JP2005164774A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To stably clean and to achieve a long life, high picture quality and a low running cost even under severe conditions for cleaning property because a small size toner with high sphericity is used. <P>SOLUTION: The photoreceptor drum 2 in the apparatus is subjected to a hardness test using a Vickers square-based pyramid diamond indenter in an environment at 25°C and 50% humidity and the drum shows 150 N/mm<SP>2</SP>to 220 N/mm<SP>2</SP>HU under 6 mN maximum load and shows 40% to 65% elastic deformation We. The toner used has 4.0 to 7.0 μm weight average particle diameter and 0.950 to 0.990 average circularity. The cleaning apparatus is composed of a blade 8a to clean over the photoreceptor drum 2, and a supporting member 8c to press the blade 8a to the photoreceptor drum 2. The free length L (mm), thickness t (mm) and the modulus of impact resilience R (%) of the blade 8a are in the relation of 0.2≤t/L≤0.6 and R≤125-1.6We. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus, and is particularly suitable for application to an image forming apparatus using an electrophotographic system having a function of cleaning residual toner remaining on the surface of a photosensitive drum.

  In general, in an image forming apparatus that records an image on a recording medium such as paper, such as a copying machine, a printer, and a facsimile, an electrophotographic system is employed as a system for recording the image on the recording medium.

  In an electrophotographic system, an image carrier having a photosensitive material coated on a surface is used as a photosensitive drum. First, after the surface of the photosensitive drum is uniformly charged, the surface of the photosensitive drum is irradiated with laser light, and a potential difference is given between the irradiated portion and the non-irradiated portion.

  Next, the charged toner contained in the developer adheres to the surface of the photosensitive drum, whereby a toner image is formed on the surface of the photosensitive drum. Thereafter, the toner image is transferred to a recording medium, and an image is formed on the recording medium.

  Recently, demands such as higher image quality and lower running cost of output devices have increased, and the photosensitive drum used in the electrophotographic system has a thinner photosensitive layer because of the necessity of high resolution. In addition, in order to reduce the running cost, it is necessary to increase the life of the photosensitive drum itself, so that the surface of the photosensitive member is improved in electrical, mechanical strength and wear resistance. .

  In such an electrophotographic system, since the surface of the photosensitive drum is repeatedly used for forming a toner image, after the toner image is transferred to the recording medium, it is not transferred to the recording medium. It is necessary to sufficiently remove residual toner remaining on the surface of the drum.

  Various methods for removing residual toner have been proposed. Of these proposals, a method of scraping off residual toner by bringing a counter blade (cleaning blade) made of an elastic material into contact with the surface of the photosensitive drum has been widely put into practical use. This method is low in cost, can make the entire electrophotographic system simple and compact, and has excellent toner removal efficiency.

  As a material for the cleaning blade, urethane rubber is generally used which has high hardness and high elasticity and is excellent in wear resistance, mechanical strength, oil resistance, ozone resistance and the like.

  The physical properties of the cleaning blade and the method of contacting the photosensitive drum greatly depend on the ease of cleaning due to the degree of adhesion of the transfer residual toner to the photosensitive drum and the surface property of the photosensitive drum. In addition, the cleaning performance is greatly affected by physical properties such as the toner shape, particle size, and material. Therefore, it is necessary to select a blade suitable for the cleaning property and set an appropriate angle and contact load with respect to the photosensitive drum. Therefore, in the actual selection and setting of the cleaning blade, the optimum condition is found by repeating trial and error.

  On the other hand, the cleaning performance and the degree of abrasion of the surface layer of the photosensitive drum differ depending on the actual operating environment, particularly temperature and humidity fluctuations. Therefore, cleaning with only the cleaning blade is difficult throughout the life of the photosensitive drum.

  Therefore, an apparatus provided with a cleaning auxiliary member has been proposed. For example, a configuration in which a magnetic developer is collected on a magnetic roller and the magnetic developer is rubbed on the photosensitive drum (see Patent Document 1, etc.), or a porous elastic roller is rubbed on the photosensitive drum (Patent Document) Etc.) have been proposed.

  Further, a colloidal silica-containing curable silicone resin is used for the surface layer of the photoreceptor, and a fur brush is brought into contact with the photoreceptor in which a structural unit having a charge transporting ability is incorporated in the siloxane resin (Patent Document 3, etc.) Etc.) have been proposed.

  In addition, it is indispensable to reduce the diameter of the toner in order to improve the image quality. For this reason, the tendency of toner diameter reduction has become remarkable. As the toner particle size is reduced, the specific surface area between the toner and the surface of the photosensitive drum is increased. As a result, the adhesion force of the toner per unit weight to the surface of the photosensitive drum is increased, so that the cleaning property of the surface of the photosensitive drum is deteriorated.

  As the particle size of the toner decreases, the fluidity of the toner deteriorates. Therefore, a larger amount of additive is required. Such a large amount of additive causes problems such as wear and chipping of the cleaning blade and local streak damage on the surface of the photosensitive drum.

  In recent years, a polymerized toner produced by a polymerization method is being adopted instead of a pulverized toner produced by a conventional pulverization method. This polymerized toner has an advantage that the transfer efficiency is higher than that of the pulverized toner, and a release agent is not required at the time of fixing the transferred image.

  Furthermore, the polymerized toner is characterized by a higher sphericity than the pulverized toner. When the sphericity of the toner is improved and the surface condition of the photosensitive drum and the contact pressure of the cleaning blade are the same as in the case of the pulverized toner, the use of the polymerized toner increases slipping from the cleaning blade. End up.

In general, in an image forming apparatus using polymerized toner, toner slipping is prevented by increasing the contact pressure of a cleaning blade. In this case, in order to reduce the load on the cleaning blade, as described above, a cleaning auxiliary member is added and configured to scrape off the toner in advance.
JP-A-2-91675 JP 60-107076 JP 2001-51576 A

  However, the conventional image forming apparatus described above has the following problems in recent years because of demands for higher image quality and lower running costs.

  That is, as represented by a toner having a small particle diameter or a polymerized toner, a toner having a high sphericity has been used in recent years. For this reason, the adhesion force with the photosensitive drum is increased, and the contact pressure of the cleaning blade needs to be increased.

  On the other hand, so-called highly durable photosensitive drums having high strength and high wear resistance have been used. If a photosensitive drum having extremely high wear resistance is used, the surface of the photosensitive drum is not cut and refreshing becomes difficult.

  Thus, when refreshing becomes difficult, electrical damage caused by charging, surface degradation due to adhesion of discharge products, and mechanical damage due to rubbing with a cleaning blade accumulate for a long time.

  As a result, the slipperiness of the surface of the photosensitive drum, particularly the slipperiness with respect to the cleaning blade, is deteriorated. As a result, chattering, squeaking, and squeezing of the cleaning blade are likely to occur. For this reason, there has been a conflicting situation in which it is difficult to increase the contact pressure of the cleaning blade.

  In particular, a contact charging method using a charging roller that generates less ozone or the like has been adopted from the corona charging method that generates ozone recently, and the contact charging method causes a large damage to the surface of the photosensitive drum. The above-mentioned cleaning blade is becoming more severe with chattering, squeaking, and drowning.

  Therefore, as shown in the above-described prior art, the use of the cleaning auxiliary member is an effective means from the viewpoint of reducing the load on the cleaning blade. However, the use of the cleaning auxiliary member has caused the following problems on the other hand.

  That is, in the configuration in which the magnetic developer is collected on the magnet roller and the magnetic toner is rubbed on the photosensitive drum, the rubbing force is insufficient because the magnetic toner is rubbed by the magnetic toner held by the magnetic force. is there.

  The color toner is a non-magnetic toner. For this reason, in the above-described configuration, the nonmagnetic toner as the transfer residue remaining on the surface of the photosensitive drum cannot be sufficiently removed, which makes it difficult to collect the nonmagnetic toner.

