JP3636103B2 - Molded member, endless belt, belt for image forming apparatus, and image forming apparatus - Google Patents

Description

【００５３】
（（Ｉ）式中、Ｒ¹，Ｒ²，Ｒ³はそれぞれ独立に水素又は炭素数１〜２０のアルキル基又はアリール基であり、Ｚは単結合又は酸素原子で少なくともその一つは酸素原子である。）
【００５４】
リン酸エステルの具体例としてはリン酸トリエチル、リン酸トリブチル、リン酸トリフェニル等が挙げられる。
【００５５】
また、亜リン酸エステルとしては下記一般式（II）〜（IV）で示されるものが挙げられる。
【００５６】
【化２】

【００５７】
（（II）式中、Ｒ⁴，Ｒ⁵，Ｒ⁶はそれぞれ独立に炭素数１〜２０のアルキル基、アリール基、シクロアルキル基、アルアルキル基、アルキルアリール基を示し、Ｚは単結合又は酸素原子で少なくとも一つは酸素原子である。）
【００５８】
その具体例としては、トリエチルホスファイト、トリブチルホスファイト、トリス（２−エチルヘキシル）ホスファイト、トリデシルホスファイト、トリステアリルホスファイト、トリフェニルホスファイト、トリクレジルホスファイト、トリス（ノニルフェニル）ホスファイト、トリス（２，４−ジ−ｔ−ブチルフェニル）ホスファイト、デシル−ジフェニルホスファイト、フェニル−ジ−２−エチルヘキシルホスファイト、フェニル−ジデシルホスファイト、トリス（ビフェニル）ホスファイト、トリシクロヘキシルホスファイト等が挙げられる。
【００５９】
【化３】

【００６０】
（（III）式中、Ｒ⁷，Ｒ⁸，Ｒ⁹，Ｒ¹⁰はそれぞれ独立に（II）式のＲ⁴，Ｒ⁵，Ｒ⁶の定義に属するものであり、Ｚは（II）式のＺと同一定義のものである。Ｙは炭素数１〜３０のアルキレン基、アリーレン基、シクロアルキレン基、アルアルキレン基、アルキルアリーレン基を示す。）
【００６１】
その具体例としては、テトラフェニル−４，４'−イソプロピリデン−ジフェノールジホスファイト、テトラトリデシル−４，４'−イソプロピリデン−ジフェノールジホスファイト、テトラトリデシル−４，４'−ブチリデンビス（３−メチル−６−ｔ−ブチルフェノール）ジホスファイト、テトラキス（２，４−ジ−ｔ−ブチルフェニル−４，４'−ビフェニレン）ホスファイト等が挙げられる。
【００６２】
【化４】

