JP2001056597A - Magnetic particles for electrification, electrifying member, electrifying device, image forming device and process cartridge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain magnetic particles for electrification capable of preventing the scattering of a toner, the scraping of a photoreceptor and the change of the color and appearance of the toner and excellent in electrifying cap ability and durability by coating the surface of each of magnetic particles with a coating layer containing a nitrogen-containing material. SOLUTION: The magnetic particles for electrification electrify an image support on which an electrostatic latent image is formed when rubbed on the image support and have magnetic particles and a coating layer which coats the surface of each of the magnetic particles. The coating layer contains a nitrogen-containing material. The electrifying device 10 has a power source 16 which applies electrification bias from an electrode sleeve 12 by way of a junction 14. Electrification is carried out by applying voltage to the electrode sleeve 12. A magnetic brush formed by the magnetic particles 13 for electrification is kept in contact with the image support by way of the rotatable electrode sleeve 12 and electrifies the image support when rubbed on the image support under counter rotation or forward rotation with an arbitrary difference in peripheral speed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charging particle for charging an image carrier used in a recording method utilizing electrophotography applied to a copying machine, a printer, a facsimile, etc. The present invention relates to a charging member, a charging device using the charging member, an image forming apparatus, and a process cartridge.

[0002]

2. Description of the Related Art A charging device used in an image forming apparatus has conventionally used a method utilizing corona discharge. However, since a large amount of ozone is generated, it is necessary to provide a filter. There have been problems in miniaturization and increase in running cost.

In order to solve such a problem, a contact charging device has been developed in which a roller-shaped charging member (charging roller) is brought into contact with the surface of a photoreceptor to perform charging. This is a method of charging the photoconductor by performing a discharge that can be interpreted according to Paschen's law in an extremely narrow space formed near the contact point between the charging roller and the photoconductor, thereby minimizing the generation of ozone. The effect of supporting is recognized.

[0004] Since this contact charging is performed by discharging from the charging roller to the photosensitive member, charging is started by applying a voltage higher than a certain threshold voltage between the charging roller and the photosensitive member. Generally, when a voltage higher than the threshold value is applied, the photoconductor surface potential linearly increases with a slope of 1 with respect to the applied voltage. Thus, if this threshold voltage is defined as the charging start voltage Vth, it is necessary to apply a DC voltage of Vd + Vth to the charging roller in order to obtain the photoconductor surface potential Vd. In such a charging method using a DC voltage, when the environment changes, the resistance value of the charging roller changes, so that the potential of the photoconductor may fluctuate.

On the other hand, in order to make the charged state uniform, as disclosed in JP-A-63-149669, a DC voltage corresponding to a desired Vd has a peak-to-peak voltage of 2 × Vth or more. A charging method in which a voltage on which a voltage is superimposed is applied to a charging roller is used. This is for the purpose of averaging the surface potential by an alternating current, and since the surface potential of the photoconductor converges to Vd which is the median of the peaks of the AC voltage, it is hardly affected by disturbances such as the environment. There is.

[0006] However, since the charging roller is made of a solid material such as rubber, vibration is generated at the contact portion with the photoreceptor due to the electric field of the applied AC voltage. Charging noise) may be a problem.

Further, fine particles such as toner and paper powder may adhere to the surface of the charging roller which comes into contact with the photoreceptor. In such a case, the charging becomes partially non-uniform, and a fog image is formed. Sometimes it occurred.

For this reason, a technique of using a magnetic brush, which has a relatively small contact load on the photoreceptor and has magnetic particles held by a magnet body, as a charging member has been studied. As a charging method using such magnetic particles, two methods have been proposed in combination with a photoconductor. One is a method in which a charge injection layer is provided on the photoreceptor surface layer, and magnetic particles are brought into contact with the charge injection layer, whereby charges are directly injected into the charge injection layer to charge the photoreceptor. The other is a method using an ordinary photoreceptor and utilizing discharge in a minute gap between the magnetic particles and the photoreceptor surface.

As a method of using the above-mentioned magnetic particles as the above-mentioned charging member (magnetic brush), Japanese Patent Laid-Open No. 59-1335 discloses a method.
No. 69 discloses a method in which particles coated with iron powder are held on a magnet roll and charged by applying a voltage. However, as a problem left in such a technique, there is a problem that it is difficult to obtain stable charging properties during continuous use.

In order to solve such a problem, for example, as disclosed in JP-A-6-301265,
By replenishing a certain amount of toner into the magnetic brush,
A configuration for stabilizing the resistance of the magnetic brush has been proposed. However, since all of the various methods of charging using magnetic particles as described above utilize a discharge phenomenon in a minute gap, the surface of the photoreceptor may be damaged and deteriorated by a product generated by the discharge. However, there still remains a problem that image flow easily occurs under high temperature and high humidity.

Furthermore, in JP-A 6-258918 discloses a is 10 ⁸ to 10 ^{1 0} [Omega] cm volume resistivity, and particle sizes of 30~100μm particles, a volume resistivity of 10
It is disclosed that charging particles are mixed with particles having a particle size of ⁸ Ωcm or less and a particle size of 30 to 100 μm. Also, in JP-A-6-274005,
Particles having a volume resistivity of 5 × 10 ⁵ Ωcm or more and 5 × 10 ⁴ Ω
It is disclosed that particles obtained by mixing particles having a particle size of not more than 1 cm are used as charging particles. As described above, a method has been proposed in which the conductivity and particle size of the particles are used in combination.

[0012] These exhibit good charging properties depending on the particle size and resistance of the particles to be mixed. However, if the particle size of the mixed particles is relatively uniform and the resistance value varies, during use,
Since particles having low resistance gather on the surface of the photoreceptor, there is a tendency that pinhole leakage occurs during use, even if the pinhole has good pinhole resistance in the initial stage. In addition, when the non-uniformity of the particle size is large, the tendency to separate particles having low resistance can be suppressed. However, there is a problem that particles having low resistance are particularly likely to leak in a low humidity environment.

Furthermore, Japanese Patent Application Laid-Open No. 8-6355 discloses a method in which magnetic particles having a smooth surface and magnetic particles having an uneven surface are mixed to form charged particles. Here, the effect of increasing the durability is described, but further improvement of the durability is desired.

Although various proposals have been made as described above, in the sense of practical use, as far as the present inventor can know, a magnetic brush is used as a photosensitive member charging member in an electrophotographic apparatus such as a copying machine on the market. There are no examples.

It is disclosed that magnetic particles obtained by kneading and pulverizing magnetite and a resin are used as the magnetic particles for charging. However, since the magnetic particles contain a large amount of a resin component, the magnetic particles tend to leak from the charging member. Since such resin magnetic particles have a high resin content on the surface and a low magnetic particle content ratio as a conductive path, resistance tends to increase due to surface contamination, and it is difficult to improve durability.

In an image forming apparatus including a charging device, an image carrier, an exposure device, a developing device, a transfer device, a fixing device, and the like, a cleaning member such as a blade or a brush is pressed against the photosensitive member as the image carrier. A cleaning device such as a blade type or a brush type is used in which the residual toner is applied to the toner container to scrape it and scrape it into a waste toner container to collect it.

The cleaning device is excellent in collecting residual toner after transfer because the cleaning member is brought into direct contact with the photoreceptor. However, the cleaning device requires processing of waste toner, and the cleaning device requires a cleaning container. It has been pointed out that the size of the device becomes large, and the life of the device is shortened due to wear of the photoreceptor.

Therefore, a simultaneous development cleaning system (or cleaner-less system) has been proposed as a system without waste toner. In this method, the transfer residual toner remaining on the photoreceptor after the transfer step is passed through the charging step again, and the transfer residual toner is collected in a developing device using a potential difference between the charged photoreceptor and the developing unit. . This method eliminates the need to dispose of toner. This method enables effective use of consumables by reusing toner, responds to ecology, prolongs life by preventing wear of photoconductors,
This is an effective means from the viewpoint of reducing the size of the image forming apparatus.

Japanese Patent Application Laid-Open No. 59-133573 discloses a conventional technique relating to simultaneous cleaning or cleanerless development.
JP-A-62-203182, JP-A-63-13317
9, JP-A-64-20587, JP-A-2-51168,
JP-A-2-302772, JP-A-5-2287, JP-A-5-2289, JP-A-5-53482, JP-A-5-61
383 etc. All of these known techniques use a corona discharge, a brush, a roller, or the like as a charging member, and have problems such as contamination of the photoreceptor surface due to discharge products and non-uniform charging, and satisfy all conditions. I have not been able to.

For this reason, a cleaner-less technique using a so-called magnetic brush as a charging member in which magnetic particles having a relatively small contact load on the photoreceptor are held by a magnet is being studied. For example, Japanese Patent Laid-Open Publication No. Hei 4-21873 proposes an image forming apparatus which does not require a cleaning device using a magnetic brush to which an AC voltage having a peak value exceeding a discharge limit value is applied. Further, Japanese Patent Application Laid-Open No. Hei 6-118855 proposes an image forming apparatus equipped with a magnetic brush charging cleaning device without an independent cleaning device. Examples of magnetic particles used include iron, chromium, nickel, and cobalt. Such as metals or alloys or compounds thereof, triiron tetroxide, γ-ferric oxide, chromium dioxide, manganese oxide, ferrite, manganese-copper alloys and styrene resins, vinyl resins, ethylene resins, Rosin modified resin, acrylic resin, polyamide resin, epoxy resin,
Disclosed are those coated with a polyester resin, particles obtained from a resin containing magnetic fine particles dispersed therein, and the like. However, the preferred form of the magnetic particles for charging is not disclosed, and a technical problem remains from the viewpoint of providing magnetic particles suitable for a charging member.

