JP4831726B2 - Image forming method - Google Patents

Description

  The present invention relates to an image forming method using an electrophotographic system.

  2. Description of the Related Art In an image forming apparatus that forms an image on a recording medium such as paper such as a copying machine, a printer, and a facsimile, an electrophotographic system is widely adopted. The electrophotographic system irradiates the surface of the image carrier with laser light after the surface of the image carrier such as a photoconductor is uniformly charged, and the portion irradiated with the laser light and the portion not irradiated with the laser light. A potential difference is generated between them, and an electrostatic latent image is formed. Next, the charged toner adheres to the surface of the image carrier, whereby the electrostatic latent image on the surface of the image carrier is developed as a toner image. Thereafter, the toner image is transferred to a recording medium, and an image is formed on the recording medium.

  As a charging means for charging the surface of the image carrier, a corona discharge device or a contact charging device is used. The corona discharge device is effective for charging the surface of the image carrier to a predetermined potential, but has a problem that a high voltage power source is required and ozone is generated. On the other hand, the contact charging device charges the surface of the image carrier to a predetermined potential by bringing a conductive charging member to which a voltage is applied into contact with the surface of the image carrier, and does not require a high-voltage power source. Even if it sees generation | occurrence | production, it has the characteristics that a structure is simple compared with a corona discharge device, and is simple.

  Further, since the toner image is repeatedly formed on the surface of the image carrier, the residual toner remaining on the surface of the image carrier without being transferred to the recording medium after the transfer of the toner image to the recording medium is sufficiently removed. It is necessary. As a cleaning member in such an electrophotographic system, a cleaning blade which is a counter blade made of an elastic material is used. The cleaning blade is brought into contact with the surface of the image carrier to scrape off residual toner, which is low in cost, can make the entire electrophotographic system simple and compact, and has excellent toner removal efficiency. It has been put into practical use. As a material for the cleaning blade, urethane rubber having high hardness and high elasticity, and excellent in abrasion resistance, mechanical strength, oil resistance and ozone resistance is generally used.

  The physical properties of the cleaning blade and the manner of contact with the image carrier greatly depend on the ease of cleaning and the surface property of the image carrier depending on the degree of adhesion of the transfer residual toner to the image carrier. In addition, the cleaning properties are greatly affected by physical properties such as the shape, particle size and material of the toner. Therefore, it is necessary to select a blade suitable for the toner and set an appropriate angle and contact load with respect to the image carrier. is there.

  Recently, there has been a demand for an image forming apparatus with high image quality and low running cost. As the photoconductor, which is an image carrier used in the electrophotographic system, a photoconductor having a thinner photosensitive layer thickness is used for improving the image quality, and for reducing the running cost, the photoconductor itself is used. In view of the necessity of extending the service life, the electrical strength, mechanical strength and wear resistance of the surface of the photoreceptor are improved.

  However, an image forming apparatus using such an image carrier has the following problems.

  Since a high-durability and high-durability image carrier having high strength and high wear resistance has come to be used, an image with a very high wear resistance of 2 mg or less by the Taber Abrasion Tester, especially on the surface of the image carrier. When using a carrier, the surface of the image carrier is less likely to be refreshed, the electrical damage due to charging, the surface degradation of the image carrier due to the adhesion of discharge products, the machine due to rubbing with the cleaning blade Damage is likely to accumulate over time. The slipperiness (especially the slipperiness with respect to the cleaning blade) of the surface of the image carrier is lowered, and chattering, squealing, and wobbling of the cleaning blade are likely to occur. Furthermore, since the surface of the image carrier is hard to be scraped off, it is difficult to remove the discharge products, and there is a problem that image flow occurs. Therefore, various methods have been considered so far to solve this problem.

  For example, there is a technique in which the image carrier is heated by a heater to prevent the image carrier surface from being lowered due to moisture adsorption and to prevent image flow (see Patent Document 1). However, the provision of a heater also requires a heat control means, which not only complicates the configuration of the image forming apparatus, but particularly when the heater is used in the miniaturization and personalization of copying machines and printers, the system becomes complicated. turn into. In addition, it takes a certain time to raise the temperature of the heater, and the time (warm-up time) from when the power is turned on until printing is long, and power consumption for that is required. Further, when the image carrier is heated, the temperature is raised to near the glass transition temperature (Tg) of the toner, so that the toner may adhere to the surface of the image carrier.

  On the other hand, as another method, a method of removing discharge products by rubbing the surface of the image carrier with an elastic roller is considered (see Patent Document 2). In this method, the rubbing force is sufficiently exerted. However, if the transfer residual toner scraped off from the surface of the image carrier and adhered to the elastic roller itself is not scraped off from the elastic roller by other means, the elastic roller is always taken. As a result, rubbing is repeated between the image carrier and the elastic roller, causing fusion. On the other hand, even when the surface of the elastic roller is sufficiently scraped, if the amount of residual toner is small, the surface of the elastic roller directly contacts and rubs against the surface of the image carrier, and the surface of the image carrier is damaged. There was a case.

  As another method, there is a method in which a discharge product is positively removed by using a developer having an abrasive (see Patent Document 3). With this method, unlike the above-described rubbing with a heater or elastic roller, no new member is provided, so that the apparatus can be simplified and can be produced at low cost.

  However, when the contact charging device described above is used as the charging means, the abrasive that has passed through the cleaning blade may contaminate the contact charging device, causing uneven charging and image defects.

No. 1-334205 JP-A-61-100780 JP 61-278861 A

  An object of the present invention is to provide an image forming method that solves the above-described problems.

  More specifically, while using an image bearing member such as a highly durable (high strength, high wear resistance) photosensitive member, it maintains a stable cleaning performance for a long period of time and does not cause image flow, and has a long life and high life. An object of the present invention is to provide an image forming method with low image quality and low running cost.

  As a result of intensive studies, the present inventors can solve the above problems by adopting the following constitution, and an image carrier such as a highly durable (high strength, high wear resistance) photosensitive member. It has been found that an image forming method having a long life, high image quality and low running cost can be obtained without maintaining image quality while maintaining a stable cleaning performance for a long time while being used, and has completed the present invention.

That is, the present invention includes a charging step of charging the image carrier with a charging member, an electrostatic latent image forming step of forming an electrostatic image on the charged image carrier, and developing the electrostatic image with toner. A developing step for forming a toner image, a transfer step for transferring the toner image formed on the image carrier onto or without the intermediate transfer member, and heating the toner image on the recording medium. a fixing step of fixing, an image forming method having even a cleaning step small without having to clean the image bearing member surface after transfer by the cleaning member, said image bearing member, a temperature 25 ° C. 50% humidity in an environment The hardness test was performed using a Vickers square pyramid diamond indenter, the surface universal hardness value HU when pressed at a maximum load of 6 mN was 150 N / mm ² or more and 220 N / mm ² or less, and the elastic change An image carrier having a shape ratio We of 40% or more and 65% or less, wherein the charging member is a contact type charging roller provided in contact with the image carrier, and rotation of the contact type charging roller The shaft and the rotation axis of the image carrier are arranged so as to intersect with each other at an intersection angle θ (°), and the cleaning member is a cleaning blade provided so as to contact the image carrier, Abrasive particles are present at the contact portion between the cleaning blade and the image carrier, and the ratio between the residual toner and the abrasive particles reaching the cleaning blade is A (mass%), and the contact pressure of the cleaning blade Is B (g / cm), HU, We, A, B and θ are represented by the following formula (I)
(1/6000) × HU × We ≦ A × B (I)
And the following formula (II)
A / B ≦ θ (II)
And the following formula (III)
10 ≦ B ≦ 50 (III)
Satisfied ,
The abrasive particles are inorganic fine particles selected from the group consisting of strontium titanate, calcium titanate and barium titanate,
The abrasive particles are
i) The average particle size of the primary particles is 30 nm to 300 nm,
ii) having a cubic particle shape and / or a rectangular parallelepiped particle shape,
iii) having a perovskite crystal structure;
iv) The present invention relates to an image forming method characterized in that the content of particles and aggregates having a particle diameter of 600 nm or more is 1% by number or less . In the present invention, HU, We, A, B and θ used in the above formulas (I), (II) and (III) mean numerical values.

  According to the present invention, while using an image bearing member such as a highly durable (high strength, high wear resistance) photosensitive member, it can maintain a stable cleaning performance for a long period of time, and does not cause image flow, and has a long life and high life. An image forming method with high image quality and low running cost could be provided.

  An image forming apparatus using an image forming method according to the present invention will be described with reference to the drawings. FIG. 1 is an example of a schematic configuration diagram of an image forming apparatus used in the present invention.

[Configuration of Image Forming Apparatus]
An image forming apparatus 1 shown in FIG. 1 is an electrophotographic full-color image forming apparatus, and forms an image on a recording medium S in accordance with an image signal sent from a computer or the like (not shown). The image carrier 2 is a photoconductor.

