JP3736347B2 - Molded member - Google Patents

Description

【００８２】
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。
【００８３】
【化２】

【００８４】
（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。
【００８５】
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。
【００８６】
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。
【００８７】
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。
【００８８】
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。
【００８９】
【化３】

【００９０】
（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、得られる成形部材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。
【００９１】
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。
【００９２】
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。
【００９３】
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１６時間溶解し、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。
【００９４】
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
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。
【００９５】
本手法でした、結晶性樹脂と、非晶性樹脂と、重合触媒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、
【００９６】
【数２】

であることが好ましく、
【００９７】
【数３】

【００９８】
であるとさらに好ましく、
【００９９】
【数４】

【０１００】
であると、十分に高い物性を得られるので特に好ましい。
【０１０１】
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。
【０１０２】
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。
【０１０３】
（ＤＳＣによる融解ピーク特性）
本発明では、ＤＳＣによる１回目の昇温による融解ピークを示すピーク温度と冷却後２回目の昇温による融解ピークを示すピーク温度との差が３０℃以下である。
【０１０４】
上記ピークは、成形部材が経時的に変化する状態であるのかどうか（未反応状態である部分が残っているかどうか）を示す指標となり、このピーク差が大きいと、エンドレスベルトは経時による寸法、機械物性等の経時変化が大きいと考えられるため好ましくない。
【０１０５】
好ましいピーク温度差は２０℃以下であり１０℃以下が特に好ましい。
【０１０６】
常温下でいくら耐久性、引張り弾性率等の機械物性が良くても経時的に変化しては部品として使用できるものではないため、上記手法による融解ピーク差がある特定範囲に入っていることが重要である。
【０１０７】
（アロイ構造）
本発明の成形部材は、海島構造を有するアロイ構造である。特に結晶成分と非結晶成分をアロイ化した構造やフィラー等を添加した構成の場合、加熱溶融した高分子材料は、冷却過程において構造が変化する場合がある。例えば、急激に冷却したり、フィラー等の存在下では本来結晶化すべき材料が結晶化しきれずに非晶状態で残る場合があるため、一旦成形された成形部材は、高温にさらされると再度結晶化を進行させることがあり、著しく小さく収縮したり、機械強度が極度に低下したりする場合があるため注意する必要がある。
【０１０８】
このような状態を阻止するためには、アロイ化する成分のうち結晶成分の材料においては成形部材として結晶化させた状態の構造をとる必要がある。
【０１０９】
このような海島構造は、四酸化ルテニウムで２分以上染色した超薄切片を透過型電子顕微鏡写真にて観察した状態にて観察される。
【０１１０】
本発明の成形部材では、少なくとも海島構造を有している部分が確認されかつ特定の弾性率、耐折れ強度を有するものが好ましい。
【０１１１】
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。
【０１１２】
（熱処理）
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。
【０１１３】
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。
【０１１４】
熱処理を施すことにより、特に後述するエンドレスベルトとした場合等において、耐折回数や引張弾性率の向上が見られる。
【０１１５】
（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。
【０１１６】
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。
【０１１７】
（エンドレスベルト）
本発明の成形部材の好適な使用例の一例としてエンドレスベルトをあげることができる。
【０１１８】
エンド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。
【０１１９】
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。
【０１２０】
また、この成形時の温度，滞留時間適正化により、より良好な物性の成形部材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。
【０１２１】
（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。
【０１２２】
・物性；耐折回数
本発明に用いる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エンドレスベルトが好ましい。
【０１２３】
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。
【０１２４】
具体的な数値としては、５００回以上あれば一応エンドレスベルトとして機能を発揮して使用することができ、実用的には５０００回以上が好ましいが、本発明では１００００回以上である。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。
【０１２５】
・物性；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。
【０１２６】
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。
【０１２７】
・物性；引張弾性率温度特性
引張弾性率の温度特性としては、４０℃で引張弾性率が５℃での引張弾性率に対し６０％以上であり、６０℃での引張弾性率が５℃での引張弾性率に対し２０％以上であることが重要である。言い換えると５℃〜４０℃間では、引張弾性率の変化は少なく、４０〜６０℃の間では、適度に低下することが好ましい。
【０１２８】
４０℃での引張弾性率が５℃での引張弾性率に対し６０％未満であると、夏場あるいは高温条件下でのプリンタや複写機等使用時にベルトが伸びてしまい画像がずれたり、クリープ変形しやすくなったりする。好ましくは、４０℃での引張弾性率が５℃での引張弾性率に対し７０％以上であり、更に好ましくは８０％以上である。
【０１２９】
また、６０℃での引張弾性率が５℃での引張弾性率に対し２０％以上であることが重要である。６０℃での引張弾性率が５℃での引張弾性率に対し２０％未満ならば、数日〜数年にかけての経時的にベルトのクリープ、寸法変化が発生し易いため好ましくない。
【０１３０】
特に好ましくは、６０℃での引張弾性率が５℃での引張弾性率に対し４０％以上であり、更に好ましくは６０％以上である。
【０１３１】
・物性；表面抵抗率
本発明に用いるエンドレスベルトは必要に応じて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。
【０１３２】
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。
【０１３３】
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。
【０１３４】
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。
【０１３５】
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。
【０１３６】
・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。
【０１３７】
・エンドレスベルトの用途
このエンドレスベルトの用途に特に制限はないが、例えば電子写真の中間転写ベルト，搬送転写ベルト，感光体ベルトなどとして好適に用いることができる。
【０１３８】
【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。
【０１３９】
（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
熱安定剤；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
（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。
【０１４０】
（エンド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表１記載の所定の厚み、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ベルトとした。
【０１４１】
成形温度，滞留時間などの条件は表１の通りとした。
【０１４２】
（評価）
評価は必要に応じ、エンドレスベルトを必要な大きさに切り開いて実施した。
・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。
・耐折回数
ＪＩＳＰ−８１１５に準拠し、試験片を幅１５ｍｍ、長さ１００ｍｍの大きさに切断し、ＭＩＴ試験機にて折り曲げ速度１７５回／分、回転角度１３５°左右、引張り荷重１．５ｋｇｆの条件にて破壊回数を測定した。
・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。
【０１４３】
表面抵抗率が１〜１×１０^６Ωとなるサンプルは、ダイヤインスツルメント（株）製 ロレスタを使用し、２０ｍｍピッチにてベルト円周方向を測定した。
【０１４４】
表面抵抗率が１０^６〜１×１０^１３Ωとなるサンプルは、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ピッチにてベルト円周方向を測定した。
【０１４５】
表面抵抗率が１０^１３〜１×１０^１６Ωとなるサンプルは、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。
【０１４６】
ＤＳＣ
セイコー電子工業（株）製ＳＳＣ−５２００（商品名）を使用し、昇温速度１０℃／ｍｉｎにて測定した。１つの試料を３００℃まで昇温させる第１回目のＤＳＣ測定した後、室温まで１０℃／ｍｉｎで冷却し、その後再度同一条件で第２回目のＤＳＣ測定を行い、１回目の融解ピーク温度と２回目の融解ピーク温度との差を求めた。
・厚み
東京精密（株）製のマイクロメータを用いてエンドレスベルトの円周方向２０ｍｍピッチにて測定した。
体積固有抵抗（Ω・ｃｍ）
高抵抗計ハイレスタＨＲＳプローブ（ダイヤインスツルメンツ（株）社製）を用い、測定電圧１００Ｖ、測定時間１０秒でエンドレスベルトの円周方向２０ｍｍピッチにて測定した。
・エンドレスベルトとしての耐久性の評価
得られたエンドレスベルトを中間転写ベルト、搬送転写ベルト或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エンドレスベルトにクラックあるいは画像ズレが発生するかを評価した。
【０１４７】
〔実施例１〜７〕
ＰＢＴ，ＰＣ，テトラブチルチタネート，酢酸マグネシウム，熱安定剤を事前に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。
【０１４８】
このときの加熱混練条件を表１に示すものとし、混練機内での反応は抑制するようにした。
【０１４９】
この材料ペレットを押出成形してエンドレスベルトを製造した。なお、この押出成形機内で反応が好ましい程度に促進し、エンドレスベルトが得られるように、表１に示す押出成形条件とした。
【０１５０】
表１にエンドレスベルトの形態、特性を示す。
【０１５１】
〔比較例１〕
重合触媒を用いなかったこと以外は実施例１と同じ条件でエンドレスベルトを製造した。
【０１５２】
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。
【０１５３】
〔比較例２〕
海島構造が生じないように混練条件、押出条件を選定した。表１の比較例２に示す条件とすることにより、ＰＢＴとＰＣとが均一に分散した非海島構造のエンドレスベルトを製造した。
【０１５４】
表１に比較例１，２のエンドレスベルトの形態、外観を示す。
【０１５５】
【表１】