As described above, with respect to the magnetic particles as the charging member, a structure suitable for achieving uniform charging is desired. Further, in an image forming apparatus equipped with a charging member, it has been recognized that toner, a free external additive, or a foreign substance such as paper dust enters the charging member at the time of image formation. Scattering and lowering of chargeability due to durability occur. The toner scattering is a phenomenon in which the toner once mixed in the charging member scatters around the charging member. However, the incorporation of foreign matter such as toner into the charging member causes not only scattering of the toner, but also a decrease in contact with the photosensitive member and an increase in the resistance of the charging member. become. Therefore, even in a cleanerless image forming apparatus, a charging member capable of preventing toner scattering and lowering of charging property is required, and a charging apparatus having uniform charging over a long period of time and excellent durability has been demanded. Devices and process cartridges are desired.

[0022]

DISCLOSURE OF THE INVENTION The present invention has been made from the above viewpoint, and is capable of preventing toner scattering, photoreceptor scraping, and change in color appearance of toner, and has excellent chargeability and durability. It is an object to provide a magnetic particle, a charging member carrying the same, and a charging device. Another object of the present invention is to provide an image forming apparatus capable of achieving high image quality by mounting the charging device, and a process cartridge capable of easily performing image formation.

[0023]

Means for Solving the Problems In order to solve the above-mentioned problems, the present inventor has made the following magnetic particles for charging.
That is, the first aspect of the magnetic particles for charging of the present invention is:
In the magnetic particles for charging which charges the image carrier by being rubbed on the image carrier on which an electrostatic latent image is formed, the magnetic particles for charging cover the magnetic particles and the surface of the magnetic particles A coating layer, wherein the coating layer contains a nitrogen-containing material.

When the charging magnetic particles have the above-described structure, frictional charging properties with respect to the toner are imparted to the charging magnetic particles, so that scattering of the toner and reduction in the charging property can be prevented. The amount of triboelectric charging of the magnetic particles for charging of the present invention with respect to powder such as toner is preferably in the range of -15 to -50 mC / kg in an environment at a temperature of 23 ° C and a humidity of 60%.

When the magnetic particles for charging according to the first aspect are used, it is preferable that the coating layer contains at least two or more materials including the nitrogen-containing material. further,
The nitrogen-containing material is preferably a material having an amino group.

The material containing an amino group is titanium,
It is preferable that the coupling agent has a metal selected from silicon, aluminum and zirconium as a central metal.

A second aspect of the magnetic particles for charging according to the present invention is directed to a magnetic particle for charging which charges an image carrier by being rubbed on the image carrier on which an electrostatic latent image is formed. Wherein the magnetic particles for charging have magnetic particles, a first coat layer covering the surface of the magnetic particles, and a second coat layer covering the surface of the first coat layer. It is characterized by containing a nitrogen-containing material.

When the charging magnetic particles of the second embodiment are used, the nitrogen-containing material is preferably a material containing an amino group. Preferably, the cure temperature of the first coat layer is higher than the cure temperature of the second coat layer. The nitrogen-containing material containing an amino group is preferably a coupling agent having a metal selected from titanium, silicon, aluminum and zirconium as a central metal.

In the magnetic particles for charging according to the second aspect, the first coat layer preferably contains an alkyl chain having 6 or more carbon atoms. At this time, the compound having an alkyl chain having 6 or more carbon atoms is titanium, silicon,
Preferably, the coupling agent is a coupling agent containing a metal selected from aluminum and zirconium as a central metal.

In the magnetic particles for charging according to each of the above embodiments, the maximum chord length of the magnetic particles for charging is 5 μm to 20 μm.
The standard deviation of the ratio of the minor axis length to the major axis length (minor axis length / major axis length) is 0.0 μm.
It is preferably 8 or more.

The charging member of the present invention is a charging member for charging an image carrier by rubbing the image carrier on which an electrostatic latent image is formed. It is characterized by having the charging magnetic particles of each of the above aspects carried by a magnetic force on a magnet body having the same. At this time, the magnet body may be a cylindrical conductive sleeve containing a magnet.

The charging device of the present invention is a charging device for charging an image carrier by rubbing the image carrier on which an electrostatic latent image is to be formed. And a power supply for applying a voltage to the magnet body.

In the charging device of the present invention, the magnet body may be a cylindrical conductive sleeve containing a magnet. Further, it is preferable that the voltage applied to the conductor is a DC voltage on which an oscillating voltage is superimposed. Further, it is preferable that a peak-to-peak voltage of the oscillation voltage is 1000 V or less.

In the charging device of the present invention, the image carrier may include a cylindrical conductive substrate, a photosensitive layer covering the surface thereof, and a charge injection layer formed on the surface of the photosensitive layer. preferable. At this time, it is preferable that the thickness of the conductive substrate is 0.5 mm to 3.0 mm.

In the image forming apparatus of the present invention, the charging magnetic particles of the above-described embodiments are placed on an image carrier for forming an electrostatic latent image and a magnet having a conductor to which a voltage is applied. A charging device for charging the image carrier by contacting a charging member carried by the image carrier, and an electrostatic latent image is formed by exposing the surface of the image carrier charged by the charging device. An exposure device for forming, a developing device for visualizing an electrostatic latent image formed on the surface of the image carrier with toner, and a transfer device for transferring an image visualized by the toner to a transfer material, I do.

Note that the image forming apparatus of the present invention does not have an independent cleaning device, and that the toner remaining on the image carrier after the transfer is performed by the transfer device is collected by the developing device. It may be a feature.

Further, the process cartridge of the present invention comprises:
A process cartridge detachably mountable to an image forming apparatus for forming an image by visualizing an electrostatic latent image formed on an image carrier with a developer, and transferring the visualized image to a transfer material. A charging member comprising a magnet having a conductor to which a voltage is applied, and the charging magnetic particles of the above-described embodiments being carried by a magnetic force; an image carrier for forming an electrostatic latent image; and the image carrier. A developing device for visualizing an electrostatic latent image formed on the surface with toner, and a cleaning device for removing residual toner on the image carrier after the image visualized by the toner is transferred to a transfer material. And at least one selected from the group consisting of:

[0038]

Embodiments of the present invention will be described below in detail.

<Charging Magnetic Particles> The charging magnetic particles of the present invention are the charging magnetic particles that charge the image carrier by being rubbed on the image carrier on which an electrostatic latent image is formed. The magnetic particles for charging have magnetic particles and a coat layer covering the surface of the magnetic particles, and the coat layer contains a nitrogen-containing material.

Ferrite particles are preferably used as the magnetic particles used in the charging magnetic particles of the present invention.
Ferrite containing a metal element such as copper, zinc, manganese, magnesium, iron, lithium, strontium, and barium is preferably used.

The presence of a coat layer containing a nitrogen-containing material on the surface of the magnetic particles imparts triboelectrification to the toner to the magnetic particles for charging, thereby controlling the polarity of the toner mixed in the charging member. And can be electrostatically bound. The toner whose polarity is controlled can be electrostatically discharged to the photoconductor side by the charging bias, so that toner accumulation inside the charging member is also prevented. As a result, it is possible to prevent the toner from scattering and lowering the chargeability.

Examples of general coating materials for forming the coating layer of the present invention include coupling agents, resins, oils such as silicone oil, resins modified with coupling agents, and materials obtained by mixing these materials. No.

Among the above-mentioned coating materials, as the resin, silicone resins such as methyl silicone, methyl phenyl silicone, silicone acryl, silicone modified with a silane coupling agent, nylon-6, nylon-1
2. Polyamide resins such as nylon-46 and aramids, polyurethane resins, melamine resins, fluorine resins such as polytetrafluoroethylene, vinyl chloride resins, polyethylene (PE) and polypropylene (PP)
And polyolefin resins, epoxy resins, polyester resins such as polyethylene terephthalate (PET), and polystyrene resins.

Examples of the oils include dimethyl silicone oil, silanol-terminated silicone oil, modified silicone oil modified by introducing various organic groups into the side chain or terminal, and methyl hydrogen silicone oil obtained by introducing hydrogen into the side chain. Used.

Examples of the modified silicone oil include amino-modified, alcohol-modified, epoxy-modified, carboxyl-modified, methacryl-modified, phenol-modified, mercapto-modified, alkoxy-modified, polyether-modified, fatty acid ester-modified, alkyl-modified, styryl-modified, and fluorine-modified. However, two or more kinds of organic groups such as an amino group and an alkoxy group and an amino group and an epoxy group may be introduced and modified.

In the present invention, the term "coupling agent" refers to a compound having a hydrolyzable group and a hydrophobic group in the same molecule and bonded to a central element such as silicon, aluminum, titanium, and zirconium. Preferred coupling agents include silane-based coupling agents, titanate-based coupling agents, and aluminum-based coupling agents.

As the hydrolyzable group of the coupling agent, for example, an alkoxy group such as a methoxy group, an ethoxy group, a propoxy group and a butoxy group, which is relatively hydrophilic, is used. In addition, an acryloxy group, a methacryloxy group, a modified form thereof, a halogen atom, and the like are also used.

As the hydrophobic group, in the case of titanate, acylate, phosphate, sulfonate, amino type,
In the case of alcoholates and silanes, functional groups such as a vinyl group, a methacryl group, an ether bond, an epoxy group, an amino group and a mercapto group are used, and in the case of aluminates, a chelate type is used.

The nitrogen-containing material is preferably a material containing an amino group. Examples of the material for the amino-containing coating layer include, among the above-mentioned coating materials, an amino-containing coupling agent, an amino-modified resin, an amino-modified silicone oil modified by introducing an amino group into a side chain or a terminal of a silicone oil. And resins modified with an amino group-containing coupling agent, and materials obtained by mixing these amino group-containing materials with other resins, oils, coupling agents, and the like.

