JP2004078071A

JP2004078071A - Conductive roller and manufacturing method therefor

Info

Publication number: JP2004078071A
Application number: JP2002241516A
Authority: JP
Inventors: Toshihiro Yamamoto; 山本　敏博; Michihiko Tomita; 富田　充彦; Yuji Onda; 恩田　裕司
Original assignee: Inoue MTP KK; Inoac Corp
Current assignee: Inoac Corp
Priority date: 2002-08-22
Filing date: 2002-08-22
Publication date: 2004-03-11
Anticipated expiration: 2022-08-22
Also published as: JP4124330B2

Abstract

<P>PROBLEM TO BE SOLVED: To provide a conductive roller which has uniform and excellent conductivity and a manufacturing method by which the conductive roller can easily be obtained. <P>SOLUTION: The conductive roller comprises: a conductive shaft 11, a roller body 21 made of an elastic body which is mounted around the outer circumference of the shaft 11 and machined in a roller shape; an outer circumferential conductive elastic layer 31 formed on the outer circumferential surface of the roller body 21 between both the ends along the axis; and end surfaces conductive elastic layers 35 and 36 which are formed on end surfaces of the roller body 21. The end surface conductive layers 35 and 36 have their center sides in contact with the outer circumferential surface 12 of the shaft 11 and their edge sides in contact with the outer circumferential conductive elastic layer 31 nearby the borders between the outer circumferential surfaces and end surfaces of the roller body 21. The outer circumferential conductive elastic layer 31 and end surface conductive elastic layers 35 and 36 are mutually different in volume resistivity. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
この発明は、導電ローラ及びその製造方法に関する。
【０００２】
【従来の技術】
従来、導電性のシャフトの外周に弾性体を設けた導電ローラは、レーザープリンタや複写機などに多用されている。前記導電ローラにおいては、弾性体に導電性を付与して、前記シャフトから弾性体内部を経て弾性体表面に至る導通路を確保していた。
【０００３】
また、従来における導電ローラの製造方法として次のような方法が知られている。まず、弾性体が、ウレタンフォームなどの通気性を有する多孔体の場合には、導電フィラーを含むラテックスなどの導電性液状原料を多孔体に含浸させ、一定の付着量になるように多孔体を絞った後、乾燥させ、さらにその後、カットや研磨により低弾性の導電ローラを製造する方法がある。また、弾性体が、ゴムスポンジのように通気性が低い場合には、カーボンブラックや導電性金属酸化物のような電子伝導性導電フィラーにより所定の電気抵抗値にしたゴム配合物を、加硫成形してロール形状にする製造方法がある。
【０００４】
【発明が解決しようとする課題】
しかし、導電性液状原料を含浸させた後にカットや研磨する方法においては、乾燥や反応等の際に含浸液が多孔体内を重力により下方へ移動し易く、また乾燥の進行にしたがい含浸液が導電フィラーと共に多孔体の表面へ移動し、多孔体の内部と表面付近とで抵抗値が異なるようになる。このようにして得られた多孔体を、その後にカットや研磨して中心に近い部分をローラとしているが、ローラ表面からの位置によって抵抗値が異なり、品質の一定した導電ローラを得難い問題がある。
【０００５】
さらに、その他の問題として、付着量を一定にするための絞り作業の際に、含浸液に含まれていたシリコン系界面活性剤や未反応成分等が溶出し、ラテックス配合液がゲル化したり、溶出物がローラ表面に再付着して、ローラの使用時にローラと接触する感光体表面を汚染するおそれがある。また、絞りを行う方法の場合は、１本のローラ内だけでなく、同一ロット内でのローラ間の抵抗値のばらつきも大きい。このローラ間における抵抗値のばらつきは、多孔体のセルの大きさ、形状、セルを塞ぐように存在するセル膜の残留度合いなどが、ローラ間で均一でないことにも起因すると考えられる。
【０００６】
また、電子伝導性導電フィラーにより所定の電気抵抗値にしたゴム配合物を、加硫成形してローラ形状にする製造方法においては、電子伝導性導電フィラーの配合や分散状態の僅かな変動による導電性の変化を抑え、安定した抵抗値を発現させることが困難であった。また、電子伝導性導電フィラーが弾性体内に安定な導通路（ネットワーク）を形成するような配合領域では、導電ローラの抵抗値が比較的安定して得られる反面、一般に導電ローラに求められる抵抗値よりも低い抵抗値となったり、電子伝導性導電フィラーを大量に含むため、導電ローラの硬度が高くなりすぎたり、伸びが減少するなど、導電ローラに求められる機械的物性から大きく外れてしまう。また、電子伝導性導電フィラーの量を減らすと、混練などの成形条件や配合量の微少変化によって導電ローラの抵抗が大きく変動し、かつロット間のばらつきが大きくなってしまう。また、導電ローラの変形によっても導電ローラ内の導通路が変化するため、ニップ量や回転速度でも抵抗が変わることになる。
