JP6711626B2 - Magnetic carrier, two-component developer, image forming method, replenishment developer - Google Patents

Description

The present invention relates to a magnetic carrier used in an image forming method for visualizing an electrostatic charge image by using electrophotography.

In recent years, copying machines and printers have been rigorously pursued to be faster and more reliable. On the other hand, the main body of the copying apparatus has come to be composed of simpler elements in various respects. As a result, the performance required of the developer has become higher, and if the improvement in the performance of the developer cannot be achieved, a better copying apparatus main body cannot be established.
Among the methods of developing an electrostatic latent image formed on an electrostatic latent image carrier with a toner, the two-component developing method using a two-component developer in which the toner is mixed with a magnetic carrier has a high image quality. It is preferably used for a full-color copying machine or printer that requires In the two-component developing method, the magnetic carrier imparts an appropriate amount of positive or negative charge to the toner by triboelectrification, and carries the toner on the surface of the magnetic carrier by the electrostatic attraction of the triboelectrification.
There are various characteristics required for the magnetic carrier and toner constituting the above two-component developer, but as the characteristics which are particularly important for the magnetic carrier, suitable charge imparting property, pressure resistance against alternating voltage, and impact resistance are given. Properties, abrasion resistance, spent resistance, developability and the like.
The magnetic carrier has characteristics such as powder characteristics, electric characteristics, and magnetic characteristics, and each performance suited to the developing system is required. In recent years, a carrier in which a core material (core material) is coated with a coating resin (coating material) has been widely used in order to improve environmental stability and durability.
For example, it has been proposed that the core material has at least two or more resin coating layers, the outermost layer contains carbon black, and the resin coating layer closest to the core material contains a metal compound and carbon black. Reference 1). As a result, even if used for a long period of time, there is no leakage of electric charges on the surface, and a stable charging ability is maintained.
Further, it has been proposed that the outermost layer contains carbon black and the resin coating layer closest to the core material contains an Al-containing compound (Patent Document 2). This suppresses the carrier adhesion to the image and suppresses the occurrence of white spots in the image portion.
Further, it has been proposed that the intermediate resin layer has at least one metal oxide of aluminum, magnesium, zinc, and lead, and the outermost coating resin layer is copolymerized with a monomer having a hydroxyl group and a carboxyl group (Patent Reference 3). As a result, the negative charge maintaining property is improved, the coating film strength is strong, the peeling of the coating resin is prevented, and the life is extended.
However, in recent years, the burden on the developer in the developing device tends to increase due to a decrease in the developer capacity accompanying the downsizing of the developing device and an increase in the developer stirring speed due to an increase in the output speed. As a result, especially under a high temperature and high humidity environment, the water-crosslinking force acting between the magnetic carrier and the toner causes the spent of the toner and the external additive to progress on the surface of the magnetic carrier, thereby deteriorating the charge imparting property of the magnetic carrier. . Further, moisture adsorption to the surface of the magnetic carrier progresses and the strength of the magnetic carrier coating resin is temporarily reduced, so that the magnetic carrier coating resin is peeled off or scraped off, resulting in a problem that the charge imparting ability is lowered. There is an urgent need to develop a magnetic carrier that satisfies these requirements, a two-component developer, and an image forming method using the same.

JP, 2009-217059, A JP, 2009-217055, A JP-A-8-6309

An object of the present invention is to provide a magnetic carrier that solves the above problems. Specifically, even when used for a long period of time in a high temperature and high humidity environment, it suppresses abrasion and peeling of the resin coating layer, maintains a stable charge imparting ability, and prevents fluctuations from a high temperature and high humidity environment to a room temperature and low humidity environment. And to provide a magnetic carrier with improved image density and tint stability.

In order to achieve the above object, the carrier of the present invention has a magnetic material-dispersed resin carrier core material having a magnetic material and a binder resin, and a resin coating layer on the surface of the magnetic material-dispersed resin carrier core material. A magnetic carrier,
The resin coating layer has a surface resin layer, a resin composition present between the magnetic material-dispersed resin carrier core material and the surface resin layer,
The resin composition,
(I) a resin,
(Ii) From oxide particles of a metal element having an ester group and/or a carboxyl group on the surface, silica particles having an ester group and/or a carboxyl group on the surface , and carbon black having an ester group and/or a carboxyl group on the surface is selected from the group consisting of containing and one or more kinds of particles child,
The particles of (ii) have a methanol wettability of 85% or less and a functional group concentration of the ester group and/or the carboxyl group of 20% or more.
The present invention relates to a magnetic carrier.
The present invention also relates to a magnetic carrier, wherein the hydrophilically treated oxide particles of a metal element are one kind or two or more kinds selected from TiO ₂ , Al ₂ O ₃ , MgO, and SrTiO ₃ .
The present invention also relates to the magnetic carrier, wherein the volume average diameter of the primary particles of the hydrophilically treated particles is 10 nm or more and 1000 nm or less.
The present invention also relates to a magnetic carrier, wherein the resin composition contains 1.0 part by mass or more and 20.0 parts by mass or less of the hydrophilically treated particles, when the resin is 100 parts by mass.
The present invention also relates to the magnetic carrier, wherein the resin coating layer has a thickness of 0.01 μm or more and 4.00 μm or less.
The present invention also relates to a magnetic carrier, wherein the resin of the resin composition is a polymer obtained by polymerizing a monomer containing an acrylic acid ester monomer or a methacrylic acid ester monomer, and/or a thermosetting silicone resin.
The present invention also relates to a magnetic carrier in which the resin coating layer contains a polymer obtained by polymerizing a monomer containing an acrylic acid ester monomer or a methacrylic acid ester monomer.
Further, the present invention provides the moisture content (A)% by mass of the magnetic carrier when left in an environment of a temperature of 30° C. and a humidity of 80% for 24 hours, and in an environment of a temperature of 30° C. and a humidity of 80% for 24 hours. After that, when the magnetic carrier is allowed to stand in an environment of a temperature of 23° C. and a humidity of 5% for 24 hours, the moisture content change (AB) from the moisture content (B) mass% of the magnetic carrier is 0.80 mass% or less. Regarding career.
The present invention also relates to a two-component developer containing a toner having toner particles containing a binder resin, a colorant and a release agent, and the magnetic carrier.
The present invention also provides a charging step of charging an electrostatic latent image carrier, an electrostatic latent image forming step of forming an electrostatic latent image on the surface of the electrostatic latent image carrier, and the electrostatic latent image A developing step of developing with a component type developer to form a toner image, a transferring step of transferring the toner image to a transfer material with or without an intermediate transfer member, and the transferred toner image The present invention relates to an image forming method having a fixing step of fixing to a transfer material.
The present invention also provides a charging step of charging the electrostatic latent image carrier, an electrostatic latent image forming step of forming an electrostatic latent image on the surface of the electrostatic latent image carrier, and the electrostatic latent image in a developing device. A developing step of developing with a two-component developer to form a toner image, a transfer step of transferring the toner image to a transfer material with or without an intermediate transfer member, and a transfer material of the transferred toner image. In the fixing device, the replenishment developer is replenished to the developing device according to the reduction of the toner concentration of the two-component developer in the developing device, and the excess magnetic carrier in the developing device is A replenishing developer for use in an image forming method that is discharged from a developing device when necessary,
The replenishment developer contains a replenishment magnetic carrier and a toner having toner particles containing a binder resin, a colorant and a release agent,
The replenishment developer relates to a replenishment developer containing 2 parts by mass or more and 50 parts by mass or less of the toner with respect to 1 part by mass of the replenishment magnetic carrier.
The present invention also provides a charging step of charging the electrostatic latent image carrier, an electrostatic latent image forming step of forming an electrostatic latent image on the surface of the electrostatic latent image carrier, and the electrostatic latent image in a developing device. A developing step of developing with a two-component developer to form a toner image, a transfer step of transferring the toner image to a transfer material with or without an intermediate transfer member, and a transfer material of the transferred toner image. In the fixing device, the replenishment developer is replenished to the developing device according to the reduction of the toner concentration of the two-component developer in the developing device, and the excess magnetic carrier in the developing device is An image forming method of discharging from a developing device when necessary,
The replenishment developer contains a replenishment magnetic carrier and a toner having toner particles containing a binder resin, a colorant and a release agent,
The replenishment developer relates to an image forming method in which the toner is contained in an amount of 2 parts by mass or more and 50 parts by mass or less based on 1 part by mass of the replenishment magnetic carrier.

By using the carrier of the present invention, even when used for a long period of time in a high temperature and high humidity environment, the resin coating layer has excellent abrasion resistance, maintains a stable charge imparting ability, and changes from a high temperature and high humidity environment to a room temperature and low humidity environment. It is possible to obtain a magnetic carrier having improved image density and tint stability against variations.

FIG. 3 is a schematic view of an image forming apparatus used in the present invention. FIG. 3 is a schematic view of an image forming apparatus used in the present invention. It is a schematic sectional drawing of the apparatus which measures the specific resistance of the magnetic substance dispersion type resin carrier core material particle. (A) is a figure in a blank state before putting a sample, and (b) is a figure showing a state when putting a sample.

Hereinafter, embodiments of the present invention will be described.

<Career>
The magnetic carrier of the present invention is a magnetic substance-dispersed resin carrier core material having a magnetic substance and a binder resin, and a magnetic carrier having a resin coating layer on the surface of the magnetic substance-dispersed resin carrier core material,
The resin coating layer has a surface resin layer, a resin composition present between the magnetic material-dispersed resin carrier core material and the surface resin layer,
The resin composition,
(I) a resin,
(Ii) Contains one or more hydrophilically treated particles selected from hydrophilically treated metal element oxide particles, hydrophilically treated silica particles, and hydrophilically treated carbon black. To do. In the following description, the layer of the resin composition existing between the carrier core material and the surface resin is referred to as an intermediate resin layer.

The hydrophilicity-treated particles used in the present invention have a methanol wettability of preferably 85% or less, more preferably 80% or less. The methanol wettability refers to the concentration of methanol in which the total amount of hydrophilically treated particles is suspended in a solution in a wettability test with a methanol/water mixed solvent.

Within this range, the carboxy group or ester group present on the particle surface forms a hydrogen bond with the water molecule in the surface resin layer, and the interaction improves the adhesion between the intermediate resin layer and the surface resin layer. To do. Even when the resin coating layer is used for a long period of time in a high temperature and high humidity environment, abrasion and peeling of the resin coating layer are suppressed, and stable charge imparting ability can be maintained. That is, since the charging characteristics of the toner are stable for a long period of time, the variation in color tone of mixed colors, the ruggedness (dot reproducibility), the developability, and the change in gradation are stable. Further, carrier adhesion in a solid image, which appears remarkably when the electric charge of the magnetic carrier itself is small, tends not to be easily exhibited. Further, since the water molecules in the surface resin layer are retained, the moisture content of the magnetic carrier does not easily change even when the environment changes. For this reason, the amount of water, which greatly affects the charging characteristics of the carrier, is unlikely to change with a change from a high temperature/high humidity environment to a room temperature/low humidity environment. This improves the white spots and the change in gradation when the environment changes.

On the other hand, when the methanol wettability exceeds 85%, the hydrophilic treatment is insufficient, and the interaction of hydrogen bond between the carboxy group or ester group existing on the particle surface and the water molecule in the surface resin layer is hard to be expressed. Therefore, it becomes difficult to improve the adhesion between the intermediate resin layer and the surface resin layer. When the resin coating layer is used for a long period of time in a high temperature and high humidity environment, the resin coating layer is scraped or peeled off, so that the stable charge imparting ability cannot be maintained easily. That is, since the charging characteristics of the toner cannot be maintained for a long period of time, variations in color tone of mixed colors, roughness (dot reproducibility), developability, and gradation change are likely to deteriorate. Further, carrier adhesion in a solid image, which appears remarkably when the electric charge of the magnetic carrier itself is small, tends to be deteriorated. Further, since it is difficult to retain water molecules in the surface resin layer, the water content of the magnetic carrier changes greatly when the environment changes. For this reason, the change in the amount of water, which greatly affects the charging characteristics of the magnetic carrier, is large in response to the change from the high temperature and high humidity environment to the room temperature and low humidity environment, and therefore the environmental change is large and stable charge imparting ability can be maintained. Can not. As a result, white spots and changes in gradation when the environment changes are likely to worsen.

The hydrophilically treated particles used in the present invention have an ester group or a carboxyl group on the surface thereof, and the functional group concentration of the ester group and/or the carboxyl group is preferably 20% or more, more preferably Is 30% or more. The functional group concentration refers to the ratio of an ester group or a carboxyl group to an element derived from particles in X-ray photoelectron spectroscopy (XPS) measurement.