  In addition, there is a configuration having an advantage that the rubbing force is sufficiently exhibited by rubbing the porous elastic roller against the photosensitive drum.

  However, it has become necessary to remove the toner adhering to the roller itself by scraping off the surface of the photosensitive drum by other means. If the toner adhering to the roller itself is not scraped off, the rubbing is repeated between the photosensitive drum and the roller in a state where the toner is always adhering to the roller, resulting in fusion.

  On the other hand, if the toner adhering to the roller surface can be scraped off sufficiently and the transfer residual toner can be made small, the roller surface comes into direct contact with the surface of the photosensitive drum and is rubbed. May be hurt.

  Accordingly, an object of the present invention is to use a photosensitive drum having high durability, high strength and improved wear resistance without using a conventional cleaning auxiliary member, and thereby having a small diameter and high sphericity. Use of toner provides an image forming apparatus that can perform stable cleaning even under extremely severe cleaning conditions, and can achieve a long life, high image quality, and low running cost. There is to do.

  The above object is achieved by an image forming apparatus having the following configuration according to the present invention.

A. The carrier is charged by a charging means, and the charged image carrier is subjected to image exposure to form a latent image on the image carrier, and the latent image is developed by a developing means containing a developer, In the image formation in which the developed image is transferred and the image carrier after the transfer is cleaned by a cleaning means, the image carrier is subjected to a hardness test using a Vickers square pyramid diamond indenter in an environment of 25 ° C. and 50% humidity, An image carrier having a HU (Universal Hardness Value) of 150 N / mm ² or more and 220 N / mm ² or less when pressed with a maximum load of 6 mN, and an elastic deformation rate We of 40% or more and 65% or less, The toner has a weight average particle diameter of 4.0 to 7.0 μm and an average circularity of 0.950 to 0.990, and the cleaning means includes at least an elastic member for cleaning the image carrier and the elasticity. Image of a member When having a support member for pressing against the carrier, when the free length of the elastic member is L (mm), the thickness is t (mm), and the rebound resilience is R (%),
2 ≦ t / L ≦ 0.6, R ≦ 125-1.6We
An image forming apparatus characterized by satisfying the above.

  B. The thickness t of the cleaning elastic member is 1.0 ≦ t ≦ 5.0, preferably 1.8 ≦ t ≦ 3, and the free length L of the cleaning elastic member is 3 ≦ L ≦ 10, preferably 4 ≦ L ≦ 8, An image forming apparatus, wherein the cleaning elastic member has a rebound resilience R of 5 ≦ R ≦ 60, preferably 20 ≦ R ≦ 50.

  C. An image forming apparatus comprising: a contact charging unit configured to charge the image carrier in contact with the image carrier.

  D. A forming apparatus comprising: an elastic member for cleaning the image carrier; and a support member for pressing the elastic member against the image carrier as cleaning means for cleaning the image carrier.

  E. The contact pressure of the cleaning means to the image carrier is 12 N / m to 37 N / m (400 to 1200 grf), and the set angle θ of the cleaning elastic member to the image carrier is 15 degrees to 30 degrees. An image forming apparatus.

  F. A hole transporting compound having a surface layer of an image carrier having one or more chain polymerizable functional groups in the same molecule and / or an image carrier containing a polymerized and cured of the hole transporting compound is used. An image forming apparatus.

  G. An image forming apparatus using an image carrier utilizing a polymerization / curing reaction by at least heat, light, or electron beam as means for forming a surface layer.

  H. An image forming apparatus, wherein the toner has an aggregation degree of 5 to 40%.

  As described above, according to the present invention, a photosensitive drum exhibiting high hardness and high elasticity and a toner having a small particle size and low cohesion are used, and contact charging with an AC + DC bias is performed with a cleaning blade alone. By achieving this stable cleaning, it is possible to provide an image forming apparatus capable of obtaining a stable cleaning performance in an image forming apparatus having high image quality, high stability, and low running cost.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all the drawings of the following embodiments, the same or corresponding parts are denoted by the same reference numerals.

  First, an image forming apparatus and a cleaning apparatus according to an embodiment of the present invention will be described. FIG. 1 shows a cleaning apparatus according to this embodiment, and FIG. 2 shows an image forming apparatus according to this embodiment.

[overall structure]
As shown in FIG. 2, the image forming apparatus 1 according to this embodiment is an electrophotographic color copying machine. The image forming apparatus 1 is configured to form an image on a recording medium S such as a recording sheet based on an image signal supplied from a computer (not shown) or the like.

  In the image forming apparatus 1 according to this embodiment, a photosensitive material such as OPC is applied to the outer peripheral surface of a cylindrical substrate such as aluminum to constitute the photosensitive drum 2.

  The photosensitive drum 2 is first rotationally driven at a peripheral speed of 200 mm / s, and a dark portion potential VD of about −600 V is uniformly charged by the charging roller 3 as a contact charging means.

  Next, a laser beam 5 that is ON / OFF controlled according to image information is scanned and exposed to the photosensitive drum 2 by a laser oscillator 4. As a result, an electrostatic latent image of about −200 V is formed on the photosensitive drum 2 as the bright portion potential VL. The electrostatic latent image formed in this way is developed with toner as a developer by the rotary developing device 6 and visualized.

  Here, the rotary developing device 6 includes a first developing device 6y containing yellow toner as a first color toner and a second developing device 6m containing magenta toner as a second color toner. And a third developing device 6c containing cyan toner as a third color toner and a fourth developing device 6k containing black toner as a fourth color toner. ing.

  Of the electrostatic latent images formed by these developing devices, the first electrostatic latent image is developed by the first developing device 6y to be visualized. As a developing method, a jumping developing method, a two-component developing method, or the like is used. As a developing method, image exposure and reversal development are often used in combination. Here, in the first embodiment, a two-component development method using a nonmagnetic toner is used.

  The visualized first color toner image is electrostatically transferred to the surface of the intermediate transfer body 7 at the first transfer portion 7a facing the intermediate transfer body 7 as a second photosensitive drum that is rotationally driven. The primary transfer is performed.

  The intermediate transfer member 7 is formed of a conductive elastic layer and a surface layer having releasability. The intermediate transfer member 7 has a circumferential length slightly longer than the length of the maximum recording medium that can be conveyed.

  In addition, the intermediate transfer member 7 is pressed against the photosensitive drum 2 with a predetermined pressing force, and is opposite to the rotational direction of the photosensitive drum 2, that is, in the same direction at the contact portion. It is rotationally driven at approximately the same peripheral speed.

  In addition, a high voltage power source 7c applies a voltage having a polarity opposite to the toner charging polarity, that is, a so-called primary transfer bias, to the cylinder portion of the intermediate transfer member 7, whereby the toner image is primarily transferred onto the surface of the intermediate transfer member 7. Is done.

  Thereafter, the toner remaining on the surface of the photosensitive drum 2 after the primary transfer is removed by the cleaning device 8.

  Subsequently, the process is sequentially repeated for each color, and toner images of four colors are transferred onto the intermediate transfer body 7 and superimposed.

  A recording medium S such as recording paper is loaded on the cassette 9. Then, the recording medium S is separated and fed from the cassette 9 one by one by the pickup roller 10.

  The separated and fed recording medium S has its skew corrected by the registration roller pair 11, and then reaches the transfer portion 7b. Here, the transfer belt 12 in a state of being separated from the surface of the intermediate transfer member 7 is pressed against the surface of the intermediate transfer member 7 with a predetermined pressing force and is driven to rotate. The transfer belt 12 is stretched by a bias roller 12a and a tension roller 12b. In addition, a voltage (secondary transfer bias) having a polarity opposite to the charging polarity of the toner is applied to the bias roller 12a by a high voltage power source 12c.

