JP3887115B2

JP3887115B2 - Endless belt forming apparatus and forming method

Info

Publication number: JP3887115B2
Application number: JP34799898A
Authority: JP
Inventors: 稔松尾; 秀樹小松; 亜希子田中
Original assignee: Ricoh Co Ltd
Current assignee: Ricoh Co Ltd
Priority date: 1998-11-24
Filing date: 1998-11-24
Publication date: 2007-02-28
Anticipated expiration: 2018-11-24
Also published as: JP2000158554A

Description

【０００１】
【発明の属する技術分野】
本発明は、円筒状の成形型の内周面に皮膜の前駆体溶液を塗布した後、高速回転の遠心力により膜化させる遠心成形法により膜を形成する無端状ベルトの形成装置及び方法に関し、特に、複写機等の静電複写プロセスに使用する中間転写ベルトの成形工程に関する。
【０００２】
【従来の技術】
複写機、プリンタ、ファクシミリ等の画像形成装置では、感光体を中心として、帯電、現像、転写、及び定着の各プロセスに応じた部品ユニットが配置されている。こうした部品ユニットの多くは、静電複写プロセスを連続的に繰り返す必要から、基本的に回転ベルトや回転ローラが用いられている。
【０００３】
上記回転ローラは、円柱状あるいは円筒状のものでありその製造は比較的簡単である。他方、回転ベルトの製造は、例えばシートの両端を張り合わせて円筒状にする方法が容易であり、またこの方がコストも安価である。しかしこの場合、ベルトに継ぎ目ができるため、プロセス動作中はその継ぎ目部分を避けるようなタイミングをとって回転駆動する必要が生じることとなる。したがって、静電複写プロセスに使用される回転ベルトとしては、無端状のベルト（シームレスベルトやエンドレスベルトとも呼ばれる）が求められきた。
【０００４】
上記無端状ベルトの画像形成装置での実用例としては、熱容量を小さくし消費電力を減らすためのサーフ定着方式のベルトや、カラーの高画質を狙った中間転写ベルト、紙を定着部へ搬送するための搬送ベルト等に多用されている。また、最近では帯電部や現像部にもそのレイアウトの自由度の面から検討されている。
【０００５】
従来、上記無端状ベルトの製造には、その部品形状が円筒状であるため、エンドレス形状を成形可能な円筒状の成形型を使用することになるが、この場合、使用材料の効率等に有利などの理由から、回転する円筒状ワークとしての回転成形型（以下「塗布型」と称する）の内周面に、ベルトの前駆体溶液（以下「塗布液」と称する）をノズルからの流し込むか、スプレーで塗布した後、塗布型の高速回転による遠心力で内周面に流延させ拡げるとともにほぼ均一な膜に平滑化した後、加熱乾燥硬化させる遠心成形法と呼ばれる製法が用いられている。
【０００６】
この遠心成形法では、塗布型の内周面に塗布液を流延させることを特徴としているが、例えば、径の異なったベルトを作製するときは、それに応じた径の塗布型を用意しなければならない。このため塗布液を吐出するノズルの位置等もその都度調整し直さなければならず、段取りに手間がかかるなどの不具合がある。そこで、そのような不具合等に鑑みて本出願人は、円筒型の内部に第２の型として中子型を挿入するだけで膜を平滑化でき、上記調整等の手間を省ける中子成形法を考案した。
【０００７】
【発明が解決しようとする課題】
ところで、一般に、複写機やプリンタ等の静電複写プロセスのトナー担持体として使用されている中間転写ベルトは、駆動ローラと、従動ローラとより回転駆動自在に保持された構成であるが、ベルトの膜厚にばらつきがあると、例えば駆動中にベルトがローラの片側に寄って皺ができたり、ついにはかじって破けてしまったりする。また、膜厚が異なることで部分的に電気抵抗が異なるため、画像の階調性が再現できなかったり、トナーが載らない、いわゆる白抜けが生じたり等の画像品質の劣化をもたらすこととなる。
【０００８】
