JP2004155892A - Conductive resin composition, conductive roll, and method for producing the roll - Google Patents
Conductive resin composition, conductive roll, and method for producing the roll Download PDFInfo
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Abstract
Description
【０００１】
【発明の属する技術分野】
本発明は、導電性樹脂組成物、導電ロール及びその製造方法に関し、更に詳しくは、特に、電子複写機、プリンターなどに使用される導電ロールに好適な導電性樹脂組成物、該樹脂組成物からなる導電ロール及びその製造方法に関する。
【０００２】
【従来の技術】
電子写真複写機やプリンターの帯電方式において 近年、オゾン発生対策として従来の高電圧を必要とするコロトロン又はスコロトンを利用した方式から、低電圧を利用した接触式帯電ローラーや帯電ブラシ、又は非接触式の針状帯電器を用いた方式への転換が進んでいる。このうち導電性帯電ロールは上記した静電気現象を利用した電子写真方式で 感光体や帯電保持部材に電荷を与えるために使用されるロールで、通常、金属製の軸芯の外周部にカーボンブラックや金属粉体を混入せしめて導電性を付与したゴム或いは発泡体を配置することによって得られている。従来の導電ロールはゴムや弾性体或いは発泡体の様に、いわゆるニップ幅を確保するために或る柔らかさを確保しつつ、その樹脂内もしくは表面に導電性物質を分散させて導電性を付与している。しかしながら、内包する導電性物質の導電性が高過ぎ、且つ導電性物質の分散の調整が困難なため導電性の制御が難しく、均一性・安定性に問題があった。
【０００３】
これらの問題に対して、導電性を制御し、且つ安定化・均一化するためにフェライトを導電性材料として使用した導電性部材が提案されている。例えば、Ｍｎ−Ｚｎフェライトの微粉末をポリプロピレン樹脂に分散させた導電性プラスチックベルトがトナー転写ベルトとして提案されている（特許文献１参照）。また、導電性顔料としてＣｕ−Ｍｇ−Ｚｎフェライトをフッ素樹脂塗料中に分散させてシリコーンゴムローラーの上に浸漬塗布し、厚さ１０μｍの被覆層を形成させた帯電部材が提案されている（特許文献２参照）。更に、フェライトをシリコーンゴム中に分散させた導電性シリコーンゴムロールが提案されている（特許文献３参照）。
【０００４】
【特許文献１】
特開平５−６６６８５号公報
【特許文献２】
特開平８−１８５０１３号公報（第６頁、実施例６）
【特許文献３】
特開平９−１５１３２３号公報
【０００５】
【発明が解決しようとする課題】
しかしながら、上記特許文献に記載の導電性部材は、いずれもフェライトの含有率が低いために曲げ弾性率が低く、感光体への帯電性付与を安定化させるために剛性を必要とする導電性帯電ロール用途においては未だに不十分であった。また、特許文献２に開示されている帯電部材は、シリコーンゴムローラー上にフェライトを含有する１２μｍの被覆層を設けるものであり、耐久性・信頼性・加工コスト等に問題がある。
【０００６】
【課題を解決するための手段】
本発明者らは、かかる実情に鑑み、上記従来技術の問題点を解決するべく鋭意研究の結果、いわゆるソフトフェライト粒子粉末の導電性とその安定性に着目し、これを比較的多量に樹脂に配合することにより、適切な導電性と曲げ弾性率を有する導電性樹脂組成物が得られ、該樹脂組成物を用いた導電ロールが感光体表面の帯電電圧を適正なレベルで安定化させるとともに、優れた研削精度を有することを見出し、本発明に到達した。
【０００７】
すなわち、本発明の請求項１に係る導電性樹脂組成物は、３０〜７０体積％のソフトフェライト粒子粉末と７０〜３０体積％の樹脂とからなり、体積固有抵抗が１．０×１０１ 〜５．５×１０４ Ω・ｍで、曲げ弾性率が５．０×１０９ 〜８．０×１０１１Ｐａであることを特徴とする。
【０００８】
本発明の請求項２に係る導電性樹脂組成物は、ソフトフェライト粒子粉末がＮｉ−Ｍｎ−Ｚｎフェライト粒子粉末、Ｎｉ−Ｚｎフェライト粒子粉末、Ｍｎ−Ｚｎフェライト粒子粉末から選ばれる少なくとも１種であることを特徴とする。
【０００９】
本発明の請求項３に係る導電性樹脂組成物は、ソフトフェライト粒子粉末がＮｉ−Ｚｎフェライト粒子粉末とＭｎ−Ｚｎフェライト粒子粉末からなり、Ｎｉ−Ｚｎフェライト粒子粉末とＭｎ−Ｚｎフェライト粒子粉末の重量比が０：１００から８０：２０であることを特徴とする。
【００１０】
本発明の請求項４に係る導電性樹脂組成物は、ソフトフェライト粒子粉末の平均粒子径が、サブシーブサイザー法で１．０〜９．０μｍであることを特徴とする。
【００１１】
本発明の請求項５に係る導電性樹脂組成物は、７５μｍを超えるソフトフェライトの粒子及び又はその凝集物を実質的に含有しないことを特徴とする。
【００１２】
本発明の請求項６に係る導電性樹脂組成物は、ソフトフェライト粒子粉末がカップリング剤で表面処理されていることを特徴とする。
【００１３】
本発明の請求項７に係る導電性樹脂組成物は、樹脂がポリアミド１２樹脂、ポリフェニレンサルファイド樹脂（ＰＰＳ）から選ばれる樹脂からなることを特徴とする。
【００１４】
本発明の請求項８に係る導電性樹脂組成物は、ペレット状であることを特徴とする。
【００１５】
本発明の請求項９に係る導電ロールは、導電性樹脂組成物で成形されたことを特徴とする。
【００１６】
本発明の請求項１０に係る導電ロールは、金属製軸芯の外周に導電性樹脂組成物を配置したことを特徴とする。
【００１７】
本発明の請求項１１に係る導電ロールの製造方法は、導電性樹脂組成物を射出成形機に供給し、金型のキャビティには金属製軸芯を装着し、軸芯の周囲に導電性樹脂組成物を射出成形することを特徴とする。
【００１８】
本発明の請求項１２に係る導電ロールの製造方法は、ペレット状の導電性樹脂組成物を用いることを特徴とする。
【００１９】
本発明の請求項１３に係る導電ロールの製造方法は、粉末状の導電性樹脂組成物を混練機に供給し、混練・溶融した樹脂組成物を射出成形機のシリンダー部に導き、金型のキャビティには金属製軸芯を装着し、該軸芯の周囲に導電性樹脂組成物を射出成形することを特徴とする。
