JPH1010840A - Charging device and electrophotographic device - Google Patents

Abstract

(57) Abstract: An object of the present invention is to prevent contamination and particles from adhering to each other, maintain good charging characteristics over a long period of time, and perform good injection charging over a long period of time. And a charging device and an electrophotographic device. The present invention relates to a charging device including an electrophotographic photosensitive member and a magnetic particle, the charging device having a charging member that is disposed in contact with the electrophotographic photosensitive member and charges the electrophotographic photosensitive member when a voltage is applied. In the above, the magnetic particles are
A surface layer containing a polyolefin resin having a weight average molecular weight of 000 or more, and 1 × 10 ⁴ to 1 × 1
A charging device and an electrophotographic device having a volume resistance of 0 ¹¹ Ωcm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charging device having an electrophotographic photosensitive member, a charging member which is disposed in contact with the electrophotographic photosensitive member and charges the electrophotographic photosensitive member when a voltage is applied thereto, and The present invention relates to an electrophotographic apparatus having a 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 photoreceptor by a charging unit and an image exposing unit, and then the latent image is developed with toner to form a visible image (toner image). 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 photoreceptor having a charge generation layer and a charge transport layer laminated thereon has been put to practical use, and a copier and a copier have been developed. It is installed in printers and facsimile machines. 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 a photoreceptor, and it can be interpreted by the so-called Paschen's law using a narrow space near the contact portion. A charging method has been developed in which the generation of ozone, which causes such a discharge, is minimized.

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, an organic photoconductive material containing about 2
When a charging roller is brought into contact with a photosensitive member having a photosensitive layer having a thickness of 5 μm, the surface potential of the photosensitive material starts to increase when a voltage of about 640 V or more is applied. On the other hand, the surface potential of the photoreceptor linearly increases at an inclination of 1. Hereinafter, this threshold voltage is defined as charging start voltage Vth. That is, in order to make the surface potential of the photoconductor Vd (V), a large DC voltage of Vd + Vth is required for the charging roller. Further, since the resistance value of the charging roller fluctuates due to environmental fluctuations or the like, it has been 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 is hardly affected by disturbances such as the environment.

However, even in such a charging method, the essential charging mechanism uses a discharge phenomenon from the charging member to the photosensitive member. Therefore, as described above, the charging is performed at a voltage higher than the surface potential of the photosensitive member. Is required. In addition, vibration and noise (hereinafter referred to as AC charging noise) of the charging member and the photoreceptor due to the electric field of the AC voltage, and the deterioration of the photoreceptor surface due to the discharge become remarkable, resulting in new problems.

On the other hand, as a charging method having higher charging efficiency, a so-called injection charging in which charges are directly injected into a photosensitive member is known.

This is a method in which a voltage is applied to a contact charging member such as a charging roller, a charging fiber brush, and a charging magnetic brush to inject a charge into a trap level on the surface of a photoreceptor. P2
87, "Contact charging characteristics using a conductive roller". However, in these methods, injection charging is performed with a low-resistance charging member to which a voltage is applied to a dark place insulative photoreceptor, and the charging member has a sufficiently low resistance value. It is a condition that a material (such as a conductive filler) imparting properties is sufficiently exposed on the surface. For this reason, the above-mentioned literature also states that the charging member is preferably an aluminum foil or an ion-conductive charging member having a sufficiently low resistance value in a high-humidity environment. According to the study of the present inventors, the resistance value of the charging member capable of sufficiently injecting electric charge into the photoconductor is 1 × 10 ³ Ω or less, and if it exceeds this, the difference between the applied voltage and the charging potential is exceeded. It has been found that the convergence of the charged potential starts to occur, causing a problem.

[0011]

However, when such a charging member having a low resistance value is actually used, an excessive current flows from the charging member to a flaw, a pinhole, or the like generated on the surface of the photoreceptor. Charging failure, enlargement of pinholes, and energization breakdown of the charging member easily occur.

In order to prevent this, the resistance value of the charging member needs to be about 1 × 10 ⁴ Ω or more. However, in such a charging member, charge injection to the photoconductor is performed as described above. This causes a contradiction that charging is not performed.

Therefore, it has been desired to solve the above-mentioned problems in a contact-type charging device or an electrophotographic device using the charging device.

Further, in a charging device using a charging member in contact with a photoreceptor, an image defect tends to occur due to a change in charging characteristics due to contamination (spent) of the charging member and a problem tends to occur in durability.

Spent of the charging member is considered to occur because toner or the like adhering to the photoreceptor without being removed by the cleaning unit is taken into the charging member and adheres to the surface of the charging member due to friction with the charging member. I have.

Therefore, in order to achieve spent resistance, a charging member is provided with a surface layer coated with a resin having spent resistance.

However, in general, a resin having excellent spent resistance does not have good adhesion to the core material, and the surface layer is peeled off due to durability due to the influence of adhesion and hardness of the surface layer. There were many.

Further, when the core material is magnetic particles, the particles tend to adhere to each other (a so-called blocking phenomenon) with use over a long period of time, and as a result, the charging tends to become non-uniform. This is a technical problem peculiar to the charging process, which hardly occurs in the developing process in which the ratio of the toner particles to the magnetic particles is large.

Therefore, it is urgently necessary to design an optimal surface layer in consideration of these factors and to prevent charging failure for a long period of time in order to enable printing of many sheets.

Also, in charging by charge injection into the photoreceptor, it is urgently necessary to prevent such charging failure for a long period of time in order to enable printing of a large number of sheets.

[0021] It is an object of the present invention to provide a charging device which is hardly stained and particles are hardly adhered to each other and which can maintain good charging characteristics for a long period of time, and an electrophotographic apparatus having the same.

Another object of the present invention is to provide a charging device capable of performing good injection charging over a long period of time and an electrophotographic apparatus having the same.

[0023]

That is, the present invention provides:
An electrophotographic photoreceptor and magnetic particles.
It is placed in contact with the light body, and
Charging device having a charging member for charging the photoreceptor.
The magnetic particles have a weight average molecular weight of 10,000 or more.
With a surface layer containing polyolefin resin
And 1 × 10 ^Four ~ 1 × 10¹¹Ωcm volume resistance
It is a charging device characterized by having.

Further, the present invention provides an electrophotographic photosensitive member and a magnetic particle, which are arranged in contact with the electrophotographic photosensitive member and charge the electrophotographic photosensitive member by applying a voltage, an exposure means, In an electrophotographic apparatus having a developing unit and a transfer unit, the magnetic particles have a surface layer containing a polyolefin resin having a weight average molecular weight of 10,000 or more, and are in a range of 1 × 10 ⁴ to 1 × 10 ¹¹ Ωcm. An electrophotographic apparatus characterized by having a volume resistance value of:

Examples of the polyolefin resin used in the present invention include resins obtained by polymerizing or copolymerizing ethylene, propylene, butylene and the like.

Weight average molecular weight M of polyolefin resin
When w is less than 10,000, blocking resistance and abrasion resistance are not sufficient. Preferably it is 30,000 or more, more preferably 50,000 to 500,000.

The polyolefin resin used in the present invention has a main peak molecular weight (P1) of GPC chromatogram of 10,000 or more and at least one peak or shoulder (P2) on the low molecular weight side of the main peak. It is more preferred to have. The main peak on the high molecular weight side improves the abrasion resistance of the resin and prevents the surface from being spent by toner or the like. The sub-peak or shoulder on the low molecular weight side has the effect of improving the adhesion between the magnetic particle core material and the resin and preventing the coating resin from peeling off from the magnetic particles. Even when the magnetic particles of the charging member are likely to have a large share due to the synergistic effect, the deterioration of the magnetic particles is small, uniform charging can be obtained even by long-term durability, and a good image can be obtained.

Specifically, the molecular weight (P1) of the main peak of the polyolefin resin of the present invention is from 30,000 to 4
Preferably, the molecular weight is at least one peak on the low molecular weight side or the shoulder molecular weight from the viewpoint of abrasion resistance under long-term shear conditions and adhesion (peeling) between the surface layer and the core material. Is 3,000-30,0
00 is preferred. In the present invention,
The inflection point of the differential curve of the GPC chromatogram was defined as the peak / shoulder position.

