JP2002082515A - Electrifying device and electrophotographic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrifying device and an electrophotographic device where a stable image can be obtained over a long period of time in the electrophotographic device utilizing a magnetic brush electrifying device. SOLUTION: In the electrophotographic device, a magnetic brush electrifying device 11 is constituted to be provided with a conductive sleeve 16 that is provided with a magnetic roll and installed to be freely rotated and a magnetic brush electrifying member provided with magnetic particles 15 forming the magnetic brush by being carried on a surface of a conductive sleeve 16 and a metallic soap member 20 containing metallic soap and installed in a position where the metallic soap is brought into contact with the magnetic brush and this is mounted on the electrophotographic device.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming method using a charging device for charging a photoreceptor, and more particularly to a charging device and an electrophotographic apparatus used for forming an image such as a copying machine, a printer, and a facsimile.

[0002]

2. Description of the Related Art Conventionally, many methods have been known as electrophotography. In general, a photoconductive substance is used to form an electric latent image on a photoreceptor by various means. The latent image is developed into a visible image by developing with toner, and the toner image is transferred to a transfer material such as paper as necessary, and then the toner image is fixed on the transfer material by heat and pressure to obtain a copy. Things. Further, toner particles remaining on the photoconductor without being transferred onto the transfer material are removed from the photoconductor by a cleaning process.

As a charging means in such an electrophotographic method, a so-called corotron or scorotron, which utilizes a corona discharge, has been used. In the corona discharge, a large amount of corona is generated particularly when a negative or positive corona is generated. Since the ozone is generated, it is necessary to provide a filter for capturing ozone in the electrophotographic apparatus, and there have been problems such as an increase in the size of the apparatus and an increase in running cost.

As a technique for solving such a problem, a charging member such as a roller or a blade is brought into contact with the surface of a photoreceptor to form a narrow space in the vicinity of the contacting portion, and interpreted according to the so-called Paschen's law. A charging method has been developed in which the generation of ozone is suppressed as much as possible by forming a discharge that can be performed. For example, JP-A-57-178257, JP-A-56-104351, and JP-A-58-4
This technology is known in Japanese Patent Application Laid-Open Nos. 0566, 58-139156 and 58-150975.

However, in a system in which charging is performed by contacting with a photoreceptor, such as a blade or roller charging system, a problem such as fusion of toner on the photoreceptor tends to occur.

[0006] For this reason, a method of using a photoconductor in close proximity to the photoconductor to avoid direct contact has been studied. As the member for charging the photoreceptor, the roller, the blade,
A brush and a member formed by applying a resistive layer to an elongated conductive plate-like material may be used. However, in this case, there is a problem that it is difficult to control a close distance, and there is a problem in practical use.

For this reason, a technique of using a so-called magnetic brush in which a magnetic particle having a relatively small contact load to a photoreceptor is held by a magnet body as a charging member has been studied.

For example, Japanese Patent Application Laid-Open No. 59-133569 discloses a method in which particles coated with iron powder are held on a magnet roll and charged by applying a voltage.
Japanese Patent No. 116674 discloses a charging device to which an alternating current having a direct current is applied. Further, in order to improve environmental dependency and the like,
JP-A-7-72667 discloses coating with a styrene acrylic resin or the like.

However, the remaining problem of these techniques is that it is difficult to obtain a stable charging property during continuous use. For example, as disclosed in Japanese Patent Application Laid-Open No. H06-301265, a magnetic brush has been proposed. There has been proposed a configuration in which toner is replenished so as to keep the amount of toner present therein constant, thereby stabilizing resistance. All of the above methods use a discharge phenomenon in a minute gap, and have a problem that the surface of the photoreceptor is damaged by a product generated by the discharge, and the image is likely to be deteriorated or image flow under high temperature and high humidity. It still remained.

As a new attempt, a voltage is applied to a contact conductive member such as a charging roller, a charging brush, or a charging magnetic brush,
There is a method of injecting charges into trap levels on the surface of the photoreceptor to perform contact injection charging.

In Japanese Patent Application Laid-Open No. 08-106200, the use of an image carrier having a charge injection layer and a charging device having a magnetic brush having a specific resistance value allows the contact to satisfy charging properties and pinhole leak. Injection charging has been proposed, and as a feature thereof, there is no discharge starting point due to a discharge phenomenon, and a configuration capable of obtaining a charging potential substantially linearly with applied voltage has been proposed.

In the cleaning process, blade cleaning, fur brush cleaning, roller cleaning and the like have been conventionally used. In either method, transfer residual toner is mechanically scraped off or dammed and collected in a waste toner container. Therefore, there has been a problem that such a member is pressed against the surface of the photoconductor. For example, it has been mentioned that a photosensitive member is worn by strongly pressing a member to shorten the life of the photosensitive member. On the other hand, from the viewpoint of the apparatus, the provision of such a cleaning apparatus inevitably increases the size of the apparatus, which has been a bottleneck when aiming for a more compact apparatus.

[0013] For the above reasons, a system free of waste toner in terms of effective use of toner has been desired from the viewpoints of device miniaturization and ecology. As a technique for realizing such a system, a technique called simultaneous development cleaning or cleanerless is known.

Conventionally, a technique called "simultaneous development cleaning" or "cleanerless" is disclosed in JP-A-59-1335.
No. 73, JP-A-62-203182, JP-A-63-133179, JP-A-64-20587, JP-A-2-51168, JP-A-2-302
772, JP-A-5-2287, JP-A-5-287
2289, JP-A-5-53482 and JP-A-5-61383. These known techniques use a corona, a brush, or a roller, and there is still room for study to satisfy all of the contamination of the photoreceptor surface due to discharge products, nonuniform charging, and the like.

For this reason, a cleaner-less technique using a so-called magnetic brush, which holds magnetic particles having a relatively small contact load on the photosensitive member with a magnet body, as a charging member has been studied.

An example of the cleanerless technique will be described with reference to FIG. FIG. 5 is a schematic view showing an example of an electrophotographic apparatus using a cleanerless technique. The electrophotographic apparatus includes a photoreceptor 12, a magnetic brush charger 11 that is a charging device that contacts the photoreceptor 12, and charges the photoreceptor 12, and forms an electrostatic latent image on the charged photoreceptor by image exposure. And a developing device 18 for visualizing the electrostatic latent image with toner, and a transfer device 14 for transferring the obtained toner image to a transfer material. Further, the electrophotographic apparatus includes a registration roller 4 for supplying a transfer material with good timing, and a fixing device 19 for fixing a non-fixed image transferred to the transfer material.

The magnetic brush charger 11 has a non-magnetic conductive sleeve 16 having a magnet body and rotatably provided, and magnetic particles 15 carried on the surface of the conductive sleeve to form a magnetic brush. It has a magnetic brush charging member and a power supply for applying a voltage to the magnetic brush charging member. The developing device 18 includes a developing container for storing the developer (toner) 10, a non-magnetic and conductive developing sleeve 17 rotatably provided at an opening of the developing container and having a magnet, and a developing sleeve 17. And a power supply for applying a voltage to the power supply.

The photosensitive member 12 is charged by a magnetic brush charger 11 composed of a conductive sleeve 16 coated with magnetic particles 15. Charged photoconductor 12
A latent image is formed by the exposing means 13. The latent image is reversely developed by the developing device 18 to form a visualized image on the exposed portion of the photoconductor 12 with toner.

The visualized image is transferred to a transfer material by a transfer means 14, and the transfer material having received the toner image is transferred to the fixing device 1.
9, and is heated and fixed, but the toner remaining after transfer exists on the photoconductor 12. The toner remaining after the transfer is affected by the transfer, and the charge polarity is variously distributed from minus to plus. The magnetic brush charger 11 can scrape such transfer residual toner while rotating and sliding with respect to the photoconductor 12, and charge the photoconductor 12 to make the toner polarity uniform to a desired toner polarity.

As a development method, reversal development is used.
When the reversal development is used, the image exposure part (bright part potential part) is developed, but the bias applied to the developing sleeve 17 is located between the photosensitive member non-exposure part and the exposure part potential,
With respect to the negative polarity toner existing on the non-exposed portion (dark portion potential portion), electrostatic force attracting to the developer side is actuated, so that the toner remaining after transfer can be collected. A force remaining on the surface of the photoreceptor acts on the negative polarity toner existing on the exposed portion, but it is a portion where a toner image is originally formed, and does not cause a problem.

Regarding such cleanerless technology,
For example, Japanese Patent Application Laid-Open No. H04-21873 proposes an image forming apparatus which does not require a cleaning device by using a magnetic brush to which an AC voltage having a peak value exceeding a discharge limit value is applied. In addition,
Japanese Patent Application Laid-Open No. 6-118855 proposes an image forming apparatus equipped with a magnetic brush charging / cleaning device without an independent cleaning device.

However, in the cleaner-less device, a cleaning device dedicated to the transfer residual toner is not provided, and the cleaning device passes through the charger and is collected and reused by the developing device. In comparison, the amount of toner mixed into the charger significantly increases. In the case of a magnetic brush charger, if the amount of transfer residual toner increases significantly, toner that cannot be collected by the charger is scattered, fog due to insufficient control of the triboelectric charge polarity on the transfer residual toner, and toner adhesion to magnetic particles. For this reason, a phenomenon such as a decrease in the charged potential of the photoreceptor surface due to an increase in the resistance of the charger and a potential non-uniformity may occur, and image defects such as fogging and density non-uniformity may occur on an image.

