JP3944701B2 - Cleaning blade, cleaning device using the same, process cartridge, and image forming apparatus - Google Patents

Description

【００６２】
［クリーニング特性試験］
試験は、重合法によって作成された本明細書記載のトナーを用い、その形状係数は１３０から１３５、その平均粒径は６μｍである。このトナーを含む二成分現像剤を上記画像形成装置における現像装置に収容して使用し、その画像形成装置によるテストプリント（１色当たりの面積率５％の画像をランレングス５枚の繰り返しで５０，０００枚分（５０ｋｐｖ）プリント後の評価）を高温高湿（２８℃、８５％ＲＨ）、低温低湿（１０℃、１５％ＲＨ）、及び、中温中湿（２２℃、５５％ＲＨ）のそれぞれの環境で行ったときのクリーニング装置のクリーニング結果をプリント画像と感光体ドラムの観察をすることにより行った。同時に各速度での感光体ドラムとクリーニングブレードのこすれ時に発生する耳障り音発生の有無を確認した。
【００６３】
評価項目としては、クリーニング性能（クリーニング不良による筋状の画質欠陥：色筋の発生の有無）、ブレードダメージ（クリーニングブレードのエッジの欠け、ブレード自体のめくれ）、感光体ドラム回転時のブレード鳴きの有無、感光体ドラムの表面層の膜厚減少量(表面層の膜厚変化による画質変動を含む)について調べた。
その結果の良否は次の基準で評価した。この結果を図５及び図６に示した。
◎：５０ｋｐｖのテストプリント終了時点で評価対象の症状が発生せず、それ以降も良好な結果が得られると予測された場合。
○：５０ｋｐｖのテストプリント終了時点で評価対象の症状が発生しないが、その時点でほぼ寿命であると判断された場合。
×：テストプリント中に評価対象の症状が発生して５０ｋｐｖ分のテストプリントを完遂できなかった場合。
××：初期段階（１０ｋｐｖ以下のテストプリント段階）で評価項目の症状が発生した場合。
【００６４】
［ブレードへたり性能試験］
実施の形態１に示した感光体ユニット３０にクリーニングブレードを規定押しつけ力が得られる様に設定した後、感光体ドラムを取り付け、感光体ユニット３０を恒温恒湿槽の中に放置する。このときの温度、湿度、および放置時間の条件は、４５℃、９５％ＲＨ、７２時間とした。その後この感光体ユニット３０を画像形成装置に装填し、１ｋｐｖのショートランニングを行い、前記各プロセススピード、各環境下において評価を実施した。評価項目としては、前記クリーニング性能（クリーニング不良による筋状の画質欠陥：色筋の発生の有無）のみとした。
【００６５】
その結果の良否は次の基準で評価した。この結果を図５及び図６に示した。
◎：１ｋｐｖのテストプリント終了時点で評価対象の症状が発生せず、それ以降も良好な結果が得られると予測された場合。
○：１ｋｐｖのテストプリント終了時点で評価対象の症状が発生しないが、その時点でほぼ寿命であると判断された場合。
×：テストプリント中に評価対象の症状が発生して１ｋｐｖ分のテストプリントを完遂できなかった場合。
××：初期段階（１００ｐｖ以下のテストプリント段階）で評価項目の症状が発生した場合。
尚、比較例１と実施例１とでへたり量（クリーニングブレードの永久変形のことである。すなわち、感光体ドラムにある量変形させて押し付け力を発生させた状態で高温高湿条件下に長期間保持した後に、元に戻らなくなくなって永久変形が生じるが、元の状態に対してどれくらい変形したかを示す値がへたり量である。）を調べたところ、比較例１が０．３ｍｍであるのに対し、実施例１は０．２ｍｍであった。
【００６６】
◎実施例３
本実施例は、実施の形態１に係るクリーニングブレードの引き裂き強度測定を６０ロット行ったところ、図７に示すような結果が得られた。尚、ここで用いた引き裂き試験は、ＪＩＳ Ｋ６２５２ アングル型に準拠した。
同図によれば、いずれのクリーニングブレードも８０ｋｇ／ｃｍ以上の引き裂き強度のものが得られており、クリーニングブレードとして要求される７０ｋｇ／ｃｍ以上の要件を充分に満たしていることが確認される。
【００６７】
◎実施例４
本実施例は、使用するウレタンゴムの材料を異ならせたサンプルＡ〜Ｄを用意し、これらの環境依存性を調べたところ、図８及び図９に示す結果が得られた。
先ず、各サンプルＡ〜Ｄについて説明する。
サンプルＡ：
１，９−ノナンジオール／２−メチル−１，８−オクタンジオール（モル比６５／３５）とアジピン酸とから分子量２０００のポリエステルポリオールを得た。ポリエステルポリオール中のエステル濃度は、６．８ｍｍｏｌ／ｇである。
このポリエステルポリオールと、ＭＤＩおよび鎖延長剤としての１，３−プロパンジオール／トリメチロールエタン混合液とを用いて熱硬化型ウレタンゴムとし、クリーニングブレードを製造した。尚、ウレタンゴム中のポリエステルポリオールは約６５重量％とした。
サンプルＢ：
エチレングリコールとアジピン酸からなる分子量２０００のポリエステルポリオール（エステル濃度１１．３ｍｍｏｌ／ｇ）を用いた以外は、サンプルＡと同様にしてクリーニングブレードを製造した。尚、ウレタンゴム中のポリエステルポリオールは約６５重量％とした。
サンプルＣ：
ネオペンチルグリコールを開始剤とし、これにε−カプロラクトンを付加させて得た、数平均分子量２０００のポリエステルジオール（カプロラクトンＡ：エステル濃度８．５ｍｍｏｌ／ｇ）を用いた以外はサンプルＡと同様にしてクリーニングブレードを製造した。尚、ウレタンゴム中のポリエステルポリオールは約６５重量％とした。
サンプルＤ：
ドデカンジオールを開始剤とし、これにε−カプロラクトンを付加させて得た、数平均分子量１５００のポリエステルジオール（カプロラクトンＢ：エステル濃度７．６ｍｍｏｌ／ｇ）を用いた以外はサンプルＡと同様にしてクリーニングブレードを製造した。尚、ウレタンゴム中のポリエステルポリオールは約６５重量％とした。
【００６８】
実験例１：
各サンプルＡ〜Ｄについて、０℃〜５０℃の反発弾性係数を測定してその温度依存性を評価した。
この結果を図８及び図９に示す。
ここで、反発弾性係数はＪＩＳ Ｋ６２５５に準拠したリュプケ式反発弾性試験装置により求めた。
この結果より、サンプルＡは、サンプルＢ〜Ｄのものと比較して、反発弾性の温度依存性が著しく小さく、１０℃の反発弾性係数が２０％以上であり且つ４０℃の反発弾性係数が７０％以下であることがわかった。
【００６９】
実験例２：
各サンプルＡ〜Ｄのクリーニングブレードを用いて、クリーニング性能をＬＬ（１０℃１５％ＲＨ）、ＮＮ（２３℃５０％ＲＨ）、ＨＨ（３５℃８５％ＲＨ）の各条件で評価し、また、エッジの摩耗状態を観察した。尚、クリーニング性能は、平均粒径６μｍの略球状重合トナーを用いて行った。
この結果を図１０に示す。また、夫々の反発弾性のデータを併せて示した。
尚、図１０中のクリーニング性能は、クリーニングが良好にできたのを○、クリーニングができなかったのを×で示した。エッジの摩耗状態は、画像に支障をきたさない均一な摩耗を問題無、画像に不具合を生じる欠落などの不均一な摩耗を摩耗量大、食い込み量大で示した。また、図１０中、Ｒｂ_T10は１０℃の反発弾性係数，Ｒｂ_T40は４０℃の反発弾性係数を意味する。
この結果より、サンプルＡのクリーニングブレードは温度変化に対して安定したクリーニング性能を示し、低温時のクリーニング性能が良好で、高温使用時におけるエッジの耐久性が良好であることがわかった。
また、これらのサンプルは、１０℃の反発弾性が２０％以上かつ４０℃の反発弾性が７０％以下の値を示した。
【００７０】
これに対して、エステル濃度が高いサンプルＢ〜Ｄでは、エッジの摩耗状態は良好であったが、低温時のクリーニングが不良であった。このサンプルＢ〜Ｄは、１０℃の反発弾性係数が２０％より小さい値を示した。
また、サンプルＣでは、高温時のクリーニングが困難であることがわかった。このサンプルＣは、反発弾性の温度依存性が大きく、しかも、４０℃の反発弾性が７０％を超えていた。
更に、サンプルＤでは、エステル濃度が８ｍｍｏｌ／ｇより小さいポリエステルポリオールを用いたポリウレタンであるが、良好なクリーニングができなかった。このサンプルＤは、反発弾性の温度依存性が比較的小さく、４０℃の反発弾性係数が７０％より小さいが、反発弾性係数の最小値が２０℃であり、０℃より高い値を示した。
【００７１】
この結果から、粒径が比較的大きく、粉砕型の形状の従来のトナーではクリーニング特性が良好であった。ポリエチレンアジペートやポリカプロラクトンを原料としたポリエステル系ウレタンゴムでは、小粒径、真球度の高いトナーに対しては十分なクリーニング特性が得られず、このような小粒径、真球度の高いトナーに対してはサンプルＡの条件を満足するウレタンゴムを用いた方がより優れた特性が得られることがわかった。
【００７２】
◎実施例５
本実施例は、ウレタンゴムを製造するポリエステルポリオールのエステル濃度が６．８±０．２ｍｍｏｌ／ｇであることがクリーニング性能を良好に保つ為に必要であることを実験的に確認したものである。
ここで、、図１１はエステル濃度の算出式についての説明図、図１２はｎ値と分子量とに対するエステル濃度の変化例を示す説明図である。
図１１において、エステル濃度の計算方法は、ＮＤ／ＡＡ １：１の繰り返し１ユニットＦｗ＝２７０で、両端末がＨ₂Ｏ無しＮＤ（Ｆｗ＝１２６）であることを考慮して、図１１中の（４）式を満たすｎを計算し、そのときのＣＯＯ濃度で計算した。
尚、図１１中、Ｍｎは分子量、Ｆｗはアジピン酸と１，９−ノナンジオールとの合計の数平均分子量、また、（４）式中、数値”１８”はＨ₂Ｏの分子量を示す。
また、図１２において、ｍｍｏｌ値は、ポリエステルポリオールを１ｇ秤取った時のモル数を示す。
【００７３】
図１２に示すように、本実施の形態１に係るクリーニングブレードの配合系で、ポリエステルポリオールの分子量を１３００に、すなわち、エステル濃度を６．６ｍｍｏｌ／ｇ未満にすると、架橋点間分子量が短くなり、１０℃における反発弾性係数が２０％未満になる。
一方、その分子量を２８４４とし、エステル濃度が７．０ｍｍｏｌ／ｇを超えると、架橋点間分子量が長くなり、永久伸びが２．５％を超えてしまうと共に、３００％モジュラスが２００ｋｇ／ｃｍ^２未満となり、目的とする所望の物性が得られないことが確認される。
ちなみに、分子量が３０００を超えると、ポリエステルポリオールの粘度が急激に上昇し、ブレードに使用するシートが得られない状態になる。
【００７４】
【発明の効果】
以上説明してきたように、本発明によれば、クリーニングブレードとして、ウレタンゴムの好ましい材料を選定した上で、環境依存性を抑え且つ機械的強度の最適化を図るようにしたので、低温低湿から高温高湿な環境条件下において、略球形トナーに対するクリーニング性能を常時良好に保つことができる。
また、このようなクリーニングブレードを組み込んだクリーニング装置、プロセスカートリッジ又は画像形成装置によれば、高画質化を実現する上で有効な小径な略球形トナーを使用したとしても、クリーニングプロセス又は作像プロセスの中でクリーニング性能を常時良好に保つことが可能になるため、夫々のプロセスの信頼性を補償することができ、その分、夫々の装置性能を極めて良好に保つことができる。
【図面の簡単な説明】
【図１】 本発明に係るクリーニングブレード及びこれを用いたクリーニング装置、プロセスカートリッジ並びに画像形成装置の概要を示す説明図である。
【図２】 本発明が適用された画像形成装置の実施の一形態を示す説明図である。
【図３】 本実施の形態で用いられる作像エンジンの詳細を示す説明図である。
【図４】 実施例１及び比較例１，２における形状係数の異なるトナーに対する性能試験を示す説明図である。
【図５】 実施例２及び比較例１，２の反発弾性係数、永久伸び、３００％モジュラス、引き裂き強度及びクリーニングブレードの押し付け力を示す説明図である。
