JP3478705B2 - Electrophotographic carrier, developing device and image forming device - Google Patents

Description

Detailed Description of the Invention

[0001]

The present invention relates to relates to a developing device and an image forming equipment electrophotographic carrier which constitutes the electrostatic charge image developer together with the toner, it is the carrier used.

[0002]

2. Description of the Related Art As an electrophotographic method, US Pat.
Various methods are described in Japanese Patent Publication No. 7,691, Japanese Patent Publication No. 42-23910, Japanese Patent Publication No. 43-24748, and the like, and all of these methods are applied to a photoconductive layer according to the original. An electrostatic latent image is formed by irradiating an image, and then a colored fine powder called toner having a polarity opposite to this is deposited on the electrostatic latent image to develop the electrostatic latent image. The toner image is transferred to a transfer target material such as paper according to the requirement, and then fixed by heat, pressure, solvent vapor or the like to obtain a copy.

In the process of developing an electrostatic latent image, toner particles charged to a polarity opposite to that of the latent image are attracted by electrostatic attraction and adhered onto the electrostatic latent image. In this case, a toner having a triboelectric charge having the same polarity as that of the latent image is used.) Generally, a method of developing such an electrostatic latent image with toner is roughly classified and a small amount of the toner is dispersed in a medium called a carrier. There are a method of using a so-called two-component developer and a method of using a so-called one-component developer in which toner is used alone without using a carrier.

In general, carriers constituting the two-component developer are roughly classified into conductive carriers and insulating carriers. Oxidized or unoxidized iron powder is usually used as the conductive carrier, but in a developer containing the iron powder carrier, the triboelectrification property to the toner is unstable, and the developer is However, there is a problem that fogging occurs in the visible image formed by the above. That is, when such a developer is used, since the toner particles adhere to the surface of the iron powder carrier particles with the use thereof, the electric resistance of the carrier particles increases, the bias current decreases, and the friction The chargeability becomes unstable, and as a result, the image density of the formed visible image is lowered and fog is increased.

Further, as the insulating carrier, generally,
A typical example of the carrier is a carrier core material made of a ferromagnetic material such as iron, nickel or ferrite, and the surface of the carrier core material is uniformly coated with an insulating resin. In the developer using this carrier, the toner particles are not significantly fused to the carrier surface as compared with the case of the conductive carrier, so that it is excellent in durability and has a long service life. It has the advantage of being suitable for machines.

However, in such an insulating carrier, so-called toner spent in which the toner is fused to the surface of the carrier does not occur, and a sufficient triboelectrification amount desired for a specific toner used with the carrier is obtained. In addition, it is required that the coating layer that covers the surface of the carrier core material has sufficient abrasion resistance and strong adhesion to the core material. That is, the individual carrier particles are
Although it is rubbed with other carrier particles and toner particles in the developing device, if the toner spent occurs on the carrier surface, the original triboelectric charge imparting ability of the carrier coating layer cannot be exhibited, and the charging characteristics are unstable. turn into.
Also, if the carrier coating layer does not have sufficient film strength and adhesion to the core material, the coating film may peel off or be missing from the core material,
The charge imparting ability to the toner is deteriorated.

Furthermore, the surface resistance of a carrier coated with an insulating resin generally tends to change with changes in environmental conditions such as low temperature and low humidity and high temperature and high humidity. For example, under low temperature and low humidity, high resistance due to decrease of water content and image density decrease due to charge up occur, and under high temperature and high humidity, low resistance due to increase of water supply amount, fog due to reduction of tribo, and scattering. Will be generated. Therefore, it is an important characteristic of the carrier that the surface resistance of the carrier does not depend on environmental fluctuations, but at present, a carrier coated with an insulating resin having a satisfactory level has not been found.

Conventionally, as a technique for solving such a drawback,
The coated carrier coated with a fluoropolymer is U.V. S.
P. No. 3,922,382, the film-forming property of the fluoropolymer is poor in the proposed technique.
The carrier surface can only be partially covered, and the charging characteristics become unstable. Further, in order to improve the film-forming property of the fluoropolymer, a method of coating with a polymer having a relatively good film-forming property is also described in U.S.P. S. P. 4,29
7,427 and JP-A-54-110839. However, since all of them are composed of a fluorine-based polymer having a strong negative charge property, it can be advantageously used for a positive toner. It is expected that it will be difficult to obtain a sufficient amount of charge, and even if a sufficient amount of charge is obtained, it is difficult to maintain stable chargeability due to the slow rising speed of charge. it is conceivable that.

On the other hand, in order to accelerate the rise of triboelectrification of the toner, there is a method in which the toner contains a charge control agent or a charge controllable resin as conventionally known, but this is sufficient. It is not possible to accelerate the rise of the triboelectrification amount, and conversely, in an environment such as high temperature and high humidity or low temperature and low humidity, there may be a considerable difference in the triboelectrification amount and the rise of electrification, which causes However, such a method is not sufficient as a method for controlling the charge of the toner, such as fogging and low density. Further, Japanese Patent Laid-Open No. 62-75551 discloses a method of enhancing the triboelectric chargeability of a toner by adding fine particles located in the opposite direction to the toner in the triboelectric charging series to the toner. However, this method alone does not sufficiently control the charging of the toner, and if fine particles that are charged in the opposite polarity to the toner are added until the triboelectric charge amount of the toner can be sufficiently controlled, it will be contrary. The toner particles agglomerate with each other to deteriorate the fluidity of the toner. As a result, the carrier and the toner cannot be sufficiently mixed, and in the developing device configuration,
It is necessary to provide a stronger and more uniform stirrer. Further, when the fluidity of the toner is deteriorated, it may cause a bad influence on the cleaning device of the copying machine.

Further, various attempts have been made to control the surface resistance, for example, Japanese Patent Laid-Open No. 62-22925.
In Japanese Patent Laid-Open No. 6-26, it is proposed that a water-soluble quaternary ammonium salt is attached to the surface of the ferrite particles so that the carrier has a small decrease in resistance under high temperature and high humidity.
However, when a water-soluble quaternary ammonium salt is used, the quaternary ammonium salt on the surface of the ferrite particles will be eluted or desorbed due to long-term standing or durability under high temperature and high humidity, and the properties of the untreated ferrite particles will be increased. It has the drawback of gradually approaching. Further, since it is not coated with a resin, the quaternary ammonium salt on the surface of the ferrite particles is easily desorbed not only in high temperature and high humidity, but also in normal environment at normal temperature and humidity, and even in a state where it is not desorbed,
Compared with the resin-coated carrier, the problem is that the so-called toner spent, in which a film is formed by the toner on the surface of the carrier, is weak and the life of the developer is short. Further, if not covered with an insulating resin to some extent, not only iron oxide powder but also ferrite particles and 雖 are unsuitable because current leaks or carrier adheres to the photoconductor in a developing system where a bias voltage is applied. Is. As described above, with respect to the durability of the carrier, the toner spent resistance, and the like, there is currently no method superior to coating with an insulating resin.