この膜厚のばらつきの発生原因は、上記塗布型の内周面が真円でなく変形や型振れがあるためで、そのような振れや乾燥加熱中の不均一分布等によって膜厚の制御が一般的に困難なことにある。上記遠心成形法では、塗布型の内周面の振れにより膜厚が変化するので、その振れの制御が重要であるが、この型振れの制御には、精度面での機械的な限界があり、より高精度を追求するにしてもかなりのコストがかかる。
【０００９】
そこで、本発明は、上記中子型を用いた遠心成形法において、簡易な手段により膜厚のバラツキを最小限に抑えることのできる無端状ベルトの形成装置及び形成方法を提供することを目的としている。
【００１０】
【課題を解決するための手段】
上記目的を達成する本発明の無端状ベルトの形成装置は、内周面に塗布された塗布液を遠心力により膜化する円筒状の塗布型と、該塗布型の内部に軸平行に回転自在に備えられ、上記塗布型の内周面上の膜厚を均一化するための中子型とを有する無端状ベルトの形成装置であって、上記中子型が、上記塗布型に従動される回転体を両端に有するとともに、該回転体間でその同軸上に均し部材を支持させたものであり、上記中子型を上記塗布型内に備えて回転させたとき、該塗布型の内周面と、上記均し部材の外表面とが均一な距離を保つことを特徴としている。
【００１１】
上記中子型が、上記塗布型の内周面の下部に載置され、その自重により塗布型に従動回転され、上記均し部材により膜表面へ加重可能な構成とするとよく、また、上記均し部材が、上記両端の回転体に従動されないように回転自在に支持されている構成とするとよい。
【００１２】
上記均し部材が、上記両端の回転体より径の小さい円柱状又は円筒状の成形用コロである構成とすることができ、また、上記均し部材が、上記両端に設けられた回転体間に吊設された成形用ブレードであり、該成形用ブレードが、その自重で鉛直方向を保つことにより、その先端部で膜表面へ加重可能な構成とすることもできる。この場合、上記両端の回転体にころがり軸受で回転自在に支持された軸部材を有し、上記成形用ブレードが、上記軸部材に固定された平板状のものである構成とすることもできる。さらに、上記均し部材が、離型性の材質のもの、又は、少なくとも膜表面へ加重する部分に、塗布液の溶剤に対して離型性の材料を被覆したものであることが望ましい。
【００１３】
上記目的を達成する本発明の無端状ベルトの形成方法は、円筒状の塗布型の内周面に塗布された塗布液を遠心力により膜化した後、上記塗布型の内部に回転自在な中子型を軸平行に載置するとともに塗布型を回転させ、上記中子型により上記塗布型の内周面上の膜を均す無端状ベルトの形成方法であって、上記中子型に、上記塗布型に従動する回転体を両端に設け、該回転体間に均し部材を回転自在に支持させ、該中子型を上記塗布型の内部に載置し回転させたとき、上記均し部材の外表面と、塗布型の内周面との間に均一な距離を保つことを特徴としている。また、この方法において、上記塗布型の内周面に形成された膜が指触乾燥の度合いとなったときに、上記中子型を塗布型に載置することが望ましい。
【００１４】
【作用】
まず、ゆっくり塗布型を回転させながら塗布液を内部に塗布し、所定の液膜厚を得る。この塗布後、高速回転の遠心力により内周面におよそ均一な膜を形成する。この状態で加熱乾燥し、剥離や液だれしない程度の指触乾燥度合としてから回転を止め、塗布型に従動可能な中子型を塗布型内に軸平行に挿入し載置し、再び塗布型を回転させる。この中子型には、塗布型に従動回転される２つの回転体間に同軸上に支持されることにより塗布型の内周面と均一な距離（ニップ）を保つことのできる離型性の均し部材が設けられている。この均し部材を介して厚膜の部分が中子型の加重を受け、加重を受けていない薄膜の部分へ移動（流動変形）する。このため膜の厚みは型振れ等に関係なく確実に均一化される。
【００１５】
【発明の実施の形態】
以下、本発明の一実施例を図面に基づいて説明する。
図１は、本実施例の無端状ベルト形成装置の全体構成を示す断面図である。図２は、図１の中子型２の一端部を示す拡大図である。同図の（ａ）は断面図、（ｂ）は軸方向からみた側面図である。
【００１６】
円筒状の成形型としての塗布型１は、内径１８０ｍｍ、幅７００ｍｍの金型であり、図示しない支持部により高速回転可能に支持されている。中子型２は、塗布型１の内周面の底に軸平行に載置されるもので、塗布型１の内表面に従動される径２０ｍｍの２つの回転体３を左右端部に備えるとともに、これら左右の回転体３の間に均し部材４を上記回転体３に従動されないよう回転フリーに支持した構成である。本実施例では、上記均し部材４として、後述の成形用コロ又は、成形用ブレードを使用している。
【００１７】