【０１５６】
表１の通り、本発明例に係るエンドレスベルトは、いずれも広い温度範囲にわたって引張弾性率が高く、ベルト耐久性にも優れ、屈曲性が良好である。これに対し、重合触媒を添加しなかった比較例１では、６万枚でクラック及び画像ズレが生じ、耐屈曲性が不足する。比較例２は、重合触媒を添加してはいるものの、混練及び成形時の温度が高目に設定され非海島構造となっているために、１回目と２回目のＤＳＣ融解温度差が大きく、そのために高温域（６０℃）での引張弾性率が小さい。そして、この結果、６万枚の複写により、エンドレスベルトの伸びによる画像ズレが生じた。
【０１５７】
【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、広い温度範囲にわたって引張弾性率が高く、且つ耐屈曲性や耐薬品性及び成形寸法安定性に優れた成形部材が提供される。
【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。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a molded member having excellent physical properties such as molding dimensional stability and bending resistance. Specifically, all components used in engineering plastics, including OA equipment components, functional parts, automotive exterior parts and interior materials, home appliance components, films and resin composition pellets used to mold these. Regarding usage.
[0002]
[Prior art]
Conventionally, various thermoplastic resins have been used for constituent parts of OA equipment, functional members, exterior parts of automobiles, interior materials, constituent parts of home appliances, and the like.
[0003]
The required performance of these thermoplastic resins includes high elastic modulus, excellent flex resistance, excellent chemical resistance, high dimensional accuracy, and transparency depending on the application.
[0004]
Moreover, 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
[0005]
However, in many cases, it is required to have excellent bending resistance, chemical resistance, and molding dimensional stability.
[0006]
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.
[0007]
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, with conventional technology, when transesterification (copolymerization) is promoted, low molecular weight product generation due to depolymerization is accompanied by foaming of the molded member, or molecular chain scission proceeds to lower the molecular weight, resulting in the mechanical properties of the molded member. It has not practically been put to practical use for reasons such as a reduction (such as a decrease in tensile elongation at break).
[0008]
Actually, molded parts that prevent deterioration of physical properties by suppressing the transesterification reaction have been used as practical products, but those that are excellent in both elastic properties (high elastic modulus) and bending resistance have been provided. Absent.
[0009]
[Problems to be solved by the invention]
An object of the present invention is to provide a molded member having a high elastic modulus and excellent in bending resistance and molding dimensional stability.
[0010]
Another object of the present invention is to provide a molded member having excellent elastic properties (high elastic modulus) and bending resistance even under a wide range of temperature environments.
[0011]
[Means for Solving the Problems]
  The molded member of the present invention comprises a crystalline resin having at least one of a hydroxyl group, a carboxylic acid group and an ester bond, an amorphous resin having at least one of a hydroxyl group, a carboxylic acid group and an ester bond, and a polymerization catalyst. , Molded,The crystalline resin is PBT (polybutylene terephthalate), the amorphous resin is PC (polycarbonate),The molded resin has a sea-island structure, and the difference between the peak temperature indicating the melting peak due to the first temperature increase by DSC (differential scanning calorimetry) and the peak temperature indicating the melting peak due to the second temperature increase after cooling. Is 30 ° C. or less, and JIS P-8115 has a folding resistance of 10,000 times or more.
[0012]
As a result of intensive investigations for the above purpose, the present inventors have found that a crystalline resin, an amorphous resin, and a polymerization catalyst are heated and kneaded and a melting peak due to the first temperature increase by DSC (differential scanning calorimetry) is shown. The difference between the temperature and the peak temperature indicating the melting peak due to the second temperature rise after cooling is 30 ° C. or less, compared to the molded member obtained by the conventional method for suppressing the reaction such as transesterification, The inventors have found that physical properties such as molding dimensional stability and flex resistance are excellent, and have reached the present invention.
[0013]
In general, alloys of ordinary thermoplastic resins can be roughly divided into two types, compatible alloys and incompatible alloys.
[0014]
It is known that incompatible alloys, even if two types of thermoplastic resins are melt-mixed, they are not completely mixed and have a sea-island structure. If there is a large difference in the volume fraction between the two thermoplastic resins, the larger the volume fraction is, the smaller the volume fraction is at sea, and the smaller the volume fraction, the easier it is to form an island structure. Affects the island structure, and it is said that the smaller the melt viscosity is, the easier it is to the sea, and the larger is the island.
[0015]
In this incompatible alloy, there is always a boundary between sea-islands between different kinds of materials, so it is assumed that the interface is most likely to break and lowers the bending resistance. Therefore, the present inventors have speculated that the bending resistance of the molded member will be improved by reinforcing the interface by graft polymerization, block polymerization or the like.
[0016]
On the other hand, in the compatible alloy, there is no interface between different materials, and usually no sea-island structure is observed. It is said that such compatible materials have mechanical properties such as flex resistance that are in accordance with the blending ratio of both materials. Therefore, since it is unlikely that a dramatic improvement in bending resistance will be expected, the present inventors should greatly improve the mechanical properties represented by bending resistance if they are compatible and copolymerized. I thought.
[0017]
In other words, it was estimated that the mechanical properties such as the elastic modulus and the bending resistance of the thermoplastic resin alloy are improved by forming a copolymerized state in both incompatible and compatible alloyed materials.
[0018]
The inventor has paid attention to a polyester-based resin, which is a low price among thermoplastic resins.
[0019]
In general, it is known that an alloy of polyester resins undergoes mutual molecular cleavage called transesterification and exchanges with each other. In addition, this transesterification reaction is generally accompanied by molecular chain scission, and as a result, it is said that it causes foaming or brittleness and causes mechanical properties to deteriorate.
[0020]
However, the present inventors believe that a copolymerization reaction should also proceed simultaneously with this transesterification reaction, and if specific conditions are set, a decrease in mechanical properties due to molecular chain breakage or the like is suppressed. The materials, compound conditions, and molding conditions were examined on the assumption that the transesterification reaction could be further transferred to a copolymerization reaction.