【００６３】
（（IV）式中、Ｒ¹¹は炭素数１〜３０のアルキル基、アリール基、シクロアルキル基、アルアルキル基、アルキルアリール基であり、Ｒ¹²は炭素数１〜２０のアルキレン基であり、Ｚは式（II）のＺと同一定義のものである。）
【００６４】
その具体例としては、ビス（ステアリル）ペンタエリスリトールジホスファイト、ビス（２，６−ジ−ｔ−ブチルフェニル）ペンタエリスリトールジホスファイト、ビス（ノニルフェニル）ペンタエリスリトールジホスファイト等が挙げられる。
【００６５】
上記した各種の化合物の内でも、特にトリブチルホスファイト、トリフェニルホスファイト、ビス（ステアリル）ペンタエリスリトールジホスファイト及びビス（２，６−ジ−ｔ−ブチルフェニル）ペンタエリスリトールジホスファイトが好ましい。
【００６６】
キレーターの配合量は含有反応触媒量により異なるので特に規定しないが、少ないと反応抑制剤としての添加効果を殆ど発揮せず、ある程度の濃度を超えた時点から顕著に効果を発揮する。従って、本発明においては、成形原料中における反応触媒の金属にキレートするキレーターの元素重量として好ましくは１０ｐｐｍ以上、より好ましくは５０ｐｐｍ以上、特に好ましくは１００ｐｐｍ以上とする。なお、キレーターの配合量が多過ぎると反応触媒の活性が失われ、良好な成形部材が得られなくなるため、成形原料中における反応触媒の金属にキレートするキレーターの元素重量として６０００ｐｐｍ以下、特に３０００ｐｐｍ以下とする。なお、以下において、成形原料の合計重量に対するキレーターの反応触媒の金属にキレートする元素の重量割合を「キレート元素濃度」と称す場合がある。
【００６７】
（導電性物質）
本発明において、成形部材の電気抵抗値を調整するために導電性物質を配合する。特に画像形成装置に用いられるエンドレスベルト等においては電気的にトナーや紙等を吸着、転写させるために表面抵抗値や体積抵抗値を用途に合わせて調整する必要があるため、成形原料中に導電性物質を配合する。
【００６８】
配合する導電性物質としては、分散性に優れているカーボンブラックを用いる。
【００７０】
カーボンブラックの種類としては、アセチレンブラック、ファーネスブラック、チャンネルブラックなどが好適に使用でき、この中でも不純物としての官能基が少なくカーボン凝集による外観不良を発生しにくいアセチレンブラックが特に好適に使用できる。さらに一次粒子径が１０〜１００ｎｍ、比表面積１０〜２００ｍ²／ｇ，ｐＨ値３〜１１のものがより好ましい。
【００７１】
また、使用するカーボンブラックは１種類であっても２種類又はそれ以上であっても良い。さらには、カーボンブラックには樹脂を被覆したカーボンブラックや、黒鉛化処理したカーボンブラックや、酸性処理したカーボンブラック等の公知の後処理工程を施したカーボンブラックを用いても何ら問題はない。
【００７２】
また、導電性物質の分散性を向上させる目的でシラン系、アルミネート系、チタネート系、又はジルコネート系等のカップリング剤で処理したカーボンブラックを用いても良い。
【００７３】
導電性物質の配合量としては、使用する導電性物質の物性により発現する抵抗値は変化するので、所望する抵抗値が得られる導電性物質濃度を見極めて設定する必要がある。本発明においては、成形部材中のカーボンブラックの割合（以下例えば、「カーボンブラック濃度」と称す場合がある。）が、１〜５０重量％、好ましくは１〜３０重量％、特に好ましくは１〜２５重量％とする。上記範囲を超えると製品の外観が悪くなり、また、材料強度が低下して好ましくない。
【００７４】
（付加的配合材；任意成分）
本発明の成形部材の成形原料には、各種目的に応じて任意の配合成分を配合することができる。
【００７５】
具体的には、日本チバガイギー社製イルガノックス１０１０（商品名）などの酸化防止剤、熱安定剤、各種可塑剤、光安定剤、紫外線吸収剤、中和剤、滑剤、防曇剤、アンチブロッキング剤、スリップ剤、架橋剤、架橋助剤、着色剤、難燃剤、分散剤等の各種添加剤を添加することができる。
【００７６】
更に、本発明の効果を著しく損なわない範囲内で、第２，第３成分として各種熱可塑性樹脂、各種エラストマー、熱硬化性樹脂、フィラー等の配合材を配合することができる。
【００７７】
付加成分としての熱可塑性樹脂としてはポリプロピレン、ポリエチレン（高密度，中密度，低密度，直鎖状低密度）、プロピレンエチレンブロック又はランダム共重合体、ゴム又はラテックス成分、例えばエチレン・プロピレン共重合体ゴム、スチレン・ブタジエンゴム、スチレン・ブタジエン・スチレンブロック共重合体又は、その水素添加誘導体、ポリブタジエン、ポリイソブチレン、ポリアミド、ポリアミドイミド、ポリアセタール、ポリアリレート、ポリカーボネート、ポリイミド、液晶性ポリエステル、ポリスルフォン、ポリフェニレンサルファイド、ポリビスアミドトリアゾール、ポリエーテルイミド、ポリエーテルエーテルケトン、アクリル、ポリフッ素化ビニリデン、ポリフッ素化ビニル、クロロトリフルオロエチレン、エチレンテトラフルオロエチレン共重合体、ヘキサフルオロプロピレン、パーフルオロアルキルビニルエーテル共重合体、アクリル酸アルキルエステル共重合体、ポリエステルエステル共重合体、ポリエーテルエステル共重合体、ポリエーテルアミド共重合体、ポリウレタン共重合体等の１種又はこれらの２種以上の混合物からなるものが使用できる。
【００７８】
熱硬化性樹脂としては、例えばエポキシ樹脂、メラミン樹脂、フェノール樹脂、不飽和ポリエステル樹脂等の１種又はこれらの２種以上の混合物からなるものが使用できる。
【００７９】
また、各種フィラーとしては、例えば炭酸カルシウム（重質、軽質）、タルク、マイカ、シリカ、アルミナ、水酸化アルミニウム、ゼオライト、ウオラストナイト、けいそう土、ガラス繊維、ガラスビーズ、ベントナイト、アスベスト、中空ガラス玉、黒鉛、二硫化モリブデン、酸化チタン、炭素繊維、アルミニウム繊維、スチレンスチール繊維、黄銅繊維、アルミニウム粉末、木粉、もみ殻、グラファイト、金属粉、導電性金属酸化物、有機金属化合物、有機金属塩等のフィラーの他、添加剤として酸化防止剤（フェノール系、硫黄系、リン酸エステル系など）、滑剤、有機・無機の各種顔料、紫外線防止剤、帯電防止剤、分散剤、中和剤、発泡剤、可塑剤、銅害防止剤、難燃剤、架橋剤、流れ性改良剤等を挙げることができる。
【００８０】
次に、本発明における加熱混練、成形、熱処理方法、成形品の物性、用途等について説明する。
【００８１】
（加熱混練，成形，熱処理）
本発明においては、熱可塑性非晶性樹脂、反応触媒、キレーター及び必要に応じて添加される上記付加的配合材を加熱混練して樹脂組成物とした後に成形部材を成形しても良く、熱可塑性非晶性樹脂、反応触媒、キレーター及び必要に応じて添加される上記付加的配合材を加熱混練してそのまま成形部材を成形しても良い。この加熱混練に当っては、予め原料を乾燥することにより、より一層良好な物性の成形部材を得られる場合があることから、加熱混練に先立つ原料の乾燥処理は有効である。
【００８２】
加熱混練の手段には特に制限はなく公知の技術を用いることができる。例えば、まず成形原料を混練して樹脂組成物とするのであれば、一軸押出機、二軸混練押出機、バンバリーミキサー、ロール、ブラベンダー、プラストグラフ、ニーダーなどを用いることができる。また、こうして得た樹脂組成物からエンドレスベルトを得る場合でも公知の技術を用いることができる。例えば射出成形機、押し出し成形機などを用いて常法に従って成形することができる。
【００８３】
このようにして得られた成形部材を熱処理することにより、より物性の向上した成形部材とすることが可能となる。この場合、熱処理条件は用いる原料樹脂にもよるが、通常６０〜２００℃の温度、好ましくは７０〜１２０℃の温度で５〜６０分、好ましくは１０〜３０分程度である。このような熱処理を行うことにより、エンドレスベルトとした場合等において、後述の耐折回数や引張弾性率の向上が見られる。
【００８４】
（本発明の成形部材の用途）
本発明の成形部材の用途に特に制限はなく、ＯＡ機器の構成部品，機能部材、自動車の外装部品，内装材、家電機器の構成部材、汎用フィルムなどとして幅広く用いることができる。
【００８５】
なかでも耐屈曲性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、例えばエンドレスベルト形状として、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ると、割れ，伸びなど不具合が少ないので好適である。
【００８６】
以下に、本発明の成形部材の好適な使用例の一例としてのエンドレスベルトについて説明する。
【００８７】
（エンドレスベルト）
本発明のエンドレスベルトを得るには、前述の熱可塑性非晶性樹脂、反応触媒、キレーター及び必要に応じて配合されるその他の付加成分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エンド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。
【００８８】
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。
【００８９】
また、この成形時の温度，滞留時間の適正化により、より良好な物性のエンド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。
【００９０】
（エンドレスベルトの物性）
本発明によれば、以下のような物性を有するエンドレスベルトを得ることができる。
【００９１】
・耐折回数
本発明のエンド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、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ことから、耐屈曲性の良好なエンドレスベルトが好ましい。
【００９２】
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、耐折回数の大きいエンド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。
【００９３】
具体的な数値としては、５００回以上であれば一応エンドレスベルトとしての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。
【００９４】
・引張弾性率
エンド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以上であるとさらに好ましく、２０００ＭＰａ以上であるとさらに好ましく、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。
【００９５】
・表面抵抗率
本発明のエンドレスベルトでは導電性物質としてカーボンブラックを配合することにより導電性を得ることができる。エンドレスベルトの抵抗領域は目的により異なるが、表面抵抗率１〜１×１０¹⁶Ωの範囲から選定することが好ましい。
【００９６】
表面抵抗率の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１〜１×１０⁶Ω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１×１０⁶〜１×１０¹¹Ω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１×１０¹⁰〜１×１０¹⁶Ωと高い領域が好ましい。
【００９７】
また、エンドレスベルト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本中の最大値が最小値の１００倍以内であることが好ましく、１０倍以内であることが特に好ましい。
【００９８】
エンドレスベルト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。
【００９９】
・エンドレスベルトの厚み
エンド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。
【０１００】
（エンドレスベルトの用途）
本発明のエンドレスベルトは、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た場合、割れ、伸びなど不具合が少なく、長期に亘り安定に使用することができる。
【０１０１】
【実施例】
以下に実施例及び比較例を挙げて、本発明をより具体的に説明する。
【０１０２】
以下の実施例及び比較例では、下記の原料及び成形条件でエンドレスベルトを製造し、その評価を行なって結果を表１に示した。
【０１０３】
（原料）
原料は下記のものを用い、配合割合は表１の通りとした。
【０１０４】
［熱可塑性非晶性樹脂］
ＰＣ（重量平均分子量２８，０００；ＰＳ換算重量平均分子量６４，０００）
ＰＡｒ（重量平均分子量３０，０００；ＰＳ換算重量平均分子量６９，０００）
【０１０５】
［反応触媒］
Ｔｉ系化合物（チタニウム(IV)ブトキシド）
【０１０６】
［キレーター］
Ｐ系化合物（サンドスタブＰ−ＥＰＱ：テトラキス（２，４−ジターシャリブチルフェニル）４，４’−ビフェニリレンジホスホナイト（構造式は下記の通り）；クラリアントジャパン（株）製）
ヒドラジン類（ＩＲＧＡＮＯＸ ＭＤ１０２４；日本チバガイギー（株）製）
【０１０７】
【化５】

