JP2002328493A - Magnetic particle-distributed resin carrier, two- component developer, and developer for replenishment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a carrier and a two-component developer which have high flow properties, do not exhibit image degradation after outputting a large number of sheets and have excellent durability. SOLUTION: A magnetic particle-distributed resin carrier formed of composite particles containing at least magnetic particles and a binder resin has A/B<=1.5, wherein A stands for the fluidity after magnetization and B stands for the fluidity after demagnetization.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art As an electrophotographic method, US Pat.
Various methods are described in JP-B-97,691, JP-B-42-23910 and JP-B-43-24748. 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. Generally, among the methods of developing an electrostatic image using toner, a developing method using a two-component developer in which toner is mixed with a carrier is suitably used for a full-color copying machine or a printer that requires high image quality. I have.

In this developing method, the carrier imparts an appropriate amount of positive or negative charge to the toner by frictional charging, and carries the toner on its surface by the electrostatic attraction of the frictional 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 electrostatic image is developed with toner 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 deterioration of the developer and the accompanying image deterioration of the developed image occur.

In general, when the true specific gravity of the carrier is increased, the developer is required to have a predetermined layer thickness on the developing sleeve by the developer layer thickness regulating member or to agitate the developer in a developing device. Therefore, the load on the developer increases. Therefore, when a developer containing a carrier having a large true specific gravity is used for a long time, (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. Further, in this case, (d) the fine line reproducibility of the developed image tends to be neglected.

Therefore, in a carrier in which the above (a) to (d) 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 preferred to improve the impact resistance and spent resistance of the carrier to prevent the above (a) to (d) and extend the life of the developer.

On the other hand, when the particle size of the carrier is reduced,
(E) Carriers tend to adhere to the electrostatic image carrier.
Further, when the particle diameter of the carrier is reduced while the toner particle diameter is constant, (f) the distribution of the charge amount of the toner is widened, and particularly, the toner charged up during development in a low humidity environment flies to the non-image area. (Hereinafter referred to as “fog”) is likely to occur.

As a carrier for solving the above-mentioned problems (a) to (f), a magnetic fine particle-dispersed resin carrier has been proposed. 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. Further, since the particle size can be controlled in a wide range, it is suitable for a high-speed copying machine, a high-speed laser beam printer, or the like in which the rotation speed of the developing sleeve or the magnet in the sleeve is large.

A magnetic fine particle-dispersed resin carrier has been proposed in JP-A-54-66134 and JP-A-61-9659. However, if the magnetic particle carrier does not contain a large amount of a magnetic substance,
(G) The saturation magnetization is small with respect to the particle diameter, and the carrier easily adheres to the electrostatic image carrier at the time of development, and a mechanism for replenishing the developer or collecting the adhered carrier is provided in the image forming apparatus. You may need to.

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, the magnetic substance is easily dropped from the carrier, and as a result, the developer is easily deteriorated.

Further, when the magnetic fine particle-dispersed resin carrier contains a large amount of magnetite, the specific resistance of the carrier decreases due to an increase in the amount of the magnetic material having a low specific resistance. ) Image failure due to leakage of bias voltage applied during development is likely to occur, and if a large amount of magnetite is contained, residual magnetization of the carrier will increase, resulting in poor transport of the developer and poor mixing with the toner. Become.

On the other hand, JP-A-58-21750 discloses that
A technique of coating a carrier core with a resin has been proposed.
The carrier coated with the resin can improve spent resistance, impact resistance, and pressure resistance against applied voltage. 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 for measurement, an image defect is likely to occur due to leakage of the developing bias voltage, or in a low humidity environment. In some cases, the charge-up phenomenon is easily caused.

On the other hand, in the mainstream two-component developing method, toner is consumed by development, and the carrier is retained in the developing machine without being consumed. Therefore, carrier contamination occurs due to transfer of the toner component to the carrier, or the carrier itself is contaminated. Under the stress in the developing machine, the resin coating layer is peeled off, which affects the developer characteristics such as charging property, and fluctuates the image density and fogs.

In order to solve this problem, for example,
Japanese Patent Publication No. 2-15991 discloses a developing device in which a carrier is added together with toner consumed during development, and the carrier in the developing device is replaced little by little, thereby suppressing a change in charge amount and stabilizing an image density. A so-called trickle developing device is disclosed. However, since the carrier used is an iron powder carrier having a large saturation magnetization, stress on the carrier in the developing machine is large, and the carrier is likely to deteriorate during repeated copying operations. Otherwise, image degradation tends to be quick and not satisfactory.

Japanese Unexamined Patent Publication (Kokai) No. 3-145678 discloses that a carrier having a higher resistance value than a carrier housed in a developing machine in advance contains a toner so as to maintain chargeability and suppress deterioration in image quality. It is disclosed. Further, Japanese Patent Application Laid-Open No. H11-223960 discloses that a carrier that imparts a higher charge amount to a toner contains the toner, thereby maintaining the chargeability and suppressing a deterioration in image quality. However, in these methods, the amount of carrier to be replaced is different due to a difference in toner consumption.
The resistance or charge amount of the developer in the developing machine changes, and the image density tends to fluctuate, which is not satisfactory.

Further, Japanese Patent Application Laid-Open No. Hei 8-234550 discloses a method of sequentially replenishing each toner by using a plurality of kinds of replenishment toners containing carriers having different physical properties from the carrier housed in the developing machine in advance. ing. However, in actuality, replenishment of a supply toner containing a plurality of carriers having different physical properties in a single toner supply container sequentially so as not to mix with each other in the developing machine requires the specific gravities of the carrier and the toner to be extremely different. In addition, it is very difficult, and the carrier tends to deteriorate due to the large amount of toner in the carrier, and a stable image cannot be obtained for a long period of time.

As described above, the strict quality requirements required today, for example, fine lines, small letters, photographs, color originals, etc.
There is a long-awaited demand for magnetic carriers that can meet various targets, and that further satisfy high image quality, high quality, high speed, and high durability.

[0025]

SUMMARY OF THE INVENTION An object of the present invention is to provide a carrier and a two-component developer (including a replenishing developer) which solve the above-mentioned problems.

An object of the present invention is to provide a carrier and a two-component developer which are excellent in durability without image deterioration even when a large number of images are formed because the carrier has low residual magnetization and high fluidity. Is to do.

It is an object of the present invention to provide a carrier and a carrier capable of forming a high-quality toner image by preventing the carrier from adhering to the electrostatic image carrier and preventing or suppressing fog since the carrier has a high saturation magnetization. An object of the present invention is to provide a component developer.

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

A further object of the present invention is to provide a replenishing developer capable of obtaining a stable image throughout the life of the main body and a developing method using the same.

[0030]

The present invention relates to a magnetic fine particle-dispersed resin carrier formed of composite particles having at least magnetic fine particles and a binder resin. A / B ≦ where B is the fluidity of
The present invention relates to a magnetic fine particle-dispersed resin carrier having a particle diameter of 1.5.

The present invention also provides a two-component developer having at least a toner having toner particles and an external additive and a magnetic fine particle-dispersed carrier, wherein the toner has a weight average particle size of 3.0 to 3.0. A toner having a particle size of 9.0 μm and a wax content of 40% by mass or less, wherein the carrier is formed of composite particles having at least magnetic fine particles and a binder resin. The present invention relates to a two-component developer, which is a magnetic fine particle-dispersed resin carrier satisfying A / B ≦ 1.5 when the fluidity is B.

Further, the present invention relates to a replenishing developer for use in a developing method for performing development while replenishing a replenishing developer, wherein the toner is contained in an amount of 2 to 50 parts by mass with respect to 1 part by mass of a carrier. A toner having a weight average particle size of 3.0 to 9.0 μm and a wax content of 40% by mass or less, wherein the carrier has at least magnetic fine particles and a binder resin. A magnetic fine particle-dispersed resin carrier which is formed of body particles and satisfies A / B ≦ 1.5 when the fluidity after magnetization is A and the fluidity after demagnetization is B. The present invention relates to a replenishing developer characterized by the following.

[0033]

BEST MODE FOR CARRYING OUT THE INVENTION The carrier used in the present invention is a magnetic fine particle-dispersed resin carrier (hereinafter sometimes abbreviated as "carrier") formed of composite particles having at least magnetic fine particles and a binder resin.

The present inventors have conducted various studies and studies to improve the above-mentioned problems. As a result, when the fluidity after magnetization of the carrier is A and the fluidity after demagnetization is B, A / B ≦ 1. .5, preferably A / B ≦ 1.2, more preferably A / B ≦
It has been found that satisfying 1.1 is effective in improving various characteristics, and the present invention has been achieved.

If the ratio A / B is larger than 1.5, the two-component developer causes poor fluidity due to magnetic aggregation of the carrier on the developer tank and the developer carrier, and the developer is not uniformly placed on the sleeve surface. Cause poor image quality and / or
The toner charge distribution is widened, fogging and toner scattering occur, and it is not possible to form a high-quality toner image for a long period of time.

The flow rate A after magnetization of the carrier and the flow rate B after demagnetization of the carrier are values obtained by the following measuring methods.

(Method of Measuring Flow Rate of Carrier) The flow rate of the carrier was indicated by a value measured with a Casa specific gravity meter manufactured by Tsutsui Physical and Chemical Instruments Co., Ltd.

More specifically, 200 g of the magnetized or demagnetized carrier was placed in a thermostat at 23 ° C. and 60% in an environment of 60 ° C. and stored at 23 ° C. and 60% for 24 hours to adjust the humidity. The conditioned carrier is divided into three parts, 50 ± 0.1 g of the measurement carrier is weighed out from each part, and the orifice (outlet diameter 4 mm) at the bottom of the funnel is covered and transferred to the funnel. At this time, make sure that the carrier is sufficiently packed in the orifice. For the measurement, a stopwatch is operated at the moment when the orifice is opened, and stopped at the moment when the orifice is finally released, and the time is read in units of 0.2 seconds. The measurement was performed once for each of the three divided measurement carriers, and the average time of the three measurements was taken as the fluidity.

When the carrier is already a two-component developer, the carrier is separated by the following method, demagnetized and magnetized, and the fluidity is measured by the above method to calculate A / B. did.

The two-component developer was put into water to which a surfactant was added, and the carrier was indirectly attracted from the outside of the container using a magnet, and the toner was separated and removed by removing water. Then, after washing with water several times, it was dried.

The fluidity A of the carrier after magnetization is 1
The carrier magnetized under a magnetic field of 000 × (10 ³ / 4π) · A / m (1000 Oe) was set to a value obtained by the above measurement method. The demagnetization was performed by packing in a 15 ml sample bottle so that the magnetized carrier did not move, and using a demagnetizer (SR-L2520D, manufactured by Nippon Electromagnetic Instruments, Inc.) to demagnetize AC.

The magnetic fine particle-dispersed resin carrier of the present invention comprises composite particles in which specific magnetite particles are dispersed as magnetic fine particles.

In the magnetite particles of the present invention, by controlling the amounts of the magnesium component, silicon component, manganese component and phosphorus component contained therein, the residual magnetization can be reduced without lowering the electric resistance and saturation magnetization of the carrier. In addition, various characteristics of fluidity can be improved in a well-balanced manner.

It is preferable to contain at least one of a magnesium component, a silicon component, a manganese component, and a phosphorus component.
It is more preferable that the carrier has magnetite particles of 5.0% by mass.

