JP2001042574A - Magnetic fine particle dispersion type resin carrier and two-component developer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a color image having high image density and high definition over a long period of time by using composite particles having at least magnetic fine particles and a resin binder and treating the magnetic fine particles with a treating agent for imparting lipophilic property in an aqueous medium. SOLUTION: This magnetic fine particle dispersion type resin carrier is formed with composite particles having at least magnetic fine particles and a resin binder and the magnetic fine particles have been treated with a treating agent for imparting lipophilic property in an aqueous medium. The magnetic fine particles may be selected from various magnetic particulate powders such as magnetite particulate powder, maghemite particulate powder, particulate powders obtained by depositing cobalt on these or incorporating cobalt into these, magnetoplumbite type ferrite particulate powder containing Br, Sr or the like and spinel type ferrite particulate powder containing one or more selected form Mn, Ni, Zn, Li, Mg, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic carrier and a two-component developer for developing an electrostatic image in electrophotography, electrostatic recording and the like.

[0002]

2. Description of the Related Art U.S. Pat.
7, 691, JP-B-42-23910 and JP-B-43-24748 describe various methods. These methods form an electrostatic image by irradiating the photoconductive layer of the electrostatic image carrier with a photo image, and then apply toner to the electrostatic image to develop the electrostatic image, After the transfer of the toner image onto a transfer material such as paper, the toner image is fixed by heat, pressure, heat and pressure, or a solvent vapor to obtain a copy or print.

In the step of developing the electrostatic image, a toner image is formed on the frictionally charged toner by utilizing the electrostatic interaction of the electrostatic image. In general, of the methods for developing an electrostatic image using toner, a two-component developer in which toner is mixed with a carrier is suitably used in a full-color copying machine or a printer that requires high image quality.

In this developing method, the carrier imparts an appropriate amount of positive or negative charge to the toner by triboelectric charging, and carries the toner on the surface by the electrostatic attraction of the triboelectric charging.

A developer having a toner and a carrier is coated on a developing sleeve containing a magnet to a predetermined layer thickness by a developer layer thickness regulating member, and by utilizing a magnetic force, an electrostatic image carrier (photosensitive material) is formed. Body) and the developing sleeve are transported to a developing area formed between the developing sleeve and the developing sleeve.

A predetermined developing bias voltage is applied between the photosensitive member and the developing sleeve, and the toner is developed on the photosensitive member in the developing area.

There are various characteristics required for the carrier, and particularly important characteristics include appropriate charging properties, pressure resistance to an applied electric field, impact resistance, abrasion resistance, spent resistance, developability, and the like. Can be

For example, when a developer is used for a long time,
A toner which does not contribute to the development called a spent toner is fused to the surface of the carrier, and toner filming occurs. As a result, the developer is deteriorated and the image quality of the developed image is deteriorated accordingly.

In general, if the true specific gravity of the carrier is too large, the developer may be used when the developer is brought into a predetermined layer thickness on the developing sleeve by the developer layer thickness regulating member, or when the developer is stirred in a developing device. In this case, the load on the developer increases. In the long-term use of the developer, (a) toner filming,
(B) Carrier destruction and (c) toner deterioration are likely to occur. As a result, deterioration of the developer and accompanying image quality deterioration of the developed image are likely to occur.

Further, when the particle size of the carrier is large, the load on the developer is increased similarly to the above, so that the above (a) to (c) tend to occur, and as a result, the deterioration of the developer occurs It will be easier. In addition, (d) the reproducibility of the fine line of the developed image is likely to be reduced.

Therefore, in a carrier in which the above (a) to (c) are likely to occur, it takes time and effort to replace the developer periodically and is uneconomical, so that the load on the developer is reduced. Alternatively, it is preferable to improve the impact resistance and spent resistance of the carrier to prevent the above (a) to (c) and extend the life of the developer.

When the particle size of the carrier is reduced, (e) the carrier easily adheres to the electrostatic image carrier. Further, reducing the particle diameter of the carrier only with a constant toner particle diameter results in (f) the distribution of the charge amount of the toner being broadened, and the toner flies to a non-image portion due to charge-up particularly in a low humidity environment ( Hereinafter, this phenomenon will be referred to as “fog”).

As a carrier for solving the above problems (a) to (f), a magnetic fine particle-dispersed resin carrier can be mentioned. This carrier is relatively easy to be formed into a sphere having a small particle shape distortion and a high particle strength, and is excellent in fluidity. Since the particle size can be controlled in a wide range, it is suitable for a high-speed copying machine in which the number of rotations of a developing sleeve or a magnet in the sleeve is large, a high-speed laser beam printer of a general-purpose computer, and the like.

A magnetic fine particle-dispersed resin carrier has been proposed in JP-A-54-66134 and JP-A-61-9659. However, when the magnetic particle carrier does not contain a large amount of a magnetic substance, the saturation magnetization is small with respect to the particle diameter, carrier adhesion easily occurs on the electrostatic image carrier during development, and the developer Replenishment,
Alternatively, it may be necessary to provide a mechanism for collecting the attached carrier in the image forming apparatus.

In addition, when a magnetic substance is contained in a large amount in a magnetic fine particle-dispersed resin carrier, the impact resistance becomes weak because the amount of the magnetic substance increases with respect to the binder resin, so that the developer is not used. When a predetermined layer thickness is formed on the sleeve by the developer layer thickness regulating member, (g) the magnetic material is easily dropped from the carrier, and as a result, the developer is easily deteriorated.

In the above-mentioned magnetic fine particle-dispersed resin carrier, when a magnetic substance is contained in a large amount, the specific resistance of the carrier decreases due to an increase in the amount of the magnetic substance having a low specific resistance. h) Image defects due to leakage of bias voltage applied during development are also likely to occur.

JP-A-58-21750 proposes a technique for coating a carrier core with a resin. Carrier coated with resin, spent resistance, impact resistance,
The withstand voltage with respect to the applied voltage can be improved. In addition, since the charging characteristics of the toner can be controlled by the charging characteristics of the resin to be coated, a desired charge can be imparted to the toner by selecting the resin to be coated.

However, also in the above resin-coated carrier, when the amount of the coating resin is large and the specific resistance of the carrier is high, the charge-up phenomenon of the toner easily occurs in a low humidity environment. Further, when the amount of the coating resin is small, the specific resistance of the carrier becomes too low, so that an image defect easily occurs due to a leak of the developing bias voltage.

Further, depending on the coating resin, even if the specific resistance of the carrier coated with the resin is considered to be an appropriate specific resistance in measurement, an image defect is likely to occur due to a leakage of a developing bias voltage, or in a low humidity environment. In some cases, the charge-up phenomenon easily occurs.

Further, as a carrier having improved surface contamination resistance, impact resistance, environmental dependency of charging, charge rising property and charge exchange property, a silicone resin coated carrier to which an aminosilane coupling agent is added is disclosed in 10-
39589 and Japanese Patent Application Laid-Open No. 10-39547. However, in the above-mentioned publication, it is difficult to control the reactivity of the aminosilane coupling agent, and as a result, the charging characteristics are likely to fluctuate due to the influence of the remaining functional groups and unreacted substances, and the resistance is also difficult to control. However, there remains a problem in stably imparting sufficient chargeability to the toner with little environmental fluctuation. Further, in the proposed developer, the adhesion strength of the coating resin is not sufficient, and when a large number of large image areas consuming a large amount of toner are copied many times, the coating resin is likely to be lost, and the charge amount of the toner is reduced. Easy to change.

As described above, it is possible to satisfy today's strict quality requirements, for example, various objects such as fine lines, small letters, photographs, and color originals, and also to achieve high image quality, high quality, high speed, and high durability. There is a long-awaited demand for magnetic carriers.

[0022]

SUMMARY OF THE INVENTION An object of the present invention is to provide a magnetic carrier and a two-component developer which have solved the above-mentioned problems.

An object of the present invention is to provide a magnetic carrier and a two-component developer capable of forming a high-quality toner image by preventing or suppressing generation of fog without carrier adhesion.

An object of the present invention is to provide a magnetic carrier and a two-component developer capable of forming a high-definition color toner image with a high image density without being affected by temperature and humidity.

An object of the present invention is to provide a magnetic carrier and a two-component developer which are excellent in durability without image deterioration even when a large number of images are formed.

[0026]

Specifically, the present invention provides:
A magnetic fine particle-dispersed resin carrier formed of composite particles having at least magnetic fine particles and a binder resin, wherein the magnetic fine particles are treated with a lipophilic treatment agent in an aqueous medium. The present invention relates to a magnetic fine particle-dispersed resin carrier.

The present invention further provides a two-component developer having at least a toner and a magnetic carrier, wherein the magnetic carrier is formed of composite particles having at least magnetic fine particles and a binder resin. Wherein the magnetic fine particles are treated with an oleophilic treatment agent in an aqueous medium.

[0028]

BEST MODE FOR CARRYING OUT THE INVENTION The present inventors have conducted various studies and studies to improve the above-mentioned problems, and as a result, have found that magnetic fine particle-dispersed resin containing magnetic fine particles treated with a lipophilic treatment agent in an aqueous medium. The inventors have found that a carrier and a two-component developer thereof are effective in improving various characteristics, and have reached the present invention.

The magnetic fine particle-dispersed resin carrier (hereinafter referred to as "carrier") used in the present invention is composed of composite particles in which magnetic fine particles whose particle surfaces have been treated in an aqueous medium are dispersed.

The magnetic fine particles constituting the composite particles in the present invention may be those which do not dissolve in water or are not altered or denatured by water. As the magnetic fine particles, magnetite particle powder, maghemite particle powder, particle powder obtained by adhering or containing cobalt, barium, strontium or barium-strontium-containing magnetoplumbite-type ferrite particles powder, manganese, nickel, zinc, Various magnetic particles such as spinel ferrite particles containing one or more selected from lithium and magnesium can be used. Further, as the nonmagnetic inorganic compound particles that can be used together with the magnetic fine particles, hematite particles, hydrous ferric oxide particles, titanium oxide particles, silica particles, talc particles,
Examples include alumina particle powder, barium sulfate particle powder, barium carbonate particle powder, cadmium yellow particle powder, calcium carbonate particle powder, and zinc white particle powder.