In order for the magnetic particles for charging to exhibit uniform charging properties and high durability, the contact property between the magnetic particles for charging and the photosensitive member is an important factor. In order to impart suitable contact properties to the magnetic particles for charging, it is preferable to use a material that can reflect the surface shape of the magnetic particles as much as possible even after the formation of the coat layer. As a material for such a coating layer, a coupling agent or an oil capable of forming a thin layer is preferable. From the viewpoint of high durability of the coat layer, a coupling agent capable of directly bonding to the magnetic particle surface is more preferable.

As such a coupling agent, an amino group-containing coupling agent whose central metal is a metal selected from silicon, titanium, aluminum and zirconium is more preferable.

Examples of the coupling agent include isopropyl tri (N-aminoethyl-aminoethyl) titanate, aminopropyltrimethoxysilane, aminopropyltriethoxysilane, dimethylaminopropyltrimethoxysilane, diethylaminopropyltrimethoxysilane, Dipropylaminopropyltrimethoxysilane, dibutylaminopropyltrimethoxysilane, monobutylaminopropyltrimethoxysilane, dioctylaminopropyldimethoxysilane, dibutylaminopropyldimethoxysilane, dibutylaminopropylmonomethoxysilane, dimethylaminophenyltriethoxysilane, tributylsilane Methoxysilyl-γ-propylphenylamine, trimethoxysilyl-γ-propylbenzylamine and the like. In addition, these coupling agents may be used alone or as a mixture of two or more arbitrary types.

The magnetic particles for charging according to another embodiment of the present invention include magnetic particles, a first coat layer covering the surface of the magnetic particles, and a second coat layer covering the surface of the first coat layer. And the second coat layer is made of a nitrogen-containing material. With such a configuration of the magnetic particles for charging, a coat layer made of a nitrogen-containing material can be formed under the same conditions without being influenced by the surface state of the magnetic particles. For this reason, the production stability can be maintained, and the stable triboelectricity can be exerted by the nitrogen-containing material, so that the scattering of the toner and the decrease in the chargeability can be more effectively prevented. The nitrogen-containing material is preferably a material containing an amino group. Furthermore, the presence of the amino group in the second coat layer prevents the coat layer of each magnetic particle from peeling off.

At this time, the cure temperature of the first coat layer is preferably higher than the cure temperature of the second coat layer. If the cure temperature of the first coat layer is higher than the cure temperature of the second coat layer containing an amino group, the second coat layer is formed at a lower temperature than the first coat layer. When manufacturing, the first coat layer can be prevented from being thermally denatured. In addition, it is possible to prevent the first coat layer component from acting unevenly on the second coat layer. As a result, the first coat layer and the second coat layer can be manufactured with good reproducibility, so that the characteristics of the amino group can be sufficiently exhibited.

Here, as the magnetic particles, ferrite particles as described above are preferably used. As the material of the second coat layer containing an amino group, the same material as the above-mentioned coat material containing an amino group is preferably used.

As the material of the first coat layer, the above-mentioned general coat material can be used. In the present invention, the first coat layer contains a compound having an alkyl chain having 6 or more carbon atoms. Is preferred. When the first coat layer contains a compound having an alkyl chain having 6 or more carbon atoms (hereinafter, sometimes referred to as “C6 or more”), lubricity is imparted to the magnetic particles for charging, and Since the load between the particles is reduced, the durability of the coat layer is improved. Further, when the charging magnetic particles having the first coat layer are used for the charging member, the load on the photoconductor and the blade is reduced, so that the photoconductor can be prevented from being scraped. Fine particles of magnetic particles generated during the manufacturing process may adhere to the surface of the magnetic particles for charging, but the fine particles are fixed to the surface of the magnetic particles in the first coat layer having an alkyl chain of C6 or more. Therefore, it is possible to prevent the fine powder from adhering to the photoreceptor due to leakage of the fine powder, to prevent the fine powder from mixing with the toner. This effect is further improved by the second coat layer containing an amino group.

Further, when the first coat layer contains a C6 or more alkyl group, the fluidity of the magnetic particles for charging is improved, the toner is prevented from adhering to the magnetic particles for charging, and the tribo-imparting property is maintained by the amino group. Achieved. As a result of these multiple actions, if the magnetic particles for charging of the present invention are used, a long-term uniform charging property can be maintained as a charging member,
The durability life and image quality of the photoconductor are improved as an image forming apparatus.

In terms of production, the lubricating properties are imparted to the magnetic particles by the first coat layer, so that the first coat layer does not wear when the second coat layer is formed, Since the wear of the coat layer is also prevented, a double coat layer can be formed efficiently.

The coating material having an alkyl chain of C6 or more used in the first coating layer of the present invention includes, for example,
Coupling agents having a hydrophobic group of C6 or more, resins, modified silicone oils having an alkyl chain of C6 or more introduced into a side chain or terminal of silicone oil, resins modified with a coupling agent having a hydrophobic group of C6 or more, Examples thereof include a material in which a material having an alkyl chain is mixed with another resin, oil, a coupling agent, or the like.

Of these, coupling agents and oils capable of forming a thin layer are preferred for the same reasons as in the case of the second coat layer containing an amino group. Further, a coupling agent is more preferable in terms of lubricity of the coating layer, high durability, and good releasability from the toner.

Examples of such a coupling agent include isopropoxytitanium tristearate (TTS), octadecyltrimethoxysilane, octyltriethoxysilane, dodecyltriethoxysilane, isopropyltri (dioctylphosphate) titanate, and isopropyltridodecylbenzenesulfonyl. Titanate, isopropyltrioctanoyl titanate, isopropyltriisostearoyl titanate and the like can be mentioned.

As described above, the alkyl chain of the coupling agent used in the first coat layer preferably has 6 or more carbon atoms, and more preferably 6 to 30 carbon atoms. If the number of carbon atoms is too large, the solvent tends to be insoluble in the solvent, so that the time required for the treatment increases. In addition, the fluidity of the magnetic particles also partially changes, and uneven charging tends to occur, which is not preferable.

The amount of the coupling agent present as a coating layer containing an amino group is 0.001 to the magnetic particles.
To 1.0% by mass, preferably 0.001 to 1.0% by mass.
More preferably, it is 0.05% by mass. If the amount of the coupling agent is too small than the above range, the effect of the coupling agent is not seen, and if the amount is too large, the flowability of the magnetic particles for charging is deteriorated, and it is not practically used. It is not preferable because it may occur. When the amount of the coupling agent is within the above range, the amount of the coupling agent with respect to the magnetic particles is extremely small, so that the electric resistance of the magnetic particles for charging is substantially equal to that of the magnetic particles before forming the coat layer. Become. Therefore, the magnetic particles for charging of the present invention are:
The production stability and the quality stability are higher than in the case where a resin in which conductive particles are dispersed is used as a surface coating agent.

It is known that the scattering of the toner from the charging member is related to the increase of the transfer residual toner, the high humidity condition, the high speed rotation of the charging member, and the like. For example, when an image having a high image ratio is continuously formed, the amount of transfer residual toner increases, and the amount of toner remaining in the charging member may increase. Even in such a case, since the magnetic particles for charging of the present invention have good lubricity, tribo-attractive property and releasability, toner accumulates on the charging member and surface contamination of the magnetic particles for charging. Can be prevented,
It is possible to prevent toner scattering and resistance fluctuation of the charging member.

Under the condition of high humidity, the chargeability of the toner is reduced by the influence of moisture in the air, and the toner is easily scattered from the charging device. Since the magnetic particles for charging of the present invention have high contact property with toner, they exhibit an excellent effect of triboelectric charging property with respect to toner and can prevent toner scattering. Furthermore, since the surface of the magnetic particles is made hydrophobic by the coat layer having an alkyl chain of C6 or more, even under a long-term high-humidity condition, the effect of moisture can be eliminated and sufficient toner charging can be performed.

Further, the magnetic particles for charging of the present invention are effective in preventing accumulation of toner and contamination even in a model having a high process speed, for example, in a case where a charging device rotates at a high speed on a photoreceptor so as to perform charging. Work on. 2. Description of the Related Art In recent years, an image forming apparatus of a developing / cleaning type (cleanerless) in which a cleaner apparatus for collecting transfer residual toner on a photoconductor is removed has been commercialized. In this image forming apparatus, since the transfer residual toner is always present in the charging nip portion, toner scattering,
It has been considered that it is more severe to prevent the fluctuation of the resistance of the charging member, the generation of a ghost image, and the like. Therefore, if the magnetic particles for charging of the present invention are used, the transfer residual toner can be efficiently taken in and discharged, so that the toner is not accumulated on the charging member, and at the same time, the toner is scattered due to the good charge imparting property to the toner. Can be prevented. Further, the magnetic particles for charging of the present invention have good surface releasability and a surface cleaning effect by magnetic particles, and can prevent toner contamination even after long-term use.

The composition of the coat layer of the present invention containing a nitrogen-containing material can be confirmed by chemical analysis. The material of the coat layer of the present invention can be easily confirmed by comparing with a known coat material, and it is possible to calculate the throughput of the coat material from a specific peak or a rate of change in peak intensity. it can.

[0068] For example, the IR (infrared spectroscopy), nitrogen material fee, NH ₂ to 3360cm ^-1 and 1590 cm ^-1
And a peak relating to NH, and a peak presumed to be a tertiary amide at 1631 cm ^-1 appears. If aminosilane treatment agent, Si in 1,120 cm ^-1 in addition to the peak of the nitrogen
A peak due to -O-Si appears. Further, an acylate type Ti-based coupling agent (for example, TTS = T18
= Isopropoxytitanium tristearate)
Peak of 10～1249Cm ^-1 and 1735 cm ^-1, and the coexistence with these peaks and 1710 cm ^-1 vicinity of the peak, the presence of a carboxylic acid or carboxylic acid ester is seen.