Within this range, the carboxy group or ester group present on the particle surface and the water molecule in the surface resin layer form a hydrogen bond, and the interaction improves the adhesion between the intermediate resin layer and the surface resin layer. To do. When an acrylic resin is used in the resin coating layer, a π-π interaction occurs between the π bond in the acrylic resin and the carboxyl group or ester group present on the particle surface, and the intermediate resin layer and the surface coating layer are formed. Improves the adhesion. Further, the interaction between the particle surface functional group and the hydroxy group on the surface of the magnetic material-dispersed resin carrier core material particles improves the adhesion between the intermediate resin layer and the magnetic material-dispersed resin carrier core material particles. As a result, even if the resin coating layer is used for a long period of time in a high temperature and high humidity environment, the resin coating layer is prevented from being scraped or peeled off, so that a stable charge imparting ability can be maintained. That is, since the charging characteristics of the toner are stable for a long period of time, the variation in color tone of mixed colors, the ruggedness (dot reproducibility), the developability, and the change in gradation are stable. Further, carrier adhesion in a solid image, which appears remarkably when the electric charge of the magnetic carrier itself is small, tends not to be easily exhibited. Further, since the water molecules in the surface resin layer are retained, the moisture content of the magnetic carrier does not easily change even when the environment changes. Therefore, the amount of water, which greatly affects the charging characteristics of the magnetic carrier, is unlikely to change with a change from a high-temperature high-humidity environment to a room-temperature low-humidity environment. This improves the white spots and the change in gradation when the environment changes.

On the other hand, when it is less than 20%, the number of carboxy groups or ester groups existing on the particle surface is small, and thus the interaction with water molecules in the surface resin layer becomes small. As a result, the adhesion between the intermediate resin layer and the surface resin layer is reduced. When an acrylic resin is used in the resin coating layer, the π-π interaction between the π bond in the acrylic resin and the carboxy group or ester group present on the particle surface becomes small, and the intermediate resin layer and the surface resin layer Adhesion with is reduced. Further, the interaction between the functional groups on the particle surface and the hydroxy groups on the surface of the magnetic material-dispersed resin carrier core material is reduced, and the adhesion between the intermediate resin layer and the magnetic material-dispersed resin carrier core material particles is reduced. As a result, even when the resin coating layer is used for a long period of time in a high temperature and high humidity environment, the resin coating layer is scraped or peeled off, so that the stable charge imparting ability cannot be maintained. In other words, the charging characteristics of the toner are not stable over a long period of time, and it is easy to reduce the tint variation of mixed colors, ruggedness (dot reproducibility), developability, and gradation stability, and further reduce the charge of the magnetic carrier itself. However, carrier adhesion is likely to occur. Further, it is difficult to retain water molecules in the surface resin layer, and the change in the water content of the magnetic carrier becomes large when the environment changes. For this reason, the amount of water that greatly affects the charging characteristics of the magnetic carrier changes due to the change from the high temperature and high humidity environment to the room temperature and low humidity environment, and the stability of the charge imparting ability tends to be reduced, resulting in a change in the environment. White spots and changes in gradation tend to be exacerbated.

The hydrophilically treated metal oxide particles used in the present invention are preferably one or more selected from TiO ₂ , AlO ₃ , MgO and SrTiO ₃ .

When particles other than the above are used, the water content of the particles themselves causes a large change in the water content of the carrier. Therefore, the amount of water, which greatly affects the charging characteristics of the carrier, changes with the change from the high temperature/high humidity environment to the room temperature/low humidity environment, and the stability of the charge imparting ability is likely to decrease. As a result, white spots and gradation changes when the environment changes are exacerbated. In addition, since it does not have a proper resistance range as a carrier and cannot have a stable charge imparting ability, it is not possible to obtain color fluctuation of mixed colors, roughness (dot reproducibility), developability, gradation stability, and carrier adhesion. It is easy to get worse. Further, it is not preferable to use organic fine particles in the present invention. It is considered that when a thermosetting resin is used as the organic fine particles, the resin molecular chains are randomly entangled with each other due to the manufacturing method, and the functional group exhibiting hydrophilicity is not oriented on the resin surface layer. Therefore, the effects of the present invention, such as durability due to improved adhesion and environmental stability, are difficult to be exhibited. When a thermoplastic resin is used, a part of the resin may be dissolved in the resin solution, a uniform coat layer cannot be formed, and the effect of the present invention is also difficult to obtain.

The volume average diameter of the primary particles of the hydrophilically treated particles used in the present invention is preferably 10 nm or more and 1000 nm or less.

When the particle size is less than 10 nm, the particles are likely to aggregate with each other and are dispersed in the intermediate resin layer in the state of aggregated mass. For this reason, the aggregates are likely to be desorbed from the intermediate resin layer, and the charge imparting ability is deteriorated at that portion. That is, since the charging characteristics of the toner cannot be maintained for a long period of time, variations in color tone of mixed colors, roughness (dot reproducibility), developability, and gradation change are likely to deteriorate. Further, carrier adhesion in a solid image, which appears remarkably when the electric charge of the magnetic carrier itself is small, tends to be deteriorated. Further, since it is difficult to stably hold water molecules in the surface resin layer due to desorption of aggregates, the water content of the magnetic carrier changes greatly when the environment changes. Therefore, when the environment changes from a high temperature and high humidity environment to a room temperature and low humidity environment, the change in the amount of water, which greatly affects the charging characteristics of the magnetic carrier, becomes large, and the environmental change becomes large, and stable charge imparting ability cannot be maintained. .. As a result, white spots and changes in gradation are easily deteriorated when the environment changes.

If it is larger than 1000 nm, the particles are likely to be detached from the intermediate resin layer, and the charge imparting ability is lowered. That is, since the charging characteristics of the toner cannot be maintained for a long period of time, variations in color tone of mixed colors, roughness (dot reproducibility), developability, and gradation change are likely to deteriorate. Further, carrier adhesion in a solid image, which appears remarkably when the electric charge of the magnetic carrier itself is small, tends to be deteriorated. Further, since it is difficult to stably hold water molecules in the surface resin layer due to desorption of aggregates, the water content of the magnetic carrier changes greatly when the environment changes. Therefore, when the environment changes from a high temperature and high humidity environment to a room temperature and low humidity environment, the change in the amount of water, which greatly affects the charging characteristics of the magnetic carrier, becomes large, and the environmental change becomes large, and stable charge imparting ability cannot be maintained. .. As a result, white spots and changes in gradation are easily deteriorated when the environment changes.

It is preferable that the resin composition used in the present invention contains 1.0 part by mass or more and 20.0 parts by mass or less of the hydrophilically treated particles, when the resin is 100 parts by mass.

When the amount is less than 1.0 part by mass, the absolute amount of the particle surface functional group interacting with water molecules in the surface resin layer is small, and therefore the adhesiveness between the intermediate resin layer and the surface resin layer is not improved. As a result, when the resin coating layer is used for a long period of time in a high temperature and high humidity environment, the resin coating layer is scraped or peeled off, and the stable charge imparting ability cannot be maintained. That is, since the charging characteristics of the toner cannot be maintained for a long period of time, variations in color tone of mixed colors, roughness (dot reproducibility), developability, and gradation change are likely to deteriorate. Further, carrier adhesion in a solid image, which appears remarkably when the electric charge of the magnetic carrier itself is small, tends to be deteriorated. Further, since the effect of retaining water molecules in the surface resin layer is lost, the change in the water content of the magnetic carrier increases when the environment changes. As a result, the change in the amount of water, which greatly affects the charging characteristics of the magnetic carrier, is large in response to the change from the high temperature/high humidity environment to the room temperature/low humidity environment. Can not. As a result, white spots and changes in gradation when the environment changes are likely to worsen.

On the other hand, when the amount is more than 20.0 parts by mass, the absolute amount of the particle surface functional group that interacts with the water molecules of the surface resin layer increases, and it is considered that the water molecules are more attracted toward the intermediate resin layer. As a result, water molecules near the outermost surface layer of the surface resin layer are reduced, and water molecules in the air are adsorbed to increase the water content of the entire resin. As a result, when the resin coating layer is used for a long period of time in a high temperature and high humidity environment, the resin coating layer is scraped or peeled off, and the stable charge imparting ability cannot be maintained. That is, since the charging characteristics of the toner cannot be maintained for a long period of time, variations in color tone of mixed colors, roughness (dot reproducibility), developability, and gradation change are likely to deteriorate. Further, carrier adhesion in a solid image, which appears remarkably when the electric charge of the magnetic carrier itself is small, tends to be deteriorated. In addition, the increase in the water content of the magnetic carrier causes a large change in the water content of the magnetic carrier when the environment changes. As a result, the change in the amount of water, which greatly affects the charging characteristics of the magnetic carrier, is large in response to the change from the high temperature/high humidity environment to the room temperature/low humidity environment. Can not. As a result, white spots and changes in gradation when the environment changes are likely to worsen.

The thickness of the surface resin layer used in the present invention is preferably 0.01 μm or more and 4.00 μm or less.

When the thickness of the surface resin layer has a region of less than 0.01 μm, it is affected by the hydrophilically treated particles, and the moisture content change of the magnetic carrier increases when the environment changes. As a result, the change in the amount of water, which greatly affects the charging characteristics of the magnetic carrier, is large in response to the change from the high temperature/high humidity environment to the room temperature/low humidity environment. Can not. As a result, white spots and changes in gradation when the environment changes are likely to worsen.

On the other hand, when the thickness of the surface resin layer has a region of more than 4.0 μm, the moisture content of the surface resin layer is affected by desorption of water, and the moisture content of the magnetic carrier changes when the environment changes. As a result, the change in the amount of water, which greatly affects the charging characteristics of the magnetic carrier, is large in response to the change from the high temperature/high humidity environment to the room temperature/low humidity environment. Can not. As a result, white spots and changes in gradation when the environment changes are likely to worsen.

The magnetic carrier of the present invention has a moisture content (A)% by mass of the magnetic carrier when left for 24 hours in an environment of a temperature of 30° C. and a humidity of 80%, and in an environment of a temperature of 30° C. and a humidity of 80% for 24 hours. After being left for 24 hours in an environment of a temperature of 23° C. and a humidity of 5%, a change in water content (AB) from the water content (B) of the magnetic carrier (B) is 0.80 mass% or less. Preferably.

If the change in water content exceeds 0.80% by mass, the change in the amount of water, which greatly affects the charging characteristics of the magnetic carrier, is large with respect to the change from the high temperature/high humidity environment to the room temperature/low humidity environment, and thus the environmental change is large. Therefore, it is impossible to maintain a stable charge imparting ability. As a result, white spots and changes in gradation when the environment changes are likely to worsen.

Next, the hydrophilic treatment method for particles of the present invention will be described.

<Hydrophilic treatment method of particles>
The oxide particles of a metal element, silica particles, and carbon black contained in the filler of the present invention require that the surface of the particles be hydrophilic.

As one of hydrophilic treatment methods, for example, for neutral or basic carbon black or acidic carbon black, a hydrophilic group can be introduced by performing an oxidation treatment.

Specific examples of the oxidation treatment method include an air contact oxidation method and a gas phase oxidation method by a reaction with nitrogen oxide and ozone. Further, a liquid phase oxidation method and the like using an oxidizing agent such as nitric acid, potassium permanganate, potassium dichromate, acetic acid, perchloric acid, hypohalogenated hydrochloric acid, hydrogen peroxide, bromine aqueous solution, ozone aqueous solution and the like can be mentioned. .. In addition, the same can be applied to carbon black whose surface is oxidized by plasma treatment or the like.

There are various methods for introducing a hydrophilic group by oxidizing the particle surface as described above. For example, the following method is preferable. When the liquid phase oxidation method is carried out, the hydrophilically treated particles can be obtained by putting carbon black in a suitable container, adding an aqueous solution of nitric acid and refluxing, followed by washing and drying. When performing the gas-phase oxidation method, each particle is placed in a cylindrical ozonizer, ozone is generated by the ozone generator, and the particle is exposed to an ozone atmosphere, whereby hydrophilically treated particles can be obtained. it can.

In addition, as one of the hydrophilic treatment methods, for example, by introducing a hydrophilic esterifying agent or carboxylation treatment of lower fatty acid, the hydrophilic ester group or carboxyl group of lower fatty acid is introduced into the hydroxy group on the particle surface. There is a method of doing.

Specific examples of the hydrophilic esterifying agent include acetic anhydride, acetic acid chloride, acetic acid, propionic anhydride, succinic anhydride, maleic anhydride, phthalic anhydride, polyglycerin fatty acid ester, and alginic acid. Two or more kinds of these hydrophilic esterifying agents or carboxylating agents for lower fatty acids may be mixed and used.

As the hydrophilic treatment method as described above, various methods of introducing a hydrophilic ester group or a carboxyl group of a lower fatty acid to a hydroxy group on the particle surface by performing a hydrophilic esterification agent or a carboxylation treatment of a lower fatty acid Exists. For example, it is preferable to use the following method. After putting each particle species in a suitable container and setting the system under a nitrogen atmosphere, anhydrous toluene, triethylamine, dimethylaminopyridine, and acetic anhydride are added and reacted at room temperature to obtain chemically modified particles. After that, put the obtained chemically modified particles in an appropriate container, add methanol and calcium carbonate, and react at room temperature. After that, carry out a reaction termination treatment, and wash and dry the particles that have been hydrophilically treated. Obtainable.

