JP2001125294A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device that uniformizes an electrifying property for a photoreceptor by uniformizing and stabilizing the resistance of magnetic particles under the environment of high humidity, prevents defective image such as image irregularity, and also prevents the defective image so-called a nip mark corresponding to the contact part of the magnetic particles even though it is left standing for a long term. SOLUTION: The outermost surface layer of the photoreceptor is an electric charge injecting layer constituted by dispersing conductive particulates or mixing or copolymerizing a conductive resin in a light-transmissible and insulated binder resin, and the electrifying member is a member to electrify the surface of the photoreceptor by an injecting and electrifying method and is an electric brush constituted of the magnetic particles whose volume resistivity value is 104-109Ω. cm, and the image forming device possesses an atmosphere heater to execute control so that the inside of the image forming device is maintained at specified temperature without coming into contact with the magnetic particles in the device, and the control temperature of the atmosphere heater is set as (T+5) to 55 deg.C when the temperature of an environment in which the image forming device is used in set as T.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

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

As a charging means in such an electrophotographic method, a so-called corotron or scorotron, which utilizes a corona discharge, has been used. However, a large amount of ozone is generated when corona discharge, particularly negative or positive corona, is generated. Therefore, it is necessary to provide a filter for capturing ozone in the electrophotographic apparatus, and there has been a problem that the apparatus becomes large or the running cost increases.

As a technique for solving such a problem, a charging member such as a roller or a blade is brought into contact with the surface of a photoreceptor to form a narrow space in the vicinity of the contacting portion, which is interpreted according to the so-called Paschen's law. A charging method has been developed in which the generation of ozone is suppressed as much as possible by forming a discharge as possible (JP-A-57-178257, JP-A-5-178257).
6-104351 JP, JP-A-58-40566, JP-A-58-139
156, JP-A-58-150975).

However, in a blade or roller charging system, the problem of toner fusion on the photosensitive member tends to occur because the charging is performed by contacting the photosensitive member.

On the other hand, a method of using a photoconductor in close proximity to the photoconductor to avoid direct contact has been studied. As the member for charging the photoreceptor, the above-described roller, blade, brush, or a member obtained by applying a resistive layer to a long and thin conductive plate-like material, and the like, there is a problem that it is difficult to control the proximity distance. There are difficulties in practical application.

For this reason, there has been reported a charging device using a so-called magnetic brush holding a magnetic particle with a magnet body as a charging member, which has a relatively small contact load to a photoreceptor (Japanese Patent Laid-Open No. 59-133569, JP-A-63-187467, JP-A-4-
21873, JP-A-4-16674, etc.).

However, when a magnetic brush using magnetic particles is used as the charging member, the electric resistance of the magnetic particles changes due to the temperature change of the magnetic particles due to the environment in which the image forming apparatus is used. In some cases, the chargeability may be uneven or the charge potential may be reduced. Another problem is that the potential and sensitivity of the photoreceptor change due to the occurrence of dew condensation or the like due to a change in the outside air temperature, and a desired good image cannot be formed.

In order to solve the above-mentioned problem, a heating member is brought into direct contact with the magnetic particles to heat the magnetic particles, to keep the temperature of the magnetic particles constant and to suppress a change in resistance. Stabilizes the chargeability of the photoreceptor, and also keeps the photoreceptor at a constant temperature via the heated magnetic particles,
A method for suppressing a change in the potential and sensitivity of the photoreceptor due to dew condensation or the like has been disclosed (JP-A-6-348107, JP-A-9-90).
No. 715). However, according to the above-described method of directly heating only the magnetic particles, only the portion where the magnetic particles and the photoreceptor are in contact has a different temperature than the portion of the photoreceptor that is not in contact. In this case, the sensitivity and chargeability of the photoreceptor differ only in the area where the magnetic particles and the photoreceptor have been in contact, resulting in an image with high or low density in the cycle of the photoreceptor, a so-called nip mark. There is a problem that a defective image is generated, and the toner mixed in the magnetic brush is melted, adhered to the surface of the magnetic particles and easily spent, and the resistance of the magnetic particles was increased.

In addition, when the image forming apparatus is used in a high-humidity environment, the resistance of the portion of the photoreceptor that is not in contact with the magnetic particles is gradually lowered by leaving the photoreceptor, and the ozone generated by charging is reduced. When active substances such as NOx and NOx repeatedly adhere to the surface, there is a problem that image flow occurs due to a decrease in the resistance of the photoreceptor surface and image uniformity becomes insufficient.

[0011] The above problems are susceptible to resistance by ion conduction, 10 ⁸ ~10 ¹⁵ Ω · c tends to electric resistance is greatly changed by a change in the environment for the
It is remarkable in a photoreceptor using a charge injection layer having a volume resistance value of m, especially when a metal oxide is dispersed in the film because the surface of the metal oxide has high water absorption. And the above-mentioned problems tend to appear more conspicuously.

[0012]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above problems. That is, the present invention provides uniform and stable resistance of magnetic particles in a high-humidity environment, thereby making the chargeability of the photoreceptor uniform, preventing image defects such as image unevenness, and maintaining the magnetic particles even after being left for a long period of time. It is an object of the present invention to provide an image forming apparatus that prevents an image defect called a nip mark corresponding to a contact portion between a photoconductor and a photoconductor. It is another object of the present invention to provide an image forming apparatus which prevents image defects such as image deletion when the image forming apparatus is used in a high humidity environment.

[0013]

SUMMARY OF THE INVENTION The present invention is as follows. (1) A photosensitive member having a photosensitive layer on a conductive support for carrying an electrostatic latent image, and a charging member is brought into contact with the photosensitive member to apply a voltage to charge the surface of the photosensitive member. A charging device having a member, an electrostatic latent image forming device for forming an electrostatic latent image on the surface of the photoconductor by performing image exposure, and a toner carrier on the electrostatic latent image formed on the surface of the photoconductor. A developing device for forming a visible image by adhering the toner thereon, a transfer device for electrostatically transferring the visible image formed on the photoconductor surface to a transfer material, and an electrostatic transfer from the photoconductor to the transfer material And a fixing device for fixing the visible image, wherein the outermost surface layer of the photoconductor,
A light-transmissive and insulative binder resin, conductive fine particles dispersed therein, or a charge injection layer formed by mixing or copolymerizing a conductive resin. A magnetic brush made of magnetic particles having a volume resistivity of 10 ⁴ to 10 ⁹ Ω · cm, wherein the image forming apparatus does not contact the magnetic particles; An atmosphere heater for controlling the inside of the image forming apparatus to a constant temperature is provided in the image forming apparatus.
Wherein the temperature is (T + 5) to 55 ° C. (2) The outermost surface layer of the photoreceptor is 10 ⁸ to 10 ¹⁵
The image forming apparatus according to (1), wherein the charge injection layer has a volume resistance of Ω · cm. (3) The image forming apparatus according to (1) or (2), wherein the light transmissive and insulating binder resin of the charge injection layer is a photocurable or thermosetting acrylic resin. (4) The conductive fine particles contained in the charge injection layer are S
(1) to (3) characterized by using nO ₂ as a main component.
The image forming apparatus according to any one of the above. (5) The image forming apparatus according to any one of (1) to (4), wherein the charge injection layer contains a lubricating powder. (6) The image forming apparatus according to (5), wherein the lubricating powder is a fluororesin, a silicone resin, or a polyolefin resin. (7) The image forming apparatus according to any one of (1) to (6), wherein the charging device is a magnetic brush charging device having a conductive sleeve containing a magnet. (8) The volume average particle diameter of the magnetic particles is 10 to 40 μm.
The image forming apparatus according to any one of (1) to (7), wherein (9) At least one device selected from the group consisting of a photoreceptor, a developing device, and a transfer device is integrally supported with the charging device, and is configured to be detachable as a process cartridge. Any one of (8)
An image forming apparatus according to any one of the preceding claims.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below in detail with reference to the drawings.

