JP2004004393A - Seamless belt and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a seamless belt, which is reduced in mechanical stress due to a difference in hardness from a releasing layer by decreasing the surface of a polyimide belt coming into contact with the releasing layer and whose belt internal part never spoils the mechanical strength that the polyimide belt originally has, and a method for manufacturing the same. <P>SOLUTION: The seamless belt has a single layer consisting principally of a polyimide resin and is characterized in that the Vickers hardness of the belt internal part is 1.1 to 3.0 times larger than the Vickers hardness of a belt external surface part. The method for manufacturing the seamless belt is characterized in that a cylindrical metal mold internal surface is coated with a polyamide acid solution and processes of solvent removal by heating to imide conversion are carried out in one stage on the metal mold internal surface. <P>COPYRIGHT: (C)2004,JPO

Description

（式中、Ｒは４価の有機基であり、芳香族、脂肪族、環状脂肪族、芳香族と脂肪族とを組み合わせたもの、またはそれらの置換された基である）で表される。
【００２４】
テトラカルボン酸二無水物の具体例としては、ピロメリット酸二無水物（ＰＭＤＡ）、３，３’，４，４’−ベンゾフェノンテトラカルボン酸二無水物（ＢＰＤＡ）、３，３’，４，４’−ビフェニルテトラカルボン酸二無水物、２，３，３’，４−ビフェニルテトラカルボン酸二無水物、２，３，６，７−ナフタレンテトラカルボン酸二無水物、１，２，５，６−ナフタレンテトラカルボン酸二無水物、１，４，５，８−ナフタレンテトラカルボン酸二無水物、２，２’−ビス（３，４−ジカルボキシフェニル）プロパン二無水物、ビス（３，４−ジカルボキシフェニル）スルホン二無水物、ペリレン−３，４，９，１０−テトラカルボン酸二無水物、ビス（３，４−ジカルボキシフェニル）エーテル二無水物、エチレンテトラカルボン酸二無水物等があげられる。
【００２５】
一方、ジアミンの例としては、４，４’−ジアミノジフェニルエーテル（ＤＤＥ）、４，４’−ジアミノジフェニルメタン、３，３’−ジアミノジフェニルメタン、３，３’−ジクロロベンジジン、４，４’−ジアミノジフェニルスルフィド、３，３’−ジアミノジフェニルスルホン、１，５−ジアミノナフタレン、ｍ−フェニレンジアミン、ｐ−フェニレンジアミン（ＰＤＡ）、３，３’−ジメチル−４，４’−ビフェニルジアミン、ベンジジン、３，３’−ジメチルベンジジン、３，３’−ジメトキシベンジジン、４，４’−ジアミノフェニルスルホン、４，４’−ジアミノジフェニルスルフィド、４，４’−ジアミノジフェニルプロパン、２，４−ビス（β−アミノ−第三ブチル）トルエン、ビス（ｐ−β−アミノ−第三ブチルフェニル）エーテル、ビス（ｐ−β−メチル−δ−アミノフェニル）ベンゼン、ビス−ｐ−（１，１−ジメチル−５−アミノ−ペンチル）ベンゼン、１−イソプロピル−２，４−ｍ−フェニレンジアミン、ｍ−キシリレンジアミン、ｐ−キシリレンジアミン、ジ（ｐ−アミノシクロヘキシル）メタン、へキサメチレンジアミン、ヘプタメチレンジアミン、オクタメチレンジアミン、ノナメチレンジアミン、デカメチレンジアミン、ジアミノプロピルテトラメチレン、３−メチルへプタメチレンジアミン、４，４−ジメチルヘプタメチレンジアミン、２，１１−ジアミノドデカン、１，２−ビス−３−アミノプロポキシエタン、２，２−ジメチルプロピレンジアミン、３−メトキシヘキサメチレンジアミン、２，５−ジメチルヘキサメチレンジアミン、２，５−ジメチルヘプタメチレンジアミン、２，５−ジメチルヘプタメチレンジアミン、３−メチルへプタメチレンジアミン、５−メチルノナメチレンジアミン、２，１１−ジアミノドデカン、２，１７−ジアミノエイコサデカン、１，４−ジアミノシクロヘキサン、１，１０−ジアミノ−１，１０−ジアミノ−１，１０−ジメチルデカン、１，１２−ジアミノオクタデカン、２，２−ビス〔４−（４−アミノフェノキシ）フェニル〕プロパン、ピペラジン、
Ｈ_２Ｎ（ＣＨ_２）_３Ｏ（ＣＨ_２）_２Ｏ（ＣＨ_２）ＮＨ_２、
Ｈ_２Ｎ（ＣＨ_２）_３Ｓ（ＣＨ_２）_３ＮＨ_２、
Ｈ_２Ｎ（ＣＨ_２）_３Ｎ（ＣＨ_３）_２（ＣＨ_２）_３ＮＨ_２、等があげられる。
【００２６】
前記したテトラカルボン酸二無水物とジアミンを重合反応させる際の溶媒としては適宜なものを用いうるが、溶解性などの点により有機極性溶媒が好ましく用いうる。前記有機極性溶媒の例としては、Ｎ，Ｎ−ジアルキルアミド類が有用であり、例えばこれの低分子量のものであるＮ，Ｎ−ジメチルホルムアミド、Ｎ，Ｎ−ジメチルアセトアミド等があげられる。これらは、蒸発、置換または拡散によりポリアミド酸およびポリアミド酸成形品から容易に除去することができる。また、前記以外の有機極性溶媒として、Ｎ，Ｎ−ジエチルホルムアミド、Ｎ，Ｎ−ジエチルアセトアミド、Ｎ，Ｎ−ジメチルメトキシアセトアミド、ジメチルスルホキシド、ヘキサメチルホスホルトリアミド、Ｎ−メチル−２−ピロリドン、ピリジン、ジメチルスルホキシド、テトラメチレンスルホン、ジメチルテトラメチレンスルホン等があげられる。これらは単独で使用してもよいし、併せて用いても差し支えない。さらに、前記有機極性溶媒にクレゾール、フェノール、キシレノール等のフェノール類、ベンゾニトリル、ジオキサン、ブチロラクトン、キシレン、シクロヘキサン、へキサン、ベンゼン、トルエン等を単独でもしくは併せて混合することもできるが、水の添加は好ましくない。すなわち、水の存在によってポリアミド酸が加水分解して低分子量化するため、ポリアミド酸の合成は実質上無水条件下で行う必要がある。