【０００７】
この発明は、前記の点に鑑みなされたもので、均一かつ良好な導電性を有する導電ローラと、その導電ローラを容易に得られる製造方法を提供する。
【０００８】
【課題を解決するための手段】
請求項１の発明は、導電性のシャフトと、前記シャフトの外周に装着されてローラ形状に加工された弾性体からなるローラ本体と、前記ローラ本体の軸方向両端間の外周面に形成された外周導電性弾性層と、前記ローラ本体の端面に形成された端面導電性弾性層とよりなって、前記端面導電性弾性層は中心側が前記シャフトの外周面と接触し、縁側が前記ローラ本体の外周面と端面との境界付近で前記外周導電性弾性層と接触していることを特徴とする導電ローラに関する。
【０００９】
請求項２の発明は、請求項１において、前記外周導電性弾性層と前記端面導電性弾性層との体積固有抵抗値が互いに異なることを特徴とする。
【００１０】
請求項３の発明は、請求項１又は２において、前記弾性体が多孔体からなることを特徴とする。
【００１１】
請求項４の発明は、導電性のシャフトの外周に弾性体を装着し、前記弾性体をローラ形状に加工して前記シャフトの外周に前記弾性体からなるローラ本体を形成するローラ本体形成工程と、前記ローラ本体の軸方向両端間の外周面と端面における何れか一方に、電子伝導性導電フィラーを含む液状の高分子組成物を塗布又は浸漬により付着させて第一の付着層を形成する第一付着工程と、前記ローラ本体の外周面と端面における他方に、電子伝導性導電フィラーを含む液状の高分子組成物を塗布又は浸漬により付着させて第二の付着層を形成し、前記ローラ本体の外周面と端面との境界付近で前記第二の付着層を前記第一の付着層に接触させる第二の付着工程と、前記第一及び第二の付着層を乾燥させてそれぞれ導電性弾性層を形成する乾燥工程、とよりなることを特徴とする導電ローラの製造方法に係る。
【００１２】
請求項５の発明は、請求項４において、前記第一付着工程で使用する高分子組成物に含まれる電子伝導性導電フィラーと、前記第二付着工程で使用する高分子組成物に含まれる電子導伝導性フィラーとが互いに異なることを特徴とする。
【００１３】
請求項６の発明は、請求項４又は５において、前記第一付着層から形成された導電性弾性層と前記第二付着層から形成された導電性弾性層との体積固有抵抗値が互いに異なることを特徴とする。
【００１４】
請求項７の発明は、請求項４から６の何れか一項において、前記弾性体が多孔体からなることを特徴する。
【００１５】
【発明の実施の形態】
以下添付の図面に従ってこの発明を詳細に説明する。図１はこの発明の一実施例に係る導電ローラの正面図、図２は図１の断面図である。図１及び図２に示すこの発明の一実施例に係る導電ローラ１０は、導電性のシャフト１１と、前記シャフト１１の外周に設けられたローラ本体２１と、前記ローラ本体２１の外面に形成された外周導電性弾性層３１と端面導電性弾性層３５、３６とからなり、プリンタや複写機等に使用されるものである。
【００１６】
前記導電性のシャフト１１は、前記導電ローラ１０の回転軸となるもので、金属等のような導電性を有する材質からなり、用途に応じたサイズとされる。前記導電性のシャフト１１は前記導電ローラ１０の軸中心（径方向の中心）に位置し、接着剤により前記ローラ本体２１と一体化されている。接着剤は、公知のものが用いられる。
【００１７】
前記ローラ本体２１は、前記シャフト１１の外周に装着されて筒状のローラ形状に切削等で加工された弾性体からなり、多孔体（発泡体）でも非多孔体（無発泡体）でもよいが、多孔体が好ましい。さらに、低硬度の導電ローラが必要とされる場合や、トナーを摩擦帯電したり、トナーを感光体や転写ベルト表面からクリーニングしたりする用途においても、前記ローラ本体２１を構成する弾性体として多孔体が好ましい。
【００１８】
前記ローラ本体２１を構成する弾性体に多孔体が好ましい理由として、次のことが挙げられる。▲１▼前記ローラ本体２１として低硬度のものが容易に得られ、トナーや感光体へのストレスが小さくなったり、前記ローラ本体２１の当接幅（ニップ量）が大きくなったりして、性能の良好な導電ローラが得られる。▲２▼本発明では、前記ローラ本体２１を構成する多孔体の骨格上に連続した導電層が形成されるが、前記多孔体は、入り組んだ多孔体骨格が非多孔体に比べて極めて広い面積を持つため、前記ローラ本体に流れる電流が過度に集中せず、そのために経時後も、電流が流れることによる高分子や電子伝導性フィラーの劣化、ひいてはショートなどの好ましくない現象を避けることができる。▲３▼多孔体は広い表面積を持ち、特に通気性のある多孔体の場合には、多孔体骨格上の導電層で複数の導通経路が合流したり、分岐したりして、導通経路が長く、かつ、抵抗が並列接続的になることで、前記ローラ本体２１の表面と前記導電性のシャフト１１間における部分的な電気抵抗のバラツキを抑制できる。
【００１９】
前記弾性体として多孔体を用いる場合には、密度１０〜５００ｋｇ／ｍ^３、セル数２５〜５０００／２５ｍｍ（ＪＩＳ　Ｋ　６４０１：１９９７規格準拠）のものが好ましい。この範囲の多孔体を用いれば、後述の外周導電性弾性層３１と端面導電性弾性層３５、３６の形成時に前記多孔体からなるローラ本体２１内に外周導電性弾性層３１と端面導電性弾性層３５、３６形成用の液状高分子組成物を含浸し難くでき、ローラ本体２１の表面に外周導電性弾性層３１と端面導電性弾性層３５，３６を形成し易くなるのみならず、前記液状高分子組成物の含浸によって前記ローラ本体２１の弾性が低下するのを防ぐことができる。前記多孔体としては、ウレタンフォームやゴムスポンジ等を挙げることができる。さらに、前記ウレタンフォームの場合、公知の溶解処理等によってセル膜除去が施されたものであってもよい。それに対し前記非多孔体としては、無発泡ゴム等を挙げることができる。なお、前記ローラ本体２１の寸法は、前記導電ローラ１０の用途に応じた値とされる。
【００２０】
前記外周導電性弾性層３１は、前記ローラ本体２１における軸方向Ｘの両端２２，２３間の外周面２４に形成され、また前記端面導電性弾性層３５，３６は、前記ローラ本体２１における端面２５，２６に形成されている。また、前記端面導電性弾性層３５，３６は、縁側（外周側）が、前記ローラ本体２１の外周面２４と端面２５，２６との境界付近で２７，２８前記外周導電性弾性層３１と接触している。さらに前記端面導電性弾性層３５，３６は中心側（前記シャフト１１の挿通部）３７，３８が前記シャフト１１の外周面１２と接触している。このように前記外周導電性弾性層３１及び前記端面導電性弾性層３５，３８が前記ローラ本体２１の外面に形成されることにより、前記導電性のシャフト１１からローラ本体２１の端面２５，２６を通って外周面２４まで導通経路が形成され、前記導電ローラ１０の周方向及び軸方向に対して測定される部分抵抗値が、前記ローラ本体２１内の状態に影響されることなく、バラツキの小さいものとなる。