In order to improve the durability of the contact injection charging method using magnetic particles, Japanese Patent Application Laid-Open No. 08-6355 proposes mixing of magnetic particles having a smooth surface and magnetic particles having an uneven surface. Japanese Patent Application Laid-Open No. 08-69156 discloses a method of forming a resin layer on the surface of magnetic particles for charging,
Japanese Patent Application Laid-Open No. 08-69149 proposes a configuration in which the particle size distribution of the magnetic particles for charging has a plurality of peaks. However, in recent years, there has been a demand for further extending the life of the charging device, and there has been an increasing need to consider not only improving the composition and characteristics of the magnetic particles but also improving the durability by improving the structure of the charger.

[0024]

As described above, there has been a demand for a structure of a magnetic brush charger having stable charging characteristics during continuous use as a charging device. Also in a cleanerless system, there has been a demand for a method in which the charging characteristics are stable for a long period of time and the transfer residual toner is suitably treated. Further, there has been a demand for an apparatus which causes less toner scattering from the magnetic brush charger.

An object of the present invention is to provide a charging apparatus and an electrophotographic apparatus which can obtain a stable image for a long time in an electrophotographic apparatus using a magnetic brush charger.

[0026]

In order to achieve the above object, the present invention provides a photosensitive member, a charging device for contacting the photosensitive member and charging the photosensitive member, and a method for statically charging the charged photosensitive member by image exposure. A charging device for use in an electrophotographic apparatus, comprising: an exposure unit that forms an electrostatic latent image; a developing device that visualizes the electrostatic latent image with toner; and a transfer unit that transfers the obtained toner image to a transfer material. A conductive sleeve having a magnet body and rotatably provided, and a magnetic brush charging member having magnetic particles carried on the surface of the conductive sleeve to form a magnetic brush; and a metal soap including metal soap. A charging device characterized by being a magnetic brush charger having a metal soap member provided at a position in contact with the magnetic brush.

Further, the present invention provides a photosensitive member, a charging device that contacts the photosensitive member and charges the photosensitive member, an exposure unit that forms an electrostatic latent image on the charged photosensitive member by image exposure, In an electrophotographic apparatus having a developing device for visualizing a latent image with toner and a transfer unit for transferring the obtained toner image to a transfer material, the charging device is a conductive sleeve having a magnet and provided rotatably. And a magnetic brush charging member having magnetic particles carried on the surface of the conductive sleeve to form a magnetic brush, and a metal soap member including metal soap and provided at a position where the metal soap contacts the magnetic brush. Provided is an electrophotographic apparatus, which is a magnetic brush charger.

Further, in the charging device and the electrophotographic device of the present invention, the surface of the magnetic particles is treated with a coupling agent whose central element having an alkyl chain having 6 or more carbon atoms is titanium, silicon, aluminum, or zirconium. It is preferable that the total amount of the coupling agent is 0.0001% by mass or more and 0.5% by mass or less based on the magnetic particles.

In the charging device and the electrophotographic apparatus according to the present invention, the magnetic particles may have a volume resistivity of 1 × 10 ⁴ Ωcm or more.
It is preferably at most 10 ⁹ Ωcm.

Further, in the charging device and the electrophotographic device of the present invention, it is preferable that the average particle size of the magnetic particles is 5 μm or more and 100 μm or less.

Further, in the charging device and the electrophotographic apparatus of the present invention, the photosensitive member may be a conductive support, a photosensitive layer formed on the conductive support, and a photosensitive layer which is located farthest from the conductive support. The charge injection layer preferably has a volume resistivity of 10 ⁸ Ωcm or more and 10 ¹⁵ Ω.
cm or less.

Further, in the charging device and the electrophotographic device of the present invention, it is preferable that the charge injection layer contains conductive fine particles and a binder resin.

In the charging device and the electrophotographic device according to the present invention, it is preferable that the charge injection layer contains a lubricant powder.

Further, in the charging device and the electrophotographic device of the present invention, it is preferable that the lubricant powder is a fluorine resin, a silicone resin, or a polyolefin resin.

In the charging device and the electrophotographic apparatus of the present invention, the toner remaining on the surface of the photoreceptor after the transfer step is held in a magnetic brush, and the toner is moved onto the photoreceptor by the magnetic brush during non-image formation. It is preferable that the toner is collected by a developing device and reused.

Further, the charging device and the electrophotographic apparatus of the present invention have a power supply for applying a voltage to the magnetic brush charging member, and the voltage applied to the magnetic brush charging member is changed so that the non-image forming operation is performed. It is preferable to move the toner onto the photoreceptor by using a magnetic brush.

In the charging device and the electrophotographic device of the present invention, it is preferable that the toner is a toner generated by a polymerization method.

Further, in the charging device and the electrophotographic device of the present invention, the shape factor SF-1 of the toner is 100 to 140;
Preferably, SF-2 is from 100 to 120.

In the charging device and the electrophotographic apparatus according to the present invention, the magnetic particles are premixed with a metal soap powder having a mixing amount of 0.005% by mass or more and 10% by mass or less with respect to the magnetic particles. Is preferred.

Further, in the charging device and the electrophotographic device of the present invention, the metal soap powder has an average particle size of 0.1 μm or more and 20 μm or more.
It is preferably in the range of μm or less. Hereinafter, the present invention will be described in more detail.

[0041]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A charging device according to the present invention is a magnetic device having a conductive sleeve having a magnet body and rotatably provided, and magnetic particles formed on a surface of the conductive sleeve to form a magnetic brush. A magnetic brush charger including a brush charging member and a metal soap member including a metal soap and provided at a position where the metal soap contacts the magnetic brush.
Since the metal soap member is placed in contact with the magnetic brush charger with a contact pressure, a part of the metal soap member is pulverized and mixed into the magnetic brush. Therefore, the present invention is characterized in that metal soap powder which has been finely powdered by repeated image formation is continuously supplied into the magnetic brush.

Metallic soap is generally used as a lubricant,
In the field of electrophotography, photoconductors, transfer belts,
It is used as an external additive or the like of toner, and is expected to have an effect of preventing adhesion contamination of toner, paper powder, and the like.

The charging device is disclosed in, for example, JP-A-06-342.
Japanese Patent Publication No. 234 proposes a method in which zinc stearate is applied as a lubricant onto a charging roller as needed on the surface of the charging roller. However, in the case of a charging roller, unevenness is likely to occur at the time of application, and since there is no process for making the application unevenness uniform,
There is a great possibility that this portion will cause charging unevenness and cause an image defect.

On the other hand, in the case of the magnetic brush charger, since the magnetic particles repeatedly contact and collide with each other in the charger, even when coating (adhesion) unevenness occurs, the unevenness is uniformly stretched between the particles and the charging is performed. The device as a whole has an advantage that charging unevenness hardly occurs. Further, even when the shape of the shaving powder from the metal soap member varies, the shape is made uniform by the same phenomenon.

From the viewpoint of toner adhesion, the surface of the magnetic particles can be uniformly coated with the metal soap powder, and the magnetic brush can be used as needed by repeated image formation. Exhibits an excellent toner adhesion prevention effect. Further, since the fluidity of the magnetic particles is greatly improved, the ability of the toner mixed in the magnetic brush to be discharged to the photoconductor is also improved.

In particular, the present inventors have found that the effect of forcibly discharging mixed toner by varying the applied voltage during non-image formation is significantly greater than that of the conventional configuration. Therefore, even when image formation is repeatedly performed, the configuration of the present invention is hardly affected by the mixed toner, and the initial state of the charging device can be maintained.

Further, the metal soap powder which cannot be held by the magnetic brush moves to the photoreceptor side. The presence of these powders on the photoreceptor alleviates the friction between the photoreceptor and the magnetic brush and reduces the toner. Since the effect of preventing fusion is also exhibited, the photosensitive member is abraded and deteriorated due to scratches, and the life of the photosensitive member can be promoted at the same time.

FIGS. 1 to 3 show an example of the charging device of the present invention mounted on an electrophotographic apparatus. In the charging device of the present invention, a roller-shaped metal soap member 20 made of metal soap, which is a feature of the present invention, is arranged in contact with a magnetic brush charging member constituted by a magnet-containing nonmagnetic conductive sleeve 16 coated with magnetic particles 15. I do. The magnetic brush charger 11, which is a charging device of the present invention, is disposed at a position where the magnetic brush contacts the photoconductor 12, and charges the photoconductor 12 by a charging method such as an injection charging method or a charging method using discharge.

The metal soap member 20 is connected to the frame of the magnetic brush charger 11 via a pressure spring. The pressure spring is a spring whose extension direction is a biasing direction, and the metal soap member 20 contacts the magnetic brush charging member with a constant contact pressure by the pressure spring. In the present embodiment, the configuration is such that the urging by the pressure spring is performed in order to make the scraping amount of the metal soap member almost constant, but the metal soap member is not limited if the metal soap is in contact with the magnetic brush charging member. Further, in the present invention, other members such as a frame for holding metal soap may be provided. Further, in the present embodiment, the urging by the pressure spring is performed in order to make the scraping amount of the metal soap member substantially constant. However, when the metal soap member is urged and installed, the urging means is used. Is not limited to a pressing spring, and various known pressing means represented by an elastic member or the like can be used.

