative examples.
[0118]
  (material)
  The following materials were used, and the blending ratios were as shown in Table 1 or Table 2.
PBT; weight average molecular weight 40,000; PS equivalent weight average molecular weight 122,000
PC; weight average molecular weight 28,000; PS-converted weight average molecular weight 64,000
Polymerization catalyst: Titanium (IV) butoxide
          Magnesium acetate
Chelator; Phosphorylation antioxidant PEPQ Made by Clariant Japan Co., Ltd.
Carbon black; Denka black; manufactured by Electrochemical Co., Ltd.
[0119]
  (Heat kneading)
  Each raw material was pelletized using a twin-screw kneading extruder (PMT32 manufactured by IKG Corporation).
[0120]
  (Seamless belt molding method)
  This material pellet was dried and extruded in a molten tube state below the annular die by a 40 mmφ extruder with a 6-spiral annular die having a diameter of 180 mm and a lip width of 1 mm. The extruded molten tube was placed on the same axis as the annular die. The belt is cooled and solidified by coming into contact with the outer surface of a cooling mandrel having an outer diameter of 170 mm mounted via a support rod, and then the seamless belt is formed by the core installed in the seamless belt and the roll installed outside. Was taken out in a cylindrical shape, and was cut into a length of 340 mm to adjust the extrusion amount and the take-up speed so that a predetermined thickness and a residence time described in each table were obtained, to obtain a resin seamless belt having a diameter of 169 mm. . The target thickness was 140 μm, and the allowable range was ± 14 μm.
[0121]
  Conditions such as molding temperature and residence time were as shown in Tables 1 and 2.
[0122]
  (Evaluation)
  The evaluation was carried out by opening the seamless belt to the required size as required.
・ Thickness
  Measured with a 20 mm pitch in the circumferential direction of the seamless belt using a micrometer manufactured by Tokyo Seimitsu Co., Ltd.
・ Folding resistance
    JIS P-8115 compliant
・ Surface resistivity Ω
  The surface resistivity can be appropriately measured depending on the measuring instrument, and therefore the surface resistivity was properly used as follows.
  1-1 × 10⁶Sample that becomes Ω Using a Loresta manufactured by Dia Instruments Co., Ltd., the belt circumferential direction was measured at a pitch of 20 mm.
  10⁶~ 1x10¹³Sample that becomes Ω Using a Hiresta (HA terminal) manufactured by Dia Instruments Co., Ltd., the belt circumferential direction was measured at a pitch of 20 mm under conditions of 500 V and 10 seconds.
  10¹³~ 1x10¹⁶Sample to be Ω Advantest Co., Ltd. Microcurrent measuring instrument R8340A (JIS electrode) was used, and the belt circumferential direction was measured at a pitch of 100 mm under conditions of 500 V and 10 seconds.
  Measurement time 10 seconds
[0123]
・ Evaluation of durability as a seamless belt
  The obtained seamless belt was mounted on an image forming apparatus as an intermediate transfer belt, a transfer transfer belt, or a photosensitive belt, and images were continuously output, and the number of sheets that were output was evaluated for cracks in the seamless belt. .
[0124]
・ Tensile modulus
  In accordance with ISO R1184-1970, the test piece was cut to a width of 15 mm and a length of 150 mm, the tensile speed was 1 mm / min, and the distance between the grips was 100 mm.
[0125]
・ Tensile elongation at break
  In accordance with JISZ1702-62, the test piece was cut into a width of 15 mm and a length of 150 mm, the pulling speed was 50 mm / min, the distance between the grips was 100 mm, and the marked line interval was 50 mm.
[0126]
  [Example 1]
  PBT, PC, tetrabutyl titanate, magnesium acetate,ChelatorWas pre-dried at about 130 ° C. in advance, and then heat-kneaded to obtain material pellets.
[0127]
  The heating and kneading conditions at this time were such that the resin temperature and the residence time in the kneader were adjusted, and the reaction in the kneader was suppressed.
[0128]
  The material pellets were extruded to obtain a transparent film.
[0129]
  The extrusion conditions were adjusted for the resin temperature and the residence time so that the reaction was accelerated to a preferred level in this extruder and a transparent seamless belt was obtained.
[0130]
  Table 1 shows the form, characteristics, and appearance of the film.
[0131]
  Furthermore, when the obtained seamless belt was heat-treated at 80 ° C. for 10 minutes, the tensile elastic modulus was improved by 5%.
[0132]
  [Comparative Example 1]
  A seamless belt obtained under the same conditions as in Example 1 except that the polymerization catalyst was omitted.
[0133]
  In order to remove the influence of the metal content in the resin as an impurity, PBT was once dissolved in a solvent, filtered using a column, and then the solvent was removed.
[0134]
  Unlike Example 1, a transparent seamless belt could not be obtained no matter how much the extrusion molding conditions (molding temperature, residence time) were adjusted.
[0135]
  Table 1 shows the form, characteristics, and appearance of the film.
[0136]
[Table 1]