In ESCA (electron spectroscopy), N of the nitrogen-containing material and Ti and Si which are the central metals of the coupling agent can be easily detected from the spectrum. Also,
From the state of the spectrum (chemical shift), N, Si, T
It is also possible that i is an amine, an organosilicon compound or an organotitanium compound, respectively. The abundance of each component can be relatively known from the peak intensity ratio, and the absolute amount can be estimated from a calibration curve using a known material.

As a material containing an alkyl chain having 6 or more carbon atoms, TTS which is the above-mentioned Ti-based coupling agent is used.
When using H-NMR, 5.13, 2.46,
From the peaks at 1.88, 1.48, and 0.98 ppm, they can be assigned to the isopropoxy compound and the long-chain alkyl carboxylic acid compound.

The TOF-SIMS (time-of-flight secondary ion mass spectrometer) can analyze the outermost surface (several atomic layers) of the coat layer, and can detect N of the nitrogen-containing material and Ti as the central metal of the coupling agent. And Si can be detected as elemental ions. Furthermore, a demonstrative formula can be found from the detection of the fragment ion species. For example, m / z = 147, 175, 191
Has been confirmed to indicate aminosilane.
In addition, even with the same coating material, the peak intensity of element ions or fragments changes at the processing temperature. When aminosilane is used as the nitrogen-containing material, the treatment temperature is increased from 120 ° C to 17 ° C.
By raising the temperature to 0 ° C., the peak intensity of NH ₄ (m / z
= 18) is reduced by about 35% from 290. The processing conditions can be confirmed from the rate of such a change.

In the above chemical analysis, analysis can be performed even when there are a plurality of materials forming the coat layer. However, the concentration gradient of the coat component can be examined by devising a method of extracting the coat component using a solvent. Thereby, when a plurality of materials are simultaneously mixed to form a coat layer (hereinafter, this may be referred to as “simultaneous coat”),
That is, it is possible to distinguish the case where the second coat layer is formed on the surface of the first coat layer (hereinafter, this may be referred to as “two-step coat”). For example, when ethanol-soluble aminosilane and ethanol-insoluble TTS are used as coating materials, when a second coating layer of aminosilane is formed on the surface of the first coating layer of TTS, that is, when two-step coating is performed, Aminosilane is selectively dissolved by ethanol extraction. However, when these are mixed and simultaneously coated, the contact between ethanol and aminosilane is inhibited by TTS, and the amount of extraction is reduced.

When Soxhlet extraction with toluene soluble in both is carried out and H-NMR analysis is performed, in the case of simultaneous coating, a spectrum belonging to the isopropoxy compound which cannot be detected in the two-step coating can be obtained.

TOF-SIMS capable of analyzing the outermost layer,
In the ESCA and the cross-sectional transmission microscope, it is possible to detect that the existing intensity of the first coat layer (TTS) tends to decrease in the case of the two-stage coating as compared with that of the simultaneous coating, so that the absolute amount of the coating material The simultaneous coating and the two-step coating can be distinguished from the relationship between the strength and the existing strength. Also, TOF-SIMS
The NH ₄ ions detected in step (2) can be distinguished from each other also because the intensity of the two-step coating is higher than that of the simultaneous coating. By the above method, the components of the coating layer and the coating means can be verified.

In the magnetic particles for charging of the present invention, among the magnetic particles for charging, the magnetic particles for charging having a maximum chord length of 5 μm to 20 μm have a ratio of the minor axis length to the major axis length (short length). The standard deviation of (axial length / long axis length) is preferably 0.08 or more, more preferably 0.10 or more. When such magnetic particles are used, the contact between the magnetic particles for charging and the surface of the photoreceptor is further improved, so that the photoreceptor can be sufficiently charged even if the transfer residual toner component exists in the charging nip portion. Can be.

If the standard deviation of (short axis length / long axis length) is smaller than the above range, the variation in the shape of the magnetic particles for charging becomes too small, and a large amount of untransferred toner is continuously generated in a cleanerless device. In such a case, the contact property with the photoreceptor and the surface cleaning property of the magnetic particles may not be maintained for a long period of time. This is because there is a shape of magnetic particles for charging suitable for contact and cleaning properties,
This is considered to be the effect.

Here, the maximum chord length of the magnetic particle indicates the maximum value of the length between any two points on the surface of the magnetic particle. In the present invention, the lengths of the minor axis and the major axis of the magnetic particles are defined as the lengths of the minor axis and the major axis of the ellipse when the secondary development shape of the magnetic particles such as an electron microscope image is replaced with the ellipse. Can be.

Hereinafter, a method for measuring the standard deviation of the length of the short axis / the length of the long axis will be described. Hitachi FE-SEM (S-800)
Is used to randomly extract 100 particle images magnified 500 times, and based on the image information, for example, ImageA
With the analyzer V10 (Toyobo Co., Ltd.),
Statistical processing of the result of image analysis is performed. In the analysis, first, from an electron micrograph, an image signal that has passed through a stereomicroscope is input to an analyzer, and the image information is binarized. Analysis is performed based on the binarized image information.

For more information, see Image Analyzer
There is a detailed description in the V10 (manufactured by Toyobo Co., Ltd.) manual, but if the method is briefly explained, the ratio of the length of the major axis to the minor axis of the ellipse is passed through the process of replacing the shape of the object with the ellipse Ask for. The processing is performed as follows. When the specific gravity of the small area Δs = Δu · Δv at the coordinates (u, v) is 1 with respect to the binarized shape of the magnetic particles,
With respect to the origin (X, Y), the second moment about the horizontal axis and the vertical axis (the second moment Mx about the horizontal axis, the second moment about the vertical axis, passing through the center of gravity of the binarized shape of the particle) The moments My) are expressed by the following equations.

[0080]

## EQU1 ## Mx = ΣΣ (u−X) ² My = ΣΣ (v−Y) ² Synergistic moment of inertia Mxy is expressed by the following equation.

[0081]

Mxy = ΣΣ (u−X) · (v−Y) The angle θ that satisfies the following equation has two solutions.

[0082]

(Equation 3) Furthermore, the moment of inertia M in the axial direction forming an angle θ with the horizontal axis
θ is expressed by the following equation.

[0083]

## EQU4 ## Mθ = Mx · (cos θ) ² + My · (sin
θ) ² −Mxy · sin2θ By substituting the above two solutions of θ, the smaller one of the calculated Mθ becomes the main axis. Furthermore, on any axis (1 / Mθ)
^When points corresponding to ^0.5 are plotted, they form ellipses. If the principal axis coincides with the principal axis of inertia, the direction of taking a small value of Mθ is A, and the larger one is B, the following ellipse is obtained.

[0084]

A x ² + B y ² = 1 The length of the minor axis / the length of the major axis in the present invention is expressed by the following equation with respect to the above ellipse.

[0085]

[Formula 6] short axis length / long axis length = (A / B) ^0.5

The analysis of the standard deviation of the minor axis length / major axis length of a particle having a maximum chord length of 5 μm to 20 μm is as follows.
The measurement is performed for a substrate having a thickness of 20 μm.

The average particle size and distribution of the magnetic particles for charging according to the present invention were set to a minimum value of 0.5 μm using a laser diffraction type particle size distribution analyzer HELOS (manufactured by JEOL Ltd.) and 1.80.
The range of μm to 350 μm was measured by 31 logarithmic division, and the average diameter was defined as a 50% volume median diameter.

The average particle size of the magnetic particles is 10 to 200
It is preferably in the range of μm, more preferably 10 to 35 μm. If the average particle diameter is too small than the above range, the transportability of the magnetic particles when the magnetic particles for charging are used as a magnetic brush tends to decrease, especially in a high-speed machine and the like, the magnetic particles may leak, Not preferred. Further, if the average particle size is larger than the above range, when the charging magnetic particles of the present invention are used in the injection charging method described below, particularly in a high-speed machine, the charging efficiency due to the injection charging is reduced and the partially charged state is obtained. It is not preferable because it may be uneven.

The magnetic particles for charging used in the present invention have a volume resistance of 1 × 10 ⁴ Ωcm to 1 × 10 ⁹ Ωc.
m, preferably 1 × 10 ⁶ Ωcm to 1 × 10 ⁹
More preferably, it is Ωcm. If the volume resistance is smaller than the above range, pinhole leakage may occur, and if the volume resistance exceeds the above range, the charging of the photoconductor becomes insufficient, which is not preferable.

The volume resistance of the magnetic particles for charging was determined by a tablet method. In the measurement, first, the cells were filled with magnetic particles.
Electrodes were arranged above and below so as to be in contact with the magnetic particles, a voltage was applied between the electrodes, and the current was calculated from the amount of current flowing at that time. The measurement conditions were as follows: the environment where the temperature was 23 ° C. and the humidity was 65%, the contact area between the filled magnetic particles and the electrode was 2 cm ² , and the thickness was 1 m.
m, weight applied to the upper electrode is 10 kg, and applied voltage is 100
V.

<Charging Member, Charging Device and Image Forming Apparatus> Next, a charging member, a charging apparatus and an image forming apparatus using the magnetic toner for charging of the present invention will be described. The charging member of the present invention is a charging member for charging an image carrier by rubbing the image carrier on which an electrostatic latent image is formed, wherein the magnet member has a conductor to which a voltage is applied. It is characterized by having the magnetic particles for charging of the present invention carried thereon by magnetic force. Further, a charging device of the present invention includes such a charging member and a power supply for applying a voltage to the magnet body.

FIG. 1 is a schematic sectional view showing an example of the charging member and the magnetic brush charging device of the present invention. The magnetic brush charging device 10 includes a magnet roll 11 as a magnetic force generating member and a non-magnetic (S
The charging member 90 includes an electrode sleeve 12 (corresponding to a conductor to which a voltage is applied) made of US, aluminum, or the like, and charging magnetic particles 13 held on the surface of the electrode sleeve 12 by the magnetic force of a magnet roll. . The magnetic particles 13 for charging form a magnetic brush by being connected to the surface of the electrode sleeve 12 by magnetic force. In FIG. 1, a magnet body is configured by the magnet roll 11 and the electrode sleeve 12. That is, in FIG. 1, the magnet body is a cylindrical conductive sleeve containing a magnet roll as a magnet. The electrode sleeve 12 is rotatably held by the frame 15.