[0011]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to solve the above-mentioned problems of the prior art, to provide excellent toner-spent resistance, and to provide a stable image with an extremely fast rise of charging. It is an object of the present invention to provide a carrier constituting a developer that can be used, a developing device using the carrier, an image forming apparatus, and a process cartridge.
Further, an object of the present invention is to provide a carrier which constitutes a developer having excellent durability, which does not cause problems such as density reduction and fog over a long period of time and which can give a stable image, and a developing device using the carrier. , Providing an image forming apparatus and a process cartridge.

[0012]

The above object can be achieved by the present invention described below. That is, the present invention is an electrophotographic carrier, wherein the core material has a resin coating layer coated with a resin composition, wherein the resin coating layer has at least a number average particle diameter of 1 to 20 μm in the binder resin. Conductive spherical particles are dispersedly contained, and the conductive spherical particles are (1) resin particle surface
Conductive resin fine particles that have been subjected to a conductive treatment, or (2)
Conductive resin with conductive fine particles dispersed in resin particles
Particles, either der electrophotographic carrier characterized by Rukoto of, developing device and an image forming instrumentation using the carrier
About the location.

In a preferred embodiment of the present invention, the conductive spherical particles used above have a true density of 3 g / cm.
³ or less, and the ratio of major axis / minor axis is 1.0 to 1.
It is within the range of 5 and the volume resistance thereof is 10 ⁶ Ωcm or less. Further, the plating as preferred conductive spherical particles as described above, for example, a conductive ball Josumi <br/> particle surface, a conductive metal, conductive metal oxide, or both of them Metal coated carbon particles being treated
Or a carbonized and / or graphitized bulk mesomorph
Conductive resin particles with resin pitch coated on the surface of resin particles
Of particles or resin particles on the surface of bulk mesophase pitch
And heat treating the resin particles in an oxidizing atmosphere
Fired to the Ru include carbonized and / or graphitized conductive resin particles.

Further, in a preferred embodiment of the present invention, in the resin composition for forming the resin coating layer, in addition to the binder resin and the conductive spherical particles as described above, a nitrogen-containing heterocycle such as an imidazole compound is added. Examples of the method include dispersing and containing the compound. In addition, an embodiment in which lubricating particles are further contained in the resin coating layer is also preferable, and the lubricating particles include graphite, molybdenum disulfide, boron nitride, mica, graphite fluoride, silver-niobium selenide, and calcium chloride. −
At least one selected from the group of particles consisting of graphite, talc and metal salt of fatty acid may be contained. It is also preferable that the resin coating layer further contains conductive fine particles other than the above-mentioned conductive spherical particles, and the conductive fine particles include carbon black, metal oxide, metal and inorganic filler. At least one selected from the particle group may be contained.

In the electrophotographic carrier of the present invention as described above, in the binder resin which is the film forming component of the resin coating layer,
It is characterized by containing specific conductive spherical particles in a dispersed manner, and as a result, the effect that the toner spent resistance of the carrier and the charging characteristics (fast rising, stable charging) are significantly improved can be obtained. The present inventors believe that the reason is due to the following.

That is, the reasons why the carrier of the present invention is excellent in toner spent resistance are as follows. (1) Since the conductive spherical particles contained in the resin coating layer are exposed on the surface of the coating layer of the carrier, the toner is less likely to adhere due to the lubricity. (2) Due to the conductivity of the conductive spherical particles, it becomes difficult for charges to accumulate on the carrier surface, and the carrier separation of the toner is promoted. (3) Due to the presence of the conductive spherical particles, the surface of the carrier particles has uniform unevenness, the contact pressure between the carrier particles and between the carrier particles and the toner particles is relieved, and the toner on the coat layer on the developer carrier is The adhered amount of is reduced. (4) Further, regarding the phenomena of (1) and (3), it is considered that the effect is increased when the shape of the conductive spherical particles contained in the resin coating layer is more spherical.

The reason why the charging property is improved is considered as follows. First, in general, the higher the resistance is, the smaller the amount of charge leakage tends to be. Therefore, the higher the resistance of the carrier is, the slower the rise of charging becomes. On the other hand, in the carrier of the present invention, since the conductive spherical particles are exposed on the surface of the resin coating layer, it is presumed that the resistance decreases at this site, the amount of leakage of electric charge increases, and the rise of charging becomes faster. . Further, it is considered that the chargeability becomes better and stable due to the synergistic effect of the addition of the charge control agent and the conductive spherical particles.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in more detail below with reference to preferred embodiments of the electrophotographic carrier of the present invention. First, the conductive spherical particles to be dispersed and contained in the resin coating layer used in the present invention will be described. The electrically conductive spherical particles used in the present invention are required to have a number average particle size of 1 to 20 μm, more preferably 2 to 15 μm. A particle size is preferable. That is, when the number average particle diameter of the conductive spherical particles is less than 1 μm, there is no effect of imparting uniform roughness to the surface as described in (3) above, the contact force between the carriers is not relaxed, and the toner Contamination and toner fusion occur, which causes deterioration of fog and reduction of image density. On the other hand, when the number average particle diameter exceeds 20 μm, the resin coating layer becomes non-uniform, so that the toner cannot be uniformly charged,
Also, the strength of the coating layer becomes insufficient. The spherical shape of the conductive spherical particles used in the present invention is, for example, a substantially spherical shape having a ratio of major axis / minor axis of the particles of 1.0 to 1.5 (preferably 1.0 to 1.2). It is preferable that the spherical particles have a major axis / minor axis ratio of 1.0.

The electroconductivity of the electroconductive spherical particles used in the present invention is preferably 10 ⁶ Ω · cm or less in volume resistance value. That is, the volume resistance of spherical particles is 10 ⁶ Ω · cm.
When it exceeds, the contamination and fusion of the toner are likely to occur with the spherical particles exposed on the surface of the coating layer due to abrasion as nuclei. Further, it is desirable that the conductive spherical particles used in the present invention have a true density of 3 g / cm ³ or less, and preferably 2.7 g / cm ³ or less. When the true density of the spherical particles exceeds ³ g / cm ³ , when the resin coating layer is formed using the resin composition, when the liquid resin composition is formed, or when the liquid is applied, further In the coating layer after coating, the dispersibility of the conductive spherical particles becomes insufficient, and it becomes difficult to obtain a state in which the conductive spherical particles are uniformly dispersed on the surface of the coating layer. In this case, the toner is uniformly charged and the strength of the coating layer is insufficient.