【００２１】
前記外周導電性弾性層３１と前記端面導電性弾性層３５，３６は、体積抵抗率が１０^−２〜１０^８Ωｃｍ（ＪＩＳ　Ｋ　６９１１：１９９５準拠）であるのが好ましい。さらには、前記端面導電性弾性層３５，３６は前記シャフト１１の外周面１２と直接接触しているのに対し、前記外周導電性弾性層３１は前記シャフト１１の外周面とは直接接触していないため、前記シャフト１１と前記外周導電性弾性層３１間における部分抵抗値のバラツキを小さくして安定した導電性を得るには、前記外周導電性弾性層３１と前記端面導電性弾性層３５，３６との体積固有抵抗値を互いに異ならせるのが好ましい。特には、前記導電性のシャフト１１から離れている前記外周導電性弾性層３１は、前記シャフト１１と直接接触している前記端面導電性弾性層３５，３６よりも体積抵抗率を大にするのが好ましい。
【００２２】
前記外周導電性弾性層３１は、電子伝導性導電フィラーを含む液状高分子組成物を、前記ローラ本体２１の外周面２４に層状に付着させ、また前記端面導電性弾性層３５，３６は、電子伝導性導電フィラーを含む液状高分子組成物を、前記ローラ本体２１の端面２５，２６に層状に付着させ、それぞれ乾燥させることにより形成される。前記外周導電性弾性層３１及び前記端面導電性弾性層３５，３６の厚みは５〜１００μｍ程度とするのが、前記ローラ本体２１の表面弾性を大きく損なわないために好ましい。
【００２３】
前記電子伝導性導電フィラーとしては、カーボンブラックやグラファイトなどの炭素質粒子、銀やニッケルなどの金属粉、酸化スズや酸化チタンあるいは酸化亜鉛などの導電性金属酸化物の単体、あるいは硫酸バリウムなどの絶縁性粒子を芯体にして前記導電性金属酸化物を湿式的に被覆したもの、導電性金属炭化物、導電性金属窒化物、導電性金属ホウ化物などから選ばれる１種又は複数種類の組合せで用いられる。特にコスト面からはカーボンブラックが好ましく、他方導電性制御のし易さからは導電性金属酸化物が好ましい。カーボンブラックと導電性金属酸化物の併用がコストと導電性制御の容易さを両立できるため、より好ましい。さらに、前記外周導電性弾性層３１の体積抵抗率と前記端面導電性弾性層３５，３６の体積抵抗率を異ならせるためには、前記外周導電性弾性層３１を形成する液状高分子組成物に含まれる電子伝導性導電フィラーと、前記端面導電性弾性層３５，３６を形成する液状高分子組成物に含まれる電子伝導性導電フィラーとを、互いに異なるものとして導電性を異ならせるのが好ましい。
【００２４】
前記液状高分子組成物は、弾性体の膨潤を防止して変形を防ぐため、水性のものが好ましい。前記液状高分子組成物としては、水溶性高分子を主成分とするものや、高分子の微粒子をこれに含まれる親水性官能基や添加した界面活性剤により安定化させた、いわゆるラテックスを主成分とするものが好適である。前記ラテックスとしては、天然ゴムラテックス、ブタジエンゴムラテックス、スチレン−ブタジエンゴムラテックス、アクリロニトリル−ブタジエンゴムラテックス、クロロプレンゴムラテックス、アクリルゴムラテックス、ポリウレタンゴムラテックス、ポリエステルゴムラテックス、フッ素ゴムラテックス、シリコーンゴムラテックスなどが利用できる。
【００２５】
前記電子伝導性導電フィラーとラテックスの割合は、電子伝導性導電フィラーの粒径や体積固有抵抗により異なるが、ラテックスの固形分１００重量部に対して電子伝導性導電フィラーが５〜８０重量部となるようにするのが好ましい。なお、前記電子伝導性導電フィラーを含む液状高分子組成物には、粘度調整等のために適量の水が添加されることもある。その他、必要に応じて架橋剤や界面活性剤などの助剤が添加される。
【００２６】
前記導電ローラ１０の製造について説明する。まず、前記導電性のシャフト１１の外周に前記ローラ本体２１を形成するためのローラ本体形成工程を行う。このローラ本体形成工程では、前記導電性シャフト１１の外周面に接着剤を塗布し、前記ローラ本体２１を構成する弾性体に前記導電性のシャフト１１を挿通し、その後に前記弾性体に対してカットや研磨（研削）等を行い、所要サイズの筒状からなる前記ローラ本体２１を形成する。図３はこのようにして得られたローラ本体２１の断面図である。
【００２７】
次に、前記ローラ本体２１の表面に前記外周導電性弾性層３１と前記端面導電性弾性層３５，３６を形成する導電性弾性層形成工程を行う。この導電性弾性層形成工程では、まず、前記ローラ本体２１の軸方向Ｘ両端２２，２３間の外周面２４と端面２５，２６における何れか一方、例えば前記外周面２４に、前記電子伝導性導電フィラーを含む液状の高分子組成物を塗布又は浸漬により付着させて第一の付着層を形成する第一付着工程を行う。
【００２８】
その後、前記ローラ本体２１の外周面２４と端面２５，２６における他方、例えば端面２５，２６に、前記電子伝導性導電フィラーを含む液状の高分子組成物を塗布又は浸漬により付着させて第二の付着層を形成し、前記ローラ本体２１の外周面２４と端面２５，２６との境界付近２７，２８で前記第二の付着層を前記第一の付着層に接触させる第二の付着工程を行う。その際、前記シャフト１１の外周面１２と前記端面２５，２６との境界部２９，３０にも確実に前記液状の高分子組成物を付着させる。
【００２９】
前記電子伝導性導電フィラーを含む液状高分子組成物の付着は、スプレー塗布、ロールコート、浸漬塗布等により行われる。特にスプレー塗布は、前記シャフト１１とローラ本体２１との境界部２９，３０への塗布が容易で、しかも前記ローラ本体２１の表面への塗布を均一に行え、さらに塗布量制御も容易で、塗布後に絞ったりして塗布量を調整する必要がないので、好ましいものである。
【００３０】
次に、前記第一及び第二の付着層を乾燥させて、前記外周導電性弾性層３１と前記端面導電性弾性層３５，３６を形成する乾燥工程を行う。この乾燥工程の終了により、前記シャフト１１の外周面１２と接触した前記端面導電性弾性層３５，３６と前記外周導電性弾性層３１とが接合した一連の導電性弾性層が、前記ローラ本体２１の外面に形成され、図１及び図２に示した前記導電ローラ１０が得られる。
【００３１】
【実施例】
以下、この発明の実施例について、具体的に示す。
・実施例１
導電性のシャフトとして快削鋼製シャフト（外径６ｍｍ、長さ２５０ｍｍ）を用い、そのシャフトの外周面に、エチレン酢酸ビニル系ホットメルト接着剤を厚さ２０μｍ程度となるように塗布する。また、弾性体を構成する多孔体として溶解処理の施されたポリエステル系ウレタンフォーム（密度３０ｋｇ／ｍ^３、セル数５０個／２５ｍｍ、商品名：ＭＦ−５０、イノアックコーポレーション社製）を用い、その弾性体を厚さ１８ｍｍ、幅１８ｍｍ、長さ２４０ｍｍに加工し、このものに直径５ｍｍの貫通孔を形成し、前記貫通孔に前記導電性のシャフトを挿通して接着させ、その後、前記ポリエステル系ウレタンフォームを研削して外径１０ｍｍ、ローラ面長２２５ｍｍのローラ本体を前記シャフトの外周面に形成した。