【図６】 （ａ）は実施例２及び比較例１，２の高温高湿条件下におけるクリーニング不良、ブレードダメージ、ブレード鳴き（異音）、像担持体の摩耗、へたり試験後のクリーニング不良の有無を評価した説明図、（ｂ）は中温中湿条件下における同様な評価説明図、（ｃ）は低温低湿条件下における同様な評価説明図である。
【図７】 実施例３で用いられるクリーニングブレードの引き裂き試験結果を示すグラフ図である。
【図８】 実施例４で用いられる各サンプルＡ〜Ｄにおける０℃〜５０℃の反発弾性係数の測定結果を示すグラフ図である。
【図９】 その温度依存性を評価した説明図である。
【図１０】 実施例４で用いられる各サンプルＡ〜Ｄについて、各環境条件下でのクリーニング性能を評価し、また、エッジの摩耗状態の観察結果を示す。
【図１１】 エステル濃度の算出式についての説明図である。
【図１２】 実施例５で用いられるクリーニングブレードのｎ値と分子量とに対するエステル濃度の関係を示す説明図である。
【符号の説明】
１…像担持体，２…クリーニングブレード，３…クリーニング装置[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a cleaning blade that is mainly used in an image forming apparatus such as a copying machine, a printer, a facsimile machine, and a multifunction machine using an electrophotographic method or an electrostatic recording method, and cleans residual toner on an image carrier. In particular, the present invention relates to a cleaning blade effective for cleaning performance when a small spherical toner having a small diameter is used as a developer, and a cleaning device, a process cartridge, and an image forming apparatus using the cleaning blade.
[0002]
[Prior art]
In general, in an electrophotographic method or an electrostatic recording method, an electrostatic latent image is formed on an image carrier such as a photosensitive member, and then the electrostatic latent image is visualized with toner as a developer. Subsequently, an image forming method is employed in which an image is formed on a recording material through a transfer process and a fixing process for the visualized toner image.
In this type of image forming system, since the residual toner remains on the image carrier after the normal transfer process, a cleaning device is provided to clean it.
Various types of cleaning devices of this type are known. Typically, a cleaning blade (usually using a contact plate having elasticity) is placed in contact with an image carrier so that the image is carried. In many cases, a blade cleaning system is employed in which residual toner on the body is scraped off by the blade.
[0003]
The toner as the developer is produced by a kneading and pulverizing method in which, for example, a thermoplastic resin is melted and kneaded together with a release agent such as a pigment, a charge control agent and wax, cooled, finely pulverized, and further classified. In addition, inorganic fine particles or organic fine particles may be added to the toner particle surfaces as necessary in order to improve fluidity and cleaning properties.
However, such an image forming apparatus is also required to provide a high-quality information document with the development of a highly advanced information society in recent years. In order to realize a higher-definition image in color image formation according to the above, development of technology for reducing the diameter of toner particles, sharp particle size distribution, and spheroidization of toner particles is underway.
In this case, particularly when the toner particles are spheroidized, the contact area with the image carrier on which the spherical toner particles are carried can be kept to a minimum, so that the adhesion force to the image carrier is suppressed. Thus, the transferability in the transfer process is improved, and this is preferable in that the final improvement in image quality characteristics such as fine line reproducibility can be expected.
[0004]
[Problems to be solved by the invention]
However, when the blade cleaning method is employed in an image forming apparatus using substantially spherical toner, there is a high probability that the substantially spherical toner slips between the blade and the image carrier due to its shape, and cleaning failure is likely to occur. Therefore, the image quality is likely to deteriorate due to the poor cleaning.
Therefore, in order to achieve high image quality in the image forming apparatus, it is important to prevent poor cleaning of the substantially spherical toner.
[0005]
Therefore, conventionally, as a countermeasure for preventing poor cleaning with respect to the substantially spherical toner, for example, an attempt has been made to increase the linear pressure applied to the edge portion of the blade and prevent the spherical toner from slipping through.
However, this measure by simply increasing the linear pressure promotes wear of the blade edge, abnormal noise due to blade chatter vibration, and accelerated wear of the image carrier due to blade contact. There are specific issues.
Also, in order to improve the occurrence of each wear and noise, a measure to reduce the friction coefficient of the blade edge by supplying submicron (about 0.2μm or less) fine particles as a lubricant to the blade edge is proposed. Has been.
However, when such sub-micron lubricant fine particles are used, the effect is initially present, but the effect is reduced after deterioration over time when the image carrier and blade edge are worn and scratched. There is a technical problem that the sub-micron fine particles of the lubricant pass through the blade edge, for example, contaminate the charging device to induce a charging failure and cause a reduction in image quality.