【００２７】
前記のテトラカルボン酸二無水物（ａ）とジアミン（ｂ）とを有機極性溶媒中で反応させることにより、ポリアミド酸が得られる。その際のモノマ−濃度「溶媒中における（ａ）＋（ｂ）の濃度」は、種々の条件に応じて設定されるが、通常、５〜３０重量％である。また、反応温度は８０℃以下に設定することが好ましく、特に好ましくは５〜５０℃であり、反応時間は約０．５〜１０時間である。
【００２８】
前記反応の進行に伴い、ポリアミド酸溶液の溶液粘度が上昇する。本発明においては、ポリアミド酸溶液のＢ型粘度計における２５℃の粘度は、１〜１０００Ｐａ・ｓに調整し用いうる。
【００２９】
本発明において、導電性を付与するためにポリイミド樹脂に導電性フィラ−を含有させることが好ましい。このためには、前記ポリアミド酸溶液に導電性フィラ−を分散させることが好ましい。
【００３０】
前記導電性フィラ−としては、ケッチェンブラック、チャンネルブラック、ファーネスブラック、アセチレンブラック、グラフトカーボンなどのカーボンブラック；アルミ、銀、銅などの各種金属等の粉末があげられる。前記カーボンブラックは、デグサジャパン株式会社製のＳｐｅｃｉａｌ　Ｂｌａｃｋ４、Ｐｒｉｎｔｅｘ　Ｖ、またはＰｒｉｎｔｅｘ　１４０Ｖ、三菱化学株式会社製のＭＡ１００などが好適に使用できる。
【００３１】
導電性フィラーの配合量は、所望の表面抵抗率を付与するようにフィラーの種類に応じて適宜設定することができる。例えば、カーボンブラックを用いた場合、表面抵抗率（ｌｏｇ（Ω／□））を６〜１４の範囲にするためには、ポリイミド固形分に対して５〜３０重量％程度配合すればよい。
【００３２】
ポリアミド酸溶液中への導電性フィラーの分散方法は、プラネタリミキサ−やビーズミルや３本ロール等の適宜な分散機にて行なうことができる。
【００３３】
次に、このようにして得られたポリアミド酸溶液を用いて、本発明のシームレスベルトの形成方法を説明する。
【００３４】
用いる円筒状金型は、従来からシームレスベルトの製造に用いられているものであればどのようなものでも差し支えなく、ベルトの形状に応じた円筒状金型を用い、その内面に塗布する。金型の材質としては、その耐熱性の観点から、金属、ガラス、セラミック等の各種のものがあげられる。
【００３５】
前記円筒状金型の内面に、前記ポリアミド酸溶液を均一に塗布する。
【００３６】
均一に塗布するには、公知の方法を適用することが可能であり、例えば金型内面にポリアミド酸溶液を塗布した後金型を高速回転させて遠心成型する方式、金型をポリアミド酸溶液に浸潰させて塗布面を弾丸状走行体などにより均一にする方式などがあげられる。
【００３７】
このようにして円筒状金型内面に均一に塗布したポリアミド酸溶液を、加熱することにより溶媒の除去およびイミド転化までの工程を金型内面で１段階で行う。このときの加熱温度は、２５０〜４５０℃であり、３００〜４００℃が好ましい。昇温速度は、１℃／分〜１５℃／分であり、２℃／分〜５℃／分が好ましい。加熱条件をこのような範囲に制御すると、ベルト内面部がベルト外面部よりもビッカース硬度が高いシームレスベルトが得られる。
【００３８】
このようにして得られたポリイミド樹脂製シームレスベルトの厚さは、ベルトの使用目的などに応じて適宜決定しうる。一般には強度や柔軟性等の機械特性などの点により、５〜５００μｍ、就中１０〜３００μｍ、特に２０〜２００μｍの厚さとされる。
【００３９】
また、前記シームレスベルトの製造方法において、ポリイミド樹脂層の外面部にさらに有機材料からなる層を積層するためには、先にポリイミド樹脂層を形成した後、その外周面に有機材料層を積層してもよいが、まず前記円筒状金型内面に有機材料からなる層を形成し、次に、形成された有機材料層上に前記ポリイミド樹脂層を積層することが好ましい。
【００４０】
有機材料からなる層の形成は、用いる有機材料に応じて、適宜公知の方法により行うことができる。例えば、フッ素樹脂層の形成は、フッ素樹脂粒子を含む分散液を金型内面に塗布後、フッ素樹脂の融点以上の温度で加熱することで形成することができる。シリコーンゴム層の形成は、シリコーンゴム溶液等をスプレーコート、ディッピング等で一定の厚みに塗布した後、２０〜２００℃で加熱、放置して硬化させることにより行うことができる。
【００４１】
前記有機材料からなる層の厚さは、適度な離型性または圧着性を発現する上で、フッ素樹脂層では１〜５０μｍが好ましく、５〜４０μｍがより好ましい。シリコーンゴム層では５〜５００μｍが好ましく、１０〜４００μｍがより好ましい。
【００４２】
前記有機材料からなる層に、前記アミド酸溶液を塗布し、前記と同様に加熱による溶媒除去からイミド転化までの工程を前記金型内面で１段階で行うことにより、有機材料層とポリイミド樹脂層とが積層されたシームレスベルトが得られる。
【００４３】
本発明によるシームレスベルトは、従来に準じた各種の用途に用いうる。就中、機械特性や電気特性に優れることにより電子写真記録装置における像の中間転写用のベルトやその中間転写を兼ねた印刷シートの搬送用ベルトなどとして好ましく用いうる。その場合、印刷シートに像を形成する記録剤としても静電気を介し付着できる適宜なものを用いうる。
【００４４】
【実施例】
以下、本発明の構成と効果を具体的に示す実施例などについて説明する。
【００４５】
（実施例１）
１８００ｇのＮ−メチル−２−ピロリドン（ＮＭＰ）中に、乾燥したカーボンブラックＰｒｉｎｔｅｘ　Ｖ（デグサジャパン社製）８４ｇ（ポリイミド固形分に対し１８．７重量％）をボールミルで分散させ、ＮＭＰ−カーボンブラック分散液を得た。このＮＭＰ−カーボンブラック分散液に３，３’，４，４’−ベンゾフェノンテトラカルボン酸二無水物（ＢＰＤＡ）２９４ｇとｐ−フェニレンジアミン（ＰＤＡ）４０ｇを溶解し、窒素雰囲気中において、室温で３時間撹拌しながら反応させて、１００Ｐａ・ｓのカーボンブラックを含有するポリアミド酸溶液を得た。