The weight average molecular weight Mw is 50,000.
５００500,000, number average molecular weight Mn is 5,000-5
000, Mw / Mn is 10 or more, and Z-average molecular weight Mz is 1,000,000.
It is preferable that it is in the range of 5,000,000 from the viewpoint that the effect of the present invention can be more remarkably obtained. More preferably, the molecular weight of the main peak is from 50,000 to 30.
000, low molecular weight peak or shoulder molecular weight of 3,000 to 15,000, weight average molecular weight Mw
Is 100,000-500,000, number average molecular weight Mn
Is 7,000 to 40,000, Mw / Mn is 20 or more,
Z average molecular weight Mz is from 1,500,000 to 4,500,
000.

The ratio between the molecular weight P1 of the main peak and the molecular weight P2 of the low molecular weight side peak or shoulder is preferably 3: 1 to 100: 1. It is preferable from the viewpoint of compatibility, and in order to exhibit a longer-term effect, the ratio is preferably 5: 1 to 50: 1.

The molecular weight of the polyolefin resin of the present invention was measured by the following method.

The apparatus used was a gel permeation chromatography (GPC) measuring apparatus manufactured by Waters, a GPC-
Using 150C, the measurement was performed under the following conditions.

Column: 2 Shodex HT-806M (1 precolumn Shodex HT-800P) Temperature: For polyethylene resin 145 ° C Other resin 40 ° C Solvent: For polyethylene resin o-dichlorobenzene (0.1% ionol added) ) For other resins Tetrahydrofuran Flow rate: 1.0 ml / min Sample: 0.4 ml of 0.15% sample injected

When measuring the molecular weight of the resin after coating the magnetic particles, the magnetic particles are subjected to Soxhlet extraction for 20 hours using a xylene solvent, xylene is removed from the extract with an evaporator or the like, dried, and dried. The solid content is used as a sample.

In calculating the molecular weight of the sample, a molecular weight calibration curve prepared from a monodisperse polystyrene standard sample was used.

In the present invention, for example, the following resins may be used in combination as long as the effects of the present invention can be obtained.

That is, polyamide resins such as nylon 6 and nylon 66, polyester resins such as polyethylene terephthalate, epoxy resins, silicone resins such as methyl silicone, methyl phenyl silicone and silicone acryl, vinyl chloride resins, polyurethane Resin, polytetrafluoroethylene, tetrafluoroethylene perfluoroalkyl vinyl ether copolymer, fluorine resin such as polyvinylidene fluoride, polycarbonate resin, melamine resin, styrene resin, acrylic resin such as polymethacrylic acid ester , Polyacetal resins, vinyl acetate resins, phenol resins and the like.

In the present invention, the resistance value of the charging member is 1
It is preferably from × 10 ⁴ Ω to 1 × 10 ¹¹ Ω. If the resistance value is less than 1 × 10 ⁴ Ω, pinhole leakage is likely to occur, and if it exceeds 10 ¹¹ Ω, good charging becomes difficult.
In order to control the resistance of the charging member within the above range, the volume resistance of the magnetic particles of the present invention is 1 × 10 ⁴ Ωc.
m to 1 × 10 ¹¹ Ωcm.

When the charging device of the present invention is used for injection charging, the charging member plays a role of satisfactorily injecting charges into the charge injection layer of the photoreceptor, and the charging current concentrates on defects such as pinholes formed on the photoreceptor. It must also have the role of preventing the charging member and the photoconductor from being energized and destroyed due to the charging.

From the viewpoint, the resistance value of the charging member is 1 ×
It is preferably 10 ⁴ Ω~1 × 10 ⁹ Ω, and particularly preferably from ^{1 × 10 4 Ω~1 × 10 7} Ω. When the resistance value of the charging member is less than 1 × 10 ⁴ Ω, pinhole leakage tends to occur, and when it exceeds 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 magnetic particles of the present invention preferably have a volume resistance value of 1 × 10 ⁴ Ωcm to 1 × 10 ⁹ Ωcm, and particularly preferably 1 × 10 ⁹ Ωcm. ⁴ Ωcm to 1 × 10 ⁷ Ω
cm.

When the charging member is used not for injection charging but for discharging, the charging member has a resistance of 1 × 10 ⁵ Ω to 1 × 10 ⁵ Ω.
It is preferably × 10 ¹¹ Ω, and the volume resistivity of the magnetic particles is preferably 1 × 10 ⁶ Ωcm to 1 × 10 ¹¹ Ωcm.

The volume resistance of the magnetic particles used in the charging member was measured using an electric resistance measuring device shown in FIG. That is, the cell A is filled with magnetic particles, and the electrodes 9 and 10 are arranged so as to be in contact with the magnetic particles. Then, a voltage is applied between the electrodes, and a current flowing at that time is measured to obtain a volume resistance value. The measurement conditions were as follows: a temperature of 23 ° C., a humidity of 65%, a contact area S between the magnetic particles and the cell S = 2 cm ² , a thickness d = 1 mm, and a load 1 on the upper electrode.
0 kg and an applied voltage of 100 V.

In FIG. 2, 9 is a main electrode, 10 is an upper electrode, 11
Denotes an insulator, 12 denotes an ammeter, 13 denotes a voltmeter, 14 denotes a constant voltage device, 15 denotes magnetic particles, and 16 denotes a guide ring.

In the present invention, a magnetic brush is formed by causing magnetic particles to spike on a conductive member (sleeve) by magnetism, and this magnetic brush is brought into contact with a photosensitive member as a charging member. Therefore, as the magnetic particles contained in the charging member, alloys or compounds containing ferromagnetic elements such as iron, cobalt and nickel are used.

However, if these are used as they are, the volume resistance value does not fall within the preferred range, so that the volume resistance value is adjusted to a preferred range by performing oxidation treatment, reduction treatment, or the like.
For example, ferrite with adjusted composition, Zn with hydrogen reduction treatment
-Cu ferrite and oxidized magnetite are used.

The particle size of the magnetic particles of the present invention is 10 to 1
It is preferably 00 μm. If it is smaller than 10 μm, the magnetic particles tend to adhere to the photoreceptor. Also 100 μm
If it is larger, the density of the ears of the magnetic brush on the sleeve cannot be increased, and uneven charging tends to occur. More preferably, 1
5 to 50 μm. The particle size of the magnetic particles can be measured by a laser diffraction particle size distribution analyzer HEROS (JEOL Ltd.)
Was measured by dividing the range of 0.05 to 200 μm into 32 logarithms, to obtain a 50% diameter of the volume distribution.

The amount of the surface layer with respect to the core material (magnetic particles) is preferably such that the solid content of the surface layer is 0.1 to 20% by weight.
If the amount is less than 0.1% by weight, the coating effect is not sufficient. If the amount exceeds 20% by weight, even if the conductive particles are dispersed, the chargeability is hardly improved, and the adhesion to the core material is rather reduced. Because of the decrease, peeling of the film and detachment of the conductive particles are likely to occur. In addition, the cost is increased, which is not preferable.

In the present invention, the surface layer does not necessarily have to completely cover the core material, and the core material may be exposed as long as the effects of the present invention can be obtained. That is, the surface layer may be formed discontinuously.

The method for producing the magnetic particles of the present invention is not particularly limited, and known methods such as a spray drying method and a dry coating method can be applied. Among them, in the present invention, it is preferable to use a method described in, for example, JP-A-60-106808 or JP-A-60-106809. According to this method, a polyolefin-based resin layer is formed directly on the surface of the magnetic particles (direct polymerization). Therefore, if the resin of the present invention is used, resin-coated magnetic particles having extremely excellent strength and durability can be obtained. Can be Further, by appropriately adjusting the molecular weight, it is possible to further enhance the adhesion between the polyolefin-based resin layer and the core material.

When a surface layer made of a resin is provided on the surface of the magnetic particles, the resin generally has high resistance, so that the resistance of the obtained magnetic particles increases, and depending on the coating amount,
In some cases, the charging characteristics are deteriorated as compared with the case where no surface layer is provided. In this case, it is necessary to use a surface layer in which conductive particles are dispersed as the surface layer and make the resistance of the surface layer approximately equal to the resistance of the core material. However, when the magnetic particles are used, the charging characteristics are improved, but the adhesion to the core material is reduced, the film strength is reduced, and the conductive particles are likely to be detached.
As a result, the charging characteristics are liable to change, which is a problem in long-term use.