  The image carrier 2 is charged to −600 V as a dark portion potential VD by a charging member 3 such as a contact charging roller while being driven to rotate at a peripheral speed of 200 mm / sec. Next, an electrostatic latent image forming means 4 such as a laser oscillator scans and exposes an exposure light 5 such as a laser beam which is ON / OFF controlled according to image information, so that a bright portion potential VL is formed on the image carrier 2. -200V electrostatic latent image is formed.

  The electrostatic latent image formed in this way is developed and visualized with toner as a developer by developing means 6 such as a rotary developing device. The developing means 6 includes a first developing device 6y containing yellow toner as a first color toner, a second developing device 6m containing magenta toner as a second color toner, and cyan as a third color toner. The third developing device 6c containing toner is integrated with the fourth developing device 6k containing black toner as the fourth color toner.

  First, the first electrostatic latent image is developed and visualized by the first developing device 6y containing yellow toner as the first color toner. As a developing method, any of the jumping developing method, the two-component developing method, and the FEED developing method may be used. Further, image exposure and reversal development are often used in combination. In this embodiment, a two-component development method using a non-magnetic toner is used.

  The visualized first color toner image is electrostatically transferred (primary transfer) to the surface of the intermediate transfer body 7 at the first transfer portion 7a facing the intermediate transfer body 7 that is rotationally driven. The intermediate transfer member 7 is formed of a conductive elastic layer and a surface layer having releasability, and has a circumferential length slightly longer than the length of the maximum transportable recording medium. The intermediate transfer member 7 is pressed against the image carrier 2 with a predetermined pressing force, and has a peripheral speed substantially equal to the peripheral speed of the image carrier 2. It is rotationally driven in the direction opposite to the rotation direction (that is, the same direction at the contact portion).

  The intermediate transfer body 7 is primarily transferred onto the surface of the intermediate transfer body 7 by applying a voltage (primary transfer bias) having a polarity opposite to the charging polarity of the toner to the cylinder portion by a high voltage power source 7c. The toner remaining on the surface of the image carrier 2 after the primary transfer is removed by a cleaning device 8 described later. Subsequently, the above process is repeated for each color, and four color toner images are transferred and superimposed on the intermediate transfer member 7.

  The recording medium S is loaded on the cassette 9 and is separated and fed one by one by the pickup roller 10. After the skew is corrected by the registration roller pair 11, the cassette 9 reaches the second transfer portion 7 b. Therefore, the transfer means 12 such as a transfer belt that is in a separated state with respect to 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 rotationally driven. The transfer unit 12 is stretched by a bias roller 12a and a tension roller 12b, and 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 member 7 is batch transferred (secondary transfer) onto the surface of the recording medium S conveyed to the second transfer portion 7b at a predetermined timing, and then sent to the fixing means 14 to be heated. After the image is fixed by applying pressure, the paper is discharged out of the apparatus by the discharge roller pair 15. The toner remaining on the surface of the intermediate transfer member 7 after the secondary transfer is completed 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.

[Image carrier]
A photoconductor that is an image carrier used in the present invention will be described below (hereinafter, the image carrier is also referred to as a photoconductor or a photosensitive drum).

The photoreceptor used in the image forming method of the present invention is subjected to a hardness test using a Vickers square pyramid diamond indenter in an environment of a temperature of 25 ° C. and a humidity of 50%, and the universal hardness value of the surface when pressed at a maximum load of 6 mN. HU is 150 N / mm ² or more and 220 N / mm ² or less, and the elastic deformation rate We is 40% or more and 65% or less. Further, it is preferred that the universal hardness value HU is 160 N / mm ² or more 200 N / mm ² or less. The elastic deformation rate We is preferably 50% or more and 65% or less.

  In addition, the universal hardness value HU and the elastic deformation rate We in the present invention are the microhardness measuring device Fischerscope in which the indenter is continuously loaded and the indentation depth under the load is directly read 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).

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

The elastic deformation rate We 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 can be obtained from the following equation (2). Here, Wt (nW) is the total work, and Wo (nW) is the work of elastic deformation.
Elastic deformation rate We (%) = Wo / Wt × 100 (2)

As described above, an improvement in durability against mechanical deterioration can be given as a performance required for the photoreceptor. 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. 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. As a result, mechanical deterioration of the photoconductor is less likely to occur.

  The amount of wear on the surface of the photoreceptor, which is an image carrier used in this embodiment, is 2 mg or less in the Taber abrasion tester, but if it is 6 mg or less, a sufficient effect on durability can be obtained. The test method for the Taber abrasion test is to mount the sample on the sample stand of the Taber abrasion tester (YSS Taber Yasuda Seisakusho) and attach the wrapping tape (Fuji Film product name: C2000) to the two surfaces. This is a method of applying a load of 500 gr to each rubber worn wheel (CS-0) and measuring the weight loss of the sample after 1000 revolutions with a precision balance.

The photoreceptor used in the present invention preferably has at least a support and a photosensitive layer on the support. The photosensitive layer may be a single-layer type photosensitive layer having a charge generation material and a charge transport material in the same layer, or a charge generation layer containing a charge generation material and a charge transport material containing a charge transport material. Any of the laminated type photosensitive layers having a structure in which the layers are laminated in this order or in the reverse order may be used. Among them, the photosensitive layer is preferably a laminated photosensitive layer from the viewpoint of characteristics as a photoreceptor, particularly electrical characteristics such as residual potential and durability. Furthermore, a surface protective layer can be formed on the photosensitive layer. In order that the universal hardness value HU of the photoreceptor surface is 150 N / mm ² or more and 220 N / mm ² or less and the elastic deformation rate We is 40% or more and 65% or less, the surface layer of the photoreceptor is cured. A layer formed by curing a functional compound by polymerization or crosslinking is preferred. As a method for forming the surface layer of the photoreceptor, first, a coating solution containing a curable compound that can be cured by polymerization or crosslinking is prepared. Next, the coating solution is applied by a coating method such as a dip coating method, a spray coating method, a curtain coating method, or a spin coating method. Among them, it is preferable to use a dip coating method as a coating method in order to efficiently mass-produce a photoreceptor. After coating the coating solution, the surface layer of the photoreceptor is cured by polymerizing or crosslinking the curable compound by a method using heat, light such as visible light or ultraviolet light, and radiation such as electron beam or gamma ray. Is formed. Among them, it is preferable to use radiation in that the residual potential does not increase without deterioration of the characteristics of the photosensitive member and sufficient hardness can be exhibited.

  In the case of irradiating an electron beam as radiation, any type of accelerator, such as a scanning type, an electron curtain type, a broad beam type, a pulse type, and a minor type can be used. In the case of irradiating an electron beam, the acceleration voltage is preferably 250 kV or less and optimally 150 kV or less, in order to develop the electrical characteristics and durability of the photoreceptor of the present invention. The irradiation dose is preferably in the range of 10 KGy to 1000 KGy, more preferably in the range of 30 KGy to 500 KGy. If the accelerating voltage exceeds the above, the electron beam irradiation damage tends to increase on the characteristics of the photoreceptor. In addition, it is necessary to be careful since curing is likely to be insufficient when the irradiation dose is less than the above range, and deterioration of the photoreceptor characteristics is likely to occur when the dose is large.

  The curable compounds that can be cured by polymerization or crosslinking include unsaturated polymerizable functional groups in the molecule from the viewpoint of high reactivity, high reaction rate, and high hardness achieved after curing. Those having a group are preferred, and among them, a compound having at least a functional group selected from the group consisting of an acryl group, a methacryl group and a styrene group is particularly preferred.

  The compound having an unsaturated polymerizable functional group in the present invention is roughly classified into a monomer and an oligomer based on repetition of the structural unit. The monomer means that the structural unit having an unsaturated polymerizable functional group is not repeated, and indicates a relatively small molecular weight, and the oligomer is a structural unit having an unsaturated polymerizable functional group having about 2 to 20 repeating units. It is a polymer. Also, a macromer having an unsaturated polymerizable functional group only at the terminal of the polymer or oligomer can be used as the curable compound used for forming the surface layer of the present invention.

  In addition, the compound having an unsaturated polymerizable functional group in the present invention is more preferably a compound having an unsaturated polymerizable functional group is a charge transport compound in order to satisfy the charge transport function necessary for the surface layer. Among these, an unsaturated polymerizable compound having a hole transport function is more preferable.

  Below, the preferable compound example of the compound which has an unsaturated polymerizable functional group is given.

  The support for the photoreceptor is only required to have conductivity, for example, a metal or alloy such as aluminum, copper, chromium, nickel, zinc and stainless steel formed in a drum or sheet, or a metal such as aluminum or copper. Foil laminated on plastic film, aluminum, indium oxide, tin oxide, etc. deposited on plastic film, metal with conductive layer applied alone or with binder resin, or plastic film and paper Etc.

