JPH08272183A - Electrophotographic charging device - Google Patents

Abstract

PURPOSE: To provide an electrophotographic charging device which gives uniform electrostatic charge on the surface of a photoreceptor and produces a stable image. CONSTITUTION: An electrophotographic charging device includes a photoreceptor 11 having a photosensitive layer on an electroconductive support and a contact type charging member 12 which performs electrostatic charging of the photosensitive element 11 by impressing a voltage upon contacting with the photosensitive element 11, wherein the photosensitive element 11 has an electric charge implant layer located the most apart from the support, and the implant layer has a volume resistivity of 10<8> Ωcm-10<15> Ωcm, and the member 12 is in the form of magnetic particles to which electron conjugate polymer is attached, and the volume resistivity of these magnetic partcles lies between 10<4> Ωcm-10<10> Ωcm.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic apparatus having an electrophotographic photosensitive member and a member for contact-charging the photosensitive member, and charging the photosensitive member by applying a voltage from the contact charging member. The present invention relates to an electrophotographic charging device used.

[0002]

2. Description of the Related Art Conventionally, a number of electrophotographic methods are known, but generally, a photoconductive material is used to form an electric latent image on a photoconductor by various means, and then the electrophotographic image is formed. The latent image is developed with toner to form a visible image, and if necessary, the toner image is transferred to a transfer material such as paper, and then the toner image is fixed on the transfer material by heat or pressure to obtain a copy. It is a thing. Further, the toner particles remaining on the photoconductor without being transferred onto the transfer material are removed from the photoconductor by the 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.
It is installed in copiers, printers, and facsimiles. As a charging means in such an electrophotographic method, a means utilizing a corona discharge has been used, but it is necessary to provide a filter because a large amount of ozone is generated, so that the apparatus becomes large or running. There were problems such as increased costs.

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 photosensitive member 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 in which ozone generation is suppressed as much as possible by forming such a discharge has been developed. Among them, a roller charging method using a charging roller as a charging member is particularly preferably used from the viewpoint of charging stability.

Specifically, since charging is performed by discharging from the charging member to the body to be charged, the charging is started by applying a voltage equal to or higher than a certain threshold voltage. For example, when the charging roller is brought into contact with an OPC photosensitive member having a photosensitive layer thickness of 25 μm, the surface potential of the photosensitive member begins to rise when a voltage of about 640 V or higher is applied, and thereafter, the voltage is applied. The surface potential of the photoconductor increases linearly with a slope of 1 with respect to the voltage. Hereinafter, this threshold voltage is defined as the charging start voltage V _th .
That is, in order to obtain the photoreceptor surface potential V _d , the charging roller needs a DC voltage of V _d + V _th , which is higher than the required DC voltage. Further, since the resistance value of the contact charging member fluctuates due to environmental fluctuations, it is difficult to set the potential of the photoconductor to a desired value.

Therefore, as disclosed in Japanese Patent Laid-Open No. 63-149669, the peak-to-peak voltage of 2 × V _th or more is added to the DC voltage corresponding to the desired V _d in order to further uniformize the charging. An AC charging method is used in which a voltage superposed with an AC component having is applied to the contact charging member. This is AC
By is intended for the purpose of Shi effects become potentials, the potential of the member to be charged converges to V _d is the central peak of the AC voltage, it will not be affected by disturbance such as environmental.

However, even in such a contact charging device, since the essential charging mechanism uses the discharge phenomenon from the charging member to the photosensitive member, the voltage required for charging as described above. Is required to have a value equal to or higher than the surface potential of the photoconductor. When AC charging is performed for uniform charging, vibration and noise of the charging member and the photoconductor due to the electric field of the AC voltage (hereinafter referred to as AC charging sound) are generated, and the surface of the photoconductor is discharged. Deterioration and the like became noticeable, which was a new problem.

On the other hand, as disclosed in Japanese Patent Laid-Open No. 61-57958, there is an image forming method in which a photosensitive member having a conductive protective film is charged with conductive fine particles. According to this, a photoconductor having a semiconductive protective film having a resistance of 10 ⁷ to 10 ¹³ Ωcm is used as the photoconductor, and the photoconductor is charged by using conductive fine particles having a resistance of 10 ¹⁰ Ωcm or less. It is described that, by doing so, it is possible to uniformly charge the photosensitive member by discharge without injecting charges into the photosensitive layer and to perform good image reproduction. According to this method, it is possible to prevent vibration, noise, etc., which are problems in AC charging. However, since charging is performed by electric discharge, deterioration of the surface of the photoconductor due to electric discharge still occurs, and a high voltage power source is also required.

Therefore, there has been a demand for charging by directly injecting charges into the photoconductor.

