JP2001013767A - Electorphotographic device and image forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrophotographic device where variation of image density or deterioration in line reproducing ability are not generated even when continuous printing of a great number of pieces is carried out. SOLUTION: In the electrophotographic device where an electrifying means 321 provided with an electrifying member 502 that is installed in contact with an electrophotographic photoreceptor body, an exposure means 210, a developing means 4 and a transfer means are installed in a periphery of the electrophotographic photoreceptor body 342 along a direction of movement of an electrophotographic photoreceptor body surface in this sequence, a surface layer of the electrophotographic photoreceptor body is provided with volume resistivity value that is 108 to 10R14 Ωcm, the electrifying member is provided with the volume resistivity value that is 104 to 109 Ωcm and electric field forming means 220 and 230 provided with electrodes to prevent soiling of the exposure means by a toner are provided upstream and/or downstream of the exposure means.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic apparatus, an image forming method and a process cartridge for developing, transferring and fixing an electric latent image, and more particularly to an electrophotographic apparatus for forming a latent image after charging by a contact charging means. The present invention relates to an apparatus and an image forming method, and more particularly, to an electrophotographic apparatus and an image forming method which have a stable injection charging property for a long time.

[0002]

2. Description of the Related Art Conventionally, many methods have been known as electrophotography. In general, a photoconductive substance is used to form an electrostatic latent image on a photoreceptor by charging means and image exposure means. Then, the latent image is developed with toner to form a visible image (toner image), the toner image is transferred to a transfer material such as paper, and the toner image is fixed on the transfer material by heat, pressure, etc. and copied. Get things. At this time, toner particles remaining on the photoconductor without being transferred onto the transfer material are removed from the photoconductor by a cleaning process.

In recent years, various organic photoconductive materials have been developed as photoconductive materials for electrophotographic photoreceptors, and in particular, a function-separated type having a charge generation layer and a charge transport layer laminated thereon has been put into practical use.
It is installed in copiers, printers, and facsimile machines. As a charging unit in such an electrophotographic apparatus, a unit using corona discharge has been used. However, since a large amount of ozone is generated, it is necessary to provide a filter. There was a problem such as up.

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 contact portion, and the space is formed 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 performing a discharge that can be interpreted, and among these, a roller charging method using a charging roller as a charging member is particularly preferably used in terms of charging stability. .

Since the charging is performed by discharging from the charging member to the member to be charged, the charging is started by applying a voltage higher than a certain threshold voltage. For example, when the charging roller is brought into contact with a photosensitive member containing an organic photoconductive substance having a photosensitive layer thickness of about 25 μm, an absolute value of about 64
When a voltage of 0 V or more is applied, the surface potential of the photoconductor starts to increase, and thereafter, the surface potential of the photoconductor increases linearly with a slope of 1 with respect to the applied voltage. Hereinafter, this threshold voltage is defined as a charging start voltage Vth. That is, in order to obtain the photoconductor surface potential Vd, the charging roller needs a DC voltage higher than Vd + Vth. Further, since the resistance value of the charging roller fluctuates due to environmental fluctuations or the like, it has been difficult to set the potential of the photoconductor to a desired value.

Therefore, as disclosed in Japanese Unexamined Patent Publication No. 63-149669, in order to achieve different charging uniformity, an AC voltage having a peak-to-peak voltage of 2 × Vth or more is applied to a DC voltage corresponding to a desired Vd. A DC + AC charging system in which a voltage on which a voltage is superimposed is applied to a contact charging roller is used. This is for the purpose of the potential leveling effect of the AC, and the potential of the member to be charged converges to Vd, which is the center of the peak of the AC voltage, and is hardly affected by disturbances such as the environment.

However, even in such a charging method, the essential charging mechanism uses a discharging phenomenon from the charging member to the photosensitive member, so that the voltage required for charging is as described above. A value higher than the photoconductor surface potential is required. In addition, the generation of vibrations and noise (hereinafter referred to as AC charging noise) of the charging member and the photoreceptor due to the electric field of the AC voltage, and the deterioration of the photoreceptor surface due to discharge become remarkable. I was

On the other hand, as disclosed in JP-A-61-57958, there is an image forming method in which a photosensitive member having a conductive protective film is charged by using conductive fine particles. In this publication, a photosensitive member having a semiconductive protective film having a resistance of 10 ⁷ to 10 ¹³ Ωcm is used as the photosensitive member, and the photosensitive member is charged by using conductive fine particles having a resistance of 10 ¹⁰ Ωcm or less. Accordingly, it is described that the photosensitive member can be uniformly charged without unevenness without injecting charge into the photosensitive layer, and good image reproduction can be performed. According to this method, vibration which is a problem in AC charging,
Although noise and the like can be prevented, the charging efficiency is low, and the toner adheres to the charging member due to scraping of the transfer residual toner by the conductive fine particles as the charging member, resulting in a change in charging characteristics.

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

[0010] A method of performing charging by applying a voltage to a contact charging member such as a charging roller, a charging fiber brush, or a charging magnetic brush to inject a charge into a trap level on the surface of a photoreceptor is disclosed in Japan Hardcopy, 1992. P
287, “Contact Charging Characteristics Using Conductive Rollers” and the like. In these methods, injection charging is performed on a photosensitive member that is insulated in a dark place with a low-resistance charging member to which a voltage is applied. This is a method in which the resistance value of the charging member is sufficiently low, and a material (such as a conductive filler) that makes the charging member conductive.
Had to be sufficiently exposed on the surface.
For this reason, the above-mentioned literature also states that the charging member is preferably an aluminum foil or an ion-conductive charging member having a sufficiently reduced resistance value in a high-humidity environment. According to the study of the present inventors, the resistance value of the charging member capable of sufficiently injecting electric charge into the photoreceptor is 1 × 10 ³ Ωcm or less. It is known that a problem occurs in the convergence of the charged potential.

However, when such a charging member having a low resistance value is actually used, an excessive leakage current flows from the charging member into a flaw, a pinhole, or the like generated on the surface of the photoreceptor. Enlargement of holes and destruction of electrification of the charging member are likely to occur.

In order to prevent this, the resistance of the charging member must be about 1 × 10 ⁴ Ω or more. And the contradiction that charging is not performed occurs.

In view of the above, the above-mentioned problems with the contact-type charging device or the image forming method using the charging device are solved, that is, on the member to be charged which cannot be prevented by the low-resistance charging member. Therefore, it has been desired to achieve both of the contradictory characteristics of pinhole leak.

Further, as described above, in an image forming method using a charging member in contact with a member to be charged, image defects are liable to occur due to poor charging due to dirt (spent) of the charging member, which causes a problem in durability. Even in charging by charge injection into a member to be charged, there is an urgent need to prevent the influence of poor charging due to contamination of the charging member in order to enable printing of many sheets.

The inventors of the present invention have conducted intensive studies on the surface layer of the latent image carrier and the contact charging member used for charging by charge injection, and have found that the resistance (B) of the contact charging member is 10 ⁴ to 10. ^When the resistance (A) of the surface layer of the latent image carrier is set to 10 ⁸ to 10 ¹⁴ Ωcm, sufficient chargeability is obtained, and the latent image is disturbed under high humidity, so-called image deletion. Has been found to be preferably 10 ¹⁰ to 10 ¹⁴ Ωcm, and more preferably 10 ¹⁰ to 10 ¹³ Ωcm in order to maintain sufficient chargeability regardless of the environment.

However, when the surface layer of the latent image carrier is charged, the residual toner remaining on the surface layer of the latent image carrier has the same polarity as the latent image carrier and easily loses adhesive force. At this time, if the absolute value of the charge amount of the residual toner is large, it is difficult to be released from the surface of the latent image carrier, but when combined with a latent image carrier having a low-resistance surface layer, the charge of the toner is transferred via the surface layer. The toner easily disappears, and the residual toner is more easily released. In particular, when applied to a cleanerless system, the amount of residual toner is large, and free toner floats in the space around the exposure device and adheres to the surface of the lens of the exposure device. As a result, there is a problem in that the amount of transmitted light changes, unevenness in light amount, diffusion of light, and the like occur, thereby deteriorating image quality.

For this reason, it is necessary to frequently clean the surface of the lens of the exposure device, and it is not possible to satisfy maintenance and management.

[0018]

SUMMARY OF THE INVENTION An object of the present invention is to provide an electrophotographic apparatus and an image forming method which solve the above-mentioned problems.

That is, an object of the present invention is to provide an electrophotographic apparatus and an image forming method which do not cause a change in image density and a decrease in line reproducibility even when a large number of continuous prints are performed.

It is a further object of the present invention to provide an electrophotographic apparatus and a method for forming an image which have clear image characteristics and are free from halftone roughness.

Another object of the present invention is to provide an electrophotographic apparatus and an image forming method which are stable in image density regardless of the environment and have excellent durability stability without fog.

[0022]

According to the present invention, there is provided a charging means having (i) a charging member for charging by contacting the surface of the electrophotographic photosensitive member around the electrophotographic photosensitive member; Exposure means for forming an electrostatic latent image on the charged electrophotographic photoreceptor by exposure by exposure means; (iii) developing means for developing the electrostatic latent image with toner to form a toner image; iv) an electrophotographic apparatus in which transfer means for transferring the toner image to a transfer material with or without an intermediate transfer member is sequentially arranged along a moving direction of the electrophotographic photosensitive member surface; When the surface layer of the electrophotographic photosensitive member is 1
0 ⁸ 10 ¹⁴ have a volume resistivity value of [Omega] cm, has a volume resistivity of 10 ⁴ to 10 ⁹ [Omega] cm the charging member, the upstream and / or downstream of the exposure means, contamination of the exposure means by the toner An electrophotographic apparatus comprising an electric field forming means having an electrode for preventing the occurrence of an electric field.

The present invention also provides a charging step of charging the electrophotographic photosensitive member by applying a voltage to a charging means having a charging member arranged in contact with the electrophotographic photosensitive member, An exposure step of forming an electrostatic latent image by irradiating the body with light by exposure means, a developing step of forming a toner image by developing the formed electrostatic latent image with toner, and An image forming method having a transfer step of transferring a toner image to a transfer material with or without an intermediate transfer member, wherein the surface layer of the electrophotographic photosensitive member has a volume resistance value of 10 ⁸ to 10 ¹⁴ Ωcm. ,
The charging member has a volume resistance of 10 ⁴ to 10 ⁹ Ωcm;
An image forming method, comprising an electric field forming means having an electrode for preventing contamination of the exposure means by toner at an upstream and / or downstream side of the exposure means.

[0024]

DETAILED DESCRIPTION OF THE INVENTION In the present invention, an electrophotographic member having a volume resistance (M) of 10 ⁴ to 10 ⁹ Ωcm and a surface layer having a volume resistance (S) of 10 ⁸ to 10 ¹⁵ Ωcm is used. The electrophotographic photosensitive member is charged by bringing it into contact with the photosensitive member and applying a voltage to the charging member. The volume resistivity (M) of the charging member and the volume resistivity (S) of the surface layer of the electrophotographic photosensitive member preferably satisfy M <S. When M ≧ S, minute resistance unevenness of the electrophotographic photosensitive member is easily picked up, and the latitude between uniform charging and dielectric breakdown at the time of charging becomes extremely narrow.

According to the study of the present inventors, when magnetic particles are used as a charging member, the surface of the magnetic particles is charged with 6 μm in order to maintain the charging ability to the transfer residual toner for a long period of time without increasing the resistance of the magnetic particles. The use of magnetic particles having a coupling agent having a linear alkyl group and / or an amino group having the above carbon number to impart charge to the transfer residual toner reduces floating toner, It has been found that the electric field formed by the electrodes proximate upstream and / or downstream of the exposure means is very effective in preventing the floating toner from adhering to the surface of the lens of the exposure device or the like. .

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

One example of the coupling agent used in the present invention includes a configuration of an alkyl group in which 6 or more carbon atoms are linearly linked to a hydrophobic group portion. The effect of including this configuration is that, in terms of triboelectric charging, the negative polarity can be easily imparted to the residual toner particularly in tribocharging due to the electron donating property of the alkyl group. Further, the alkyl group is relatively resistant to oxidation and the like, and also resistant to mechanical or thermal deterioration due to rubbing of the magnetic particles. Furthermore, if the chain is long, even if the molecular chain is cut by the mechanical or thermal load,
The remaining portion becomes an alkyl group having a certain length,
From the viewpoint of triboelectric charging, the change is small over a long period.