The particles may be in any form such as cubic, polyhedral, spherical, acicular or plate-like. The average particle size may be a particle smaller than the average particle size of the composite particles, and is 0.02 to 5.0 μm,
In particular, the magnetic particle powder (a) is preferably 0.02 to 2 μm, the nonmagnetic particle powder (b) is preferably 0.05 to 5 μm, and 1.5a <b.

When the magnetic particles and the non-magnetic particles are used in combination, the mixing ratio is preferably such that the magnetic particles contain at least 30% by weight.

The magnetic fine particles are entirely or partially treated with a lipophilic treatment agent.

As the lipophilic treatment agent, one or more functional groups selected from epoxy groups, amino groups, mercapto groups, organic acid groups, ester groups, ketone groups, halogenated alkyl groups and aldehyde groups are used. Organic compounds having a group and mixtures thereof can be preferably used, and any of them can achieve the object of the present invention. Of these, coupling agents containing a functional group are preferred, and silane coupling agents are particularly preferred because they can be treated while hydrolyzed in an aqueous medium. Furthermore, as a preferable functional group, an epoxy group, an amino group, and a mercapto group are preferable in that they are easily dispersed uniformly in a carrier.
It is preferable because it is hardly affected by temperature and humidity and the charge-imparting ability of the carrier is stabilized.

As the organic compound having an epoxy group,
Epichlorohydrin, glycidol, styrene-glycidyl (meth) acrylate copolymer and the like.

Examples of the silane coupling agent having an epoxy group include γ-glycidoxypropylmethyldimethoxysilane, γ-glycidoxypropyltrimethoxysilane, β- (3,4-epoxycyclohexyl) trimethoxysilane and the like. is there.

As the organic compound having an amino group, ethylenediamine, diethylenetriamine, styrene-
And dimethylaminoethyl (meth) acrylate copolymer.

As the silane coupling agent having an amino group, γ-aminopropyltrimethoxysilane, N
-Β- (aminoethyl) -γ-aminopropyltrimethoxysilane, N-β- (aminoethyl) -γ-aminopropylmethyldimethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane and the like.

Examples of the titanium-based coupling agent having an amino group include isopropyl tri (N-aminoethyl) titanate.

Examples of the organic compound having a mercapto group include mercaptoethanol and mercaptopropionic acid.

Examples of the silane coupling agent having a mercapto group include γ-mercaptopropyltrimethoxysilane.

Examples of the organic compound having an organic acid group include oleic acid, stearic acid, styrene-acrylic acid and the like.

Examples of the organic compound having an ester group include:
Examples include ethyl stearate and styrene-methyl methacrylate.

Examples of the organic compound having a ketone group include cyclohexanone, acetophenone, and methyl ethyl ketone resin.

Examples of the organic compound having a halogenated alkyl group include chlorohexadecane and chlorodecane.

Examples of the organic compound having an aldehyde group include propionaldehyde and benzaldehyde.

The amount of the lipophilic treatment agent in the present invention is preferably from 0.1 to 5.0% by weight based on the weight of the inorganic compound particles.

If the content is less than 0.1% by weight, uniform dispersion becomes difficult due to insufficient lipophilic treatment, and composite particles having a high content of inorganic compound particles cannot be obtained.

When the content exceeds 5.0% by weight, the resin coating can be adhered to the surface of the composite particles, but the formed composite particles aggregate, and the particle size of the composite particles is controlled. It becomes difficult. In addition, a large amount of unreacted treating agent remains in the aqueous medium, and undesirably causes device adhesion, wastewater contamination, and the like.

The binder resin constituting the composite particles in the present invention is preferably a thermosetting resin.

Examples of the thermosetting resin include phenolic resins, epoxy resins, polyamide resins, melamine resins, urea resins, unsaturated polyester resins, alkyd resins, xylene resins, acetoguanamine resins, furan resins, silicone resins, and polyimide resins. , Urethane resin, etc.
These resins may be used alone or in combination of two or more, but it is preferable that the resin contains at least a phenol resin.

In the present invention, the ratio of the binder resin and the inorganic compound particles constituting the composite particles is 1 to 20% by weight of the binder resin and 80 to 99% of the inorganic compound particles.
% By weight.

In the magnetic carrier according to the present invention, the surface of the composite particles is coated with a coupling agent having one or more functional groups selected from an epoxy group, an amino group and a mercapto group. Is more preferred. At this time, it is preferable to select a functional group contained in the coupling agent that reacts with a functional group contained in the lipophilic treatment agent treating the inorganic compound particles in the composite particles.

The coating amount of the coupling agent is preferably from 0.001 to 5.0% by weight based on the composite particles. 0.0
When the amount is less than 01% by weight, it becomes difficult to bring the coating of the coupling agent into close contact with the surface of the composite particles, and there is a problem in durability of the charge amount. When the amount exceeds 5.0% by weight, the coating of the coupling agent can be adhered to the surface of the composite particles, but the change in the charge amount due to long-term use due to the presence of the excess coupling agent. Is caused.

Further, in the case of coating with a resin, the amount used is preferably 0.005 to 4.0% by weight in order to increase the adhesion strength of the resin.

The particle size of the magnetic carrier powder according to the present invention coated with a coupling agent has an average particle diameter of 1
0 to 200 μm is preferred. When the average particle diameter is less than 10 μm, the magnetic carrier particles themselves fly to the photoreceptor, causing a so-called carrier adhesion that causes a defect on an image. If it exceeds 200 μm, it will be difficult to obtain a clear image.

In particular, for high image quality and high quality, the average particle diameter is more preferably in the range of 10 to 50 μm, and furthermore, the average particle diameter is 15 to 45 μm. Even when a large number of original continuous prints are performed, it is more preferable in that the mixed toner transportability of the replenishment toner is excellent.

The magnetic carrier according to the present invention may be
A resin may be further coated on the coating of the coupling agent.

The resin to be coated may be any known resin, for example, epoxy resin, silicone resin,
Polyester resin, fluorine resin, styrene resin, acrylic resin, phenol resin and the like can be used. A polymer obtained by polymerizing from a monomer may be used. A silicone resin is preferable in consideration of durability and stain resistance.

More preferably, the binder resin of the core particles is contained in a phenolic resin, the surface treating agent of the magnetic fine particles is contained in an epoxy group-containing silane coupling agent, a silicone coat resin, or contains an amino group as a pretreatment agent for the core agent. By making the silane coupling agent to be, the silane coupling agent containing an amino group is hydrolyzed by moisture appropriately adsorbed in the binder resin, while forming a hydrogen bond with the hydroxyl group of the phenol resin, At the same time as self-condensing or condensing with the remaining silanol groups in the silicone resin to form a strong coating, the amino groups react with the epoxy group of the surface treatment agent of the magnetic fine particles, improving the adhesion of the silicone resin, The loss of the coating resin and the like are suppressed.

The carrier of the present invention has a true specific gravity of 2.5 to 4.5 (preferably 3.0 to 4.3). When the true specific gravity is in this range, the carrier and the toner are mixed and stirred. This is preferable because the load on the toner is small, the contamination of the carrier surface by the toner is suppressed, and the adhesion of the carrier to the non-image portion on the electrostatic image carrier is preferred.

The carrier of the present invention has a size of 1000 × (10 ³⁾
/ 4π) · A / m (1000 Oersteds) with a magnetization intensity (σ ₁₀₀₀ ) of 20 to 80 Am ² /
kg (emu / g) (preferably 25 to 70 Am ²
A / kg), residual magnetization (sigma _r) is 0.1～20Am ²
/ Kg (emu / g) (preferably 0.3 to 10 A
m ² / kg), and when the magnetic properties of the carrier are within this range, the electrostatic charge of the carrier under the magnetic field of the magnetic field generating means (for example, a fixed magnet) contained in the developer carrier (developing sleeve) This is preferable because carrier adhesion to the image carrier is prevented, the compressive force of the two-component developer on the toner in the magnetic brush is reduced, and carrier contamination by external additives and toner particles is suppressed. Remanent magnetization of carrier (σ
_{When r} ) exceeds 20 Am ² / kg, the two-component developer on the developer carrier and the two-component developer in the developing device are not smoothly exchanged, and the charge-up of the toner and the charge amount of the toner are not performed. Variation easily occurs.

The carrier of the present invention has a specific resistance of 5 × 10
A ¹¹ to 5 × 10 ¹⁵ Ω · cm, the specific resistance of the carrier is in this range, the carrier is less likely to adhere the carrier to the electrostatic image bearing member, the charge-up of toner may also be satisfactorily suppressed.

In order to make the specific resistance value and the magnetic characteristics of the carrier fall within predetermined ranges, it is preferable that a non-magnetic inorganic compound is added to the carrier core in addition to the magnetic fine particles. The fact that the magnetic fine particles and the nonmagnetic inorganic compound fine particles are contained in a total amount of 70 to 99% by weight (based on the carrier) (more preferably, 80 to 99% by weight) can adjust the true specific gravity of the carrier, This is preferable in relation to the adjustment of the specific resistance value and the mechanical strength of the carrier core.

Further, the specific resistance of the non-magnetic inorganic compound fine particles is larger than that of the magnetic fine particles, and the larger the number average particle diameter of the non-magnetic inorganic compound fine particles than that of the magnetic fine particles, the higher the specific resistance of the carrier. This is preferable for increasing the value and reducing the true specific gravity of the carrier.