If the metal soap member in the charging device is located at a position in the charging device that does not affect image formation, it does not depend on the arrangement position and does not affect its effect. The shape of the metal soap member is not particularly limited as long as it is a shape that abuts the magnetic brush almost uniformly along the longitudinal direction of the conductive sleeve. For example, the metal soap member processed into a roller shape shown in FIG. 34, the square-shaped member shown in FIG. 3 or the metal soap member 44 processed into a blade shape can be exemplified.

The charging device of the present invention may have a structure in which metal soap powder, which is a particle made of finely powdered metal soap, is previously mixed into magnetic particles. By mixing the metal soap powder in the magnetic particles in advance, it is possible to further reduce the toner adhesion at the initial stage of image formation. The mixing amount of the metal soap powder is 0.005% by mass or more with respect to the magnetic particles.
It is preferably in the range of not more than mass%. When the content is 0.005% by mass or less, it is difficult to sufficiently suppress toner adhesion at the initial stage of image formation, and it is difficult to exert the effects of the present invention. When the content is 10% by mass or more, the metallic soap powder cannot be held by the magnetic brush, and the fine powder may be scattered in the apparatus.

The average particle size of the metal soap powder is 0.1%.
It is preferably in the range of not less than μm and not more than 20 μm.
When it is 0.1 μm or less, the metal soap powder leaks more easily than the magnetic brush, and when it is 20 μm or more, it is difficult to mix the metal soap powder with the magnetic particles, so that it becomes difficult to make the metal soap powder uniform in the magnetic brush.

As the metal soap used for the metal soap member and the metal soap powder, various ones can be used. For example, cadmium stearate, zinc stearate, barium stearate, calcium stearate, aluminum stearate can be used. , Magnesium stearate, sodium stearate, lead stearate, zinc stearate, magnesium stearate, zinc laurate, sodium palmitate, barium myristate, and the like. The same or different materials are selected for the metal soap member placed in contact with the magnetic brush and the metal soap powder to be mixed in the magnetic particles in advance.

Various types of magnetic particles can be used as the magnetic particles used in the present invention. For example, magnetic particles used as a charging member for electrophotography can be applied to an applied voltage in view of image stability and quality. On the other hand, it is preferable to obtain a stable electric potential even in a wide range of environments and usage conditions. For example, strontium, barium, so-called hard ferrites such as rare earth, or magnetite, copper, zinc, nickel,
Ferrite such as manganese is used. These can be used alone or in combination.

The magnetic particles used in the present invention preferably have a volume resistance of 1 × 10 ⁴ Ωcm or more and 1 × 10 ⁹ Ωcm or less. Volume resistance of magnetic particles is 1 × 10 ⁴ Ωc
If it is lower than m, a pinhole leak tends to occur.
If it exceeds × 10 ⁹ Ωcm, the charging of the photoconductor tends to be insufficient.

The volume resistance of the magnetic particles can be measured by a so-called tablet method using a measuring device shown in FIG. To measure the volume resistance of the magnetic particles, the measurement cell A is filled with magnetic particles as a measurement sample, electrodes 51 and 52 are arranged so as to be in contact with the magnetic particles, a voltage is applied between the electrodes, and a current flowing at that time is measured. Obtained by measurement. The measurement conditions are as follows: the contact area between the filled magnetic particles and the electrode is 2 cm ² , the thickness is 1 mm, the load on the upper electrode is 10 kg, and the applied voltage is 100 V in an environment of 23 ° C. and 65%.

Further, the average particle size of the magnetic particles is 5 μm or more and 10
It is preferably 0 μm or less. When the average particle size of the magnetic particles is less than 5 μm, the magnetic particles are likely to leak from the charger, and when the average particle size exceeds 100 μm, uneven charging becomes noticeable.

In particular, in the injection charging method, since charging is performed only by contact, in particular, the average particle diameter of the magnetic particles is 50 μm or less in order to increase the contact probability and ensure sufficient photoreceptor chargeability. Preferably, it is more preferably 35 μm or less.

On the other hand, in the charging method using discharge, the average particle size of the magnetic particles is preferably at least 40 μm, more preferably at least 50 μm. 40 μm
When a smaller magnetic particle is used in a charging method using electric discharge, a voltage higher than the discharge starting point is constantly applied between the charged magnetic brush and the photoconductor, so that the magnetic particle tends to fall off from the charger. That's why.

Further, from the viewpoint of toner scattering from the magnetic brush charger, the charging method using discharge requires a substantially high AC electric field, so that the magnetic particles vibrate violently. Since the magnetic particles have a large particle diameter, they tend to be slightly inferior to the injection charging method in preventing the scattering of toner and magnetic particles.

The average particle size of the magnetic particles was determined using a laser diffraction type particle size distribution analyzer HEROS (manufactured by JEOL Ltd.).
The range of 05 μm to 200 μm was measured by 32 logarithmic division, and the average particle size was defined as the 50% volume average particle size.

The average particle diameter of the metal soap powder used in the present invention was randomly extracted by an electron microscope at least 100 pieces, the maximum horizontal chord length was used as the particle diameter, and the total horizontal maximum chord length was measured. The average particle diameter of the particle-shaped product is divided by the number of particles obtained.

In the present invention, the magnetic particles have 6 carbon atoms.
It is preferable to be treated with a coupling agent having a configuration in which the above alkyl chain and furthermore, a configuration in which 6 or more carbon atoms are linearly connected. Since the magnetic particles are rubbed tightly with the photoreceptor, especially for the anti-organic photoreceptor, there is a severe condition in the shaving. By including the configuration of the present invention,
It has an effect on photoreceptor damage and also has an effect on the environment dependency of magnetic particles. Particularly, when the surface layer of the photoreceptor is made of an organic compound, it has a remarkable effect.

The coupling agent used in the present invention includes an alkyl group having 6 or more carbon atoms in the hydrophobic group,
More preferably, the central element such as titanium, aluminum, silicon, and zirconium is not particularly limited as long as it includes a configuration connected in a straight chain. The coupling agent in the present invention has a hydrolyzable group that can be hydrolyzed in the same molecule and a hydrophobic group containing the alkyl group and the like as described above, and silicon, aluminum, titanium, zirconium, and the like as preferable central elements. Compounds bonded to the central element of are shown.

As the hydrolyzable group, for example, an alkoxy group having a relatively high hydrophilicity such as a methoxy group, an ethoxy group, a propoxy group and a butoxy group is used. In addition, an acryloxy group, a methacryloxy group, a modified form thereof, and the like are also used.

The hydrophobic group may be any as long as it has a structure in which six or more carbon atoms are linearly linked in its structure. In the form of bonding with the central element, carboxylic acid esters, alkoxy, sulfone An acid ester, a phosphoric ester or a direct bond may be formed. Further, the structure may contain a functional group such as an ether bond, an epoxy group, or an amino group.

From this point of view, the alkyl group in the coupling agent needs to have 6 or more, preferably 8 or more carbons connected in series, and up to about 30 carbons can be used as the coupling agent used in the present invention. Conceivable. When the number of alkyl groups exceeds 30, the coupling agent tends to be insoluble in the solvent, it is difficult to uniformly treat the surface of the magnetic particles, and the fluidity of the treated magnetic particles is extremely deteriorated, The chargeability tends to be non-uniform.

The amount of the coupling agent is preferably 0.0001% by mass or more and 0.5% by mass or less based on the magnetic particles. If the amount is less than 0.0001% by mass, the effect of the coupling agent may not be obtained, and if it exceeds 0.5% by mass, the fluidity of the magnetic particles may be deteriorated and the magnetic particles may not be practically used. In this sense, more preferably, 0.1.
A coupling agent in an amount of from 001% by mass to 0.2% by mass can be preferably used.

In the present invention, it is basically desirable that the surface of the magnetic particles is composed of only a coupling agent, but it is also possible to coat a small amount of a resin component together if necessary. When a resin is used in combination, it is preferable that the amount of the resin used in combination with the amount of the coupling agent be equal to or less than the amount of the coupling agent and the weight loss on heating be 0.0001 to 0.5% by mass. Can be maintained. Here, the heating loss refers to a weight loss from 150 ° C. to 800 ° C. in a nitrogen atmosphere in the analysis using a thermobalance.

In the charging device of the present invention, it is also possible to use a combination of the magnetic particles subjected to the coupling treatment and the magnetic particles coated with the resin. The mixing ratio in that case is preferably 50% by mass or less based on the mass of the magnetic particles in the charger. 50
If the amount is more than 30% by mass, the effect of the magnetic particles tends to be weak. Also,
The magnetic particles used in the present invention preferably have a heating loss of 0.5% by mass or less, more preferably 0.2% by mass or less.
% By mass or less.

The conductive sleeve used in the charging device of the present invention is not particularly limited as long as it is a cylindrical body having conductivity, but is preferably non-magnetic. As a material of such a conductive sleeve, for example, aluminum,
Metals such as nickel, stainless steel, steel, etc., non-conductive substances such as plastics, conductive particles are dispersed, or conductive film is formed on the surface by plating, etc. Examples include a magnet roll.

The magnet used in the charging device of the present invention is
There is no particular limitation as long as it can attract and carry an appropriate amount of magnetic particles on the conductive sleeve. As a preferred form of the magnet body, for example, a magnet roll or the like installed in a conductive sleeve can be exemplified.