[0021]
As a result, using polyester resin of the same composition, (1) one having a sea-island structure, (2) one having a sea-island structure but having a copolymerized interface, and (3) a sea-island structure It was found that some of them could not be seen, and the mechanical properties represented by the bending resistance were higher in (2) than in (1) and (3) than in (2). Furthermore, in the structure of (2) (interfacial copolymerized sea-island structure) or (3) (non-sea-island structure), there is almost no decrease in mechanical strength even when a third component such as a conductive filler is added. There was found.
[0022]
Furthermore, even when a conductive filler is added to obtain a specific electric resistance, the conductive filler is used as long as it has the structure (2) (interfacial copolymerized sea-island structure) or (3) (non-sea-island structure). Was fixed to the copolymerized resin component, so that it was found to be electrically stable and change little over time.
[0023]
Furthermore, the structures of (1) (sea island structure) and (2) (interfacial copolymerized sea island structure) that retain the sea-island structure of crystalline resin and non-crystalline resin are difficult to stretch in a wide range of temperature environments. It has been found that a high elastic modulus and a low creep are maintained even in a high-temperature environment or under a aging condition of several days to several years.
[0024]
That is, it has been found that the molded member of the present invention maintains high elasticity and low creep even under a heat history environment over a wide temperature range.
[0025]
In order to analyze the reason why this thermal history characteristic is excellent, the molded member of the present invention was analyzed by the thermal characteristics of the thermopolymer by differential scanning calorimetry (DSC). (In this thermal characteristic, by applying heat, we can capture the movement from macroscopic segmental motion to macroscopic motion of macromolecules, looking at micro Brownian motion at the glass transition point and folding motion at the melting point. ).
[0026]
In this DSC measurement, the temperature was first raised at a constant rate, then cooled at a constant rate, and further heated at a constant rate, and the endothermic peak point at the time of melting was measured. As a result, if the temperature difference between the melting peak point in the first heating process and the melting peak point in the second heating process is greater than 30 ° C., the amount of resin that has probably not been reacted yet remains. Therefore, it is recognized that the tensile elastic modulus is greatly reduced at high temperatures, and the belt may be stretched or deformed due to creep in a high temperature environment or over several days to several years. It was. Conversely, when this temperature difference is 30 ° C. or less, it is recognized that the decrease in tensile elastic modulus at high temperatures is small and the creep is remarkably small.
[0027]
The molded member of the present invention heats a crystalline resin having at least one of a hydroxyl group, a carboxylic acid group and an ester bond, an amorphous resin having at least one of a hydroxyl group, a carboxylic acid group and an ester bond, and a polymerization catalyst. A resin having a difference in melting peak temperature of 30 ° C. or less, a crystalline resin having at least one of a hydroxyl group, a carboxylic acid group and an ester bond, and at least one of a hydroxyl group, a carboxylic acid group and an ester bond. It may be made of a resin obtained by mixing an amorphous resin and a polymerization catalyst having heat and mixing with a resin having a difference in melting peak temperature of more than 30 ° C.
[0028]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be described in detail below.
[0029]
  (Crystalline resin)
  The crystalline resin used in the present invention has at least one of a hydroxyl group, a carboxylic acid group, and an ester bond.PBT (polybutylene terephthalate). PBT is particularly preferable because it has a high crystal acceleration, so that there is little change in crystallinity due to molding conditions, and the crystallinity is generally stable at around 30%.
[0032]
The molecular weight of the crystalline resin used in 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 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.
[0033]
  (Amorphous resin)
  The amorphous resin used in the present invention has a polymer main chain by an ester bond.PC (polycarbonate).
[0036]
The molecular weight of the amorphous resin used in 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, but has high mechanical properties such as tensile elongation at break. High molecular weight materials are preferred when required. Specifically, it is preferably 20,000 or more, more preferably 25,000 or more, and particularly preferably 30,000 or more.
[0037]
(Weight ratio of crystalline resin to amorphous resin)
There is no particular limitation on the weight ratio of the crystalline resin and the amorphous resin used in the present invention. However, in general, a crystalline resin is excellent in chemical resistance and flex resistance, and an amorphous resin is excellent in molding dimensional stability, so an arbitrary 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.
[0038]
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.
[0039]
(Difference in viscosity between crystalline resin and amorphous resin)
If the difference in viscosity 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.
[0040]
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.
[0041]
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.
[0042]
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.
[0043]
(Polymerization catalyst)
The polymerization catalyst is not particularly limited as long as it has the ability to polymerize the crystalline resin and the amorphous resin used in the present invention.
[0044]
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.
[0045]
Of the polymerization catalysts, Ti-based polymerization catalysts are preferred, and alkyl titanates can be suitably used.
[0046]
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).
[0047]
Further, 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 a polymerization catalyst.
[0048]
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.
[0049]
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. Specifically, the mass of metal in the polymerization catalyst is preferably 1 ppm or more, preferably 10 ppm or more with respect to the total resin. Is more preferable, and 20 ppm or more is particularly preferable. On the other hand, since ester resins may cause depolymerization in the presence of a large amount of heavy metals, it is preferable that they are somewhat small, specifically 10,000 ppm or less, more preferably 1000 ppm or less, even more preferably 500 ppm or less. Is particularly preferred.
[0050]
(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.
[0051]