【００４６】
上記ポリアミド酸溶液ワニスを内径３００ｍｍ、長さ５００ｍｍの円筒金型の内面にディスペンサーで厚さ４００μｍに塗布後、２０００ｒｐｍで５分間回転させ均一な塗布面を得た。次に、２０ｒｐｍで回転させながら、金型の外側より１５０℃の熱風を１５分間あてた後、１５０℃から４００℃まで２℃／分の昇温速度で昇温を行い、更に４００℃で１０分間加熱し、金型内面にて溶媒の除去、脱水閉環水の除去およびイミド転化を行った。その後室温に戻し、金型内面から剥離し、７４〜７６μｍのシームレスベルトを得た。
【００４７】
（実施例２）
１８００ｇのＮ−メチル−２−ピロリドン（ＮＭＰ）中に、３，３’，４，４’−ベンゾフェノンテトラカルボン酸二無水物（ＢＰＴＡ）２９４ｇとｐ−フェニレンジアミン（ＰＤＡ）４０ｇを溶解し、窒素雰囲気中において、室温で３時間撹拌しながら反応させて、１００Ｐａ・ｓポイズのポリアミド酸溶液を得た。上記ポリアミド酸溶液ワニスを用いて、実施例１と同様の方法で、７４〜７６μｍのシームレスベルトを得た。
【００４８】
（比較例１）
実施例１と同様の方法で得た、カーボンブラックを含有するポリアミド酸溶液ワニスを、内径３００ｍｍ、長さ５００ｍｍの円筒金型の内面にディスペンサーで厚さ４００μｍに塗布後、２０００ｒｐｍで５分間回転させ、均一な塗布面を得た。次に、２０ｒｐｍ回転させながら、金型の外側より１５０℃の熱風を１５分間あてた後、１５０℃から２００℃まで２℃／分の昇温速度で昇温を行い、更に２００℃１０分間加熱し、金型内面にて溶媒の除去およびヒートセットを行なう。その後室温に戻し、金型内面より剥離させた中間体ベルトを、外径３００ｍｍの金型外面に挿入する。金型外面に中間体ベルトを挿入した状態で室温から１５０℃で１０分間加熱させた後、１５０℃から４００℃まで２℃／分の昇温速度で昇温を行い、更に４００℃で１０分間加熱し、溶媒の除去、脱水閉環水の除去、及びイミド転化を完了させて、７４〜７６μｍの半導電性シームレスベルトを得た。
【００４９】
（比較例２）
実施例２と同様の方法で得たポリアミド酸溶液を用いて、比較例１と同様の方法で７４〜７６μｍのシームレスベルトを得た。
【００５０】
上記、実施例および比較例で得られたシームレスベルトのビッカース硬度を測定した。測定結果を表１に示す。
【００５１】
（測定方法）
（１）ビッカース硬度
薄膜物性評価装置ＮＨ４０００（ＮＥＣ製）で、微小押し込み硬度を測定し、ビッカース硬度を求めた。すなわち、対稜角８０℃の三角圧子にて、最大押し込み荷重５ｍＮまで押し込んだときの押し込み深さ１μｍの押し込み荷重より、微小押し込み硬度を求めた。
【００５２】
（２）表面抵抗率
実施例１および比較例１で得られたシームレスベルトの表面抵抗率は、以下のように測定した。すなわち、ハイレスタＵＰ、ＭＣＰ−ＨＴＰ１６（三菱化学社製、プローブ：ＵＲ−１００）にて印加電圧１００Ｖ、１０秒後、測定条件２５℃、６０％ＲＨでの表面抵抗率を調べ、常用対数値（ｌｏｇΩ／□）にて示した。
【００５３】
【表１】

表１に示すように、実施例１および実施例２のシームレスベルトは、ベルト外面部に比べ、ベルト内面部のビッカース硬度が１．５倍ほど高くなった。比較例１および比較例２のシームレスベルトは、ベルト外面部とベルト内面部ではビッカース硬度の差がほとんど見られなかった。
【００５４】
（実施例３）
実施例１で得られたポリイミド製シームレスベルトの外周面に、メチルシリコーンゴム（東レ・ダウコーニング社製、ＤＸ３５−２０８３）をスプレー塗布し、１８０℃の熱風循環式炉で３０分加熱硬化させて、均一な厚さ１５０μｍの弾性体層を形成した。
【００５５】
（実施例４）
実施例１で得られたポリイミド製シームレスベルトの外周面に、ＰＦＡ濃度６０％の水性ディスパージョン（デュポン社製、ＴＥ−３３４Ｊ）を均一にスプレーコートし、１００℃で１０分間加熱した後、４００℃で５分間フルキュアを行い、１０μｍのＰＦＡ離型層を形成した。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a polyimide resin seamless belt and a method for manufacturing the same. More specifically, the present invention relates to a belt suitable for a fixing belt, an intermediate transfer belt, a transfer conveyance belt, a transfer and fixing belt, and the like in an electrophotographic recording apparatus, and a method for manufacturing the belt.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, copiers, laser printers, video printers, facsimile machines, multifunction machines thereof, and the like have been known as electrophotographic recording apparatuses for forming and recording an image in an electrophotographic system. In this type of apparatus, in order to avoid a system in which an image formed by a recording agent such as a toner is directly fixed on a print sheet on an image carrier such as a photosensitive drum for the purpose of improving the life of the apparatus, an image carrier is used. An intermediate transfer system in which the upper image is temporarily transferred to an intermediate transfer belt and is fixed on a print sheet has been studied. Further, for the purpose of downsizing the apparatus, a method in which a transfer belt also serves to convey a printing sheet has been studied.