A method for performing contact injection charging by applying a voltage to a contact charging member such as a charging roller, a charging brush, a charging magnetic brush, and injecting a charge into a trap level on the surface of the photosensitive member is described in Japan Hardcopy 1992. P28
Although it is described in "Contact charging characteristics using a conductive roller" of 7, etc., these methods perform injection charging to a dark insulating photoconductor with a low resistance charging member to which a voltage is applied. In this method, the resistance value of the charging member is sufficiently low, and the material (conducting filler, etc.) that makes the charging member conductive is sufficiently exposed on the surface. For this reason, in the above-mentioned documents, it is said that the charging member is preferably an aluminum foil or an ion-conducting charging member having a sufficiently low resistance value in a high humidity environment. According to the study by the present applicants, the resistance value of the charging member capable of sufficiently injecting charge into the photoconductor is 1 × 10 ³ Ωcm or less, and above this, a difference occurs between the applied voltage and the charging potential. At the beginning, it is known that a problem occurs in the convergence of the charging potential.

However, when such a charging member having a low resistance value is actually used, scratches generated on the surface of the photosensitive member,
Excessive leakage current flows from the contact charging member to the pinhole and the like, resulting in defective charging around the pinhole, enlargement of the pinhole, and electrical breakdown of the charging member.

In order to prevent this, it is necessary to set the resistance value of the charging member to about 1 × 10 ⁴ Ω or more. However, the charging member having this resistance value has the property of injecting charge into the photosensitive member as described above. Will decrease, resulting in a contradiction that charging is not performed.

Therefore, the problems as described above in the contact type charging device or the image forming method using the charging device are solved, that is, good charge injection can be achieved without using the low resistance contact charging member. It is desirable to be able to simultaneously achieve both the antistatic property and the contradictory property of pinhole leak on the charged body that could not be prevented by the low resistance contact charging member, and for that purpose, This is achieved by using magnetic particles whose resistance is adjusted as a contact charging member. Further, the magnetic particles must have a magnetic force of a certain level or more, and if the magnetic force is weak, it becomes difficult to hold the magnetic particles on the charging member, and the particles adhere to the photoconductor, resulting in image defects. Will occur.

That is, the magnetic particles must be adjusted so as to satisfy both the desired resistance value and magnetic force.

However, when the resistance value of the magnetic particles is adjusted, the magnetic force may be reduced, and when the magnetic force is increased, the resistance value may be reduced. Therefore, there has been a demand for a method capable of easily and stably adjusting the characteristics of magnetic particles to an arbitrary resistance value and an arbitrary magnetic characteristic.
Furthermore, it is necessary to prevent changes in the resistance value and magnetic force due to so-called "rust", especially in a high-humidity environment, by long-term use.

[0016]

SUMMARY OF THE INVENTION An object of the present invention is to have a contact charging member composed of an electrophotographic photosensitive member and magnetic particles for injecting and charging the photosensitive member, and applying a voltage to the photosensitive member from the charging member. In order to prevent good and uniform charging in the electrophotographic charging device that charges the photosensitive member, and to prevent current destruction of the charging member and the photosensitive member due to current concentration on defects such as pinholes generated on the photosensitive member. Another object of the present invention is to provide an electrophotographic charging device having a contact charging member having a uniform and desired resistance without uneven resistance.

[0017]

That is, the present invention relates to an electrophotographic photosensitive member having a photosensitive layer on a conductive support, and a photosensitive member by contacting a charging member with the photosensitive member and applying a voltage thereto. In an electrophotographic charging device having a contact charging member for charging, the photoconductor has a charge injection layer farthest from the support, and the charge injection layer is 10 ⁸ Ωcm-10.
^An electron having a volume resistance value of ¹⁵ Ωcm, wherein the contact charging member is a magnetic particle to which an electron-conjugated polymer is added, and the magnetic particle has a volume resistance value of 10 ⁴ Ωcm to ^{10 10} Ωcm. It is a photographic charging device.

In the present invention, it is possible to charge the photosensitive member potential to 90% or more of the voltage applied to the charging member.

The present invention will be described in detail below.

The magnetic particles used in the contact charging member exhibit conductivity by imparting an electron conjugated polymer.

Examples of the electron-conjugated polymer of the present invention include polypyrrole, polythiophene, polyquinoline, polyphenylene, polynaphthylene, polyacetylene, polyphenylene sulfide, polyaniline, polyphenylene vinylene, and pyrrole or thiophene.
Examples thereof include polymers of derivatives in which the position is substituted with a C ₁ to C ₁₂ alkyl group, and these can be used alone or in combination of two or more kinds. Among them, polypyrrole and polythiophene having a heterocycle in the polymer molecule, polyaniline having a nitrogen atom and an allocyclic ring, and derivatives thereof are particularly preferable because they have excellent high voltage resistance as a charging member.