In the present invention, if there is a chelator having the ability to chelate the metal in the polymerization catalyst, depolymerization can be suppressed.
[0052]
There is no restriction | limiting in particular as a kind of chelator, A well-known chelator can be used.
[0053]
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), IRGANOX MD1024 (manufactured by Ciba-Geigy Japan), CDA-6 (manufactured by Asahi Denka Kogyo Co., Ltd.), and hydrazines are easily obtained from the market. be able to.
[0054]
The addition amount of these chelators can suppress the depolymerization and low molecular weight generation by optimizing the molding conditions in the present invention, so that the addition amount of the chelator can be 0 parts by weight. If necessary, 0.001 part by weight or more is preferably added, and 0.1 part by weight or more is preferably added to obtain more effect.
[0055]
If the amount of the chelator is too large, the polymerization catalyst loses its activity and a molded member having good physical properties may not be obtained, so it is preferable not to add too much, preferably 10 parts by weight or less with respect to 100 parts by weight of the resin, More preferably, it is 5 parts by weight or less.
[0056]
In general, it is preferable to use a small amount of 0.1 parts by weight or less as a usage of a chelator, but when using a chelator in the present invention, an example of a particularly preferable usage is the addition of a polymerization catalyst. The amount is added as much as 50 to 500 ppm, and the chelator is 0.5 to 5 parts by weight, preferably 0.7 to 2 parts by weight. When the residence time and the like are optimized, depolymerization can be suppressed while the formation of a chemical bond between the crystalline resin and the amorphous resin and the molecular weight increase are promoted, and a molded member having excellent physical properties can be obtained.
[0057]
(Conductive substance)
In the present invention, when it is necessary to adjust the electric resistance value, a conductive substance may be blended. In particular, in an endless belt, 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 use in order to electrically adsorb and transfer toner, paper, and the like.
[0058]
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.
[0059]
A particularly preferable conductive material is carbon black having excellent dispersibility.
[0060]
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, and the specific surface area is 10 to 200 m.²/ G, those having a pH value of 3 to 11 are more preferred.
[0061]
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.
[0062]
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.
[0063]
The blending amount of such carbon black is preferably 3 to 30% by weight in terms of the content in the molded member, and particularly preferably within the above range, 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.
[0064]
(Additional ingredients; optional ingredients)
In the molded member of the present invention, arbitrary blending components can be blended according to various purposes.
[0065]
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.
[0066]
Furthermore, compounding materials, such as various thermoplastic resins, various elastomer 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.
[0067]
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.
[0068]
(Heat kneading)
In the present invention, a crystalline resin, an amorphous resin, and a polymerization catalyst are heated and kneaded to form a resin composition, and then a molded member is molded. Alternatively, a crystalline resin, an amorphous resin, and a polymerization catalyst are heated and kneaded. Thus, a molded member can be obtained as it is.
[0069]
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 molded member. It ’s fine. In any case, the heating temperature cannot be sufficiently dispersed unless it is in a molten state. Therefore, it is preferable that the heating temperature is higher to some extent. Specifically, the melting point of the crystalline resin should be used as a guideline, and the heating temperature should be higher than the melting point of the crystalline resin. Is preferable, and it is further more preferable that it is melting | fusing point +10 degreeC or more. Further, 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 too low. Specifically, the melting point of the crystalline resin is used as a guideline, and the melting point of the crystalline resin + 80 ° C. The following is preferable, and it is more preferable that it is melting | fusing point +60 degrees C or less.
[0070]
Moreover, since the molded member with better physical properties may be obtained by drying the raw material before heating and kneading, it is preferable to perform drying.
[0071]
In some cases, after heat-kneading to obtain a resin composition, heat treatment is performed at a temperature lower than the melting point to form an ester bond, and then the molded member can be molded.
[0072]
In the present invention, it is considered that the polymerization catalyst can promote the reaction of the crystalline resin and the amorphous resin to obtain a molded member having excellent physical properties. Since the reaction to be promoted is important for the temperature, pressure, and heat receiving time during the heat-kneading, it is necessary to set the heat-kneading conditions while grasping the dispersion form of the obtained molded member. 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.
[0073]
Although it is a means for heat kneading, there is no particular limitation on this, and a known technique can be used. For example, if a crystalline resin, an amorphous resin, and a polymerization catalyst are first heat-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 Etc. can be used. Moreover, even when a molded member is obtained from the resin composition thus obtained, a known technique can be used. For example, an injection molding machine or an extrusion molding machine.
[0074]
(Chemical bond between molecular chain of crystalline resin and molecular chain of amorphous resin)
In 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 the two resins is increased and the fine dispersion of the form is promoted. A molded member having both bending resistance, dimensional stability of an amorphous resin, and (depending on conditions) can be obtained.
[0075]
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 1,000,000 g or less, more preferably 300,000 g or less, and particularly preferably 100,000 g or less.
[0076]
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.
[0077]
A measurement example in the case of using PBT as the crystalline resin and PC as the amorphous resin is shown below.
[0078]
Measurement model JEOLGSSX400
Solvent 1,1,1,2,2,2-hexafluoroisopropanol / d-chloroform = 3/7 (VOL)
Accumulation count 128 times
Standard TMS
By this measurement, the charts shown in FIGS. FIG. 2 is an enlarged view of the portion II in FIG.
[0079]
The chemical shift of benzene ring hydrogen of terephthalic acid (TPA) differs between when carboxylic acid is bonded to butanediol and bisphenol A (BPA).
[0080]
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.
[0081]
[Chemical 1]