Examples of the method for obtaining the conductive spherical particles used in the present invention include the following methods, but the present invention is not necessarily limited to those obtained by these methods. For example, phenolic resin, naphthalene resin, furan resin, xylene resin, divinylbenzene polymer, styrene-divinylbenzene copolymer, polyacrylonitrile, or other resin-based spherical particles or mesocarbon microbeads are carbonized by firing and / or graphite. The method of making According to this method, spherical carbon particles having a low density and good conductivity can be obtained, and as a preferable method for obtaining more excellent conductive spherical particles, a phenol resin, a naphthalene resin, a furan resin, a xylene resin, and divinylbenzene are preferable. polymer, a styrene - divinylbenzene copolymer, the surface of the spherical particles such as polyacrylonitrile, covering the bulk mesophase pitch by a mechanochemical method, and fired after heat treatment in an oxidizing atmosphere it, carbonization and / Alternatively, a method of graphitizing may be used.

The spherical carbon particles obtained by these methods are
In either method, the conductivity can be controlled to some extent by changing the firing conditions and the like. Further, the spherical carbon particles obtained by these methods may have a conductive metal and / or metal oxide or the like on the surface thereof so that the true density does not exceed 3 in order to further increase the conductivity in some cases. It may be plated.

As another method for obtaining the conductive spherical particles preferably used in the present invention, conductive fine particles smaller than the particle diameter of the core particles are provided on the surface of the core particles (mother particles) made of spherical resin particles. After mechanically mixing in an appropriate mixing ratio and applying conductive fine particles (small particles) evenly around the resin particles by the action of Van der Waals force and electrostatic force, for example, by mechanical impact force, etc. Examples include conductive treated spherical resin particles in which the surface of the resin particles is softened by the local temperature rise which occurs and a coating film of conductive fine particles is formed on the surface.

As a constituent material of the mother particles used in the above-mentioned method, it is preferable to use a resin which is a spherical organic compound having a small true density, and examples thereof include PMMA, acrylic resin, polybutadiene resin, polystyrene resin and polyethylene. , Polypropylene, polybutadiene, or copolymers thereof, benzoguanamine resin, phenol resin, polyamide resin, nylon, fluorine resin, silicone resin, epoxy resin, polyester resin, or other resin particles. Further, as the conductive fine particles that are small particles to be attached to the surface, in order to form a film uniformly when forming a film on the surface of the mother particle by the particles, in order to form the film uniformly, The particle size is preferably ⅛ or less of the particle size of the mother particles.

As another method for obtaining the conductive spherical particles preferably used in the present invention, the conductive fine particles are uniformly dispersed in the spherical resin particles to form the conductive spherical particles (hereinafter, the conductive fine particle-dispersed spherical particles are used). (Also referred to as particles), for example, conductive fine particles dispersed in a binder resin, kneaded, and then pulverized to a predetermined particle size, and then made into spherical particles by mechanical treatment and thermal treatment. Dispersed spherical particles or a polymerizable monomer, a polymerization initiator, conductive fine particles, and if necessary, other additives are added, and uniformly dispersed by a disperser or the like to prepare a monomer composition. , Introduced into an aqueous phase containing a dispersion stabilizer, and suspended by a stirrer or the like so as to have a predetermined particle size and granulated, then conductive fine particles dispersed spherical particles etc. obtained by polymerization are obtained. Can be mentioned. Furthermore,
Conductive fine particle dispersed spherical particles obtained by these methods,
This is used as a core particle, and is mechanically mixed with conductive fine particles having a particle size smaller than the core particle at an appropriate mixing ratio, and the conductive fine particle-dispersed spherical particles are surrounded by the action of Van der Waals force and electrostatic force. After the conductive fine particles are uniformly attached, for example, the conductive fine particle-dispersed resin particle surface is softened by a local temperature rise caused by mechanical impact force, etc., and the conductive fine particles are formed into a film to further increase the conductivity. May be used.

As the binder resin which is a film forming material for forming the resin coating layer, a conventionally known and generally used resin can be used. For example, as the positively charged resin, an amino acrylate resin, an acrylic resin, or a copolymer of those resins and a styrene resin, or the like,
It is suitable because it is located on the positive charging side in the charging series.
As the negatively charged resin, silicone resin, polyester resin, polytetrafluoroethylene, monochlorotrifluoroethylene polymer, polyvinylidene fluoride, etc.,
It is preferable because it is located on the negative side in the charging series. These positive and negative mixed resins or a plurality of times of application are performed for adjusting the charge amount, but the application is not necessarily limited to this.

The resin coating layer of the electrophotographic carrier of the present invention is constituted by dispersing the above-mentioned various conductive spherical particles in the binder resin as described above. By using a mode in which a nitrogen-containing heterocyclic compound is further contained in the resin coating layer in combination with the hydrophilic spherical particles, the charging performance of the resin coating layer can be significantly improved, and the object of the present invention can be achieved. Be more certain. The nitrogen-containing heterocyclic compound contained in the resin coating layer that can be used in the present invention preferably has a number average of 20 μm or less, more preferably 0.1 to 15 μm. Number average particle size of nitrogen-containing heterocyclic compound is 20 μm
If it exceeds, the dispersibility of the nitrogen-containing heterocyclic compound in the resin coating layer will be poor, and it will be difficult to sufficiently obtain the effect of improving the charging performance, which is not preferable.

Examples of the nitrogen-containing heterocyclic compound preferably used in the present invention include indole, isoindole, indazole, carbazole, quinoline, pyridine, isoquinoline, cinnoline, quinazoline, quinoxaline, phthalazine, purine, pyrrole, imidazole, pyrazole and the like. Can be mentioned. Each of these nitrogen-containing heterocyclic compounds is
Alternatively, two or more kinds can be used in combination. In particular, in order to accelerate the effect of the carrier of the present invention, when the toner is controlled to be negatively charged, the following formula B-1 or B
It is preferable to use an imidazole compound represented by -2.