The magnetic particles of the present invention can be coated with a conductive polymer by applying a polymerization catalyst to the surface of the particles and then contacting them with a monomer which is a precursor of the conductive polymer. Here, the monomers can be contacted in a vapor or solution state. In the case of a soluble conductive polymer, magnetic particles can be impregnated with a polymer solution dissolved in a suitable solvent, or conductivity can be imparted directly to the magnetic particles by means such as spray coating. A soluble conductive polymer solution dissolved in a suitable solvent can form a conductive layer made of a conductive polymer only by removing the solvent without using a binder. Further, unlike the case where the magnetic particles are coated with a resin in which a conductive filler is dispersed, magnetic particles having a uniform resistance value can be obtained without controlling the thickness of the coating layer.

Further, since the surface of the magnetic particles is subjected to the conductive treatment as described above to form a very thin coat layer to adjust the conductivity, the magnetic characteristics of the magnetic particles are measured before and after the conductive treatment. As a result, there is no change, and the conductive treatment can be performed without impairing the magnetic properties of the magnetic particles.

Further, by treating the surface of the magnetic particle as described above, the surface of the magnetic particle is not exposed to the outside air, so that it is possible to prevent the magnetic particle from being oxidized by being left unused for a long period of time. It is possible to prevent changes in resistance and magnetic characteristics due to so-called "rust".

To give a specific example, when polypyrrole is added, a 20 mass% ferric chloride aqueous solution (oxidation catalyst) is used.
After immersing magnetic particles therein to adsorb iron chloride, the magnetic particles are set in a closed container filled with pyrrole monomer vapor. Vapor-phase polymerization of pyrrole proceeds on the surface of the magnetic particles to produce conductive polypyrrole. At this time, the pyrrole monomer concentration,
Arbitrary conductivity can be easily and stably obtained by adjusting the gas phase polymerization time or the catalyst application amount. Next, sufficient washing is performed and heat drying is performed to remove unreacted monomers and water. Further, in the catalytic reaction of the pyrrole monomer, the magnetic particles to which the catalyst is added may be directly immersed in the liquid monomer. In this case, the resistance value can be adjusted by diluting the liquid monomer with an appropriate solvent or the contact reaction time.

Examples of the soluble conductive polymer include polyaniline. Polyaniline can be polymerized by chemically oxidizing aniline in the presence of ammonium peroxodisulfate (oxidizer) and sulfuric acid (protic acid),
This is treated with aqueous ammonia to make it soluble. The solvent is
N-methyl-2-pyrrolidone (NMP) is suitable, but in addition, N, N-dimethylacetamide and N, N-
Dimethylformamide and the like can also be used. The magnetic particles can be made conductive by impregnating the magnetic particles with an NMP solution having a polymer concentration adjusted to about 1% to 10% and then drying. Further, the magnetic particles can be etched with an acid or alkaline solution or the surface of the particles can be modified with a coupling agent or the like for the purpose of facilitating adsorption of an oxidation catalyst and coating of a conductive polymer.

The contact charging member plays a role of injecting charges into the charge injection layer of the photosensitive member, and the charging current is concentrated on defects such as pinholes formed on the photosensitive member to prevent the charging member and the photosensitive member from being broken due to electric conduction. Must also have the role to play. If the resistance value of the magnetic particles of the contact charging member is less than 1 × 10 ⁴ Ωcm, pinhole leakage cannot be prevented, and if it exceeds 1 × 10 ¹⁰ Ωcm, the current required for charging cannot be passed. Therefore,
The resistance value of the magnetic particles used for the contact charging member is 1 × 10.
It should be in the range of ⁴ Ωcm to 1 × 10 ¹⁰ Ωcm. The resistance value is preferably in the range of 1 × 10 ⁴ Ωcm to 1 × 10 ⁸ Ωcm.

Further, the resistance value between the voltage application portion of the contact charging member using the magnetic particles and the portion in contact with the photosensitive member is 10
It is preferably in the range of ⁴ to 10 ¹⁰ Ω, more preferably in the range of 10 ⁴ to 10 ⁸ Ω.

Further, the average particle size of the magnetic particles is 5 to 200.
μm is preferred. If it is less than 5 μm, the magnetic brush is apt to adhere to the photoconductor, and if it is more than 200 μm, the density of the spikes of the magnetic brush on the sleeve cannot be made dense, and the charging property to the photoconductor is deteriorated. There is a tendency. More preferably 10 to 100 μm, and particularly preferably 15 to
It is 50 μm.