[0082]
On the other hand, the benzene ring hydrogen in TPA of PBT bonded to BPA of PC as shown in chemical formula 2 changes the chemical shift, hydrogen (b) has a doublet at 8.25, and (c) has a doublet peak at 8.13. Show.
[0083]
[Chemical formula 2]

[0084]
The area ratio of (d): {(b) + (c)} can determine the ratio of TPA in the PBT molecule to TPA bound to PC.
[0085]
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.
[0086]
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).
[0087]
The mass of PBT per mol of PBT-PC bond can be calculated as about 11000 (22000 / 1.98).
[0088]
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).
[0089]
[Chemical Formula 3]

[0090]
(Molecular weight)
In the present invention, a crystalline resin, an amorphous resin, and a polymerization catalyst are heated and kneaded to form a chemical bond between the molecular chain of the crystalline resin and the molecular chain of the amorphous resin, and as a resin composition Since it is considered that the physical properties of the resulting molded member can be improved by maintaining or increasing the total molecular weight, a higher molecular weight is preferable.
[0091]
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.
[0092]
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.
[0093]
As measurement conditions, 20 mg of a sample was dissolved in 0.5 ml of 1,1,1,3,3,3-hexafluoro-2-propanol and 0.2 ml of chloroform for 16 hours, 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.
[0094]
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
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.
[0095]
The PS-converted weight average molecular weight (Mw) of the resin composition obtained after heating and kneading the crystalline resin, the amorphous resin, and the polymerization catalyst, which was this method₃Specifically, 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
[0096]
[Expression 2]