図２は、均し部材４として成形用コロ４′を備えた装置の一端部の構成を示しており、同図の（ａ）は断面図、（ｂ）は軸方向からの側面図である。図３は、回転体３の軸受部を示す拡大図である。成形用コロ４′は、長尺の筒形状のもので、その表面が指触乾燥（指で触れても、くっ付いてこない程度）の膜７に対して離型性の部材、又は、離型性の平滑面を被覆することにより塗布液の溶剤に非溶解性となっている。この成形用コロ４′は、クロムメッキ及び樹脂コートした離型性の軸部材である鉄棒５（径１０ｍｍ）の同芯上に固定され、上記回転体３間に支持されている。また、図３に示すように、支持する鉄の棒５は、その両端がころがり軸受としてのボールベアリング６により左右の回転体３に対して回転自在に支持されており、このような鉄の棒５に固定されている成形用コロ４′は、塗布型１に従動して回転される回転体３によって連れ回りされないようになっており、また、回転体３と同軸上に支持され、この回転体３の外径と、成形用コロ４′の外径との差が均一な距離ｈ′としてのニップを常に保つようになっている。
【００１８】
図４は、均し部材４として成形用ブレード４″を備えた装置の要部構成を示しており、同図（ａ）は断面図、（ｂ）は側面図である。成形用ブレード４″は、肉厚ｄが１ｍｍで、その先端と塗布型１の内周面との間で５．９ｍｍの距離ｈ″を保つように軸部材としての鉄の棒５に吊設される。さらに、成形用ブレード４″には、塗布液の溶剤に非溶解性でかつ離型性の部材としてのパープルフルオロエチレン等のＰＴＦＥからなる材料を使用している。この場合、鉄の棒５の軸方向に切り込みが形成されており、その切り込みにＰＴＥＦ製ブレード４″を挟持させている。また、鉄の棒５が回転体３にフリーに支持されており、回転体３が回転されても、鉄の棒５に固定された成形用ブレード４″は、その自重により常に鉛直方向を向くことで距離ｈ″を一定に保つことができる。
【００１９】
上記構成により、成形用コロ４′で形成される距離ｈ′、および成形用ブレード４″で形成される距離ｈ″は、それぞれ膜厚の制御幅としてのスペース（ニップ）となるので、塗布型１の内周面にテープを貼付するなどスペーサを別途に設ける必要はない。
【００２０】
しかも、均し部材４が塗布型１に従動されず一定の姿勢を維持可能であるから、単なる円柱状の中子型（例えば、単なる金属棒）を用いてその全周面により膜７を均す場合と比べ、例えは、その金属棒外表面の異常な凹凸部や膜厚の偏差等の影響を受けにくく、表面の平滑化においてさらに優れたものとなっている。
【００２１】
なお、後に説明する形成工程での平滑化後に、中子型２を搭載したまま加熱硬化を行う場合は、塗布型１のみならず、上記均し部材４等の材質として、約３００℃までの温度に耐熱性があることが要求される。この場合、中子型２にも、例えば無機質で弾性のある材料、一般的にはクロムメッキ、Ｔｉｎ処理、又はＡｕ蒸着した金属、その他フッ素樹脂を被覆した金属を使用してもよい。
【００２２】
つぎに、本実施例の無端状ベルトの形成方法を説明する。塗布型１をゆっくり回転させながら、その内部に、ポリイミド前駆体と導電剤とをＤＭＡＣ（Ｎ，Ｎ′ジメチルアセトアミド）に分散して３０％に希釈した塗布液を注入し、内周面に流延させ、所定の厚みの液膜を形成する。
【００２３】
その後、塗布型１を１０００ｒｐｍで高速回転させ、塗布液を内周面に流延させて拡げ、ほぼ均一の膜７とする。この状態で、溶剤を乾燥させて指で触ってもくっつかない指触乾燥の度合いに固化した後、回転を止め、上記均し部材４を備えた中子型２を塗布型１内に挿入し、所定の位置に載置して再度高速回転を行う。
【００２４】
指触乾燥程度の皮膜７はまだ柔らかであり、再度の高速回転時に均し部材４の加重により膜厚が均一化される。その後に昇温し、膜７を３０分、３００℃の加熱乾燥により硬化させ、冷却後に回転を止める。塗布型１から中子型２を取り出してから、皮膜７を剥離して無端状ベルトを得る。ここで、この皮膜７の膜厚および面粗度を測定し、さらに実際の複写機により性能を評価した。
【００２５】
上記均し部材４を備えた中子型２を用いて作製した場合を実施例１とし、この実施例１と同様の希釈分散液を用いて、中子型２を用いない従来の遠心成形法を比較例１とし、さらに、この比較例１と同様の条件下で、単なる棒状の中子型２を用いて作製した場合を比較例２として、それぞれ得られた無端状ベルトについて、膜厚のバラツキや面粗度等の測定を行った。測定結果を表１に示す。
【００２６】
【表１】