【００３２】
次に、前記ローラ本体における両端面及び前記両端面から５ｍｍまでの外周面部分を５０μｍのＰＥＴ（ポリエチレンテレフタレート）フィルムで覆ってマスキングし、アクリル系ラテックス（不揮発分約４５％、商品名：ＡＥ３３６、ＪＳＲ社製）１００重量部にカーボンブラック分散液（不揮発分約３８％）５０重量部と、純水５０重量部を配合した電子伝導性導電フィラーを含む第一の液状高分子組成物を、付着量が１．８ｇになるようにギヤポンプ（ＲＩＦ−０．５−０２、ランズバーグ・インダストリー社製）を用いた精密スプレー塗布装置で、前記ローラ本体の外周面に塗布し、第一の付着層を形成した。続いて前記ＰＥＴフィルムを外し、前記ローラ本体の両端部のみに、すなわち、前記ローラ本体における両端面（前記端面とシャフト外周面との境界を含む）及び前記両端面から１０ｍｍまでの外周面部分のみに、アクリル系ラテックス（不揮発分約４５％、商品名：ＡＥ３３６、ＪＳＲ社製）１００重量部に導電性酸化スズ分散液（不揮発分約３０％）５０重量部と、純水２５重量部を配合した電子伝導性導電フィラーを含む第ニの液状高分子組成物を、前記両端部それぞれの付着量が０．２５ｇになるようにギヤポンプ（ＲＩＦ−０．５−０２、ランズバーグ・インダストリー社製）を用いた精密スプレー塗布装置で塗布し、第二の付着層を形成した。その際、前記ローラ本体の外周面端部では、約５ｍｍの幅で前記第一の付着層に前記第二の付着層が重なっている。その後８０℃で６０分間熱風循環乾燥炉により乾燥させて、実施例１の導電ローラを得た。その際、前記第一の付着層は、前記ローラ本体外面の外周導電性弾性層となり、また前記第二の付着層は端面導電性弾性層となる。
【００３３】
なお、前記電子伝導性導電フィラーを含む第一の液状高分子組成物と第二の液状高分子組成物を、それぞれ乾燥厚さが約２０μｍとなるように別途形成して、得られた第一の塗膜（第一の液状高分子組成物から得られたもの）と第二の塗膜（第二の液状高分子組成物から得られたもの）について体積固有抵抗値をＪＩＳＫ　６９１１にしたがい、印可電圧１Ｖにて測定した値は、第一の塗膜が１×１０^２Ωｃｍ、第二の塗膜が５×１０^５Ωｃｍであった。
【００３４】
・実施例２
実施例１におけるポリエステル系ウレタンフォームが溶解処理の施されていない多孔体からなることを除き、実施例１と同様にして、外周導電性弾性層と端面導電性弾性層を形成し、実施例２の導電ローラを得た。
【００３５】
・実施例３
ＥＰＤＭゴム１００重量部に、亜鉛華３重量部、発泡剤としてアゾジカルボンアミド５重量部、発泡助剤０．５重量部、加硫促進剤０．７重量部、イオウ２重量部配合して混練りし、ゴム射出成形機により、型温１６５℃の金型内（内径１４ｍｍの型内に外径５ｍｍの金属芯をセット済み）に射出し、発泡成形を行った。得られた弾性体を、実施例１と同じシャフトに圧入して、研削により外径１０ｍｍ、ローラ面長２２５ｍｍのＥＰＤＭ製ローラ本体を前記シャフトの外周面に形成した。その後、実施例１と同様にして、外周導電性弾性層と端面導電性弾性層を形成し、実施例３の導電ローラを得た。
【００３６】
・実施例４
分子量５０００のポリエーテルポリオール１００重量部に対し、１，４ブタンジオール７．５重量部、ウレタン変性ＭＤＩを５０重量部、シリコン系界面活性剤１．５重量部、触媒として１，８−ジアザビシクロ［５，４，０］ウンデセン−７のトルエンスルホン酸塩０．５重量部、ジブチルスズジラウレート０．００１５重量部を添加した配合物を調製し、前記配合物をオークスミキサーにて乾燥空気を導入しながら泡立てて、外径５ｍｍの金属芯を備えた内径１６ｍｍの金型内に注入し、８０℃で１０分間加熱して硬化させた。これを、実施例１と同じシャフトに圧入した後、研削し、外径１０ｍｍ、ローラ面長２２５ｍｍの機械発泡ウレタンフォームからなるローラ本体を前記シャフトの外周面に形成した。その後、実施例１と同様にして外周導電性弾性層と端面導電性弾性層を形成し、実施例４の導電ローラを得た。
【００３７】
・比較例１
厚さ３０ｍｍのウレタンフォーム（密度３０ｋｇ／ｍ^３、セル数５０個／２５ｍｍ、商品名：ＭＦ−５０、イノアックコーポレーション社製）のシートにシャフトが入る穴を開け、実施例１で用いた前記電子伝導性導電フィラーを含む第一の液状高分子組成物を前記シートに含浸させ、約１０００ｇ／ｍ^２の付着量になるように絞った後、１２０℃で１２０分間乾燥させた。乾燥後の含浸ウレタンフォームに、実施例１と同様にしてシャフトを圧入し、ウレタンフォーム外周を研削して外径１０ｍｍ、ローラ面長２２５ｍｍのウレタンフォームをシャフトの外周に有する比較例１の導電ローラを得た。
【００３８】
・比較例２
実施例４の配合物にさらに電子伝導性導電フィラーとしてカーボンブラック（ケッチェンブラックＥＣ６００ＪＤ、ライオン社製）を３重量部添加し、オークスミキサーにて乾燥空気を導入しながら泡立てて、外径５ｍｍの金属芯を備えた内径１６ｍｍの金型内に注入し、８０℃で１０分間加熱して硬化させた。これを、実施例１と同じシャフトに圧入した後研削して、外径１０ｍｍ、ローラ面長２２５ｍｍの機械発泡ウレタンフォームをシャフト外周に有する比較例２の導電ローラを得た。
【００３９】
・比較例３
実施例４の配合物に、イオン導電剤として、水酸基を持つ４級アンモニウム塩（カチオンＩＮ、日本油脂社製）を３重量部添加し、オークスミキサーにて乾燥空気を導入しながら泡立てて、外径５ｍｍの金属芯を備えた内径１６ｍｍの金型内に注入し、８０℃で１０分間加熱して硬化させた。これを、実施例１と同じシャフトに圧入した後研削して、外径１０ｍｍ、ローラ面長２２５ｍｍの機械発泡ウレタンフォームをシャフト外周に有する比較例３の導電ローラを得た。
【００４０】
前記実施例及び比較例の導電ローラに対して、シャフトの両端に５０ｇずつの荷重をかけ、軸方向に５ｍｍ幅の金属電極を等間隔に９カ所配置して弾性層部分の導電層外周面あるいは比較例では中央部外周面と当接させ、前記シャフトと金属電極の間に１００Ｖの電圧を印可しての電気抵抗値を測定した。その際、シャフトを２０°ピッチで回転させて電極に当接する位置を変えながら、合計（９×３６０°／２０°＝）１６２点で部分抵抗値測定を行い、平均抵抗値を計算した。表１は、２３℃、５５ＲＨにおける測定データである。また、表２は、前記実施例及び比較例を１０℃、１５％ＲＨと２８℃、８５％ＲＨの環境下に２日放置した後、前記と同様に抵抗値を測定した結果である。表３は、各実施例及び比較例から各１０本の導電ローラを抽出し、前記方法で測定した平均抵抗値の平均とその標準偏差を示すものである。
【００４１】
【表１】