  As a result, the toner image on the intermediate transfer body 7 is collectively transferred to the surface of the recording medium S conveyed at a predetermined timing toward the second transfer portion 7b, and secondary transfer is performed.

  Thereafter, the recording medium S is fed to a fixing device 14 as fixing means, and an image is fixed by heating and pressing. Subsequently, the recording medium S is discharged out of the apparatus by the discharge roller pair 15.

  On the other hand, the toner remaining on the surface of the intermediate transfer member 7 after the completion of the secondary transfer is removed by the intermediate transfer member cleaning device 13 that comes into contact with the surface of the intermediate transfer member 7 at a predetermined timing.

[Photosensitive drum]
Next, the photosensitive drum according to the embodiment of the present invention will be described below.

  The HU (universal hardness value) and elastic deformation rate in the present invention are the microhardness measuring device Fischerscope that continuously applies a load to the indenter and directly reads the indentation depth under the load to obtain the continuous hardness. Measurement was performed using H100V (Fischer). The indenter used was a Vickers square pyramid diamond indenter with a face angle of 136 °. The load conditions were measured stepwise up to a final load of 6 mN (273 points with a holding time of 0.1 s for each point).

  An outline of the output chart is shown in FIG. The vertical axis represents the load (mN) and the horizontal axis represents the indentation depth h (μm), which is the result of increasing the load stepwise and applying the load to 6 mN, and then decreasing the load stepwise similarly.

  HU (universal hardness value: hereinafter referred to as HU) is defined by the following formula (1) from the indentation depth under the same load when indented at 6 mN.

弾性変形率は圧子が膜に対して行った仕事量（エネルギー）、すなわち圧子の膜に対する荷重の増減によるエネルギーの変化より求めたものであり、下記式（２）からその値は求まる。全仕事量Ｗｔ（ｎＷ）は図３中のＡ−Ｂ−Ｄ−Ａで囲まれる面積で表され、弾性変形の仕事量Ｗｏ（ｎＷ）はＣ−Ｂ−Ｄ−Ｃで囲まれる面積で表される。

The elastic deformation rate is obtained from the work (energy) performed by the indenter on the membrane, that is, the change in energy due to the increase or decrease of the load of the indenter on the membrane, and the value is obtained from the following equation (2). The total work Wt (nW) is represented by the area surrounded by A-B-D-A in FIG. 3, and the work Wo (nW) of elastic deformation is represented by the area surrounded by C-B-D-C. Is done.

Elastic deformation rate We = Wo / Wt × 100 (%) (2)
As described above, the performance required for the organic electrophotographic photosensitive member includes improved durability against mechanical deterioration. In general, the hardness of the film is higher as the amount of deformation with respect to external stress is smaller, and it is considered that the electrophotographic photosensitive member having higher pencil hardness or Vickers hardness naturally improves durability against mechanical deterioration. However, the high hardness obtained by these measurements has not always been expected to improve durability.

As a result of intensive studies, we have found that when the values of HU and elastic deformation ratio are within a certain range, mechanical deterioration of the surface layer of the photoconductor hardly occurs. That is, a hardness test is performed using a Vickers square pyramid diamond indenter, the HU when pressed at a maximum load of 6 mN is 150 N / mm ² or more and 220 N / mm ² or less, and the elastic deformation rate is 40% or more and 65% or less. By using the electrophotographic photosensitive member, which is Also, the further improvement of properties and is more preferably HU value is 160 N / mm ² or more 200 N / mm ² or less.

For example, when the HU exceeds 220 N / mm ² and the elastic deformation rate is less than 40%, paper dust or toner sandwiched between the cleaning blade and the charging roller cannot be captured separately. However, since the elastic force of the photosensitive member is insufficient, if the elastic deformation rate is larger than 65%, the elastic deformation amount becomes small even if the elastic deformation rate is high. As a result, a large pressure acts locally. And deep scratches occur. Therefore, it is considered that the one with a high HU is not necessarily optimal as the photosensitive member.

Further, when the HU is less than 150 N / mm ² and the elastic deformation rate exceeds 65%, even if the elastic deformation rate is high, the amount of plastic deformation becomes large, and the paper dust or toner sandwiched between the cleaning blade and the charging roller Scraping may cause scraping or fine scratches.

  The photosensitive drum used in the present invention is composed of an electrophotographic photosensitive member containing a compound having at least a surface layer polymerized or crosslinked and cured. As the curing means, heat, light such as visible light or ultraviolet light, and radiation can be used.

  Therefore, in this first embodiment, as a method for forming the surface layer of the photoreceptor, a coating solution that is used for the surface layer and melts or contains a compound that can be cured by polymerization or crosslinking is used. A method in which the applied compound is cured by a curing means after being applied by a dip coating method, a spray coating method, a curtain coating method, a spin coating or the like is employed.

  Of these, the dip coating method is most preferable as a method for efficiently mass-producing photoreceptors, and the dip coating method can also be adopted in the first embodiment.

  Further, the configuration of the photosensitive drum according to this embodiment is a single-layer type having a layer configuration in which both the charge generation material and the charge transport material are contained in the same layer on a conductive substrate having an outer diameter of, for example, about 30 mm. The charge generation layer containing a charge generation material and the charge transport layer containing a charge transport material are either stacked or sequentially stacked in reverse order. Furthermore, a surface protective layer can be formed on the photosensitive layer.

  In the embodiment of the present invention, at least the surface layer of the photoreceptor only needs to contain a compound that can be polymerized or crosslinked and cured by heat, light such as visible light and ultraviolet light, and radiation. Preferably, from the viewpoints of characteristics as a photoreceptor, particularly electrical characteristics such as residual potential and durability, a function separation type photoreceptor structure in which a charge generation layer and a charge transport layer are sequentially laminated, or this function separation. It is preferable that a surface protective layer is further formed on the photosensitive layer laminated with the type photosensitive member structure.

  In this embodiment, as a method for curing a compound in polymerization or cross-linking in the surface layer, there is little deterioration of the photoreceptor characteristics, no increase in residual potential occurs, and sufficient hardness can be exhibited. Radiation is used.

  The radiation used in generating the polymerization or crosslinking is preferably an electron beam or gamma ray. When using an electron beam of these, it is possible to use all types such as a scanning type, an electron curtain type, a broad beam type, a pulse type, and a laminar type as an accelerator.

  In the case of irradiation with an electron beam, the acceleration voltage is preferably 250 kV or less, preferably 150 kV or less, as an irradiation condition in order to develop the electrical characteristics and durability performance of the photoreceptor according to the first embodiment. Is more preferable. The irradiation dose is preferably in the range of 10 kJ / kg to 1000 kJ / kg, and more preferably in the range of 15 kJ / kg to 500 kJ / kg.

  When the acceleration voltage is larger than the upper limit of the above range, damage due to electron beam irradiation on the characteristics of the photoreceptor, so-called damage tends to increase. Further, if the irradiation dose is less than the lower limit of the above range, curing is likely to be insufficient. In addition, when the dose is large, the photoreceptor characteristics are likely to be deteriorated. From this viewpoint, the dose is preferably selected from the above range.

  In addition, as a compound for a surface layer that can be cured by polymerization or crosslinking, it is unsaturated in the molecule from the viewpoint of high reactivity, high reaction rate, and high hardness achieved after curing. Those containing a polymerizable functional group are preferred.

  Furthermore, among the molecules having an unsaturated polymerizable functional group in the molecule, compounds having an acrylic group, a methacryl group and a styrene group are particularly preferable.