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

  The undercoat layer is used for improving the adhesion of the photosensitive layer, improving the coatability, protecting the support, covering defects on the support, improving the charge injection from the support, and protecting the photosensitive layer from electrical breakdown. Formed for. Materials 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, gelatin, etc. Can be used. These are dissolved in a solvent suitable for each and coated on a support. The film thickness at that time is preferably 0.1 to 2 μm.

  Examples of the charge generation material used in the charge generation layer include selenium-tellurium, pyripium, thiapyrylium dyes, various central metals and crystal systems, specifically crystal types such as α, β, γ, ε, and X types. Phthalocyanine compounds having an anthrone, anthanthrone pigment, dibenzpyrenequinone pigment, pyranthrone pigment, trisazo pigment, disazo pigment, monoazo pigment, indigo pigment, quinacridone pigment, asymmetric quinocyanine pigment, quinocyanine, and JP-A No. 54-143645 Amorphous silicon and the like.

  In the case of a photoreceptor having a laminated photosensitive layer, the charge generation layer comprises a homogenizer, an ultrasonic dispersion, a ball mill, a vibration ball mill, a sand mill, an attritor, and the charge generation material together with 0.3 to 4 times the amount of binder resin and solvent. The film 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 deposition film of the charge generation material. The film thickness is desirably 5 μm or less, and particularly preferably within a range of 0.1 to 2 μm.

  As the binder resin, polymers and copolymers of vinyl compounds such as styrene, vinyl acetate, vinyl chloride, acrylic acid ester, methacrylic acid ester, vinylidene fluoride, trifluoroethylene, polyvinyl alcohol, polyvinyl acetal, polycarbonate, Examples include polyester, polysulfone, polyphenylene oxide, polyurethane, cellulose resin, phenol resin, melamine resin, silicon resin, and epoxy resin.

  The hole transporting compound having an unsaturated polymerizable functional group in the present invention is a charge transport layer comprising a charge transport layer and a charge transport material on the charge generation layer or as a charge transport layer. After forming, it can also be used as a surface layer.

  When the photoreceptor has a surface layer, the charge transport layer underneath is a suitable charge transport material, for example, a polymer compound having a heterocyclic ring or condensed polycyclic aromatic such as poly-N-vinylcarbazole or polystyrylanthracene, Suitable heterocyclic compounds such as pyrazoline, imidazole, oxazole, triazole, carbazole, low molecular weight compounds such as triarylamine derivatives such as triphenylamine, phenylresinamine derivatives, N-phenylcarbazole derivatives, stilbene derivatives, hydrazone derivatives, etc. A solution dispersed / dissolved in a solvent together with a binder resin (which can be selected from the aforementioned resin for charge generation layer) can be applied and dried by the above-mentioned known methods. In this case, the ratio of the charge transport material to the binder resin is suitably selected in the range of 30 to 100, more preferably 50 to 100, when the total mass of both is 100. If the amount of the charge transport material is less than that, 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, and 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 layer.

  The surface layer can be formed by the method described above.

  Further, the surface layer may have conductive particles. Examples of the conductive particles include metals, metal oxides, and carbon black. Examples of the metal include aluminum, zinc, copper, chromium, nickel, stainless steel, silver, and the like, and those obtained by depositing these metals on the surface of plastic particles. Examples of the metal oxide include zinc oxide, titanium oxide, tin oxide, antimony oxide, indium oxide, bismuth oxide, tin-doped indium oxide, antimony-doped tin oxide, and antimony-doped zirconium oxide. These can be used alone or in combination of two or more. When two or more kinds are combined, they may be simply mixed or formed into a solid solution or a fused form.

  The average particle size of the conductive particles used in the present invention is preferably 0.3 μm or less, more preferably 0.1 μm or less, from the viewpoint of transparency of the protective layer.

  In the present invention, among the conductive particles as described above, it is particularly preferable to use a metal oxide in terms of transparency.

The ratio of the conductive metal oxide particles in the surface layer is one of the factors that directly determine the resistance of the surface layer, and the resistance of the surface layer is in the range of 10 ¹⁰ to 10 ¹⁵ Ω · cm. Is preferred.

  The surface layer in the present invention can contain fluorine atom-containing resin particles.

  Fluorine atom-containing resin particles include tetrafluoroethylene resin, trifluorinated ethylene resin, hexafluoroethylene propylene resin, vinyl fluoride resin, vinylidene fluoride resin, difluorodiethylene chloride resin, and their co-polymers. It is preferable to select one or two or more from the coalesced, but particularly preferred are tetrafluoroethylene resin and vinylidene fluoride resin. The molecular weight and particle size of the resin particles can be appropriately selected and are not particularly limited.

  The proportion of the fluorine atom-containing resin in the surface layer is preferably 5 to 70% by mass, more preferably 10 to 60% by mass with respect to the total mass of the surface layer. When the proportion of fluorine atom-containing resin particles is more than 70% by mass, the mechanical strength of the surface layer tends to be lowered, and the surface layer releasability of the surface layer in which the proportion of fluorine atom-containing resin particles is less than 5% by mass, Wear resistance and scratch resistance may not be sufficient.

  In the present invention, additives such as a radical scavenger and an antioxidant may be added to the surface layer for the purpose of further improving dispersibility, binding properties and weather resistance.

  The film thickness of the surface layer used in the present invention is preferably in the range of 0.2 to 10.0 μm, more preferably in the range of 0.5 to 6.0 μm.

[Developer]
The developer used in the present invention may be a one-component developer having only toner or a two-component developer having toner and carrier. In the present invention, the toner is a toner having at least toner particles and inorganic fine particles. As the colorant used for the toner particles, any of the dyes and pigments used in conventionally known toners can be used. The method for producing the toner particles of the present invention is not particularly limited, and a suspension polymerization method, an emulsion polymerization method, an association polymerization method, and a kneading pulverization method are used.

  Hereinafter, a method for producing toner particles by suspension polymerization will be described. A colorant, a low softening point material such as wax, a polar resin, a charge control agent, and a polymerization initiator are added to the polymerizable monomer, and if necessary, the solution is uniformly dissolved or dispersed by a homogenizer or an ultrasonic disperser. The monomer composition is dispersed in an aqueous phase containing a dispersion stabilizer by a stirrer, a homogenizer or a homomixer. At this time, granulation is preferably performed by adjusting the stirring speed and time so that the droplets of the monomer composition have a desired toner particle size. Thereafter, stirring may be carried out to such an extent that the particle state of the monomer composition is maintained by the action of the dispersion stabilizer and precipitation of the particles of the monomer composition is prevented. The polymerization temperature is preferably set to 40 ° C. or higher, generally 50 to 90 ° C. The temperature may be raised in the second half of the polymerization reaction, and in order to remove unreacted polymerizable monomers and by-products that cause odor during toner fixing, some water may be added in the second half of the reaction or at the end of the reaction. Alternatively, a part of the aqueous medium may be distilled off. After completion of the reaction, the produced toner particles are recovered by washing and filtration and dried. In the suspension polymerization method, it is usually preferable to use 300 to 3,000 parts by weight of water as a dispersion medium with respect to 100 parts by weight of the monomer composition.

  Toner particle size distribution control and particle size control include pH adjustment of aqueous media during granulation, methods of changing the type and addition amount of poorly water-soluble inorganic salts and dispersants that act as protective colloids, mechanical devices This can be achieved by controlling the peripheral speed of the rotor, the number of passes, the shape of the stirring blade, the stirring conditions, the container shape, or the solid content concentration in the aqueous solution.

  Examples of the polymerizable monomer used for suspension polymerization include styrene; styrene derivatives such as o- (m-, p-) methylstyrene and m- (p-) ethylstyrene; methyl (meth) acrylate, (meta ) Propyl acrylate, butyl (meth) acrylate, octyl (meth) acrylate, dodecyl (meth) acrylate, stearyl (meth) acrylate, behenyl (meth) acrylate, (meth) acrylate-2-ethylhexyl, Examples include (meth) acrylic acid ester monomers such as dimethylaminoethyl (meth) acrylate and diethylaminoethyl (meth) acrylate; butadiene, isoprene, cyclohexene, (meth) acrylonitrile, and acrylamide.

  As the polar resin added during polymerization, a copolymer of styrene and (meth) acrylic acid, a maleic acid copolymer, a polyester resin, and an epoxy resin are preferably used.

  Examples of the low softening point material used in the present invention include paraffin wax, polyolefin wax, Fischer-Tropsch wax, amide wax, higher fatty acid, ester wax and derivatives thereof, or graft / block compounds thereof.

