JP4240800B2 - Non-fixing image receiving sheet - Google Patents

Description

【００３７】
後記の表２は、上記表１に示した各種体積抵抗率ρ1，ρ2を適用した受像シート（サンプルシート）ＳＰの転写性、保持性及びクリーニング性を表したものである。
【００３８】
転写性の評価については、転写前の感光体上の付着量に対して、受像シート上に転写された付着量を測定し，受像シートに転写された比率が８０％以上を良好（○）、それ以下を不可（×）としている。
【００３９】
保持性の評価については、画像形成された受像シートを重ね合わせ、シートの裏汚れを目視で評価し、裏汚れのないものを良好（○）、それ以外を不可（×）としている。
【００４０】
クリーニング性の評価については、画像形成されたシートを図３のクリーニング装置２０を通過させて転写部直前の受像シートの残像を目視で評価した。残像のないものを良好（○）、それ以外を（×）としている。
【００４１】
【表２】

【００４２】
上記表２より、転写性、保持性及びクリーニング性について、次のようなことが判明している。
【００４３】
［転写性］
シート表層２及びシート芯層３ともに体積抵抗率ρ1，ρ2が高すぎると、受像シートの厚み方向の抵抗が大きくなり、転写領域の電界が十分に確保されず、トナーの移動が十分に行われない。すなわち、表２のサンプルシートＳＰ５，６のように転写性はあまり向上しない。
【００４４】
また、シート芯層３の体積抵抗率ρ2が低すぎると、転写バイアスがシート芯層３を介して対向ローラ（シートクリーニング装置、または凸条部クリーニング装置）にリークし、転写電界が十分に印加されない場合が発生する。すなわち、表２のサンプルシートＳＰ１のように転写性はあまり期待できない。
【００４５】
［保持性］
シート表層２及びシート芯層３とも体積抵抗率ρ1，ρ2が高いと、シート芯層裏面側にトナーの帯電極性と逆極性の電荷が蓄積され、受像シートを重ねたときに、下側の受像シート凹部のトナー粒子との間に静電力を形成し、上側受像シート裏面に吸着される現象が発生する。すなわち、表２のサンプルシートＳＰ５，６のように保持性はあまり向上しない。
【００４６】
また、シート表層２の体積抵抗率ρ1が低過ぎると、トナー粒子とシート表層の静電的吸着力が小さくなり、画像が乱れる現象が発生する。すなわち、表２のサンプルシートＳＰ８，９，１０のように保持性はあまり向上しない。
【００４７】
［クリーニング性］
シート表層２、シート芯層３とも体積抵抗率ρ1,ρ2が高すぎると、受像シートの厚み方向抵抗が大きくなり、トナー粒子を剥離時に除電が十分に行われずに、受像シート表面に電荷が蓄積され、次の画像形成時に影響がでる。すなわち、表２のサンプルシートＳＰ５，６のようにクリーニング性はあまり向上しない。
【００４８】
転写性、保持性及びクリーニング性の３つの特性をすべて良好に向上させるためには、表１及び表２のサンプルシートＳＰ２〜ＳＰ４及びＳＰ７に示されているように、シート表層２の体積抵抗率ρ1は高く、シート芯層３の体積抵抗率ρ2を低くすることがポイントであり、具体的にはシート表層２の体積抵抗率ρ1が１０¹²Ω・cm以上で、シート芯層３の体積抵抗率が１０⁴Ω・cm以上１０¹⁰Ω・cm以下の割合（サンプルＳＰ２〜ＳＰ４に相当）が良好であった。
【００４９】
【本願発明の別の実施の形態】
（１）図１の非定着式受像シートはニ層構造であるが、三層構造以上とすることも可能である。
【００５０】
（２）図３に示す乾式のシートクリーニング装置（画像除去装置）２０の代わりに、図７に示すように、受像シートに液体を付与することで、受像シートの凹部のトナーを除去し、該シートを再使用可能な状態に再生する画像除去装置２１０を利用することも可能である。以下、図７の画像除去装置２１０を説明する。
【００５１】
▲１▼ 画像除去装置の概略構成
画像除去装置２１０は、概略、この装置２１０で再生する受像シートＳを収容し供給するシート供給部２１２と、シート供給部２１２から送り出された受像シートＳに液体を付与して該受像シートＳを濡らす浸漬部２１４と、液体の付与された受像シートＳからトナーを除去するトナー除去部２１６と、トナーが除去された受像シートＳに液体をスプレーして該受像シートＳ上に残留しているトナーなどの異物を除去するリンス部２１８と、トナーが除去された受像シートＳの表面に付着した液体を除去する液体除去部２２０と、液体を除去した受像シートＳを再利用可能な状態まで乾燥する乾燥部２２２と、乾燥した受像シートＳを排出し収容するシート排出部２２４とを有する。
【００５２】
▲２▼ シート供給部
シート供給部２１２は、受像シートＳを収容する供給トレイ２２６を有する。シート供給部２１２はまた、供給トレイ２２６に積層して収容されている複数の受像シートＳから最上シートのみを送り出すための捌き機構２２８と、捌き機構２２８によって下層のシートから分離された最上シートをシート搬送経路２３０に沿って送り出す送り出し機構２３２を有する。本実施形態では、捌き機構２２８として、最上シートに接触するピックアップローラと該ピックアップローラの外周面に接触する捌きパッドとを有する捌き装置を利用しているが、他の形態の捌き装置を利用してもよい。また、送り出し機構２３２としては、通常、駆動系に連結された第１の軸とこれに平行に配置された第２の軸とを有し、これらの軸に所定の間隔をあけて複数のローラ（例えば、ゴムローラ）を取り付け、一方の軸に取り付けたローラと他方の軸に取り付けたローラとでシートを挟持して搬送する、従来から複写機やプリンタの用紙搬送装置として利用されているローラ搬送装置が利用される。
【００５３】
▲３▼ 浸漬部
浸漬部２１４は、クリーニング液（液体）２３４を収容する容器２３６を有する。クリーニング液２３４としては、水が利用される。なお、受像シートＳに付着しているトナーを除去し易くするために、界面活性剤を約０．０１％（＝界面活性剤の重量／水の重量）添加してもよい。また、必要に応じて他の材料をクリーニング液２３４に添加してもよい。
【００５４】
容器２３６の内部空間は、越流壁２３８によって、受像シートＳを浸漬するための浸漬槽２４０と、この浸漬槽２４０から越流したクリーニング液２３４を収容する越流槽２４２とに分断されている。容器２３６にはまた、浸漬槽２４０から越流壁２３８を越流して越流槽２４２に流れ込んだクリーニング液２３４を再び浸漬槽２４０に送り込むとともに越流槽２４２から浸漬槽２４０にクリーニング液２３４を送る過程で該クリーニング液２３４に含まれる異物（例えば、トナー）を回収する液体循環部２４４が付設されている。
【００５５】
液体循環部２４４は液体循環路２４８を有する。液体循環路２４８は、一端が越流槽２４２に接続され、他端が浸漬槽２４０の上方に位置している。したがって、越流槽２４２に溜まったクリーニング液２３４は、浸漬槽２４０に液面上から補給される。また、液体循環路２４８は、この液体循環路２４８に沿ってクリーニング液２３４を強制循環するためのポンプ２５０と、クリーニング液２３４に含まれる異物を除去するフィルタ部２５２を有する。