【０１０８】
［導電性物質］
カーボンブラック（デンカブラック；電気化学（株）製）
【０１０９】
（加熱混練）
各原料を、二軸混練押出機（ＩＫＧ（株）製 ＰＭＴ３２）を用いて溶融混合し、樹脂組成物をペレット化した。
【０１１０】
（エンドレスベルトの成形方法）
この材料ペレットを１３０℃で８時間乾燥し、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下記に記載の厚み、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エンドレスベルトとした。なお、エンドレスベルトの物性の滞留時間依存性を評価するため、滞留時間を調節し、下記の２種類の条件で成形した。
【０１１１】
条件Ａ；滞留時間１２分、厚み１５０μｍを目標とし、厚みの範囲が±１５μｍになるように調整して成形
条件Ｂ；滞留時間２４分、厚み１５０μｍを目標とし、厚みの範囲が±１５μｍになるように調整して成形
【０１１２】
この条件Ｂでは、条件Ａより滞留時間が長くなるようスクリューの回転を遅くして成形すると共に、条件Ａとベルト厚みが同じになるように引取速度も遅く調整して成形した。
【０１１３】
（評価）
評価は必要に応じ、エンドレスベルトを適当な大きさに切り開いて実施した。
【０１１４】
・耐折回数
ＪＩＳ Ｐ−８１１５準拠
各サンプルで３回づつ測定し、平均値（有効数字２桁）を代表値とした。耐折回数は、耐屈曲疲労性の指標で数字が大きいほど割れにくく丈夫であることを意味する。
【０１１５】
・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ピッチで測定した。
【０１１６】
・表面抵抗率
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。測定時間は１０秒とし、エンドレスベルトの円周方向に２０ｍｍピッチで測定した。
【０１１７】
１〜１０⁶Ωとなるサンプル ：ダイヤインスツルメント（株）製 ロレスタ（商品名）
１０⁶〜１０¹³Ω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）（商品名）（印加電圧５００Ｖ）
１０¹³〜１０¹⁶Ωとなるサンプル：アドバンテスト（株）製 Ｒ８３４０Ａ （商品名）（ＪＩＳ電極）（印加電圧５００Ｖ）
【０１１８】
比較例１
表１の配合で、まず、成形条件Ａで表面抵抗率を１０⁹Ω程度に調整してエンドレスベルトを成形した。この表面抵抗率のエンドレスベルトは中間転写ベルトとして好適に用いることができる。
【０１１９】
この比較例１では、Ｔｉ系化合物は配合しなかったので、共重合化、高分子量化の反応は生じなかったと考えられる。得られた成形部材の耐折回数は２５０回であった。また、成形条件Ｂにおいても条件Ａ品とほぼ同物性のエンドレスベルトを得ることができた。
【０１２０】
本比較例のエンドレスベルトを中間転写ベルトとして画像形成装置に搭載したところ、良好な初期画像を得た。さらに連続で画像出力を続けたが、約３０００枚出力した時点でエンドレスベルトにクラックが発生し、画像出力ができなくなった。
【０１２１】
本樹脂組成物ペレットは成形条件が多少変化してもベルトの物性があまり変化しないので熱的に安定で扱いやすい意味で好ましい材料といえる。ただし、耐折回数２５０回程度であるので、中間転写ベルトとしての初期物性においても実用性能を有さず、物性的には全く不十分であるといえる。
【０１２２】
比較例２
比較例１の配合を基準とし、Ｔｉ系化合物をＴｉ濃度９８ｐｐｍ配合した。得られたペレットでエンドレスベルトの成形を試みたが、条件Ａ，Ｂどちらにおいてもダイ出口から出てきた樹脂は劣化が激しく、ドローダウンしてしまい、エンドレスベルトを得ることができなかった。
【０１２３】
これは、Ｔｉ系化合物が共重合化と高分子量化と共に、解重合の触媒として作用し、本比較例２の条件のもとでは、解重合の方が優先してしまったためと考えられる。
【０１２４】
比較例３
比較例１を基本配合とし、キレーターとしてのＰ系化合物を０．５重量部配合した。
【０１２５】
この比較例３では、比較例１と同様にＴｉ系化合物を配合しなかったので、共重合化、高分子量化の反応は生じなかったと考えられる。得られた成形部材の耐折回数は２７０回であった。また、成形条件Ｂにおいても条件Ａ品とほぼ同物性のエンドレスベルトを得ることができた。
【０１２６】
ただし、耐折回数が低いので、比較例１と同様に中間転写ベルトとしての初期物性においても実用性能を有さず、物性的には全く不十分であるといえる。
【０１２７】
実施例１
比較例３の配合を基本とし、さらにＴｉ系化合物をＴｉ濃度６９ｐｐｍ配合した。
【０１２８】
その結果、成形条件Ａ，Ｂのいずれでも、良好なエンドレスベルトを得ることができ、特に条件Ａでは、耐折回数は１３，０００回と非常に高い値が得られた。
【０１２９】
本実施例１では、成形条件が変わっても、安定して良好且つ高物性のエンドレスベルトを得ることができた。これは、Ｔｉ系化合物にＰ系化合物が配位したことで、触媒としての反応選択性が高められたため、成形条件が変わっても安定して物性の高いエンドレスベルトが得られるようになったためと考えられる。
【０１３０】
実施例２
実施例１の組成を基準とし、Ｔｉ系化合物及びＰ系化合物の配合量をさらに高めた。
【０１３１】
これにより、実施例１よりも更に耐折回数の高い良好なエンドレスベルトを安定的に得ることができた。
【０１３２】
本実施例２のエンドレスベルトを中間転写ベルトとして画像形成装置に搭載したところ、良好な初期画像を得た。さらに連続で画像出力を続けたが、画像形成装置の目標寿命となる約１０万枚出力してもエンドレスベルトにクラックが発生することがなかった。また、耐折回数も高く、中間転写ベルトとして使用しても初期物性を満足し、長期にわたり連続使用できるので良好な物性であるといえる。
【０１３３】
実施例３
実施例２の組成を基準とし、カーボンブラック濃度を下げて表面抵抗率１０¹²Ω程度のエンドレスベルトを得た。本エンドレスベルトは搬送転写ベルトとして好適に用いることができる。
【０１３４】
実施例４
実施例３の組成を基準とし、カーボンブラック濃度を上げて表面抵抗率１０⁴Ω程度のエンドレスベルトを得た。本エンドレスベルトは感光体ベルトの基材として好適に用いることができる。
【０１３５】
実施例５
実施例２の組成を基準とし、キレーターとしてＰ系化合物の代わりにヒドラジン類を１重量部配合してエンドレスベルトを得た。
【０１３６】
上記実施例３〜５においても、耐折回数の高い良好なエンドレスベルトを安定的に得ることができた。
【０１３７】
【表１】