The fact that the magnetic fine particles are contained in an amount of 30 to 95% by weight based on the total amount of the magnetic fine particles and the nonmagnetic inorganic compound fine particles prevents the carrier from adhering by adjusting the magnetic force of the carrier, It is preferable for adjusting the specific resistance.

The shape of the carrier is appropriately selected so as to be suitable for a predetermined system. However, the sphericity of the carrier is between 100 and 130 (more preferably 1
00 to 120) are preferred. The carrier has a sphericity of 13
If it exceeds 0, the fluidity of the developer will be poor, and the ability to impart frictional charge to the toner will be reduced, and the shape of the magnetic brush will be uneven at the developing pole, making it difficult to obtain high-quality images. .

The sphericity of the carrier was measured by using a field emission scanning electron microscope S-Hitachi, Ltd.
This is performed by extracting 300 or more carriers at random using 800, and using a Luzex3 image processing / analysis device manufactured by Nireco to determine the sphericity derived by the following equation.

[0069]

(Equation 1) [Where MXLNG indicates the maximum diameter of the carrier, and ARE
A indicates the projected area of the carrier. Here, SF-1 closer to 100 means closer to a sphere.

Next, a preferred method for producing the carrier according to the present invention will be described.

The treatment of the magnetic fine particles with the lipophilic treatment agent is as follows:
What is necessary is just to add and mix a solution of a coupling agent or an organic compound to the magnetic fine particles dispersed in the aqueous medium, and to perform the treatment. In the method of treating in an aqueous medium, the magnetic fine particles can be treated while being mechanically dispersed so as to have a primary particle size. The particles act as a repulsion between the particles, and are processed in a state of substantially primary particles.

Further, the method of treating the coupling agent while hydrolyzing it in an aqueous medium does not require the use of a coupling agent that generates a gas such as chlorosilanes or silazanes. In the gaseous phase, the particles were likely to coalesce, and good processing was difficult. A highly viscous coupling agent can be used, and the effect is enormous.

Further, when used as a polymerization carrier as described later, the magnetic fine particles treated in an aqueous medium can be applied as a wet cake or a water-containing slurry after filtration and washing without completely drying the magnetic fine particles. A large amount of magnetic fine particles can be easily contained therein, and the effect is enormous.

The composite particles are obtained by dispersing magnetic fine particles dispersed in a solvent in a monomer constituting a binder resin,
Polymerization by adding an initiator or a catalyst, a so-called polymerization method, pulverizing a binder resin containing magnetic fine particles,
It can be manufactured by a so-called kneading and pulverizing method. A polymerization method is preferred for easily controlling the particle size of the magnetic carrier and obtaining a sharp particle size distribution.

The production of composite particles using a phenol resin as a binder resin is carried out, for example, by dispersing phenols and aldehydes and magnetic fine particles subjected to lipophilic treatment in an aqueous medium and adding a basic catalyst. A method for causing the reaction is mentioned. A natural resin such as rosin and a drying oil such as tung oil and linseed oil are mixed with phenols and reacted.
A method of forming a so-called modified phenol resin may also be used.

When the binder resin is a phenol resin in particular, it is preferable because it retains a suitable amount of adsorbed water, promotes the hydrolysis of the coupling agent, and forms a strong coating.

The production of composite particles using an epoxy resin as a binder resin is carried out, for example, by dispersing bisphenols, epihalohydrin and lipophilic magnetic fine particles in an aqueous medium, and reacting them in an alkaline aqueous medium. Is mentioned.

For the production of composite particles using a melamine resin as a binder resin, for example, melamines and aldehydes and magnetic fine particles subjected to lipophilic treatment are dispersed in an aqueous medium, and the presence of a weakly acidic catalyst The reaction is performed under the following conditions.

Other methods for producing composite particles using a thermosetting resin include, for example, kneading magnetic particles subjected to lipophilic treatment with various resins, pulverizing them, and further subjecting them to spheroidizing treatment. And the like.

The lipophilic composite particles composed of magnetic fine particles and a binder resin may be subjected to a heat treatment if necessary to further cure the resin. In particular, it is preferable to perform the treatment under reduced pressure or in an inert atmosphere in order to prevent oxidation of the magnetic fine particles and the like.

The coating treatment of the composite particles with the coupling agent may be carried out by immersing the composite particles in water or a solvent in which the coupling agent is dissolved, followed by filtration and drying. A method of spraying and drying an aqueous solution or a solvent solution of the coupling agent with stirring is used. In particular, in order to prevent coalescence of the composite particles and form a uniform coating layer, a method of performing treatment with stirring is preferable.

The resin may be coated by a known method, for example, a method of dry-mixing the composite particles and the resin using a Henschel mixer or a high-speed mixer, or a method of mixing the composite particles in a solvent containing the resin. How to impregnate,
Any method such as spraying a resin onto the composite particles using a spray dryer may be used.

Here, a method for measuring the characteristic values used for the magnetic carrier of the present invention will be described.

(Measurement Method of Carrier Characteristic Value) The average particle diameter is a value measured by a laser diffraction type particle size distribution meter (manufactured by Horiba, Ltd.).

The magnetization value (σ ₁₀₀₀ ) and the remanence magnetization value were measured using a vibrating sample magnetometer VSM-3S-15 (manufactured by Toei Kogyo Co., Ltd.) under an external magnetic field of 1 kOe.

The true specific gravity was indicated by a value measured with a multi-volume densitometer (manufactured by Micromeritics).

The specific volume resistance was represented by a value measured with a high resistance meter 4329A (produced by Yokogawa Hewlett-Packard).

More specifically, the specific resistance of the magnetic resin carrier or the carrier core is measured by using a measuring device shown in FIG. Cell E is filled with a magnetic resin carrier or core,
The electrodes 121 and 122 are arranged so as to be in contact with the magnetic resin carrier or the core filled as the sample 127, a voltage is applied between the electrodes, and a current flowing at that time is measured to obtain a specific resistance. In the above-mentioned measuring method, since the magnetic resin carrier or the core is a powder, a change occurs in the filling rate, and the specific resistance may change with the change. The measurement conditions of the specific resistance are as follows: The contact area S between the filled magnetic resin carrier or core and the electrode is about 2.3 cm.
² , thickness d = about 2 mm, load 180 g of the upper electrode 22,
The applied voltage is 100 V.

The measurement of the specific resistance of the fine particles conforms to the method of the specific resistance of the carrier. The cell E of FIG. 4 is filled with fine particles, and the electrode 1 is contacted with the charged fine particles as a sample 127.
21 and 122 are arranged, a voltage is applied between the electrodes, and a current flowing at that time is measured to obtain a specific resistance.
When the fine particles are filled, the filling is performed while rotating the upper electrode 121 right and left so that the electrode uniformly contacts the sample. In the above measuring method, the measuring conditions of the specific resistance are as follows: the contact area S between the filled fine particles and the electrode is about 2.3 cm ² , the thickness d is about 2 mm, the load of the upper electrode 122 is 180 g, and the applied voltage is 100 V.

Next, the toner used in the developer of the present invention will be described.

The toner according to the present invention has a weight average particle size of 3.
0 to 10.0 μm, and preferably 4.5 to 9.0 μm. In addition, the cumulative value of the distribution not more than 1/2 times the number average particle diameter is 20 number% or less, and the weight average particle diameter is 2% or less.
It is preferable that the cumulative value of the distribution having a diameter of not less than the diameter is 10% by volume or less in order to improve the chargeability without reversal components and to improve the reproducibility of the latent image dots. In order to further improve the triboelectric chargeability of the toner and enhance the dot reproducibility, the cumulative value of the distribution having a diameter equal to or less than 1/2 times the number average particle diameter is 15% by number or less,
It is more preferred that the cumulative value of the distribution of twice or more the weight average particle size is 5% by volume or less. Furthermore, the number average particle size of 1
It is further preferred that the cumulative value of the distribution not more than / 2 times the diameter is 10% by number or less, and the cumulative value of the distribution not less than twice the diameter of the weight average particle diameter is 2% by volume or less.

The weight average particle diameter (D4) of the toner is 10.0
If it exceeds μm, the toner particles for developing the electrostatic image become large, so that it is difficult to faithfully develop the electrostatic image even if the magnetic force of the carrier is reduced, and if the electrostatic transfer is performed, the toner Becomes splattered easily. On the other hand, a toner having a weight average particle diameter of less than 3 μm has poor powder handling properties.

If the cumulative value of the distribution of 径 or less of the number average particle diameter exceeds 20% by number, the toner charge cannot be properly applied to the fine toner particles, and the toner has a wide tribo distribution. Due to poor charging (generation of a reversal component) and uneven distribution of the particle diameter of the developed toner, a problem of a change in particle diameter during durability is likely to occur. On the other hand, if the cumulative value of the distribution having a diameter twice or more the weight average particle diameter exceeds 10% by volume, it becomes difficult to satisfactorily perform triboelectric charging with the carrier, and it becomes difficult to faithfully reproduce an electrostatic charge image. The particle size distribution of the toner can be measured by, for example, a method using a Coulter counter.

As the binder resin used for the toner, the following binder resins can be used.

For example, homopolymers of styrene and its substituted substances such as polystyrene, poly-p-chlorostyrene and polyvinyl toluene; styrene-p-chlorostyrene copolymer, styrene-vinyltoluene copolymer, styrene-
Vinyl naphthalene copolymer, styrene-acrylic ester copolymer, styrene-methacrylic ester copolymer, styrene-α-chloromethyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-
Styrene such as vinyl methyl ether copolymer, styrene-vinyl ethyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-acrylonitrile-indene copolymer -Based copolymer; polyvinyl chloride; phenolic resin; natural modified phenolic resin; natural resin modified maleic acid resin; acrylic resin; methacrylic resin; polyvinyl acetate; silicone resin; polyester resin; A xylene resin; a polyvinyl butyral; a terpene resin; a cumarone indene resin; Preferred binder resins include styrene copolymers and polyester resins.

