JPH09288403A - Electrophotographic electrifying device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrophotographic electrifying device in which good electrification characteristics can be maintained for a long time, good contamination resistance for an electrifying member is maintained, and injection of charges can be performed in a good state. SOLUTION: This electrophotographic electrifying device is equipped with an electrophotographic photoreceptor and an electrifying member disposed in contact with the photoreceptor. By applying voltage on the electrifying member, the electrophotographic photoreceptor is charged. The volume resistance of the photoreceptor is specified to >=1×10<8> Ωcm. The electrifying member has magnetic particles containing 0.001 to 5wt.% phosphorus component. The volume resistance of the magnetic particles is controlled to >=1×10<4> Ωcm and <=1×10<11> Ωcm.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has an electrophotographic photosensitive member and a member for contact-charging the electrophotographic photosensitive member, and an electron for charging the electrophotographic photosensitive member by applying a voltage to the contact charging member. Photographic charging device

[0002]

2. Description of the Related Art Conventionally, many methods are known as electrophotography, but the following method is generally used. That is, an electrostatic latent image is formed on a photoconductor by a charging unit and an image exposing unit, then the latent image is developed with toner to form a visible image (toner image), and the toner image is formed on a transfer material such as paper. After the transfer, the toner image is fixed on the transfer material by heat, pressure or the like to obtain a copy. At this time, toner particles remaining on the photoconductor without being transferred onto the transfer material are removed from the photoconductor by a cleaning process.

In recent years, various organic photoconductive materials have been developed as photoconductive materials for electrophotographic photoreceptors, and in particular, a function-separated type in which a charge generation layer and a charge transport layer are laminated has been put into practical use and a copying machine or printer. It is installed in a fax machine, etc. As a charging unit in such an electrophotographic apparatus, a unit using corona discharge has been used. However, since a large amount of ozone is generated, it is necessary to provide a filter. There were problems such as rising.

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 the photoconductor to form a narrow space in the vicinity of the contact portion, which is interpreted by the so-called Paschen's law. A charging method has been developed in which ozone generation is suppressed as much as possible by forming such a discharge.

Among them, a roller charging system using a charging roller as a charging member is particularly preferably used from the viewpoint of charging stability. Since the charging is performed by discharging from the charging member to the member to be charged, the charging is started by applying a voltage higher than a certain threshold voltage.

For example, when a charging roller is brought into contact with a photosensitive body containing an organic photoconductive substance having a photosensitive layer thickness of about 25 μm, a voltage of about 640 V or more is applied to the photosensitive body. The surface potential starts to rise, and thereafter the surface potential of the photoconductor linearly increases with a slope of 1 with respect to the applied voltage. Hereinafter, this threshold voltage is defined as charging start voltage Vth. That is, in order to obtain the photoreceptor surface potential Vd, the charging roller needs a direct current voltage of Vd + Vth, which is higher than the required DC voltage. Further, since the resistance value of the charging roller fluctuates due to environmental fluctuations, it is difficult to set the potential of the photoconductor to a desired value.

Therefore, in order to further uniform the charging, as disclosed in JP-A-63-149669, a peak-to-peak voltage of 2 × Vth or more is applied to a DC voltage corresponding to a desired Vd. A DC + AC charging system is used in which a voltage obtained by superimposing an AC voltage is applied to a charging roller. This is for the purpose of the potential leveling effect of the alternating current,
The potential of the member to be charged converges to Vd, which is the center of the AC voltage,
It was difficult to be affected by external disturbances, and it was confirmed that the charging property was improved.

However, even in such a charging method, since the essential charging mechanism uses the discharging phenomenon from the charging member to the photoconductor, the voltage required for charging is the photoconductor as described above. A value above the surface potential is required. Further, vibrations of the charging member and the photoconductor due to the electric field of the AC voltage, generation of noise (hereinafter referred to as AC charging sound), deterioration of the photoconductor surface due to discharge, and the like become remarkable, which is a new problem.

As a charging method with higher charging efficiency, so-called injection charging in which charges are directly injected into the photosensitive member is known.

This charging roller, charging fiber brush, electromagnetic belt
A charging device that applies a voltage to a contact charging member such as a gas brush
Used to inject charge into the trap level on the surface of the photoconductor
The injection charging method is described in Japan Hardcopy.
 1992 Proceedings P287, "Contact Using Conductive Rollers
There is a description in "Charging characteristics" etc.
Low-resistance charging member that applies voltage to a photosensitive member
Is a method of performing injection charging with a
Material that is very low and that makes the charging member conductive (conductive
Under the condition that it is exposed to the surface sufficiently.
I was Therefore, in the above-mentioned document,
As a result, the resistance value has dropped sufficiently in aluminum foil and high humidity environment.
On-conductive charging members are said to be preferred. The present invention
According to the study of the person, it may be possible to inject sufficient charge into the photoconductor.
The effective resistance of the charging member is 1 x 10 ^ThreeΩcm or less,
Above this, a difference between the applied voltage and the charging potential begins to occur.
It is known that there is a problem in the convergence of the electric potential.

However, when such a charging member having a low resistance value is actually used, an excessive leak current flows from the injection charging member to the scratches, pinholes, etc. formed on the surface of the photosensitive member, which may cause charging failure in the periphery. It is easy for the pinhole to expand and the charging member to be damaged by electricity.

In order to prevent this, it is necessary to set the resistance value of the charging member to about 1 × 10 ⁴ Ωcm or more. However, in the charging member having this resistance value, the charge injection into the photoconductor is as described above. There is a contradiction that the charge is lowered and charging is not performed.

Therefore, it is desirable to eliminate the above-mentioned problems in the contact type charging device or the image forming method using the charging device, that is, it is preferable to use the charge injection which does not occur unless the low resistance contact charging member is used. It is desirable to simultaneously achieve the antistatic property and the contradictory characteristic of pinhole leak on the charged body that could not be prevented by the low resistance contact charging member, and for that purpose adjust to the desired resistance value. In addition, it was found that this can be achieved by using magnetic particles that can contact more members as a charging member with the photoconductor.

[0014]

An object of the present invention is to provide an electrophotographic charging device which can perform good charging, and an object of the present invention is to provide an electrophotographic charging device which can perform good injection charging. To do.

[0015]

The present invention has an electrophotographic photosensitive member and a charging member disposed in contact with the electrophotographic photosensitive member, and applies the voltage to the charging member to form the electrophotographic photosensitive member. In an electrophotographic charging device for charging, the electrophotographic photosensitive member has a volume resistance value of 1 × 10 ⁸ Ωcm or more, and the charging member has magnetic particles containing 0.001 to 5% by weight of a phosphorus component. , The volume resistance value of the magnetic particles is 1
The electrophotographic charging device is characterized in that it is not less than × 10 ⁴ Ωcm and not more than 1 × 10 ¹¹ Ωcm.

[0016]

DETAILED DESCRIPTION OF THE INVENTION The charging member used in the present invention will now be described. The charging member used in the present invention has magnetic particles containing a phosphorus component, and the resistance value of the magnetic particles can be easily adjusted to a desired resistance by adjusting the amount of phosphorus, particularly by adding phosphorus. Can be easily controlled low.