【００２７】
表１に示すように、中子を用いない比較例１は、実施例１あるいは比較例２と比べて最大膜厚と最小膜厚との間に大きな差があり、膜厚のバラツキσおよび面粗度Ｒｚもかなり大きい値となった。これに対し、実施例１は、各測定値について良好な結果が得られ、特に面粗度Ｒｚでは比較例２よりも良好であった。
【００２８】
ベルトの評価にあたっては、各例のサンプルをユニット寸法の長さに切断し、寄り止めのテープを貼り付けて、出願人製造のフルカラー複写機（商品名プリテール）の転写ベルトユニットに取り付けて画出しをしながらベルト耐久性等を評価した。
【００２９】
この評価の結果、比較例１の無端状ベルトを用いた場合には白抜けが発生したが、中子型２を用いて作製した実施例１及び比較例２のベルトでは、ずれも階調性の白抜け等の問題が発生せず、良好な画像が得られた。また、実施例１のベルトは、比較例２と比較しても、階調性が更に良く画像のコントラストも良好であった。
【００３０】
【発明の効果】
以上説明したように、本発明の無端状ベルトの形成装置は、内周面に塗布された塗布液を遠心力により膜化する円筒状の塗布型と、該塗布型の内部に軸平行に回転自在に備えられ、上記塗布型の内周面上の膜厚を均一化するための中子型とを有する無端状ベルトの形成装置であって、上記中子型が、上記塗布型に従動される回転体を両端に有するとともに、該回転体間でその同軸上に均し部材を支持させたものであり、上記中子型を上記塗布型内に備えて回転させたとき、該塗布型の内周面と、上記均し部材の外表面とが均一な距離を保つ構成なので、上記中子型が、上記塗布型の振れに対応して従動回転され、均し部材が塗布型内面と常に一定の距離を保つことができ、型振れに関係なく膜厚を均一化することができる。
【００３１】
上記均し部材が、上記両端の回転体に従動されないように回転自在に支持されている構成によれば、上記均し部材が両端の回転体の回転に束縛されることなく一定の姿勢を維持し、塗布型内面と常に一定の距離を保つことができる。
【００３２】
上記均し部材が、離型性の材質のもの、又は、少なくとも膜表面へ加重する部分に、塗布液の溶剤に対して離型性の材料を被覆した構成によれば、均し部材が、塗布液からの溶剤の吸収や、その溶剤への溶解により変形して膜が均一化できなくなったり、膜中に異成分が溶け込んで膜質が劣化することを防止できる。また、離型性であれば、膜との間の摺動抵抗により膜厚にばらつきが生じることを防止できる。
【００３３】
本発明の形成方法において、塗布型の内周面に形成された膜が指触乾燥の度合いとなったときに、上記中子型を塗布型に載置することにより、膜表面が、変形可能で流動性の少ない乾燥レベルで均されるため、指触乾燥前の液状レベルで均す場合より、著しい効果が得られる。
【図面の簡単な説明】
【図１】本実施例の無端状ベルト形成装置の全体構成を示す断面図である。
【図２】均し部材として成形用コロを備えた中子型の一端部を拡大して示しており、（ａ）は断面図で、（ｂ）は軸方向からみた側面図である。
【図３】本実施例に備える中子型の回転体軸受部を示す拡大図である
【図４】均し部材として成形用ブレード４″を備えた中子型の一端部を拡大して示しており、（ａ）は断面図で、（ｂ）軸方向からみた側面図である。
【符号の説明】
１塗布型
２中子型
３回転体
４，４′，４″ 均し部材
４′ 成形用コロ
４″ 成形用ブレード
５軸部材（鉄の棒）
６ころがり軸受（ボールベアリング）
７内周面上の膜
ｈ′，ｈ″ 均一な距離[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an endless belt forming apparatus and method for forming a film by a centrifugal molding method in which a film precursor solution is applied to the inner peripheral surface of a cylindrical mold and then formed into a film by centrifugal force at high speed. More particularly, the present invention relates to a process for forming an intermediate transfer belt used in an electrostatic copying process such as a copying machine.
[0002]
[Prior art]
In an image forming apparatus such as a copying machine, a printer, and a facsimile, component units corresponding to each process of charging, developing, transferring, and fixing are arranged around a photosensitive member. Many of these component units basically use rotating belts or rotating rollers because the electrostatic copying process needs to be repeated continuously.
[0003]
The rotating roller is cylindrical or cylindrical, and its manufacture is relatively simple. On the other hand, for the production of the rotating belt, for example, a method of sticking both ends of the sheet into a cylindrical shape is easy, and this is also cheaper. However, in this case, since the seam is formed in the belt, it is necessary to drive the belt at a timing to avoid the seam during the process operation. Therefore, an endless belt (also called a seamless belt or an endless belt) has been required as a rotating belt used in the electrostatic copying process.
[0004]
Examples of practical use of the endless belt image forming apparatus include a surf fixing belt for reducing heat capacity and reducing power consumption, an intermediate transfer belt aiming at high image quality of color, and transporting paper to a fixing unit. For this reason, it is often used as a conveyor belt for this purpose. Recently, the charging portion and the developing portion have been studied from the viewpoint of the degree of freedom of layout.
[0005]
Conventionally, in manufacturing the endless belt, since the part shape is cylindrical, a cylindrical mold capable of forming an endless shape is used. In this case, however, the efficiency of the material used is advantageous. For this reason, the belt precursor solution (hereinafter referred to as “coating liquid”) is poured from the nozzle into the inner peripheral surface of a rotating mold (hereinafter referred to as “coating mold”) as a rotating cylindrical workpiece. After applying by spraying, a method called a centrifugal molding method is used in which it is cast and spread on the inner peripheral surface with a centrifugal force due to high-speed rotation of the coating mold, smoothed into a substantially uniform film, and then heated and dried and cured. .
[0006]
This centrifugal molding method is characterized in that the coating liquid is cast on the inner peripheral surface of the coating mold. For example, when manufacturing belts having different diameters, a coating mold having a diameter corresponding to the belt must be prepared. I must. For this reason, the position of the nozzle that discharges the coating liquid must be readjusted each time, and there is a problem such as troublesome setup. Therefore, in view of such problems, the present applicant is able to smooth the film only by inserting the core mold as the second mold inside the cylindrical mold, and the core molding method that saves the labor of the adjustment and the like Devised.
[0007]
[Problems to be solved by the invention]
Incidentally, in general, an intermediate transfer belt used as a toner carrier of an electrostatic copying process such as a copying machine or a printer is configured to be rotatably driven by a driving roller and a driven roller. If the film thickness varies, for example, the belt may move toward one side of the roller during driving, or it may eventually be broken. In addition, since the electrical resistance is partially different due to the different film thickness, the gradation of the image cannot be reproduced, and the image quality is deteriorated such that the toner is not mounted, so-called white spots are generated. .
[0008]