Further, a crosslinked styrene resin is also a preferable binder resin.

The styrene-based polymer or styrene-based copolymer may be cross-linked, or may be a mixed resin of a cross-linked resin and a non-cross-linked resin.

As the crosslinking agent for the binder resin, a compound having two or more polymerizable double bonds may be mainly used. For example, aromatic divinyl compounds such as divinylbenzene and divinylnaphthalene; ethylene glycol diacrylate, ethylene glycol dimethacrylate,
Carboxylic acid esters having two double bonds such as 1,3-butanediol dimethacrylate; divinyl compounds such as divinylaniline, divinylether, divinylsulfide and divinylsulfone; and compounds having three or more vinyl groups. Can be These are used alone or as a mixture.

The amount of the crosslinking agent to be added may be as follows.
0.001 to 10 parts by weight based on 00 parts by weight is preferred.

The toner may contain a charge control agent.

The following substances control the toner to be negatively charged.

For example, organic metal compounds and chelate compounds are effective, and monoazo metal compounds, acetylacetone metal compounds, aromatic hydroxycarboxylic acids, and aromatic dicarboxylic acid-based metal compounds are preferably used. Further, aromatic hydroxycarboxylic acids, aromatic mono- and polycarboxylic acids and their metal salts, their anhydrides, their esters, their phenol derivatives such as bisphenol; urea derivatives; metal-containing salicylic acid-based compounds; Metal naphthoic acid compound; boron compound;
Quaternary ammonium salts; calixarenes; silicon compounds; styrene-acrylic acid copolymers; styrene-methacrylic acid copolymers; styrene-acrylic-sulfonic acid copolymers; and nonmetal carboxylic acid compounds.

These charge control agents are used in an amount of 0.01 to 20 parts by weight, preferably 0.1 to 10 parts by weight, more preferably 0.2 to 4 parts by weight, based on 100 parts by weight of the resin component of the toner. Good to do.

As the colorant of the toner used in the present invention, carbon black, a magnetic substance, and a black colorant using the following yellow / magenta / cyan colorant as a black colorant are used.

Examples of the yellow colorant include condensed azo compounds, isoindolinone compounds, anthraquinone compounds,
Compounds represented by azo metal complexes, methine compounds and allylamide compounds are used. Specifically, C.I. I. Pigment Yellow 12, 13, 14, 15, 17, 6
2, 74, 83, 93, 94, 95, 109, 110,
111, 128, 129, 147, 168 or 180 are preferably used. Further, C.I. I. Dyes such as Solvent Yellow 93 and 162 may be used.

As the magenta coloring agent, condensed azo compounds, diketopyrrolopyrrole compounds, anthraquinones, quinacridone compounds, basic dye lake compounds, naphthol compounds, benzimidazolone compounds, thioindigo compounds and perylene compounds are used. Specifically, C.I.
I. Pigment Red 2, 3, 5, 6, 7, 23, 4
8: 2, 48: 3, 48: 4, 57: 1, 81: 1, 1
44, 146, 166, 169, 177, 184, 18
5, 202, 206, 220, 221 or 254 are preferably used.

As the cyan coloring agent, copper phthalocyanine compounds and derivatives thereof, anthraquinone compounds, basic dye lake compounds and the like can be used. Specifically, C.I. I.
Pigment Blue 1, 7, 15, 15: 1, 15: 2,
15: 3, 15: 4, 60, 62, 66 can be particularly preferably used.

These colorants can be used alone or as a mixture or in the form of a solid solution. The colorant of the present invention is selected from the viewpoints of hue angle, saturation, brightness, weather resistance, OHP transparency, and dispersibility in toner. The colorant is used in an amount of 1 to 20 parts by weight based on 100 parts by weight of the resin.

Further, the wax is used as the binder resin 10 of the toner.
1 to 40 parts by weight per 0 parts by weight, preferably 2 to 40 parts by weight
You may mix 30 weight part.

In the production of a pulverized toner in which a mixture having a binder resin, a colorant and a wax is melt-kneaded, cooled, pulverized and then classified to obtain toner particles, the amount of wax added is 100 parts by weight of the binder resin. It is preferable to use 1 to 10 parts by weight, more preferably 2 to 7 parts by weight.

In a polymerized toner production method in which toner particles are directly obtained by polymerizing a mixture containing a polymerizable monomer, a colorant and a wax, the amount of the wax added is determined by the amount of the polymerizable monomer or polymerizable monomer. 2 to 40 parts by weight, more preferably 5 to 30 parts by weight, even more preferably 10 to 2 parts by weight per 100 parts by weight of the resin synthesized by polymerization of the monomer.
It is preferred to use 0 parts by weight.

Since the wax used in the polymerization toner production method is lower in polarity than the binder resin as compared with the pulverized toner production method, a large amount of wax is easily included in the toner particles by the polymerization method in an aqueous medium. In comparison, a large amount of wax can be used, which is particularly effective for the effect of preventing offset during fixing.

If the amount of the wax is less than the lower limit, the effect of preventing offset tends to decrease, and if it exceeds the upper limit, the anti-blocking effect is reduced and the anti-offset effect is liable to be adversely affected. In particular, in the case of a polymerization toner production method, a toner having a wide particle size distribution tends to be produced.

Next, a method for producing the toner used in the present invention will be described. The toner used in the present invention can be manufactured using a pulverized toner manufacturing method and a polymerized toner manufacturing method.

In the present invention, a method for producing a pulverized toner includes a binder resin, a wax, a pigment as a colorant, a dye or a magnetic material, a charge controlling agent, and other additives as necessary. The resulting mixture is melt-kneaded using a heat kneader such as a heating roll, kneader, extruder and the like, and the metal components, pigments, dyes, and magnetic materials are mixed while the resin components are mutually mixed. The kneaded product is cooled and solidified, and then pulverized and classified to obtain a toner.

Further, if necessary, the toner and the desired additive are sufficiently mixed by a mixer such as a Henschel mixer,
The toner used in the present invention can be obtained.

The method for producing a polymerized toner is described in JP-B-56-13.
No. 945, etc., a method of atomizing a molten mixture into air using a disk or a multi-fluid nozzle to obtain a spherical toner, Japanese Patent Publication No. Sho 36-10231, and Japanese Patent Application Laid-Open No. Sho 59-53.
No. 856, JP-A-59-61842, a method of directly producing a toner using a suspension polymerization method, an aqueous organic solvent which is soluble in a monomer and insoluble in a polymer obtained. An emulsion polymerization method typified by a dispersion polymerization method in which a toner is directly produced using a water-soluble polar polymerization initiator or a soap-free polymerization method in which a toner is produced by directly polymerizing in the presence of a water-soluble polar polymerization initiator, or a method in which primary polar emulsion polymerization particles are previously prepared. It is possible to produce a toner using a hetero-aggregation method in which polar particles having opposite charges are added and associated.

Of these, a method in which toner particles are produced by directly polymerizing a monomer composition containing at least a polymerizable monomer, a colorant and a wax is preferred.

A so-called seed polymerization method in which a monomer is further adsorbed on the polymer particles once obtained and then polymerized using a polymerization initiator can also be suitably used in the present invention.

Next, the external additives externally added to the toner particles will be described.

The toner used in the present invention comprises fine particles of inorganic fine particles such as silica, alumina, and titanium oxide; It is preferable that it is done. By externally adding the above-described fine powder to the toner, the fine powder exists between the toner and the carrier or between the toner particles, whereby the fluidity of the developer is improved, and the life of the developer is also increased. improves. The average particle size of the fine powder described above is preferably 0.2 μm or less. When the average particle size exceeds 0.2 μm, the effect of improving the fluidity decreases,
In some cases, image quality is degraded due to a defect during development or transfer. The measurement of the average particle size of these fine powders will be described later.

The surface area of these fine powders is BET
Specific surface area by nitrogen adsorption 30 m ² / g or more by law, is excellent particularly in the range of 5~400m ² / g. The addition amount of the fine powder is preferably 0.1 to 20 parts by weight based on 100 parts by weight of the toner.

Since the toner is a negatively chargeable toner, it is preferable to use at least one kind of silica which has been subjected to hydrophobic treatment from the viewpoint of chargeability. That is, since silica has a higher negative chargeability than a fluidizing agent such as alumina or titanium oxide, the adhesion to the toner matrix is high, and the amount of liberated external additives is reduced. Therefore, filming on the electrostatic image carrier and contamination of the charging member can be suppressed.

The silica is preferably subjected to a hydrophobic treatment in order to maintain the chargeability under high humidity. An example of the hydrophobic treatment is shown below.

One of the hydrophobizing agents is a silane coupling agent. The amount of the silane coupling agent is 1 to 40 parts by weight, preferably 2 to 35 parts by weight, based on 100 parts by weight of the inorganic fine powder. Is good. When the amount is 1 to 40 parts by weight, moisture resistance is improved and aggregates are hardly generated.

As another hydrophobizing agent, silicone oil can be mentioned.

Additives for imparting various toner properties may have a particle size of not more than 1/5 of the volume average particle size of the toner particles from the viewpoint of durability when added to the toner or when added to the toner. preferable. The particle size of the additive means an average particle size obtained by observing the surface of the toner particles with an electron microscope. As additives for the purpose of imparting these properties, for example, the following are used.

Examples of the fluidity-imparting agent include metal oxides such as silicon oxide, aluminum oxide and titanium oxide;
Carbon black; and carbon fluoride.
Each of these is preferably subjected to a hydrophobic treatment.

Examples of the abrasive include metal oxides such as strontium titanate, cerium oxide, aluminum oxide, magnesium oxide and chromium oxide; nitrides such as silicon nitride; carbides such as silicon carbide; and calcium sulfate and sulfuric acid. Metal salts such as barium and calcium carbonate are mentioned.