Next, a method for producing the magnetic material-dispersed resin carrier core material particles of the present invention will be described.

<Method for producing magnetic material-dispersed resin carrier core material particles>
The magnetic carrier core used in the present invention may be produced by either a kneading pulverization method or a polymerization method as long as it is a magnetic material-dispersed resin carrier core material particle in which a magnetic material is dispersed in a binder resin.

The magnetic particles used in the present invention include magnetic inorganic compound particles and non-magnetic inorganic compound particles. As the magnetic inorganic compound particles, magnetite particle powder, maghemite particle powder, magnetic iron oxide containing one or more kinds of oxides of silicon, hydroxides of silicon, oxides of aluminum, and hydroxides of aluminum in these powders. Object powder, various types such as barium, strontium or barium-strontium-containing magnetoplumbite ferrite powder, spinel ferrite powder containing one or more selected from manganese, nickel, zinc, lithium and magnesium Magnetic iron compound particle powder can be used. Among these, magnetic iron oxide particle powder such as magnetite particle powder can be preferably used. The non-magnetic inorganic compound particles powder, non-magnetic iron oxide particles powder such as hematite particles powder, non-magnetic ferric hydroxide particles powder such as goethite particles powder, titanium oxide particles powder, silica particles powder, talc particles powder, Alumina particle powder, barium sulfate particle powder, barium carbonate particle powder, cadmium yellow particle powder, calcium carbonate particle powder, and zinc white particle powder can be used. Among these, non-magnetic iron oxide particle powder can be preferably used.

The magnetic material can be manufactured by a conventionally known manufacturing method such as a wet method or a dry method. Specifically, the manufacturing method is as follows. In a reaction tank substituted with nitrogen gas, an aqueous solution of alkali hydroxide having a concentration of 2 mol/L or more and 5 mol/L or less and a concentration of 0.5 mol/L or more and 2.0 mol/L or less. The following iron sulfate aqueous solution and zinc sulfate aqueous solution were added so that the molar ratio of alkali hydroxide and iron sulfate (the number of moles of alkali hydroxide/the number of moles of iron sulfate) was 1.0 or more and 5.0 or less. To prepare a mixed solution. Then, additional alkali hydroxide is added to obtain the desired pH. While maintaining the temperature of the mixed solution at 70° C. or higher and 100° C. or lower, stirring and mixing is performed for 7 hours or more and 15 hours or less while blowing an oxidizing gas (air) into the reaction tank to generate magnetite. Further, the mixed solution containing the generated magnetite is filtered, washed with water, dried and crushed to obtain magnetite. The viscosity of the reaction slurry can be controlled by adjusting the concentration of the iron sulfate aqueous solution added to the mixed solution, and the particle size distribution of the produced magnetite can be adjusted. Further, the iron sulfate aqueous solution may contain divalent metal ions such as Zn ²⁺ , Mn ²⁺ , Ni ²⁺ , Cr ²⁺ or Cu ²⁺ . Examples of the divalent metal ion source include sulfates, chlorides and nitrates thereof. Further, SiO ₂ may be contained if necessary, and silicate is used as a raw material.

Further, the magnetic carrier of the present invention may contain a dielectric substance. By containing the dielectric substance, the developability is improved and a stable image can be provided for a long period of time. Examples of the dielectric substance include titanium oxide, titanate and zirconate. Specific examples include barium titanate, strontium titanate, potassium titanate, magnesium titanate, lead titanate, titanium dioxide, barium zirconate, calcium zirconate, and lead zirconate.

Examples of the binder resin used in the present invention include resins such as vinyl resin, polyester resin, epoxy resin, phenol resin, urea resin, polyurethane resin, polyimide resin, cellulose resin, silicone resin, acrylic resin and polyether resin. .. The resin may be one kind or a mixed resin of two or more kinds. In particular, phenol resin is preferable from the viewpoint of increasing the strength of the carrier core so as to retain a relatively large magnetic substance. In order to increase the magnetic force of the carrier core and control the specific resistance, the amount of magnetic material is increased. Specifically, in the case of magnetite particles, it is preferable to add 80% by mass or more and 90% by mass or less to the carrier core.

Phenol, which is an aqueous monomer, and aldehyde are subjected to an addition polymerization reaction in an aqueous medium under a basic catalyst to cure as a phenol resol resin. At this time, the magnetic substance is put into an aqueous medium, the monomer and the magnetic substance are uniformly slurried, and when the reaction proceeds and the resin is cured, the magnetic substance is taken in to form a core.

The volume distribution-based 50% particle size (D50) of the carrier core obtained as described above is 18.0 μm or more and 78.m or more in order to make the final magnetic carrier particle size 20.0 μm or more and 80.0 μm or less. It is preferably 0 μm or less. This makes it possible to improve the property of imparting triboelectrification to the toner, satisfy the image quality of the halftone portion, suppress fog and prevent carrier adhesion.

When the carrier core has a specific resistance of 1.0×10 ⁶ Ω·cm or more and 1.0×10 ⁹ Ω·cm or less at an electric field strength of 300 V/cm in the later-described specific resistance measurement method, the developability is improved. It is preferable because it can be increased.

<Method for producing resin composition-coated particles>
The method for coating the magnetic material-dispersed resin carrier core material particle surface with the resin composition is not particularly limited, but a coating method such as a dipping method, a spray method, a brush coating method, a dry method, and a fluidized bed is used. Is mentioned. The amount of the resin to be coated is preferably 0.1 part by mass or more and 5.0 parts by mass or less with respect to 100 parts by mass of the magnetic material-dispersed resin carrier core material particles.

The resin of the resin composition may be either a thermoplastic resin or a thermosetting resin, but it is a polymer obtained by polymerizing a monomer containing an acrylic acid ester monomer or a methacrylic acid ester monomer, or a silicone resin. .. Examples of usable (meth)acrylic acid ester monomers include methyl acrylate, ethyl acrylate, propyl acrylate, isopropyl acrylate, normal butyl acrylate, isobutyl acrylate, tert-butyl acrylate, acrylic acid 2 -Ethylhexyl, lauryl acrylate, dodecyl acrylate, tridecyl acrylate, tetradecyl acrylate, pentadecyl acrylate, hexadecyl acrylate, heptadecyl acrylate, octadecyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate , Normal butyl methacrylate, isobutyl methacrylate, tert-butyl methacrylate, 2-ethylhexyl methacrylate, lauryl methacrylate, dodecyl methacrylate, tridecyl methacrylate, tetradecyl methacrylate, pentadecyl methacrylate, hexadecyl methacrylate, heptadecyl methacrylate and Examples thereof include octadecyl methacrylate. For straight silicone resins, KR-271, KR-251, KR-255 manufactured by Shin-Etsu Chemical Co., Ltd., SR2400, SR2405, SR2410, SR2411 manufactured by Toray Dow Corning. Examples of the modified silicone resin include KR206 (alkyd modified), KR5208 (acrylic modified), ES1001N (epoxy modified) and SR2110 (alkyd modified) manufactured by Shin-Etsu Chemical Co., Ltd.

Next, a method for manufacturing the magnetic carrier will be described.

<Method of manufacturing magnetic carrier>
The method for coating the surface of the resin composition-coated particles with the resin coating layer composition is not particularly limited, but includes a method of treating by a coating method such as a dipping method, a spray method, a brush coating method, a dry method, and a fluidized bed. Can be mentioned.

The resin of the resin coating layer is a polymer obtained by polymerizing a monomer containing an acrylic acid ester monomer or a methacrylic acid ester monomer. Further, a vinyl-based resin which is a copolymer of a vinyl-based monomer having a cyclic hydrocarbon group in its molecular structure and another vinyl-based monomer is preferable. By coating with the vinyl-based resin, it is possible to suppress a reduction in the amount of charge in a high temperature and high humidity environment.

The reason why the reduction of the charge amount under the high temperature and high humidity environment is suppressed by coating the vinyl resin is considered as follows. When the vinyl resin is coated on the surface of the resin composition-coated particles, a coating step in which the vinyl resin dissolved in an organic solvent and the resin composition-coated particles are mixed and desolvated is performed. .. In the above step, the solvent is removed while the cyclic hydrocarbon group is oriented on the surface of the resin coating layer, and a highly hydrophobic cyclic hydrocarbon group is oriented on the surface of the completed magnetic carrier. This is because the resin coating layer is formed by.

Specific examples of the cyclic hydrocarbon group include cyclic hydrocarbon groups having 3 to 10 carbon atoms, such as cyclohexyl group, cyclopentyl group, adamantyl group, cyclopropyl group, cyclobutyl group, cycloheptyl group, cyclooctyl group. , A cyclononyl group, a cyclodecyl group, an isobornyl group, a norbornyl group, a boronyl group and the like. Of these, a cyclohexyl group, a cyclopentyl group, and an adamantyl group are preferable, and a cyclohexyl group is particularly preferable from the viewpoint that it is structurally stable and therefore has high adhesion to the filled core particles.

Further, in order to adjust the glass transition temperature (Tg), another monomer may be further contained as a constituent component of the vinyl resin.

Known monomers are used as the other monomer used as a constituent component of the vinyl resin, and examples thereof include the following. Examples thereof include styrene, ethylene, propylene, butylene, butadiene, vinyl chloride, vinylidene chloride, vinyl acetate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, vinyl methyl ether, vinyl ethyl ether and vinyl methyl ketone.

Further, it is preferable that the vinyl-based resin used for the coating layer is a graft polymer because the wettability with the magnetic material-dispersed resin carrier core material particles is further improved and a uniform coating layer is formed.

To obtain a graft polymer, there are a method of graft polymerization after forming a backbone chain and a method of copolymerizing by using a macromonomer as a monomer. It is preferable because it can be easily controlled.

The macromonomer used is not particularly limited, but a methylmethacrylate macromonomer is preferable because the wettability with the magnetic material-dispersed resin carrier core material particles is further improved.

The amount used when polymerizing the macromonomer is preferably 10 parts by mass or more and 50 parts by mass or less, and 20 parts by mass or more and 40 parts by mass or less with respect to 100 parts by mass of the copolymer of the backbone chain of the vinyl resin. More preferable.

Further, the resin coating layer composition may be used by incorporating particles having conductivity or particles or materials having charge controllability. Examples of particles having conductivity include carbon black, magnetite, graphite, zinc oxide, and tin oxide. Among them, by suitably acting the filler effect of carbon black, the surface tension of the resin coating layer composition can be suitably exerted, which is preferable from the viewpoint of improving the coatability of the resin coating layer composition.

The reason why the coatability of the resin coating layer composition can be improved by appropriately exerting the filler effect of carbon black is derived from the primary particle diameter and cohesiveness of carbon black. That is, carbon black exhibits a large specific surface area because of its small primary particle size. On the other hand, carbon black has a high aggregating property and therefore exists as a large particle as an aggregating particle. Due to the primary particle size and the cohesiveness, the particles can largely deviate from the relationship between the particle size and the specific surface area. That is, this is because the particle size is such that the surface tension of the resin coating layer composition acts, and since the contact point is large due to the size of the specific surface area, the surface tension of the resin coating layer composition easily acts.

The amount of conductive particles added is preferably 0.1 parts by mass or more and 10.0 parts by mass or less with respect to 100 parts by mass of the resin coating layer in order to adjust the resistance of the magnetic carrier. Particles having charge controllability include particles of organometallic complex, particles of organometallic salt, particles of chelate compound, particles of monoazo metal complex, particles of acetylacetone metal complex, particles of hydroxycarboxylic acid metal complex, and metal of polycarboxylic acid. Complex particles, polyol metal complex particles, polymethylmethacrylate resin particles, polystyrene resin particles, melamine resin particles, phenol resin particles, nylon resin particles, silica particles, titanium oxide particles, alumina particles, etc. Can be mentioned. The addition amount of the particles having charge controllability is preferably 0.5 parts by mass or more and 50.0 parts by mass or less with respect to 100 parts by mass of the resin coating layer in order to adjust the triboelectric charge amount.

Next, a preferable toner structure for achieving the object in the invention will be described.

<Structure of toner>
In the present invention, a preferable toner constitution for achieving the object will be described in detail below.

Examples of the binder resin used in the present invention include vinyl resins, polyester resins, epoxy resins and the like. Of these, vinyl resins and polyester resins are more preferable in terms of charging property and fixing property.

In the present invention, a vinyl monomer homopolymer or copolymer, polyester, polyurethane, epoxy resin, polyvinyl butyral, rosin, modified rosin, terpene resin, phenol resin, aliphatic or alicyclic hydrocarbon resin, aromatic system Petroleum resin and the like can be used by mixing with the binder resin described above, if necessary.

When two or more kinds of resins are mixed and used as a binder resin, as a more preferable form, it is preferable to mix resins having different molecular weights in an appropriate ratio.