【０１３８】
【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、耐屈曲性や成形寸法安定性等に優れ、溶融混合時の反応による物性劣化を抑えたエンドレスベルト等の熱可塑性非晶性樹脂成形部材と、このエンド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】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 導電性エンドレスベルト
７，８，９ 搬送ローラ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a molded member having excellent physical properties such as bending resistance and molding dimensional stability, an endless endless belt having such excellent physical properties, and an electrophotographic copying machine using the endless belt. The present invention relates to an intermediate transfer belt, a transfer transfer belt, or a photosensitive belt used for a laser beam printer, a facsimile machine, or the like, and an image forming apparatus including the image forming apparatus belt.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, as an image forming apparatus such as an OA apparatus, an electrophotographic system using a photoconductor and toner, and a toner jet system that directly transfers toner onto an endless belt without using a photoconductor are devised and put on the market. These devices include conductive belts, intermediate transfer belts, transfer transfer belts, transfer separation belts, charging tubes, developing sleeves, fixing belts, toner transfer belts, etc., regardless of the presence or absence of seams, conductive, semiconductive, insulating Endless belts controlled to various electrical resistances are used.
[0003]
For example, the intermediate transfer device is configured to once form a toner image on an intermediate transfer member and then transfer the toner to paper or the like. A conductive endless belt is used for charging and discharging the toner on the surface layer of the intermediate transfer member. The endless belt is set (conductive, semiconductive, insulated) to have different surface resistivity and thickness direction electrical resistance (volume specific resistivity) for each machine model.
[0004]
The transport transfer device is configured to hold the paper once on the transport transfer body, transfer the toner from the photosensitive member onto the paper held on the transport transfer body, and further remove the paper from the transport transfer body by discharging. Has been. On the surface of the transport transfer body, an endless belt with or without a seam is used for charging or neutralizing paper. The endless belt is set to have different surface electric resistance and thickness direction electric resistance (volume specific resistivity) for each machine model as described above.
[0005]
FIG. 1 is a side view of a conventional intermediate transfer apparatus. In the figure, 1 is a photosensitive drum and 6 is a conductive endless 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 endless 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.
[0006]
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 endless 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.
[0007]
By the way, in the case of a conductive endless belt such as an electrophotographic copying machine, it is functionally driven for a long time by two or more rolls with a high tension, so that sufficient durability is required. 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.
[0008]
Such an endless 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.
[0009]
Therefore, the following items (1) to (7) are required for the intermediate transfer belt.
(1) The semiconductor region has a predetermined surface resistivity and volume specific resistivity.
(2) Toner releasability.
(3) The thickness is thin and uniform.
(4) Strong mechanical strength (hard to break).
(5) There should be little variation in resistance due to the environment (temperature, humidity).
(6) Low cost.
(7) The belt must be seamless and round.
[0010]
In addition, with the recent high-speed printing of machines, the driving speed of the belt has increased, and it has become necessary to improve the durability of the belt.
[0011]
In particular, attention is paid to the fact that printing can be performed at a high speed with a tandem type transport transfer, intermediate transfer belt or toner jet belt in which four photoconductors are arranged, and durability and image misalignment are particularly important.
[0012]
To date, carbon blacks such as acetylene black, furnace black, and channel black are added to resin compositions such as polyamide, polyimide, polyvinylidene fluoride, ethylene tetrafluoroethylene copolymer, polycarbonate, and polyester. Then, by forming this to a thickness of several tens to several hundreds of micrometers, a belt set to a predetermined electrical resistivity (surface resistivity, volume resistivity) is used as an intermediate transfer belt, paper transport and toner transfer. It is known that a transfer belt that also serves as a transfer belt is obtained (Japanese Patent Laid-Open Nos. 63-111267, 5-170946, 6-228335, etc.).
[0013]
In addition, the following methods are considered as a manufacturing method of an endless belt.
[0014]
(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). This method is mainly used for manufacturing a polyimide transfer belt.
[0015]
(ii) Extrusion molding method This is a method in which a resin compounded with a conductive material is melt-extruded in a ring shape. This method is mainly used in a method for producing an ethylenetetrafluoroethylene copolymer, polyvinylidene fluoride, polycarbonate-based, polyester-based, or polyimide-based transfer belt.
[0016]
(iii) Dipping method In this method, a 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. This method is mainly used for producing a transfer film made of polyvinylidene fluoride.
[0017]
(iv) Rubber Extrusion Method A method has been reported in which polyurethane rubber is extruded and vulcanized into a cylindrical shape, and then the surface is polished and the surface of the outer layer is coated with a fluororesin or the like (Electrophotographic Society Journal 33 (1) 43 ( 1994)).
[0018]
Conventionally, as such a conductive endless belt, one formed by blending a thermosetting resin or a thermoplastic resin with a conductive material such as carbon black has been mainly used. Among them, those mainly composed of a thermoplastic resin are easy to continuously form and have been widely used.
[0019]
Especially in the field of molded members using thermoplastic ester resins as thermoplastic resins, it is possible to finely disperse two or more thermoplastic ester resins by promoting transesterification (copolymerization). It has been reported. However, in the conventional technology, when transesterification (copolymerization) is promoted, generation of a low molecular weight product by depolymerization proceeds, resulting in foaming of the resulting molded member, or molecular chain scission. Thus, there are problems such as a decrease in mechanical properties of the molded member due to a decrease in molecular weight (such as a decrease in tensile elongation at break), and fine dispersion of the resin by promoting transesterification has not been put into practical use.
[0020]
For this reason, the present condition is that the molded member which prevented the physical-property fall by suppressing transesterification reaction is actually used as a practical product.
[0021]
[Problems to be solved by the invention]
The present invention solves the above-mentioned conventional problem of deterioration of physical properties, uses a thermoplastic amorphous resin, and uses a molded member having excellent physical properties such as bending resistance and molding dimensional stability, an endless belt, and the endless belt. Provided are image forming apparatus belts such as intermediate transfer belts, conveyance transfer belts, and photoreceptor belts used in electrophotographic copying machines, laser beam printers, facsimile machines, and the like, and image forming apparatuses including the image forming apparatus belts. The purpose is to do.
[0022]
[Means for Solving the Problems]
The molded member of the present invention is formed by heating and mixing a thermoplastic amorphous resin having an ester bond, a reaction catalyst, a conductive material for adjusting electric resistance, and a chelator, and carbon black as a conductive material. Is contained in an amount of 1 to 50% by weight.