Examples of the lubricant include fluororesin powders such as vinylidene fluoride and polytetrafluoroethylene; and fatty acid metal salts such as zinc stearate and calcium stearate.

Examples of the charge control particles include tin oxide,
Metal oxides such as titanium oxide, zinc oxide, silicon oxide and aluminum oxide; and carbon black.

These additives are preferably used in an amount of 0.1 to 10 parts by weight, more preferably 0.1 to 5 parts by weight, based on 100 parts by weight of the toner particles. These additives may be used alone or in combination of two or more.

In the present invention, when a two-component developer is prepared by mixing a toner and a carrier, the mixing ratio is 2% by weight to 15% by weight as the toner concentration in the developer.
Good results are obtained when the content is preferably 4% to 13% by weight. If the toner concentration is less than 2% by weight, the image density tends to be low, and if it exceeds 15% by weight, fogging and scattering in the machine are liable to occur, and the useful life of the developer tends to decrease.

The ratio a / b of the weight average particle diameter a of the toner to the number average particle diameter b of the carrier is preferably 0.1 to 0.3. If the ratio is less than 0.1, it becomes difficult to appropriately charge the toner, and fog or toner scattering in a high humidity environment is likely to occur. On the other hand, if it exceeds 0.3, the charge amount of the toner particularly under low humidity becomes too high, which tends to cause a decrease in image density and fog.

As a developing method using the carrier of the present invention, for example, development can be performed using a developing means as shown in FIG. Specifically, it is preferable to perform development in a state where the magnetic brush is in contact with the latent image carrier, for example, the photosensitive drum 1 while applying an alternating electric field. The distance (S-D distance) B between the developer carrier (developing sleeve) 11 and the photosensitive drum 1 is preferably 100 to 1000 [mu] m in order to prevent carrier adhesion and improve dot reproducibility.
If it is smaller than 100 μm, the supply of the developer tends to be insufficient and the image density is lowered. If it is larger than 1000 μm, the magnetic field lines from the magnetic pole S ₁ are widened and the density of the magnetic brush is reduced, resulting in poor dot reproducibility or poor carrier performance. The binding force is weakened and carrier adhesion is likely to occur.

The voltage between the peaks of the alternating electric field is 300 to 30.
00V is preferable, the frequency is 500 to 10000 Hz,
Preferably, it is 1000-7000 Hz, and each can be appropriately selected and used depending on the process. In this case, the waveform may be triangular, rectangular, sine, or D
Various waveforms with different duty ratios, intermittent alternating superposed electric fields, and the like can be selected and used. If the applied voltage is lower than 300 V, it may be difficult to obtain a sufficient image density, and it may not be possible to satisfactorily collect fog toner in the non-image area. If the voltage exceeds 5000 V, the latent image may be disturbed via the magnetic brush, which may cause deterioration in image quality.

By using a two-component developer having a well-charged toner, the fog removal voltage (Vback)
And the primary charge of the photoconductor can be reduced, so that the life of the photoconductor can be extended. Vbac
k is preferably 200 V or less, more preferably 150 V or less, depending on the developing system.

The contrast potential is preferably from 100 V to 400 V so that a sufficient image density can be obtained.

When the frequency is lower than 500 Hz, although it depends on the process speed, when the toner in contact with the electrostatic image carrier is returned to the developing sleeve, sufficient vibration is not given and fog is liable to occur. When the frequency exceeds 10,000 Hz, the toner cannot follow the electric field, and the image quality is liable to be deteriorated.

In the image forming method of the present invention, three or more developing units for magenta, cyan and yellow are used in outputting a full-color image in which halftone is particularly important. By using the developing method, particularly in combination with a developing system that forms a digital latent image, it is possible to develop the dot latent image faithfully without being affected by the magnetic brush and disturbing the latent image. Also in the transfer step, a high transfer rate can be achieved by using a fine-particle-cut toner having a sharp particle size distribution, so that high image quality can be achieved in both the halftone portion and the solid portion.

Further, by using the two-component developer according to the present invention together with the initial improvement in image quality, the share of the developer in the developing unit is small, and the present invention does not cause a deterioration in image quality even when copying a large number of sheets. The effect of can be fully exhibited.

In order to obtain a tighter image, it is preferable to have developing devices for magenta, cyan, yellow, and black, and to exhibit a tighter image by performing black development last. Can be.

An image forming method according to the present invention will be described with reference to the accompanying drawings.

In FIG. 1, a magnetic brush made of magnetic particles 23 is formed on the surface of the transfer sleeve 22 by the magnetic force of the magnet roller 21, and this magnetic brush contacts the surface of the electrostatic image carrier (photosensitive drum) 1. Then, the photosensitive drum 1 is charged. A charging bias is applied to the transport sleeve 22 by a bias applying unit (not shown). By irradiating the charged photosensitive drum 1 with laser light 24 by an exposure device (not shown), a digital electrostatic charge image is formed. The electrostatic charge image formed on the photosensitive drum 1 includes a magnet roller 12 and a developer 19 carried on a developing sleeve 11 to which a developing bias is applied by a bias applying device (not shown).
It is developed by the toner 19a inside.

The developing device 4 includes a partition 17 and a developer chamber R.
_1, is divided into the stirring chamber R _2, respectively developer conveying screw 13, 14 is installed. Above the stirring chamber R _2, a toner storage chamber R ₃ containing a replenishing toner 18 is installed, supply opening 20 is provided in a lower portion of the storage chamber R _3.

The developer transport screw 13 rotates to transport the developer in the developer chamber R1 in _one direction along the longitudinal direction of the developing sleeve 11 while stirring. The partition 17 is provided with openings (not shown) on the near side and the back side in the drawing, and the developer conveyed to _one of the developer chambers R1 by the screw 13 passes through the opening of the partition 17 on one side. The developer is sent to the stirring chamber R ₂ and transferred to the developer transport screw 14. In the direction of rotation the screw 13 opposite the screw 14, the developer in the stirring chamber R _2, the developer chamber R ₁
Stirring the toner supplied from the passed developer and toner storage chamber R ₃ from, with mixing, the screw 13 and conveyed in the stirring chamber R ₂ in the opposite direction, through the other opening of the partition wall 17 sent into the developer chamber R _1.

[0147] To develop the electrostatic latent image formed on the photosensitive drum 1, the developer 19 in the developer chamber R ₁ is drawn up by the magnetic force of the magnet roller 12, the developing sleeve 1
1 is carried on the surface. The developer carried on the developing sleeve 11 is conveyed to the regulating blade 15 with the rotation of the developing sleeve 11, where it is regulated to a thin developer layer having an appropriate layer thickness. To the development area opposed to it. The portion corresponding to the developing area of the magnet roller 12, the magnetic poles are (developing pole) N ₁ is positioned, the developing pole N ₁ forms a developing magnetic field in the developing area,
This developer magnetic field causes the developer to spike, and a magnetic brush of the developer is generated in the development area. Then, the magnetic brush contacts the photosensitive drum 1, and the toner adhered to the magnetic brush and the toner adhered to the surface of the developing sleeve 11 are transferred to the electrostatic image area on the photosensitive drum 1 by the reversal developing method. Then, the electrostatic image is developed to form a toner image.

The developer that has passed through the developing area is returned into the developing device 4 as the developing sleeve 11 rotates, and the magnetic pole S
Due to the repelling magnetic field between S ₁ and S ₂ , it is peeled off from the developing sleeve 11 and falls into the developer chamber R ₁ and the stirring chamber R ₂ to be collected.

By the above development, the developer 1 in the developing device 4
T / C ratio of 9 (toner and mixing ratio of the carrier, i.e., toner concentration in the developer) When decreases is, the agitation chamber R in an amount that was seen from the toner storage chamber R ₃ to the amount consumed toner 18 in the developing ₂ and the T / C of the developer 19 is maintained at a predetermined amount. To detect the T / C ratio of the developer 19 in the container 4,
A toner concentration detection sensor that measures a change in the magnetic permeability of the developer using the inductance of the coil is used. The toner concentration detection sensor has a coil (not shown) therein.

The regulating blade 15 arranged below the developing sleeve 11 and regulating the layer thickness of the developer 19 on the developing sleeve 11 is a non-magnetic blade 15 made of a non-magnetic material such as aluminum or SUS316. The distance between the end and the surface of the developing sleeve 11 is 300 to 1000 μm.
m, preferably 400 to 900 μm. If the distance is less than 300 μm, the magnetic carrier is clogged during this time, and the developer layer is likely to be uneven, and it is difficult to apply the developer necessary for good development, and a developed image having a low density and many unevenness is formed. Easy to be. This distance is preferably 400 μm or more in order to prevent non-uniform application (so-called blade jam) due to unnecessary particles mixed in the developer. If it is larger than 1000 μm, the amount of the developer applied on the developing sleeve 11 increases, and it is difficult to regulate a predetermined thickness of the developer layer. The regulation of development by the blade 15 is weakened, so that toner tribo is reduced 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 and gravity and the conveying force in the moving direction of the developing sleeve 11. Movement slows down. 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 magnetic carrier particles, the magnetic carrier particle layer becomes closer to the sleeve so that the magnetic pole N ₁ becomes closer to the sleeve.
To form a moving layer. Due to the movement of the magnetic carrier particles, the developer is conveyed to the developing area with the rotation of the developing sleeve 11 and is used for development.

Further, the developed toner image is transferred onto a transfer material (recording material) 25 conveyed by a bias applying means 2.
The toner image transferred by the transfer blade 27 as a transfer unit to which a transfer bias is applied by 6 and transferred onto the transfer material is fixed to the transfer material by a fixing device (not shown). In the transfer step, the transfer residual toner remaining on the photosensitive drum 1 without being transferred to the transfer material is adjusted in charge in the charging step, and is collected during development.

FIG. 3 is a schematic diagram in which the image forming method of the present invention is applied to a full-color image forming apparatus employing a cleanerless system.