The average particle size of the whole is randomly extracted by an optical microscope or a scanning electron microscope, and 100 or more particles are extracted. The volume particle size distribution is calculated with the maximum chord length in the horizontal direction, and the average particle size is calculated with 50% of the average particle size. Particle size may be used, or laser diffraction particle size distribution measuring device HEROS
(Manufactured by JEOL Ltd.), the range of 0.05 μm to 200 μm is divided into 32 logarithms and measured, and the 50% average particle size may be used as the average particle size.

The magnetic particles according to the present invention are magnetically erected, and the magnetic brush is brought into contact with the photosensitive member to be charged, so that the material exhibits ferromagnetism such as iron, cobalt and nickel. Alloys or compounds containing elements are used. The volume resistance value is 1 × from the viewpoint of preventing image defects due to pinhole leak.
Magnetic particles having a resistance of 10 ⁴ Ωcm or more must be used. Since the upper limit of the resistance can be adjusted by attaching the electron-conjugated polymer, it is not necessary to set the upper limit. Therefore, those whose volume resistance value has been adjusted by performing oxidation treatment, reduction treatment, etc., such as composition-adjusted ferrite, hydrogen reduction-treated Zn-Cu ferrite, and oxidation-treated magnetite, are used.

The photoreceptor of the present invention is a support.
In the farthest layer, as described above,
Volume resistance value to satisfy the condition that does not cause image deletion
Is 1 × 10⁸ Ωcm ~ 1 x 10^FifteenVoltage in the range of Ωcm
A photoreceptor provided with a load injection layer must be used. Hope
The volume resistance value is 1 × 10 from the viewpoint of image deletion. ¹¹
Ωcm ~ 1 x 10¹⁴Ωcm, especially environmental change of volume resistance
Considering movement, etc., the volume resistance value is 1 × 10¹²Ωcm ~ 1
× 10¹⁴It is desirable to use one having an Ωcm. 1 × 10
^TenIf it is less than Ωcm, the charged electric charge is retained in the surface direction in high humidity
Image deletion occurs because it is not performed, and 1 × 10^FifteenOver Ωcm
Then, the charged electric charge from the charging member can be sufficiently injected and retained.
There is a tendency that defects will result in poor charging. Such a functional layer
Inject from charging member by providing
Plays a role of retaining the charged electric charge that is generated, and during light exposure
It also plays the role of releasing this charge to the photoconductor support,
Reduce the rank. Further, the charging member and the photosensitive member according to the present invention
By taking this kind of configuration for the body,
Starting voltage V_thIs small, and the photoconductor charging potential is applied to the charging member.
It is possible to converge to almost 90% or more of the voltage
Became. Here, the charge injection layer is an insulating vine.
Disperse an appropriate amount of light-transmissive and conductive particles in the
The feature is that it is made of a resistance material.

Here, the method for measuring the volume resistance value of the charge injection layer is the same as the method for measuring the charging member coating agent described above, and the charge injection layer is formed on a polyethylene terephthalate (PET) film having a conductive film deposited on its surface. And a volume resistance measuring device (4140 manufactured by Hewlett Packard).
B pAMASTER) at 23 ° C, 65% environment 1
The measurement was performed by applying a voltage of 00V.

This charge injection layer is composed of a metal vapor deposition film or a conductive powder resin dispersion film in which conductive fine particles are dispersed in a binder resin. The vapor deposition film is vapor-deposited, and the conductive powder resin dispersion film is dipping coating method or spray coating. A charge injection layer is formed by applying an appropriate coating method such as a coating method, a roll coat coating method, or a beam coat coating method. Further, it may be constituted by mixing or copolymerizing an insulating binder with a resin having a high light-transmitting ionic conductivity, or may be constituted by a single resin having a medium resistance and a photoconductivity. In the case of the conductive fine particle dispersed film, the added amount of the conductive fine particles is preferably within the range of 2 to 100 mass% with respect to the binder. If it is less than 2% by mass, it is difficult to obtain the desired volume resistance value, and
If it exceeds 0 mass%, the charge injection layer is easily scraped off due to the decrease in film strength, and the life of the photoreceptor is too short.

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

It is desirable that the charge injection layer contains lubricant powder. The reason is that the friction between the photoconductor and the injection charging member is reduced during charging, so that the charging nip is enlarged and the charging characteristics are improved. In particular, it is more preferable to use a fluorine-based resin, a silicone-based resin, or a polyolefin-based resin having a low critical surface tension as the lubricant powder. Particularly preferably, tetrafluoroethylene resin (PTF
E) is used. In this case, the amount of lubricant powder added is preferably 2 to 50 mass% with respect to the binder,
More preferably, it is 5 to 40 mass%. If it is less than 2% by mass, the amount of the lubricant powder is not sufficient, so that the charging property is not sufficiently improved, and if it exceeds 50% by mass, the resolution of the image and the sensitivity of the photosensitive member are significantly lowered. is there.