A magnesium component in the magnetite particles,
When the total amount of the silicon component, manganese component, and phosphorus component is less than 0.03% by mass with respect to Fe in terms of each element, the residual magnetization of the carrier becomes large, and poor fluidity due to magnetic aggregation is likely to occur. When it is more than 5% by mass, although the effect of improving electric resistance, residual magnetization, and fluidity can be sufficiently obtained, environmental resistance, particularly hygroscopicity, is high, and filterability during production is poor. , Which is industrially undesirable.

The magnetite particles preferably contain a magnesium component, a silicon component, a manganese component, and a phosphorus component inside and on the surface of the particles.

The magnetite particles according to the present invention preferably have the above elements both inside and on the surface of the magnetite particles. Even if the above elements are present inside the magnetite particles, if they are not exposed on the surface, the electric resistance is low and the fluidity tends to be poor. In addition, when exposed only on the surface of the magnetite particles, the residual magnetization tends to be inferior.

As described above, in the magnetite particles according to the present invention, it is preferable that a predetermined amount of the above element be present both inside and on the surface of the magnetite particles.

Further, by containing at least two of magnesium component, silicon component, manganese component and phosphorus component, magnesium component, silicon component,
Compared to the case where only one of the manganese component and the phosphorus component is contained, it is preferable because various characteristics of remanent magnetization and fluidity can be improved in a well-balanced manner without lowering the electric resistance and the saturation magnetic flux density. . In particular, when at least two of the magnesium component, the silicon component, the manganese component, and the phosphorus component are contained, it is preferable to include at least a magnesium component in terms of improving various properties in a well-balanced manner.

The ratio of the magnesium element to the (total amount of the silicon element, the manganese element and the phosphorus element) is preferably 1: 9 to 9: 1 in terms of each element.

Even when the ratio of the magnesium element to the (total amount of the silicon element, the manganese element and the phosphorus element) is out of the above range, it is possible to certainly improve various properties, but it is possible to synergistically. In order to improve various characteristics in a well-balanced manner, the ratio is preferably within the above range.

In the present invention, more preferably, a magnesium component, a silicon component, a manganese component and a phosphorus component are contained before the magnetite crystal is formed. Magnesium component, silicon component, manganese component,
The magnetite particles to which no phosphorus component is added have a residual magnetization of 7.5.
Compared to Am was more than ² / kg, magnetite particles obtained in this way, the residual magnetization is 10
It is obtained as low as about 50%. Although the reason is not yet clear, the present inventors have found that the magnesium component, the silicon component, the manganese component, and the phosphorus component suppress the agglomeration of the growing particles during the generation of the magnetite particles, and that the crystal growth of the magnetite particles occurs. I think it has some effect.

Further, the magnetite particles of the present invention
Zinc, copper, nickel, cobalt, aluminum, tin,
At least one or more metal elements selected from titanium and zirconium are used in a total amount of 0.01 to
3.0% by mass, and the total amount of the metal component, the magnesium component, the silicon component, the manganese component, and the surface exposure of the phosphorus component is 0.01 to 1.5% by mass in terms of each element.
(Preferably 0.01 to 0.5% by mass), and more preferably these metal elements are contained more in the outer shell than in the inner shell of the magnetic fine particles. In the outer shell and inner shell of the magnetic fine particles, zinc,
By increasing the concentration of each component of copper, nickel, cobalt, aluminum, tin, titanium and zirconium in the outer shell and surface, synergistic remanence and fluidity without lowering electric resistance and saturation magnetization Characteristics can be improved in a well-balanced manner. In particular, by adding these metal elements, the fluidity of the magnetite is remarkably improved, the magnetite is easily dispersed uniformly in the composite particles, and the variation in electric resistance, saturation magnetization, remanence magnetization, etc. between the carrier particles. Is eliminated, the carrier is prevented from adhering to the electrostatic image carrier, and the charge distribution of the toner is sharpened, so that a high image density and high definition image can be obtained for a long period of time. The addition of these metal components is not essential in the present invention.

Even if the above metal component, magnesium component, silicon component, manganese component, and phosphorus component are present in the inner shell of the magnetite particles but are not exposed to the outer shell and the surface, that is, the surface exposed component is 0%. If it is less than 0.01% by mass, the effect of improving electric resistance, residual magnetization and fluidity tends to be small. In addition, the amount of the surface exposed component is 1.5
If the content is more than 10% by mass, good properties can be obtained, but the surface-exposed components cannot be supported on the magnetite surface, and each compound is likely to be unevenly distributed or separated, which is not preferable.

Further, the abundance of the surface exposure component element mentioned here is a value obtained by the following analysis method. That is, 0.900 g of a sample is weighed, and 25 ml of a 1 mol / liter-NaOH solution is added. While stirring the liquid 4
Heat to 5 ° C. to dissolve the metal component on the particle surface. After filtering the undissolved matter, the eluate was quantified to 125 ml with pure water,
Plasma emission spectrometry (ICP) for each element contained in the eluate
Quantify with The abundance is determined by the following equation.

Surface exposed magnesium component, silicon component,
Amount of each element of manganese component, phosphorus component and metal component =
｛[Each element (g / l) contained in the eluate × 125 ÷ 10
00] /0.900 (g)｝ × 100 The total amount of magnesium component, silicon component, manganese component, phosphorus component and metal component in the whole magnetite particles was determined by dissolving a sample in a salt-hydrofluoric acid solution and emitting plasma. Quantify by analysis (ICP).

Examples of the method for increasing the concentration of the metal component in the outer shell portion (surface portion) include a method of continuously changing the concentration, a method of adjusting pH, a method of adding stepwise, and the like. There are known methods, but the method is not limited at all.

Next, the method for producing magnetite particles of the present invention will be described.

First, a magnesium component, a silicon component, a manganese component, and a phosphorus component to be contained in magnetite are added to a solution whose main component is a ferrous salt. As the ferrous salt used here, ferrous sulfate is preferable, and as the magnesium component, the silicon component, the manganese component, and the phosphorus component, the following are used. As the magnesium component, water-soluble magnesium compounds such as magnesium sulfate, magnesium chloride, and magnesium nitrate are preferable. As the silicon component, a solution containing a silicon colloid prepared from water glass, sodium silicate, potassium silicate, or the like is preferable. As the manganese component, water-soluble manganese compounds such as manganese sulfate, manganese chloride, and manganese nitrate are preferable. As the phosphorus component, sodium hexametaphosphate, phosphates such as ammonium monophosphate,
Phosphoric acids such as orthophosphoric acid and phosphorous acid are preferred.

An aqueous solution whose main component is a ferrous salt is mixed with a magnesium component, a silicon component, a manganese component, a phosphorus component, and 1.0 to 1.1 equivalents of alkali relative to iron. As the ferrous salt used here, ferrous sulfate is preferable. As the silicon component, a solution containing a hydrous silicate colloid prepared from a silicate compound is preferable.
For example, by using sodium silicate or the like, a silicate compound (including a hydrous compound) can be generated in the produced particles. Similarly, the magnesium and manganese components can generate a magnesium compound (including a hydrous compound) in the formed particles by using, for example, a sulfate.
Similarly, for the phosphorus component, a phosphorus compound (including a water-containing compound) can be generated in the formed particles by using, for example, sodium hexametaphosphate.

An oxygen-containing gas, desirably air is blown into the mixture, and the mixture is heated at 60 to 100 ° C., preferably 80 to 90 ° C.
At 0 ° C., an oxidation reaction is performed to generate seed crystals. The control of the oxidation reaction amount is performed by analyzing unreacted ferrous hydroxide during the reaction and adjusting the amount of oxygen-containing gas. In this oxidation reaction, it is important to maintain the pH at 7 to 10, preferably 7 to 9.

In the course of this oxidation reaction, when the amount of seed crystals formed becomes 1 to 30%, preferably 5 to 25% of the total oxidation amount, 0.9 to 1.2 equivalents to the initial alkali. Insufficient iron, preferably 1.05 to 1.15 equivalents, is added. The iron used here is preferably a ferrous salt solution such as ferrous sulfate.

Further, under the same conditions as above, pH 6 to 10,
Preferably, the oxidation reaction is continued while maintaining the value at 6 to 9, to generate particles, and the particles are washed, filtered, dried, and pulverized by a conventional method to obtain magnetite particles.

In the present invention, as described above, the pH during the oxidation reaction
Is preferably adjusted to 6 to 10. The reason is that if the pH during the oxidation reaction is higher than the neutral range, the magnesium component, silicon component, manganese component and phosphorus component are more likely to be taken into the center of the magnetite particles, and conversely, if the pH is lowered the surface is less likely to be worked inside This is because it is deposited on the surface. By adjusting the pH within this range, the presence states of the magnesium component, the silicon component, the manganese component, and the phosphorus component can be controlled.

As a result of the observation of the shape of the particles during the oxidation reaction by the present inventors, the seed crystals formed in the first reaction are irregular, but particles having a narrow particle size distribution are observed. Then, in the latter half neutral range, weak alkaline range (pH 6-1
The reaction in step (0) gradually changes into a pseudo spherical shape.

When at least one metal element selected from the group consisting of zinc, copper, nickel, cobalt, aluminum, tin, titanium and zirconium is added to magnetite, the pH is adjusted to 6 to 10 under the same conditions as described above. The oxidation reaction is continued while maintaining preferably at 6 to 9, and zinc, copper, nickel, cobalt, aluminum and tin are generated when particles are generated, that is, between the time when the insufficient iron is added and the time when the reaction is completed. , An aqueous solution containing at least one metal element selected from titanium and zirconium is added to the reaction system. At this time, the added metal element may be an aqueous solution or a hydroxide. When two or more components are added, two components may be added separately or a mixture of two components may be added.

The form of the magnetite particles may be any of cubic, polyhedral, spherical, needle-like, plate-like, etc., but the magnetite particles are uniformly dispersed in the composite particles. Above, spherical ones are preferably used. The average particle diameter may be a particle smaller than the average particle diameter of the composite particles, and the number average particle diameter is 0.02 to 0.02.
5.0 μm, particularly preferably 0.02 to 2.0 μm.

The magnetic fine particles of the present invention are preferably treated with a lipophilic treatment agent.

Examples of the lipophilic treatment agent include one or more functional groups selected from an epoxy group, an amino group, a mercapto group, an organic acid group, an ester group, a ketone group, a halogenated alkyl group and an aldehyde group. Or a mixture thereof, which can achieve the object of the present invention. Among these, a coupling agent containing a functional group is preferable, more preferably a silane coupling agent, a titanium coupling agent or an aluminum coupling agent, and particularly preferably a silane coupling agent. Further, as a preferable functional group, an epoxy group, an amino group and a mercapto group are preferable because the magnetic fine particles are easily dispersed uniformly in the carrier, and furthermore, the epoxy group is hardly affected by temperature and humidity, and the carrier is charged. It is preferable in that the imparting ability is stabilized.

The organic compound having an epoxy group includes
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. No.

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

Examples of silane coupling agents having an amino group include γ-aminopropyltrimethoxysilane, N
-Β- (aminoethyl) -γ-aminopropyltrimethoxysilane, N-β- (aminoethyl) -γ-aminopropylmethyldimethoxysilane, and N-phenyl-γ-aminopropyltrimethoxysilane.

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, and styrene-acrylic acid.

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 0.1 to 5.0% by mass based on the magnetic fine particles.

When the amount is less than 0.1% by mass, it becomes difficult to adhere the resin coating to the surface of the composite particles, and the lipophilic treatment is insufficient, so that the composite having a high content of magnetic fine particles is high. Body particles cannot be obtained.

When the content exceeds 5.0% by mass, 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.

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. And urethane resins. 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 magnetic fine particles constituting the composite particles is, on a mass basis, binder resin: magnetic fine particles = 1: 99 to 1:50.
It is preferable that

The carrier according to the present invention may be coated with a coupling agent or a resin, if necessary.