The main body of the full-color image forming apparatus includes a first image forming unit Pa, a second image forming unit Pb,
An image forming unit Pc and a fourth image forming unit Pd are provided side by side, and images of different colors are formed on a transfer material through a process of forming, developing, and transferring a latent image.

The configuration of each image forming unit provided in the image forming apparatus will be described with reference to the first image forming unit Pa as an example.

The first image forming unit Pa includes an electrophotographic photosensitive drum 6 having a diameter of 30 mm as an electrostatic image carrier.
1a, the photosensitive drum 61a is rotated in the direction of arrow a. Reference numeral 62a denotes a primary charger as a charging unit, and a magnetic brush formed on the surface of a sleeve having a diameter of 16 mm is arranged so as to contact the surface of the photosensitive drum 61a. Reference numeral 67a denotes a laser beam for forming an electrostatic charge image on the photosensitive drum 61a, the surface of which is uniformly charged by the primary charger 62a, and is irradiated by an exposure device (not shown). 63a is the photosensitive drum 6
The developing device is a developing device as a developing unit for forming a color toner image by developing the electrostatic charge image carried on 1a, and holds a color toner. Reference numeral 64a denotes a transfer blade as transfer means for transferring the color toner image formed on the surface of the photosensitive drum 61a to the surface of a transfer material (recording material) conveyed by a belt-shaped transfer material carrier 68. The transfer blade 64a can apply a transfer bias by contacting the back surface of the transfer material carrier 68.

The first image forming unit Pa uniformly and primary charges the photosensitive drum 61a with the primary charger 62a, forms an electrostatic image on the photosensitive member with the exposure device 67a, and forms the electrostatic image with the developing device 63a. Is developed using a color toner, and the developed toner image is transferred to a back surface side of a belt-shaped transfer material carrier 68 which carries and conveys the transfer material at a first transfer portion (a contact position between the photoconductor and the transfer material). A transfer bias is applied from a transfer blade 64a that comes into contact with the transfer member to transfer the image onto the surface of the transfer material.

When the toner is consumed by the development and the T / C ratio decreases, the decrease is detected by a toner concentration detecting sensor 85 for measuring a change in the magnetic permeability of the developer using the inductance of the coil, and the toner is consumed. The supply toner 65 is supplied according to the toner amount. The toner density detection sensor 85 has a coil (not shown) therein.

This image forming apparatus has the same configuration as the first image forming unit Pa, and has the second image forming unit Pb, the third image forming unit Pc, and the third image forming unit Pc having different colors of the color toner held in the developing device. Four image forming units of the fourth image forming unit Pd are provided side by side. For example, yellow toner is used for the first image forming unit Pa, magenta toner is used for the second image forming unit Pb, cyan toner is used for the third image forming unit Pc, and black toner is used for the fourth image forming unit Pd. The transfer of each color toner onto the transfer material is sequentially performed in the transfer section of each image forming unit. In this step, while the registration is being performed, each color toner is superimposed on the same transfer material by one transfer of the transfer material, and when the transfer is completed, the transfer material is separated from the transfer material carrier 68 by the separation charger 69. The sheet is sent to the fixing device 70 by a conveying means such as a conveying belt, and the final full-color image is obtained by a single fixing.

The fixing device 70 has a pair of a fixing roller 71 having a diameter of 40 mm and a pressure roller 72 having a diameter of 30 mm. The fixing roller 71 has heating means 75 and 76 inside.

The unfixed color toner image transferred onto the transfer material passes through the pressure contact portion between the fixing roller 71 and the pressure roller 72 of the fixing device 70, and is applied to the transfer material by the action of heat and pressure. Is established.

In FIG. 3, the transfer material carrier 68 is an endless belt-like member, which is moved in the direction of arrow e by a driving roller 80. 7
9 is a transfer belt cleaning device, 81 is a belt driven roller, and 82 is a belt static eliminator. 8
Reference numeral 3 denotes a pair of registration rollers for conveying the transfer material in the transfer material holder to the transfer material carrier 68.

The transfer means is a contact transfer in which a transfer bias can be directly applied by contacting the back surface of a transfer material carrier such as a roller-shaped transfer roller instead of the transfer blade contacting the back surface of the transfer material carrier. Means can be used.

Further, in place of the above-mentioned contact transfer means, a non-contact type in which transfer is performed by applying a transfer bias from a corona charger arranged in a non-contact manner on the back side of a generally used transfer material carrier. May be used.

However, it is more preferable to use the contact transfer means because the amount of ozone generated when the transfer bias is applied can be controlled.

In the image forming method of the present invention, a toner image obtained by developing the electrostatic image formed on the latent image carrier can be transferred to a recording material via an intermediate transfer member.

A specific example of the measurement of the toner particle size will be described below.

0.1 to 5 ml of a surfactant (alkylbenzenesulfonate) is added to 100 to 150 ml of the electrolyte solution.
And 2 to 20 mg of a measurement sample is added thereto. The electrolytic solution in which the sample was suspended was subjected to dispersion treatment for 1 to 3 minutes by an ultrasonic disperser, and the above-mentioned Coulter counter multisizer was used to adjust the volume of the electrolyte to a value of 0.1 μm based on the volume using an aperture appropriately adjusted to a toner size of 17 μm or 100 μm. 3 ~
A particle size distribution of 40 μm is to be measured. The number average particle diameter and the weight average particle diameter measured under these conditions are obtained by computer processing, and the cumulative ratio of the number average particle diameter smaller than 1/2 times the diameter cumulative distribution is calculated from the number-based particle diameter distribution,
A cumulative value equal to or smaller than the 1/2 diameter cumulative distribution is obtained. Similarly, a cumulative ratio equal to or larger than the double diameter cumulative distribution of the weight average particle diameter is calculated from the volume-based particle size distribution, and a cumulative value equal to or larger than the double diameter cumulative distribution is obtained.

The method for measuring the triboelectric charge amount will be described.

1.6 g of toner and 18.4 g of magnetic carrier
Is placed in a 50 cc polyethylene container and left open for one day under each environment. In a high-temperature and high-humidity environment, the sample is sealed after standing and the apparatus is further left for 2 hours so that the sample does not dew. Mix the powder (developer) in a metal container equipped with a 625 mesh conductive screen at the bottom, suction with a suction machine, and mix the powder with the weight difference before and after suction. The amount of triboelectric charge is determined from the potential stored in the connected capacitor. On this occasion,
The suction pressure is 250 mmHg. With this method, the triboelectric charge amount is calculated using the following equation.

Q (mC / kg) = (C × V) × (W ₁ −W ₂ ) ⁻¹ (where W ₁ is the weight before suction, W ₂ is the weight after suction, and C Is the capacity of the capacitor, and V is the potential stored in the capacitor.)

The amount of triboelectric charge of the toner in the developer at the time of the endurance was determined by sampling 1 g of the developer on the developing sleeve.
The measurement was performed using the above-mentioned measuring device without mixing and stirring.

[0174]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Production Examples and Examples, but this does not limit the present invention in any way. The number of parts described in the examples indicates parts by weight.

(Production Example 1 of Hydrophobic Iron Oxide) A ferrous sulfate aqueous solution is mixed with 1.0 to 1.1 equivalents of a caustic soda solution with respect to iron ions, and an aqueous solution containing ferrous hydroxide is added. Prepared.

The pH of the aqueous solution is adjusted to pH 7 to 10 (for example, pH
While maintaining the condition of 9), air was blown in to perform an oxidation reaction at 80 to 90 ° C. to prepare a slurry liquid for generating seed crystals.

Next, the slurry was added in an amount of 0.9 to 1.0 with respect to the initial alkali amount (sodium component of caustic soda).
After adding an aqueous solution of ferrous sulfate to 2 equivalents, the pH of the slurry solution is maintained at 6 to 10 (for example, pH 8), and the oxidation reaction is promoted while blowing air, and the pH is adjusted at the end of the oxidation reaction. 0.5 parts of a coupling agent (γ-glycidyltrimethoxysilane) was added, and the mixture was sufficiently stirred.
The produced hydrophobic iron oxide particles were washed, filtered and dried by a conventional method, and then the aggregated particles were crushed to obtain hydrophobic iron oxide 1 having an average particle size of 0.22 μm.

(Production Example 2 of Hydrophobic Iron Oxide) The oxidation reaction was carried out in the same manner as in Production Example 1, and the magnetic iron oxide particles produced after the oxidation reaction were washed, filtered, taken out, and dried without drying in another aqueous medium. After redispersion in, adjust the pH of the redispersion,
While sufficiently stirring, 0.5 part of a silane coupling agent (γ-glycidyltrimethoxysilane) was added to perform a coupling treatment. The produced hydrophobic iron oxide particles were washed, filtered and dried by a conventional method, and then the aggregated particles were crushed to obtain hydrophobic iron oxide 2 having an average particle diameter of 0.20 μm.

(Production Example 3 of Hydrophobic Iron Oxide) As a silane coupling agent,

[0180]

Embedded image Was obtained in the same manner as in Production Example 2 except that the above-mentioned was used, to thereby obtain a hydrophobic iron oxide 3 having an average particle size of 0.24 μm.

(Production Example 4 of Hydrophobic Iron Oxide) As a silane coupling agent,

[0182]

Embedded image Was obtained in the same manner as in Production Example 2 except for using a hydrophobic iron oxide 4 having an average particle size of 0.21 μm.

(Production Example 5 of Hydrophobic Iron Oxide) A caustic soda solution in an amount of 1.0 to 1.1 equivalents to iron ions was mixed with an aqueous ferrous sulfate solution, and an aqueous solution containing ferrous hydroxide was added. Prepared.

The pH of the aqueous solution is adjusted to pH 7 to 10 (for example, pH
While maintaining the condition of 9), air was blown in to perform an oxidation reaction at 80 to 90 ° C. to prepare a slurry liquid for generating seed crystals.