【００２０】
【発明の実施の形態】
本発明に係る導電性樹脂組成物は、３０〜７０体積％のソフトフェライト粒子粉末と７０〜３０体積％の樹脂とからなり、体積固有抵抗が１．０×１０１ 〜５．５×１０４ Ω・ｍで、曲げ弾性率が５．０×１０９ 〜８．０×１０１１Ｐａであることを特徴とする。
【００２１】
尚、本発明において、導電性の評価はその逆数である体積固有抵抗によって行う。導電性が低いものは体積固有抵抗が高く、逆に導電性が高いものは体積固有抵抗が低くなる関係にある。
【００２２】
本発明に用いられるソフトフェライト粒子粉末は、例えば、Ｎｉ−Ｍｎ−Ｚｎフェライト粒子粉末、Ｎｉ−Ｚｎフェライト粒子粉末、Ｍｎ−Ｚｎフェライト粒子粉末等が挙げられ、これらは単独で又は２種以上組み合わせて用いられる。これらは、他の金属酸化物に比して、導電性が比較的高く、且つ化学的に安定しているという特徴を有する。
【００２３】
Ｎｉ−Ｍｎ−Ｚｎフェライト粒子粉末は、主成分のＦｅ２ Ｏ３ 、ＮｉＯ、ＭｎＯ、ＺｎＯ、それぞれの金属酸化物のモル比が、５２±１１％、１５±１０％、５±２％、及び２８±１１％であって、副成分のＣｕ、Ｍｇ、Ｂｉ、Ｓｉ、Ｃａ等の金属が酸化物として重量比でそれぞれ０〜４％程度添加されたフェライト粒子粉末であり、通常のＮｉ−Ｍｎ−Ｚｎフェライト粒子粉末の製造方法で製造されることが体積固有抵抗の制御上好ましい。
【００２４】
Ｎｉ−Ｚｎフェライト粒子粉末は、主成分のＦｅ２ Ｏ３ 、ＮｉＯ、ＺｎＯ、それぞれの金属酸化物のモル比が５０±１１％、１９±１１％、及び３１±１１％であって、副成分のＣｕ、Ｍｇ、Ｂｉ、Ｓｉ、Ｃａ、Ｂ等の金属が酸化物として重量比でそれぞれ０〜６％程度添加されたフェライト粒子粉末であり、通常のＮｉ−Ｚｎフェライト粒子粉末の製造方法で製造されることが体積固有抵抗の制御上好ましい。
【００２５】
Ｍｎ−Ｚｎフェライト粒子粉末は、主成分のＦｅ２ Ｏ３ 、ＭｎＯ、ＺｎＯそれぞれの金属酸化物のモル比が５３±１１％、３２±１１％、及び１５±８％であって、副成分のＳｉ、Ｍｇ、Ｃａ、Ｃｕ、Ｂ、Ｂｉ等の金属が酸化物として重量比率でそれぞれ０〜２％程度添加されたフェライト粒子粉末であり、通常のＭｎ−Ｚｎフェライト粒子粉末の製造方法で製造されることが体積固有抵抗の制御上好ましい。
【００２６】
Ｎｉ−Ｚｎフェライト粒子粉末は、Ｍｎ−Ｚｎフェライト粒子粉末に比して導電性が低いので、導電性が高いＭｎ−Ｚｎフェライト粒子粉末と組み合わせることによって、所望の導電性と曲げ弾性率を有する導電性樹脂組成物を設計することができる。
Ｎｉ−Ｚｎフェライト粒子粉末とＭｎ−Ｚｎフェライト粒子粉末との重量比は、０：１００〜８０：２０が好ましい。より好ましくは、０：１００〜７５：２５、さらに好ましくは、５：９５〜７５：２５である。Ｎｉ−Ｚｎフェライト粒子粉末重量の割合が８０％を越えると、体積固有抵抗が高くなって帯電性（導電性）が悪化する傾向があるので好ましくない。
【００２７】
ソフトフェライト粒子粉末の粒子径は、製造時の該成分組成固有の粒子成長及び焼結の状態と粉砕条件で決まるが、樹脂との混練性を考慮して設計することが好ましい。
このような観点から、ソフトフェライト粒子粉末の平均粒子径は、サブシーブサイザー法で、１．０〜９．０μｍであることが好ましく、より好ましくは、１．５〜８．０μｍである。
【００２８】
ソフトフェライト粒子粉末の平均粒子径が１．０μｍ未満では 該フェライト粒子粉末の樹脂中への分散が容易ではなく、一方、平均粒子径が９．０μｍを超えると巨大な粒子が一部混在するために、該大粒子が存在する部分とその他の部分との導電性が相対的に大きく異なるという分布が発生するので好ましくない。
【００２９】
樹脂中への分散性を良好にするためには、分散させるソフトフェライト粒子粉末の粒子径は、数μｍ以上が好ましい。しかし、成形物の導電性の均一性を確保するためには粒子径は小さいことが好ましい。この相反する現象を解決する１つの手段として、ソフトフェライト粒子粉末を２種以上併用する場合は、上記したように、導電性が相対的に大きく、成形物への導電性の寄与が大きいＭｎ−Ｚｎフェライト粒子は比較的小さく、導電性へ寄与が相対的に小さいＮｉ−Ｚｎフェライト粒子は比較的大きく設計するのが好ましい。
【００３０】
また、７５μｍを超える巨大な粒子、あるいは凝集物を実質上除去することが、上述した導電性の均一化に有効である。また、後述する様に、成形体表面を研削する場合、部分的欠損（フェライト粒子粉末の欠落）が小さく且つ少ないことが実用上特に有効である。これらの巨大な粒子、あるいは凝集物は、風力分級機を使用するか、或いは目開きが７５μｍ以下の篩を通すことにより、実用上問題の無い含有量、すなわち、概ね０．３重量％以下に低減することができる。
【００３１】
本発明の目的である導電性を満足するために、Ｎｉ−Ｍｎ−Ｚｎフェライト粒子粉末、Ｎｉ−Ｚｎフェライト粒子粉末やＭｎ−Ｚｎフェライト粒子粉末以外に、例えば酸化ケイ素やチタン酸バリウムなどの水分や空気（酸素）に対して安定なフィラーを、適宜少量添加することは何ら差し支えない。
【００３２】
導電性の安定、特に水分の影響に対する安定性の確保は、導電ロールにとって重要特性の１つである。本発明で採用するソフトフェライト粒子粉末は、水分・湿気に対して物理化学的に安定であるが、カップリング剤を粒子表面に処理して使用することが好ましい。ソフトフェライト粒子表面をカップリング剤で被覆しておくことによって、フェライト粒子の分散が均一化されるだけでなく、導電ロールの導電性への水分の影響を最小化することができる。
【００３３】
カップリング剤は、一般に市販されているシラン系カップリング剤、チタネート系カップリング剤等が有効であるが、特に、日本ユニカー社製 Ａ−１１２０のようなアミノ基を有するシランカップリング剤が比較的安価で、樹脂との混練性に優れている点で好適である。これらカップリング剤は、ソフトフェライト粒子粉末１００重量部に対して、通常０．１〜０．９重量部使用される。カップリング剤の処理量が０．１重量部未満では、上記処理効果が十分でなく、一方、０．９重量部を超えると混練物表面に未吸着分がにじみ出す危険性が高まる。
【００３４】