【００４２】
【表２】

【００４３】
【表３】

【００４４】
前記比較例１及び比較例２では、部分抵抗に関して導電ローラ１本内のバラツキと、１０本の平均抵抗値のバラツキが大きいことと、比較例３では、１０℃、１５％ＲＨと２８℃、８５％ＲＨの環境下での抵抗差が大きいことが表からわかる。それに対して実施例１〜４は、導電ローラ１本内のバラツキ、１０本の平均抵抗値のバラツキが小さく、また、１０℃、１５％ＲＨと２８℃、８５％ＲＨの環境下での抵抗差も小さいことがわかる。
【００４５】
【発明の効果】
以上図示し説明したように、この発明の導電ローラによれば、均一かつ良好な導電性が得られる効果がある。またこの発明の製造方法によれば、均一かつ良好な導電性を有する導電ローラを簡単に得ることができる効果がある。
【図面の簡単な説明】
【図１】この発明の一実施例に係る導電ローラの正面図である。
【図２】図１の２−２断面図である。
【図３】この発明の一実施例に係るローラ本体の断面図である。
【符号の説明】
１０　導電ローラ
１１　シャフト
１２　シャフトの外周面
２１　ローラ本体
３１　外周導電性弾性層
３５，３６　端面導電性弾性層[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a conductive roller and a method for manufacturing the same.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, conductive rollers provided with an elastic body on the outer periphery of a conductive shaft have been widely used in laser printers, copying machines, and the like. In the conductive roller, a conductive path is provided from the shaft to the surface of the elastic body through the inside of the elastic body by imparting conductivity to the elastic body.
[0003]
Further, the following method is known as a conventional method for manufacturing a conductive roller. First, when the elastic body is a porous body having air permeability such as urethane foam, the porous body is impregnated with a conductive liquid material such as a latex containing a conductive filler, and the porous body is formed so as to have a fixed adhesion amount. There is a method of manufacturing a low-elasticity conductive roller by squeezing, drying, and then cutting or polishing. Further, when the elastic body has low air permeability like a rubber sponge, a rubber compound having a predetermined electric resistance value with an electronic conductive conductive filler such as carbon black or a conductive metal oxide is vulcanized. There is a manufacturing method of forming into a roll shape.
[0004]
[Problems to be solved by the invention]
However, in the method of cutting or polishing after impregnating the conductive liquid material, the impregnating liquid easily moves downward in the porous body due to gravity during drying or reaction, and the impregnating liquid becomes conductive as the drying proceeds. It moves to the surface of the porous body together with the filler, and the resistance value differs between the inside of the porous body and the vicinity of the surface. The porous body obtained in this manner is then cut or polished, and the portion close to the center is used as a roller. However, the resistance value differs depending on the position from the roller surface, and there is a problem that it is difficult to obtain a conductive roller of uniform quality. .
[0005]
Further, as another problem, at the time of squeezing work to keep the adhesion amount constant, the silicon-based surfactant and unreacted components contained in the impregnating solution are eluted, and the latex compounding solution gels, The eluate may adhere to the roller surface again and contaminate the photoreceptor surface that comes into contact with the roller when the roller is used. Also, in the case of the method of performing the drawing, the variation in the resistance value between the rollers within the same lot as well as within one roller is large. It is considered that the variation in the resistance value between the rollers is also caused by the non-uniformity of the size and shape of the cells of the porous body, the degree of residual cell film existing so as to close the cells, and the like.
[0006]
In addition, in a manufacturing method of vulcanizing and molding a rubber compound having a predetermined electric resistance value with an electron conductive conductive filler into a roller shape, a conductive compound due to a slight change in the compounding or dispersion state of the electron conductive conductive filler is used. It was difficult to suppress the change in the properties and develop a stable resistance value. In addition, in a compounding region where the electron conductive conductive filler forms a stable conductive path (network) in the elastic body, the resistance value of the conductive roller can be obtained relatively stably, but the resistance value generally required for the conductive roller can be obtained. Since the conductive roller has a lower resistance value or contains a large amount of the electron conductive conductive filler, the mechanical properties required for the conductive roller are largely deviated, such as the hardness of the conductive roller being too high and the elongation being reduced. In addition, when the amount of the electron conductive conductive filler is reduced, the resistance of the conductive roller greatly changes due to small changes in molding conditions such as kneading and the amount of compounding, and the lot-to-lot variation increases. In addition, since the conduction path in the conductive roller changes due to the deformation of the conductive roller, the resistance also changes with the nip amount and the rotation speed.
[0007]
The present invention has been made in view of the above points, and provides a conductive roller having uniform and good conductivity, and a manufacturing method capable of easily obtaining the conductive roller.
[0008]
[Means for Solving the Problems]
The invention according to claim 1 is formed on a conductive shaft, a roller body which is mounted on the outer periphery of the shaft and is made of an elastic body processed into a roller shape, and an outer peripheral surface between both ends in the axial direction of the roller body. An outer peripheral conductive elastic layer, comprising an end surface conductive elastic layer formed on an end surface of the roller main body, wherein the end surface conductive elastic layer has a center side in contact with the outer peripheral surface of the shaft, and an edge side of the roller main body. The present invention relates to a conductive roller which is in contact with the outer peripheral conductive elastic layer near a boundary between an outer peripheral surface and an end surface.
[0009]
According to a second aspect of the present invention, in the first aspect, the outer peripheral conductive elastic layer and the end surface conductive elastic layer have different volume specific resistance values.
[0010]
According to a third aspect of the present invention, in the first or second aspect, the elastic body is made of a porous body.
[0011]
A roller body forming step of attaching an elastic body to the outer periphery of the conductive shaft, processing the elastic body into a roller shape to form a roller body made of the elastic body on the outer periphery of the shaft, A first adhesive layer is formed by applying or dipping a liquid polymer composition containing an electron-conductive filler on one of the outer peripheral surface and the end surface between both ends in the axial direction of the roller body. A second adhesion layer is formed by applying or dipping a liquid polymer composition containing an electron-conductive filler on the other one of the outer peripheral surface and the end surface of the roller main body; A second adhesion step of bringing the second adhesion layer into contact with the first adhesion layer near the boundary between the outer peripheral surface and the end surface, and drying the first and second adhesion layers to form a conductive elastic material, respectively. Drying to form a layer Extent, and according to the manufacturing method of the conductive roller, wherein become more that.
[0012]
According to a fifth aspect of the present invention, in the fourth aspect, the electron conductive conductive filler contained in the polymer composition used in the first attaching step and the electron contained in the polymer composition used in the second attaching step are contained. The conductive filler is different from the conductive filler.
[0013]
According to a sixth aspect of the present invention, in the fourth or fifth aspect, the volume elastic resistance of the conductive elastic layer formed from the first adhesion layer and the volume elastic resistance of the conductive elastic layer formed from the second adhesion layer are different from each other. It is characterized by the following.
[0014]
According to a seventh aspect of the present invention, in any one of the fourth to sixth aspects, the elastic body is made of a porous body.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a front view of a conductive roller according to an embodiment of the present invention, and FIG. 2 is a sectional view of FIG. A conductive roller 10 according to an embodiment of the present invention shown in FIGS. 1 and 2 is formed on a conductive shaft 11, a roller body 21 provided on an outer periphery of the shaft 11, and an outer surface of the roller body 21. The outer peripheral conductive elastic layer 31 and the end surface conductive