In the worst case, the lubrication effect does not partially occur, causing local chipping of the blade edge, resulting in poor cleaning, and degrading image quality such as streak-like printing.
[0006]
Further, a method has been proposed in which sub-micron (about 0.2 μm or less) amorphous inorganic fine particles are supplied to the blade edge portion to form a seal layer on the blade edge portion to make it difficult for the spherical toner to slip through. Yes.
In this method, for example, silica or alumina having an irregular shape as amorphous inorganic fine particles is supplied to the blade edge portion and attempts to prevent slipping based on a mechanism of trapping substantially spherical toner particles that are easily slipped by these irregular fine particles. Is.
However, since this method also uses a small particle size of submicron, the same technical problem as in the case of using the lubricant fine particles occurs.
[0007]
In addition to this, a method (for example, JP-A-8-62893 and JP-A-8-95286) has been proposed in which substantially spherical toner and irregular toner are mixed at a specific ratio.
However, even in such a method, since the substantially spherical toner may pass through the gap between the irregular toner and advance to the blade edge portion, the cleaning defect with respect to the substantially spherical toner is not sufficiently improved. .
[0008]
The cleaning blade is made of, for example, urethane rubber. It is known that this urethane rubber has temperature dependency, and this temperature dependency greatly affects the resilience resilience of the cleaning blade.
For example, if the impact resilience decreases in a low-temperature and low-humidity environment, cleaning may be defective, and if the impact resilience greatly increases in a high-temperature and high-humidity environment, there is a concern that abnormal noise may occur due to missing or turning blade edges or chatter vibration. .
Therefore, in a cleaning blade made of this type of urethane rubber, trial and error studies have been conducted as an important solution issue on how to suppress environmental dependency.
[0009]
In order to solve the technical problems described above, the present invention reliably prevents poor cleaning of a substantially spherical toner under low-temperature low-humidity to high-temperature high-humidity environmental conditions. The present invention provides a cleaning blade, a cleaning device using the same, a process cartridge, and an image forming apparatus capable of maintaining good cleaning performance with respect to a substantially spherical toner under conditions.
[0010]
[Means for Solving the Problems]
In order to solve such a technical problem, the present inventors have studied how much the dependency on the environment should be suppressed for a cleaning blade made of urethane rubber. As a result, the resilience coefficient, 300% modulus, and tearing A proposal has been made to optimize the mechanical properties of the strength within a predetermined range under environmental conditions so as to improve the cleaning failure of the substantially spherical toner while suppressing the influence of the environmental dependency.
Thereafter, the present inventors further examined the relationship between the mechanical properties of the cleaning blade and the material conditions, and found that the mechanical properties of the cleaning blade can be easily optimized under predetermined material conditions. The present invention has been devised.
[0011]
That is, as shown in FIG. 1, the present invention is a cleaning blade 2 that is disposed in contact with an image carrier 1 and cleans residual toner on the image carrier 1, and is formed of a specific urethane rubber described later. (1) The coefficient of rebound resilience (JIS K6255) is in the range of 20% or more at 10 ° C and 70% or less at 40 ° C, (2) 300% modulus (JIS K6251) is 200 kg / cm² It is characterized by satisfying the physical property conditions of (3) tear strength (JIS K6252 angle type) of 70 kg / cm or more.
[0012]
In such technical means, the image carrier 1 includes a wide variety of image carriers. The image carrier such as a photoconductor as well as the image on the image carrier are directly or indirectly supported. And an image bearing carrier (intermediate transfer member or recording material carrier) to be conveyed.
The urethane rubber applied in the present invention uses a polyester polyol obtained by dehydration condensation of a diol and a dibasic acid as a long-chain polyol.
Here, as the diol, diol component 1 (1,9-nonanediol) and diol component 2 (methyl-1,8 octanediol) were mixed in a molar ratio of (65 ± 3) :( 35 ± 3). Things are used.
However, the molar ratio “± 3” is the standard width.
[0013]
  Furthermore, the polyester polyol needs to have an ester concentration in the range of 6.6 to 7.0 mmol / g.
  However, ester concentration (mmol / g)
      = (Number of moles of ester group) / (weight of polyester)
Defined by
  That is, the ester concentration is 6.6 to 7.0 mmo.lIn urethane rubber using polyester polyol of / g, the temperature dependence of rebound resilience is reduced, rebound resilience at a low temperature range is ensured to some extent, and an increase in rebound resilience at a high temperature range is suppressed. Therefore, the rebound resilience coefficient condition can be easily satisfied.
  In addition, since the mechanical strength is sufficiently secured, the 300% modulus condition and the tear strength condition can be easily satisfied.
  Thus, the ester concentration is 6.6 to 7.0 mmo.l/ G is suitable for achieving both mechanical strength and temperature dependence of impact resilience.
[0014]
Here, when the ester concentration exceeds the upper limit value, the temperature dependence of the resilience increases. In other words, the rebound resilience coefficient at low temperatures is less than 20% at 10 ° C., and the occurrence of defective cleaning is observed. In the case of a high temperature, the rebound resilience coefficient exceeds 70% at 40 ° C. Along with this, the stick-slip motion becomes intense, the edge of the cleaning blade 2 is damaged, and toner slipping due to chipping is seen, which is not preferable.
On the other hand, if the ester concentration is lower than the lower limit, the content of the hard segment specific to urethane is remarkably lowered and the mechanical strength is also lowered.
[0015]
In order to produce urethane rubber using the polyester polyol described above, polyisocyanate is blended and reacted with the polyester polyol and the short-chain polyol as the chain extender.
Here, 1,3-propanediol and trimethylolethane are used as the short-chain polyol, and the short-chain polyol contains 85 to 90% of 1,3-propanediol.
For the reaction, a general method for producing urethane rubber such as a prepolymer method or a one-shot method can be used. The prepolymer method is suitable for the present invention because urethane rubber having excellent strength and wear resistance can be obtained, but is not limited by the production method.
In the urethane rubber used in the present invention, the long-chain polyol in the urethane rubber is preferably 60 to 80% by weight.
Furthermore, in the present invention, in addition to the predetermined polyester polyol described above, other polyols can be used in combination as long as the effects of the present invention are not impaired. The content of the polyester polyol is 90 to 30 in the long-chain polyol. It is preferable that it is weight%.
[0016]
Next, rebound resilience coefficient conditions will be described as follows.
That is, in order to ensure the cleaning performance with the conventional cleaning blade under the low temperature and low humidity conditions, the pressing force of the cleaning blade to the image carrier 1 may be increased. The wear amount of the body 1 is increased, and the life of the image carrier 1 is shortened.
However, in the cleaning blade 2 according to the present invention, since the rebound resilience coefficient (JIS K6255) is in the range of 20% or more at 10 ° C. and 70% or less at 40 ° C., temperature dependency (fluctuation) Less is.
In this case, in order to improve the cleaning performance under low-temperature and low-humidity conditions, even if the rebound resilience on the low temperature side is set to a certain level, the increase in rebound resilience on the high temperature side is small.
Accordingly, it is possible to use a material having a large rebound resilience on the low temperature side, and accordingly, it is possible to ensure the cleaning performance without increasing the pressing force on the low temperature side.
Moreover, since rebound resilience on the high temperature side is suppressed, turning and chipping under high temperature and high humidity conditions can be suppressed.
[0017]
In the present invention, 300% modulus (JIS K6251) is 200 kg / cm.²Further, the tear strength (JIS K6252 angle type) is 70 kg / cm or more.
As described above, when the 300% modulus and the tear strength are high, it is possible to suppress the minute chipping of the cleaning blade 2.
[0018]
As described above, if the material of the cleaning blade 2 is selected, it is possible to easily select each physical property condition (reduction in influence of environment dependency, mechanical strength).
Therefore, according to the present invention, it is not necessary to unnecessarily increase the pressing force on the image carrier 1 in order to ensure the cleaning performance, and the cleaning performance can be ensured satisfactorily in all use environments. In addition, the wear amount of the image carrier 1 can be reduced.
Further, even when the discharge product adheres to the surface of the image carrier 1 or the surface is denatured and the surface friction coefficient of the image carrier 1 is increased, noise (squeal) due to vibration of the cleaning blade 2 is reduced. can do.
[0019]
In the cleaning blade 2 of the present invention, if permanent elongation (JIS K6262) is 2.5% or less, the image carrier 1 after being left for a long time under high temperature and high humidity conditions. This is preferable in that the pressing force is less reduced and the cleaning performance can be secured.
[0020]
  In particular, the cleaning blade 2 of the present invention isWhen used with an image forming device,Although it is advantageous for high image quality, it is effective to use a small-diameter, generally spherical toner, which is usually difficult to clean, and specifically, a toner having a shape factor SF of less than 140 and a volume average particle diameter of 2-8 μm. Therefore, it is extremely effective when these are to be cleaned.