本発明に用いられる樹脂としては、ソフトフェライト粒子粉末との樹脂組成物とした場合に、５．０×１０９ 〜８．０×１０１１Ｐａの曲げ弾性率を有する成形体を与えるような樹脂が用いられる。このような樹脂としては、例えば、ポリアミド６、ポリアミド１２等のポリアミド樹脂、ポリエチレン、ポリプロピレン等のポリオレフィン樹脂、液晶樹脂、ポリフェニレンサルファイド樹脂（ＰＰＳ）などが好適であり、これらは単独で又は２種以上組み合わせて用いられる。また、エチレンビニルアセテート樹脂（ＥＶＡ）やエチレンエチルアクリレート樹脂（ＥＥＡ）、或いはその他のエラストマーなどの比較的弾性率が低い樹脂であっても、ソフトフェライト粒子粉末との樹脂組成物としての曲げ弾性率が５．０×１０９ 〜８．０×１０１１Ｐａであれば採用できる。
【００３５】
また、対湿度信頼性の観点からは、吸湿性が小さい熱可塑性樹脂、すなわち、ポリアミド１２樹脂、ポリフェニレンサルファイド樹脂（ＰＰＳ）等が特に好適である。また、対湿度信頼性と成形性・生産性の両者の観点からはポリアミド１２樹脂が選択され、対湿度信頼性の観点からはポリフェニレンサルファイド樹脂（ＰＰＳ）が選択される。
【００３６】
本発明の導電性樹脂組成物は、３０〜７０体積％のソフトフェライト粒子粉末及び７０〜３０体積％の樹脂からなる。ソフトフェライト粒子粉末が７０体積％を超えると、混練・成形が難しく、また、３０体積％未満では曲げ弾性率が低くなり過ぎ、形状が変形しやすくなるために、後述するように、導電ロールの研削精度が確保できない。好ましくは３５体積％以上である。更に、エチレンエチルアクリレート樹脂のように柔らかい樹脂を使う場合には、４０体積％以上が好ましい。
【００３７】
本発明の導電性樹脂組成物は、更に、加工助剤、安定剤、その他、この種の導電性樹脂組成物に通常用いられる各種の添加剤を含有することができる。加工助剤としては、川研ファインケミカル社製 アマイド−６Ｓ等の滑剤が好ましい。加工助剤の好適な添加量は、０．０１〜０．３重量％である。加工助剤の量が０．０１重量％未満では十分な効果が期待できず、一方、０．３重量％を超えるとロール表面への滑剤の拡散・滲み出しが多くなり、帯電に悪影響を及ぼす場合がある。
【００３８】
本発明の導電性樹脂組成物は、通常の方法で混練・造粒して、いわゆるペレットとして得ることができる。具体的には、ソフトフェライト粒子粉末３０〜７０体積％に樹脂７０〜３０体積％を添加し、必要に応じ、加工助剤等の添加剤を添加して混練・溶融し、ダイから押し出されるストランドを数ミリの長さにカットすることにより得られる。
【００３９】
本発明の導電性樹脂組成物は、特に導電ロールとして好適であり、各種の成形方法により導電ロールとされる。
例えば、ペレット状の導電性樹脂組成物は、通常の射出成形方法で金型キャビティに射出することで導電ロールを成形することができる。該キャビティに予め金属軸芯を装着しておけば、軸芯インサート射出成形法で容易に導電ロールを成形することができる。軸芯は予め、表面をメッキし、更に必要に応じて表面処理してもよい。
【００４０】
また、粉末状の導電性樹脂組成物は、混練機に供給し、所定の温度で混練し、溶融した樹脂組成物を溶融した状態で射出成形機のシリンダー部に導き、金型のキャビティには金属製軸芯を装着し、該軸芯の周囲に導電性樹脂組成物を射出成形することにより、導電ロールを成形することができる。本成形方法は、樹脂の溶融状態を連続で保持する時間が長いので、樹脂温度が均一となり、射出成形が安定するので、特性の安定した導電ロールを得ることができる。
【００４１】
更に、本成形方法は、ペレットを射出成形機で可塑化・成形する場合に比して、滑剤等の加工助剤を必ずしも同等量必要としないので、該添加剤による、ブリード、汚染、機械強度の低下等を減少させることができる。更にまた、本成形方法は、ペレット化工程を省略することができるので、生産性が高く、生産コストが低減される利点がある。
【００４２】
上記の如くして得られる本発明に係る導電ロールは、１．０×１０１ 〜５．５×１０４ Ω・ｍの体積固有抵抗を有する。
体積固有抵抗が１．０×１０１ Ω・ｍ未満では、導電ロールが接触時に感光体や電荷保持体上の電荷がリークすることにより十分な帯電ができず、一方、体積固有抵抗が５．５×１０４ Ω・ｍを超えると、感光体や電荷保持体上に帯電不足が生じ、十分に帯電できない。好ましい体積固有抵抗は、１．０×１０２ 〜５．０×１０４ Ω・ｍである。
【００４３】
導電ロールは、感光体もしくは帯電保持部材に直接帯電させるため、その寸法形状には高い精度が要求される。そのために、必要に応じ、該導電ロールの外周面を研削する必要があるが、ゴムや発泡体の様に剛性が低い導電ロールの場合は、研削寸法精度が低くなる。これに対して、剛性が高い場合、高い寸法精度を確保することができる。導電ロールの軸が金属製であれば、該研削加工寸法精度は更に高めることができる。
【００４４】
上記の如くして得られる本発明に係る導電ロールは、５．０×１０９ 〜８．０×１０１１Ｐａの曲げ弾性率を有する。
曲げ弾性率が５．０×１０９ Ｐａ未満では、上記したように、導電ロールの研削精度を確保できないだけでなく、導電ロールの押し付け圧により導電ロールの接触面積が増加し、導電ロール及び感光体等の回転トルクが増加する。また、導電ロールがたわみ変形するために導電性が不均一になる。一方、曲げ弾性率が８．０×１０１１Ｐａを超えると、導電ロールと感光体等の被帯電部材との接触が悪くなり、十分に帯電されない。
【００４５】
【実施例】
以下、実施例及び比較例を挙げて本発明を更に詳細に説明するが、これらは本発明を何ら制限するものではない。
尚、以下の記載において、体積固有抵抗、曲げ弾性率、感光体表面の帯電電圧は、それぞれ下記の方法で測定した。
【００４６】
体積固有抵抗：
得られたペレットをφ２５ｍｍの円柱空間に充填し、２４０±１０℃に加熱後、円柱の高さ方向に圧力を加え、厚さ約１０ｍｍの円盤状サンプルを準備し、該試験片の表面を＃１０００のサンドペーパーで研磨して、スキン層（樹脂リッチ層）を除去した。該表面調整後の試験片を断面積２．４１９×１０−４ｍ２ のステンレス製平面電極で挟み、５Ｎの加重を掛け、ホイーストンブリッジ法で抵抗を測定した。印加電圧は直流２０Ｖであった。
【００４７】
曲げ弾性率：
ＡＳＴＭ−Ｄ７９０に準拠した。
【００４８】
感光体表面の帯電電圧：
富士通社製レーザービームプリンター（Ｍｏｄｅｌ Ｆ９６８２Ｅ２）のプリンターに上記導電ロールを挿入し、シャフトに６００〜７００Ｖを印加し、感光体上の表面電位を表面電位計で測定した。
【００４９】
実施例１〜５