【００５６】
越流槽２４２の液面高さを一定にするために、液面高さを計測し、越流槽２４２内の水位が所定以下になると図示しない予備タンクから浸漬槽２４０にクリーニング液２３４が補充されるようにしてもよい。
【００５７】
容器２３６の浸漬槽２４０には、シート搬送経路２３０に沿って、シート供給部２１２から送られてきた受像シートＳを浸漬槽２４０内のクリーニング液２３４中で搬送するために、複数の搬送機構２５６と、これら複数の搬送機構２５６の間で受像シートＳをガイドするガイド部材（図示せず）とを有する。搬送機構２５６は、上述したローラ搬送装置が用いられる。ガイド部材としては、シート搬送経路２３０を挟み、所定の間隔をあけて対向する一対のガイド板（クリーニング液２３４が出入りできる複数の開口部を有する板）又はガイドワイヤ（シート搬送方向に伸び且つシート搬送方向と直交する方向に所定の間隔をあけて配置された複数のワイヤ）が好適に利用できる。
【００５８】
▲４▼ トナー除去部
トナー除去部２１６は、シート搬送経路２３０を挟んで対向する一対のブラシローラ２５８を有する。これらブラシローラ２５８は、駆動系に連結された軸と、この軸の外周にナイロン繊維の植毛された基布を巻き付けたものが利用され、シート搬送経路２３０に沿って搬送される受像シートＳの表面と裏面にそれぞれのブラシローラ２５８の毛が接触するように配置されている。また、ブラシローラ２５８の間を通過する受像シートＳの表面又は裏面に付着しているトナーに接触して該受像シートＳからトナーを除去するために、それぞれ図示しないモータに駆動連結されている。
【００５９】
なお、ブラシローラ２５８の周速度は、受像シートＳの搬送速度の数倍から数十倍に設定される。また、ブラシローラ２５８の回転方向について簡単に説明すると、受像シートＳの先端がブラシローラ２５８の対向部に進入するときブラシローラ２５８の毛先がシート搬送方向に移動し、受像シートＳの先端が対向部を通過した後は毛先がシート搬送方向と逆方向に移動するように、ブラシローラ２５８の駆動モータを制御することが好ましい。
【００６０】
なお、図７では、受像シートＳに接触して該受像シートＳからトナーを除去する部材としてブラシローラ２５８を用いているが、回転軸の周囲にスポンジ又は布等の柔らかい部材を取り付けたローラを利用することもできる。
【００６１】
▲５▼ リンス部
リンス部２１８は、一対のブラシローラ２５８の間を通過する又は通過した受像シートＳの表面と裏面にクリーニング液２３４を供給するために、シート搬送経路２３０を挟み且つブラシローラ２５８の上方に配置されたスプレーノズル２６０を有する。このスプレーノズル２６０は、上述した液体循環路２４８の他端に接続されており、この液体循環路２４８で浄化されたクリーニング液２３４が供給されるようにしてある。なお、本実施形態において、スプレーノズル２６０は、所定の間隔をあけて液体噴射孔を形成した管をその途中で１８０°折り返して形成されている。
【００６２】
なお、図に示すように、シート搬送経路の両側にブラシローラ２５８及びスプレーノズル２６０を設けてあるのは、供給トレイ２２６上に受像シートの凹凸面を下側又は上側にして配置しても画像除去が行われるようにするためである。
【００６３】
▲６▼ 液体除去部
液体除去部２２０は、シート搬送経路２３０を挟んで対向するとともに、このシート搬送経路２３０上で互いに接触する２つのローラからなる絞りローラ対２６２を有する。これら絞りローラ対２６２を構成する２つのローラの一方は図示しないモータに駆動連結されている。
【００６４】
▲７▼ 乾燥部
乾燥部２２２は、クリーニング液２３４が除去された受像シートＳを、画像形成装置で再利用できる状態まで乾燥するために、液体除去部２２０の下流側に配置される。乾燥部２２２として、本実施形態では、シート搬送経路２３０を挟んで対向するとともに、このシート搬送経路２３０上で互いに接触する２つのローラ２６４、２６６からなる。これらローラ２６４、２６６のうち、少なくとも一方のローラ２６６は内部に加熱源であるヒータ２６８を備えている。
【００６５】
なお、乾燥部２２２の乾燥手段として、上述したローラ型加熱器の代わりに、例えば、シートに対して常温の空気を吹付けるだけの送風機や、温風を吹出すことのできるヒータ内蔵型送風機を用いてもよい。さらに除湿機によって乾燥させた空気を吹付ける形態のものであってもよい。
【００６６】
▲８▼ シート排出部
シート排出部２２４は、乾燥部２２２で乾燥された受像シートＳを積層して収容する排出トレイ２７０を有する。
【００６７】
▲９▼ シート再生処理
以上の構成を有する画像除去装置２１０の動作を説明する。具体的に、再生すべき受像シートＳは供給トレイ２２６に積層して収容される。この状態で装置２１０が起動すると、供給トレイ２２６に収容された複数の受像シートＳは、捌き機構２２８によって最上シートから順次送り出され、送り出し機構２３２によって浸漬部２１４に供給される。
【００６８】
浸漬部２１４に供給された受像シートＳは、ガイド部材にガイドされながら搬送機構２５６によって搬送され、浸漬槽２４０内のクリーニング液２３４に所定時間浸漬され、受像シートＳのシート表層の凹部にクリーニング液２３４が浸透する。これにより、受像シートＳの表面の凹部の中に付着しているトナーと表面との接着力が失われ、トナーは機械的な力を与えるだけで分離可能な状態になる。浸漬槽２４０のクリーニング液２３４から排出された受像シートＳは、その表面と裏面が一対のブラシローラ２５８の摺擦力を受け、これら表面又は裏面に付着しているトナーが除去される。このとき、受像シートＳの表面と裏面にはそれぞれスプレーノズル２６０からクリーニング液２３４が噴射され、ブラシローラ２５８の対向部を通過したシート部分に付着しているトナーが洗い流される。また、ブラシローラ２５８に付着したトナーが浸漬槽２４０に洗い落とされる。
【００６９】
浸漬槽２４０に落下したトナー、また浸漬槽２４０の中を受像シートＳが搬送される過程で該受像シートＳから分離したトナーは、越流壁２３８を越えて浸漬槽２４０から越流槽２４２に流れるクリーニング液２３４と共に越流槽２４２に流れ込む。越流槽２４２のクリーニング液２３４に含まれるトナーは、液体循環路２４８内をポンプ２５０によって送られ、フィルタ部２５２によって除去される。トナーが除去されたクリーニング２３４は、スプレーノズル２６０から受像シートＳの表面と裏面、及びブラシローラ２５８に噴射される。
【００７０】
トナーが除去された受像シートＳは、液体除去部２２０の絞りローラ対２６２によって挟圧され、表面上のクリーニング液２３４が除去される。続いて、受像シートＳは乾燥部２２２に送られて乾燥された後、シート排出部２２４の排出トレイ２７０上に排出される。