In the present invention, since a polyolefin-based resin layer having a weight average molecular weight of 10,000 or more is used, it can be formed into a thin film or a conductive particle dispersion layer to form a charging member for charging a photoreceptor. It is now possible to control the resistance to an appropriate value.

In general, when the particle diameter of the magnetic particles is small, it becomes difficult to uniformly coat the entire surface of the magnetic particles with the resin. However, in the magnetic particles of the present invention, the entire surface of the magnetic particles can be uniformly coated by using the direct polymerization method. Therefore, even in such a case, it is possible to exhibit good charging characteristics over a long period of time.

The conductive particles used in the present invention include:
Generally known conductive particles can be used, for example, copper, nickel, iron, aluminum, gold, silver or other metal or iron oxide, zinc oxide, tin oxide, antimony oxide,
Examples include metal oxides such as titanium oxide, and conductive powders such as carbon black. These may be subjected to a surface treatment for the purpose of hydrophobization or resistance adjustment as needed.
At the time of use, it is selected and used in consideration of dispersibility with resin and productivity.

The above-described magnetic particles are generally held by a conductive member (sleeve) such as a metal cylinder or metal foil having an arbitrary surface roughness and including a permanent magnet such as a magnet for restraining the magnetic particles. Used in the form.

The charging member thus manufactured is used in a state where a charging nip is formed by using a suppressing means such as a spring and the photosensitive member is brought into a suppressed contact.

Further, from the viewpoint of obtaining a high-definition image, it is preferable that a voltage capable of charging the surface of the photosensitive member to 400 V or more is applied to the magnetic particles forming the charging member. More preferably, the voltage is applied so as to exceed 500V. In addition, in the injection charging, a preferable embodiment of the present invention is to apply an AC voltage having a peak-to-peak voltage of 2 × Vth (V) or less to the DC voltage from the viewpoint of charging uniformity. On the other hand, in discharge charging, the DC voltage is 2
It is preferable to apply an AC voltage having a peak-to-peak voltage of Vth (V) or more from the viewpoint of charging uniformity.

In general, in a charging method using a charging member made of magnetic particles, the magnetic particles tend to be extruded into an end region in the longitudinal direction (general generatrix direction) of the charging member as it is used. In addition, the contact between the charging member and the photosensitive member is likely to be uneven.

When the contact becomes uneven, the charging potential of the photosensitive member at the end of the charging member is partially lower than that at the center. Due to this potential drop, the potential difference between the potential of the electrode sleeve and the surface potential of the photoconductor increases, and as a result, the magnetic particles move (attach) from the charging member to the photoconductor or detach (leak). As described above, the movement and detachment of the magnetic particles to the photoconductor side decrease the contact between the magnetic brush and the photoconductor, thereby causing charging failure.

Therefore, in the present invention, it is preferable to provide an insulating or conductive member in the longitudinal end region of the charging member (hereinafter, also referred to as an end treatment). Is very suitable and has a remarkable effect.

This is because the magnetic particles of the present invention can also prevent wear of the magnetic particles and the treated part. In particular, it is very effective when the processing portion is made of resin.

An example of the edge processing means will be specifically described with reference to the drawings.

(1) As shown in FIG.
A ring-shaped insulator 24 is provided on the outer peripheral surface at the longitudinal end of the ring. The rotatable electrode sleeve 22 contains a magnet roll 21.

In this configuration, the magnetic particles 2
Since the conduction path to the magnetic particles 3 is cut off, no charge is injected into the magnetic particles in a portion where the contact with the photoconductor 1 becomes uneven, and the adhesion electric field does not work on the magnetic particles 23, so that the magnetic particles 23 on the photoconductor 1 side Can be prevented from adhering to the surface.

As the insulator 24, polyester resin,
Nylon resin, silicone resin, fluororesin, acrylic resin, urethane resin, phenolic resin, polyolefin resin, polycarbonate resin, and other resins are listed, and these resins can be directly coated or film-like or cap-like ones with an adhesive. And stick it. In addition, styrene,
A tube made of a urethane-based, polyamide-based, olefin-based, or fluorine-based elastomer can also be formed by press-fitting or heat shrinking.

(2) As shown in FIG.
-1 in the area corresponding to the end of the magnetic brush 2
Form 2-3.

Specifically, the float electrode 22-3 is connected to the second
And is formed of a sleeve-like material made of a conductive material, and is fixed to the electrode sleeve 22-1 via the insulating spacer 22-2. Flow and electrode 22-3
Is made of a conductive material such as a metal such as aluminum, SUS and copper, or a resin in which conductive particles are dispersed.

Examples of the material of the insulating spacer 22-2 include resins such as polyester resin, nylon resin, silicone resin, fluorine resin, acrylic resin, urethane resin, phenol resin, polyolefin resin and polycarbonate resin.

In this configuration, the float electrode 22-
By the action of 3, the potential of the magnetic particles 23 at the end of the magnetic brush becomes the same level as the potential of the photoreceptor 1, so that no charge is injected into the magnetic particles. As a result, the adhesion of the magnetic particles to the photoconductor can be prevented.

Further, in the present invention, as shown in FIG. 5, a float electrode 22-3 can be provided on the surface of the ring-shaped insulator of (1).

(3) As shown in FIGS. 6 and 7, the float electrode portion 22-3 in the area corresponding to the end of the magnetic brush of the electrode sleeve shown in (2) is grounded.

More specifically, the float electrode 22-3 is grounded so as to be shared with the photoconductor ground.

With the grounding of the end, the potential of the magnetic brush 23 also decreases toward the end, and the potential finally reaches the ground of the photoconductor, so that the magnetic brush 23 and the photoconductor 1 (the surface of the photoconductor where the brush does not contact) are contacted. Can be prevented for a long time.

This configuration is particularly effective for an AC superimposed charging method in which a large potential difference occurs between the charging member and the photosensitive member as compared with the DC voltage charging method.

The AC superposition charging method is generally used in the conventional electrophotographic process. However, even in a cleanerless process in which a cleaning device for removing the transfer residual toner on the surface of the photoreceptor is eliminated, the transfer residual toner can be removed. The AC superposition charging method is adopted for the purpose of suppressing the influence, and this configuration is highly effective as a charging contact charging device for a cleanerless process.

(4) As shown in FIG. 8, an electrode (conductive member) 25 is formed on the surface of the photoconductor 1 at a position corresponding to the end of the magnetic brush at the longitudinal end of the photoconductor 1.

Since the electrode 25 comes into contact with the end of the magnetic brush 23 and has the same potential as the electrode sleeve 22, even if the magnetic particle 23 is pushed to the end at the charging nip portion, no charge is injected into the magnetic particle. Since no electric force acts, the adhesion of magnetic particles can be prevented.

(5) As shown in FIG. 9, a float electrode portion (conductive member) 29 insulated from the photoreceptor support at a position corresponding to the end of the magnetic brush at the longitudinal end of the photoreceptor 1
Is provided. Here, 28 is an insulating layer.

As a result, the potential of the electrode portion 29 becomes the same as that of the magnetic brush 23, thereby preventing the magnetic particles 23 from adhering to the photosensitive member 1.

(6) As shown in FIG. 10, the magnetic brush can be formed by directly attaching the magnetic particles 23 to the rotatable multi-pole magnet roll 21 as a configuration of the charging device.

By adhering the magnetic particles 23 directly to the surface of the magnet roll 21, the binding force of the magnetic particles is strengthened and the adhesion to the photoreceptor is prevented.

In this configuration, the surface of the magnet roll 21 can be subjected to the conductive treatment 30 in order to apply a voltage to the magnetic particles. The conductive processing region may extend to both ends of the magnetic brush, and the ends may be regulated (insulated) by the sealing material 31 or the like. Even if the magnetic brush spreads outside the conductive processing area, the charge conduction path is cut off, so that charge injection into the magnetic particles 23 does not occur, and the magnetic particles 23
Adhesion to the side is prevented.

Examples of the conductive treatment include a method of depositing a metal for forming a resin layer in which the conductive particles are dispersed as described above and winding a metal foil or the like.

Next, the electrophotographic photosensitive member used in the present invention will be described.

When the charging device of the present invention is used for injection charging, the photoreceptor has a charge injection layer as a layer farthest from the support, that is, a surface layer.