  As the charge control agent used in the present invention, a known charge control agent can be used, but a charge control agent having no polymerization inhibitory property and no soluble component in an aqueous medium is particularly preferable. Specific examples of the negative compound include salicylic acid, naphthoic acid, dicarboxylic acid, metal compounds of derivatives thereof, polymer compounds having sulfonic acid in the side chain, boron compounds, urea compounds, silicon compounds, calixarene. . Examples of the positive system include a quaternary ammonium salt, a polymer compound having the quaternary ammonium salt in the side chain, a guanidine compound, and an imidazole compound. The amount of the charge control agent used is preferably 0.2 to 10 parts by mass with respect to 100 parts by mass of the polymerizable monomer.

  Examples of the polymerization initiator used in the present invention include 2,2′-azobis- (2,4-dimethylvaleronitrile), 2,2′-azobisisobutyronitrile, 1,1′-azobis (cyclohexane-1- Carbonitrile), 2,2′-azobis-4-methoxy-2,4-dimethylvaleronitrile, azo polymerization initiators such as azobisisobutylnitrile, benzoyl peroxide, methyl ethyl ketone peroxide, diisopropyl peroxycarbonate, cumene hydroxy peroxide, 2 Peroxide polymerization initiators such as 1,4-dichlorobenzoyl peroxide and lauroyl peroxide are used. The addition amount of the polymerization initiator varies depending on the desired degree of polymerization, but is generally used at a ratio of 0.5 to 20% by mass (based on the polymerizable monomer) with respect to the polymerizable monomer. . The kind of the polymerization initiator is slightly different depending on the polymerization method, but may be used alone or mixed with reference to the 10-hour half-life temperature.

  As a dispersant for suspension polymerization, inorganic oxides such as calcium phosphate, magnesium phosphate, aluminum phosphate, zinc phosphate, calcium carbonate, magnesium carbonate, calcium hydroxide, magnesium hydroxide, aluminum hydroxide, calcium metasilicate , Calcium sulfate, barium sulfate, bentonite, silica, alumina, magnetic substance, and ferrite. Examples of the organic compound include polyvinyl alcohol, gelatin, methyl cellulose, methyl hydroxypropyl cellulose, ethyl cellulose, sodium salt of carboxymethyl cellulose, and starch. These dispersants are preferably used in a proportion of 0.2 to 2.0 parts by mass with respect to 100 parts by mass of the polymerizable monomer.

  A commercially available dispersant may be used as it is, but in order to obtain dispersed particles having a fine uniform particle size, it can also be obtained by producing an inorganic compound in a dispersion medium under high-speed stirring. For example, in the case of calcium phosphate, a dispersant preferable for the suspension polymerization method can be obtained by mixing an aqueous sodium phosphate solution and an aqueous calcium chloride solution under high-speed stirring.

  In order to refine these dispersants, 0.001 to 0.1 parts by mass of a surfactant may be used in combination with 100 parts by mass of the suspension. Specifically, commercially available nonionic, anionic and cationic surfactants can be used. Examples include sodium dodecyl sulfate, sodium tetradecyl sulfate, sodium pentadecyl sulfate, sodium octyl sulfate, sodium oleate, sodium laurate, potassium stearate, and calcium oleate.

  Next, a method for producing toner particles by a kneading and pulverizing method will be described. Examples of the binder resin used in the kneading and grinding method include polystyrene, poly-α-methylstyrene, styrene-propylene copolymer, styrene-butadiene copolymer, styrene-vinyl chloride copolymer, and styrene-vinyl acetate copolymer. Examples of the polymer include styrene-acrylic acid ester copolymer, styrene-methacrylic acid ester copolymer, vinyl chloride resin, polyester resin, epoxy resin, phenol resin, and polyurethane resin. These are used alone or in combination. Of these, styrene-acrylic acid ester copolymer resins, styrene-methacrylic acid ester copolymer resins, and polyester resins are preferable.

  When toner particles are controlled to be positively charged, a modified product of a fatty acid metal salt; a quaternary ammonium salt such as tributylbenzidylammonium-1-hydroxy-4-naphthosulfonate or tetrabutylammonium tetrafluoroborate; tributylbenzyl Phosphonium salts such as phosphonium-1-hydroxy-4-naphthosulfonate and tetrabutylphosphonium tetrafluoroborate; amine and polyamine compounds; metal salts of higher fatty acids; acetylacetone metal complexes; dibutyltin oxide, dioctyltin oxide, dicyclohexyltin oxide Diorganotin oxides such as dibutyltin borate, dioctyltin borate, dicyclohexyltin borate are added to the toner particles. When the toner particles are controlled to be negatively charged, organometallic complexes and chelate compounds are effective, and monoazo metal complexes, acetylacetone metal complexes, aromatic hydroxycarboxylic acids, and aromatic dicarboxylic acid metal complexes can be used. The amount of these charge control agents used is 0.1 to 15 parts by mass, preferably 0.1 to 10 parts by mass, with respect to 100 parts by mass of the binder resin.

  A low softening point substance can be added to the toner particles as necessary. Low softening point substances include aliphatic hydrocarbon waxes such as low molecular weight polyethylene, low molecular weight polypropylene, paraffin wax, and Fischer-Tropsch wax or their oxides; aliphatic esters such as carnauba wax and montanate wax. And wax obtained by deoxidizing a part or all of the wax. In addition, saturated linear fatty acids such as palmitic acid, stearic acid, and montanic acid; unsaturated fatty acids such as brassic acid, eleostearic acid, and parinalic acid; stearyl alcohol, aralkyl alcohol, behenyl alcohol, carnauvyl alcohol, and seryl alcohol Saturated alcohols such as melisyl alcohol; polyhydric alcohols such as sorbitol; fatty acid amides such as linoleic acid amide; saturated fatty acid bisamides such as methylenebisstearic acid amide; unsaturated fatty acid amides such as ethylene bisoleic acid amide Aromatic bisamides such as N, N'-distearylisophthalic acid amide; fatty acid metal salts such as zinc stearate; waxes grafted to aliphatic hydrocarbon waxes using vinyl monomers such as styrene; Such fatty acids and partial esters of polyhydric alcohols behenic acid monoglyceride; and methyl ester having a hydroxyl group obtained by hydrogenation of vegetable fats and oils. The addition amount of the low softening point substance is 0.1 to 20 parts by mass, preferably 0.5 to 10 parts by mass with respect to 100 parts by mass of the binder resin.

  Next, the binder resin, release agent, charge control agent, colorant, etc. are mixed thoroughly by a mixer such as a Henschel mixer or ball mill, and then melted using a heat kneader such as a heating roll, kneader, or extruder. After kneading and mixing the resins together, the charge control agent and colorant are dispersed or dissolved, cooled and solidified, then mechanically pulverized to the desired particle size, and further classified by particle size distribution. To sharpen. 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, in order to improve developability and durability, the following inorganic fine particles can be added to the toner. For example, oxides of metals such as silicon, magnesium, zinc, aluminum, titanium, cerium, cobalt, iron, zirconium, chromium, manganese, tin, antimony; metal salts such as barium sulfate, calcium carbonate, magnesium carbonate, aluminum carbonate; Examples thereof include clay minerals such as kaolin; phosphoric acid 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 to the toner. Resin particles such as polyamide resin particles, silicon resin particles, silicon rubber particles, urethane particles, melamine-formaldehyde particles, acrylic particles; rubbers, waxes, fatty acid compounds or resins, and inorganic particles of metals, metal oxides, and carbon black Composite particles comprising: Teflon (registered trademark), fluorine resin such as polyvinylidene fluoride; fluorine compound such as carbon fluoride; fatty acid metal salt such as zinc stearate; fatty acid derivative such as fatty acid ester; molybdenum sulfide, amino acid and amino acid Derivatives.

The developer used in the image forming method of the present embodiment is a two-component developer that is a mixture of a nonmagnetic polymer toner produced by suspension polymerization and a resin magnetic carrier. The ratio of the developer toner to the carrier (T / D ratio: the mass ratio of the toner in the two-component developer) is 8%, and the resin magnetic carrier has a magnetization amount in the magnetic field of 1 kiloOersted of 100 emu / cm ^3, and number average particle diameter and a 40 [mu] m, further the specific resistance is used. for 10 ¹³ Ω · cm.

  In general, the polymer toner has a higher degree of sphericity than the pulverized toner. The degree of sphericity of the shape of the toner particles is expressed using shape factors SF-1 and SF-2 calculated from the following equation (3). As for the toner shape factors SF-1 and SF-2, 100 toner images are randomly sampled using Hitachi FE-SEM (S-800), and the image information is obtained from an image analyzer (Luxex 3) manufactured by Nireco. And is calculated from the following equation (3).