[0137]
  [Example 2]
  PBT, PC, tetrabutyl titanate, magnesium acetate,ChelatorThe carbon black was preliminarily dried and then heated and kneaded to obtain material pellets.
[0138]
  Thereafter, the material pellets were formed into a seamless belt by an extruder.
[0139]
  As shown in Table 2, the obtained molded product had a remarkably high folding resistance of 58,000 times and a high tensile elastic modulus and good physical properties.
[0140]
  Surface resistivity is 1 × 10 on average¹⁰Ω and volume resistivity is 1 × 10 on average¹⁰When it was mounted on the image forming apparatus as an intermediate transfer belt, an image could be obtained satisfactorily. Further, no cracks were generated even when 100,000 images were output in this state.
[0141]
  In this example, it is considered that a molded article having good physical properties could be obtained by setting an appropriate residence time and molding temperature by heating and kneading at the time of molding.
[0142]
  Furthermore, when the obtained seamless belt was heat-treated at 80 ° C. for 20 minutes, the tensile elastic modulus was improved by 8%.
[0143]
  Example 3
  A seamless belt was obtained under the same conditions as in Example 1 except that the weight ratio of PBT and PC was changed and the residence time was increased during molding. Also in Example 3, good physical properties were obtained as in Example 1 as shown in Table 2.
[0144]
  The reason why the residence time was increased is considered to be that the point of the appropriate reaction conditions of the system was changed by changing the PBT / PC ratio.
[0145]
  Furthermore, when the obtained seamless belt was heat-treated at 80 ° C. for 10 minutes, the tensile elastic modulus was improved by 7%.
[0146]
  Example 4
  A seamless belt with high surface resistivity was obtained by lowering the carbon concentration. As shown in Table 2, even in Example 4, a uniformly dispersed state was obtained and the physical properties were good. When this seamless belt was mounted on an image forming apparatus as a transfer transfer belt, a good image could be obtained.
[0147]
  Furthermore, when the obtained seamless belt was heat-treated at 80 ° C. for 10 minutes, the tensile elastic modulus was improved by 5%.
[0148]
  Example 5
  A seamless belt having a low surface resistivity was obtained by increasing the carbon concentration. As shown in Table 2, even in Example 5, a uniformly dispersed state was obtained and the physical properties were good. When this seamless belt was used as a photoreceptor belt and a photosensitive layer was provided on the surface thereof and mounted on an image forming apparatus, a good image could be obtained.
[0149]
  Furthermore, when the obtained seamless belt was heat-treated at 80 ° C. for 10 minutes, the tensile elastic modulus was improved by 5%.
[0150]
  [Comparative Example 2]
  A seamless belt was produced under the same conditions as in Example 2 except that the polymerization catalyst was omitted.
[0151]
  In order to remove the influence of the metal content in the resin as an impurity, PBT was once dissolved in a solvent, filtered using a column, and then the solvent was removed.
[0152]
  The tensile elastic modulus was almost the same as in Example 1, but the number of folding times was low. Moreover, when form observation was carried out, it turned out that PC has taken the 2 phase-separation structure used as an island. When the image forming apparatus was mounted as an intermediate transfer belt, an image could be obtained satisfactorily. However, when image output was continued in this state, cracks occurred when 8000 sheets were output.
[0153]
[Table 2]