Next, the slurry was added to the slurry in an amount of 0.9 to 1.0 with respect to the initial alkali amount (sodium component of caustic soda).
After adding an aqueous solution of ferrous sulfate to 2 equivalents, the slurry is maintained at pH 6 to 10 (for example, pH 8), and the oxidation reaction is promoted while blowing air, and the pH is adjusted at the final stage of the oxidation reaction. The reaction was completed. The produced particles were washed, filtered and dried by a conventional method, and then the aggregated particles were crushed to obtain iron oxide particles 1.

The obtained iron oxide particles 1 were used as a silane coupling agent in the gas phase.

[0187]

Embedded image To obtain a hydrophobic iron oxide 5 having an average particle size of 0.42 μm.

(Production Example 6 of Hydrophobic Iron Oxide) The iron oxide particles 1 obtained in Production Example 5 of hydrophobic iron oxide were dispersed in an aqueous solution, and the pH of the aqueous iron oxide dispersion was adjusted. As a ring agent,

[0189]

Embedded image Was added and mixed and stirred sufficiently. The produced particles were washed, filtered and dried by a conventional method, and then the aggregated particles were crushed to obtain hydrophobic iron oxide 6 having an average particle size of 0.26 μm.

<Production Example 1 of Magnetic Carrier> ・ 50 parts of phenol (hydroxybenzene) ・ 80 parts of 37 wt% formalin aqueous solution ・ 50 parts of water ・ 600 parts of hydrophobic iron oxide 2 ・ 15 parts of 25% aqueous ammonia

The above materials were placed in a four-necked flask, and the temperature was raised to 85 ° C. for 60 minutes while stirring and mixing, and the mixture was reacted and cured for 120 minutes. After cooling to 30 ° C. and addition of 500 parts by weight of water, the supernatant was removed, and the precipitate was washed with water and air-dried. Then, this is put under reduced pressure (5 mmHg) 1
After drying at 50 to 180 ° C. for 24 hours, a magnetic carrier core (A) using a phenol resin as a binder resin was obtained. 0.4% by weight of adsorbed water was present in the magnetic carrier core (A) at 30 ° C./80% for 24 hours.

A 5% by weight solution of γ-aminopropyltrimethoxysilane in toluene was applied to the surface of the obtained magnetic carrier core (A).

The surface of the magnetic carrier core (A) was 0.2
It had been treated with γ-aminopropyltrimethoxysilane by weight. During the application, the toluene was volatilized while applying while continuously applying shear stress to the magnetic carrier core (A). On the surface of the magnetic carrier core (A)

[0194]

Embedded image Was confirmed to be present.

While stirring the magnetic carrier core (A) treated with the silane coupling agent in the above processing machine at 70 ° C., the silicone resin KR-221 (manufactured by Shin-Etsu Chemical Co., Ltd.) was added to the silicone resin solid component. On the other hand, 3% by weight of γ-aminopropyltrimethoxysilane was added, diluted with toluene so as to have a silicone resin solid content of 20% by weight, and then added under reduced pressure to coat the resin.

Thereafter, after stirring for 2 hours, heat treatment was performed at 140 ° C. for 2 hours in an atmosphere of nitrogen gas to loosen agglomeration, coarse particles of 200 mesh or more were removed, and σ ₁₀₀₀ was 65 Am ² / kg, Average particle size is 35 μm, SF-1 is 1
07 magnetic carrier I was obtained.

<Production Examples 2-6 of Magnetic Carrier> Production Example 1
, Except that hydrophobic iron oxides 1, 3, 4, 5, and 6 were used, to obtain magnetic carriers II to VI having σ ₁₀₀₀ of 65 Am ² / kg and an average particle diameter of 35 μm. S
F-1 is, in order, 112 (II), 117 (III),
108 (IV), 115 (V) and 107 (VI).

<Production Example 7 of Magnetic Carrier> The procedure of Production Example 1 was repeated except that iron oxide particles 1 not subjected to lipophilic treatment in Production Example 5 were used, and σ ₁₀₀₀ was 63 Am ² /
kg, a magnetic carrier VII having an average particle diameter of 39 μm and an SF-1 of 121 was obtained.

<Production Example 8 of Magnetic Carrier> The procedure of Production Example 1 was repeated, except that 400 parts of hydrophobic iron oxide 2 and 200 parts of hydrophobic alumina were used instead of 600 parts of hydrophobic iron oxide 2. To obtain a magnetic carrier VIII having σ ₁₀₀₀ of 43 Am ² / kg and an average particle diameter of 40 μm.

Toner Production Example 1 450 parts of a 0.1 M Na ₃ PO ₄ aqueous solution was charged into 710 parts of ion-exchanged water and heated to 60 ° C., and then a TK homomixer (manufactured by Tokushu Kika Kogyo) was used. And stirred at 1300 rpm. To this, 68 parts of a 1.0 M CaCl ₂ aqueous solution was gradually added to obtain a pH 6 aqueous medium containing Ca ₃ (PO ₄ ) ₂ . 160 parts of styrene 34 parts of n-butyl acrylate 12 parts of copper phthalocyanine pigment 2 parts of metal compound ditertiary butyl salicylate 10 parts of saturated polyester (acid value 10 mg KOH / g, peak molecular weight 8500) Monoester wax 20 parts (Mw : 500, Mn: 400, Mw / Mn: 1.25, melting point: 69 ° C, viscosity: 6.5 mPa · s, Vickers hardness: 1.1, SP value: 8.6)

The above-mentioned material was heated to 60 ° C., and was subjected to 12000 rpm using a TK homomixer (manufactured by Tokushu Kika Kogyo).
To dissolve and disperse uniformly. In addition, polymerization initiator 2,
2'-azobis (2,4-dimethylvaleronitrile) 1
0 g was dissolved to prepare a polymerizable monomer composition. The polymerizable monomer composition was charged into the aqueous medium, and the mixture was heated at 60 ° C. and N ₂
Under an atmosphere, the mixture was stirred at 10,000 rpm for 10 minutes with a CLEAR MIXER (manufactured by M Technique Co., Ltd.) to granulate the polymerizable monomer composition. Thereafter, the temperature was raised at 80 ° C. while stirring the aqueous medium with a paddle stirring blade, and a polymerization reaction was carried out for 10 hours while maintaining the pH at 6.

After the completion of the polymerization reaction, the mixture was cooled, hydrochloric acid was added to adjust the pH to 2 to dissolve the calcium phosphate, and then filtered, washed with water and dried to obtain polymer particles (toner particles).

The obtained polymer particles contained 8.4 parts of a monoester wax per 100 parts of the binder resin, and the wax was converted to the outer resin by a tomographic method of measuring the polymer particles using a transmission electron microscope (TEM). A core-shell structure encapsulated in the layer was confirmed.

Further, the binder resin of the obtained polymer particles was S
The P value was 19 and the Tg was 60 ° C.

To 100 parts of the obtained polymer particles (toner particles), the following three external additives were externally added, and after the external addition, coarse particles were removed with a 330-mesh (mesh 43 μm) sieve. And negatively charged cyan toner No. 1 was obtained. Cyan toner No. 1 had a weight average particle size of 7.3 μm and SF-1 was 108.

(1) 0.3 parts of first hydrophobic silica fine powder: BET specific surface area 170 m ² / g Number average particle diameter 12 nm 20 parts of hexamethyldisilazane in the gas phase with respect to 100 parts of silica fine powder Hydrophobized.

(2) Second hydrophobic silica fine powder 0.7 part: BET specific surface area 70 m ² / g Number average particle size 30 nm 10 parts of hexamethyldisilazane in the gas phase with 100 parts of silica fine powder Hydrophobized.

(3) 0.4 parts of hydrophobic titanium oxide fine powder: BET specific surface area 100 m ² / g Number average particle diameter 45 nm Hydrophobic with 10 parts of isobutyltrimethoxysilane in an aqueous medium with respect to 100 parts of titanium oxide fine powder Which has been converted.

Production Example 2 of Toner Magenta polymer particles (toner particles) were obtained in the same manner as in Production Example 1 of the toner except that a quinacridone pigment was used instead of the copper phthalocyanine pigment. Three types of external additives were externally added to the obtained polymer particles in the same manner as in Example 1 to obtain a negatively charged magenta toner No. 1 7 was prepared. The magenta toner had a weight average particle size of 7.3 μm and SF-1 was 108.

Toner Production Example 3 Instead of copper phthalocyanine pigment, C.I. I. Pigment Yellow 180 and Solvent Yellow 93 were used, and yellow polymer particles (toner particles) were obtained in the same manner as in Production Example 1 of the toner except that Pigment Yellow 180 and Solvent Yellow 93 were used. Three kinds of external additives were externally added to the obtained polymer particles in the same manner as in Example 1 to obtain a negatively chargeable yellow toner No. 1 8 was prepared. The yellow toner had a weight average particle diameter of 7.2 μm, and SF-1 was 109.

Toner Production Example 4 Black polymer particles (toner particles) were obtained in the same manner as in Toner Production Example 1 except that carbon black was used instead of the copper phthalocyanine pigment. Three kinds of external additives were externally added to the obtained polymer particles in the same manner as in Example 1 to obtain a black toner No. 9 was prepared. The black toner had a weight average particle size of 7.4 μm and SF-1 of 108.

[Example 1] 92 parts of magnetic carrier II and cyan toner No. 18 parts were mixed with a V-type mixer so that the toner concentration became 8%, to obtain a two-component developer 1.