The preferable amount of phosphorus contained in the magnetic particles is in the range of 0.001 to 5% by weight, more preferably 0.005 to 5% by weight, and further preferably 0.01 to 0. It is in the range of 2% by weight. If it is less than 0.001% by weight, there is almost no effect of lowering the resistance value, and if it exceeds 5% by weight, the magnetic force is lowered and carrier adhesion to the photoreceptor is increased, which is not preferable.

Resistance of Magnetic Particles of Charging Member in the Present Invention
The value is the resistance value between the voltage application part and the part in contact with the photoconductor.
lx10^Four Ω ~ l × 10¹¹It is preferably Ω. Often
Resistance value is 1 × 10^Four If less than Ω, pinhole leak easily occurs
1 x 10 ¹¹Good charging when exceeding Ω
It tends to be difficult to remove. Also, change the resistance value of the charging member
In order to control within the above range, the body of the charging member of the present invention
Product resistance is l × 10^FourΩcm ~ 1 x 10¹¹Ω cm
Is preferred.

When the charging device of the present invention is used for injection charging, the charging member plays a role of favorably injecting charges into the charge injection layer of the photosensitive member, and the charging current is caused by defects such as pinholes formed on the photosensitive member. It must also have a role of preventing the electrical breakdown of the charging member and the photoconductor caused by the concentration.

Therefore, regarding the resistance value of the magnetic particles of the charging member, the resistance value between the voltage application portion and the portion in contact with the photosensitive member is l × 1.
It is preferably 0 ⁴ Ω to 1 × 10 ⁹ Ω, and particularly 1
It is preferably from 10 ⁴ Ω to 1 × 10 ⁸ Ω. If the resistance value of the charging member is less than 1 × 10 ⁴ Ω, pinhole leakage tends to occur, and if it exceeds 1 × 10 ⁹ Ω, good charging tends to be difficult.

In order to control the resistance value of the charging member within the above range, the volume resistance value of the charging member of the present invention is 1 ×.
It is preferably 10 ⁴ Ωcm to 1 × 10 ⁹ Ωcm, and particularly preferably 1 × 10 ⁴ Ωcm to 1 × 10 ⁸ Ωcm.

When the photosensitive member is charged by discharging in a minute gap between the charging member and the photosensitive member instead of the charging method of directly injecting electric charge into the photosensitive member, the resistance value of the magnetic particles as the charging member is It is preferably 1 × 10 ⁵ Ωcm to 1 × 10 ¹¹ Ωcm, and the volume resistance value of the charging member is 1 × 10 ⁶
It is preferably Ωcm to 1 × 10 ¹¹ Ωcm.

The volume resistance value of the magnetic particles used for the charging member was measured using the electric resistance measuring device shown in FIG. That is, the cell A is filled with particles, and the electrode 1 and the electrode 2 are arranged so as to contact the filled particles. Here, the voltage is applied between the electrodes, and the current flowing at that time is measured to measure. The measurement conditions were 23 ° C. and 65% environment, and the contact area S of the packed particles with the cell was S = 2 cm ² , and the thickness d.
= 1 mm, upper electrode load 10 kg, applied voltage 100 V
It is.

In FIG. 1, 1 is a main electrode, 2 is an upper electrode, 3 is an insulator, 4 is an ammeter, 5 is a voltmeter, 6 is a constant voltage device, 7 is a magnetic particle, and 8 is a guide ring. Show.

Further, it is in contact with the photoreceptor having the charge injection layer.
Magnetic particles that are contact charging members that are charged by injection
Of the applied voltage applied to the contact charging member is V
Plunge into the nip between the photoconductor and the contact charging member (nip
On the photoconductor at the upstream side in the photoconductor moving direction when viewed from the part)
The potential VD, the voltage application portion of the contact charging member and the photosensitive member
If the electrophotographic charging device is such that the distance of
Contact the charging member of the contact charging member to the base of the rotating body of the conductor.
The volume resistance value in the dynamic resistance measuring method that is touched is (V
-VD) / d or V / d, whichever is higher, is V1
(V / cm), application of 20 to V1 (V / cm)
10 in the electric field range^Four Ωcm-10 ^TenΩcm range
It is preferable to be in the surrounding area.

The volume resistance value of the magnetic particles was measured by the dynamic resistance measuring method using an apparatus as shown in FIG. That is, 22 conductive aluminum substrates and 0.
Magnetic particles 27 are attached to 21 magnetic particle holding members having a gap 24 of 5 mm so that the nip 23 between the magnetic drum 27 and the aluminum drum will be 5 mm. The charging member and the photoconductor are rotated in the direction, a DC voltage is applied to the charging member, and the current flowing in the system is measured to obtain the resistance.
The volume resistance was calculated from the contact width between No. 4, the nip 23, and the magnetic particles and the aluminum drum. 26 is a constant voltage device.

The measurement environment was 23 ° C./65%.

The resistance value of the magnetic particles as the charging member generally varies depending on the applied electric field applied to the charging member, and the behavior is such that the resistance is low particularly in a high applied electric field and high in a low applied electric field. , The dependency of the applied electric field is recognized.

When charging is performed by injecting charges into the photoconductor, the surface to be charged of the photoconductor rushes into the nip portion between the photoconductor and the charging member (upstream side as viewed from the charging member).
In this case, the voltage difference between the charging potential of the photoconductor before the rush and the voltage applied to the charging member is large, and therefore the applied electric field applied to the charging member is high. However, as the photoconductor passes through the nip portion, charges are injected into the photoconductor, and the charging is gradually performed in the nip portion, so that the potential on the photoconductor gradually changes to the applied voltage applied to the charging member. , The difference between the applied voltage applied to the voltage application portion and the potential on the photoconductor is small, and the difference approaches 0 V.
Accordingly, the applied electric field applied to the charging member becomes smaller. That is, in the step of charging the photoconductor, the applied electric field applied to the charging member is different between the upstream side and the downstream side of the nip portion of the charging member, and the applied electric field applied to the charging member is high on the upstream side and low on the downstream side. .

Therefore, if a charge removing step such as pre-exposure is performed before the charging step, the potential on the photosensitive member when it enters the nip portion of the charging member is almost 0 V, so The applied electric field is almost determined by the applied voltage applied to the charging member, but if such a step of removing charges is not provided, the applied voltage and polarity of charging and transfer will
That is, it is determined by the potential on the photoconductor after transfer and the applied voltage applied to the charging member.

That is, when charging is performed by injecting charges onto the photosensitive member, the resistance value of the charging member is, for example, 0.3 × the applied electric field at an applied voltage of 30% of the applied voltage applied to the charging member. 10 in the range of V / d (V / cm) or less
^If the resistance is ¹⁰ Ωcm or more, the charging due to the injection at the downstream side of the nip portion of the charging member is significantly reduced, and the charging up to 70% of the applied voltage is good, but the remaining 30% is the charge. Injectability deteriorates, and it becomes difficult to inject charges onto the photoconductor, so that a desired potential cannot be charged, resulting in poor charging. That is, the resistance value when a lower electric field is applied has a great influence on the property of injecting charges into the photoconductor.

Therefore, the volume resistance value of the contact charging member in the dynamic resistance measuring method in which the charging member is brought into contact with the base of the rotating body of the conductor is either (V-VD) / d or V / d. 20-V when the higher electric field is V1 (V / cm)
10 ⁴ Ωc in the applied electric field range of 1 (V / cm)
It is preferably in the range of m to ^{10 10} Ωcm, and 0.2 × V from the viewpoint that a good image can be formed when the potential on the photoreceptor is up to about 80% of the applied voltage.
When the electric field of / d is V3 (V / cm), V3 to V1
10 ⁴ Ωcm in the applied electric field range of (V / cm)
It is preferably in the range of 10 to 10 ¹⁰ Ωcm.