In the image forming apparatus of the present invention, the outermost surface layer of the photoreceptor is made of a light-transmitting and insulating binder resin.
Dispersion of conductive fine particles, or a charge injection layer formed by mixing or copolymerizing a conductive resin, the contact charging member,
A magnetic brush configured to charge the surface of the photoreceptor by an injection charging method, and has a volume resistance value of 10 ⁴ to 10 ⁹ Ω · cm.
When an atmosphere heater that controls the inside of the image forming apparatus to a constant temperature without contacting the magnetic particles is provided in the image forming apparatus, and the control temperature of the atmosphere heater is T in the environment where the image forming apparatus is used ( T + 5) The temperature is not lower than 55 ° C. or higher.

FIG. 1 shows a schematic configuration of an image forming apparatus having the process cartridge of the present invention. In FIG.
The drum-shaped photoconductor 18 is driven to rotate at a predetermined peripheral speed in the direction of arrow X. In the rotation process, the photosensitive member 18 is uniformly charged with a predetermined positive or negative potential on its peripheral surface by a primary charging device, and then the image from the electrostatic latent image forming device 31 such as a slit exposure or a laser beam scanning exposure. Receive exposure. Thus, an electrostatic latent image is formed on the peripheral surface of the photoconductor.

The formed electrostatic latent image is visualized by the developing device 32 to become a toner image. The toner image is transferred between the photoconductor 18 and the transfer device 38 from a paper supply unit (not shown).
The image is electrostatically transferred by the transfer device 38 onto the transfer material 37 fed in synchronization with the rotation of the rotation 8. The transfer material 37 having undergone the image transfer is separated from the photoreceptor surface, introduced into the fixing device 35, and subjected to image fixing, thereby being printed out of the device as a copy.

After the image transfer, the surface of the photoreceptor 18 is cleaned and cleaned by removing the untransferred toner by a cleaning device 36, and is further subjected to a charge removal process by pre-exposure light from pre-exposure means (not shown). , For repeated image formation.
Note that pre-exposure is not always necessary.

The photosensitive member is charged by using a magnetic brush charging device 11 composed of magnetic particles as a primary charging device.

The magnetic brush charging device uses a magnetic brush composed of magnetic particles as a contact charging member, and applies a voltage by bringing the magnetic brush into contact with a photosensitive member.
It charges the surface of the photoreceptor. The magnetic brush applies a voltage to the magnetic particles by applying a voltage to a magnetic particle holder such as a conductive sleeve, and charges the photoconductor.

The resistance of the magnetic particles changes and becomes non-uniform due to the effect of moisture in the environment in which the magnetic particles are used, especially in a high humidity environment (particularly, the portion where the magnetic particles are in contact with the photosensitive member (exposed portion) and the magnetic particles are contained. The non-exposed area of the photoreceptor), the chargeability of the photoreceptor is unstable and uneven, and in an image forming apparatus that forms an image, if an image is formed after being left for a long time, The temperature and humidity of the part of the photoreceptor that corresponds to the part where the photoreceptor has contacted are different from those of the other parts, and the chargeability and sensitivity are different only for that part. It tends to occur, and when used in a high-humidity environment, image defects such as image deletion tend to occur.

For this purpose, the image forming apparatus of the present invention has an atmosphere heater for controlling the inside of the image forming apparatus to a constant temperature without contacting the magnetic particles. By controlling the temperature inside the image forming apparatus, that is, the entire surface of the photoconductor and the magnetic particles at a constant temperature, the influence of moisture in the magnetic particles is removed, the resistance value is made uniform, and the chargeability to the photoconductor is stabilized. In addition, the change in sensitivity and potential of the photoreceptor between the magnetic particles and the part that is not in contact with the photoreceptor is suppressed, preventing image defects at nip marks, and reducing the resistance due to moisture absorption on the photoreceptor surface. Prevent,
Image defects such as image unevenness, image blur, and image deletion can be prevented.

The atmosphere heater is not particularly limited as long as the inside of the image forming apparatus can be controlled to a constant temperature.
It is preferable to use them at the positions indicated by b and c because the entire surface of the photoreceptor and the magnetic particles can be kept at a constant temperature. Also,
It can be used not only in one place but also in several places. In any case, it is preferable that the magnetic brush is provided at a position where it does not come into contact with the magnetic particles, or is placed in contact with or away from the photoconductor.

As a heating method using an atmosphere heater, a heating element having a vacuum specification may be used. Specific examples of the heating element include electric resistance heating elements such as a winding heater, a plate heater, and a ceramics heater; A heat radiation lamp heating element such as an infrared lamp; a heating element by heat exchange means using a liquid, a gas or the like as a heating medium. The surface of the heating element may be covered, and as the surface material at that time, metals such as stainless steel, nickel, aluminum, and copper; ceramics; heat-resistant polymer resin, and the like can be used.

The temperature of the heating element can be controlled by installing a thermoswitch near the heating element and controlling the temperature by sensing the temperature of the heating element itself, or by installing a thermoswitch inside or near the photosensitive element and controlling the temperature. Any of the methods of controlling the temperature by sensing the temperature in the vicinity may be used.

The control temperature of the atmosphere heater for controlling the inside of the image forming apparatus to a constant temperature must be (T + 5) to 55 ° C., where T is the temperature of the environment where the image forming apparatus is used. If the temperature in the image forming apparatus is (T + 5) ° C. or lower, it is not preferable because the magnetic particles or the surface of the photoreceptor easily absorbs moisture, and the resistance of the magnetic particles or the photoreceptor tends to become nonuniform and low. If the temperature in the image forming apparatus is 55 ° C. or higher, the sensitivity of the photoconductor is deteriorated, the development characteristics of the developer are changed, and the toner is fused to the photoconductor. More preferably (T + 10) to 50 ° C
It is.

The present invention is also an image forming apparatus having a charging device for charging the surface of a photoreceptor by an injection charging method. The injection charging method is a method of performing charging by directly injecting a charge into a photoconductor, and uses a photoconductor having a charge injection layer as an outermost surface layer.

In the image forming apparatus of the present invention, the photosensitive member is charged by using a magnetic brush using magnetic particles as a contact charging member. When only a DC (direct current) voltage is applied to the contact charging member, a discharge starting voltage is applied. Is present, the potential on the photosensitive member due to the discharge is not charged up to the applied voltage, the potential difference between the contact charging member and the photosensitive member increases accordingly, and the magnetic particles serving as the contact charging member also leak onto the photosensitive member. It is more preferable to use the injection charging method since it tends to be easily lost. In addition, the charging by discharge has a problem that the surface of the photoreceptor is damaged by a discharge product and is likely to deteriorate or cause an image flow under high temperature and high humidity. In this regard, it is preferable to use the injection charging method.

The photoreceptor of the present invention comprises at least a conductive support, a photosensitive layer formed on the support, and a charge injection layer as an outermost surface layer.

The conductive support may be the same as the conductive support used for the photoreceptor included in an ordinary image forming apparatus. Specifically, a metal or alloy such as iron, copper, nickel, aluminum, titanium, tin, antimony, indium, lead, zinc, gold, silver, or a conductive material such as an oxide, carbon, or conductive resin thereof is used. It is possible to use a formed conductive support or a conductive support obtained by applying or vapor-depositing the above-mentioned conductive material on a substrate surface having a desired shape and physical properties by an appropriate method. Examples of the shape include a drum shape, a belt shape, and a sheet shape. In the present invention, a drum-shaped conductive support is preferably used.

The charge injection layer is formed by dispersing conductive fine particles in a light-transmitting and insulating binder resin, or mixing or copolymerizing a conductive resin.