【００７１】
【発明の効果】
以上説明したように本願発明は、
（１）トナー粒子が除去可能に付着される非定着式受像シートを採用しているので、受像シートの再利用ができ、紙消費量を削減できると共に、定着式のようなエネルギー及び消耗品が不要になり、また、受像シートから回収したトナーを再利用でき、ランニングコストの低減が可能になる。
【００７２】
（２）受像シートＳの表面に、トナー粒子を受容する多数の凹部とトナー粒子を保護する多数の凸部が形成されているので、凹部内にトナー粒子を機械的に確実に保持し、かつ、多数の凸部により上記機械的な保持を強固にすると共に、凸部がスペーサとしての役目を果たすことにより、上方からの異物（指あるいは他のシート裏面）の接触を確実に防ぎ、機械的な保持性を向上させることができる。
【００７３】
（３）表面に多数の凹部と凸部が形成されると共に、受像シートの断面構造を、少なくとも、凹凸表面を有するシート表層と、シート芯層とを含む積層構造としていると、転写性、保持性及びクリーニング性等各種特性について、簡単に各層の体積抵抗率を異ならせることができ、それにより需要者の希望に応じた特性を向上させた受像シートを提供することができる。
【００７４】
（４）シート表層の体積抵抗率ρ1がシート芯層の体積抵効率Rρ2よりも大きくなるように構成すると、表２のサンプルシートＳＰ１〜ＳＰ８のようになり、良好な転写性、保持性及びクリーニング性を有する受像シートを作成できる可能性が高くなる。
【００７５】
（５）シート表層の体積抵抗率ρ1が１０¹²Ω・cm以上で、シート芯層の体積抵抗率ρ2が１０⁴Ω・cm以上１０¹⁰Ω・cm以下になるように設定すると、表２のサンプルＳＰ２〜ＳＰ４のように、すべての受像シートが良好な転写性、保持性及びクリーニング性を確実に発揮させるようにすることができる。
【００７６】
具体的には、転写領域においては、充分な転写電界を確保することができ、これにより、転写性を向上させることができる。クリーニング領域においては、トナー粒子脱離時の受像シートの除電効果が高まり、クリーニング性を高めることができると共に、安定した画像形成が可能となる。さらに、画像形成後の受像シートを重ねたときに、静電遮蔽効果が得られるとともに、シート表層に対するトナー粒子の吸着力も確保され、画像保持性も高くすることができる。
【００７７】
（６）凹凸状のシート表面を構成する凹部を溝状に形成し、凸部を溝状凹部に沿う尾根状（凸条）に形成すると、機械的な保持性が一層向上すると共に、高解像度で、かつ高コントラストな受像シートを実現することができる。
【図面の簡単な説明】
【図１】 本願発明を適用した非定着式受像シートの縦断面部分拡大斜視図である。
【図２】 体積抵抗率測定装置の配線図である。
【図３】 画像形成装置の簡略側面図である。
【図４】 画像形成装置の転写部の拡大縦断面図である。
【図５】 凸条部クリーニング装置の拡大縦断面図である。
【図６】 クリーニング装置（画像除去装置）の拡大縦断面図である。
【図７】 湿式のクリーニング装置（画像除去装置）の簡略側面図である。
【符号の説明】
２ シート表層
３ シート芯層
５ 溝状凹部
６ 凸部（凸条部）
１０ トナー粒子[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a non-fixing image-receiving sheet having a surface that is uneven and to which toner is removably attached.
[0002]
[Prior art]
[Fixed image receiving sheet]
Currently, printers used for output from a personal computer generally use an electrophotographic system in which toner particles are heated and fixed on an image receiving sheet made of paper, plastic, or the like, or ink receiving sheet. A typical example is an ink-jet system in which drying is fixed on the top.
[0003]
In each of the fixing methods described above, printing time is required, and consumables such as electricity bills and ink are required, which increases running costs. In addition, due to the recent trend toward reducing environmental impact, printer energy and paper consumption are required to be reduced.
[0004]
On the other hand, paper output by a printer or the like is temporarily necessary, but at present, the paper is no longer needed and is often discarded.
[0005]
[Non-fixing image receiving sheet]
In contrast to the above method, a method of reusing transfer paper is also known. For example, as a method for separating the toner from the transfer paper, a method of melting and peeling the solidified toner by passing the transfer paper between a pair of heat rollers, and a method of deinking using an aqueous solution such as a surfactant are known. It has been.
[0006]
However, a large amount of energy is required for heating and removing moisture that permeates, and the removed toner is melted and solidified and cannot be reused.
