JP2000352855A - Magnetic particle dispersed composite particles for electrification, electrifying member using the same, electrifying device, electrophotographic device and process cartridge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide magnetic particle dispersed composite particles having stable electrostatic property in continuous use and durable for long-term use. SOLUTION: The magnetic particle dispersed composite particles have a bonding resin and magnetic particles dispersed in the bonding resin. The amount of the magnetic particles is 81-98 wt.% of the amount of the composite particles, the standard deviation of the minor axis size to major axis size ratio of the composite particles having >=5 μm particle diameter is >=0.08 and the volume resistivity of the composite particles is 104-109 Ωcm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to particles used for a member for charging an object, and also relates to a charging device, an image forming apparatus and a process cartridge using the charging member, and is applied to a copying machine, a printer, a facsimile and the like. Is done.

[0002]

2. Description of the Related Art Conventionally, many methods are 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.

[0003] As a photosensitive member charging means in such an electrophotographic method, there is a charging method using so-called corotron or scorotron using corona discharge. Furthermore, a charging method such as a roller, a fur brush or a blade was brought into contact with the surface of the photoreceptor, and a discharge was formed in a narrow space near the contact portion, thereby minimizing the generation of ozone. I have.

However, in the charging method using corona discharge, a large amount of ozone is generated when corona discharge, particularly negative or positive corona, is generated. Therefore, it is necessary to provide an electrophotographic apparatus with a filter for capturing ozone. There is
There have been problems such as an increase in the size of the device or an increase in running costs.

Further, among charging methods in which ozone generation is suppressed as much as possible by forming a discharge in a narrow space, a method of charging by contacting with a photoreceptor such as a blade or roller charging method is used. Tend to cause problems such as toner fusion.

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 above-mentioned roller or blade, a brush, a member obtained by applying a resistive layer to a long and thin conductive plate, and the like, there is a problem that it is difficult to control the proximity distance. There was a problem in practical use.

For this reason, a technique of using a so-called magnetic brush, which has a relatively small contact load to the photoreceptor and has magnetic particles held by a magnet, as a charging member has been studied.

[0008] As a charging method using magnetic particles, two methods have been proposed in combination with a photoreceptor.

One is a method in which a charge injection layer is provided on a surface layer of a photoreceptor, and charges are directly injected through the contact with the charge injection layer to charge the photoreceptor. The other is a method using a normal photoreceptor and utilizing the discharge of magnetic particles and minute voids on the surface of the photoreceptor.

As a disclosure of magnetic particles used as a charging member, JP-A-59-133569 discloses a method in which particles coated with iron powder are held on a magnet roll and charged by applying a voltage to the particles. I have.

However, the remaining problem of these techniques is that it is difficult to obtain stable charging properties during continuous use. For example, as disclosed in Japanese Patent Application Laid-Open No. Hei 6-301265, there is a problem in magnetic brushes. There has been proposed a configuration in which toner is supplied so as to keep the amount of existing toner constant, thereby stabilizing the resistance. All of the above-mentioned methods use discharge development in a minute gap, and there is a problem that the surface of the photoreceptor is damaged by a product generated by the discharge, and the image is easily deteriorated or image flow under high temperature and high humidity. It still remained.

Further, in Japanese Patent Application Laid-Open No. Hei 6-258918, 30 to ¹⁰⁰ μm which is 10 ⁸ to 10 ¹⁰ Ωcm
And 100 to 100 μm which is 10 ⁸ Ωcm or less.
In Japanese Unexamined Patent Publication No. 6-274005, it is possible to mix particles having a particle size of 5 × 10 ⁵ Ωcm
It is disclosed that the above particles and particles of 5 × 10 ⁴ or less are mixed and used as charging particles. Proposals in the form of mixing have been made.

[0013] These have good chargeability due to the particle size and resistance of the particles to be mixed, but if the particle size of the mixed particles is relatively close and the resistance is far away, the particles with low resistance are exposed during use. Since it gathers on the body surface, even if it has good pinhole resistance in the initial stage, it tends to cause pinhole leakage during use. Also, if the particle size is far,
Although it is possible to suppress the tendency of particles having low resistance to separate, there is a problem that particles having low resistance leak out particularly in a low humidity environment.

Furthermore, Japanese Patent Application Laid-Open No. 8-6355 proposes a mixture of magnetic particles having a smooth surface and magnetic particles having a rough surface. In these, the effect of extending the durability is described, but further improvement in the durability is desired.

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

As described above, with respect to magnetic particles as a photosensitive member charging member, it has been insufficient to study the desirable physical properties and their effects from the viewpoint of physical properties. It is desired to develop a suitable composition of the particles.

The cleaning process in electrophotography has conventionally used blade cleaning, fur brush cleaning, roller cleaning, and the like. Either method mechanically scrapes off the transfer residual toner,
Alternatively, it is 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. In fact, 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.

For the above reasons, from the viewpoint of miniaturization of the apparatus and ecology, there has been a demand for a system free of waste toner in terms of effective utilization of toner.

It is a system called cleaning at the same time of development or a cleaner-less system in which the developing means is a substantial cleaning means, that is, between the transfer position and the charging position and between the charging position and the developing position. This is a system in which toner remaining on the photoreceptor after transfer is collected and stored by a developing unit without a cleaning unit. For example, JP-A-59-133573, JP-A-62-203182, JP-A-63-133179,
JP-A-64-20587, JP-A-2-51168, JP-A-2-302772, JP-A-5-2287, JP-A-5-205
2289, JP-A-5-53482, JP-A-5-6138
There are 3 etc. These known techniques use a corona, a brush, or a roller, and have not yet satisfied all of the contamination of the photoreceptor surface due to discharge products, nonuniform charging, and the like.

For this reason, a cleanerless technique using a so-called magnetic brush, which has a relatively small contact load on the photoreceptor and has magnetic particles held by a magnet body, as a charging member has been studied.

For example, Japanese Patent Application Laid-Open No. Hei 4-21873 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. ing. Further, Japanese Patent Application Laid-Open No. Hei 6-118855 proposes an image forming apparatus equipped with a magnetic brush charging cleaning device without an independent cleaning device. Examples of magnetic particles used include iron, chromium, nickel, and cobalt. Metal or alloys or compounds thereof, triiron tetroxide, γ-ferric oxide, chromium dioxide, manganese oxide,
Ferrite, manganese-copper alloy and those coated with styrene resin, vinyl resin, ethylene resin, rosin modified resin, acrylic resin, polyamide resin, epoxy resin, polyester resin, or dispersed magnetic fine particles There are disclosures of particles and the like obtained by using a resin contained in the resin.

[0022]

However, the preferred form of the magnetic particles for charging is not disclosed, and a technical problem remains from the viewpoint of magnetic particles suitable for a cleanerless method.

As described above, there has been a demand for magnetic particles for charging having a preferable configuration as a charging member. Furthermore, a charging device that has stable charging properties during continuous use and can withstand long-term use,
Electrophotographic apparatuses and process cartridges are desired.

Also, in the cleanerless image forming method, there has been a demand for an electrophotographic apparatus capable of stably charging the toner and suitably processing the toner remaining after transfer.

An object of the present invention is to provide charging particles having higher durability than conventional ones, and a charging device, an electrophotographic apparatus, and a process cartridge using the charging particles.

It is another object of the present invention to provide an electrophotographic apparatus and a process cartridge in which the photoreceptor is hardly scraped.

Still another object of the present invention is to provide a charging device and an electrophotographic device which are equipped with a cleanerless system using a charged magnetic brush and are stable for a long period of time.