サブシーブサイザー法で平均粒子径６．０μｍのＮｉ−Ｚｎフェライト粒子粉末（戸田工業社製、商品名ＢＳＮ−７１４）と、サブシーブサイザー法で平均粒子径３．２μｍのＭｎ−Ｚｎフェライト粒子粉末（戸田工業社製、商品名ＢＳＦ−５４７）とを所定の重量比率で混合し合計１００重量部とし、０．５重量部のアミノ基含有シランカップリング剤（日本ユニカー社製、商品名Ａ−１１２０）で表面処理した後、滑剤（川研ファインケミカル社製、商品名アマイド−６Ｓ）を０．２重量部、ポリアミド６樹脂（宇部興産社製、商品名Ｐ１０１０）粉末を所定の量加えた該混合物を２４０℃±１０にコントロールされたφ２５ｍｍの二軸混練機で溶融・混練し、米粒大のペレットからなる導電性樹脂組成物を得た。
【００５０】
該ペレットを、通常の射出成形機で、金属製の軸芯（シャフト）を装着した金型の該軸芯の周囲に射出成形（軸芯インサート射出成形）して、導電ロールを得た。
【００５１】
実施例６
Ｎｉ−Ｚｎフェライト粒子粉末及びＭｎ−Ｚｎフェライト粒子粉末をそれぞれあらかじめ篩に掛けて、７５μｍを超える粒子および凝集物を除去し、それらの含有量を０．３重量％以下とし、実施例１〜５と同じ方法でそれぞれを５５重量部、４５重量部を使用し、フェライト粒子粉末含有率が６０体積％になる様にフェライト粒子粉末と樹脂等の混合物を調製後、溶融・混練し、ペレットからなる導電性樹脂組成物を得た。得られたペレットの曲げ弾性率は実施例４の約１．２倍（１．７×１０１０Ｐａ）になり、軸芯インサート導電ロール表面を研削した際、巨大粒子や凝集物による表面の荒れや小さな欠けなどの欠陥がほとんど認められなかった。感光体表面の帯電電圧は６５５±１５Ｖで安定していた。
【００５２】
実施例７
実施例６と同様にして得たフェライト粒子粉末と樹脂等の混合物からなる導電性樹脂組成物を混練機（ＴＥＸ３０、日本製鋼所製）で溶融・混練し、樹脂組成物が溶融したままの状態で射出成形機（Ｊ３５０ＥＸ、日本製鋼所製）のシリンダーに導き、以下通常の軸芯インサート射出成形によって軸芯インサート導電ロールを得た。本方法では、ペレットの状態を経ることなく粉体組成物から直接簡素化された工程で導電ロールを得ることができ、極めて効率的であった。
【００５３】
実施例８〜９
Ｍｎ−Ｚｎフェライト粒子粉末とＮｉ−Ｚｎフェライト粒子粉末とを所定の重量部比率で、ソフトフェライト粒子粉末含有率をそれぞれ所定の体積％とし、樹脂としてエチレンエチルアクリレート樹脂（ＥＥＡ樹脂、三井デュポン製エバフレックス ７０２）を採用し、滑剤としてサンワックス１７１Ｐ（三洋化成社製商品名）を採用したこと以外は、実施例１〜５と同様の方法で、軸芯インサート導電ロールを得た。
【００５４】
実施例１０
樹脂としてポリアミド１２樹脂（ダイセル社製商品名Ａ１７０９Ｐ）を採用し、粗粒子除去操作を実施せず、フェライト含有率を変更したこと以外は、実施例７と同様の方法で、軸芯インサート導電ロールを得た。
【００５５】
実施例１１〜１２
樹脂として、実施例１０で用いたポリアミド樹脂１２、ポリフェニレンサルファイド樹脂（ＰＰＳ樹脂、東レＭ−３９１０）をそれぞれ採用し、滑剤として、それぞれアマイド６Ｓ又はサンワックス１７１Ｐを採用し、実施例６と同様の方法で、軸芯インサート導電ロールを得た。
【００５６】
実施例１３〜１４
Ｍｎ−Ｚｎフェライト粒子粉末及びＮｉ−Ｚｎフェライト粒子粉末の粒子径をそれぞれ変更した以外は実施例１〜５と同様にして、軸芯インサート導電ロールを得た。実施例１３の導電ロールはソフトフェライト粒子粉末が比較的大きいため、帯電電圧のバラツキが大きい傾向にある。一方、実施例１４はソフトフェライト粒子粉末が比較的小さいため、分散が難しく帯電電圧のバラツキが大きくなる。いずれも導電ロール組成のミクロな均一性の乱れの影響によるものと考えられる。
【００５７】
実施例１５
Ｎｉ−Ｚｎフェライト粒子粉末とＭｎ−Ｚｎフェライト粒子粉末の重量比を８０：２０に変更した以外は実施例１〜５と同様にして軸芯インサート導電ロールを得た。得られた導電ロールは体積固有抵抗がやや高くなり、感光体表面の帯電電圧がやや低かった。
【００５８】
実施例１６
Ｍｎ−Ｚｎフェライト粒子粉末とＮｉ−Ｚｎフェライト粒子粉末との混合物に代えて、Ｎｉ−Ｍｎ−Ｚｎフェライト粒子粉末（Ｆｅ２ Ｏ３ 、ＮｉＯ、ＭｎＯ、ＺｎＯ、それぞれの金属酸化物のモル比が、５２％、１５％、５％、及び２８％）を使用した以外は実施例１〜５と同様にして軸芯インサート導電ロールを得た。
【００５９】
比較例１〜２
ソフトフェライトの含有率をそれぞれ７４体積％、２５体積％に変更した他は実施例４と同様にして軸芯インサート導電ロールを得ようとしたが、比較例１はソフトフェライト粒子粉末の含有率が高過ぎるため、粘度が高く樹脂との混練が不可能であった。一方、比較例２はソフトフェライト粒子粉末の含有率が低過ぎるため、曲げ弾性率が低過ぎ、その結果、得られた軸芯インサート導電ロールは研削精度が悪く実用性の乏しいものであった。
【００６０】
以上の実施例１〜１６と比較例１〜２の結果を表１及び表２にまとめた。
【００６１】
【表１】
【表２】
【発明の効果】
以上のように、本発明の導電性樹脂組成物は、適切な導電性と曲げ弾性率を有し、特に、導電ロールに有用である。本発明の導電性樹脂組成物からなる導電ロールは、安定且つ均一な導電性を有するとともに、導電ロールの研削精度を確保することができる。また、本発明の導電性樹脂組成物によれば、導電ロールを射出成形法によって得ることができ、更に、ペレットを経ないで、粉体状の樹脂組成物から直接導電ロールを射出成形することにより、工程が簡素化された安価な方法で生産することができる。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a conductive resin composition, a conductive roll and a method for producing the same, and more particularly, particularly to a conductive resin composition suitable for a conductive roll used in an electronic copying machine, a printer, and the like. And a method of manufacturing the same.