[0023]
That is, as a result of intensive studies to achieve the above object, the present inventors paid attention to a thermoplastic amorphous resin having an ester bond that has been widely used in the past, and for its copolymerization and high molecular weight. When the reaction catalyst and chelator are heated and kneaded, it is possible to stably obtain a molded member having undergone copolymerization or high molecular weight by transesterification reaction, etc. without being affected by molding conditions. The present inventors have found that physical properties such as bending resistance are superior to molded members obtained by the suppressed method, and that there is almost no problem of deterioration of mechanical properties even when a conductive material is blended.
[0024]
In the present invention, the reaction catalyst is preferably a titanium (Ti) compound, and alkyl titanate is particularly preferable among them. There is no restriction | limiting in particular as a chelator to add, Although a well-known chelator can be used, A phosphorus (P) type compound is preferable among these.
[0025]
In the present invention, polyesters such as polycarbonate (hereinafter abbreviated as “PC”) and polyarylate (hereinafter abbreviated as “PAr”) are suitable as the thermoplastic amorphous resin having an ester bond.
[0027]
The endless belt of the present invention is composed of such a molded member of the present invention. When the conductive material is contained, the surface resistivity is 1 to 10 ¹⁶ Ω, and the endless belt is in one endless belt. Preferably, the maximum value of the resistivity is not more than 100 times the minimum value.
[0028]
The belt for an image forming apparatus of the present invention is an intermediate transfer belt, a transfer transfer belt, or a photosensitive belt made of this conductive endless belt.
[0029]
The image forming apparatus of the present invention is provided with this image forming apparatus belt.
[0030]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail.
[0031]
First, each compounding component of the molding raw material in the present invention and its compounding ratio will be described.
[0032]
(Thermoplastic amorphous resin having an ester bond)
The thermoplastic amorphous resin used in the present invention may be any thermoplastic amorphous resin having an ester bond, such as a polyester having an ester bond in the main chain or an amorphous high resin having an ester bond in the side chain. Molecule. The thermoplastic amorphous resin used in the present invention refers to those having a crystallinity of 0% or more and less than 10%.
[0033]
Specifically, polyesters such as PC (polycarbonate) and PAr (polyarylate), and resins having ester bonds in the side chains such as PMMA (polymethyl methacrylate) can be given as suitable examples. Of these, polyester is preferable.
[0034]
Moreover, a copolymerization component can also be introduce | transduced in the thermoplastic amorphous resin used for this invention in the range which does not impair the effect of this invention remarkably. Specific examples include those having an ester bond as a main chain and an ester bond such as polymethylene glycol introduced therein.
[0035]
The molecular weight of the thermoplastic amorphous resin used in the present invention is not particularly limited. For example, a resin having a general molecular weight of about 10,000 to 100,000 in weight average molecular weight can be used. When there is a demand for high mechanical properties, high molecular weight materials are preferred. In this case, the molecular weight is preferably 20,000 or more, more preferably 25,000 or more, and particularly preferably 30,000 or more.
[0036]
In the present invention, one type of thermoplastic amorphous resin having such an ester bond may be used alone, or two or more types may be mixed and used.
[0037]
Further, a thermoplastic amorphous resin having an ester bond and a thermoplastic resin having a functional group capable of reacting with the ester component by a reaction catalyst can also be used. Examples of functional groups in this case include a hydroxyl group and a carboxyl group.
[0038]
(Reaction catalyst)
The reaction catalyst is not particularly limited as long as it has an ability to catalyze the reaction of the ester bond contained in the thermoplastic amorphous resin. Specifically, a polyester polymerization catalyst having an ability to condense an organic acid and a hydroxyl group can be used.
[0039]
Of the reaction catalysts, Ti (titanium) compounds are preferred, and alkyl titanates are particularly preferred because of their high activity. 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).
[0040]
In addition, the Ti-based reaction 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 use an Mg (magnesium) -containing compound in combination.
[0041]
The compound containing Mg (magnesium) is not particularly limited, but an organic acid magnesium salt is preferable, and magnesium acetate is particularly preferable. The amount used is preferably 2/8 to 8/2 in terms of the weight ratio Mg / Ti of the Mg element of the Mg-containing compound to the Ti element of the Ti-based compound, and particularly preferably about 5/5.
[0042]
As the content of the reaction catalyst in the molding material, if it is too small, it may not work effectively. Therefore, it is preferable that the content is large to some extent, and the weight of metal in the reaction catalyst is 1 ppm or more with respect to the total weight of the molding material. Preferably, it is more preferably 10 ppm or more, and particularly preferably 20 ppm or more. On the other hand, since ester resins may cause depolymerization in the presence of a large amount of heavy metals, the content of the reaction catalyst is preferably not too much, and the weight of the metal in the reaction catalyst is relative to the total weight of the molding raw material. It is preferably 10,000 ppm or less, more preferably 1000 ppm or less, and particularly preferably 500 ppm or less. In the following, the weight ratio of the Ti element of the Ti compound as the reaction catalyst to the total weight of the forming raw material may be referred to as “Ti concentration”.
[0043]
(Chelator)
If the activity of the reaction 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 substance may cause problems.
[0044]
Therefore, in the present invention, depolymerization is suppressed by using a chelator having the ability to chelate the metal in the reaction catalyst.
[0045]
There is no restriction | limiting in particular as a kind of chelator, A well-known chelator can be used.
[0046]
Examples include P-based compounds such as phosphites, phosphates, phosphates, and hydrazines, such as Irgafos 168 (manufactured by Nippon Ciba Geigy Co., Ltd.), PEP36 (Asahi Denka Kogyo Co., Ltd.). ), Sandstub P-EPQ (Clariant Japan Co., Ltd.), phosphite ester, IRGANOXMD1024 (Nihon Ciba Geigy Co., Ltd.), CDA-6 (Asahi Denka Kogyo Co., Ltd.) hydrazines Etc. can be easily obtained from the market. Among these, P-based compounds are particularly preferable.
[0047]
The P-type compound as a chelator will be described in detail below.
[0048]
A reaction catalyst such as a Ti-based compound is effective as a catalyst for copolymerization or high molecular weight, but also promotes depolymerization as a side reaction, and if the activity is too high, depolymerization may have priority. In the present invention, a P-based compound blended as a chelator coordinates to Ti of a Ti-based compound as a reaction catalyst. Thereby, the reaction regularity as a catalyst becomes high, depolymerization of a side reaction can be suppressed, and copolymerization and high molecular weight can be accelerated | stimulated.
[0049]
Examples of the P-based compound include one or more selected from the group consisting of phosphoric acid, phosphate, phosphate ester, phosphorous acid, phosphite, and phosphite.
[0050]
The phosphate and phosphite are not particularly limited as long as they are metal salts, but alkali metal salts or alkaline earth metal salts are preferred.
[0051]
Examples of the phosphate ester include those represented by the following general formula (I).
[0052]
[Chemical 1]