[0028]

In order to solve the above-mentioned problems, the present invention provides a magnetic particle-dispersed composite particle having a binder resin and magnetic particles dispersed in the binder resin. The abundance is 81 to 9 in the magnetic particle-dispersed composite particles.
The magnetic particle-dispersed composite particles having a particle diameter of 5 μm or more have a standard deviation of minor axis length / major axis length of 0.08 or more and a volume resistance value of 10 ⁴ to 10 ^9. Ωc
m.

According to the present invention, it is possible to obtain a charging device, an electrophotographic apparatus, and a process cartridge which have stable chargeability during continuous use, have low environmental dependency, and have stable chargeability over a long period of time, especially in a cleanerless system. Can be

Further, it is possible to realize an electrophotographic apparatus and a process cartridge having a small load on a member to be charged and having high durability of the entire system.

[0031]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.

As described above as a conventional technique, various magnetic particles may be used as the magnetic particles for charging. However, according to the results of studies by the present inventors, magnetic particles as in the conventional example, as magnetic particles for photoreceptor charging, have many inadequate aspects, and as a result of intensive studies in view of the situation, The present invention has been accomplished by finding one of the preferred embodiments.

The magnetic particles used in the present invention are magnetic particle-dispersed composite particles having a binder resin and magnetic particles dispersed in the binder resin. 81 to 98% by weight of the particles,
The standard deviation of the minor axis length / major axis length of the magnetic particle-dispersed composite particles having a particle diameter of at least m is 0.08 or more, and the volume resistance value is 10 ⁴ to 10 ⁹ Ωcm.

Such a configuration provides a more remarkable effect on durability and image quality than the conventional example. The cause of the deterioration in durability is that the magnetic particles surface is contaminated by toner or toner components mixed into the charging member or foreign matter such as paper powder.
That is, the resistance of the charging member increases, and the surface of the photosensitive member cannot be sufficiently charged.

In particular, at present, the photoreceptor cannot be sufficiently charged for a long period of time in a low humidity environment, that is, there is no sufficient durability.

The effect on the image caused by this problem is as follows, taking a durable image using the reversal development method as an example.
When an image having no initial problem is advanced in durability, first, a ghost image is generated in the photoconductor cycle. At this time, the charged potential of the photoconductor is equal to the initial potential. If you further endurance,
Causes ground fog. At this time, the potential of the photoreceptor has deteriorated from the initial state, and a sufficient potential for obtaining an image without fogging cannot be obtained.

As a mechanism that causes an image problem, ghost images are described in A.1. The difference in charged potential between the exposed portion of the photoconductor and the unexposed portion is large. B. Unremoved toner components remain on the exposed portion of the photoreceptor, hindering the contact between the particles and the surface of the photoreceptor, resulting in uneven charging potential. It is.

As long as the photoreceptor potential is measured by a conventional method, there is no correlation with image quality, and these are problems specific to the contact charging method using particles.

Furthermore, when a so-called cleaner-less image forming apparatus is used instead of the cleaning apparatus in the image forming apparatus, particularly, the ghost image is removed because the portion where the transfer residual toner exists and the exposed portion of the photosensitive member coincide. There are particularly severe conditions.

The effects of the present invention will now be described with reference to a cleaner-less image forming apparatus as an example. The contact between the charged particles and the surface of the photoreceptor is improved, and the photoreceptor can be sufficiently charged even if there is a toner component remaining after transfer.

2. There is a surface cleaning effect between the charged particles, and even when used for a long time, the accumulation of foreign substances on the particle surface is suppressed, and the effect is long lasting. The operation and effect are obtained.

As a result, a stable image can be formed for a long period of time even in a low humidity environment, even when there are multiple components that inhibit the contact on the photoreceptor.

When the standard deviation of the minor axis length / major axis length of the particles of 5 μm or more is smaller than 0.08, the variation in the shape is too small, and the mutual surface cleaning effect is not sufficient. It is considered that due to the variation in shape, a shape suitable for cleaning exists for a certain shape of magnetic particles with respect to the load between charged particles, and the load concentrates to produce a surface cleaning effect. In addition, 5 to 5 of charged particles
The standard deviation of the minor axis length / major axis length of the 20 μm portion is 0.
When it is 08 or more, the surface cleaning effect of particles larger than that is large, which is a preferable configuration. When it is 0.10 or more, the cleaning property is further improved.

Here, a method of measuring the standard deviation of the length of the short axis / the length of the long axis will be described. Hitachi FE-SEM (S-80
0), a particle image magnified 500 times was randomly selected
0 images are extracted, and based on the image information, for example, Image
Statistical processing of the result of the image analysis is performed by Analyzer V10 (manufactured by Toyobo Co., Ltd.).

The details of the analysis are as follows. First, from an electron micrograph, an image signal that has passed through a stereomicroscope is input to an analyzer, and the image information is binarized. Next, the following analysis is performed based on the binarized image information.

For details, refer to Image Analyzer
There is a detailed description in the instruction manual of V10 (manufactured by Toyobo Co., Ltd.), but if the method is briefly described, the procedure of replacing the shape of the object with an ellipse and the length of the major axis and the minor axis of the ellipse will be described. That is to take the ratio. The procedure is as follows.

For the binarized shape of the composite particles,
Assuming that the specific gravity of the small area Δs = Δu · Δv at the coordinates (u, v) is 1, with respect to the origin (X, Y), 2
The second moment about the horizontal axis and the vertical axis (the second moment Mx about the horizontal axis and the second moment My about the vertical axis) passing through the center of gravity of the quantified shape is Mx = ΣΣ (u−X) ² My = ΣΣ (v−Y) ² , where the synergistic moment of inertia Mxy is Mxy = ΣΣ (u−X) · (v−Y), and the angle θ that satisfies the following equation is obtained by solving two solutions. Have. Further, the moment of inertia in the axial direction that forms an angle θ with the horizontal axis is Mθ: Mθ = Mx · (cos θ) ² + My · (sin θ) ² −
Mxy · sin2θ, which is calculated by substituting the two solutions of θ,
The smaller one of θ is the main axis.

Further, when points corresponding to (1 / Mθ) ^0.5 are plotted on an arbitrary axis, they form an ellipse. If this main axis coincides with the main axis of inertia, a direction in which Mθ takes a small value is obtained. If A is B and the larger one is B, the following ellipse is obtained.

A · x ² + B · y ² = 1 In the present invention, the ratio of the minor axis length / major axis length to the above ellipse is as follows: minor axis length / major axis length = (A / B) It is represented by ^0.5 .

The standard deviation of the composite particles having a particle size of 5 μm or more and the composite particles having a particle size of 5 μm to 20 μm is as follows when the maximum chord length of the particles is 5 μm or more and 5 μm to 20 μm in the electron micrograph. Analyze something.

The average particle size and distribution of the charging particles were measured using a laser diffraction type particle size distribution analyzer HELOS (manufactured by JEOL Ltd.) by dividing the range of 0.5 μm to 350 μm into 32 logarithms, and the volume was 50% median. The diameter was defined as the average particle diameter.

In the present invention, the average particle size of the charging composite particles is preferably in the range of 10 to 200 μm.
If it is smaller than 0 μm, particles are likely to leak, and the magnetic particles are inferior in transportability when used as a magnetic brush.

When used in the injection charging method, if it exceeds 40 μm, the charging uniformity of the injection charging method in the present invention tends to deteriorate. More preferably, it is 15 to 30 μm.

As the magnetic particles constituting the magnetic particle-dispersed composite particles used in the present invention, magnetite and ferrite particles are preferably used. Ferrite compositions include copper, zinc, manganese, magnesium, iron,
Those containing a metal element such as lithium, strontium and barium are preferably used.

A preferred method for producing the magnetic particle-dispersed composite particles in the present invention is a method of pulverizing magnetic particle-dispersed composite particles of 20 μm to 20 mm.