As the resin to be coated, any known resin can be used, and examples thereof include an epoxy resin, a silicone resin, a polyester resin, a fluorine resin, a styrene resin, an acrylic resin, and a phenol resin.
A polymer obtained by polymerizing from a monomer may be used.
A silicone resin is preferable in consideration of durability and stain resistance. The treatment amount of the coating resin is preferably 0.01 to 3.0 parts by mass, more preferably 0.1 to 2.0 parts by mass, based on 100 parts by mass of the carrier core, to obtain the above characteristics. Preferred for

In particular, a phenol resin is used as a binder resin for the composite particles, an epoxy group-containing silane coupling agent is used as a lipophilic treatment agent for the magnetic fine particles, and a silicone resin is used as a coating resin for the composite particles (carrier core). It is preferable to incorporate an amino group-containing silane coupling agent into the silicone resin, or to use an amino group-containing silane coupling agent as a pretreatment before coating the composite particles with the resin. With such a configuration, the silane coupling agent containing an amino group is hydrolyzed by water appropriately adsorbed in the phenol resin, and self-condensed while being hydrogen-bonded to the hydroxyl group of the phenol resin, Alternatively, at the same time as forming a strong coating by condensing with the remaining silanol groups in the silicone resin, the amino group reacts with the epoxy group of the lipophilic treatment agent of the magnetic fine particles to improve the adhesion of the silicone resin, Missing or the like is suppressed.

The carrier of the present invention preferably has a true specific gravity of 2.5 to 4.5 (preferably 3.0 to 4.3). When the true specific gravity is within this range, the magnetic resin carrier and the toner This is preferable since the load on the toner is small in the stirring and mixing with the toner, the contamination of the carrier surface with the toner is suppressed, and the adhesion of the carrier to the non-image portion on the electrostatic image carrier is suppressed.

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 15 to 80 Am ² /
kg (emu / g) (preferably 20 to 70 Am ²
/ Kg) and the residual magnetization (σr) is 7.5 Am ² / k
g (emu / g) or less (preferably 2.9 to 6.9 A)
m ² / kg, and further less than 4.5 Am ² / kg)
When the magnetic properties of the carrier are in this range, the carrier adheres to the electrostatic image carrier under the magnetic field of a magnetic field generating means (for example, a fixed magnet) included in the developer carrier (developing sleeve). This is preferable because the compression force of the two-component developer to the toner in the magnetic brush is reduced, and carrier contamination by external additives and toner particles is suppressed.

The residual magnetization of the carrier is 7.5 Am ² / kg
If it is larger, the two-component developer causes poor fluidity due to magnetic aggregation.

That is, as described above, the magnesium component, the silicon component, and the manganese component are added to the granular magnetite particles used in the magnetic fine particle-dispersed resin carrier.
By containing a phosphorus component and a metal component, the residual magnetization is reduced to 7.5 Am ² / kg or less within a range that does not impair the magnetic characteristics to be retained as a carrier, for example, the saturation magnetization. The purpose of the adjustment is as follows.

The purpose of reducing the residual magnetization is to improve the fluidity of the two-component developer. A two-component developer using a carrier having magnetite particle powder has a problem of poor fluidity due to magnetic aggregation in the developer. We thought that these problems could be improved by weakening the remanent magnetization, in other words, the magnetic cohesion. Further, it is considered that this also leads to an improvement in the releasability of unnecessary toner from the drum after the completion of electrostatic transfer in electrophotography.

The volume average particle diameter of the carrier of the present invention is as follows:
In particular, for high image quality and high quality, the average particle diameter is 10 to 10.
A range of 50 μm is preferable, and a volume average particle size of 1
4 to 45 μm is even more preferable in that, when original continuous printing with a high image ratio such as a photographic original and a large amount of toner consumption is performed, the mixing and transportability of the replenishment toner is excellent.

The residual magnetization (σ) of the carrier of the present invention is
r) and the volume average particle diameter (d) are 1.0 ≦ d / σr <3
0.0 (unit: μm · kg / Am ² ), preferably 1.
5 ≦ d / σr <20.0, more preferably 5.1 ≦ d /
σr ≦ 12.3. When d / σr is 30 or more,
The fluidity of the two-component developer is too high, so that the toner and the carrier are easily separated when left for a long period of time, and fog and scattering are liable to occur. If d / σr is less than 1.0, the fluidity of the two-component developer is deteriorated, and the ability of the carrier to impart charge to the toner is deteriorated.

The carrier of the present invention may be added to the composite particles in addition to the non-magnetic inorganic particles of the present invention in order to adjust the specific resistance and the magnetic properties so as to be suitable for a predetermined system. Compound particles may be blended. The magnetic fine particles and the nonmagnetic inorganic compound particles are in a total amount of 500 to 990% by mass, more preferably 700 to 990% by mass based on the binder resin.
The content of 990% by mass is preferable in relation to the adjustment of the true specific gravity of the carrier, the adjustment of the specific resistance value of the carrier, and the mechanical strength of the carrier core.

The magnetic fine particles preferably contain 50% by mass or more of the total amount of the magnetic fine particles and the non-magnetic inorganic compound particles.

Further, it is preferable that the nonmagnetic inorganic fine particles have a larger specific resistance value than magnetite. The number average particle diameter of the nonmagnetic inorganic compound fine particles is larger than the number average particle diameter of magnetite, thereby increasing the specific resistance of the carrier,
This is preferable for reducing the true specific gravity of the carrier.

The shape of the carrier is appropriately selected so as to be convenient for a predetermined system.

However, the sphericity of the carrier SF-1
Is 100 to 130 (more preferably 100 to 12
0) is preferred. When the carrier has a sphericity of more than 130, the fluidity as a developer becomes inferior. It becomes difficult to obtain an image.

The sphericity of the carrier was measured using a field emission scanning electron microscope S-manufactured by 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.

Sphericity SF-1 = [(MXLNG) ² /
(AREA)] × (π / 4) × 100 [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 method for producing the magnetic fine particle-dispersed resin carrier according to the present invention will be described.

The composite particles are prepared by dispersing magnetic fine particles (non-magnetic inorganic compound fine particles as necessary) in a monomer constituting a binder resin, adding an initiator or a catalyst, and dispersing in a water-based medium and polymerizing. , A so-called polymerization method, pulverizing a binder resin containing magnetic fine particles, a so-called
It can be produced by a kneading and pulverizing method. A polymerization method is preferred for easily controlling the particle size of the carrier and obtaining a sharp particle size distribution.

In the production of composite particles using a phenol resin as a binder resin, for example, phenols and aldehydes are dispersed in an aqueous medium with magnetic fine particles, and a basic catalyst is added. A method for causing the reaction is mentioned. A method of forming a so-called modified phenol resin, in which a natural resin such as rosin or a drying oil such as tung oil or linseed oil is mixed and reacted with phenols, may also be used.

It is preferable that the binder resin is a phenol resin, in particular, since it retains an appropriate amount of adsorbed water, promotes hydrolysis of the coupling agent, and can form 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.

The production of composite particles using a melamine resin as a binder resin is carried out, for example, by dispersing melamines and aldehydes, and lipophilic magnetic fine particles in an aqueous medium, and adding a weak acid catalyst. The reaction is performed under the following conditions.

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

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

In the case of coating the composite particles with a coupling agent, the composite particles may be immersed in a solution of the coupling agent in water or a solvent by a conventional method, followed by filtration and drying. A method of spraying and drying an aqueous solution or a solvent solution of the coupling agent while stirring the body particles 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.

When the surface of the composite particles is coated with a resin, the resin may be coated by a well-known method. For example, the composite particles may be coated with a stirrer such as a Henschel mixer or a high-speed mixer. Any of a method of mixing with a resin, a method of impregnating the composite particles into a solvent containing the resin, and a method of spraying the resin to the composite particles using a spray dryer may be used.

Next, the toner used in the two-component 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 9.0 μm, preferably 4.5 to 8.5 μm.

The weight average particle diameter (D4) of the toner is 9.0 μm.
When m exceeds m, the toner particles for developing the electrostatic image become large, so that it is difficult to perform development faithful to the electrostatic image, and when electrostatic transfer is performed, the toner is easily scattered. When the weight average particle diameter of the toner is less than 3.0 μm, the handling property as a powder is reduced.

For measuring the particle size of the toner, for example, a method using a Coulter counter can be mentioned.

As the binder resin used for the toner, the following 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-acrylate copolymer, styrene-methacrylate 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 coumarone 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, divinylbenzene, aromatic divinyl compounds such as 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. It is. These are used alone or as a mixture.

The amount of the crosslinking agent to be added is preferably 0.001 to 10 parts by mass based on 100 parts by mass of the polymerizable monomer used for producing the above-mentioned binder resin.

The toner may contain a charge control agent.

The following substances can be used to 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 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.

The following substances can be used to control the toner to be positively charged.

For example, amino compounds, quaternary ammonium compounds and organic dyes, especially basic dyes and salts thereof are known, such as benzyldimethyl-hexadecylammonium chloride, decyl-trimethylammonium chloride, nigrosine base, nigrosine hydrochloride, and the like.
And safranin γ and crystal violet. These dyes can also be used as a coloring agent.

These charge control agents can be used alone or in combination of two or more. The charge control agent is added in an amount of 0.0 to 100 parts by mass of the binder resin of the toner.
1 to 20 parts by mass, preferably 0.1 to 10 parts by mass, more preferably 0.2 to 4 parts by mass.

The toner may contain a magnetic substance. As the magnetic material, iron oxides such as magnetite, hematite, and ferrite; metals such as iron, cobalt, and nickel; or these metals and aluminum, cobalt, copper, lead,
Magnesium, tin, zinc, antimony, beryllium,
Alloys with metals such as bismuth, cadmium, calcium, manganese, selenium, titanium, tungsten, vanadium and mixtures thereof. These magnetic materials are
It may be a coloring agent.

As the colorant of the toner used in the present invention, carbon black, a magnetic substance, and a black-colored toner using the following yellow / magenta / cyan colorants 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, 162 and 163 may be used in combination.

Examples of the magenta colorant include condensed azo compounds, diketopyrrolopyrrole compounds, anthraquinones, quinacridone compounds, basic dye lake compounds, naphthol compounds, benzimidazolone compounds, thioindigo compounds and perylene compounds. 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 coloring agents 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 mass per 100 parts by mass of the binder resin.

Further, the toner particles according to the present invention contain wax, and 1 to 4 parts by mass with respect to 100 parts by mass of the binder resin.
0 parts by mass, preferably 2 to 30 parts by mass.

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

When a toner is produced by a polymerization method in which toner particles are directly obtained by polymerizing a mixture having a polymerizable monomer, a colorant and a wax, the amount of the wax to be added is determined by the amount of the polymerizable monomer or the polymerizable monomer. It is preferable to use 2 to 40 parts by mass, more preferably 5 to 30 parts by mass, and still more preferably 10 to 20 parts by mass, based on 100 parts by mass of the resin synthesized by polymerization of the polymerizable monomer.

Usually, since the wax has a lower polarity than the binder resin, a large amount of the wax is easily encapsulated in the toner particles by the polymerization method in which the polymerization method is carried out in an aqueous medium. Can be used. Therefore, when the toner is produced by the polymerization method, a better offset prevention effect can be obtained.

When the amount of the wax is less than the lower limit, the effect of preventing offset tends to decrease, and when the amount exceeds the upper limit, the anti-blocking effect is reduced and the anti-offset effect is liable to be adversely affected. In particular, when a toner is produced by a polymerization 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 known pulverization method and polymerization method.

