JP7614811B2 - Two-component developer - Google Patents

Description

The present invention relates to a two-component developer used in an electrophotographic image forming apparatus.

In recent years, there has been an increasing demand for electrophotographic image forming devices to operate at higher speeds, with higher resolution and more stable image quality. To meet these demands, electrophotographic developers require magnetic carriers with high performance, such as excellent charging properties.

Patent document 1 discloses that a developer composition having carrier particles with high triboelectric charging and constant electrical conductivity can be provided by using a carrier having a core and a polymer having alkylaminoalkyl methacrylate units covering the core.

JP 2000-75558 A

However, as a result of extensive research by the inventors into the developer composition described in Patent Document 1, they realized that further improvements were needed in terms of the density stability of output images associated with environmental changes and excellent density reproducibility in high-temperature, high-humidity environments.

The present invention provides a two-component developer that has excellent density reproducibility in high-temperature, high-humidity environments and has excellent density stability even when the environment changes.

The present invention provides a two-component developer containing a toner and a magnetic carrier,
the toner comprises toner particles and organosilicon polymer particles on the surfaces of the toner particles;
The organosilicon polymer particles have a T3 unit structure represented by the following formula (1):
R-SiO _3/2 ... (1)
(In formula (1), R represents an alkyl group having 1 to 6 carbon atoms or a phenyl group.)
The magnetic carrier contains magnetic carrier core particles and magnetic carrier particles having a resin coating layer on the surface of the magnetic carrier core particles,
The resin coating layer contains a resin A having a monomer unit A1 containing a nitrogen atom,
In the measurement of carbon element, oxygen element, silicon element, nitrogen element, and iron element of the magnetic carrier particles by X-ray photoelectron spectroscopy,
When the ratio of nitrogen elements on the surface of the magnetic carrier particle is defined as N1 (atom %), the N1 is 0.0 to 0.7,
The two-component developer is characterized in that, when the thickness of the resin coating layer is d (μm) and the ratio of nitrogen elements at a position 0.95d from the surface of the magnetic carrier particle is N2 (atom %), N2 is 0.8 to 13.0.

The present invention provides a two-component developer that has excellent density stability even when the environment changes, and has excellent density reproducibility in high-temperature, high-humidity environments.

1 is a schematic diagram of a cross section of a magnetic carrier according to the present invention and a measurement position of X-ray photoelectron spectroscopy (hereinafter also referred to as XPS). 1 is a schematic diagram showing one embodiment of a cross section of a magnetic carrier according to the present invention.

When a numerical range is expressed as "xx or more and xx or less" or "xx to xx", it means that the numerical range includes the upper and lower limits, which are the endpoints, unless otherwise specified. When a numerical range is stated in stages, the upper and lower limits of each numerical range can be combined in any way.

(Meth)acrylate means acrylate and/or methacrylate, and (meth)acrylic acid means acrylic acid and/or methacrylic acid.

A monomer unit is a unit that constitutes a polymer, and refers to the reacted form of a monomer (polymerizable monomer). For example, one section of carbon-carbon bonds in the main chain of a polymer formed by polymerization of a vinyl monomer is one monomer unit. A vinyl monomer can be represented by the following formula (Z), and a vinyl monomer unit is a structural unit of a polymer, and is the reacted form of a monomer represented by the following formula (Z). A monomer unit may also be simply referred to as a "unit."

(In formula (Z), _R represents a hydrogen atom or an alkyl group, and _R represents an arbitrary substituent.)
<Background to the invention>
It is known that the resin coating layer of the magnetic carrier in the two-component developer improves the chargeability of the toner by containing a resin having a monomer unit containing a nitrogen atom such as an amino group. However, when such a resin is present on the surface of the magnetic carrier, the chargeability in a normal temperature and low humidity environment tends to be high. As a result, the charge amount of the toner in a low temperature and low humidity environment tends to be high compared to the charge amount of the toner in a high temperature and high humidity environment, and therefore the density and color of the image tend to change with such environmental changes.

The inventors have discovered that by containing the above-mentioned resin in the resin coating layer of the magnetic carrier and controlling the nitrogen atom ratio in the outermost layer of the resin coating layer to be below a specific ratio, excellent concentration stability can be achieved even when the environment changes.

The inventors further investigated the two-component developer having the magnetic carrier and found that the density reproducibility of the output image may be insufficient when the image is output after being left in a high-temperature, high-humidity environment for a long time. The inventors speculate that one of the reasons for this is that the magnetic carrier is easily charged, so that materials added to the toner in the two-component developer tend to adhere electrostatically to the magnetic carrier. For the magnetic carrier when the density reproducibility of the output image is insufficient, the magnetic carrier was observed using a scanning electron microscope and surface analysis using X-ray photoelectron spectroscopy was performed to confirm that materials added to the toner tend to adhere to the magnetic carrier.

As a result of the investigations conducted by the inventors based on the above considerations, it was found that a two-component developer having the above-mentioned constituent requirements can have excellent density stability even when the environment changes, and can also have excellent density reproducibility in high-temperature, high-humidity environments. The hypothesized mechanism and each of the constituent requirements are explained in detail below.

<Mechanism by which the effects of the present invention are manifested>
The present inventors consider the mechanism by which the effects of the present invention are manifested as follows.

The resin coating layer contains resin A, which has a monomer unit containing nitrogen atoms, and the concentration of nitrogen atoms near the core of the magnetic carrier is within a specific range, which is thought to make it easier for the magnetic carrier to be sufficiently charged even in a high-temperature, high-humidity environment, making it easier to obtain a stable image density.

In addition, by keeping the concentration of nitrogen atoms in the outermost layer of the magnetic carrier below a specific ratio, it is believed that the magnetic carrier is less likely to become overcharged in a low-humidity environment, making it easier to obtain a stable image density.

Furthermore, organosilicon polymer particles having the T3 unit structure represented by formula (1) on the surface of toner particles are believed to be less susceptible to large electrostatic adhesion forces and also tend to have excellent elasticity. As a result, the organosilicon polymer particles are less likely to have excessive adhesion forces to the magnetic carrier, and are also believed to be less likely to separate from the toner particle surface even when the toner is subjected to stress, which tends to result in a two-component developer with excellent density reproducibility in high-temperature, high-humidity environments.

<Organosilicon Polymer Particles>
The toner comprises toner particles and organosilicon polymer particles on the surfaces of the toner particles;
The organosilicon polymer particles have a T3 unit structure represented by the following formula (1).

R-SiO _3/2 ... (1)
(In formula (1), R represents an alkyl group having 1 to 6 carbon atoms or a phenyl group.)
The organosilicon polymer particles according to the present invention are particles that have organic groups and are composed of polyorganosiloxane in which the main polymer skeleton is a siloxane bond (Si--O--).

The above R-SiO _3/2 means a structure in which a silicon atom is bonded to three oxygen atoms and one alkyl or phenyl group, and each of the three oxygen atoms is bonded to two silicon atoms. In other words, the above three oxygen atoms are oxygen atoms constituting a siloxane bond.

The amount of organosilicon polymer contained in the toner is preferably 0.1 to 30.0% by mass, more preferably 0.1 to 10.0% by mass, even more preferably 1.0 to 10.0% by mass, and even more preferably 1.0 to 5.0% by mass.