（ＡＲＥＡ：トナー投影面積、ＭＸＬＮＧ：絶対最大長、ＰＥＲＩ：周長）

(AREA: toner projection area, MXLNG: absolute maximum length, PERI: circumference)

  Of the toner shape factors, SF-1 indicates the degree of sphericity. When SF-1 is 100, the toner is a true sphere, and when SF-1 is 100-140, the toner is substantially omitted. It is spherical. When SF-1 is larger than 140, the toner gradually changes from a substantially spherical shape to an indefinite shape. The shape factor SF-2 indicates the degree of unevenness of the toner particle surface. When SF-2 is 100 to 120, the toner surface is smooth. When SF-2 is greater than 120, In this case, the unevenness of the surface of the toner becomes remarkable. As the polymerized toner used in the image forming method of the present embodiment, a substantially spherical toner having an average particle diameter of 6 μm to 10 μm, a shape factor SF-1 of 100 to 140, and SF-2 of 100 to 120. However, it is preferable for maintaining high transfer efficiency.

  The toner used in the present embodiment is manufactured by a polymerization method, and silica, titanium oxide, or the like having a particle diameter of 20 nm is externally added to stabilize charged performance against environmental fluctuations and improve fluidity.

  In this embodiment, the spherical toner having good transferability is described by the polymerization method. However, the present invention is not limited to this, and for example, the toner prepared by a conventional mechanical pulverization classification method is used. It is also possible to use toner that has been subjected to thermal or mechanical post-treatment and rounded.

[Abrasive particles]
Next, the abrasive particles used in the present invention will be described. In the present invention, inorganic fine particles are used as the abrasive particles. Inorganic fine particles have high hardness and excellent polishing performance. The inorganic fine particles are preferably inorganic fine particles selected from the group consisting of strontium titanate, barium titanate and calcium titanate. The polishing performance is greatly related to the particle size of the inorganic fine particles, and the larger the particle size, the greater the polishing effect. Any shape can be used as long as it has excellent polishing performance, but strontium titanate having a cubic particle shape and / or a rectangular parallelepiped particle shape and having a perovskite crystal is used. Is preferred. Since the abrasive particles have a cubic particle shape and / or a rectangular parallelepiped particle shape and are perovskite-type crystals, the charged product on the surface of the image carrier can be efficiently removed. This is because the particle shape is cubic and / or rectangular parallelepiped, so that the contact area with the surface of the image carrier can be increased, and the ridgeline of the cube and / or cuboid is in contact with the surface of the image carrier. This is considered to be because good scraping properties can be obtained. The strontium titanate of the perovskite crystal used in the present invention preferably has an average primary particle size of 30 nm to 300 nm or less, more preferably 30 nm to 200 nm. If the average particle size is less than 30 nm, the polishing effect of the particles in the cleaner portion is insufficient. On the other hand, if the average particle size exceeds 300 nm, the polishing effect is too strong, so that scratches on the surface of the photoreceptor and contact-type charging roller damage occur. There is a case.

  Abrasive particles can be supplied by externally adding perovskite-type crystalline inorganic fine particles to the toner particles obtained as described above and developing the toner particles. At this time, the amount of the perovskite crystalline inorganic fine particles added to the toner particles is preferably 0.05 to 2.00 parts by mass, more preferably 0.20 to 1.80 parts by mass with respect to 100 parts by mass of the toner particles. In addition, when the perovskite inorganic fine particles surface-treated with a fatty acid having 8 to 35 carbon atoms or a metal salt thereof are externally added, the addition amount is preferably 0.05 to 3.00 parts by mass with respect to 100 parts by mass of the toner particles. 0.20 to 2.50 parts by mass are more preferable.

  Silica and titanium oxide used as external additives for the developer are also inorganic fine particles. In this case, since the particle size is as small as 20 nm and the shape is spherical or nearly polyhedral, the present invention. Effective polishing effect is unlikely to be exerted on the high durability photoconductor used in the above.

[Cleaning device]
Next, the cleaning device will be described. FIGS. 3, 4 and 5 are views relating to the cleaning blade. The cleaning blade 8a is made of polyurethane rubber that is integrally held at the tip of the sheet metal 8f, and is in contact with the photosensitive member 2 under conditions of a predetermined penetration amount δ and a set angle ψ. In the present invention, the rubber hardness of the cleaning blade is preferably 50 to 85 ° (JIS A), and more preferably 60 to 80 ° (JIS A). In this embodiment, a cleaning blade having urethane rubber of 70 ° (JIS A) is used, ψ = 22 °, δ is in the range of 0.5 to 1.3 mm, and the contact pressure B of the cleaning blade to the photoreceptor 2 is B. In the range of 10 to 50 g / cm. The contact pressure B of the cleaning blade is preferably 10 to 50 g / cm. When the contact pressure of the cleaning blade is less than 10 g / cm, cleaning failure due to toner slippage is likely to occur, and when it exceeds 50 g / cm, it is difficult to obtain satisfactory durability due to chipping of the cleaning blade. .

  In the present invention, the abrasive particles are present at the contact portion between the cleaning blade and the image carrier. As a method of supplying the abrasive particles to the corresponding contact portion, for example, a method of supplying the toner particles by externally adding the abrasive particles to the developing and a method of supplying the abrasive particles separately by a supply member are used. The method of supplying abrasive particles externally to toner particles is such that, after transferring a toner image to a recording medium, the transfer residual toner and abrasive particles are, for example, 5 masses with respect to the transfer residual toner remaining on the surface of the photoreceptor. Add externally so as to be mixed at a ratio of%. Specifically, the amount of toner remaining after transfer varies depending on the density of the image to be formed. Therefore, the addition ratio is about 5 to 20%, which is a commonly used image density. Based on the average amount of residual toner generated when forming an image having a density, the addition amount is set so that abrasive particles are mixed in a desired ratio in the residual toner. For example, when 100 images having a density of about 5 to 20% are created, the ratio of the abrasive particles added to the waste toner once collected by the cleaning device is 5% in the waste toner. A method of adjusting the amount of abrasive particles added externally so as to have a mass% ratio can be used.

  At that time, in the transfer process, the toner particles are more selectively transferred onto the recording medium. As a result, the mixing ratio of the abrasive particles is relatively increased in the transfer residual toner. That is, the mixing ratio of the abrasive particles in the transfer residual toner is significantly higher than the mixing ratio of the abrasive particles contained in the toner used for development. Therefore, in the image forming conditions of the above-mentioned frequently used image density, the abrasive particles externally added to the toner in advance so that the mixing ratio of the added abrasive particles is within a desired ratio range in the waste toner. It is desirable to adjust the addition ratio.

  On the other hand, depending on the case, in the image forming apparatus in which the average value of the formed image density is in a usage state that significantly exceeds the above-mentioned density of about 20%, according to the average value, the abrasive particles to be externally added It can be set to increase the amount of addition. On the contrary, in the image forming apparatus in which the average value of the formed image density is in a usage state that is significantly lower than the above-mentioned density of about 5%, it can be set so as to reduce the amount of abrasive particles added. It goes without saying that no problem is caused even when a standard addition amount for a concentration of about 5 to 20% is used.

  When setting the addition amount of the abrasive particles, the ratio of the added abrasive particles in the transfer residual toner is evaluated by using the fluorescent X-rays specific to the inorganic fine particles used for the abrasive particles. A method for obtaining the mixing ratio of the measured abrasive particles in the transfer residual toner using the fluorescent X-ray intensity per unit mass sample in a standard sample with a known mixing ratio as a calibration curve can be used.

  On the other hand, when supplying abrasive particles directly to the surface of the photoreceptor using an abrasive particle supply device instead of externally adding toner particles as a method for supplying abrasive particles, after passing through the transfer portion, the photoreceptor 2 is supplied. It is also possible to carry out at any position until reaching the contact portion between the cleaning blade 8a and the cleaning blade 8a. For example, as shown in FIG. 3, the rotating fur brush 8d that supplies abrasive particles may be configured to supply abrasive particles immediately before the contact portion of the cleaning blade 8a, for example.

  In addition, a configuration in which abrasive particles are partially externally added in advance to the toner particles, and after passing through the transfer portion, an abrasive particle supply device is provided to supply the abrasive particles directly to the surface of the photoreceptor. You can also At this time, the abrasive particles externally added to the developing toner in advance and the abrasive particles supplied in a fixed amount from the abrasive particle supply device are totaled to obtain the desired abrasive particles in the transfer residual toner. Each addition amount can also be set so that it may mix in a ratio range.

  Usually, when the edge tip of the cleaning blade comes into contact with the movement direction of the photoreceptor surface from the counter direction, the wedge-shaped gap has a finer particle diameter and fine particles with poor adhesion, for example, Silica, titanium oxide, and in the case of the present invention, abrasive particles and the like are accumulated, and the toner particles enter the wedge-shaped gap and prevent the phenomenon of slipping through the gap.