  Further, the compound having an unsaturated polymerizable functional group according to the first embodiment is roughly classified into a monomer and an oligomer depending on the repeating state of the structural unit. The monomer refers to a monomer having a relatively small molecular weight without repeating a structural unit having an unsaturated polymerizable functional group. On the other hand, an oligomer is a polymer having about 2 to 20 repeating units of a structural unit having an unsaturated polymerizable functional group. Also, a so-called macronomer in which an unsaturated polymerizable functional group is bonded only to the terminal of the polymer or oligomer can be used as the curable compound for the surface layer according to the first embodiment.

  In addition, it is more preferable that the compound having an unsaturated polymerizable functional group according to this embodiment adopts a charge transport compound in order to satisfy the charge transport function required for the surface layer. Among these charge transport compounds, an unsaturated polymerizable compound having a hole transport function is more preferable.

  Next, the photosensitive layer of the electrophotographic photoreceptor according to the embodiment of the present invention will be described.

  That is, the electrophotographic photosensitive member support may be any material as long as it has conductivity. Specifically, for example, a metal such as aluminum, copper, chromium, nickel, zinc, and stainless steel, or an alloy thereof may be used as a drum. Or formed into a sheet, laminated with a metal foil such as aluminum and copper on a plastic film, deposited with aluminum, indium oxide, tin oxide, etc. on a plastic film, or applied with a conductive material alone or with a binder resin By doing so, a metal provided with a conductive layer, or a plastic film or paper can be used.

  In the embodiment of the present invention, an undercoat layer having a barrier function and an adhesive function can be provided on the surface of the conductive support.

  The undercoat layer can be used to improve the adhesion of the photosensitive layer, improve coating properties, protect the support, cover defects on the support, improve charge injection from the support, or protect against electrical breakdown of the photosensitive layer. This is a layer formed for the purpose.

  Examples of the material for the undercoat layer include polyvinyl alcohol, poly-N-vinylimidazole, polyethylene oxide, ethyl cellulose, ethylene-acrylic acid copolymer, casein, polyamide, N-methoxymethylated 6 nylon, copolymer nylon, glue and Gelatin or the like can be used. These materials are dissolved in a suitable solvent and applied to the support surface. And the film thickness of this undercoat layer is 0.1-2 micrometers suitably.

  When the photoreceptor of the present invention is a function separation type photoreceptor, a charge generation layer and a charge transport layer are laminated. Examples of the charge generation material used in the charge generation layer include selenium-tellurium (Se-Te), pyripium, thiapyrylium dyes, or various central metals and crystal systems, such as α, β, γ, ε, And X-type crystalline phthalocyanine compounds, anthanthrone pigments, dibenzpyrenequinone pigments, pyranthrone pigments, trisazo pigments, disazo pigments, monoazo pigments, indigo pigments, quinacridone pigments, asymmetric quinocyanine pigments, quinocyanine and amorphous silicon, etc. Can be mentioned.

  In the case of the function separation type photoconductor, the charge generation layer includes a charge generation material in a 0.3 to 4 times amount of a binder resin and a solvent, a homogenizer, an ultrasonic dispersion, a ball mill, a vibration ball mill, a sand mill, an attritor, and the like. It is well dispersed by means such as a roll mill, and is formed by applying a dispersion and drying, or formed as a single composition film such as a vapor-deposited film of a charge generating material. Here, the curtain pressure of this electrification generation layer is typically 5 μm or less, and preferably 0.1 to 2 μm.

  Examples of the case where a binder resin is used are polymers and copolymers of vinyl compounds such as styrene, vinyl acetate, vinyl chloride, acrylic acid ester, methacrylic acid ester, vinylidene fluoride, trifluoroethylene, and polyvinyl alcohol. , Polyvinyl acetal, polycarbonate, polyester, polysulfone, polyphenylene oxide, polyurethane, cellulose resin, phenol resin, melanin resin, silicon resin, epoxy resin, and the like.

  The hole transporting compound having an unsaturated polymerizable functional group according to this embodiment can be used as a charge transport layer on the charge generation layer described above. Alternatively, after forming a charge transport layer composed of a charge transport layer and a binder resin on the charge generation layer, it can also be used as a surface protective layer.

  When a hole transporting compound is used as the surface protective layer, the charge transporting layer underneath is a suitable charge transporting material, for example, a heterocyclic ring such as poly-N-vinylcarbazole or polystilanthracene, or a condensed polycyclic aromatic. High molecular weight compounds, heterocyclic compounds such as pyrazoline, imidazole, oxador, triazole or carbazole, triarylamine derivatives such as triphenylamine, phenylresinamine derivatives, N-phenylcarbazole derivatives, stilbene derivatives, hydrazone derivatives, etc. The low molecular weight compound can be selected from the above-mentioned resin for charge generation layer and can be formed by applying a solution dispersed or dissolved in a solvent together with an appropriate binder resin by the above-mentioned known method and drying it. .

  In this case, the ratio of the charge transport material to the binder resin is preferably such that the weight of the charge transport material is in the range of 30 to 100, more preferably 50 to 100, assuming that the total weight of both is 100. It is preferable to select appropriately within the range.

  When the weight of the charge transport material in the charge transport layer is smaller than these ranges, the charge transport ability is lowered, and problems such as a decrease in sensitivity and an increase in residual potential occur. Also in this case, the thickness of the photosensitive layer is in the range of 5 to 30 μm. Further, the film thickness of the photosensitive layer at this time is the sum of the film thicknesses of the charge generation layer, the charge transport layer, and the surface protective layer.

  In any case, the surface layer is generally formed by applying a solution containing a hole transporting compound, followed by polymerization or curing reaction. It is also possible to form a surface layer using a material obtained by previously reacting a solution containing a hole transporting compound to obtain a cured product and then again dispersing or dissolving it in a solvent.

  Further, as a method for applying the above-mentioned solution, a dip coating method, a spray coating method, a curtain coating method, a spin coating, and the like are known. From the viewpoint of efficiency / productivity, the dip coating method is desirable as a method for applying the solution. It should be noted that other known film forming methods such as vapor deposition and plasma treatment can be appropriately selected.

  In the surface protective layer according to the embodiment of the present invention, conductive particles can be mixed. Examples of the conductive particles include metals, metal oxides, and carbon black.

  Specific examples of the metal as the conductive particles include aluminum, zinc, copper, chromium, nickel, stainless steel, and silver. Further, as the conductive particles, these metals may be used as plastic particles. Examples include those deposited on the surface.

  Further, the metal oxide as the conductive particles specifically includes zinc oxide, titanium oxide, tin oxide, antimony oxide, indium oxide, bismuth oxide, tin-doped indium oxide, antimony-doped tin oxide and antimony. Zirconium oxide doped with can be mentioned.

  These metal oxides can be used alone or in combination of two or more. In addition, when combining 2 or more types, it is also possible to just mix and it is also possible to give a solid solution or a melt | fusion.

  The average particle size of the conductive particles used in the embodiment of the present invention is preferably 0.3 μm or less, more preferably 0.1 μm or less from the viewpoint of the transparency of the protective layer. Is desirable. Furthermore, in the first embodiment, it is particularly preferable to use a metal oxide from the viewpoint of transparency or the like in the above-described conductive particle material.

The ratio of the conductive metal oxide particles in the surface protective layer is one of the factors that directly determines the resistance of the surface protective layer. Therefore, the specific resistance of the protective layer is desirably in the range of 10 ⁸ to 10 ¹³ Ωm (10 ¹⁰ to 10 ¹⁵ Ωcm).

  In this embodiment, the surface layer may contain fluorine atom-containing resin particles. Examples of the fluorine atom-containing resin particles include a tetrafluoroethylene resin, a trifluorinated ethylene resin, a hexafluoroethylene propylene resin, a vinyl fluoride resin, a vinylidene fluoride resin, a difluorodiethylene chloride resin, and these It is preferable to appropriately select at least one of the copolymers.