[0073] The amount of the magnetic particles held on an electroconductive sleeve, preferably, 50 to 500 mg / cm ^2, more preferably from 100 to 300 mg / cm ^2. It is preferable that the magnetic particles be carried on the conductive sleeve in such a range, since stable charging properties can be obtained in charging the photoconductor. The amount of the magnetic particles can be adjusted by the type of the magnetic particles used, the magnetic force and the arrangement of the magnet body, and the like.

The power supply used in the charging device of the present invention may be any of a DC power supply, an AC power supply, and a power supply capable of applying both DC and AC voltages. When using the injection charging method, the charging bias applied to the magnetic brush charging member may be only a DC component, but if a slight AC component is applied, the image quality is improved. As the AC component, depending on the process speed of the apparatus, at a frequency of about 100 Hz to 10 kHz, the peak-to-peak voltage of the applied AC component is:
It is preferably about 1000 V or less. If the voltage exceeds 1000 V, the photosensitive member potential is obtained with respect to the applied voltage, so that the latent image surface may undulate in potential, causing fogging and light density.

In the method using discharge, the alternating current component depends on the process speed of the apparatus.
At a frequency of about z to 10 kHz, the peak-to-peak voltage of the applied AC component is about 1000 V or more, and preferably twice or more the discharge starting voltage. This is for obtaining a sufficient leveling effect on the magnetic brush and the surface of the photoconductor. As a waveform of the applied AC component, a sine wave, a rectangular wave, a sawtooth wave, or the like can be used.

Further, in the charging device of the present invention, extra magnetic particles may be held and circulated in the charging device. Such a configuration is preferable in that rapid deterioration of the magnetic particles is prevented and good and stable charging of the photoconductor is realized. Such a configuration includes, for example, installation of stirring means for stirring the magnetic particles in the charging device, a supply chamber storing new magnetic particles, and supply of the magnetic particles from the supply chamber to the charging device according to predetermined conditions. And a replenishing means.

Next, the electrophotographic apparatus of the present invention will be described. The electrophotographic apparatus of the present invention is a photoconductor, a charging device that contacts the photoconductor and charges the photoconductor, an exposure unit that forms an electrostatic latent image on the charged photoconductor by image exposure,
A developing device for visualizing the electrostatic latent image with toner,
An electrophotographic apparatus having a transfer unit for transferring the obtained toner image to a transfer material, wherein the charging device is the above-described magnetic brush charger.

FIG. 1 shows an example of the electrophotographic apparatus of the present invention. The electrophotographic apparatus shown in FIG. 1 includes a photoconductor 12, a magnetic brush charger 21, an exposure unit 13, a developing unit 18, and a transfer unit 1.
4, a registration roller 4, a fixing device 19, and the like.

In the electrophotographic apparatus, the photosensitive member 12 includes a conductive support, a photosensitive layer formed on the conductive support,
If the photosensitive layer has a charge injection layer formed farthest from the conductive support, a charging potential of 80% or more, and more preferably 90% or more with respect to the DC applied voltage can be obtained. Therefore, it is possible to realize a further ozone-less charging method as compared with a charging method interpreted according to Paschen's law, such as a charging method using discharge.

Specifically, the most distant from the conductive support is
Conditions that do not cause sufficient chargeability and image deletion
In order to satisfy, the volume resistance value is 1 × 10⁸Ωcm ~ 1 ×
10^{1 Five}A photoreceptor provided with a charge injection layer in the range of Ωcm
Is to use. More preferably, such as image flow
Volume resistance value is 1 × 10 from the point^TenΩcm-1 × 10^FifteenΩc
m, the volume resistance value is 1 × 10 in consideration of environmental fluctuations.
¹¹Ωcm-1 × 10¹⁴Ωcm charge injection layer
Is preferred. The volume resistivity of the charge injection layer is 1 × 10⁸Ωc
If it is smaller than m, the electrostatic latent image cannot be
Image deletion tends to occur in a high humidity environment.
× 10^FifteenIn case of larger than Ωcm, charge from charging member
Is not received enough, and tends to cause poor charging.
is there.

In the present invention, the charge injection layer preferably contains conductive fine particles and a binder resin. That is, the charge injection layer can be made of a material having a medium resistance by dispersing an appropriate amount of light-transmitting and conductive conductive fine particles in an insulating binder resin, and having the above-described resistance. Forming an inorganic layer is also an effective means. By providing such a functional layer surface on the photoreceptor, it serves to hold the charge injected from the charging member, and further, the charge injection layer plays a role in releasing this charge to the conductive support during image exposure. To reduce the residual potential of the photoconductor. By providing this charge injection layer, an injection charging method can be realized.

Here, the volume resistance of the charge injection layer is determined by using polyethylene terephthalate (PE) having a conductive film deposited on the surface.
T), a charge injection layer was formed, and a volume resistance measuring device (4140BpAMATE manufactured by Hewlett-Packard Company) was formed on the charge injection layer.
R), a voltage of 100 V was applied in an environment of 23 ° C. and 65% to perform measurement.

The particle size of the conductive fine particles dispersed in the charge injection layer is preferably 0.3 μm or less from the viewpoint of light transmission, and most preferably 0.1 μm or less. The compounding amount of the conductive fine particles is 2 to 250% by mass, preferably 2 to 190% by weight based on 100% by mass of the binder resin. If the amount of the conductive fine particles is less than 2% by mass, it is difficult to obtain a preferable volume resistance value. If the amount exceeds 250% by mass, the film strength tends to decrease, and the charge injection layer tends to be easily scraped. The thickness of the charge injection layer is preferably 0.1 to 10 μm.
m, more preferably 1 to 7 μm.

Preferably, the charge injection layer contains a lubricant powder. Expected effects include a reduction in friction between the photosensitive member and the magnetic brush charging member during charging, an increase in the nip involved in charging, and an improvement in charging characteristics. In addition, since the releasability of the photoreceptor surface is improved, magnetic particles are less likely to adhere. Particularly, 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 preferably, a tetrafluoroethylene resin is used.

When the lubricant powder is contained and dispersed in the charge injection layer, the amount of the lubricant powder is preferably 2 to 50% by mass, more preferably 5 to 40% by mass based on 100% by mass of the binder resin. % By mass. If the amount of the lubricant powder is less than 2% by mass, the amount of the lubricant powder is insufficient, so that the effect of improving the chargeability of the photoreceptor is not sufficient, and the transfer residual toner tends to increase from the viewpoint of a cleanerless device. If the amount of the lubricant powder exceeds 50% by mass, the resolution of the image and the sensitivity of the photoreceptor tend to decrease.

When an inorganic layer is coated as a surface layer (charge injection layer), the underlying photoconductive layer (photosensitive layer) is preferably amorphous silicon, and is formed by a known technique such as glow discharge. It is preferable to sequentially form various layers such as a blocking layer, a photoconductive layer, and a charge injection layer on a cylinder (conductive support).

As the photosensitive layer, conventionally known ones can be used. For example, as an organic material, a phthalocyanine pigment, an azo pigment and the like can be mentioned.

Further, an intermediate layer may be provided between the surface protective layer and the photosensitive layer. The purpose of such an intermediate layer is to enhance the adhesion between the protective layer and the photosensitive layer, or to function as a charge barrier layer. As the intermediate layer, for example, commercially available resin materials such as epoxy resin, polyester resin, polyamide resin, polystyrene resin, acrylic resin, and silicone resin can be used.

Examples of the conductive support for the photoreceptor include metals such as aluminum, nickel, stainless steel, and steel, plastics or glass having a conductive film, and conductive paper.

In the electrophotographic apparatus of the present invention, the above-described charging device for charging the photosensitive member by contacting the photosensitive member is used. The closest gap between the conductive sleeve of the magnetic brush charger and the photosensitive member is preferably 0.3 mm to 2.0 mm. If the gap is less than 0.3 mm, depending on the applied voltage, a leak may occur between the conductive sleeve and the photoconductor, possibly damaging the photoconductor.

The magnetic brush charging member may be moved in the opposite direction with respect to the moving direction of the photoreceptor, regardless of the direction in which the magnetic brush charging member moves. Preferably, it moves in the opposite direction to the body.

The photosensitive member 12 is charged by the charging device described above. At this time, from the power supply of the charging device, for example, an alternating voltage in which an AC component is superimposed on a DC voltage is applied to the magnetic brush charging member as a charging bias. The charged photoreceptor 12 is image-exposed by the exposing means 13 to form an electrostatic latent image. As the exposure unit 13, a laser, an LED,
And other known means.

The electrostatic latent image formed on the photoreceptor 12 on which the electrostatic latent image is formed is visualized by the developing device 18, and a toner image corresponding to the electrostatic latent image is formed on the photoreceptor 12. Developing device 1
Reference numeral 8 is not particularly limited, and a known developing device that realizes simultaneous cleaning with development can be suitably used. In the case of an electrophotographic apparatus having no cleaning means, reversal development is preferable, and a configuration in which the developer and the photoconductor are in contact is preferable.

The developing method using the developing device 18 includes:
For example, a contact two-component developing method, a contact one-component method and the like are mentioned as suitable developing methods. This is because, when the developer and the transfer residual toner are in contact with each other on the photoreceptor, a rubbing force is applied to the electrostatic force, and there is a tendency that the transfer residual toner can be effectively collected by the developing device. Regarding the bias applied to the development, the DC component is represented by a black portion (image exposed portion).
And the potential of the white background portion.