In the method for producing a pulverized toner, a binder resin, a wax, a pigment as a colorant, a dye or a magnetic substance,
If necessary, a charge control agent and other additives are sufficiently mixed by a mixer such as a Henschel mixer or a ball mill; and the obtained mixture is melt-kneaded using a heat kneader such as a heating roll, a kneader or an extruder. A metal compound, a pigment, a dye, and a magnetic substance are dispersed or dissolved in a resin component being mutually compatible. The obtained kneaded product is cooled, 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
No. 3945, 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. 36-10231, Japanese Patent Application Laid-Open No. 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, It is possible to produce a toner using a hetero-aggregation method in which polar particles having opposite charges are added and associated.

Among them, a suspension polymerization method in which a monomer composition containing at least a polymerizable monomer, a colorant and a wax is directly polymerized to form toner particles is preferable.

A so-called seed polymerization method in which a monomer is further adsorbed onto 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 includes silica,
It is preferable that inorganic fine particles such as alumina and titanium oxide; and fine particles of organic fine particles such as polytetrafluoroethylene, polyvinylidene fluoride, polymethyl methacrylate, polystyrene and silicone are externally added. By externally adding the fine powder described above to the toner,
Fine powder exists between the toner and the carrier or between the toner particles, so that the fluidity and transferability of the developer are improved, and the life of the developer is also improved.

The fine powder has an average particle size of 3 to 100 n.
m is preferable. When the average particle size exceeds 100 nm, the effect of improving the fluidity is reduced, and the image quality may be deteriorated due to a defect at the time of development or transfer. If it is smaller than 3 nm, it is difficult to maintain fluidity during durability. 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 50 to 400 m ² / g. The addition amount of the fine powder is preferably 0.1 to 20 parts by mass with respect to 100 parts by mass of the toner particles.

In the case where the toner is a negatively chargeable toner,
It is preferable to use at least one type of silica that has been subjected to a hydrophobic treatment from the viewpoint of chargeability. That is, since silica has higher negative chargeability than a fluidizing agent such as alumina or titanium oxide, the adhesion to the toner base is high, and free external additives are 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, and the amount thereof is preferably 1 to 40 parts by mass, more preferably 2 to 35 parts by mass, per 100 parts by mass of silica. When the treatment amount is 1 to 40 parts by mass, the moisture resistance is improved and aggregates are hardly generated.

As another hydrophobizing agent, silicone oil can be mentioned.

For the purpose of imparting various toner characteristics, other additives can be added. From the viewpoint of durability when added to the toner particles, the additive preferably has a particle diameter of 1/5 or less of the volume average diameter of the toner particles. 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 abrasive include metal oxides such as strontium titanate, cerium oxide, aluminum oxide, magnesium oxide and chromium oxide; nitrides such as silicon nitride; silicon carbide carbide; and calcium sulfate, barium sulfate and Metal salts such as calcium carbonate are mentioned.

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

As the charge controlling particles, for example, 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 mass, more preferably 0.1 to 5 parts by mass, based on 100 parts by mass 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 to 15% by mass, preferably 4 to 13% by mass, as the toner concentration in the developer. Good results can be obtained. When the toner concentration is less than 2% by mass, the image density tends to be low. When the toner concentration is more than 15% by mass, fogging and scattering in the machine easily occur, and the useful life of the developer tends to decrease.

In a developing method in which development is performed while replenishing the replenishing developer, when the replenishing developer is prepared by mixing the toner and the carrier, the mixing ratio is set to 1 part by mass of the carrier in the developer. On the other hand, when the ratio of the toner is 2 to 50 parts by mass, good results can be obtained. When the amount of the toner is less than 2 parts by mass, the charge amount of the developer is apt to increase because the amount of the carrier is too large, and the image density changes. If the amount exceeds 50 parts by mass, the amount of toner becomes extremely large, the carrier is deteriorated, and the charge amount of the developer tends to be reduced.

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 it is less than 0.1%, it becomes difficult to properly charge the toner, and fog and toner scattering in a high humidity environment are 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,
This tends to cause a decrease in image density and fog.

The two-component developer of the present invention can be used in any developing method (regardless of full-color or monochrome), for example, a developer for high-speed systems, a developer for oilless fixing, and a developer for auto-refresh (trickle). It is applicable to a known developing method such as a developer (including replenishment).

Since the carrier of the present invention synergistically improves various properties of residual magnetization and fluidity without lowering electric resistance and saturation magnetization, it is suitable for a developer for auto refresh (trickle). Can be used. In other words, since the true specific gravity and the residual magnetization are small and the fluidity is high, the carrier in the replenishment developer having a high T / C ratio (the ratio of the toner in the two-component developer) becomes longer in the replenishment developer. It becomes possible to be uniformly dispersed. As a result, a replenishing developer having a constantly stable T / C ratio can be replenished to the developing tank, and a long-term stable high-quality toner image can be formed.

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.

An image forming apparatus provided with a developing device using the replenishing developer of the present invention will be described. FIG. 1 is a schematic configuration diagram of an electrophotographic full-color image forming apparatus equipped with a rotary rotation type developing device. First, the surface of the electrostatic latent image carrier 1 is uniformly charged to a negative polarity by the charging device 15. Next, the exposure device 14 performs image exposure corresponding to the first color, for example, a yellow image.
On the surface of the electrostatic latent image carrier 1, an electrostatic latent image corresponding to a yellow image is formed.

The developing device 13 is of a rotary moving type, and the yellow developing device faces the electrostatic latent image carrier 1 before the leading end of the electrostatic latent image corresponding to the yellow image reaches the developing position. Thereafter, the magnetic brush rubs the electrostatic latent image to form a yellow toner image on the electrostatic latent image carrier.

In the developing device used for the above-described development, for example, a developing sleeve, a supply roll, a magnet roll, a regulating member, a scraper, and the like are provided inside the developing device. FIG. 2 is a schematic configuration diagram of the developing units 2, 3, 4, and 5 of FIG. Referring to FIG. 2, a flow of the developer in the developing machine until the developer is developed will be described.

The developing sleeve 6 contains a fixed magnet and is driven and rotated while maintaining a predetermined developing interval between the developing sleeve 6 and the peripheral surface of the electrostatic latent image carrier 1. The developing sleeve 6 and the electrostatic latent image carrier 1 may be in contact with each other. The regulating member 7 has rigidity and magnetism and is pressed against the developing sleeve 6 with a predetermined load in a state where the developer is not interposed therebetween, or is disposed at a predetermined distance from the developing sleeve 6. And so on. The pair 10 and 11 have a screw structure, function to convey and circulate the developer in opposite directions to sufficiently agitate and mix the toner and the carrier, and then send the toner and the developer to the developing sleeve 6 as a developer.
The magnet roll 8 is formed of, for example, a magnet of four poles of equal magnetic force in which N poles and S poles are alternately arranged at equal intervals, or forms a repulsive magnetic field in a portion in contact with the scraper, and peels off the developer. In order to facilitate the above, one pole may be dropped to five poles, and may be included in the developing sleeve 6 in a fixed state.

The two developer stirring / conveying members 10 and 11
Is a member that also functions as a stirring member that rotates in directions opposite to each other, and conveys replenishing toner supplied from the toner storage device 9 by the thrust of the stirring screw,
Due to the mixing action of the toner and the magnetic carrier, a uniform two-component developer triboelectrically charged is formed, and the developer adheres in a layer on the peripheral surface of the developing sleeve 6. The developer on the surface of the developing sleeve 6 forms a uniform layer by the regulating member 7 having a double structure made of a non-magnetic material and a magnetic material provided opposite to the magnetic pole of the magnet roll 8. The uniformly formed developer layer develops a latent image on the peripheral surface of the electrostatic latent image carrier 1 in a development area to form a toner image.

In FIG. 1, a transfer material 12 such as a paper or a transparent sheet is conveyed from a paper feed tray 26 or 27 by a feed roll 28 or 29, and once its tip is closed by a registration roll 25, It is sent to the transfer drum 24 at a predetermined timing. The transferred transfer material 12 is attached to the suction device 32 and the opposing roll 30.
The transfer drum 24 and the electrostatic latent image carrier 1 are conveyed to a transfer area where the transfer drum 24 and the electrostatic latent image carrier 1 face each other. Then, the transfer material comes into close contact with the yellow toner image on the electrostatic latent image carrier 1, and the yellow toner image is transferred onto the transfer material 12 by the operation of the transfer device 31.
Prepares for the next step while holding the transfer material 12.

After the transfer of the yellow toner, the electrostatic latent image carrier 1 is subjected to a pre-cleaning process, if necessary, and then is discharged by a discharging corotron, and the yellow toner remaining on the surface by the cleaning device 18 is removed. Is removed, and the charge remaining on the surface is further removed by the charge removing device 16.

Next, for the second color, for example, magenta image forming process, the electrostatic latent image carrier 1 is
The surface of the electrostatic latent image carrier 1 is uniformly charged to a negative polarity, image exposure corresponding to the magenta image is performed by the laser exposure device 14, and an electrostatic latent image corresponding to the magenta image is formed on the surface of the electrostatic latent image carrier 1. It is formed. Further, after the formation of the yellow toner layer is completed, the developing device 13 is switched so that the magenta developing device faces the electrostatic latent image carrier 1, and the electrostatic latent image corresponding to the magenta image is changed. The image is developed with a magenta magnetic brush. Then, the transfer material held on the transfer drum is again conveyed to the transfer area, and by the operation of the transfer device 31, the magenta toner is multiply transferred onto the yellow toner.

After the transfer of the magenta toner, the electrostatic latent image carrier 1 is cleaned of the residual toner on the surface and neutralized of the residual electric charges in the same manner as in the yellow image forming step. After the transfer of the transfer material is completed, the transfer material is held on the transfer drum 24 and is ready for the next step.

Thereafter, in the same manner as in the magenta image forming step, a third color, for example, cyan image forming step is performed, and finally, a fourth color, for example, black image forming step is performed. In the final black image forming step, the transfer of the transfer material is different from the steps up to the third color. That is, the transfer material having completed the transfer of the fourth color is separated from the transfer drum 24 by the peeling static eliminator 19 and the peeling finger (not shown) at the tip of the transport guide member 20, and the fixing device 21 forms the multi-toner image by the transfer material Is transferred to the outside of the image forming apparatus.

The transfer drum 2 from which the transfer material has been separated
In 4, after the surface is neutralized by the neutralization devices 22 and 33, the surface cleaning is performed by the cleaning device 23, and the supply of the next transfer material 12 is awaited.

When the above copying operation is repeated,
The toner in the developer accommodated in the developing tank 17 in the developing device in FIG. 2 is gradually consumed, and the ratio of the toner to the carrier, that is, the toner concentration decreases. This change in toner density is feedback-controlled by a toner density sensor (not shown) provided in the developing tank 17 so that the toner density always falls within an appropriate range required for development. By the above control, the toner is supplied from the supply port of the toner supply unit (toner storage device 9) to the developing tank 17 in the developing device.

On the other hand, the carrier in the developer in the developing tank 17 is not consumed by the development, but is stirred together with the toner in the developing tank 17, the magnetic force of the magnet roll, and the electrostatic latent image. Due to the influence of contact with the carrier 1 and the like,
The surface is gradually contaminated and deteriorates. When the carrier deteriorates in this manner, a predetermined amount of charge cannot be imparted to the toner, and the image quality deteriorates. Therefore, it is necessary to replace the unconsumed deteriorated carrier in the developing device with a new carrier. In FIG. 1, as a means for replenishing a new carrier into the developing device, toner for replenishment and a predetermined amount of the carrier are stored in a toner cartridge (toner storage device 9) for replenishing toner consumed by development. Is mixed, and the developing devices 2 and
Replenish to 3, 4 and 5. The excess developer is discharged from the developer outlet on the developing device side as described below.