[0053]
(In the formula (I), R ¹ , R ² and R ³ are each independently hydrogen, an alkyl group or an aryl group having 1 to 20 carbon atoms, Z is a single bond or an oxygen atom, and at least one of them is an oxygen atom. .)
[0054]
Specific examples of the phosphate ester include triethyl phosphate, tributyl phosphate, and triphenyl phosphate.
[0055]
Examples of the phosphite include those represented by the following general formulas (II) to (IV).
[0056]
[Chemical formula 2]

[0057]
(In the formula (II), R ⁴ , R ⁵ and R ⁶ each independently represents an alkyl group having 1 to 20 carbon atoms, an aryl group, a cycloalkyl group, an aralkyl group or an alkylaryl group, and Z represents a single bond or (At least one of the oxygen atoms is an oxygen atom.)
[0058]
Specific examples thereof include triethyl phosphite, tributyl phosphite, tris (2-ethylhexyl) phosphite, tridecyl phosphite, tristearyl phosphite, triphenyl phosphite, tricresyl phosphite, tris (nonylphenyl) phosphine. Phyto, tris (2,4-di-t-butylphenyl) phosphite, decyl-diphenyl phosphite, phenyl-di-2-ethylhexyl phosphite, phenyl-didecyl phosphite, tris (biphenyl) phosphite, tricyclohexyl A phosphite etc. are mentioned.
[0059]
[Chemical 3]

[0060]
(In the formula (III), R ⁷ , R ⁸ , R ⁹ and R ¹⁰ each independently belong to the definition of R ⁴ , R ⁵ and R ^{6 in} the formula (II), and Z is a formula in the formula (II) (Y is an alkylene group having 1 to 30 carbon atoms, an arylene group, a cycloalkylene group, an aralkylene group, or an alkylarylene group.)
[0061]
Specific examples thereof include tetraphenyl-4,4′-isopropylidene-diphenol diphosphite, tetratridecyl-4,4′-isopropylidene-diphenol diphosphite, tetratridecyl-4,4′-. Examples include butylidenebis (3-methyl-6-tert-butylphenol) diphosphite, tetrakis (2,4-di-tert-butylphenyl-4,4′-biphenylene) phosphite, and the like.
[0062]
[Formula 4]