The reason for the variation in the film thickness is that the inner peripheral surface of the coating mold is not a perfect circle, but is deformed or shaken. The film thickness can be controlled by such fluctuations and uneven distribution during drying and heating. It is generally difficult. In the above centrifugal molding method, since the film thickness changes due to the shake of the inner peripheral surface of the coating mold, it is important to control the shake. However, there is a mechanical limit in terms of accuracy in the control of the mold run. Even if high accuracy is pursued, a considerable cost is required.
[0009]
Accordingly, an object of the present invention is to provide an endless belt forming apparatus and a forming method capable of minimizing film thickness variations by simple means in the centrifugal molding method using the core mold. Yes.
[0010]
[Means for Solving the Problems]
The endless belt forming apparatus of the present invention that achieves the above object includes a cylindrical coating mold that forms a coating solution applied to an inner peripheral surface by centrifugal force, and a shaft that is rotatable in parallel with the interior of the coating mold. And an endless belt forming apparatus having a core mold for uniforming the film thickness on the inner peripheral surface of the coating mold, the core mold being driven by the coating mold A rotating member is provided at both ends and a leveling member is supported coaxially between the rotating members. When the core mold is provided in the coating mold and rotated, It is characterized in that the circumferential surface and the outer surface of the leveling member maintain a uniform distance.
[0011]
The core mold may be placed on the lower part of the inner peripheral surface of the coating mold, and may be driven and rotated by the coating mold by its own weight so that the film surface can be loaded by the leveling member. It is good to set it as the structure currently supported so that a shin member may not be driven by the rotary body of the said both ends.
[0012]
The leveling member may be a cylindrical or cylindrical molding roller having a smaller diameter than the rotating bodies at both ends, and the leveling member is between the rotating bodies provided at the both ends. It is also possible to adopt a configuration in which the forming blade can be loaded onto the film surface at the tip portion by maintaining the vertical direction by its own weight. In this case, it is also possible to have a configuration in which the rotating members at both ends have shaft members that are rotatably supported by rolling bearings, and the molding blade is a flat plate fixed to the shaft member. Further, it is desirable that the leveling member is made of a releasable material, or at least a part to be weighted to the film surface is coated with a releasable material against the solvent of the coating solution.
[0013]
The endless belt forming method of the present invention that achieves the above object is a method in which a coating solution applied to the inner peripheral surface of a cylindrical coating mold is formed into a film by centrifugal force and then rotated inside the coating mold. A method for forming an endless belt in which a core mold is placed parallel to the axis and the coating mold is rotated, and the film on the inner peripheral surface of the coating mold is smoothed by the core mold, A rotating body that follows the coating mold is provided at both ends, and a leveling member is rotatably supported between the rotating bodies. When the core mold is placed inside the coating mold and rotated, the leveling is performed. A uniform distance is maintained between the outer surface of the member and the inner peripheral surface of the coating mold. Further, in this method, it is desirable that the core mold is placed on the coating mold when the film formed on the inner peripheral surface of the coating mold reaches a dry degree of touch.
[0014]
[Action]
First, the coating solution is applied inside while slowly rotating the coating mold to obtain a predetermined liquid film thickness. After this application, a substantially uniform film is formed on the inner peripheral surface by centrifugal force at high speed. In this state, heat dry, stop the rotation after the degree of dryness to the touch that does not peel or spill, insert the core mold that can be driven by the coating mold into the coating mold parallel to the axis, and place it again. Rotate. This core mold has releasability that can maintain a uniform distance (nip) from the inner peripheral surface of the coating mold by being coaxially supported between two rotating bodies that are driven to rotate by the coating mold. A leveling member is provided. Through this leveling member, the thick film portion receives a core-type weight and moves (flow deformation) to the thin film portion that is not subjected to the weight. For this reason, the thickness of the film is surely made uniform irrespective of mold runout or the like.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional view showing the overall configuration of an endless belt forming apparatus of this embodiment. FIG. 2 is an enlarged view showing one end of the core mold 2 of FIG. (A) of the same figure is sectional drawing, (b) is the side view seen from the axial direction.
[0016]
The coating mold 1 as a cylindrical mold is a mold having an inner diameter of 180 mm and a width of 700 mm, and is supported by a support portion (not shown) so as to be able to rotate at high speed. The core mold 2 is placed in parallel to the bottom of the inner peripheral surface of the coating mold 1 and includes two rotating bodies 3 having a diameter of 20 mm driven by the inner surface of the coating mold 1 at the left and right ends. In addition, the leveling member 4 is supported between the left and right rotating bodies 3 so as not to be driven by the rotating body 3. In the present embodiment, a molding roller or a molding blade described later is used as the leveling member 4.