<T3 unit structure>
The organosilicon polymer particles having the above T3 unit structure are less likely to develop large electrostatic adhesion and tend to have excellent elasticity, and the present inventors believe that the reason for this is as follows.

The inventors speculate that the organosilicon polymer particles having the above T3 unit structure are less likely to have an excessively high charge density and are more likely to be uniform due to the balance between the content ratio of the organic portion represented by R and the siloxane bond portion, which makes it easier for the electrostatic adhesion force to be small.

In addition, unlike particles that are composed only of silicon and oxygen atoms, such as polysiloxane skeletons, organosilicon polymer particles have an organic portion represented by R, which is thought to make them more likely to have excellent elasticity.

The T3 unit structure can be incorporated into the organosilicon polymer particles by using a trifunctional silane, described below, as a monomer during the production of the organosilicon polymer particles.

<Relative dielectric constant εr>
The present inventors speculate that the electrostatic adhesion of the organosilicon polymer particles is due to electrostatic interactions at the microscopic level, specifically, electrostatic adhesion due to permanent dipoles and excited dipoles at the molecular level, known as van der Waals forces.

Therefore, we focused on the dielectric constant as an indicator of the electrical properties of organosilicon polymer particles. When a two-component developer is used in an electrophotographic image forming device, an electric field such as a development bias is applied, so we thought that the degree of polarization of the molecules in the electric field, i.e., the dielectric constant, would be an appropriate indicator of electrostatic adhesion. It is believed that the smaller the dielectric constant, the smaller the electrostatic adhesion of the organosilicon polymer particles will be, and it is easier to obtain a two-component with excellent density reproducibility in high-temperature, high-humidity environments.

For the above reasons, the relative dielectric constant εr of the organosilicon polymer particles measured at 10 Hz is preferably 4.0 or less, more preferably 2.5 or less. There is no particular lower limit, but it is 0.0 or more.

It has also been found that by keeping the relative dielectric constant within the above range, it becomes easier to obtain a two-component developer with excellent charging stability, even when continuous image output is performed in a room temperature, low humidity environment. This is thought to be because the organosilicon polymer particles are less likely to electrostatically adhere to the magnetic carrier even when the magnetic carrier in the two-component developer becomes overcharged in the above environment.

The above-mentioned relative dielectric constant εr can be controlled by adjusting the balance between the content of the organic portion and the siloxane bond portion in the organosilicon polymer particles.

<Water adsorption amount>
In addition, the water adsorption amount of the organosilicon polymer particles at a relative humidity of 80% is preferably 15 cm ³ g ^-1 or more and 30 cm ³ g ^-1 or less. If the water adsorption amount is 30 cm ³ g ^-1 or less, it is considered that the organosilicon polymer particles are difficult to adhere to the magnetic carrier. Therefore, it is preferable that it is 30 cm ³ g ^-1 or less, and more preferable that it is 25 cm ³ g ^-1 or less. Furthermore, if it is 15 cm ³ g ^-1 or more, it is considered that the two-component developer can appropriately retain water, and therefore it can appropriately transfer water to the carrier when the environment changes, and the image density is unlikely to change. Therefore, it is preferable that it is 15 cm ³ g ^-1 or more, and more preferable that it is 18 cm ³ g ^-1 or more.

The amount of water adsorption can be controlled by the content of siloxane bonds in the organosilicon polymer particles.

<Number average particle size>
It is also preferred that the organosilicon polymer particles have a number average particle size of 30 nm or more and 300 nm or less.

If the diameter is 30 nm or more, it is believed that the organosilicon polymer particles are less likely to be embedded even when stress is applied to the toner inside the developing device. Therefore, it is preferable that the diameter is 30 nm or more, and more preferable that the diameter is 80 nm or more. Also, if the diameter is 300 nm or less, it is believed that the organosilicon polymer particles are less likely to detach from the toner particle surface. Therefore, it is preferable that the diameter is 300 nm or less, and more preferable that the diameter is 150 nm or less.

<Method of Producing Organosilicon Polymer Particles>
There are no particular limitations on the method for producing the organosilicon polymer particles, and they can be obtained, for example, by dropping a silane compound into water, carrying out hydrolysis and condensation reactions in the presence of a catalyst, and then filtering and drying the resulting suspension. The number average particle size of the primary particles of the organosilicon polymer particles can be controlled by the type of catalyst, the compounding ratio, the reaction start temperature, the dropping time, etc.

Catalysts include acidic and basic catalysts. This is because the use of an acidic catalyst makes it easier for the hydrolysis reaction to proceed, while the use of a basic catalyst makes it easier for the condensation reaction to proceed.

Examples of acidic catalysts include hydrochloric acid, hydrofluoric acid, sulfuric acid, and nitric acid, while examples of basic catalysts include aqueous ammonia, sodium hydroxide, and potassium hydroxide.

The organosilicon polymer particles having the above T3 unit structure can be obtained by polymerizing the following monomer raw materials.
Monomer raw material: A monomer raw material containing an organosilicon compound represented by the following formula (4), in which R ⁷ in the following formula (4) is an alkyl group or a phenyl group having 1 to 6 carbon atoms, and R ⁸ , R ⁹ , and R ¹⁰ are each independently a hydrolyzable group.

Hereinafter, the above organosilicon compound will also be referred to as a trifunctional silane. The monomer raw material may contain one type of trifunctional silane alone, or two or more types of trifunctional silanes.

A hydrolyzable group refers to a functional group that is converted to a hydroxy group after a hydrolysis reaction.

The types of hydrolyzable groups include at least one substituent selected from the group consisting of halogen functional groups (fluoro, chloro, bromo, and iodine groups), alkoxy groups, and acyloxy groups. Among the above, alkoxy groups and acetoxy groups are preferred, and at least one substituent selected from the group consisting of methoxy groups, ethoxy groups, propoxy groups, and acetoxy groups is more preferred. When these hydrolyzable groups are hydrolyzed, they are converted into a silyl alcohol structure, which is preferred because it is believed to be easy to form a polysiloxane skeleton or a crosslinked structure by polycondensation from there.

The monomer raw material may contain, for example, the following compounds.
A compound in which R ⁷ , R ⁸ , R ⁹ , and R ¹⁰ in formula (4) are each independently a hydrolyzable group (hereinafter, referred to as a tetrafunctional silane);
An organosilicon compound in which R ⁷ and R ⁸ in the formula (4) are each independently an alkyl group having 1 to 6 carbon atoms or a phenyl group, and R ⁹ and R ¹⁰ are each independently a hydrolyzable group (hereinafter, bifunctional silane);
An organosilicon compound represented by the formula (4) in which R ⁷ , R ⁸ , and R ⁹ are each independently an alkyl group having 1 to 6 carbon atoms or a phenyl group, and R ¹⁰ is a hydrolyzable group (hereinafter, monofunctional silane).

In order to easily incorporate sufficient amounts of the above T3 unit structure into the organosilicon polymer particles, it is preferable that the above trifunctional silane is 50 mol % or more relative to the number of moles of all monomers contained in the monomer raw material.

Examples of the tetrafunctional silanes include tetramethoxysilane, tetraethoxysilane, and tetraisocyanate silane.