The replacement of the developer utilizing the rotational movement in the rotationally moving developing device 13 shown in FIG. 1 will be described with reference to FIGS. In the full-color image forming apparatus using the developing device 13 adopting the rotational movement method, the developing units 2, 3, 4, and 5 rotate inside the developing device 13 and face the electrostatic latent image carrier 1 during development. Position to perform development, and at the time of non-development, the electrostatic latent image carrier 1
Rotationally move to a position that does not face.

At the position where the developing device 2 faces the electrostatic latent image carrier 1 and performs the developing operation, the developer overflowing from the developing device side developer discharge port 34 provided in the developing device 2 is rotated. The developer is moved in the communication pipe 36 by the operation, and is discharged from the developer collecting port 35 provided on the rotation center shaft of the rotary developing device switching device.

As a developing method using the carrier of the present invention, specifically, an AC voltage is applied to the developer carrier to form an alternating electric field in the developing area while the magnetic brush contacts the photosensitive drum 1. It is preferable to carry out development in a state where the development is performed. Developer carrier (developing sleeve) 6 and photosensitive drum 1
Is preferably 100 to 1000 μm in terms of preventing carrier adhesion and improving dot reproducibility. If it is smaller than 100 μm, the supply of the developer tends to be insufficient, and the image density becomes low.
exceeds m the lower the density of magnetic lines of force spread magnetic brush from the magnetic pole S _1, or poor dot reproducibility, the force constraint weakens carrier adhesion easily occurs the magnetic coated carrier.

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 of the AC bias for forming the alternating electric field may be a triangular wave, a rectangular wave, a sine wave, or a waveform having a changed duty ratio. In order to cope with a change in the speed of forming a toner image, it is preferable to apply a developing bias voltage having a discontinuous AC bias voltage (intermittent alternating superimposed voltage) to the developer carrying member to perform development. . 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 3000 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. As the contrast potential, 100 to 400 V is preferably used so that a sufficient image density can be obtained.

If the frequency is lower than 500 Hz, the toner in contact with the electrostatic latent image carrier is returned to the developing sleeve, but sufficient vibration is not applied and fog is liable to occur, although this is related to the process speed. Become. 10,000Hz
When the value exceeds, the toner cannot follow the electric field, and the image quality is likely to be deteriorated.

What is important in the developing method of the present invention is that the photosensitive drum 1 of the magnetic brush on the developing sleeve 11 is used in order to obtain a sufficient image density, have excellent dot reproducibility, and perform development without magnetic carrier adhesion. Is preferably 3 to 8 mm. If the developing contact portion is smaller than 3 mm, it is difficult to sufficiently satisfy a sufficient image density and dot reproducibility. If the developing contact portion is wider than 8 mm, packing of a developer occurs, which stops the operation of the machine, or causes a magnetic carrier. It becomes difficult to sufficiently suppress the adhesion.
As a method of adjusting the developing contact portion, the distance between the regulating blade 7 and the developing sleeve 6 or the distance between the developing sleeve 6 and the photosensitive drum 1 (distance between SD) is adjusted to adjust the contact width. Is appropriately adjusted.

The structure of the photoreceptor may be the same as that of a photoreceptor used in an image forming apparatus. For example, a conductive layer, an undercoat layer, and a charge generation layer may be formed on a conductive base such as aluminum or SUS in this order. , A charge transport layer and, if necessary, a photoreceptor having a configuration in which a charge injection layer is provided.

The conductive layer, the undercoat layer, the charge generation layer, and the charge transport layer may be those usually used for a photoreceptor.

For example, a charge injection layer or a protective layer may be used as the outermost surface layer of the photosensitive member.

Further, by using the replenishing carrier of the present invention, the share of the developer in the developing device is small, and the toner or the external additive to the carrier is used even when copying many sheets. Etc. are suppressed,
Even with a small amount of replenishment carrier, the effect of the present invention with little deterioration in image quality can be sufficiently exhibited.

The image forming method of the present invention will be further described with reference to the drawings.

In FIG. 5, the magnetic force of the magnet roller 51 causes the magnetic particles 5
A charging magnetic brush 3 is formed, and the magnetic brush is brought into contact with the surface of an electrophotographic photosensitive member (hereinafter referred to as “photosensitive member”) 40 to charge the photosensitive member 40. Transfer sleeve 5
2, a charging bias is applied by bias applying means (not shown). The charged photoconductor 40 is irradiated with a laser beam 54 by an exposure device (not shown) to form a digital electrostatic latent image. The electrostatic latent image formed on the photoreceptor 40 includes a magnet roller 42, and a toner 49a in a developer 49 carried on a developing sleeve 41 to which a developing bias is applied by a bias applying device (not shown). Developed.

The developing device 43 is divided into a developer chamber R ₁ and a stirring chamber R ₂ by a partition wall 47, and developer conveying screws 46 and 47 are provided respectively. Above the stirring chamber R _2, a toner storage chamber R ₃ containing a replenishing toner 48 is installed, the toner supply opening 50 is provided in the lower portion of the storage chamber R _3.

[0193] The developer conveying screw 46 by rotating and conveying in the longitudinal direction of the developing sleeve 41 in one direction while stirring the developer in the developer chamber R _1. The partition 47 has openings (not shown) on the near side and the back side in the figure, and the developer conveyed to _one of the developer chambers R1 by the screw 46 passes through the opening of the partition 47 on one side. The developer is sent to the stirring chamber R ₂ and is transferred to the developer conveying screw 44. In the direction of rotation the screw 46 opposite the screw 44, the developer in the stirring chamber R _2, the developer chamber R ₁
While stirring and mixing the developer and the toner replenished from the toner storage chamber R ₃ delivered from the container, the developer is conveyed in the stirring chamber R ₂ in a direction opposite to the screw 46 and passes through the other opening of the partition wall 47. sent into the developer chamber R _1.

[0194] To develop the electrostatic latent image formed on the photosensitive member 40, the developer 49 in the developer chamber R ₁ is drawn up by the magnetic force of the magnet roller 42, the developing sleeve 41
Carried on the surface of The developer carried on the developing sleeve 41 is conveyed to the regulating blade 45 with the rotation of the developing sleeve 41, 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 42, the magnetic poles are (developing pole) N ₁ is positioned, the developing pole N ₁ forms a developing magnetic field in the developing region, the developer Shi standing ears by the developing magnetic field Thus, a magnetic brush of the developer is generated in the developing area. Then, the magnetic brush comes into contact with the photoconductor 40, and the toner adhering to the magnetic brush and the toner adhering to the surface of the developing sleeve 41 by the reversal development method are transferred to the area of the electrostatic latent image on the photoconductor 40. The toner image is transferred and adheres, and the electrostatic latent image is developed to form a toner image.

[0195] developer having passed through the developing region is returned into the developing device 43 with the rotation of the developing sleeve 41 is taken off from the developing sleeve 41 by the screw 46, the developer chamber R ₁ and the stirring chamber R ₂ Dropped and collected.

[0196] Toner 48 from T / C ratio (toner mixing ratio of the carrier, i.e., toner concentration in the developer) When decreases is, the supply developer storage chamber R ₃ of the developer 49 in the developing device 43 by development of the was supplied to the stirring chamber R ₂ in an amount that was found in the amount consumed by the developing, carriers increased more than necessary, as the deterioration developer is mixed with the toner, is removed from the 59 discharge screw to the outside developer The T / C and the carrier amount of the developer 49 in the device 43 are maintained at predetermined amounts. To detect the T / C ratio of the developer 49 in the container 43, a toner density detection sensor 58 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 45 disposed below the developing sleeve 41 and regulating the layer thickness of the developer 49 on the developing sleeve 41 is a non-magnetic blade 45 made of a non-magnetic material such as aluminum or SUS316. The distance between the end and the surface of the developing sleeve 41 is 150 to 800 μm.
m, preferably from 250 to 700 μm. If the distance is less than 150 μm, the magnetic carrier is aggregated and clogged during this period, which tends to cause unevenness in the developer layer. In addition, it is difficult to apply the developer necessary for good development, and the density is low. An image is easily formed. This distance is preferably 150 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 800 μm, the developing sleeve 4
As a result, the amount of the developer applied on the photosensitive member 40 is increased, and it is difficult to regulate the predetermined thickness of the developer layer.
, The toner is less regulated, and the toner is easily fogged.

Even when the developing sleeve 41 is rotationally driven 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 magnetic force and gravity and the conveying force in the moving direction of the developing sleeve 41. Movement slows down. It falls under the influence of gravity.

Further, the developed toner image is transferred onto a transfer material (recording material) 55 conveyed by a bias applying means 56.
The toner image transferred by the transfer blade 57, which is a transfer unit to which a transfer bias is applied, 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 photoreceptor 40 without being transferred to the transfer material is adjusted in charge in the charging step, and is collected during development.

FIG. 6 is a schematic diagram in which the image forming method of the present invention is applied to a full-color image forming apparatus. Also, the full-color image forming apparatus in FIG. 6 does not have an independent cleaning unit for collecting and storing the transfer residual toner remaining on the photoconductor, and after the developing unit transfers the toner image onto the transfer material. The developing and cleaning method for recovering the toner remaining on the image carrier is performed.

The carrier increased in amount by the carrier contained in the replenishment developer overflows the capacity UP, is taken into the developer collection auger, and is conveyed to the replenishment developer container or another collection container.

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 structure of each image forming unit provided in the image forming apparatus will be described by taking the first image forming unit Pa as an example.

The first image forming unit Pa includes a photosensitive member 61a having a diameter of 30 mm as an electrostatic latent image carrier.
The photoreceptor 61a is rotated in the direction of arrow a. The primary charging device 62a as a charging means includes a charging magnetic brush formed on the surface of a sleeve having a diameter of 16 mm.
It is arranged so as to contact the surface of a. The laser beam 67a is irradiated by an exposure device (not shown) to form an electrostatic latent image on the photoconductor 61a whose surface is uniformly charged by the primary charger 62a. Photoconductor 61
a developing device 63a as developing means for developing the electrostatic latent image carried on
Holds color toner. The transfer blade 64a as a transfer unit transfers the color toner image formed on the surface of the photoconductor 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 member 61a by the primary charger 62a, and forms an electrostatic latent image on the photosensitive member by the exposure device 67a.
The developing device 63a develops the electrostatic latent image using a color toner, and the developed toner image is transferred to a belt-like shape which carries and conveys a transfer material at a first transfer portion (a contact position between the photoconductor and the transfer material). Transfer blade 64 abutting on the back side of transfer material carrier 68
The transfer is performed on the surface of the transfer material by applying a transfer bias from a.

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

The present 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 fixing device 70 by a conveying means such as a conveying belt.
And a 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 therein.
have.

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. 6, 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.
In addition, a transfer belt cleaning device 79, a belt driven roller 81, and a belt static eliminator 82 are provided. A pair of registration rollers 83 are for transporting the transfer material in the transfer material holder to the transfer material carrier 68. is there.

As the transfer means, instead of the transfer blade abutting on the back side of the transfer material carrier, a contact capable of directly applying a transfer bias by abutting on the back surface side of the transfer material carrier such as a roller-shaped transfer roller. It is possible to use transfer means.

Further, in place of the above-mentioned contact transfer means, 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. It is also possible to use non-contact transfer means.

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

Next, methods for measuring various characteristic values according to the present invention will be listed.