The charging device 10 further includes an electrode sleeve 1
Power supply 1 for applying a charging bias from 2 to contact 14
6 is provided.

The charging is performed by applying a voltage to the electrode sleeve 12. As the voltage to be applied to the electrode sleeve 12, a DC voltage or a voltage obtained by superimposing an oscillating voltage (AC voltage) on a DC voltage is used, and a voltage obtained by superimposing an oscillating voltage is preferable. This is because stable charging can be performed against disturbances such as mechanical accuracy due to the oscillating voltage.

The magnetic brush formed by the charging magnetic particles 13 is rotated by the rotatable electrode sleeve 12 in a state where the magnetic brush is opposed to or rotated in a forward direction at an arbitrary peripheral speed difference while being in contact with an image carrier described later. The image carrier is rubbed and charged. Also, charging in a fixed state without rotation is possible. The amount of the magnetic brush, that is, the amount of the charging magnetic toner 13 held on the electrode sleeve 12 is 50 to 500 with respect to the electrode sleeve surface in order to stabilize the charging property.
mg / cm ² , preferably 100-300 m
g / cm ² is more preferable. Alternatively, extra magnetic particles 13 for charging may be held in the charger and circulated.

Next, an image forming apparatus using the charging device will be described. The image forming apparatus according to the present invention includes an image carrier that forms an electrostatic latent image, and a magnetic body that carries the magnetic particles for charging of the present invention on a magnet having a conductor to which a voltage is applied by magnetic force. A charging device that charges the image carrier by contacting the member with the image carrier, and an exposure device that forms an electrostatic latent image by exposing a surface of the image carrier charged by the charging device; A developing device for visualizing the electrostatic latent image formed on the surface of the image carrier with toner, and a transfer device for transferring the image visualized by the toner to a transfer material.

FIG. 2 is a schematic sectional view showing an example of the image forming apparatus of the present invention. The image forming apparatus of the present invention includes an image carrier (photoreceptor) 20, a magnetic brush charging device 10 that contacts the image carrier 20 and charges the image carrier 20 by applying a voltage, and an image carrier. An exposure device 30 for forming an electrostatic latent image on the surface of the image bearing member 20, which is disposed close to or in contact with the image carrier 20 to develop the electrostatic latent image to form a toner image and to remove transfer residual toner remaining on the photoreceptor; Developing device 4 to collect
0, a transfer device 50 is provided.

Although the charging device 10 described above is used, the injection charging method can be preferably used in the electrophotographic device of the present invention. When the injection charging method is used, the image carrier 20 preferably has a configuration including a cylindrical conductive substrate, a photosensitive layer covering the surface thereof, and a charge injection layer formed on the surface of the photosensitive layer. . With such a configuration, 80% or more, and even 90%
% Or more can be obtained.

By using such an injection charging method, it is possible to realize a further ozoneless charging method as compared with a charging method interpreted by Paschen's law. In addition, the charge injection layer can reduce the residual potential by playing a role of more efficiently discharging the charged charges to the conductive substrate during exposure. Therefore, effects such as suppression of fluctuations in contrast and uniform images can be obtained by the injection charging method.

As described above, as the voltage applied to the electrode sleeve 12 of the charging device 10, a DC voltage or a voltage obtained by superimposing an oscillating voltage (AC voltage) on a DC voltage is preferably used. .

In the injection charging method, since the potential of the image carrier 20 follows the applied voltage, if the peak-to-peak voltage is too large, the potential of the charged surface of the photoreceptor may undulate, causing image fogging and the like. is there. Therefore, the frequency of the applied vibration voltage is preferably about 100 Hz to 10 kHz. The peak-to-peak voltage is 100 V or more and 1000 V or more.
V or lower, preferably 300 V or higher and 1000 V or lower.
It is more preferred that: The waveform is a sine wave,
A rectangular wave, sawtooth wave or the like can be used.

The charge injection layer formed on the image carrier 20 may be made of a material having a medium resistance by dispersing an appropriate amount of light-transmitting and conductive particles in an insulating binder resin. It is possible, and it is also effective to form an inorganic layer having the same resistance. When the charge injection layer is formed on the layer farthest from the conductive substrate, the volume resistivity of the charge injection layer is 1 × so that the image carrier retains sufficient chargeability and does not cause image deletion. 10 ⁸ -1 × 1
It is preferably in the range of 0 ¹⁵ Ωcm. If the volume resistivity is smaller than the above range, the image carrier 20 cannot hold an electrostatic latent image, and image deletion may occur in a high-temperature and high-humidity environment. In some cases, sufficient charge from the device 10 cannot be received, resulting in poor charging.

From the viewpoint of more reliably preventing image deletion under high temperature and high humidity conditions, the volume resistivity is 1 × 10 ¹⁰ to 1 ×.
More preferably, it is 10 ¹⁵ Ωcm. In consideration of a sudden environmental change, the volume resistivity is 1 × 10 ¹² to 1 ×.
More preferably, it is 10 ¹⁵ Ωcm.

The volume resistance of the charge injection layer was measured by a method in which polyethylene terephthalate (P) having a conductive film deposited on the surface was used.
ET), and a charge injection layer is formed on the charge injection layer.
(TER) in a 23 ° C., 65% humidity environment with a voltage of 100 V applied.

When the charge injection layer is formed by dispersing conductive particles in an insulating binder resin, the particle size of the conductive particles dispersed in the charge injection layer is 0.3 μm from the viewpoint of light transmission.
Or less, and most preferably 0.1 μm or less. The dispersion amount of the conductive particles may be 2 to 250 parts by mass with respect to 100 parts by mass of the binder resin, and is preferably 2 to 250 parts by mass.
To 190 parts by mass. If the amount of dispersion is less than the above range, it is difficult to obtain a preferable volume resistance value of the charge injection layer. is there. The charge injection layer preferably has a thickness of 0.1 to 10 μm, more preferably 1 to 7 μm.

It is preferable that the charge injection layer contains a lubricant powder. Since the lubricant powder is contained in the charge injection layer, the image carrier 20 and the charging device 10 are charged during charging.
Is reduced, and the nip involved in charging is enlarged, so that charging characteristics are improved. Further, the image carrier 20
Since the releasability of the image carrier is improved, the magnetic particles
To adhere to the surface. As the lubricant powder, it is preferable to use a fluororesin, a silicone resin, or a polyolefin resin having a low critical surface tension. Particularly preferred is a tetrafluoroethylene resin. In this case, the addition amount of the lubricant powder is preferably 2 to 100 parts by mass of the binder resin.
It is 50 parts by mass, more preferably 5 to 40 parts by mass. If the amount of the lubricant powder is too small than the above range,
Since the amount of the lubricant powder is insufficient, the effect of improving the chargeability of the image carrier 20 cannot be sufficiently obtained, and the amount of the transfer residual toner increases. Therefore, it is not preferable from the viewpoint of a cleanerless device. On the other hand, if the amount of the lubricant powder is too large, the image resolution and the sensitivity of the photoreceptor are undesirably reduced.

When an inorganic layer is used for the charge injection layer, it is necessary to form a photosensitive layer thereunder. This photosensitive layer is preferably amorphous silicon, and it is preferable to sequentially form a blocking layer, a photosensitive layer, and a charge injection layer on a conductive substrate by glow discharge or the like.

As the photosensitive layer, conventionally known ones can be used. For example, as an organic material, a phthalocyanine pigment, an azo pigment, or the like can be used. Further, an intermediate layer may be provided between a surface protective layer such as a charge injection layer and the photosensitive layer. The purpose of such an intermediate layer is to enhance the adhesion between the surface protective layer and the photosensitive layer or to function as a charge barrier layer. As the intermediate layer, for example, a commercially available resin material such as an epoxy resin, a polyester resin, a polyamide resin, a polystyrene resin, an acrylic resin, and a silicone resin can be used.

The conductive substrate of the image carrier 20 may be aluminum, nickel, stainless steel, steel, or the like, or a metal or a plastic having a conductive film, glass, or conductive paper.

The conductive substrate has a thickness of 0.5 to 0.5.
3.0 mm is preferable because the vibration of the image carrier 20 can be suppressed. If the conductive substrate is thinner than the above range, the dimensional stability is poor, and if it is too thick, the rotational torque increases and the material cost increases, which is disadvantageous in terms of cost and is not preferable.

In the image forming apparatus of the present invention, a known device such as a laser or an LED can be used as the exposure device 30.

As the developing device 40 used in the image forming apparatus of the present invention, a conventionally known developing device can be used. However, a developing and cleaning type (cleanerless type) image forming apparatus having no independent cleaning means can be used. In this case, reversal development is preferable, and a configuration in which the developer and the photoreceptor are in contact is preferable. For example, a contact two-component development method, a contact one-component method, and the like can be mentioned as suitable development methods. When the developer and the transfer residual toner can come into contact with each other on the photoreceptor, in addition to the electrostatic action, a rubbing force is applied, and the recoverability of the transfer residual toner is improved. Further, the DC component of the developing bias applied to the development is preferably between the black portion (image exposed portion) and the potential of the white background portion.

In FIG. 2, a developing device 40 is a two-component magnetic brush developing device using a contact two-component developing method, and stirs a developing sleeve 41, a magnet roller 42 fixedly arranged in the developing sleeve 41, and a developer 45. It has a stirring screw 43 that conveys the developer 45 onto the developing sleeve 41 and a regulating blade 44 for forming a thin layer of the developer 45 on the developing sleeve 41. The developing sleeve 41 is disposed very close to the image carrier 20, and
5 is set so as to be in contact with the image carrier 20 and can be developed. A DC voltage and an AC voltage are applied to the developing sleeve 41 from a power supply 46. Developing device 40
By controlling the voltage applied to the developing sleeve 41, it is possible to collect the toner in the non-image area remaining on the image carrier 20 at the same time as the development to the developing base side. I have.