From this viewpoint, it is necessary that the alkyl group has a straight chain of 6 or more, preferably 8 or more, more preferably 12 or more, and preferably 30 or less. When the number of carbon atoms is less than 6, the remarkable effects of the present invention cannot be obtained.
It tends to be insoluble in the solvent, making it difficult to uniformly treat the surface of the magnetic particles, and further, the fluidity of the treated magnetic particles for charging deteriorates, and the chargeability tends to be non-uniform.

The amount of the coupling agent is as follows:
The content is preferably 0.0001% by weight or more and 0.5% by weight or less based on the total mass of the charging magnetic particles including the coupling agent.
If the amount is less than 0.0001% by weight, the effect of the coupling agent is not observed. In this sense, a processing amount of 0.001% by weight or more and 0.2% by weight or less can be more preferably used.

The abundance can be evaluated by weight loss on heating, and the weight loss on heating is preferably 0.5% by weight or less, more preferably 0.2% by weight or less.

Here, the heating loss refers to a temperature from 150 ° C. to 800 ° C. in a nitrogen atmosphere in an analysis using a thermobalance.
Up to the weight loss.

In the present invention, it is basically preferable that the surface of the magnetic particles for charging is treated only with a coupling agent, but it is also possible to coat a small amount of a resin component. In this case, the amount is preferably equal to or less than the amount of the coupling agent.

It is also possible to use a combination of the resin-coated magnetic particles for charging. In this case, the mixing ratio of the resin-coated magnetic particles is preferably 50% by weight or less based on the total weight of the magnetic particles in the charger. If the content exceeds 50% by weight, the effect of the magnetic particles for charging of the present invention is weakened.

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

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

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

In particular, when a negatively chargeable toner is used as the toner, it is more effective to use a silane coupling agent containing an amino group in combination to prevent floating toner, especially under high humidity.

Specific examples of the compounds that can be used in the present invention are shown below.

[0039]

Embedded image

Specific examples of the silane coupling agent containing an amino group are shown below.

[0041]

Embedded image

These can be used alone or in combination of two or more.

The magnetic particles for charging which can be used in the present invention have a volume resistivity of 1 × 10 ⁴ Ωcm or more and 1 × 10 ⁹ Ωcm or less. If it is lower than 1 × 10 ⁴ Ωcm, pinhole leakage tends to occur, and if it is higher than 1 × 10 ⁹ Ωcm, charging of the photoconductor tends to be insufficient.

In the magnetic particles for charging in the present invention, since the treatment amount of the coupling agent is 0.5% by weight or less, preferably 0.2% by weight or less, it is almost the same as the magnetic particles without surface treatment. Since a resistance value is obtained, stability in production and stability in quality are higher than in the case where a conductive particle-dispersed resin is used.

As the magnetic particles serving as the core of the magnetic particles for charging used in the present invention, so-called hard ferrites such as strontium, barium and rare earth, or ferrites such as magnetite, copper, zinc, nickel and manganese are used. More preferably, iron, aluminum,
Ferrites such as silicon, calcium, strontium, manganese, magnesium, and lithium are used.

The volume resistance value of the magnetic particles is determined by filling a cell A shown in FIG. 4 with magnetic particles 33, arranging electrodes 31 and 32 so as to be in contact with the magnetic particles, applying a voltage between the electrodes, and then flowing. Obtained by measuring the current. The measurement conditions are as follows: in an environment of a temperature of 23 ° C. and a relative humidity of 65%, the contact area between the filled magnetic particles and the electrode is 2 cm ² , the thickness (d) is 1 mm, the upper electrode is 10 kg, and the applied voltage is 100 V.

The average particle size of the magnetic particles for charging in the present invention is preferably 5 to 100 μm, more preferably 5 to 50 μm, and further preferably 5 to 35 μm. The average particle size is 5μ
If it is smaller than m, the chargeability is good, but the binding force is reduced. As a result, the toner may be mixed into the developing container, which may disturb the latent image during development. On the other hand, if it is larger than 100 μm, the spikes of the magnetic brush particles are in a coarse state, and charging unevenness and the like are likely to occur, and image quality is likely to deteriorate.

The average particle diameter of the magnetic particles was determined using a laser diffraction type particle size distribution analyzer HEROS (manufactured by JEOL Ltd.).
The range of 5 μm to 200 μm is divided into 32 logarithms and measured.
The average particle diameter was defined as a 50% volume median diameter.

In the present invention, there is also a preferable range in the triboelectric charging property between the toner used and the magnetic particles of the charging member, and a ratio of 7 parts by weight of the toner used to 100 parts by weight of the magnetic particles for charging is used. , The measured tribo value of the toner is the same as the charging polarity of the photoconductor, and its absolute value is 1 to 90 mC / kg, preferably 5 to 80 mC / k.
g, more preferably 10 to 40 mC / kg. Within this range, particularly good characteristics are exhibited with respect to the characteristics of taking in and sweeping out toner and charging of the photoreceptor.

The method for measuring the triboelectric charge of the toner is described below. FIG. 6 shows an outline of the measuring apparatus.

A mixture obtained by adding 2.8 g of toner to 40 g of magnetic particles to be measured conditioned at 30 ° C. and 80% relative humidity for 24 hours is placed in a 50-100 ml polyethylene bottle and shaken by hand 150 times. I do. Then add 500 to the bottom
Metal measuring container 52 with mesh screen 53
Then, 0.5 g of the above mixture is put in, and a metal lid 54 is placed. At this time, the entire weight of the measuring container 52 is weighed to be W1 kg. Next, in the suction machine (at least the portion in contact with the measurement container 52 is an insulator), the air is suctioned from the suction port 57 and the air volume control valve 56 is adjusted to adjust the pressure of the vacuum gauge 55 to 250 mmAq. In this state, suction is performed for 3 minutes to remove the developer. The potential of the electrometer 59 at this time is set to V (volt). Here, 58 is a capacitor whose capacity is C (mF).
And Also, the weight of the entire measuring machine after suction is weighed and W2 (k
g). The tribo value (mC / kg) of this developer is
Usually, it is calculated as shown below. Triboelectric charge (mC / kg) = CV / (W1-W2)

However, since the magnetic particles used in the present invention have a small particle size, a considerable amount of the particles pass through the mesh even with a 500-mesh screen. Then, it is calculated as in the following equation including the correction.

The weight of the previously weighed magnetic particles is expressed as M
1. M2 is a toner, and M3 is 500
Metal measuring container 52 with mesh screen 53
When charged into the toner triboelectric charge (mC / kg) = CV / ｛M3 × M2 / (M
1 + M2)｝.

In the electrophotographic apparatus of the present invention, a magnetic brush is used as a charging member that comes into contact with the photoreceptor. The charging means is constituted by a magnet roll as the magnetic particle holding member or a magnet roll inside. A conductive sleeve having a magnetic particle uniformly coated on its surface is preferably used.

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

The direction of movement of the magnetic brush for charging does not matter in the order of contact with the direction of movement of the photoreceptor at the contact portion. It is preferred to move in the direction.

The amount of the magnetic particles for charging held by the magnetic particle holding member for charging is preferably 50 to 500 mg / c.
m ² , more preferably 100 to 300 mg / cm ² . Within this range, particularly stable charging properties can be obtained.

The charging bias applied to the charging member may be only a DC component since the injection charging method is used in the present invention. However, it is preferable to apply a slight AC component since the image quality can be improved. The DC component may be the same voltage as the surface potential of the photosensitive member to be obtained, but preferably has a slightly larger absolute value. Although the AC component depends on the process speed of the apparatus, the peak-to-peak voltage of the applied AC component is 1000 Hz at a frequency of about 100 Hz to 10 kHz.
It is preferably about V or less. If the applied voltage exceeds 1000 V, a potential is generated on the photoreceptor with respect to the applied voltage, so that the latent image surface may undulate in potential, causing fogging and low density. As the waveform of the applied AC component, a sine wave, a rectangular wave, a sawtooth wave, or the like can be used.

Further, extra charging magnetic particles may be held and circulated in the charger.

In the present invention, since the transfer residual toner can be scattered by the magnetic brush, the transfer residual toner does not adversely affect the formation of the electrostatic latent image by exposure.

Preferred examples of the electrophotographic photosensitive member used in the present invention will be described below.

Examples of the conductive substrate include metals such as aluminum and stainless steel, aluminum alloys and alloys such as indium oxide-tin oxide, plastics having a coating layer of these metals and alloys, paper and plastic impregnated with conductive particles. For example, a cylindrical cylinder and a film such as a plastic having a conductive polymer are used.

On these conductive substrates, improvement of adhesiveness of the photosensitive layer, improvement of coating property, protection of the substrate, coating of defects on the substrate,
An undercoat layer may be provided for the purpose of improving the charge injection property from the substrate and protecting the photosensitive layer against electrical breakdown.
The undercoat layer is made of polyvinyl alcohol, poly-N-vinylimidazole, polyethylene oxide, ethyl cellulose, methyl cellulose, nitrocellulose, ethylene-
It is formed of materials such as acrylic acid copolymer, polyvinyl butyral, phenolic resin, casein, polyamide, copolymerized nylon, glue, gelatin, polyurethane, and aluminum oxide. The film thickness is usually 0.1 to
It is about 10 μm, preferably about 0.1 to 3 μm.

The photosensitive layer is of a single layer type in which a charge generating substance and a charge transporting substance are contained in the same layer, and a laminated type having a charge generating layer containing a charge generating substance and a charge transporting layer containing a charge transporting substance. It is roughly classified, and it is preferable to use a laminated type from the viewpoint of characteristics.

The charge generation layer is made of an azo pigment, a phthalocyanine pigment, an indigo pigment, a perylene pigment, a polycyclic quinone face, a squarylium dye, a pyrylium salt, a thiopyrium salt, a triphenylmethane dye, selenium or amorphous silicon. A charge generating substance such as an inorganic substance is dispersed in a suitable binder resin and coated. Alternatively, it is formed by vapor deposition. As the binder resin, can be selected from a wide range of binder resins, for example, polycarbonate resin, polyester resin, polyvinyl butyral resin,
Examples include polystyrene resin, acrylic resin, methacrylic resin, phenol resin, silicone resin, epoxy resin, and vinyl acetate resin. The amount of the binder resin contained in the charge generation layer is 80% by weight or less, preferably 0 to 40%.
Select to weight%. Further, the thickness of the charge generation layer is 5 μm or less,
Particularly, the thickness is preferably 0.05 to 2 μm.

The charge transport layer has a function of receiving charge carriers from the charge generation layer in the presence of an electric field and transporting them. The charge transporting layer is formed by dissolving a charge transporting substance in a solvent together with a binder resin if necessary, and applying the solution. The film thickness is generally 5 to 40 μm. As the charge transport material, biphenylene,
Polycyclic aromatic compounds having structures such as anthracene, pyrene and phenanthrene; indole, carbazole,
Nitrogen-containing cyclic compounds such as oxadiazole and pyrazoline; hydrazone compounds; styryl compounds; and selenium;
Inorganic compounds such as selenium-tellurium, amorphous silicon and cadmium sulfide.

As the binder resin for dispersing these charge transporting substances, polycarbonate resin, polyester resin, polymethacrylate, polystyrene resin,
Resin such as acrylic resin and polyamide resin, poly-N-
Organic photoconductive polymers such as vinyl carbazole and polyvinyl anthracene are exemplified.

The single-layer type photosensitive layer is formed by applying a solution containing the above-mentioned charge generating substance, charge transporting substance and binder resin.

The photoreceptor used in the present invention has a layer farthest from the support, that is, a charge injection layer as a surface layer. The volume resistance value of the charge injection layer is set to 1 in order to obtain sufficient chargeability and to prevent image deletion.
It is preferably from 10 ⁸ Ωcm to 1 × 10 ¹⁵ Ωcm, and particularly from 1 × 10 ¹⁰ Ωcm to 1 × 1 from the viewpoint of image deletion.
0 ¹⁵ Ωcm, considering environmental changes, etc., 1 × 10
It is preferably ^{10 Ωcm~1} × ^{10 13 Ωcm.} 1
If it is less than × 10 ⁸ Ωcm, the charged charge is not held in the surface direction in a high humidity environment, so that image flow may easily occur. If it exceeds 1 × 10 ¹⁵ Ωcm, the charged charge from the charging member cannot be sufficiently injected and held. Tends to cause poor charging. By providing such a functional layer on the surface of the photoreceptor, it plays a role of retaining the charged electric charge injected from the charging member, and also plays a role of releasing this electric charge to the photoreceptor support during light exposure, thereby reducing the residual potential. . Further, by employing such a configuration by using the charging member and the photoconductor according to the present invention, the charging start voltage Vth is small, and the photoconductor charging potential is almost 90% or more of the DC component of the voltage applied to the charging member. , That is, injection charging can be performed.