The above trifunctional silanes include methyltrimethoxysilane, methyltriethoxysilane, methyldiethoxymethoxysilane, methylethoxydimethoxysilane, methyltrichlorosilane, methylmethoxydichlorosilane, methylethoxydichlorosilane, methyldimethoxychlorosilane, methylmethoxyethoxychlorosilane, methyldiethoxychlorosilane, methyltriacetoxysilane, methyldiacetoxymethoxysilane, methyldiacetoxyethoxysilane, methylacetoxydimethoxysilane, methylacetoxymethoxyethoxysilane, methylacetoxydiethoxysilane, methyltrihydroxysilane, methylmethoxydihydroxysilane, methylethoxydihydroxysilane, methyldimethoxyhydroxysilane, methylethoxymethoxyhydroxysilane, methyldiethoxyhydroxysilane, ethoxymethoxysilane, ethoxyhydroxysilane, ethoxymethoxyhydroxysilane, ethoxy ... Examples of the silane include ethyltrimethoxysilane, ethyltriethoxysilane, ethyltrichlorosilane, ethyltriacetoxysilane, ethyltrihydroxysilane, propyltrimethoxysilane, propyltriethoxysilane, propyltrichlorosilane, propyltriacetoxysilane, propyltrihydroxysilane, butyltrimethoxysilane, butyltriethoxysilane, butyltrichlorosilane, butyltriacetoxysilane, butyltrihydroxysilane, hexyltrimethoxysilane, hexyltriethoxysilane, hexyltrichlorosilane, hexyltriacetoxysilane, hexyltrihydroxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, phenyltrichlorosilane, phenyltriacetoxysilane, phenyltrihydroxysilane, and pentyltrimethoxysilane.

The above bifunctional silanes include di-tert-butyldichlorosilane, di-tert-butyldimethoxysilane, di-tert-butyldiethoxysilane, dibutyldichlorosilane, dibutyldimethoxysilane, dibutyldiethoxysilane, dichlorodecylmethylsilane, dimethoxydecylmethylsilane, diethoxydecylmethylsilane, dichlorodimethylsilane, dimethyldimethoxysilane, diethoxydimethylsilane, diethyldimethoxysilane, etc.

Examples of the monofunctional silanes include t-butyldimethylchlorosilane, t-butyldimethylmethoxysilane, t-butyldimethylethoxysilane, t-butyldiphenylchlorosilane, t-butyldiphenylmethoxysilane, t-butyldiphenylethoxysilane, chlorodimethylphenylsilane, methoxydimethylphenylsilane, ethoxydimethylphenylsilane, chlorotrimethylsilane, trimethylmethoxysilane, ethoxytrimethylsilane, triethylmethoxysilane, triethylethoxysilane, tripropylmethoxysilane, tributylmethoxysilane, tripentylmethoxysilane, triphenylchlorosilane, triphenylmethoxysilane, and triphenylethoxysilane.

<Magnetic Carrier>
The magnetic carrier contains magnetic carrier core particles and magnetic carrier particles having a resin coating layer on the surface of the magnetic carrier core particles.

<Resin coating layer>
The resin coating layer contains a resin A having a monomer unit A1 containing a nitrogen atom.

By including a resin having a monomer unit containing a nitrogen atom in the resin coating layer of the magnetic carrier particles, the charge amount of the toner tends to increase even in a high humidity environment. The inventors believe that this is because the nitrogen atoms in the resin tend to exist in the form of amines or their quaternary salts, and are prone to adsorb moisture from the surroundings and become polarized.

That is, the monomer unit A1 is preferably a monomer unit having at least one selected from the group consisting of an amino group, a monoalkylamino group, a dialkylamino group, and a trialkylammonium group. A trialkylammonium group is an amine functional group having a quaternary ammonium salt structure, such as a trimethylammonium group. In addition, the resin A is preferably a vinyl resin.

More preferably, the monomer unit A1 is a monomer unit represented by the following formula (2-1) or a monomer unit represented by the following formula (2-2). It has been found that when the monomer unit A1 is a monomer unit represented by formula (2-1) or formula (2-2), a two-component developer having excellent charging stability is more easily obtained even when continuous image output is performed in a room temperature and low humidity environment. This is thought to be because when the monomer unit contained in the resin coating layer is an aliphatic amine monomer unit represented by the following, the magnetic carrier is less likely to be excessively charged, and the organosilicon polymer particles are less likely to electrostatically adhere to the magnetic carrier. More preferably, the monomer unit A1 is a monomer unit represented by the following formula (2-2).

(In formula (2-1), R ¹ , R ² , and R ³ each independently represent a hydrogen atom or an alkyl group having 1 to 8 carbon atoms (preferably 1 to 4 carbon atoms); R ⁴ represents an alkylene group having 1 to 20 carbon atoms (preferably 1 to 10); R′ represents a hydrogen atom or a methyl group (preferably a methyl group); and X ⁻ represents a counter anion (preferably a halogen ion, more preferably Cl ⁻ ).

In formula (2-2), R ¹¹ and R ¹² are each independently a hydrogen atom or an alkyl group having 1 to 8 carbon atoms (preferably 1 to 4 carbon atoms), R ¹⁴ is an alkylene group having 1 to 20 carbon atoms (preferably 1 to 10), and R″ is a hydrogen atom or a methyl group (preferably a methyl group).
The content of the monomer unit A1 represented by the above formula (2-1) or (2-2) in the resin A is preferably 2.0% by mass to 20.0% by mass, and more preferably 3.0% by mass to 15.0% by mass. When multiple types of monomer unit A1 are contained, the total content is the total content.

The content of resin A in the resin coating layer is preferably 4.0 to 40.0% by mass. When multiple types of resin A are contained, the total content is used.

<Ratio of Nitrogen Atoms in Resin Coating Layer (N2)>
In the measurement of carbon, oxygen, silicon, nitrogen, and iron elements by X-ray photoelectron spectroscopy of magnetic carrier particles,
When the thickness of the resin coating layer is d (μm) and the proportion of nitrogen element at a position 0.95d from the surface of the magnetic carrier particle is N2 (atom %), N2 is 0.8 to 13.0.

By setting the ratio of nitrogen atoms near the magnetic carrier core particles, i.e., N2, to 0.8 atom% or more, the magnetic carrier is easily charged sufficiently and a stable image density is easily obtained even in a high-temperature, high-humidity environment where the charge amount is likely to decrease. The inventors believe that this is because the nitrogen atoms in the resin tend to exist in the form of amines or their quaternary salts, and are easily polarized by adsorbing moisture in the surroundings, so that the resin near the magnetic carrier core particles is easily charged as moisture is adsorbed. Therefore, it is 0.8 atom% or more, preferably 3.0 atom% or more, and more preferably 4.0 atom% or more. In addition, it is considered that the chargeability of the magnetic carrier is unlikely to become excessive in a high-temperature, high-humidity environment when it is 13.0 atom% or less. It was also found that a two-component developer with excellent charge stability is easily obtained even when continuous image output is performed in a normal temperature, low humidity environment. This is considered to be because the chargeability of the magnetic carrier is unlikely to become excessive even in a normal temperature, low humidity environment, and the organosilicon polymer particles are unlikely to electrostatically adhere to the magnetic carrier. Therefore, it is 13.0 atom% or less, preferably 9.0 atom% or less, and even more preferably 8.0 atom% or less.