Using this two-component developer 1, a commercially available digital copying machine GP55 (manufactured by Canon) was modified as an image forming apparatus so that the developing apparatus shown in FIG. 1 could be inserted, and the developing bias shown in FIG. 2 was used. The surface layer of both the fixing device and the heating roller and the pressure roller was PFA 1.2 μm.
Changed to a coated roller and modified to remove the oil application mechanism, using ferrite particles as a charging member,
Using original manuscript with 25% image area, 23 ℃ / 6
0% (N / N), 23 ° C / 5% (N / L), 32.5 ° C
In each environment of / 90% (H / H), a paper passing test of 10,000 sheets was performed, and the evaluation was performed based on the following evaluation method. The results are shown in Table 1. As can be seen from Table 1, good results were obtained.

(1) Image Density: The image density was measured using a Macbeth Densitometer RD918 type (Macbeth Densitometer) manufactured by Macbeth and fitted with an SPI filter.
et RD918manufactured by
Macbeth Co. 2) on plain paper using
5 solid patches of 0φ (original C original density 1.5)
The image was formed at several places and measured as an average image density.

(2) Carrier adhesion: A solid white image was formed, and a portion of the photosensitive drum between the developing section and the cleaner section was sampled by adhering a transparent adhesive tape, and sampled at 5 cm.
The number of magnetic carrier particles adhering on the photosensitive drum in a size of 5 cm is counted, and the number of adhering carrier particles per 1 cm ² is calculated. ◎: less than 5 pieces / cm ² ：: less than 5 pieces / cm ² Δ: less than 10 pieces / cm ² ×: more than 20 pieces / cm ²

(3) Fog The average reflectance Dr (%) of plain paper before image formation was measured using a reflectometer (“REFLECTOME” manufactured by Tokyo Denshoku Co., Ltd.).
TER MODEL TC-6DS "). On the other hand, a solid white image was formed on plain paper, and the reflectance Ds (%) of the solid white image was measured. Fog (%)
Is calculated from the following equation: Fog (%) = Dr (%)-Ds (%) ◎: less than 0.4% ○: 0.4 to less than 0.8% △: 0.8 to less than 1.2% ×: 1.2% or more

(4) Solid Uniformity The difference between the maximum and minimum patch densities at the five locations used in (1) was determined.

Example 2 The same procedure as in Example 1 was carried out except that the magnetic carrier I was used. As shown in Table 1, although fog suppression after 10,000 sheets was slightly deteriorated, good results were obtained. The result was obtained. This is presumably because, since cleaning was not performed before the coupling agent treatment, impurities presumed to be impurities could not be completely removed, and toner spent slightly increased on the surface of the carrier after durability.

Example 3 Example 1 was repeated except that the magnetic carrier III was used.
Good results were obtained as shown in Table 1, although fog suppression and solid uniformity after 10,000 copies were slightly deteriorated. This is presumably because the number of carbon atoms in the alkyl group of the coupling agent was large, resulting in a slightly non-uniform treatment, and the dispersion of the magnetic material was deteriorated, resulting in non-uniform charging of the toner. .

Example 4 The procedure of Example 1 was repeated, except that the magnetic carrier IV was used.
Good results were obtained although the image density after 10,000 copies slightly decreased and fog suppression also worsened. This is because the functional group of the treating agent of the magnetic substance is an alkyl group, and the reaction with the amino group of the coupling agent that has treated the composite particles is not performed, so that the adhesiveness of the coating resin of the composite particles is reduced. It is presumed that it decreased slightly.

[Comparative Example 1] The same procedure as in Example 1 was carried out except that the magnetic carrier V was used. As a result, the image density was low, and both fog suppression and solid uniformity were deteriorated.
This is presumed to be due to the fact that the dispersion in the magnetic carrier became non-uniform because the coupling agent was performed in the gas phase.

Example 5 The same procedure as in Example 1 was carried out except that the magnetic carrier VI was used. As a result, good results were obtained although fog suppression and solid uniformity were slightly deteriorated. This is presumed to be due to the fact that the treatment of the magnetic material was performed once after drying, so that the magnetic material was slightly agglomerated and the dispersibility was insufficient.

Comparative Example 2 The procedure of Example 1 was repeated, except that the magnetic carrier VII was used.
The evaluation was stopped because the image density was low and carrier adhesion and fog suppression were poor. This is because dispersion of the iron oxide was very unstable because it did not lipophilicize the iron oxide.
It is presumed that iron oxide was exposed on the surface of the magnetic carrier, causing a development bias leak.

Example 6 The same procedure as in Example 1 was carried out except that the magnetic carrier core (A) was used. As a result, although fog suppression was deteriorated, the material was practically usable. This is presumably because charge control for the toner was not sufficiently performed due to the use of the carrier core.

Example 7 The same procedure as in Example 1 was carried out except that the magnetic carrier VIII was used, but good results were obtained although the carrier adhesion was slightly deteriorated.

Example 8 Toner No. 1 to No. 4, a developer was prepared in the same manner as in Example 1, and an image was formed in the order of yellow, magenta, cyan, and black using the image forming apparatus shown in FIG. As a result of evaluation, good results were obtained as in Example 1.

[0227]

[Table 1]

[0228]

According to the present invention, a high-density, high-definition color image can be obtained over a long period of time, the toner has excellent charge-imparting ability, and is less likely to cause spent on the toner. A component developer can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic view illustrating a preferred example of an image forming method of the present invention.

FIG. 2 is a diagram showing an alternating electric field used in Example 1.

FIG. 3 is a schematic explanatory view showing an example of a full-color image forming method.

FIG. 4 is a schematic diagram of a cell used for measuring a volume resistance value.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 electrostatic image carrier (photosensitive drum) 4 developing device 11 developer carrier (developing sleeve) 12 magnet roller 13, 14 developer transport screw 15 regulating blade 17 partition 18 replenishing toner 19 developer 19 a toner 19 b carrier 20 replenishing Port 21 Magnet roller 22 Transport sleeve 23 Magnetic particles 24 Laser beam 25 Transfer material (recording material) 26 Bias applying means 27 Transfer blade 28 Toner density detection sensor 61a Photosensitive drum 62a Primary charger 63a Developing device 64a Transfer blade 65a Replenishing toner 67a Laser light 68 Transfer material carrier 69 Separation charger 70 Fixer 71 Fixing roller 72 Pressure roller 73 Web 75, 76 Heating means 79 Transfer belt cleaning device 80 Driving roller 81 Belt driven roller 82 Bell G Static eliminator 83 Registration roller 85 Toner concentration detection sensor 121 Lower electrode 122 Upper electrode 123 Insulator 124 Ammeter 125 Voltmeter 126 Power supply 127 Sample 128 Guide ring

Continuing on the front page (72) Ryoichi Fujita, Incorporated Canon Inc. 3- 30-2 Shimomaruko, Ota-ku, Tokyo (72) Inventor Naotaka Incorporated Canon Inc. 3- 30-2, Shimomaruko, Ota-ku, Tokyo (72) Inventor Kenichi Nakayama 3-30-2 Shimomaruko, Ota-ku, Tokyo F-term in Canon Inc. (reference) 2H005 AB06 BA03 BA05 BA11 BA15 CA26 CA28 CB03 EA05 FA02

Claims (20)

[Claims] 1. A magnetic fine particle-dispersed resin carrier formed of composite particles having at least magnetic fine particles and a binder resin, wherein the magnetic fine particles are treated with an oleophilic treatment agent in an aqueous medium. A magnetic fine particle-dispersed resin carrier, characterized in that: 2. The magnetic fine particle-dispersed resin carrier according to claim 1, wherein the lipophilic treatment agent is a silane coupling agent. 3. The resin carrier according to claim 1, wherein the magnetic fine particles are iron oxide. 4. The magnetic fine particle-dispersed resin carrier according to claim 1, wherein the carrier contains magnetic fine particles and a nonmagnetic inorganic compound. 5. The method according to claim 1, wherein the silane coupling agent has one or more functional groups selected from an epoxy group, an amino group and a mercapto group.
5. The magnetic fine particle-dispersed resin carrier according to any one of items 1 to 4. 6. The magnetic fine particle-dispersed resin carrier according to claim 1, wherein the composite particles are obtained by a polymerization method. 7. The composite particles according to claim 1, wherein the surface of the composite particles is further treated with a coupling agent.
The magnetic fine particle-dispersed resin carrier according to any one of the above. 8. The composite particles according to claim 1, wherein the surface of the composite particles is further treated with a silane coupling agent.
7. The magnetic fine particle-dispersed resin carrier according to any one of items 1 to 6. 9. The magnetic fine particle-dispersed resin carrier according to claim 1, wherein the surface of the composite particles is further treated with a silane coupling agent having an amino group. 10. A two-component developer having at least a toner and a magnetic carrier, wherein the magnetic carrier is a magnetic fine particle-dispersed resin carrier formed of composite particles having at least magnetic fine particles and a binder resin, A two-component developer, wherein the magnetic fine particles are treated with a lipophilic treatment agent in an aqueous medium. 11. The two-component developer according to claim 10, wherein the lipophilic treatment agent is a silane coupling agent. 12. The two-component developer according to claim 10, wherein the magnetic fine particles are iron oxide. 13. The two-component developer according to claim 10, wherein the carrier contains magnetic fine particles and a non-magnetic inorganic compound. 14. The method according to claim 1, wherein the silane coupling agent has one or more functional groups selected from an epoxy group, an amino group and a mercapto group.
14. The two-component developer according to any one of 0 to 13. 15. The two-component developer according to claim 10, wherein the composite particles are obtained by a polymerization method. 16. The two-component developer according to claim 10, wherein the surface of the composite particles is further treated with a coupling agent. 17. The two-component developer according to claim 10, wherein the surface of the composite particles is further treated with a silane coupling agent. 18. The two-component developer according to claim 10, wherein the surface of the composite particles is further treated with a silane coupling agent having an amino group. 19. The toner according to claim 1, wherein the toner has a weight average particle diameter of 3 to 10 μm.
The two-component developer according to any one of claims 10 to 18, wherein m is m. 20. The two-component developer according to claim 10, wherein said toner is produced by a polymerization method.