The glass transition temperature of the binder resin is preferably 45 to 80° C., more preferably 55 to 70° C., the number average molecular weight (Mn) is 2,500 to 50,000, and the weight average molecular weight (Mw) is 10,000. It is preferably from 1 to 1,000,000.

The following polyester resins are also preferable as the binder resin.

In the polyester resin, 45 to 55 mol% is an alcohol component and 55 to 45 mol% is an acid component in all components.

The acid value of the polyester resin is preferably 90 mgKOH/g or less, more preferably 50 mgKOH/g or less, and the OH value is preferably 50 mgKOH/g or less, more preferably 30 mgKOH/g or less. This is because as the number of terminal groups in the molecular chain increases, the toner charging characteristics become more environmentally dependent.

The glass transition temperature of the polyester resin is preferably 50 to 75°C, more preferably 55 to 65°C. The number average molecular weight (Mn) is preferably 1,500 to 50,000, more preferably 2,000 to 20,000. The weight average molecular weight (Mw) is preferably 6,000 to 100,000, more preferably 10,000 to 90,000.

When the toner of the present invention is used as a magnetic toner, the magnetic material contained in the magnetic toner includes iron oxides such as magnetite, maghemite and ferrite, and iron oxides containing other metal oxides; such as Fe, Co and Ni. Metals, or alloys of these metals with metals such as Al, Co, Cu, Pb, Mg, Ni, Sn, Zn, Sb, Be, Bi, Cd, Ca, Mn, Se, Ti, W, V , And mixtures thereof.

Specifically, as the magnetic material, iron trioxide (Fe ₃ O ₄ ), iron sesquioxide (γ-Fe ₂ O ₃ ), zinc iron oxide (ZnFe ₂ O ₄ ), yttrium iron oxide (Y ₃ Fe) ₅ O ₁₂ ), iron cadmium oxide (CdFe ₂ O ₄ ), iron gadolinium oxide (Gd ₃ Fe ₅ O ₁₂ ), iron oxide copper (CuFe ₂ O ₄ ), lead iron oxide (PbFe ₁₂ O ₁₉ ), iron nickel oxide (NiFe ₂ O ₄ ), iron neodymium oxide (NdFe ₂ O ₃ ), iron oxide barium (BaFe ₁₂ O ₁₉ ), magnesium iron oxide (MgFe ₂ O ₄ ), iron manganese oxide (MnFe ₂ O ₄ ), lanthanum iron oxide. (LaFeO ₃ ), iron powder (Fe), cobalt powder (Co), nickel powder (Ni), and the like.

These are used in an amount of 20 parts by mass or more and 150 parts by mass or less, preferably 50 parts by mass or more and 130 parts by mass or less, and more preferably 60 parts by mass or more and 120 parts by mass or less with respect to 100 parts by mass of the binder resin. ..

Examples of the non-magnetic colorant used in the present invention include the following.

Examples of the black colorant include carbon black; those adjusted to black using a yellow colorant, a magenta colorant and a cyan colorant.

Examples of the color pigment for magenta toner include the following. Examples thereof 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 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 21, 22, 23, 30, 31, 32, 37, 38, 39, 40, 41, 48:2, 48:3, 48:4, 49, 50, 51, 52, 53, 54, 55, 57:1, 58, 60, 63, 64, 68, 81:1, 83, 87, 88, 89, 90, 112, 114, 122, 123, 144, 146, 150, 163, 166, 169, 177, 184, 185, 202, 206, 207, 209, 220, 221, 238, 254, 269; C.I. I. Pigment Violet 19, C.I. I. Butred 1, 2, 10, 13, 15, 23, 29, and 35.

Although the pigment may be used alone as the colorant, it is preferable from the viewpoint of the image quality of a full-color image to improve the sharpness by using a dye and a pigment in combination.

Examples of the magenta toner dye include the following. C. I Solvent Red 1, 3, 8, 23, 24, 25, 27, 30, 49, 81, 82, 83, 84, 100, 109, 121, C.I. I. Disperse Red 9, C.I. I. Solvent Violet 8, 13, 14, 21, 27, C.I. I. Oil soluble dyes such as Disper Violet 1, C.I. I. Basic Red 1, 2, 9, 12, 13, 14, 15, 17, 18, 22, 23, 24, 27, 29, 32, 34, 35, 36, 37, 38, 39, 40, C.I. I. Basic dyes such as Basic Violet 1, 3, 7, 10, 14, 15, 21, 25, 26, 27, 28 and the like.

Examples of the color pigment for cyan toner include the following. C. I. Pigment Blue 1, 2, 3, 7, 15:2, 15:3, 15:4, 16, 17, 60, 62, 66; C.I. I. Bat Blue 6, C.I. I. Acid Blue 45, a copper phthalocyanine pigment having 1 to 5 phthalimidomethyl substituted on the phthalocyanine skeleton.

Examples of the coloring pigment for yellow include the following. Condensed azo compounds, isoindolinone compounds, anthraquinone compounds, azo metal compounds, methine compounds, allylamide compounds. Specifically, C.I. I. Pigment Yellow 1, 2, 3, 4, 5, 6, 7, 10, 11, 12, 13, 14, 15, 16, 17, 23, 62, 65, 73, 74, 83, 93, 95, 97, 109, 110, 111, 120, 127, 128, 129, 147, 155, 168, 174, 180, 181, 185, 191; I. Butt Yellow 1, 3, and 20 are mentioned. Also, C.I. I. Direct Green 6, C.I. I. Basic Green 4, C.I. I. Dyes such as Basic Green 6 and Solvent Yellow 162 can also be used.

The amount of the colorant used is preferably 0.1 parts by mass or more and 30 parts by mass or less, more preferably 0.5 parts by mass or more and 20 parts by mass or less, and most preferably 100 parts by mass of the binder resin. It is 3 parts by mass or more and 15 parts by mass or less.

In addition, it is preferable to use a toner obtained by mixing the binder resin with a colorant in advance and forming a master batch in the toner. Then, the colorant can be satisfactorily dispersed in the toner by melt-kneading the colorant masterbatch and other raw materials (binder resin, wax, etc.).

In the toner of the present invention, a charge control agent can be used, if necessary, in order to further stabilize its chargeability. The charge control agent is preferably used in an amount of 0.5 parts by mass or more and 10 parts by mass or less per 100 parts by mass of the binder resin. If it is less than 0.5 parts by mass, sufficient charging characteristics may not be obtained, and if it exceeds 10 parts by mass, the compatibility with other materials may be deteriorated, and charging may be performed under low humidity. It may be excessive, which is not preferable.

Examples of the charge control agent include the following.

An organometallic complex or a chelate compound is effective as a negatively charge controlling agent for controlling the toner negatively. Examples thereof include a monoazo metal complex, an aromatic hydroxycarboxylic acid metal complex, and an aromatic dicarboxylic acid metal complex. Other examples include aromatic hydroxycarboxylic acids, aromatic mono- and polycarboxylic acids and metal salts thereof, anhydrides thereof, esters thereof, or phenol derivatives of bisphenol.

Examples of the positive charge control agent for controlling the toner to have a positive charge property include modified products of nigrosine and fatty acid metal salts, tributylbenzylammonium-1-hydroxy-4-naphthosulfonate, tetrabutylammonium tetrafluoroborate and the like. Primary ammonium salts, onium salts such as phosphonium salts which are analogs thereof, and chelate pigments thereof, such as triphenylmethane dyes and lake pigments thereof (as a laker, phosphorus tungstic acid, phosphorus molybdic acid, phosphorus tungsten) Molybdic acid, tannic acid, lauric acid, gallic acid, ferricyanic acid, ferrocyanine compounds, etc.), dibutyltin oxide such as dibutyltin oxide, dioctyltin oxide, dicyclohexyltin oxide and dibutyltin borate, dioctyl as metal salts of higher fatty acids. Examples thereof include diorgano tin borate such as tin borate and dicyclohexyl tin borate.

In the present invention, one or more release agents may be contained in the toner particles, if necessary. Examples of the release agent include the following.

Aliphatic hydrocarbon waxes such as low molecular weight polyethylene, low molecular weight polypropylene, microcrystalline wax and paraffin wax can be preferably used. In addition, oxides of aliphatic hydrocarbon waxes such as oxidized polyethylene wax, or block copolymers thereof; waxes containing fatty acid esters such as carnauba wax, sazol wax and montanic acid ester wax as a main component; and Examples include fatty acid esters such as deoxidized carnauba wax that are partially or wholly deoxidized.

The amount of the release agent is preferably 0.1 parts by mass or more and 20 parts by mass or less, and more preferably 0.5 parts by mass or more and 10 parts by mass or less, per 100 parts by mass of the binder resin.

The melting point of the release agent, which is defined by the maximum endothermic peak temperature at the time of temperature increase measured by a differential scanning calorimeter (DSC), is preferably 65 to 130°C. More preferably, it is 80 to 125°C. When the melting point is lower than 65°C, the viscosity of the toner is lowered, and the toner is apt to adhere to the photoconductor. When the melting point is higher than 130°C, the low temperature fixing property may be deteriorated, which is not preferable. ..

In the toner of the present invention, a fine powder whose fluidity can be increased by externally adding to the toner particles before and after addition may be used as a fluidity improver. For example, vinylidene fluoride fine powder, fluororesin powder such as polytetrafluoroethylene fine powder; fine silica powder such as wet process silica and dry process silica, fine powder titanium oxide, fine powder alumina, etc. as silane coupling agent, titanium It is preferable that the surface treatment is performed with a coupling agent and silicone oil, and then the surface is hydrophobized.

The inorganic fine particles in the invention are used in an amount of 0.1 parts by mass or more and 10 parts by mass or less, preferably 0.2 parts by mass or more and 8 parts by mass or less, relative to 100 parts by mass of the toner.

When the toner of the present invention is mixed with a magnetic carrier to be used as a two-component developer, the carrier mixing ratio at that time is 2% by mass or more and 15% by mass or less, preferably 4% by mass as the toner concentration in the developer. % Or more and 13% by mass or less, usually good results are obtained. If the toner concentration is less than 2% by mass, the image density tends to decrease, and if it exceeds 15% by mass, fog or scattering in the machine tends to occur.

Further, in a replenishment developer for replenishing the two-component developer in the developing device according to the decrease in toner concentration, the toner amount is 2 parts by mass or more and 50 parts by mass or more with respect to 1 part by mass of the replenishing magnetic carrier. Below the section.

Next, an image forming apparatus equipped with a developing device using the magnetic carrier of the present invention, a two-component developer and a replenishing developer will be described by way of example. The developing device used in the developing method of the present invention is It is not limited to.

<Image forming method>
In FIG. 1, the electrostatic latent image carrier 1 rotates in the direction of the arrow in the figure. The electrostatic latent image carrier 1 is charged by a charger 2 which is a charging means, and the charged electrostatic latent image carrier 1 surface is exposed by an exposing device 3 which is an electrostatic latent image forming means to form an electrostatic latent image. Form an image. The developing device 4 has a developing container 5 for accommodating a two-component developer, a developer carrier 6 is rotatably arranged, and a magnetic field generating means is provided inside the developer carrier 6 to form a magnet. Contains 7. At least one of the magnets 7 is installed so as to face the latent image carrier. The two-component developer is held on the developer carrier 6 by the magnetic field of the magnet 7, the amount of the two-component developer is regulated by the regulation member 8, and the developer is opposed to the electrostatic latent image carrier 1. Be transported. In the developing section, a magnetic brush is formed by the magnetic field generated by the magnet 7. Then, by applying a developing bias formed by superimposing an alternating electric field on the DC electric field, the electrostatic latent image is visualized as a toner image. The toner image formed on the electrostatic latent image carrier 1 is electrostatically transferred to the recording medium 12 by the transfer charger 11. Here, as shown in FIG. 2, the electrostatic latent image carrier 1 may be temporarily transferred to the intermediate transfer member 9 and then electrostatically transferred to the transfer material (recording medium) 12. After that, the recording medium 12 is conveyed to the fixing device 13, where the toner is fixed on the recording medium 12 by being heated and pressed. After that, the recording medium 12 is ejected outside the apparatus as an output image. After the transfer process, the toner remaining on the electrostatic latent image carrier 1 is removed by the cleaner 15. After that, the electrostatic latent image carrier 1 cleaned by the cleaner 15 is electrically initialized by the light irradiation from the pre-exposure 16, and the image forming operation is repeated.

FIG. 2 shows an example of a schematic diagram in which the image forming method of the present invention is applied to a full-color image forming apparatus.