The volume resistivity of the charge injection layer is preferably from 1 × 10 ⁸ to 1 × 10 ¹⁵ Ωcm in order to obtain sufficient chargeability and to prevent image deletion. In particular, from the viewpoint of image deletion, it is preferable that the volume resistivity is 1 × 10 ¹⁰ to 1 × 10 ¹⁴ Ωcm, and 1 × 10 ¹² to 1 × 10 ¹⁴ Ωcm in consideration of environmental fluctuation of the volume resistance. If the volume resistance is less than 1 × 10 ⁸ Ωcm, the charge flow is less likely to be held in the surface direction in a high humidity environment, so that an image flow is likely to occur. Also, 1 × 10 ¹⁵ Ωc
If m exceeds m, the charge from the charging member cannot be sufficiently injected and held, and the charging failure tends to occur.

The method for measuring the volume resistance of the charge injection layer according to the present invention is as follows. A surface layer is formed on a polyethylene terephthalate (PET) film having gold deposited on the surface, and the surface layer is formed using a volume resistance measuring device (manufactured by Hewlett-Packard Company). 41
The measurement is performed by applying a voltage of 100 V in an environment of 23 ° C. and 65% at 40 B pA MATER).

By using the charging device of the present invention and the above-described photoreceptor, the charging start voltage Vth is small and the photoreceptor can be charged to a potential almost 90% or more of the voltage applied to the charging member. .

For example, the charging device of the present invention has an absolute value of 10
When a DC voltage of 0 to 2,000 V is applied at a process speed of 1000 mm / min or less, the charging potential of the electrophotographic photoreceptor having the charge injection layer is set to 80% or more, and more preferably 90% or more of the applied voltage. it can. On the other hand, the charging potential of the photoreceptor obtained by charging using conventional discharge is almost 0 V when the applied voltage is 640 V or less, and is 64 V.
When the voltage is 0 V or more, only a charging potential of a value obtained by subtracting 640 V from the applied voltage can be obtained.

The charge injection layer is composed of an inorganic layer such as a metal vapor-deposited film or a conductive powder-dispersed resin layer in which conductive fine particles are dispersed in a binder resin. Is dipping coating method, spray coating method,
It is formed by coating by an appropriate coating method such as a roll coating method and a beam coating method. Further, a resin formed by mixing or copolymerizing an insulating binder resin with a resin having high light transmittance and ionic conductivity, or a resin formed of a single resin having a medium resistance and photoconductive properties may be used.

First, in the case of a resin layer composed of conductive fine particles and a binder resin, the binder resin includes polyester resin, polycarbonate resin, polystyrene resin, fluororesin, cellulose, vinyl chloride resin, polyurethane resin, acrylic resin, epoxy resin, and the like. Resin, silicone resin, alkyd resin,
Resins such as vinyl chloride-vinyl acetate copolymer resins can be used. Examples of the conductive fine particles include metals such as copper, aluminum, silver, and nickel, metal oxides such as zinc oxide, tin oxide, antimony oxide, tin oxide, and titanium oxide, and solid solutions and fused materials thereof, polyacetylene, polythiophene, and polypyrrole. However, it is more preferable to select and use a metal oxide such as tin oxide having high transparency from the viewpoint of the translucency of the photoreceptor. The particle diameter of these conductive fine particles is preferably 0.3 μm or less from the viewpoint of translucency, and most preferably 0.1 μm or less.
μm or less. When it is contained in the charge injection layer, the content of the conductive fine particles depends on the particle size, but is preferably in the range of 2 to 280% by weight based on the binder resin.
If the content is less than 2% by weight, it is difficult to adjust the resistance of the charge injection layer, and if it exceeds 280% by weight, the coating properties of the binder resin may be partially reduced.

The binder resin of the charge injection layer can be the same as the binder resin of the lower layer. In this case, the coating surface of the charge transport layer is disturbed during the coating of the charge injection layer. It is necessary to pay attention to the coating method.

Various additives can also be added for the purpose of improving the dispersibility of the conductive fine particles, the adhesiveness with the binder resin, and the smoothness of the coating film after film formation. Especially,
To improve the dispersibility, it is very effective to modify the surface of the conductive fine particles with a coupling agent or a leveling agent. Further, from the viewpoint of improving dispersibility, it is effective to use a curable resin as the binder resin.

When a curable resin is used for the charge injection layer, a coating liquid in which conductive fine particles are dispersed in a solution of a curable monomer or oligomer is applied to the photosensitive layer, and after forming a film, heat or light irradiation is performed. The coating is cured to form a surface layer. Examples of such a curable resin include an acrylic resin, an epoxy resin, a phenol resin, and a melamine resin, but are not limited thereto. Any resin that causes and cures can be used.

The charge injection layer has a thickness of 0.1 to 10 μm.
It is particularly preferable that the thickness be 0.5 to 5 μm.

Further, the charge injection layer may contain a lubricant powder. The friction between the photosensitive member and the charging member or the friction between the photosensitive member and the cleaning member is reduced, and the dynamic load on the electrophotographic apparatus can be reduced. In addition, since the releasability of the photoreceptor surface is improved, adhesion of developer particles (toner) can be prevented. As such lubricant particles, it is preferable to use a fluororesin, silicone resin or polyolefin resin having a low critical surface tension. Particularly preferred is a tetrafluoroethylene resin. In this case, the amount of the lubricant powder added is
Preferably it is 2 to 50% by weight, more preferably 5 to 40% by weight, based on the binder resin. If the amount is less than 2% by weight, the effect of improving the chargeability is not sufficient because the amount of the lubricant powder is not sufficient, and if it exceeds 50% by weight, the dispersibility of the image and the sensitivity of the photoreceptor tend to decrease.

Next, examples of the charge injection layer made of an inorganic material include a semiconductor such as amorphous silicon.

The photoreceptor made of silicon can be manufactured continuously by using a plasma chemical vapor deposition apparatus by high-frequency glow discharge decomposition by selecting photoconductive amorphous silicon for the lower photosensitive layer.

The photosensitive layer in the present invention is formed by laminating a charge generation layer and a charge transport layer, but a single layer type in which the charge generation material and the charge transport material constituting each layer are made the same layer is also possible. Here, the thickness of the charge transport layer is 5 to 40 μm,
The thickness of the charge generation layer is set in the range of 0.05 to 5 μm.

Examples of such photosensitive layer materials include organic materials such as phthalocyanine pigments and azo pigments, and inorganic materials such as silicon compounds.

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

As the conductive support for the photoreceptor in the present invention, metals such as aluminum, nickel, stainless steel and steel, plastics or glass having a conductive film, conductive paper and the like can be used.

[0102]

BEST MODE FOR CARRYING OUT THE INVENTION

[Production Example of Magnetic Particles for Charging Member] (Production Example 1 of Magnetic Particles) Polymerization conditions such as an amount of a catalyst and a reaction time are adjusted based on a method known in JP-A-60-106808 and JP-A-60-106809. And Cu
A polyethylene resin layer is directly polymerized on the surface of Zn ferrite magnetic particles (average particle diameter 27 μm), and the resistance is 7 × 10
Magnetic particles 1 of ⁷ Ωcm were obtained. The molecular weight distribution was such that the main peak molecular weight was 95,000 and the shoulder was 5,000.
0, Mn = 10,000, Mw = 285,000, Mw
/Mn=28.5.

(Magnetic Particle Production Examples 2 to 4) Magnetic particles shown in Table 1 were produced by adjusting polymerization conditions such as the amount of the catalyst and the reaction time based on a known method similar to that of Magnetic Particle Production Example 1.

The resistance of the magnetic particles 2 and 3 was adjusted by adding carbon black as conductive fine particles in the surface layer during polymerization.

(Production Example 5 of Magnetic Particles) Hot Xylene Solvent 10
0.1 parts by weight of a polyethylene resin having a peak molecular weight of 7000 and 0.9 parts by weight of a polyethylene resin having a peak molecular weight of 130,000 were added to 0 parts by weight and mixed to prepare a surface layer solution. Mn = 15,000 for the whole mixed resin
0, Mw = 390,000, Mw / Mn = 26.0. This solution was applied to Cu-Zn ferrite magnetic particles (average particle size: 24 μm) using a spira coater to obtain magnetic particles 5 having a resistance value of 7 × 10 ⁷ Ωcm.