In the present invention, the binder resin that can be used for the charge injection layer is not particularly limited as long as it is light-transmitting and insulating, but the light-transmitting property is such that the wavelength of the light for image exposure is 90% or more. As a material that transmits light and has an insulating property, a resin having a resistance of 1 × 10 ¹⁵ Ω · cm or more can be used.

Specific examples of such light-transmitting and insulating binder resins include polycarbonate resins, polyester resins, polyacrylate resins, polystyrene resins, polyethylene resins, polypropylene resins, polyurethane resins, An acrylic resin, an epoxy resin, a silicone resin, a cellulose resin, a polyvinyl chloride resin, a phosphazene resin, a melamine resin, and a vinyl chloride-vinyl acetate copolymer are exemplified. These binder resins can be used alone or in combination of two or more. Among these, a photo-curable or thermosetting acrylic resin that exhibits hardness and strength when cured is particularly preferred.

The conductive fine particles used in the charge injection layer in the present invention include metals, metal oxides and carbon black. Examples of the metal include aluminum, zinc, copper, chromium, nickel, silver, stainless steel, and the like, and those obtained by vapor-depositing these metals on the surfaces of plastic particles. Examples of the metal oxide include zinc oxide, titanium oxide, tin oxide, antimony oxide, indium oxide, bismuth oxide, tin-doped indium oxide, antimony and tantalum-doped tin oxide, and antimony-doped zirconium oxide. . These can be used alone or in combination of two or more. When two or more kinds are used in combination, they may be simply mixed, or may be in the form of a solid solution or fusion. The number average particle diameter of the conductive fine particles used in the present invention is preferably 0.3 μm or less, particularly preferably 0.1 μm or less from the viewpoint of the transparency of the protective layer. Further, in the present invention, it is particularly desirable to use a metal oxide from the viewpoint of transparency and the like among the conductive fine particles described above. Particularly preferred are conductive fine particles containing tin oxide (SnO ₂ ) as a main component.

In the present invention, examples of the conductive resin used for the charge injection layer include N-methoxymethylated nylon, polyurethane, and polypyrrole resin.

In view of the fact that the charge injection layer can be easily formed, a charge injection layer in which conductive fine particles are dispersed is a preferable configuration. When the charge injection layer is a layer in which conductive fine particles are dispersed, the addition amount of the conductive fine particles is preferably 2 to 250 parts by mass, more preferably 2 to 190 parts by mass, based on 100 parts by mass of the binder resin. preferable. If the amount is less than 2 parts by mass, it may be difficult to obtain a desired volume resistance value. If the amount is more than 250 parts by mass, the film strength may be reduced, and the charge injection layer may be easily scraped off. The reason for this is that the life tends to be shortened, and the resistance becomes low, and image defects due to the flow of the latent image potential are likely to occur.

When the charge injection layer is a layer obtained by mixing a conductive resin with a binder resin, the mixing ratio of the binder resin and the conductive resin is 2 to 100 parts by mass of the binder resin.
100 parts by mass of conductive resin. As a mixing method,
Although there is no particular limitation, a method in which the above resin is dissolved and mixed is exemplified.

In the case where the charge injection layer is a layer obtained by copolymerizing a binder resin and a conductive resin, the weight ratio of the two is 2 to 100 parts by mass of the binder resin and 100 parts by mass of the binder resin. Is preferred. The copolymerization method is not particularly limited, and examples thereof include a method of mixing and polymerizing both monomers.

The resistance value of a normal photosensitive drum surface material is 1 ×
In contrast to 10 ¹⁵ Ω · cm or more, when a charge injection layer is provided, the area where electric charges can be held on the surface of the photoreceptor increases, so that a contact charging member having a medium resistance value can be used. Charging can be performed. In the present invention, if the resistance value of the charge injection layer is in the range of 1 × 10 ⁸ to 1 × 10 ¹⁵ Ω · cm, the charging member having a medium resistance value (the volume of the contact charging member of the image forming apparatus of the present invention) Resistance value is 1 × 10 ⁴ to 1 × 10 ⁹ Ω · c
m) is preferable because charging can be performed with good efficiency such that the surface potential of the photosensitive member charged with respect to the applied voltage is 90% or more.

[0040] desirable from the viewpoint of the image flow, volume resistivity ^{1 × 10 10 ~1 × 10 14} Ω · cm, further also consider environmental variations in volume resistivity, volume resistivity 1 × 10 ¹² ~
It is desirable to use one having 1 × 10 ¹⁴ Ω · cm. 1x
If the resistivity is less than 10 ⁸ Ω · cm, the charged charge is not retained in the surface direction in a high humidity environment, causing image deletion, and 1 × 10 ¹⁵ Ω · cm.
cm, the charged charge from the contact charging member cannot be sufficiently injected and retained, and the charging tends to be poor. By providing such a functional layer on the surface of the photoreceptor, it plays a role of retaining the charged charge injected from the contact charging member, and also plays a role of releasing this charge to the photoreceptor substrate during light exposure, thereby reducing the residual potential. Let it.

The charge injection layer in the present invention may be constituted by dispersing conductive fine particles in a light-transmitting and insulating binder resin, or mixing or copolymerizing a conductive resin. It is preferable that each of the charge injection layers has a resistance of about 1 × 10 ⁸ to 1 × 10 ¹⁵ Ω · cm.

A method for measuring the volume resistance value of the charge injection layer is, for example, to form a charge injection layer on a polyethylene terephthalate (PET) film having a conductive film deposited on the surface, and use this film with a volume resistance measurement device (Hewlett Packard). Company 4
140B pAMATER) and a method of measuring by applying a voltage of 100 V in an environment of 23 ° C. and 65%.

The volume resistivity of the charge injection layer can be controlled within the above range by adjusting the amount of conductive fine particles or conductive resin. That is, the volume resistance decreases as the amount of the conductive fine particles or the conductive resin increases, and increases as the amount decreases.

In the present invention, the charge injection layer preferably contains a lubricating powder. The reason is that during charging, the friction between the photoconductor and the contact charging member is reduced, so that the charging nip is enlarged and the charging characteristics are improved.In the case of a cleanerless system, the transfer residual toner is mixed into the charging member. This is also to improve the transfer efficiency from the viewpoint of minimizing the transfer. In particular, it is more preferable to use a fluorine resin, a silicone resin, or a polyolefin resin having a low critical surface tension as the lubricating powder.

Of these, fluorine-based resins are more preferred. Examples of the fluorine-based resin include ethylene tetrafluoride resin, ethylene trifluoride chloride resin, ethylene hexafluoride propylene resin, vinyl fluoride resin, and vinylidene fluoride. Resins, ethylene dichloride ethylene chloride resins and copolymers thereof can be used alone or in combination of two or more.

The silicone resin used as the lubricating powder includes, for example, KMP- manufactured by Shin-Etsu Silicone Co., Ltd.
590, X52-854, X52-821, X52-8
30, X52-831 (silicone resin powder), K
MP110, KMP105, etc. can be used.

Examples of the polyolefin resin used as the lubricating powder include polyethylene and polypropylene resins.

The volume average particle diameter of the lubricating powder is 0.01 to 3
The range of μm is preferred. If it exceeds 3 μm, the transmittance of the charge injection layer deteriorates, and the strength of the film tends to weaken, which is not preferable. If it is less than 0.01 μm, it is difficult to come out on the surface of the film, and the lubricity of the film tends to deteriorate. It is not preferable.