On the other hand, when the applied electric field at the applied voltage applied to the charging member is 10 ⁴ Ωcm or less, excessive leakage current flows from the contact charging member to scratches, pinholes, etc. generated on the surface of the photosensitive member. In addition, defective charging around, enlargement of pinholes, and electrical breakdown of the charging member may occur.
Since the conductive layer (metal substrate) of the photoconductor is exposed on the surface of the photoconductor, the potential on the photoconductor is 0 V, and therefore the maximum applied electric field applied to the charging member is not applied to the charging member. It is determined by the applied voltage applied.

Therefore, in order to charge the photoconductor, the maximum electric field applied to the charging member, that is, the voltage determined by the voltage difference between the photoconductor potential on the upstream side of the nip portion of the charging member and the applied voltage applied to the charging member. The higher of the applied electric field V1 (V / V) which is determined by the applied voltage applied to the charging member when there is a pinhole due to a scratch or the like on the photoconductor
cm), the resistance value is preferably 10 ⁴ Ωcm to ^{10 10} Ωcm in the applied electric field range of 20 to V1 (V / cm).

Further, the wider the nip width between the charging member and the photosensitive member, the larger the contact area between the charging member and the photosensitive member and the longer the contact time. That is, the charging is performed well. However, in order to obtain a sufficient charge injection property even when the nip width is narrowed, the resistance value of the charging member is R1 when the resistance value is the maximum R1 and the minimum R2 by the applied electric field within the range of the applied electric field.
It is preferably within the range of / R2 ≦ 1000. In the process where charging is performed in the nip, the resistance changes abruptly, so that the charge may not be injected into the photoconductor and the charge may pass through the nip portion, which may result in insufficient charging. Is.

In the magnetic particles of the present invention, a magnetic medium resistance material is magnetically erected, and the magnetic brush is brought into contact with the photoreceptor to be charged.

Therefore, as the magnetic particles contained in the charging member, an alloy or compound containing an element exhibiting ferromagnetism such as iron, cobalt and nickel is used. Preferably, ferrite particles whose volume resistance value is adjusted to a preferable range by performing oxidation treatment, reduction treatment, composition adjustment and the like are used.

The particle diameter of the magnetic particles is 2.2 μm in volume distribution diameter.
In the above magnetic particles, the volume distribution 50% diameter is 10 μm
And 100 μm or less, and the ratio of the volume distribution 50% diameter to the volume distribution 5% diameter (hereinafter referred to as the particle size ratio) is 1.40.
The volume distribution is preferably 5 or more, more preferably 5
0% diameter is 10 μm or more and 60 μm or less, particle diameter ratio is 1.55
It is above 5.00.

In the contact charging, improving the contact property with the photosensitive member is an important factor for enhancing the charging ability, and it is effective to use the magnetic particles having the above particle size and particle size ratio as a means for achieving the effect. .

That is, in the case of magnetic particles having the above particle size distribution, magnetic particles having a particle size smaller than the 50% volume distribution are:
As the auxiliary particles, they can move between the magnetic particles to be attached (restrained by magnetic force), so that the following effects can be obtained.

1) The contact surface between the magnetic particles and the photoconductor is brought into closer contact.

2) The magnetic particles are closely packed to make the resistance in the magnetic brush uniform.

Here, if the particle size ratio is less than 1.40, the effect as auxiliary particles decreases, and charging failure may occur under low temperature and low humidity conditions. On the small particle size side of the volume distribution, magnetic particles having a volume distribution diameter of less than 2.2 μm may adhere to the photoconductor, and in such a case, it may cause abrasion of the photoconductor.

Here, the volume distribution diameter of the magnetic particles is measured by a laser diffraction type particle size distribution measuring device HEROS (JEOL Ltd.).
Manufactured), and a range of 0.05 μm to 200 μm is set to 32.
The measurement was performed by logarithmic division.

By the way, the above-mentioned magnetic particles are generally used in a form of being held by a metal tube or a metal foil having an arbitrary surface roughness which contains a permanent magnet such as a magnet for restraining the magnetic particles.

The charging member thus manufactured is used in a state in which the charging nip is formed by using a pressing means such as a spring and the pressing member is pressed into contact with the photosensitive member.

The gap between the holding member holding the magnetic particles and the photosensitive member is preferably in the range of 0.2 to 2 mm. If the diameter is less than 0.2 mm, it becomes difficult for the magnetic particles to pass through the gap, and the magnetic particles are not smoothly transported on the holding member, resulting in poor charging or excessive accumulation of magnetic particles in the nip portion, resulting in adhesion to the photoconductor. If it is 2 mm or more, it is difficult to form a wide nip width between the photoconductor and the magnetic particles, which is not preferable. It is more preferably 0.2 to 1 mm, and particularly preferably 0.3 to 0.7 mm.

In the present invention, it is preferable to provide a surface layer on the surface of the magnetic particles from the viewpoint of suppressing the contamination of the magnetic particles as the charging member by image formation.

The form of the magnetic particles having a surface layer is such that the surface of the magnetic particles is coated with a vapor deposition film, a conductive resin film, a conductive pigment-dispersed resin film or the like. This surface layer does not necessarily have to completely cover the magnetic particles, and the magnetic particles may be exposed within a range in which the effect of the present invention can be obtained.
That is, the surface layer may be formed discontinuously.

From the viewpoint of productivity, cost, etc., it is preferable to coat the conductive pigment-dispersed resin film.

As a matter of course, the resistance of the magnetic particles after coating must be within the above range.

When a surface layer made of resin alone is provided on the surface of the magnetic particles, the resin generally has a high resistance, so the resistance of the magnetic particles increases, and depending on the coating amount, it is compared with the case where the surface layer is not provided. The charging characteristics tend to deteriorate.

Therefore, in this case, a surface layer in which conductive particles are dispersed to control the resistance is used as the surface layer.

Further, controlling the resistance of the magnetic particles only by the surface layer makes the resistance range abruptly decreased on the high electric field side, and the permissible range of the leak image generation due to the size and depth of the scratch on the photoconductor is widened. It is not preferable from the viewpoint of the above, and it is preferable that the resistance of the magnetic particles of the matrix is also within the above range.

Therefore, the resistance of the surface layer needs to be about the same as the resistance of the core material.

The binder resin used for coating the magnetic particles includes styrenes such as styrene and chlorostyrene; monoolefins such as ethylene, propylene, butylene and isobutylene; vinyl acetate, vinyl propionate, vinyl benzoate and butyric acid. Vinyl esters such as vinyl; methyl acrylate, ethyl acrylate, butyl acrylate, dodecyl acrylate, octyl acrylate, phenyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, α-methylene such as dodecyl methacrylate. Aliphatic monocarboxylic acid ester vinyl methyl ether,
Vinyl ethers such as vinyl ethyl ether and vinyl butyl ether; homopolymers or copolymers of vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone and vinyl isopropenyl ketone, and the like. From the viewpoints of dispersibility of the organic fine particles, film-forming property as a coat layer and productivity, polystyrene, styrene-alkyl acrylate copolymer, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride Examples thereof include acid copolymers, polyethylene and polypropylene. Further, polycarbonate, phenol resin, polyester, polyurethane, epoxy resin, polyolefin, fluororesin, silicone resin, polyamide and the like can be mentioned.