Further, after pulverization while controlling the shape distribution, classification can be carried out as appropriate, and the mixture can be used as it is. If necessary, it can be used by mixing with other particles.

As a conventional example, it is disclosed that magnetic particles obtained by kneading and grinding magnetite and a resin are used. However, since a large amount of a resin component is contained, leakage of magnetic particles from a charging member tends to be large. Furthermore, in the case of resin magnetic particles, the ratio of the resin present on the surface is high, and the ratio of the magnetic particles that are the conductive paths is low. From this fact, resistance tends to increase due to surface contamination by foreign matter, and there is a tendency that a sufficient effect of improving durability cannot be obtained.

For this reason, in the present invention, the magnetic particles in the magnetic particle-dispersed composite particles have an abundance of 81 to 98% by weight, thereby preventing the deterioration of the function due to surface contamination by foreign matter. Usually, it is extremely difficult to disperse the magnetic particles in the resin at such a ratio, and therefore, it is preferable to control the shape of the composite particles produced by the following production method.

A preferred example of the present invention is a method in which a monomer forming a binder resin and magnetic particles are mixed to polymerize the monomer. Examples of monomers include phenols and aldehydes, which are capable of suspension polymerization in an aqueous medium. Preferred phenols include alkylphenols such as m-cresol, p-tert-butylphenol, o-propylphenol, resorcinol and bisphenol A.

It is also preferable to include a crosslinking component in order to increase the strength of the composite particles from the viewpoint of improving performance.

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

In terms of particle leakage, the resistance value of the charging composite particles is more preferably 1 × 10 ⁶ Ωcm or more.

The method for measuring the volume resistance of the composite particles is as follows. A cell A shown in FIG. 1 is filled with magnetic particles, electrodes 12 and 13 are arranged in contact with the composite particles, a voltage is applied between the electrodes, Obtained by measuring the current. The measurement conditions are
The contact area between the filled composite particles and the electrode is 2 cm ² , the thickness is 1 mm, the upper electrode is 10 kg, and the applied voltage is 100 V in an environment of 23 ° C. and 65%. 13 is a guide ring, 14 is an ammeter, 15 is a voltmeter, 16 is a constant voltage device, 17 is a measurement sample, and 18 is an insulator.

Further, a preferable resistance distribution according to the present invention is that a difference in resistance between particles having a relatively small particle diameter and particles having a relatively large particle diameter is small.

Preferably, the volume resistivity of the particles of 5 μm to 20 μm of the magnetic particle-dispersed composite particles for charging is Ra,
The volume resistance value of the portion of the composite particles exceeding 20 μm is calculated as Rb
0.5 ≦ Ra / Rb ≦ 5.0, and more preferably 1.0 ≦ Ra / Rb ≦ 5.0.

5 μm to 5 μm of the magnetic particle-dispersed composite particles for charging
In measuring the volume resistance value of the 20 μm particles,
Separate as follows. Prepare sieves having openings of 5 μm and 20 μm. These sieves are Φ75mm × H
It is 20 mm in size and these 5 μm or 20 μm
The method of making the opening of μm is by plating if necessary.
Adjust by increasing the wire diameter of the sieve. Open the screen from the top, and sieve in the order of 25 μm, 20 μm, 5 μm,
0.5 g of the composite particles is placed on a sieve having an opening of 25 μm and sufficiently vibrated to collect the composite particles having a 20 μm pass and a 5 μm ON. Furthermore, what was left on the 5 μm sieve was further
The particles of 5 μm pass are removed by a differential pressure of 200 mmAq. This sample is used for measurement. Samples exceeding 20 μm are mixed with magnetic particles of 20 μm and 25 μm among the above sieves to obtain samples.

When the resistance value of the particles having a relatively small particle diameter is lower than 1/10 of the resistance value of the particles having a relatively large particle diameter, when an oscillating voltage is applied to the charging member, particularly in a low humidity environment, This is because particles having a relatively small particle diameter and a low resistance have a strong tendency to fall off the charging member. In particular, in the case of the cleaner-less image forming method, the tendency to drop off is even stronger.

Further, when particles having relatively small particle diameters and different resistance values by one digit or more are used in combination, particles having low resistance are biased toward the surface of the photoreceptor during use, and the bias of low resistance particles is biased. Therefore, a pinhole leak tends to occur.

In order to make the present invention more effective, it is preferable that the composite particles of the present invention have been treated with a coupling agent having a structure in which 6 or more carbon atoms are linearly connected.

Since the charging composite particles are rubbed against the photoreceptor, the organic photoreceptor is subjected to severe conditions especially in shaving. As an effect by including the constitution of the present invention, lubrication is imparted by a long-chain alkyl group, which has an effect on photoreceptor damage and an effect on contamination of the surface of the charging composite particles. Particularly, when the surface layer of the photoreceptor is made of an organic compound, it has a remarkable effect.

From this viewpoint, it is necessary that the alkyl group has a carbon number of 6 or more, preferably 8 or more, and preferably 30 or less. When the number of carbon atoms is less than 6, the above effect is hardly obtained, and when the number of carbon atoms exceeds 30,
It tends to be insoluble in a solvent, making it difficult to uniformly treat the surface of the composite particles, and further, the flowability of the treated composite particles for charging is extremely deteriorated, and the chargeability tends to be non-uniform.

The amount of the coupling agent is as follows.
0.0 to the charging composite particles including the coupling agent.
It is preferably from 001% by mass to 0.5% by mass. 0.0
If the amount is less than 001% by mass, it is difficult to obtain the effect of the coupling agent. If the amount exceeds 0.5% by mass, the flowability of the composite particles for charging is deteriorated, and the charging tends to be uneven. More preferably, the amount is 0.001% by mass or more and 0.2% by mass or less.

In the present invention, the surface of the magnetic particles for charging is basically preferably composed of only a coupling agent. However, it is also possible to coat a small amount of a resin component. In this case, an amount equivalent to the amount of the coupling agent is preferable.

Further, it can be used in combination with resin-coated magnetic particles for charging. In this case, the mixing ratio is preferably 50% by mass or less based on the mass of the composite particles in the charger. 5
If the content exceeds 0% by mass, the effect of the present invention is reduced.

As the coupling agent used in the present invention, a central element such as titanium, aluminum, silicon, and zirconium may be used as long as the hydrophobic group has a structure in which six or more carbon atoms are linearly connected. Do not choose.

The coupling agent in the present invention refers to a compound having a hydrolyzable group and a hydrophobic group in the same molecule and bonded to a central element such as silicon, aluminum, titanium and zirconium.

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

The hydrophobic group may be any as long as it has a structure in which at least 6 carbon atoms are linearly linked in its structure. In the form of bonding with the central element, carboxylate, alkoxy, sulfone They may be bonded via an acid ester or a phosphoric ester or directly. Further, the structure may contain a functional group such as an ether bond, an epoxy group, or an amino group.

Some specific examples of the compounds that can be used in the present invention include:

[0080]

Embedded image

[0081]

Embedded image

Further, in the case where the coupling agent is present on the surface of the charging composite particles of the present invention, the amount of the coupling agent is not more than 0.1.
Since it is 5% by mass or less, preferably 0.2% by mass or less, a resistance value approximately equal to that of the composite particles not present on the surface can be obtained. High stability in production and quality.

Further, the reaction rate of the coupling agent is 80%
It is preferably at least 85%, more preferably at least 85%. This is because, in the present invention, since a coupling agent having a relatively long alkyl group is used, if the proportion of unreacted substances is large, the fluidity is deteriorated. Also, when the photoreceptor surface to be used is substantially a non-crosslinked resin,
Unreacted processing agents may permeate the photoreceptor surface and cause fogging and fogging. For this reason, it is preferable to use a coupling agent that can react with the surface of the magnetic particles.