The toner image is transferred to the transfer unit 1 by the photoreceptor 12.
It is transported to the position of No. 4. Then, the transfer unit 14 transfers the toner image onto the transfer material supplied with the timing adjusted by the registration roller 4 so that the toner image contacts the transfer material. As the transfer unit 14, a known unit such as a corona, a roller, or a belt is used. The transfer material after the transfer is introduced into a fixing device 19 having a heating roller and a pressure roller, and the toner image on the transfer material is fixed on the transfer material by the fixing device 19. As the fixing unit 19, a known unit such as a heating and pressing roller is used.

After the transfer step, the toner remaining after transfer remains on the photosensitive member 12. The transfer residual toner may be removed from the photoreceptor 12 by providing a separate cleaning means or the like. However, the electrophotographic apparatus of the present invention uses a magnetic brush charger to transfer the toner remaining on the photoreceptor surface after the transfer step. It is possible to reduce the size of the apparatus and prevent the generation of waste toner by holding toner in the magnetic brush and moving the toner onto the photoreceptor from the magnetic brush during non-image formation, collecting and reusing the toner in the developing device. Is preferred. When the transfer residual toner is conveyed from the magnetic brush charger that has collected the photoreceptor surface to the developing part using the surface of the photoreceptor, and collected and reused by the developing device, it can be realized without changing the charging bias. In addition, when a transfer paper jam occurs, or when images having a high image ratio are continuously taken, it is possible that an excessive amount of toner is mixed into the magnetic brush charger.

In this case, it is preferable to change the voltage (charging bias) applied to the magnetic brush charging member to move the toner onto the photosensitive member from the magnetic brush during non-image formation. Examples of the photoreceptor at the time of non-image formation include the surface of the photoreceptor where no electrostatic latent image is formed between processes, such as during pre-rotation, post-rotation, and between transfer papers. The charging bias that causes the toner to easily come out of the magnetic brush, that is, the voltage applied to move the toner from the magnetic brush onto the photoreceptor, includes an AC component having a small peak-to-peak voltage or a DC component, or a peak-to-peak voltage. And an AC component whose AC effective value is lowered by changing the waveform without changing the waveform.

The toner used in the electrophotographic apparatus of the present invention may be a one-component developer or a two-component developer containing a toner and a carrier. Although it can be used, there is a preferable mode in terms of transfer efficiency due to toner scattering. That is, if the amount of the transfer residual toner that enters the magnetic brush is small, the absolute amount of the toner involved in the scattering is small, so that the combination effect with the electrophotographic apparatus of the present invention is large.

The toner is a toner produced by a polymerization method and preferably has a spherical shape. The polymerization method is a preferable method for producing a toner having a uniform shape and particle diameter, and a substantially spherical toner is obtained.
As such a polymerization method, an emulsion polymerization method, a suspension polymerization method and the like can be exemplified as suitable polymerization methods.

The toner used in the present invention has a toner shape factor SF-1 of 100 to 140 and SF-2 of 100 to 140.
It is preferably 120. A toner having a shape factor in the above range tends to show good transferability. If the shape factor of the toner is out of the above range, an increase in transfer residual toner, abrasion of the photoconductor, and the like are likely to occur.

Here, SF-1 and SF-2, which are the shape factors of the toner specified in the present invention, will be described. The toner shape factors SF-1 and SF-2 are measured and defined as follows. The shape factor of the toner is, for example, using a FE-SEM (S-800) manufactured by Hitachi, Ltd., randomly sample 100 toner images of 2 μm or more that are enlarged 1000 times, and the image information is transmitted via an interface. For example, an image analyzer manufactured by Nicole (Luzex II)
It is introduced into I), measured and analyzed, and the values obtained from the following equations are defined as shape factors SF-1 and SF-2.

[0102]

(Equation 1)

(Equation 2)

Here, MXLNG represents the absolute maximum length of the particle, PERIME represents the peripheral length of the particle, and AREA represents the projection surface of the particle. SF-1 indicates the degree of roundness of the particle, and S
F-2 indicates the unevenness of the particles.

An external additive or the like may be added to the toner used in the present invention for the purpose of improving the fluidity of the toner. Examples of such external additives include inorganic fine powders such as titanium oxide and silica. It is preferable that the surface of the inorganic fine powder or the above-mentioned carrier is subjected to a hydrophobic treatment. For this hydrophobizing treatment, a silicone resin or the above-described coupling agent can be used.

The average particle size of the toner used in the present invention is as follows:
Coulter Multisizer Type II or Type II E (manufactured by Coulter Corporation), and ISOTON R-II (1%
NaCl aqueous solution, manufactured by Coulter Scientific Japan Co., Ltd.) according to the following method.

The measuring method is as follows.
0.1 to 5 m of a surfactant as a dispersant in 150 mL
L and about 2 to 20 mg of the powder sample to be measured. The electrolytic solution in which the sample is suspended is approximately 1 to
After the dispersion treatment for 3 minutes, the measurement apparatus was used to prepare a 2.00 μm aperture using a 100 μm aperture.
The volume distribution and the number distribution are calculated by measuring the volume and the number of m or more toners.

Then, the average particle size of the toner is determined by using the weight-based weight average particle size (D4) obtained from the desired volume distribution (the median value of each channel is a representative value for each channel). 2.00 to 2.52 μm as a channel
Less than 2.52 to 3.17 μm; 3.17 to 4.0
Less than 0 μm; 4.00 to less than 5.04 μm;
7.35 μm or less; 6.35 to less than 8.00 μm;
00 to less than 10.08 μm; 10.08 to 12.70 μm
m; 12.70 to less than 16.00 μm; 16.00
20.20 to less than 25.40 μm; 25.40 to less than 32.00 μm; 32.00 to 4
13 channels of less than 0.30 μm are used.

[0108]

The present invention will be described below with reference to examples.
This does not limit the present invention. First, the configuration, material, manufacturing method, and the like of a member used in the present invention will be described.

<Production Example 1 of Magnetic Particles for Charging> Fe ₂ O ₃ 52
Mol%, CuO 26 mol%, ZnO 22 mol% Mixture 1
After adding 0.05 parts by mass of phosphorus to 00 parts by mass, pulverizing and mixing with a ball mill, and adding a dispersant, a binder and water to form a slurry, and then performing a granulation operation with a spray drier. After classification as appropriate, baking was performed at 1200 ° C. Classify the obtained ferrite after pulverization,
A copper-zinc ferrite having an average particle size of 28 μm and a volume resistance of 5 × 10 ⁷ Ωcm was obtained.

<Production Example 2 of Magnetic Particles for Charging> 100 parts by mass of the copper-zinc ferrite particles obtained in Production Example 1 of magnetic particles for charging, 0.01 parts by mass of a silane coupling agent and dodecyltrimethoxysilane as a coupling agent. And a solution dissolved in 20 parts by mass of methyl ethyl ketone was kept at 70 ° C. while stirring, and after the solvent was evaporated, the obtained magnetic powder was cured in an oven kept at 200 ° C. for 60 minutes, and charged. Magnetic particles for members were obtained. Average particle size is 3
0 μm, and the volume resistance was 4.1 × 10 ⁷ Ωcm.

<Production Example 3 of Charging Magnetic Particles> 100 parts by mass of the copper-zinc ferrite particles obtained in Production Example 1 of charging magnetic particles, a silane coupling agent as a coupling agent, and 0.07 parts by mass of dodecyltrimethoxysilane And a solution dissolved in 20 parts by mass of methyl ethyl ketone was kept at 70 ° C. while stirring, and after the solvent was evaporated, the obtained magnetic powder was cured in an oven kept at 200 ° C. for 60 minutes, and charged. Magnetic particles for members were obtained. Average particle size is 2
9 μm, and the volume resistance was 4.2 × 10 ⁷ Ωcm.

<Production Example 4 of Magnetic Particles for Charging> 100 parts by mass of the copper-zinc ferrite particles obtained in Production Example 1 of magnetic particles for charging, a silane coupling agent as a coupling agent, and 0.1 part by mass of dodecyltrimethoxysilane. And a solution dissolved in 20 parts by mass of methyl ethyl ketone was stirred while stirring.
After maintaining the temperature at 0 ° C. and evaporating the solvent, the obtained magnetic powder was cured in an oven maintained at 200 ° C. for 60 minutes to obtain magnetic particles for a charging member. Average particle size is 31
μm, and the volume resistance was 4.2 × 10 ⁷ Ωcm.

<Production Example 5 of Magnetic Particles for Charging> 100 parts by mass of the copper-zinc ferrite particles obtained in Production Example 1 of magnetic particles for charging, a titanium coupling agent as a coupling agent, and isopropoxytriisostearoyl titanate 0.06.
The solution dissolved in parts by mass and 20 parts by mass of methyl ethyl ketone was kept at 70 ° C. while stirring, and after the solvent was evaporated, the obtained magnetic powder was cured in an oven kept at 200 ° C. for 60 minutes. Thus, magnetic particles for a charging member were obtained. The average particle size is 30 μm, and the volume resistance is 3.9 × 10 ⁷
Ωcm.