For example, the absolute value of the charging member is 100 to 20.
When a DC voltage of 00 V is applied at a process speed of 1000 mm / min or less, the charging potential of the electrophotographic photoreceptor having the charge injection layer of the present invention can be 80% or more, and more preferably 90% or more of the applied voltage. . On the other hand, the charging potential of the photoconductor obtained by the charging using the conventional discharge is, if the applied voltage is a DC voltage having an absolute value of 700 V,
The absolute value was only about 30% and was about 200 V.

The charge injection layer is composed of an inorganic layer such as a metal vapor deposition film or a conductive fine particle resin dispersion layer in which conductive fine particles are dispersed in a binder resin. The film is formed by applying an appropriate coating method such as a dipping coating method, a spray coating method, a roll coating method, and a beam coating method. In addition, an insulating binder resin mixed with a resin having a high light-transmitting ionic conductivity or mixed or copolymerized,
Alternatively, it may be formed of a single resin having a medium resistance and photoconductivity. In the case of the conductive fine particle dispersed film, the amount of the conductive fine particles is preferably 2 to 190% by weight based on the binder resin. If the amount is less than 2% by weight, it is difficult to obtain a desired volume resistance value. If the amount is more than 190% by weight, the film strength is reduced, the charge injection layer is easily scraped off, and the life of the photoconductor is shortened. This is because it becomes a tendency.

As the binder resin for the charge injection layer, polyester, polycarbonate, acrylic resin, epoxy resin, phenol resin, or a curing agent for these resins may be used alone or in combination of two or more.
Furthermore, when dispersing a large amount of conductive fine particles, it is necessary to disperse the conductive fine particles using a reactive monomer or a reactive oligomer, apply the dispersion to the surface of the photoreceptor, and then cure by light or heat. Is preferred. When the photosensitive layer is made of amorphous silicon, the charge injection layer is preferably made of SiC.

Examples of the conductive fine particles dispersed in the binder resin of the charge injection layer include metals and metal oxides, preferably zinc oxide, titanium oxide, tin oxide, antimony oxide, and the like. Indium oxide, bismuth oxide,
There are ultrafine particles such as tin oxide-coated titanium oxide, tin-coated indium oxide, antimony-coated tin oxide, and zirconium oxide. These may be used alone or as a mixture of two or more. Generally, when particles are dispersed in the charge injection layer, it is necessary that the particle diameter of the particles is smaller than the wavelength of the incident light in order to prevent scattering of the incident light by the dispersed particles. The particle size of the conductive and insulating particles to be formed is preferably 0.5 μm or less.

In the present invention, the charge injection layer preferably contains lubricant particles. The reason is that the friction between the photosensitive member and the charging member during charging is reduced, so that the charging nip is enlarged and the charging characteristics are improved. In particular, it is preferable to use a fluorine resin, a silicone resin or a polyolefin resin having a low critical surface tension as the lubricant particles. More preferably, a fluorine-based resin, in particular, polytetrafluoroethylene (PTFE) is preferable. In this case, the amount of the lubricant particles is 2 to 50% by weight, preferably 5 to 40% by weight, based on the binder resin. If the amount is less than 2% by weight, the amount of the lubricant particles is not sufficient, so that the charging characteristics are not sufficiently improved. If the amount exceeds 50% by weight, the resolution of the image and the sensitivity of the photoreceptor are greatly reduced. It is.

The fluororesin particles include polytetrafluoroethylene, polychlorotrifluoroethylene, polyvinylidene fluoride, polydichlorodifluoroethylene,
Tetrafluoroethylene-perfluoroalkylvinyl ether copolymer, tetrafluoroethylene-hexafluoropropylene copolymer, tetrafluoroethylene-
It is composed of one or more selected from ethylene copolymers and tetrafluoroethylene-hexafluoropropylene-perfluoroalkylvinyl ether copolymers. Commercially available fluorine resin particles can be used as they are. Those having a number average molecular weight of 0.3000 to 5,000,000 can be used, and 0.01 to 10μ
m, preferably those having a particle size of 0.05 to 2.0 μm can be used.

In the present invention, the thickness of the charge injection layer is 0.1
It is preferably from 10 to 10 μm, particularly preferably from 1 to 7 μm. When the film thickness is less than 0.1 μm, resistance to minute scratches is lost, and as a result, an image defect due to poor injection is caused. When the film thickness exceeds 10 μm, the image is easily disturbed due to diffusion of injected charges.

As the exposure means in the present invention, known means such as a laser and an LED can be used. In FIG. 1, L is exposure light from the exposure means.

Hereinafter, the color image forming apparatus according to the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram of a color image forming apparatus according to the present invention, which comprises a color reader unit and a color printer unit.

[Structure of Color Reader Unit] In FIG. 1, a document table glass (platen) 301 is provided horizontally above the color reader unit, and a document feeder (D) is placed above it.
F) 302 is arranged. There is also a configuration in which a mirror pressure plate (not shown) is mounted instead of the document feeder 302. First
A light source 3 which is a halogen lamp is provided in the carriage 314.
03, 304, reflectors 305, 306 for condensing the light from these light sources on the original, and a mirror 307 for reflecting the reflected light or the projected light from the original. Further, the reflected light from the mirror 307 is further applied to the second carriage 315 by C.
Mirrors 308 and 309 for focusing light on the CD 101 are mounted.

The substrate 31 on which the CCD 101 is mounted
1, an image processing unit 312 including a binary conversion unit and a delay unit, and another interface (I / F) unit 31 such as an IPU.
3 is provided.

The speed of the first carriage 314 is V.
The second carriage 315 scans the entire surface of the document (sub-scanning) at a speed V / 2 by mechanically moving the driving unit 316 in a direction perpendicular to the electrical scanning (main scanning) direction of the CCD 101. .

Documents on the platen glass are light sources 303 and 30
4 is reflected, and the reflected light is guided to the CCD 101 and converted into an electric signal. In the case where the CCD 101 is a color sensor, even if the RGB color filters are inlined in RGB order on a one-line CCD,
3 line CCD, R filter, G filter,
The B filter may be arranged for each CCD, the filter may be on-chip, or the filter may be C
It may be different from the CD.

Then, the electric signal (analog signal) is input to the image processing unit 312, and the clamp & Amp. & S
/ H & A / D section, sample-and-hold (S / H), clamp the dark level of the analog image signal to the reference potential, amplify it to a predetermined amount (the above processing order is not limited to the writing order), and A / D conversion Then, for example, it is converted into a digital signal of 8 bits for each of RGB.

The RGB signals are subjected to shading correction and black correction in a shading section, and then to a connection & MTF correction & document detection section. In the case where the CCD 101 is a three-line CCD, the connection position is determined by the reading position between lines. Therefore, the delay amount for each line is adjusted according to the reading speed, the signal timing is corrected so that the reading positions of the three lines are the same, and the MTF correction varies depending on the reading speed and the magnification, since the reading MTF changes. The change is corrected, and the document detection recognizes the size of the document on the platen glass.

The digital signal whose read position timing has been corrected is input to the input masking section to control the spectral characteristics of the CCD 101, the light sources 303 and 304, and the reflectors 305 and 306.
Is corrected. The output of the input masking section is input to a selector that can be switched with an external I / F signal.

The signal output from the selector is input to the color space compression / background removal / LOG conversion unit and background removal unit. After the signal input to the background removal unit is removed,
It is input to a black character determination unit that determines whether or not the document is a black character of the original, and generates a black character signal from the original. Also,
In the color space compression & background removal & LOG conversion unit to which the output of the other selector is input, the color space compression determines whether or not the read image signal is within the range that can be reproduced by the printer. If not, the image signal is corrected so that the image signal can be reproduced by the printer. Then, a background removal process is performed, and RGB conversion is performed by LOG conversion.
The signal is converted into a CMY signal.

In order to correct the timing and the signal generated by the black character determination unit, the output signal of the color space compression / background removal / LOG conversion unit is adjusted in timing by the delay unit. The two types of signals are subjected to moiré removal by a moiré removal unit, and then subjected to scaling processing in the main scanning direction by a scaling unit.

In the UCR & masking & black character reflecting section, the signal processed by the scaling section is converted into a CMYK signal by the UCR processing of the CMY signal, and the masking processing section corrects the signal to the signal which was present at the output of the printer. The determination signal generated by the black character determination unit is fed back to the CMYK signal.

The signal processed in the UCR & masking & black character reflection section is subjected to density adjustment in the γ correction section, and then to smoothing or edge processing in the filter section.

As described above, the processed signal is converted into 8 signals by the binary conversion section.
It is converted to a bit multi-level signal. This conversion method may be any one of the improved dither method, error diffusion method, and error diffusion.

[Configuration of Color Printer Unit] In FIG. 1, the Y image forming unit 317, the M image forming unit 318, the C image forming unit 319, and the K image forming unit 320 are photosensitive drums 342, 343, 344, and 345, respectively. , Charger 32
1, 324, 327, 330, LED units 210, 21
1, 212, 213, developing units 322, 325, 328,
331 are provided. Further, the developing devices 322, 325,
328 and 331 are developing sleeves 345 and 34, respectively.
6, 347 and 348 are provided.

Here, since the respective structures are the same, the Y image forming section 317 will be described in detail, and the description of the other image forming sections will be omitted.

In the Y image forming section 317, 117 mm / s
A photosensitive drum 342 that rotates at a speed of ec is provided, around which a charger 321, an LED unit 210, and a developing device 322 are provided.
And so on.

The charger 321 rotates the sleeve 500 in the direction of the arrow at a speed of 140 mm / sec as shown in FIG.
2 to form a dielectric brush, the photosensitive drum 34
2 is uniformly charged to prepare for latent image formation.

Next, the photosensitive drum 3 is
The latent image on 42 is developed to form a toner image.

The developing device 322 includes a sleeve 345 for applying a developing bias to develop. A transfer charger 323 is disposed below the developing device 322 in the figure with the transfer belt 333 interposed therebetween.
, And the toner image on the photosensitive drum 342 is transferred to a recording paper or the like on the transfer belt 333.

After the transfer, the toner 19a remaining on the photosensitive drum 342 is once taken into the charger 321 and is changed back to the photosensitive drum 342 after changing its electrostatic property. The developing device 322 collects the toner and re-uses it. Use.

Next, a procedure for forming an image on a recording sheet or the like will be described. The recording paper and the like stored in the cassettes 340 and 341 are fed one by one by the pickup rollers 338 and 339 and fed by the paper feed rollers 336 and 337 at 110 mm / s.
It is supplied onto the transfer belt 333 moving at ec. The transfer belt 333 includes a Y image forming unit 317 and an M image forming unit 3.
18, are disposed below the C image forming section 319 and the K image forming section 320, and are driven by the transfer belt roller 348.

The recording paper fed to the transfer belt 333 is
The transfer belt roller 348 is charged by the suction charger 366 paired with the transfer belt roller 348, and is held by the transfer belt 333 by suction. A paper edge sensor 367 is arranged adjacent to the adsorption charger 366, and detects the edge of the recording paper or the like on the transfer belt 333. The detection signal of the paper leading edge sensor 367 is sent from the printer unit to the color reader unit, and is used as a sub-scanning synchronization signal when a video signal is sent from the color reader unit to the printer unit.

Thereafter, the recording paper or the like is conveyed by the transfer belt 333 and is transferred to the image forming units 317 to 320 in the Y direction.
A toner image is formed on the surface in the order of M, C, and K.

The recording paper or the like that has passed through the K image forming section 320 is separated from the transfer belt 333 after the charge is removed by the charge remover 349 to facilitate separation from the transfer belt 333. Peeling charger 3 adjacent to static eliminator 349
50 is provided to prevent image disturbance due to peeling discharge when recording paper or the like is separated from the transfer belt 333.

The separated recording paper or the like is charged with a pre-fixing charger 35 in order to supplement the toner attraction force and prevent image disturbance.
After being charged at 1 and 352, the toner image is heat-fixed by the fixing device 334, and then discharged to a discharge tray 335. Further, the transfer belt 333 is discharged by the inside / outside discharger 353.

Next, the operation during electric field formation will be described with reference to the Y image forming section in FIG. In FIG.
Is an LED unit, 240 is a lens unit, and 220 and 230 are electric field forming electrodes. That is, by applying a voltage to the electrodes 220 and 230, a toner flying electric field is formed on the photoreceptor surface, and contamination due to toner adhesion to the lens surface can be prevented. Here, it is desirable that the electrode is separated from the lens surface by 5 mm or more. If it is less than 5 mm, an electric field is easily formed from the electrode to the lens surface, and the effect of preventing toner adhesion is suppressed.