(Method of Measuring Toner Particle Size) Electrolyte Solution 1
0.1 to 5 ml of a surfactant (alkylbenzene sulfonate) is added to 00 to 150 ml, and 2 to 20 mg of a measurement sample is added thereto. The electrolytic solution in which the sample is suspended is subjected to dispersion treatment with an ultrasonic disperser for 1 to 3 minutes, and a particle size distribution or the like of 0.3 to 40 μm is measured by a Coulter counter multisizer using a 100 μm aperture based on the volume. It shall be. The number average particle diameter measured under these conditions, the weight average particle diameter is determined by computer processing,
Further, from the particle size distribution based on the number, a cumulative ratio of less than a half-size cumulative distribution of the number average particle size is calculated, and a cumulative value less than a 1 / 2-size cumulative distribution is calculated. 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.

(Method for Measuring Particle Size of Carrier) The average particle size is represented by a volume average particle size measured by a laser diffraction type particle size distribution meter (manufactured by Horiba, Ltd.).

(Method for Measuring the Particle Size of Magnetic Particles (Non-magnetic Inorganic Fine Particles)) The particle size of 50 particles on a transmission electron micrograph (magnification: 30,000) is measured, and the average is defined as the particle size.

(Method of Measuring Magnetic Properties of Carrier and Magnetic Particle) The magnetization value (σ ₁₀₀₀ ) and the residual magnetization value (σr) were measured using a vibrating sample magnetometer VSM-3S-15 (manufactured by Toei Kogyo Co., Ltd.). It was measured.

(Method of Measuring True Specific Gravity of Carrier) The true specific gravity is measured by using a multi-volume density meter (manufactured by Micromeritics).
It was shown by the value measured in.

(Method of Measuring Volume Specific Resistance of Carrier and Magnetic Particle) The specific resistance was measured using a high resistance meter 432.
9A (manufactured by Yokogawa Hewlett-Packard). More specifically, the specific resistance of the magnetic fine particles or the carrier is measured using a measuring device shown in FIG. Cell E
Is filled with magnetic fine particles or a carrier.
The electrodes 121 and 122 are disposed so as to be in contact with the magnetic fine particles or the carrier filled as 7, and a voltage is applied between the electrodes, and a current flowing at that time is measured to obtain a specific resistance. In the above-described measurement method, since the magnetic fine particles or the carrier are powder, a change occurs in the filling rate, which may cause a change in the specific resistance. The conditions for measuring the specific resistance are as follows: the contact area S between the filled magnetic fine particles or the carrier and the electrode is about. 2.3cm ² ,
Thickness d = about 2 mm, load of the electrode 122 1.76 N
(180 g) and the applied voltage is 100 V.

(Method of Measuring Friction Charge) A toner and a carrier are mixed so as to have an appropriate mixing amount (toner: 2 to 15% by mass), and mixed for 120 seconds using a turbula mixer. This mixed powder (developer) was placed in a metal container equipped with a 635-mesh conductive screen at the bottom, suctioned by a suction machine, and the difference in mass before and after suction and accumulated in a condenser connected to the container. The amount of triboelectric charge is determined from the potential. At this time, the suction pressure is set to 250 mmHg. With this method, the frictional charge amount of the toner is calculated using the following equation.

[0222]

[Outside 1]

(Where W1 is the mass of the mixed powder before suction, W2 is the mass of the mixed powder after suction, C is the capacity of the condenser, and V is the potential stored in the condenser. .)

[0224]

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.

(Production Example 1 of Hydrophobic Iron Oxide) Fe ²⁺ 2.4
To 57 liters of an aqueous ferrous sulfate solution containing mol / liter, 2646 g of magnesium sulfate containing 9.9% by mass of Mg in terms of Mg element and sodium carbonate were added to adjust the pH to 9. A mixture of 65 mol of 4.4 mol / l sodium hydroxide aqueous solution and the adjusted aqueous solution was mixed,
While maintaining the temperature at 80 ° C., air was blown at 40 liters / min, and crystals were grown for 30 minutes. Next, 6.5 liters of an aqueous solution of ferrous sulfate having the same concentration as that used at the beginning of the reaction was added to the iron hydroxide slurry containing the seed crystal particles, and the pH was adjusted to 8 to 8 while adding an aqueous solution of sodium hydroxide.
9. At a temperature of 85 ° C., 40 liter / min of air was blown in to complete the oxidation reaction in 6 hours. The magnetite slurry after the reaction is washed, filtered, dried, and
Crushed. The magnetite particles thus obtained have a total M
g amount is 2.1% by mass, and the surface exposed Mg amount is 0.26%.
% By mass.

The magnetite thus obtained was
The particle size, magnetic properties, volume resistance value and degree of aggregation were measured, and the results are shown in Tables 1 and 2.

The above magnetite (magnetite I) 10
0 parts by mass was subjected to a surface treatment with 0.5 parts by mass of γ-glycidyltrimethoxysilane to obtain hydrophobic iron oxide 1.

Method for measuring the degree of agglomeration: One method for measuring the flow characteristics of hydrophobic iron oxide is to use the degree of agglomeration.
It is determined that the larger the value of the degree of aggregation, the poorer the fluidity of the sample. Measurement sample is 400 g per 1 liter poly bottle
It was charged and left standing for 5 days under each environment to measure.

As a measuring device, a powder tester (manufactured by Hosokawa Micron Co., Ltd.) having a digital vibrometer (Digi Vibro Model 1332) was used.

The measurement was performed at a vibration time of 60 sec. The measurement results were calculated by a predetermined calculation formula to determine the degree of aggregation. The degree of agglomeration of less than 30% was defined as "low", and the degree of aggregation of 30% or more was defined as "high".

(Production Examples 2 to 19 of Hydrophobic Iron Oxide) Hydrophobic iron oxide was prepared by changing the addition amount of the magnesium component, the silicon component, the manganese component, the phosphorus component, and the amount of the alkali to change the pH during the oxidation reaction variously. Hydrophobic iron oxides 2 to 20 were obtained in the same manner as in the case of hydrophobic iron oxide 1. Tables 1 and 2 show the main production conditions and the physical properties of the formed hydrophobic iron oxides 2 to 19.

(Production Example 20 of Hydrophobic Iron Oxide) Fe ²⁺
1323 g of magnesium sulfate containing 9.9% by weight of Mg element in terms of Mg element and 13% in terms of Si element in 57 L of an aqueous ferrous sulfate solution containing 4 mol / L.
1005 g of sodium silicate and sodium carbonate
Adjusted to H9. 65 liters of 4.4 mol / L aqueous sodium hydroxide solution and the above-prepared aqueous solution were mixed,
Air was blown at 40 L / min while maintaining the temperature at 80 ° C., and the crystals were grown for 30 minutes. Next, 6.5 liters of an aqueous ferrous sulfate solution having the same concentration as that used at the beginning of the reaction was added to the iron hydroxide slurry containing the seed crystal particles.
At 5 ° C., air was blown at 40 liters / min to allow the oxidation reaction to proceed. On the way, while checking the unreacted ferrous hydroxide concentration, the progress of the reaction was examined. When the progress of the reaction progressed by 45% with respect to the beginning of the reaction, 10 liters of a 0.18 mol / liter nickel sulfate aqueous solution was added. Over 100 minutes, the oxidation reaction was added to the ferrous hydroxide slurry containing magnetite during the oxidation reaction, and the pH was maintained at 6 to 9 to complete the oxidation reaction in 6 hours. The magnetite slurry after the completion of the reaction was washed, filtered, dried and pulverized by a conventional method. The magnetite thus obtained had a total Mg amount of 1.1% by mass, a total Si amount of 1.1% by mass, a surface exposed Mg amount of 0.13% by mass, and a surface exposed Si amount of 0.13% by mass. The total amount of Si, Mg and Ni is 2.6% by mass,
The total amount of Mg and Ni was 0.46% by mass.

The magnetite thus obtained was
The particle size, magnetic properties, volume resistance value and cohesion degree described above were measured, and the results are shown in Tables 1 and 2.

100 parts by mass of the above magnetite was subjected to a surface treatment with 0.5 parts by mass of γ-glycidyltrimethoxysilane to obtain hydrophobic iron oxide 20.

(Production Examples 21-31 of Hydrophobic Iron Oxide) Hydrophobic iron oxide 2 was prepared except that the type and amount of the added metal component were changed.
0, hydrophobic iron oxides 21 to 31 were obtained. Tables 1 and 2 show the physical properties of the hydrophobic iron oxides 21 to 31.

[0236]

[Table 1]

[0237]

[Table 2]

[Production Example of Carrier 1] • 50 parts by mass of phenol (hydroxybenzene) • 80 parts by mass of a 37% by mass aqueous formalin solution • 50 parts by mass of water • 600 parts by mass of hydrophobic iron oxide 1 • 25% by mass of aqueous ammonia 15 parts by mass Put the above materials in a four-necked flask and mix while stirring.
The temperature was raised to 85 ° C. in 0 minutes, and the reaction and curing were performed 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 was reduced to 150 to 180 under reduced pressure (5 mmHg).
After drying at 24 ° C. for 24 hours, a carrier core using a phenol resin as a binder resin was obtained.

On the surface of the obtained carrier core, a 5% by mass toluene solution of γ-aminopropyltrimethoxysilane as a silane coupling agent was applied.

The surface of the carrier core has a γ of 0.2% by mass.
-Has been treated with aminopropyltrimethoxysilane. During the application, the toluene was volatilized while applying while continuously applying shear stress to the carrier core. On the surface of the carrier core

[0241]

[Outside 2]

Was confirmed to be present.

While stirring the magnetic carrier core treated with the silane coupling agent in the above-mentioned processing machine at 70 ° C., a silicone resin solid content of 3% was added to the silicone resin KR-221 (manufactured by Shin-Etsu Chemical Co., Ltd.). After adding [gamma] -aminopropyltrimethoxysilane and diluting with toluene so as to have a silicone resin solid content of 20%, the mixture was added under reduced pressure to coat the resin. The coating amount is the carrier core 1
The operation was performed so that the silicone resin solid content was 0.8 parts by mass with respect to 00 parts by mass.

After stirring for 2 hours, heat treatment was performed at 140 ° C. for 2 hours in an atmosphere of nitrogen gas to loosen agglomeration, and coarse particles having an opening of 82 μm (200 mesh) or more were removed. A carrier 1 having physical properties was obtained.

[Examples of Production of Carriers 2 to 31] Carrier I
In the same manner as in Production Example 1 except that hydrophobic iron oxides 2 to 31 were used instead of hydrophobic iron oxide 1, carriers 2 to 31 having physical properties shown in Table 3 were obtained.

[Production Example of Carrier 32] Carrier 32 having the physical properties shown in Table 3 was obtained in the same manner as in the production example of Carrier 1, except that magnetite particles I were used in place of hydrophobic iron oxide 1.

[Production Example of Carrier 33] The same procedure as in Production Example of Carrier 1 was carried out except that 540 parts by mass of hydrophobic iron oxide 1 and 60 parts by mass of hydrophobic hematite having an average particle size of 0.35 μm were used. 3 was obtained.

[Production Example of Carrier 34] The same procedure as in Production Example of Carrier 1 was conducted except that 420 parts by mass of hydrophobic iron oxide 1 and 120 parts by mass of hydrophobic hematite having an average particle size of 0.35 μm were used. Physical properties carrier 34 shown in 3
I got

[Production Example of Carrier 35] A carrier 35 having physical properties shown in Table 3 was obtained in the same manner as in the production example of Carrier 1, except that the silicone resin was not coated.