elastic layers

35 and 36 are used for a printer, a copying machine or the like.
[0016]
The conductive shaft 11 serves as a rotating shaft of the conductive roller 10 and is made of a conductive material such as a metal, and has a size suitable for a use. The conductive shaft 11 is located at the axial center (center in the radial direction) of the conductive roller 10 and is integrated with the roller main body 21 by an adhesive. A known adhesive is used.
[0017]
The roller main body 21 is made of an elastic body mounted on the outer periphery of the shaft 11 and cut into a cylindrical roller shape by cutting or the like, and may be a porous body (foamed body) or a non-porous body (non-foamed body). , A porous body is preferred. Further, in the case where a low-hardness conductive roller is required, or in a case where the toner is frictionally charged or the toner is cleaned from the surface of a photoconductor or a transfer belt, a porous body is used as the elastic body constituting the roller body 21. The body is preferred.
[0018]
The reason why the porous body is preferable as the elastic body constituting the roller body 21 is as follows. {Circle around (1)} The roller body 21 can be easily obtained with a low hardness, and the stress on the toner and the photoreceptor is reduced, and the contact width (nip amount) of the roller body 21 is increased. And a conductive roller having a good value is obtained. {Circle around (2)} In the present invention, a continuous conductive layer is formed on the skeleton of the porous body constituting the roller main body 21. Therefore, the current flowing through the roller body is not excessively concentrated, and therefore, even after a lapse of time, deterioration of the polymer and the electron conductive filler due to the current flowing, and thus undesirable phenomena such as short circuit can be avoided. . (3) The porous body has a large surface area. Particularly, in the case of a porous body having air permeability, a plurality of conductive paths are joined or branched by the conductive layer on the porous body skeleton, so that the conductive path is long. In addition, since the resistances are connected in parallel, it is possible to suppress variation in the partial electric resistance between the surface of the roller body 21 and the conductive shaft 11.
[0019]
When a porous body is used as the elastic body, the elastic body preferably has a density of 10 to 500 kg / m ³ and a number of cells of 25 to 5000/25 mm (based on JIS K 6401: 1997 standard). When a porous body in this range is used, the outer peripheral conductive elastic layer 31 and the end surface conductive elastic layer 31 and the end surface conductive

elastic layers

35 and 36 are formed in the roller body 21 made of the porous body. The liquid polymer composition for forming the

layers

35 and 36 can be hardly impregnated, so that not only the outer peripheral conductive elastic layer 31 and the end surface conductive

elastic layers

35 and 36 can be easily formed on the surface of the roller body 21 but also the liquid It is possible to prevent the elasticity of the roller body 21 from decreasing due to the impregnation of the polymer composition. Examples of the porous body include urethane foam and rubber sponge. Furthermore, in the case of the urethane foam, the cell membrane may be removed by a known dissolution treatment or the like. On the other hand, examples of the non-porous body include a non-foamed rubber. The size of the roller main body 21 is a value according to the use of the conductive roller 10.
[0020]
The outer peripheral conductive elastic layer 31 is formed on the outer peripheral surface 24 between both ends 22 and 23 in the axial direction X of the roller body 21, and the end surface conductive

elastic layers

35 and 36 are formed on the end surface 25 of the roller body 21. , 26 are formed. The edge conductive

elastic layers

35 and 36 are in contact with the outer peripheral conductive elastic layer 31 on the edge side (outer peripheral side) near the boundary between the outer peripheral surface 24 of the roller body 21 and the end surfaces 25 and 26. are doing. Further, the end surface conductive

elastic layers

35 and 36 are in contact with the outer peripheral surface 12 of the shaft 11 at the center side (the insertion portion of the shaft 11) 37 and 38. Since the outer peripheral conductive elastic layer 31 and the end surface conductive elastic layers 35 and 38 are formed on the outer surface of the roller main body 21 in this manner, the end faces 25 and 26 of the roller main body 21 are separated from the conductive shaft 11. A conductive path is formed through the conductive roller 10 to the outer peripheral surface 24, and the partial resistance value measured in the circumferential direction and the axial direction of the conductive roller 10 has a small variation without being affected by the state in the roller body 21. It will be.
[0021]
It is preferable that the outer peripheral conductive elastic layer 31 and the end surface conductive

elastic layers

35 and 36 have a volume resistivity of 10 ⁻² to 10 ⁸ Ωcm (based on JIS K 6911: 1995). Further, while the end surface conductive

elastic layers

35 and 36 are in direct contact with the outer peripheral surface 12 of the shaft 11, the outer peripheral conductive elastic layer 31 is in direct contact with the outer peripheral surface of the shaft 11. Therefore, in order to reduce the variation of the partial resistance between the shaft 11 and the outer peripheral conductive elastic layer 31 and obtain stable conductivity, the outer peripheral conductive elastic layer 31 and the end surface conductive elastic layer 35, It is preferable to make the volume resistivity values different from each other. In particular, the outer peripheral conductive elastic layer 31 distant from the conductive shaft 11 has a larger volume resistivity than the end surface conductive

elastic layers

35 and 36 that are in direct contact with the shaft 11. Is preferred.
[0022]
The outer peripheral conductive elastic layer 31 has a liquid polymer composition containing an electron conductive conductive filler adhered to the outer peripheral surface 24 of the roller body 21 in a layered manner. The liquid polymer composition containing the conductive filler is adhered to the end faces 25 and 26 of the roller main body 21 in a layer form, and is formed by drying each. The thickness of the outer peripheral conductive elastic layer 31 and the end surface conductive

elastic layers

35 and 36 is preferably about 5 to 100 μm so that the surface elasticity of the roller main body 21 is not significantly impaired.
[0023]
Examples of the electron conductive conductive filler include carbonaceous particles such as carbon black and graphite, metal powders such as silver and nickel, conductive metal oxides such as tin oxide, titanium oxide and zinc oxide, and barium sulfate. One obtained by wet coating the conductive metal oxide with an insulating particle as a core, a conductive metal carbide, a conductive metal nitride, a conductive metal boride, or a combination of a plurality of types selected from the above. Used. Particularly, carbon black is preferable from the viewpoint of cost, and a conductive metal oxide is preferable from the viewpoint of easy control of conductivity. The combined use of carbon black and a conductive metal oxide is more preferable because both cost and ease of controlling the conductivity can be achieved. Further, in order to make the volume resistivity of the outer peripheral conductive elastic layer 31 different from the volume resistivity of the end surface conductive

elastic layers

35 and 36, the liquid polymer composition forming the outer peripheral conductive elastic layer 31 needs to be formed. It is preferable that the electron conductive conductive filler contained therein and the electron conductive conductive filler contained in the liquid polymer composition forming the end surface conductive

elastic layers

35 and 36 are different from each other so as to have different conductivity.
[0024]
The liquid polymer composition is preferably aqueous in order to prevent swelling and deformation of the elastic body. The liquid polymer composition is mainly composed of a water-soluble polymer as a main component, or a so-called latex in which polymer fine particles are stabilized by a hydrophilic functional group or a surfactant added thereto. Components are preferred. Examples of the latex include natural rubber latex, butadiene rubber latex, styrene-butadiene rubber latex, acrylonitrile-butadiene rubber latex, chloroprene rubber latex, acrylic rubber latex, polyurethane rubber latex, polyester rubber latex, fluorine rubber latex, and silicone rubber latex. Available.
[0025]
The ratio between the electron conductive conductive filler and the latex varies depending on the particle size and volume resistivity of the electron conductive conductive filler, but the electronic conductive conductive filler is 5 to 80 parts by weight based on 100 parts by weight of the solid content of the latex. It is preferred that In addition, an appropriate amount of water may be added to the liquid polymer composition containing the electron conductive conductive filler for viscosity adjustment or the like. In addition, auxiliary agents such as a crosslinking agent and a surfactant are added as necessary.
[0026]
The manufacture of the conductive roller 10 will be described. First, a roller main body forming step for forming the roller main body 21 on the outer periphery of the conductive shaft 11 is performed. In this roller main body forming step, an adhesive is applied to the outer peripheral surface of the conductive shaft 11, the conductive shaft 11 is inserted into the elastic body constituting the roller main body 21, and then the elastic body is The roller main body 21 having a cylindrical shape of a required size is formed by performing cutting, polishing (grinding), and the like. FIG. 3 is a sectional view of the roller body 21 obtained in this manner.
[0027]
Next, a conductive elastic layer forming step of forming the outer conductive elastic layer 31 and the end surface conductive