More specifically, since the transfer residual toner is triboelectrically charged by the charged particles 502 and has a negative charge, when a voltage of -1.5 to -0.5 kV is applied to 220 and 230, the toner remains floating. The toner moves back onto the photoreceptor. The voltages applied to 220 and 230 may be the same or different. Further, since the chargeability of the residual toner changes depending on the temperature and humidity, the applied voltage may be changed depending on the temperature and humidity.

Although the developing means is not particularly limited, a system in which the developing means is also a substantial cleaning means, that is, the electrophotographic photosensitive member after transfer between the transfer position and the charging position and between the charging position and the developing position In the case of a so-called cleaner-less system having no cleaning means for collecting and storing the toner remaining on the upper surface, reversal development is preferable, and a configuration in which the developer and the photoconductor are in contact is preferable.
For example, a contact two-component developing method, a contact one-component method and the like are mentioned as suitable developing methods. This is because, when the developer and the transfer residual toner are in contact with each other on the photoreceptor, a rubbing force is applied to the electrostatic force, and the transfer residual toner tends to be effectively collected by the developing unit. It is preferable that the DC component of the bias applied to the development be between the black portion (the exposed portion in the case of the reversal development) and the potential of the white background portion.

As the transfer means, a known method such as a corona, a roller and a belt is used.

In the present invention, the electrophotographic photosensitive member, the charging member, and, if necessary, the developing means are integrally supported to form a cartridge, and the process cartridge is detachable from the main body of the electrophotographic apparatus. Reference numeral 23 in FIG. In the present invention, the developing means may be a cartridge separate from the cartridge having the electrophotographic photosensitive member and the charging member.

In the present invention, it is necessary to change the charging bias of the photoreceptor in order to use the surface of the photoreceptor to transport the toner from the charging device that temporarily collects the transfer residual toner to the developing portion and to collect and reuse it. Absent. However, practically, when a transfer material jam occurs or when images having a high image ratio are continuously obtained, the amount of the transfer toner mixed into the charger may be extremely large.

In this case, during the operation of the electrophotographic apparatus, the toner may be moved from the charger to the developing machine by utilizing the time when no image is formed on the photosensitive member. The non-image forming time includes the time of pre-rotation, the time of post-rotation, and between transfer materials. In that case, it is also preferable to change the charging bias so that the toner is more easily transferred to the photoconductor than the charger. As a method of facilitating the discharge from the charger, the peak-to-peak voltage of the AC component is reduced, or only the DC component is used.In addition, without changing the peak-to-peak voltage, the waveform is changed to lower the AC effective value, And the like.

The toner used in the present invention has a weight average particle diameter of 1 to 9 μm, and has particles having a weight average particle diameter of 0.012 to 0.4 μm as an external additive. The average particle size of the external additive is preferably 0.02 to 0.3 μm,
More preferably, it is 0.03-0.2 μm.

As described above, in the charged magnetic brush, the load due to friction between the magnetic particles is very large as compared with the case of development, but in the present invention, the toner surface mixed into the magnetic brush This is because the presence of the external additive having the above particle diameter can soften the rubbing of the magnetic particles on the toner. In particular, a cleaner-less system that reuses toner remaining after transfer is preferable because deterioration of the toner from the viewpoint of development can be prevented.

If the particle size is less than 0.012 μm, it is difficult to obtain the above-mentioned effects, and the toner hardly separates from the charging member and accumulates. On the other hand, if it exceeds 0.4 μm, it is easy to fall off the toner, and it is difficult to obtain the above effects.
In addition, the fluidity of the toner tends to deteriorate, and the charging of the toner becomes uneven.

There is no particular limitation on the toner other than the above conditions, but there is a preferred mode in terms of transfer efficiency from the viewpoint of toner scattering. In other words, if the amount of the transfer residual toner that enters the magnetic brush is small, the absolute amount of the toner that may be scattered is small, so that the combination effect with the electrophotographic apparatus of the present invention is large. In the shape factor of the toner, SF-1 is 100 to 160, and SF-2 is 1 to 1.
When the SF-value is in the range of 100 to 140, particularly SF-1 is in the range of 100 to 140, and the SF-2 is in the range of 100 to 140, the transferability tends to be good. In particular, those formed by a polymerization method and having a shape coefficient in the above range are preferable because of particularly high transfer efficiency.

The measurements for SF-1 and SF-2 are as follows.

For example, a Hitachi FE-SEM (S-
800), 100 toner images of 2 μm or more, which are enlarged 1000 times, are randomly sampled, and the image information is introduced into, for example, an image analyzer (Luzex III) manufactured by Nicole Corporation via an interface, and analyzed. And the value obtained from the following equation.

[0117]

(Equation 1) In the formula, MXLNG indicates the absolute maximum length of the particle, PERIME indicates the perimeter of the particle, and AREA indicates the projection plane of the particle. SF-
1 indicates the degree of roundness of the particles, and SF-2 indicates the irregularities of the particles. The closer they are to 100, the closer the shape is to a true sphere.

The external additive of the toner used in the present invention is not particularly limited as long as it is 0.012 to 0.4 μm which satisfies the above-mentioned characteristics. However, in terms of charge stability and white color. Hydrophobized silica, titania, zirconia or alumina is preferable, and further, from the viewpoint of imparting fluidity and environmental stability of the toner, titania or alumina, particularly amorphous alumina, further does not hinder the injection chargeability. , Medium resistance anatase titania is more preferred.

Examples of the above-mentioned hydrophobizing agent include coupling agents such as silane coupling agents, titanium coupling agents and aluminum coupling agents, and oils such as silicone oils, fluorine-based oils and various modified oils.

Among the above-mentioned hydrophobizing agents, a coupling agent is particularly preferable in terms of stabilizing the charge of the toner and imparting fluidity.

Therefore, the external additives used in the present invention include:
Particularly preferably, anatase-type titanium oxide fine particles subjected to a surface treatment while hydrolyzing a coupling agent are extremely effective in terms of stabilizing charging and imparting fluidity.

The above-mentioned hydrophobic fine inorganic powder preferably has a hydrophobicity of preferably 20 to 80%, more preferably 40 to 80%.

If the degree of hydrophobicity of the inorganic fine powder is less than 20%, the charge amount is likely to be greatly reduced due to long-term storage under high humidity, and a mechanism for accelerating the charge on the hardware side is required, and the apparatus becomes complicated. When the degree of hydrophobicity exceeds 80%, it is difficult to control the charging of the inorganic fine powder itself, and as a result, the toner is easily charged up under low humidity.

The method for measuring the degree of hydrophobicity will be described later.

When the weight average particle diameter of the toner is less than 1 μm, the miscibility with the carrier is reduced and defects such as toner scattering and fogging are liable to occur.
A decrease in the reproducibility of the minute dot latent image, scattering at the time of transfer, and the like are likely to occur, which hinders high image quality.

Examples of the colorant contained in the toner used in the present invention include known dyes and pigments such as phthalocyanine blue, induslen blue, peacock blue, permanent red, lake red, rhodamine lake, Hansa yellow, permanent yellow and Benzidine yellow can be used. Its content is O
In order to be sensitive to the permeability of the HP film, it is preferably 12 parts by weight or less based on 100 parts by weight of the toner.
More preferably, the content is 2 to 10 parts by weight.

Additives may be added to the toner used in the present invention as needed as long as the characteristics of the toner are not impaired. Examples of such additives include Teflon (registered trademark) and zinc stearate. And a transfer aid such as a fixing agent (eg, low molecular weight polyethylene, low molecular weight polypropylene, etc.), silica particles, silicone resin particles, alumina particles, and organic resin particles.

In the production of the toner used in the present invention, the constituent materials are kneaded well by a heat kneader such as a hot roll, a kneader and an extruder, and then obtained by mechanical pulverization or classification. A method in which a toner material such as a colorant is dispersed and then obtained by spray drying, or a method in which a predetermined material is mixed with a polymerizable monomer capable of forming a binder resin, and then this suspension is polymerized. A method for producing a polymerized toner for obtaining a toner can be applied.

Various resins are used as the binder resin used in the toner of the present invention. For example, polystyrene,
Styrene copolymers such as styrene-butadiene copolymer and styrene-acryl copolymer, ethylene copolymers such as polyethylene, ethylene-vinyl acetate copolymer and ethylene-vinyl alcohol copolymer, phenolic resins , Epoxy resin, acrylic phthalate resin,
Examples include polyamide resins, polyester resins, and maleic acid resins. The production method of any resin is not particularly limited.

In the present invention, a suspension polymerization method under normal pressure or under pressure is particularly preferable, wherein a fine particle toner having a sharp particle size distribution and a particle size of 4 to 8 μm can be obtained relatively easily. As a specific method for encapsulating the low softening point substance, the polarity of the material in the aqueous medium is set to be smaller for the low softening point substance than for the main monomer, and further, a small amount of a large polar resin or a monomer. By adding a body, a toner having a so-called core / shell structure in which a material having a low softening point is coated with an outer shell resin can be obtained. To control the particle size distribution and the particle size of the toner, it is necessary to change the type and amount of the hardly water-soluble inorganic salt or dispersant that acts as a protective colloid, and the mechanical device conditions such as the rotor peripheral speed, the number of passes, and the shape of the stirring blade. A predetermined toner can be obtained by controlling the stirring conditions such as, the shape of the container, and the solid content concentration in the aqueous solution.

In the present invention, as a specific method for measuring the tomographic plane of the toner, a cured product obtained by sufficiently dispersing the toner in a room-temperature curable epoxy resin and then curing the same in an atmosphere at a temperature of 40 ° C. for 2 days. Is dyed using ruthenium tetroxide and, if necessary, osmium tetroxide, and then a flaky sample is cut out using a microtome with diamond teeth, and the tomographic morphology of the toner is measured using a transmission electron microscope (TEM). Method. In the present invention, it is preferable to use a ruthenium tetroxide dyeing method in order to provide a contrast between materials by utilizing a slight difference in crystallinity between the low softening point substance used and the resin constituting the outer shell.

As the outer shell resin used in the present invention, generally used styrene- (meth) acrylic copolymers, polyester resins, epoxy resins and styrene-butadiene copolymers can be used. In the polymerization method, those monomers are preferably used. Specifically, styrene monomers such as styrene, o- (m-, p-)-methylstyrene and m (p-)-ethylstyrene; methyl (meth) acrylate, ethyl (meth) acrylate, Propyl (meth) acrylate, butyl (meth) acrylate, octyl (meth) acrylate, dodecyl (meth) acrylate, stearyl (meth) acrylate, behenyl (meth) acrylate, 2-ethylhexyl (meth) acrylate (Meth) acrylate monomers such as dimethylaminoethyl (meth) acrylate and diethylaminoethyl (meth) acrylate; ene-based monomers such as butadiene, isoprene, cyclohexene, (meth) acrylonitrile and acrylamide The body is preferably used.

These can be used alone or in general in the published Polymer Handbook, 2nd edition III-P139-192.
Monomers are appropriately mixed and used so that the theoretical glass transition temperature (Tg) described in (John Wiley & Sons) indicates 40 to 75 ° C. If the theoretical glass transition temperature is lower than 40 ° C., problems arise in terms of the storage stability of the toner and the durability stability of the developer. On the other hand, if the theoretical glass transition temperature exceeds 75 ° C., the fixing point rises. In the case of (1), the color mixture of the toners of the respective colors is insufficient, and the color reproducibility is poor. Further, the transparency of the OHP image is remarkably reduced, which is not preferable from the viewpoint of high image quality.

The molecular weight of the outer shell resin is measured by GPC (gel permeation chromatography). As a specific GPC measurement method, the toner is extracted in advance with a toluene solvent using a Soxhlet extractor for 20 hours, and then the toluene is distilled off with a rotary evaporator. After washing sufficiently by adding an organic solvent which cannot be dissolved, for example, chloroform, etc., the solution dissolved in THF (tetrahydrofuran) was filtered through a solvent-resistant membrane filter having a pore diameter of 0.3 μm. And the column configuration was A-801, 802, 80 manufactured by Showa Denko
3, 804, 805, 806 and 807 can be connected to measure the molecular weight distribution using a standard polystyrene resin calibration curve.
The number average molecular weight (Mn) of the obtained resin component is 5000
And the ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) is 2 to 100
Is preferred for the present invention.