[0007]
Japanese Patent Laid-Open No. 6-43682 discloses a method for solving such a problem, in which minute protrusions are dispersedly formed on the surface of the image receiving sheet, and a toner image is transferred onto the surface of the image receiving sheet having a large number of minute protrusions. It is proposed that an image is formed by fixing with pressure, and then the toner is detached from the image receiving sheet by a mechanical method, and the image receiving sheet and the toner are reused.
[0008]
[Problems to be solved by the invention]
However, according to the image receiving sheet described in Japanese Patent Application Laid-Open No. 6-43682, the minute protrusions serve as a spacer above the sheet, so that the toner particles adhere to the back surface of the upper sheet superposed on the sheet surface. Although it is prevented, it hardly fulfills the function of mechanically and reliably holding the toner particles adhering to the sheet surface.
[0009]
Further, since the minute protrusions are simply formed in a dispersed manner, the image receiving sheet after image formation may be handled while the toner is attached to the minute protrusions of the image receiving sheet. Although it is fixed to the protrusions by pressure treatment, the toner is fixed to such an extent that it can be mechanically removed from the image-receiving sheet, and the fingers and the back of the sheet are soiled by touching or rubbing with fingers. Sometimes it ends up.
[0010]
In addition, since the minute protrusions formed on the image receiving sheet are formed in isolated dot shapes, they are easily bent or deformed when subjected to an external force, so that an object can easily enter between the protrusions and the image is disturbed. The toner image cannot be sufficiently protected.
[0011]
OBJECT OF THE INVENTION
An object of the present invention is to realize an image receiving sheet that can be used repeatedly, to improve the mechanical toner retaining property as compared with the image receiving sheet disclosed in JP-A-6-43682, and to retain the toner including electric factors. , the various properties such as the toner transferability and cleanability (toner removability), as well as to be able to improve the desired properties depending on the needs of consumers, electrical toner retention, the toner transferability and The object is to make it possible to improve the overall properties of the cleaning property (toner removal property).
[0012]
[Technical means for solving the problems]
In order to achieve the above object, according to the first aspect of the present invention, in the non-fixing type image receiving sheet to which the toner particles are removably attached, the surface of the image receiving sheet is provided with a plurality of recesses for receiving the toner particles and the toner particles. A plurality of convex portions to be protected are formed, and the cross-sectional structure of the image receiving sheet is a laminated structure including at least the sheet surface layer having the uneven portions and the sheet core layer, and the volume resistivity of the sheet surface layer is 10 ¹² Ω · above cm, it is characterized in that the volume resistivity of the sheet core layer is not more than 10 ⁴ Ω · cm or more ¹⁰ 10 Ω · cm.
[0013]
According to a third aspect of the present invention, in the non-fixing image-receiving sheet according to the first aspect, the concave portion constituting the concave-convex surface is formed in a groove shape, and the convex portion is formed as a ridge-shaped convex strip portion along the groove-shaped concave portion. Has been.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
[Structure of non-fixing image receiving sheet]
FIG. 1 is an enlarged partial perspective view of a longitudinal section of a non-fixing image-receiving sheet S to which the present invention is applied. The cross-sectional structure of the image-receiving sheet S is a laminated structure (two-layer structure) composed of a sheet surface layer 2 and a sheet core layer 3. It has become. The surface of the sheet surface layer 2 is an uneven surface in which a large number of concave portions 5 and convex portions 6 are formed, and the sheet surface layer 2 and the sheet core layer 3 have different volume resistivity ρ1, ρ2. In the embodiment, the volume resistivity ρ1 of the sheet surface layer 2 is larger than the volume resistivity ρ2 of the sheet core layer 3, the volume resistivity of the sheet surface layer 2 is 10 ¹² Ω · cm or more, The volume resistivity is 10 ⁴ Ω · cm or more and 10 ¹⁰ Ω · cm or less.
[0018]
The concave portion 5 is formed in a continuous groove shape, and the convex portion 6 is continuous in a ridge shape along the groove-shaped concave portion 5 and is formed as a so-called convex strip portion.
[0019]
The groove recess 5 is regularly provided in parallel with, for example, the same width W1 in order to receive the toner 10. It is desirable that the width W1 of each recess 5 has a width that is twice or more the average particle diameter of the toner 10. For example, it is preferable that the width W1 of each groove-like recess 5 is 20 μm to 500 μm with respect to the average particle diameter of 2 to 30 μm of the toner 10, and the depth D (projection height H) is 20 μm to 100 μm. Preferably there is. The width W <b> 2 of the convex portion 6 is preferably less than or equal to ½ or less than ½ of the width W <b> 1 of the groove-like recess 5.
[0020]
The material of the image receiving sheet S can be formed of various materials such as paper, synthetic resin (polyester, polyethylene terephthalate, polyolefin (polypropylene, polyethylene, etc.), polyimide, polyamide, etc.), or combinations thereof.
[0021]
As shown in FIG. 1, the concave portion 5 has a continuous groove shape, and the convex portion 6 has a ridge-shaped convex portion 6 along the continuous groove-shaped concave portion 5, so that the convex portion 6 has a width W 1 and an upper space of the concave portion 5. The toner attached to a predetermined position on the bottom surface of the groove recess 5 is mechanically stably held, and even if the image sheets on which the images have been formed are stacked, the back surface of the upper image sheet is the toner. In addition, even if the surface of the image sheet is touched with a hand, the convex stripe portion 6 protects the toner, so that the hand is not stained or the image receiving sheet surface is not stained.
[0022]
[Method for producing non-fixing image-receiving sheet]
As shown in FIG. 1, as a method for forming a sheet surface layer 2 having an uneven surface on a sheet core layer 3, a synthetic resin (for example, polyethylene, acrylic) is formed on the sheet core layer 3 made of paper or the like. A layer of a sheet surface layer material obtained by kneading a white pigment, an extender pigment, etc. with titanium oxide, zinc oxide, silica, alumina, clay, talc, etc. 5 can be formed by a forming die (for example, a master roller) in which a pattern capable of forming 5 is formed. It may be performed by casting a resin into a mold.
[0023]
Further, a method of forming a polymer film used as a so-called resist on the sheet core layer 3 and performing an exposure process through a light-shielding mask to remove a portion corresponding to the continuous groove-shaped recess 5, and a specific example will be given. An example is a method in which a film of a photopolymerizable polymer is formed on the sheet core layer 3 and exposed through a light-shielding mask, and then a portion corresponding to the continuous groove-shaped recess 5 is removed by washing or the like.