The arrows indicating the arrangement and rotation directions of the image forming units such as K, Y, C, and M in the drawing are not limited to these. By the way, K means black, Y means yellow, C means cyan, and M means magenta. In FIG. 2, the electrostatic latent image carriers 1K, 1Y, 1C, 1M rotate in the direction of the arrow in the figure. Each electrostatic latent image carrier is charged by a charger 2K, 2Y, 2C, 2M which is a charging unit, and the charged electrostatic latent image carrier surface has an exposing unit 3K which is an electrostatic latent image forming unit. 3Y, 3C, and 3M expose to form an electrostatic latent image. After that, the electrostatic latent image can be converted into a toner image by the two-component developer carried on the developer carrying members 6K, 6Y, 6C and 6M provided in the developing devices 4K, 4Y, 4C and 4M which are developing means. To be visualized. Further, it is transferred to the intermediate transfer body 9 by the intermediate transfer chargers 10K, 10Y, 10C and 10M which are transfer means. Further, it is transferred onto a recording medium 12 by a transfer charger 11 which is a transfer means, and the recording medium 12 is heated and pressure-fixed by a fixing device 13 which is a fixing means, and is output as an image. Then, the intermediate transfer body cleaner 14, which is a cleaning member for the intermediate transfer body 9, collects the transfer residual toner and the like. As the developing method of the present invention, specifically, an alternating voltage is applied to the developer carrying member to form an alternating electric field in the developing region, and the developing is carried out while the magnetic brush is in contact with the photosensitive member. Preferably. The distance (SD distance) between the developer carrying member (developing sleeve) 6 and the photosensitive drum is preferably 100 μm or more and 1000 μm or less in terms of preventing carrier adhesion and improving dot reproducibility. If it is less than 100 μm, the supply of the developer is likely to be insufficient and the image density is lowered. If it exceeds 1000 μm, the magnetic lines of force from the magnetic pole S1 spread and the density of the magnetic brush becomes low, the dot reproducibility becomes poor, or the force for restraining the magnetic coated carrier weakens, and carrier adhesion easily occurs.

The peak-to-peak voltage (Vpp) of the alternating electric field is 300 V or more and 3000 V or less, preferably 500 V or more and 1800 V or less. The frequency is 500 Hz or more and 10000 Hz or less, preferably 1000 or more and 7000 Hz or less, and can be appropriately selected and used depending on the process. In this case, examples of the waveform of the AC bias for forming the alternating electric field include a triangular wave, a rectangular wave, a sine wave, and a waveform in which the duty ratio is changed. In order to cope with the change in the toner image forming speed, it is preferable to apply a developing bias voltage (intermittent alternating superposition voltage) having a discontinuous AC bias 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 the fog toner in the non-image area may not be recovered well. If the voltage exceeds 3000 V, the latent image may be disturbed via the magnetic brush, and the image quality may be degraded.

By using a two-component developer having a well-charged toner, the fog removal voltage (Vback) can be lowered, and the primary charge of the photoconductor can be lowered, so that the photoconductor life is extended. it can. Vback is preferably 200 V or lower, more preferably 150 V or lower, though it depends on the developing system. The contrast potential is preferably 100 V or more and 400 V or less so that a sufficient image density can be obtained.

Further, when the frequency is lower than 500 Hz, the structure of the electrostatic latent image bearing photoconductor is usually the same as that of the photoconductor used in the image forming apparatus, although it is related to the process speed. For example, there is a photoreceptor having a structure in which a conductive layer, an undercoat layer, a charge generation layer, a charge transport layer, and a charge injection layer are provided in this order on a conductive substrate such as aluminum or SUS.

The conductive layer, the undercoat layer, the charge generation layer, and the charge transport layer may be those usually used for a photoreceptor. As the outermost surface layer of the photoreceptor, for example, a charge injection layer or a protective layer may be used.

<Measurement method of volume average particle diameter of inorganic particles or primary particles of carbon black>
The volume average particle diameter of the primary particles of the hydrophilically treated particles in the present invention was observed with a transmission electron microscope, and the average value of the major axis and the minor axis of the particles was taken as the particle diameter. Further, the particle size of 100 particles was measured, and the average value was defined as the volume average particle size of the primary particles.

<Measurement method of volume average particle diameter (D50) of magnetic carrier and magnetic carrier core>
The particle size distribution was measured with a laser diffraction/scattering type particle size distribution measuring device "Microtrac MT3300EX" (manufactured by Nikkiso Co., Ltd.).

To measure the volume average particle size (D50) of the magnetic carrier and the porous magnetic material-dispersed resin carrier core particles, a sample feeder "one-shot dry type sample conditioner Turbotrac" (manufactured by Nikkiso Co., Ltd.) for dry measurement is attached. I went. As the conditions for supplying Turbotrac, a dust collector was used as a vacuum source, an air flow rate was about 33 l/sec, and a pressure was about 17 kPa. The control is automatically performed by software. For the particle size, a 50% particle size (D50), which is a cumulative value of volume average, is determined. Control and analysis are performed using the attached software (version 10.3.3-202D). The measurement conditions are as follows.
Set Zero time: 10 seconds Measurement time: 10 seconds Number of measurements: 1 time Particle refractive index: 1.81%
Particle shape: Non-spherical measurement upper limit: 1408 μm
Lower limit of measurement: 0.243 μm
Measurement environment: 23°C, 50%RH

<Method of measuring weight average particle diameter (D4) and number average particle diameter (D1) of toner>
The weight average particle diameter (D4) and the number average particle diameter (D1) of the toner are "Coulter Counter Multisizer 3" (registered trademark, Beckman Beckman Coulter Multisizer 3 Version 3.51 (manufactured by Beckman Coulter, Inc.) and dedicated software for setting measurement conditions and analyzing measurement data were used. The number of effective measurement channels was 25,000, and the measurement data was analyzed and calculated.

The electrolytic aqueous solution used for the measurement may be prepared by dissolving special grade sodium chloride in ion-exchanged water so that the concentration becomes about 1% by mass, for example, "ISOTON II" (manufactured by Beckman Coulter, Inc.).

Before the measurement and analysis, the dedicated software was set as follows.

In the special software “Change Standard Measurement Method (SOM) screen”, set the total count in control mode to 50,000 particles, set the number of measurements once, and set the Kd value to “Standard particles 10.0 μm” (Beckman Coulter, Inc.). The value obtained by using the product is set. The threshold and noise level are automatically set by pressing the threshold/noise level measurement button. In addition, the current is set to 1600 μA, the gain is set to 2, the electrolyte is set to ISOTON II, and the flash of the aperture tube after the measurement is checked.

On the "pulse-to-particle size conversion setting screen" of the dedicated software, set the bin interval to the logarithmic particle size, the particle size bin to the 256 particle size bin, and the particle size range from 2 μm to 60 μm.

The specific measuring method is as follows.
(1) About 200 ml of the electrolytic aqueous solution is put in a glass 250 ml round bottom beaker for Multisizer 3 and set on a sample stand, and the stirrer rod is stirred counterclockwise at 24 rpm. Then, the dirt and air bubbles in the aperture tube are removed by the "aperture flush" function of the analysis software.
(2) About 30 ml of the electrolytic aqueous solution is placed in a glass 100 ml flat-bottom beaker. In this, as a dispersant, "contaminone N" (a nonionic surfactant, an anionic surfactant, a 10 mass% aqueous solution of a neutral detergent for washing precision measuring instruments of pH 7 comprising an organic builder, manufactured by Wako Pure Chemical Industries ) Is diluted 3 times by mass with ion-exchanged water, and about 0.3 ml of a diluted solution is added.
(3) Two oscillators with an oscillating frequency of 50 kHz are installed with their phases shifted by 180 degrees, and are placed in the water tank of an ultrasonic disperser "Ultrasonic Dispersion System Tetora 150" (manufactured by Nikkaki Bios) with an electric output of 120 W. Add a fixed amount of deionized water. About 2 ml of the Contaminone N is added to the water tank.
(4) The beaker of (2) is set in the beaker fixing hole of the ultrasonic disperser, and the ultrasonic disperser is operated. Then, the height position of the beaker is adjusted so that the resonance state of the liquid level of the electrolytic aqueous solution in the beaker becomes maximum.
(5) About 10 mg of toner is added little by little to the electrolytic aqueous solution in a state where the electrolytic aqueous solution in the beaker of (4) is irradiated with ultrasonic waves and dispersed. Then, the ultrasonic dispersion treatment is continued for another 60 seconds. In the ultrasonic dispersion, the water temperature in the water tank is appropriately adjusted to be 10°C or higher and 40°C or lower.
(6) To the round-bottom beaker (1) installed in the sample stand, drop the toner-dispersed aqueous electrolyte solution (5) with a pipette, and adjust so that the measured concentration is about 5%. .. Then, the measurement is performed until the number of measured particles reaches 50,000.
(7) The measurement data is analyzed by the dedicated software attached to the apparatus to calculate the weight average particle diameter (D4) and the number average particle diameter (D1). When the graph/volume% is set with the dedicated software, the “average diameter” on the analysis/volume statistical value (arithmetic mean) screen is the weight average particle diameter (D4), and the dedicated software sets the graph/number%. The “average diameter” on the analysis/number statistical value (arithmetic mean) screen at this time is the number average particle diameter (D1).

<Calculation method of fine powder amount>
The number-based fine powder amount (number%) in the toner is calculated as follows. For example, for the number% of particles of 4.0 μm or less in the toner, after measuring the Multisizer 3 described above, (1) set the graph/number% with the dedicated software and display the measurement result chart as the number%. To do. (2) Check "<" in the particle size setting section on the format/particle size/particle size statistical screen, and enter "4" in the particle size input section below. Then, (3) when the analysis/number statistical value (arithmetic mean) screen is displayed, the numerical value of the “<4 μm” display portion is the number% of particles of 4.0 μm or less in the toner.

<Calculation method of coarse powder amount>
The volume-based coarse powder amount (volume %) in the toner is calculated as follows. For example, for the volume% of particles of 10.0 μm or more in the toner, after measuring the Multisizer 3 described above, (1) set the graph/volume% with the dedicated software to display the measurement result chart as the volume%. To do. (2) Check ">" in the particle size setting section on the format/particle size/particle size statistical screen, and enter "10" in the particle size input section below. Then, (3) when the analysis/volume statistic (arithmetic mean) screen is displayed, the numerical value of the “>10 μm” display portion is the volume% of particles of 10.0 μm or more in the toner.

<Measurement method of methanol wettability of hydrophilically treated particles>
To a 500 ml beaker, precisely weigh 0.20 g of the hydrophilically treated particles. Subsequently, pure 50 ml was added, and while stirring with a magnetic stirrer, while the hydrophilically treated particles were floating on the liquid surface, methanol was continuously added below the liquid surface at a dropping rate of 4.0 ml/min to inject. To do. The total amount of hydrophilically treated particles is suspended in the solution, and when the hydrophilically treated particles are no longer observed on the liquid surface, the methanol wettability is calculated from the amount of added methanol, and the hydrophilically treated particles are It was used as an index showing hydrophilicity.

The wettability of methanol is determined according to the following equation, where X is the amount of methanol added.
Methanol wettability (%)=X/(50+X)·100

<Measurement method of water content change of magnetic carrier>
The magnetic carrier is weighed in a stainless steel dish with a precision balance in an amount of 10 g, and the carrier mass is W1 when the magnetic carrier is left for 5 hours in a dryer at a set temperature of 60° C. under reduced pressure. After that, the mass of the carrier when the obtained magnetic carrier was left in an atmosphere of a temperature of 30° C. and a humidity of 80% for 24 hours was W2. The water content of the magnetic carrier at this time is (A) mass %. After that, the carrier mass when continuously left in an environment of a temperature of 23° C. and a humidity of 5% for 24 hours is set to W3. Further, the water content of the magnetic carrier at this time is (B) mass %. The water content change of the magnetic carrier was calculated according to the following formula (1).
Moisture content change of magnetic carrier (mass %)
= [(W2-W1) x 100/W1]-[(W3-W1) x 100/W1]
=[A]-[B]
=(AB) (Formula 1)

<Measurement Method of Intermediate Resin Layer and Surface Resin Layer Thickness of Magnetic Carrier>
As a method of measuring the film thickness of the intermediate resin layer and the surface resin layer, the cross section of the magnetic carrier was observed with a transmission electron microscope (TEM) (50,000 times each), and the thickness of the resin coating layer was measured.

Specifically, an argon ion milling device (Hitachi High-Technologies Corporation, trade name E-3500) was used as the magnetic carrier. Ion-milling under conditions of a beam diameter of 400 μm at full width at half maximum, an ion gun of 5 kV (accelerating voltage: 5 kV, discharge voltage: 4 kV, discharge current: 463 μA, irradiation current amount: 90 μA/cm ³ /1 min), and a transmission electron microscope (TEM). At each (50,000 times), the thickness of the surface resin layer on the cross section of the magnetic carrier was arbitrarily measured at 10 points. The same measurement is performed on 100 points of the magnetic carrier, and the minimum value and the maximum value are selected from the obtained 1000 points of the measured thickness of the surface resin layer, and the minimum film thickness (μm) and the maximum film thickness (μm) are selected. And In addition, for the thickness of the intermediate resin layer, the minimum film thickness (μm) and the maximum film thickness (μm) were measured by the same method. In the magnetic carrier of the present invention, the type of particles contained in the intermediate resin layer and the surface resin layer and the amount thereof are different, so that the intermediate resin layer and the surface resin layer can be determined by the measuring method.

