JP2007156059A - Image forming apparatus and image forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To precisely remove toner remainings on an image carrier surface after toner image transfer with an image forming apparatus using the spherical toner of a small diameter. <P>SOLUTION: A blade edge 31a consisting of a rubber elastic body of the cleaning blade 31 containing magnet particles 32 in a dispersion state in the blade edge 31a is made to abut on the surface of the image carrier 8. The amorphous particles having magnetism are supplied to the edge to form a magnetic amorphous particle layer 33. The residual spherical toner on the image carrier surface, i.e. the compact spherical toner 34, are stemmed by the particle layer 33. As a result, the intrusion of the spherical toner to the back of the edge can be prevented even if the toner having sphericity of ≥0.96 and volume average grain size of ≤6 μm is used as the spherical toner. Consequently, a high degree of developability and transferability of a latent image (toner image) can be obtained and in addition, the high definition image can be stably obtained. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image forming apparatus and an image forming method using electrophotography.

  In recent years, an image forming apparatus using an electrophotographic method has been improved in image quality, and specific examples of the directionality include a reduction in toner diameter and a spherical shape. By reducing the diameter, an image faithful to the latent image can be obtained, and by making it spherical, it is considered that developability and transferability are improved and high image quality is achieved.

  If the diameter of the toner is reduced by a pulverization method, which is a typical typical toner manufacturing method, the yield is poor and the cost is increased. Therefore, recently, a toner is produced by a polymerization method which is advantageous in terms of cost even when the diameter is reduced and the shape is made spherical. Examples of the toner production method by polymerization include suspension polymerization, emulsion polymerization, and dispersion polymerization.

  However, such a small-diameter and spherical toner has a drawback that cleaning (removal from the surface of the image carrier) is difficult. That is, even with a blade cleaning method in which a widely used rubber blade is pressed against the photoreceptor, there is a problem that the toner slips through the gap between the blade and the photoreceptor. The concept of this slip-through phenomenon is as follows: (a) When the toner dammed at the blade edge is spherical and has a particularly narrow particle size distribution, it is easy to close-pack, and the dammed toner layer is composed of one aggregate. Since the force that pushes up the blade works like this, the idea that slip-through occurs, and (b) in the case of small diameter toner, the toner is particularly easy to enter the gap where the blade edge is slightly deformed, and it is spherical, There is an idea that slipping occurs while rolling.

  In the following Patent Documents 1 and 2, as a means for solving the above-mentioned problem, by depositing amorphous particles that hardly cause compaction or rolling on the blade edge and forming a layer by damming the irregular particles on the blade edge A method of performing blade cleaning of spherical small-diameter toner has been proposed.

  However, since the damming layer of these irregularly shaped particles is only deposited on the blade edge, the irregularly shaped particles are repelled by the vibration of the blade, so that the accumulation of irregularly shaped particles cannot be sufficiently maintained, and good cleaning properties are achieved. It was difficult to maintain stably.

  Therefore, a method for firmly holding the deposited layer of irregular shaped particles has also been proposed. Patent Document 3 describes a method of depositing amorphous particles by using magnetic powder as irregular particles, generating a magnetic field at the blade edge portion. As a magnetic field generation method, a method of installing a magnetic field generation member inside a member facing the blade or a method of attaching a magnetic member to the edge portion of the blade has been proposed.

  However, in these magnetic field generation methods, it cannot be said that amorphous particles are sufficiently retained. For small and spherical toners having a circularity of 0.96 or more and a particle size of 6 μm or less, the irregular particles are There is a possibility that toner enters the deposited layer and causes cleaning failure. Further, the method of installing the magnetic field generating member inside the member facing the (cleaning) blade leads to an increase in the size of the apparatus and an increase in manufacturing cost, and is not suitable for a low-priced small machine.

  In addition, in the method of attaching the magnet member to the edge portion of the blade, the accuracy of the blade edge after attaching the magnet member is lowered, so if it is attempted to achieve the same accuracy as a normal cleaning blade, the manufacturing cost will increase. Invite. Furthermore, since a magnet member having a very low elasticity compared with a normal urethane rubber blade becomes the blade edge portion, there is a problem that the blade edge is likely to be chipped.

  Also, none of the above methods considers the durability of the blade, and even if the initial cleaning property is good, cleaning failure tends to occur over time. In recent years, there has been a demand for higher durability of parts in order to reduce the burden of maintenance work on service personnel. Furthermore, in addition to the cleaning properties of the spherical toner, high wear resistance is also required, and it cannot be said that sufficient studies have been made in the prior art as described above.

JP-A-8-254873 JP 2001-166659 A JP 2002-6710 A

  The present invention has been made in view of the above circumstances of the prior art, and an object of the present invention is to provide an image forming apparatus and an image forming apparatus in which toner remaining on the surface of an image carrier after transferring a toner image is removed by a cleaning blade. In the method, even when a small-diameter and spherical toner (for example, a toner having a circularity of 0.96 or more and a particle size of 6 μm or less) is used, good cleaning characteristics are obtained and the durability of the blade is high. Another object of the present invention is to provide an image forming apparatus and an image forming method in which good cleaning characteristics are maintained over a long period of time.

  The image forming apparatus and the image forming method according to the present invention achieve the above object by firmly depositing and holding a layer of magnetic amorphous particles on the (blade) edge of a cleaning blade.

  That is, the invention according to claim 1 is a developing device that develops a latent image on an image carrier with spherical toner, a transfer device that transfers a developed image formed on the image carrier by development onto a transfer material, and rubber. In the image forming apparatus, comprising at least a cleaning device that removes spherical toner remaining on the surface of the image carrier after transfer of the visible image by bringing a cleaning blade made of an elastic body into contact with the surface of the image carrier. A magnetic amorphous particle supply device for supplying irregular particles having magnetism for damming up the residual spherical toner by depositing and holding on the edge of the toner, and the cleaning blade contains magnet particles in a rubber elastic body (Magnet particles are contained at least in the blade edge portion).