[0017]
FIG. 2 shows the configuration of one end of an apparatus provided with a forming roller 4 ′ as the leveling member 4, where (a) is a cross-sectional view and (b) is a side view from the axial direction. . FIG. 3 is an enlarged view showing a bearing portion of the rotating body 3. The forming roller 4 ′ has a long cylindrical shape, and the surface of the forming roller 4 ′ is a releasable member with respect to the film 7 whose surface is dry to the touch (not touching even when touched by a finger), or a release roller. By covering the mold-like smooth surface, it becomes insoluble in the solvent of the coating solution. The molding roller 4 ′ is fixed on the same core of a steel bar 5 (diameter 10 mm) that is a releasable shaft member coated with chrome plating and resin, and is supported between the rotating bodies 3. Also, as shown in FIG. 3, the iron rod 5 to be supported is supported at its both ends rotatably with respect to the left and right rotating bodies 3 by ball bearings 6 as rolling bearings. The molding roller 4 ′ fixed to 5 is not rotated by the rotating body 3 that is rotated by being driven by the coating die 1, and is supported on the same axis as the rotating body 3. The difference between the outer diameter of the body 3 and the outer diameter of the molding roller 4 'always keeps the nip as a uniform distance h'.
[0018]
4A and 4B show the configuration of the main part of an apparatus provided with a molding blade 4 ″ as the leveling member 4, where FIG. 4A is a sectional view and FIG. 4B is a side view. Is suspended from an iron rod 5 as a shaft member so as to maintain a distance h ″ of 5.9 mm between its tip and the inner peripheral surface of the coating die 1. For the molding blade 4 ″, a material made of PTFE such as purple fluoroethylene as a releasable member that is insoluble in the solvent of the coating solution is used. In this case, an incision is formed in the axial direction of the iron rod 5, and a PTEF blade 4 ″ is sandwiched between the incisions. The iron rod 5 is supported by the rotating body 3 freely, Even when the rotating body 3 is rotated, the forming blade 4 ″ fixed to the iron rod 5 can keep the distance h ″ constant by always facing the vertical direction by its own weight.
[0019]
With the above configuration, the distance h ′ formed by the forming roller 4 ′ and the distance h ″ formed by the forming blade 4 ″ become spaces (nips) as film thickness control widths. There is no need to provide a separate spacer such as attaching a tape to the inner peripheral surface of the first member.
[0020]
In addition, since the leveling member 4 is not driven by the coating mold 1 and can maintain a constant posture, the film 7 is leveled by the entire circumferential surface using a simple cylindrical core type (for example, a simple metal rod). Compared with the case of the case, for example, the metal rod is less susceptible to the effects of abnormal irregularities on the outer surface of the metal rod, the deviation of the film thickness, etc., and is further excellent in smoothing the surface.
[0021]
In the case where heat curing is performed with the core mold 2 mounted after smoothing in the forming process described later, not only the coating mold 1 but also the material of the leveling member 4 and the like up to about 300 ° C. The temperature is required to be heat resistant. In this case, the core mold 2 may also be made of, for example, an inorganic and elastic material, generally a metal plated with chromium plating, tin treatment, or Au, or other metal coated with a fluororesin.
[0022]
Next, a method for forming an endless belt according to this embodiment will be described. While slowly rotating the coating mold 1, a coating solution in which a polyimide precursor and a conductive agent are dispersed in DMAC (N, N′dimethylacetamide) and diluted to 30% is injected into the coating mold 1. To form a liquid film having a predetermined thickness.
[0023]
Thereafter, the coating die 1 is rotated at a high speed of 1000 rpm, and the coating liquid is cast and spread on the inner peripheral surface to form a substantially uniform film 7. In this state, after the solvent is dried and solidified to a degree of dryness that does not stick even if touched with a finger, the rotation is stopped and the core mold 2 provided with the leveling member 4 is inserted into the coating mold 1. Then, it is placed at a predetermined position and rotated again at a high speed.
[0024]
The film 7 that is dry to the touch is still soft, and the film thickness is made uniform by the weighting of the leveling member 4 during high-speed rotation again. Thereafter, the temperature is raised, the film 7 is cured by heating and drying at 300 ° C. for 30 minutes, and the rotation is stopped after cooling. After removing the core mold 2 from the coating mold 1, the coating 7 is peeled off to obtain an endless belt. Here, the film thickness and surface roughness of the film 7 were measured, and the performance was evaluated by an actual copying machine.
[0025]
A case where the core mold 2 provided with the leveling member 4 is used as Example 1, and a conventional centrifugal molding method without using the core mold 2 by using the same diluted dispersion as in Example 1. Is a comparative example 1 and, further, a case where a simple rod-shaped core mold 2 is used under the same conditions as in the comparative example 1 is used as a comparative example 2, and the obtained endless belts Variation, surface roughness, etc. were measured. The measurement results are shown in Table 1.
[0026]
[Table 1]