  And as said fluorine atom containing resin particle, a tetrafluoroethylene resin and a vinylidene fluoride resin are especially preferable. The molecular weight and particle size of the resin particles can be appropriately selected and are not necessarily limited to the molecular weight and particle size described above.

  The ratio of the fluorine atom-containing resin in the surface layer is typically 5 to 40% by weight, and preferably 10 to 30% by weight with respect to the total mass of the surface layer. This is because when the proportion of the fluorine atom-containing resin particles is more than 40% by weight, the mechanical strength of the surface layer tends to be lowered. This is because the wear and scratch resistance may be insufficient.

  In the embodiment of the present invention, an additive such as a radical scavenger and an antioxidant can be added to the surface layer in order to further improve dispersibility, binding properties and weather resistance. In the first embodiment, the thickness of the surface protective layer is preferably in the range of 0.2 to 10 μm, and more preferably in the range of 0.5 to 6 μm.

[Charging]
Next, a charging roller as a charging unit according to this embodiment will be described. That is, the charging roller 3 as a flexible contact charging member which is a charging means in this embodiment is formed by providing a middle resistance layer of rubber or foam on a cored bar.

  The intermediate resistance layer is formulated by a resin such as urethane, for example, conductive particles such as carbon black, a sulfurizing agent or a foaming agent, and is formed into a roller shape on a core metal, and then the surface is polished. .

  Here, it is important that the charging roller 3 as a contact charging member functions as an electrode. In other words, the resistance needs to be sufficiently low in order to secure sufficient contact with the member to be charged and to charge the moving member to be charged.

On the other hand, it is necessary to prevent voltage leakage when there is a low breakdown voltage defect portion such as a pinhole in the member to be charged. When an electrophotographic photosensitive member is used as the member to be charged, a resistance of about 10 ⁴ to 10 ⁷ Ω is desirable to obtain sufficient chargeability and leakage resistance. In the first embodiment, 10 ⁶ Ω The resistance is used.

  In addition, regarding the hardness of the charging roller 3, if it is too low, the shape is not stable and the contact property with the member to be charged is deteriorated. If it is too high, it is difficult to secure the charging nip portion a between the member to be charged. In addition, the micro-contact property with respect to the surface of the charged body is deteriorated. Accordingly, the hardness of the charging roller 3 is preferably in the range of 25 degrees to 60 degrees in Asker C hardness. In the first embodiment, for example, the hardness is 50 degrees.

  The material of the charging roller 3 is not limited to an elastic foam, but as an elastic material such as EPDM, urethane, NBR, silicone rubber, IR, etc., carbon black, metal oxide, etc. for resistance adjustment. Examples thereof include a rubber material in which a conductive material is dispersed, or a material obtained by foaming these materials. Note that the resistance can be adjusted using an ion conductive material without dispersing the conductive substance.

  The charging roller 3 is disposed in such a manner that a pressing force against elasticity is pressed against the photosensitive drum 2 as a member to be charged at 19.6 N (2 kgf). In the first embodiment, a charging unit having a width of several mm is formed.

  The resistance value of the charging roller 3 is measured as follows.

  That is, the photosensitive drum 2 of the printer is replaced with an aluminum drum. Thereafter, a voltage of 100 V is applied between the aluminum drum and the cored bar 8 h of the charging roller 3. Then, the resistance value of the charging roller 3 is obtained by measuring the current value flowing at this time.

The resistance value of the charging roller 3 according to this embodiment obtained in this manner was 5 × 10 ⁶ Ω. This resistance was measured in an environment where the temperature was 25 ° C. and the humidity was 60%.

  The charging roller 3 described above is driven to rotate as the photosensitive drum 2 rotates. The charging roller 3 is controlled by a constant current having a frequency of 2 kHz and a total current of 1800 μA from a charging high-voltage power source, and the photosensitive member potential is determined by a superimposed DC bias.

[Developer]
The developer used in the image forming apparatus according to this embodiment is a two-component developer that is a mixture of a nonmagnetic toner produced by a polymerization method or a pulverization method and a resin magnetic carrier.

The developer has a T / D ratio (weight Wt%) of 8%. In addition, as the resin magnetic carrier, the magnetization intensity in the magnetism of (4π) ⁻¹ × 106 A / m ( ¹ kOe) is 4π × 10 ⁻² Wb / m ² (100 emu / cm ³ ), and the number An average particle diameter of 40 μm and a specific resistance of 10 ¹¹ Ωm (10 ¹³ Ωcm) are used.

  The toner of the present invention preferably has an average circularity of 0.950 to 0.990 as measured by a flow type particle image analyzer in order to reduce toner fluidity deterioration due to durability.

  When the average circularity is less than 0.950, the toner approaches an indeterminate shape, so that the fluidity in durability is likely to deteriorate, and the transfer efficiency is also deteriorated. If the average circularity exceeds 0.990, the probability of occurrence of defective cleaning of the photoreceptor increases.

  In the present invention, the average circularity was measured with a flow type particle image analyzer FPIA-1000 manufactured by Toa Medical Electronics Co., Ltd.

The measurement is performed by removing fine dust through a filter, and as a result, in a water of 10 ⁻³ cm ³ , a nonionic type is used in water having a measurement range (for example, an equivalent circle diameter of 0.60 μm or more and less than 159.21 μm) of 20 or less Sample dispersion prepared by adding 5 mg of toner to 10 ml of an aqueous solution to which several drops of surfactant (Contaminone N manufactured by Wako Pure Chemical Industries, Ltd.) was added, and performing dispersion treatment with UH-50 manufactured by STM as an ultrasonic dispersing machine. Is used to measure the particle size distribution of particles having an equivalent circle diameter of 0.60 μm or more and less than 159.21 μm.

  The outline of the measurement is as follows.

  The sample dispersion liquid is passed through a flow path (expanded along the flow direction) of a flat and flat transparent flow cell (thickness: about 200 μm). The strobe and the CCD camera are mounted so as to be opposite to each other with respect to the flow cell so as to form an optical path that passes across the thickness of the flow cell. While the sample dispersion is flowing, strobe light is irradiated at 1/30 second intervals to obtain an image of the particles flowing through the flow cell, so that each particle is a two-dimensional having a certain range parallel to the flow cell. Taken as an image. From the area of the two-dimensional image of each particle, the diameter of a circle having the same area is calculated as the equivalent circle diameter.

  In about 1 minute, the equivalent circle diameter of 1200 or more particles can be measured, and the number based on the equivalent circle diameter distribution and the ratio (number%) of particles having a prescribed equivalent circle diameter can be measured.

  The average circularity is obtained by calculating the circularity of particles measured using the flow type particle image analyzer FPIA-1000 from the following equation, and dividing the total circularity of all particles measured by the total number of particles. Defined as average circularity.

Circularity = (perimeter of a circle having the same projected area as the particle image) / (perimeter of the projected image of the particle) (11)
The average circularity in the present invention is an index of the degree of unevenness of toner particles, and indicates 1.000 when the toner is a perfect sphere, and the average circularity becomes smaller as the toner shape becomes more complicated.

  The toner satisfying the circularity of the present invention preferably has a weight average particle diameter in the range of 4 to 7 μm.

  The weight average particle diameter of the toner was measured using Coulter Multisizer II (manufactured by Coulter). An interface for outputting number distribution and volume distribution (manufactured by Nikka) and a PC9801 personal computer (manufactured by NEC) are connected to Coulter Multisizer II, and a 1% NaCl aqueous solution is prepared using first-grade sodium chloride as the electrolyte. For example, ISOTON R-II (manufactured by Coulter Scientific Japan) can be used. As a measuring method, 0.1 to 5 ml of a surfactant, preferably alkylbenzene sulfonate, is added as a dispersant to 100 to 150 ml of the electrolytic aqueous solution, and 2 to 20 mg of a measurement sample is further added. The electrolyte in which the sample is suspended is dispersed for about 1 to 3 minutes with an ultrasonic disperser, and the volume and number of toners of 2 μm or more are measured using the Coulter Multisizer with a 100 μm aperture as the aperture. Distribution and number distribution were calculated. Then, the weight average particle diameter based on the weight based on the volume distribution according to the present invention (representing the representative value of each channel as the representative value for each channel) was obtained.