(Production Example 6 of Magnetic Particles) Production Example 5 of magnetic particles except that a polyethylene resin having the following molecular weight distribution was used.
In the same manner as in the above, magnetic particles 6 having a resistance of 9 × 10 ⁷ Ωcm were obtained. The molecular weight distribution was such that the peak molecular weight was 35,000,
Mn = 7,000, Mw = 110,000, Mw / Mn
= 15.7.

(Production Example 7 of Magnetic Particles) In the same manner as in Production Example 5 of magnetic particles, a mixture of 0.1 parts by weight of a polyethylene resin having a peak molecular weight of 5,000 and 0.9 parts by weight of a polyethylene resin having a peak molecular weight of 110,000 was used. Dispersed carbon. This was applied to Cu—Zn ferrite magnetic particles (average particle diameter 27 μm) to obtain magnetic particles 7 having a resistance of 1 × 10 ⁷ Ωcm. For the mixed resin as a whole, Mn = 1
4,500, Mw = 383,000, Mw / Mn = 2
6.4.

(Magnetic Particle Production Example 8) Argon-substituted 5
100 ml of purified n-heptane, 10 g of magnesium stearate and 0.3 g of titanium tetrachloride in a 00 ml flask.
3 g, and the mixture was heated and reacted under reflux for 2 hours to obtain a titanium-containing catalyst component.

In a separately prepared 3,000 ml flask, purified n-heptane (1,000 ml), dehydrated and dried under reduced pressure at 150 ° C., particle size 25 μm, volume resistivity 1 × 10 ⁵ Ωcm
Of Cu-Zn ferrite fine powder and 0.3 g (equivalent to 0.05 mmol) of a titanium-containing catalyst component were added, and the mixture was heated and heated for 1 hour under reflux to obtain a mixture 8.

Next, a volume of 3,000 ml replaced with argon
The mixture 8 was placed in the autoclave of No. 1, and purified n-heptane was added to make the total amount 1,500 ml. Then, 5 mmol of triethylaluminum and 5 mmol of diethylaluminum monochloride were added, and after heating to 80 ° C., hydrogen was added. Supply up to 3 kg / cm ² G, total pressure 7 kg / cm ² G
While continuously supplying ethylene gas to maintain
The polymerization reaction was carried out for 1 minute to obtain polyolefin resin-coated magnetic particles 8 having a volume resistance of 8 × 10 ⁶ Ωcm. This was constrained by a 16 mm sleeve containing a magnet, and used as a charging member. The weight average molecular weight Mw of the polyolefin on the surface of the magnetic particles was 170,000.

(Production Example 9 of Magnetic Particles) Synthesis was performed in the same manner as in Production Example 8 of magnetic particles, except that a monomer having a composition of ethylene / propylene = 9/1 was used as a monomer. Polyolefin resin-coated magnetic particles 9 of 10 ⁶ Ωcm were obtained.

(Production Example 10 of Charging Member) 1,000 ml of purified n-heptane was placed in a 3,000 ml flask under reduced pressure.
Particle size 25 μm dehydrated and dried at 50 ° C., volume resistance value 1 × 1
0 ⁵ cm of Cu-Zn ferrite fine powder 600 g, carbon black 0.3g and the charging member production example titanium-containing catalyst component 0.6g put (0.1 mmol equivalent) used in 8, under reflux for 1 was heated The mixture is heated for 10 hours.
I got

Next, a volume of 3,000 ml replaced with argon
The mixture 10 was placed in the autoclave of No. 1, and purified n-heptane was added to make the total amount 1,500 ml. Then, 10 mmol of triethylaluminum and 10 mmol of diethylaluminum monochloride were added, and the temperature was raised to 80 ° C.
Hydrogen is supplied up to 4 kg / cm ² G and the total pressure is 9 kg / c
ethylene gas to maintain the m ² G performs continuously fed for 30 minutes while the polymerization reaction, the volume resistivity is 2 × 10 ⁶ Ωc
m of polyolefin resin-coated magnetic particles 10 were obtained. The weight average molecular weight Mw of the polyolefin in the surface layer of the magnetic particles was 250,000.

(Production Example 11 of Magnetic Particles) A volume resistivity of 1 × 10 ⁶ Ωcm was obtained in the same manner as in Production Example 10 of magnetic particles except that a monomer having a composition of ethylene / propylene = 9/1 was used as a monomer. Polyolefin resin-coated magnetic particles 11 were obtained.

(Magnetic Particle Production Example 12) A xylene solution of a low density polyethylene resin (polyethylene resin solid content 0.5
Weight%), 400 parts by weight average molecular weight 50,000), and 0.2 part of carbon black dispersed therein. Spiral coater (Okada Seiko Co., Ltd.) A polyethylene resin in which carbon black was dispersed was applied to obtain polyolefin resin-coated magnetic particles 12 having a volume resistance of 3 × 10 ⁶ Ωcm.

(Production Example 13 of Magnetic Particles) As magnetic particles,
Except that 600 g of a Cu—Zn ferrite fine powder having an average particle diameter of 25 μm and a volume resistivity of 4 × 10 ⁶ Ωcm was used, the volume resistivity was 7
× 10 ⁷ Ωcm polyolefin resin-coated magnetic particles 13
I got

(Production Example 14 of Magnetic Particles) As magnetic particles,
Except for using 600 g of a Cu-Zn ferrite fine powder having an average particle size of 80 µm and a volume resistance value of 5x10 ⁶ Ωcm, the volume resistance value was 8x in the same manner as in the magnetic particle production example 10.
Polyolefin resin-coated magnetic particles 14 of 10 ⁷ Ωcm were obtained.

(Production Example 15 of Magnetic Particles)
C having an average particle size of 80 μm and a volume resistivity of 8 × 10 ⁸ Ωcm
Polyolefin resin-coated magnetic particles 15 having a volume resistivity of 4 × 10 ¹¹ Ωcm were obtained in the same manner as in Magnetic Particle Production Example 8 except that 600 g of the u-Zn ferrite fine powder was used and the polymerization reaction time was changed to 30 minutes.

(Production Example 16 of Magnetic Particles) Production Example 1 of Magnetic Particles
The uncoated Cu—Zn-based ferrite fine powder having a volume resistivity of 4 × 10 ⁶ Ωcm used in 3 was used as the magnetic particles 16.

(Production Example 17 of Magnetic Particles) Production Example 1 of Magnetic Particles
The uncoated Cu—Zn-based ferrite fine powder having a volume resistivity of 8 × 10 ⁸ Ωcm used in 5 was used as the magnetic particles 17.

(Production Example 18 of Magnetic Particles) The average particle size was 25 μm.
The uncoated magnetite fine powder having a volume resistivity of 7 × 10 ³ Ωcm was used as the magnetic particles 18.

(Production Example 19 of Magnetic Particles) The resistance was 4 × 10 ⁸ Ω in the same manner as in Production Example 12 of magnetic particles except that the weight average molecular weight Mw of the polyethylene resin was set to 10,000.
cm of polyolefin resin-coated magnetic particles 19 were obtained.

(Magnetic Particle Production Example 20) 100 ml of purified n-heptane was placed in a 500 ml flask purged with argon.
10 g of magnesium stearate and 0.1 g of titanium tetrachloride.
33 g was added, and the mixture was heated and reacted under reflux for 2 hours to obtain a titanium-containing catalyst component.

A separately prepared 3,000 ml flask was charged with 1,000 ml of purified n-heptane, dehydrated and dried at 150 ° C. under reduced pressure, and having a particle size of 25 μm and a resistance of 1 × 10 ⁵ Ωcm.
600 g of u-Zn ferrite fine powder and 0.3 g (equivalent to 0.05 mmol) of a titanium-containing catalyst component were added, and the mixture was heated and heated for 1 hour under reflux to obtain a mixture 20.

Next, a volume of 3,000 m
l of the mixture 20 was placed in an autoclave, and purified n-heptane was added to make the total amount 1,500 ml. Then, 5 mmol of triethylaluminum and 5 mmol of diethylaluminum monochloride were added, and after heating to 80 ° C, hydrogen was added. Supply up to 3 kg / cm ² G, total pressure 7 kg / cm
While continuously feeding ethylene gas so as to maintain the ² G 3
A polymerization reaction was performed for 0 minutes to obtain polyolefin resin-coated magnetic particles 20 having a resistance of 6 × 10 ¹⁰ Ωcm. 0.1 parts by weight of carbon black was dry-dispersed in 100 parts by weight of the polyolefin resin-coated magnetic particles, and the carbon black was fixed to the particle surface mechanochemically using a hybridizer (manufactured by Nara Machinery Co., Ltd.). The resistance of the obtained magnetic particles is 5 ×
It was 10 ⁶ Ωcm. The weight average molecular weight Mw of the polyolefin in the surface layer of the magnetic particles was 220,000.