In order to keep N2 within the above range, it can be controlled by adjusting the type and amount of the nitrogen atom-containing monomer that is used to manufacture the resin that constitutes the resin coating layer and is used to coat the magnetic carrier core particles, or by adjusting the layer thickness of the resin coating layer.

<Ratio of Nitrogen Atoms in Resin Coating Layer (N1)>
In a measurement of carbon element, oxygen element, silicon element, nitrogen element, and iron element of a magnetic carrier particle by X-ray photoelectron spectroscopy, when the proportion of nitrogen element on the surface of the magnetic carrier particle is defined as N1 (atom %), N1 is 0.0 to 0.7.

It is believed that by making the ratio of nitrogen atoms contained in the outermost layer of the magnetic carrier particles, i.e., N1, 0.7 atom% or less, the magnetic carrier is less likely to be excessively charged even in a low-humidity environment where charging is likely to occur. As a result, the chargeability of the two-component developer is more likely to be stable even in that environment, and a stable image density is more likely to be obtained. The inventors speculate that this is because when the ratio of nitrogen atoms in the outermost layer of the magnetic carrier particles is high, the nitrogen compound, which is the charge-imparting component, is more likely to excessively charge the toner. Therefore, it is 0.7 atom% or less, preferably 0.3 atom% or less, more preferably 0.2 atom% or less, and even more preferably 0.1 atom% or less. In other words, it is preferable that N1 is 0.0 to 0.1. There is no particular limit to the lower limit, and it is 0.0 atom% or more, and more preferably 0.0 atom% or more.

One example of a method for setting N1 within the above range is to coat the magnetic carrier core particles with the above resin A, and then further coat them with a resin with a controlled nitrogen atom content (for example, resin B, described below).

In addition, when N1 satisfies the above range, it is believed that the amount of moisture on the outermost surface of the magnetic carrier particles is low. For this reason, it is believed that by combining a magnetic carrier that satisfies the above N1 and N2 with the above organosilicon polymer particles, which are less likely to have large electrostatic adhesion forces, the organosilicon polymer particles are less likely to adhere to the magnetic carrier particles even in a high-temperature, high-humidity environment. For this reason, even when an image is output after being left in a high-temperature, high-humidity environment for a long period of time, the organosilicon polymer particles are less likely to separate from the surface of the toner particles, making it easier to produce a two-component developer with excellent density reproducibility.

The measurement positions of N1 and N2 are explained using FIG. 1. FIG. 1 shows a cross section of a magnetic carrier particle according to the present invention, and a schematic diagram of the measurement positions for X-ray photoelectron spectroscopy. The magnetic carrier 20 has a magnetic carrier core particle 19 and a resin coating layer 18 formed on the surface of the magnetic carrier core particle 19. In the resin coating layer 18, the magnetic carrier particle surface 21 is the measurement position where the above N1 is measured. In addition, in the resin coating layer 18, a position of 0.95×d (μm) with respect to the distance d in the depth direction from the magnetic carrier particle surface 21 to the magnetic carrier core particle 19 is the measurement position where the above N2 is measured.

In addition, in the present invention, the resin coating layer means all the resin layers that coat the magnetic carrier core particles. That is, as shown in FIG. 2, the resin coating layer 23 that coats the magnetic carrier core particles 22 may be composed of multiple resin layers (for example, when there are two layers, it may be composed of resin layer 24 and resin layer 25).

<Resin B>
It is preferable that the resin coating layer further contains a nitrogen-free resin B. When the resin B is a nitrogen-free resin, the above N1 is easily controlled, which is preferable.

It is more preferable that resin B has a monomer unit B1 represented by the following formula (3). It has been found that the inclusion of monomer unit B in resin B tends to improve concentration stability in response to environmental changes. It is also preferable that resin B is a vinyl resin.

(In formula (3), ^R6 represents a hydrogen atom or a methyl group (preferably a methyl group), and Y represents a cycloalkyl group having 4 to 12 carbon atoms (preferably 5 to 9).)
The monomer unit B1 can be contained in the resin B by using a (meth)acrylic acid ester having a cycloalkyl group as a monomer when the resin B is produced.

Examples of (meth)acrylic acid esters having a cycloalkyl group include cyclobutyl acrylate, cyclopentyl acrylate, cyclohexyl acrylate, cycloheptyl acrylate, dicyclopentenyl acrylate, dicyclopentanyl acrylate, cyclobutyl methacrylate, cyclopentyl methacrylate, cyclohexyl methacrylate, cycloheptyl methacrylate, dicyclopentenyl methacrylate, and dicyclopentanyl methacrylate. These monomers may be used alone or in combination of two or more.

The content of monomer unit B1 in resin B is preferably 30.0 to 90.0 mass%, and more preferably 40.0 to 80.0 mass%.

It is also preferable that the content of resin B in the resin coating layer is 30.0 to 90.0 mass%.

It is also preferred that the resin coating layer includes two layers, a resin layer A on the magnetic carrier core particle side and a resin layer B on the surface side of the magnetic carrier particle, and that the resin constituting the resin layer A is the above-mentioned resin A and the resin constituting the resin layer B is the above-mentioned resin B.

It is more preferable that the resin coating layer is composed of two layers, a resin layer A on the magnetic carrier core particle side and a resin layer B on the surface side of the magnetic carrier particle, and that the resin constituting the resin layer A is the above-mentioned resin A and the resin constituting the resin layer B is the above-mentioned resin B.

The resin layer on the magnetic carrier core particle side means the resin layer that is in contact with and directly covers the magnetic carrier core particle, and the resin layer on the surface side of the magnetic carrier particle means the resin layer that constitutes the surface of the magnetic carrier particle.

<Method of coating with resin>
The method for coating the surfaces of the magnetic carrier core particles with a resin is not particularly limited, but examples thereof include coating methods using a coating method such as a dipping method, a spraying method, a brush coating method, a dry method, and a fluidized bed method.

Specifically, for example, the surfaces of the magnetic carrier core particles can be coated with the resin by putting the magnetic carrier core particles and the resin solution into a mixer and mixing them. The amount of resin to be put in is preferably 0.1 to 10.0 parts by mass (resin solid content equivalent) per 100.0 parts by mass of the magnetic carrier core particles. The concentration of the resin in the resin solution is preferably 1 to 10% by mass. Furthermore, the solvent in the resin solution is not particularly limited, but is preferably toluene from the viewpoint of the efficiency of solvent removal. As the mixer, for example, a planetary type mixer such as Nauta Mixer VN type (Hosokawa Micron Corporation) can be used.

The magnetic carrier particles whose surfaces are coated with resin can then be dried, for example, at a temperature of 130°C to 230°C for 0.5 to 4.0 hours to obtain a magnetic carrier having a resin coating layer. When the obtained magnetic carrier is to be further coated with resin, the same operation as above can be carried out, except that the magnetic carrier core particles are replaced with magnetic carrier particles having a resin coating layer.