  Here, the shape factor SF is defined by the following equation.
  SF = {M²/ (A × 4π)} × 100
  Where M is the maximum perimeter of the toner particles, and A is the projected area of the particles.
  On the other hand, when the shape factor SF exceeds 140, the toner particles enter an atypical region, and it becomes difficult to obtain good transferability with a substantially spherical toner, and it is difficult to improve the image quality of the obtained image.
  On the other hand, when the volume average particle diameter of the toner is smaller than 2 μm, the particles are small, and appropriate development characteristics and cleaning performance cannot be obtained. On the other hand, if the volume average particle diameter is larger than 8 μm, the particles are too large and the image becomes rough, which is disadvantageous for improving the image quality.
[0021]
As shown in FIG. 1, the present invention is not limited to the cleaning blade 2 as described above, but also covers a cleaning device 3 using the same.
In this embodiment, the cleaning device 3 includes a wide range of devices including a cleaning blade 2 disposed in contact with the image carrier 1.
For this reason, the cleaning device 3 is not limited to having one cleaning blade 2, and may have a plurality of cleaning blades 2, and other cleaning members such as a cleaning brush may be arranged upstream of the cleaning blade 2. You can select the appropriate ones.
[0022]
The present invention is also directed to a process cartridge.
In this case, the present invention is a process cartridge including an image carrier 1 and a cleaning device 3 having the above-described cleaning blade 2 as shown in FIG.
This process cartridge usually includes a developing device that visualizes the electrostatic latent image on the image carrier 1 with toner. However, since the process cartridge may have a separate developing device, here, The development device is not an indispensable requirement, and the process cartridge is widely targeted.
[0023]
Furthermore, the present invention is also directed to an image forming apparatus.
In this case, according to the present invention, as shown in FIG. 1, in the image forming apparatus having one or a plurality of cleaning devices 3, the above-described cleaning blade 2 is incorporated in at least one of the cleaning devices 3.
Therefore, even if the cleaning blade 2 of the present invention is used for any one of the plurality of cleaning devices 3 and a cleaning member other than the present invention is used for the other cleaning devices 3, it is within the scope of the present invention.
However, in an image forming apparatus having a plurality of cleaning devices 3, from the viewpoint of satisfactorily suppressing the cleaning performance, an embodiment in which the cleaning blade 2 of the present invention is used for all the cleaning devices 3 is preferable.
Further, the image carrier 1 includes an image forming carrier that forms and carries a toner image, and an image carrier that carries the toner image on the image forming carrier directly or indirectly. In this case, the cleaning blade 3 of the present invention incorporated in the cleaning device 3 provided on the image forming carrier is also within the scope of the present invention.
[0024]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail based on embodiments shown in the accompanying drawings.
Embodiment 1
FIG. 2 is an explanatory view showing Embodiment 1 of a tandem type image forming apparatus to which the present invention is applied.
In the figure, the tandem type image forming apparatus has four image forming engines 22 (specifically, 22a to 22d) in the horizontal direction in a main body housing 21 (in this embodiment, black, yellow, magenta, and cyan). A belt module 23 including an intermediate transfer belt 230 that is circulated and conveyed along the direction in which the image forming engines 22 are arranged is arranged above the image forming engine 22. A recording material supply cassette 24 in which a material (not shown) is accommodated is disposed, and a recording material conveyance path 25 serving as a conveyance path for the recording material from the recording material supply cassette 24 is disposed in the vertical direction. .
[0025]
In the present embodiment, the image forming engines 22 (22a to 22d) are, for example, for black, yellow, magenta, and cyan in order from the upstream side in the circulation direction of the intermediate transfer belt 230. (Not limited) toner image, each photosensitive unit 30, each developing unit 33, and one common exposure unit 40.
Here, the photosensitive unit 30 includes, for example, a photosensitive drum 31, a charging device (charging roll in this example) 32 that precharges the photosensitive drum 31, and a cleaning device that removes residual toner on the photosensitive drum 31. 34 is integrated into a sub-cartridge.
The developing unit 33 develops the electrostatic latent image exposed and formed by the exposure unit 40 on the charged photosensitive drum 31 with a corresponding color toner (for example, negative polarity in the present embodiment). For example, a process cartridge (so-called CRU: Customer Replaceable Unit) is configured by being integrated with a sub-cartridge including the photosensitive unit 30.
Of course, the photoconductor unit 30 may be separated from the developing unit 33 to form a single CRU. In FIG. 2, reference numeral 35 (35a to 35d) denotes a toner cartridge for supplying each color component toner to each developing unit 33 (a toner supply path is not shown).
[0026]
On the other hand, the exposure unit 40 includes, for example, four semiconductor lasers (not shown), one polygon mirror 42, an imaging lens (not shown), and mirrors (see FIG. (Not shown), the light from the semiconductor laser for each color component is deflected and scanned by the polygon mirror 42, and the light image is guided to the exposure point on the corresponding photosensitive drum 31 via the imaging lens and mirror. It is a thing.
[0027]
Further, in the present embodiment, the belt module 23 is obtained by, for example, spanning the intermediate transfer belt 230 between a pair of stretching rolls (one of which is a drive roll) 231 and 232, and the photoreceptor of each photoreceptor unit 30. A primary transfer device (primary transfer roll in this example) 51 is disposed on the back surface of the intermediate transfer belt 230 corresponding to the drum 31, and a voltage having a polarity opposite to the toner charging polarity is applied to the primary transfer device 51. The toner image on the photosensitive drum 31 is electrostatically transferred to the intermediate transfer belt 230 side.
Further, a secondary transfer device 52 is disposed at a portion corresponding to the tension roll 232 on the downstream side of the most downstream image forming engine 22d of the intermediate transfer belt 230, and the primary transfer image on the intermediate transfer belt 230 is recorded. Secondary transfer (collective transfer) is performed on the material.
[0028]
In the present embodiment, the secondary transfer device 52 includes a secondary transfer roll 521 that is disposed in pressure contact with the toner image carrying surface side of the intermediate transfer belt 230, and a secondary transfer roll that is disposed on the back side of the intermediate transfer belt 230. A backup roll (in this example, also serving as a stretching roll 232) is provided.
For example, the secondary transfer roll 521 is grounded, and a bias having the same polarity as the charging polarity of the toner is applied to the backup roll (stretching roll 232).
Furthermore, a belt cleaning device 53 is disposed on the upstream side of the most upstream image forming engine 22a of the intermediate transfer belt 230 so as to remove residual toner on the intermediate transfer belt 230.
[0029]
The recording material supply cassette 24 is provided with a feed roll 61 for picking up the recording material. A takeaway roll 62 for feeding the recording material is disposed immediately after the feed roll 61, and at the secondary transfer site. A registration roll (registration roll) 63 for supplying the recording material to the secondary transfer portion at a predetermined timing is disposed in the recording material conveyance path 25 positioned immediately before.
On the other hand, a fixing device 66 is provided in the recording material conveyance path 25 located on the downstream side of the secondary transfer site, and a discharge roll 67 for discharging the recording material is provided on the downstream side of the fixing device 66. The discharged recording material is accommodated in a discharge tray 68 formed on the upper portion of the housing 21.
[0030]
Further, in the present embodiment, a manual feed device (MSI) 71 is provided on the side of the main body housing 21, and the recording material on the manual feed device 71 is recorded by the feed roll 72 and the takeaway roll 62. It is sent out toward the material conveyance path 25.
Further, the main body housing 21 is provided with a double-sided recording unit 73. The double-sided recording unit 73 discharges the recording material on which single-sided recording has been performed when the double-sided mode in which image recording is performed on both sides of the recording material is selected. 67 is reversed and taken in by the guide roll 74 in front of the entrance, and the recording material is conveyed along the internal recording material return conveyance path 76 by an appropriate number of conveyance rolls 77, and again toward the registration roll 63 side. And supply.
[0031]
Next, the cleaning device 34 used in the present embodiment will be described in detail.
In FIG. 3, the cleaning device 34 has a cleaning case 341 that contains residual toner and opens to face the photosensitive drum 31, and the cleaning case 341 has a lower edge of the opening disposed in contact with the photosensitive drum 31. A cleaning blade 342 is attached via a bracket (not shown), and a film seal 344 is attached to the upper edge of the opening of the cleaning case 341 so as to keep airtight with the photosensitive drum 31. Reference numeral 345 denotes a transport auger that guides waste toner accommodated in the cleaning case 341 to a side waste toner container.