(Production Example 21 of Magnetic Particles) Production Example 12 of magnetic particles except that Mw of polyethylene resin was set to 5,000.
In the same manner as in the above, polyolefin resin-coated magnetic particles 21 having a resistance of 5 × 10 ⁶ Ωcm were obtained.

(Production Example 22 of Magnetic Particles) The resistance value was 3 × 1 in the same manner as in Production Example 8 of magnetic particles except that the reaction conditions were changed.
0 ⁶ [Omega] cm to obtain a polyolefin resin-coated magnetic particles 22.

[0128]

[Table 1]

[Production Example of Electrode Sleeve] (Production Example 1 of Electrode Sleeve) Based on FIG. 3, the electrode sleeve 22 was subjected to end treatment. That is, a polyester sheet 24 having a thickness of 40 μm was adhered to the outer peripheral surface near the longitudinal end of the sleeve 22 (the area corresponding to the end of the magnet roller 21) with an adhesive. The sticking portion had a width of 25 mm outward from a position 6 mm inside the longitudinal end of the magnetic brush. The electrode sleeve used was an aluminum sleeve having an outer diameter of 16 mm and containing a magnet roller. This is referred to as an electrode sleeve 1.

(Electrode Sleeve Manufacturing Example 2) Based on FIG.
A sleeve-like material 223 made of aluminum was fixed to the electrode sleeve as an end float electrode portion via an insulating spacer 222 made of Teflon resin. The insulating spacer has a width of 6 mm and is located inside the longitudinal end of the magnetic brush. This is referred to as an electrode sleeve 2.

(Electrode Sleeve Production Example 3) The surface of the polyester sheet (25 mm width) of Electrode Sleeve Production Example 1 was coated with a urethane resin in which carbon black was dispersed, and a float electrode portion was produced (FIG. 5). This is referred to as an electrode sleeve 3.

(Electrode Sleeve Manufacturing Example 4) The float electrode portion of the electrode sleeve manufacturing example 2 was grounded as shown in FIG.
Further, a polycarbonate resin was used as the insulating spacer instead of the Teflon resin. This is the electrode sleeve 4
And

(Electrode Sleeve Manufacturing Example 5) The float electrode portion of the electrode sleeve manufacturing example 3 was grounded as shown in FIG.
This is an electrode sleeve 5.

(Electrode Sleeve Manufacturing Example 6) Electrode Sleeve 1
The electrode sleeve 6 is not subjected to the edge treatment.

[Production Example of Photoreceptor] (Production Example 1 of Photoreceptor) The photoreceptor is a photoreceptor using an organic photoconductive substance for negative charging, and the following layers are provided on an aluminum cylinder of φ30 mm. Was.

The first layer is a conductive particle-dispersed resin layer having a thickness of about 20 μm, which is provided to smooth defects of the aluminum cylinder and to prevent the occurrence of moire due to the reflection of laser exposure. It is.

The second layer is a positive charge injection preventing layer (undercoat layer), which serves to prevent positive charges injected from the aluminum support from canceling out negative charges charged on the surface of the photoreceptor. 10 ⁶ Ωc with methylated nylon
This is a middle resistance layer having a thickness of about 1 μm, the resistance of which is adjusted to about m.

The third layer is a charge generation layer having a thickness of about 0.3 μm in which a disazo pigment is dispersed in a resin, and generates a positive / negative charge pair by receiving laser exposure.

The fourth layer is a charge transport layer, a layer having a thickness of about 25 μm 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. This is designated as Photoconductor 1.

(Example 2 of photoreceptor production) Based on FIG.
A conductive resin of 0 mm was coated to a thickness of 25 μm. As the conductive resin, one obtained by dispersing carbon black in an acrylic resin was used. This is designated as Photoconductor 2.

(Photoreceptor Production Example 3)
As a charge injection layer on the surface of the layer, a layer was formed in which ultrafine SnO ₂ particles and, further, tetrafluoroethylene resin particles having a particle size of about 0.25 μm were dispersed in a photocurable acrylic resin.

Specifically, antimony-doped and low-resistance SnO ₂ particles having a particle size of about 0.03 μm and having a particle size of 100% by weight with respect to the resin, 20% by weight of ethylene tetrafluoride resin particles, and a dispersant were used. 1.2% by weight was dispersed. The coating liquid thus prepared is spray-coated to a thickness of about 2.
It was coated to 5 μm to form a charge injection layer.

As a result, the volume resistivity of the photoreceptor surface layer exceeded 1 × 10 ¹⁵ Ωcm in the case of the charge transporting layer alone, whereas the resistance of the photoreceptor surface became 3 × 10 ¹² Ωcm. This is designated as Photoconductor 3.

(Photoreceptor Production Example 4) Based on FIG. 9, the layer 27 including the charge injection layer of the photoreceptor 3 is formed 6 mm inward from a position corresponding to both ends in the longitudinal direction of the magnetic brush. As an insulating layer, the polycarbonate layer 28 (100
μm), and a polycarbonate resin layer in which conductive tin oxide was dispersed was provided as a float electrode on this surface. The cylinder in the end area is polished and the outer diameter of the center (φ
30) smaller by 1 mm. This is designated as photoconductor 4.

(Photoreceptor Production Example 5) A photoreceptor was produced in the same manner as in Photoreceptor Production Example 3, except that the tetrafluoroethylene resin particles and the dispersant were not dispersed in the charge injection layer. The volume resistance value of this photoreceptor surface layer was 1 × 10 ¹² Ωcm.
This is designated as Photoconductor 5.

(Photoreceptor Production Example 6) φ3 with mirror finish
A blocking layer, a photoconductive layer, and a surface layer were formed on a 0-mm aluminum cylinder by a glow discharge method to produce an amorphous silicon photoreceptor.

First, the reaction chamber was evacuated to about 5 × 10 ⁻³ Pa, and then various gases of SiH ₄ , B ₂ , H ₆ , NO and H ₂ were applied to the surface of the aluminum cylinder adjusted to 250 ° C. It was sent to the reaction chamber by a flow method. When the internal pressure reached about 30 Pa, glow discharge was generated to form a 5 μm blocking layer.

Next, Si is formed in the same manner as in the formation of the blocking layer.
Using H ₄ and H ₂ gas, a photoconductive layer having a thickness of 20 μm was formed under an internal pressure condition of about 50 Pa.

Further, a glow discharge was performed using SiH ₄ , CH ₄ and H ₂ gas under an internal pressure condition of about 60 Pa to form a surface layer made of Si and C with a thickness of 0.5 μm. The body was made. The surface resistance of the photoreceptor is 8 × 10 ¹² Ωcm. This is referred to as a photoconductor 6.

(Photoconductor Production Example 7) Based on FIG. 9, the photosensitive member 6 has a width 1 at a position corresponding to both longitudinal ends of the magnetic brush.
A copper evaporated film having a thickness of 5 mm and a thickness of 0.4 μm was formed. This is referred to as a photoreceptor 7.

(Photoreceptor Production Example 8) Photoreceptor production example except that antimony-doped and low-resistance SnO ₂ particles having a particle size of about 0.03 μm were dispersed at 300% by weight in a photocurable acrylic resin. A photoconductor was prepared in the same manner as in No. 3. The volume resistance value of the photoconductor surface layer was 2 × 10 ⁷ Ωcm. This is designated as photoconductor 8.

(Toner Production Example) 100 parts by weight of polyester resin, the same applies hereinafter) 3 parts of carbon black 4 parts of chromium compound of di-tert-butylsalicylic acid

The above materials were sufficiently premixed with a Henschel mixer, melt-kneaded with a twin-screw extruder, and mixed.
After cooling, coarsely pulverized to about 1 mm using a hammer mill,
Next, it was pulverized by a pulverizer using an air jet method. 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.

[0155]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The electrophotographic printer used in this embodiment will be described with reference to FIG. Process speed is 1
The photosensitive member 1 was manufactured in the example of manufacturing the photosensitive member.