<Measurement method of surface functional group concentration of particles>
-Method for measuring carboxyl group concentration 10 mg of particles are stuck on an indium foil. At that time, the particles are evenly attached so that the indium foil portion is not exposed. 1.0 ml of 2,2,2-trifluoroethanol is added dropwise to a 30 ml screw tube bottle, and the system is saturated with steam. The particles are put together with the indium foil in the system, and left for 12 hours while the particles are exposed in the atmosphere of 2,2,2-trifluoroethanol. At this time, be careful that the particles do not directly adhere to the 2,2,2-trifluoroethanol solution. The particles, together with the indium foil, were taken out of the system and left in a dryer at a set temperature of 25°C under reduced pressure for 6 hours. When XPS analysis is performed on the obtained particles, a C _1S XPS peak (P1) derived from 2,2,2-trifluoroethyl ester and an XPS peak (P2) derived from the particle-derived element are detected. The surface functional group concentration of the particles was calculated according to the equation (2). The measurement conditions are as follows.
Device: PHI5000VERSAPPROBEII (ULVAC-PHI)
Ltd.)
Irradiation line: Al Kd line output: 25W 15kV
PassEnergy: 29.35 eV
Stepsize: 0.125eV
XPS peak (P2): C _1S (CB), Ti _2P (TiO ₂ , SrTiO ₂ ), Al _2P (Al ₂ O ₃ ), Si _2P (SiO ₂ ), Mg _2P (MgO), Zn _2P3/2 (ZnO) )
Surface functional group concentration of particles [%]=P1/P2×100 (Equation 2)

-Measurement method of ester group (carbonyl group) concentration XPS analysis is performed in the same manner as the measurement of ester group (carboxyl group) concentration except that the reaction reagent is changed from 2,2,2-trifluoroethanol to diamine. went. Since the N _1S XPS peak (P3) derived from the imino group was detected, the surface functional group concentration of the particles was calculated according to the following formula (3).
Surface functional group concentration of particles [%]=P3/P2×100 (Formula 3)

<Method of measuring true density of magnetic carrier and magnetic carrier core>
The true density was measured using a dry automatic densitometer auto pycnometer (manufactured by Yuasa Ionics).

<Specific resistance measurement of magnetic carrier core particles>
The resistance of the magnetic carrier core particles is measured using the measuring device outlined in FIG. The specific resistance at an electric field strength of 300 (V/cm) is measured.

The resistance measuring cell A comprises a cylindrical container (made of PTFE resin) 17, a lower electrode (made of stainless steel) 18, a support pedestal (made of PTFE resin) 19, an upper electrode (made of stainless steel) with a hole having a cross-sectional area of 2.4 cm ^2. It consists of 20. The cylindrical container 18 is placed on the support pedestal 19, the sample 21 is filled to have a thickness of about 1 mm, the upper electrode 20 is placed on the filled sample 5, and the thickness of the sample is measured. As shown in FIG. 3(a), the gap without the sample is d1, and as shown in FIG. 3(b), the gap is d2 when the sample is filled to have a thickness of about 1 mm. d is calculated by the following formula.
d=d2-d1 (mm)

At this time, the mass of the sample is appropriately changed so that the thickness d of the sample is 0.95 mm or more and 1.04 mm or less.

The specific resistance of the sample can be determined by applying a DC voltage between the electrodes and measuring the current flowing at that time. For the measurement, an electrometer 22 (Kesley 6517A made by Kessley Co.) and a processing computer 23 for control are used.

A control system and control software (LabVEIW National Instruments) manufactured by National Instruments were used as a processing computer for control.

As measurement conditions, the contact area S between the sample and the electrode S=2.4 cm ² and the value d measured so that the thickness of the sample is 0.95 mm or more and 1.04 mm or less are input. The load on the upper electrode is 270 g and the maximum applied voltage is 1000V.
Specific resistance (Ω·cm)=(applied voltage (V)/measured current (A))×S (cm ² )/d (cm)
Electric field strength (V/cm)=applied voltage (V)/d (cm)

For the specific resistance of the magnetic carrier core particles at the electric field strength, the specific resistance at the electric field strength on the graph is read from the graph.

Hereinafter, the present invention will be described more specifically with reference to Examples, but the present invention is not limited to these Examples. In addition, Examples 16-18 are reference examples.

<Production Example of Magnetic Material-Dispersed Resin Carrier Core Material 1>
4.0 mass% of the silane coupling agent (3-(2-aminoethylaminopropyl)tri) was added to the magnetite powder having a number average particle size of 0.30 μm and the hematite powder having a number average particle size of 0.30 μm. (Methoxysilane) was added, and high speed mixing and stirring were performed at 100° C. or higher in the container to treat each fine particle.

-Phenol 10 parts by mass-Formaldehyde solution 6 parts by mass (formaldehyde 40%, methanol 10%, water 50%)
-Treatment of magnetite 80 parts by mass-Treatment of hematite 4 parts by mass The above materials, 5 parts by mass of 28% ammonia water, and 20 parts by mass of water are put into a flask and heated to 85°C in 30 minutes while stirring and mixing, and kept. Then, a polymerization reaction was carried out for 3 hours to cure the resulting phenol resin. Then, the cured phenol resin was cooled to 30° C., water was further added, the supernatant was removed, the precipitate was washed with water, and then air dried. Then, this was dried under reduced pressure (5 mmHg or less) at a temperature of 60° C. to obtain spherical magnetic substance-containing resin carrier core particles in which a magnetic substance was dispersed.

To 100.0 parts by mass of the obtained magnetic substance-containing resin carrier core particles, 1.0 part by mass of stearic acid chloride and 200 parts by mass of o-xylene were added and stirred. While stirring, the reaction temperature was gradually raised to 120° C. and the reaction was performed for 3 hours.

After the reaction, filtration under reduced pressure, washing with water, air-drying, and drying under reduced pressure to obtain magnetic substance-dispersed resin carrier core material particles 1.

<Production Example of Additive Particles 1 to 5, 7 and 8>
Additive particle 1 was prepared as follows.

100 parts by mass of strontium titanate (trade name: SW540, manufactured by Titanium Industry Co., Ltd.) was placed in a 500 ml-volume rubbing round bottom flask, and the system was placed in a nitrogen atmosphere, and then 300 parts by mass of anhydrous toluene was added. After cooling this with ice, 5 parts by mass of triethylamine, 10 parts by mass of dimethylaminopyridine, and 10 parts by mass of acetic anhydride were added, and the temperature was raised to 25° C. and stirred for 2 hours. The reaction was stopped by adding 100 parts by mass of a saturated sodium hydrogencarbonate aqueous solution, washed with water and a toluene solvent, air-dried and dried under reduced pressure to obtain chemically modified particles.

100 parts by mass of the obtained chemically modified particles were placed in a rubbing round bottom flask having a volume of 500 ml, and 200 parts by mass of methanol was added. After cooling this with ice, 30 parts by mass of calcium carbonate was added, the temperature was raised to 25° C., and the mixture was stirred for 2 hours. The reaction was stopped by adding 100 parts by mass of a saturated ammonium chloride aqueous solution, washed with water, air-dried and dried under reduced pressure to obtain additional particles 1.

Further, except that the particles or the treating agent was changed, the same treatment as that of the additive particles 1 was performed to obtain additive particles 2 to 5, 7 and 8. Table 1 shows the processing conditions of the obtained additive particles 1 to 5, 7 and 8.

<Production Example of Added Particle 6>
The additive particles 6 were prepared as follows.

100 parts by mass of carbon black (#4400, manufactured by Tokai Carbon Co., Ltd.) was placed in a cylindrical ozonizer in a 500 mL volume rubbing round bottom flask. Subsequently, an ozone generator (KQS-120, manufactured by Kotohira Kogyo Co., Ltd.) was used to generate 5 parts by mass of ozone per hour, and under an ozone atmosphere, the treatment temperature was kept at 40° C. and oxidation treatment was carried out for 2 hours. Particle 6 was obtained.

Table 1 shows the processing conditions of the obtained additive particles 6.

<Production Example of Additive Particles 9 to 15>
The additive particles 9 were prepared as follows.

100 parts by mass of zinc oxide powder was placed in a rubbing round bottom flask having a volume of 500 ml, and the system was made into a nitrogen atmosphere, and then 300 parts by mass of anhydrous toluene was added. After cooling this with ice, 5 parts by mass of triethylamine, 10 parts by mass of dimethylaminopyridine, and 10 parts by mass of formate chloride were added, and the temperature was raised to 25° C. and stirred for 2 hours. The reaction was stopped by adding 100 parts by mass of a saturated aqueous solution of sodium hydrogen carbonate, washed with water and a solvent of toluene, and air-dried and dried under reduced pressure to obtain additional particles 9.

Further, except that the treatment agent and the treatment amount were changed, the same treatment as for the additive particles 9 was performed to obtain additive particles 10 to 15. Table 1 shows the processing conditions of the obtained added particles 9 to 15.

<Production Example of Added Particle 16>
As the additive particles 16, strontium titanate (trade name: SW540, manufactured by Titanium Industry Co., Ltd.) was used without any special treatment. Table 1 shows the processing conditions of the obtained additive particles 16.

<Production Example of Additive Particle 17>
The additive particles 17 were prepared as follows.

100 parts by mass of strontium titanate (trade name: SW540, manufactured by Titanium Industry Co., Ltd.) was placed in a round bottom flask having a volume of 500 ml, and the system was made to have a nitrogen atmosphere, and then 300 parts by mass of anhydrous dimethylformamide was added. This was ice-cooled, 10 parts by mass of imidazole and 10 parts by mass of t-butyldimethylsilyl chloride were added, the temperature was raised to 25° C., and the mixture was stirred for 20 hours. The reaction was stopped by adding 100 parts by mass of a saturated aqueous solution of sodium hydrogen carbonate, washed with water and a solvent of toluene, and air-dried and dried under reduced pressure to obtain additional particles 17. Table 1 shows the processing conditions for the obtained additive particles 17.

<Production Example of Magnetic Carriers 1 to 21>
(Intermediate resin layer forming step)
In a planetary motion type mixer (Nauta Mixer VN type manufactured by Hosokawa Micron Co., Ltd.) maintained under reduced pressure (1.5 kPa) at a temperature of 60° C., the resin solution 5 shown in Table 3 was added to the magnetic substance-dispersed resin carrier core material particles 100. It was added such that the solid content of the resin component was 2.0 parts by mass with respect to parts by mass. As a method of charging, a 1/3 amount of the resin solution was charged, and the solvent removal and coating operation were performed for 20 minutes. Next, a 1/3 amount of the resin solution was added, and the solvent removal and coating operation was performed for 20 minutes, and a 1/3 amount of the resin solution was added, and the solvent removal and coating operation were performed for 20 minutes.

Then, the resin composition-coated particles coated with the resin composition are transferred to a mixer (drum mixer UD-AT type manufactured by Sugiyama Heavy Industries, Ltd.) having a spiral blade in a rotatable mixing container. The mixing container was heat-treated for 2 hours at a temperature of 120° C. in a nitrogen atmosphere while stirring by rotating 10 times a minute. The obtained resin composition-coated particles were subjected to magnetic separation to separate low-magnetism products, passed through a sieve having an opening of 150 μm, and then classified by an air classifier to obtain resin composition-coated particles 1.
Similarly, resin composition-coated particles 2 to 20 were obtained using the resin solutions shown in Table 3.

(Surface resin layer forming step)
In a planetary motion type mixer (Nauta Mixer VN type manufactured by Hosokawa Micron Co., Ltd.) maintained at a temperature of 60° C. under reduced pressure (1.5 kPa), the resin solution 1 shown in Table 4 was coated with the above resin composition particles 1 and 100. It was added such that the solid content of the resin component was 2.0 parts by mass with respect to parts by mass. As a method of charging, a 1/3 amount of the resin solution was charged, and the solvent removal and coating operation were performed for 20 minutes. Next, a 1/3 amount of the resin solution was added, and the solvent removal and coating operation was performed for 20 minutes, and a 1/3 amount of the resin solution was added, and the solvent removal and coating operation were performed for 20 minutes.

After that, the surface-coated magnetic carrier is transferred to a mixer having a spiral blade in a rotatable mixing container (a drum mixer UD-AT type manufactured by Sugiyama Heavy Industries). The mixing container was heat-treated for 2 hours at a temperature of 120° C. in a nitrogen atmosphere while stirring by rotating 10 times a minute. The magnetic carrier 1 thus obtained was separated into a low magnetic force product by magnetic separation, passed through a sieve having an opening of 150 μm, and then classified by an air classifier to obtain a magnetic carrier 1.

Table 5 shows the manufacturing conditions of each step of the obtained magnetic carrier 1, and Table 6 shows the respective physical properties.