  FIG. 4 schematically shows the contact state of the edge tip of the cleaning blade 8a with the surface of the photoreceptor in the cleaning device 8 used in the image forming method of the present invention. Inside the wedge-shaped gap formed by the edge tip abutted from the counter direction with respect to the moving direction A of the surface of the photoreceptor, a finer particle diameter, in the case of this embodiment, silica, titanium oxide, Abrasive particles and the like are classified and accumulated.

[Charging]
FIG. 2 shows a front view, a cross-sectional view, and a top view of the charging member and the photosensitive member.

  The contact type charging roller 3 as a flexible contact charging member as a charging member in this embodiment is formed by forming a middle resistance layer of rubber or foam on a cored bar.

  The middle resistance layer was formulated with a resin (urethane in this example), conductive particles (for example, carbon black), a sulfurizing agent, a foaming agent, and the like, and formed in a roller shape on the core metal. Thereafter, the surface was polished.

Here, it is important that the contact-type charging roller 3 as a charging member functions as an electrode. That is, it is necessary to provide a sufficient contact state with the photoconductor by providing elasticity, and at the same time, have a sufficiently low resistance to charge the moving photoconductor. 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 photoreceptor. In order to obtain sufficient chargeability and leakage resistance, the resistance value of the contact-type charging roller is preferably 10 ⁴ to 10 ⁷ Ω. In this embodiment, the resistance value of the contact-type charging roller is 10 ⁶ Ω. The resistance value of the contact charging roller 3 was measured as follows. The photoconductor 2 of the printer is replaced with an aluminum drum. Thereafter, a voltage of 100 V was applied between the aluminum drum and the core metal 3a of the contact-type charging roller 3, and the resistance value of the contact-type charging roller 3 was obtained by measuring the current value flowing at that time. The resistance measurement was performed in an environment at a temperature of 25 ° C. and a humidity of 60%.

  If the hardness of the contact-type charging roller 3 is too low, the shape is not stable, so that the contact property with the photosensitive member is deteriorated. If the hardness is too high, the charging nip portion N cannot be secured between the photosensitive member and the photosensitive member. Since the micro contact property to the surface of the photoreceptor is deteriorated, the Asker C hardness is preferably 20 ° or more and 60 ° or less. In this embodiment, a 40 ° one is used.

  The material of the contact-type charging roller 3 is not limited to the elastic foam, but the material of the elastic body may be EPDM, urethane, NBR, silicone rubber, carbon black or metal oxide for adjusting resistance to IR or the like. Examples thereof include rubber materials in which conductive materials such as these are dispersed, and those obtained by foaming these materials. It is also possible to adjust the resistance using an ion conductive material without dispersing the conductive substance.

  The contact-type charging roller 3 is arranged as shown in FIG. 2 while the cored bar 3a is supported by the bearing 22 at both ends in the longitudinal direction, and the load associated with the bearing 22 is added. A pressure spring 23 as a pressure member is pressed against the surface of the photoreceptor 2. At this time, the contact pressure of the contact charging roller with respect to the surface of the photoreceptor 2 is preferably 50 (g / cm) or less. When the abrasive particles are supplied when the particle size is larger than 50 (g / cm), the abrasive particles that have passed through the cleaning blade are rubbed between the contact charging roller and the photosensitive member, and the contact charging roller or photosensitive Causes damage to the body surface. On the other hand, the lower limit of the contact pressure is determined by the charging property. If the contact pressure is too low, the contact nip between the photosensitive member 2 and the contact-type charging roller 3 becomes unstable, and stable discharge is difficult. In this embodiment, the contact pressure of the contact-type charging roller 3 against the surface of the photoreceptor 2 is set to 30 [g / cm]. In this setting, the contact width n (nip width) between the photosensitive member 2 and the contact charging roller 3 is 2 mm or more in the longitudinal direction even when the crossing angle between the photosensitive member and the contact charging roller is provided as in the present invention. Secured and stable chargeability was obtained. The contact pressure is expressed as a linear pressure per unit length in the longitudinal direction of the contact-type charging roller 3. However, when the contact width is about 3 mm or less, the contact area is very small, so the line pressure is higher than the pressure per unit area. In terms of ease of measurement, the pressure is more appropriate.

  As a method for measuring the contact pressure, two thin plates made of SUS are inserted into a contact nip region between the photosensitive member 2 and the contact-type charging roller 3, and a thin plate having a width of 1 [cm] is pulled out. It was obtained by measuring the force required for the measurement with only a spring. The contact-type charging roller 3 is driven to rotate in the direction of the arrow as the photoconductor 2 rotates.

  In the present invention, the rotation axis of the contact type charging roller 3 is provided with a crossing angle of an angle θ ° with respect to the rotation axis of the photosensitive member as shown in FIG. The purpose of providing the crossing angle in the present invention is to diffuse as much as possible the contamination of the contact-type charging roller from external additives, etc. as disclosed in Japanese Patent No. 0245726, and to prevent local charging failure. It is. In the present invention, since the abrasive particles are supplied to the cleaning blade, the contact type charging roller due to the abrasive particles is prevented from being contaminated, and the contact type charging roller and the photosensitive drum due to local contamination are prevented from being damaged.

  The contact-type charging roller described above rotates following the rotation of the photosensitive member. The contact-type charging roller is subjected to constant current control with a frequency of 1.8 kHz and a total current of 2000 μA from a high-voltage power supply for charging, and the photoreceptor potential is determined by the superimposed DC bias.

  Hereinafter, the present invention will be described more specifically with reference to examples. The present invention is not limited to these examples.

Example 1
The outline of the image forming apparatus used in the present embodiment is as described in the above embodiment. As the abrasive particles, strontium titanate having an average primary particle diameter of 100 nm, a cubic particle shape and / or a rectangular parallelepiped particle shape, and a perovskite crystal was used. The abrasive particles had a content ratio of particles having a particle diameter of 600 nm or more and aggregates of 1% by number or less. The abrasive particles used in this embodiment have a cubic particle shape and / or a rectangular parallelepiped particle shape, and are perovskite crystals, thereby efficiently removing charged products on the surface of the photoreceptor. be able to. A supply member for abrasive particles was provided in the cleaning container. FIG. 3 shows the apparatus configuration. The cleaning device 8 includes a cleaning blade 8a as a cleaning means supported by a sheet metal 8f, a toner collecting sheet 8b, a waste toner collecting container 8c, a fur brush 8d as a supply member of abrasive particles, a brush scraper 8e as a scraper member, a partition wall 8k, abrasive particles 8j, and the like. Here, the abrasive particles 8j may be powder, or may be once melted and solidified. The fur brush rotates in the same direction at the contact portion with the photosensitive drum. The supply amount of the abrasive particles can be adjusted, for example, by changing the rotation speed of the fur brush and the fur brush fiber density.

The fur brush 8d used in the present example is configured by planting conductive fibers on a base fabric and winding it around a core metal 8h having a diameter of 6 mm to form a brush shape having a diameter of 16 mm. Has been. As the fiber, for example, various materials such as nylon, rayon, polyester, acrylic, and the like can be used. In this embodiment, a conductive thread of nylon having a thickness of 0.7 Tex is used, and the fiber density is 93 fibers / mm ^2. The material implanted in the base fabric was formed into a sheet shape, and was wound spirally so as to ensure conduction with the core metal 8h.

  The supply amount of the abrasive particles was adjusted by changing the rotation speed of the fur brush 8d.

  Further, when the fur brush 8d is repeatedly operated for a long time, the brush fibers are clogged, and the abrasive particle supply performance is lowered. In order to prevent this, a brush scraper 8e, which is a member that scrapes off toner and the like accumulated on the brush fibers, is provided. In this embodiment, a flexible PET sheet having a thickness of 0.1 mm is attached to the sheet metal 8g as the brush scraper 8e, the free length is set to 2 mm, and the intrusion amount β = 1.0 mm with respect to the fur brush 8d is set. is doing.

  For the waste toner stored in the cleaning device, the amount (mixing ratio) of strontium titanate contained was measured by the fluorescent X-ray analysis described above.

  As drum characteristics, the larger the HU, the higher the hardness and the harder the surface is. Further, the elastic deformation rate We has a characteristic that the higher the value, the harder it is to cut. In other words, HU × We is an index representing the difficulty of scraping the surface of the photosensitive drum, and the larger the value, the harder it is to scrape.

  An object of the present invention is to polish the surface of a highly durable photosensitive drum having a small scraping amount as described above with a cleaning unit, refresh a photoreceptor deteriorated by charging, and prevent image flow and poor cleaning.