[0032]
Further, the cleaning blade 342 according to the present embodiment is formed of urethane rubber which is an elastic material.
This urethane rubber uses polyester polyol obtained by dehydration condensation of diol and dibasic acid as a long-chain polyol.
Particularly suitable in terms of performance and cost are diol component 1 (1,9-nonanediol) and diol component 2 (methyl-1,8-octanediol) in a predetermined molar ratio (in this example, (65 ± 3): A polyester polyol obtained by dehydration condensation of the diol mixed in (35 ± 3)) and adipic acid.
Of course, those having these as the main components and having some components substituted with other glycols or dibasic acids can also be suitably used.
Here, methyl-1,8-octanediol is an octanediol having a methyl group at a position other than 1 or 8, and a typical one is 2-methyl-1,8-octanediol. It is not limited to.
The polyester polyol has an ester concentration of 6.6 to 7.0 mmol / g.
[0033]
Examples of the polyisocyanate to be reacted with the polyester polyol include 2,6-toluene diisocyanate (TDI), 4,4′-diphenylmethane diisocyanate (MDI), paraphenylene diisocyanate (PPDI), 1,5-naphthalene diisocyanate (NDI), Examples include 3,3-dimethyldiphenyl-4,4′-diisocyanate (TODI). In particular, MDI is preferable in terms of performance and cost.
[0034]
In order to produce urethane rubber using the polyester polyol described above, polyisocyanate is blended and reacted with the polyester polyol and the short-chain polyol as the chain extender. For the reaction, a general method for producing polyurethane such as a prepolymer method or a one-shot method can be used.
Here, 1,3-propanediol and trimethylolethane are used as the short-chain polyol, and those containing 85 to 90% of 1,3-propanediol in the short-chain polyol are used.
[0035]
The mechanical properties of the cleaning blade 342 according to the present embodiment are as follows.
・ Rebound resilience coefficient:
This is based on JIS K6255, and needs to be in the range of 20% or more at 10 ° C. and 70% or less at 40 ° C.
300% modulus:
This conforms to JIS K6251 and is 200 kg / cm.² That is necessary.
・ Tear strength:
This conforms to the angle type of JIS K6252 and needs to be 70 kg / cm or more.
・ Permanent elongation:
This is based on JIS K6262 and needs to be 2.5% or less, preferably 1% or less, more preferably 0.5% or less.
・ Pressing pressure:
This is the contact pressure of the cleaning blade 342 with respect to the photosensitive drum 31, and is 3.0 to 6.0 gf (= 3.0 to 6.0 × 10^-3× 9.8 N) / mm or so.
[0036]
In the present embodiment, the same cleaning blade 342 is used in all the cleaning devices 34 of the image forming engines 22 (22a to 22d), and the cleaning blade 531 used in the belt cleaning device 53 is also described above. A material having the same physical properties as the cleaning blade 342 is used.
[0037]
Further, the developing unit (developing device) 33 used in the present embodiment has a unit case 331 that contains a developer and opens to face the photosensitive drum 31, as shown in FIG. A developing roll 332 is disposed at a position facing the opening of the unit case 331, and a transport auger 333 for stirring and transporting the developer is disposed in the unit case 331. Further, the developing roll 332, the transport auger 333, A conveyance paddle 334 is disposed between the two, as necessary, and after the developer is supplied to the developing roll 332, the developer is opposed to the photosensitive drum 31 with the layer thickness regulated by the trimming member 335, for example. It is transported to the development area and used for development.
In the present embodiment, as the developing unit 33, for example, an embodiment using a two-component developer composed of toner and carrier is shown, but an embodiment using a one-component developer using only toner, etc. It may be selected as appropriate.
[0038]
Here, the toner used in the present embodiment is a small-diameter substantially spherical toner.
That is, the toner is a spherical particle having a shape factor SF of less than 140, preferably 135 or less, more preferably 120 or less.
When the shape factor SF is 140 or more, the toner particles are indeterminate in a non-spherical shape, and it becomes difficult to obtain good transferability and the like, and it is difficult to improve the image quality of the obtained image.
On the other hand, the toner particles preferably have a volume average particle diameter of 2 to 8 μm from the viewpoint of improving the image quality.
[0039]
The toner particles contain a binder resin and a colorant as essential components, and optionally contain a release agent or a release agent resin. As the binder resin, a binder resin conventionally used for toner can be used and is not particularly limited.
Specifically, styrenes such as styrene, parachlorostyrene, and α-methylstyrene; acrylic monomers such as methyl acrylate, ethyl acrylate, n-propyl acrylate, lauryl acrylate, and 2-ethylhexyl acrylate Methacrylic monomers such as methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, lauryl methacrylate and 2-ethylhexyl methacrylate; ethylenically unsaturated acids such as acrylic acid, methacrylic acid and sodium styrenesulfonate Polymers; Vinyl nitriles such as acrylonitrile and methacrylonitrile; Vinyl ethers such as vinyl methyl ether and vinyl isobutyl ether; Vinyl ketones such as vinyl methyl ketone, vinyl ethyl ketone and vinyl isopropenyl ketone; Ethylene, propylene Homopolymer consisting of a monomer such as olefins such as butadiene, copolymers combinations thereof monomers of two or more, or the like mixtures thereof. Furthermore, to these homopolymers, copolymers or mixtures, epoxy resins, polyester resins, polyurethane resins, polyamide resins, cellulose resins, polyether resins, etc., non-vinyl condensation resins, or those and the vinyl resins And a graft polymer obtained by polymerizing a vinyl monomer in the presence of these.
[0040]
A conventionally known colorant can be used as the colorant, and is not particularly limited.
For example, carbon black, chrome yellow, hansa yellow, benzidine yellow, selenium yellow, quinoline yellow, permanent orange GTR, pyrazolone orange, vulcan orange, watch young red, permanent red, brilliantamine 3B, brilliantamine 6B, dapon oil red, Various pigments such as pyrazolone red, resol red, rhodamine B lake, lake red C, rose bengal, aniline blue, ultramarine blue, calco oil blue, methylene blue chloride, phthalocyanine blue, phthalocyanine green, malachite green oxalate, acridine series , Xanthene, azo, benzoquinone, azine, anthraquinone, thioindico, dioxazine , Thiazine, azomethine, indico, thioindico, phthalocyanine, aniline black, polymethine, triphenylmethane, diphenylmethane, thiazine, thiazole, xanthene, etc. The above can be used together.
[0041]
The release agent or release agent resin that is optionally contained in the toner particles may be added as a part of the binder resin component.
The release agent used here includes low molecular weight polyolefins such as polyethylene, polypropylene and polybutene; fatty acid amides such as silicones, oleic acid amide, erucic acid amide, ricinoleic acid amide and stearic acid amide; carnauba wax Plant waxes such as beeswax, rice wax, candelilla wax, tree wax, jojoba oil, etc .; animal waxes such as beeswax; minerals such as montan wax, ozokerite, ceresin, paraffin wax, microcrystalline wax, Fischer-Tropsch wax, etc. And petroleum-based waxes, and modified products thereof. At least one of these may be contained in the toner particles.
[0042]
In addition to the above components, the toner particles can contain various components in order to control various characteristics. For example, when used as a magnetic toner, a magnetic powder (for example, ferrite or magnetite), a metal such as reduced iron, cobalt, nickel, or manganese, an alloy, or a compound containing these metals may be included. Further, if necessary, a charge control agent usually used such as a quaternary ammonium salt, a nigrosine compound or a triphenylmethane pigment may be appropriately selected and contained.
[0043]
The method for obtaining the toner particles satisfying the above conditions is not particularly limited. For example, an irregularly shaped toner particle selected by a normal pulverization method is spherically shaped so as to satisfy the above conditions by a mechanical impact force. By known high-speed mechanical impact method, which is produced by spheroidization, wet melt spheronization method, which is produced by spheroidizing irregularly shaped toner in a dispersion medium, suspension polymerization, dispersion polymerization, emulsion polymerization aggregation method, etc. For example, a spherical toner manufacturing method can be used.
[0044]
As a more preferable aspect of the toner, a toner obtained by externally adding specific irregularly shaped fine particles, monodispersed spherical silica and a small-diameter organic compound to substantially spherical toner particles, or a specific abrasive is added to substantially spherical toner particles. Examples thereof include a toner externally added with fine particles, monodispersed spherical silica, and a small-diameter organic compound.
Here, the amorphous fine particles to be externally added to the toner particles have irregular shapes having a shape factor of 130 or more, preferably 135 to 150, more preferably 140 to 145.
This shape factor is the same as the shape factor SF of the toner particles described above. If the value of the shape factor is too low, a sufficient effect as a sealant cannot be obtained at the blade edge portion of the cleaning device.