Among these, in particular, ethylene tetrafluoride resin (PTFE) and vinylidene fluoride resin are more preferably used. In this case, the amount of the lubricating powder to be added is preferably 2 to 50 parts by mass, and more preferably 5 to 40 parts by mass with respect to 100 parts by mass of the binder resin. If the amount is less than 2 parts by mass, the amount of the lubricant powder is not sufficient, so that the charging characteristics are not sufficiently improved.If the amount is more than 50 parts by mass, the resolution of the image and the sensitivity of the photoreceptor may be greatly reduced. .

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

In the present invention, the photosensitive layer constituting the photoreceptor is a layer containing both a charge generating material for generating photocarriers and a charge transporting material for transporting carriers at least on the side in contact with the conductive support (hereinafter referred to as “photoconductive layer”). "Charge generation / transport layer"), and the charge injection layer may be provided thereon as a surface layer. Instead of the charge generation / transport layer, a two-layer structure in which a charge generation layer containing a charge generation material for generating photocarriers and a charge transport layer containing a charge transport material for transporting carriers may be used. good. In that case, either the charge generation layer or the charge transport layer may be formed on the side in contact with the conductive support.

Further, a conductive layer and an undercoat layer can be provided between the charge generation / transport layer and the conductive support in this order from the conductive support side. In addition, the conductive layer and the undercoat layer
They can also be combined into one layer. Here, in the present invention, the photosensitive layer is used as a concept in which all the layers formed on the conductive support are put together.

Specific examples of the charge generation material used in the photosensitive layer include phthalocyanine pigments, azo pigments, amorphous silicon, and triphenylmethane dyes.

As the charge transporting material used in the photosensitive layer,
Specific examples include a pyrene compound, a carbazole compound, a hydrazone compound, a triphenylamine compound, a styryl compound, and a stilbene compound.

As the binder resin used for the photosensitive layer, specifically, polyester resin, polyurethane resin, polyarylate resin, polyethylene resin, polystyrene resin, polybutadiene resin, polycarbonate resin, phenol resin, Epoxy resins, butyral resins and the like can be mentioned. Furthermore, after mixing reactive epoxy and (meth) acrylic monomers and oligomers,
It can be used after being cured.

The charge generation layer may be composed of only the charge generation material. In other cases, the charge generation layer may contain the binder resin or the like.

The content of the charge generation material in the charge generation layer is preferably from 30 to 100% by mass based on the total amount of the layer constituting materials. Further, the thickness of the charge generation layer is preferably about 0.1 to 0.5 μm.

The charge transport layer contains a binder resin and a charge transport material preferably in an amount of 30 to 120% by mass with respect to the binder resin, and further contains an ordinary charge transport layer if necessary. Various optional components similar to the above can be contained. The thickness of the charge transport layer is preferably about 10 to 30 μm.

The optional undercoat layer is a layer provided for preventing, for example, charges injected from the conductive support from affecting the charges charged on the surface of the photosensitive layer. It can be made of the same binder resin as described above, and may contain a conductive material or an acceptor. The thickness of the undercoat layer is preferably about 0.1 to 1.0 μm.

Further, the conductive layer is a layer provided for improving the surface condition of the conductive support, for example.
It is possible to adopt a configuration in which the conductive material is dispersed in a binder resin similar to the above. The thickness of the conductive layer is 10 to 2
It is preferably about 0 μm.

As a method for producing a photoreceptor used in the present invention, a conductive layer, an undercoat layer, a charge generation / transport layer, and a charge injection layer are usually laminated on a conductive support by vapor deposition or coating. Is used. Regarding the lamination method, specifically, a bar coater, a knife coater, a roll coater, an attritor, a spray, a dip coating, an electrostatic coating, a powder coating and the like are used for the coating. The coating method, the components of each layer is dissolved in an organic solvent or the like, after applying a solution or dispersion liquid and the like dispersed in the above method,
The removal can be performed by removing the solvent by drying or the like. Alternatively, when a reaction-curable binder resin is used, a solution or dispersion obtained by dissolving and dispersing each layer constituent component in a resin raw material component and an appropriate organic solvent or the like added as necessary is prepared by the above-described method. After applying by
For example, the resin material may be reacted and cured by heat, light, or the like, and the solvent may be removed by drying or the like as necessary.

The organic solvent used for producing the photoreceptor includes ethanol, toluene, methyl ethyl ketone and the like.

In the present invention, the charging member is a magnetic brush using magnetic particles having a volume resistivity of 1 × 10 ⁴ to 1 × 10 ⁹ Ω · cm as a contact charging member. More preferably, the volume resistivity is in the range of 1 × 10 ⁵ to 10 ⁸ Ω · cm.

The volume resistivity of the magnetic particles is 1 × 10 ⁴ Ω · c
If it is less than m, when a defect such as a scratch or a pinhole is present on the surface of the photoconductor, the electric charge is concentrated on the surface, and the electrification of the charging member and the photoconductor may be caused. If the volume resistance value of the magnetic particles exceeds 1 × 10 ⁹ Ω · cm, good charging of the photoconductor is not performed, and poor charging may occur.

The method for measuring the volume resistance of the magnetic particles is shown in FIG.
The method shown in FIG. That is, the cell B is filled with magnetic particles, the electrodes 21 and 22 are arranged in contact with the magnetic particles, a voltage is applied between the electrodes, and a current flowing at that time is measured to obtain a volume resistance value of the magnetic particles. be able to.

Measurement conditions are as follows: 23 ° C., 65% environment
Contact area between magnetic particles and electrode 2cm ^Two, Thickness 1mm, top
The applied voltage is 10 kg and the applied voltage is 100 V.

By sufficiently contacting the magnetic brush, which is a contact charging member, with the photoreceptor, the chargeability is improved, the transferability of the transfer residual toner into the charging device is improved, and the toner mixed in the charging device is removed. It is preferable that the magnetic brush be moved with a difference in speed between the photoconductor and the photoconductor because the chance of discharging the magnetic brush onto the photoconductor increases.

In the present invention, the charging device is preferably a magnetic brush charging device having a conductive sleeve enclosing a magnet body, and a contact brush being a magnetic brush composed of magnetic particles.

Specifically, as shown in FIG. 1, there is a configuration in which the conductive sleeve 14 includes a magnet roller 14 as a magnet.

The conductive sleeve is made of aluminum, SU
Examples thereof include those obtained by blasting a conductive material such as S or a conductive resin.

Examples of the magnet body include a magnet roller and the like.

A magnetic particle holder for holding magnetic particles (FIG. 1)
The gap between the conductive sleeve) and the photoconductor is 0.2
A range of ２2 mm is preferred. If the diameter is smaller than 0.2 mm, the magnetic particles do not easily pass through the gap, and the magnetic particles are not smoothly transported on the holding member, resulting in poor charging or excessive accumulation of the magnetic particles in the nip portion, causing adhesion to the photoreceptor. When the thickness is 2 mm or more, it is difficult to form a wide nip width between the photosensitive member and the magnetic particles, which is not preferable. More preferably, it is 0.2 to 1 mm, more preferably 0.3 to 0.7 mm.

The volume average particle diameter of the magnetic particles used for the contact charging member is preferably 10 to 40 μm. If it is smaller than 10 μm, the magnetic brush tends to adhere to the photoreceptor, and the magnetic particles are inferior in transportability when formed into a magnetic brush. 40
If it exceeds μm, the contact point between the magnetic particles and the photoreceptor decreases,
The charging uniformity of the injection charging method tends to deteriorate. More preferably, it is 15 to 30 μm.

In the present invention, the average particle size and the distribution of the magnetic particles are measured in a range of 0.05 to 350 μm using a laser diffraction type particle size distribution analyzer HEROS (manufactured by JEOL Ltd.).
It can be calculated by a method of measuring by dividing two logarithms and using the 50% volume median diameter as the average particle diameter.

As the magnetic particles used in the present invention, ferrite particles are preferably used. Ferrite containing a metal element such as copper, zinc, manganese, magnesium, iron, lithium, strontium, and barium is preferably used.