According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, the spherical toner has a circularity of 0.96 or more and a volume average particle size of 6 μm or less.
According to a third aspect of the present invention, in the image forming apparatus according to the second aspect, the circularity of the spherical toner is 0.98 or more and the volume average particle diameter is 5 μm or less.
According to a fourth aspect of the present invention, in the image forming apparatus according to any one of the first to third aspects, the magnet particles are dispersed and blended in the cleaning blade, and the volume average particle diameter of the magnet particles is 5 μm or more and 50 μm or less. It is characterized by being.
According to a fifth aspect of the present invention, in the image forming apparatus according to any one of the first to fourth aspects, the contact pressure of the cleaning blade against the image carrier is 0.20 N / cm or less, and the image carrier and the cleaning blade Is formed with a cleaning angle θ of 80 degrees or more.
According to a sixth aspect of the present invention, in the image forming apparatus according to any one of the first to fifth aspects, the volume average particle diameter Df of the amorphous particles having magnetism and the volume average particle diameter of the spherical toner that develops the latent image. The ratio of Dt (Df / Dt) satisfies the relationship of 1.3> (Df / Dt)> 0.01.
According to a seventh aspect of the present invention, in the image forming apparatus according to the sixth aspect, the ratio (Df) of the volume average particle diameter Df of the amorphous particles having magnetism to the volume average particle diameter Dt of the spherical toner for developing the latent image. / Dt) satisfies the relationship of 0.9> (Df / Dt)> 0.01.
The invention according to claim 8 is the image forming apparatus according to any one of claims 1 to 7, wherein the developing device performs development by a two-component developing method using a developer formed by mixing a carrier and a spherical toner. And the carrier has a content ratio of particles having a weight average particle diameter Dw of less than 22 μm of 3 wt% or less.

According to the ninth aspect of the present invention, the latent image on the image carrier is developed with a spherical toner to form a visible image, the visible image is transferred to a transfer material, and a cleaning blade made of a rubber elastic body is provided on the surface of the image carrier. A cleaning blade (magnet particles) containing magnet particles in a rubber elastic body in an image forming method having at least a step of removing spherical toner remaining on the surface of the image carrier after transferring a visible image Is contained in at least the blade edge portion), and the amorphous particles having magnetism are supplied to the edge of the cleaning blade, and the magnetic amorphous particles are deposited and held on the edges. An image forming method characterized in that residual spherical toner on a body surface is removed.
According to a tenth aspect of the present invention, in the image forming method according to the ninth aspect, the spherical toner has a circularity of 0.96 or more and a volume average particle diameter of 6 μm or less.

  In the image forming apparatus according to claim 1 and the image forming method according to claim 9, a cleaning blade containing magnet particles in a rubber elastic body (containing magnet particles in a dispersed state in the rubber elastic body). Is used to deposit the irregular particles having magnetism on the blade edge (hereinafter, the magnetic irregular particles may be referred to as irregular particles). In addition, it is possible to firmly deposit and hold an irregular particle layer, and even if a small-diameter spherical toner (for example, having a circularity of 0.96 or more and a volume average particle size of 6 μm or less) is stable. A cleaning blade (for example, a urethane blade) in which magnet particles are dispersed improves the wear resistance of the blade, and good cleaning performance is maintained for a long time. And over sustained, it can be formed over the quality good image in long term.

In the inventions of claims 2 and 10, since a spherical toner having a circularity of 0.96 or more and a volume average particle diameter of 6 μm or less is used, high developability and transferability of a visible image (toner image) can be obtained. In addition, a high-definition image is stably formed.
In the invention according to claim 3, since the circularity of the spherical toner is 0.98 or more and the volume average particle diameter is 5 μm or less, particularly high developability and transferability of a visible image can be obtained, and particularly high definition can be obtained. A stable image is formed stably.
In the invention according to claim 4, when the volume average particle size of the magnet particles dispersed in the cleaning blade is 5 μm or more and 50 μm or less, the amorphous particle layer can be deposited and held more firmly on the blade edge. And the magnet particles can be stably held on the rubber elastic body.
In the invention according to claim 5, the contact pressure is set to 0.20 N / cm or less, and the cleaning angle θ formed by the image carrier and the cleaning blade is set to 80 degrees or more, so that the toner removing function by the leaning blade is enhanced. In addition, damage to the surface of the image carrier due to the magnet particles in the blade can be suppressed. The meaning of the cleaning angle θ will be described later.
In the invention according to claim 6, the ratio (Df / Dt) satisfies the relationship of 1.3> (Df / Dt)> 0.01, thereby preventing the residual spherical toner from entering behind the edge of the cleaning blade. Increases effectiveness.
In the invention according to claim 7, when the ratio (Df / Dt) satisfies the relationship of 0.9> (Df / Dt)> 0.01, the residual spherical toner is prevented from penetrating behind the edge of the cleaning blade. The prevention effect is significantly increased.
In the invention according to claim 8, the developing device performs development by a two-component development method in which a carrier and a toner are mixed, and the content of particles having a weight average particle diameter Dw of less than 22 μm in the carrier is 3 wt% or less. As a result, the adhesion of the carrier to the edge of the cleaning blade is reduced, and as a result, damage to the surface caused by the carrier rubbing the surface of the image carrier can be suppressed.

  Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic view showing the main structure of the image forming apparatus. FIG. 2 is a schematic view showing the main structure of a magnetic amorphous particle supply device constituting the image forming apparatus. FIG. 3 is a schematic explanatory view of a blade edge portion constituting the blade cleaning device in the image forming apparatus of FIG. FIG. 4 relates to Comparative Example 2 to be described later, and is a schematic explanatory view showing a contact state of the cleaning blade to the photosensitive member.