[0028]

Next, as the carrier core material used for the electrophotographic carrier of the present invention and on which the resin coating layer as described above is formed, commonly used iron powder, ferrite or the like can be used. , Its particle size is 10 to 1,000
0 μm, preferably 20 to 200 μm is suitable. As a specific method of coating the surface of the carrier core material as described above with the conductive spherical particles described above, and the binder resin material in which the conductive spherical particles and the nitrogen-containing compound are dispersed, There are ways to list. For example, the binder resin material is dissolved in a solvent, further, conductive spherical particles in it,
A nitrogen-containing compound is added if necessary, and after sufficiently dispersed by a disperser, the core material is immersed in the obtained solution and stirred if necessary, followed by desolvation, drying and baking at high temperature. There is a method.

The composition ratio of each component used in the resin coating layer formed on the surface of the core material as described above will be described. The following is a particularly preferable range, and the present invention is not limited to this. First, the addition amount of the conductive spherical particles in the resin coating layer is preferably in the range of 2 to 200 parts by mass, and 5 to 100 parts by mass with respect to 100 parts by mass of the binder resin.
Particularly preferred results are given in parts by weight. That is, if it is less than 2 parts by mass, the effect of adding the conductive spherical particles is small, and if it exceeds 200 parts by mass, the surface resistance of the carrier becomes too low,
Alternatively, the carrier particles may have a non-uniform shape, or the carrier may not be uniformly coated.

The content of the nitrogen-containing heterocyclic compound contained in the resin coating layer in combination with the conductive spherical particles is preferably 0.5 to 100 parts by mass, more preferably 100 parts by mass of the binder resin. Gives particularly preferable results in the range of 1 to 50 parts by mass. Nitrogen-containing heterocyclic compound content is 0.5
If the amount is less than 10 parts by mass, the effect of adding them is small and 10
If the amount is more than 0 parts by mass, the charge-up phenomenon is likely to occur and the toner adhesion to the resin coating layer may be increased, so that it is difficult to obtain the effect of adding the conductive spherical particles.

Next, the carrier of the present invention is usually mixed with toner in a range such that the toner concentration is several percent to form a two-component developer, and the carrier is mounted on a copying machine or the like to be electrostatic latent. Used when developing an image to form a visible image. The toner used in this case will be briefly described below. Toners are roughly classified into dry toners and wet toners. However, since wet toners have a large problem of solvent volatilization, dry toners are currently the mainstream. The toner includes a binder resin and a colorant, which are the main components, and if necessary, a release agent,
A colored resin fine powder in which a charge control agent or the like is added, melt-kneaded, solidified, pulverized, and then classified, etc. to have a uniform particle size distribution.

At this time, a generally known resin can be used as the binder resin used for the toner. For example, styrene, α-methylstyrene, homopolymers of styrene such as p-chlorostyrene and its substitution products; styrene-propylene copolymer, styrene-vinyltoluene copolymer, styrene-ethyl acrylate copolymer, styrene. -Butyl acrylate copolymer, styrene-octyl acrylate copolymer, styrene-dimethylaminoethyl copolymer, styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer Polymer, styrene-dimethylaminoethyl methacrylate copolymer, styrene-vinyl methyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-maleic acid Copolymer, Styrene-maleic acid S Styrene-based copolymers such as copolymers; polymethylmethacrylate, polybutylmethacrylate, polyvinyl acetate, polyethylene, polypropylene, polyvinyl butyral, polyacrylic acid resin, rosin, modified rosin, tempel resin, phenol resin, aliphatic or Alicyclic hydrocarbon resins, aromatic petroleum resins, paraffin wax, carnauba wax and the like can be used alone or in combination.

The toner may contain a pigment as a coloring agent, and examples thereof include carbon black, nigrosine dye, lamp black, Sudan black SM, fast yellow G, benzidine yellow, pigment yellow, India First Orange, Irgadine Red, Paranitroaniline Red, Toluidine Red, Carmine FB, Permanent Bordeaux FR
R, Pigment Orange R, Resor Red 2G,
Lake Red C, Rhodamine FB, Rhodamine B Lake, Methyl Vio Red B Lake, Phthalocyanine
Blue, Pigment Blue, Brilliant Green B, Phthalocyanine Green, Oil Yellow GG, Pomelo First Yellow CGG, Kayaset Y96
3, Kayaset YG, Pomelo First Orange R
R, Oil Scarlet, Orazol Brown B,
Pomelo First Scarlet CG, Oil Pink O
P etc. can be applied.

It is also preferable to use various releasing agents in the toner, and examples of such releasing agents include polyfluorinated ethylene, fluororesin, fluorocarbon oil, silicone oil, low molecular weight polyethylene, low molecular weight polypropylene, Various W
Examples include AXs. Further, if necessary, a charge control agent for facilitating positive or negative charge may be added.

Next, a developing device in which the above-mentioned carrier of the present invention is incorporated will be described using the device illustrated in FIG. In FIG. 1, the developing chamber 45 of the developing container 2
A non-magnetic developing sleeve (developer carrying body) 21 as a developer carrying body is provided inside the developing sleeve 21 so as to face the electrostatic latent image holding body 1 rotated in the direction of arrow a. A magnetic roller 22 as a means is installed immovably, and the magnetic roller 22 is magnetized to S ₁ , N ₁ , S ₂ , N ₂ , N ₃ in this order from the position of the top in the rotation direction of arrow b. . In the developing chamber 45, the toner 40 and the magnetic carrier 43
A two-component developer 41 that is a mixture of and is stored. The developer 41 is applied to the developing chamber 45 at one end thereof with a partition wall 48 having an open upper end.
The stirring chamber 4 of the developing container 2 through one opening (not shown)
2 is supplied to the stirring chamber 42 from the toner chamber 47, and the other end of the stirring chamber 42 is mixed while being mixed by the first developer stirring / conveying means 50 in the stirring chamber 42. Until it is transported. The developer 41 conveyed to the other end of the stirring chamber 42 is returned to the inside of the developing chamber 45 through the other opening (not shown) of the partition wall 48, where the second developer stirring / conveying means 51 in the developing chamber 45 and The third developer stirring / conveying means conveys the developer in the upper direction inside the developing chamber 45 in the direction opposite to the conveying direction by the conveying means 51, and the developer is conveyed to the developing sleeve 21 while being stirred / conveyed.

The developer 41 supplied to the developing sleeve 21.
Is magnetically restrained by the action of the magnetic force of the magnet roller 22, is carried on the developing sleeve 21, and is provided on the developing sleeve 21 substantially at the top thereof.
Due to the regulation in (1), while being formed as a thin layer of the developer 41 on the developing sleeve 21, the developing sleeve 21 is conveyed to the developing section 101 facing the latent image carrier 1 as the developing sleeve 21 rotates in the direction of the arrow b, and there. It is used for developing the electrostatic latent image on the latent image carrier 1. Residual developer 41 not consumed for development
Are collected in the developing container 2 by the rotation of the developing sleeve 21.