[Production Example of Carrier 36] A carrier 36 having the physical properties shown in Table 3 was obtained in the same manner as in Production Example of Carrier 1, except that γ-aminopropyltrimethoxysilane was not coated.

[Production Examples of Carriers 37 to 39] In the production example of Carrier 1, the same procedure as in Table 3 was carried out except that hydrophobic iron oxide 9 was used instead of hydrophobic iron oxide 1 and the stirring speed was further changed. Carriers 37 to 39 having the following physical properties were obtained.

[Production Examples of Carriers 40 to 42] In the production example of Carrier 1, the same procedure as in Table 3 was carried out except that hydrophobic iron oxide 28 was used instead of hydrophobic iron oxide 1 and the stirring speed was further changed. Carriers 40 to 42 having the physical properties shown were obtained.

[0253]

[Table 3]

Example of Production of Toner 1 450 parts by mass of a 0.1 M Na ₃ PO ₄ aqueous solution was charged into 710 parts by mass of ion-exchanged water, and heated to 60 ° C.
1300 using a homo homomixer (manufactured by Tokushu Kika Kogyo)
Stirred at rpm. 68 parts by mass of a 1.0 M CaCl ₂ aqueous solution was gradually added thereto to obtain a pH 6 aqueous medium containing Ca ₃ (PO ₄ ) ₂ . 160 parts by mass of styrene 34 parts by mass of n-butyl acrylate 12 parts by mass of copper phthalocyanine pigment 2 parts by mass of metal compound ditertiary butylsalicylate 2 parts by mass of saturated polyester 10 parts by mass (acid value 10 mg KOH / g, peak molecular weight 8500) Monoester 20 parts by mass of wax (Mw: 500, Mn: 400, Mw / Mn: 1.25, melting point: 69 ° C., viscosity: 65 mPa · s, Vickers hardness: 1.1, SP value: 8.6) The mixture was heated to 60 ° C., and uniformly dissolved and dispersed at 12,000 rpm using a TK homomixer (manufactured by Tokushu Kika Kogyo). 10 g of a polymerization initiator 2,2′-azobis (2,4-dimethylvaleronitrile) was dissolved therein,
A polymerizable monomer composition was prepared.

The polymerizable monomer composition was charged into the aqueous medium, and the mixture was stirred at 10,000 rpm for 10 minutes at 60 ° C. in a N ₂ atmosphere using a Clare mixer (manufactured by M Technique Co., Ltd.). The composition was granulated. Thereafter, the temperature was raised at 80 ° C. while stirring the aqueous medium with a paddle stirring blade,
While maintaining the pH at 6, a polymerization reaction was carried out for 10 hours.

After the completion of the polymerization reaction, the mixture was cooled, hydrochloric acid was added to adjust the pH to 2, and calcium phosphate was dissolved, followed by filtration, washing with water and drying to obtain polymerized particles (toner particles 1).

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

The binder resin of the polymer particles obtained was S
The P value was 19 and the Tg was 60 ° C. The weight average particle size of the obtained cyan toner particles was 7.3 μm.

The following three external additives were externally added to 100 parts by mass of the obtained polymer particles (toner particles).
The coarse powder was removed with a 0-mesh sieve to obtain a negatively chargeable cyan toner (toner 1). The weight average particle size of Toner 1 is 7.
It was 3 μm.

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

(2) 0.7 parts by mass of second hydrophobic silica fine powder: BET specific surface area 70 m ² / g Number average particle diameter 30 nm Hexamethyldisilazane 10 in a gas phase with respect to 100 parts by mass of silica fine powder Hydrophobized by mass.

(3) Hydrophobic titanium oxide fine powder 0.4 parts by mass: BET specific surface area 100 m ² / g Number average particle diameter 45 nm Isobutyltrimethoxysilane 10 parts by mass in an aqueous medium with respect to 100 parts by mass of titanium oxide fine powder Hydrophobized part.

Preparation Example of Toner 2 Magenta polymer particles (toner particle 2) were obtained in the same manner as in Preparation Example of Toner Particle 1 except that a quinacridone pigment was used instead of the copper phthalocyanine pigment. The obtained toner particles 2 had a weight average particle size of 7.3 μm.

Production Example of Toner 3 In place of the copper phthalocyanine pigment, C.I. I. Pigment Yellow 180 and Solvent Yellow 163 were used, and yellow polymer particles (toner particles 3) were obtained in the same manner as in the production example of toner particles 1. The obtained toner particles 3 had a weight average particle size of 7.2 μm.

Production Example of Toner 4 Black polymer particles (toner particle 4) were obtained in the same manner as in the production example of toner particle 1 except that carbon black was used instead of the copper phthalocyanine pigment. The obtained toner particles 4 had a weight average particle size of 7.4 μm.

<Example 1> A toner (7 parts) and a carrier (93 parts) were mixed with a V-type mixer to form a two-component developer.
1 part by mass and mixed with a V-type mixer to make a replenishing developer,
Next, as an image forming apparatus, a developing device of a commercial copying machine GP55 (manufactured by Canon) was modified as shown in FIG. Specifically, as the developing sleeve, a SUS sleeve having a diameter of 16 mm whose surface shape was adjusted to a surface roughness Rz = 12.1 μm by sandblasting was used. As the charging member, magnetic particles a are used using a magnetic brush charger shown in FIG.
Rotation at 00%, DC / AC electric field (-700V, 1.
5 kHz / 1.2 kVpp).
Is charged. Further, the cleaning unit is removed, and the developing contrast is set to 250 V and the reversal contrast with fog is set to -180 V. A developing bias having a discontinuous AC voltage shown in FIG. Both the heating roller and the pressure roller were changed to rollers in which the surface layer was coated with PFA (ethylene tetrafluoride-perfluoroalkyl vinyl ether copolymer) at 1.2 μm, and the oil application mechanism was removed.

Using an original manuscript having an image area of 50%, 23 ° C./60% (N / N), 23 ° C./5% (N / N)
L), 32.5 ° C./90% (H / H), 20,000 sheets of paper passing test were performed using CLC80g paper (manufactured by Canon Sales Co., Ltd.) in each environment, and evaluated based on the following evaluation method. .
The results are shown in Tables 4 and 5, and as can be seen from the tables, good results were obtained.

[Evaluation Method / Criteria] Image density: The image density was determined by converting a solid image into an X-Rite 40 image.
4A color reflection densitometer (X-Rite Incorporated)
rated). At the time of measurement, five white copy papers are placed on a desk, and the measurement is performed so as not to pick up the influence of the background. Fog: In the present invention, the amount of fog in the non-image area is measured by a reflection densitometer (TOKYO DENSHOKU CO, L
REFLECOMETER MODEL T manufactured by TD
C-6DS) (Ds is the worst value of the reflection density of the white background after printing, and Ds-Dr is the fog amount when the average reflection density of the paper before printing is Dr).
As in the case of the image density measurement, the measurement is performed by placing five white copy sheets on a desk so as not to pick up the influence of the background. A: Less than 0.4% B: 0.4 to less than 0.8% C: 0.8 to less than 1.2% D: 1.2 to less than 1.6% E: 1.6% or more Highlight Evaluation of the image quality of the part: Five levels of A (excellent) to E (bad) were visually observed by comparison with the standard sample of the highlight part. Evaluation criteria for toner scattering: The degree of toner scattering from the developing device was visually evaluated in five stages. A: There is substantially no toner scattering. B: Slight toner scattering is observed. C: There is toner scattering, but there is no effect on the image, and cleaning of the developing device is not necessary even after 20,000 sheets have passed. D: The toner was scattered and 20,000 sheets passed, and there was no effect on the image, but finally the developing device needs to be cleaned. E: The toner is scattered, the image is stained after passing 20,000 sheets, and the developing device needs to be cleaned frequently. -Loss of image quality due to scratches on electrostatic image carrier: As a means for evaluating the adhesion of carriers to the surface of the electrostatic image carrier, image loss due to scratches on the surface of the electrostatic image carrier after passing 20,000 sheets was observed. . After the endurance of 20,000 sheets, the surface of the electrostatic image carrier was observed with a scanning electron microscope, and the image quality was visually evaluated, and evaluated according to the following criteria. A: No scratch was observed on the surface of the photosensitive drum, and the image was good without any image loss. B: Despite slight scratches on the surface of the photosensitive drum, the image was good without any image loss. C: Despite considerable scratches on the photosensitive drum surface, no image loss occurred. D: Slight image omission is observed in the highlight portion, but there is no defect in the character image, and there is no practical problem. E: Missing character images are also observed.

<Examples 2 to 7> When the same procedure as in Example 1 was carried out except that Carrier 1 was Carriers 2 to 7, good results were obtained as shown in Tables 4 and 5.

<Embodiment 8> The same operation as in Embodiment 1 was carried out except that the carrier 1 was the carrier 8, and as shown in Tables 4 and 5, the fog in the H / H environment was higher than that of the embodiment 1. The toner scattering was slightly inferior.
It is considered that this is because the amount of the silicon component and the magnesium component added was large, so that the hygroscopicity of the carrier under high humidity was increased and the environmental stability was slightly lowered.

<Examples 9 to 11> When the same procedure as in Example 1 was carried out except that the carrier 1 was the carriers 9 to 11, good results were obtained as shown in Tables 4 and 5.

<Example 12> In Example 1, except that the carrier 1 was the carrier 12, the same procedure was performed as shown in Tables 4 and 5, and the fog and toner scattering were slightly different from those in Example 1. Became inferior. This is because the magnesium component and the silicon component on the surface of the hydrophobic iron oxide are not exposed, so that the dispersion of the hydrophobic iron oxide in the carrier becomes non-uniform, the SF of the carrier increases, and the charging ability to the toner is slightly reduced. It is thought that it decreased.

<Comparative Example 1> In Example 1, except that the carrier 1 was the carrier 13, the same operation was performed.
As shown in Tables 4 and 5, fogging and toner scattering were significantly inferior to those in Example 1, and image defects due to scratches on the surface of the electrostatic image carrier were observed. This is presumably because the saturation magnetization was small because the magnesium and silicon components inside the hydrophobic iron oxide were small, and the residual magnetization of the carrier was large, so that the fluidity of the two-component developer was reduced.

<Example 13> In Example 1, except that the carrier 1 was the carrier 14, the same results as in Tables 4, 5 and 5 were obtained.

<Example 14> In Example 1, the procedure was the same as in Example 1, except that the carrier 1 was the carrier 15, and as shown in Tables 4 and 5, the fog and toner scattering were inferior to those of Example 1. It became so. This is probably because the magnesium content in the hydrophobic iron oxide is small, so that the residual magnetic flux density of the carrier is slightly large, the fluidity is reduced, and the fluidity of the two-component developer is reduced.

<Example 15> In Example 1, except that the carrier 1 was the carrier 16, the same results as in Tables 4 and 5 were obtained.

<Example 16> In Example 1, the same operation was performed except that the carrier 1 was the carrier 17, and as shown in Tables 4 and 5, the fog and toner scattering were inferior to those of Example 1. It became so. It is considered that this is because the residual magnetic flux density of the carrier is slightly large because the silicon component inside the hydrophobic iron oxide is small, the fluidity is reduced, and the fluidity of the two-component developer is reduced.

<Comparative Example 2> In Example 1, except that the carrier 1 was the carrier 18, the same operation was performed.
As shown in Tables 4 and 5, all the evaluation items became significantly inferior to Example 1. This is because the magnesium component, silicon component, manganese component, phosphorus component and metal component inside the hydrophobic iron oxide are not added,
This is probably because A / B is large, the residual magnetization of the carrier is large, and the fluidity is poor.