[0027]
As shown in Table 1, Comparative Example 1 that does not use a core has a large difference between the maximum film thickness and the minimum film thickness, as compared with Example 1 or Comparative Example 2. The roughness Rz was also a considerably large value. On the other hand, in Example 1, good results were obtained for each measured value, and in particular, the surface roughness Rz was better than Comparative Example 2.
[0028]
When evaluating the belt, cut the sample of each example to the length of the unit dimension, attach the offset tape, and attach it to the transfer belt unit of the applicant's full-color copier (trade name Pretail). While doing this, belt durability and the like were evaluated.
[0029]
As a result of this evaluation, white spots occurred when the endless belt of Comparative Example 1 was used. However, in the belts of Example 1 and Comparative Example 2 manufactured using the core mold 2, the deviation is also gradation. A good image was obtained without causing problems such as white spots. In addition, the belt of Example 1 had better gradation and better image contrast than Comparative Example 2.
[0030]
【The invention's effect】
As described above, the endless belt forming apparatus of the present invention has a cylindrical coating mold that forms a coating solution applied to the inner peripheral surface with a centrifugal force, and rotates in parallel with the inside of the coating mold. An endless belt forming apparatus that is freely provided and has a core mold for uniformizing the film thickness on the inner peripheral surface of the coating mold, wherein the core mold is driven by the coating mold. A rotating member that has a rotating member at both ends, and a leveling member that is coaxially supported between the rotating members. When the core mold is provided in the coating mold and rotated, the coating mold Since the inner peripheral surface and the outer surface of the leveling member are kept at a uniform distance, the core mold is driven to rotate in response to the deflection of the coating mold, and the leveling member is always in contact with the inner surface of the coating mold. A certain distance can be maintained, and the film thickness can be made uniform regardless of mold deflection.
[0031]
According to the configuration in which the leveling member is rotatably supported so as not to be driven by the rotating bodies at both ends, the leveling member maintains a constant posture without being restricted by the rotation of the rotating bodies at both ends. In addition, a constant distance can always be maintained from the inner surface of the coating mold.
[0032]
According to the configuration in which the leveling member is made of a releasable material, or at least a part that is weighted to the film surface is coated with a releasable material with respect to the solvent of the coating solution, the leveling member is It is possible to prevent the film from becoming uniform due to the absorption of the solvent from the coating solution and the dissolution in the solvent, and the deterioration of the film quality due to the dissolution of different components into the film. Moreover, if it is mold release property, it can prevent that a film thickness varies by sliding resistance between films.
[0033]
In the forming method of the present invention, when the film formed on the inner peripheral surface of the coating mold is dry to the touch, the film surface can be deformed by placing the core mold on the coating mold. Therefore, a significant effect can be obtained as compared with the case of leveling at a liquid level before drying by touching.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing the overall configuration of an endless belt forming apparatus of the present embodiment.
FIGS. 2A and 2B are enlarged views of one end portion of a core mold provided with a forming roller as a leveling member, wherein FIG. 2A is a cross-sectional view and FIG. 2B is a side view as viewed from the axial direction.
FIG. 3 is an enlarged view showing a core-type rotor bearing portion provided for the present embodiment. FIG. 4 is an enlarged view of one end portion of the core type provided with a molding blade 4 ″ as a leveling member. (A) is sectional drawing, (b) It is the side view seen from the axial direction.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Coating type 2 Core type | mold 3