The resin coating layer may contain conductive particles or charge-controlling particles or materials. Examples of conductive particles include carbon black, magnetite, graphite, zinc oxide, and tin oxide. From the viewpoint of adjusting the resistance of the magnetic carrier, it is preferable that the content of the conductive particles is 0.1 parts by mass or more and 10.0 parts by mass or less per 100 parts by mass of the coating resin.

Examples of particles having charge controllability include particles made of the following substances.
Organic metal complexes, organic metal salts, chelate compounds, monoazo metal complexes, acetylacetone metal complexes, hydroxycarboxylic acid metal complexes, polycarboxylic acid metal complexes, polyol metal complexes, polymethyl methacrylate resins, polystyrene resins, melamine resins, phenolic resins, nylon resins, silica, titanium oxide, and alumina.

From the viewpoint of adjusting the amount of triboelectric charge, it is preferable that the content of the particles having charge control properties is 0.5 parts by mass or more and 50.0 parts by mass or less per 100 parts by mass of the coating resin.

<Magnetic Carrier Core Particles>
The magnetic carrier core particles are not particularly limited, and for example, in addition to magnetic carrier core particles made of magnetic iron oxide, magnetic material dispersion type resin particles in which a magnetic material component is dispersed in a resin component, or porous magnetic core particles containing a resin in the void portion can be used. Among these, magnetic carrier core particles made of magnetic iron oxide are preferred.

Examples of the magnetic material component contained in the magnetic material-dispersed resin particles include the following.
magnetite particles, maghemite particles, or magnetic iron oxide particles containing at least one selected from the group consisting of silicon oxide, silicon hydroxide, aluminum oxide, and aluminum hydroxide;
Magnetoplumbite ferrite particles containing at least one selected from barium and strontium;
Magnetic iron compound particles, such as spinel-type ferrite particles, containing at least one selected from manganese, nickel, zinc, lithium and magnesium.

Among these, magnetic iron oxide particles are preferably used.

The magnetic material-dispersed resin particles may contain, in addition to the magnetic material component, a non-magnetic material component (non-magnetic inorganic compound particles) exemplified below.
Non-magnetic iron oxide particles such as hematite particles, non-magnetic ferric oxide hydrous particles such as goethite particles, titanium oxide particles, silica particles, talc particles, alumina particles, barium sulfate particles, barium carbonate particles, cadmium yellow particles, calcium carbonate particles, zinc oxide particles, etc.

When using a combination of magnetic and non-magnetic components (non-magnetic inorganic compound particles), the proportion of the magnetic component in the mixture is preferably 30% by mass or more.

It is preferable that all or part of the magnetic material component is treated with a lipophilic treatment agent.

Examples of lipophilic treatment agents include organic compounds having at least one functional group selected from the group consisting of an epoxy group, an amino group, a mercapto group, a carboxy group, an ester group, a ketone group, a halogenated alkyl group, and an aldehyde group, and mixtures thereof.

The lipophilic treatment agent is preferably at least one selected from the group consisting of a silane coupling agent, a titanium coupling agent, and an aluminum coupling agent, and is more preferably a silane coupling agent.

The resin component that constitutes the magnetic material-dispersed resin particles is preferably a thermosetting resin.

Examples of the thermosetting resin include phenolic resin, epoxy resin, and unsaturated polyester. Among these, phenolic resin is preferred, such as phenol-formaldehyde resin.

The ratio of the resin component and magnetic component (or a mixture of magnetic and non-magnetic components) that make up the magnetic material-dispersed resin particles is preferably 1% to 20% by mass of the resin component (80% to 99% by mass of the magnetic material component).

<Method of manufacturing magnetic material-dispersed resin particles>
The magnetic material-dispersed resin particles can be produced, for example, by the following method.

In the presence of magnetic components such as magnetic iron oxide particles and a basic catalyst, phenols and aldehydes are stirred in an aqueous medium. The phenols and aldehydes are then reacted and hardened to produce magnetically dispersed resin particles that contain magnetic components such as magnetic iron oxide particles and phenolic resin.

The above manufacturing method is preferred from the viewpoint of ease of controlling the particle size of the magnetic carrier particles and making it easier to sharpen the particle size distribution of the magnetic carrier particles.

Magnetic material-dispersed resin particles can also be produced by grinding resin containing magnetic components such as magnetic iron oxide particles, i.e., by the kneading grinding method.

<Porous magnetic core particles>
Examples of the material of the porous magnetic core particle include magnetite and ferrite. Among them, ferrite is preferred from the viewpoint of ease of control of the porous structure of the porous magnetic core particle and ease of adjustment of the resistance of the porous magnetic core particle. Ferrite is a sintered body represented by the following formula:
(M1 ₂ O) _x (M2O) _y (Fe ₂ O ₃ ) _Z
(In the above formula, M1 is a monovalent metal, M2 is a divalent metal, and when x+y+z=1.0, 0≦x≦0.8, 0≦y≦0.8, and 0.2<z<1.0.)
In the above formula, examples of M1 and M2 include Li, Fe, Mn, Mg, Sr, Cu, Zn, Ca, Ni, Co, Ba, Y, V, Bi, In, Ta, Zr, B, Mo, Na, Sn, Ti, Cr, Al, Si, rare earth elements, etc. Among these, from the viewpoint of maintaining an appropriate amount of magnetization and easily controlling the rate of the ferritization reaction, Mn-based ferrite, Mn-Mg-based ferrite, Mn-Mg-Sr-based ferrite, and Li-Mn-based ferrite containing Mn element are more preferable.

<Two-component developer>
The mixture ratio of the magnetic carrier and the toner in the two-component developer is preferably such that the toner concentration in the two-component developer is 2% by mass or more and 15% by mass or less, and more preferably 4% by mass or more and 13% by mass or less.

<Toner and toner particles>
The toner particles preferably contain a binder resin. Examples of the binder resin include vinyl resin, polyester, and epoxy resin, and one type may be used alone or two or more types may be used in combination. Among them, from the viewpoint of electrostatic chargeability and fixability, vinyl resin and/or polyester are preferable, and polyester is more preferable.

If necessary, polyurethane, epoxy resin, polyvinyl butyral, rosin, modified rosin, terpene resin, phenolic resin, aliphatic or alicyclic hydrocarbon resin, aromatic petroleum resin, etc. can also be mixed with the binder resin.

<Polyester>
As the binder resin, preferred polyesters are described below.

Based on the total monomer units constituting the polyester, it is preferable that 45 mol% to 55 mol% is an alcohol component, and 45 mol% to 55 mol% is a carboxylic acid component.

The acid value of the polyester is preferably 0 to 90 mgKOH/g, more preferably 5 to 50 mgKOH/g. The hydroxyl value of the polyester is preferably 0 to 50 mgKOH/g, more preferably 5 to 30 mgKOH/g. When the acid value and hydroxyl value of the polyester are within the above ranges, it is believed that the charging characteristics of the toner are less dependent on the environment.

The glass transition temperature (Tg) of the polyester is preferably 50 to 75°C, more preferably 55 to 65°C. The number average molecular weight (Mn) of the polyester is preferably 1,500 to 50,000, more preferably 2,000 to 20,000. The weight average molecular weight (Mw) of the polyester is preferably 6,000 to 150,000, more preferably 10,000 to 100,000.