The constitution, material, manufacturing method and the like of the member used in the present invention will be exemplified below.

[Production Example of Toner] Styrene-butyl acrylate copolymer (copolymerization mass ratio 80:20) 100 parts by mass Magnetite 100 parts by mass Metal azo pigment 2 parts by mass Low molecular weight polypropylene 3 parts by mass The above materials are used in a Henschel mixer. After mixing in 130
The mixture was kneaded in an extruder set at ℃. The obtained kneaded product is cooled, and after roughly crushing with a cutter mill,
The mixture was finely pulverized with a jet mill using a jet stream and subjected to air classification to obtain a black fine powder (magnetic toner particles) having a weight average particle diameter of 7 μm. To 100 parts by mass of this black fine powder, 1.0 part by mass of silica hydrophobized with silicone oil was added and mixed with a Henschel mixer to obtain a magnetic toner.

[Photoreceptor Production Example 1] The photoreceptor is a negatively charged organic photoreceptor (hereinafter referred to as an OPC photoreceptor), and five functional layers are provided on a drum made of aluminum having a diameter of 30 mm.

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

The second layer is a positive charge injection preventing 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, and the amylan resin and methoxymethylation. By nylon 10 ⁶
It is a medium resistance layer having a thickness of about 1 μm whose resistance is adjusted to about Ωcm.

The third layer is a charge generating 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 subjected to laser exposure.

The fourth layer is a charge transport layer, which is a polycarbonate resin in which hydrazone is dispersed, and is a P-type semiconductor. Therefore, the negative charges charged on the surface of the photoconductor cannot move in this layer, and only the positive charges generated in the charge generation layer can be transported to the surface of the photoconductor.

The fifth layer is a charge injection layer, which is a feature of the present invention, and includes a photo-curable acrylic resin, SnO ₂ ultrafine particles, and a contact charging member and a photosensitive member for a longer contact time to achieve uniform charging. For this purpose, tetrafluoroethylene resin particles having a particle size of about 0.25 μm are dispersed. Specifically, antimony is doped to reduce the resistance, and the particle size is about 0.03.
70% by weight of SnO ₂ particles having a particle diameter of μm are dispersed in the resin, 30% by weight of tetrafluoroethylene resin particles and 1.2% by weight of a dispersant are dispersed therein.

The surface resistance of the photoconductor is 5 × 10 ¹² Ω.
It was cm.

[Photoreceptor Manufacturing Example 2] Fifth of Photoreceptor Manufacturing Example 1
A photoconductor was prepared in the same manner as in Photoconductor Production Example 1 except that the tetrafluoroethylene resin particles and the dispersant were not dispersed in the layer.

The surface resistance of the photoconductor is 2 × 10 ¹² Ω.
It was cm.

[Photoreceptor Manufacturing Example 3] Fifth of Photoreceptor Manufacturing Example 1
Photoreceptor Production Example 1 except that the layer was added with antimony-doped SnO ₂ particles having a resistance of about 0.03 μm dispersed in a photocurable acrylic resin in an amount of 120% by mass. A photoconductor was prepared in the same manner as in.

As a result, the resistance of the surface of the photoconductor is 6 × 1.
It was reduced to 0 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.

As an example of manufacturing a charging member, an example of a charging member made of magnetic particles having the surface of magnetic particles coated with an electron-conjugated polymer and exhibiting conductivity will be described. However, this does not limit the present invention in any way.

[Charging Member Manufacturing Example 1] Average particle diameter 25 μm,
8 × 10 ¹¹ Ωcm Zn—Cu ferrite is prepared.
The volume resistance value of the magnetic particles was measured using the cell shown in FIG. That is, it was determined by filling the cell A with magnetic particles, arranging the electrodes 1 and 2 so as to contact the filled magnetic particles, applying a voltage between the electrodes, and measuring the current flowing at that time. The measurement conditions are as follows: contact area S of the filled magnetic particles with the cell at 23 ° C. and 65% environment S = 2 cm ² , thickness d = 1 mm, upper electrode load 10 kg, applied voltage 100.
V.