Rotating body

4,4 ', 4 "Leveling member 4' Forming roller 4" Forming blade 5 Shaft member (iron bar)
6 Rolling bearing (ball bearing)
7 Film h ′, h ″ on the inner peripheral surface Uniform distance

Claims

A cylindrical coating mold that forms a coating solution applied to the inner peripheral surface by centrifugal force, and an axially parallel rotatable inside the coating mold, and the film thickness on the inner peripheral surface of the coating mold is An endless belt forming device having a core shape for homogenization,
The core mold has rotating bodies driven by the coating mold at both ends, and a leveling member is supported on the same axis between the rotating bodies. An endless belt forming apparatus, wherein the inner peripheral surface of the coating mold and the outer surface of the leveling member are kept at a uniform distance when rotated in preparation.

2. The core mold according to claim 1, wherein the core mold is mounted on a lower portion of the inner peripheral surface of the coating mold, is driven to rotate by the coating weight by its own weight, and can be applied to the film surface by the leveling member. The endless belt forming apparatus as described.

3. The endless belt forming apparatus according to claim 1, wherein the leveling member is rotatably supported so as not to be driven by the rotating bodies at both ends.

The endless belt forming apparatus according to any one of claims 1 to 3, wherein the leveling member is a cylindrical or cylindrical molding roller having a smaller diameter than the rotating bodies at both ends.

The leveling member is a molding blade suspended between the rotating bodies provided at both ends, and the molding blade keeps the vertical direction by its own weight, thereby loading the membrane surface at the tip. 4. The endless belt forming apparatus according to claim 1, wherein the endless belt forming apparatus is possible.

6. A shaft member rotatably supported by rolling bearings on the rotating bodies at both ends, and the molding blade is a flat plate fixed to the shaft member. Endless belt forming device.

The leveling member is made of a releasable material, or is formed by coating a releasable material against a solvent of a coating solution on at least a portion to be loaded on the film surface. The endless belt forming apparatus according to any one of 1 to 6.

After the coating solution applied to the inner peripheral surface of the cylindrical coating mold is formed into a film by centrifugal force, a rotatable core mold is placed inside the coating mold in parallel with the axis, and the coating mold is rotated. A method of forming an endless belt that levels the film on the inner peripheral surface of the coating mold by the core mold,
The core mold is provided with a rotating body that follows the coating mold at both ends, a leveling member is rotatably supported between the rotating bodies, and the core mold is placed inside the coating mold and rotated. And forming an endless belt, wherein a uniform distance is maintained between the outer surface of the leveling member and the inner peripheral surface of the coating mold.

9. The formation of an endless belt according to claim 8, wherein the core mold is placed on the coating mold when the film formed on the inner peripheral surface of the coating mold reaches a dry degree of touch. Method.