First, the gist of the present invention will be described with reference to FIG.
The edge 31 a of the cleaning blade 31 containing the magnet particles 32 in the blade edge 31 a made of a rubber elastic body is brought into contact with the surface of the image carrier 8. Magnetic amorphous particles 33 are supplied to the edges to form the magnetic amorphous particle layer 33. Residual spherical toner on the surface of the image carrier, that is, small spherical toner 34 is dammed by the particle layer 33. As a result, even when a spherical toner having a circularity of 0.96 or more and a volume average particle size of 6 μm or less is used, the residual spherical toner can be prevented from entering behind the edge. As a result, high developability and transferability of a visible image (toner image) are obtained, and a high-definition image is stably formed.

  Next, referring to FIG. 1, the image carrier (photoconductor) 8 is uniformly charged by the charging device 1 and then irradiated with a laser beam (laser beam) 2a from the exposure device 2 to write a latent image. And an electrostatic latent image is formed on the surface of the image carrier 8. The image carrier 8 is an organic photoreceptor showing negative charging characteristics. The electrostatic latent image is developed into a toner image by a two-component developing type developing device 3. The developed toner image is transferred to a transfer material (transfer paper) 9 by a transfer device (transfer roller) 4, and then the toner image is fixed to the transfer paper 9 by a fixing device (fixing roller) 5. The transfer residual toner on the image carrier 8 is cleaned (removed) by a cleaning blade 31 (FIG. 3) provided in the blade cleaning device 7 and firmly holding irregular shaped particles on the blade edge. Note that the image forming apparatus of the present invention is not limited to the image forming apparatus shown in FIG.

  In FIG. 1, reference numeral 6 denotes a (magnetic) amorphous particle supply device for supplying amorphous particles having magnetism to the edge of the cleaning blade 31. The magnetic amorphous particles are supplied to the surface of the image carrier 8 and are conveyed to the cleaning blade 31 by the rotation of the image carrier 8, and in the vicinity of the edge 31 a (in FIG. 3, the edge tip surface facing the surface of the image carrier 8. By depositing on the lower portion, that is, on the toner scraping portion on the surface of the image carrier 8, the function of blocking the residual spherical toner 34 is achieved. The cleaning blade is constituted by dispersing and blending magnet particles in a rubber elastic body. Further, in FIG. 1, reference numeral 21 denotes a developing roller.

  As shown in FIG. 3, the cleaning blade 31 has magnet particles 32 dispersed in a molded product made of a rubber elastic body. Due to the magnetic field of the magnet particles 32 dispersed in the blade, the amorphous particles having magnetism can be held at the blade edge. In FIG. 3, reference numeral 33 indicates a magnetic amorphous particle layer that is an aggregate of magnetic amorphous particles 27. In addition, by dispersing magnet particles, irregularities can be formed on the blade surface, making it easier for amorphous particles to be caught on the blade surface, and holding a more rigid amorphous particle layer on the blade edge than holding the irregular particles by a magnetic field. It becomes possible.

  Due to such a strongly held magnetic amorphous particle layer, toner with a circularity of 0.96 or more and a volume average particle size of 6 μm or less does not enter the blade edge, and extremely good cleaning can be performed. It becomes possible. Further, since the magnetic field generating member and the cleaning blade member are integrated, it contributes to downsizing of the apparatus. In addition, as an effect of dispersing the magnet particles in the blade, the magnet particles serve as a reinforcing material, and the wear resistance of the blade is also improved. The improved wear resistance of the blade has enabled good cleaning characteristics not only in the initial stage but also for a long time. Therefore, there is provided an image forming apparatus capable of obtaining good cleaning performance for a small diameter spherical toner over a long period of time.

  In the present invention, the volume average particle diameter and circularity of the toner, and the volume average particle diameter of the magnet particles were measured using FPIA-2100 manufactured by Sysmex.

[About amorphous particles]
The magnetic amorphous particles of the present invention are ferromagnetic particles that are magnetized by an external magnetic field, and particularly if the particles are amorphous particles that can suppress the intrusion and consolidation of the developing toner into the minutely deformed portion of the blade edge. There is no limit. The magnetic particles themselves may be supplied, but since the magnetic particles may damage the surface of the image carrier (photoreceptor), it is preferable that the magnetic particles are dispersed in the resin. As the magnetic amorphous particles of the present invention, for example, magnetic toner particles produced by an ordinary pulverization method are suitable.

  When the magnetic amorphous particles are a magnetic toner produced by a pulverization method, the magnetic toner contains, for example, a thermoplastic resin as a binder resin as a main component, and includes magnetic powder, a charge control agent, a release agent, and the like. Magnetic powder used includes magnetic iron oxide particles such as magnetite and maghemite, spinel ferrite particles containing one or more metals other than iron (Mn, Ni, Zn, Mg, Cu, etc.), barium Magnetoplumbite type ferrite particle powder such as ferrite, fine particle powder of iron and its alloy having an oxide layer on the surface, and the like can be used. Moreover, nonmagnetic iron oxide particle powders such as hematite, goethite, and wustite can also be used, and in some cases, they can be used by mixing with the magnetic iron oxide particles. Preferred are magnetic iron oxide particles such as magnetite and maghematite, or nonmagnetic iron oxide particles such as hematite and goethite. The particle shape may be any of granular, spherical and acicular.