<Production Example 6 of Magnetic Particles for Charging> Fe ₂ O ₃ 53
After adding 0.05 parts by mass of phosphorus to 100 parts by mass of a mixture of mol%, 32 mol% of MnO and 10 mol% of MgO, pulverizing and mixing with a ball mill, and adding a dispersant, a binder and water to form a slurry. The granulation operation was performed using a spray dryer. After classification as appropriate, baking was performed at 1200 ° C. while adjusting the oxygen concentration. The obtained ferrite was classified after pulverization to obtain a manganese ferrite having an average particle diameter of 27 μm and a volume resistance of 6.2 × 10 ⁷ Ωcm. Next, 100 parts by mass of the manganese ferrite particles, a silane coupling agent as a coupling agent, a solution dissolved in 0.06 parts by mass of isopropoxyisostearoyl titanate and 20 parts by mass of methyl ethyl ketone,
After the solvent was evaporated at 70 ° C. while stirring, the obtained magnetic powder was placed in an oven maintained at 200 ° C. for 6 hours.
Curing was performed for 0 minutes to obtain magnetic particles for a charging member.
The average particle size is 28 μm and the volume resistance is 4.8 × 10 ⁷ Ωcm
Met.

<Example 7 of Production of Magnetic Particles for Charging> The pulverizing and classifying steps of Production Example 1 of magnetic particles for charging were operated to obtain an average particle size of 4.
Charging magnetic particles having a thickness of 2 μm and a volume resistance of 5.3 × 10 ⁷ Ωcm were obtained. As described above, charging magnetic particles were produced. Table 1 shows the characteristics and the like of each magnetic particle for charging.

[0116]

[Table 1]

<Photoconductor Production Example 1> Four functional layers are provided on an aluminum cylinder having a diameter of 30 mm. The first layer is an undercoat layer, and is a conductive layer having a thickness of about 20 μm provided to smooth defects of the aluminum drum and to prevent the occurrence of moire due to reflection of laser exposure. The second layer is a positive charge injection preventing layer, serves to prevent canceling the negative charge positive charge injected from the aluminum substrate is charged to the photosensitive member surface, 10 by Amilan resin and methoxymethylated nylon ⁶ This is a medium resistance layer having a thickness of about 1 μm and a resistance adjusted to about Ωcm. The third layer is a charge generation layer, and is a layer having a thickness of about 0.3 μm in which a titanyl phthalocyanine pigment is dispersed in a resin, and generates a positive / negative charge pair by receiving laser exposure. The fourth layer is a charge transport layer, in which hydrazone is dispersed in a polycarbonate resin, and is a P-type semiconductor. Therefore,
Negative charges charged on the photoreceptor surface cannot move through this layer, and only positive charges generated in the charge generation layer can be transported to the photoreceptor surface. The thickness was 22 μm. The surface resistance of the photoreceptor is 2 × 10 ¹⁵ Ωc for the charge transport layer alone.
m.

<Photoconductor Production Example 2> Five functional layers are provided on an aluminum cylinder having a diameter of 30 mm. 1st layer, 2nd layer
The layer and the third layer were formed in the same manner as in Photoreceptor Production Example 1, and the fourth layer was formed in the same manner as in Photoreceptor Production Example 1, except that the thickness was changed to 17 μm, and the charge injection layer was formed in the fifth layer. . The charge injection layer is obtained by dispersing SnO ₂ ultrafine particles in a photocurable acrylic resin. Specifically, antimony-doped SnO ₂ particles having a particle size of about 0.03 μm and having a reduced resistance are dispersed in an amount of 170 mass% with respect to 100 mass% of the resin, and 20 mass% of tetrafluoroethylene resin particles. The composition was obtained by dispersing 1.2% by mass of the agent. The thickness was 3 μm. The photoconductor surface resistance was 4 × 10 ¹² Ωcm for the charge injection layer alone.

<Toner Production Example 1> Polyester resin 10
After dry-mixing 0% by mass, 2% by mass of a metal-containing azo dye, 3% by mass of low-molecular-weight polypropylene, and 6% by mass of carbon black, the mixture was kneaded by a twin-screw extruder set at 140 ° C. The obtained kneaded material was cooled, finely pulverized by an air-flow type pulverizer, and then subjected to air classification to obtain a toner composition having an adjusted particle size distribution. 1.6 wt% of hydrophobically treated titanium oxide was externally added to this toner composition to prepare a toner having a weight average particle diameter of 7.2 μm.

<Toner Production Example 2> 88% by mass of styrene,
12% by mass of n-butyl acrylate, 3% by mass of low-molecular-weight polypropylene, 8% by mass of carbon black, 1% by mass of a metal-containing azo dye, and 3% by mass of an azo initiator are dispersed and mixed.
The above solution is mixed with 50% pure water in which 4% by weight of calcium phosphate is dispersed.
0% by mass and dispersed by a homomixer.
The polymer obtained by polymerizing for 8 hours was filtered, washed, dried and classified to obtain a toner composition. 1.6 wt% of hydrophobically treated titanium oxide was externally added to the toner composition to prepare a toner having a weight average diameter of 7.4 μm. The obtained toner is formed by a polymerization method, and shows a spherical shape when observed with an electron microscope. The shape factor is
SF-1 was 115 and SF-110.

<Developer Production Example 1> Nickel zinc ferrite having an average diameter of 55 μm coated with a silicone resin was used.
% By mass to form a developer.

<Developer Production Example 2> Toner production example 2 in which nickel-zinc ferrite having an average diameter of 55 μm coated with an acrylic-modified silicone resin was used in an amount of 100% by mass.
The toner was mixed with 6% by mass to prepare a developer.

Next, the present invention will be described using evaluation machines and methods used in the examples and comparative examples of the present invention, and the examples and comparative examples.

<Digital Copier 1> A digital copier using a laser beam as an electrophotographic apparatus (manufactured by Canon:
GP55) was prepared. The outline of the device includes a corona charger as a charging unit for the photoconductor, and a one-component developing device employing a one-component jumping developing method as a developing unit.
A transfer unit includes a corona charger, a blade cleaning unit, and a pre-charging exposure unit. The photosensitive member charger, cleaning means, and photosensitive member are an integrated unit. The process speed is 150 mm / s. The digital copier was modified as follows.

The development part is changed from one-component jumping development to
The two-component developer was modified so that it could be used. Further, a 16 Φ (mm) conductive non-magnetic sleeve containing a magnet roller is disposed on the charged portion to form a magnetic brush charger. Further, the transfer means using a corona charger was changed to a roller transfer method, and the pre-charge exposure means was removed. The gap between the conductive sleeve of the charged part and the photoconductor is 0.5 mm
Was set. As for the developing bias, a rectangular wave of 1000 Vpp / 3 KHz is superimposed on a DC component of -500 V.
Further, the cleaning blade was removed to obtain a cleanerless copying machine. FIG. 5 is a schematic diagram.

<Digital Copier 2> In the digital copier 1, a metallic brush material, which is a feature of the present invention, was processed into a roller shape in a magnetic brush charger, and was placed in contact with the charging device by a pressure spring. The metal soap member is made of calcium stearate. FIG. 1 shows a schematic diagram.

<Digital Copier 3> The digital copier 2 has the same configuration as that of the digital copier 2 except that the material of the metal soap provided in contact with the magnetic brush charger is changed to zinc stearate.

<Evaluation Method> For actual durability evaluation, a digital copying machine 1 is used, a magnetic brush is formed so that the coating density of the magnetic particles is 180 mg / cm ^2, and a photoreceptor is mounted. In order to form a magnetic brush so as to be 180 mg / cm ² , a minimum of about 30 g of magnetic particles is required.

The evaluation mode is as follows.
Four thousand sheets are continuously fed with four horizontal feeds. At this time, as a bias applied to the charging member, a DC voltage of -700 V and a rectangular wave AC component of 1 KHz and 600 Vpp are applied, and a durability test is performed under the conditions of 25 ° C./65% relative humidity.

Further, in the non-image forming section, that is, during continuous paper feeding, during charging (pre-rotation), during image formation (between sheets), and during the 500th image before the first image can be formed. At the time of charging the photoconductor after the formation is completed (post-rotation), a DC voltage of -700 V or a DC voltage of -700 V and a rectangular wave AC component of 1 KHz and 300 Vpp are applied to charge the photoconductor while charging the photoconductor. The toner mixed in the brush is moved onto the photoreceptor, and is collected at the developing portion.

In the present embodiment, the timing for applying a charging bias different from that for charging the photoreceptor is selected between pre-rotation, post-rotation, and sheet spacing. However, the present invention is not limited to this, and it is not limited to this. Instead, the timing at which the photoconductor moves may be ascertained. The toner remaining after transfer is collected by a magnetic brush charger, and its frictional charging polarity is made the same as the charging polarity of the photoreceptor.

During the pre-rotation, the paper interval, and the post-rotation, a DC component of -700 V is applied, and the toner staying from the magnetic brush is swept out onto the photoreceptor to be collected by the developing device via the photoreceptor.

A DC voltage of -700 V and a rectangular wave AC component of 1 KHz and 300 Vpp are applied between the papers in the non-image forming portion to charge the photosensitive member and transfer toner mixed in the charged magnetic brush onto the photosensitive member. And collected by a developing device.

The applied voltage is -7 for every 20,000 endurable sheets.
A DC voltage of 00 V and a rectangular wave AC component of 1 KHz and 600 Vpp were applied, and the potential convergence rate was measured to determine what percentage of the DC component -700 V of the charging potential of the photoconductor surface from 0 V reached. Convergence rate is good if 90% or more, 9
If it is 5% or more, excellent chargeability is obtained.