In particular, from the viewpoint of preventing toner contamination, it is more desirable to contain a resin having a small critical surface tension, such as polyolefin, fluororesin, or silicone resin. Further, from the viewpoint of maintaining a wide allowable range for preventing a leak image due to a decrease in resistance on the high electric field side and a scratch on the photoconductor, the resin coated on the magnetic particles is preferably a silicone resin having high voltage resistance.

Examples of the fluororesin include polyvinyl fluoride, polyvinylidene fluoride, polytrifluoroethylene, polychlorotrifluoroethylene, polydichlorodifluoroethylene, polytetrafluoroethylene, polyhexafluoropropylene, and other monomers. Examples include polymerized solvent-soluble copolymers.

As the silicone resin, for example, KR271, KR282, KR31 manufactured by Shin-Etsu Silicone Co., Ltd.
1, KR255, KR155 (straight silicone varnish), KR211, KR212, KR216, KR2
13, KR217, KR9218 (silicone varnish for modification), SA-4, KR206, KR5206 (silicone alkyd varnish), ES1001, ES1001
N, ES1002T, ES1004 (silicone epoxy varnish), KR9706 (silicone acrylic varnish), KR5203, KR5221 (silicone polyester varnish) and SR2100 manufactured by Toray Silicone Co., Ltd.
SR2101, SR2107, SR2110, SR21
08, SR2109, SR2400, SR2410, S
R2411, SH805, SH806A, SH840 and the like are used.

However, when a surface layer in which conductive particles are dispersed and whose resistance is controlled is used, although the charging characteristics are improved,
In many cases, the adhesion to the core material and the film strength will decrease.
In the case of magnetic particles whose surface is coated with resin, resin wear,
Peeling and spent are problems, and in a charging device using magnetic particles, charging is non-uniform during long-term durability, which is a cause of image deterioration. Further, as a result of resistance fluctuation due to detachment of the conductive particles, a change in charging characteristics is likely to occur, which is a problem in long-term use.

Therefore, in the present invention, it is preferable to coat the surface of the magnetic particles with a resin having a specific molecular weight distribution.

Specifically, the main peak on the high molecular weight side improves the abrasion resistance of the resin and prevents the spent of the surface due to toner or the like. Further, the sub-peak or shoulder on the low molecular weight side has the effect of improving the adhesion between the magnetic particle core and the resin and preventing the coating resin from peeling off from the magnetic particles. Due to these synergistic effects, even in the case of the magnetic particles of the charging member, which tends to have a large share, the magnetic particles are less deteriorated, and uniform charging is obtained even by long-term durability, and a good image is easily obtained.

In the present invention, the molecular weight of the main peak of the GPC chromatogram of the magnetic particles is 10,000 or more, preferably 30,000 to 400,000, and at least one peak or shoulder on the low molecular weight side is 3,000 to 3.
It is preferably between 0000, and the weight average molecular weight Mw is 50,000 to 700,000, and the number average molecular weight M is
n is in the range of 5,000 to 50,000, Mw / Mn is 10 or more, and further, the Z-average molecular weight Mz is 10.
It is preferably in the range of 00000 to 5000000.

If the molecular weight of the main peak is less than 10,000, the effect on wear resistance is not sufficient. If the peak or shoulder on the low molecular weight side is less than 3,000, the effect on abrasion resistance is not sufficient, and if it exceeds 30,000, the resin tends to peel off from the magnetic particle surface.

Similarly, when the number average molecular weight Mn, the weight average molecular weight Mw, the Z average molecular weight Mz, and Mw / Mn are in the above ranges, it is effective for the abrasion resistance of the resin, the prevention of peeling, and the prevention of the spent of toners. is there.

Preferably, the main peak has a molecular weight of 50.
000 to 300,000, the peak or shoulder on the low molecular weight side is 3000 to 15,000, the weight average molecular weight Mw is 100,000 to 500,000, and the number average molecular weight Mn is 70.
It is preferable that 00-400000 and Mw / Mn are 20 or more.

Further, the ratio of the molecular weight P1 of the main peak to the molecular weight P2 of the peak or shoulder on the low molecular weight side is 3: 1 to 100: 1 so that the adhesion of the resin to the magnetic particles and the abrasion resistance can be improved. It is preferable from the viewpoint of compatibility. Particularly preferably, it is in the range of 5: 1 to 50: 1.

Here, the molecular weight of the resin on the surface of the magnetic particles was measured as follows.

The apparatus is a gel permeation chromatography (GPC) measuring apparatus manufactured by Waters, GPC-
Using 150C, it measured on the following conditions.

Column: Shodex HT-806M
Two (pre-column Shodex HT-800P 1
Main) temperature: polyethylene resin 145 ° C., other resin 40 ° C. solvent: polyethylene resin o-dichlorobenzene (0.1% ionol added), other resin tetrahydrofuran flow rate: 1.0 ml / min sample: 0. Inject 0.4 ml of 15% sample

As a measurement sample, Soxhlet extraction of magnetic particles was carried out for 20 hours using a xylene solvent, xylene was removed from the extract by an evaporator, etc. and dried, and the obtained solid content was used as a sample.

The molecular weight of the sample was calculated by using a molecular weight calibration curve prepared from a monodisperse polystyrene standard sample.

As a method for determining the position of the peak / shoulder, the inflection point of the differential curve of the GPC chromatogram was used as the position of the peak / shoulder.

The conductive fine particles according to the present invention include metals such as copper, nickel, iron, aluminum, gold and silver or metal oxides such as iron oxide, ferrite, zinc oxide, tin oxide, antimony oxide and titanium oxide. Further, there may be mentioned electrically conductive powder such as carbon black, and further examples of the ion conductive agent include lithium perchlorate, quaternary ammonium salt and the like.

As a method for producing resin-coated magnetic particles containing conductive fine particles according to the present invention, the particles to be coated are immersed in a coating layer solution prepared by dissolving the conductive fine particles and the coating resin in an appropriate solvent. Then, the solvent is volatilized using a spray dryer to form the coating layer, or particles of the material to be coated are put into a general fluidized bed coating device to form a fluidized bed while spraying the coating layer solution and drying. And a method of gradually forming a coat layer.

Further, for example, in the case of an electrophotographic apparatus using the reversal development, by aligning the charge amount of the toner with the polarity of the photoconductor, the toner mixed in the charging device is developed on the photoconductor to discharge the toner. It will be possible. Therefore, it is considered that the spent resistance is improved as compared with the case where the coating is not applied.

When discharge is used for charging,
Contamination of magnetic particles tends to be exacerbated by the generation of ozone, damage by discharge energy, and the like. On the other hand, when the injection charging is used, injection charging is preferable because a large voltage is not required for charging like discharge.

In the present invention, the amount of the coating layer based on the core material is preferably 0.1 to 20% by weight of the coating layer solid content. If it is less than 0.1% by weight, the covering effect is not sufficient, and 2
If it exceeds 0% by weight, the chargeability is not improved even when the conductive particles are dispersed, rather the adhesion to the core material is deteriorated and the film is peeled off or the conductive particles are detached. It is not preferable because the effect is insufficient because it is easy.