  Examples of the binder resin include styrene such as polystyrene and polyvinyltoluene, and homopolymers thereof, styrene-p-chlorostyrene copolymer, styrene-propylene copolymer, styrene-vinyltoluene copolymer, styrene-acrylic. Acid methyl copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate Copolymer, styrene-o-chloromethyl acrylate copolymer, styrene-acrylonitrile copolymer, styrene-vinyl methyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene- Isobutylene copolymer, styrene-male Styrene copolymers such as acid copolymers, styrene-maleic acid ester copolymers, polymethyl methacrylate, polybutyl methacrylate, polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene, polyester, polyurethane, epoxy resin, polyvinyl butyral Polyacrylic acid resin, rosin, modified rosin, terpene resin, phenol resin, aliphatic or aromatic hydrocarbon resin, aromatic petroleum resin, chlorinated paraffin, paraffin wax and the like can be used alone or in combination.

The polyester resin as a binder resin can be obtained by a polycondensation reaction between an alcohol and an acid.
Examples of the alcohol include diols such as polyethylene glycol, diethyl glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-propylene glycol, neopentyl glycol, and 1,4-butenediol. 1,4-bis (hydroxymethyl) cyclohexane, bisphenol A, hydrogenated bisphenol A, etherified bisphenols such as polyoxyethylenated bisphenol A, polyoxypropylenated bisphenol A, and the like. Divalent alcohol monomers substituted with unsaturated hydrocarbon groups, other divalent alcohol monomers, sorbitol, 1,2,3,6-hexanetetrol, 1,4-sarbitane, pentaerythritol, Zippe Taerythritol, tripentaerythritol, sucrose, 1,2,4-butanetriol, 1,2,5-pentanetriol, glycerol, 2-methylpropanetriol, 2-methyl-1,2,4-butanetriol, tri Mention may be made of trihydric or higher alcohol monomers such as methylolethane, trimethylolpropane and 1,3,5-trihydroxymethylbenzene.

  Examples of the carboxylic acid used to obtain the polyester resin include monocarboxylic acids such as palmitic acid, stearic acid, and oleic acid, maleic acid, fumaric acid, mesaconic acid, citraconic acid, terephthalic acid, cyclohexanedicarboxylic acid, and succinic acid. Acids, adipic acid, sebacic acid, malonic acid, divalent organic acid monomers in which these are substituted with a saturated or unsaturated hydrocarbon group having 3 to 22 carbon atoms, anhydrides of these acids, lower alkyl esters and Dimer from linolenic acid, 1,2,4-benzenetricarboxylic acid, 1,2,5-benzenetricarboxylic acid, 2,5,7-naphthalenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, 1, 2,4-butanetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,3-dicarboxylic acid-2-methyl Trivalent or higher polyvalent carboxylic acid monomers such as 2-methylenecarboxypropane, tetra (methylenecarboxyl) methane, 1,2,7,8-octanetetracarboxylic acid embol trimer, and anhydrides of these acids Can be mentioned.

  Further, examples of the epoxy resin include polycondensates of bisphenol A and epichlorohydrin. For example, Epomic R362, R364, R365, R366, R367, R369 (above, manufactured by Mitsui Petrochemical Co., Ltd.), Epototo YD-011, YD There are commercially available products such as -014, YD-904, YD-017 (above, manufactured by Tohto Kasei Co., Ltd.), Epocoat 1002, 1004, 1007 (above, manufactured by Shell Chemical Co., Ltd.).

  The magnetic amorphous particles of the present invention have no inconvenience even if they contain a drug to be contained for the purpose of controlling the triboelectric chargeability. As such so-called polarity control agents, for example, metal complexes of monoazo dyes, nitrohumic acid and its salts, metal complexes of salicylic acid, naphthoic acid, dicarboxylic acid such as Co, Cr, Fe, Zn, etc. may be used alone or in combination. However, it is not limited to these. The polarity control agent used in the color toner needs to be colorless, and a polymer-type polarity control material having polarity is preferably used.

  A fluidity modifier can be added to the magnetic toner used as the magnetic amorphous particles of the present invention. Examples of fluidity modifiers include organic resin fine particles, metal soaps, polytetrafluoroethylene fluororesins, lubricants such as zinc stearate, or abrasives such as acid value cerium and silicon carbide, generally fluidity modifiers Known metal oxides used for the above-mentioned purposes, typically metal oxide fine particles such as silicon oxide, titanium oxide, and aluminum oxide, and particles whose surfaces are hydrophobized. In any of these fine powders, hydrophobizing the surface brings about an excellent effect in terms of fluidity. In order to hydrophobize the surface, for example, a silicon compound generally known as a silane coupling agent or silylating agent can be brought into contact with and reacted with the particle surface.

Examples of the hydrophobizing agent include the following.
For example, chlorosilanes typically include trichlorosilane, methyldichlorosilane, dimethyldichlorosilane, trimethylchlorosilane, ethyldichlorosilane, diethylchlorosilane, triethylchlorosilane, propyldichlorosilane, dipropyldichlorosilane, tripropylchlorosilane and other alkylchlorosilanes, phenyl Such as chlorosilane. Fluoroalkyl chlorosilanes and perfluoroalkyl chlorosilanes as the fluoro-substituted product.
Typical examples of silylamines include hexamethyldisilazane, diethylaminotrimethylsilane, and diethylaminotrimethylsilane.
Typical examples of silylamides include N, O-bistrimethylsilylacetamide, N-trimethylsilylacetamide, bistrimethylsilyltrifluoroacetamide, and the like.
Further, as alkoxysilanes, methyltrialkoxysilane, dimethyldialkoxysilane, trimethylalkoxysilane, ethyldialkoxysilane, diethylalkoxysilane, triethylalkoxysilane, propyltrialkoxysilane, dipropylalkoxysilane, tripropylalkoxysilane, etc. Alkylchlorosilane and phenylalkoxysilane having a phenyl group.
In addition, fluoroalkyl alkoxysilanes, perfluoroalkylalkoxysilanes as fluorine-substituted products, dimethylsilicone oil and derivatives thereof as silicone oils, fluorine-substituted products, siloxanes such as disiloxane, hexamethyldisiloxane, etc. A compound that can be used as a generally known hydrophobizing agent can be used.