The content of polyester in the binder resin is preferably 50 to 100% by mass, and more preferably 80 to 100% by mass.

A crystalline polyester may be added to the toner particles in order to promote the plasticizing effect of the toner particles and improve the low-temperature fixability of the toner. An example of the crystalline polyester is a polycondensate of a monomer composition containing, as main components, an aliphatic diol having 2 to 22 carbon atoms and an aliphatic dicarboxylic acid having 2 to 22 carbon atoms.

The aliphatic diol having 2 to 22 carbon atoms (more preferably 6 to 12 carbon atoms) is not particularly limited, but is preferably a chain (more preferably a straight-chain) aliphatic diol. Among these, particularly preferred examples include straight-chain aliphatic α,ω-diols such as ethylene glycol, diethylene glycol, 1,4-butanediol, and 1,6-hexanediol.

Of the alcohol components, preferably 50% by mass or more, more preferably 70% by mass or more, is an alcohol selected from aliphatic diols having 2 to 22 carbon atoms.

Polyhydric alcohol monomers other than aliphatic diols can also be used. Dihydric alcohol monomers include aromatic alcohols such as polyoxyethylenated bisphenol A and polyoxypropylenated bisphenol A; 1,4-cyclohexanedimethanol, etc.

Examples of trihydric or higher polyhydric alcohol monomers include aromatic alcohols such as 1,3,5-trihydroxymethylbenzene; and aliphatic alcohols such as pentaerythritol, dipentaerythritol, tripentaerythritol, 1,2,4-butanetriol, 1,2,5-pentanetriol, glycerin, 2-methylpropanetriol, 2-methyl-1,2,4-butanetriol, trimethylolethane, and trimethylolpropane.

Monohydric alcohol may also be used to the extent that it does not impair the properties of the crystalline polyester.

On the other hand, the aliphatic dicarboxylic acid having 2 to 22 carbon atoms (more preferably 6 to 12 carbon atoms) is not particularly limited, but is preferably a chain (more preferably linear) aliphatic dicarboxylic acid. Also included are those obtained by hydrolyzing the acid anhydrides or lower alkyl esters of these.

Of the carboxylic acid components, preferably 50% by mass or more, more preferably 70% by mass or more, is a carboxylic acid selected from aliphatic dicarboxylic acids having 2 to 22 carbon atoms.

Polyvalent carboxylic acids other than the above aliphatic dicarboxylic acids having 2 to 22 carbon atoms can also be used. Examples of divalent carboxylic acids include aromatic carboxylic acids such as isophthalic acid and terephthalic acid; aliphatic carboxylic acids such as n-dodecylsuccinic acid and n-dodecenylsuccinic acid; and alicyclic carboxylic acids such as cyclohexanedicarboxylic acid, as well as their acid anhydrides and lower alkyl esters.

Examples of trivalent or higher polyvalent carboxylic acids include aromatic carboxylic acids such as 1,2,4-benzenetricarboxylic acid (trimellitic acid), 2,5,7-naphthalenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, and pyromellitic acid, and aliphatic carboxylic acids such as 1,2,4-butanetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, and 1,3-dicarboxy-2-methyl-2-methylenecarboxypropane, as well as their acid anhydrides and derivatives such as lower alkyl esters.

It may also contain a monovalent carboxylic acid to the extent that it does not impair the properties of the crystalline polyester.

Crystalline polyesters can be produced according to conventional polyester synthesis methods. For example, a carboxylic acid monomer and an alcohol monomer can be subjected to an esterification reaction or an ester exchange reaction, followed by a conventional polycondensation reaction under reduced pressure or by introducing nitrogen gas, to obtain the desired crystalline polyester.

The amount of crystalline polyester used is preferably 0.1 parts by weight or more and 30 parts by weight or less, more preferably 0.5 parts by weight or more and 20 parts by weight or less, and even more preferably 3 parts by weight or more and 15 parts by weight or less, per 100 parts by weight of binder resin.

<Method of producing toner and toner particles>
The method for producing the toner particles is not particularly limited, and examples thereof include a melt-kneading method, a suspension polymerization method, a dissolution suspension method, an emulsion aggregation method, etc. The toner particles are preferably produced by the melt-kneading method or the emulsion aggregation method.

In addition, the method for producing toner particles preferably uses a mixture in which a colorant is mixed with a binder resin in advance to form a master batch. Then, by melting and kneading this mixture with other raw materials (binder resin, wax, etc.), the colorant can be well dispersed in the toner particles.

The melt-kneading method is described below. The melt-kneading method is a toner manufacturing method that includes a process of melting and kneading a mixture containing toner raw materials such as a binder resin, wax, and colorant to obtain a melt-kneaded product (hereinafter also simply referred to as the melt-kneading process). It is also preferable to include a process of cooling the melt-kneaded product obtained in the melt-kneading process, and then pulverizing the resulting toner particles to heat-treat them (hereinafter also simply referred to as the heat treatment process). This allows the externally added organosilicon polymer to be fixed to the toner.

The procedure for producing toner particles using the melt-kneading method is described below.

First, in the raw material mixing process, predetermined amounts of binder resin, wax, colorant, etc. are weighed out and mixed as toner raw materials.

The equipment used for the mixing includes Henschel mixer (manufactured by Nippon Coke Co.); Super mixer (manufactured by Kawata Co.); Ribocone (manufactured by Okawara Manufacturing Co.); Nauta mixer, Turbulizer, Cyclomix (manufactured by Hosokawa Micron Co.); Spiral pin mixer (manufactured by Pacific Machinery Works Co.); and Lödige mixer (manufactured by Matsubo Co.).

Next, the resulting mixture is melted and kneaded to melt the resins and disperse the wax, colorants, etc. into it (melt-kneading process).

The equipment used for melt kneading includes a TEM type extruder (manufactured by Toshiba Machine Co., Ltd.); a TEX twin screw kneader (manufactured by Japan Steel Works, Ltd.); a PCM kneader (manufactured by Ikegai Iron Works Co., Ltd.); and a Kneadex (manufactured by Mitsui Mining Co., Ltd.). Continuous kneaders such as single screw or twin screw extruders are preferred over batch kneaders because of their advantage of being capable of continuous production.

Next, the resulting molten mixture is rolled using a two-roll mill or similar and cooled using water or other methods.

The cooled material is then pulverized to the desired particle size. First, it is coarsely pulverized using a crusher, hammer mill, or feather mill, and then it is finely pulverized using a Kryptron system (manufactured by Kawasaki Heavy Industries, Ltd.) or a Super Rotor (manufactured by Nisshin Engineering, Inc.).

The powder may then be classified to the desired particle size. Devices used for classification include Turboplex, Faculty, TSP, TTSP (manufactured by Hosokawa Micron Corporation); Elbow Jet (manufactured by Nittetsu Mining Co., Ltd.), etc.

The obtained toner particles may also be subjected to a heat treatment. If coarse particles are present after the heat treatment, they may be removed by classification or sieving, as necessary. Apparatuses used for classification include those mentioned above. Apparatuses used for sieving include Ultrasonic (manufactured by Koei Sangyo Co., Ltd.); Resonaseave, Gyroshifter (Tokuju Kogyo Co., Ltd.); Turbo Screener (manufactured by Turbo Kogyo Co., Ltd.); and Hi-Volter (manufactured by Toyo Hitec Co., Ltd.).