When the charging device of the present invention is used for injection charging, the photoreceptor used in the present invention has a charge injection layer as a layer farthest from the support, that is, a surface layer. The charge injection layer has a volume resistance value of 1 × 10 in order to obtain sufficient chargeability and to prevent image deletion from occurring.
It is preferably from ⁸ to 1 × 10 ¹⁵ Ωcm, and particularly from the viewpoint of image deletion, the volume resistance value is from 1 × 10 ¹⁰ to 1 × 10 ¹⁴ Ω.
cm × 1 × 1 considering the environmental change of volume resistance
It is preferably 0 ¹² to 1 × 10 ¹⁴ Ωcm.

When the volume resistance value is less than 1 × 10 ⁸ Ωcm, the image charge tends to occur because charged charges are not retained in the surface direction in a high humidity environment. On the other hand, if it exceeds 1 × 10 ¹⁵ Ωcm, the charged electric charge from the charging member cannot be sufficiently injected and held, and charging failure tends to occur.

Here, the method for measuring the volume resistance value of the charge injection layer in the present invention is to prepare a surface layer on a polyethylene terephthalate (PET) film having gold vapor-deposited on the surface thereof and use this for measuring the volume resistance (Hewlett Packard). Manufactured by 4140B pA MATER) at 23 ° C., 65
The measurement is performed by applying a voltage of 100 V in an environment of 100%.

By providing such a functional layer on the surface of the photoconductor, it plays a role of holding the charged electric charge injected from the charging member, and further plays a role of releasing the electric charge to the photoconductor support during light exposure. Reduce the residual potential.

Further, by using the charging device of the present invention and the above-mentioned photosensitive member, the charging start voltage Vth is small and the charging potential of the photosensitive member can be charged to almost 90% or more of the voltage applied to the charging member. became.

For example, the charging device of the present invention has an absolute value of 10
When a direct current voltage of 0 to 2000 V is applied at a process speed of 1000 mm / min or less, the charging potential of the electrophotographic photosensitive member having a charge injection layer of the present invention is 80% of the applied voltage.
%, Or even 90% or more. On the other hand, the charging potential of the photoconductor obtained by charging using conventional discharge is almost 0 V when the applied voltage is 640 V or less, and when the applied voltage is 640 V or more, only a charging potential of a value obtained by subtracting 640 V from the applied voltage can be obtained. It was

This charge injection layer is composed of an inorganic layer such as a metal vapor deposition film or a conductive powder-dispersed resin layer in which conductive fine particles are dispersed in a binder resin. The vapor deposition film is vapor-deposited and the conductive powder-dispersed resin film is It is formed by applying an appropriate coating method such as a dipping coating method, a spray coating method, a roll coating method and a beam coating method. Further, it may be constituted by mixing or copolymerizing an insulating binder resin with a resin having a high light-transmitting ion conductivity, or a resin having a medium resistance and a photoconductivity alone.

In the case of the conductive fine particle dispersed film, the amount of the conductive fine particles added is 2 to 250 parts by weight, more preferably 2 to 190 parts by weight, based on 100 parts by weight of the binder resin. When the amount is less than 2 parts by weight, it is difficult to obtain a desired volume resistance value, and when the amount is more than 250 parts by weight, the film strength is lowered and the charge injection layer is easily scraped off, and the life of the photoreceptor is shortened. Become. Further, the resistance becomes low, and the image defect due to the flow of the latent image potential is likely to occur.

The binder resin of the charge injection layer may be the same as the binder resin of the lower layer, but in this case, the coating surface of the charge transport layer is disturbed when the charge injection layer is coated. Therefore, the coating method needs to be particularly selected because it may occur.

In the present invention, the charge injection layer preferably contains lubricant particles in order to improve the durability of the photoreceptor. In particular, it is more preferable to use a fluorine resin, a silicone resin, or a polyolefin resin having a low critical surface tension as the lubricant particles. More preferably, tetrafluoroethylene resin (PTFE) is used. In this case, the amount of lubricant particles added is preferably 2 to 50 parts by weight, and more preferably 5 to 40 parts by weight, based on 100 parts by weight of the binder resin. If the amount is less than 2 parts by weight, the improvement of the durability tends to be insufficient, and if the amount is more than 50 parts by weight, the resolution of the image and the sensitivity of the photoreceptor tend to decrease.

The thickness of the charge injection layer in the present invention is preferably 0.1 to 10 μm, and particularly preferably 1 to 7.
μm is preferred.

The constitution, material, manufacturing method and the like of the members used in the present invention will be exemplified below. [Toner Production Example] Polyester resin 100 parts (parts by weight, the same applies hereinafter) Carbon black 3 parts by weight Chromium compound of di-tert-butylsalicylic acid 4 parts by weight The above materials are sufficiently premixed by a Henschel mixer, and biaxial extrusion kneading is performed. The mixture was melt-kneaded by a machine, cooled, coarsely pulverized to about 1 mm by using a hammer mill, and then finely pulverized by a fine pulverizer by an air jet system. Further, the obtained finely pulverized product was subjected to air classification to obtain a black powder having a weight average particle size of 10 μm.

100 parts of the above black powder and 1.5 parts of silica fine powder (average particle size: 0.05 μm) whose surface was hydrophobized were mixed with a Henschel mixer to obtain a toner.

[Photoreceptor Production Example 1] The photoreceptor is a photoreceptor using an organic photoconductive substance for negative charging, and five functional layers are provided on a cylinder made of aluminum having a diameter of 30 mm.

The first layer is a conductive layer, and is a conductive particle-dispersed resin layer having a thickness of about 20 μm, which is provided to smooth defects such as aluminum cylinders and to prevent moire due to reflection of laser exposure. Is.

The second layer is a positive charge injection preventing layer (undercoat layer), which plays a role of preventing the positive charges injected from the aluminum support from canceling out the negative charges charged on the surface of the photosensitive member. It is a medium resistance layer having a thickness of about 1 μm, the resistance of which is adjusted to about 10 ⁶ Ωcm by using -66-610-12 nylon resin and methoxymethylated nylon.

The third layer is a charge generation layer, which is a layer having a thickness of about 0.3 μm in which a disazo pigment is dispersed in a resin, and generates positive and negative charge pairs by being exposed to laser.

The fourth layer is a charge transport layer, which is a layer having a thickness of about 25 μm in which hydrazone is dispersed in 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.

The fifth layer is a charge injection layer, which is a feature of the present invention, and is made by dispersing SnO ₂ ultrafine particles and tetrafluoroethylene resin particles having a particle size of about 0.25 μm in a photocurable acrylic resin. is there. Specifically, 167 parts of SnO ₂ particles having a particle size of about 0.03 μm, which has been doped with antimony and has a low resistance, per 100 parts of resin, further 20 parts of tetrafluoroethylene resin particles, and 1.2 parts of a dispersant. It is dispersed. The coating solution prepared in this manner was applied by spray coating to a thickness of about 2.5 μm to form a charge injection layer.

As a result, the volume resistance of the photoconductor surface layer was 1 × 10 ¹⁵ Ωcm in the case of the charge transport layer alone, whereas the resistance of the photoconductor surface was lowered to 5 × 10 ¹² Ωcm.

[Photoreceptor Production Example 2]
A photoconductor was prepared in the same manner as in Photoconductor Production Example 1 except that no layer was provided.

As a result, the volume resistance value of the surface layer of the photoconductor was 1 × 10 ¹⁵ Ωcm.