In the present invention, in the case of producing a toner having a core / shell structure, it is particularly preferable to add a polar resin in addition to the outer shell resin in order to incorporate a low softening point substance in the outer shell resin. preferable. As the polar resin used in the present invention, a copolymer of styrene and (meth) acrylic acid, a maleic acid copolymer, a saturated polyester resin and an epoxy resin are preferably used. The polar resin is
Those having no unsaturated group capable of reacting with the outer shell resin or monomer in the molecule are particularly preferred. If a polar resin having an unsaturated group is included, a cross-linking reaction occurs with the monomer forming the outer shell resin layer. It is disadvantageous and not preferred.

In the present invention, an outermost resin layer may be further provided on the surface of the toner.

The glass transition temperature of the outermost resin layer is designed to be equal to or higher than the glass transition temperature of the outer resin layer in order to further improve the blocking resistance, and is further crosslinked so as not to impair the fixability. Is preferred. The outermost resin layer preferably contains a polar resin and a charge control agent for improving the chargeability.

The method for providing the outermost shell layer is not particularly limited, but includes, for example, the following methods.

After or after the end of the polymerization reaction, if necessary, a monomer composition in which a polar resin, a charge control agent, a cross-linking agent, and the like are dissolved and dispersed is added to the reaction system, and the resulting mixture is adsorbed on polymer particles to start polymerization. A method of performing polymerization by adding an agent.

If necessary, emulsion polymerization particles or soap-free polymerization particles formed from a monomer composition containing a polar resin, a charge control agent, a crosslinking agent, etc., are added to the reaction system, and aggregated on the surface of the polymerization particles. Method of fixing by heat or the like according to the conditions.

A method in which emulsion polymerized particles or soap-free polymerized particles formed from a monomer composition containing a polar resin, a charge control agent, a cross-linking agent, and the like, if necessary, are dry-mechanically fixed to the toner particle surfaces.

On the other hand, when iron powder, copper-zinc-ferrite, nickel-zinc-ferrite, etc., which are conventionally preferably used as a magnetic carrier constituting the two-component developer of the present invention, are used, the electrophotographic photoreceptor can be used. Is easily disturbed.

As the carrier core material, a magnetite-containing polymerized resin carrier produced by a suspension polymerization method is preferable.

As the polymerized resin carrier, in addition to Fe ₃ O ₄ , Fe ₂ O ₃ , Al ₂ O ₃ , SiO ₂ , CaO, Sr
O, MgO, Li ₂ O, preferably contain MnO, or mixtures thereof.

The amount a of Fe ₃ O ₄ is preferably 0.2 to 0.8 (weight ratio) based on all oxides.

In the above formula (I), when x is less than 0.2 and when the amount a of Fe ₃ O ₄ in the polymerized resin carrier is less than 0.2, the magnetic properties are lowered and the carrier scattering and The surface of the photoreceptor is easily damaged, and x is 0.95
If the value exceeds a or exceeds 0.8, the resistance of the carrier core material tends to be low, and a large amount of resin or the like must be coated on the surface of the core material, resulting in coalescence of carrier particles. It becomes easy and is not preferred.

The polymerized resin carrier can be easily formed into a spherical shape and a sharp particle size distribution can be achieved due to its manufacturing method. Therefore, even if the particle size is smaller than that of a normal ferrite carrier, the carrier can be applied to the photosensitive member. It is advantageous for adhesion. Therefore, the 50% particle size of the carrier is 10 to 4
It is good to have 5 μm, preferably 15 to 40 μm.

As the resin for coating the surface of the magnetic carrier core material particles of the present invention, a specific crosslinkable silicone resin, fluorine resin or acrylic resin can be preferably used.

As a method for forming a resin coating layer on the surface of the magnetic carrier core particles, the resin composition is dissolved in an appropriate solvent, and the magnetic carrier core particles are immersed in the obtained solution.
Thereafter, a method of removing the solvent, drying and baking at a high temperature, or suspending the magnetic carrier core material particles in a fluidizing system,
A method in which a solution in which the resin composition is dissolved is sprayed and applied, followed by drying and high-temperature baking, and a method in which magnetic carrier core particles are simply mixed with a resin composition powder or an aqueous emulsion can be used.

In the present invention, 0.1 to 5 parts by weight, preferably 0.1 to 5 parts by weight of water is contained in 100 parts by weight of a solvent containing 5% by weight or more, preferably 20% by weight or more of a polar solvent such as ketones and alcohols. A method using a mixed solvent containing 3 to 3 parts by weight is preferable for firmly attaching the reactive silicone resin to the magnetic carrier core material particles. If the amount of water is less than 0.1 part by weight, the hydrolysis reaction of the reactive silicone resin is not sufficiently performed, and it is difficult to coat the magnetic carrier core material particles with a thin layer and evenly. Control becomes difficult, and conversely, the coating strength decreases.

In the present invention, when a two-component developer is prepared by mixing a carrier and a toner, the mixing ratio is 1 to 15% by weight, preferably 3 to 15% by weight, as the toner concentration in the two-component developer. 12% by weight, more preferably 5 to
Good results are usually obtained at 10% by weight. If the toner density is less than 1% by weight, the image density tends to be low.
If the content is more than 10% by weight, fog and scattering in the machine may be increased, and the useful life of the two-component developer may be shortened.

On the other hand, when an image is formed using a one-component developer, the toner carrier has the function of the carrier.

This will be described in more detail. FIG. 3 shows an example of a developing device in the case of performing non-magnetic one-component development using the toner of the present invention, but is not necessarily limited to this. Reference numeral 171 denotes an electrophotographic photosensitive member, and a latent image is formed by an electrophotographic process unit or an electrostatic recording unit (not shown). Reference numeral 172 denotes a developer carrier, which is preferably made of an elastic rubber sleeve such as silicone rubber, urethane rubber, styrene-butadiene rubber, and polyamide resin. In the present invention, an organic resin may be contained, or organic fine particles or inorganic fine particles may be dispersed in order to have a suitable volume resistance value as required.

The non-magnetic one-component toner is stored in the hopper 173, and is supplied onto the developer carrier by the supply roller 174. The supply roller 174 also removes the toner on the developer carrier after development. The toner supplied on the developer carrier is uniformly and thinly applied by the developer application blade 175. 176 is a power supply.

The contact pressure between the developer application blade and the developer carrier is 3 to 250 g as a linear pressure in the sleeve generatrix direction.
/ Cm, preferably 10 to 120 g / cm is effective. If the contact pressure is less than 3 g / cm, it becomes difficult to apply the toner uniformly, and the charge amount distribution of the toner becomes broad, causing fogging and scattering. The contact pressure is 25
If it exceeds 0 g / cm, a large pressure is applied to the toner, so that the toners are aggregated or pulverized. By adjusting the contact pressure to 3 to 250 g / cm, it becomes possible to loosen the agglomeration peculiar to the small particle size toner, and it is possible to instantly increase the charge amount of the toner. The developer coating blade is preferably made of a material of a triboelectric series suitable for charging the toner to a desired polarity. In the present invention, silicone rubber, urethane rubber, styrene-butadiene rubber and the like are preferred. Further, it may be coated with a polyamide resin or the like. Use of a conductive rubber or the like is preferable because the toner can be prevented from being excessively charged.

In the non-magnetic one-component development proposed in the present invention, in order to obtain a sufficient image density, the thickness of the toner layer on the developer carrier is adjusted by the distance between the developer carrier and the electrophotographic photosensitive member. Although it may be smaller than the gap length and an AC voltage may be applied to this gap, it is particularly preferable in the present invention that the residual toner after transfer is favorably recovered and reused in the development area. Is preferably performed by applying a developing bias while contacting with the electrophotographic photosensitive member. In this case, the developing bias may be a DC voltage alone or an AC voltage as necessary.

Next, an electrophotographic apparatus of the present invention using the two-component developer will be described.

In this electrophotographic apparatus, a two-component developer having a toner and a carrier is circulated and conveyed on a developer carrier, and an electrostatic latent image on the electrophotographic photoreceptor is developed on the developer carrier in a development area. Developing with a two-component developer toner.

In the electrophotographic apparatus according to the present invention, of the developing sleeve (developer carrying member) and the magnet roller incorporated therein, for example, the magnet roller is fixed and the developing sleeve is rotated alone to form a two-component developing device. The developer is circulated and transported on a developing sleeve, and the electrostatic latent image held on the surface of the electrophotographic photosensitive member is developed by the two-component developer.

The magnetic characteristics of the carrier are affected by the magnet roller built in the developing sleeve, and greatly affect the developing characteristics and transportability of the developer.

In the electrophotographic apparatus of the present invention, the magnet roller has a pole configuration having repulsive poles, the magnetic flux density in the developing area is 500 to 1200 gauss,
When the carrier has a saturation magnetization of 20 to 50 Am ² / kg, the uniformity of the image and the reproducibility of the gradation are excellent.

In the electrophotographic apparatus of the present invention, it is preferable to apply a developing bias in the developing area to develop the electrostatic latent image with a two-component developer toner.

A particularly preferred developing bias will be described below in detail.

In the electrophotographic apparatus of the present invention, since a developing electric field is formed in a developing area between the electrophotographic photosensitive member and the developer carrier, a discontinuous AC component as shown in FIG. It is preferable to develop the electrostatic latent image on the electrophotographic photosensitive member with the toner of the two-component developer on the developer carrying member by applying a developing voltage having the following. Specifically, the developing voltage includes a first voltage for directing toner from the electrophotographic photosensitive member to the developer carrying member in a developing region, and a second voltage for directing toner from the developer carrying member to the electrophotographic photosensitive member. ,
A first voltage and a third voltage between the second voltage.

Further, the first voltage and the second voltage are larger than the total time for applying the first voltage and the second voltage to the developer carrier, that is, the time (T ₁ ) during which the AC component is acting. And the time during which the third voltage is applied to the developer carrier, that is,
It is particularly preferable to lengthen the rest time (T ₂ ) of the AC component for the purpose of rearranging the toner on the latent image carrier and faithfully reproducing the latent image.

Specifically, an electric field in which toner travels from the electrophotographic photosensitive member to the developer carrying member between the electrophotographic photosensitive member and the developer carrying member in the developing area, and the electric field from the developer carrying member to the electrophotographic photosensitive member After the electric field toward the toner is formed at least once, in the image area, the toner moves from the developer carrier to the electrophotographic photoconductor, and in the non-image area, the electric field moves from the electrophotographic photoconductor to the developer carrier in the non-image area. The electrostatic latent image on the electrophotographic photosensitive member is developed with the toner of the two-component developer carried on the developer carrying member by forming the electrophotographic photosensitive member over time. In the image area, the toner moves from the developer carrier to the electrophotographic photosensitive member, and the non-image occurs due to the total time (T ₁ ) for forming the electric field toward the toner and the electric field causing the toner from the developer carrier to the electrophotographic photosensitive member. In the department, It is preferable that toner is longer towards the time to form the electric field directed to the developer carrying member from the electrophotographic photosensitive member (T _2).

In the developing method of forming and developing the above-mentioned specific developing electric field, that is, an alternating electric field, when the developing is performed using the developing electric field for periodically turning off the alternating electric field, the adhesion of the carrier to the electrophotographic photosensitive member becomes more difficult. Less likely to occur. The reason for this is
Although it is not clear yet, it is considered as follows.

In the conventional continuous sine wave or rectangular wave, if the electric field strength is increased in order to achieve high image quality, the toner and the carrier are reciprocated between the latent image carrier and the developer carrier as a unit. As a result, the carrier strongly rubs against the electrophotographic photoreceptor, and carrier adhesion occurs. This tendency becomes more remarkable as the amount of the fine powder carrier increases.

However, when the above-described specific AC voltage is applied, the toner or carrier reciprocates between the developer carrying member and the electrophotographic photosensitive member in one pulse so that the reciprocating motion does not occur. When the potential difference V _cont between the surface potential of the body and the DC component of the developing bias is V _cont <0, V _cont acts to fly the carrier from the developer carrier, but the magnetic properties of the carrier and the development of the magnet roller By controlling the magnetic flux density in the region, carrier adhesion can be prevented. When V _cont > 0, the force of the magnetic field and V _cont work to attract the carrier to the developer carrier side, and no carrier adhesion occurs. .

An electrophotographic apparatus capable of forming an image with the two-component developer of the present invention will be described with reference to FIG.