In the developing container 2, the repulsive magnetic field between N2 and N3 having the same polarity allows the residual developer 41 remaining after the development, which is magnetically restrained on the developing sleeve 21, to be peeled off. There is. Further, in order to prevent toner scattering when the developer 41 stands up along the lines of magnetic force by the magnetic pole N2, an elastic seal member 31 is provided at the lower part of the developer container 2 so that one end of the elastic seal member 31 contacts the developer 41. It is fixed and installed. FIG. 1 is merely a schematic example, and it goes without saying that there are various forms such as the shape of the container, the presence / absence of a stirring member, and the arrangement of magnetic poles.

[0039]

EXAMPLES Next, the present invention will be described more specifically with reference to Examples and Comparative Examples. The present embodiment does not limit the present invention at all. Further, all percentages and the number of copies in the examples are based on mass.

Example 1 As conductive spherical particles, 14 parts by weight of a coal-based bulk mesophase pitch powder having a particle size of 2 μm or less was uniformly added to 100 parts of a 7.8 μm spherical phenol resin by using a Laikai machine (automatic mortar, manufactured by Ishikawa Plant). And heat-stabilized in air at 280 ° C., and then graphitized by firing at 2,000 ° C. in a nitrogen atmosphere, and further classified to obtain a number average particle diameter of 7.2 μm. Conductive spherical carbon particles A-1 (conductive spherical particles A-1) were used. Table 1 shows the physical properties of A-1.

Conductive spherical particles A-1 obtained above,
To the mixture with the following materials, glass beads having a diameter of 3 mm were added as media particles and dispersed in a sand mill for 1 hour, and then the beads were separated using a sieve to contain conductive spherical particles A-1 dispersed therein. To obtain a resin composition (hereinafter referred to as a carrier coating liquid). -Silicone resin solution (containing 50% toluene) 40 parts-Conductive spherical particles A-1 1 part-Toluene 60 parts

Next, 100 g of the above carrier coating liquid was used for 1 kg of a spherical ferrite carrier core material having an average particle diameter of 100 μm, and a conductive resin coating layer was formed on the surface of the carrier core material with a Nauta mixer. Let it form
Subsequently, the conductive resin coating layer was cured by heating at 140 ° C. for 1 hour in a hot air drying oven to prepare a coated carrier C-1. Table 2 shows the structure of the carrier.

On the other hand, the coated carrier C-obtained above
The toner to be used together with No. 1 was kneaded, pulverized and classified according to a general dry toner manufacturing method using the following materials to bind a negative triboelectrifying cyan polyester resin having a volume average particle diameter of 8.8 μm. A powder to be used as a coating resin was obtained. Cyan toner was prepared by mixing 100 parts of the obtained colored powder with 0.5 part of hydrophobic colloidal silica. -Polyester resin 100 parts-Phthalocyanine pigment 5 parts-Di-tert-butylsalicylic acid chromium complex 4 parts

The cyan toner thus obtained and the above-prepared coated carrier C-1 were used in a toner concentration of 5%.
And mixed to prepare a two-component developer. Then, using a color copying machine CLC-500 manufactured by Canon Inc., which was fixed at a developing contrast of 350 V, an image drawing test was conducted while supplying the obtained developer. The obtained image was evaluated for (1) image density, (2) stain resistance of coating layer, and (3) fog density by the following methods and evaluation criteria. Table 3 shows the obtained evaluation results.

Evaluation (1) Image Density Image density was measured by using a reflection densitometer RD918 (manufactured by Macbeth) to measure the density of solid areas.

(2) Contamination resistance of the coating layer The surface of the carrier after endurance was observed by SEM to evaluate the degree of toner contamination. ○: Minor contamination is observed. ○ △: Some contamination is observed. Δ: Contamination is partially observed. X: Significant contamination is observed.

(3) Fog Density The reflectance of solid white areas was measured, and the reflectance of unused paper was measured, and the value subtracted from the previous value was taken as the fog density. At this time, the reflectance was measured by TC-6DS (manufactured by Tokyo Denshoku Co., Ltd.). ⊚: Fog is less than 1.5 and almost no fog is noticeable. ◯: 1.5 to 2.5, which cannot be understood unless carefully observed. B: From 2.5 to 3.5, fog can be gradually recognized. Δ ×: 3.5 to 4.0, which is the lower limit of the practical level, and fogging can be confirmed at a glance. X: 4.0 to 5.0, the image is considerably bad.

Example 2 As conductive spherical particles, 100 parts of spherical phenol resin of 3.1 μm was used, and a coal-based bulk mesophase pitch powder 14 having a number average of 1.4 μm or less was used by using a Laika machine (automatic mortar, manufactured by Ishikawa Plant). Evenly cover the parts by weight, and in air 2
Heat stabilization treatment at 80 ° C, then under nitrogen atmosphere for 2,0
Conductive spherical carbon particles A-2 (conductive spherical particles A-2) having a number average particle diameter of 2.8 μm obtained by graphitizing by firing at 00 ° C. and further classifying were used.
Table 1 shows the physical properties of A-2.

Next, instead of the conductive spherical particles A-1 used in preparing the carrier coating solution in Example 1, 1 part of the conductive spherical particles A-2 obtained above was added. In the same manner as in Example 1, coated carrier C-2
It was created. Table 2 shows the structure of the carrier. Further, a two-component type developer was prepared using the toner used in Example 1 and the coated carrier C-2 obtained above, and Example 1 was used.
An image output test was conducted in the same manner as in. The obtained image was evaluated in the same manner as in Example 1, and the results are shown in Table 3.

Example 3 As conductive spherical particles, 100 parts of spherical phenol resin having a diameter of 14.5 μm was added to a Reiki machine (automatic mortar, manufactured by Ishikawa Plant).
14 parts by weight of a coal-based bulk mesophase pitch powder having a number average of 1.4 μm or less is uniformly coated, and heat-stabilized in air at 280 ° C., and then in a nitrogen atmosphere, 2.
Conductive spherical carbon particles A-3 (conductive spherical particles A-3) having a number average particle diameter of 14.8 μm obtained by baking at 000 ° C. for graphitization and further classification were used. Table 1 shows the physical properties of A-3.