elastic layers

35 and 36 on the surface of the roller body 21 is performed. In this conductive elastic layer forming step, first, one of the outer peripheral surfaces 24 and the end surfaces 25 and 26 between both ends 22 and 23 in the axial direction X of the roller main body 21, for example, the outer peripheral surface 24 is provided with the electron conductive conductive material. A first adhesion step of forming a first adhesion layer by applying a liquid polymer composition containing a filler by coating or dipping is performed.
[0028]
Thereafter, a liquid polymer composition containing the electron-conductive filler is applied to the other of the outer peripheral surface 24 and the end surfaces 25 and 26 of the roller main body 21 by, for example, application or immersion, thereby forming the second surface. A second adhesion step of forming an adhesion layer and bringing the second adhesion layer into contact with the first adhesion layer near the

boundaries

27 and 28 between the outer peripheral surface 24 and the end surfaces 25 and 26 of the roller body 21 is performed. . At this time, the liquid polymer composition is securely adhered also to boundaries 29 and 30 between the outer peripheral surface 12 of the shaft 11 and the end surfaces 25 and 26.
[0029]
The adhesion of the liquid polymer composition containing the electron conductive conductive filler is performed by spray coating, roll coating, dip coating, or the like. In particular, in the spray coating, the coating is easily performed on the boundary portions 29 and 30 between the shaft 11 and the roller main body 21, and the coating on the surface of the roller main body 21 can be uniformly performed. This is preferable because it is not necessary to adjust the application amount by squeezing later.
[0030]
Next, a drying step of drying the first and second adhesion layers to form the outer conductive elastic layer 31 and the end conductive

elastic layers

35 and 36 is performed. By the end of the drying process, a series of conductive elastic layers in which the end surface conductive

elastic layers

35 and 36 in contact with the outer peripheral surface 12 of the shaft 11 and the outer peripheral conductive elastic layer 31 are joined to the roller body 21 And the conductive roller 10 shown in FIGS. 1 and 2 is obtained.
[0031]
【Example】
Hereinafter, examples of the present invention will be specifically described.
-Example 1
A free-cutting steel shaft (outer diameter 6 mm, length 250 mm) is used as the conductive shaft, and an ethylene vinyl acetate hot melt adhesive is applied to the outer peripheral surface of the shaft so as to have a thickness of about 20 μm. In addition, a polyester urethane foam (density 30 kg / m ³ , number of cells 50/25 mm, trade name: MF-50, manufactured by INOAC CORPORATION) subjected to a dissolution treatment was used as the porous body constituting the elastic body. The elastic body is processed into a thickness of 18 mm, a width of 18 mm, and a length of 240 mm, a through-hole having a diameter of 5 mm is formed in the elastic body, and the conductive shaft is inserted into and adhered to the through-hole. A roller body having an outer diameter of 10 mm and a roller surface length of 225 mm was formed on the outer peripheral surface of the shaft by grinding urethane foam.
[0032]
Next, both end surfaces of the roller body and the outer peripheral surface portion up to 5 mm from the both end surfaces were covered with a 50 μm PET (polyethylene terephthalate) film and masked, and an acrylic latex (non-volatile content: about 45%, trade name: AE336, A first liquid polymer composition containing an electron conductive conductive filler obtained by mixing 50 parts by weight of a carbon black dispersion (about 38% of non-volatile content) with 50 parts by weight of pure water to 100 parts by weight of JSR Corporation is attached. The first adhesive layer is applied to the outer peripheral surface of the roller body by a precision spray applying device using a gear pump (RIF-0.5-02, manufactured by Ransburg Industry Co., Ltd.) so that the amount becomes 1.8 g. Was formed. Subsequently, the PET film is removed, and only at both end portions of the roller body, that is, only at both end surfaces (including the boundary between the end surface and the outer peripheral surface of the shaft) and the outer peripheral surface portion of up to 10 mm from the both end surfaces. 100 parts by weight of acrylic latex (non-volatile content: about 45%, trade name: AE336, manufactured by JSR Corporation), 50 parts by weight of a conductive tin oxide dispersion (non-volatile content: about 30%), and 25 parts by weight of pure water A gear pump (RIF-0.5-02, manufactured by Ransburg Industry Co., Ltd.) was used to apply the second liquid polymer composition containing the obtained electron conductive conductive filler so that the adhesion amount at each of the both ends was 0.25 g. To form a second adhesion layer. At this time, at the end of the outer peripheral surface of the roller body, the second adhesive layer overlaps the first adhesive layer with a width of about 5 mm. Thereafter, the conductive roller was dried at 80 ° C. for 60 minutes in a circulating hot air drying oven to obtain a conductive roller of Example 1. In this case, the first adhesion layer becomes an outer peripheral conductive elastic layer on the outer surface of the roller body, and the second adhesive layer becomes an end surface conductive elastic layer.
[0033]
The first liquid polymer composition and the second liquid polymer composition containing the electron conductive conductive filler were separately formed so that the dry thickness was about 20 μm, respectively. According to JIS K 6911, the volume resistivity of the coating film (obtained from the first liquid polymer composition) and the second coating film (obtained from the second liquid polymer composition) is determined according to JIS K 6911, The value measured at an applied voltage of 1 V was 1 × 10 ² Ωcm for the first coating film and 5 × 10 ⁵ Ωcm for the second coating film.
[0034]
-Example 2
An outer peripheral conductive elastic layer and an end surface conductive elastic layer were formed in the same manner as in Example 1 except that the polyester-based urethane foam in Example 1 was made of a porous body not subjected to a dissolution treatment. Was obtained.
[0035]
-Example 3
To 100 parts by weight of EPDM rubber, 3 parts by weight of zinc white, 5 parts by weight of azodicarbonamide as a foaming agent, 0.5 parts by weight of a foaming aid, 0.7 parts by weight of a vulcanization accelerator, and 2 parts by weight of sulfur are mixed and mixed. The mixture was kneaded, and injected into a mold having a mold temperature of 165 ° C. (a metal core having an outer diameter of 5 mm was set in a mold having an inner diameter of 14 mm) by a rubber injection molding machine to perform foam molding. The obtained elastic body was pressed into the same shaft as in Example 1, and an EPDM roller main body having an outer diameter of 10 mm and a roller surface length of 225 mm was formed on the outer peripheral surface of the shaft by grinding. Thereafter, the outer peripheral conductive elastic layer and the end surface conductive elastic layer were formed in the same manner as in Example 1, and the conductive roller of Example 3 was obtained.
[0036]
-Example 4
For 100 parts by weight of a polyether polyol having a molecular weight of 5,000, 7.5 parts by weight of 1,4-butanediol, 50 parts by weight of urethane-modified MDI, 1.5 parts by weight of a silicon-based surfactant, and 1,8-diazabicyclo [ [5,4,0] Undecene-7 was prepared by adding 0.5 parts by weight of toluenesulfonate and 0.0015 parts by weight of dibutyltin dilaurate to the above mixture while introducing dry air with an Oak mixer. The mixture was foamed, poured into a mold having an inner diameter of 16 mm provided with a metal core having an outer diameter of 5 mm, and cured by heating at 80 ° C. for 10 minutes. This was pressed into the same shaft as in Example 1 and then ground to form a roller body made of mechanically foamed urethane foam having an outer diameter of 10 mm and a roller surface length of 225 mm on the outer peripheral surface of the shaft. Thereafter, the outer peripheral conductive elastic layer and the end surface conductive elastic layer were formed in the same manner as in Example 1, and the conductive roller of Example 4 was obtained.
[0037]
-Comparative example 1
A hole was formed in a sheet of urethane foam having a thickness of 30 mm (density: 30 kg / m ³ , number of cells: 50 cells / 25 mm, trade name: MF-50, manufactured by INOAC CORPORATION) to allow a shaft to enter, and the electron used in Example 1 was cut out. The sheet was impregnated with a first liquid polymer composition containing a conductive conductive filler, squeezed to an adhesion amount of about 1000 g / m ² , and dried at 120 ° C. for 120 minutes. A shaft is press-fitted into the impregnated urethane foam after drying in the same manner as in Example 1, and the outer periphery of the urethane foam is ground to form a conductive roller of Comparative Example 1 having an outer diameter of 10 mm and a roller surface length of 225 mm on the outer periphery of the shaft. Got.
[0038]
-Comparative example 2
To the composition of Example 4, 3 parts by weight of carbon black (Ketjen Black EC600JD, manufactured by Lion Corporation) was further added as an electron conductive filler, and foamed while introducing dry air with an Oaks mixer to give an outer diameter of 5 mm. It was poured into a mold having a metal core and having an inner diameter of 16 mm, and was cured by heating at 80 ° C. for 10 minutes. This was pressed into the same shaft as in Example 1 and then ground to obtain a conductive roller of Comparative Example 2 having a mechanically foamed urethane foam having an outer diameter of 10 mm and a roller surface length of 225 mm on the outer periphery of the shaft.
[0039]
-Comparative example 3
To the composition of Example 4, 3 parts by weight of a quaternary ammonium salt having a hydroxyl group (Cation IN, manufactured by NOF CORPORATION) was added as an ion conductive agent, and the mixture was foamed while introducing dry air with an Oaks mixer. It was poured into a mold having an inner diameter of 16 mm provided with a metal core having a diameter of 5 mm, and was cured by heating at 80 ° C. for 10 minutes. This was pressed into the same shaft as in Example 1 and then ground to obtain a conductive roller of Comparative Example 3 having a mechanically foamed urethane foam having an outer diameter of 10 mm and a roller surface length of 225 mm on the outer periphery of the shaft.
[0040]
A load of 50 g was applied to both ends of the shaft with respect to the conductive rollers of the above Examples and Comparative Examples, and metal electrodes having a width of 5 mm were arranged in nine places at equal intervals in the axial direction. In the comparative example, the electric resistance value was measured by applying a voltage of 100 V between the shaft and the metal electrode while making contact with the outer peripheral surface of the central portion. At that time, the partial resistance value was measured at a total of 162 points (9 × 360 ° / 20 ° =) while rotating the shaft at a pitch of 20 ° to change the position of contact with the electrode, and the average resistance value was calculated. Table 1 shows measurement data at 23 ° C. and 55 RH. Table 2 shows the results of measuring the resistance values of the above Examples and Comparative Examples in the same manner as described above after leaving them in an environment of 10 ° C., 15% RH and 28 ° C., 85% RH for 2 days. Table 3 shows the average of the average resistance values measured by the above method and the standard deviation of ten conductive rollers extracted from each of the examples and comparative examples.
[0041]
[Table 1]