As a method of measuring the reaction rate of the coupling agent, a solvent capable of dissolving the coupling agent to be used may be selected, and the abundance before and after washing may be measured.

For example, a means for quantifying the coupling agent component in the solvent by immersing it in a solvent 100 times the amount of the treated composite particles by chromatography, or the coupling agent component remaining on the composite particle surface after washing is used. , ESCA, CHN,
Means for quantifying by a method such as TGA and quantifying the abundance before and after washing can be used.

In the charging device and the electrophotographic device of the present invention, the injection charging method can be preferably used.

As the injection charging method, by using a photoconductor in which the electrophotographic photoconductor is farthest from the support and has a charge injection layer, 80% of the applied voltage when only DC charging is applied to the charging member is used. As described above, the effect that a charging potential of 90% or more can be obtained can be obtained.
Therefore, an ozone-less charging method can be further realized in comparison with the charging method interpreted by Paschen's law.

The charge injection layer has a volume resistivity of 1 × 1 in order to satisfy the conditions for sufficient chargeability and image deletion.
0 ⁸ is preferably in the range of Ωcm~1 × 10 ¹⁵ Ωcm. More preferably, the volume resistance value is 1 × 10 ¹⁰ Ωcm to 1 × 10 ¹⁵ Ωcm from the viewpoint of image deletion, and the volume resistance value is 1 × 10 ¹² Ωcm to 1 × in consideration of environmental changes.
It is preferable to use one of 10 ¹⁵ Ωcm. 1 × 10 ⁸
If the volume resistance value is smaller than Ωcm, the electrostatic latent image cannot be retained, and image deletion occurs particularly in a high-temperature and high-humidity environment.
If the resistance value is larger than × 10 ¹⁵ Ωcm, the charge from the charging member cannot be sufficiently received, and poor charging tends to occur.

Further, in the charging device and the electrophotographic apparatus of the present invention, it is preferable to apply an oscillating voltage as the voltage applied to the photosensitive member charging member. The effect of applying the oscillating voltage is that a stable charge can be obtained with respect to disturbance such as mechanical accuracy.

In the injection charging method, when an oscillating voltage is applied, the above-described advantages can be obtained. However, the applied oscillating voltage is limited, and is limited to 100 Hz to 10 Hz.
A frequency of about kHz is preferable, and the peak-to-peak voltage is
Preferably, the voltage is 1000 V or less. In the injection charging method, since the photoconductor potential follows the applied voltage, if the peak-to-peak voltage is too large, the potential of the photoconductor charging surface becomes wavy, which may cause fog or reversal fog. Because.

[0091] Regarding the oscillating voltage, the effective peak-to-peak voltage is 100 V or more, preferably 300 V or more.
V or more. As the waveform, a sine wave, a rectangular wave, a sawtooth wave, or the like can be used.

The charge injection layer can be made of a material having a medium resistance by dispersing an appropriate amount of light-transmitting and conductive particles in an insulating binder resin. Is also an effective means. By providing such a functional layer surface, it plays a role of holding the charge injected from the charging member, and also plays a role of releasing this charge to the photosensitive member support during exposure, thereby reducing the residual potential.

Here, the volume resistance of the surface layer of the photoreceptor is determined by using polyethylene terephthalate (PE) having gold deposited on the surface.
T), a layer (3 μm) similar to the surface layer was formed, and this was used as a volume resistance measuring device (414 manufactured by Hewlett-Packard Company).
0B pAMATER) at a temperature of 23 ° C and a relative humidity of 65
%, A voltage of 100 V was applied in the environment and the measurement was performed.

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

Preferably, the charge injection layer contains a lubricant powder. The expected effect is that the friction between the photosensitive member and the charging member during charging is reduced, the nip involved in charging is enlarged, and the charging characteristics are improved. In addition, since the releasability of the photoreceptor surface is improved, magnetic particles are less likely to adhere. In particular, as the lubricant particles, it is preferable to use a fluororesin, a silicone resin or a polyolefin resin having a low critical surface tension. Particularly preferably, 4
A fluorinated polyethylene resin is used.

In this case, the amount of the lubricant powder to be added is preferably 2 to 50 parts by weight based on 100 parts by weight of the binder resin.
More preferably, it is 5 to 40 parts by mass. If the amount is less than 2 parts by mass, the amount of the lubricant powder is not sufficient, 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. Also, 50
When the amount exceeds the mass part, the resolution of the image and the sensitivity of the photoreceptor tend to decrease.

When the surface layer is coated with an inorganic layer, the underlying photosensitive layer is preferably made of amorphous silicon, and a blocking layer, a photosensitive layer and a charge injection layer are sequentially formed on a cylinder by glow discharge or the like. Is preferred.

As the photosensitive layer, conventionally known ones can be used. For example, if it is 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 substrate for the photoreceptor include metals such as aluminum, nickel, stainless steel, and steel.
Plastic or glass having a conductive film, conductive paper, or the like can be used.

As another effect of the present invention, when the applied voltage is a DC voltage on which an oscillating voltage is superimposed, the vibration noise caused by the oscillating electric field is reduced. It is considered that vibration is absorbed by the variation in shape. Furthermore,
The thickness of the conductive substrate of the photoconductor is 0.5 mm or more and 3.0 m or more.
In the case of m or less, the effect is remarkable. If it is less than 0.5 mm, the vibration noise tends to increase, and if it exceeds 3 mm, the rotational torque increases, and if it exceeds 3 mm, it is disadvantageous in terms of cost such as an increase in material cost.

There is also a preferable range in the triboelectric charging property between the toner used and the magnetic particles of the charging member. Value is the same as the charging polarity of the photoreceptor, and its absolute value is 1 to 90 mC / kg, preferably 5 to 80 mC / kg, and more preferably 10 to 4 mC / kg.
When it is 0 mC / kg, the characteristics of taking in and sweeping out the toner and charging of the photosensitive member are good.

A preferred measuring method is as follows. First, under an environment of a temperature of 23 ° C. and a relative humidity of 60%, a mixture obtained by adding 200 mg of toner to 40 g of magnetic particles to be measured is 50 to 50%.
Shake by hand 150 times in a 100 ml polyethylene bottle. A mixture of the toner to be used and the magnetic particles for charging is loaded as magnetic particles for a charging member. Next, a metal drum having the same dimensions as the photoreceptor to be used is loaded, a DC bias having the same polarity as the toner charging polarity is applied to the charging portion, and the photoreceptor is driven under the conditions for charging. The charge amount of the transferred toner is measured.

In the electrophotographic apparatus of the present invention, when a magnetic brush made of composite particles is used as a charging member that comes into contact with the photoreceptor, the configuration is such that a magnet roll or an internal roller is used as a magnetic particle holding member. A conductive sleeve having a magnet roll and a composite particle uniformly coated on the surface thereof are used. In particular, a conductive sleeve having a magnet roll and the surface coated with magnetic particles are preferably used.

The closest gap between the charging magnetic particle holding member and the photosensitive member is preferably 0.3 mm to 2.0 mm. When it is closer than 0.3 mm, depending on the applied voltage,
Leakage may occur between the conductive portion of the magnetic particle holding member for charging and the photoconductor, which may damage the photoconductor.

The charging magnetic brush does not move in the forward and reverse directions at the contact portion with respect to the moving direction of the photosensitive member, but moves in the opposite direction from the viewpoint of taking in the residual toner after transfer. preferable.

The amount of the magnetic particles for charging held by the magnetic particle holding member for charging is preferably 50 to 500 mg / c.
m ² , more preferably 70 to 210 mg / cm ² , can provide stable chargeability.

Further, extra magnetic particles for charging may be held in the charger and circulated. As image exposure means,
Known means such as a laser and an LED can be used.