Next, instead of the conductive spherical particles A-1 used in preparing the carrier coating solution in Example 1, 1 part of the conductive spherical particles A-3 obtained above was added. In the same manner as in Example 1, coated carrier C-3
It was created. Table 2 shows the structure of the carrier. Furthermore, a two-component developer was prepared using the toner used in Example 1 and the coated carrier C-3 obtained above, and Example 1 was used.
An image output test was conducted in the same manner as in. The obtained image was evaluated in the same manner as in Example 1, and the results are shown in Table 3.

Example 4 As the conductive spherical particles, the following materials were used, kneading, pulverization and classification were carried out to obtain conductive particles having a number average particle diameter of 8.3 μm. The conductive spherical resin particles A-4 (conductive spherical particles A-4) obtained by spheroidizing by stirring together with the inorganic dispersant were used. The particles are resin particles in which carbon black is dispersed. Table 1 shows the physical properties of A-4.・ Styrene-acrylic resin 100 parts ・ Conductive carbon black 25 parts

Next, instead of the conductive spherical particles A-1 used in preparing the carrier coating solution in Example 1, 1 part of the conductive spherical particles A-4 obtained above was added. In the same manner as in Example 1, coated carrier C-4
It was created. Table 2 shows the structure of the carrier. Furthermore, a two-component developer was prepared using the toner used in Example 1 and the coated carrier C-4 obtained above, and Example 1 was used.
An image output test was conducted in the same manner as in. The obtained image was evaluated in the same manner as in Example 1, and the results are shown in Table 3.

Example 5 As electrically conductive spherical particles, 100 parts of spherical PMMA particles of 11.5 μm were coated with 5 parts of electrically conductive carbon black to obtain spherical electrically treated resin particles A-5 (electroconductive spherical particles). A-5) was used. This particle is in a state in which fine carbon black powder is adsorbed on the surface of the spherical PMMA particle, and then heated to soften the carbon black to form a film, which is coated. Table 1 shows the physical properties of A-5. Next, Example 1 was repeated except that 1 part of the conductive spherical particles A-5 obtained above was added instead of the conductive spherical particles A-1 used when preparing the carrier coating liquid in Example 1. A coated carrier C-5 was prepared in the same manner as in. Table 2 shows the structure of the carrier. Further, the toner used in Example 1,
A two-component developer was prepared using the coated carrier C-5 obtained above, and an image drawing test was conducted in the same manner as in Example 1. The obtained image was evaluated in the same manner as in Example 1, and the results are shown in Table 3.

Example 6 As conductive spherical particles, 14 parts by weight of coal-based bulk mesophase pitch powder having a particle size of 1.4 μm or less was added to 100 parts of 7.5 μm spherical phenol resin using a Laikai machine (auto mortar, manufactured by Ishikawa Plant). Conductive spherical carbon with a number average particle size of 7.5 μm obtained by uniform coating, heat stabilization treatment in air at 280 ° C., and then carbonization by firing at 1,000 ° C. in a nitrogen atmosphere. Metal-coated carbon particles (electroconductive spherical particles A-6) having a number average particle diameter of 9.5 μm obtained by further plating the surface of the particles with copper and silver were used. A-6
The physical properties of are shown in Table 1, and the true density of the conductive spherical particles A-6 was 3.20 g / cm ³ .

Next, instead of the conductive spherical particles A-1 used in preparing the carrier coating solution in Example 1, 1 part of the conductive spherical particles A-6 obtained above was added. In the same manner as in Example 1, the coated carrier C-6
It was created. Table 2 shows the structure of the carrier. Furthermore, a two-component developer was prepared using the toner used in Example 1 and the coated carrier C-6 obtained above, and Example 1 was used.
An image output test was conducted in the same manner as in. The obtained image was evaluated in the same manner as in Example 1, and the results are shown in Table 3.

Reference Example Instead of the conductive spherical particles A-1, spherical iron powder particles A-7 were used.
A coated carrier C-7 was prepared in the same manner as in Example 1 except that 1 part of was added. Table 2 shows the constitution of the carrier. The true density of the spherical iron powder particles A-7 is 7.87 g / cm.
^{Was 3} . Next, Example 1 was repeated except that 1 part of the conductive spherical particles A-7 obtained above was added in place of the conductive spherical particles A-1 used when preparing the carrier coating liquid in Example 1. In the same manner as described above, coated carrier C-7
It was created. Table 2 shows the structure of the carrier. Further, a two-component developer was prepared using the toner used in Example 1 and the coated carrier C-7 obtained above, and Example 1 was used.
An image output test was conducted in the same manner as in. The obtained image was evaluated in the same manner as in Example 1, and the results are shown in Table 3.

Example 8 Using the conductive spherical particles A-1 prepared in Example 1 and the following materials, a carrier coating liquid containing the conductive spherical particles A-1 dispersed therein was obtained, and this was used. A coated carrier C-8 was prepared in the same manner as in Example 1. Table 2 shows the structure of the carrier. -Fluorine acrylic resin (containing 50% methanol) 40 parts-Conductive spherical particles A-1 1 part-Methanol 60 parts Further, the toner used in Example 1 and the coated carrier C-8 obtained above are used. To produce a two-component developer,
An image output test was conducted in the same manner as in Example 1. The obtained image was evaluated in the same manner as in Example 1, and the results are shown in Table 3.

Example 9 Using the conductive spherical particles A-1 prepared in Example 1 and the following materials, a carrier coating liquid containing the conductive spherical particles A-1 dispersed therein was obtained. A coated carrier C-9 was prepared in the same manner as in Example 1. Table 2 shows the structure of the carrier. Resol type phenol resin solution (containing 50% methanol) 40 parts Conductive spherical particles A-1 1 part Methanol 60 parts Further, the toner used in Example 1 and the coated carrier C-9 obtained above. To prepare a two-component developer,
An image output test was conducted in the same manner as in Example 1. The obtained image was evaluated in the same manner as in Example 1, and the results are shown in Table 3.

Example 10 The procedure of Example 10 was repeated except that the coated carrier C-1 prepared in Example 1 was used and a black toner containing a styrene-butyl methacrylate copolymer as a binder resin was prepared by the following method. A developer was obtained in the same manner as in Example 1. -Styrene / butyl methacrylate 100 parts-Carbon black 5 parts-Low molecular weight polypropylene wax 2 parts-Cr complex of 3,5-di-t-butylsalicylic acid 2 parts The above materials are kneaded and pulverized by a general dry toner manufacturing method. Then, classification and the like were performed to obtain a black powder having a negative triboelectrification property and a volume average particle diameter of 8.8 μm. To 100 parts of the black powder described above, 0.5 part of hydrophobic silica treated with diphenyldichlorosilane was mixed to obtain a black toner. This toner was mixed with the coated carrier C-10 at a toner concentration of 5% to prepare a two-component developer. Using the obtained developer,
In the same manner as in Example 1, using a Canon color copying machine CLC-500 fixed at a development contrast of 350V,
An image output test was conducted. The obtained image was evaluated in the same manner as in Example 1, and the results are shown in Table 3.