[0002]
[Prior art]
In recent years, in the charging method of electrophotographic copiers and printers, as a measure against ozone generation, from the conventional method using a corotron or scoroton that requires a high voltage, a contact-type charging roller or charging brush using a low voltage, or a non-contact The conversion to a system using a needle-shaped charger is progressing. Among these, the conductive charging roll is a roll used to apply a charge to the photoreceptor and the charge holding member in the electrophotographic method utilizing the above-mentioned electrostatic phenomenon. Usually, carbon black or the like is provided around the outer periphery of the metal shaft core. It is obtained by arranging a rubber or foam provided with conductivity by mixing metal powder. Conventional conductive rolls, such as rubber, elastic or foamed materials, have a certain softness to secure the so-called nip width and provide conductivity by dispersing a conductive substance in or on the resin. are doing. However, since the conductivity of the conductive substance contained therein is too high, and it is difficult to adjust the dispersion of the conductive substance, it is difficult to control the conductivity, and there is a problem in uniformity and stability.
[0003]
To solve these problems, there has been proposed a conductive member using ferrite as a conductive material in order to control conductivity and stabilize / uniformity. For example, a conductive plastic belt in which fine powder of Mn-Zn ferrite is dispersed in a polypropylene resin has been proposed as a toner transfer belt (see Patent Document 1). Also, a charging member has been proposed in which Cu-Mg-Zn ferrite as a conductive pigment is dispersed in a fluororesin paint and immersed and applied on a silicone rubber roller to form a coating layer having a thickness of 10 µm (Patent) Reference 2). Furthermore, a conductive silicone rubber roll in which ferrite is dispersed in silicone rubber has been proposed (see Patent Document 3).
[0004]
[Patent Document 1]
JP-A-5-66685 [Patent Document 2]
JP-A-8-185013 (page 6, Example 6)
[Patent Document 3]
JP-A-9-151323
[Problems to be solved by the invention]
However, the conductive members described in the above patent documents all have a low flexural modulus due to a low ferrite content, and a conductive charge that requires rigidity in order to stabilize charging of the photoreceptor. It was still insufficient for roll applications. Further, the charging member disclosed in Patent Document 2 has a 12 μm coating layer containing ferrite on a silicone rubber roller, and has problems in durability, reliability, processing cost, and the like.
[0006]
[Means for Solving the Problems]
In view of such circumstances, the present inventors have conducted intensive studies to solve the problems of the above-described conventional technology, and as a result, focused on the conductivity of so-called soft ferrite particle powder and its stability. By blending, a conductive resin composition having appropriate conductivity and flexural modulus is obtained, and the conductive roll using the resin composition stabilizes the charging voltage on the photoreceptor surface at an appropriate level, The inventors have found that they have excellent grinding accuracy, and have reached the present invention.
[0007]
That is, the conductive resin composition according to claim 1 of the present invention is composed of 30 to 70% by volume of a soft ferrite particle powder and 70 to 30% by volume of a resin, and has a volume resistivity of 1.0 × 10 1 to 10%. It is characterized by 5.5 × 10 4 Ω · m and a flexural modulus of 5.0 × 10 9 to 8.0 × 10 11 Pa.
[0008]
In the conductive resin composition according to claim 2 of the present invention, the soft ferrite particles are at least one selected from Ni-Mn-Zn ferrite particles, Ni-Zn ferrite particles, and Mn-Zn ferrite particles. It is characterized by the following.
[0009]
In the conductive resin composition according to claim 3 of the present invention, the soft ferrite particles are composed of Ni-Zn ferrite particles and Mn-Zn ferrite particles, and the Ni-Zn ferrite particles and the Mn-Zn ferrite particles are mixed. The weight ratio is from 0: 100 to 80:20.
[0010]
The conductive resin composition according to claim 4 of the present invention is characterized in that the soft ferrite particles have an average particle diameter of 1.0 to 9.0 μm by a sub-sieve sizer method.
[0011]
The conductive resin composition according to claim 5 of the present invention is characterized in that it does not substantially contain soft ferrite particles exceeding 75 μm and / or aggregates thereof.
[0012]
The conductive resin composition according to claim 6 of the present invention is characterized in that soft ferrite particles are surface-treated with a coupling agent.
[0013]
The conductive resin composition according to claim 7 of the present invention is characterized in that the resin is made of a resin selected from polyamide 12 resin and polyphenylene sulfide resin (PPS).
[0014]
The conductive resin composition according to claim 8 of the present invention is in the form of a pellet.
[0015]
A conductive roll according to a ninth aspect of the present invention is characterized by being formed from a conductive resin composition.
[0016]
A conductive roll according to a tenth aspect of the present invention is characterized in that a conductive resin composition is disposed on an outer periphery of a metal shaft core.
[0017]
According to a method of manufacturing a conductive roll according to claim 11 of the present invention, a conductive resin composition is supplied to an injection molding machine, a metal shaft is mounted in a cavity of a mold, and a conductive resin is formed around the shaft. The composition is injection molded.
[0018]
A method of manufacturing a conductive roll according to a twelfth aspect of the present invention is characterized in that a conductive resin composition in the form of a pellet is used.
[0019]
In the method for producing a conductive roll according to claim 13 of the present invention, a powdery conductive resin composition is supplied to a kneading machine, and the kneaded and melted resin composition is guided to a cylinder portion of an injection molding machine. A metal shaft is mounted in the cavity, and a conductive resin composition is injection-molded around the shaft.
[0020]
BEST MODE FOR CARRYING OUT THE INVENTION
The conductive resin composition according to the present invention comprises 30 to 70% by volume of soft ferrite particle powder and 70 to 30% by volume of resin, and has a volume resistivity of 1.0 × 10 1 to 5.5 × 10 4. Ω · m, and a flexural modulus of 5.0 × 10 9 to 8.0 × 10 11 Pa.