  Regarding the particle diameter Df of the irregular shaped particles, the ratio (Df / Dt) to the average particle diameter Dt of the spherical toner is preferably smaller than 1.3, and more preferably smaller than 0.9. If Df / Dt is too large, the gap between the irregular shaped particles deposited on the blade edge becomes large, and the spherical toner tends to enter. The lower limit of Df / Dt is preferably larger than 0.01. If it is less than 0.01, the irregularly shaped particles are small, and the blade edge may slip through.

[Feeding device for magnetic amorphous particles]
The supply device for magnetic amorphous particles used in the present invention is not particularly limited as long as the magnetic amorphous particles are deposited at the blade edge. For example, when a magnetic toner produced by a pulverization method is used as the magnetic amorphous particles, the image carrier can be developed and supplied by a developing device storing the magnetic toner (FIG. 1).
Further, in an image forming apparatus provided with an intermediate transfer member, development may be performed on the intermediate transfer member, and magnetic amorphous particles may be supplied to the image carrier via the intermediate transfer member and deposited on the blade edge.

[About cleaning blade]
In the cleaning blade of the present invention, at least magnet particles are blended in a rubber elastic body, more preferably in a dispersed state. Conventionally known magnet materials can be used as the material of the magnet particles.
For example, ferrite magnets such as Ba ferrite and Sr ferrite, rare earth magnets such as Nd-Fe-B magnets and Sm-C magnets, MK steel (Fe-Ni-Al alloys), alnico magnets (Fe-Co) -Ni-Al-Cu alloy) and the like, but an expensive metal element is not included, and a low-cost ferrite magnet is desirable.
The particle shape of the magnet particles is preferably granular or spherical, and the volume average particle size is preferably 5 μm or more and 50 μm or less. When the volume average particle size is less than 5 μm, the magnetic amorphous particles may not be sufficiently retained. When the volume average particle size is greater than 50 μm, the particles are easily detached from the rubber elastic body, and the surface of the photoreceptor is easily damaged.
The content of the magnet particles is desirably 10 wt% or more and 70 wt% or less. If it is less than 10 wt%, the magnetic amorphous particles may not be sufficiently retained, and if it exceeds 70 wt%, the magnet particles may be easily detached and the rubber elasticity of the blade may be lost.

  As the rubber elastic body of the cleaning blade, conventionally known materials (synthetic rubber, natural rubber, thermoplastic elastomer, etc.) can be used, and polyurethane rubber is preferred. Polyurethane rubber usually uses a polyethylene adipate ester or polycaprolactone ester as a polyol component, and a prepolymer is prepared using 4,4′-diphenylmethane diisocyanate as a polyisocyanate component. It is manufactured by adding a catalyst, crosslinking in a predetermined mold, post-crosslinking in a furnace, and then aging at room temperature.

  As the high molecular weight polyol, for example, a polyester polyol which is a condensate of an alkylene glycol and an aliphatic dibasic acid, for example, ethylene adipate ester polyol, butylene adipate ester polyol, hexylene adipate ester polyol, ethylene propylene adipate ester polyol, ethylene Polyester polyols such as butylene adipate ester polyol, polyester glycols of alkylene glycol and adipic acid such as ethylene neopentylene adipate ester polyol, polycaprolactone polyols such as polycaprolactone ester polyol obtained by ring-opening polymerization of caprolactone, Poly (oxy (tetramethylene) glycol, poly (oxypropylene) glycol, etc. Ether-based polyols, or the like is used.

  Other low molecular weight polyols include, for example, 1,4-butanediol, ethylene glycol, neopentyl glycol, hydroquinone-bis (2-hydroxyethyl) ether, 3,3′-dichloro-4,4′-diaminodiphenyl. Dihydric alcohols such as methane, 4,4'-diaminodiphenylmethane, 1,1,1-trimethylolpropane, glycerin, 1,2,6-hexanetriol, 1,2,4-butanetriol, trimethylol Mention may be made of trihydric and higher polyhydric alcohols such as ethane, 1,1,1-tris (hydroxyethoxymethyl) propane, diglycerin, pentaerythritol.

  Specific examples of the curing catalyst include 2-methylimidazole and 1,2-dimethylimidazole, and 1,2-dimethylimidazole is particularly preferably used. Such a catalyst is usually used in an amount of 0.01 to 0.5 parts by weight, more preferably 0.05 to 0.3 parts by weight, based on 100 parts by weight of the main agent.

A conventionally known method can also be adopted as a method for producing the cleaning blade, and at least magnet particles may be dispersed in the prepolymer before molding. For example, the cleaning blade used in the present invention can be obtained as follows. Urethane elastomer is mainly obtained by adding a small amount of antifoaming agent to the prepolymer and curing agent as the main components, mixing it uniformly, putting it in a mold and curing it by heating, but the magnet particles were heated and melted. A cleaning blade containing desired magnet particles can be obtained by dispersing in a prepolymer or by dispersing in a liquid curing agent having a relatively low molecular weight at room temperature. The magnet particles may be surface-treated with a silane coupling agent or the like in advance as necessary in order to improve the dispersibility and the adhesion to the rubber-like elastic material for the cleaning blade.
The obtained blade is finally magnetized to magnetize the magnet particles. Further, a desired cleaning blade is obtained by bonding the blade to the support member.