Example 11 Using the conductive spherical particles A-1 prepared in Example 1 and the following materials, a carrier coating liquid containing the conductive spherical particles A-1 dispersed therein was obtained. In the same manner as in Example 1, a coated carrier C-10 having a coating layer containing imidazole compound particles was produced. Table 2 shows the structure of the carrier. -Silicone resin solution (containing 50% toluene) 40 parts-Conductive spherical particles A-1 1 part-Imidazole compound B-1 1 part-Toluene 60 parts As the nitrogen-containing heterocyclic compound used at this time, the following formula B was used. Imidazole compound particles having a number average particle diameter of 3 μm represented by −1 were used. Further, a two-component type developer was prepared using the black toner used in Example 10 and the coated carrier C-10 obtained above, and an image forming test was conducted in the same manner as in Example 1. . The obtained image was evaluated in the same manner as in Example 1, and the results are shown in Table 3.

Example 12 As a nitrogen-containing compound, 1 part of imidazole compound particles represented by the following formula B-2 having a number average particle diameter of 3 μm was added in place of the imidazole compound B-1 represented by the formula B-1. A coated carrier C-11 having a coating layer containing imidazole compound particles was prepared in the same manner as in Example 11 except for the above. Table 2 shows the structure of the carrier. Further, a two-component type developer was prepared by using the black toner used in Example 10 and the coated carrier C-11 obtained above, and an image forming test was conducted in the same manner as in Example 1. . The obtained image was evaluated in the same manner as in Example 1, and the results are shown in Table 3.

Example 13 A coating containing imidazole compound particles in the same manner as in Example 11 except that 1 part of carbon black-dispersed resin particles A-4 was added instead of the conductive spherical particles A-1. A coated carrier C-12 having a layer was prepared. Table 2 shows the structure of the carrier. Further, the black toner used in Example 10 and the coated carrier C obtained above.
A two-component type developer was prepared using No. 12 and, and an image drawing test was conducted in the same manner as in Example 1. The obtained image was evaluated in the same manner as in Example 1, and the results are shown in Table 3.

Example 14 Example 1 was repeated except that 1 part of carbon black surface-treated resin particles A-5 was added instead of the conductive spherical particles A-1.
In the same manner as in 1, a coated carrier C-13 having a coating layer containing imidazole compound particles was prepared. Table 2 shows the structure of the carrier. Furthermore, Example 10
A two-component type developer was prepared using the black toner used in 1. and the coated carrier C-13 obtained above, and an image forming test was conducted in the same manner as in Example 1. The obtained image was evaluated in the same manner as in Example 1, and the results are shown in Table 3.

Example 15 Imidazole compound particles were prepared in the same manner as in Example 11 except that 1 part of nigrosine (B-3) which was a CA agent for positive toner was added in place of the imidazole compound represented by the formula B-1. A coated carrier C-14 having a coating layer contained therein was prepared. Table 2 shows the structure of the carrier. Further, a two-component type developer was prepared using the black toner used in Example 10 and the coated carrier C-15 obtained above, and an image forming test was conducted in the same manner as in Example 1. . The obtained image was evaluated in the same manner as in Example 1, and the results are shown in Table 3.

Example 16 A coat having a coating layer containing imidazole compound particles was prepared in the same manner as in Example 11 except that 40 parts of the resol-type phenol resin used in Example 9 was added instead of the silicone resin. Carrier C-15 was created. Table 2 shows the structure of the carrier. Further, the black toner used in Example 10 and the coated carrier C obtained above.
A two-component type developer was prepared by using -15 and, and an image forming test was conducted in the same manner as in Example 1. The obtained image was evaluated in the same manner as in Example 1, and the results are shown in Table 3.

Comparative Example 1 A coated carrier D-1 was prepared in the same manner as in Example 1 except that the conductive spherical particles A-1 used in Example 1 were omitted. Table 2 shows the structure of the carrier. Further, the toner used in Example 1 and the coated carrier D obtained above
A two-component developer was prepared by using -1 and -1, and an image output test was conducted in the same manner as in Example 1. The obtained image was evaluated in the same manner as in Example 1, and the results are shown in Table 3.

Comparative Example 2 Instead of the conductive spherical particles A-1, the number average particle size is 7.5.
A coated carrier D-2 was prepared in the same manner as in Example 1 except that 1 part of the spherical PMMA particles a-1 having no conductivity of μm was added. Table 1 shows the physical properties of the spherical PMMA particles a-1, and Table 2 shows the constitution of the carrier. Further, a two-component type developer was prepared using the toner used in Example 1 and the coated carrier D-2 obtained above, and Example 1 was used.
An image output test was conducted in the same manner as in. The obtained image was evaluated in the same manner as in Example 1, and the results are shown in Table 3.

Comparative Example 3 Instead of the conductive spherical particles A-1, the number average particle size is 9.2.
A coated carrier D-3 was prepared in the same manner as in Example 1 except that 1 part of the amorphous graphite particles a-2 was added. Table 1 shows the physical properties of the amorphous graphite particles a-2, and Table 2 shows the constitution of the carrier. Further, a two-component type developer was prepared using the toner used in Example 1 and the coated carrier D-3 obtained above, and an image forming test was conducted in the same manner as in Example 1. The obtained image was evaluated in the same manner as in Example 1, and the results are shown in Table 3.

Comparative Example 4 The following materials were used instead of the conductive spherical particles A-1.
A coated carrier D-4 was prepared in the same manner as in Example 1 except that the electrically conductive amorphous particles a-3 having a number average particle diameter of 8.5 μm obtained by kneading, pulverizing, and classifying were used. did. Table 1 shows the physical properties of the electrically conductive amorphous particles a-3, and Table 2 shows the constitution of the carrier. -Styrene-acrylic resin 100 parts-Conductive carbon black 25 parts Further, a two-component developer was prepared using the toner used in Example 1 and the coated carrier D-4 obtained above,
An image output test was conducted in the same manner as in Example 1. The obtained image was evaluated in the same manner as in Example 1, and the results are shown in Table 3.