In FIG. 2, the electrophotographic apparatus has an electrophotographic photosensitive member (photosensitive drum) 342 and a developing device 4
The inside of the developing container 16 is separated into a developing chamber (first
Chamber) R ₁ and stirring chamber (second chamber) is partitioned into a R _2, stirring chamber R
The _second upper toner storage chamber R ₃ are formed at a partition wall 17. The developing chamber R ₁ and the stirring chamber R ₂ is accommodated developer 19, the replenishing toner (non-magnetic toner) 18 is stored in the toner storage chamber R _3. Note that the toner storage chamber R ₃ replenishing opening 20 is provided, the amount of the replenishment toner 18 commensurate to the consumed toner is dropped replenished to the stirring chamber R in ₂ through the supply opening 20.

[0172] A conveying screw 13 in the developing chamber R ₁ is formed, the developer 19 in the developing chamber R ₁ by the driving rotation of the conveying screw 13 is conveyed toward the longitudinal direction of the developing sleeve 11 . Similarly, the conveying screw 14 is provided in the storage chamber R _2, conveying screws 14
By rotation of the toner that has fallen into the stirring chamber R ₂ from the supply port 20 to convey in the longitudinal direction of the developing sleeve 11.

The developer 19 is a two-component developer having a non-magnetic toner 19a and a development carrier 19b.

An opening is provided in a portion of the developing container 16 close to the photosensitive drum 342, and the developing sleeve 11 projects outside from the opening, and a gap is provided between the developing sleeve 11 and the photosensitive drum 342. ing. A bias applying unit (not shown) for applying a bias is arranged on the developing sleeve 11 formed of a non-magnetic material.

As described above, the magnet roller as a magnetic field generating means fixed in the developing sleeve 11, that is, the magnet 12, is composed of the developing magnetic pole N and the magnetic pole S located downstream thereof.
And magnetic poles N, S, and S for transporting the developer 19. The magnet 12 is disposed in the developing sleeve 11 such that the developing magnetic pole S faces the photosensitive drum 342. The developing magnetic pole S forms a magnetic field near the developing section between the developing sleeve 11 and the photosensitive drum 342, and the magnetic field forms a magnetic brush.

The regulating blade 15 which is disposed below the developing sleeve 11 and regulates the layer thickness of the developer 19 on the developing sleeve 11 is an end portion of the non-magnetic blade 15 made of a non-magnetic material such as aluminum or SUS316. The distance between the surface and the surface of the developing sleeve 11 is 300 to 1000 μm, preferably 400 to 900 μm. If this distance is smaller than 300 μm, the magnetic carrier is clogged during this time, and the developer layer is likely to be uneven, and the developer required for good development cannot be applied, resulting in low density and many unevenness. There is a problem that only a developed image can be obtained. In order to prevent non-uniform application (so-called blade jam) due to unnecessary particles mixed in the developer, the thickness is preferably 400 μm or more. If the thickness is larger than 1000 μm, the amount of the developer applied on the developing sleeve 11 increases, and a predetermined thickness of the developer layer cannot be regulated. As a result, the amount of magnetic carrier particles attached to the photosensitive drum 342 increases, and the There is a problem in that the development regulation by the magnetic blade 15 is weakened, the toner tribo is insufficient, and fogging is likely to occur.

Even when the developing sleeve 11 is driven to rotate in the direction of the arrow, the magnetic carrier particle layer is separated from the sleeve surface by the balance between the restraining force based on the magnetic force or gravity and the conveying force in the moving direction of the developing sleeve 11. Movement slows down. Of course, some fall under the influence of gravity.

Therefore, by appropriately selecting the arrangement positions of the magnetic poles N and N and the fluidity and magnetic properties of the developing carrier particles, the closer the developing carrier particle layer is to the developing sleeve, the closer the magnetic pole N becomes.
To form a moving layer. Due to the movement of the developing carrier particles, the developer is conveyed to the developing area with the rotation of the developing sleeve 11 and is used for development.

After the photosensitive member 342 is contact-charged by the magnetic particles 502 carried on the charging magnetic particle holding member 500, an electrostatic latent image is formed by exposure means (not shown), and a developed image is formed by toner. .

Hereinafter, methods for measuring various physical properties according to the present invention will be described.

(1) Measurement of Magnetic Characteristics of Carrier A BHU-60 type magnetization measurement device (manufactured by Riken Keisoku) is used. About 1.0 g of a measurement sample is weighed, packed in a cell having an inner diameter of 7 mmφ and a height of 10 mm, and set in the above-mentioned apparatus. In the measurement, an applied magnetic field is gradually applied to change the maximum to 3,000 Oe. Next, the applied magnetic field is decreased, and finally a hysteresis curve of the sample is obtained on the recording paper. From this, the saturation magnetization, residual magnetization, and coercive force are obtained.

(2) Measurement of Volume Resistance Value of Carrier The measurement was performed using the cell shown in FIG. That is, the cell A is filled with a sample, the electrodes 31 and 32 are arranged so as to be in contact with the filled sample 33, a DC voltage of 1000 V is applied between the electrodes, and the current flowing at that time is measured by an ammeter. Was. The measurement conditions were as follows: temperature 23 ° C., relative humidity 6
2cm contact area of the filled sample with the cell in 5% environment
^{2. The} thickness (d) is 3 mm and the load on the upper electrode is 15 kg.

(3) Measurement of Toner Particle Size (Weight Average Particle Size) The average particle size and particle size distribution of the toner can be measured using a Coulter Counter TA-II or a Coulter Multisizer (manufactured by Coulter Inc.). In the invention, a Coulter Multisizer (manufactured by Coulter Inc.) is used, and an interface (manufactured by Nikkaki) for outputting the number distribution and volume distribution and a PC9801 personal computer (manufactured by NEC) are connected. Prepare 1% NaCl aqueous solution. For example, IS
OTON R-II (manufactured by Coulter Scientific Japan) can be used. As a measuring method, a surfactant, preferably an alkylbenzene sulfonate, is used as a dispersant in 100 to 150 ml of the electrolytic aqueous solution.
Add 1 to 5 ml, and further add 2 to 20 mg of the measurement sample.
The electrolytic solution in which the sample was suspended was subjected to dispersion treatment for about 1 to 3 minutes using an ultrasonic disperser, and a 100 μm aperture was used as an aperture by the Coulter Multisizer.
The volume distribution and the number distribution were calculated by measuring the volume and the number of the toner particles having a size of μm or more. Then, the volume average particle diameter (D _v : the median value of each channel is a representative value of the channel), the weight average particle diameter (D ₄ ), and the number distribution were determined from the volume distribution according to the present invention. The number-based length average particle diameter (D ₁ ) and the volume-based particle ratio determined from the volume distribution) and the number-based particle ratio determined from the number distribution were determined.

(4) Measurement of Weight Average Particle Size of External Additive An appropriate amount of a sample was put into 30 to 50 ml of distilled water to which a trace amount of a surfactant was added, and an ultrasonic generator (Tomy Seiko U.S.A.)
(D-200 type) with an output of 2 to 6 for 2 to 5 minutes. Transfer the resulting dispersion to the cell, and after the air bubbles escape,
It is set on a Coulter counter N4 (manufactured by Coulter) whose measurement temperature has been set to 50 ° C. in advance. After a lapse of 10 to 20 minutes to bring the sample to a constant temperature, the measurement is started, and the volume average particle size distribution and the weight average particle size are determined.

(5) Measurement of hydrophobicity of external additive 0.2 g of a sample is added to 50 ml of water in a 250 ml Erlenmeyer flask. While stirring the solution with a magnetic stirrer, methanol is added dropwise using a burette. The ratio of the amount of methanol used until all the samples are suspended in the solution to the total amount of methanol and water is defined as the degree of hydrophobicity of the external additive.

(6) Measurement of Volume Resistance of Surface Layer The volume resistance of the surface layer of the electrophotographic photoreceptor and the surface layer of the toner carrier in the present invention is determined by measuring the volume resistivity of a polyethylene terephthalate (PET) film having gold deposited on the surface. A layer (thickness: 3 μm) similar to the surface layer was formed on the upper layer, and this layer was used as a volume resistance measuring device (4140B pA manufactured by Hewlett-Packard Company).
MATER) and a voltage of 100 V is applied in an environment of a temperature of 23 ° C. and a relative humidity of 65% for measurement.

[0187]

EXAMPLES Examples of the present invention will be shown below, but the present invention is not limited to these examples. “Parts” indicates “parts by weight”.

(Production Example 1 of Magnetic Particles for Charging) 8 parts of MgO,
After 8 parts of MnO, 4 parts of SrO and 80 parts of Fe ₂ O ₃ were each atomized, water was added and mixed, and the mixture was granulated.
After adjusting the particle size, ferrite particles having an average particle size of 20 μm (saturation magnetization 63 Am ² / kg, coercive force 55
Oersted).

[0189] A solution obtained by mixing 100 parts of the above ferrite particles with 10 parts of isopropoxytriisostearoyl titanate (compound (1)) and 10 parts of γ-aminopropyltrimethoxysilane in toluene was used. The surface was treated to be 1 part to obtain magnetic particles a for charging.

The average particle size of the magnetic particles was 20 μm, the volume resistivity was 2 × 10 ⁷ Ωcm, and the weight loss on heating was 0.1% by weight.

(Production Example 2 of Magnetic Particles for Charging) 6 parts of MgO,
Charging magnetic particles b were obtained in the same manner as in Charging Magnetic Particle Production Example 1, except that 5 parts of CaO and 89 parts of Fe ₂ O ₃ were used.

The average particle size of the magnetic particles was 20 μm, the volume resistance was 3 × 10 ¹⁰ Ωcm, the loss on heating was 0.1% by weight, the saturation magnetization was 60 Am ² / kg, and the coercive force was Was 75 Oersted.

(Example 3 of Preparation of Magnetic Particles for Charging) The ferrite particles used in Production Example 1 of magnetic particles for charging were treated in the same manner except that γ-aminopropyltrimethoxysilane was not used. By applying as described above, charging magnetic particles c were obtained.

The average particle size of the particles was 21 μm, the volume resistivity was 4 × 10 ⁸ Ωcm, and the heat loss was 0.0
5% by weight, the saturation magnetization is 60 Am ² / kg,
The coercive force was 75 Oersted.

(Production Example 4 of Magnetic Particles for Charging) 8 parts of NiO,
Magnetic particles for charging d were obtained in the same manner as in Production Example 1 of magnetic particles for charging, except that 8 parts of Li ₂ O, 4 parts of ZnO and 80 parts of Fe ₂ O ₃ were used.

The average particle size of the particles was 18 μm, the volume resistivity was 3 × 10 ³ Ωcm, and the heat loss was 0.0
5% by weight, the saturation magnetization is 55 Am ² / kg,
The coercive force was 100 Oe.

(Production Example 5 of Magnetic Particles for Charging) As ferrite particles, the average particle diameter was 65 μm, and the volume resistivity was 4 × 10 ⁷ Ω.
cm, a saturation magnetization of 61 Am ² / kg, and a coercive force of approximately 0, using copper-zinc ferrite particles.
Except that 0.05 parts of butyltriethoxysilane was used,
Similarly, magnetic particles e for charging were obtained.

The average particle size of the particles is 23 μm, the volume resistance value is 4 × 10 ⁷ Ωcm, and the heat loss is 0.0
It was 5% by weight.

(Photoreceptor Production Example 1) The photoreceptor is a photoreceptor using an organic photoconductive material for negative charging, and five functional layers are provided on a φ30 mm aluminum cylinder.

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

The second layer is a positive charge injection preventing layer (undercoat layer), which serves to prevent positive charges injected from the aluminum cylinder from canceling out negative charges charged on the surface of the photoreceptor. This is a medium resistance layer having a thickness of about 1 μm, the resistance of which is adjusted to about 10 ⁶ Ωcm by 66-610-12-nylon and methoxymethylated nylon.

The third layer is a charge generation layer, which is a layer having a thickness of about 0.3 μm in which a disazo pigment is dispersed in a resin, and generates positive and negative charge pairs upon exposure.

The fourth layer is a charge transporting layer, a layer having a thickness of 20 μm in which hydrazone is dispersed in a polycarbonate resin, and is a P-type semiconductor. Therefore, the negative charges charged on the photoreceptor surface cannot move through this layer, and only the positive charges generated in the charge generation layer can be transported to the photoreceptor surface.

The fifth layer is a charge injecting layer, which has a particle size of about 0.01 to increase the contact time between the photo-curable member and the photosensitive member by increasing the contact time between the photo-curable acrylic resin and SnO ₂ ultrafine particles. This is a 3.5 μm thick layer in which 0.25 μm tetrafluoroethylene resin particles are dispersed. Specifically, 160 parts of SnO ₂ particles having a particle diameter of about 0.03 μm, which had been made oxygen-deficient to have a low resistance, with respect to 100 parts of the resin, further 30 parts of the ethylene tetrafluoride resin particles, and 1 part of the dispersant. Two parts are dispersed.