Before or after the heat treatment step, inorganic fine particles, organosilicon polymers, etc. may be added as necessary.

<Various additives>
If necessary, the toner may contain one or more additives selected from a colorant, a release agent, a charge control agent, inorganic fine particles, etc. Various additives used in the toner will be specifically described.

<Coloring Agent>
Examples of the colorant include the following: As the colorant, a pigment may be used alone, or a dye and a pigment may be used in combination.
Carbon black as a black colorant; a black colorant adjusted using a yellow colorant, a magenta colorant, and a cyan colorant.

Examples of color pigments for magenta toner include the following:
Condensed azo compounds, diketopyrrolopyrrole compounds, anthraquinone compounds, quinacridone compounds, basic dye lake compounds, naphthol compounds, benzimidazolone compounds, thioindigo compounds, and perylene compounds.
Specifically, C.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. Pigment Violet 19, C.I. Bat Red 1, 2, 10, 13, 15, 23, 29, 35.

Dyes for magenta toner 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. Disperse Red 9, C. I. Solvent Violet 8, 13, 14, 21, 27, C. I. Disperse Violet 1 and other oil-soluble dyes, C. 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. Basic Violet 1, 3, 7, 10, 14, 15, 21, 25, 26, 27, 28 and other basic dyes.

Examples of color pigments 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. Bat Blue 6, C. I. Acid Blue 45, copper phthalocyanine pigments having 1 to 5 phthalimidomethyl groups substituted on the phthalocyanine skeleton.

Yellow color pigments include the following:
Condensed azo compounds, isoindolinone compounds, anthraquinone compounds, azo metal compounds, methine compounds, and allylamide compounds.
Specifically, C.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; C.I. Bat Yellow 1, 3, 20. In addition, dyes such as C.I. Direct Green 6, C.I. Basic Green 4, C.I. Basic Green 6, and Solvent Yellow 162 can also be used.

The content of the colorant is preferably 0.1 to 30.0 parts by mass, more preferably 0.5 to 20.0 parts by mass, and even more preferably 3.0 to 15.0 parts by mass, per 100 parts by mass of the binder resin.

<Charge Control Agent>
Examples of the charge control agent include the following. One type may be used alone, or two or more types may be used in combination.

As an example of a negative charge control agent that controls the toner to be negatively charged, an organic metal complex or a chelate compound is effective. Specific examples include monoazo metal complexes, metal complexes of aromatic hydroxycarboxylic acids, and metal complexes of aromatic dicarboxylic acids. Other examples include aromatic hydroxycarboxylic acids, aromatic mono- and polycarboxylic acids and their metal salts, their anhydrides, or their esters, or phenol derivatives of bisphenol.

Positive charge control agents that control the toner to be positively charged include modified products of nigrosine and fatty acid metal salts, quaternary ammonium salts such as tributylbenzylammonium-1-hydroxy-4-naphthosulfonate and tetrabutylammonium tetrafluoroborate, and onium salts such as phosphonium salts that are analogues of these, and chelate pigments thereof, such as triphenylmethane dyes and lake pigments thereof (lake forming agents include phosphotungstic acid, phosphomolybdic acid, phosphotungstomolybdic acid, tannic acid, lauric acid, gallic acid, ferricyanide compounds, etc.), and metal salts of higher fatty acids, such as diorgano tin oxides such as dibutyl tin oxide, dioctyl tin oxide, and dicyclohexyl tin oxide, and diorgano tin borates such as dibutyl tin borate, dioctyl tin borate, and dicyclohexyl tin borate.

It is preferable to use 0.5 to 10 parts by weight of the charge control agent per 100 parts by weight of the binder resin. If it is 0.5 parts by weight or more, sufficient charging characteristics are obtained. On the other hand, if it is 10 parts by weight or less, compatibility with other materials is good and excessive charging in low humidity conditions can be suppressed.

<Release Agent>
Examples of the release agent include the following. One type may be used alone, or two or more types may be used in combination.
Aliphatic hydrocarbon waxes such as low molecular weight polyethylene, low molecular weight polypropylene, microcrystalline wax, and paraffin wax are preferably used. In addition, oxides of aliphatic hydrocarbon waxes such as oxidized polyethylene wax or block copolymers thereof; waxes mainly composed of fatty acid esters such as carnauba wax, sazol wax, and montan acid ester wax; and partially or completely deoxidized fatty acid esters such as deoxidized carnauba wax.

The content 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, as determined by the maximum endothermic peak temperature during heating measured with a differential scanning calorimeter (DSC), is preferably 65 to 130°C. More preferably, it is 80 to 125°C. If the melting point is 65°C or higher, the toner has a suitable viscosity, which makes it possible to suppress toner adhesion to the photoreceptor. On the other hand, if the melting point is 130°C or lower, low-temperature fixability is good.

<Inorganic fine particles>
As the inorganic fine particles, silica fine particles, titanium oxide fine particles, and aluminum oxide fine particles are preferable. The inorganic fine particles may be added internally to the toner particles, or may be mixed with the toner particles as an external additive. In addition, one type of inorganic fine particles may be used alone, or two or more types may be used in combination.

The inorganic fine particles are preferably hydrophobized with a hydrophobizing agent such as a silane compound, silicone oil, or a mixture thereof. When the inorganic fine particles are added as an external additive, the amount is preferably 0.1 to 10.0 parts by mass per 100.0 parts by mass of the toner particles. When adding inorganic fine particles to the toner particles, it is advisable to use a mixer such as a Henschel mixer.

<Various measurement methods, etc.>
Various measurement methods are described below.

<Method for confirming the structures represented by formulas (2-1), (2-2), and (3) in the resin coating layer>
The resin constituting the resin coating layer on the surface of the magnetic carrier core particle can be separated from the magnetic carrier particles and confirmed to have the structures represented by formulas (2-1), (2-2), and (3). As a method for separating the resin constituting the resin coating layer from the magnetic carrier particles, there is a method in which 10 g of the magnetic carrier is placed in a cup, toluene is added, and the mixture is stirred to elute the resin.

The separated resin is dissolved in chloroform-D and ¹ H-NMR and ¹³ C-NMR are measured under the following NMR measurement conditions. The content ratio of each resin in the coating resin layer can also be calculated from the mass of each resin and the NMR measurement.

(Measurement conditions)
・Apparatus: JEOL ECA-400 (400MHz)
Temperature: 25°C
Furthermore, the structure of the resin coating layer remaining on the magnetic carrier core particles is confirmed, for example, by the following method using a pyrolysis gas chromatography mass spectrometer (hereinafter, pyrolysis GC-MS).

(Measurement method)
The apparatus used was a "PYROFOIL SAMPLER JPS-700" manufactured by Japan Analytical Industry Co., Ltd., and the gas chromatography mass spectrometer was a "Trace GCMS" manufactured by Thermo Fisher Scientific Co., Ltd. The sample was 0.1 mg of sample wrapped in 590 ° C. pyrofoil and set in the pyrolysis apparatus. The column used was HP-INNOWAX (manufactured by Agilent Technologies, column length 30 m, inner diameter 0.25 mm, liquid phase 0.25 μm). The column temperature increase conditions were 50 ° C. to 120 ° C. at 5 ° C./min, 10 ° C./min to 200 ° C., and 3 minutes at 200 ° C. The conditions of the GC-MS inlet were set as inlet temperature 200 ° C., split analysis, split flow 50 mL/min, and inlet pressure 100 kPa.