Hereinafter, the present invention will be further described with reference to examples.

<Example 1> As magnetic particles for charging a magnetic brush, 0.5% by mass of calcium stearate (fine powder in Table 2) having an average particle size of 2 μm was used in Preparation Example 6 for charging magnetic particles.
80 g of the added mixed particles were loaded, and a durability test by continuous paper passing was performed using Digital Copier 2 using Photoconductor Production Example 2 as the photoconductor and Developer Production Example 2 as the developer. Initial, 30,000, 50,000, 10,000
The potential convergence rate was measured for 0 and 150,000 sheets. The photoreceptor used in this durability test did not cause fogging or fusion due to the photoreceptor scraping.

As a result, the potential convergence rate was maintained at 90% or more even at 150,000 sheets, and a good image was obtained without occurrence of uneven charging. Table 2 shows the details of the results.

<Example 2> A test similar to that of Example 1 was performed, except that the magnetic particles used in Preparation Example 3 were used as magnetic particles, and no fine powder was added. Table 2 shows the results
Shown in Although the chargeability is slightly deteriorated at 150,000 sheets, it is at a level without any problem.

<Example 3> The same test as in Example 1 was conducted except that the magnetic particle for charging was prepared in Production Example 1 and no fine powder was added. Table 2 shows the results
Shown in Although the chargeability is slightly deteriorated at 150,000 sheets, it is at a level without any problem. However, fogging due to photoreceptor scraping occurred on the 110,000th sheet. This is because the surface treatment of the magnetic particles is not performed.

Example 4 A test similar to that of Example 1 was performed, except that the magnetic particles used in Production Example 2 for magnetic particles for charging were not used, and no fine powder was added. Table 2 shows the results
Shown in Although the chargeability is slightly deteriorated at 150,000 sheets, it is at a level without any problem. However, fog due to scraping of the photosensitive member occurred on the 140,000th sheet. This is because although the surface treatment of the magnetic particles is performed, the treatment amount is as small as 0.01 part by mass with respect to 100 parts by mass of the magnetic particles.

<Example 5> The same test as in Example 1 was performed, except that the magnetic particle used was Production Example 3 of the magnetic particles for charging, the developer was Production Example 1 and no fine powder was added. Was. Table 2 shows the results. Although the chargeability is slightly deteriorated after 150,000 sheets, it is at a level without any problem.
This is due to the low sphericity of the toner of Developer Production Example 1.

<Example 6> Using the digital copying machine 3, the same test as in Example 2 was performed except that the material of the metal soap was zinc stearate. Table 2 shows the results. Although the chargeability is slightly deteriorated after 150,000 sheets, it is at a level without any problem.

<Example 7> The same test as in Example 1 was performed except that the magnetic particle for charging was prepared in Production Example 4 and fine powder was not added. Table 2 shows the results
Shown in Although the chargeability is slightly deteriorated at 150,000 sheets, it is at a level without any problem.

<Example 8> The same test as in Example 1 was conducted, except that the magnetic particle for charging was prepared in Preparation Example 5 and fine powder was not added. Table 2 shows the results
Shown in

<Example 9> The same test as in Example 1 was performed, except that the magnetic particle used in Preparation Example 6 was used as the magnetic particles and no fine powder was added. Table 2 shows the results
Shown in The reason why the durability of the charging property is better than that in Example 8 is considered to be due to the composition of the magnetic particles, and the potential convergence rate at 30,000 sheets is considered to be the effect of the addition of the fine powder.

<Comparative Example 1> The configuration was the same as that of Example 1 except that the digital copying machine 1 was used as the evaluator and the magnetic particle production example 1 was used as the magnetic particles. As a result, the deterioration of the charging member was somewhat severe, and fogging caused by scraping of the photoreceptor occurred at 90,000 sheets. Thereafter, the photoconductor was replaced and the test was continued. Table 2 shows the results.

<Comparative Example 2> The same test as in Comparative Example 1 was performed except that no fine powder was added. Fogging caused by scraping of the photoreceptor occurred at 80,000 sheets. Thereafter, the photoconductor was replaced and the test was continued. Table 2 shows the results.

<Comparative Example 3> The charging method is changed to a discharging method. Comparative Example 1 was performed except that the AC component applied to the charging member was a rectangular wave of 1300 Vpp, the magnetic particles were magnetic particle production example 7, and the photoconductor was photoconductor production example 1. As a result, the life of the photoconductor reached 40,000 sheets, and the evaluation was stopped. Table 2 shows the results.

[0149]

[Table 2]

[0150]

According to the present invention, a photoreceptor, a charging device that contacts the photoreceptor to charge the photoreceptor, and an exposure unit that forms an electrostatic latent image on the charged photoreceptor by image exposure. A developing device for visualizing the electrostatic latent image with toner,
What is claimed is: 1. A charging device for use in an electrophotographic apparatus having a transfer unit for transferring an obtained toner image onto a transfer material, comprising: a conductive sleeve having a magnet body and rotatably provided; and a surface of the conductive sleeve. A magnetic brush charging member having magnetic particles that form a magnetic brush supported by a magnetic brush, and a metal brush member including metal soap and provided at a position where the metal soap is in contact with the magnetic brush. By configuring the characteristic charging device, it is possible to provide a charging device capable of obtaining a stable image over a long period of time in an electrophotographic device equipped with a magnetic brush charger.

Further, according to the present invention, a photoreceptor, a charging device that contacts the photoreceptor to charge the photoreceptor, and an exposure unit that forms an electrostatic latent image on the charged photoreceptor by image exposure. In an electrophotographic apparatus having a developing device for visualizing an electrostatic latent image with toner and a transfer unit for transferring the obtained toner image to a transfer material, the charging device has a magnet and is rotatably provided. A conductive sleeve, a magnetic brush charging member having magnetic particles carried on the surface of the conductive sleeve to form a magnetic brush, and a metal soap member including a metal soap and provided at a position where the metal soap contacts the magnetic brush By configuring an electrophotographic apparatus characterized by being a magnetic brush charger having the following, an electrophotographic apparatus equipped with a magnetic brush charger can provide a stable image for a long time. It is possible to provide an electrophotographic apparatus which is.

In the present invention, the surface of the magnetic particles is treated with a coupling agent whose central element having an alkyl chain having 6 or more carbon atoms is titanium, silicon, aluminum or zirconium. The total amount of the agent is 0.0001 with respect to the magnetic particles.
By setting the amount to not less than 0.5% by mass and not more than 0.5% by mass, it is possible to provide a charging device and an electrophotographic device capable of obtaining a more stable image for a long time in an electrophotographic device equipped with a magnetic brush charger.

Further, according to the present invention, by setting the volume resistance of the magnetic particles to 1 × 10 ⁴ Ωcm or more and 1 × 10 ⁹ Ωcm or less, an electrophotographic apparatus equipped with a magnetic brush charger can provide a stable image for a long time. It is more effective in providing a charging device and an electrophotographic device that can obtain the above.

Further, according to the present invention, by setting the average particle diameter of the magnetic particles to 5 μm or more and 100 μm or less, in an electrophotographic apparatus equipped with a magnetic brush charger, a charging device and an electronic apparatus capable of obtaining a stable image for a long period of time. It is more effective in providing a photographic device.

Further, in the present invention, the photosensitive member includes a conductive support, and a photosensitive layer formed on the conductive support.
A charge injection layer formed farthest away from the conductive support, wherein the charge injection layer has a volume resistivity of at least 10 ⁸ Ωcm;
By setting the resistance to 0 ¹⁵ Ωcm or less, it is possible to provide a charging device and an electrophotographic device capable of obtaining a more stable image over a longer period of time in an electrophotographic device equipped with a magnetic brush charger.

In the present invention, the charge injection layer contains conductive fine particles and a binder resin, so that an electrophotographic apparatus equipped with a magnetic brush charger can provide a stable image for a long period of time. It is more effective in providing an apparatus and an electrophotographic apparatus.

Further, according to the present invention, in the electrophotographic apparatus equipped with a magnetic brush charger, a charge device and an electrophotographic apparatus capable of obtaining a stable image for a long period of time by providing the charge injection layer containing a lubricant powder. It is more effective in providing the device.

In the present invention, a stable image can be obtained for a long time in an electrophotographic apparatus equipped with a magnetic brush charger by using the lubricant powder as a fluororesin, a silicone resin or a polyolefin resin. It is more effective in providing a charging device and an electrophotographic device that can be used.

In the present invention, the toner remaining on the surface of the photoreceptor after the transfer step is held in the magnetic brush,
By moving the toner onto the photoreceptor from the magnetic brush during non-image formation and collecting and reusing the toner in the developing device, an electrophotographic apparatus equipped with a magnetic brush charger and a cleanerless system can be used for a long time. It is possible to provide a charging device and an electrophotographic device that can obtain a stable image and are effective from the viewpoint of ecology.

Further, according to the present invention, a power supply for applying a voltage to the magnetic brush charging member is provided, and the voltage applied to the magnetic brush charging member is changed so that the magnetic brush is placed on the photosensitive member from the magnetic brush during non-image formation. By adopting a configuration in which the toner is moved, in an electrophotographic apparatus equipped with a magnetic brush charger and a cleaner-less system, a stable image can be obtained for a long period of time, and an effective charging apparatus and an electrophotographic apparatus from the viewpoint of ecology are provided. It is even more effective in providing.