[0024]
[Image forming apparatus]
An image forming apparatus for forming an image on a non-fixing type image receiving sheet according to the present invention will be described.
[0025]
FIG. 3 shows an example of an image forming apparatus. A cleaning device (toner removing device) 20 is disposed on the conveyance start end side (left side in FIG. 3) of the image forming device 21, and a protrusion cleaning device (on the conveyance end side) A ridge toner removing device) 22 is disposed. The cleaning device 20 includes a collection conductive brush roller 25 and a counter roller 26. The image forming apparatus 21 includes a drum-shaped photosensitive member 27 and a transfer roller 28 facing the drum-shaped photosensitive member 27. Around the photosensitive member 27, a transfer unit 30 in contact with the transfer roller 28 is sequentially arranged in the drum rotation direction R side. A toner wiping portion (scraping portion) 31, an image charging portion 32, an exposure portion 33, and a developing portion 34 are arranged. A bias that attracts toner particles is applied to the transfer roller 28. The protrusion cleaning device 22 includes a charging roller 35 and a counter roller 36, and a toner wiping portion 37 is disposed on the charging roller 35.
[0026]
[Image forming method]
An image forming method using the image forming apparatus 21 of FIG. 3 will be described.
(1) The image forming apparatus 21 uniformly charges the surface of the photosensitive member 27 to about −900 V in the image charging unit 32, performs exposure according to the image data in the exposure unit 33, and electrostatically charges the surface of the photosensitive member 27. A latent image is formed. Of the surface of the photoreceptor 27, the exposed portion is attenuated to about -100V, and the unexposed portion is maintained at about -900V. Thereafter, toner particles (negative polarity) are attached to the photoreceptor 27 in accordance with the electrostatic latent image in the developing unit 34.
[0027]
(2) When the image receiving sheet S is reused, the toner particles in the groove recess 5 are once removed by the cleaning device 20, and even when it is not reused, the surface is cleaned as necessary to form an image. It is conveyed to the transfer unit 30 of the apparatus 21.
[0028]
(3) In the transfer unit 30 of the image forming apparatus 21, the toner particles of the electrostatic latent image attached to the photoreceptor 27 are transferred onto the uneven surface of the image receiving sheet S conveyed from the cleaning apparatus 20. At this time, as the bias applied to the transfer roller 28, for example, about +1 kV is applied.
[0029]
FIG. 4 is an enlarged view of the transfer portion 30, and most of the toner particles 10 adhering to the surface of the photoreceptor 27 adhere to the bottom surface of the groove recess portion 5, but a part of the toner particles 10 is also attached to the protrusion portion 6. Adhere to. At the time of transfer, the protrusion 6 serves as a spacer between the photoreceptor 27 and the bottom surface of the groove-shaped recess 5 to prevent the bottom surface of the groove recess 5 and the photoreceptor 27 from being too close, An appropriate electric field distance can be secured and good transferability can be exhibited.
[0030]
(4) The image receiving sheet S to which the toner image has been transferred is conveyed to the convex portion cleaning device 22 of FIG. 3 and is projected by the electrostatic force of the charging roller (positive charge) 35 as shown in FIG. The toner particles 10 attached to 6 are collected. At this time, a bias of about +300 V is applied to the charging roller 35, and the opposing roller 36 is grounded.
[0031]
(5) When the image-receiving sheet S on which an image has been formed is used again, the toner particles that are conveyed to the sheet cleaning device 20 in FIG. At this time, a bias of about +1 kV having a polarity opposite to the toner particle charging polarity is applied to the collected conductive brush roller 25. The opposing roller 26 is grounded.
[0032]
【Example】
Table 1 below shows the volume resistivity ρ1 of the sheet surface layer 2 and the volume resistivity ρ2 of the sheet core layer 3 in the laminated image-receiving sheet S having the sheet surface layer 2 and the sheet core layer 3 as shown in FIG. It is a table combined with various changes.
[0033]
As a specific example of forming the sheet surface layer 2 on the sheet core layer 3, a thermoplastic resin (high density polyethylene) whose volume resistivity is adjusted by changing the blending (dispersion) amount of the carbon particles is uniformly formed on the sheet core layer 3. Next, the shape forming mold was stacked and hot pressed (120 ° C., 30 minutes, 10 kg / cm ² ), then cooled and separated to transfer the surface shape. The concavo-convex shape at this time was a concave portion width W1 = 200 μm, a convex portion width W2 = 10 μm, and a height H = 50 μm in FIG. Further, the minimum thickness portion (thickness of the sheet surface layer at the bottom of the recess) T1 of the sheet surface layer 2 was about 20 μm.
[0034]
As the material for the sheet core layer 3, a material obtained by processing polyethylene terephthalate kneaded with carbon particles or the like into a sheet having a thickness of about 80 μm was used. The volume resistivity was adjusted by changing the blending and dispersion amount of the carbon particles.
[0035]
The volume resistivity ρ1, ρ2 of each of the layers 2 and 3 is measured using a volume resistivity measuring apparatus as shown in FIG. 2, and each sheet is used as a sample sheet SP1 to SP10 to form a smooth sheet (thickness of about 100 μm) and measured. In FIG. 2, the volume resistivity measuring apparatus includes a pair of disk-shaped electrodes 50 and 51 having the same area (φ30 mm), and one electrode 50 is connected to a constant voltage power source (500 v) 52 via an ammeter 51. The other disk-shaped electrode 51 is grounded, a sample sheet SPn having a predetermined thickness is sandwiched between both electrodes 50, voltage is applied, current is measured, and volume resistivity ρ is calculated. is there.
[0036]
In Table 1, the sample sheets SP1 to SP6 fix the volume resistivity of the sheet surface layer 2 to a high value of ρ1 of 5.4 × 10 ^13, and the volume resistivity ρ2 of the sheet core layer 3 of the sheet surface layer 2 Within a range smaller than the volume resistivity ρ1, the sample sheets SP1 to SP6 are sequentially increased. In the sample sheets SP7 and SP8, the volume resistivity ρ2 of the sheet core layer 3 is fixed to a medium height of 7.6 × 10 ⁷ , and the volume resistivity ρ1 of the sheet surface layer 2 is set to the volume of the sheet core layer 3. Within the range higher than the resistivity ρ2, the sample sheets SP7 to SP8 are sequentially decreased. In the sample sheets SP9 and SP10, the volume resistivity ρ2 of the sheet core layer 3 is made larger than the volume resistivity ρ1 of the sheet surface layer 2, contrary to the sample sheets SP1 to SP8.