<Comparative Example 3> The procedure of Example 1 was repeated, except that the carrier 1 was the carrier 19;
As shown in Tables 4 and 5, fog and toner scattering were worse than in Example 1. This is because A / B is large, the residual magnetization of the carrier is large, and the fluidity is poor because the amount of the magnesium component added in the hydrophobic iron oxide is small.
It is considered to be.

<Example 17> In Example 1, except that the carrier 1 was the carrier 20, the same results were obtained as shown in Tables 4 and 5, and good results were obtained.

<Comparative Example 4> In Example 1, except that the carrier 1 was the carrier 21, the same operation was performed.
As shown in Tables 4 and 5, fog and toner scattering were significantly inferior to Example 1. This is presumably because the silicon component or magnesium component inside the hydrophobic iron oxide was not added, so that the residual magnetic flux density of the carrier was large and the fluidity was poor.

<Example 18> In Example 1, except that the carrier 1 was the carrier 22, the same results as in Tables 4 and 5 were obtained.

<Embodiment 19> In the same manner as in the embodiment 1 except that the carrier 1 was the carrier 23, as shown in Tables 4 and 5, compared to the embodiment 1, the fog and toner scattering were slightly reduced. Became inferior. This is presumably because the amount of the metal component of the hydrophobic iron oxide added was large, which inhibited the reaction during carrier granulation, increased the SF, and slightly deteriorated the fluidity and the like.

<Example 20> In Example 1, except that the carrier 1 was the carrier 24, similar results were obtained as shown in Tables 4 and 5.

<Examples 21 to 27> In Example 1,
The same operation as in Example 17 was carried out, except that the carrier 1 was the carriers 25 to 31. Good results were obtained.

<Example 28> In Example 1, except that the carrier 1 was the carrier 32, the same operation was carried out, and good results were obtained as shown in Tables 4 and 5.

<Example 29> The procedure of Example 1 was repeated, except that the carrier 1 was the carrier 33. Good results were obtained as shown in Tables 4 and 5.

<Example 30> The procedure of Example 1 was repeated, except that the carrier 1 was the carrier 34. Good results were obtained as shown in Tables 4 and 5.

<Example 31> In Example 1, except that the carrier 1 was the carrier 35, the same results were obtained. As shown in Tables 4 and 5, good results were obtained.

<Example 32> In Example 1, except that the carrier 1 was the carrier 36, the same operation was carried out. As shown in Tables 4 and 5, the fog and toner scattering were slightly different from those of Example 1. Became inferior. This is considered to be because the surface of the carrier was not treated with aminopropyltrimethoxysilane, and the tribo-giving ability under high humidity was weak, so that the carrier slightly deteriorated.

<Examples 33 to 35> In Example 1,
When the same procedure was carried out except that the toner 1 was the toners 2 to 4, good results were obtained as shown in Tables 4 and 5.

<Examples 36 and 37> In Example 1,
When the same procedure was performed except that the carrier 1 was the carriers 37 and 38, good results were obtained as shown in Tables 4 and 5.

<Comparative Example 5> In Example 1, except that the carrier 1 was the carrier 39, the same operation was performed.
As shown in Tables 4 and 5, the whole image was rough.
This is presumed to be due to the fact that the carrier has a small particle diameter, so that the carrier easily adheres to the electrostatic image carrier and is easily damaged.

<Embodiments 38 and 39> In Embodiment 1,
When the same procedure was performed except that the carrier 1 was the carriers 40 and 41, good results were obtained as shown in Tables 4 and 5.

<Comparative Example 6> In Example 1, except that the carrier 1 was the carrier 42, the same operation was performed.
As shown in Tables 4 and 5, fog and toner scattering were inferior to Example 1. This is presumably because the fluidity of the carrier was poor, so that the charge-imparting ability to the toner was deteriorated.

<Example 40> The procedure of Example 1 was repeated, except that the replenishing developer was not replenished and the developer was not discharged. Good results were obtained as shown in Tables 4 and 5.

[0297]

[Table 4]

[0298]

[Table 5]

[0299]

The carrier of the present invention has a low residual magnetization,
Further, since the fluidity is high, the occurrence of fog and toner scattering is prevented or suppressed, and a good image can be obtained for a long time. Further, since the saturation magnetization of the carrier is high, the carrier does not adhere to the electrostatic image carrier, and a high-quality toner image can be formed for a long period of time.

Further, since the carrier of the present invention has a stable charge-imparting ability to the toner without being affected by temperature and humidity, a high-definition color image with high image quality and density can be obtained for a long period of time. .

[Brief description of the drawings]

FIG. 1 is a view showing an embodiment of an image forming apparatus provided with a rotary rotation type developing device using a replenishing developer of the present invention.

FIG. 2 is a view showing one embodiment of the developing device of FIG. 1;

FIG. 3 is an enlarged configuration diagram for explaining the developing device of FIG. 1;

FIG. 4 is a view showing one embodiment of the developing device of FIG. 3;

FIG. 5 is a view showing an embodiment of an image forming apparatus provided with a developing device used in the cleanerless system of the present invention.

FIG. 6 is a view showing one embodiment of a full-color image forming apparatus of the present invention.

FIG. 7 shows a bias having a discontinuous alternating electric field of a developing bias used in the image forming apparatus used in FIG.

FIG. 8 shows a schematic diagram of a cell used for measuring volume resistance.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 photosensitive drum 2, 3, 4, 5 developing device 6 developing sleeve 7 regulating blade 8 magnet roller 9 replenishment developer storage device 10, 11 developer transport screw 12 transfer material 13 developing device 14 exposure means 15 roller charging device 17 developing tank 18, 23 Cleaning device 19, 22, 33 Static elimination device 20 Conveyance guide buzzing member 21 Fixing device 24 Transfer drum 25 Registration roller 26, 27 Feed tray 28, 29 Feed roller 30 Opposite roller 31 Transfer device 32 Suction device 34 Developer outlet 35 Developer Collection Port 37 Developer Primary Storage Unit 38 Developer Collection Auger 40 Electrostatic Image Carrier (Photosensitive Drum) 41 Developer Carrier (Development Sleeve) 42 Magnet Roller 43 Developing Devices 46, 47 Developer Conveying Screw 45 Regulation Blade 47 Partition wall 48 Supply Developer 49 Developer 49a Toner 49b Carrier 50 Supply port 51 Magnet roller 52 Transport sleeve 53 Magnetic particles 54 Laser light 55 Transfer material (recording material) 56 Bias applying means 57 Transfer blade 58 Toner density detection sensor 61a Photosensitive drum 62a Primary charger 63a Developing device 64a Transfer blade 65a Replenishing developer 67a Laser beam 68 Transfer material carrier 69 Separating charger 70 Fixing device 71 Fixing roller 72 Pressure roller 73 Web 75, 76 Heating means 79 Transfer belt cleaning device 80 Drive roller 81 Belt Driven roller 82 belt 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 12 8 Guide ring

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshi ▲ Saki ▼ Kazumi F-term in Canon Inc. 3-30-2 Shimomaruko, Ota-ku, Tokyo (reference) 2H005 AA01 AA06 AA08 AA21 BA03 BA06 BA11 BA15 CA04 CA12 CA14 CA26 CB03 CB07 CB10 CB13 DA05 EA02 EA05 EA07 EA10 FA02

Claims (22)

[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 fluidity after magnetization is A, and the fluidity after demagnetization is B. A / B ≦ 1.5, wherein a magnetic fine particle-dispersed resin carrier is provided. 2. The carrier according to claim 1, wherein the ratio A / B satisfies A / B ≦ 1.2. 3. The carrier according to claim 1, wherein the ratio A / B satisfies A / B ≦ 1.1. 4. The carrier according to claim 1, wherein the magnetic fine particles contain at least one of a magnesium component, a silicon component, a manganese component, and a phosphorus component. 5. The magnetic fine particles contain at least one of a magnesium component, a silicon component, a manganese component, and a phosphorus component, and have a total amount of 0.0 with respect to Fe in terms of each element.
The carrier according to any one of claims 1 to 3, wherein the content is 3 to 5.0% by mass. 6. The magnetic fine particle-dispersed resin carrier according to claim 1, wherein a residual magnetization σr (Am ² / kg) and a volume average particle diameter d (μm) satisfy the following expression. The carrier described in. 1.0 ≦ d / σr <30.0 7. The d / σr is 5.1 ≦ d / σr ≦ 1.
The carrier according to claim 6, which satisfies 2.3. 8. The magnetic fine particles include zinc, copper, nickel,
It contains at least one metal element selected from the group consisting of cobalt, aluminum, tin, titanium and zirconium, and the total amount of these components in terms of each metal element is 0.01 to 3.0 with respect to Fe. Mass%
And the above metal component and magnesium component, silicon component,
The carrier according to any one of claims 1 to 7, wherein the total amount of surface exposure in terms of each element of the manganese component and the phosphorus component is 0.01 to 1.5 mass% with respect to Fe. 9. In the magnetic fine particles, the total amount of the magnesium component, the silicon component, the manganese component, and the surface exposure of the phosphorus component is 0.01 to 0.5 mass% in terms of each element.
The carrier according to claim 8, wherein: 10. The magnetic fine particles contain a magnesium component and at least one selected from the group consisting of a silicon component, a manganese component and a phosphorus component,
The carrier according to any one of claims 1 to 9, wherein a ratio based on mass in terms of each element satisfies the following expression. Magnesium element: (total amount of silicon element, manganese element and phosphorus element) = 1: 9 to 9: 1 11. The carrier has a residual magnetization of 7.5 Am ^2.
/ Kg or less. 12. The carrier has a residual magnetization of 2.9 to 6.
2. The composition according to claim 1, wherein the amount is 9 Am ² / kg.
The carrier according to any one of 0. 13. The carrier according to claim 1, wherein said magnetic fine particles are magnetite particles. 14. The carrier according to claim 1, wherein the magnetic fine particles have been subjected to lipophilic treatment with a lipophilic treatment agent. 15. The carrier according to claim 14, wherein the lipophilic treatment agent is a silane coupling agent. 16. The carrier according to claim 1, wherein the carrier contains the magnetite and a nonmagnetic inorganic compound. 17. The carrier according to claim 1, wherein the composite particles are obtained by a polymerization method. 18. A two-component developer having at least a toner having toner particles and an external additive and a magnetic fine particle-dispersed carrier, wherein the toner has a weight average particle diameter of 3.0 to 9.0 μm. A toner containing 40% by mass or less of a wax, wherein the carrier is formed of composite particles having at least magnetic fine particles and a binder resin, and has a fluidity A after magnetization and a fluidity after demagnetization. Wherein B is a magnetic fine particle-dispersed resin carrier satisfying A / B ≦ 1.5. 19. The external additive has a number average particle size of 3 to 100 n.
19. The two-component developer according to claim 18, wherein m is m. 20. The two-component developer according to claim 18, wherein the carrier is the carrier according to any one of claims 2 to 17. 21. A replenishing developer for use in a developing method in which development is performed while replenishing a replenishing developer, wherein the developer is contained at a ratio of 2 to 50 parts by mass of toner to 1 part by mass of a carrier. Wherein the toner has a weight average particle diameter of 3.0 to 9.0 μm and contains 40% by mass or less of wax, and the carrier is a composite particle having at least magnetic fine particles and a binder resin. It is a magnetic fine particle-dispersed resin carrier that satisfies A / B ≦ 1.5 when the fluidity after magnetization is A and the fluidity after demagnetization is B. Replenishing developer. 22. The replenishing developer according to claim 21, wherein the carrier is the carrier according to any one of claims 2 to 17.