It is preferable that
[0097]
[Equation 3]

[0098]
More preferably,
[0099]
[Expression 4]

[0100]
It is particularly preferable because sufficiently high physical properties can be obtained.
[0101]
In the present invention, Mw₃Mw by heating and mixing₁And Mw₂It is important that it is higher than the arithmetic average value of₁And Mw₂Even if the resin is used, 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.
[0102]
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.
[0103]
(Melting peak characteristics by DSC)
In the present invention, the difference between the peak temperature indicating the melting peak due to the first temperature increase by DSC and the peak temperature indicating the melting peak due to the second temperature increase after cooling is 30 ° C. or less.
[0104]
The above peak serves as an index indicating whether or not the molded member is in a state that changes with time (whether or not an unreacted part remains). If this peak difference is large, the endless belt is dimensioned and machined over time. Since it is thought that a change with time such as physical properties is large, it is not preferable.
[0105]
A preferable peak temperature difference is 20 ° C. or less, and 10 ° C. or less is particularly preferable.
[0106]
Even if mechanical properties such as durability and tensile elastic modulus are good at room temperature, it can not be used as a part if it changes over time, so it may be within a specific range with a melting peak difference by the above method is important.
[0107]
  (Alloy structure)
  The molded member of the present invention has an alloy structure having a sea-island structure.TheIn particular, in the case of a structure in which a crystalline component and an amorphous component are alloyed or a configuration in which fillers are added, the structure of the polymer material heated and melted may change during the cooling process. For example, in the presence of a filler or the like, the material that should be crystallized may not be crystallized and may remain in an amorphous state in the presence of a filler. Care must be taken because it may cause shrinkage and may cause extremely small shrinkage and extremely low mechanical strength.
[0108]
In order to prevent such a state, it is necessary to adopt a crystallized structure as a molded member in the material of the crystal component among the components to be alloyed.
[0109]
Such a sea-island structure is observed in a state where an ultrathin section stained with ruthenium tetroxide for 2 minutes or more is observed with a transmission electron micrograph.
[0110]
In the molded member of the present invention, it is preferable that at least a portion having a sea-island structure is confirmed and has a specific elastic modulus and bending strength.
[0111]
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.
[0112]
(Heat treatment)
By heat-treating the obtained molded member, a molded member with improved physical properties can be obtained.
[0113]
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.
[0114]
By applying the heat treatment, the folding resistance and the tensile elastic modulus are improved particularly in the case of an endless belt, which will be described later.
[0115]
(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.
[0116]
In particular, it can be suitably used for the OA equipment field, which has strict physical properties such as dimensional accuracy, bending resistance, and tensile elongation at break, especially for functional members. For example, as an endless belt shape, an electrophotographic copying machine, a laser beam printer, a facsimile machine. When used as an intermediate transfer belt, a transfer transfer belt, a photoreceptor belt or the like in an image forming apparatus such as a printer, it is preferable because there are few problems such as cracking and elongation.
[0117]
(Endless belt)
An example of a suitable use example of the molded member of the present invention is an endless belt.
[0118]
In order to obtain an endless belt, a method in which a crystalline resin, an amorphous resin, and a polymerization catalyst are mixed by, for example, a twin-screw kneading extruder, pelletized, and then formed into an endless belt is particularly preferably used.
[0119]
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.
[0120]
In addition, by optimizing the temperature and residence time during molding, a molded member with better physical properties can be obtained. Therefore, it is preferable to adjust the conditions according to each formulation.
[0121]
(Physical properties of endless belt)
According to the present invention, an endless belt having the following physical properties can be obtained.
[0122]
・ Physical properties: Fold resistance
When the endless belt used in the present invention is used as an intermediate transfer belt in an image forming apparatus, for example, an endless belt having good bending resistance is preferred because cracks occur and images cannot be obtained if the bending resistance is poor.
[0123]
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.
[0124]
  As a specific value, if it is 500 times or more, it can be used as an endless belt.ThePractically 5000 times or more is preferredIn the present invention,More than 10,000 timesTheIf it is 30000 times or more, it is particularly preferable because cracks are hardly generated.
[0125]
・ Physical properties: Tensile modulus
If the tensile elastic modulus of the endless 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 misregistration. 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.
[0126]
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.
[0127]
・ Physical properties: Temperature characteristics of tensile modulus
As the temperature characteristics of the tensile modulus, the tensile modulus at 40 ° C. is 60% or more of the tensile modulus at 5 ° C., and the tensile modulus at 60 ° C. is 20% with respect to the tensile modulus at 5 ° C. That is important. In other words, the change in tensile modulus is small between 5 ° C. and 40 ° C., and it is preferably moderately reduced between 40 ° C. and 60 ° C.
[0128]
If the tensile elastic modulus at 40 ° C is less than 60% of the tensile elastic modulus at 5 ° C, the belt stretches during use in printers or copiers in the summer or at high temperatures, causing images to shift or creep deformation. It becomes easy to do. Preferably, the tensile elastic modulus at 40 ° C. is 70% or more with respect to the tensile elastic modulus at 5 ° C., more preferably 80% or more.