[Table 1]

[0037]
Table 2 described later shows transferability, retention, and cleaning properties of the image receiving sheet (sample sheet) SP to which the various volume resistivity ρ1, ρ2 shown in Table 1 is applied.
[0038]
For the evaluation of transferability, the amount of adhesion transferred onto the image receiving sheet is measured with respect to the amount of adhesion on the photoreceptor before transfer, and the ratio transferred to the image receiving sheet is 80% or more. Anything below that is not possible (x).
[0039]
With respect to the evaluation of retentivity, image-formed image-receiving sheets are overlapped, and the backside stains of the sheets are visually evaluated, and those that do not have backside stains are good (◯), and others are not possible (×).
[0040]
Regarding the evaluation of the cleaning property, the image-formed sheet was passed through the cleaning device 20 in FIG. 3 and the afterimage of the image receiving sheet immediately before the transfer portion was visually evaluated. Good (◯) indicates no afterimage, and (x) indicates no.
[0041]
[Table 2]

[0042]
From Table 2 above, the following has been found regarding transferability, retention and cleaning properties.
[0043]
[Transferability]
If the volume resistivity ρ1, ρ2 of both the sheet surface layer 2 and the sheet core layer 3 is too high, the resistance in the thickness direction of the image receiving sheet increases, the electric field in the transfer region is not sufficiently secured, and the toner is sufficiently moved. Absent. That is, the transferability is not so improved like the sample sheets SP5 and SP6 in Table 2.
[0044]
If the volume resistivity ρ2 of the sheet core layer 3 is too low, the transfer bias leaks to the opposing roller (sheet cleaning device or ridge cleaning device) via the sheet core layer 3, and the transfer electric field is sufficiently applied. It may not happen. That is, transferability cannot be expected much like the sample sheet SP1 in Table 2.
[0045]
[Retention]
If both the sheet surface layer 2 and the sheet core layer 3 have a high volume resistivity ρ1, ρ2, a charge opposite in polarity to the charge polarity of the toner is accumulated on the back side of the sheet core layer. A phenomenon occurs in which an electrostatic force is formed between the toner particles in the concave portion of the sheet and is attracted to the back surface of the upper image receiving sheet. That is, the retainability is not improved so much like the sample sheets SP5 and 6 in Table 2.
[0046]
On the other hand, if the volume resistivity ρ1 of the sheet surface layer 2 is too low, the electrostatic adsorption force between the toner particles and the sheet surface layer becomes small, and a phenomenon that the image is disturbed occurs. That is, the retainability is not improved so much as the sample sheets SP8, 9, and 10 in Table 2.
[0047]
[Cleanability]
If the volume resistivity ρ1, ρ2 of both the sheet surface layer 2 and the sheet core layer 3 is too high, the resistance in the thickness direction of the image receiving sheet increases, and charge is accumulated on the surface of the image receiving sheet without sufficient charge removal when the toner particles are peeled off. This affects the next image formation. That is, like the sample sheets SP5 and SP6 in Table 2, the cleaning property is not improved so much.
[0048]
In order to satisfactorily improve all three characteristics of transferability, holding property and cleaning property, the volume resistivity of the sheet surface layer 2 as shown in the sample sheets SP2 to SP4 and SP7 in Tables 1 and 2 The point is that ρ1 is high and the volume resistivity ρ2 of the sheet core layer 3 is low. Specifically, the volume resistivity ρ1 of the sheet surface layer 2 is 10 ¹² Ω · cm or more. The rate was 10 ⁴ Ω · cm to 10 ¹⁰ Ω · cm (corresponding to samples SP2 to SP4).
[0049]
[Another embodiment of the present invention]
(1) The non-fixing image-receiving sheet in FIG. 1 has a two-layer structure, but it can also have a three-layer structure or more.
[0050]
(2) Instead of the dry sheet cleaning device (image removing device) 20 shown in FIG. 3, as shown in FIG. 7, by applying a liquid to the image receiving sheet, the toner in the recesses of the image receiving sheet is removed, It is also possible to use an image removal apparatus 210 that reproduces a sheet in a reusable state. Hereinafter, the image removing apparatus 210 of FIG. 7 will be described.
[0051]
(1) Schematic configuration of image removing apparatus The image removing apparatus 210 is roughly configured to store and supply an image receiving sheet S reproduced by the apparatus 210, and to supply liquid to the image receiving sheet S sent out from the sheet supplying section 212. The image receiving sheet S is soaked to wet the image receiving sheet S, the toner removing unit 216 removes the toner from the liquid image receiving sheet S, and the image receiving sheet S from which the toner has been removed is sprayed with liquid. A rinsing unit 218 for removing foreign matters such as toner remaining on the sheet S, a liquid removing unit 220 for removing liquid adhering to the surface of the image receiving sheet S from which the toner has been removed, and an image receiving sheet S from which liquid has been removed. Are dried to a reusable state, and a sheet discharge unit 224 that discharges and stores the dried image-receiving sheet S.
[0052]
(2) Sheet Supply Unit The sheet supply unit 212 includes a supply tray 226 for storing the image receiving sheet S. The sheet supply unit 212 also includes a separation mechanism 228 for sending out only the uppermost sheet from the plurality of image receiving sheets S accommodated in the supply tray 226, and the uppermost sheet separated from the lower layer sheet by the separation mechanism 228. A delivery mechanism 232 that delivers the sheet along the sheet conveyance path 230 is provided. In the present embodiment, a whirling device having a pick-up roller that contacts the uppermost sheet and a whirling pad that touches the outer peripheral surface of the pick-up roller is used as the whirling mechanism 228, but a whirling device of another form is used. May be. The feed mechanism 232 usually has a first shaft connected to the drive system and a second shaft arranged in parallel to the first shaft, and a plurality of rollers with a predetermined interval between these shafts. (For example, a rubber roller) is attached, and the sheet is nipped and conveyed by a roller attached to one shaft and a roller attached to the other shaft, and has been conventionally used as a paper conveyance device for copying machines and printers. A device is used.