[0071]

[Table 1] Table 1: Physical properties of conductive spherical particles used in Examples and Comparative Examples

[0072]

[Table 2]

[0073]

[Table 3]

[0074]

As described above, according to the present invention,
Conductive spherical particles in the binder resin, more preferably, by using a carrier provided with a coating layer in which conductive spherical particles and a nitrogen-containing heterocyclic compound are dispersed and mixed, toner-spent resistance more than in the prior art Is improved, and it becomes possible to form an image while maintaining a good image for a long time. That is,
By providing a highly durable carrier that does not cause deterioration such as toner contamination on the carrier surface due to repeated copying or durability, it is possible to obtain a high-quality image for a long time without a decrease in image density.

[Brief description of drawings]

FIG. 1 is a schematic view of a developing device in which a carrier of the present invention is incorporated.

[Explanation of symbols]

1: Latent image holder 2: Development container 21: developing sleeve (developer carrier) 22: Magnet roller 23: Developer Control Blade 40: Toner 41: developer 42: stirring chamber 43: Career 45: Development room 47: Toner chamber

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazuki Saiki 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Kenji Fujishima 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. Incorporated (56) Reference JP 61-259265 (JP, A) JP 8-286430 (JP, A) JP 8-190264 (JP, A) JP 8-75521 (JP, A) JP-A-6-256008 (JP, A) JP-A-3-217856 (JP, A) JP-A-3-27054 (JP, A) JP-A-2-236568 (JP, A) JP-A-2 -176762 (JP, A) (58) Fields surveyed (Int.Cl. ⁷ , DB name) G03G 9/08 G03G 9/10

Claims (19)

(57) [Claims] 1. A core material is an electrophotographic carrier having a resin coating layer coated with a resin composition, wherein the resin coating layer has at least a number average particle diameter of 1 to 20 μm in a binder resin. Contact conductive spherical particles are contained dispersed
And the conductive spherical particles are (1) made conductive on the surface of the resin particles.
Conducted conductive resin particles or (2) resin particles
Conductive resin particles containing conductive fine particles dispersed in
A carrier for electrophotography, which is characterized by being slightly off . Wherein the true density of the conductive spherical particles 3 g / cm
The electrophotographic carrier according to claim 1, wherein the carrier is ³ or less. 3. A carrier for electrophotography according to claim 1 or 2 ratio of the major axis to the minor axis of the conductive spherical particles is in the range of 1.0 to 1.5. 4. A volume resistivity of the conductive spherical particles 10 ⁶ Omega
The electrophotographic carrier according to any one of claims 1 to 3, having a size of not more than cm. 5. A conductive treatment is applied to the surface of the resin particles (1).
The applied conductive resin particles are the surface of the conductive spherical carbon particles.
The conductive metal, conductive metal oxide, or electrophotographic carrier according to any one of claims 1 to 4 Ru Oh surfaces with both of them at the plating metal coated carbon particles. 6. The conductive spherical carbon particles are resin particle surfaces.
By firing particles coated with bulk mesophase pitch on
The electrophotographic image recording apparatus according to claim 5, which is a carbonized particle.
Rear . 7. A conductive treatment is applied to the surface of the resin particles (1).
Conducted conductive resin particles were carbonized and / or graphitized
Particles coated with bulk mesophase pitch on the surface of resin particles
The electronic copy according to any one of claims 1 to 4, which is a child.
True use carrier. 8. A conductive treatment is applied to the surface of the resin particles (1).
Conductive resin particles are applied to the surface of the resin particles in bulk mesophase.
Cover with a pitch pitch and coat the resin particles in an oxidizing atmosphere.
Carbonized and / or graphitized particles that have been heat treated and then fired
The electronic copy according to any one of claims 1 to 4, which is a child.
True use carrier. 9. Any one of the resin coating layer, according to claim 1 to 8 further nitrogen-containing heterocyclic compound is contained dispersed
The electrophotographic carrier according to the item . 10. A carrier for electrophotography according to claim 9 wherein the nitrogen-containing heterocyclic compound is an imidazole compound. 11. A container for accommodating a two-component developer having at least a toner and a carrier, and a developer carrier for carrying and carrying the developer, wherein the developer carrier and the latent image carrier are in opposing the developing area, the developing device for developing a latent image formed on the latent image holding member with a toner of the two-component developer carried on the developer carrying member, the carrier comprises a core material A resin coating layer, and the resin coating layer has a number average particle diameter of at least 1 in the binder resin.
Ri Na dispersed containing conductive spherical particles of 20 [mu] m, the conductive
Spherical particles are (1) treated with a conductive treatment on the surface of resin particles.
Conductive resin fine particles, or (2) conductivity in resin particles
Conductive resin particles containing fine particles dispersed therein,
Oh developing apparatus according to claim Rukoto. 12. The carrier according to claim 1 which is an electrophotographic carrier according to any one of claims 2 to 10
1. The developing device according to 1 . 13. the toner comprises at least a styrene - developing device according to claim 1 1 or 12 composed of an acrylic copolymer or a polyester binder resin and a colorant. 14. The method of claim developer regulating member for regulating the amount of the developer conveyed being disposed with a predetermined gap is further provided between the developer carrying member surface 1 1 to
13. The developing device according to any one of 13 . 15. A container containing (i) an electrostatic latent image holding member for holding an electrostatic latent image, and (ii) a two-component developer having at least a toner and a carrier, and carrying the developer. A developer carrier to be conveyed, and the latent image formed on the latent image carrier is carried on the developer carrier in a developing region where the developer carrier and the latent image carrier face each other. and developed with toner of the two-component developer, an image forming apparatus having a developing apparatus for forming a developed image, said carrier, and a core material and a resin coating layer, and the resin coating layer , The number average particle diameter of the binder resin is at least 1
Ri Na dispersed containing conductive spherical particles of 20 [mu] m, the conductive
Spherical particles are (1) treated with a conductive treatment on the surface of resin particles.
Conductive resin fine particles, or (2) conductivity in resin particles
Conductive resin particles containing fine particles dispersed therein,
Oh image forming apparatus according to claim Rukoto. 16. A method according to claim 1 wherein said carrier is a carrier for electrophotography according to any one of claims 2 to 10
5. The image forming apparatus according to item 5 . 17. The electrostatic latent image holding member is, the image forming apparatus according to claim 1 5 or 16 which is an electrophotographic photoreceptor. 18. The transfer means for transferring the developed image onto the recording material that has been further provided 請 Motomeko 1 of 5 to 17
The image forming apparatus according to any one of items . 19. The method according to claim 15, further comprising fixing means for fixing the developed image on the recording material .
The image forming apparatus according to item 1 .