  The method for producing the toner of the present invention is not particularly limited, but in order to obtain an average circularity of 0.950 to 0.990, it is produced by a suspension polymerization method, a mechanical pulverization method, a spheronization treatment, or the like. The suspension polymerization method is particularly preferable.

  Further, the toner has a cohesion degree of 40 or less, preferably 5 to 30. This is because if the degree of aggregation is greater than 40, the toner scraped off by the cleaning blade in the cleaning nip causes aggregation in a high-temperature and high-humidity environment, and the risk of developing to fusion increases.

  On the other hand, if the degree of aggregation is smaller than 5, the fluidity is too high and the slipping through cleaning becomes severe.

  The toner aggregation degree was measured using a powder tester PT-D type manufactured by Hosokawa Micron which will be described below. A 100 mesh sieve, a 200 mesh sieve, and a 400 mesh sieve were set on a powder tester shaking table, and 5.0 g of toner was gently put on the 100 mesh sieve, and was vibrated for 15 seconds in an oscillating state with an amplitude of 0.5 mm and a frequency of 50 Hz. Note that the measurement is performed in an environment of 23 ° C./60% RH, and the toner used for the measurement is a toner sufficiently aged in this environment.

  Then, the weight of the toner on each sieve was measured, and the toner aggregation degree was calculated by the following formula.

Aggregation degree 1 = (toner weight on 60 mesh sieve / 2.0) × 100
Aggregation degree 2 = (toner weight on 100 mesh sieve / 2.0) × (3/5) × 100
Aggregation degree 3 = (weight of toner on 200 mesh sieve / 2.0) × (1/5) × 100
Aggregation degree = aggregation degree 1 + aggregation degree 2 + aggregation degree 3
Hereinafter, a method for producing toner by the suspension polymerization method used in the present invention will be described.

  First, a low softening point substance, a polar resin, a colorant, a charge control agent, a polymerization initiator, and other additives were added to the polymerizable monomer and dissolved or dispersed uniformly by a homogenizer, an ultrasonic disperser, or the like. The monomer system is dispersed in an aqueous phase containing a dispersion stabilizer by a usual stirrer, homogenizer, homomixer or the like. At this time, granulation is preferably performed while adjusting the stirring speed and time so that the monomer droplets have a desired developer particle size.

  Toner particle size distribution control and particle size control can be done by adjusting the pH of the system during granulation, changing the type and addition amount of a sparingly water-soluble inorganic salt and protective colloid, mechanical equipment conditions, For example, it can be achieved by controlling the stirring conditions such as the peripheral speed of the rotor, the number of passes, the shape of the stirring blade, the shape of the container or the solid content in the aqueous solution, and the like.

  Next, a method for producing toner by the pulverization method used in the present invention will be described.

  The pulverized toner used in the present invention is prepared by thoroughly mixing a binder resin, a release agent, a charge control agent, a colorant and the like with a mixer such as a Henschel mixer and a ball mill, and then heating rolls, kneaders, and extruders. The mixture is melt-kneaded using a heat kneader such as the above, the charge control agent and the colorant are dispersed or dissolved in the resins that are mutually compatible, cooled and solidified, and then mechanically pulverized to the desired particle size, Sharpen particle size distribution by classification. Alternatively, after cooling and solidification, a finely pulverized product obtained by colliding with a target under a jet stream is spheroidized by heat or mechanical impact force.

  Further, in the present invention, the following inorganic powder can be further added in order to improve developability, transferability, cleaning property and durability. Metal oxides such as magnesium, zinc, aluminum, titanium, cerium, cobalt, iron, zirconium, chromium, manganese, strontium, tin, antimony; complex metal oxides such as calcium titanate, magnesium titanate, strontium titanate; sulfuric acid Metal salts such as barium, calcium carbonate, magnesium carbonate, and aluminum carbonate; clay minerals such as kaolin; phosphate compounds such as apatite; silicon compounds such as silicon carbide and silicon nitride; and carbon powders such as carbon black and graphite.

  For the same purpose, the following organic particles and composite particles may be added. Resin particles such as polyamide resin particles, silicone resin particles, silicone rubber particles, urethane particles, melamine-formaldehyde particles, acrylic particles; rubbers, waxes, fatty acid compounds, resins, etc. and metals, metal oxides, salts, carbon black, etc. Composite particles composed of inorganic particles; Fluorine resins such as polyfluorinated ethylene and polyvinylidene fluoride; Fluorine compounds such as carbon fluoride; Fatty acid metal salts such as zinc stearate; Fatty acid derivatives such as fatty acids and fatty acid esters; Molybdenum sulfide And amino acids and amino acid derivatives.

[Cleaning device]
Next, this cleaning device will be described. FIG. 1 shows a cleaning device according to this embodiment.

  As shown in FIG. 1, the cleaning device 8 according to this embodiment includes a cleaning blade 8a as a cleaning member, a toner collecting sheet 8b, a blade support metal plate 8c, and the like.

  The cleaning blade 8a has a flat plate shape and a thickness of t (mm). The upper portion of the cleaning blade 8a is held by the blade support sheet metal 8c, and a free length L (mm) protrudes from the blade support sheet metal 8c. The cleaning blade 8 a is in contact with the photosensitive drum 2 at a point B on the photosensitive drum 2, and the extension line of the blade supporting sheet metal 8 c at the point where the extended line of the blade supporting sheet metal 8 a intersects the photosensitive drum 2. Is defined as a set angle θ of the cleaning elastic member with respect to the image carrier, and θ is preferably 15 ° to 40 °, and more preferably 20 ° to 30 °. This is because if the θ is less than 15 °, the toner easily slips through, and if it exceeds 40 °, the squealing or the reversal of the cleaning blade 8a is likely to occur.

  The cleaning blade 8a is in contact with the photosensitive drum 9 with a linear pressure of 12 N / m or more and 37 N / m or less. This is because toner slipping occurs when the linear pressure is less than 12 N / cm, and reversal of the cleaning blade 8 a occurs when the linear pressure exceeds 37 N / m. The cleaning blade 8a is an elastic blade mainly composed of urethane rubber, and its physical property values are based on the measuring method described in JIS-K6301.

[Relationship between photosensitive drum, toner and cleaning blade]
In the present invention, an electrophotographic photosensitive member having a universal hardness HU of 150 N / mm ² or more and 220 N / mm ² or less and an elastic deformation ratio of 40% or more and 65% or less for high image quality and high stability. On the other hand, the cleaning blade 8a is mainly composed of urethane rubber as described above and has rebound resilience as rubber, and the cleaning blade 8a having the rebound resilience has an edge portion with respect to the surface of the photosensitive drum 2. Is abutted in the counter direction to clean residual toner and the like. Further, in order to improve the reproducibility of the electrostatic latent image formed on the photosensitive drum 2, the weight average particle diameter is 4.0 to 7.0 μm, the average circularity is 0.950 to 0.990, and the aggregation degree is 5-40% toner is used.

  Usually, when trying to make full use of the drum as described above, especially when a charging roller that is charged by contact charging of AC + DC is used and the cleaning blade 8a is intended to achieve cleaning, the photosensitive drum 2 is hardly worn. Therefore, when the cleaning blade 8a is easily vibrated or reversed, and the toner having a small particle size, high circularity, and low cohesion is used as described above, the toner from the cleaning blade 8a is difficult to slip through.