[0053]
(3) Immersion part The immersion part 214 has a container 236 for storing a cleaning liquid (liquid) 234. Water is used as the cleaning liquid 234. In order to easily remove the toner adhering to the image receiving sheet S, a surfactant may be added in an amount of about 0.01% (= surfactant weight / water weight). Further, other materials may be added to the cleaning liquid 234 as necessary.
[0054]
The internal space of the container 236 is divided by the overflow wall 238 into an immersion tank 240 for immersing the image receiving sheet S and an overflow tank 242 for storing the cleaning liquid 234 that has overflowed from the immersion tank 240. . Further, the cleaning liquid 234 that has flowed from the immersion tank 240 to the overflow tank 242 through the overflow wall 238 is sent again to the immersion tank 240 and the cleaning liquid 234 is sent from the overflow tank 242 to the immersion tank 240. A liquid circulation unit 244 for collecting foreign substances (for example, toner) contained in the cleaning liquid 234 in the process is attached.
[0055]
The liquid circulation unit 244 has a liquid circulation path 248. The liquid circulation path 248 has one end connected to the overflow tank 242 and the other end positioned above the immersion tank 240. Therefore, the cleaning liquid 234 accumulated in the overflow tank 242 is replenished to the immersion tank 240 from above the liquid surface. Further, the liquid circulation path 248 includes a pump 250 for forcibly circulating the cleaning liquid 234 along the liquid circulation path 248 and a filter unit 252 for removing foreign substances contained in the cleaning liquid 234.
[0056]
In order to make the liquid level height of the overflow tank 242 constant, the liquid level height is measured, and when the water level in the overflow tank 242 falls below a predetermined level, the cleaning liquid 234 is replenished from the reserve tank (not shown) to the immersion tank 240. You may be made to do.
[0057]
In order to convey the image receiving sheet S sent from the sheet supply unit 212 in the cleaning liquid 234 in the immersion tank 240 along the sheet conveyance path 230, a plurality of conveyance mechanisms 256 are provided in the immersion tank 240 of the container 236. And a guide member (not shown) for guiding the image receiving sheet S between the plurality of transport mechanisms 256. As the transport mechanism 256, the above-described roller transport device is used. As the guide member, a pair of guide plates (plates having a plurality of openings through which the cleaning liquid 234 can enter and exit) or a guide wire (a sheet extending in the sheet conveyance direction and sandwiching the sheet conveyance path 230 with a predetermined interval therebetween) A plurality of wires arranged at predetermined intervals in a direction orthogonal to the transport direction can be suitably used.
[0058]
(4) Toner Removal Unit The toner removal unit 216 has a pair of brush rollers 258 facing each other with the sheet conveyance path 230 interposed therebetween. These brush rollers 258 use a shaft connected to a drive system and a base fabric in which nylon fibers are implanted around the shaft, and the image receiving sheet S conveyed along the sheet conveying path 230 is used. It arrange | positions so that the hair of each brush roller 258 may contact a surface and a back surface. In addition, in order to remove the toner from the image receiving sheet S in contact with the toner adhering to the front surface or the back surface of the image receiving sheet S passing between the brush rollers 258, each is connected to a motor (not shown).
[0059]
The peripheral speed of the brush roller 258 is set to several to several tens of times the conveying speed of the image receiving sheet S. The rotation direction of the brush roller 258 will be briefly described. When the leading edge of the image receiving sheet S enters the opposite portion of the brush roller 258, the hair tip of the brush roller 258 moves in the sheet conveying direction, and the leading edge of the image receiving sheet S is moved. It is preferable to control the drive motor of the brush roller 258 so that the hair ends move in the direction opposite to the sheet conveying direction after passing through the facing portion.
[0060]
In FIG. 7, the brush roller 258 is used as a member that contacts the image receiving sheet S and removes toner from the image receiving sheet S. However, a roller having a soft member such as sponge or cloth around the rotating shaft is used. It can also be used.
[0061]
(5) Rinsing section The rinsing section 218 sandwiches the sheet conveying path 230 and supplies the brush roller 258 so as to supply the cleaning liquid 234 to the front and back surfaces of the image receiving sheet S that has passed between or passed between the pair of brush rollers 258. Has a spray nozzle 260 disposed above. The spray nozzle 260 is connected to the other end of the liquid circulation path 248 described above, and the cleaning liquid 234 purified by the liquid circulation path 248 is supplied thereto. In the present embodiment, the spray nozzle 260 is formed by folding back a pipe formed with liquid ejection holes at a predetermined interval by 180 ° in the middle.
[0062]
As shown in the figure, the brush roller 258 and the spray nozzle 260 are provided on both sides of the sheet conveyance path because the image receiving sheet is arranged on the supply tray 226 with the uneven surface on the lower side or the upper side. This is because removal is performed.
[0063]
(6) Liquid Remover The liquid remover 220 has a squeezing roller pair 262 composed of two rollers that are opposed to each other with the sheet conveying path 230 in between and in contact with each other on the sheet conveying path 230. One of the two rollers constituting the diaphragm roller pair 262 is drivingly connected to a motor (not shown).
[0064]
(7) The drying unit drying unit 222 is disposed on the downstream side of the liquid removing unit 220 in order to dry the image receiving sheet S from which the cleaning liquid 234 has been removed to a state where it can be reused in the image forming apparatus. In the present embodiment, the drying unit 222 includes two rollers 264 and 266 that are opposed to each other with the sheet conveyance path 230 interposed therebetween and are in contact with each other on the sheet conveyance path 230. Among these rollers 264 and 266, at least one of the rollers 266 includes a heater 268 serving as a heating source.
[0065]
In addition, as a drying means of the drying unit 222, instead of the above-described roller-type heater, for example, a blower that just blows room temperature air to the sheet, or a heater built-in blower that can blow warm air It may be used. Furthermore, the thing of the form which sprays the air dried with the dehumidifier may be sufficient.
[0066]
(8) Sheet Discharge Unit The sheet discharge unit 224 includes a discharge tray 270 that stores the image receiving sheets S dried by the drying unit 222 in a stacked manner.
[0067]
(9) The operation of the image removing apparatus 210 having the above configuration of the sheet reproduction process will be described. Specifically, the image receiving sheet S to be reproduced is stacked and accommodated on the supply tray 226. When the apparatus 210 is activated in this state, the plurality of image receiving sheets S accommodated in the supply tray 226 are sequentially fed from the uppermost sheet by the rolling mechanism 228 and are supplied to the immersion unit 214 by the feeding mechanism 232.