The charging means 2 has a non-magnetic aluminum conductive sleeve (φ16 mm) whose surface is blasted for raising ears as a magnetic brush (charging member), and a magnetic flux density contained therein of 0.1 T (tesla). ) Magnet roll. The gap between the conductive sleeve and the photoreceptor 1 was about 500 μm, and the magnetic particles obtained in the magnetic particle production example were coated on the sleeve so that a charging nip having a width of about 5 mm was formed between the sleeve and the photoreceptor. In addition, the magnet roll is fixed, and the surface of the sleeve is rotated at a speed 1.5 times the peripheral speed of the surface of the photoreceptor in the opposite direction at the opposed position so that the photoreceptor and the magnetic brush are uniformly contacted. did.

When there is no peripheral speed difference between the magnetic brush and the photosensitive member, the magnetic brush itself has no physical restoring force, and the magnetic brush is pushed away due to deflection or eccentricity of the photosensitive member. The charging nip cannot easily be secured,
Poor charging may occur. For this reason, it is preferable to always apply a new magnetic brush surface. In this embodiment, charging is performed by using a charging device that is rotated 1.5 times faster in the opposite direction.

Next, image exposure is performed in the exposure section. The light used is laser light or the like, which is exposure light 3 from a laser diode that has been intensity-modulated according to an image signal, and the photosensitive member is irradiated with laser light by scanning using a polygon mirror to form an electrostatic charge image. I do.

Next, two-component development is performed using the toner of the toner production example.

The developing carrier has an average particle diameter of 35 μm.
This is a Cu—Zn ferrite carrier whose surface is coated with a silicone resin. The toner used is the 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 was provided on the toner carrier 4 containing a magnet with a gap of 500 μm for controlling the coating layer of the developer, and the developer was coated on the toner carrier. Was controlled.

In this state, a two-component phenomenon is caused between the toner carrier and the photosensitive member by applying a voltage obtained by superimposing an AC voltage having a frequency of 2,000 Hz and a peak-to-peak voltage of 2.0 KV on a DC voltage of -500 V. Was. The rotation speed of the stainless steel sleeve, which is the toner carrier, was set to be twice that of the photoconductor in the same direction at the portion facing the photoconductor.

The image developed with toner in this manner is
Next, it is transferred to the transfer material 5. As the transfer means, a transfer roller 6 having a medium resistance is used. In this embodiment, the roller resistance value is 5
The transfer was carried out by applying a DC voltage of +2,500 V using a capacitor of × 10 ⁸ Ω.

The print image on which the toner image has been transferred onto the transfer material is thereafter fixed by the heat fixing roller 7, and
Emitted outside the machine. The toner not transferred is scraped off from the surface of the photoconductor by the cleaning blade 8.

The following evaluation was performed using such an electrophotographic apparatus. The voltage applied to the electrode sleeve is superimposed by AC (DC-700 V, 1.6 kVpp), superimposed by weak AC (DC-700 V, 1.0 kVpp), and injected DC (DC
-700 V). However, photoconductors 6 and 7
, The DC component was set to + 500V.

Evaluation 1 Image-printing durability (5,000 sheets and 10,000 sheets) using the magnetic toner prepared in the toner production example.
0), and the leakage of the magnetic particles and the adhesion to the drum during the running were observed. The evaluation levels are four levels shown in Table 2.

[0167]

[Table 2]

Evaluation 2 The surface of the end of the electrode sleeve or the end of the photosensitive member before and after the endurance was photographed under an enlarged scale (electron microscope), and the abrasion and peeling of the coating resin layer or the float electrode were evaluated. The evaluation levels are four levels shown in Table 3.

[0169]

[Table 3]

Table 4 shows the results.

(Examples 1 to 10) Evaluations 1 and 2 were examined using combinations of the resin-coated magnetic particles, the electrode sleeve, the photosensitive member, and the applied voltage shown in Table 4. Table 4 shows the results
Shown in

[0172]

[Table 4]

(Examples 11 to 15) Evaluations 1 and 2 were examined using the photosensitive members subjected to the edge treatment in combinations shown in Table 5. Table 5 shows the results.

[0174]

[Table 5]

(Examples 16 to 20) The process speed was changed from 100 mm / sec to 150 mm / sec.
In the combinations shown in Table 6, evaluation 1 and evaluation 2 were examined. Table 6 shows the results.

[0176]

[Table 6]

As described above, according to the present invention, the leakage of the magnetic particles and the adhesion to the drum which deteriorate the image quality were not observed, and the good chargeability was maintained. At the same time, the adhesion of the coating resin was good and the wear resistance was excellent. Furthermore, it was possible to prevent durable wear of the end processing section.

Among them, magnetic particles directly polymerized and coated with a polyolefin having two peaks have a process speed of 15
Excellent abrasion resistance was exhibited even at endurance speeding up to 0 mm / sec.

(Examples 21 to 27) Evaluations 1 and 2 were examined in the same manner as in Example 1 with the combinations of the resin-coated magnetic particles, the electrode sleeve, the photosensitive member, and the applied voltage shown in Table 7. Table 7 shows the results.

[0180]

[Table 7]

(Examples 28 to 30) Evaluations 1 and 2 were carried out using the photoreceptors subjected to the edge treatment in the combinations shown in Table 8. Table 8 shows the results.

[0182]

[Table 8]

According to the present invention, no leakage of the magnetic particles and the adhesion to the drum which deteriorate the image quality were observed, and the good chargeability was maintained. At the same time, the adhesion of the coating resin was good, and the wear resistance was also excellent.

Example 31 The same electrophotographic apparatus as in Example 1 was used. However, the peripheral speed of the surface of the electrode sleeve is set to twice the peripheral speed of the surface of the photoreceptor using the electrode sleeve 6, and the magnetic particles used are the magnetic particles 8.
Then, the photosensitive member was designated as photosensitive member 3. The evaluation is as follows.

In the present embodiment, first, using the charging device described in this embodiment, idle rotation was evaluated for the purpose of promoting spent, and then evaluation was performed using the printer having the above-described configuration.

The idle rotation evaluation was performed as follows.

In the charging device described in this embodiment, the toner was mixed at a ratio of 1 part of the toner of the toner production example to 100 parts by weight of the magnetic particles of the magnetic particles 8, and this mixture was obtained in the photoconductor production example 3. The photosensitive member was coated on the sleeve so that a charging nip having a width of about 5 mm was formed between the photosensitive member and the photosensitive member. Next, the photosensitive member was brought into contact with the photosensitive member, and in this state, the photosensitive member was stopped, and was rotated idle for 10 hours at the speed described in this embodiment.

Next, a DC voltage of -700 V was applied to
In the case of No. 4, only 50 sheets were washed with solid white, and the toner was discharged.
Thereafter, the photoreceptor was replaced with an unused one, and evaluated according to Evaluation 3. The surface of the magnetic particles was evaluated according to Evaluation 4.

Subsequently, evaluation was made using the printer described in this example. The charging device used for the idling evaluation was used as it was, and a voltage of -700 V was applied.
%, The surface potential of the photoreceptor, Evaluation 3, Evaluation 4 and Evaluation 5 were evaluated in the initial stage, and Evaluation 3, Evaluation 4 and Evaluation 5 were evaluated after the durability of 4000 sheets. Also,
Apart from these evaluations, the potential of the charging device was measured without mixing the toner. Further, a durability test was advanced and evaluated according to Evaluation 1.

Evaluation 3 As an evaluation of the charging device, a DC voltage of -700 V was applied to the charging member, and the rise of the surface potential of the photosensitive member which was 0 V (the potential in the first rotation of the photosensitive member) was measured.

Evaluation 4 The surface of the magnetic particles was observed with a scanning electron microscope, the state of toner spent was observed and evaluated as follows.

〇 = Spent is hardly observed. Δ = Spent is partially observed. X = Spent is observed on most of the surface.

Evaluation 5 Images obtained when the applied voltage was -700 V were evaluated. In the A4 vertical image, an image was printed in which one round of the photoreceptor (about 94 mm in this embodiment) was solid black (low potential) and immediately thereafter was solid white (high potential), and the charged ghost of the obtained image was evaluated. I went by.