Further preferred are ferrite particles containing copper, manganese or lithium and iron, most preferably selected from copper or manganese.

The preferred composition ratio is

[0078]

Embedded image (Here, A1 to An represent elements, and A1 is selected from copper, manganese or lithium.
n and Y indicate the atomic ratio of the contained elements other than oxygen. 0.02 <X1 / Y <5, preferably 0.03 <X1 / Y <3.5, and more preferably 0.05 <X1 / Y <1.

Preferred elements after A2 are those not used in A2, such as copper, manganese, lithium, zinc,
Magnesium.

Further, the ferrite particles of the present invention include:
It can contain phosphorus, sodium, potassium, calcium, strontium, bismuth, silicon, aluminum and the like.

As a preferable configuration of the magnetic particles for charging, iron, copper, and iron among the total atoms of the elements except oxygen in the magnetic particles are preferable.
Manganese, lithium, zinc and magnesium containing atoms of 80 atomic% or more are preferably used, more preferably 90 atomic% or more, most preferably 95 atomic% or more.
Atomic number% or more.

Ferrite is a solid solution of oxide and is not always based on strict stoichiometry, but when copper is used,

[0083]

Embedded image Can be expressed by When using manganese,

[0084]

Embedded image And when lithium is used

[0085]

Embedded image It is.

[0086] Due to the characteristic usage of the magnetic particles for charging, particles using copper, manganese or lithium have an effect of being particularly excellent in durability. The effect is particularly great when copper and manganese are used.

While this mechanism is under intensive study, current flows through ferrite when a voltage is applied to charge the photoreceptor. This current path differs depending on the element, and particularly copper or manganese. It is presumed that many current paths are formed in the ferrite composed of In addition, it is assumed that even in the state of the surface, the exchange of charges with the photoreceptor forms a smooth surface.

The method for producing the magnetic particles for charging according to the present invention is as follows. For example, when producing Cu—Zn ferrite, 45 to 55 mol%, 20 to 30 mol%, and 20 to 30 mol% of Fe ₂ O ₃ , CuO and ZnO are used, respectively. The mixture is blended at a ratio of mol%, and a suitable dispersing agent, a binder and the like and water are added to form a slurry.
By firing at about ° C, magnetic particles having a volume resistance value used in the present invention can be obtained. Further, if necessary, crushing, pulverization, and classification are performed to obtain magnetic particles of a desired size.

As the binder used in the production of the magnetic particles, polyvinyl alcohol and the like can be mentioned.

Further, as a preferred method of producing ferrite particles, a method of pulverizing ferrite particles of 20 to 200 μm is mentioned.

After pulverization while controlling the shape distribution, the particles can be classified and used as they are, or can be used by mixing with other particles if necessary.

Although a production method by pulverizing a mass of ferrite is also possible, it is preferable to pulverize ferrite particles from the viewpoint of efficiency. Also,
The particle size adjustment of the magnetic particles for charging is performed at the crushing strength during the crushing step,
The adjustment is performed by adjusting the processing time and, if necessary, by performing a classification step.

The magnetic particles constituting the magnetic brush used as the contact charging member used in the present invention may have a surface layer for the purpose of adjusting the resistance, controlling the triboelectric charge polarity to the toner, and the like. The form of the surface layer is such that the surface of the magnetic particles is coated with a vapor-deposited film, a conductive resin film, a conductive pigment-dispersed resin film, or the like. The surface layer does not necessarily need to completely cover the magnetic particles, and the magnetic particles 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 deposited film formed on the surface of the magnetic particles is made of gold,
An example is a deposited film obtained by depositing platinum, ITO, or the like.

Examples of the conductive resin film used for coating the magnetic particles include N-methoxymethylated nylon, polyurethane, and polypyrrole resin. The resin used for the conductive pigment-dispersed resin film includes a binder resin and conductive fine particles. ,
Pigment dispersed.

Binder resins used for coating the magnetic particles include styrenes such as styrene and chlorostyrene; monoolefins such as ethylene, propylene, butylene and isobutylene; vinyl acetate, vinyl propionate, and the like.
Vinyl esters such as vinyl benzoate and vinyl butyrate; methyl acrylate, ethyl acrylate, butyl acrylate,
Dodecyl acrylate, octyl acrylate, phenyl acrylate, methyl methacrylate, ethyl methacrylate,
Α-methylene aliphatic monocarboxylic acid esters such as butyl methacrylate and dodecyl methacrylate; vinyl ethers such as vinyl methyl ether, vinyl ethyl ether and vinyl butyl ether; and vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone and vinyl isopropenyl ketone. And a homopolymer or a copolymer thereof. Particularly preferred binder resins include polystyrene, a styrene-alkyl acrylate copolymer, a styrene-acrylonitrile copolymer, and a styrene-butadiene from the viewpoints of dispersibility of conductive fine particles, film formability as a coating layer, and productivity. Copolymer, styrene-maleic anhydride copolymer, polyethylene, polypropylene and the like.

Further, polycarbonate resins, phenol resins, polyester resins, polyurethane resins, epoxy resins, polyolefin resins, fluorine resins,
Silicone-based resins, polyamide-based resins, and the like are also examples of binder resins used for coating magnetic particles.

Examples of the fluorine resin include polyvinyl fluoride, polyvinylidene fluoride, polytrifluoroethylene, polychlorotrifluoroethylene, polydichlorodifluoroethylene, polytetrafluoroethylene, and the like.
Solvent-soluble copolymers obtained by copolymerizing other monomers with polyhexafluoropropylene and the like can be given.

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

The conductive fine particles and pigments added to the resin used for coating the magnetic particles include copper, nickel,
Metals such as iron, aluminum, gold, and silver, or metal oxides such as iron oxide, ferrite, zinc oxide, tin oxide, antimony oxide, and titanium oxide, and electron conductive conductive powders such as carbon black. Examples of the conductive agent include lithium perchlorate and quaternary ammonium salts.

Further, from the viewpoint of suppressing the moisture absorption on the surface of the magnetic particles, the surface of the magnetic particles may be coated with a coupling agent, which is a compound having a hydrophilic group and a hydrophobic group, to perform a hydrophobic treatment. In the case of the coupling agent, an extremely thin film (at the molecular level) is formed on the surface of the magnetic particles, so the influence on the resistance value of the magnetic particles is small. The process of resistance adjustment may not be performed.

Examples of the coupling agent include titanates such as isopropoxytriisostearoyl titanate, dihydroxybis (lactato) titanium, diisopropoxybis (acetylacenato) titanium and the like, for example, acetoalkoxyaluminum diisopropylate and the like. Aluminum-based, for example, dimethylaminopropyltrimethoxysilane, n-octadecyldimethylmethoxysilane, n
Examples thereof include silane coupling agents such as -hexyltriethoxysilane, 3-aminopropyltrimethoxysilane, and n-octadecyltrimethoxysilane, and various functional groups such as an amino group and fluorine may be appropriately introduced.

The method of coating the surface of the magnetic particles with the coupling agent is as follows. The magnetic particles are added to a solution obtained by dissolving the coupling agent in an appropriate solvent, and the mixture is stirred and the surface of the magnetic particles is coated with the coupling agent. After forming the film, a method of heating to remove the solvent, taking out the magnetic particles, and drying by heating is used.

As the solvent used for the treatment with the coupling agent, toluene and methyl ethyl ketone may be mentioned.

The developing device in the image forming apparatus of the present invention is not particularly limited, but may have the same configuration as the developing device usually used in a normal image forming apparatus.

Specifically, a contact two-component developing device, a contact one-component developing device and the like can be mentioned as suitable developing devices. Here, the contact two-component developing device is a device that uses a mixture of toner and a magnetic carrier as a developer and conveys it by a magnetic force to develop the surface of the photoconductor in a contact state.