The above Zn-Cu ferrite was washed with dilute hydrochloric acid and etched, and then impregnated with an aqueous ferric chloride solution (concentration: 30% by mass) as an oxidation catalyst and stirred for 20 minutes to allow ferric chloride to surface the ferrite. Adsorbed on. The ferrite was set in a closed container (23 ° C.) filled with pyrrole vapor (pyrrole solution purity 98%), brought into contact with pyrrole vapor (gas phase oxidative polymerization), and then thoroughly washed with pure water and ethanol. And dried to obtain the desired magnetic particles. When the magnetic particles were measured by the above-described resistance measuring method, it was 5 × 10 ⁶ Ωcm.

[Charging Member Manufacturing Example 2] Average particle diameter 40 μm,
2 × 10 ¹¹ Ωcm Zn—Cu ferrite is prepared.

The Zn-Cu ferrite was washed with dilute hydrochloric acid and etched, and then impregnated with an aqueous ferric chloride solution (concentration 20% by mass) as an oxidation catalyst and stirred for 25 minutes to allow ferric chloride to surface on the ferrite. Adsorbed on. The ferrite was set in a closed container (23 ° C.) filled with pyrrole vapor (pyrrole solution purity 98%), brought into contact with pyrrole vapor (gas phase oxidative polymerization), and then thoroughly washed with pure water and ethanol. And dried to obtain the desired magnetic particles. When the magnetic particles were measured by the above-mentioned resistance measuring method, it was 8 × 10 ⁵ Ωcm.

[Charging Member Manufacturing Example 3] Average particle diameter 40 μm,
Prepare 5 × 10 ¹¹ Ωcm strontium ferrite.

The above hard ferrite was washed with diluted hydrochloric acid and etched, and then impregnated with an aqueous ferric chloride solution (concentration: 20% by mass) as an oxidation catalyst and stirred for 40 minutes,
Ferric chloride was adsorbed on the ferrite surface. The ferrite was set in a closed container (23 ° C.) filled with pyrrole vapor (pyrrole solution purity 98%), brought into contact with pyrrole vapor (gas phase oxidative polymerization), and then thoroughly washed with pure water and ethanol. And dried to obtain the desired magnetic particles. When the magnetic particles were measured by the above-described resistance measuring method, it was 2 × 10 ⁵ Ωcm.

[Charging Member Manufacturing Example 4] First, aniline was added.
Ammonium luoxodisulfate (oxidizer) and sulfuric acid (prototype)
Acid) to give polyaniline. this
After washing polyaniline with ammonia water,
N-methyl-2-pyrrolidone so that the degree becomes 5% by mass
(NMP) and then toluenesulfonic acid NM
The P solution was mixed. Shown in this solution in Production Example 1 of charging member
Impregnated with Zn-Cu ferrite before conductive treatment
Coat the surface of the particles with aniline and dry the solution to obtain the desired
Conductive magnetic particles were obtained. This magnetic particle was measured by the resistance measurement described above.
3 × 10 when measured by a fixed method ⁶ Ω cm
Was.

[Charging Member Manufacturing Example 5] The ferrite particles of charging member manufacturing example 1 which were not subjected to the conductive treatment were used as the charging member.

[Charging Member Manufacturing Example 6] The ferrite particles of charging member manufacturing example 2 which were not subjected to the conductive treatment were used as the charging member.

[Charging Member Manufacturing Example 7] The ferrite particles of charging member manufacturing example 3 which were not subjected to the conductive treatment were used as the charging member.

[Charging Member Manufacturing Example 8] Average particle diameter 40 μm,
Using 5 × 10 ³ Ωcm of magnetite, the same conductive treatment as in Charging Member Production Example 1 was performed to obtain conductive magnetic particles. When the resistance of these magnetic particles was measured, it was 7 × 10 ² Ω.
It was cm.

[0065]

EXAMPLES Specific examples of the present invention are shown below, but the invention is not limited thereto. [Embodiment 1] The principle of charging using the above-mentioned photoreceptor and the contact charging member will be described. The present invention is a medium-resistance contact charging member for injecting charges into the surface of a photoconductor having a medium resistance surface resistance. In this embodiment, charges are injected into the trap potential of the surface material of the photoconductor. Instead, it is the principle of charging by charging the conductive particles of the charge injection layer.

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 support and conductive particles in the charge injection layer as both electrode plates. is there. 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 seems to be charged and charged to a uniform electric potential on a macroscopic scale, but in reality, a myriad of minute charged SnO ₂ covers the surface of the photoconductor. ing. Therefore, even if image exposure is performed with a laser, each SnO ₂ particle is electrically independent, so that an electrostatic latent image can be held.