[0045]
The irregular fine particles are fine particles having a polarity opposite to the charging polarity of the toner.
Moreover, the irregular fine particles have a particle size of 0.1 to 1.0 times the volume average particle size of the toner particles.
Specifically, the volume average particle diameter is in the range of 0.5 to 10 μm, preferably 0.7 to 5 μm, more preferably 1 to 3 μm. When the volume average particle diameter of the fine particles becomes a value less than 0.1 times (less than 0.5 μm) with respect to the volume average particle diameter of the toner particles, the irregular fine particles as a sealant for the blade edge portion in the cleaning device Since the supply is not sufficiently performed, there is a tendency that good cleaning characteristics cannot be obtained.
On the other hand, if the volume average particle diameter exceeds 1.0 times the value (10 μm) of the volume average particle diameter of the toner particles, the particles are likely to scatter in the developing device and cause contamination in the image forming apparatus. It tends to be easier.
[0046]
The material of the irregular fine particles is not particularly limited, and for example, various resin components shown as the binder resin for the toner particles can be used.
And, as a method for obtaining the irregular fine particles, resin fine particles are produced by the existing resin pulverization method using the resin component, or the existing emulsification method or dispersion method in a liquid medium such as water or an organic solvent. Can be used.
[0047]
The abrasive fine particles added externally to the toner particles are fine particles having a polarity opposite to the charged polarity of the toner. Moreover, the fine particles are particles having a volume average particle diameter in the range of 0.3 to 2 μm, preferably 0.5 to 1.5 μm.
When the abrasive fine particles have a volume average particle size of less than 0.3 μm, slipping occurs at the blade edge portion of the cleaning device, and the abrasive fine particles cannot be accumulated in the blade edge portion, so that a good polishing effect is obtained. There is a tendency that good cleaning characteristics cannot be obtained. On the other hand, when the volume average particle diameter exceeds 2 μm, the external addition strength with the toner particles becomes weak, and the particles are likely to be scattered in the developing device and the like, and the image forming apparatus tends to be contaminated.
[0048]
Further, the monodispersed spherical silica externally added to the toner particles has a specific gravity of 1.3 to 1.9 and an average particle size of 80 to 300 nm.
By controlling the specific gravity to 1.9 or less, peeling of the spherical silica from the toner particles can be suppressed, and conversely, by controlling the specific gravity to 1.3 or more, aggregation and dispersion can be suppressed. Further, when the average particle diameter is smaller than 80 nm, the effect as a transfer aid is lowered, and when it is larger than 300 nm, there is a problem that it is difficult to externally add to the toner particles. Since this silica is monodispersed and spherical, it is uniformly dispersed on the surface of the toner particles, and a stable spacer effect is obtained.
[0049]
Here, the definition of monodispersion can be discussed by the standard deviation with respect to the average particle size including aggregates, and it is desirable that the standard deviation is D50 * 0.22 or less. As the definition of the sphere, it can be discussed by Wadell's sphericity, and the sphericity is 0.6 or more, preferably 0.8 or more. Further, the reason for limiting to silica is that its refractive index is around 1.5, and even if the particle size is increased, the transparency decreases due to light scattering, especially on an OHP (overhead projector) by forming an image on an OHP sheet. It does not affect the PE value at the time of image collection. General spherical silica having a specific gravity of 2.2 and a particle size of 50 nm at the maximum is the limit from the viewpoint of production. In this case, uniform dispersion to toner particles and a stable spacer effect cannot be obtained.
[0050]
Such monodispersed spherical silica can be obtained by a sol-gel method which is a wet method. The specific gravity of the silica at this time can be controlled to be lower than that of the vapor phase oxidation method because it is prepared by a wet method and without firing. Further, it is possible to further adjust by controlling the type of hydrophobic treatment agent or the amount of treatment in the hydrophobization treatment step. The particle size can be freely controlled by the sol-gel hydrolysis, the weight ratio of alkoxysilane, ammonia, alcohol, water in the condensation polymerization step, the reaction temperature, the stirring rate, and the supply rate. Monodisperse and spherical shapes can also be achieved by creating this method.
[0051]
Specifically, tetramethoxysilane is dropped and stirred while applying temperature using ammonia water as a catalyst in the presence of water and alcohol. Next, the silica sol suspension prepared by the reaction is centrifuged and separated into wet silica gel, alcohol, and aqueous ammonia. Next, a solvent is added to wet silica gel to form a silica sol again, and then a hydrophobic treatment agent is added to hydrophobize the silica surface. A general silane compound can be used as the hydrophobizing agent. Next, the target monodispersed silica can be obtained by removing the solvent from the hydrophobized silica sol, drying, and sieve. Moreover, you may hydrophobize again the silica obtained in this way. The said silane compound can use what is water-soluble. Examples of such silane compounds include chemical structural formula Ra SiX4-a (wherein a is an integer of 0 to 3, R represents an organic group such as a hydrogen atom, an alkyl group and an alkenyl group, and X represents a chlorine atom) Represents a hydrolyzable group such as a methoxy group and an ethoxy group.), And any type of chlorosilane, alkoxysilane, silazane, and a special silylating agent can be used. is there. Of these hydrophobizing agents comprising a silane compound, particularly preferred are dimethyldimethoxysilane, hexamethyldisilazane, methyltrimethoxysilane, isobutyltrimethoxysilane, decyltrimethoxysilane and the like.
[0052]
Further, the organic compound having a small diameter externally added to the toner particles has a diameter smaller than that of the monodispersed spherical silica, specifically 80 nm or less, more preferably 50 nm or less.
The reason for using such a small-diameter organic compound is that it is necessary to sufficiently coat the surface of the toner particles in order to control the fluidity and charge of the toner, but the above-mentioned spherical silica alone cannot be sufficiently coated. To supplement it.
[0053]
The small-diameter organic compound and the monodispersed spherical silica are coated on the toner particles by the procedure of first mixing the monodispersed spherical silica with the toner and then adding and mixing the small-diameter organic compound. This is a procedure in which a small-diameter organic compound and monodispersed spherical silica are simultaneously added to and mixed with toner particles, and the small-diameter organic compound selectively adheres to the toner surface. This is because the spherical silica is easily released from the toner particles, and in the procedure of adding and mixing the monodispersed spherical silica after adding and mixing the organic compound having a small diameter, the toner fluidity becomes extremely high. This is because it is difficult to uniformly disperse the spherical silica to be added and mixed without affecting the toner particles.
[0054]
The above irregular or abrasive fine particles, monodispersed spherical silica and small-sized organic compounds (hereinafter collectively referred to as “aggregated fine particles”) preferably do not contain a colorant. This is to prevent image defects caused by some of the fine particles included in the toner image together with the toner particles when transferred and fixed.
Then, the toner for development used in the present embodiment can be prepared by externally adding and aggregating the agglomerated fine particles obtained as described above to the toner particles described above at a certain ratio.
In this case, the external addition ratio is 0.3 to 10 parts by weight, preferably 0.5 to 5 parts by weight, more preferably 1 when the total amount of toner particles and aggregated particles is 100 parts by weight. ~ 3 parts by weight. If the amount of the aggregated particles added is less than 0.3 parts by weight, a good cleaning effect on the spherical toner tends not to be obtained sufficiently. And the flow characteristics tend to be significantly impaired.
[0055]
In the image forming apparatus according to this embodiment, when the toner composed of spherical toner particles externally added with the above irregular or abrasive fine particles, monodispersed spherical silica, and a small-diameter organic compound is used. In view of obtaining a better cleaning effect with respect to the substantially spherical toner.
[0056]
Next, the operation of the image forming apparatus according to the present embodiment will be described.
First, when each image forming engine 22 (22a to 22d) forms each color component toner image, each color component toner image is sequentially primary-transferred to the intermediate transfer belt 230, and thereafter, the secondary transfer device 52 batches the recording material onto the recording material. The recording material to which the unfixed toner image has been transferred is subjected to a fixing process by the fixing device 66 and then discharged to the discharge tray 68.
On the other hand, in each image forming engine 22 (22a to 22d), the residual toner on the photosensitive drum 31 is cleaned by the cleaning device 34, and the residual toner on the intermediate transfer belt 230 is cleaned by the belt cleaning device 53. The
[0057]
In such an image forming process, the toner used is a small spherical toner (for example, a toner having no specific irregular fine particles, abrasive, monodispersed spherical silica and a small organic compound added externally). Residual toner is reliably cleaned by the cleaning device 34 (or the belt cleaning device 53) almost without being affected by environmental conditions.
Such performance is supported by examples described later.
[0058]
Further, when a toner in which specific irregular fine particles, an abrasive, monodispersed spherical silica and a small-diameter organic compound are externally added to the toner particles is used as the toner used, the toner itself has a cleaning effect. Further, the cleaning performance by the cleaning blade is improved.