[0129]
Further, it is important that the tensile modulus at 60 ° C. is 20% or more with respect to the tensile modulus at 5 ° C. If the tensile elastic modulus at 60 ° C. is less than 20% of the tensile elastic modulus at 5 ° C., belt creep and dimensional changes are likely to occur over time from several days to several years, which is not preferable.
[0130]
Particularly preferably, the tensile elastic modulus at 60 ° C. is 40% or more, more preferably 60% or more with respect to the tensile elastic modulus at 5 ° C.
[0131]
・ Physical properties; surface resistivity
The endless belt used in the present invention can obtain conductivity by blending a conductive filler or a substance exhibiting conductivity as required.
[0132]
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.
[0133]
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.
[0134]
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 difference between the maximum value and the minimum value in one is within two digits (the maximum value is It is preferably within 100 times the minimum value).
[0135]
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.
[0136]
・ Endless belt thickness
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.
[0137]
・ Use of endless belt
The use of the endless belt is not particularly limited. For example, it can be suitably used as an electrophotographic intermediate transfer belt, a conveyance transfer belt, a photosensitive belt, and the like.
[0138]
【Example】
The present invention will be described more specifically with reference to examples and comparative examples.
[0139]
(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
Heat stabilizer; Phosphorylation antioxidant PEPQ Made by Clariant Japan
Carbon black; Denka black; manufactured by Electrochemical Co., Ltd.
(Heat kneading)
Each raw material was pelletized using a twin-screw kneading extruder (PMG32 manufactured by IKG Co., Ltd.).
[0140]
(Endless 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, and the extruded molten tube was placed on the same axis as the annular die. While contacting and cooling the outer surface of a cooling mandrel with an outer diameter of 170 mm mounted via a support rod, the seamless belt is then provided by a core installed in the seamless belt and a roll installed outside. Was cut in a length of 340 mm while being held in a cylindrical shape, and the extrusion amount and the take-up speed were adjusted so that the predetermined thickness and residence time described in Table 1 were obtained, to obtain a resin seamless belt having a diameter of 169 mm. .
[0141]
Conditions such as molding temperature and residence time were as shown in Table 1.
[0142]
(Evaluation)
The evaluation was carried out by cutting the endless belt to the required size as required.
・ 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.
・ Folding resistance
In accordance with JISP-8115, the test piece was cut to a size of 15 mm in width and 100 mm in length, and was bent with a MIT tester at a bending speed of 175 times / minute, a rotation angle of 135 ° left and right, and a tensile load of 1.5 kgf. The number of breaks was measured.
・ Surface resistivity Ω
The surface resistivity can be properly measured depending on the measuring instrument.
[0143]
Surface resistivity is 1-1 × 10⁶As a sample to be Ω, Diales Instruments Co., Ltd. Loresta was used, and the belt circumferential direction was measured at a pitch of 20 mm.
[0144]
Surface resistivity is 10⁶~ 1x10¹³As a sample to be Ω, Hiresta (HA terminal) manufactured by Dia Instruments Co., Ltd. was used, and the belt circumferential direction was measured at a pitch of 20 mm under conditions of 500 V and 10 seconds.
[0145]
Surface resistivity is 10¹³~ 1x10¹⁶As a sample to be Ω, a belt current direction was measured at a pitch of 100 mm under a condition of 500 V for 10 seconds using a microcurrent measuring device R8340A (JIS electrode) manufactured by Advantest Corporation.
[0146]
DSC
Using SSC-5200 (trade name) manufactured by Seiko Denshi Kogyo Co., Ltd., the measurement was performed at a heating rate of 10 ° C./min. After the first DSC measurement to raise the temperature of one sample to 300 ° C., the sample was cooled to room temperature at 10 ° C./min, and then the second DSC measurement was performed again under the same conditions to obtain the first melting peak temperature and The difference from the second melting peak temperature was determined.
・ Thickness
Measurement was performed at a pitch of 20 mm in the circumferential direction of the endless belt using a micrometer manufactured by Tokyo Seimitsu Co., Ltd.
Volume resistivity (Ω · cm)
Using a high resistance meter Hiresta HRS probe (manufactured by Dia Instruments Co., Ltd.), measurement was performed at a measurement voltage of 100 V and a measurement time of 10 seconds at a pitch of 20 mm in the circumferential direction of the endless belt.
・ Durability evaluation as an endless belt
The obtained endless belt is mounted on an image forming apparatus as an intermediate transfer belt, a transfer transfer belt, or a photosensitive belt, and images are continuously output, and how many sheets are output indicates whether cracks or image deviation occurs in the endless belt. evaluated.
[0147]
[Examples 1-7]
PBT, PC, tetrabutyl titanate, magnesium acetate, and a heat stabilizer were preliminarily dried at about 130 ° C. in advance, and then heated and kneaded to obtain material pellets.
[0148]
The heating and kneading conditions at this time are shown in Table 1, and the reaction in the kneader was suppressed.
[0149]
This material pellet was extruded to produce an endless belt. It should be noted that the extrusion conditions shown in Table 1 were set so that the reaction was accelerated to a preferable level in the extruder and an endless belt was obtained.
[0150]
Table 1 shows the form and characteristics of the endless belt.
[0151]
[Comparative Example 1]
An endless belt was produced under the same conditions as in Example 1 except that the polymerization catalyst was not used.
[0152]
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.
[0153]
[Comparative Example 2]
The kneading conditions and extrusion conditions were selected so that the sea-island structure did not occur. By setting the conditions shown in Comparative Example 2 in Table 1, an endless belt having a non-sea island structure in which PBT and PC were uniformly dispersed was manufactured.
[0154]
Table 1 shows the form and appearance of the endless belts of Comparative Examples 1 and 2.
[0155]
[Table 1]