[0021]
In the present invention, the conductivity is evaluated based on the reciprocal of the volume resistivity. Those with low conductivity have high volume resistivity, and those with high conductivity have low volume resistivity.
[0022]
The soft ferrite particle powder used in the present invention includes, for example, Ni-Mn-Zn ferrite particle powder, Ni-Zn ferrite particle powder, Mn-Zn ferrite particle powder, and the like, alone or in combination of two or more. Used. These are characterized by having relatively high conductivity and being chemically stable as compared with other metal oxides.
[0023]
The Ni—Mn—Zn ferrite particle powder has a main component of Fe 2 O 3 , NiO, MnO, ZnO, and a molar ratio of each metal oxide of 52 ± 11%, 15 ± 10%, 5 ± 2%, and 28 ± 11%, which is a ferrite particle powder in which a metal such as Cu, Mg, Bi, Si, Ca as a sub-component is added as an oxide in an amount of about 0 to 4% by weight, respectively. -It is preferable from the viewpoint of controlling the volume resistivity that the powder is produced by a method for producing Zn ferrite particle powder.
[0024]
The Ni-Zn ferrite particle powder has a main component of Fe 2 O 3 , NiO, ZnO, and a molar ratio of each metal oxide of 50 ± 11%, 19 ± 11%, and 31 ± 11%. Is a ferrite particle powder in which metals such as Cu, Mg, Bi, Si, Ca, and B are added as oxides in an amount of about 0 to 6% by weight, respectively, and is manufactured by an ordinary method for manufacturing Ni-Zn ferrite particle powder. It is preferable to control the volume resistivity.
[0025]
In the Mn-Zn ferrite particles, the molar ratios of the metal oxides of the main components Fe 2 O 3 , MnO, and ZnO are 53 ± 11%, 32 ± 11%, and 15 ± 8%, respectively. Ferrite particle powder in which a metal such as Si, Mg, Ca, Cu, B, Bi or the like is added as an oxide in an amount of about 0 to 2% by weight, respectively, and is manufactured by an ordinary method for manufacturing Mn-Zn ferrite particle powder. It is preferable to control the volume resistivity.
[0026]
Since the Ni-Zn ferrite particle powder has lower conductivity than the Mn-Zn ferrite particle powder, by combining with the Mn-Zn ferrite particle powder having high conductivity, a conductive material having desired conductivity and flexural modulus can be obtained. Can be designed.
The weight ratio between the Ni-Zn ferrite particles and the Mn-Zn ferrite particles is preferably from 0: 100 to 80:20. More preferably, it is 0: 100 to 75:25, and still more preferably, it is 5:95 to 75:25. If the proportion of the Ni-Zn ferrite particle powder weight exceeds 80%, the volume resistivity is increased and the chargeability (electric conductivity) tends to deteriorate, which is not preferable.
[0027]
The particle diameter of the soft ferrite particle powder is determined by the state of particle growth and sintering specific to the component composition at the time of production and crushing conditions, but it is preferable to design in consideration of the kneadability with the resin.
From such a viewpoint, the average particle size of the soft ferrite particle powder is preferably from 1.0 to 9.0 μm, more preferably from 1.5 to 8.0 μm, according to a sub-sieving sizer method.
[0028]
If the average particle size of the soft ferrite particle powder is less than 1.0 μm, it is not easy to disperse the ferrite particle powder in the resin. On the other hand, if the average particle size exceeds 9.0 μm, some large particles are mixed. In addition, a distribution occurs in which the conductivity of the portion where the large particles are present and the other portion are relatively different, which is not preferable.
[0029]
In order to improve the dispersibility in the resin, the particle diameter of the soft ferrite particles to be dispersed is preferably several μm or more. However, it is preferable that the particle size is small in order to ensure the uniformity of the conductivity of the molded product. As one means for solving this contradictory phenomenon, when two or more kinds of soft ferrite particles are used in combination, as described above, the conductivity is relatively large, and the contribution of conductivity to the molded product is large. The Zn ferrite particles are relatively small, and the Ni-Zn ferrite particles that contribute relatively little to the conductivity are preferably designed to be relatively large.
[0030]
Further, substantially removing giant particles or aggregates exceeding 75 μm is effective for the above-mentioned uniformity of conductivity. Further, as described later, when grinding the surface of the molded body, it is particularly effective in practice that small and small partial defects (loss of ferrite particle powder) are small. By using an air classifier or passing through a sieve having a mesh size of 75 μm or less, the content of these huge particles or agglomerates can be reduced to a practically acceptable content, that is, approximately 0.3% by weight or less. Can be reduced.
[0031]
In order to satisfy the conductivity of the object of the present invention, in addition to Ni-Mn-Zn ferrite particles, Ni-Zn ferrite particles and Mn-Zn ferrite particles, for example, water or silicon oxide or barium titanate or the like There is no problem in adding a small amount of a filler that is stable to air (oxygen) as appropriate.
[0032]
One of the important characteristics of a conductive roll is to ensure the stability of the conductivity, especially the stability against the influence of moisture. The soft ferrite particle powder used in the present invention is physically and chemically stable to moisture and moisture, but it is preferable to use a coupling agent after treating the particle surface. By coating the surface of the soft ferrite particles with the coupling agent, not only the dispersion of the ferrite particles can be made uniform, but also the effect of moisture on the conductivity of the conductive roll can be minimized.
[0033]
As the coupling agent, a commercially available silane-based coupling agent, titanate-based coupling agent, and the like are effective, and in particular, a silane coupling agent having an amino group such as A-1120 manufactured by Nippon Unicar Co., Ltd. is compared. It is suitable in that it is relatively inexpensive and has excellent kneading properties with resin. These coupling agents are usually used in an amount of 0.1 to 0.9 parts by weight based on 100 parts by weight of the soft ferrite particle powder. When the treatment amount of the coupling agent is less than 0.1 part by weight, the above-mentioned treatment effect is not sufficient. On the other hand, when the treatment amount exceeds 0.9 part by weight, the danger of unadsorbed components oozing on the surface of the kneaded material increases.
[0034]
As the resin used in the present invention, a resin that gives a molded body having a flexural modulus of 5.0 × 10 9 to 8.0 × 10 11 Pa when a resin composition with soft ferrite particle powder is used. Is used. Suitable examples of such a resin include polyamide resins such as polyamide 6 and polyamide 12, polyolefin resins such as polyethylene and polypropylene, liquid crystal resins, and polyphenylene sulfide resins (PPS). Used in combination. Even if the resin has a relatively low elastic modulus such as an ethylene vinyl acetate resin (EVA), an ethylene ethyl acrylate resin (EEA), or another elastomer, the bending elastic modulus as a resin composition with the soft ferrite particle powder is also considered. Is 5.0 × 10 9 to 8.0 × 10 11 Pa.