  Regarding the contact condition of the cleaning blade, the contact pressure of the cleaning blade to the image carrier is 0.20 N / cm or less, and the cleaning angle θ formed by the image carrier (photoreceptor) and the cleaning blade (FIG. 3). ) Is preferably 80 degrees or more. Since the blade contains magnet particles, if the cleaning angle θ is less than 80, the surface of the photoconductor may be scratched. By using the above contact conditions, the surface of the photoconductor can be prevented from being scratched. . The contact pressure shown here is a value (linear pressure) obtained by dividing the load applied to the photosensitive member by the length of the blade in the longitudinal direction of the photosensitive member (dimension in the axial direction of the photosensitive member). The load applied to the photoreceptor was measured by a pressure distribution measurement system I-SCAN (manufactured by Nitta Corporation). In addition, the cleaning angle θ referred to here is an angle formed by the tangent L at the contact point between the cleaning blade 31 and the surface of the photosensitive member 8 and the cut surface 31b of the cleaning blade 31, as shown in FIG. The cleaning angle θ was measured by taking a photograph of the blade contact portion with the surface of the photoreceptor 8.

[About toner]
The latent image developing toner used in the present invention preferably has a particle circularity of 0.96 or more and a volume average particle size of 6 μm or less, but is not limited thereto. By using such a toner, dot reproducibility and transferability are improved, and a good image can be obtained. The toner preferably has a volume average particle size of 5 μm or less and a circularity of 0.98 or more, and dot reproducibility and transferability are particularly improved.

  As an example of this toner, at least a resin material for a binder and / or a prepolymer thereof, a colorant, and a release agent are dispersed in the form of fine droplets in an organic solvent liquid of a toner material containing an organic solvent or an aqueous medium. Then, after the organic polymer and the aqueous medium are removed and / or after the prepolymer in the droplets is cross-linked and / or extended during or after the dispersion, It can be produced by removing the organic solvent and the aqueous medium.

Preferably, at least in an organic solvent, a compound having active hydrogen and a polymer having a site capable of reacting with the compound, or a self-polymerizable material having active hydrogen and a site capable of reacting with it in the molecule at the same time The organic solvent and the aqueous system are dissolved or dispersed, preferably in the form of a composition containing them, after reacting with or reacting with the active hydrogen reactive site. The medium can be removed, washed and dried. The circularity of the toner may be adjusted by adjusting the stirring strength during the reaction or by forced stirring after drying. As the resin material and / or its prepolymer, various materials can be used, and in particular, a polyester resin and / or a polyester prepolymer can be preferably used.
These are merely examples, and the spherical toner may of course be manufactured by a method other than such a manufacturing method.

  In the development process in the image forming apparatus according to the present invention, either a one-component development method or a two-component development method can be used. In the case of a high-speed image forming process, the two-component development method is preferable. In the case of the two-component development method, it is preferable that the carrier used has a weight average particle diameter Dw of 22 μm or less and 3 wt% or less. Since the carrier is also a ferromagnetic material, when the carrier adheres to the photoconductor, the carrier is also held at the blade edge portion, and the surface of the photoconductor is damaged. Since there are many particles that tend to cause carrier adhesion with a small particle size and a small magnetic moment, controlling the particle size distribution of the fine powder as described above suppresses carrier adhesion and prevents scratches on the photoreceptor. Is done.

The weight average particle diameter Dw referred to for the carrier in the present invention is calculated based on the particle diameter distribution (relationship between the number frequency and the particle diameter) of the particles measured on the basis of the number.
The weight average particle diameter Dw in this case is represented by the following formula (1).
Dw = {1 / Σ (nD3)} × {Σ (nD4)} (1)
In the formula (1), D represents a representative particle size (μm) of particles present in each channel, and n represents the total number of particles present in each channel. The channel indicates a length for equally dividing the particle size range in the particle size distribution diagram. In the present invention, a length of 2 μm is adopted. Further, as the representative particle size of the particles existing in each channel, the lower limit value of the particle size stored in each channel was adopted.

As a particle size analyzer for measuring the particle size distribution of the carrier, a Microtrac particle size analyzer (model HRA9320-X100: manufactured by Honeywell) having the following specifications was used.
(1) Particle size range: 100-8 μm
(2) Channel length (channel width): 2 μm
(3) Number of channels: 46

[Image forming apparatus and image forming method]
Since the structure of the main part of the image forming apparatus and the image forming process using the structure are as already described with reference to FIG. 1, the magnetic indefinite form constituting the image forming apparatus is based on FIG. 2 here. The main structure of the particle supply device and its operation will be described.

  The magnetic amorphous particle supply device 6 is a one-component developing device filled with magnetically pulverized toner as amorphous particles. In FIG. 2, the magnetic amorphous particle supply device 6 supplies a magnetic pulverized toner, which is magnetic amorphous particles 27, to the image carrier 8 (FIG. 1), and develops the magnetic roller. The supply roller 22 for supplying the pulverized toner 27, the magnetic pulverized toner conveying material 23 for conveying the magnetic pulverized toner 27 toward the supply roller 22, and the magnetic pulverized toner 27 supplied onto the developing roller 21 are thinned. A magnetic pulverization toner regulating roller 24, a metal spring 26 for urging the toner regulating roller 24 toward the developing roller 21, and a case 25 for housing these components are provided.

  In the magnetic amorphous particle supply device 6, the magnetic pulverized toner 27 is supplied to the surface of the developing roller 21 via the toner conveying material 23 and the replenishing roller 22. The magnetic pulverized toner 27 supplied onto the developing roller 21 is further thinned to a predetermined amount by the contact pressure of the toner regulating roller 24. By rotating the developing roller 21, the photosensitive member as the image carrier 8 is formed. Be transported. The developing roller 21 is disposed in contact with the photoconductor 8 so that the axis is parallel to that of the photoconductor 8. A bias approximately halfway between the charging potential of the photosensitive member and the residual potential after optical writing by laser light irradiation is applied to the developing roller 21. The magnetic pulverized toner 27 on the developing roller 21 comes into contact with the photosensitive member, and the magnetic pulverized toner 27 is supplied to the photosensitive member by a developing electric field generated by the photosensitive member potential and the developing bias. The magnetic amorphous particle supply device 6 can move forward and backward with respect to the photosensitive member by a moving mechanism (not shown). The magnetic amorphous particle supplying device 6 advances only when the irregular particle is supplied, and the developing roller 21 contacts the photosensitive member 8. The irregularly shaped particles are supplied, and the developing roller 21 is not in contact with the photosensitive member 8 in normal times.