[0003]
[Problems to be solved by the invention]
In the intermediate transfer belt in the image forming apparatus, if the releasability between the intermediate transfer belt and the toner on the belt during secondary transfer is poor, an image is incomplete. Therefore, in order to improve the releasability, a release layer made of silicone or a fluorine-based organic material is formed on the surface of the intermediate transfer belt. Further, in the fixing belt in the image forming apparatus, the layer made of the organic material is useful as a pressure-bonding layer for improving the pressure-bonding property. However, since the polyimide resin is harder than the silicone or fluorine-based organic material forming the release layer, a mechanical stress occurs due to a difference in hardness between the polyimide belt and the release layer, and the release layer is made of polyimide. There is a risk of peeling from the belt.
[0004]
Therefore, an object of the present invention is to reduce the mechanical stress due to the difference in hardness between the release layer and the polyimide belt by lowering the hardness of the surface of the polyimide belt in contact with the release layer, and the inner surface of the belt has the original mechanical strength of the polyimide belt. To provide a seamless belt and a method for manufacturing the same, which do not impair the performance.
[0005]
[Means for Solving the Problems]
The present inventors have found that the above problems can be solved by controlling the heating temperature and the heating rate in the solvent removal and imide conversion steps in the process of producing the polyimide belt, and have completed the present invention.
[0006]
That is, the seamless belt of the present invention is a seamless belt composed of a single layer mainly composed of a polyimide resin, and the Vickers hardness of the inner surface of the belt is 1.1 to 3.0 times higher than the Vickers hardness of the outer surface of the belt. It is characterized by the following.
[0007]
Preferably, the polyimide resin contains a conductive filler, and the belt has a surface resistivity (log (Ω / □)) of 6 to 14.
[0008]
In the seamless belt of the present invention, it is preferable that a layer made of an organic material is further laminated on the outer surface of the single layer.