[0035]
Further, from the viewpoint of reliability against humidity, a thermoplastic resin having low hygroscopicity, that is, a polyamide 12 resin, a polyphenylene sulfide resin (PPS), or the like is particularly suitable. Polyamide 12 resin is selected from the viewpoint of both humidity reliability and moldability / productivity, and polyphenylene sulfide resin (PPS) is selected from the viewpoint of humidity reliability.
[0036]
The conductive resin composition of the present invention comprises 30 to 70% by volume of soft ferrite particle powder and 70 to 30% by volume of resin. If the soft ferrite particle powder exceeds 70% by volume, kneading and molding are difficult, and if it is less than 30% by volume, the flexural modulus becomes too low and the shape is easily deformed. Grinding accuracy cannot be secured. It is preferably at least 35% by volume. Further, when a soft resin such as an ethylene ethyl acrylate resin is used, the content is preferably 40% by volume or more.
[0037]
The conductive resin composition of the present invention can further contain processing aids, stabilizers, and other various additives commonly used in this type of conductive resin composition. As a processing aid, a lubricant such as Amide-6S manufactured by Kawaken Fine Chemical Co., Ltd. is preferable. A suitable amount of the processing aid is 0.01 to 0.3% by weight. When the amount of the processing aid is less than 0.01% by weight, a sufficient effect cannot be expected. On the other hand, when the amount exceeds 0.3% by weight, the diffusion and seepage of the lubricant to the roll surface increases, which adversely affects the charging. There are cases.
[0038]
The conductive resin composition of the present invention can be kneaded and granulated by a usual method to obtain so-called pellets. Specifically, a resin is added in an amount of 70 to 30% by volume to 30 to 70% by volume of soft ferrite particles, and if necessary, additives such as processing aids are added, kneaded and melted, and a strand extruded from a die is extruded. Is cut to a length of several millimeters.
[0039]
The conductive resin composition of the present invention is particularly suitable as a conductive roll, and can be formed into a conductive roll by various molding methods.
For example, a conductive roll can be formed by injecting the pellet-shaped conductive resin composition into a mold cavity by a normal injection molding method. By mounting a metal shaft core in the cavity in advance, the conductive roll can be easily formed by the shaft core insert injection molding method. The surface of the shaft core may be plated in advance, and may be subjected to a surface treatment if necessary.
[0040]
In addition, the powdery conductive resin composition is supplied to a kneading machine, kneaded at a predetermined temperature, and the molten resin composition is led to a cylinder portion of an injection molding machine in a molten state. A conductive roll can be formed by mounting a metal shaft core and injection-molding a conductive resin composition around the shaft core. In the present molding method, since the time for continuously maintaining the molten state of the resin is long, the resin temperature becomes uniform and the injection molding is stabilized, so that a conductive roll having stable characteristics can be obtained.
[0041]
Furthermore, the present molding method does not necessarily require a processing aid such as a lubricant in the same amount as when plasticizing and molding pellets by an injection molding machine. Can be reduced. Furthermore, since the present molding method can omit the pelletizing step, there is an advantage that the productivity is high and the production cost is reduced.
[0042]
The conductive roll according to the present invention obtained as described above has a volume resistivity of 1.0 × 10 1 to 5.5 × 10 4 Ω · m.
If the volume resistivity is less than 1.0 × 10 1 Ω · m, sufficient charging cannot be performed due to the leakage of the charge on the photoconductor and the charge holding member when the conductive roll contacts, while the volume resistivity is 5. If it exceeds 5 × 10 4 Ω · m, insufficient charging will occur on the photoreceptor or the charge holding member, and sufficient charging will not be possible. A preferable volume resistivity is 1.0 × 10 2 to 5.0 × 10 4 Ω · m.
[0043]
Since the conductive roll directly charges the photosensitive member or the charge holding member, high precision is required for its dimensions and shape. For this purpose, it is necessary to grind the outer peripheral surface of the conductive roll as necessary. However, in the case of a conductive roll having low rigidity such as rubber or foam, the grinding dimensional accuracy is reduced. On the other hand, when the rigidity is high, high dimensional accuracy can be ensured. If the shaft of the conductive roll is made of metal, the grinding dimensional accuracy can be further enhanced.
[0044]
The conductive roll according to the present invention obtained as described above has a bending elastic modulus of 5.0 × 10 9 to 8.0 × 10 11 Pa.
When the flexural modulus is less than 5.0 × 10 9 Pa, as described above, not only the grinding accuracy of the conductive roll cannot be ensured, but also the contact area of the conductive roll increases due to the pressing pressure of the conductive roll, and the conductive roll and the photosensitive roll are exposed to light. The rotation torque of the body etc. increases. In addition, since the conductive roll bends and deforms, the conductivity becomes non-uniform. On the other hand, if the flexural modulus exceeds 8.0 × 10 11 Pa, the contact between the conductive roll and the member to be charged such as the photoreceptor becomes poor, resulting in insufficient charging.
[0045]
【Example】
Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but these do not limit the present invention at all.
In the following description, the volume resistivity, the flexural modulus, and the charging voltage of the photoreceptor surface were measured by the following methods.
[0046]
Volume resistivity:
The obtained pellets were filled in a cylindrical space of φ25 mm, heated to 240 ± 10 ° C., and then pressure was applied in the height direction of the cylinder to prepare a disk-shaped sample having a thickness of about 10 mm. The skin layer (resin-rich layer) was removed by polishing with 1000 sandpaper. The test piece after the surface adjustment was sandwiched between stainless steel flat electrodes having a sectional area of 2.419 × 10 −4 m 2 , a load of 5 N was applied, and the resistance was measured by the Wheatstone bridge method. The applied voltage was DC 20V.
[0047]
Flexural modulus:
It conformed to ASTM-D790.
[0048]
Charge voltage on photoconductor surface:
The above-described conductive roll was inserted into a printer of a laser beam printer (Model F9682E2) manufactured by Fujitsu Ltd., 600 to 700 V was applied to the shaft, and the surface potential on the photoreceptor was measured with a surface voltmeter.
[0049]
Examples 1 to 5
Ni-Zn ferrite particle powder (trade name: BSN-714, manufactured by Toda Kogyo Co., Ltd.) having an average particle diameter of 6.0 μm by sub-sieve sizer method, and Mn—Zn ferrite particle powder having an average particle diameter of 3.2 μm by sub-sieve sizer method (Toda Kogyo Co., Ltd., trade name BSF-547) at a predetermined weight ratio to make a total of 100 parts by weight, and 0.5 parts by weight of an amino group-containing silane coupling agent (Nihon Unicar Co., Ltd., trade name A- 1120), and 0.2 parts by weight of a lubricant (Amide-6S manufactured by Kawaken Fine Chemical Co., Ltd.) and a predetermined amount of powder of polyamide 6 resin (P1010 manufactured by Ube Industries, Ltd.) are added. The mixture was melted and kneaded with a biaxial kneader of φ25 mm controlled at 240 ° C. ± 10 to obtain a conductive resin composition composed of rice-sized pellets.