  The refreshing effect on the surface of the photoreceptor is achieved by abrasive particles and a cleaning blade. As described above, the vicinity of the cleaning blade edge is as shown in FIG. 4, and fine particles having a small particle size are accumulated in a wedge-shaped gap formed between the blade edge and the surface of the photoreceptor. It is considered that as the supply amount of abrasive particles increases, the amount of abrasive particles accumulated in the wedge-shaped gap increases, and the polishing force on the surface of the photoreceptor increases. Also, the polishing force increases by increasing the contact pressure of the cleaning blade. This is presumably because the frictional force of the blade itself against the photoconductor increases and the pressure of abrasive particles accumulated in the wedge-shaped gap increases against the surface of the photoconductor.

  In other words, the polishing force on the surface of the photosensitive member is the product A × B of the supply amount A of abrasive particles (in the present invention, the abrasive particle ratio A mass% in the transfer residual toner) and the cleaning blade contact pressure B (g / cm). expressed.

  On the other hand, intervening particles exist at the contact portion (nip portion) between the cleaning blade and the photosensitive member, and maintain lubricity. If there are no intervening particles, the cleaning blade will bend. As the intervening particles, it is considered that fine particles accumulated in the wedge-shaped gap near the edge are gradually entering. The amount of particles that pass through also depends on the cleaning blade contact pressure B. The higher the pressure, the smaller the amount of particles that pass through. That is, it is considered that the level at which the abrasive particles slip through the cleaning blade and contaminate the contact-type charging roller becomes worse in proportion to A / B.

  Normally, when a contact-type charging roller is used as the charging member, a pad-like or brush-like cleaning member is provided to keep the roller surface clean. However, when it is durable for a long period of time, it is contaminated in the form of streaks in the circumferential direction of the roller at places where the contact state of the cleaning member is poor or where the cleaning member is partially slipped through. In the contaminated portion, the surface resistance of the contact-type charging roller is changed, so that the charging property is changed. In particular, the contact-type charging roller is often contaminated in the form of streaks as described above, so that the difference from a non-contaminated adjacent portion is large and tends to appear in a halftone or other halftone. In the case of using a full-color image forming apparatus as in this embodiment, since the proportion of halftone is large, it becomes more severe with respect to uneven contamination of the contact-type charging roller. Further, since abrasive particles are used in the present invention, local (streak-like) contamination causes damage to the contact-type charging roller surface and the photoreceptor surface. Therefore, in this embodiment, the contact charging roller and the photosensitive drum are provided with a crossing angle θ to diffuse the contaminants adhering to the contact charging roller surface. When the crossing angle is provided, the vectors in the rotation direction of the contact-type charging roller and the photosensitive drum are different, so that contaminants are diffused in the nip portion. The greater the crossing angle θ, the stronger the diffusion force, and the more local (streak-like) contamination is less likely to occur.

With the above configuration, the abrasive particle supply amount A (% by mass), the cleaning blade contact pressure B (g / cm), and the crossing angle θ (°) are varied, and the characteristics of the photoconductor produced by the above-described production method are HU. Various photoconductors having different We were prepared, and experiments on image flow and cleanability were conducted.
The manufacturing method of the photoreceptor used here is as follows.

(Photoreceptor manufacturing method A)
An aluminum cylinder having a diameter of 60 mm × 357.5 mm is used as a conductive support, and a coating liquid composed of the following materials is applied onto the conductive support by a dip coating method, followed by heat curing at 140 ° C. for 30 minutes. A conductive layer having a film thickness of 18 μm was formed.
Conductive pigment: SnO ₂ coated barium sulfate 10 parts Resistance control pigment: titanium oxide 2 parts Binder resin: phenol resin 6 parts Leveling material: silicone oil 0.001 part Solvent: methanol / methoxypropanol = 0.2 / 0.8 15 parts

  Next, a solution obtained by dissolving 3 parts of N-methoxymethylated nylon and 3 parts of copolymer nylon in a mixed solvent of 65 parts of methanol / 30 parts of n-butanol was applied as a coating solution on this conductive layer by a dip coating method. Thus, an intermediate layer having a thickness of 0.7 μm was formed.

  Next, 4 parts of hydroxygallium phthalocyanine having strong peaks at 7.4 ° and 28.2 ° of the black angle (2θ ± 0.2 °) of CuKα characteristic X-ray diffraction, polyvinyl butyral (trade name: ESREC BX-1) 2 parts of Sekisui Chemical Co., Ltd.) and 80 parts of cyclohexanone were dispersed in a sand mill using 1 mm diameter glass beads for 4 hours, and then 80 parts of ethyl acetate was added to prepare a coating solution for charge generation layer. This was applied by a dip coating method to form a charge generation layer having a thickness of 0.2 μm.

Next, 7 parts of a styryl compound of the following general formula (2) and 10 parts of a polycarbonate resin (trade name: Iupilon Z800, manufactured by Mitsubishi Engineering Plastics) were dissolved in a mixed solvent of 105 parts of monochlorobenzene / 35 parts of dichloromethane. A charge transport layer was formed on the charge generation layer using the charge transport layer coating solution prepared above. The film thickness of the charge transport layer at this time was 10 μm.

Next, 45 parts of a hole transporting compound represented by the following general formula (3) was dissolved in 55 parts of n-propyl alcohol to prepare a surface layer coating solution.

Using this coating solution, a surface layer is coated on the charge transport layer, and then irradiated with an electron beam in nitrogen under conditions of an acceleration voltage of 150 KV and a dose of 1.5 × 10 ⁴ Gy, and then electrophotographic photosensitive. Heat treatment was performed for 3 minutes under the condition that the body temperature was 150 ° C. The oxygen concentration at this time was 80 ppm. Further, the electrophotographic photoreceptor was post-treated at 140 ° C. for 1 hour in the air to form a surface layer having a thickness of 5 μm, thereby obtaining a photoreceptor.

A part of the obtained electrophotographic photosensitive member was allowed to stand in an environment of 23 ° C./50% RH for 24 hours, and then the following hardness measurement was performed. The universal hardness value (HU) and elastic deformation rate are measured by a microhardness measuring device, Fischerscope H100V, in which continuous hardness is obtained by applying a continuous load to the indenter and directly reading the indentation depth under the load. (Fischer). As the indenter, a Vickers quadrangular pyramid diamond indenter having a facing angle of 136 ° can be used. Specifically, measurement is performed in stages (273 points with a holding time of 0.1 sec for each point) up to a final load of 6 mN.
The photoconductor prepared by this manufacturing method had We = 57 and HU = 185.

(Photoreceptor manufacturing method B)
In the photoreceptor manufacturing method A, the photoreceptor is the same as the photoreceptor manufacturing method A, except that the coating liquid in which 45 parts of polytetrafluoroethylene fine particles are added and dispersed in the coating liquid for the surface layer is used as the coating liquid for the surface layer. Was made.
The photoreceptor prepared by this manufacturing method had We = 40 and HU = 150.

(Photoreceptor manufacturing method C)
In the photoreceptor production method A, 45 parts of the hole transporting compound represented by the general formula (3) is added to 30 parts, 15 parts of an acrylic monomer represented by the following general formula (12) is added, and 5 parts of polytetrafluoro An electrophotographic photosensitive member was produced in the same manner as in the photosensitive member production method A, except that the coating solution in which ethylene fine particles were added and dispersed was used as the coating solution for the surface layer.
The photoreceptor prepared by this manufacturing method had We = 65 and HU = 220.

As another method for controlling HU and We, changing electron beam irradiation conditions can also be used effectively. For example, if the electron beam irradiation conditions are set to be lower than 1.5 × 10 ⁴ Gy of the photoconductor manufacturing method A, the values of HU and We can be made small. In this way, a photoconductor having controlled values of HU and We was prepared.

  FIG. 6 shows a graph showing the relationship between A × B and HU × We. A numerical value 6000 on the horizontal axis is a value that minimizes HU × We in a range of 150 ≦ HU ≦ 220 and 40 ≦ We ≦ 65, that is, a condition that the photoconductor is most easily scraped. Even if the condition is easy to scrape, the amount of scraping is smaller than that of a conventional organic photoreceptor. Under the condition of HU × We = 6000, the abrasive particle supply amount A and the contact pressure B of the cleaning blade were varied, and an endurance test of 10,000 sheets was performed and evaluated in an environment of a temperature of 30 ° C. and a humidity of 80%. The results are shown in Table 1. In Table 1, ◯ means good and x means bad.

  Next, in the range of 150 ≦ HU ≦ 220 and 40 ≦ We ≦ 65, the value at which HU × We is the maximum, that is, the condition HU × We = 14300, which is the most difficult to scrape as a photoreceptor, is the abrasive particle supply amount A, the cleaning blade The durability test of 10,000 sheets was evaluated in an environment of 30 ° C. and 80% humidity. The results are shown in Table 2. In Table 2, ◯ means good and x means bad.