[0042]
[Table 2]

[0043]
[Table 3]

[0044]
In Comparative Examples 1 and 2, variations in the partial resistance within one conductive roller and variations in the average resistance value of the ten rollers were large. In Comparative Example 3, 10 ° C., 15% RH and 28 ° C. It can be seen from the table that the resistance difference under an environment of 85% RH is large. On the other hand, in Examples 1 to 4, the variation within one conductive roller and the variation of the average resistance value of the ten conductive rollers were small, and the resistance in an environment of 10 ° C., 15% RH and 28 ° C., 85% RH was small. It can be seen that the difference is small.
[0045]
【The invention's effect】
As shown and described above, according to the conductive roller of the present invention, there is an effect that uniform and good conductivity can be obtained. Further, according to the manufacturing method of the present invention, there is an effect that a conductive roller having uniform and good conductivity can be easily obtained.
[Brief description of the drawings]
FIG. 1 is a front view of a conductive roller according to an embodiment of the present invention.
FIG. 2 is a sectional view taken along line 2-2 of FIG.
FIG. 3 is a sectional view of a roller body according to one embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Conductive roller 11 Shaft 12 Outer peripheral surface of shaft 21 Roller body 31 Outer peripheral conductive

elastic layers

35, 36 End surface conductive elastic layers

Claims

A conductive shaft (11), a roller body (21), which is mounted on the outer periphery of the shaft and is made of an elastic body processed into a roller shape, and an outer peripheral surface between both axial ends (22, 23) of the roller body; An outer conductive elastic layer (31) formed on (24) and an end conductive elastic layer (35, 36) formed on end surfaces (25, 26) of the roller body (21).
The end surface conductive elastic layers (35, 36) have the center side in contact with the outer peripheral surface (12) of the shaft (11), and the rim side has the outer peripheral surface (24) of the roller body (21) and the end surfaces (25, 26). A conductive roller which is in contact with the outer peripheral conductive elastic layer (31) near a boundary (27, 28) between the conductive roller and the outer peripheral conductive elastic layer (31).

The conductive roller according to claim 1, wherein the outer peripheral conductive elastic layer (31) and the end surface conductive elastic layers (35, 36) have different volume resistivity values from each other.

The conductive roller according to claim 1, wherein the elastic body is formed of a porous body.

A roller body forming step of mounting an elastic body on the outer periphery of the conductive shaft, processing the elastic body into a roller shape to form a roller body made of the elastic body on the outer periphery of the shaft,
A liquid polymer composition containing an electron-conductive filler is applied to one of an outer peripheral surface and an end surface between both ends in the axial direction of the roller body by coating or dipping to form a first adhesive layer. An adhesion process,
On the other of the outer peripheral surface and the end surface of the roller main body, a liquid polymer composition containing an electron conductive conductive filler is applied or immersed to form a second adhesion layer, and the outer peripheral surface and the end surface of the roller main body are formed. A second adhesion step of contacting the second adhesion layer with the first adhesion layer near the boundary with,
A drying step of drying the first and second adhesion layers to form conductive elastic layers, respectively.

The electron conductive conductive filler contained in the polymer composition used in the first attaching step, and the electron conductive conductive filler contained in the polymer composition used in the second attaching step are different from each other. The method for manufacturing a conductive roller according to claim 4.

6. The conductive elastic layer formed from the first adhesive layer and the conductive elastic layer formed from the second adhesive layer have different volume resistivity values from each other. A method for manufacturing a conductive roller.

The method for manufacturing a conductive roller according to claim 4, wherein the elastic body is made of a porous body.