  Therefore, paying attention to the fact that both the photosensitive drum 2 and the cleaning blade 8a have elastic characteristics, the relationship between them and the characteristics of the cleaning blade 8a as a rubber are not limited to the physical properties of the rubber, but the conditions for its use. As a result, it became possible to perform stable cleaning. Hereinafter, it demonstrates along an Example.

  The photosensitive drum 2 was prepared as follows. Prepare 30mm aluminum cylinder for hardness test and actual machine test. The coating material for the conductive layer was prepared by the following procedure. 50 parts of conductive titanium oxide powder coated with tin oxide containing 10% antimony oxide (parts by weight, the same applies hereinafter), 25 parts of phenol resin, 20 parts of methyl cellosolve, 5 parts of methanol and silicone oil (polydimethylsiloxane poly) An oxyalkylene copolymer (average molecular weight 3000) 0.002 part was dispersed for 2 hours in a sand mill using φ1 mm glass beads. This paint was applied onto the cylinder by a dip coating method and dried at 140 ° C. for 30 minutes to form a conductive layer having a thickness of 20 μm.

  Next, 5 parts of N-methoxymethylated nylon was dissolved in 95 parts of methanol to prepare an intermediate layer coating material. This paint was applied onto the conductive layer by a dip coating method and dried at 100 ° C. for 20 minutes to form a 0.6 μm intermediate layer.

  Next, 3 parts of oxytitanium phthalocyanine having a strong peak at 9.0, 14.2, 23.9, and 27.1 degrees in the black angle 2θ ± 0.2 degrees in CuKα X-ray diffraction , 3 parts of polyvinyl butyral (trade name ESREC BM2, manufactured by Sekisui Chemical Co., Ltd.) and 35 parts of cyclohexanone were dispersed for 2 hours in a sand mill using a φ1 mm glass bead, and then 60 parts of ethyl acetate was added. Thus, a charge generation layer coating material was prepared. This paint was applied onto the intermediate layer by a dip coating method and dried at 50 ° C. for 10 minutes to form a charge generation layer having a thickness of 0.2 μm.

  After forming the charge generation layer, 10 parts of a styryl compound of the following structural formula (4)

および下記構造式（５）の繰り返し単位を有するポリカーボネート樹脂１０部を

And 10 parts of a polycarbonate resin having a repeating unit of the following structural formula (5)

モノクロロベンゼン５０部およびジクロロメタン３０部の混合溶媒中に溶解し、電荷輸送層用塗布液を調整した。この塗布液を前記の電荷発生層上に浸漬コーティングし、１２０℃で一時間乾燥することによって膜厚が２０μｍの電荷輸送層を形成した。

It was dissolved in a mixed solvent of 50 parts of monochlorobenzene and 30 parts of dichloromethane to prepare a charge transport layer coating solution. This coating solution was dip-coated on the charge generation layer and dried at 120 ° C. for 1 hour to form a charge transport layer having a thickness of 20 μm.

次いで、構造式（３）の正孔輸送性化合物６０部をモノクロロベンゼン５０部およびジクロロメタン５０部の混合溶媒中に溶解し保護層用塗料を調整した。この保護層用塗料には、フッ素原子含有樹脂粒子として４フッ化エチレン樹脂を保護層の全重量に対して３０ｗｔ％含有させた。

Next, 60 parts of the hole transporting compound of the structural formula (3) was dissolved in a mixed solvent of 50 parts of monochlorobenzene and 50 parts of dichloromethane to prepare a protective layer coating material. This protective layer coating material contained 30 wt% of tetrafluoroethylene resin as fluorine atom-containing resin particles with respect to the total weight of the protective layer.

  This coating solution was coated on the charge transport layer and irradiated with an electron beam under the conditions of an acceleration voltage of 150 KV and an irradiation dose of 50 KGy in an atmosphere having an oxygen concentration of 10 ppm. Subsequently, a heat treatment was performed for 10 minutes under the same atmosphere at a temperature of 100 ° C. to form a protective layer having a thickness of 5 μm to obtain an electrophotographic photoreceptor.

After leaving the photoconductor for hardness test in an environment of 25 ° C. and 50% humidity for 24 hours, using the above-described microhardness measuring device Fischerscope H100V (manufactured by Fischer), HU and elastic deformation rate are obtained. HU (universal hardness value) was 190 N / mm ² and We (elastic deformation rate) was 45%.

  Next, the cleaning blade 8a has a cleaning means 2 having a thickness t of 2 mm, a free length L of 5 mm, a pressure applied to the photosensitive drum 2 of 20 N / m, and a set angle of 24 ° as shown in FIG. Using the image forming apparatus thus prepared, the image formation evaluation of 10,000 sheets of A4 size text charts was performed stably under high temperature and high humidity environment (30 ° C., 80%) and low temperature low humidity (15 ° C., 10%). The case where the cleaning performance was obtained was indicated by ○, and the case where a defect such as vibration of the cleaning blade, reversal or toner slipping occurred was indicated by ×.

  The toner used here will be described.

  The cleaning property was evaluated using a polymerized toner having a weight average particle diameter of 6.0 μm, an average circularity of 0.99, and an aggregation degree of 5. As described above, the polymerized toner having a high average circularity has a small aggregation degree and exhibits a characteristic of being easily removed.

  And when a weight average particle diameter becomes smaller than 4.0 micrometers, handling as a powder will become very difficult and slipping-through etc. will deteriorate. On the other hand, when the weight average particle diameter exceeds 7.0 μm, the toner is formed from the external additive and the fine powder component of the toner formed in the cleaning nip portion, and is supplied to the blocking layer ensuring the cleaning stability. Since the fine powder component decreases, cleaning may become unstable.

  If the average circularity is less than 0.950, the transfer efficiency (especially multiple transfer or secondary transfer) starts to decrease. On the other hand, if it exceeds 0.990, the toner rolls very well so that it passes through the cleaning. Becomes tough.

  FIG. 4A shows the result of evaluation under the above conditions by changing the rebound resilience R of the cleaning blade 8a and the elastic deformation rate We of the photosensitive drum 2 under the above conditions.

  From this result, there is a negative correlation between the elastic deformation rate of the photosensitive drum and the rebound resilience rate of the cleaning blade. When using a photosensitive drum having a large elastic deformation rate, it is better to lower the rebound resilience rate of the cleaning blade.

FIG. 4B is a graph of the data of FIG. 4-1, and the boundary of the portion where the elastic deformation rate We of the photosensitive drum 2 and the cleaning blade 8a rebound elastic modulus R have a negative correlation is approximated by a straight line.
R ≦ 125−1.6 × We
Get. Accordingly, it has been found that the rebound resilience R of the cleaning blade 8a is preferably 125−1.6 × We or less when the elastic deformation rate We of the photosensitive drum 2 is used.

  This is because the higher the elastic deformation rate We, the smaller the plastic deformation, the less the surface of the drum is worn, the less the surface layer is worn by the cleaning blade 8a, and the less so-called shaving powder is generated. Since the direct and micro contact area of the photosensitive drum 2 with 8a increases and friction increases, and the cleaning blade 8a easily vibrates, the rebound resilience R should be lowered as a characteristic that the cleaning blade 8a does not vibrate easily. It is considered good.

  Further, when the rebound resilience R was less than 5%, slip-through occurred regardless of the value of the elastic deformation rate We of the photosensitive drum 2. This is because when the cleaning blade 8a receives a load from the photosensitive drum or toner, the stress is caused by the load, and the blocking force of the blade in the cleaning nip is partially reduced. However, it is considered that the toner having a small, circular shape and high fluidity has slipped through, preferably 20% or more.

  If the rebound resilience R of the cleaning blade 8a exceeds 60, the resilience of the rubber itself is high, and if the elastic deformation rate We of the photosensitive drum is in a high range of 40 to 65, vibration or reversal of the blade occurs, which is inappropriate. More preferably, the rebound resilience R of the cleaning blade 8a is 50% or less.