As the transfer device 50 used in the image forming apparatus of the present invention, a known device such as a roller, a belt, and a corona transfer device is used.

Further, in the image forming apparatus of the present invention,
Attachment of the photosensitive member potential control member to the image carrier 20 after the transfer step and before the charging step improves the stability of image formation, and is particularly effective in a developing and cleaning system. As the photosensitive member potential control member, a member that emits light to control the photosensitive potential, a conductive roller, a blade, or a fur brush arranged in contact or close proximity is used, and a roller and a fur brush are particularly preferable.

In the developing and cleaning method, when the transfer residual toner is conveyed to the developing portion by using the surface of the image carrier from the charging member from which the transfer residual toner has been recovered, and is collected and reused, the image carrier is removed. This can be achieved without changing the charging bias, but in practice, when transfer paper jams or when images with a high image ratio are continuously taken, an excessive amount of toner may be mixed into the charging member. .

In this case, during the image forming operation, it is possible to move the toner from the charging member to the developing machine by utilizing the time during which no image is formed on the photosensitive member. The time during which no image is formed is, for example, during pre-rotation, post-rotation, or between transfer sheets. In such a case, a method of changing the charging bias so that the toner is more easily transferred to the photoconductor than the charging device 10 is preferably used. Examples of the bias that easily shifts from the charging device 10 include a method of reducing the peak-to-peak voltage of the AC component or setting the DC component, or changing the waveform to lower the AC effective value by making the peak-to-peak voltage the same. .

In the present invention, the durability of the charging device can be further extended by a method of increasing the amount of the charging magnetic particles in the charging device 10 or a method of circulating the charging magnetic particles in the charging device 10.

As means for circulating, the magnetic particles for charging are mechanically agitated, the magnetic pole structure is configured so that the magnetic particles for charging can be circulated, or the magnetic particles for charging are charged in a container storing the magnetic particles. It is preferable to use each method such as providing a member to be moved. For example, providing a screw member for stirring behind the magnetic brush,
A method of providing a repulsion pole and recoating while peeling off the magnetic particles for charging, or a method of providing an obstruction member or the like that obstructs the flow of the magnetic particles for charging can be given.

Further, according to the present invention, when the charging member 90 is mounted on the charging device 10, for example, one of other devices such as the image carrier 20, the developing device 40, and the cleaning device is used.
Such an image forming apparatus may be realized by removably incorporating the process cartridge integrally supported in the image forming apparatus main body.

[0121]

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

<Production Example 1 of Magnetic Particles> Fe ₂ O ₃ (53 mol%), CuO (23.5 mol%), ZnO (23.5 mol%)
(Mol%) as the main component and 100 parts by mass of an oxide containing 0.1 mol of phosphorus.
After adding 05 parts by mass and pulverizing and mixing, water, a dispersant and a binder were added to form a slurry. The slurry was granulated by a spray drier method and calcined at 1170 ° C. to obtain CuZn ferrite. After firing, crushing and classification are performed to obtain spherical magnetic particles 1 having an average particle size of 25 μm.
I got The standard deviation of minor axis length / major axis length of the magnetic particles having a maximum chord length of 5 to 20 μm was 0.06.

8 × 10 ⁴ A / m of the obtained magnetic particles 1
The magnetization under a magnetic field of (1 KOe) is 57 Am ² / k
g (57 emu / g).

<Production Example 2 of Magnetic Particles> Fe ₂ O ₃ (53 mol%), MnO (32 mol%), MgO (15 mol%)
0.3 parts by mass of phosphorus was added to 100 parts by mass of an oxide containing as a main component, and the mixture was pulverized and mixed, and then water, a dispersant, and a binder were added to form a slurry. This slurry was granulated by a spray drier method and fired in an electric furnace with an adjusted oxygen partial pressure.
MnMg ferrite was obtained. After firing, crushing and classification were performed to obtain spherical magnetic particles 2 having an average particle size of 30 μm.
Short axis length of magnetic particles having a maximum chord length of 5 to 20 μm /
The standard deviation of the major axis length was 0.06.

8 × 10 ⁴ A / m of the obtained magnetic particles 2
Magnetization in the magnetic field under (1 KOe) is the same as in Production Example 1 was ^{57Am 2 / kg (57emu / g} ).

<Production Example 3 of Magnetic Particles> In Production Example 1 of magnetic particles, those obtained by adjusting granulation conditions by a spray drier method were fired and pulverized to obtain spherical magnetic particles having an average particle diameter of about 70 μm. Produced. This was pulverized with a vibration mill to deform it, and classified so that the average particle diameter of the magnetic particles became 35 μm, to obtain magnetic particles 3. The standard deviation of minor axis length / major axis length of magnetic particles having a maximum chord length of 5 to 20 μm was 0.14.

8 × 10 ⁴ A / m of the obtained magnetic particles 3
The magnetization under a magnetic field of (1 KOe) is 57 Am ² / k
g (57 emu / g).

<Production Example 1 of Developer> Polyester Resin 1
After dry mixing 00 parts by mass, 2 parts by mass of a metal-containing azo dye, 3.5 parts by mass of low molecular weight polypropylene, and 5 parts by mass of carbon black, the mixture was kneaded with a biaxial kneading extruder set at 150 ° C. After the obtained kneaded material was air-cooled, it was finely pulverized by an air-flow type pulverizer, and further subjected to air classification to adjust the particle size distribution. To 100 parts by mass of the classified toner, 1 part by mass of hydrophobic titanium oxide and 1 part by mass of silica were externally added to prepare a toner having an average particle diameter of 7 μm.

The developing carrier of the developer was prepared by the following method. After mixing and dispersing a phenol / formaldehyde monomer (mass ratio 50:50) in an aqueous medium, the monomer 1
With respect to 00 parts by mass, 600 parts by mass of magnetic powder obtained by hydrophobizing magnetite particles surface-treated with alumina with isopropoxytriisostearoyl titanate, and 400 parts by mass of nonmagnetic hematite particles hydrophobized with isopropoxytriisostearoyl titanate Parts by weight were uniformly dispersed. The monomer was polymerized while appropriately adding ammonia thereto, to obtain a spherical magnetic resin carrier core material containing magnetic particles. A carrier for development 1 was obtained by coating 0.5 part by mass of an acrylic resin with respect to 100 parts by mass of the core material of the spherical magnetic resin carrier. This carrier has an average particle size of 40
μm, and the volume resistance value was 4 × 10 ¹³ Ωcm.

The developer described above was obtained by mixing the above-mentioned toner and the developing carrier 1 at a mass ratio of 7: 100.

<Production Example 2 of Developer> Polyester Resin 1
00 parts by mass, 4 parts by mass of a chromium compound of di-tert-butylsalicylic acid, a dilead yellow pigment (C.I.
I. Pigment Yellow 17) was preliminarily mixed in a dry manner with 4 parts by mass, and kneaded with a twin-screw kneading extruder in the same manner as in the preparation of the black toner. After air cooling, the mixture was finely pulverized by an airflow pulverizer, and the particle size distribution was adjusted by air classification. To 100 parts by mass of the classified toner, 1 part by mass of hydrophobic titanium oxide and 1 part by mass of silica were externally added to prepare a toner having an average particle size of 6.8 μm.

The toner and the developing carrier 1 were mixed at a mass ratio of 7: 100 to obtain a developer 2.

<Production Example of Image Carrier> An OPC photosensitive member was prepared by laminating a functional layer on an aluminum cylinder having a diameter of 30 mm and a thickness of 1.0 mm. The laminated layers are the first, second, third, fourth and fifth layers in this order from the aluminum cylinder side.

The first layer is an undercoat layer. A conductive layer having a thickness of 20 μm was provided in order to smooth defects of the aluminum cylinder and to prevent the occurrence of moire due to reflection of laser exposure. The second layer is a positive charge injection prevention layer. In order to prevent the positive charge injected from the aluminum cylinder side from canceling the negative charge charged on the photoreceptor surface, 6 × 10 ⁶
A layer made of an amylan resin adjusted to Ωcm and methoxymethylated nylon was formed to a thickness of about 1 μm.

The third layer is a charge generation layer. In order to generate positive and negative charge pairs by laser exposure, a layer having a thickness of about 0.5 μm in which a disazo pigment was dispersed was formed. The fourth layer is a charge transport layer. Hydrazone was dispersed in a polycarbonate resin to form a p-type semiconductor layer. This layer has a function of transporting positive charges generated in the charge generation layer to the surface of the photoreceptor, and negative charges charged on the surface of the photoreceptor cannot move through this layer.

The fifth layer is a charge injection layer. The charge injection layer is a conductive resin layer in which tin oxide is dispersed in a photocurable acrylic resin. Tin oxide is ultrafine particles having an average particle diameter of about 0.03 μm which is made conductive by doping with antimony, and dispersed in 180 parts by mass with respect to 100 parts by mass of the photocurable acrylic resin. The resistance was 6 × 10 ¹² Ωcm. In the charge injection layer, 20 parts by mass of polytetrafluoroethylene resin particles and 1 part by mass of a dispersant were dispersed for the purpose of improving the surface slipperiness.