In the contact one-component developing device, the non-magnetic toner is coated on a sleeve by a blade or the like as a developer alone, and the magnetic toner is
Again, this is an apparatus that develops in a contact state by itself as a developer.

In this manner, the developer (that is, a mixture of the toner and the magnetic carrier in the contact two-component developing device, and the toner itself in the contact one-component developing device) and the transfer residual toner are exposed to light. When the contact is made on the surface of the body, a rubbing force is applied to the electrostatic force, and there is a tendency that the transfer residual toner can be effectively collected by the developing device. Therefore, a cleanerless image forming device is preferable.

When the developing device used in the present invention is, for example,
In the case of a component developing device, specifically, a developing device having the following configuration is used.

That is, a rotatable drum-shaped developing sleeve (toner carrier) for carrying a developer composed of a mixture of toner and a magnetic carrier for development, a magnet roller fixedly arranged in the developing sleeve, and a developer A regulating blade arranged to form a thin layer on the surface of the developing sleeve, a developing container for storing the developer, a developer stirring screw for stirring the developer in the developing container, and, if necessary, in the developing container. And a replenishing toner hopper for supplying the toner to the developing device.

In the developing sleeve, at least at the time of development, the gap at the position closest to the surface of the photoreceptor is about 2 mm.
It is preferable that the developer is arranged so as to have a thickness of 100 to 800 μm. ) Is 1.0 to 10.0 m
m. Usually, the developing blade rotates at least at the time of development.

Specific examples of the magnetic carrier for development used in the contact two-component developing means include magnetic particles composed of Cu-Zn ferrite, Mn-Mg ferrite, magnetic powder-dispersed resin particles, and the like. A resin coated with a resin, an acrylic resin, a fluororesin, or the like can be used. The volume average particle diameter of these magnetic particles is preferably 20 to 200 μm, more preferably 30 to 200 μm.
80 μm. These volume average particle diameters can be measured in the same manner as the above-described charging magnetic particles.

The mixing ratio of the toner and the magnetic carrier for development in the two-component developer is, specifically, a mass ratio of toner: magnetic carrier for development of 4: 100 to 12:
About 100 can be mentioned.

The image forming apparatus of the present invention has a photoreceptor, a charging device, an electrostatic latent image forming device, a developing device, a transfer device and a cleaning device. The photoreceptor, charging device and developing device have been described above. It is on the street. For the electrostatic latent image forming apparatus, the transfer apparatus, and the cleaning apparatus for cleaning the transfer residual toner remaining on the drum after the transfer,
The same electrostatic latent image forming apparatus, transfer apparatus, and cleaning apparatus that are usually used in a normal image forming apparatus can be used.

The transfer device has a member that comes into contact with the surface of the photoreceptor via the transfer material, and the transfer is performed by bringing the transfer material into contact with the surface of the photoreceptor using the member. It is preferred that

In the image forming apparatus of the present invention,
It is preferable that at least one device selected from the group consisting of a photoreceptor, a developing device, and a transfer device is supported integrally with the charging device, and is configured to be detachable as a process cartridge.

Specifically, as shown in FIG. 1, there is a process cartridge in which the charging device 11, the photosensitive member 18, and the cleaning device 36 are integrally detachable. By making the charging device detachable, even if the charging property is deteriorated due to the life (scraping) of the photoconductor, it is possible to form an image with the remaining toner by replacing only the cartridge, and the remaining toner can be removed. It can be used effectively without discarding.

[0118]

EXAMPLES The present invention will be described below in more detail with reference to examples, but the present invention is not limited to these examples. The evaluation methods used in the examples are as follows. 1) Measurement of Average Particle Size of Magnetic Particles The average particle size and distribution of magnetic particles were measured using a laser diffraction particle size distribution analyzer HEROS (manufactured by JEOL Ltd.).
The measurement was performed by dividing the range of 5-350 μm by 32 logarithms, and using a 50% volume median diameter as the average particle diameter. 2) Measurement of Volume Resistance Value of Magnetic Particle As a method for measuring the volume resistance of the magnetic particles, a method shown in FIG. 2 is exemplified. That is, the cell B is filled with magnetic particles, electrodes 21 and 22 are arranged so as to be in contact with the magnetic particles, a voltage is applied between the electrodes, and a current flowing at that time is measured to obtain a volume resistance value of the magnetic particles. Was.

Measurement conditions were as follows: 23 ° C., 65% environment
Contact area between magnetic particles and electrode 2cm ^Two, Thickness 1mm, top
The applied voltage is 10 kg and the applied voltage is 100 V. 3) Measurement of the volume resistivity of the functional layer of the photoreceptor The method of measuring the volume resistivity of the functional layer of the photoreceptor is as follows.
Evaporated polyethylene terephthalate (PET)
Create a functional layer to measure on the LUM and measure the volume resistance
Device (4140B pAM manufactured by Hewlett-Packard Company)
ATER), 100V power at 23 ℃, 65% environment
The measurement was performed by applying a pressure. 4) Measurement of toner particle size The toner particle size is Coulter Counter Multisizer type
(Coulter) and output number distribution and volume distribution
Interface (made by Nikkaki) and personal computer
Connect a pewter and use 1st grade sodium chloride as electrolyte
And 1% NaCl aqueous solution was adjusted.
As a dispersant in 100 to 150 ml of the above-mentioned electric field aqueous solution,
0.1% surfactant (alkylbenzene sulfonate)
５5 ml, and 2-20 mg of the measurement sample.
Electrolyte in which the material is suspended is dispersed for about 1 to 3 minutes with an ultrasonic disperser
Process, and aperture by the above coulter counter.
Using a 100 μm aperture as the
Calculate volume distribution and number distribution by measuring the volume and number of nuts
And the volume-based mass determined from the volume distribution according to the present invention.
Average particle size (D4: The median value of each channel is
(Representative value).

[0120]

Embodiment 1 First, magnetic particles, a photoreceptor, and a toner constituting a magnetic brush as a contact charging member used in the image forming apparatus of the present invention were manufactured. <Production of Magnetic Particles> Fe ₂ O ₃ was 50 mol% and CuO was 2
5 mol%, ZnO 25 mol%, phosphorus 0.05 mass%
The mixture was added, a dispersant, a binder, and water were added, dispersed and mixed by a ball mill, and granulated by a spray drier. Next, firing was performed at 1150 ° C. for 6 hours. The fired product was pulverized by a hammer mill to obtain spherical ferrite particles having a volume of 50% and a median diameter of 100 μm. The ferrite particles were further pulverized by a vibration mill and classified to obtain magnetic particles having a 50% volume median diameter of 24.5 μm and a volume resistance value of 2 × 10 ⁸ Ω · cm. <Production of Photoconductor> The photoconductor is a photoconductor using an organic photoconductive substance for negative charging (hereinafter referred to as “OPC photoconductor”), and an aluminum cylinder of φ30 mm is used as a conductive support. A structure in which five functional layers were provided thereon was adopted.

The first layer is a conductive layer, which is provided for smoothing defects of the aluminum cylinder and for preventing the occurrence of moire due to the reflection of laser exposure, and a conductive fine particle-dispersed resin layer having a thickness of about 20 μm. It is. The conductive fine particle-dispersed resin layer uses a phenol resin as a binder resin, and the binder resin has a thickness of 100%.
It is a layer in which conductive particles (tin oxide) of 50% by mass are uniformly dispersed. This is a method in which 100 parts by mass of tin oxide is dispersed in 100 parts by mass of phenol resin, applied, and the solvent is dried. And obtained by distillation.

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. A medium resistance layer having a thickness of about 1 μm, the resistance of which is adjusted to about 10 ⁶ Ω · cm by -66-610-12-nylon resin and methoxymethylated nylon.