[0068]
The image receiving sheet S supplied to the dipping unit 214 is conveyed by the conveying mechanism 256 while being guided by the guide member, dipped in the cleaning liquid 234 in the dipping tank 240 for a predetermined time, and is cleaned in the concave portion of the sheet surface layer of the image receiving sheet S. 234 penetrates. As a result, the adhesive force between the toner adhering in the concave portion on the surface of the image receiving sheet S and the surface is lost, and the toner can be separated only by applying a mechanical force. The image receiving sheet S discharged from the cleaning liquid 234 of the dipping tank 240 receives the rubbing force of the pair of brush rollers 258 on the front and back surfaces, and the toner adhering to the front and back surfaces is removed. At this time, the cleaning liquid 234 is sprayed from the spray nozzle 260 to the front surface and the back surface of the image receiving sheet S, respectively, and the toner adhering to the sheet portion that has passed through the facing portion of the brush roller 258 is washed away. Further, the toner adhering to the brush roller 258 is washed away in the immersion tank 240.
[0069]
The toner dropped into the immersion tank 240 and the toner separated from the image receiving sheet S in the process of transporting the image receiving sheet S through the immersion tank 240 crosses the overflow wall 238 and enters the overflow tank 242 from the immersion tank 240. It flows into the overflow tank 242 together with the flowing cleaning liquid 234. The toner contained in the cleaning liquid 234 in the overflow tank 242 is sent through the liquid circulation path 248 by the pump 250 and removed by the filter unit 252. The cleaning 234 from which the toner has been removed is sprayed from the spray nozzle 260 onto the front and back surfaces of the image receiving sheet S and the brush roller 258.
[0070]
The image receiving sheet S from which the toner has been removed is pinched by the pair of squeezing rollers 262 of the liquid removing unit 220, and the cleaning liquid 234 on the surface is removed. Subsequently, the image receiving sheet S is sent to the drying unit 222 and dried, and then discharged onto the discharge tray 270 of the sheet discharge unit 224.
[0071]
【The invention's effect】
As described above, the present invention
(1) Since a non-fixing type image receiving sheet to which toner particles are removably attached is adopted, the image receiving sheet can be reused, paper consumption can be reduced, and energy and consumables such as a fixing type In addition, the toner collected from the image receiving sheet can be reused, and the running cost can be reduced.
[0072]
(2) Since the surface of the image receiving sheet S has a large number of concave portions for receiving toner particles and a large number of convex portions for protecting the toner particles, the toner particles are mechanically reliably held in the concave portions, and In addition to strengthening the mechanical holding by a large number of convex portions, the convex portions serve as spacers, thereby reliably preventing contact of foreign matter (finger or other sheet back) from above, and mechanical Can be improved.
[0073]
(3) A large number of concave portions and convex portions are formed on the surface, and when the cross-sectional structure of the image receiving sheet is a laminated structure including at least a sheet surface layer having an uneven surface and a sheet core layer, transferability and retention With respect to various properties such as properties and cleaning properties, it is possible to easily vary the volume resistivity of each layer, thereby providing an image receiving sheet having improved properties according to the desires of consumers.
[0074]
(4) When the volume resistivity ρ1 of the sheet surface layer is larger than the volume resistivity Rρ2 of the sheet core layer, sample sheets SP1 to SP8 in Table 2 are obtained, and good transferability, retention and cleaning are achieved. There is a high possibility that an image-receiving sheet having a property can be created.
[0075]
(5) When the volume resistivity ρ1 of the sheet surface layer is 10 ¹² Ω · cm or more and the volume resistivity ρ2 of the sheet core layer is 10 ⁴ Ω · cm or more and 10 ¹⁰ Ω · cm or less, As in the samples SP2 to SP4, all the image receiving sheets can surely exhibit good transferability, retention and cleaning properties.
[0076]
Specifically, a sufficient transfer electric field can be secured in the transfer region, thereby improving transferability. In the cleaning area, the effect of neutralizing the image receiving sheet at the time of toner particle detachment is enhanced, the cleaning property can be improved, and stable image formation is possible. Further, when the image-receiving sheets after image formation are stacked, an electrostatic shielding effect is obtained, the toner particles adsorbing force to the sheet surface layer is ensured, and the image retention can be enhanced.
[0077]
(6) When the concave portion constituting the uneven sheet surface is formed in a groove shape and the convex portion is formed in a ridge shape (protruding line) along the groove-shaped concave portion, the mechanical retainability is further improved and high resolution is achieved. In addition, a high-contrast image receiving sheet can be realized.
[Brief description of the drawings]
FIG. 1 is a partially enlarged perspective view of a longitudinal section of a non-fixing image receiving sheet to which the present invention is applied.
FIG. 2 is a wiring diagram of a volume resistivity measuring device.
FIG. 3 is a simplified side view of the image forming apparatus.
FIG. 4 is an enlarged vertical sectional view of a transfer portion of the image forming apparatus.
FIG. 5 is an enlarged longitudinal sectional view of a ridge cleaning device.
FIG. 6 is an enlarged longitudinal sectional view of a cleaning device (image removing device).
FIG. 7 is a simplified side view of a wet cleaning device (image removal device).
[Explanation of symbols]
2 Sheet surface layer 3 Sheet core layer 5 Groove-shaped recess 6 Projection (projection strip)
10 Toner particles

Claims (2)

In a non-fixing image receiving sheet to which toner particles are removably attached,
On the surface of the image receiving sheet, a large number of concave portions that receive toner particles and a large number of convex portions that protect the toner particles are formed.
The cross-sectional structure of the image receiving sheet is a laminated structure including at least a sheet surface layer having the concavo-convex portion and a sheet core layer,
A volume resistivity of the sheet surface is 10 ¹² Ω · cm or more, the non-fixing type image receiving sheet, wherein the volume resistivity of the sheet core layer is not more than 10 ⁴ Ω · cm or more ¹⁰ 10 Ω · cm. 2. The non-fixing type image receiving sheet according to claim 1, wherein the concave portion constituting the concave and convex surface is formed in a groove shape, and the convex portion is formed as a ridge-shaped convex strip portion along the groove-shaped concave portion .

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