[0050]
The pellets were injection-molded around a metal core equipped with a metal shaft (shaft) using a usual injection molding machine (shaft core insert injection molding) to obtain a conductive roll.
[0051]
Example 6
Each of the Ni-Zn ferrite particle powder and the Mn-Zn ferrite particle powder was previously sieved to remove particles and agglomerates exceeding 75 µm, and the content thereof was reduced to 0.3% by weight or less. Using a mixture of 55 parts by weight and 45 parts by weight in the same manner as described above, a mixture of ferrite particle powder and resin is prepared so that the content of ferrite particle powder becomes 60% by volume, and then melted and kneaded to form a pellet. A conductive resin composition was obtained. The flexural modulus of the obtained pellets was about 1.2 times (1.7 × 10 10 Pa) of Example 4, and when the surface of the shaft insert conductive roll was ground, the surface was roughened by giant particles and aggregates. Almost no defects such as cracks and small chips were found. The charging voltage on the photoreceptor surface was stable at 655 ± 15V.
[0052]
Example 7
A conductive resin composition comprising a mixture of a ferrite particle powder and a resin obtained in the same manner as in Example 6 was melted and kneaded by a kneader (TEX30, manufactured by Nippon Steel Works), and the resin composition was kept in a molten state. In this manner, the mixture was guided to a cylinder of an injection molding machine (J350EX, manufactured by Nippon Steel Works), and a shaft insert conductive roll was obtained by ordinary shaft insert injection molding. In this method, the conductive roll can be obtained in a simplified process directly from the powder composition without passing through the state of pellets, which was extremely efficient.
[0053]
Examples 8 to 9
The Mn-Zn ferrite particle powder and the Ni-Zn ferrite particle powder are each in a predetermined weight ratio, the soft ferrite particle powder content is each a predetermined volume%, and an ethylene ethyl acrylate resin (EEA resin; Flex 702) was used, and a shaft core insert conductive roll was obtained in the same manner as in Examples 1 to 5, except that Sunwax 171P (trade name, manufactured by Sanyo Chemical Industries, Ltd.) was used as a lubricant.
[0054]
Example 10
A shaft core insert conductive roll was produced in the same manner as in Example 7, except that a polyamide 12 resin (trade name: A1709P, manufactured by Daicel Corporation) was used as the resin, and the ferrite content was changed without performing the coarse particle removing operation. Got.
[0055]
Examples 11 to 12
As the resin, the polyamide resin 12 and the polyphenylene sulfide resin (PPS resin, Toray M-3910) used in Example 10 were respectively used, and as the lubricant, amide 6S or sun wax 171P was used, respectively. A shaft core insert conductive roll was obtained by the method.
[0056]
Examples 13 to 14
A shaft core insert conductive roll was obtained in the same manner as in Examples 1 to 5, except that the particle diameters of the Mn-Zn ferrite particle powder and the Ni-Zn ferrite particle powder were respectively changed. The conductive roll of Example 13 has a relatively large soft ferrite particle powder, and thus tends to have a large variation in charging voltage. On the other hand, in Example 14, since the soft ferrite particle powder was relatively small, dispersion was difficult and the variation in charging voltage was large. It is considered that both are due to the influence of disturbance of the microscopic uniformity of the conductive roll composition.
[0057]
Example 15
A shaft core insert conductive roll was obtained in the same manner as in Examples 1 to 5, except that the weight ratio between the Ni-Zn ferrite particle powder and the Mn-Zn ferrite particle powder was changed to 80:20. The obtained conductive roll had a slightly higher volume resistivity and a slightly lower charging voltage on the photoreceptor surface.
[0058]
Example 16
Instead of a mixture of Mn-Zn ferrite particle powder and Ni-Zn ferrite particle powder, Ni-Mn-Zn ferrite particle powder (Fe 2 O 3 , NiO, MnO, ZnO, the molar ratio of each metal oxide is Except for using 52%, 15%, 5%, and 28%), a shaft core insert conductive roll was obtained in the same manner as in Examples 1 to 5.
[0059]
Comparative Examples 1-2
An attempt was made to obtain a shaft core insert conductive roll in the same manner as in Example 4, except that the content of the soft ferrite was changed to 74% by volume and 25% by volume, respectively. Since it was too high, the viscosity was so high that kneading with the resin was impossible. On the other hand, in Comparative Example 2, since the content of the soft ferrite particle powder was too low, the flexural modulus was too low. As a result, the obtained shaft-insert conductive roll had poor grinding accuracy and was of poor practicality.
[0060]
Tables 1 and 2 summarize the results of Examples 1 to 16 and Comparative Examples 1 and 2 described above.
[0061]
[Table 1]
[Table 2]
【The invention's effect】
As described above, the conductive resin composition of the present invention has appropriate conductivity and flexural modulus, and is particularly useful for a conductive roll. The conductive roll made of the conductive resin composition of the present invention has stable and uniform conductivity and can ensure the grinding accuracy of the conductive roll. Further, according to the conductive resin composition of the present invention, the conductive roll can be obtained by an injection molding method, and further, the conductive roll can be directly injection-molded from a powdery resin composition without passing through a pellet. Thereby, the production can be performed by an inexpensive method with a simplified process.
Claims (13)
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2013046434A1 (en) * | 2011-09-30 | 2013-04-04 | Ｊｘ日鉱日石エネルギー株式会社 | Benzoxazine resin composition, and fiber-reinforced composite material |
| JP2017167200A (en) * | 2016-03-14 | 2017-09-21 | 株式会社金陽社 | Semiconductive resin roll |
| CN109651815A (en) * | 2018-12-26 | 2019-04-19 | 聚威工程塑料(上海)有限公司 | A kind of PPS composite material and preparation method of high fluidity high metal filling |
-
2002
- 2002-11-06 JP JP2002322396A patent/JP4265202B2/en not_active Expired - Lifetime
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2013046434A1 (en) * | 2011-09-30 | 2013-04-04 | Ｊｘ日鉱日石エネルギー株式会社 | Benzoxazine resin composition, and fiber-reinforced composite material |
| JP2017167200A (en) * | 2016-03-14 | 2017-09-21 | 株式会社金陽社 | Semiconductive resin roll |
| CN109651815A (en) * | 2018-12-26 | 2019-04-19 | 聚威工程塑料(上海)有限公司 | A kind of PPS composite material and preparation method of high fluidity high metal filling |
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| JP4265202B2 (en) | 2009-05-20 |
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