[0009]
The method for producing a seamless belt according to the present invention is characterized in that a polyamic acid solution is applied to the inner surface of a cylindrical mold, and a process from solvent removal by heating to imide conversion is performed in one step on the inner surface of the mold. .
[0010]
When the seamless belt of the present invention has a layer made of an organic material laminated on the outer surface of the polyimide resin layer, the method for manufacturing the seamless belt includes forming the organic material layer on the inner surface of a cylindrical mold, It is preferable that the polyamic acid solution is applied on the formed organic material layer, and the steps from solvent removal by heating to imide conversion are performed in one step on the inner surface of the mold.
[0011]
[Effects]
According to the seamless belt of the present invention, the Vickers hardness of the outer surface portion of the polyimide resin layer is lower than the Vickers hardness of the inner surface portion, and even when a release layer made of silicone or a fluorine-based organic material is laminated, the difference in hardness of the contact surface is small. Since it is small, it is possible to provide a seamless belt which does not easily cause delamination between layers and does not impair the inherent mechanical strength of the polyimide belt. Also, according to the seamless belt manufacturing method of the present invention, the hardness of the outer surface portion and the inner surface portion of the polyimide resin layer can be appropriately adjusted by performing one step from the solvent removal by heating to the imide conversion on the inner surface of the mold. Thus, the seamless belt as described above can be efficiently manufactured.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
The seamless belt of the present invention is a seamless belt composed of a single layer mainly composed of a polyimide resin, wherein the Vickers hardness of the inner surface of the belt is 1.1 to 3.0 times higher than the Vickers hardness of the outer surface of the belt. Features.
[0013]
The ratio of the Vickers hardness is from 1.1 to 3.1 from the viewpoint of maintaining the mechanical strength of the polyimide resin as a whole belt while reducing the difference in hardness between the outer surface portion of the polyimide resin layer and the layer made of the following organic material. It is 0 times.
[0014]
The Vickers hardness is a value measured by the method described in Examples. In the present invention, the Vickers hardness of the polyimide resin layer is usually 60 or more.
[0015]
In order to use the seamless belt of the present invention as a semiconductive belt, the polyimide resin preferably contains a conductive filler. In this case, in order to have a semiconductive property, the belt has a surface resistivity (log (Ω / □)) of preferably 6 to 14, more preferably 9 to 12. When a seamless belt having such a surface resistivity is used as an intermediate transfer belt or the like, high-quality images can be obtained without toner scattering due to peeling discharge during transfer.
[0016]
In the seamless belt of the present invention, it is preferable that a layer made of an organic material is further laminated on the outer surface of the single layer.
[0017]
As the layer made of an organic material, when the seamless belt of the present invention is used as an intermediate transfer belt in an image forming apparatus, a release layer for improving releasability from toner, or when used as a fixing belt, Examples of the pressure-bonding layer to be improved are exemplified.
[0018]
Examples of the organic material for forming the release layer and / or the pressure-bonding layer include silicone-based and fluorine-based organic materials.
[0019]
As the silicone-based organic material, general-purpose materials can be used, and examples thereof include silicone rubber such as methyl silicone rubber, vinyl methyl silicone rubber, and fluorosilicone rubber. However, since it is necessary to withstand the heating temperature at the time of imide conversion, a material having high heat resistance is preferable.
[0020]
The fluorine-based organic material is not particularly limited as long as it contains a fluorine atom in the molecule. Specifically, polytetrafluoroethylene (PTFE) and its modified products, tetrafluoroethylene-perfluoroalkylvinyl ether copolymer (PFA), tetrafluoroethylene-ethylene copolymer (ETFE), tetrafluoroethylene-hexafluoropropylene Copolymer (FEP), tetrafluoroethylene-vinylidene fluoride copolymer (TFE / VdF), tetrafluoroethylene-hexafluoropropylene-perfluoroalkylvinyl ether copolymer (EPA), polychlorotrifluoroethylene (PCTFE) , Chlorotrifluoroethylene-ethylene copolymer (ECTFE), chlorotrifluoroethylene-vinylidene fluoride copolymer (CTFE / VdF), polyvinylidene fluoride (PVdF), polyvinyl fluoride ( PVF), and PFA is preferred.
[0021]
The method for producing a seamless belt according to the present invention is characterized in that a polyamic acid solution is applied to the inner surface of a cylindrical mold, and the steps from solvent removal by heating to imide conversion are performed in one step on the inner surface of the mold.
[0022]
The polyamic acid solution is prepared by polymerizing substantially equimolar amounts of a tetracarboxylic dianhydride or a derivative thereof and a diamine in a solvent.
[0023]
The tetracarboxylic dianhydride has the following formula:
Embedded image

(Wherein, R is a tetravalent organic group, which is aromatic, aliphatic, cycloaliphatic, a combination of aromatic and aliphatic, or a substituted group thereof).