Further, magnetic carriers 2 to 21 were manufactured under the manufacturing conditions shown in Table 5, and the physical properties of these are shown in Table 6.

<Production Example of Toner 1>
Binder resin (polyester resin) 100 parts by mass C.I. I. Pigment Blue 15:3 4.5 parts by mass 1,4-di-t-butylsalicylic acid aluminum compound 0.5 parts by mass Normal paraffin wax (melting point: 78° C.) 6 parts by mass Using the ingredients of the above formulation, a Henschel mixer (FM-75J type, manufactured by Mitsui Mining Co., Ltd.), and then a feed amount of 10 kg/h with a twin-screw kneader (PCM-30 type, manufactured by Ikegai Iron and Steel Co., Ltd.) set to a temperature of 130° C. Was kneaded (the temperature of the kneaded material at the time of discharge was about 150° C.). The obtained kneaded product was cooled, coarsely crushed with a hammer mill, and then finely pulverized with a mechanical pulverizer (T-250: manufactured by Turbo Kogyo Co., Ltd.) at a Feed amount of 15 kg/hr. Then, particles having a weight average particle diameter of 5.5 μm, containing 55.6% by number of particles having a particle diameter of 4.0 μm or less, and containing 0.8% by volume of particles having a particle diameter of 10.0 μm or more are obtained. It was

The obtained particles were classified by using a rotary classifier (TTSP100, manufactured by Hosokawa Micron Corp.) to cut fine powder and coarse powder. Cyan toner particles 1 having a weight average particle diameter of 6.4 μm, an abundance of particles having a particle diameter of 4.0 μm or less of 25.8% by number, and containing 2.5 vol% of particles having a particle diameter of 10.0 μm or more. Got

Further, the following materials were charged into a Henschel mixer (FM-75 type, manufactured by Nippon Coke Co., Ltd.), the peripheral speed of the rotary blades was set to 35.0 (m/sec), and the mixture was mixed for 3 minutes to obtain a cyan toner. Cyan toner 1 was obtained by adhering silica and titanium oxide to the surfaces of particles 1.
Cyan toner particles 1 100 parts by mass Silica 3.5 parts by mass (Silica fine particles produced by the sol-gel method are subjected to surface treatment with hexamethyldisilazane treatment of 1.5% by mass and then adjusted to a desired particle size distribution by classification. .)
Titanium oxide 0.5 parts by mass (metatitanic acid having anatase-type crystallinity surface-treated with an octylsilane compound)

Further, among cyan toner particles 1, C.I. I. Pigment Blue 15:3:5 parts by mass, and C.I. I. Pigment Yellow 74: 7.0 parts by mass, C.I. I. Pigment Red 122: 6.3 parts by mass and carbon black: 5.0 parts by mass to obtain yellow, magenta and black toner particles 1, respectively.

Further, similarly to the cyan toner 1, yellow toner, magenta toner, and black toner 1 are obtained.

Table 7 shows the formulation and physical properties of the obtained toner.

[Example 1]
To 90 parts by mass of the magnetic carrier 1, 10 parts by mass of each color toner 1 was added and shaken by a shaker (YS-8D type: manufactured by Yayoi Co., Ltd.) to prepare 300 g of a two-component developer. The shaking condition of the shaker was 200 rpm for 2 minutes.

On the other hand, 90 parts by mass of each color toner 1 is added to 10 parts by mass of the magnetic carrier 1, and is mixed for 5 minutes by a V-type mixer in a room temperature and normal humidity 23° C./50% RH (hereinafter N/N) environment, and replenished. A developer for use was obtained.

100 parts by mass of the two-component developer and the replenishing developer were dried at 25° C. under reduced pressure for 5 hours while stirring.

The following evaluations were performed using the two-component developer and the replenishment developer.

As the image forming apparatus, a Canon color copying machine imageRUNNER ADVANCE C9075 PRO remodeling machine was used. A two-component developer was placed in each color developing device, a replenishment developer container containing each color replenishment developer was set, an image was formed, and various evaluations were performed.

The copying machine is left to stand at a temperature of 30° C./humidity of 80 RH% (hereinafter “H/H”) for 24 hours and then at a temperature of 23° C./humidity of 5 RH% (hereinafter “N/L”) for 24 hours. The environmental state when changed over time is H/Ha.

As a durability test, a FFH output chart with an image ratio of 1% was used as a durability test under a printing environment of a temperature of 23° C. and a humidity of 5 RH% (hereinafter “N/L”). Further, under a printing environment of temperature 30° C./humidity 80 RH% (hereinafter “H/H”), an FFH output chart with an image ratio of 40% was used. FFH is a value in which 256 gradations are displayed in hexadecimal notation, 00h is the first gradation of 256 gradations (white background portion), and FFH is the 256th gradation of 256 gradations (solid portion). ..

The type of output image and the number of output sheets were changed according to each evaluation item.
conditions:
Paper laser beam printer paper ^{CS-814 (81.4g / m 2} )
(Canon Marketing Japan Inc.)
Image formation speed A4 size, modified to output at 80 (sheets/min) in full color
It was
Development conditions The development contrast can be adjusted to an arbitrary value, and automatic correction by the main unit is activated.
It was modified so that it would not exist.
The voltage (Vpp) between the peaks of the alternating electric field has a frequency of 2.0 kHz and Vpp.
Remodeled to change from 0.7kV to 1.8kV in 0.1kV steps
It was
Each color was modified to output images in a single color.

Each evaluation item is shown below.

(1) White space Initially under H/Ha environment, and immediately after 2000 continuous sheets, halftone horizontal band (30H width 10mm) and solid horizontal band (FFH width 10mm) alternate in the transport direction of transfer paper. Output the chart arranged in. The image is read by a scanner and binarized. The luminance distribution (256 gradations) of a certain line in the transport direction of the binarized image was taken. A tangent line is drawn to the halftone brightness at that time, and the area of the brightness (area: sum of the number of brightnesses) that deviates from the tangent line at the rear end of the halftone area until it intersects with the solid area brightness is defined as the whiteout degree, and It evaluated based on. The evaluation was performed with a single cyan color.
A: less than 20 B: 20 or more and less than 30 C: 30 or more and less than 40 D: 40 or more and less than 50 E: 50 or more

(2) Change in gradation in H/Ha Under the H/Ha environment, 10 images with each pattern set to the density shown below are output. The image is calculated by an X-Rite color reflection densitometer (Color reflection densitometer X-Rite 404A) under H/Ha environment, and the average value of each pattern of 10 images is calculated.
Pattern 1: 0.10 to 0.15
Pattern 2: 0.25 to 0.30
Pattern 3: 0.45 to 0.50
Pattern 4: 0.65 to 0.70
Pattern 5: 0.85 to 0.90
Pattern 6: 1.05 to 1.10
Pattern 7: 1.25 to 1.30
Pattern 8: 1.45 to 1.50

The judgment criteria are as follows.
A: All pattern images satisfy the above density range B: One pattern image is outside the density range C: Two pattern images are outside the density range D: Three pattern images are above the density range Out of range E: Four or more pattern images are out of the density range above

(3) Variation in tint of mixed color after endurance Variation in tint of red, which is a mixed color of yellow and magenta, was evaluated.

Before the durability test, the development contrast was adjusted so that the solid image reflection density on the monochromatic paper of each color was 1.5. After that, the initial solid image of red and the solid image of red immediately after continuous printing of 20,000 sheets under H/H environment were output to confirm the degree of tint variation before and after running.

<Measurement method of color difference>
The difference in tint variation can be obtained by measuring a ^* and b ^* using a SpectroScan Transmission (manufactured by GretagMacbeth). An example of specific measurement conditions is shown below.

(Measurement condition)
Observation light source: D50
Field of view: 2°
Concentration: DIN NB
White reference: Pap
Filter: None Generally, a ^* and b ^* are values used in the L ^* a ^* b ^* color system, which is a useful means for numerically expressing colors. Both a ^* and b ^* represent a hue. The hue is a scale of hue such as red, yellow, green, blue, and purple. Each of a ^* and b ^* indicates a color direction, where a ^* indicates a red-green direction and b ^* indicates a yellow-blue direction. In the present invention, the difference (ΔC) in tint variation is defined as follows.
[Delta] C = {(the HH environment durability after image a ^* -HH environment of the initial image a ^{*) 2}
+ (B in HH environment durability after image b ^* -HH environment of the initial image ^{*) 2} 1/2}
For the measurement, arbitrary 5 points in the image were measured and the average value was obtained. As the evaluation method, a ^* and b ^* of the solid image output in each environment were measured, and ΔC was obtained by the above formula.
A: 0≦ΔC<2.0
B: 2.0≦ΔC<3.5
C: 3.5≦ΔC<5.0
D: 5.0≦ΔC<6.5
E: 6.5≦ΔC

(4) Carrier Adhesion After Durability After carrying out an evaluation of durability image output under H/H environment, carrier adhesion was evaluated. The 00H image and the FFH image were output, the power was turned off during the image output, and a transparent adhesive tape was brought into close contact with the electrostatic latent image bearing member before being cleaned for sampling. Then, the number of magnetic carrier particles adhering to the electrostatic latent image bearing member in 3 cm×3 cm was counted, the number of adhering carrier particles per 1 cm ² was calculated, and evaluated according to the following criteria. The evaluation was performed with a single cyan color.
A: 2 or less B: 3 or more and 4 or less C: 5 or more and 6 or less D: 7 or more and 8 or less E: 8 or more

(5) Roughness after Half-Tone Image Durability After initial and endurance image output evaluation (50,000 sheets) under H/H environment, one half-tone image (30H) was printed on A4. For the image, an area of 1000 dots was measured using a digital microscope VHX-500 (lens wide range zoom lens VH-Z100 manufactured by Keyence Corporation). The number average (S) of dot areas and the standard deviation (σ) of dot areas were calculated, and the dot reproducibility index was calculated by the following formula. Then, the roughness of the halftone image was used as the dot reproducibility index (I), and the difference from the initial value was compared.
Dot reproducibility index (I)=σ/S×100

As the evaluation standard for rustling, cyan single color was used, and evaluation was performed according to the following standards.
A: Difference from initial stage is less than 3.0 B: Difference from initial stage is 3.0 to less than 5.0 C: Difference from initial stage is 5.0 to less than 8.0 D: Difference from initial stage is 8. 0 or more and less than 10.0 E: Difference from the initial value is 10.0 or more

(6) Post-durability developing property The evaluation of the post-durability developing property was performed under a H/H environment with the initial Vpp fixed at 1.3 kV and the density when the density of the cyan single-color solid image was 1.50 (reflection density). The last potential was set. After running 20,000 sheets at that setting, Vpp was 1.3 kV and the contrast potential at which the image density was 1.50 was obtained, and the difference from the initial value was compared. The evaluation was performed with a single cyan color. The reflection density was measured using a spectral densitometer 500 series (manufactured by X-Rite).

Developability Evaluation Criteria A: Difference from initial, less than 40V B: Difference from initial, 40V to less than 60V C: Difference from initial, 60V to less than 80V D: Difference from initial, 80V to 100V Less than E: 100V or more difference from the initial

(7) Change in gradation before and after endurance An image in which each pattern is set to the density shown below by default is output immediately after 2000 sheets have been passed under the H/H environment. Immediately after, the deviation in gradation was confirmed. The image was judged by measuring the respective image densities with an X-Rite color reflection densitometer (Color reflection densitometer X-Rite 404A). The evaluation was performed with a single cyan color.
Pattern 1: 0.10 to 0.13
Pattern 2: 0.25 to 0.28
Pattern 3: 0.45 to 0.48
Pattern 4: 0.65 to 0.68
Pattern 5: 0.85 to 0.88
Pattern 6: 1.05 to 1.08
Pattern 7: 1.25 to 1.28
Pattern 8: 1.45 to 1.48

The judgment criteria are as follows.
A: All pattern images satisfy the above density range B: One pattern image is outside the density range C: Two pattern images are outside the density range D: Three pattern images are above the density range Out of range E: Four or more pattern images are out of the density range above

(8) Overall Judgment The evaluation ranks in the above evaluation items (1) to (7) were digitized, and the total value was judged according to the following criteria. The evaluation ranks other than the evaluation item (6) are “A=5, B=4, C=3, D=2, E=0”, and the evaluation rank of the evaluation item (6) is “A=10”. , B=8, C=6, D=4, E=2”.
A: 35 or more B: 28 or more and 34 or less C: 20 or more and 27 or less D: 15 or more and 19 or less E: 14 or less

In Example 1, the results were very good in all evaluations. The evaluation results are shown in Table 8.

[Examples 2, 3, 4]
In the same manner as in Example 1, magnetic carriers 2, 3 and 4 were used to prepare a two-component developer and a replenishment developer in the same ratio as in Example 1. Evaluation was performed in the same manner as in Example 1 except that the obtained developer was used.

In Examples 2, 3 and 4, the added particle species are different from those in Example 1, but in all the evaluations, the results were very good. The evaluation results are shown in Table 8.