When the magnetically pulverized toner (amorphous particles) 27 has a negative charging polarity, the photosensitive member is irradiated with laser light and the irregular particles are supplied to the photosensitive member. If the magnetically pulverized toner 27 has a positive charging polarity, the irregularly shaped particles are supplied to the charged potential portion without writing by laser light irradiation.
The irregularly shaped particles supplied from the irregularly shaped particle supply device 6 to the photoreceptor 8 are deposited on the cleaning blade edge 31a of the blade cleaning device 7 on the downstream side by the rotation of the photoreceptor. FIG. 3 schematically shows a blade edge portion of the blade cleaning device 7. That is, FIG. 3 is a diagram schematically showing a state in which the cleaning blade 31 in which the magnet particles 32 are dispersed is in contact with the surface of the photoconductor 8, and the magnetic amorphous particle layer 33 is deposited on the blade edge 31 a. The magnetic amorphous particle layer 33 is firmly held by the magnetic field of the magnet particles 32 dispersed in the blade and the unevenness of the blade surface formed by dispersing the magnet particles 32. The magnetic amorphous particle layer 33 prevents the small spherical toner 34 from entering behind the blade edge. The supply operation of the irregular shaped particles is controlled by a controller (not shown) so that it can be supplied at a desired timing.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated further more concretely, this invention is not limited to the following Example, unless it deviates from the meaning.

[Example 1]
Using the image forming apparatus shown in FIG. 1, the cleaning performance and image quality of the cleaning blade were evaluated under the following conditions.
The cleaning blade was prepared by preparing a urethane rubber blade having a thickness of 2 mm in which 15 wt% of Ba ferrite magnet particles having a volume average particle diameter of 3 μm were dispersed in the blade, performing magnetization, and adhering to a sheet metal support. Is. The cleaning blade contact conditions were a cleaning angle θ of 78 degrees and a contact pressure of 0.22 N / cm. Magnetic pulverized toner having an average volume particle size of 9 μm was used as the magnetic amorphous particles. This was filled and stored in a magnetic amorphous particle supply device which is a one-component developing device. In developing with toner, a developing device using a two-component developing method was used.
As this toner, a spherical toner having an average circularity of 0.97 and a volume average particle diameter of 5.8 μm prepared by a polymerization method was used. As the carrier, a Cu-Zn ferrite core material coated with silicone and having a weight average particle diameter of 40 μm and a carrier of 22 μm or less being 4.5 wt% or less was used. In the developing device, a developer prepared by mixing these toner and carrier in a ratio of 7 parts by weight to 93 parts by weight was used. In this case, the toner was negatively charged.

〔Evaluation methods〕
After the amorphous particles were supplied to the blade edge from the amorphous particle supply device, the running of printing the image of the S-5 chart was performed. The number of printed sheets was 250K, and the cleaning performance and image quality were evaluated at the initial stage of 10K, 100K, and 250K sheets.
[Cleaning property evaluation]
The rank evaluation of the cleaning property was performed by a five-step evaluation. Rank 5 is the best and rank 1 is poor. The acceptable level that can withstand actual use is rank 3 or higher.
[Image quality evaluation]
As an image quality evaluation, a half-level unevenness, resolution, sharpness, etc. were comprehensively evaluated, and a 5-level rank evaluation was performed. Rank 5 is the best and rank 1 is bad.
[Blade wear amount]
Regarding edge wear of the cleaning blade, the blade edge was observed with a laser microscope (manufactured by Keyence, VK9500), and the wear width was calculated from the profile.
[Photoconductor scratches]
The presence / absence of scratches on the photoreceptor was determined based on visual observation and observation results with a laser microscope (manufactured by Keyence, VK9500), and evaluated for ranking. As in the case of a new article, a rank of 5 was assigned, with a case where there was no scratch at all being ranked 5 and a case where many scratches were bad, and rank 1 was assigned.

[Example 2]
In Example 1 described above, the magnet particles dispersed in the cleaning blade were changed to Ba ferrite having a volume average particle size of 5 μm. The blade contact conditions were evaluated in the same manner as in Example 1 except that the cleaning angle θ was 80 degrees and the contact pressure was 0.19 N / cm.

[Example 3]
In Example 1 described above, the magnet particles dispersed in the cleaning blade were changed to Ba ferrite having a volume average particle size of 10 μm, and the blade contact conditions were such that the cleaning angle θ was 80 degrees and the contact pressure was 0.19 N / cm. Evaluation was performed in the same manner as in Example 1 except that

[Example 4]
In Example 1 described above, the magnet particles dispersed in the cleaning blade were changed to Sr ferrite having a volume average particle size of 30 μm, and the blade contact conditions were such that the cleaning angle θ was 80 degrees and the contact pressure was 0.19 N / cm. Evaluations were made in exactly the same manner as in Example 1 except that.

[Example 5]
Example 3 is exactly the same as Example 3 except that the volume-average particle size of the magnetic amorphous particles used (magnetic toner prepared by the pulverization method) was 6.8 μm and Df / Dt was changed to 1.2. Evaluation was performed in the same manner.

[Example 6]
Example 3 is the same as Example 3 except that the volume-average particle size of the magnetic amorphous particles used (magnetic toner prepared by the pulverization method) is 4.5 μm and Df / Dt is changed to 0.8. Evaluation was performed in the same manner.

[Example 7]
In Example 6 above, the toner used was changed to a toner with an average circularity of 0.98 and a volume average particle size of 4.8 μm, and the volume average particle size of the magnetic amorphous particles used (magnetic toner prepared by the pulverization method) was used. Evaluation was made in the same manner as in Example 6 except that the thickness was set to 4 μm.