As a result, the volume resistivity of the surface layer of the photoreceptor 1 was reduced to 3 × 10 ¹¹ Ωcm, compared with 5 × 10 ¹⁵ Ωcm for the charge transport layer alone.

(Photoreceptor Production Example 2) Photoreceptor 2 was produced in the same manner as in Photoreceptor Production Example 1, except that 300 parts of SnO ₂ particles were used for 100 parts of the photocurable acrylic resin.

As a result, the volume resistance of the surface layer of the photosensitive member was reduced to 5 × 10 ⁷ Ωcm.

(Photoreceptor Production Example 3) Photoreceptor 3 having a surface layer having a volume resistance of 4 × 10 ¹⁵ Ωcm was prepared in the same manner except that SnO ₂ was not used.

[Production Example 1 of Cyan Toner] Ion-exchanged water 7
To 10 g, was charged 0.1M-Na ₃ PO ₄ aqueous solution 450 g, followed by heating to 60 ° C., using a TK-type homomixer (manufactured by Tokushu Kika Kogyo), and stirred at 12000 rpm.
To this, 68 g of a 1.0 M CaCl ₂ aqueous solution was gradually added, and HCl was added to obtain an aqueous medium containing a pH 6 calcium phosphate compound.

On the other hand, (monomer) styrene 165 g n-butyl acrylate 35 g (colorant) I. After finely dispersing 15 g of Pigment Blue 15: 3 with a ball mill, (charge control agent) salicylic acid metal compound 3 g (polar resin) saturated polyether resin 10 g (release agent) 50 g of ester wax (melting point 70 ° C.) was added, and the mixture was heated to 60 ° C. Using a heated TK homomixer (manufactured by Tokushu Kika Kogyo), the mixture was uniformly dissolved and dispersed at 12000 rpm. 10 g of a polymerization initiator 2,2′-azobis (2,4-dimethylvaleronitrile) was dissolved therein,
A polymerizable monomer composition was prepared.

The polymerizable monomer composition was put into the aqueous medium, and the mixture was stirred at 10,000 rpm for 10 minutes with a TK homomixer at 60 ° C. in an N ₂ atmosphere. Granulated. Thereafter, the mixture was reacted at 60 ° C. for 5 hours while stirring with a paddle stirring blade while maintaining the pH at 6, and further, potassium persulfate was added and the temperature was raised to 80 ° C.
The reaction was performed for 5 hours. After completion of the polymerization reaction, the remaining monomer was distilled off under reduced pressure, and after cooling, hydrochloric acid was added to dissolve calcium phosphate at pH 11, followed by filtration, washing with water, and drying.
Sharp colored suspension particles having a weight average particle size of 7.2 μm were obtained.

To 100 parts of the obtained particles, anatase-type hydrophobic titanium oxide (7 × 10 ⁹ Ωcm) having an average particle size of 0.05 μm and a BET of 100 m ² / g treated with isobutyltrimethoxysilane in an aqueous medium was used. 0.5 part, and average particle size 0.06μ treated with hexamethyldisilazane
The suspension polymerization toner 1 was obtained by externally adding 0.7 part of silica fine powder having a m.BET of 40 m ² / g. The weight average particle size of this toner is 7.2 μm, SF-1 is 108 and SF-2 is 112.
Met.

[Cyan Toner Production Example 2] Polyester resin obtained by condensing propoxylated bisphenol with fumaric acid and trimellitic acid 100 parts Phthalocyanine pigment 4 parts Aluminum compound of di-tert-butylsalicylic acid 4 parts Low molecular weight polypropylene 4 Part The above raw materials are sufficiently premixed by a Henschel mixer, melt-kneaded by a twin-screw extruder, cooled, coarsely pulverized to about 1 to 2 mm using a hammer mill, and then finely pulverized by an air jet method. Finely ground. Further, after classifying the obtained finely pulverized product, it was subjected to spheroidizing treatment by mechanical impact to obtain a blue powder (toner particles) having a weight average particle size of 5.8 μm.

[0214] 100 parts of the above blue powder and n-
_{C 4 H 9 -Si- (OCH 3} ) 3 a weight average particle size 0.05μm treated with 20 parts per hydrophilic anatase type titanium oxide fine powder 100 parts, fine anatase type titanium oxide 55% hydrophobicity 1.5 parts of powder (3 × 10 ¹⁰ Ωcm) was mixed with a Henschel mixer to obtain cyan toner 2. The weight average particle size of this toner is 5.8 μm, SF-1 is 132,
SF-2 was 128.

(Development carrier production example 1) After mixing and dispersing a phenol / formaldehyde monomer (50:50) in an aqueous medium, 100 parts of the monomer was subjected to a surface treatment with an epoxy group-containing silane coupling agent at 0.25 μm.
Of magnetite particles and 400 parts of 0.6 μm hematite particles are uniformly dispersed, and the monomer is polymerized while appropriately adding ammonia. The magnetic material-containing spherical magnetic resin carrier core material (average particle diameter 33 μm, saturation magnetization 38 Am ²⁾
/ Kg). This core material was treated at 50 ° C. using 0.1 part of γ-aminopropyltrimethoxysilane in a coating machine (Nauta mixer manufactured by Hosokawa Micron Co., Ltd.).

On the other hand, toluene 20 parts, butanol 20
Parts, 20 parts of water, and 40 parts of ice in a four-necked flask, and while stirring, 15 mol of CH ₃ SiCl ₃ and (CH ₃ ) ₂ SiC
40 parts of a mixture with 10 mol of l ₂ was added, and the mixture was further stirred for 30 minutes, and then subjected to a condensation reaction at 60 ° C. for 1 hour. Thereafter, the siloxane as a condensation product was sufficiently washed with water and dissolved in a mixed solvent of toluene, methyl ethyl ketone and butanol to prepare a silicone varnish having a solid content of 10%.

To the silicone varnish, 2.0 parts of ion-exchanged water and 1.0 part of siloxane solids
Parts of the following aminosilane coupling agent

[0218]

Embedded image And 5.0 parts of a silane coupling agent

[0219]

Embedded image Was added simultaneously to prepare a developing carrier coating solution I. This solution I was applied to 100 parts of the above-mentioned carrier core material using a coating machine (manufactured by Hosokawa Micron Co., Ltd .: Nauter Mixer) so that the resin coating amount was 0.5 part, to obtain a development carrier I. The 50% particle size of this development carrier was 33 μm, and the volume resistivity was 2 × 10 ¹³ Ωcm. The development carrier has a saturation magnetization of 38 Am ² / kg and a coercive force of 4 Am ² / kg.
0 Oersted.

(Development carrier production example 2) 15 parts of MgO,
Developed carrier II having a 50% particle size of 35 μm and a volume resistivity of 4 × 10 ¹² Ωcm was obtained in the same manner as in Carrier Production Example 3 except that 10 parts of CaO and 75 parts of Fe ₂ O ₃ were used. The saturation magnetization of this development carrier is 51 Am ² / kg
The coercive force was 7 Oe.

(Development Carrier Production Example 3) A 50% particle size was 34 μm, and a volume resistivity was the same as in Carrier Production Example 1 except that a vinylidene fluoride / methyl methacrylate copolymer was used instead of the silicone varnish. Is 5 × 10 ¹⁴
Ωcm of development carrier III was obtained. The saturation magnetization of this development carrier was 38 Am ² / kg, and the coercive force was 10 Oe.

(Electrophotographic Apparatus) A digital copying machine using a laser beam as an electrophotographic apparatus (Canon: GP
55) was prepared. An outline of the apparatus includes a corona charger as a charging unit of the photoconductor, a one-component developing unit employing a one-component jumping developing method as a developing unit, a corona charger as a transfer unit, a blade cleaning unit,
An exposure means is provided before charging. The charger, the cleaning means, and the photoreceptor are an integrated unit (process cartridge). Process speed is 150mm /
s. This digital copying machine was modified as shown in FIG.

The development part was changed from one-component jumping development to
The two-component developer was modified so that it could be used. Further, a 16φ conductive non-magnetic sleeve 500 including a magnet roller 501 is disposed on a charging portion, and a charging magnetic brush 502 is provided.
(FIG. 2). The gap between the conductive sleeve for charging and the photoconductor was set to 0.5 mm. The developing bias superimposes the component of FIG. 5 on the DC component of -300V. Further, the transfer means using a corona charger was changed to a roller transfer method, and the pre-charge exposure means was removed.

Further, the cleaning blade was removed to obtain a cleanerless copying machine.

Next, instead of the laser part of the exposure part, LED
An exposure unit was provided, and an electrode for forming an electric field was provided above / downstream of the exposure unit. The applied voltage was -1.5 kV.

Example 1 A cyan developer was prepared by mixing cyan toner 1 and development carrier I at a toner concentration of 8%.

Using the above-described electrophotographic apparatus and the above-described cyan developer, toner scattering / adhesion to the LED section and images were evaluated. However, the peripheral speed of the photoconductor is 150 mm / s,
The peripheral speed of the charger was set to 180 mm / s, a DC / AC electric field (-700 V, 1 kHz / 1.2 kVpp) was applied in a superimposed manner, the cleaning unit was removed, and the developing contrast was set to 300 V, and the reversal contrast with fog was set to -150 V. 32.5 ° C. using the discontinuous alternating electric field of FIG.
/ 85%, and image area ratio 30%
And 50,000 copies were made continuously using the original manuscript of 6%. Table 1 shows the results.

From Table 1, it can be seen that the above-described electrophotographic apparatus has good image quality, small image change due to continuous copying, and very good toner scattering and adhesion. Further, it can be seen that there is no problem due to toner reuse.

The scattering and adhesion of the toner were measured by collecting the lens surface with a Mylar tape and using a Macbeth densitometer RD-918 to indicate the difference from the blank with the Mylar tape alone as the density difference. 0.04 or less is excellent, 0.04 or more and 0.08 or less is good, 0.08 or more and 0.12 or less are acceptable, and 0.12 or more is poor. The image density was measured for a 1.4 density portion of the original image using a Macbeth densitometer RD-918.
A value closer to 1.4 indicates that the original is faithful.
Fog is a reflection densitometer REFLECOMETER MO
DEL TC-6DS (TOKYO DENSHOKU
CO. , LTD). Ds when the average value of the five reflection densities of the white background portion after printing is Ds, and the average value of the five reflection densities of the white background portion before printing is Dr
s-Dr was used as the fog amount. The solid density unevenness was determined by measuring a solid portion of an image at five points using the Macbeth densitometer and subtracting the minimum value from the maximum value. In any case, 0.04 or less is excellent,
A value of more than 0.04 and not more than 0.08 indicates good, a value of more than 0.08 and not more than 0.12 indicates acceptable, and a value of more than 0.12 indicates poor.

Comparative Example 1 An image was formed in the same manner as in Example 1 except that the photosensitive member 2 was used. When 30% of the original document was used, the amount of toner adhered to the lens surface was 20,000 sheets. Was outstanding. Also, in 6% of original documents, toner adhesion was noticeable at 50,000 sheets. This is probably because the resistance of the photoconductor became too low, and the toner could not be sufficiently held on the photoconductor.

Comparative Example 2 An image was formed in the same manner as in Example 1 except that the photoreceptor 3 was used. As a result, although there was no problem with toner adhesion, fog suppression was deteriorated and solid uniformity was deteriorated. This is considered to be because the resistance of the photosensitive member was high and the charging ability by injection was insufficient.

Example 2 An image was formed in the same manner as in Example 1 except that the charging magnetic particles b were used. In continuous copying of 20,000 sheets, good results were obtained as in Example 1. However, when the printing was further continued up to 50,000 sheets, the solid uniformity slightly deteriorated and the fog slightly deteriorated to 0.8 to 1.2%, but at a practically acceptable level. This is presumed to be because the injection property was slightly lowered due to the high resistance.

Example 3 An image was formed in the same manner as in Example 1 except that the magnetic particles c for charging were used. There was no problem with fog. , Was at a level without problems. On the other hand, the toner adhesion was worse than expected for 30% of original documents, but was at a practically acceptable level. This is presumed to be due to the fact that no aminosilane was used as the treating agent, and thus the charge-imparting property to the toner was reduced.

Example 4 An image was formed in the same manner as in Example 1 except that cyan toner 2 was used. In continuous copying of 20,000 sheets, good results were obtained as in Example 1. However, when the printing was further continued up to 50,000 sheets, fog and toner adhesion deteriorated, but were at an acceptable level. This is presumably because the toner shape was slightly distorted, the transfer efficiency was reduced, and the remaining amount of the transfer residual toner was increased.