[Photoreceptor Manufacturing Example 3] Fifth of Photoreceptor Manufacturing Example 1
Photoreceptor except that a layer was prepared by adding 300 parts by weight of SnO ₂ particles having a particle diameter of about 0.03 μm, which was doped with antimony and reduced in resistance, to 100 parts by weight of a photocurable acrylic resin. A photoconductor was prepared in the same manner as in Production Example 1.

As a result, the volume resistance of the surface layer of the photoconductor was lowered to 2 × 10 ⁷ Ωcm.

[Photoreceptor Manufacturing Example 4] A blocking layer, a photoconductive layer and a surface layer were sequentially formed on a mirror-finished aluminum cylinder by the glow discharge method.

First, the reaction chamber was set to about 7.5 × 10 ⁻³ Pa, and then the aluminum cylinder was kept at 250 ° C. while SiH
₄ , B ₂ H ₆ , NO, and H ₂ gas were fed into the reaction chamber, while the gas was allowed to flow out from the reaction chamber, and an internal pressure of about 30 Pa was applied to cause glow discharge to form a 5 μm blocking layer.

Then, using a method similar to that for forming the blocking layer, SiH ₄ and H ₂ gases were used to adjust the internal pressure to 50 Pa, and then a photoconductive layer having a thickness of 20 μm was formed.
_A surface layer made of Si and C having a film thickness of 0.5 μm was formed by glow discharge under a pressure of 55 Pa using ₄ , CH ₄ and H ₂ gas to prepare an amorphous silicon photoreceptor.

[Charging Member Manufacturing Example 1] Fe ₂ O ₃ , Cu
The metal oxides of O and Zn0 have a molar ratio of 2.3:
Weigh and mix so as to be 1: 1 and further add phosphorus to the total weight of 0.
042% by weight, and to the resulting mixed powder was added an aqueous solution of PVA (polyvinyl alcohol) as a binder resin (0.5 to 5.0% by weight of PVA) to form a slurry, Granulated with a spray dryer.
The obtained granulated powder was fired in the air at 1100 to 1300 ° C. and crushed, and then magnetic particles having a desired particle size were obtained by classification.

The above magnetic particles were measured with a laser diffraction particle size distribution measuring device HEROS (manufactured by JEOL Ltd.). The 50% diameter was 32.3 μm, and the ratio of 50% diameter to 5% diameter was 1.66. there were.

[Manufacturing Example 2 of Charging Member] The same as Manufacturing Example 1 except that the phosphorus added was phosphorus oxide and the amount of phosphorus contained in the total weight of the magnetic particles was 0.035% by weight. It was made by the method.

The above magnetic particles were measured using a laser diffraction particle size distribution analyzer HEROS (manufactured by JEOL Ltd.). The 50% diameter was 24.7 μm, and the ratio of the 50% diameter to the 5% diameter was 1.58. Met.

[Manufacturing Example 3 of Charging Member] In Manufacturing Example 1, the molar ratio of the metal oxides Fe ₂ O ₃ , CuO and Zn0 was set to 2.
Weigh and mix so that the ratio is 4: 1: 1, and phosphorus is added in an amount of 0.
Magnetic particles were produced in the same manner as in Production Example 1 except that the amount was 003% by weight. The particle size distribution was measured using a laser diffraction particle size distribution analyzer HEROS (manufactured by JEOL Ltd.), and the 50% diameter was 45 μm, and the ratio of the 50% diameter to the 5% diameter was 1.61.

[Charging Member Manufacturing Example 4] In Manufacturing Example 1, the molar ratio of the metal oxides Fe ₂ O ₃ , CuO and Zn0 was set to 3.
Magnetic particles were produced in the same manner as in Production Example 1 except that the weight was mixed to be 5: 1: 0.5 and phosphorus was added so as to be 0.95 wt% of the total weight.

The above magnetic particles were measured with a laser diffraction type particle size distribution measuring device HEROS (manufactured by JEOL Ltd.). The 50% diameter was 42 μm, and the ratio of the 50% diameter to the 5% diameter was 1.59. It was

[Charging Member Production Example 5] The ferrite particles obtained in Magnetic Particle Production Example 1 were used as the magnetic particle core material, and the surface coating material was a polyperfluoroalkylmethacrylate-polymethylmethacrylate copolymer having a peak molecular weight of 28,000. And 5 parts each of a methyl methacrylate-butyl acrylate copolymer having a peak molecular weight of 28,000 were added and mixed in 10 parts of a toluene-methyl ethyl ketone (1: 1) mixed solvent, and conductive carbon black was dispersed in the resin solution. A conductive resin solution with adjusted resistance was prepared. Mn = 800 for the entire mixed resin
0, Mw = 45000 and Mw / Mn = 5.6.
This coating solution was applied to the magnetic particle particles so that the resin coating amount was 1 part with respect to the magnetic particle, to prepare a desired carbon-containing fluororesin-coated magnetic particle charging member.

The above magnetic particles were measured using a laser diffraction particle size distribution analyzer HEROS (manufactured by JEOL Ltd.). The 50% diameter was 33.4 μm, and the ratio of the 50% diameter to the 5% diameter was 1.58. Met.

[Charging Member Production Example 6] The ferrite particles obtained in Magnetic Particle Production Example 1 were used as the magnetic particle core material, and the surface coating material was a polyperfluoroalkylmethacrylate-polymethylmethacrylate copolymer having a peak molecular weight of 28,000. And 5 parts each of a methyl methacrylate-butyl acrylate copolymer having a peak molecular weight of 3800 and a toluene-methyl ethyl ketone (1: 1) mixed solvent 1
A conductive resin solution was prepared by adding and mixing in 100 parts and further dispersing conductive carbon black in the resin solution to adjust the resistance. Mn = 400 for the entire mixed resin
0, Mw = 42000, and Mw / Mn = 10.5. Using these raw materials, a charging member for carbon-containing fluororesin-coated magnetic particles obtained by the same method as in Magnetic Particle Production Example 5 was produced.

The above magnetic particles were measured using a laser diffraction type particle size distribution measuring device HEROS (manufactured by JEOL Ltd.). The 50% diameter was 33.1 μm, and the ratio of the 50% diameter to the 5% diameter was 1.58. Met.

[Charging Member Production Example 7] The ferrite particles obtained in Magnetic Particle Production Example 1 were used as the magnetic particle core material, and 0.1 part of a polyethylene resin having a peak molecular weight of 4000 and polyethylene having a peak molecular weight of 100000 were used as the surface coating material. A conductive resin solution having a resistance adjusted by dispersing 20 parts of conductive carbon in 0.9 part of the resin was used. Mn = 13000, Mw = 3700000, Mw /
Mn was 28.5. Using these raw materials, carbon-containing polyethylene resin-coated magnetic particles obtained by the same method as in Magnetic Particle Production Example 5 were produced as a charging member.

The above magnetic particles were measured with a laser diffraction particle size distribution analyzer HEROS (manufactured by JEOL Ltd.). The 50% diameter was 33.8 μm, and the ratio of the 50% diameter to the 5% diameter was 1.59. Met.

[Charging Member Production Example 8] The ferrite particles obtained in Magnetic Particle Production Example 1 were used as magnetic particles, and the surface coating resin had a peak molecular weight of 50,000 and Mn = 90.
A polyethylene resin-coated magnetic particle obtained by the same method as in Magnetic Particle Production Example 7 was prepared as a charging member, except that a polyethylene resin of 00, Mw = 14,000, and Mw / Mn = 15.6 was used.