The third layer is a charge generation layer, which uses polyvinyl butyral as a binder resin and has a pigment (oxytitanium phthalocyanine) having a thickness of about 0.3 μm in which 66% by mass of a pigment (oxytitanium phthalocyanine) is dispersed in the binder resin. A layer that generates positive and negative charge pairs when subjected to laser exposure.

The fourth layer is a charge transporting layer, a layer having a thickness of 15 μm in which 100% by mass of 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.

The fifth layer is a charge injecting layer, which is composed of a photocurable acrylic resin and ultrafine SnO ₂ particles, and further increases the contact time between the contact charging member and the photoreceptor to achieve uniform charging. It is a dispersion of ethylene tetrafluoride resin particles having a particle size of about 0.25 μm. It was prepared as follows.

15 parts by mass of an acrylic monomer (R604 (manufactured by Nippon Kayaku Co., Ltd.)), 20 parts by mass of antimony-doped tin oxide fine particles having a treatment amount of 7%, methyl hydrogen silicone oil (trade name: KF99: manufactured by Shin-Etsu Silicone Co., Ltd.) ) (30% by mass) and 150 parts by mass of ethanol were dispersed in a sand mill for 66 hours. Next, polytetrafluoroethylene fine particles (volume average particle size 0.18 μm) 15
After adding parts by mass and dispersing with a microfluidizer,
1 part by mass of 2-methylthioxanthone was added as a photopolymerization initiator. Using this solution, dip coating was performed on the charge transport layer to form a film, and 150 W / cm was applied using a high-pressure mercury lamp.
Light curing was performed at a light intensity of ² for 60 seconds, and then 120
C. for 2 hours to form a protective layer having a thickness of 3 .mu.m to form an electrophotographic photosensitive member. The dispersion used was a uniform charge injection layer having good dispersibility and a uniform layer surface.

As a result, the volume resistivity of the photoreceptor surface layer was 1.2 × 10 ¹⁵ Ω · cm in the case of the charge transport layer alone, while the resistance of the photoreceptor surface was 2 × 10 ¹² Ω.・
cm was obtained. <Production of toner> The following materials were mixed using a Henschel mixer, melted and kneaded with a twin screw extruder, coarsely ground with a hammer mill, and finely ground with a cryptron.
After classification, toner particles having a weight average particle size of 7.3 μm were obtained. 100 parts by weight of polyester resin 2 parts by weight of metal-containing azo dye 2 parts by weight of low-molecular-weight polypropylene 4 parts by weight of carbon black 5 parts by weight In producing a toner from the above toner particles, the surface of the silica matrix is silane-coupled to 100 parts by weight of the toner particles. 1.5 parts by mass of hydrophobic silica (number average particle size 10 nm) hydrophobized with an agent and silicone oil was externally added for 3 minutes using a Hensiel mixer FM10B to prepare a toner. The weight average particle diameter after external addition hardly changed from the weight average particle diameter of the toner particles.

An apparatus having the same structure as the image forming apparatus shown in FIG. 1 of the above embodiment was used as the image forming apparatus of this embodiment.

That is, a digital copying machine (GP55, manufactured by Canon Inc.) using a laser beam was prepared as an electrophotographic apparatus. An outline of the device is provided with a corona charger as a charging device for a photoreceptor, a one-component developing device employing a one-component jumping developing method as a developing device, and a corona charger, a blade cleaning device, a pre-charging exposure device as a transfer device. Equipment. Further, the photosensitive member charging device, the cleaning unit, and the photosensitive member are a single unit. The process speed is 150 mm / s.

An image forming apparatus obtained by modifying the above-described apparatus as follows is referred to as an image forming apparatus of this embodiment.

The developing part was modified from one-component jumping development to use of a two-component developer. The developer is a two-component developing method using a Cu-Zn ferrite carrier whose surface has a volume average particle diameter of 35 μm coated with a silicone resin and a developer composed of the above-mentioned negatively chargeable non-magnetic toner for the carrier. And The toner and the carrier were mixed at a mass ratio of 7: 100.

The developing device 32 includes a rotatable drum-shaped developing sleeve (toner carrier) 33 for carrying a developer composed of a mixture of toner and a magnetic carrier for development, and a magnet-containing developing device in which a magnet roller is fixedly disposed inside. A sleeve 33, a regulating blade 34 arranged to form the developer on the surface of the developing sleeve 33 in a thin layer, a developing container for storing the developer, and a developer stirring screw for stirring the developer in the developing container ( (Not shown).

The developing sleeve 33 is arranged so that the area closest to the photoconductor at the time of development is at least about 500 μm, and a thin layer of developer formed on the surface of the developing sleeve 33 is applied to the photoconductor. It is set so that it can be developed in a state where it is in contact.

The transfer device using the corona charger was changed to a transfer roller 38, which is a roller transfer type transfer device, and the pre-charge exposure device was removed. A reversal developing method using a negatively charged photoreceptor and a negatively charged toner was used.

The charging device is a magnetic brush charging device 11 using a Φ16 cm aluminum conductive sleeve 15 blast-treated on a non-magnetic surface to make it stand as a magnetic brush, and a magnet roller 14 contained therein. It was used. The gap between the conductive sleeve 15 serving as a magnetic particle holding member and the photosensitive member was set to about 500 μm, and the magnetic particles were coated on the sleeve. Further, the magnet roller is fixed, and the surface of the conductive sleeve 15 is in a direction opposite to the peripheral speed of the surface of the photoconductor at the nip portion with the photoconductor (arrow Z in FIG. 1).
Direction), and the photoreceptor and the magnetic brush were set to be in uniform contact.

Further, 40 g of the magnetic particles constituting the magnetic brush as the charging member are mounted on a conductive non-magnetic sleeve so that a charging nip having a width of about 3 mm is formed between the magnetic brush and the photosensitive member. The charging device was rotated at a peripheral speed of 180 mm / s at a peripheral speed of 150 mm / s so as to be opposed to the photoreceptor rotating.

As the developing bias, a rectangular wave of 1000 Vpp / 3 kHz is superimposed on a DC component of -500 V.

The primary charging bias was a voltage obtained by superimposing an AC component of 0.5 kVpp / 1000 Hz on a DC component of -700 V.

[0139]

Embodiment 2 The image forming apparatus described in Embodiment 1, magnetic particles,
The following durability test was performed using the photoconductor and the developer.

A ceramic heater in the form of a plate was placed at the position shown in FIG. 1A as an atmosphere heater. The control temperature of the heater was set to 42 ° C., and the above image was obtained under the environment of a temperature of 32 ° C. and a relative humidity of 85%. The forming apparatus was placed, and 20,000 sheets were durable at an image ratio of 30%. <Evaluation Method 1> After standing for 48 hours before and after endurance and after endurance, halftone, solid white, and character images were imaged, and the nip mark image, image deletion, and fusion were evaluated according to the following items. Was done. The results are summarized in Table 1. (1) Image unevenness (before durability, in an image left for 48 hours) 〇: A uniform image having no density difference in a halftone image is obtained.

Δ: Even if there is a slight difference in density in the halftone image, a uniform image can be obtained, and there is no practical problem.

X: A uniform halftone image having a large density difference in the halftone image was not obtained. (2) Nip mark image (in the image after being left for 48 hours) に お い て: Good in the halftone image with no difference in density between the nip portion and the place other than the nip.

Δ: In the halftone image, there is a slight difference in density between the nip and the place other than the nip, but there is no practical problem.

X: The density difference between the nip portion and the place other than the nip was large in the halftone image, and a uniform halftone image could not be obtained. (3) Image deletion (in the image after being left for 48 hours) ：: Good in the character image without image deletion.