Further, in the present electrophotographic apparatus, a preferable step in the cleanerless image forming method can be added. After the transfer step in the electrophotographic apparatus of the present invention,
And by having a photoconductor potential control member before the charging step,
The stability is further improved as an electrophotographic apparatus.

As the photosensitive member potential control member, a member that emits light to control the photosensitive potential, or a conductive roller, blade, or fur brush arranged in contact with or in close proximity is used. Among them, a roller and a fur brush are particularly preferably used. When a voltage is applied to these to control the potential of the photoconductor, it is preferable to control the polarity to the opposite of that of the charging step of the photoconductor. The reason is that the photoconductor potential is adjusted to a lower one before the photoconductor charging step, and the history of the pre-formed image is erased to help uniform charging.

The developing means is not particularly limited, but in the case of an image forming apparatus having no cleaning means, reversal development is preferable, and a structure in which the developer and the photoreceptor are in contact is preferable. For example, a contact two-component development method, a contact one-component method, and the like can be mentioned as suitable development methods. 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 unit. . Regarding the bias applied to the development, it is preferable that the DC component comes between the potential of the black portion (image exposed portion) and the potential of the white portion.

Further, a known method such as a corona, a roller, or a belt is used as the transfer means.

Further, when the transfer residual toner is collected, and is conveyed to the developing portion by utilizing the surface of the photoreceptor by using the surface of the photoreceptor and is collected and reused, it can be realized without changing the photoreceptor charging bias. However, in practice, when a transfer paper jam occurs or when images with a high image ratio are continuously taken, it is conceivable that the toner may be mixed into an excessive amount of the toner charger.

In this case, during the image forming operation, it is possible to move the toner from the charger to the developing machine by utilizing a portion where no image is formed on the photosensitive member. The image forming portion is, for example, during pre-rotation, post-rotation, and between transfer sheets.
In that case, it is also preferable to change the charging bias so that the toner is more easily transferred to the photoconductor than the charger. As the bias that easily comes out of the charger, the AC component is set to a smaller peak-to-peak voltage or a DC component. Alternatively, there is a method in which the peak-to-peak voltage is made the same and the waveform is changed to reduce the AC effective value.

Further, in the present invention, in consideration of the life of the charger portion and the use of a non-magnetic sleeve containing a magnet, it is preferable that the toner can be further added due to cost requirements. In such a case, it is preferable that the magnetic particles for charging are present in the charged portion in a larger amount than the minimum required amount, and the durability is further increased by circulating the magnetic particles.

As means for circulating, it is preferable to provide mechanical stirring or a magnetic pole structure capable of circulating the magnetic particles, or a member for moving the magnetic particles in a container storing the magnetic particles. preferable. For example,
Screw member to stir behind magnetic brush, or
Examples include a configuration in which a repulsion pole is provided and recoating is performed while the magnetic particles are being peeled off, and an obstruction member that obstructs the flow of the magnetic particles is provided.

Further, a process cartridge based on the present charging member can be prepared.

Hereinafter, the present invention will be described with reference to Examples, but the present invention is not limited thereto.

First, the structure, material, manufacturing method and the like of the members used in the present invention will be exemplified.

[Production Example 1 of Magnetic Particles for Charging] After mixing and dispersing 50 parts by weight of a phenol monomer and 50 parts by weight of a formaldehyde monomer in an aqueous medium, 950 parts by weight of magnetite particles hydrophobicized with a titanium coupling agent were added. The particles were uniformly dispersed, and the monomer was polymerized while adding ammonia to obtain magnetic particle-dispersed composite particles having an average particle diameter of 50 μm.

Table 1 summarizes the characteristics.

[Production Example 2 of Magnetic Particles for Charging] After mixing and dispersing 50 parts by weight of a phenol monomer and 50 parts by weight of a formaldehyde monomer in an aqueous medium, 950 parts by weight of magnetite particles hydrophobized with a titanium coupling agent were added. The particles were uniformly dispersed, and the monomers were polymerized while adding ammonia to obtain magnetic particle-dispersed composite particles having an average particle diameter of 27 μm.

Table 1 summarizes the characteristics.

[Production Example 3 of Magnetic Particles for Charging] To 40 parts by weight of styrene resin, 60 parts by weight of magnetite were added, melt-kneaded, and cooled and pulverized to obtain magnetic particles having an average diameter of 25 μm.

Table 1 summarizes the characteristics.

[Production Example 4 of Magnetic Particles for Charging] To 30 parts by weight of styrene resin, 5 parts by weight of conductive carbon black and 40 parts by weight of magnetite were added, melt-kneaded, and cooled and pulverized to obtain magnetic particles having an average diameter of 10 μm. Was.

Table 1 summarizes the characteristics.

[Production Example 5 of Magnetic Particles for Charging] The particles obtained in [Production Example 1 of Magnetic Particles for Charging] were obtained by using an air-jet mill.
While checking the shape, the mixture was pulverized and classified to obtain magnetic particle-dispersed composite particles.

Table 1 summarizes the characteristics.

[Example 6 of Production of Magnetic Particles for Charging] The particles obtained in Example 1 of Production of Magnetic Particles for Charging were
While checking the shape, the mixture was pulverized and classified to obtain magnetic particle-dispersed composite particles.

Table 1 summarizes the characteristics.

[Production Example 7 of Magnetic Particles for Charging] 15 parts by weight of styrene resin, 15 parts by weight of toluene and 85 parts of magnetite
By weight, the mixture was melt-kneaded, removed from the solvent, and cooled and pulverized to obtain magnetic particles having an average diameter of 25 μm.

Table 1 summarizes the characteristics.

[Production Example 8 of Magnetic Particles for Charging] 99 parts by weight of magnetite was added to 1 part by weight of styrene resin, and melt kneading was attempted, but no particles could be formed.

[Production Example 9 of Magnetic Particles for Charging] The particles obtained in Production Example 2 of Magnetic Particles for Charging and the particles obtained in Production Example 5 of Magnetic Particles for Charging were mixed at a weight ratio of 1: 1.

Table 1 summarizes the characteristics.

[Production Example 10 of Magnetic Particles for Charging] The particles obtained in Production Example 2 of Magnetic Particles for Charging and the particles obtained in Production Example 5 of Magnetic Particles for Charging were mixed in a weight ratio of 8: 2. .

Table 1 summarizes the characteristics.

[Charging Magnetic Particle Production Example 11] The particles obtained in [Charging Magnetic Particle Production Example 2] and the particles obtained in [Charging Magnetic Particle Production Example 5] were mixed at a weight ratio of 9: 1. .

Table 1 summarizes the characteristics.

[Charging Magnetic Particle Production Example 12] The particles obtained in [Charging Magnetic Particle Production Example 3] and the particles obtained in [Charging Magnetic Particle Production Example 4] were mixed at a weight ratio of 1: 1. .

Table 1 summarizes the characteristics.

[Production Example 13 of Magnetic Particles for Charging] Produced in [Production Example 5 of Magnetic Particles for Charging] in a solution of titanium coupling agent, 0.1 parts by weight of isopropoxytriisostearoyl titanate and 20 parts by weight of toluene. 100 parts by mass of the obtained magnetic particles, and kept at 70 ° C. while stirring,
After evaporating the solvent, it was placed in an oven at 200 ° C. for curing. The properties are summarized in Table 1.

[Production Example 14 of Magnetic Particles for Charging] A magnetic material prepared in [Production Example 5 of Magnetic Particles for Charging] in a solution dissolved in 0.1 part by weight of a silane coupling agent, dodecyltrimethoxysilane and 25 parts by weight of ethanol. 100 parts by mass of the particles were added, and the mixture was kept at 50 ° C. with stirring. After the solvent was evaporated, the mixture was placed in an oven at 100 ° C. and cured. The properties are summarized in Table 1.