The above magnetic particles were measured using a laser diffraction particle size distribution measuring device HEROS (manufactured by JEOL Ltd.). The 50% diameter was 33.2 μm, and the ratio of the 50% diameter to the 5% diameter was 1.58. Met.

[Charging Member Production Example 9] The ferrite particles obtained in Magnetic Particle Production Example 2 were used as magnetic particles, and conductive carbon black was dispersed in a water-based mixed solvent of toluene-methyl ethyl ketone-butanol as a surface coating resin. Using a silicone resin coating solution whose resistance is adjusted by
This coating solution was applied to the above magnetic particles so that the resin coating amount was 1 part with respect to the magnetic particles to prepare desired carbon-containing silicone resin coated magnetic particles.

The above magnetic particles were measured using a laser diffraction particle size distribution measuring device HEROS (made by JEOL Ltd.). The 50% diameter was 30.8 μm, and the ratio of the 50% diameter to the 5% diameter was 1.59. Met.

[Charging Member Production Example 10] Magnetic particles, which are magnetite (FeO.Fe ₂ O ₃ ) particles, were prepared as magnetic particles.

The above magnetic particles were measured using a laser diffraction particle size distribution analyzer HEROS (manufactured by JEOL Ltd.). The 50% diameter was 20 μm, and the ratio of the 50% diameter to the 5% diameter was 1.81. .

[Manufacturing Example 11 of Charging Member] A charging member was manufactured in the same manner as in Manufacturing Example 1 except that the amount of phosphorus added was 6.0 wt% in the total weight of the magnetic particles. .

The above magnetic particles were measured using a laser diffraction particle size distribution measuring device HEROS (manufactured by JEOL Ltd.). The 50% diameter was 35.3 μm, and the ratio of the 50% diameter to the 5% diameter was 1.70. Met.

[0127]

【Example】

(Embodiment 1) The principle of charging using the photoconductor and the contact charging member will be described.

In the present invention, a medium-resistance contact charging member is used to inject charges to the surface of the photoconductor having a medium resistance surface resistance. In this embodiment, charges are applied to the trap level of the surface material of the photoconductor. Is not injected, but the conductive particles in the charge injection layer are charged with electric charges for charging.

Specifically, it is based on the theory that a contact charging member charges a minute capacitor having a charge transport layer as a dielectric and an aluminum substrate and conductive particles in the charge injection layer as both electrode plates. At this time, the conductive particles are electrically independent of each other and form a kind of minute float electrode. For this reason, the surface of the photoconductor appears to be charged and charged to a uniform potential on a macroscopic scale, but in reality, innumerable minute charged conductive particles cover the photoconductor surface. Has become. Therefore, even if image exposure is performed with a laser, each particle is electrically independent and can hold an electrostatic latent image.

Next, the electrophotographic printer used in this embodiment will be described with reference to FIG. The process speed was 98 mm / sec, and the photoconductor 10 used was the photoconductor produced in Photoconductor Production Example 1.

The contact charging member 11 is composed of a non-magnetic conductive sleeve made of non-magnetic aluminum, the surface of which is blasted as a magnetic brush, and a magnet roll contained therein, which holds the magnetic particles. The gap between the sleeve and the photosensitive member was about 500 μm, and the magnetic particles obtained in Production Example 1 of the charging member as the charging member were coated on the sleeve so as to form a charging nip with a width of about 5 mm between the sleeve and the photosensitive member. . The magnet roll was fixed, and the surface of the sleeve was rotated in the opposite direction at a speed 1 times the peripheral speed of the surface of the photoconductor so that the photoconductor and the magnetic brush were in uniform contact.

When the peripheral speed difference is not provided between the magnetic brush and the photoconductor, the magnetic brush itself does not have a physical restoring force, and therefore the magnetic brush is pushed away by the deflection or eccentricity of the photoconductor. In such a case, the nip of the magnetic brush cannot be secured easily and charging failure may occur. For this reason, it is preferable to always contact the surface of a new magnetic brush. Therefore, in the present embodiment, charging was performed using a charging device that was rotated in the opposite direction at twice the speed.

Next, the exposure section receives image exposure. This scans a laser beam 12 from a laser diode whose intensity is modulated in accordance with an image signal with a polygon mirror to irradiate the photoconductor with the laser beam to form an electrostatic latent image.

Next, two-component development is carried out using the toner of the above manufacturing example.

The developer has a mean particle size of 35 μm and is composed of a Cu—Zn ferrite carrier whose surface is coated with a silicone resin and a toner of the toner production example.
The toner and the carrier were mixed at a weight ratio of 5: 100.

A non-magnetic stainless steel blade is attached on the toner carrier 13 containing a magnet with a gap of 500 μm for controlling the developer coating layer, and the developer is coated on the blade to regulate the coating thickness. did.

In this state, a voltage having a frequency of 2000 Hz and an AC voltage having a peak-to-peak voltage of 2.0 KV superposed on a DC voltage of -550 V was applied to cause a two-component phenomenon between the toner carrier and the photoconductor. The rotation speed of the stainless steel sleeve, which is the toner carrier, was set to 200% of that of the photoconductor in the same direction in the portion facing the photoconductor.

The image visualized with the toner in this manner is then transferred to the transfer material 14. A medium resistance transfer roller 15 is used as the transfer means. In this embodiment, a roller resistance value of 5 × 10 ⁸ Ω is used, and DC of + 2500V is used.
Transfer was performed by applying a voltage.

The print image on which the toner image has been transferred onto the transfer material is then fixed by the heat fixing roller 17,
Emitted outside the machine. Further, the toner that has not been transferred is scraped off from the surface of the photoconductor by the cleaning blade 16 and prepared for the next image formation.

The surface potential, leak, and flow image of the photoconductor were evaluated by the printer having the above-mentioned structure under the environment of 23 ° C./65% according to the following evaluation items. Table 2 shows the results.

Evaluation 1) The resistance value of the magnetic particles was measured at a voltage of 100 V applied by the method of filling the particles shown in FIG.

Evaluation 2) As an evaluation of the charging device, a DC voltage of -700 V was applied to the charging member, and the surface potential of the photosensitive member at 0 V at the first revolution and the saturation potential after the second revolution were measured.
The potential difference between the saturation potential and the first-round potential (convergence of potential) was measured.

◯: Potential difference is within 15 V ○ Δ: Potential difference is 15 to 30 V Δ: Potential difference is 30 to 60 V (practical lower limit level) ×: Potential difference is 60 V or more

Evaluation 3) Photoreceptor Using the photoconductor of Production Example 1, the photosensitive layer on the photoconductor was peeled off by about 1 mm ^2, and a defective photoconductor in which the aluminum base layer was exposed was used to form an image. The degree of image failure due to charging failure due to dielectric breakdown was evaluated according to the following evaluation items.

◯: Excellent (image defect remains only in the defective portion of the photoconductor) Δ: Lower limit of practical use (image defect is 30 m from the defective portion of the photoconductor)
m) x: Not practical (image defects spread over the entire image)

Evaluation 4) Evaluation of image deletion due to potential flow in the lateral direction was performed by character images according to the following evaluation items.