[0063]
(In the formula (IV), R ¹¹ is an alkyl group having 1 to 30 carbon atoms, an aryl group, a cycloalkyl group, an aralkyl group or an alkylaryl group, and R ¹² is an alkylene group having 1 to 20 carbon atoms, Z has the same definition as Z in formula (II).)
[0064]
Specific examples thereof include bis (stearyl) pentaerythritol diphosphite, bis (2,6-di-t-butylphenyl) pentaerythritol diphosphite, bis (nonylphenyl) pentaerythritol diphosphite, and the like.
[0065]
Among the various compounds described above, tributyl phosphite, triphenyl phosphite, bis (stearyl) pentaerythritol diphosphite, and bis (2,6-di-t-butylphenyl) pentaerythritol diphosphite are particularly preferable.
[0066]
The amount of chelator varies depending on the amount of the reaction catalyst contained and is not particularly defined. However, if it is small, the addition effect as a reaction inhibitor is hardly exhibited, and the effect is remarkably exhibited when a certain concentration is exceeded. Therefore, in the present invention, the element weight of the chelator chelating to the metal of the reaction catalyst in the forming raw material is preferably 10 ppm or more, more preferably 50 ppm or more, and particularly preferably 100 ppm or more. If the compounding amount of the chelator is too large, the activity of the reaction catalyst is lost, and a good molded member cannot be obtained. And Hereinafter, the weight ratio of the element chelating to the metal of the reaction catalyst of the chelator relative to the total weight of the forming raw material may be referred to as “chelate element concentration”.
[0067]
(Conductive substance)
In the present invention, a conductive substance is blended in order to adjust the electric resistance value of the molded member. In particular, in endless belts used in image forming apparatuses, it is necessary to adjust the surface resistance value and volume resistance value according to the application in order to electrically adsorb and transfer toner and paper. Add a sex substance.
[0068]
As the conductive material to be blended, carbon black having excellent dispersibility is used.
[0070]
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. Further, those having a primary particle diameter of 10 to 100 nm, a specific surface area of 10 to 200 m ² / g, and a pH value of 3 to 11 are more preferable.
[0071]
Moreover, the carbon black to be used may be one type, or two or more 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 treatment, or carbon black subjected to acid treatment is used as the carbon black.
[0072]
Also, silane for the purpose of improving the dispersibility of the conductive material, aluminate, titanate, or may be used carbon black click treated with a coupling agent zirconate like.
[0073]
As the compounding amount of the conductive material, the resistance value that is expressed varies depending on the physical properties of the conductive material to be used. Therefore, it is necessary to determine the conductive material concentration at which the desired resistance value is obtained. In the present invention, the proportion of carbon black click in the molded member (hereinafter for example, sometimes referred to as "carbon black concentration.") Is 1 to 50 wt%, preferably 1 to 30% by weight, particularly preferably 1 -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 .
[0074]
(Additional ingredients; optional ingredients)
Arbitrary compounding components can be blended in the molding material of the molding member of the present invention according to various purposes.
[0075]
Specifically, antioxidants such as Irganox 1010 (trade name) manufactured by Ciba Geigy Japan, heat stabilizers, various plasticizers, light stabilizers, ultraviolet absorbers, neutralizers, lubricants, antifogging agents, antiblocking agents. Various additives such as an agent, a slip agent, a crosslinking agent, a crosslinking aid, a colorant, a flame retardant, and a dispersant can be added.
[0076]
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.
[0077]
The thermoplastic resin as an additional component is polypropylene, polyethylene (high density, medium density, low density, linear low density), propylene ethylene block or random copolymer, rubber or latex component such as ethylene / propylene copolymer Rubber, styrene / butadiene rubber, styrene / butadiene / styrene block copolymer or hydrogenated derivatives thereof, polybutadiene, polyisobutylene, polyamide, polyamideimide, polyacetal, polyarylate, polycarbonate, polyimide, liquid crystalline polyester, polysulfone, polyphenylene Sulfide, polybisamide triazole, polyether imide, polyether ether ketone, acrylic, polyfluorinated vinylidene, polyfluorinated vinyl, chlorotrifluoroethylene, ethylene Rentetrafluoroethylene copolymer, hexafluoropropylene, perfluoroalkyl vinyl ether copolymer, alkyl acrylate ester copolymer, polyester ester copolymer, polyether ester copolymer, polyether amide copolymer, polyurethane copolymer What consists of 1 type, such as a polymer, or these 2 or more types of mixtures can be used.
[0078]
As a thermosetting resin, what consists of 1 type, such as an epoxy resin, a melamine resin, a phenol resin, an unsaturated polyester resin, or these 2 or more types of mixtures can be used, for example.
[0079]
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, graphite, metal powder, conductive metal oxide, organometallic compound, organic In addition to fillers such as metal salts, additives such as antioxidants (phenolic, sulfur, phosphate ester, etc.), lubricants, various organic and inorganic pigments, UV inhibitors, antistatic agents, dispersants, neutralization Agents, foaming agents, plasticizers, copper damage inhibitors, flame retardants, crosslinking agents, flowability improvers and the like.
[0080]
Next, the heat kneading, molding, heat treatment method, physical properties of the molded product, application, etc. in the present invention will be described.
[0081]
(Heat kneading, molding, heat treatment)
In the present invention, the molded member may be molded after heating and kneading the thermoplastic amorphous resin, reaction catalyst, chelator and the above-mentioned additional compounding material added as necessary to obtain a resin composition. The molded member may be molded as it is by heating and kneading the plastic amorphous resin, the reaction catalyst, the chelator and the additional compounding material added as necessary. In this heat-kneading, since a molded member having better physical properties may be obtained by drying the raw material in advance, the raw material drying treatment prior to the heat-kneading is effective.
[0082]
There is no restriction | limiting in particular in the means of heat kneading, A well-known technique can be used. For example, if the molding raw material is first 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 an endless belt from the resin composition thus obtained, a known technique can be used. For example, it can be molded according to a conventional method using an injection molding machine, an extrusion molding machine or the like.
[0083]
By heat-treating the molded member thus obtained, a molded member with improved physical properties can be obtained. In this case, the heat treatment conditions are usually 60 to 200 ° C., preferably 70 to 120 ° C. for 5 to 60 minutes, preferably about 10 to 30 minutes, although depending on the raw material resin used. By performing such a heat treatment, an improvement in the number of folding resistances and a tensile elastic modulus, which will be described later, can be seen in an endless belt.
[0084]
(Use of the molded member of the present invention)
There is no restriction | limiting in particular in the use of the shaping | molding member of this invention, It can use widely as a structural component of OA equipment, a functional member, a vehicle exterior component, interior material, a structural member of household appliances, a general purpose film, etc.
[0085]
In particular, it can be suitably used in the field of office automation equipment, which requires strict physical properties such as bending resistance, especially for functional members. When used as an intermediate transfer belt, a transfer transfer belt, a photoreceptor belt, etc., it is preferable because there are few problems such as cracking and elongation.
[0086]
Below, the endless belt as an example of the suitable usage example of the shaping | molding member of this invention is demonstrated.
[0087]
(Endless belt)
In order to obtain the endless belt of the present invention, the above-described thermoplastic amorphous resin, reaction catalyst, chelator and other additional components blended as necessary are mixed by, for example, a twin-screw kneading extruder and pelletized. A method of forming an endless belt is particularly preferably used.
[0088]
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.
[0089]
In addition, an endless 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.
[0090]
(Physical properties of endless belt)
According to the present invention, an endless belt having the following physical properties can be obtained.
[0091]
-Folding resistance When using the endless belt of the present invention in an image forming apparatus as an intermediate transfer belt, for example, if the bending resistance is poor, cracks occur and images cannot be obtained. preferable.
[0092]
The degree of bending resistance can be quantitatively evaluated by following the method for measuring the folding endurance of JIS P-8115, and it is judged that an endless belt with a higher folding endurance is less susceptible to cracking and has superior bending resistance. be able to.
[0093]
As a specific numerical value, if it is 500 times or more, it can be used by exhibiting the function as an endless belt, but it is practically 5000 times or more, more preferably 10,000 times or more, and more preferably 30000. If it is more than the number of times, it is particularly preferable because cracks are hardly generated.
[0094]
-Tensile elastic modulus If the tensile elastic modulus of the endless belt is low, for example, when it is used as an intermediate transfer belt in an image forming apparatus, a slight elongation may occur due to the tension, which may cause problems such as color misregistration. Is higher, specifically 1000 MPa or more, more preferably 1500 MPa or more, further preferably 2000 MPa or more, and if it is 2500 MPa or more, it is possible to significantly suppress problems such as color misalignment. preferable.
[0095]
-Surface resistivity In the endless belt of this invention, electroconductivity can be acquired by mix | blending carbon black as an electroconductive substance. The resistance region of the endless belt varies depending on the purpose, but is preferably selected from the range of surface resistivity of 1 to 1 × 10 ¹⁶ Ω.
[0096]
The more preferable range of the surface resistivity varies depending on the application. For example, when used as a photoreceptor belt, the surface resistivity is as low as 1 to 1 × 10 ⁶ Ω so that the charge on the outer surface can escape to the inner surface as necessary. 1 × 10 ⁶ to 1 × 10 ¹¹ Ω, which can be easily charged and transferred when used as an intermediate transfer belt, is preferable, and when used as a transfer transfer belt, it is easy to be charged and is not easily damaged even at a high voltage. A high region of 10 ¹⁰ to 1 × 10 ¹⁶ Ω is preferable.
[0097]
Further, it is preferable that the distribution of the surface resistivity in one endless belt is narrow, and in each preferable surface resistivity region, the maximum value in one belt is preferably within 100 times the minimum value, and within 10 times. It is particularly preferred that
[0098]
The surface resistivity of the endless belt can be easily measured by, for example, Hiresta, Loresta manufactured by Dia Instruments Co., Ltd. or R8340A manufactured by Advantest Co., Ltd.
[0099]
-Thickness of endless belt The thickness of the endless belt is preferably 50 to 1000 µm, more preferably 80 to 500 µm, and particularly preferably 100 to 200 µm.
[0100]
(Use of endless belt)
When the endless 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, there are few problems such as cracking and elongation, It can be used stably over a long period of time.
[0101]
【Example】
Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples.
[0102]
In the following examples and comparative examples, endless belts were produced with the following raw materials and molding conditions, evaluated, and the results are shown in Table 1.
[0103]
(material)
The raw materials were as follows, and the mixing ratio was as shown in Table 1.
[0104]
[Thermoplastic amorphous resin]
PC (weight average molecular weight 28,000; PS-converted weight average molecular weight 64,000)
PAr (weight average molecular weight 30,000; PS-converted weight average molecular weight 69,000)
[0105]
[Reaction catalyst]
Ti compounds (titanium (IV) butoxide)
[0106]
[Killator]
P-based compound (sand stub P-EPQ: tetrakis (2,4-ditertiarybutylphenyl) 4,4′-biphenylylene diphosphonite (structural formula is as follows); manufactured by Clariant Japan Co., Ltd.)
Hydrazines (IRGANOX MD1024; manufactured by Nippon Ciba Geigy Co., Ltd.)
[0107]
[Chemical formula 5]