[0024]
Specific examples of tetracarboxylic dianhydride include pyromellitic dianhydride (PMDA), 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride (BPDA), 3,3 ′, 4, 4′-biphenyltetracarboxylic dianhydride, 2,3,3 ′, 4-biphenyltetracarboxylic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 1,2,5 6-naphthalenetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, 2,2′-bis (3,4-dicarboxyphenyl) propane dianhydride, bis (3 4-dicarboxyphenyl) sulfone dianhydride, perylene-3,4,9,10-tetracarboxylic dianhydride, bis (3,4-dicarboxyphenyl) ether dianhydride, ethylene tetracarboxylic dianhydride And the like.
[0025]
On the other hand, examples of diamines include 4,4'-diaminodiphenyl ether (DDE), 4,4'-diaminodiphenylmethane, 3,3'-diaminodiphenylmethane, 3,3'-dichlorobenzidine, and 4,4'-diaminodiphenyl. Sulfide, 3,3'-diaminodiphenyl sulfone, 1,5-diaminonaphthalene, m-phenylenediamine, p-phenylenediamine (PDA), 3,3'-dimethyl-4,4'-biphenyldiamine, benzidine, 3, 3′-dimethylbenzidine, 3,3′-dimethoxybenzidine, 4,4′-diaminophenylsulfone, 4,4′-diaminodiphenylsulfide, 4,4′-diaminodiphenylpropane, 2,4-bis (β-amino -Tert-butyl) toluene, bis (p-β-amino-tert-butylphenyl) ether, bis p-β-methyl-δ-aminophenyl) benzene, bis-p- (1,1-dimethyl-5-amino-pentyl) benzene, 1-isopropyl-2,4-m-phenylenediamine, m-xylylenediamine P-xylylenediamine, di (p-aminocyclohexyl) methane, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, decamethylenediamine, diaminopropyltetramethylene, 3-methylheptamethylenediamine, 4,4-dimethylheptamethylenediamine, 2,11-diaminododecane, 1,2-bis-3-aminopropoxyethane, 2,2-dimethylpropylenediamine, 3-methoxyhexamethylenediamine, 2,5-dimethylhexamethylene Diamine, 2,5-dimethylhe Tamethylenediamine, 2,5-dimethylheptamethylenediamine, 3-methylheptamethylenediamine, 5-methylnonamethylenediamine, 2,11-diaminododecane, 2,17-diaminoeicosadecane, 1,4-diaminocyclohexane 1,1,10-diamino-1,10-diamino-1,10-dimethyldecane, 1,12-diaminooctadecane, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, piperazine,
H ₂ N (CH ₂ ) ₃ O (CH ₂ ) ₂ O (CH ₂ ) NH ₂ ,
H ₂ N (CH ₂ ) ₃ S (CH ₂ ) ₃ NH ₂ ,
H ₂ N (CH ₂ ) ₃ N (CH ₃ ) ₂ (CH ₂ ) ₃ NH ₂ , and the like.
[0026]
As a solvent for the polymerization reaction between the tetracarboxylic dianhydride and the diamine, an appropriate solvent can be used, but an organic polar solvent is preferably used in view of solubility and the like. As examples of the organic polar solvent, N, N-dialkylamides are useful, and examples thereof include N, N-dimethylformamide, N, N-dimethylacetamide and the like having a low molecular weight. These can be easily removed from polyamic acids and polyamic acid moldings by evaporation, displacement or diffusion. Other organic polar solvents include N, N-diethylformamide, N, N-diethylacetamide, N, N-dimethylmethoxyacetamide, dimethylsulfoxide, hexamethylphosphortriamide, N-methyl-2-pyrrolidone, pyridine Dimethyl sulfoxide, tetramethylene sulfone, dimethyltetramethylene sulfone, and the like. These may be used alone or in combination. Further, cresol, phenol, phenols such as xylenol, benzonitrile, dioxane, butyrolactone, xylene, cyclohexane, hexane, benzene, toluene and the like may be used alone or in combination with the organic polar solvent. Addition is not preferred. That is, since polyamic acid is hydrolyzed to have a low molecular weight by the presence of water, it is necessary to synthesize polyamic acid under substantially anhydrous conditions.
[0027]
By reacting the tetracarboxylic dianhydride (a) with the diamine (b) in an organic polar solvent, a polyamic acid is obtained. The monomer concentration "concentration of (a) + (b) in the solvent" at that time is set according to various conditions, and is usually 5 to 30% by weight. The reaction temperature is preferably set to 80 ° C. or lower, particularly preferably 5 to 50 ° C., and the reaction time is about 0.5 to 10 hours.
[0028]
As the reaction proceeds, the solution viscosity of the polyamic acid solution increases. In the present invention, the viscosity of the polyamic acid solution at 25 ° C. in a B-type viscometer can be adjusted to 1 to 1000 Pa · s before use.
[0029]
In the present invention, it is preferable to include a conductive filler in the polyimide resin in order to impart conductivity. For this purpose, it is preferable to disperse a conductive filler in the polyamic acid solution.
[0030]
Examples of the conductive filler include carbon black such as Ketjen black, channel black, furnace black, acetylene black, and graft carbon; and powders of various metals such as aluminum, silver, and copper. As the carbon black, Special Black4, Printex V, or Printex 140V manufactured by Degussa Japan, MA100 manufactured by Mitsubishi Chemical Corporation, or the like can be suitably used.