Further, in the present invention, the toner is a toner produced by a polymerization method, and by using a spherical toner, the transfer efficiency of the toner is improved. In the device, a charging device and an electrophotographic device capable of obtaining a more stable image for a long time can be provided.

In the present invention, the shape factor SF-1 of the toner is 100 to 140, and SF-2 is 100 to 120.
As a result, the transfer efficiency of toner is improved, and in an electrophotographic apparatus equipped with a magnetic brush charger, it is more effective in providing a charging apparatus and an electrophotographic apparatus capable of obtaining a more stable image over a long period of time. is there.

Further, in the present invention, the magnetic particles are preliminarily mixed with a metal soap powder having a mixing amount of 0.005% by mass or more and 10% by mass or less with respect to the magnetic particles. In an electrophotographic apparatus equipped with a magnetic brush charger, the present invention is more effective in providing a charging apparatus and an electrophotographic apparatus capable of obtaining a stable image for a long time.

Further, in the present invention, by setting the average particle size of the metal soap powder to be in the range of 0.1 μm to 20 μm, a stable image can be obtained for a long time in an electrophotographic apparatus equipped with a magnetic brush charger. It is even more effective in providing a charging device and an electrophotographic device that can be used.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an embodiment of an electrophotographic apparatus according to the present invention.

FIG. 2 is a schematic view showing one embodiment of the charging device of the present invention.

FIG. 3 is a schematic view showing another embodiment of the charging device of the present invention.

FIG. 4 is a schematic diagram showing an apparatus for measuring the volume resistance of magnetic particles used in the charging device of the present invention.

FIG. 5 is a schematic view showing an example of a conventional magnetic brush charger and an electrophotographic apparatus.

[Explanation of symbols]

 Reference Signs List 4 registration roller 10 developer (toner) 11, 21 magnetic brush charger 12 photoreceptor 13 exposure means 14 transfer means 15, 31, 41 magnetic particles 16, 32, 42 conductive sleeve 17 developing sleeve 18 developing device 19 fixing device 20 , 34, 44 Metal soap member 33, 43 Magnet roller (magnet) 51, 52 Electrode 53 Guide ring 54 Ammeter 55 Voltmeter 56 Constant voltage device 57 Measurement sample 58 Insulator A Measurement cell

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G03G 15/08 507 G03G 15/08 507B (72) Inventor Shuichi Aida 3-30-2 Shimomaruko, Ota-ku, Tokyo (72) Inventor Fumihiro Arahira 3-30-2 Shimomaruko, Ota-ku, Tokyo F-term (reference) 2H003 AA12 BB00 BB11 CC04 DD11 2H005 AA15 AB06 DA07 2H068 AA05 AA06 AA08 BB04 BB31 BB33 CA37 FC01 2H077 AA37 AC16 AD06 AD31 EA03 GA03

Claims (30)

[Claims] A photoconductor, a charging device that contacts the photoconductor and charges the photoconductor, an exposure unit that forms an electrostatic latent image on the charged photoconductor by image exposure, and the electrostatic latent image. A charging device used in an electrophotographic apparatus having a developing device for visualizing the toner image with toner and a transfer means for transferring the obtained toner image to a transfer material, wherein the charging device has a magnet body and is rotatably provided. A sleeve, a magnetic brush charging member having magnetic particles carried on the surface of the conductive sleeve to form a magnetic brush, and a metal soap member including metal soap and provided at a position where the metal soap contacts the magnetic brush. A magnetic brush charger having: 2. The surface of the magnetic particles is treated with a coupling agent whose central element having an alkyl chain having 6 or more carbon atoms is titanium, silicon, aluminum or zirconium, and the amount of the coupling agent present 2. The charging device according to claim 1, wherein the total amount is 0.0001% by mass or more and 0.5% by mass or less with respect to the magnetic particles. 3. The magnetic particles have a volume resistance of 1 × 10 ^4.
The charging device according to claim 1, wherein the charging device has a resistance of not less than Ωcm and not more than 1 × 10 ⁹ Ωcm. 4. The magnetic particles having an average particle size of 5 μm or more and 1
The charging device according to claim 1, wherein the charging device has a thickness of not more than 00 μm. 5. The method according to claim 1, wherein the photosensitive member has a conductive support, a photosensitive layer formed on the conductive support, and a charge injection layer formed farthest from the conductive support. The charging device according to claim 1, wherein: 6. The charge injection layer has a volume resistance of 10 ⁸ Ω.
The charging device according to claim 5, wherein the thickness is not less than 10 cm and not more than 10 ¹⁵ Ωcm. 7. The charging device according to claim 5, wherein the charge injection layer contains conductive fine particles and a binder resin. 8. The charging device according to claim 5, wherein the charge injection layer contains a lubricant powder. 9. The charging device according to claim 8, wherein the lubricant powder is a fluororesin, a silicone resin, or a polyolefin resin. 10. The toner remaining on the surface of the photoreceptor after the transfer step is retained in the magnetic brush, and the toner is moved from the magnetic brush onto the photoreceptor during non-image formation, collected by the developing device, and re-used. The charging device according to claim 1, wherein the charging device is used. 11. A power supply for applying a voltage to the magnetic brush charging member, and by changing a voltage applied to the magnetic brush charging member, toner is moved from the magnetic brush onto a photosensitive member during non-image formation by changing a voltage applied to the magnetic brush charging member. The charging device according to claim 10, wherein: 12. The charging device according to claim 1, wherein the toner is a toner generated by using a polymerization method. 13. The toner according to claim 13, wherein the shape factor SF-1 is 10
The charging device according to claim 12, wherein 0 to 140 and SF-2 are 100 to 120. 14. The magnetic particles according to claim 1, wherein a metal soap powder having a mixing amount of 0.005% by mass or more and 10% by mass or less with respect to the magnetic particles is mixed in advance. 5. The charging device according to claim 4. 15. The metal soap powder has an average particle size of 0.1.
The charging device according to claim 14, wherein the charging device is in a range of not less than μm and not more than 20 μm. 16. A photoconductor, a charging device that contacts the photoconductor and charges the photoconductor, an exposure unit that forms an electrostatic latent image on the charged photoconductor by image exposure, and the electrostatic latent image An electrophotographic apparatus having a developing device that visualizes the toner image with a toner and a transfer unit that transfers the obtained toner image to a transfer material, wherein the charging device has a magnet body and is rotatably provided with a conductive sleeve; A magnetic brush charging member having magnetic particles carried on the surface of the conductive sleeve to form a magnetic brush; and a metal soap member including metal soap and provided at a position where the metal soap contacts the magnetic brush. An electrophotographic apparatus, which is a magnetic brush charger. 17. The surface of the magnetic particles is treated with a coupling agent whose central element having an alkyl chain having 6 or more carbon atoms is titanium, silicon, aluminum, or zirconium, and the abundance of the coupling agent Is from 0.0001% by mass to 0.5% by mass based on the magnetic particles.
The electrophotographic apparatus according to claim 16, wherein the content is not more than mass%. 18. The magnetic particles having a volume resistance of 1 × 10 ^4.
18. The electrophotographic apparatus according to claim 16, wherein the resistivity is Ωcm or more and 1 × 10 ⁹ Ωcm or less. 19. The electrophotographic apparatus according to claim 16, wherein the average particle size of the magnetic particles is 5 μm or more and 100 μm or less. 20. The photoconductor has a conductive support, a photosensitive layer formed on the conductive support, and a charge injection layer formed farthest from the conductive support. The electrophotographic apparatus according to claim 16, wherein: 21. A volume resistivity value of the charge injection layer is 10 ^8.
17. The electrophotographic apparatus according to claim 16, wherein the resistance is not less than Ωcm and not more than 10 ¹⁵ Ωcm. 22. The electrophotographic apparatus according to claim 20, wherein the charge injection layer contains conductive fine particles and a binder resin. 23. The electrophotographic apparatus according to claim 20, wherein the charge injection layer contains a lubricant powder. 24. The electrophotographic apparatus according to claim 23, wherein said lubricant powder is a fluororesin, a silicone resin, or a polyolefin resin. 25. A toner remaining on the surface of the photoreceptor after the transfer step is retained in the magnetic brush, the toner is moved from the magnetic brush onto the photoreceptor during non-image formation, and is collected by the developing device and re-used. 17. The method according to claim 16, wherein:
An electrophotographic apparatus according to the above. 26. A power supply for applying a voltage to the magnetic brush charging member, and by changing a voltage applied to the magnetic brush charging member, toner is moved from the magnetic brush onto the photosensitive member during non-image formation by changing a voltage applied to the magnetic brush charging member. The electrophotographic apparatus according to claim 25, wherein: 27. The electrophotographic apparatus according to claim 15, wherein the toner is a toner generated by using a polymerization method. 28. The shape factor SF-1 of the toner is 10
The electrophotographic apparatus according to claim 27, wherein 0 to 140 and SF-2 are 100 to 120. 29. The magnetic particles, wherein a metal soap powder having a mixing amount of 0.005% by mass or more and 10% by mass or less with respect to the magnetic particles is mixed in advance. 20. The electrophotographic apparatus according to any one of the items 19 to 19. 30. The metal soap powder having an average particle size of 0.1
30. The electrophotographic apparatus according to claim 29, wherein the distance is in a range of not less than μm and not more than 20 μm.