Example 1 Production Example 1 of Magnetic Particles for Charging 0.15 parts by mass of T with respect to 100 parts by mass of magnetic particles 3
The i-type coupling agent (isopropoxytitanium tristearate) was wet-coated at 120 ° C. while stirring with a toluene solvent in a coater. Two more coat pots
The first coat layer was formed by raising the temperature to 20 ° C. and curing for 90 minutes. Next, after air cooling to around room temperature, 0.1
0 parts by mass of aminosilane (N- (2-aminoethyl)-
3-aminopropyltrimethoxysilane) was wet-coated at 80 ° C. with the above-mentioned coating kettle using an ethanol solvent, and further cured at 170 ° C. for 90 minutes to form a second coat layer, thereby obtaining magnetic particles 1 for charging. Was. There was no change in the particle size, short axis length / long axis length, and magnetic properties of the charging magnetic particles 1 before and after coating.

<Examples 2 to 18> Charging magnetic particles 2 to 18 were obtained in the same manner as in Example 1, except that the surface treatment of the magnetic particles was performed under the conditions shown in Table 1. Table 2 shows substance names corresponding to the abbreviations of the treatment agents for the first and second coat layers used in Table 1.

[0139]

[Table 1]

[0140]

[Table 2]

Example 19 100 parts by mass of magnetic particles 2
0.10 parts by mass of N- (2-aminoethyl)-
A mixture of 3-aminopropyltrimethoxysilane and 0.10 parts by mass of an acrylic resin was simultaneously wet-coated at 120 ° C. while stirring with a toluene solvent in a coater. Further, the temperature of the coat pot was raised to 170 ° C. and 90
Cure for a minute. As a result, magnetic particles 19 for charging were obtained.

<Example 20> Charging magnetic particles 20 were obtained in the same manner as in Example 19 except that the acrylic resin in Example 19 was changed to isopropoxytitanium tristearate.

As an image forming apparatus, a digital copying machine (GP55, manufactured by Canon Inc.) using a laser beam was modified and used as shown in FIG. The GP 55 is basically a reversal developing type digital copying machine having a process speed of 150 mm / s, including a corona charging device, a one-component jumping developing device, a corona transfer device, a blade-type cleaning device, and an exposure unit. This is the process speed 200
mm / s and further modified as follows.

The developing device was modified into a two-component magnetic brush developing device to enable development and cleaning. Developing device 40
Is a stirring screw 4 that conveys the developing sleeve 41, the magnet roller 42 fixedly disposed in the developing sleeve 41, and the developer 45 onto the developing sleeve 41 while stirring the developer 45.
3. It has a regulating blade 44 for forming a thin layer of the developer 45 on the developing sleeve 41. Developing sleeve 41
Is set so that the area closest to the image carrier 20 is at least about 500 μm at least at the time of development, and is set so that development can be performed in a state where the developer 45 is in contact with the image carrier.

A DC voltage and an AC voltage are applied to the developing sleeve 41 from a power supply 46. In this embodiment, the DC voltage is -500V, the AC voltage is Vpp = 1500V,
Vf = 2000 Hz was applied.

The charging device 10 is a magnetic brush type charging device shown in FIG. The non-magnetic electrode sleeve 12 (outer diameter 16 mm) containing the fixed magnet is attached to the image carrier 20.
Rotates in the opposite direction. In the present embodiment, the image carrier is rotated oppositely at a peripheral speed of 120% of the rotational speed of the image carrier. The charging bias is DC-700V / AC700Vpp (1 kHz
z).

As the image carrier 20, the one obtained by the above-mentioned production example was used.

The cleaning device was removed (blade and container) and modified to a cleanerless system (developing and cleaning system). As the transfer device 50, a contact-type transfer roller was attached, and constant current control was performed.

<Example 21> The magnetic brush charging device 10 carrying the charging magnetic particles 1 manufactured in Example 1 was mounted on the above-mentioned image forming apparatus, and evaluated by the following evaluation methods 1 and 2.

(Evaluation Method 1) Using the developer 1, a 10% character original of A4 size paper was laterally fed to continuously copy 30,000 sheets, and the following evaluation was performed. The experiment environment is
(1) and (2) are in a normal temperature and low humidity environment (23 ° C./5%, hereinafter referred to as “N / L environment”), and (3) and (4) are in a high temperature and high humidity environment (30 ° C./80). %, Hereinafter referred to as “H / H environment”).

(1) Image fog caused by poor charging was measured with a reflection densitometer. JISZ8722 (0 degree -4
Using a reflection densitometer (TC-6MC, Tokyo Denshoku Technical Center) based on a 5 degree method, the difference (%) before and after image formation was calculated and defined as fog density. Table 3 shows the evaluation levels. A fog of less than 2% was judged as having no practical problem.

[0152]

[Table 3] (2) The uniformity of chargeability was confirmed by fine line reproducibility. Table 4 shows the evaluation levels.

[0153]

[Table 4] (3) The state of toner scattering around the charging device 10 and in the vicinity of the exposure device 30 was visually observed, and image disturbance (fogging) due to toner scattering was evaluated. Table 5 shows the evaluation levels.

[0154]

[Table 5] (4) The occurrence of scratches on the photoreceptor was evaluated by visual evaluation and image quality. Table 6 shows the evaluation levels.

[0155]

[Table 6] (Evaluation Method 2) Developer 2
Was put into the developing device 10, and idle rotation was performed for 30 minutes using the above-described image forming apparatus. Thereafter, solid images having different densities are copied by variously changing the value of the developing bias of the image forming apparatus, and Sp68 SPECTROHOTO is copied.
The color space is measured for L ^* (lightness), a ^* (chromaticity (red-green)), and b ^* (chromaticity (yellow-blue)) using METER (X-Rite Inc), and L ^* Is 9
The value of b ^* at 2.80 ± 0.10 was defined as b1.

Next, the magnetic particles for charging were added to the developing device. As for the magnetic particles for charging, the developer 2 is used in an amount of 1 to 100 parts.
7 parts were added, and after the idle rotation for 30 minutes, similar image formation was performed. The color space was measured for the image, and L ^* was 9
The value of b ^* at 2.80 ± 0.10 is defined as b2, and b1-
The value of b2 was used as an index of a change in color due to the magnetic particles for charging. Table 7 shows the evaluation levels.

[0157]

[Table 7] Table 8 shows the evaluation results. As a result, N / L with severe charging
In the environment, the image fog was less than 0.5%, and the reproducibility of fine lines was good. H / H with severe tribo imparting property
In the environment, toner scattering was prevented, and no damage to the image carrier and no image disturbance occurred. In addition, vibration of the image carrier was suppressed, and noise was prevented.

Further, in the evaluation of color appearance change using the yellow developer, color appearance change was prevented and good quality color reproducibility was confirmed despite the magnetic particles produced by the pulverization method. As described above, toner scattering was prevented, and uniform charging and high image quality were achieved. Further, generation of ozone was suppressed as a whole as compared with the conventional charging device, and an excellent effect on environmental measures was obtained.

The magnetic particles for charging 1 were soxhlet-extracted with toluene and ethanol, concentrated and dried, and the extracted components were chemically analyzed by IR (infrared spectroscopy) and H-NMR. As a result, in the IR analysis, 3360 indicating nitrogen content was shown.
Peaks at cm ⁻¹ , 1590 cm ⁻¹ (NH ₂ , NH, respectively), and 1631 cm ⁻¹ (amide) were obtained. Furthermore, Si—O indicating the presence of a silane system at 1120 cm ⁻¹
A peak due to -Si was obtained. These characteristic peaks were equivalent to those measured when aminosilane (N- (2-aminoethyl) -3-aminopropyltrimethoxysilane) of the second coat layer material was used as a reference sample.

Also, 1101-1249 cm ⁻¹ , 171
0 cm ^-1, 1735 cm ^-1 peak indicating a carboxylic acid ester (carboxylate) is obtained, it was found that is detected acid IR from H-NMR is isopropyl ester. These characteristic peaks correspond to the T of the first coat layer material.
It was equivalent to the case where the i-type coupling agent (isopropoxytitanium tristearate) was measured as a reference sample.

Furthermore, since the central metals (Ti—O and Si—O) of the coupling agent were detected from ESCA,
The Ti-based coupling agent and aminosilane were confirmed by chemical analysis.

Next, methanol extraction was performed with time to investigate the elution rate of the aminosilane component (IR and nitrogen components were measured).
As a result, the difference was found between the magnetic particles for charging 20 manufactured by the simultaneous coating method and the difference due to the manufacturing method of the coating layer (two-step coating and simultaneous coating).

Example 22 The same evaluation as in Example 21 was performed, except that the charging magnetic particles 1 were changed to the charging magnetic particles 5. Table 8 shows the evaluation results. In Example 22, as in Example 21, excellent results were obtained in terms of uniform charging, prevention of toner scattering, and image quality.

Example 23 The same evaluation as in Example 21 was performed except that the magnetic particles for charging 1 were changed to the magnetic particles for charging 8. Table 8 shows the evaluation results. In Example 23, the same favorable results as in Example 21 were obtained except that a slight photoreceptor flaw which did not affect the image occurred.

Examples 24 to 27 Except that the charging magnetic particles 1 were changed to charging magnetic particles 2, 3, 4, and 6,
The same evaluation as in Example 21 was performed. Table 8 shows the evaluation results. In each of the examples, good results similar to those of the example 21 were obtained.

<Examples 28 to 31> Except that the charging magnetic particles 1 were changed to charging magnetic particles 7, 9, 10, and 11,
The same evaluation as in Example 21 was performed. Table 8 shows the evaluation results. In each of the examples, good results similar to those of the example 21 were obtained except that a slight damage to the photosensitive member without affecting the image occurred.

<Examples 32 and 33> Evaluations were made in the same manner as in Example 21 except that the charging magnetic particles 1 were changed to charging magnetic particles 12 and 13. Table 8 shows the evaluation results.
In each of the examples, the use of an acrylic resin instead of the coupling agent as the first coating agent of the magnetic particles for charging caused slight fog and toner scattering, but did not affect the image quality. Further, the change in color appearance was suppressed to a small level, and sufficient image quality was obtained in terms of quality.