[Examples 5 and 6]
In the same manner as in Example 1, the magnetic carriers 5 and 6 were used to prepare a two-component developer and a replenishment developer in the same ratio as in Example 1. Evaluation was performed in the same manner as in Example 1 except that the obtained developer was used.

In Examples 5 and 6, the added particle species and the resin species of the intermediate resin layer were different from those in Example 1, but the results were very good in all evaluations. The evaluation results are shown in Table 8.

[Example 7]
In the same manner as in Example 1, the magnetic carrier 7 was used to prepare a two-component developer and a replenishment developer in the same ratio as in Example 1. Evaluation was performed in the same manner as in Example 1 except that the obtained developer was used.

Example 7 differs from Example 1 in that it contains two types of additive particles, but in all evaluations, the result was very good. The evaluation results are shown in Table 8.

[Example 8]
In the same manner as in Example 1, the magnetic carrier 8 was used to prepare a two-component developer and a replenishment developer in the same ratio as in Example 1. Evaluation was performed in the same manner as in Example 1 except that the obtained developer was used.

Example 8 differs from Example 1 in the resin species of the surface resin layer. Polystyrene resin is used for the surface resin layer. Therefore, the value of change in water content was large. As a result, there was a slight effect on the evaluation results of white spots under the NL environment, gradation changes, and color changes after endurance under the HH environment, but other evaluations were very good results. It was The evaluation results are shown in Table 8.

[Example 9]
In the same manner as in Example 1, the magnetic carrier 9 was used to prepare a two-component developer and a replenishing developer in the same ratio as in Example 1. Evaluation was performed in the same manner as in Example 1 except that the obtained developer was used.

Example 9 differs from Example 8 in the resin type of the intermediate resin layer. Polystyrene resin is used for the intermediate resin layer. Therefore, the value of the change in water content became larger. As a result, there was a slight effect on white spots under the NL environment, gradation changes, color changes after endurance under the HH environment, rustiness, and sticky carry, but the other evaluations were very small. It was a good result. The evaluation results are shown in Table 8.

[Examples 10 and 11]
In the same manner as in Example 1, the magnetic carriers 10 and 11 were used to prepare a two-component developer and a replenishment developer in the same ratio as in Example 1. Evaluation was performed in the same manner as in Example 1 except that the obtained developer was used.

Examples 10 and 11 are different from Example 9 in the film pressure of the surface resin layer, the mass part of the added particles, and the average diameter of the added particles. Therefore, the value of the change in water content became larger. As a result, there was a slight effect on the evaluation results of white spots and gradation changes under the NL environment, but other evaluations were good results. The evaluation results are shown in Table 8.

[Examples 12 and 13]
In the same manner as in Example 1, magnetic carriers 12 and 13 were used to prepare a two-component developer and a replenishing developer in the same ratio as in Example 1. Evaluation was performed in the same manner as in Example 1 except that the obtained developer was used.

Examples 12 and 13 are different from Examples 10 and 11 in the functional group species, the film pressure of the surface resin layer, the mass part of the added particles, and the average diameter of the added particles. Therefore, the value of the change in water content became larger. As a result, there was a slight effect on the evaluation result of the change in color tone after endurance under HH environment, roughness, and developability, but other than that, the result was slightly good. The evaluation results are shown in Table 8.

[Example 14]
In the same manner as in Example 1, the magnetic carrier 14 was used to prepare a two-component developer and a replenishing developer in the same ratio as in Example 1. Evaluation was performed in the same manner as in Example 1 except that the obtained developer was used.

Example 14 differs from Example 13 in that the concentration of functional groups on the surface of the added particles is low. Therefore, the value of the change in water content became larger. As a result, there was a slight effect on the tone change after endurance and the evaluation result with solid carry, but other than that, the results were rather good. The evaluation results are shown in Table 8.

[Example 15]
In the same manner as in Example 1, the magnetic carrier 15 was used to prepare a two-component developer and a replenishing developer in the same ratio as in Example 1. Evaluation was performed in the same manner as in Example 1 except that the obtained developer was used.

Example 15 differs from Example 14 in that the concentration of functional groups on the surface of the added particles is low. Therefore, the value of the change in water content became larger. As a result, the evaluation results in white spots under the NL environment were affected, but other than that, the results were rather good. The evaluation results are shown in Table 8.

Example 16
In the same manner as in Example 1, a two-component type developer and a replenishing developer were prepared using the magnetic carrier 16 in the same ratio as in Example 1. Evaluation was performed in the same manner as in Example 1 except that the obtained developer was used.

Example 16 differs from Example 15 in that the concentration of functional groups on the surface of the added particles is low. Therefore, the value of change in water content was large. As a result, the change in color tone after endurance under the HH environment and the evaluation result on rustling were affected, but other than that, the result was rather good. The evaluation results are shown in Table 8.

Example 17
In the same manner as in Example 1, the magnetic carrier 17 was used to prepare a two-component developer and a replenishing developer in the same ratio as in Example 1. Evaluation was performed in the same manner as in Example 1 except that the obtained developer was used.

Example 17 differs from Example 16 in that the wettability with methanol is high. Therefore, the value of the change in water content became larger. As a result, the change in tone after endurance under the HH environment and the evaluation result of rubbish were affected, but other than that, there was no problem. The evaluation results are shown in Table 8.

[Example 18]
In the same manner as in Example 1, the magnetic carrier 18 was used to prepare a two-component developer and a replenishing developer in the same ratio as in Example 1. Evaluation was performed in the same manner as in Example 1 except that the obtained developer was used.

Example 18 differs from Example 17 in that the wettability with methanol is high. Therefore, the value of the change in water content became larger. As a result, the change in tone under the NL environment and the evaluation result with solid carry under the HH environment deteriorated, but otherwise there were no problems. The evaluation results are shown in Table 8.

[Comparative Example 1]
In the same manner as in Example 1, using the magnetic carrier 19, a two-component type developer and a replenishment developer were prepared in the same ratio as in Example 1. Evaluation was performed in the same manner as in Example 1 except that the obtained developer was used.

Comparative Example 1 differs from Example 1 in that the intermediate resin layer does not contain additional particles. As a result, the water retention in the surface resin is reduced, so that desorption of water becomes remarkable and the value of change in water content becomes larger. As a result, the evaluation results deteriorated. The evaluation results are shown in Table 8.

[Comparative Example 2]
As in Example 1, the magnetic carrier 20 was used to prepare a two-component developer and a replenishment developer in the same ratio as in Example 1. Evaluation was performed in the same manner as in Example 1 except that the obtained developer was used.

Comparative Example 2 is different from Example 1 in that hydrophilic treatment is not performed on the added particles. Therefore, the value of methanol wettability was large, and the value of change in water content was larger. As a result, the evaluation results deteriorated. The evaluation results are shown in Table 8.

[Comparative Example 3]
In the same manner as in Example 1, the magnetic carrier 21 was used to prepare a two-component developer and a replenishment developer in the same ratio as in Example 1. Evaluation was performed in the same manner as in Example 1 except that the obtained developer was used.

Comparative Example 3 is different from Example 1 in that the added particles are subjected to a hydrophobic treatment. Therefore, the value of methanol wettability was large, and the value of change in water content was larger. As a result, the evaluation results deteriorated. The evaluation results are shown in Table 8.

1, 1K, 1Y, 1C, 1M: electrostatic latent image carrier, 2, 2K, 2Y, 2C, 2M: charger, 3K, 3Y, 3C, 3M: exposure unit, 4, 4K, 4Y, 4C 4M: developing device, 5: developing container, 6, 6K, 6Y, 6C, 6M: developer carrier, 7: magnet, 8: regulating member, 9: intermediate transfer member, 10K, 10Y, 10C, 10M: intermediate Transfer charger, 11: Transfer charger, 12: Transfer material (recording medium), 13: Fixing device, 14: Intermediate transfer member cleaner, 15, 15K, 15Y, 15C, 15M: Cleaner, 16: Pre-exposure

Claims (12)

A magnetic material-dispersed resin carrier core material having a magnetic material and a binder resin, and a magnetic carrier having a resin coating layer on the surface of the magnetic material-dispersed resin carrier core material,
The resin coating layer has a surface resin layer, a resin composition present between the magnetic material-dispersed resin carrier core material and the surface resin layer,
The resin composition,
(I) a resin,
(Ii) From oxide particles of a metal element having an ester group and/or a carboxyl group on the surface, silica particles having an ester group and/or a carboxyl group on the surface , and carbon black having an ester group and/or a carboxyl group on the surface is selected from the group consisting of containing and one or more kinds of particles child,
The particles of (ii) have a methanol wettability of 85% or less and a functional group concentration of the ester group and/or the carboxyl group of 20% or more.
A magnetic carrier characterized by the above. The magnetic carrier according to claim 1, wherein the hydrophilically treated oxide particles of the metal element are one kind or two or more kinds selected from TiO ₂ , Al ₂ O ₃ , MgO, and SrTiO ₃ . The volume average diameter of the primary particles of the hydrophilic treated particles, the magnetic carrier of claim 1 or 2 is 10nm or more 1000nm or less. Said resin composition, when the resin is 100 parts by mass, the hydrophilic treated particles 1.0 parts by mass or more, in any one of claims 1 to 3 containing less 20.0 parts by The magnetic carrier described. Thickness of the resin coating layer, the magnetic carrier according to any one of claims 1 to 4 is 0.01μm or 4.00μm or less. Resin in the resin composition, the magnetic according to any one of claims 1 to 5, which is a polymer or a thermosetting silicone resin is obtained by polymerizing a monomer containing an acrylic acid ester monomer or a methacrylic acid ester monomer Career. The magnetic carrier according to any one of claims 1 to 6 , wherein the resin coating layer contains a polymer obtained by polymerizing a monomer containing an acrylic acid ester monomer or a methacrylic acid ester monomer. The magnetic carrier has a moisture content (A) of the magnetic carrier when left in an environment of temperature 30° C. and humidity 80% for 24 hours, and a moisture content of the magnetic carrier for 24 hours in an environment of temperature 30° C. and humidity 80%, 23 ° C., a humidity of 5% of the magnetic carrier when left for 24 hours in an environment moisture content change of the moisture content (B) (a-B) is of claims 1 to 7 or less 0.80 mass% The magnetic carrier according to any one of claims. A two-component developer containing a toner having a toner particle containing a binder resin, a colorant and a release agent, and a magnetic carrier,
A two-component developer, wherein the magnetic carrier is the magnetic carrier according to any one of claims 1 to 8 . A charging step of charging the electrostatic latent image carrier, an electrostatic latent image forming step of forming an electrostatic latent image on the surface of the electrostatic latent image carrier, the electrostatic latent image using a two-component developer A developing step of developing and forming a toner image, a transferring step of transferring the toner image onto a transfer material with or without an intermediate transfer body, and a fixing step of fixing the transferred toner image onto the transfer material. An image forming method having:
An image forming method, wherein the two-component developer according to claim 9 is used as the two-component developer. A charging step of charging the electrostatic latent image carrier, an electrostatic latent image forming step of forming an electrostatic latent image on the surface of the electrostatic latent image carrier, and a two-component developer in the developing device for the electrostatic latent image. A developing step of developing with the use of a toner image, a transferring step of transferring the toner image onto a transfer material with or without an intermediate transfer member, and a fixing step of fixing the transferred toner image onto the transfer material. The developer for replenishment is replenished to the developing device according to the decrease in the toner concentration of the two-component developer in the developing device, and excess magnetic carrier in the developing device is removed from the developing device as necessary. A replenishing developer for use in a discharged image forming method,
The replenishment developer contains a replenishment magnetic carrier and a toner having toner particles containing a binder resin, a colorant and a release agent,
The replenishing developer contains the toner in an amount of 2 parts by mass or more and 50 parts by mass or less with respect to 1 part by mass of the replenishing magnetic carrier,
The replenishment developer is characterized in that the replenishment magnetic carrier is the magnetic carrier according to any one of claims 1 to 9 . A charging step of charging the electrostatic latent image carrier, an electrostatic latent image forming step of forming an electrostatic latent image on the surface of the electrostatic latent image carrier, and a two-component developer in the developing device for the electrostatic latent image. A developing step of developing with the use of a toner image, a transferring step of transferring the toner image onto a transfer material with or without an intermediate transfer member, and a fixing step of fixing the transferred toner image onto the transfer material. The developer for replenishment is replenished to the developing device according to the decrease in the toner concentration of the two-component developer in the developing device, and excess magnetic carrier in the developing device is removed from the developing device as necessary. An ejected image forming method,
The replenishment developer contains a replenishment magnetic carrier and a toner having toner particles containing a binder resin, a colorant and a release agent,
The replenishing developer contains the toner in an amount of 2 parts by mass or more and 50 parts by mass or less with respect to 1 part by mass of the replenishing magnetic carrier,
The image forming method, wherein the magnetic carrier for replenishment is the magnetic carrier according to any one of claims 1 to 9 .

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