Comparative Example 3 An image was formed in the same manner as in Example 1 except that the scattering prevention electrode was not used. The image was good at the beginning, but at the time of 20,000 sheets, 30% of the original document was not used. Evaluation was stopped because toner adhesion was conspicuous and unevenness occurred in the image.

Comparative Example 4 An image was formed in the same manner as in Example 1 except that the magnetic particles d were used. As a result, an abnormality occurred in the image from the beginning. This is presumed to be due to the fact that leakage occurred due to the low resistance of the magnetic particles.

Example 5 An image was formed in the same manner as in Example 1 except that magnetic particles e were used. As a result, toner adhesion was slightly observed, and fog suppression was slightly deteriorated at 50,000 sheets. It was at no problem level. This is presumably because the coupling agent has 4 carbon atoms, so that the durable life is slightly reduced.

Example 6 In the same manner as the cyan developer used, a yellow developer
A magenta developer and a black developer were obtained. The electrophotographic apparatus having the configuration shown in FIG. 1 was charged with the above four color developers, and 30,000 sheets of images were produced in the order of yellow, magenta, cyan, and black without using a cleaning unit.
Good results with little change in image density and no fog were obtained. However, the applied voltage and the like are the same as in Example 1, and the method for producing each toner is as follows.

[Production Example of Yellow Toner] I. Pigment Blue 15: 3 and C.I. I. Pigment Yellow 933 parts and Solvent Yellow 1623 parts, except that yellow toner particles were obtained in the same manner as in the production example 1 of the cyan toner. A toner was obtained.

[Production Example of Magenta Toner] I. Magenta toner particles were obtained in the same manner as in Cyan toner production example 1 except that quinacridone pigment was used in place of CI Pigment Blue 15: 3. A toner was obtained.

[Production Example of Black Toner] I. Pigment Blue 15: 3, except that carbon black is used instead of Pigment Blue 15: 3, to obtain black toner particles in the same manner as in Cyan Toner Production Example 1, and similarly mixed with anatase-type titanium oxide fine powder and silica fine powder to obtain black toner particles. A toner was obtained.

[0242]

[Table 1]

[0243]

As described above, according to the present invention, there is no toner scattering to an exposed portion, excellent chargeability for injection into an electrophotographic photoreceptor, and high image quality which does not cause disturbance of a latent image in a development area. And an electrophotographic apparatus and an image forming method with high durability.

[Brief description of the drawings]

FIG. 1 shows a schematic view of an electrophotographic apparatus of the present invention.

FIG. 2 shows a schematic view around the drum of the present invention.

FIG. 3 is a schematic diagram of a developing device when performing non-magnetic one-component development.

FIG. 4 is a schematic sectional view of an apparatus used for measuring the resistance of magnetic particles.

FIG. 5 is a diagram showing an AC voltage used in the embodiment.

FIG. 6 is an explanatory diagram of an apparatus used for measuring a triboelectric charge amount of a toner.

[Explanation of symbols]

 Reference Signs List 4 developing device 11 developing sleeve (developer carrier) 12 magnet roller 18 replenishing toner 19 developer 19a toner 19b carrier 21 transport sleeve 210 LED section (exposure means) 220 electric field forming electrode 230 electric field forming electrode 321 charger 342 Photosensitive drum 500 Sleeve 501 Magnet roller 502 Charged particles (magnetic particles)

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G03G 15/02 101 G03G 9/10 331 15/08 507 352 354 354 15/08 507B (72) Inventor Nobuya Taniuchi 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Yasufumi Katsuta 3-30-2 Shimomaruko 3-chome, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Kikatsu Mizoe Ota, Tokyo Maruko Kushita 3-30-2 Canon Inc. F-term (reference) 2H003 BB11 CC04 EE11 2H005 AA08 AA15 AB09 BA02 BA03 BA06 BA15 CA11 CA12 CA17 CB03 CB04 CB07 CB13 EA02 EA05 EA07 FA02 2H068 AA03 BB06 EB07 AB05 AB82 2H077 AA11 AA37 AC02 AC04 AD02 AD06 AD13 AD36 DB08 EA03 EA14 EA15 GA17

Claims (40)

[Claims] 1. A charging means having (i) a charging member for contacting and charging the surface of the electrophotographic photoreceptor around the electrophotographic photoreceptor; Exposure means for forming an electrostatic latent image by exposure by the exposure means; (iii) developing means for developing the electrostatic latent image with toner to form a toner image; and (iv) intermediate transfer of the toner image. An electrophotographic apparatus in which transfer means for transferring to a transfer material via a body or without a body is sequentially arranged along a moving direction of the surface of the electrophotographic photosensitive member; Has a volume resistance value of 10 ⁸ to 10 ¹⁴ Ωcm, the charging member has a volume resistance value of 10 ⁴ to 10 ⁹ Ωcm, and an upstream and / or downstream side of the exposure unit is provided with a toner exposure unit. Electric field type with electrodes to prevent contamination Electrophotographic apparatus comprising means. 2. The charging means has magnetic particles for charging and a magnetic particle holding member for forming a charged magnetic brush by magnetically constraining the magnetic particles, and has a volume resistance value of 10 ^4.
2. The electrophotographic apparatus according to claim 1, wherein the charging member having a charge density of from 10 to 10 ⁹ Ωcm is the magnetic particles for charging. 3. A cleaning device for recovering and storing toner remaining on an electrophotographic photosensitive member after transfer between a transfer device and a charging device and between a charging device and a developing device. 3. The electrophotographic apparatus according to 2. 4. The magnetic particles for charging have 6
The electrophotographic apparatus according to claim 2, further comprising a coupling agent having a linear alkyl group having the above carbon number. 5. The electrophotographic apparatus according to claim 2, wherein the magnetic particles for charging have a coupling agent having an amino group on a surface thereof. 6. A magnetic particle for charging, comprising:
The electrophotographic apparatus according to claim 2, further comprising a coupling agent having a linear alkyl group having the above carbon number and a coupling agent having an amino group. 7. The electrophotographic apparatus according to claim 4, wherein the amount of the coupling agent is 0.0001 to 0.5% by weight based on the total mass of the magnetic particles. 8. The electrophotographic apparatus according to claim 4, wherein the central element of the coupling agent is selected from titanium, aluminum and silicon. 9. The electrophotographic apparatus according to claim 2, wherein the average particle size of the magnetic particles is 5 to 100 μm. 10. The electrophotographic apparatus according to claim 2, wherein the average particle size of the magnetic particles is 5 to 50 μm. 11. The electrophotographic apparatus according to claim 2, wherein the magnetic particles have an average particle size of 5 to 35 μm. 12. The developing means includes a toner having an external additive, the toner having a weight average particle size of 1 to 9 μm,
The electrophotographic apparatus according to claim 1, wherein the external additive has a weight average particle size of 0.012 to 0.4 μm. 13. The toner according to claim 1, wherein SF-1 of the toner is 100 to 160, and SF-2 of the toner is 100 to 140.
3. The electrophotographic apparatus according to any one of 2. 14. The toner according to claim 1, wherein SF-1 of the toner is 100 to 140, and SF-2 of the toner is 100 to 140.
3. The electrophotographic apparatus according to any one of 2. 15. The electrophotographic apparatus according to claim 1, wherein the developing means is a reversal developing means. 16. An electrophotographic apparatus according to claim 1, wherein said developing means has a two-component developer having a toner and a magnetic carrier. 17. The electrophotographic apparatus according to claim 16, wherein the magnetic carrier has a weight average particle size of 15 to 45 μm. 18. A magnetic carrier comprising ²⁰ to 50 Am ² / k.
The electrophotographic apparatus according to claim 16 or 17, having a saturation magnetization of g and a coercive force of 5 to 200 Oe. 19. A magnetic carrier represented by the following formula (II) (Fe ₃ O ₄ ) _α (C) _β formula (II) wherein C is Fe ₂ O ₃ , Al ₂ O ₃ , SiO ₂ , CaO,
Represents SrO, MgO, MnO, Li ₂ O or a mixture thereof, α and β represent weight ratios and satisfy the following conditions: 0.2 ≦ α ≦ 0.8 and α + β ≦ 1. 20. The electrophotographic apparatus according to claim 16, wherein the carrier is a spherical carrier produced by a polymerization method in which the compound represented by the formula (1) is dispersed in a binder resin. 20. The electrophotographic apparatus according to claim 16, wherein the magnetic carrier is coated with a crosslinkable silicone resin and / or a fluorine atom-containing resin. 21. A charging step of charging the electrophotographic photosensitive member by applying a voltage to a charging means having a charging member disposed in contact with the electrophotographic photosensitive member, and exposing the charged electrophotographic photosensitive member to light. An exposure step of forming an electrostatic latent image by irradiating light, a developing step of forming a toner image by developing the formed electrostatic latent image using toner, and an intermediate step of developing the developed toner image. An image forming method having a transfer step of transferring to a transfer material with or without a transfer member, wherein the surface layer of the electrophotographic photosensitive member has a volume resistance of 10 ⁸ to 10 ¹⁴ Ωcm, and the charging member There have 10 ⁴ to 10 ⁹ volume resistivity of the [Omega] cm, the upstream and / or downstream of the exposure means, and wherein a field forming means having an electrode for preventing contamination of the exposure means by the toner An image forming method that. 22. The charging means has magnetic particles for charging and a magnetic particle holding member for magnetically constraining the magnetic particles to form a charged magnetic brush.
22. The image forming method according to claim 21, wherein the charging member having ⁴ to 10 < ⁹ > [Omega] cm is the magnetic particles for charging. 23. A cleaning step for recovering and storing toner remaining on the electrophotographic photosensitive member after the transfer step between the transfer step and the charging step and between the charging step and the developing step. Or the image forming method according to 22. 24. The image forming method according to claim 22, wherein the magnetic particles for charging have a coupling agent having a linear alkyl group having 6 or more carbon atoms on the surface thereof. . 25. The magnetic particle for charging has a coupling agent having an amino group on its surface.
24. The image forming method according to 2 or 23. 26. The magnetic particle according to claim 22, wherein the magnetic particle for charging has a coupling agent having a linear alkyl group having 6 or more carbon atoms and an amino group on its surface. Image forming method. 27. The method according to claim 2, wherein the amount of the coupling agent is 0.0001 to 0.5% by weight based on the total mass of the magnetic particles.
The image forming method according to any one of Items 4 to 26. 28. The central element of the coupling agent is titanium,
The image forming method according to any one of claims 24 to 27, wherein the image forming method is selected from aluminum and silicon. 29. The magnetic particles having an average particle size of 5 to 100 μm
The image forming method according to any one of claims 22 to 28, wherein 30. The image forming method according to claim 22, wherein the average particle size of the magnetic particles is 5 to 50 μm. 31. The image forming method according to claim 22, wherein the average particle diameter of the magnetic particles is 5 to 35 μm. 32. The developing step includes a toner having a weight average particle diameter of 1 to 9 μm having an external additive, wherein the external additive has
The image forming method according to any one of claims 21 to 31, having a weight average particle diameter of 2 to 0.4 µm. 33. The image forming method according to claim 21, wherein SF-1 of the toner is 100 to 160, and SF-2 of the toner is 100 to 140. 34. The image forming method according to claim 21, wherein SF-1 of the toner is 100 to 140, and SF-2 of the toner is 100 to 140. 35. The image forming method according to claim 21, wherein the developing step is a reversal developing step. 36. The image forming method according to claim 21, wherein the developing step includes a two-component developer using a toner and a magnetic carrier. 37. The image forming method according to claim 36, wherein the magnetic carrier has a weight average particle diameter of 15 to 45 μm. 38. A magnetic carrier comprising ²⁰ to 50 Am ² / k.
38. The image forming method according to claim 36, wherein the image forming method has a saturation magnetization of g and a coercive force of 5 to 200 Oe. 39. A magnetic carrier represented by the following formula (II) (Fe ₃ O ₄ ) _α (C) _β formula (II) wherein C is Fe ₂ O ₃ , Al ₂ O ₃ , SiO ₂ , CaO,
SrO, MgO, MnO, Li ₂ O or a mixture thereof, α and β indicate a weight ratio, and the following condition 0.2
≤ α ≤ 0.8 and α + β ≤ 1. 39. The image forming method according to claim 36, wherein the carrier is a spherical carrier produced by a polymerization method in which the compound represented by the formula (1) is dispersed in a binder resin. 40. The image forming method according to claim 36, wherein the magnetic carrier is coated with a crosslinkable silicone resin and / or a fluorine atom-containing resin.