[0108]
[Conductive substance]
Carbon black (Denka Black; manufactured by Electrochemical Co., Ltd.)
[0109]
(Heat kneading)
Each raw material was melt-mixed using a twin-screw kneading extruder (PMT32 manufactured by IKG Corporation) to pelletize the resin composition.
[0110]
(Endless belt molding method)
This material pellet was dried at 130 ° C. for 8 hours, extruded in a molten tube state below the annular die by an extruder with a diameter of 180 mm and a lip width of 1 mm and a 6-thread spiral annular die, and the extruded molten tube was Next, it is installed on the outside of the core installed in the seamless belt while contacting the outer surface of the cooling mandrel with an outer diameter of 170 mm mounted on the same axis as the support rod and allowing it to cool and solidify. With a roll, the seamless belt is drawn in a cylindrical shape, and is cut into a length of 340 mm. Endless belt. In addition, in order to evaluate the residence time dependency of the physical properties of the endless belt, the residence time was adjusted and molding was performed under the following two conditions.
[0111]
Condition A: Targeting a residence time of 12 minutes and a thickness of 150 μm and adjusting the thickness range to be ± 15 μm and molding condition B; Targeting a residence time of 24 minutes and a thickness of 150 μm and a thickness range of ± 15 μm Adjust and mold as follows
Under this condition B, molding was performed by slowing the screw rotation so that the residence time was longer than in condition A, and the take-up speed was also adjusted so that the belt thickness was the same as that in condition A.
[0113]
(Evaluation)
The evaluation was carried out by cutting the endless belt into an appropriate size as necessary.
[0114]
-Fold resistance times Measured three times for each sample in accordance with JIS P-8115, and the average value (2 significant digits) was used as the representative value. The number of folding resistances is an index of bending fatigue resistance, and the larger the number, the harder it is to break and the stronger it is.
[0115]
-Thickness Measured at a pitch of 20 mm in the circumferential direction of the seamless belt using a micrometer manufactured by Tokyo Seimitsu Co., Ltd.
[0116]
・ Surface resistivity Since the area where the surface resistivity can be suitably measured differs depending on the measuring instrument, it was properly used as follows. The measurement time was 10 seconds, and the measurement was performed at a pitch of 20 mm in the circumferential direction of the endless belt.
[0117]
Samples with 1 to 10 ⁶ Ω: Loresta (trade name) manufactured by Dia Instruments Co., Ltd.
Samples with 10 ⁶ to 10 ¹³ Ω: Hiresta (HA terminal) (trade name) (applied voltage: 500 V) manufactured by Dia Instruments Co., Ltd.
Sample to be 10 ¹³ to 10 ¹⁶ Ω: R8340A (trade name) (JIS electrode) (applied voltage 500V) manufactured by Advantest Corporation
[0118]
Comparative Example 1
First, an endless belt was molded by adjusting the surface resistivity to about 10 ⁹ Ω under molding condition A with the composition shown in Table 1. This endless belt having a surface resistivity can be suitably used as an intermediate transfer belt.
[0119]
In Comparative Example 1, since no Ti-based compound was blended, it is considered that no copolymerization or high molecular weight reaction occurred. The resulting molded member had a folding endurance of 250 times. Also, under the molding condition B, an endless belt having substantially the same physical properties as the condition A product could be obtained.
[0120]
When the endless belt of this comparative example was mounted on an image forming apparatus as an intermediate transfer belt, a good initial image was obtained. Further, the image output was continued continuously. However, when about 3000 sheets were output, a crack occurred in the endless belt, and the image could not be output.
[0121]
The present resin composition pellets can be said to be a preferable material in terms of being thermally stable and easy to handle because the physical properties of the belt do not change much even if the molding conditions change somewhat. However, since the folding endurance is about 250, the initial physical properties as an intermediate transfer belt have no practical performance, and it can be said that the physical properties are quite insufficient.
[0122]
Comparative Example 2
Based on the formulation of Comparative Example 1, a Ti compound was blended with a Ti concentration of 98 ppm. Attempts were made to mold an endless belt with the obtained pellets, but the resin exiting from the die exit was severely deteriorated in both conditions A and B, and the resin was drawn down, so that an endless belt could not be obtained.
[0123]
This is presumably because the Ti-based compound acted as a catalyst for depolymerization as well as copolymerization and high molecular weight, and the depolymerization was prioritized under the conditions of this Comparative Example 2.
[0124]
Comparative Example 3
Comparative Example 1 was used as a basic blend, and 0.5 part by weight of a P-based compound as a chelator was blended.
[0125]
In Comparative Example 3, since no Ti-based compound was blended as in Comparative Example 1, it is considered that no copolymerization or high molecular weight reaction occurred. The obtained molded member had a folding resistance of 270 times. Also, under the molding condition B, an endless belt having substantially the same physical properties as the condition A product could be obtained.
[0126]
However, since the number of folding times is low, the initial physical properties of the intermediate transfer belt as in Comparative Example 1 do not have practical performance, and it can be said that the physical properties are quite insufficient.
[0127]
Example 1
Based on the formulation of Comparative Example 3, a Ti compound was further blended with a Ti concentration of 69 ppm.
[0128]
As a result, a good endless belt can be obtained under both molding conditions A and B. In particular, under condition A, the folding endurance was 13,000 times, which was a very high value.
[0129]
In Example 1, an endless belt having stable and good physical properties could be obtained even when the molding conditions were changed. This is because the P-based compound is coordinated to the Ti-based compound, so that the reaction selectivity as a catalyst is enhanced, and an endless belt having high physical properties can be stably obtained even if the molding conditions are changed. Conceivable.
[0130]
Example 2
Based on the composition of Example 1, the compounding amounts of the Ti compound and the P compound were further increased.
[0131]
As a result, a good endless belt having a higher folding resistance than that of Example 1 could be stably obtained.
[0132]
When the endless belt of Example 2 was mounted on an image forming apparatus as an intermediate transfer belt, a good initial image was obtained. Further, the image output was continued continuously, but no cracks were generated on the endless belt even when about 100,000 sheets, which is the target life of the image forming apparatus, were output. In addition, the folding performance is high, and even if it is used as an intermediate transfer belt, it satisfies the initial physical properties and can be used continuously over a long period of time.
[0133]
Example 3
Based on the composition of Example 2, the carbon black concentration was lowered to obtain an endless belt having a surface resistivity of about 10 ¹² Ω. This endless belt can be suitably used as a conveyance transfer belt.
[0134]
Example 4
Based on the composition of Example 3, the carbon black concentration was increased to obtain an endless belt having a surface resistivity of about 10 ⁴ Ω. This endless belt can be suitably used as a base material for a photoreceptor belt.
[0135]
Example 5
Based on the composition of Example 2, 1 part by weight of hydrazine was used as a chelator instead of the P-based compound to obtain an endless belt.
[0136]
Also in Examples 3 to 5, a good endless belt having a high folding resistance could be stably obtained.
[0137]
[Table 1]

[0138]
【The invention's effect】
As is clear from the above examples and comparative examples, according to the present invention, thermoplastic amorphous properties such as endless belts, which are excellent in bending resistance, molding dimensional stability, etc., and suppressed physical property deterioration due to reaction during melt mixing. A resin molded member, an image forming apparatus belt using the endless belt, and an image forming apparatus using the image forming apparatus belt are provided.
[Brief description of the drawings]
FIG. 1 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 endless belt 7, 8, 9 Conveying roller

Claims (7)

A thermoplastic amorphous resin having an ester bond, a reaction catalyst, a conductive substance for adjusting electric resistance, and a chelator are mixed by heating and molded, and contains 1 to 50% by weight of carbon black as a conductive substance. A molded member characterized by:   The molded member according to claim 1, wherein the reaction catalyst is a titanium-based compound.   The molded member according to claim 2, wherein the reaction catalyst is an alkyl titanate.   The molded member according to any one of claims 1 to 3, wherein the chelator is a phosphorus compound. An endless belt comprising the molded member according to any one of claims 1 to 4 . A belt for an image forming apparatus, which is an intermediate transfer belt for an image forming apparatus, a transfer transfer belt, or a photosensitive belt, comprising the endless belt according to claim 5 . An image forming apparatus comprising the belt for an image forming apparatus according to claim 6 .

Images