Example 34 The same evaluation as in Example 21 was performed except that the magnetic particles for charging 1 were changed to the magnetic particles for charging 14. Table 8 shows the evaluation results. In Example 34,
By using silicone oil instead of the coupling agent as a coating agent for the first coating layer of the charging magnetic particles, slight fog and scratches on the photoreceptor were confirmed.

Example 35 The same evaluation as in Example 21 was performed, except that the magnetic particles for charging 1 were changed to the magnetic particles for charging 15. Table 8 shows the evaluation results. In Example 35,
By using an acrylic resin instead of a coupling agent as a coating agent for the first coating layer of the charging magnetic particles,
Although slight fogging and toner scattering occurred, no effect on the image quality was observed, and the change in color appearance was suppressed to a small level, and sufficient image quality was obtained.

Example 36 The same evaluation as in Example 21 was performed except that the charging magnetic particles 1 were changed to the charging magnetic particles 16. Table 8 shows the evaluation results. In Example 36,
Compared with Example 34, the use of N- (2-aminoethyl) -3-aminopropyltrimethoxysilane as a coating agent for the second coating layer of the magnetic particles for charging improved fog prevention and toner scattering prevention. Admitted.

Example 37 The same evaluation as in Example 21 was performed, except that the charging magnetic particles 1 were changed to the charging magnetic particles 17. Table 8 shows the evaluation results. In Example 37,
By using a silicone resin instead of a coupling agent as a coating agent for the first coating layer of the magnetic particles for charging, the reproducibility of fog and fine lines was reduced, but an image with a small change in color appearance was obtained as a whole. Was done.

Example 38 The same evaluation as in Example 21 was performed except that the magnetic particles for charging 1 were changed to the magnetic particles for charging 18. Table 8 shows the evaluation results. In Example 38, the change in color appearance was suppressed, and fog and toner scattering were suppressed to a level that did not affect the image quality, and an image with sufficient quality was obtained.

Example 39 The same evaluation as in Example 21 was performed, except that the charging magnetic particles 1 were changed to the charging magnetic particles 19. Table 8 shows the evaluation results. In Example 39,
Some color appearance change and image fogging occurred.

<Example 40> The same evaluation as in Example 21 was performed, except that the charging magnetic particles 1 were changed to the charging magnetic particles 20. Table 8 shows the evaluation results. In Example 40,
The image carrier was good in terms of flaws and color change, and fog and scattering were partially observed.

Comparative Example 1 The same evaluation as in Example 21 was performed except that the magnetic particles 1 were used instead of the magnetic particles 1 for charging. Table 8 shows the evaluation results. In Comparative Example 1, the toner was scattered and the image carrier was scraped, and the image quality was deteriorated.

<Comparative Production Example of Charging Magnetic Particles> 0.20 parts by mass of a polycarbonate resin per 100 parts by mass of magnetic particles 1 was simultaneously wet-processed at 100 ° C. while stirring with a toluene solvent in a coater. Coated. Further, the coat pot was heated to 120 ° C. and cured for 90 minutes. Thus, the magnetic particles for charging 21 were obtained.

<Comparative Example 2> The same evaluation as in Example 21 was performed except that the magnetic particles for charging 1 were changed to the magnetic particles for charging 21. Table 8 shows the evaluation results. As a result, toner scattering occurred, and the reproducibility of fine lines was reduced.

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[Table 8]

[0179]

According to the present invention, it is possible to provide magnetic particles for charging which are prevented from scattering of toner and scratches on the photoreceptor, and are excellent in chargeability and durability. In addition, by mounting the charging device carrying the magnetic particles for charging of the present invention in an image forming apparatus, it is possible to prevent a change in color appearance of the toner and achieve high image quality in addition to good charging performance and durability.

Further, according to the present invention, excellent image characteristics can be imparted even to an image forming apparatus using a developing and cleaning system, so that the generation of ozone in the charging step is suppressed, and environmental measures are taken. An excellent charging device and an excellent image forming apparatus can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a magnetic brush charging device using the magnetic particles for charging of the present invention.

FIG. 2 is a schematic diagram of an image forming apparatus using the charging device of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Charging device 11 Magnet roll 12 Electrode sleeve 13 Magnetic particle 14 Contact 15 Frame 20 Image carrier 30 Exposure device 40 Developing device 50 Transfer device 90 Charging member

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01F 1/06 H01F 1/06 K

Claims (27)

[Claims] 1. A charging magnetic particle that charges an image carrier by being rubbed on an image carrier on which an electrostatic latent image is formed, wherein the charging magnetic particle is a magnetic particle, Charging magnetic particles having a coat layer covering the particle surface, wherein the coat layer contains a nitrogen-containing material. 2. The magnetic particles for charging according to claim 1, wherein the coat layer contains at least two kinds of materials including the nitrogen-containing material. 3. The magnetic particles for charging according to claim 1, wherein the nitrogen-containing material is a material containing an amino group. 4. The magnetic particles for charging according to claim 3, wherein the material containing an amino group is a coupling agent having a metal selected from titanium, silicon, aluminum and zirconium as a central metal. 5. A charging magnetic particle that charges an image carrier by being rubbed on an image carrier on which an electrostatic latent image is formed, wherein the charging magnetic particle comprises a magnetic particle and the magnetic particle. A first coating layer covering the surface of the particles; and a second coating layer covering the surface of the first coating layer, wherein the second coating layer contains a nitrogen-containing material. particle. 6. The charging magnetic particle according to claim 5, wherein the nitrogen-containing material is a material containing an amino group. 7. The magnetic particles for charging according to claim 5, wherein the cure temperature of the first coat layer is higher than the cure temperature of the second coat layer. 8. The nitrogen-containing material containing an amino group,
7. A coupling agent containing a metal selected from titanium, silicon, aluminum and zirconium as a central metal.
Or magnetic particles for charging according to 7. 9. The charging magnetic particles according to claim 5, wherein the first coat layer contains a compound having an alkyl chain having 6 or more carbon atoms. 10. The magnetic particles for charging according to claim 9, wherein the compound having an alkyl chain having 6 or more carbon atoms is a coupling agent having a metal selected from titanium, silicon, aluminum and zirconium as a central metal. 11. A charging magnetic particle having a maximum chord length of 5 μm to 20 μm among the charging magnetic particles, wherein a ratio of a minor axis length to a major axis length (minor axis length / major axis length). The magnetic particle for charging according to any one of claims 1 to 10, wherein the standard deviation is 0.08 or more. 12. A charging member for charging an image carrier by rubbing the image carrier on which an electrostatic latent image is formed, wherein a magnetic force is applied to a magnet having a conductor to which a voltage is applied. A charging member comprising the magnetic particles for charging according to any one of claims 1 to 11 carried by the charging member. 13. The charging member according to claim 12, wherein said magnet body is a cylindrical conductive sleeve containing a magnet. 14. A charging device for charging an image carrier by rubbing the image carrier on which an electrostatic latent image is formed, wherein the charging device is provided on a magnet having a conductor to which a voltage is applied. A charging device, comprising: a charging member carrying the charging magnetic particles according to claim 1; and a power supply for applying a voltage to the magnet body. 15. The charging device according to claim 14, wherein the magnet body is a cylindrical conductive sleeve containing a magnet. 16. The charging device according to claim 14, wherein the voltage applied to the conductor is a DC voltage on which an oscillating voltage is superimposed. 17. The peak-to-peak voltage of the oscillating voltage is 100
17. The charging device according to claim 16, wherein the voltage is 0 V or less. 18. The image carrier according to claim 14, wherein the image carrier has a cylindrical conductive substrate, a photosensitive layer covering the surface thereof, and a charge injection layer formed on the surface of the photosensitive layer. The charging device according to Item. 19. The conductive substrate has a thickness of 0.5 mm or more.
19. The charging device according to claim 18, which is 3.0 mm. 20. An image carrier on which an electrostatic latent image is formed, and a magnet having a conductor to which a voltage is applied.
A charging device for charging the image carrier by bringing a charging member, which carries the magnetic particles for charging according to any one of claims 11 to 11 with a magnetic force, into contact with the image carrier, An exposure device that forms an electrostatic latent image by exposing a charged image carrier surface; a developing device that visualizes the electrostatic latent image formed on the image carrier surface with toner; And a transfer device for transferring the transferred image to a transfer material. 21. The image forming apparatus according to claim 20, wherein the magnet body of the charging device is a cylindrical conductive sleeve containing a magnet. 22. The image forming apparatus according to claim 20, wherein the voltage applied to the conductor of the charging device is a DC voltage on which an oscillating voltage is superimposed. 23. The peak-to-peak voltage of the oscillating voltage is 100.
23. The image forming apparatus according to claim 22, wherein the voltage is 0 V or less. 24. The image carrier according to claim 20, wherein the image carrier has a cylindrical conductive substrate, a photosensitive layer covering the surface thereof, and a charge injection layer formed on the surface of the photosensitive layer. Item 10. The image forming apparatus according to item 1. 25. The conductive substrate has a thickness of 0.5 mm or more.
The image forming apparatus according to claim 24, wherein the size of the image forming apparatus is 3.0 mm. 26. No independent cleaning device,
26. The image forming apparatus according to claim 20, wherein toner remaining on the image carrier after the transfer is performed by the transfer device is collected by a developing device. 27. An image forming apparatus for forming an image by visualizing an electrostatic latent image formed on an image carrier with a developer, and transferring the visualized image to a transfer material. 2. A process cartridge, comprising: a magnet body having a conductor to which a voltage is applied;
A charging member carrying the magnetic particles for charging according to any one of claims 11 to 11 by magnetic force, an image carrier for forming an electrostatic latent image, and an electrostatic latent image formed on the surface of the image carrier. A developing device that visualizes the toner with toner, and at least one selected from the group consisting of a cleaning device that removes residual toner on the image carrier after the image visualized by the toner is transferred to a transfer material. Characteristic process cartridge.