Δ: A slightly flowing image is seen in the character image, and although the character becomes thicker, there is no practical problem.

X: In a character image, image deletion occurs and characters cannot be distinguished. (4) Fused image (image after endurance and after standing for 48 hours) ：: Good solid image with no spot image due to fusion at all.

Δ: Pochi image due to fusion was slightly present in the solid image, but there was no practical problem. ×: Pochi image due to fusion occurred in the solid self image. <Evaluation Method 2> Before and after the endurance, the surface potential of the photosensitive member, which was 0 V, in the first cycle and the saturation potential in the second and subsequent cycles were measured, and the potential difference between the saturation potential and the potential in the first cycle (potential convergence). Measure
The durability was evaluated by evaluating the increase in resistance of the charged particles according to the following evaluation items, with the difference in the potential difference between the saturation potential before and after the durability test and the potential in the first cycle being reduced in chargeability. The results are summarized in Table 1.

：: The chargeability after the durability is reduced by 30 V or less as compared with before the durability. △: The chargeability after the durability is 30 to 50 V as compared to before the durability.
Δ: The chargeability after the endurance is reduced in the range of 50 to 90 V as compared to before the endurance. ×: The chargeability after the endurance is 90 V or more lower than before the endurance.

[0149]

Example 3 Evaluation was performed in the same manner as in Example 2 except that the atmosphere heater was set at the position shown in FIG. The results are summarized in Table 1.

[0150]

Example 4 Evaluation was performed in the same manner as in Example 2 except that the control temperature of the atmosphere heater was set to 37 ° C. The results are summarized in Table 1.

[0151]

Example 5 Evaluation was performed in the same manner as in Example 2 except that the control temperature of the atmosphere heater was set to 48 ° C. The results are summarized in Table 1.

[0152]

Example 6 Evaluation was performed in the same manner as in Example 2 except that the atmosphere heater was set at the position shown in FIG. The results are summarized in Table 1.

[0153]

Comparative Example 1 Evaluation was performed in the same manner as in Example 2 except that the atmosphere heater was set at the position of d in FIG. The results are summarized in Table 1.

[0154]

Comparative Example 2 Evaluation was performed in the same manner as in Example 2 except that the control temperature of the atmosphere heater was changed to 32 ° C. The results are summarized in Table 1.

[0155]

Comparative Example 3 Evaluation was performed in the same manner as in Example 2 except that the control temperature of the atmosphere heater was changed to 60 ° C. The results are summarized in Table 1.

[0156]

Comparative Example 4 Evaluation was performed in the same manner as in Example 2 except that the atmosphere heater was omitted from the image forming apparatus. The results are summarized in Table 1.

[0157]

[Table 1] ────────────────────────────────── Evaluation method 1 Evaluation method 2 Image unevenness Nip mark Image flow Fusion 実 施 Example 2 ○ ○ ○ ○ ○ Example 3 ○ △ ○ ○ △ Example 4 △ △ △ ○ ○ Example 5 ○ ○ ○ △ ○ △ Example 6 ○ ○ ○ ○ △ ─────────────────────── ─────────── Comparative Example 1 ○ × × ○ × Comparative Example 2 × △ × ○ ○ Comparative Example 3 ○ ○ ○ × × Comparative Example 4 × × × ○ ○ ─────── ───────────────────────────

[0158]

According to the present invention, the chargeability of the photoreceptor is made uniform by uniformizing and stabilizing the resistance of the magnetic particles in a high humidity environment, and the contact between the magnetic particles and the photoreceptor after being left for a long period of time. Image defects and image deletion in the nip part, which is a part,
Further, it is possible to provide an image forming apparatus for preventing a fused image. Further, the image forming apparatus of the present invention can suppress the increase in resistance of the magnetic particles due to durability, and can provide a good image.

[Brief description of the drawings]

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

FIG. 2 is a schematic view of an apparatus for measuring a volume resistance value of magnetic particles as a charging member in the present invention.

FIG. 3 is a schematic diagram of an image forming apparatus used in a comparative example.

[Explanation of symbols]

 11: Magnetic brush charging device 12: Magnetic particle regulating blade 13: Magnetic particle storage chamber 14: Magnet roller 15: Conductive sleeve 16: Stirring roller 17: Magnetic particle 18: Photoconductor B: Cell 21, 22: Electrode 23: Guide Ring 24: Ammeter 25: Voltmeter 26: Constant voltage device 27: Measurement sample 28: Insulator 31: Exposure device 32: Developing device 33: Magnet-containing developing sleeve 34: Toner regulating blade 35: Fixing roller 36: Cleaning device 37: transfer material 38: transfer roller a, b, c, d: atmosphere heater

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) G03G 21/20 G03G 21/00 534 (72) Inventor Kikatsu Mizoe 3-30-2 Shimomaruko, Ota-ku, Tokyo No. Canon F-term (reference) 2H003 BB11 CC04 2H027 DA11 JA12 JC01 2H031 AC08 AC30 BA05 BA09 CA11 FA05 2H068 AA03 AA05 AA06 AA08 BB03 BB06 BB31 BB33 BB57 CA37 FA07 FA27 FC01

Claims (9)

[Claims] A photosensitive member having a photosensitive layer on a conductive support for carrying an electrostatic latent image; and a charging member contacting the photosensitive member to apply a voltage to charge the surface of the photosensitive member. A charging device having a contact charging member; an electrostatic latent image forming device for forming an electrostatic latent image on the surface of the photoconductor by performing image exposure; and a toner on the electrostatic latent image formed on the surface of the photoconductor. A developing device for forming a visible image by adhering toner on the carrier; a transfer device for electrostatically transferring the visible image formed on the surface of the photoconductor to a transfer material; A fixing device for fixing the electrotransferred visible image, wherein the outermost surface layer of the photoconductor is a light-transmitting and insulating binder resin, in which conductive fine particles are dispersed, or Charge injection by mixing or copolymerizing conductive resin The contact charging member is for charging the surface of the photoreceptor by an injection charging method, and has a volume resistance of 10
^A magnetic brush composed of magnetic particles of ⁴ to 10 ⁹ Ωcm, wherein the image forming apparatus has an atmosphere heater in the image forming apparatus for controlling the inside of the image forming apparatus to a constant temperature without contacting the magnetic particles. When the control temperature of the atmosphere heater is T in the environment in which the image forming apparatus is used, (T + 5) to 5
An image forming apparatus, wherein the temperature is 5 ° C. 2. An outermost surface layer of the photoreceptor is 10 ⁸
2. The image forming apparatus according to claim 1, wherein the charge injection layer has a volume resistance of 10 to 10 < ¹⁵ > [Omega] .cm. 3. The image forming apparatus according to claim 1, wherein the light-transmissive and insulating binder resin of the charge injection layer is a photo-curable or thermosetting acrylic resin. 4. The image forming apparatus according to claim 1, wherein the conductive fine particles contained in the charge injection layer contain SnO ₂ as a main component. 5. The image forming apparatus according to claim 1, wherein the charge injection layer contains a lubricating powder. 6. The image forming apparatus according to claim 5, wherein the lubricating powder is a fluororesin, a silicone resin, or a polyolefin resin. 7. The charging device according to claim 1, wherein the charging device is a magnetic brush charging device having a conductive sleeve containing a magnet body.
The image forming apparatus according to any one of claims 1 to 6, wherein 8. The magnetic particles have a volume average particle diameter of 10 to 10.
The image forming apparatus according to claim 1, wherein the thickness of the image forming apparatus is 40 μm. 9. The apparatus according to claim 1, wherein at least one device selected from the group consisting of a photoconductor, a developing device, and a transfer device is supported integrally with the charging device, and is configured to be detachable as a process cartridge. An image forming apparatus according to any one of claims 1 to 8.