[0145]

[Table 1]

[Photoreceptor Production Example 1] φ30 mm, thickness 0.
Four functional layers are provided on a 75 mm aluminum cylinder.

The first layer is a subbing layer, and is a conductive layer having a thickness of about 20 μm provided to smooth out defects of the aluminum drum and to prevent the occurrence of moire due to the reflection of laser exposure.

The second layer is a positive charge injection preventing layer, which serves to prevent positive charges injected from the aluminum substrate from canceling out negative charges charged on the surface of the exposed body, and comprises an amylan resin and methoxymethylated nylon. By 10 ⁶ Ω
This is a medium resistance layer having a thickness of about 1 μm and a resistance adjusted to about cm.

The third layer is a charge generation 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 when subjected to 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, the negative charges charged on the photoreceptor surface cannot move through this layer, and only the positive charges generated in the charge generation layer can be transported to the photoreceptor surface. Thickness 1
The thickness was 5 μm.

The surface resistance of the photoreceptor was 3 × 10 ¹⁵ Ωcm in the case of the charge transport layer alone.

The charge injection layer is formed on the fifth layer. The charge injection layer is obtained by dispersing SnO ₂ ultrafine particles in a photocurable acrylic resin. Specifically, 150 parts by mass of SnO ₂ particles having a particle diameter of about 0.03 μm, which is doped with antimony and reduced in resistance, is added to 100 parts by mass of resin, and 20 parts by mass of tetrafluoroethylene resin particles are further dispersed. 1.2 parts by mass of the agent. 2.5 μm thick. Thus, the surface resistance of the photoreceptor is 2 × 10 ¹³ Ωcm.

[Photoreceptor Production Example 2] φ30 mm, thickness 1.
Except that we used a 0mm aluminum cylinder
A photoconductor was manufactured in the same manner as in [Photoconductor Manufacturing Example 1].

[Photoreceptor Production Example 3] φ30 mm, thickness
Except that we used a 5mm aluminum cylinder
A photoconductor was manufactured in the same manner as in [Photoconductor Manufacturing Example 1].

[Photoreceptor Production Example 4] φ30 mm, thickness 4.
Except that we used a 0mm aluminum cylinder
A photoconductor was manufactured in the same manner as in [Photoconductor Manufacturing Example 1].

[Developer Production Example 1] Styrene acrylic resin 100 parts by weight Metal-containing azo dye 2 parts by weight Low molecular weight polypropylene 2 parts by weight Carbon black 5 parts by weight After dry-mixing the above materials, biaxial kneading set at 150 ° C. It was kneaded with an extruder. 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. To this toner composition, 0.5 wt% of hydrophobically treated titanium oxide and 1.0 wt% of hydrophobicized silica were externally added to prepare a toner having a weight average particle diameter of 7.4 μm.

Also, a nickel zinc ferrite having an average diameter of 50 μm coated with a silicone resin was used for 100
The developer was prepared by mixing 6 parts by weight of the toner with respect to parts by weight.

[Developer Production Example 2] 89 parts by weight of styrene
11 parts by weight of n-butyl acrylate, 0.2 parts by weight of divinylbenzene, 2 parts by weight of low molecular weight polypropylene, 4 parts by weight of carbon black, 1.2 parts by weight of a metal-containing azo dye,
3 parts by weight of an azo initiator are dispersed and mixed, and the above solution is added to 500 parts by weight of pure water in which 4 parts by weight of calcium phosphate is dispersed, and the mixture is dispersed by a homomixer, and polymerized at 70 ° C. for 8 hours to obtain a polymer. After filtration and washing, dry classification is performed,
A toner composition was obtained.

The above toner composition was added to 0.4 wt% of hydrophobically treated titanium oxide and 1.0% of hydrophobically treated silica.
wt% was externally added to prepare a toner having a weight average diameter of 6.4 μm.

The obtained toner is formed by a polymerization method, and when observed with an electron microscope, shows a true spherical shape.

A nickel-zinc ferrite having an average diameter of 50 μm coated with a silicone resin was treated with 100%
6 parts by mass of the toner was mixed with the parts by mass to obtain 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 apparatus is generally provided with a corona charger as a charging means for the photoreceptor, a one-component developing device employing a one-component jumping developing method as a developing means, and a corona charger, a blade cleaning means, a pre-charging exposure means as a transferring means. Is provided. The photosensitive member charger, the cleaning means, and the photosensitive member are an integrated unit (process cartridge). Process speed 1
50 mm / s. The digital copier was modified as follows.

First, the process speed was set to 200 mm / s
And remodeled.

The developing components were changed from one-component jumping development to
Modifications were made so that a two-component developer could be used. Further, a 16Φ conductive non-magnetic sleeve containing a magnet roller is arranged on the charged portion to form a charging magnetic brush. 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 portion and the photosensitive member was set to 0.5 mm.

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 is removed,
It was a cleanerless copying machine. FIG. 2 shows a schematic diagram.

[0169]

[Embodiment 1] [Digital copier 1]
The magnetic particles are brought into close contact with the charger so that the coating density becomes 130 mg / cm ^2, and the photoreceptor is mounted.

In order to mount it at 180 mg / cm ² , a minimum amount of about 20 g is required.

The magnetic brush charger is rotated in the opposite direction at the contact portion with the photosensitive member. At this time, the charger rotation peripheral speed is 240 mm / s.

In the evaluation mode, first, the bias applied to the charging member is a DC voltage of -700 V and 1 kV.
Hz, a rectangular wave oscillation voltage of 700 Vpp
/ Under the condition of 10% relative humidity, the developing bias is −50.
A rectangular wave of 1000 Vpp / 3 kHz is superimposed on the DC component of 0 V, the image of FIG. 7 is copied, and the image is evaluated.

The durability test is performed as follows. An image ratio of 15% is obtained by rotating the image at a rotational peripheral speed of 300 mm / s under a condition of 50 mm.
In the intermittent sheet mode, 200 cycles, that is, 10,000 sheets are copied, and the same evaluation as in the initial stage is performed. At this time, in the non-image forming section, during continuous paper feeding, at the time of charging (at the time of pre-rotation) before image formation of the first first sheet, during image formation (between sheets), and at the time of 500th sheet At the time of charging the photoconductor after the completion (post-rotation), a DC voltage of -700 V and a rectangular wave AC component of 1 kHz and 500 Vpp are applied to charge the photoconductor and expose the toner mixed into the charged magnetic brush. Move on the body and collect at the developing part.

[Production Example 5 of Magnetic Particles], [Production Example 2 of Developer]
And [Photoconductor Production Example 1], the above evaluation is performed. During endurance, the noise generated by interference between the magnetic particles for charging and the photoreceptor due to the bias voltage applied to the charging member is at a level that is hardly noticeable.

As a result, the image was substantially free of fog at a peripheral speed of the charger of 240 mm / s, and good results were obtained. The durability was further improved, and fog caused by scraping of the photoreceptor occurred at 30,000 sheets. However, the fog was improved by replacing the photoreceptor.

Further, the charging composite particles are sampled every 10,000 sheets to estimate the amount of contamination. The method of estimating the amount of contamination is as follows: Electron micrograph of the particles before use (500x)
And the electron micrograph (500 times) of the sampled magnetic particles for charging during use. ○: level at which sediment is observed at 1/10 or less of the particle surface ○ △: 1 / of the particle surface Over 10 and 1/3 or less, the level at which sediment is observed. △: Over 1/3 of the particle surface, and at 1/2 or less, the level at which sediment is observed. Δ ×: Over 1/2 of the particle surface. , 2/3 or less, a level at which a deposit is observed. ×: Exceeds 2/3 of the particle surface and is judged as a level at which a deposit is observed.