[0031]
The amount of the conductive filler can be appropriately set according to the type of the filler so as to give a desired surface resistivity. For example, when carbon black is used, the surface resistivity (log (Ω / □)) may be in the range of 6 to 14 by blending about 5 to 30% by weight with respect to the solid content of polyimide.
[0032]
The method of dispersing the conductive filler in the polyamic acid solution can be performed by a suitable dispersing machine such as a planetary mixer, a bead mill, or a three-roll mill.
[0033]
Next, a method for forming a seamless belt of the present invention using the polyamic acid solution thus obtained will be described.
[0034]
The cylindrical mold to be used may be any one as long as it has been conventionally used for the production of a seamless belt. A cylindrical mold according to the shape of the belt is used, and the inner surface is coated. Examples of the material of the mold include various materials such as metal, glass, and ceramic from the viewpoint of heat resistance.
[0035]
The polyamic acid solution is uniformly applied to the inner surface of the cylindrical mold.
[0036]
In order to apply uniformly, it is possible to apply a known method, for example, a method of applying a polyamic acid solution to the inner surface of the mold, then rotating the mold at a high speed and centrifugally molding the mold, and applying the mold to the polyamic acid solution. There is a method in which the coating surface is made uniform by a bullet-shaped traveling body by immersion.
[0037]
By heating the polyamic acid solution uniformly coated on the inner surface of the cylindrical mold in this manner, the steps from solvent removal to imide conversion are performed in one step on the inner surface of the mold. The heating temperature at this time is from 250 to 450 ° C, preferably from 300 to 400 ° C. The heating rate is 1 ° C./min to 15 ° C./min, preferably 2 ° C./min to 5 ° C./min. When the heating conditions are controlled in such a range, a seamless belt having a Vickers hardness of the inner surface of the belt higher than that of the outer surface of the belt can be obtained.
[0038]
The thickness of the thus obtained polyimide resin seamless belt can be appropriately determined according to the intended use of the belt. Generally, the thickness is 5 to 500 μm, preferably 10 to 300 μm, particularly 20 to 200 μm, in view of mechanical characteristics such as strength and flexibility.
[0039]
Further, in the method for manufacturing a seamless belt, in order to further laminate a layer made of an organic material on the outer surface of the polyimide resin layer, first form a polyimide resin layer, and then laminate an organic material layer on the outer peripheral surface thereof. However, it is preferable that a layer made of an organic material is first formed on the inner surface of the cylindrical mold, and then the polyimide resin layer is laminated on the formed organic material layer.
[0040]
The formation of the layer made of an organic material can be appropriately performed by a known method depending on the organic material to be used. For example, the fluororesin layer can be formed by applying a dispersion containing fluororesin particles to the inner surface of a mold and then heating the dispersion at a temperature equal to or higher than the melting point of the fluororesin. The silicone rubber layer can be formed by applying a silicone rubber solution or the like to a predetermined thickness by spray coating, dipping, or the like, and then heating and leaving at 20 to 200 ° C. to cure.
[0041]
The thickness of the layer made of the organic material is preferably from 1 to 50 μm, more preferably from 5 to 40 μm in the case of the fluororesin layer, in order to exhibit appropriate releasability or press-fitting property. The thickness of the silicone rubber layer is preferably from 5 to 500 μm, more preferably from 10 to 400 μm.
[0042]
The organic material layer and the polyimide resin layer are formed by applying the amic acid solution to the layer made of the organic material, and performing the steps from solvent removal by heating to imide conversion in one step on the inner surface of the mold in the same manner as described above. Is obtained.
[0043]
The seamless belt according to the present invention can be used in various conventional applications. In particular, because of its excellent mechanical properties and electrical properties, it can be preferably used as a belt for intermediate transfer of an image in an electrophotographic recording apparatus or a belt for transporting a print sheet also serving as the intermediate transfer. In that case, a recording material that forms an image on a printing sheet may be any suitable recording material that can be attached via static electricity.
[0044]
【Example】
Hereinafter, examples and the like that specifically show the configuration and effects of the present invention will be described.
[0045]
(Example 1)
In 1800 g of N-methyl-2-pyrrolidone (NMP), 84 g of dry carbon black Printex V (manufactured by Degussa Japan) (18.7% by weight based on the solid content of polyimide) was dispersed by a ball mill, and NMP-carbon black was dispersed. A dispersion was obtained. In this NMP-carbon black dispersion, 294 g of 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride (BPDA) and 40 g of p-phenylenediamine (PDA) were dissolved, and the solution was dissolved in a nitrogen atmosphere at room temperature. The reaction was carried out while stirring for an hour to obtain a polyamic acid solution containing 100 Pa · s carbon black.
[0046]
The polyamic acid solution varnish was applied to the inner surface of a cylindrical mold having an inner diameter of 300 mm and a length of 500 mm with a dispenser to a thickness of 400 μm, and then rotated at 2,000 rpm for 5 minutes to obtain a uniform applied surface. Next, while rotating at 20 rpm, hot air of 150 ° C. was applied from the outside of the mold for 15 minutes, and then the temperature was raised from 150 ° C. to 400 ° C. at a rate of 2 ° C./min. After heating for one minute, removal of the solvent, removal of dehydrated ring-closing water and imide conversion were performed on the inner surface of the mold. Thereafter, the temperature was returned to room temperature, and the mold was peeled off from the inner surface of the mold to obtain a seamless belt of 74 to 76 μm.