◯: Excellent (image deletion did not occur) ×: Practical use (image deletion occurred)

Evaluation 5) As a promotion of durability, the cleaning blade, which is a cleaning member, was removed, 500 sheets of solid black images were printed, and durability was evaluated. Evaluation was carried out in the same manner as in 2), and the decrease in chargeability before and after running was evaluated according to the following evaluation items.

◯: Charging property after endurance decreased within 30 V compared to before endurance ○ Δ: Charging property after endurance decreased in the range of 30 to 50 V compared to before endurance Δ: Endurance of chargeability after endurance Decrease in the range of 50 to 90 V compared to before (practical lower limit level) X: Decrease in charging property after endurance of 90 V or more compared to before endurance

Examples 2 to 12 and Comparative Examples 1 to 3 Table 1 summarizes the contents of Examples 1 to 12 and Comparative Examples 1 to 3, and the results are shown in Table 2.

In the image output durability evaluation of Example 7, the image exposure was back-scanning which was laser exposure to the non-image area to perform positive development, and the developing bias was a DC voltage of +180 V, the frequency was 2000 Hz, and the peak-to-peak voltage was 1. An image was displayed by changing the AC voltage of 0.5 KV to the superimposed voltage.

[0152]

[0153] In Comparative Example 3, there was adhesion to the photoconductor, and measurement was impossible.

[0154]

INDUSTRIAL APPLICABILITY In the present invention, an electrophotographic apparatus having an electrophotographic photosensitive member and a charging member arranged in contact with the electrophotographic photosensitive member, and charging the electrophotographic photosensitive member by applying a voltage to the charging member. In the charging device, the electrophotographic photosensitive member has a volume resistance value of 1 × 10 ⁸ Ωcm or more, and the charging member has magnetic particles containing 0.001 to 5% by weight of a phosphorus component. Has a volume resistance value of 1 × 10 ⁴ Ωcm or more and 1 × 10 ¹¹ Ωcm or less, it becomes possible to satisfactorily charge the surface of the photoconductor, and further, a charge for injecting electric charges onto the surface of the photoconductor. By providing an injection layer and charging it with a contact charging device using magnetic particles similar to those described above, uniform charging is given to the surface of the photoconductor by injection charging, and even if a defect occurs in the photoconductor, a leak image, etc. No image defects, stable It becomes possible to obtain an image, and by providing a resin coating layer on the surface of the magnetic particles, it is possible to suppress the adhesion and contamination of the toner on the magnetic particles, and it is possible to obtain a good image for a long period of time. .

[Brief description of drawings]

FIG. 1 is a schematic view schematically showing an electric resistance measuring device.

FIG. 2 is a schematic configuration diagram of an electrophotographic printer of the present invention.

FIG. 3 is a schematic view schematically showing a dynamic electric resistance measuring device.

[Explanation of symbols]

 1 Main Electrode 2 Upper Electrode 3 Insulator 4 Ammeter 5 Voltmeter 6 Constant Voltage Device 7 Magnetic Particles 8 Guide Ring 10 Photosensitive Drum 11 Contact Charging Member 12 Exposure Means 13 Toner Carrier 14 Transfer Material 15 Transfer Roller 16 Cleaning Blade 17 Heat The fixing roller 21 includes a mug-containing sleeve 21-a, a conductive sleeve 21-b, a magnet roll 22, an aluminum drum 23, a nip width between the charging member and the aluminum drum 24, a gap between the mag-containing sleeve and the aluminum drum 25, an ammeter 26, a constant voltage device 27, and a charging member. Magnetic particles that are

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Yoshifumi Hino 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Takeshi Takiguchi 3-30-2 Shimomaruko, Ota-ku, Tokyo Kya Non-Incorporated (72) Inventor Motoki Hisaki 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Yuji Ishihara 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. In the company

Claims (19)

[Claims] 1. An electrophotographic charging device comprising an electrophotographic photosensitive member and a charging member arranged in contact with the electrophotographic photosensitive member, and charging the electrophotographic photosensitive member by applying a voltage to the charging member, The volume resistance value of the electrophotographic photosensitive member is 1
× 10 ⁸ Ωcm or more, and the charging member is 0.00
It has magnetic particles containing 1 to 5% by weight of a phosphorus component, and the volume resistance value of the magnetic particles is 1 × 10 ⁴ Ωcm or more and 1 × 10 ¹¹
An electrophotographic charging device characterized by having an Ωcm or less. 2. The amount of phosphorus contained in the magnetic particles is 0.00
The electrophotographic charging device according to claim 1, wherein the amount is 5 to 5% by weight. 3. The electrophotographic charging device according to claim 1, wherein the phosphorus component contained in the magnetic particles is phosphorus oxide. 4. The 50% diameter of the volume distribution of the magnetic particles is 10
is 100 μm or more and 50% of volume distribution
4. The electrophotographic charging device according to claim 1, wherein the ratio of the diameter to the 5% diameter of the volume distribution is 1.40 or more. 5. The resistance value between the voltage application portion of the magnetic particles and the portion in contact with the electrophotographic photosensitive member is 1 × 10 ⁴ to 1 × 10.
The electrophotographic charging device according to claim 1, wherein the electrophotographic charging device has a resistance of ¹¹ Ω. 6. The electrophotographic charging device according to claim 1, wherein the surface layer of the magnetic particles contains a resin. 7. The electrophotographic charging device according to claim 1, wherein the resin of the surface layer of the magnetic particles has a main peak molecular weight P1 of GPC chromatogram of 10,000 or more. 8. The GPC chromatogram of the resin of the surface layer of the magnetic particles has at least one peak or shoulder on the low molecular weight side of the main peak.
The electrophotographic charging device described in any one of 1. 9. A ratio P1: of the molecular weight P1 of the main peak and the molecular weight P2 of the peak or shoulder on the low molecular weight side.
The electrophotographic charging device according to claim 8, wherein P2 is 3: 1 to 100: 1. 10. The molecular weight of the main peak is 30,000.
Is about 400000, and the molecular weight of at least one peak or shoulder on the low molecular weight side is 3000 to 3000.
The electrophotographic charging device according to claim 8, which is 0. 11. The resin of the surface layer of the magnetic particles has a weight average molecular weight Mw of 50,000 to 700,000, a number average molecular weight Mn of 5,000 to 50,000, and an Mw / Mn of 10.
The electrophotographic charging device according to claim 1, which is as described above. 12. The electrophotographic charging device according to claim 1, wherein the surface layer of the magnetic particles contains at least a polyolefin resin. 13. The electrophotographic charging device according to claim 1, wherein the resin of the surface layer of the magnetic particles contains conductive particles. 14. The electrophotographic charging device according to claim 1, wherein the surface layer of the electrophotographic photosensitive member is a charge injection layer. 15. The volume resistance value of the charge injection layer is 1 × 10.
⁸ Ωcm ~ 1 x 10 ^Fifteen15. The electrode according to claim 14, which is Ωcm.
Child photo charging device. 16. The electrophotographic charging device according to claim 14, wherein the charge injection layer contains conductive particles and a binder resin. 17. The electrophotographic charging device according to claim 14, wherein the charge injection layer contains a lubricant powder. 18. The lubricant powder is a fluorine resin, a silicone resin or a polyolefin resin.
The described electrophotographic charging device. 19. The electrophotographic charging device according to claim 14, wherein the charge injection layer is an inorganic semiconductor layer.