Table 2 summarizes the results. Further, when the frictional chargeability of the toner used in [Magnetic Particle Production Example 7] and [Developer Production Example 5] was confirmed, it was minus which is the same polarity as the charging polarity of the photoconductor of this example.

(Examples 2 to 7) The same evaluation as in Example 1 was performed using the combinations shown in Table 2. Table 2 summarizes the results. Fogging due to scraping of the photoreceptor has occurred up to 30,000 sheets, and the image quality is evaluated by exchanging the photoreceptor.

In Example 7, the image quality was almost the same except that some fog occurred at 30,000 sheets.

During the durability of each embodiment, the noise generated by the interference between the magnetic particles for charging and the photoreceptor due to the bias voltage applied to the charging member is at a level that is hardly noticeable.

The frictional charging properties of the magnetic particles used in Examples 2 to 7 and the toners used in [Developer Production Example 1] and [Developer Production Example 2] were confirmed. The negative polarity was the same as the charging polarity of the photoconductor of the example.

(Examples 7 and 8) The same evaluation as in Example 1 was performed using the combinations shown in Table 2. Table 2 summarizes the results. During the durability of each embodiment, the noise generated by the interference between the magnetic particles for charging and the photosensitive member due to the bias voltage applied to the charging member is at a level that is hardly noticeable.

Further, as for the photoreceptor, no fog due to shaving of the photoreceptor was found even at 30,000 sheets.

When the triboelectric charging properties of the magnetic particles used in Examples 7 and 8 and the toner used in [Developer Production Example 2] were confirmed, the charging polarity of the photoreceptor of this example was confirmed. The same polarity was minus.

(Comparative Examples 1 to 3)
The same evaluation as in the example was performed. Table 2 summarizes the results. However, in Comparative Example 1 and Comparative Example 2, the level of the noise generated by the interference between the magnetic particles for charging and the photoconductor was slightly anxious due to the bias voltage applied to the charging member during image formation. In order to lower the level to a level not to cause any concern, [Photoconductor Production Example 4] having an aluminum cylinder thickness of 3.5 mm was used.

[0186]

[Table 2]

In Comparative Example 1, fog was good at the beginning, but after about 20,000 sheets, the image became slightly noticeable and the amount of contamination was as high as 0.95%. This is because the standard deviation of the minor axis length / major axis length of the magnetic particles used is small.

In Comparative Example 2, although there was no problem at the beginning, the magnetic particles gradually leaked because the resistance value of the particles of 5 to 20 μm was slightly low, A leak image during the durability, which is considered to be caused by the bias, was generated. The standard deviation of the minor axis length / major axis length of the magnetic particles is 0.1, but the magnetic particles for charging interfere with the photoconductor due to the low resistance value in the region of 5 to 20 μm. It is considered that the level of the sound generated due to was anxious.

In Comparative Example 3, a fog level occurred at the initial stage without any problem, but a fog image was generated at 10,000 sheets. It is considered that the chargeability of the photoreceptor is inferior because the amount of the magnetic particles in the used composite particles is small.

[0190]

As described above, according to the present invention, it has become possible to obtain a stable and long-term image.

[Brief description of the drawings]

FIG. 1 is an explanatory view schematically showing a method for measuring the volume resistance of magnetic particle-dispersed composite particles for charging according to the present invention.

FIG. 2 is a longitudinal sectional view schematically showing a configuration of an electrophotographic digital copying machine according to the present invention.

[Explanation of symbols]

 A Measurement cells 11, 12 Electrodes 13 Guide ring 14 Ammeter 15 Voltmeter 16 Constant voltage device 17 Measurement sample 18 Insulator 201 Image fixing device 202 Charger 203 Magnetic particles for charging 204 Conductive sleeve containing magnet 205 Photoconductor 206 Image exposure 207 Developing sleeve 208 Developing device 209, 210 Stirring screw 211 Developer 212 Paper transport guide 213 Transfer paper 214 Transfer roller 215 Paper transport belt

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Toshio Takamori 3-30-2 Shimomaruko, Ota-ku, Tokyo F-term in Canon Inc. (reference) 2H003 BB11 CC04 EE11 2H068 AA01 AA03 AA04 AA54 BB06 BB31 BB59 CA37 FA27

Claims (41)