In addition, evaluation was performed under various HU × We value conditions. The results are summarized as follows:
1/6000 × HU × We ≦ A × B (I)
In the range that satisfies the conditions, image flow, cleaning blade stagnation, chattering, and chipping did not occur. This is the shaded area in FIG. That is, the larger the value of HU × We (the harder the photosensitive drum becomes), the larger the value of A × B is necessary (strong polishing power is required). This is presumably because the surface of the drum is not refreshed so much that the drum surface is hard to be scraped, and the discharge products accumulate much. Further, the contact pressure B (g / cm) of the cleaning blade needs to satisfy 10 ≦ B ≦ 50. When the contact pressure B of the cleaning blade is less than 10 g / cm, the toner tends to slip through, and when it exceeds 50 g / cm, the cleaning blade tends to chip.

  Next, regarding the contact type charging roller contamination, as described above, the contamination level becomes worse as the value of A / B increases. That is, as the A / B value increases, the level of streak-like contamination on the contact-type charging roller becomes worse, and thus a stronger diffusibility is required. Table 3 shows the supply of abrasive particles A, contact pressure B of the cleaning blade, and contact charging roller crossing angle θ, and an environment with a temperature of 23 ° C. and humidity of 5%, where image unevenness due to contact charging roller contamination is likely to occur. The results of performing an endurance test and evaluating the results are shown below. In Table 3, ○ means good and × means bad.

Table 3 summarizes the results under conditions where the A / B value is relatively large. The results evaluated under small conditions are summarized as follows:
A / B ≦ θ (II)
In the range satisfying the above, no image defect due to contact-type charging roller contamination occurred. FIG. 7 shows the relationship between A / B and θ, where the shaded area is a range where good chargeability can be obtained. When θ> 5.00, the contact of the end portion of the charging roller with the photosensitive member deteriorated, and good chargeability could not be obtained. The crossing angle θ (°) between the rotation axis of the contact-type charging roller and the rotation axis of the image carrier is preferably 0 <θ ≦ 5.00, more preferably 0.10 to 0.50. is there.

Summarizing the above results, in the configuration of this example, the following formula (I)
1/6000 × HU × We ≦ A × B (I)
And the following formula (II)
A / B ≦ θ (II)
And the following formula (III)
By satisfying the condition of 10 ≦ B ≦ 50 (III), image flow under high humidity and image unevenness due to contamination of the contact charging roller under low humidity did not occur, and good cleaning performance was obtained.

(Example 2)
In this embodiment, as a method for supplying abrasive particles, a method of supplying the toner particles by adding them to the developing toner and developing them is used. As the configuration of the cleaning device 8, a configuration obtained by removing the rotating fur brush 8d and the abrasive particles 8j of the abrasive particle supply member from those used in Example 1 was used. Other configurations are the same as those of the first embodiment.

  Table 4 shows the relationship between the ratio of abrasive particles externally added to the developing toner and the mixing ratio of abrasive particles present in the transfer residual toner (waste toner).

  With the configuration as described above, the abrasive particle supply amount A (mass%) and the cleaning blade contact pressure B (g / cm) were respectively shaken in the same manner as in Example 1, and the temperature was 30 ° C. and the humidity was 80%. The image unevenness, charging unevenness in an environment of a temperature of 23 ° C. and a humidity of 5%, and cleaning properties were evaluated from a durability test of 10,000 sheets.

The result is the following formula (I)
1/6000 × HU × We ≦ A × B (I)
And the following formula (II)
A / B ≦ θ
And the following formula (III)
10 ≦ B ≦ 50 (III)
Satisfying the above conditions, image flow under high humidity and contact-type charging roller contamination under low humidity will not cause image unevenness, and good cleaning performance can be obtained. was gotten.

(Example 3)
In this embodiment, as a method for supplying abrasive particles, a method of supplying the developer by externally adding to the developing toner and a method of providing an abrasive particle supplying member in the cleaning container are used in combination. The configuration of the cleaning device 8 is the same as that of the first embodiment. In the same manner as in Examples 1 and 2, the abrasive particle supply amount A (mass%), the cleaning blade contact pressure B (g / cm), and the crossing angle θ were varied, and the temperature was 30 ° C. and the humidity was 80%. The image unevenness, charging unevenness in an environment of a temperature of 23 ° C. and a humidity of 5%, and cleaning properties were evaluated from a durability test of 10,000 sheets.

The result is the following formula (I)
1/6000 × HU × We ≦ A × B (I)
And the following formula (II)
A / B ≦ θ (II)
And the following formula (III)
10 ≦ B ≦ 50 (III)
If the above condition is satisfied, image flow under high humidity and image unevenness due to contamination of the contact-type charging roller under low humidity do not occur, and good cleaning performance is obtained. By providing two or more means as the abrasive particle supply means as in the configuration of this embodiment, it is possible to supply the abrasive particles more stably throughout the durability.

Schematic cross-sectional view of an image forming apparatus suitable for the present invention Schematic configuration diagram of contact-type charging roller and photoreceptor used in the present invention FIG. 1 is a schematic cross-sectional view of a cleaning device according to first and third embodiments suitable for the present invention. Enlarged view of the vicinity of the cleaning blade edge Schematic configuration diagram of cleaning blade and photoconductor The figure which shows the relationship between AxB of Example 1 and HUxWe. The figure which shows the relationship between (theta) and A / B of Example 1. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Image carrier (photosensitive body)
3 Charging means (contact charging roller)
4 Electrostatic latent image forming means (laser oscillator)
5 Exposure light (laser beam)
6 Development means (rotary development device)
6y First developing device 6m Second developing device 6c Third developing device 6k Fourth developing device 7 Intermediate transfer member 7a First transfer portion 7b Second transfer portion 7c High-voltage power supply 8 Cleaning device 8a Cleaning blade 8b Toner collection sheet 8c Waste toner collection container 8d Fur brush 8e Brush scraper 8f Sheet metal 8h Core metal 8j Abrasive particles 8k Bulkhead 9 Cassette 10 Pickup roller 11 Registration roller pair 12 Transfer means (transfer belt)
12a Bias roller 12b Tension roller 12c High-voltage power supply 13 Intermediate transfer member cleaning device 14 Fixing means 15 Discharge roller pair 22 Bearing 23 Pressure spring 3a Core metal 41 Fine particles 42 Toner S Recording medium

Claims (7)

A charging step of charging the image carrier with a charging member, an electrostatic latent image forming step of forming an electrostatic charge image on the charged image carrier, and development for developing the electrostatic charge image with toner to form a toner image A transfer step of transferring a toner image formed on the image carrier onto a recording medium via or without an intermediate transfer member, and a fixing step of heating and fixing the toner image on the recording medium; and a cleaning step for cleaning the image bearing member surface after transfer by the cleaning member to an image forming method having the at least without
The image bearing member performs a hardness test using a Vickers square pyramid diamond indenter at a temperature 25 ° C. humidity of 50%, the universal hardness value HU of the surface when pushed in the maximum load 6mN is 150 N / mm ² or more An image bearing member having an elastic deformation rate We of 40% or more and 65% or less, and 220 N / mm ² or less,
The charging member is a contact-type charging roller provided so as to come into contact with the image carrier, and the rotation axis of the contact-type charging roller and the rotation axis of the image carrier cross each other with a crossing angle θ (°). Are arranged to
The cleaning member is a cleaning blade provided so as to come into contact with the image carrier, and abrasive particles are present in a contact portion between the cleaning blade and the image carrier,
HU, We, A, B, and θ are as follows when the ratio of the residual transfer toner and abrasive particles reaching the cleaning blade is A (mass%) and the contact pressure of the cleaning blade is B (g / cm). Formula (I)
(1/6000) × HU × We ≦ A × B (I)
And the following formula (II)
A / B ≦ θ (II)
And the following formula (III)
10 ≦ B ≦ 50 (III)
Satisfied ,
The abrasive particles are inorganic fine particles selected from the group consisting of strontium titanate, calcium titanate and barium titanate,
The abrasive particles are
i) The average particle size of the primary particles is 30 nm to 300 nm,
ii) having a cubic particle shape and / or a rectangular parallelepiped particle shape,
iii) having a perovskite crystal structure;
iv) The image forming method, wherein the content of particles having a particle diameter of 600 nm or more and aggregates is 1% by number or less . The image forming method according to claim 1, wherein the abrasive particles are supplied by an abrasive particle supply member in a cleaning container.   The image forming method according to claim 2, wherein the abrasive particle supply member in the cleaning container is a rotatable fur brush. 2. The image forming method according to claim 1, wherein the abrasive particles are supplied by being externally added to the toner particles and developed. The cleaning blade, the image forming method according to any one of claims 1 to 4, characterized in that a rubber blade. Contact pressure against the image bearing member of the contact charging roller, 50 (g / cm) The image forming method according to any one of claims 1 to 5, characterized in that less. The image forming method according to any one of claims 1 to 6 Asker C hardness of the contact charging roller, characterized in that at 20 ° to 60 °.

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