That is, indefinite or abrasive fine particles externally added to the toner particles are accumulated between the photosensitive drum 31 (or the intermediate transfer belt 230) and the tip of the cleaning blade 342 (531) so as to stay. Since it exists like a dam, the substantially spherical toner is blocked by the irregular shape or fine particles of the abrasive and does not advance further, and as a result, it is prevented from slipping out from the tip of the cleaning blade 342 (531). It is to be done.
In particular, the irregular or abrasive fine particles have a relatively large diameter as compared with fine particles having a relatively large diameter, such as a volume average particle diameter of the toner particles or slightly smaller than that of other external additives. There is also an advantage that it is difficult to scatter because of the fine particles. Since the minute organic compound is an ultrafine particle having a very minute particle size, the photosensitive drum 31 (or the intermediate transfer belt 230) and the cleaning blade slip through without being blocked by the irregular shape or the fine particles of the abrasive. 342 (531) is sent between the tip portion and functions as a lubricant.
[0059]
【Example】
Example 1
  The cleaning blade according to this example is a more specific model of the first embodiment, and is configured as follows.
  ・ Urethane rubber:
  A polyester polyol having a molecular weight of 2000 was obtained from 1,9-nonanediol / 2-methyl-1,8-octanediol (molar ratio 65/35) and adipic acid. The ester concentration in this polyester polyol is 6.8 mmol / g. This polyester polyol was reacted with a mixture of 1,3-propanediol and trimethylolethane as a chain extender to obtain the following physical properties.
  -Rebound resilience at 10 ° C = 22%
  ・ Rebound resilience at 40 ℃ = 60%
  ・ 300% modulus = 230kg / cm²
  ・ Tear strength = 84kg / cm
  ・Permanent elongation(JIS K6262) = 2.5%
  The pressing force between the cleaning blade and the photosensitive drum is set to 4 gf / mm.
  The comparative example has a rebound resilience coefficient of less than 20% at 10 ° C.Permanent elongationWas a cleaning blade with a 3.8%, 300% modulus of 280 kg / cm, and a tear strength of 73 kg / cm.
[0060]
FIG. 4 is an explanatory diagram showing the presence or absence of a toner slipping state of the cleaning blades according to Example 1 and Comparative Example for various toners having different shape factors.
In the figure, in the comparative example, as the SF (shape factor) value becomes smaller, the state of occurrence of defective cleaning becomes worse. In FIG. 4, “number of slipped-out” indicates the number of residual toner on the photosensitive drum that has passed through the cleaning blade and caused defective cleaning.
[0061]
Example 2
Next, a cleaning characteristic test was performed using the following image forming apparatus.
[Configuration of Image Forming Apparatus]
As the image forming apparatus, the image forming apparatus shown in FIG. 2 was used, and the respective conditions were as follows.

[0062]
[Cleaning characteristics test]
  The test uses a toner described in this specification prepared by a polymerization method, and has a shape factor of 130 to 135 and an average particle diameter of 6 μm. The two-component developer containing this toner is housed in the developing device in the image forming apparatus and used, and a test print by the image forming apparatus (an image with an area ratio of 5% per color is repeated 50 times with 5 run lengths). High-temperature and high-humidity (28 ° C, 85%)RH), Low temperature and low humidity (10 ° C, 15%RH) And medium temperature and medium humidity (22 ° C., 55%RHThe cleaning result of the cleaning device when the test was performed in each environment was performed by observing the print image and the photosensitive drum. At the same time, the presence or absence of an annoying noise generated when the photosensitive drum and the cleaning blade were rubbed at each speed was checked.
[0063]
Evaluation items include cleaning performance (streaky image quality defects due to poor cleaning: presence or absence of color streaks), blade damage (defects of the edge of the cleaning blade, turning of the blade itself), blade squeal when rotating the photosensitive drum The presence or absence and the amount of decrease in the film thickness of the surface layer of the photosensitive drum (including fluctuations in image quality due to changes in the film thickness of the surface layer) were investigated.
The quality of the results was evaluated according to the following criteria. The results are shown in FIGS.
A: When the symptom to be evaluated does not occur at the end of the 50 kpv test print and it is predicted that good results will be obtained thereafter.
○: When the symptom to be evaluated does not occur at the end of the 50 kpv test print, but it is determined that the life is almost at that point.
X: When the symptom to be evaluated occurred during the test print and the test print for 50 kpv could not be completed.
XX: When the symptoms of the evaluation item occur in the initial stage (test print stage of 10 kpv or less).
[0064]
[Blade hedding performance test]
After setting the cleaning blade to the photosensitive unit 30 shown in the first embodiment so as to obtain a specified pressing force, the photosensitive drum is attached, and the photosensitive unit 30 is left in a constant temperature and humidity chamber. The conditions of temperature, humidity, and standing time at this time were 45 ° C., 95% RH, and 72 hours. Thereafter, the photoconductor unit 30 was loaded into the image forming apparatus, short running of 1 kpv was performed, and evaluation was performed under each process speed and in each environment. The evaluation item was only the cleaning performance (streaky image quality defect due to poor cleaning: presence or absence of color streak).
[0065]
The quality of the results was evaluated according to the following criteria. The results are shown in FIGS.
A: When the symptom to be evaluated does not occur at the end of the 1 kpv test print, and it is predicted that good results will be obtained thereafter.
○: The symptom to be evaluated does not occur at the end of the 1 kpv test print, but it is determined that the life is almost at that point.
X: When the symptom to be evaluated occurred during the test print and the test print for 1 kpv could not be completed.
XX: When the symptoms of the evaluation item occur in the initial stage (test print stage of 100 pv or less).
Incidentally, the amount of sag in Comparative Example 1 and Example 1 (permanent deformation of the cleaning blade. That is, the photosensitive drum was deformed by a certain amount to generate a pressing force under high temperature and high humidity conditions. After holding for a long period of time, it does not return to its original state and permanent deformation occurs, but the value indicating how much the original state has been deformed is the amount of sag. While it was 3 mm, Example 1 was 0.2 mm.
[0066]
Example 3
In this example, when the tear strength measurement of the cleaning blade according to Embodiment 1 was performed for 60 lots, the result shown in FIG. 7 was obtained. The tear test used here was based on the JIS K6252 angle type.
According to the figure, each cleaning blade has a tear strength of 80 kg / cm or more, and it is confirmed that the requirement of 70 kg / cm or more required as a cleaning blade is sufficiently satisfied.
[0067]
Example 4
In this example, samples A to D with different materials of urethane rubber to be used were prepared, and their environmental dependence was examined. The results shown in FIGS. 8 and 9 were obtained.
First, each sample A to D will be described.
Sample A:
A polyester polyol having a molecular weight of 2000 was obtained from 1,9-nonanediol / 2-methyl-1,8-octanediol (molar ratio 65/35) and adipic acid. The ester concentration in the polyester polyol is 6.8 mmol / g.
Using this polyester polyol, MDI and a 1,3-propanediol / trimethylolethane mixed solution as a chain extender, a thermosetting urethane rubber was formed to produce a cleaning blade. The polyester polyol in the urethane rubber was about 65% by weight.
Sample B:
A cleaning blade was produced in the same manner as Sample A, except that a 2000-molecular weight polyester polyol (ester concentration: 11.3 mmol / g) composed of ethylene glycol and adipic acid was used. The polyester polyol in the urethane rubber was about 65% by weight.
Sample C:
Sample A was used except that a polyester diol having a number average molecular weight of 2000 (caprolactone A: ester concentration 8.5 mmol / g) obtained by adding ε-caprolactone to neopentyl glycol as an initiator was used. A cleaning blade was manufactured. The polyester polyol in the urethane rubber was about 65% by weight.
Sample D:
Cleaning was performed in the same manner as Sample A except that polyester diol (caprolactone B: ester concentration 7.6 mmol / g) obtained by adding ε-caprolactone to dodecanediol and adding ε-caprolactone thereto was used. A blade was manufactured. The polyester polyol in the urethane rubber was about 65% by weight.
[0068]
Experimental example 1:
About each sample AD, the impact resilience coefficient of 0 degreeC-50 degreeC was measured, and the temperature dependence was evaluated.
The results are shown in FIGS.
Here, the rebound resilience coefficient was obtained by a Lübke rebound resilience test apparatus based on JIS K6255.
From this result, the temperature dependence of the rebound resilience is significantly smaller in the sample A than in the samples B to D, the rebound resilience coefficient at 10 ° C. is 20% or more, and the rebound resilience coefficient at 40 ° C. is 70%. % Or less.