[Claims] 1. A magnetic particle-dispersed composite particle having a binder resin and magnetic particles dispersed in the binder resin, wherein the amount of the magnetic particle is 81% in the magnetic particle-dispersed composite particle.
And the standard deviation of minor axis length / major axis length of the magnetic particle-dispersed composite particles having a particle size of 5 μm or more is 0.08 or more, and the volume resistance value is 10 ⁴ to 10. ⁹
Magnetic particle-dispersed composite particles for charging, characterized by having a Ωcm. 2. The method according to claim 1, wherein the composite particles of magnetic particles dispersed for charging are 5
2. The magnetic particle-dispersed composite particles for charging according to claim 1, wherein the standard deviation of the minor axis length / major axis length of the particles of μm to 20 μm is 0.08 or more. 3. The charging magnetic particle-dispersed composite particles 5
2. The magnetic particle-dispersed composite particles for charging according to claim 1, wherein the standard deviation of the minor axis length / major axis length of the particles of μm to 20 μm is 0.10 or more. 4. The magnetic particle-dispersed composite particles for charging 5
0.5 ≦ Ra / Rb ≦ 5.0, where Ra is the volume resistance value of the particles in the range of μm to 20 μm and Rb is the volume resistance value of the portion of the composite particles exceeding 20 μm. 4. The magnetic particle-dispersed composite particles for charging according to any one of items 3 to 3. 5. The magnetic particle-dispersed composite particles for charging 5
5. When the volume resistance value of the particles in the range of μm to 20 μm is Ra and the volume resistance value of the composite particles exceeding 20 μm is Rb, 1.0 ≦ Ra / Rb ≦ 5.0. Magnetic particle-dispersed composite particles for charging. 6. The magnetic particle dispersion-type composite particles for charging,
The magnetic particle dispersion for charging according to any one of claims 1 to 5, which is produced by crushing magnetic particle-dispersed composite particles having a binder resin and magnetic particles dispersed in the binder resin. Type composite particles. 7. The charging magnetic particle-dispersed composite particles,
The magnetic particle-dispersed composite particles for charging according to any one of claims 1 to 6, further comprising a coupling agent having a linear alkyl group having a carbon number of ₆ or more on the surface thereof. 8. A magnetic particle-dispersed composite particle comprising a binder resin and magnetic particles dispersed in the binder resin on a magnet body having a conductive portion to which a voltage is applied, wherein the magnetic particles are present. The amount is 81 to 98% by weight in the magnetic particle-dispersed composite particles, and the standard deviation of the minor axis length / major axis length of the magnetic particle-dispersed composite particles having a particle diameter of 5 μm or more is 0.08. And the volume resistance is 10 ⁴ to 10 ⁹ Ωc
m. A charging member carrying the magnetic particle-dispersed composite particles of m. 9. The charging member according to claim 8, wherein the magnet body having a conductive portion to which the voltage is applied is a conductive sleeve containing the magnet body. 10. The standard deviation of minor axis length / major axis length of particles of 5 μm to 20 μm of the magnetic particle dispersed composite particles for charging is 0.08 or more. Item 2. The charging member according to item 1. 11. The standard deviation of minor axis length / major axis length of particles of 5 μm to 20 μm of the magnetic particle-dispersed composite particles for charging is 0.10 or more. Item 2. The charging member according to item 1. 12. The volume resistivity of particles of 5 μm to 20 μm of the magnetic particle-dispersed composite particles for charging is Ra, and the volume resistance of a portion of the composite particles exceeding 20 μm is Rb.
The charging member according to claim 8, wherein 0.5 ≦ Ra / Rb ≦ 5.0. 13. The volume resistivity of the particles of 5 μm to 20 μm of the magnetic particle-dispersed composite particles for charging is Ra, and the volume resistance of the portion of the composite particles exceeding 20 μm is Rb.
13. The charging member according to claim 12, wherein 1.0 ≦ Ra / Rb ≦ 5.0. 14. The magnetic particle-dispersed composite particles for charging are produced by pulverizing magnetic particle-dispersed composite particles having a binder resin and magnetic particles dispersed in the binder resin. 14. The charging member according to any one of 8 to 13. 15. The magnetic particle-dispersed composite particles for charging have a coupling agent having a linear alkyl group having a carbon number of C ₆ or more on the surface thereof.
The charging member according to any one of the above. 16. A charging device for charging an image carrier by bringing a charging member to which a voltage is applied into contact with the image carrier,
The charging member is a magnet body having a conductive portion to which a voltage is applied, and a magnetic particle-dispersed composite particle having a binder resin and magnetic particles dispersed in the binder resin, wherein the abundance of the magnetic particles Is 81 to 98% by weight in the magnetic particle-dispersed composite particles, and the standard deviation of the minor axis length / major axis length of the magnetic particle-dispersed composite particles having a particle diameter of 5 μm or more is 0.08 or more. And the volume resistance value is 10 ⁴ to 10 ⁹ Ωc.
a magnetic particle-dispersed composite particle of m. 17. The charging device according to claim 16, wherein the magnet body having a conductive portion to which the voltage is applied is a conductive sleeve containing the magnet body. 18. The standard deviation of minor axis length / major axis length of particles of 5 μm to 20 μm of the magnetic particle-dispersed composite particles for charging is 0.08 or more. Item 2. The charging device according to item 1. 19. The standard deviation of minor axis length / major axis length of particles of 5 μm to 20 μm in the magnetic particle dispersion type composite particles for charging is 0.10 or more. Item 2. The charging device according to item 1. 20. The volume resistivity of the particles of 5 μm to 20 μm of the magnetic particle-dispersed composite particles for charging is Ra, and the volume resistivity of the portion of the composite particles exceeding 20 μm is Rb.
The charging device according to claim 16, wherein 0.5 ≦ Ra / Rb ≦ 5.0. 21. The volume resistance value of the particles in the range of 5 μm to 20 μm of the magnetic particle-dispersed composite particles for charging is Ra, and the volume resistance value of the composite particles exceeding 20 μm is Rb.
21. The charging device according to claim 20, wherein 1.0 ≦ Ra / Rb ≦ 5.0. 22. The magnetic particle-dispersed composite particles for charging are produced by pulverizing magnetic particle-dispersed composite particles having a binder resin and magnetic particles dispersed in the binder resin. 22. The charging device according to any one of 16 to 21. 23. The magnetic particle-dispersed composite particle for charging has a coupling agent having a linear alkyl group having a carbon number of C ₆ or more on the surface thereof.
3. The charging device according to any one of 2. 24. The charging device according to claim 16, wherein the applied voltage is a DC voltage on which an oscillating voltage is superimposed. 25. The peak-to-peak voltage of the oscillating voltage is 100.
The charging device according to any one of claims 16 to 24, wherein the voltage is 0 V or less. 26. The image carrier has a conductive substrate and a photosensitive layer, a layer furthest from the conductive substrate is a charge injection layer, and the charge injection layer has a volume resistivity of 1 × 10 ⁸ to
26. Any one of claims 16 to 25, which has a density of 1 × 10 ¹⁵ Ωcm.
The charging device according to Item. 27. The image bearing member according to claim 16, wherein the photosensitive member has a photosensitive layer formed on a conductive cylindrical substrate, and the conductive substrate has a thickness of 0.5 mm or more and 3.0 mm or less. 27. The charging device according to any one of claims 26 to 26. 28. A developing method in which a voltage is applied, a magnetic body carrying magnetic particles is brought into contact with a photosensitive member, charged, an electrostatic latent image is formed by image exposure, and the electrostatic latent image is visualized with toner. An electrophotographic apparatus having a transfer member for transferring the magnetic particles to a transfer material, wherein the magnetic particles are magnetic particle-dispersed composite particles having a binder resin and magnetic particles dispersed in the binder resin. The magnetic particles are present in an amount of 81 to 98% by weight in the magnetic particle-dispersed composite particles;
The magnetic particle-dispersed composite particles having a particle size of 5 μm or more have a standard deviation of the minor axis length / major axis length of 0.08 or more and a volume resistivity of 10 ⁴ to 10 ⁹ Ωcm. Electrophotographic apparatus. 29. The electrophotographic apparatus according to claim 28, wherein the magnet body having a conductive portion to which the voltage is applied is a conductive sleeve containing the magnet body. 30. The standard deviation of minor axis length / major axis length of particles of 5 μm to 20 μm of the magnetic particle dispersion type composite particles for charging is 0.08 or more. 2. The electrophotographic apparatus according to claim 1. 31. The standard deviation of minor axis length / major axis length of the particles of 5 μm to 20 μm of the magnetic particle-dispersed composite particles for charging is 0.10 or more. 2. The electrophotographic apparatus according to claim 1. 32. The volume resistivity of particles of 5 to 20 μm of the magnetic particle-dispersed composite particles for charging is Ra, and the volume resistance of a portion of the composite particles exceeding 20 μm is Rb.
The electrophotographic apparatus according to any one of claims 28 to 31, wherein 0.5 < Ra / Rb < 33. The volume resistivity of the 5 μm to 20 μm portion of the charging magnetic particle-dispersed composite particles is Ra, and the volume resistivity of the composite particles exceeding 20 μm is Rb.
33. The electrophotographic apparatus according to claim 32, wherein 1.0 ≦ Ra / Rb ≦ 5.0. 34. The magnetic particle-dispersed composite particles for charging are produced by pulverizing magnetic particle-dispersed composite particles having a binder resin and magnetic particles dispersed in the binder resin. The electrophotographic apparatus according to any one of claims 28 to 33. 35. The magnetic particle-dispersed composite particles for charging have a coupling agent having a linear alkyl group having a carbon number of C ₆ or more on the surface thereof.
5. The electrophotographic apparatus according to any one of 4. 36. The electrophotographic apparatus according to claim 28, wherein the applied voltage is a DC voltage on which an oscillating voltage is superimposed. 37. The peak-to-peak voltage of the oscillating voltage is 100.
The electrophotographic apparatus according to any one of claims 28 to 36, wherein the voltage is 0 V or less. 38. The image carrier has a conductive substrate and a photosensitive layer, a layer farthest from the conductive substrate is a charge injection layer, and the charge injection layer has a volume resistivity of 1 × 10 ⁸ to
51. Any one of claims 38 to 50, wherein the density is 1 × 10 ¹⁵ Ωcm.
An electrophotographic apparatus according to the item. 39. The image bearing member, wherein a photosensitive layer is formed on a conductive cylindrical substrate, and the thickness of the conductive substrate is 0.5 mm or more and 3.0 mm or less. 39. The electrophotographic apparatus according to any one of -38. 40. The electronic device according to claim 28, wherein the electrophotographic apparatus does not have an independent cleaning mechanism, and collects a toner remaining on the photoreceptor after transfer by a developing process. Photo equipment. 41. At least two members selected from the group consisting of a charging unit, a developing unit, a cleaning unit, and a photoconductor having the magnetic particles for charging according to any one of claims 1 to 7.
A process cartridge, wherein at least one of the process cartridges is integrally supported and is detachably attached to an electrophotographic apparatus main body.