[0156]
As shown in Table 1, each of the endless belts according to the examples of the present invention has a high tensile elastic modulus over a wide temperature range, excellent belt durability, and good flexibility. On the other hand, in Comparative Example 1 in which the polymerization catalyst was not added, cracks and image misalignment occurred with 60,000 sheets, and the bending resistance was insufficient. In Comparative Example 2, although the polymerization catalyst was added, the temperature at the time of kneading and molding was set to a high value and a non-sea island structure, so the difference between the first and second DSC melting temperatures was large. Therefore, the tensile elastic modulus in a high temperature region (60 ° C.) is small. As a result, 60,000 copies produced an image shift due to elongation of the endless belt.
[0157]
【The invention's effect】
As is clear from the above examples and comparative examples, according to the present invention, a molded member having a high tensile elastic modulus over a wide temperature range and excellent in bending resistance, chemical resistance and molding dimensional stability is provided. .
[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.

Claims (8)

A crystalline resin having at least one of a hydroxyl group, a carboxylic acid group and an ester bond, an amorphous resin having at least one of a hydroxyl group, a carboxylic acid group and an ester bond, and a polymerization catalyst are mixed by heating, and molded.
The crystalline resin is PBT (polybutylene terephthalate), the amorphous resin is PC (polycarbonate),
The molded resin has a sea-island structure,
The difference between the peak temperature indicating the melting peak due to the first temperature increase by DSC (differential scanning calorimetry) and the peak temperature indicating the melting peak due to the second temperature increase after cooling is 30 ° C. or less, and JIS P-8115 The molded member is characterized in that the folding endurance is 10,000 times or more.   The molded member 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 molded member 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 molded member according to any one of claims 1 to 3, wherein when the PS-converted weight average molecular weight of the resin composition obtained after heat-kneading the functional resin and the polymerization catalyst is Mw ₃ , the following relationship is satisfied: .

  The molded member according to any one of claims 1 to 4, wherein the PS-converted weight average molecular weight is 130,000 or more.   The molded member according to claim 1, wherein the polymerization catalyst contains Ti.   The molded member 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 molded member according to claim 7, wherein the element of the group is Mg.

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