[0154]
【The invention's effect】
  As is clear from the above Examples and Comparative Examples, according to the present invention, a seamless belt excellent in flex resistance, chemical resistance and molding dimensional stability, and suppressing physical property deterioration due to reaction during melt mixing, and this seamless belt There are provided an image forming apparatus belt using the belt and an image forming apparatus using the image forming apparatus belt.
[Brief description of the drawings]
FIG. 1 is an NMR chart of a mixed reaction product of PBT and PC.
FIG. 2 is an enlarged view of a portion II in FIG.
FIG. 3 is a side view of a conventional intermediate transfer apparatus.
[Explanation of symbols]
  1 Photosensitive drum
  2 Charger
  3 Exposure optical system
  4 Developer
  5 Cleaner
  6 Conductive seamless belt
  7, 8, 9 Transport roller

Claims (13)

A crystalline resin having at least one of a hydroxyl group, a carboxylic acid and an ester bond, an amorphous resin having at least one of a hydroxyl group, a carboxylic acid and an ester bond, a polymerization catalyst, a chelator and a conductive substance are mixed by heating. And a seamless belt formed by molding,
The crystalline resin is selected from PBT (polybutylene terephthalate), PET (polyethylene terephthalate), and PEN (polyethylene naphthalate);
The amorphous resin is selected from PC (polycarbonate), PAr (polyarylate), and PMMA (polymethyl methacrylate);
The compounding amount of the polymerization catalyst is 50 to 500 ppm with respect to the resin in terms of the mass of the metal in the polymerization catalyst, and the compounding amount of the chelator is 0.1 to 3 parts by weight with respect to 100 parts by weight of the resin.
A seamless belt having a conductive material content of 3 to 30% by weight.   The seamless belt according to claim 1, wherein a chemical bond exists between the molecular chain of the crystalline resin and the molecular chain of the amorphous resin. The seamless belt according to claim 1 or 2, wherein the weight ratio of the components satisfies the following conditions.
The weight ratio of crystalline resin / amorphous resin is 1/99 to 99/1.
The metal in the polymerization catalyst is 1 ppm to 10000 ppm relative to the weight of (crystalline resin + amorphous resin). The compounding ratio of the crystalline resin is X parts by weight, the polystyrene (PS) equivalent weight average molecular weight is Mw ₁ , the amorphous resin compounding ratio is Y parts by weight, the PS equivalent weight average molecular weight is Mw ₂ , the crystalline resin, amorphous The seamless belt according to any one of claims 1 to 3, wherein when the weight average molecular weight in terms of PS of the resin composition obtained after heat-kneading the functional resin and the polymerization catalyst is Mw ₃ , the following relationship is satisfied: .

  The seamless belt according to any one of claims 1 to 4, wherein the PS-converted weight average molecular weight is 130,000 or more.   The seamless belt according to any one of claims 1 to 5, wherein the polymerization catalyst contains Ti.   The seamless belt according to any one of claims 1 to 6, wherein the polymerization catalyst contains at least one member selected from the group consisting of alkali metals, alkaline earth metals, and zinc, and Ti.   The seamless belt according to claim 7, wherein the element of the group is Mg. The seamless belt according to any one of claims 1 to 8, wherein the crystalline resin is PBT (polybutylene terephthalate).   The seamless belt according to any one of claims 1 to 9, wherein the amorphous resin is PC (polycarbonate).   The seamless belt according to any one of claims 1 to 10, wherein carbon black is contained as a conductive substance.   An image forming apparatus belt comprising the seamless transfer belt according to claim 1, the intermediate transfer belt for an image forming apparatus, a transfer transfer belt, or a photosensitive belt.   An image forming apparatus comprising the belt for an image forming apparatus according to claim 12.

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