If a charging failure occurs, the potential sufficiently rises immediately after solid black, and appears as fog in reversal development. The degree of fog was evaluated according to the following evaluation items. Fog is a reflection type densitometer (TOKYO DENSH
Oku Corporation, REFLECTOMETER MOD
EL TC-6DS), and the worst value of the reflection density of the white background after printing was Ds, the average reflection density of the paper before printing was Dr, and Ds-Dr was the fog amount.

〇 = good (less than 3%) Δ = slight fog generation (3% to 5%) × = impractical, fog image generation due to poor charging (more than 5%) The results are shown in Table 9.

(Example 32) An image was evaluated in the same manner as in Example 31 except that the magnetic particles were replaced with the magnetic particles 9. Table 9 shows the results.

(Example 33) An image was evaluated in the same manner as in Example 31 except that the magnetic particles were replaced with the magnetic particles 10. Table 9 shows the results.

Example 34 An image was evaluated in the same manner as in Example 31, except that the magnetic particles were replaced with the magnetic particles 11. Table 9 shows the results.

Example 35 An image was evaluated in the same manner as in Example 31, except that the magnetic particles were replaced with the magnetic particles 12. Table 9 shows the results.

Example 36 An image was evaluated in the same manner as in Example 31 except that the magnetic particles were replaced with the magnetic particles 13. Table 9 shows the results.

Example 37 An image was evaluated in the same manner as in Example 31, except that the photosensitive member was replaced with the photosensitive member 5. Table 9 shows the results.

Example 38 An image was evaluated in the same manner as in Example 31 except that the magnetic particles were replaced with the magnetic particles 22. Table 1 shows the results.

Example 39 An image was evaluated in the same manner as in Example 31, except that the magnetic particles were replaced with the magnetic particles 19. Table 9 shows the results.

Comparative Example 1 An image was evaluated in the same manner as in Example 31 except that the magnetic particles were replaced with the magnetic particles 16. Table 9 shows the results.

(Comparative Example 2) An image was evaluated in the same manner as in Example 31, except that the magnetic particles were replaced with the magnetic particles 21. Table 11 shows the results.

[0206]

[Table 9]

Example 40 The magnetic particles were replaced with the magnetic particles 14 and the photoreceptor was replaced with the photoreceptor 1. The voltage applied to the charging member during evaluation and endurance was changed to a DC voltage of -700 V, a frequency of 1000 Hz, and a peak-to-peak voltage of 1. The evaluation was performed in the same manner as in Example 31 except that a voltage in which an AC voltage of 0.6 KV was superimposed was applied, and a weight was put inside the photoreceptor so that no AC charging noise was generated. Table 10 shows the results.

(Example 41) An image was evaluated in the same manner as in Example 31 except that the magnetic particles were replaced with the magnetic particles 20. Table 10 shows the results.

(Comparative Example 3) An image was evaluated in the same manner as in Example 31, except that the magnetic particles were replaced with the magnetic particles 18. However, when the image was checked at the beginning, a leak image occurred.

Comparative Example 4 Image evaluation was performed in the same manner as in Example 40 except that the magnetic particles were replaced with the magnetic particles 15. However, since the initial potential was only charged to -580 V, it was made impractical.

(Comparative Example 5) An image was evaluated in the same manner as in Example 31 except that the magnetic particles were changed to the magnetic particles 17. Table 10 shows the results. After idling, the charged potential decreased, and when observed under a microscope, toner spent was observed.

[0212]

[Table 10]

[0213]

As described above, according to the present invention, it is possible to maintain good charging characteristics over a long period of time, and it is possible to maintain good charging characteristics over a long period of time. The charging device and the electrophotographic device which can be provided.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of a schematic configuration of an electrophotographic apparatus having a charging device of the present invention.

FIG. 2 is a cross-sectional view of a configuration of an apparatus for measuring a volume resistance value of magnetic particles according to the present invention.

FIG. 3 is a diagram illustrating an example of end processing.

FIG. 4 is a diagram illustrating an example of end processing.

FIG. 5 is a diagram illustrating an example of end processing.

FIG. 6 is a diagram illustrating an example of end processing.

FIG. 7 is a diagram illustrating an example of end processing.

FIG. 8 is a diagram illustrating an example of end processing.

FIG. 9 is a diagram illustrating an example of end processing.

FIG. 10 is a diagram illustrating an example of end processing.

 ──────────────────────────────────────────────────続 き Continuation of the front page (31) Priority claim number Japanese Patent Application No. 8-100966 (32) Priority date Hei 8 (1996) April 23 (33) Priority claim country Japan (JP) (72) Inventor Shuichi Aida 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Kikatsu Mizoe 3-30-2 Shimomaruko 3-chome, Ota-ku, Tokyo In Canon Inc. (72) Motoshi Hisaki Inventor (72) Inventor Yuji Ishihara 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (18)

[Claims] 1. A charging device comprising an electrophotographic photoreceptor and magnetic particles, the charging device having a charging member that is disposed in contact with the electrophotographic photoreceptor and charges the electrophotographic photoreceptor by applying a voltage, A charging device, wherein the magnetic particles have a surface layer containing a polyolefin resin having a weight average molecular weight of 10,000 or more, and have a volume resistance of 1 × 10 ⁴ to 1 × 10 ¹¹ Ωcm. . 2. The charging device according to claim 1, wherein the magnetic particles have a weight average molecular weight of 30,000 or more. 3. The charging device according to claim 2, wherein the magnetic particles have a weight average molecular weight of 50,000 or more. 4. The charging device according to claim 1, wherein the surface layer of the magnetic particles is formed by a direct polymerization method. 5. A charging member is carried on a conductive member, and a region of the conductive member corresponding to an end of the charging member or a region of the electrophotographic photosensitive member corresponding to an end of the charging member is insulative. The charging device according to claim 1, wherein the charging device has been subjected to a treatment or a conductive treatment. 6. The charging device according to claim 1, wherein the electrophotographic photosensitive member has a charge injection layer as a surface layer. 7. The charge injection layer is 1 × 10 ⁸ to 1 × 10 ¹⁵ Ω.
The charging device according to claim 1, wherein the charging device has a volume resistance of about 10 cm. 8. The charge injection layer is 1 × 10 ¹⁰ to 1 × 10 ¹⁴ Ω.
The charging device according to claim 7, which has a volume resistance value of about 10 cm. 9. The charge injection layer is 1 × 10 ¹² to 1 × 10 ¹⁴ Ω.
9. The charging device according to claim 8, which has a volume resistance of 10 cm. 10. An electrophotographic photosensitive member, comprising magnetic particles,
An electrophotographic apparatus having a charging member, an exposure unit, a developing unit, and a transfer unit, which is disposed in contact with the electrophotographic photosensitive member and charges the electrophotographic photosensitive member when a voltage is applied, wherein the magnetic particles are An electrophotographic apparatus having a surface layer containing a polyolefin resin having a weight average molecular weight of 000 or more, and having a volume resistivity of 1 × 10 ⁴ to 1 × 10 ¹¹ Ωcm. 11. The electrophotographic apparatus according to claim 10, wherein the magnetic particles have a weight average molecular weight of 30,000 or more. 12. The electrophotographic apparatus according to claim 11, wherein the magnetic particles have a weight average molecular weight of 50,000 or more. 13. The electrophotographic apparatus according to claim 10, wherein the surface layer of the magnetic particles is formed by a direct polymerization method. 14. A charging member carried on a conductive member,
2. The electroconductive member according to claim 1, wherein a region corresponding to an end of the charging member or a region of the electrophotographic photosensitive member corresponding to an end of the charging member is subjected to an insulating treatment or a conductive treatment.
3. The electrophotographic apparatus according to any one of 3. 15. The electrophotographic apparatus according to claim 10, wherein the electrophotographic photosensitive member has a charge injection layer as a surface layer. 16. The charge injection layer is 1 × 10 ⁸ to 1 × 10 ^15.
The electrophotographic apparatus according to any one of claims 10 to 15, which has a volume resistance value of Ωcm. 17. The method according to claim 1, wherein the charge injection layer is 1 × 10 ¹⁰ to 1 × 10 ^14.
17. The electrophotographic apparatus according to claim 16, which has a volume resistance of Ωcm. 18. The method according to claim 1, wherein the charge injection layer is 1 × 10 ¹² to 1 × 10 ^14.
The electrophotographic apparatus according to claim 17, which has a volume resistance of Ωcm.