  That is, the appropriate ranges of the rebound resilience R of the cleaning blade 8a and the elastic deformation rate We of the photosensitive drum 2 are within the range indicated by the oblique lines in FIG.

  Therefore, by optimizing the elastic deformation rate We of the photosensitive drum 2 and the rebound resilience rate R of the cleaning blade 8a as in this embodiment, the photosensitive drum 2 having high hardness and high elasticity can be obtained using an AC + DC bias. It was possible to stably perform cleaning with a single cleaning blade that was charged by contact with a charging roller.

  In the present embodiment, even within the preferable range in the first embodiment of the elastic deformation rate We of the photosensitive drum 2 and the rebound resilience rate R of the cleaning blade 8a, the blade is focused on the shape of the cleaning blade 8a having a high degree of freedom. The characteristics as a whole are examined so as to be favorable. Therefore, evaluation was performed using an image forming apparatus similar to that of Example 1 while changing the free length L and the thickness t of the cleaning blade 8a. As the toner, a cleaning property was evaluated using a pulverized toner having a weight average particle diameter of 6.0 μm, an average circularity of 0.96, and an aggregation degree of 10. Even in the case of the pulverized toner, when the average circularity is increased in this way, the degree of aggregation is as small as 10 and the characteristics are very easy to be removed.

  FIG. 5A shows the results of investigation under the above conditions.

  FIG. 51 shows the results obtained by changing the free length L and the thickness t, and there seems to be a correlation between them. FIG. 5-2 shows the result of rearranging the data using t / L as a parameter. From this result, it was shown that stable cleaning was achieved when t / L was between 0.2 and 0.6, but preferably 0.35 to 0.6.

  This t / L is the ratio of the free length L to the thickness t, and is considered to be a parameter indicating the rigidity of the cleaning blade 8a in contact with the counter as rubber with respect to the rotation direction of the photosensitive drum 2.

If t / L is smaller than 0.2, the rigidity of the cleaning blade 8a in the rotation direction of the photosensitive drum 2 is reduced,
This is because the cleaning blade 8a loses the load at the cleaning nip and vibrates or reverses. Conversely, if t / L is larger than 0.6, the rigidity is too high and the cleaning blade 8a vibrates or reverses. However, the torque was too high or the photosensitive drum 2 was locally damaged.

  Here, the thickness t and the free length L of the cleaning blade 8a satisfy the above-mentioned t / L, but the thickness t is preferably 1.0 mm to 5.0 mm, more preferably 1.8 mm to 3.0 mm. If it is good. If the thickness t is less than 1.0 mm, the rubber itself is too thin to withstand the load at the cleaning nip portion in the drum rotation direction as an absolute value, and the cleaning blade 8a is reversed. If it exceeds 5.0 mm, the rigidity is too high, and the cleaning blade 8a does not vibrate or invert, but the torque increases excessively or causes local damage.

  In addition, the free length L is preferably 3.0 mm to 10 mm, and more preferably 4.0 mm to 8.0 mm. When the free length L is less than 3.0 mm, when the vibration or deviation of friction or torque locally increases due to rubbing with the photosensitive drum 2, the variation in the free length L cannot be absorbed and the photosensitive drum 2 or This is because the vibration may be propagated to the cleaning container and the like to cause image unevenness. Conversely, when the free length L exceeds 10 mm, the displacement width of the blade edge with respect to the stress increases or permanent distortion occurs. Because it expands.

  As described above, the relationship between the elastic deformation rate We of the photosensitive drum and the rebound resilience rate R of the cleaning blade is the first example, and among these relationships, the shape (free length and thickness) of the cleaning blade is representative in the second example. Although the example has been described, the relationship between the elastic deformation rate We of the photosensitive drum and the rebound resilience rate R of the cleaning blade and the shape (free length and thickness) of the cleaning blade were satisfied within both ranges.

  Accordingly, by optimizing the shape of the cleaning blade as in this embodiment, the photosensitive drum 2 having high hardness and high elasticity is contact-charged by a charging roller using an AC + DC bias, and the cleaning blade alone is stable. Was able to be cleaned.

  In the description so far, the present invention has been described with respect to the image forming apparatus of contact charging, two-component non-magnetic toner, and intermediate transfer body. However, without being restricted by these image forming methods and apparatuses, the photosensitive member, toner The method other than cleaning is not particularly limited, and can be applied to various known methods, means, and apparatuses.

Schematic sectional view of a cleaning device for explaining the present invention 1 is a schematic cross-sectional view of an image forming apparatus that preferably implements the present invention. Schematic of output chart of Fischerscope H100V (manufactured by H. Fischer) 4-1 Data showing the result of Example 1 (Relationship between We and R) FIG. 4-2 A graph illustrating FIG. 4-1 and explaining the result of Example 1 5-1 Data showing the results of Example 2 (relationship between L and t) FIG. 5-2 Table in which FIG. 5-1 is rewritten at t / L

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Image carrier 8 Cleaning apparatus 8a Cleaning blade 8b Toner collection sheet 8c Blade support metal plate L Free length of blade t Blade thickness θ Blade setting angle

Claims (8)

The image carrier is charged by a charging unit, and the charged image carrier is subjected to image exposure to form a latent image on the image carrier, and the latent image is developed by a developing unit including a developer. In the image formation in which the developed image is transferred and the image carrier after the transfer is cleaned by a cleaning means,
The image carrier is subjected to a hardness test using a Vickers square pyramid diamond indenter under an environment of 25 ° C. and 50% humidity, and the HU (universal hardness value) when pressed at a maximum load of 6 mN is 150 N / mm ² or more and 220 N / mm. ^An image bearing member having an elastic deformation rate We of 40% or more and 65% or less.
The toner has a weight average particle diameter of 4.0 to 7.0 μm and an average circularity of 0.950 to 0.990, and the cleaning means includes an elastic member for cleaning the image carrier and an image of the elastic member. When having a support member for pressing against the carrier, when the free length of the elastic member is L (mm), the thickness is t (mm), and the rebound resilience is R (%),
0.2 ≦ t / L ≦ 0.6, R ≦ 125-1.6We
An image forming apparatus characterized by satisfying the above.   0.35 ≦ t / L ≦ 0.6, 1.0 ≦ t ≦ 5.0 (preferably 1.8 ≦ t ≦ 3), 3 ≦ L ≦ 10 (preferably 4 ≦ L ≦ 8), 5 ≦ 2. The image forming apparatus according to claim 1, wherein R ≦ 60 (preferably 20 ≦ R ≦ 50).   3. The image forming apparatus according to claim 1, wherein the charging unit that charges the image carrier includes a contact charging unit that charges the image carrier in contact with the image carrier. 4.   2. The cleaning means for cleaning the image carrier comprises only an elastic member for cleaning the image carrier and a support member for pressing the elastic member against the image carrier. 4. The image forming apparatus according to any one of items 3.   The contact pressure of the cleaning means to the image carrier is 12 N / m to 37 N / m, and the set angle θ of the cleaning elastic member to the image carrier is 15 degrees to 40 degrees. Item 5. The image forming apparatus according to any one of Items 1 to 4.   An image carrier comprising a hole transporting compound having a surface layer of the image carrier having one or more chain polymerizable functional groups in the same molecule and / or a product obtained by polymerizing and curing the hole transporting compound. The image forming apparatus according to claim 1, wherein the image forming apparatus is used.   8. The image formation according to claim 1, wherein an image carrier using a polymerization / curing reaction by heat, light, or an electron beam is used as the surface layer forming means. apparatus. The image forming apparatus according to claim 1, wherein the toner has an aggregation degree of 5 to 40%.

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