Next, the electrophotographic printer used in the experiment of this embodiment will be described with reference to FIG. The process speed is 48 mm / sec, the photoconductor uses the photoconductor manufacturing example 1, the contact charging member is the coated magnetic particles prepared in the charging member manufacturing example 1, and a non-magnetic conductive sleeve for supporting the coated magnetic particles. It was constituted by a magnet roll contained therein, and the above coated magnetic particles were coated on the sleeve to a thickness of 1 mm to form a charging nip with a width of about 5 mm between the sleeve and the photoconductor. The gap between the magnetic particle holding sleeve and the photoconductor was about 500 μm. Also,
The magnet roll was fixed and rotated so that the surface of the sleeve rubs in the opposite direction at twice the peripheral speed of the surface of the photoconductor, so that the photoconductor and the magnetic brush come into uniform contact. If 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, so when the magnetic brush is pushed away by the deflection or eccentricity of the photoconductor, The nip of the magnetic brush cannot be secured, resulting in poor charging. For this reason, since it is necessary to constantly contact the surface of a new magnetic brush, in this embodiment, charging is performed using a charging device that rotates in the opposite direction at twice the speed.

Next, image exposure (image exposure) is performed in the exposure section.
Receive. Next, the laser light 13 from the laser diode whose intensity is modulated in accordance with the image signal is scanned by the polygon mirror to serve as an exposing means, and an electrostatic latent image is formed on the photoconductor.

Next, reversal development is performed using the magnetic one-component insulating toner of the manufacturing example. Diameter 16 including magnet
The non-magnetic sleeve 14 of mm is coated with the above-mentioned negative toner, and is fixed at a distance of 300 μm from the surface of the photoconductor, and is rotated at the same speed as the photoconductor drum to apply a voltage to the sleeve. The voltage is a DC voltage of -500V and a frequency of 20.
A rectangular AC voltage having a frequency of 00 Hz and a peak-to-peak voltage of 1200 V is superimposed, and jumping development is performed between the sleeve and the photoconductor.

The image visualized with the toner in this manner is then transferred to the transfer material 16. A transfer roller 15 having a medium resistance is used in the transfer section. In this embodiment, a roller having a resistance value of 5 × 10 ⁸ Ω was used, and a DC voltage of +2000 V was applied to transfer.

The print image on which the toner image has been transferred onto the transfer material is then fixed by the heat fixing roller 18,
It is discharged outside the aircraft. Further, the transfer residual toner is scraped off from the photosensitive drum by the cleaning blade 17 and prepared for the next image formation.

The surface potential of the photosensitive member and the image were evaluated in the printer having the above-mentioned constitution under the environment of 23 ° C./60% according to the following evaluation items. The results are shown in Table 1.

Evaluation 1) A DC voltage of -700 V was applied to the charging member, and the rise of the surface potential of the photoconductor, which was 0 V (potential on the first revolution of the photoconductor), was measured.

Evaluation 2) In the image evaluation, when a charging failure occurs in the reversal development, the history on the photosensitive member influences the charging. Therefore, in the A4 vertical image, one round of the photosensitive member (about 94 mm in this embodiment) is used. Image evaluation (charging ghost evaluation) was performed with a solid black image (potential low) and immediately after that a solid white (potential high). If a charging failure occurs, the potential does not rise sufficiently immediately after solid black and appears as a fog in reversal development. The degree of fogging was evaluated according to the following evaluation items. Fogging is a reflection densitometer (TOKYO D
ENSHOKU CO. , LTD REFLECTO
METER ODEL TC-6DS) measured using (a white portion reflection density worst value after printing D _s, before printing D _s -D _r when the reflection average density value was D _r of the paper
Was taken as the fogging amount).

◯: Good (5% or less) ×: Not practical, fog image generation due to poor charging (more than 5%)

Evaluation 3) The evaluation of the image deletion due to the lateral flow of the electric potential was carried out by a character image according to the following evaluation items.

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

Evaluation 4) Photoreceptor Using the photoreceptor of Production Example 1, the photosensitive layer on the photoreceptor was peeled off by about 1 mm ^2, and a defective photoreceptor in which the aluminum support was exposed was used.
An image was displayed by applying a DC voltage of 1 kV, and 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 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)

Example 2 The same evaluation as in Example 1 was carried out except that the magnetic particles of the contact charging member in Example 1 were used in the charging member manufacturing example 2.

Example 3 The same evaluation as in Example 1 was carried out except that the magnetic particles of the contact charging member in Example 1 were used in Manufacturing Example 3 for charging member.

Example 4 The same evaluation as in Example 1 was carried out except that the magnetic particles of the contact charging member in Example 1 were used in Manufacturing Example 4 for charging member.

Example 5 The same evaluation as in Example 1 was carried out except that the photosensitive member manufacturing example 2 was used as the photosensitive member in the example 1.