[Example 8]
In Example 7, evaluation was performed in the same manner as in Example 7 except that a carrier having a weight average particle diameter of 42 μm and particles having a particle size of 22 μm or less was 2.5 wt% was used.

[Comparative Example 1]
Except for using a urethane rubber blade that does not disperse magnet particles as a cleaning blade in Example 1 above, removing the magnetic amorphous particle supply device, and supplying no magnetic amorphous particles, the same as Example 1. Was evaluated.
However, since the cleaning performance was poor from the beginning of the running (image forming process), the subsequent running was stopped.

[Comparative Example 2]
Evaluation was performed in exactly the same manner as in Example 1 except that the blade edge portion in Example 1 was changed to a cleaning blade to which a Ba ferrite magnet was attached. FIG. 4 schematically shows the contact state of the used cleaning blade with the photosensitive member. A bar-shaped Ba ferrite magnet 42 is attached to the edge portion of the urethane rubber blade 41 in the blade longitudinal direction. Reference numeral 43 denotes a magnetic amorphous particle layer, and reference numeral 44 denotes toner to be cleaned.
In Comparative Example 2, the evaluation was stopped halfway because the cleaning failure was severe at the end of 100K and the blade was worn and chipped severely.

  The test conditions are summarized in Table 1 below, and the test results are summarized in Table 2 below.

1 is a schematic configuration diagram illustrating an example of an image forming apparatus of the present invention. It is the schematic which shows the principal part structure of the magnetic amorphous particle | grain supply apparatus arrange | positioned at the image forming apparatus of FIG. FIG. 2 is a schematic explanatory diagram of a blade edge portion constituting a blade cleaning device provided in the image forming apparatus of FIG. 1. FIG. 10 is a schematic explanatory diagram illustrating a contact state of the cleaning blade with respect to the photosensitive member according to the comparative example 2.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Charging device 2 Exposure device 2a Laser beam 3 Developing device (of two component development system) 4 Transfer device (transfer roller)
5 Fixing Device 6 (Magnetic) Amorphous Particle Supply Device 7 Blade Cleaning Device 8 Image Carrier (Photoconductor)
DESCRIPTION OF SYMBOLS 9 Transfer material 21 Developing roller 22 Replenishment roller 23 Magnetic grinding toner conveyance material 24 Magnetic grinding toner control roller 25 Case 26 Metal spring 27 Magnetic amorphous particle (magnetic grinding toner)
31 Cleaning blade 31a Edge 31b Cut surface 32 Magnet particle 33 Magnetic amorphous particle layer 34 Small spherical toner 41 Urethane rubber blade
(Cleaning blade)
41a edge 42 Ba ferrite magnet 43 magnetic amorphous particle layer 44 toner

Claims (10)

A developing device that develops a latent image on the image carrier with a spherical toner, a transfer device that transfers a developed image formed on the image carrier by development to a transfer material, and a cleaning blade made of a rubber elastic body. In an image forming apparatus comprising at least a cleaning device that removes spherical toner remaining on the surface of an image carrier after transferring a visible image by contacting the surface,
A magnetic amorphous particle supply device for supplying irregular particles having magnetism for damming up the residual spherical toner by depositing on the edge of the cleaning blade is provided, and the cleaning blade includes magnet particles in a rubber elastic body. An image forming apparatus containing the image forming apparatus.   2. The image forming apparatus according to claim 1, wherein the spherical toner has a circularity of 0.96 or more and a volume average particle diameter of 6 μm or less.   The image forming apparatus according to claim 2, wherein the spherical toner has a circularity of 0.98 or more and a volume average particle diameter of 5 μm or less.   The image forming apparatus according to claim 1, wherein magnet particles are dispersed and blended in a cleaning blade, and the volume average particle diameter of the magnet particles is 5 μm or more and 50 μm or less. apparatus.   5. The image forming apparatus according to claim 1, wherein a contact pressure of the cleaning blade to the image carrier is 0.20 N / cm or less, and a cleaning angle θ formed by the image carrier and the cleaning blade is 80. An image forming apparatus characterized in that the image forming apparatus has a degree equal to or higher than that.   6. The image forming apparatus according to claim 1, wherein the ratio (Df / Dt) of the volume average particle diameter Df of the amorphous particles having magnetism to the volume average particle diameter Dt of the spherical toner for developing the latent image. Satisfies the relationship of 1.3> (Df / Dt)> 0.01.   6. The image forming apparatus according to claim 1, wherein the ratio (Df / Dt) of the volume average particle diameter Df of the amorphous particles having magnetism to the volume average particle diameter Dt of the spherical toner for developing the latent image. Satisfies the relationship of 0.9> (Df / Dt)> 0.01.   8. The image forming apparatus according to claim 1, wherein the developing device performs development by a two-component developing method using a developer formed by mixing a carrier and a spherical toner, and the carrier has a weight. An image forming apparatus, wherein the content ratio of particles having an average particle diameter Dw of less than 22 μm is 3 wt% or less. The latent image on the image carrier is developed with a spherical toner to form a visible image, the visible image is transferred to a transfer material, and a cleaning blade made of a rubber elastic body is brought into contact with the surface of the image carrier to thereby develop a visible image. In an image forming method having at least a step of removing spherical toner remaining on the surface of an image carrier after image transfer,
An image bearing member using a cleaning blade containing magnet particles in a rubber elastic body, supplying irregular particles having magnetism to the edge of the cleaning blade, and depositing the magnetic irregular particles on the edge An image forming method comprising removing residual spherical toner on the surface. 10. The image forming method according to claim 9, wherein the spherical toner has a circularity of 0.96 or more and a volume average particle diameter of 6 μm or less.

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