[0047]
(Example 2)
In 1800 g of N-methyl-2-pyrrolidone (NMP), 294 g of 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride (BPTA) and 40 g of p-phenylenediamine (PDA) were dissolved. The reaction was carried out in an atmosphere with stirring at room temperature for 3 hours to obtain a polyamic acid solution of 100 Pa · s poise. Using the polyamic acid solution varnish, a seamless belt of 74 to 76 μm was obtained in the same manner as in Example 1.
[0048]
(Comparative Example 1)
A polyamic acid solution varnish containing carbon black obtained in the same manner as in Example 1 was applied to the inner surface of a cylindrical mold having an inner diameter of 300 mm and a length of 500 mm to a thickness of 400 μm with a dispenser, and then rotated at 2,000 rpm for 5 minutes. To obtain a uniform coated surface. Next, while rotating at 20 rpm, hot air of 150 ° C. was applied from the outside of the mold for 15 minutes, and then the temperature was raised from 150 ° C. to 200 ° C. at a rate of 2 ° C./min, and further heated at 200 ° C. for 10 minutes. Then, solvent removal and heat setting are performed on the inner surface of the mold. Thereafter, the temperature is returned to room temperature, and the intermediate belt peeled from the inner surface of the mold is inserted into the outer surface of the mold having an outer diameter of 300 mm. After heating from room temperature to 150 ° C. for 10 minutes with the intermediate belt inserted into the outer surface of the mold, the temperature is raised from 150 ° C. to 400 ° C. at a rate of 2 ° C./min, and further at 400 ° C. for 10 minutes. Heating was performed to complete the removal of the solvent, the removal of the dehydrated ring-closing water, and the imide conversion to obtain a semiconductive seamless belt of 74 to 76 μm.
[0049]
(Comparative Example 2)
Using the polyamic acid solution obtained in the same manner as in Example 2, a seamless belt of 74 to 76 μm was obtained in the same manner as in Comparative Example 1.
[0050]
The Vickers hardness of the seamless belts obtained in the above Examples and Comparative Examples was measured. Table 1 shows the measurement results.
[0051]
(Measuring method)
(1) Vickers hardness The microindentation hardness was measured with a thin film physical property evaluation device NH4000 (manufactured by NEC) to determine the Vickers hardness. That is, the micro indentation hardness was determined from the indentation load of 1 μm in the indentation depth when the indentation was carried out to a maximum indentation load of 5 mN with a triangular indenter having a ridge angle of 80 ° C.
[0052]
(2) Surface resistivity The surface resistivity of the seamless belt obtained in Example 1 and Comparative example 1 was measured as follows. That is, after applying an applied voltage of 100 V for 10 seconds using a Hiresta UP and MCP-HTP16 (produced by Mitsubishi Chemical Corporation, probe: UR-100), the surface resistivity was measured at 25 ° C. and 60% RH under measurement conditions. (logΩ / □).
[0053]
[Table 1]

As shown in Table 1, in the seamless belts of Examples 1 and 2, the Vickers hardness of the inner surface of the belt was 1.5 times higher than that of the outer surface of the belt. In the seamless belts of Comparative Examples 1 and 2, there was almost no difference in Vickers hardness between the outer surface of the belt and the inner surface of the belt.
[0054]
(Example 3)
Methyl silicone rubber (DX35-2083, manufactured by Dow Corning Toray Co., Ltd.) was spray-coated on the outer peripheral surface of the seamless belt made of polyimide obtained in Example 1, and was heated and cured in a hot air circulating furnace at 180 ° C. for 30 minutes. An elastic layer having a uniform thickness of 150 μm was formed.
[0055]
(Example 4)
An aqueous dispersion (TE-334J, manufactured by DuPont) having a PFA concentration of 60% was uniformly spray-coated on the outer peripheral surface of the seamless belt made of polyimide obtained in Example 1 and heated at 100 ° C. for 10 minutes. Full cure was performed at 5 ° C. for 5 minutes to form a 10 μm PFA release layer.

Claims (5)

A seamless belt comprising a single layer mainly composed of a polyimide resin, wherein the Vickers hardness of the inner surface of the belt is 1.1 to 3.0 times higher than the Vickers hardness of the outer surface of the belt. 2. The seamless belt according to claim 1, wherein the polyimide resin contains a conductive filler, and a surface resistivity (log (Ω / □)) of the belt is 6 to 14. 3. A seamless belt obtained by further laminating a layer made of an organic material on the outer surface of the seamless belt according to claim 1. The process for producing a seamless belt according to claim 1 or 2, wherein a polyamic acid solution is applied to the inner surface of the cylindrical mold, and a process from solvent removal by heating to imide conversion is performed in one step on the inner surface of the mold. Method. A layer made of an organic material is formed on the inner surface of a cylindrical mold, and then a polyamic acid solution is applied on the formed organic material layer. The method for producing a seamless belt according to claim 3, wherein the method is performed at a stage.