[Embodiment 6] Canon Copier, NP6
060 was prepared, the primary charging part was modified, and the charging member described below was installed. Further, the photoconductor is the photoconductor production example 4.
Was used.

The contact charging member uses the magnetic particles prepared in Manufacturing Example 1 of the charging member, and in order to hold the magnetic particles, the contact charging member is constituted by a non-magnetic conductive sleeve and a magnet roll contained therein. Was coated on the sleeve with a thickness of 1 mm to form a charging nip with a width of about 8 mm between the sleeve and the photosensitive member. The gap between the magnetic particle holding sleeve and the photoconductor was about 500 μm. Also, the magnet roll is fixed and rotated so that the sleeve surface rubs in the opposite direction at twice the peripheral speed of the photoconductor surface, and adjustment is made so that the photoconductor and the magnetic brush come into uniform contact. The same evaluation as in Example 1 was performed using the copying machine having the above configuration.

Here, the direct current voltage applied to the charging member of Evaluation 1 was +450 V, and the image evaluation of Evaluation 2 was also performed for the solid black image because the above copying machine uses the positive development method. (Poor charging appears as solid lines and spots on solid black.) Evaluation 4 was also performed by applying + 600V.

[Comparative Example 1] The same evaluation as in Example 1 was carried out except that the photosensitive member manufacturing example 3 was used as the photosensitive member in the example 1.

[Comparative Example 2] The same evaluation as in Example 1 was carried out except that the magnetic particles of the contact charging member in Example 1 were used in Manufacturing Example 5 for charging member.

Comparative Example 3 The same evaluation as in Example 1 was carried out except that the magnetic particles of the contact charging member in Example 1 were used in the charging member manufacturing example 6.

Comparative Example 4 The same evaluation as in Example 1 was carried out except that the magnetic particles of the contact charging member in Example 1 were used in the charging member manufacturing example 7.

[Comparative Example 5] The same evaluation as in Example 1 was carried out except that the magnetic particles of the contact charging member in Example 1 were used in Manufacturing Example 8 of Charging Member.

[0092]

[0093]

According to the present invention, a charge injection layer for injecting charges to the surface of a photoconductor is provided, and a contact charging member made of magnetic particles for contact-charging the photoconductor is provided. The particles have conductivity by adding a polymer, and the volume resistance value of the magnetic particles is 10 ⁴ Ω.
cm to ^{10 10} Ωcm, a uniform charge is applied to the surface of the photoconductor by an electrophotographic charging device that charges the photoconductor by applying a voltage from the contact charging member using the magnetic particles to the photoconductor, It became possible to obtain stable images.

[Brief description of drawings]

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

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

[Explanation of Codes] 1 Main electrode 2 Upper electrode 3 Insulator 4 Ammeter 5 Voltmeter 6 Constant voltage device 7 Magnetic particles 8 Guide ring 11 Photosensitive drum 12 Contact charging member 13 Exposure means 14 Developing device 15 Transfer roller 16 Transfer material 17 Cleaning blade 18 Heat fixing roller

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Nozomi Mizoe 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (7)

[Claims] 1. An electron having an electrophotographic photosensitive member having a photosensitive layer on a conductive support, and a contact charging member for charging the photosensitive member by bringing a charging member into contact with the photosensitive member and applying a voltage thereto. In a photographic charger, the photoreceptor has a charge injection layer furthest away from the support, the charge injection layer being 1
The magnetic particles having a volume resistance value of 0 ⁸ Ωcm to 10 ¹⁵ Ωcm, and the contact charging member is a magnetic particle provided with an electron-conjugated polymer, and the volume resistance value of the magnetic particles is 10 ⁴ Ωcm to ^{10 10} Ω.
An electrophotographic charging device characterized by being cm. 2. The electrophotographic charging device according to claim 1, wherein the electron-conjugated polymer contains a heterocycle or a homocycle with a nitrogen atom. 3. The magnetic particles are conductive magnetic particles obtained by polymerizing a conductive monomer on the particle surface in a gas phase.
Or the electrophotographic charging device according to 2. 4. The electrophotographic charging device according to claim 1, wherein a resistance value between a voltage application portion of the contact charging member and a portion in contact with the photosensitive member is 10 ⁴ to 10 ¹⁰ Ω. 5. The electrophotographic charging device according to claim 1, wherein the magnetic particles used in the contact charging member have an average particle size of 5 to 200 μm. 6. The electrophotographic charging device according to claim 1, wherein the charge injection layer of the electrophotographic photosensitive member contains at least conductive fine particles, a binder resin and a lubricant powder. 7. The electrophotographic charging device according to claim 6, wherein the lubricant powder is a powder of fluorine resin, silicone resin or polyolefin resin.