[0069]
Experimental example 2:
Using the cleaning blade of each sample A to D, the cleaning performance was evaluated under the conditions of LL (10 ° C. 15% RH), NN (23 ° C. 50% RH), HH (35 ° C. 85% RH), The edge wear state was observed. The cleaning performance was performed using a substantially spherical polymer toner having an average particle diameter of 6 μm.
The result is shown in FIG. Moreover, the data of each impact resilience were shown together.
The cleaning performance in FIG. 10 is indicated by ◯ when the cleaning was good and by × when the cleaning was not possible. As for the wear state of the edge, there was no problem with uniform wear without causing any trouble in the image, and non-uniform wear such as a defect that caused a defect in the image was indicated by a large wear amount and a large bite amount. In FIG. 10, Rb_T10Is the rebound resilience coefficient at 10 ° C, Rb_T40Means rebound resilience of 40 ° C.
From this result, it was found that the cleaning blade of Sample A exhibited stable cleaning performance against temperature changes, good cleaning performance at low temperatures, and good edge durability when used at high temperatures.
In addition, these samples exhibited a rebound resilience at 10 ° C. of 20% or more and a rebound resilience at 40 ° C. of 70% or less.
[0070]
On the other hand, Samples B to D having a high ester concentration had good edge wear, but the cleaning at low temperatures was poor. Samples B to D showed a value of 10 ° C. rebound resilience coefficient of less than 20%.
Further, it was found that cleaning at high temperature was difficult for sample C. Sample C had a large temperature dependency of the resilience, and the resilience at 40 ° C. exceeded 70%.
Furthermore, Sample D was a polyurethane using a polyester polyol having an ester concentration of less than 8 mmol / g, but good cleaning could not be performed. In this sample D, the temperature dependence of the rebound resilience was relatively small, and the rebound resilience coefficient at 40 ° C. was smaller than 70%, but the minimum rebound resilience coefficient was 20 ° C., which was higher than 0 ° C.
[0071]
As a result, the conventional toner having a relatively large particle size and a pulverized shape has good cleaning characteristics. Polyurethane rubber made from polyethylene adipate or polycaprolactone does not provide sufficient cleaning properties for toner with small particle size and high sphericity, and such small particle size and high sphericity. It has been found that the use of urethane rubber that satisfies the conditions of Sample A gives better properties to the toner.
[0072]
Example 5
In this example, it is experimentally confirmed that the ester concentration of the polyester polyol for producing the urethane rubber is 6.8 ± 0.2 mmol / g in order to keep the cleaning performance good. .
Here, FIG. 11 is an explanatory diagram of an equation for calculating the ester concentration, and FIG. 12 is an explanatory diagram illustrating an example of changes in the ester concentration with respect to the n value and the molecular weight.
In FIG. 11, the calculation method of ester concentration is ND / AA 1: 1 repetition 1 unit Fw = 270, and both terminals are H₂In consideration of O-free ND (Fw = 126), n satisfying the equation (4) in FIG. 11 was calculated, and the COO concentration at that time was calculated.
In FIG. 11, Mn is the molecular weight, Fw is the total number average molecular weight of adipic acid and 1,9-nonanediol, and in the formula (4), the numerical value “18” is H₂The molecular weight of O is shown.
In FIG. 12, the mmol value indicates the number of moles when 1 g of polyester polyol is weighed.
[0073]
  As shown in FIG. 12, when the molecular weight of the polyester polyol is 1300, that is, the ester concentration is less than 6.6 mmol / g, the molecular weight between the crosslinking points is shortened in the cleaning blade blending system according to the first embodiment. The impact resilience coefficient at 10 ° C. is less than 20%.
  On the other hand, when the molecular weight is 2844 and the ester concentration exceeds 7.0 mmol / g, the molecular weight between cross-linking points becomes long,Permanent elongationExceeds 2.5% and 300% modulus is 200kg / cm²It is confirmed that the desired desired physical properties cannot be obtained.
  By the way, the molecular weight is 3000TheIf it exceeds, the viscosity of the polyester polyol will rise rapidly, and a sheet for use in the blade will not be obtained.
[0074]
【The invention's effect】
As described above, according to the present invention, a preferable material of urethane rubber is selected as the cleaning blade, and the environment dependency is suppressed and the mechanical strength is optimized. The cleaning performance for the substantially spherical toner can always be kept good under high temperature and high humidity environmental conditions.
Further, according to the cleaning device, process cartridge, or image forming apparatus incorporating such a cleaning blade, even if a small spherical toner that is effective in realizing high image quality is used, the cleaning process or the image forming process is used. Since the cleaning performance can be kept good at all times, the reliability of each process can be compensated, and the performance of each apparatus can be kept very good accordingly.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing an outline of a cleaning blade according to the present invention, a cleaning device using the cleaning blade, a process cartridge, and an image forming apparatus.
FIG. 2 is an explanatory diagram showing an embodiment of an image forming apparatus to which the present invention is applied.
FIG. 3 is an explanatory diagram showing details of an image forming engine used in the present embodiment.
FIG. 4 is an explanatory diagram showing a performance test for toners having different shape factors in Example 1 and Comparative Examples 1 and 2;
5 is an explanatory diagram showing a resilience coefficient, permanent elongation, 300% modulus, tear strength, and pressing force of a cleaning blade in Example 2 and Comparative Examples 1 and 2. FIG.
6A is a cleaning defect under high temperature and high humidity conditions in Example 2 and Comparative Examples 1 and 2, blade damage, blade squealing (abnormal noise), image carrier wear, and poor cleaning after a sag test. Explanatory drawing which evaluated the presence or absence of (2), (b) is the same evaluation explanatory drawing in medium temperature and humidity conditions, (c) is the same evaluation explanatory drawing in low temperature low humidity conditions.
7 is a graph showing a tear test result of the cleaning blade used in Example 3. FIG.
8 is a graph showing the measurement results of the rebound resilience coefficient of 0 ° C. to 50 ° C. for each of samples A to D used in Example 4. FIG.
FIG. 9 is an explanatory diagram evaluating the temperature dependence.
10 shows the cleaning performance under each environmental condition for each of samples A to D used in Example 4, and shows the observation results of the edge wear state. FIG.
FIG. 11 is an explanatory diagram of a formula for calculating an ester concentration.
12 is an explanatory diagram showing the relationship of the ester concentration with respect to the n value and the molecular weight of the cleaning blade used in Example 5. FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Image carrier, 2 ... Cleaning blade, 3 ... Cleaning apparatus

Claims (8)

A cleaning blade that is disposed in contact with the image carrier and cleans residual toner on the image carrier,
Formed by the urethane rubber described below,
The impact resilience coefficient (JIS K6255) is within the range of 20% or more at 10 ° C and 70% or less at 40 ° C.
300% modulus (JIS K6251) is 200 kg / cm ² or more,
Tear strength (JIS K6252 angle type) is 70 kg / cm or more,
A cleaning blade characterized by satisfying the physical property conditions of
However, urethane rubber is a diol obtained by mixing diol component 1 (1,9-nonanediol) and diol component 2 (methyl-1,8 octanediol) in a molar ratio of (65 ± 3) :( 35 ± 3). A polyester polyol obtained by dehydration condensation of a dibasic acid and an ester concentration in the range of 6.6 to 7.0 mmol / g as a long-chain polyol,
A mixture of 1,3-propanediol and trimethylolethane in a ratio of 85 to 90:15 to 10% is used as a short-chain polyol. The cleaning blade according to claim 1, wherein
A cleaning blade having a permanent elongation (JIS K6262) of 2.5% or less. A cleaning device in which the cleaning blade according to claim 1 is incorporated. A process cartridge comprising at least an image carrier and a cleaning device having the cleaning blade according to claim 1 . In an image forming apparatus having one or a plurality of cleaning devices,
An image forming apparatus comprising the cleaning blade according to claim 1 or 2 incorporated in at least one of the cleaning apparatuses. In an image forming apparatus having one or a plurality of cleaning devices,
At least one of the cleaning device viewed write set a cleaning blade according to any of claims 1 or 2, and less than a shape factor of 140 by the cleaning blade, and a volume average particle size of 2~8μm An image forming apparatus having toner as a cleaning target . In an image forming apparatus comprising, as an image carrier, an image forming carrier that forms and carries a toner image, and an image carrier that directly or indirectly conveys the toner image on the image forming carrier ,
An image forming apparatus, wherein the cleaning blade provided in the image forming carrier incorporates the cleaning blade according to claim 1. In an image forming apparatus having a plurality of cleaning devices,
An image forming apparatus comprising the cleaning blade according to claim 1 or 2 incorporated in all of the plurality of cleaning apparatuses.

Images