<Method of measuring N1 and N2 by XPS>
The measurement sample is prepared by attaching an indium foil to a platen dedicated to XPS and then attaching a magnetic carrier to the indium foil. The magnetic carrier is attached evenly so that the indium foil is not exposed. Using the XPS device described below, the X-ray irradiation area and the sputtering area by GCIB irradiation are set on the magnetic carrier on the indium foil.
Equipment used: ULVAC-PHI PHI 5000 VersaProbe II
Irradiation radiation: Al-Kα rays Output: 100μ25W15kV
Photoelectron capture angle: 45°
Pass Energy: 58.70eV
Step size: 0.125eV
XPS peaks: C2p, O2p, Si2p, N1s, Fe2p
Measurement range: 300 μm x 200 μm
Gun type: GCIB
Time: 15 minutes Interval: 1 minute Sputter Setting: 20 kV
Measurement is performed under the above conditions, and the element number ratio (atom%) can be calculated from the peak of each element. N1 is the element number ratio of nitrogen element among the above five elements on the surface of the magnetic carrier particle. In addition, the layer thickness d is reached when the element number ratio of Fe2p originating from sputtering becomes 1.0 (atom%) or more, and the element number ratio of nitrogen element among the above five elements at the time when the number of sputtering times is 0.95 is N2.

The measurement locations are changed and the above measurements are carried out a total of 10 times, and the average values are taken as N1 and N2 according to the present invention.

In addition, the depth rate of one sputtering can be calculated based on the layer thickness d measured using the method described below.

<Method of measuring thickness d of resin coating layer>
The thickness d of the resin coating layer can be measured by observing the cross section of the magnetic carrier particle with a transmission electron microscope (TEM) (50,000 times magnification).

Specifically, the magnetic carrier is ion milled using an argon ion milling device (Hitachi High-Technologies Corporation, product name E-3500), and the thickness of the resin coating layer on the cross section of the magnetic carrier particle is measured at any 10 points using a transmission electron microscope (TEM) (50,000x magnification each).

The cross sections of 20 magnetic carrier particles were subjected to the same measurement as above, and the average value of the 200 measured values of the thickness of the resin coating layer obtained was taken as d (μm). The ion milling measurement conditions were as follows:
Beam diameter: 400 μm (half width)
Ion gun acceleration voltage: 5 kV
Ion gun discharge voltage: 4 kV
Ion gun discharge current: 463 μA
Ion gun irradiation current: 90 μA/cm ³ /1 min <Identification of organosilicon polymer particles>
The composition and ratio of the constituent compounds of the organosilicon polymer particles contained in the toner are identified using a pyrolysis gas chromatography mass spectrometer (hereinafter also referred to as "pyrolysis GC/MS") and NMR. If the organosilicon polymer particles are available separately, they can also be measured separately.

Pyrolysis GC/MS is used to analyze the types of constituent compounds in organosilicon polymer particles.

The types of constituent compounds of the organosilicon polymer particles are identified by analyzing the mass spectrum of the components of the decomposition products derived from the organosilicon polymer particles that are produced when the toner is thermally decomposed at 550°C to 700°C. The specific measurement conditions are as follows.

(Measurement conditions for pyrolysis GC/MS)
・Pyrolysis device: JPS-700 (Japan Analysis Industry)
Decomposition temperature: 590°C
GC/MS equipment: Focus GC/ISQ (Thermo Fisher)
Column: HP-5MS, length 60 m, inner diameter 0.25 mm, film thickness 0.25 μm
Inlet temperature: 200℃
Flow pressure: 100 kPa
Split: 50 mL/min MS ionization: EI
Ion source temperature: 200°C Mass Range 45-650
The abundance ratios of the identified constituent compounds of the organosilicon polymer particles are then measured and calculated by solid-state ^29Si -NMR. In solid-state ^29Si -NMR, peaks are detected in different shift regions depending on the number of functional groups bonded to the Si of the constituent compounds of the organosilicon polymer particles. The number of functional groups of each peak is identified using a standard sample. The abundance ratios of each constituent compound are calculated from the peak areas obtained.

The measurement conditions for solid-state ^29Si -NMR are as follows.
・Device: JNM-ECX5002 (JEOL RESONANCE)
Temperature: Room temperature Measurement method: DDMAS method 29Si 45°
Sample tube: Zirconia 3.2 mm diameter
Sample: Powdered and filled into test tube Sample rotation speed: 10 kHz
relaxation delay: 180s
Scan: 2000
When the toner contains silicon-containing materials other than the organosilicon polymer particles, the toner is dispersed in a solvent such as chloroform, and then the silicon-containing materials other than the organosilicon polymer particles are removed by the difference in specific gravity using centrifugation or the like. One example of this method is shown below.
First, 1 g of toner is added to 31 g of chloroform in a vial and dispersed, and silicon-containing materials other than the organosilicon polymer particles are separated from the toner. The dispersion is processed for 30 minutes using an ultrasonic homogenizer to produce a dispersion liquid. The processing conditions are as follows:
・Ultrasonic processing device: Ultrasonic homogenizer VP-050 (manufactured by Taitec Co., Ltd.)
Microchip: Step type microchip, tip diameter φ2mm
Position of the tip of the microchip: at the center of the glass vial and at a height of 5 mm from the bottom of the vial. Ultrasonic conditions: intensity 30%, 30 minutes (ultrasonics was applied while cooling the vial with ice water to prevent the temperature of the dispersion from increasing).
The dispersion is transferred to a glass tube (50 mL) for a swing rotor, and centrifuged in a centrifuge (H-9R; manufactured by Kokusan Co., Ltd.) at 58.33 S ⁻¹ for 30 minutes. In the glass tube after centrifugation, silicon-containing materials other than the organosilicon polymer particles and a residue from which silicon-containing materials other than the organosilicon polymer particles have been removed from the toner are separated. The residue from which silicon-containing materials other than the organosilicon polymer particles have been removed from the toner is extracted and dried under vacuum conditions (40° C./24 hours) to obtain a sample from which silicon-containing materials other than the organosilicon polymer particles have been removed from the toner. The composition and ratio of the constituent compounds of the organosilicon polymer particles contained in the toner can be identified by the same procedure as above.

<Method for quantifying organosilicon polymer particles contained in toner>
The content of organosilicon polymer particles in the toner is measured using fluorescent X-rays.

The measurement of fluorescent X-rays conforms to JIS K 0119-1969, but is specifically as follows. The measurement equipment is a wavelength dispersive X-ray fluorescence analyzer "Axios" (manufactured by PANalytical) and the accompanying dedicated software "SuperQ ver. 5.0L" (manufactured by PANalytical) for setting measurement conditions and analyzing measurement data. Rh is used as the anode of the X-ray tube, the measurement atmosphere is vacuum, and the measurement diameter (collimator mask diameter) is 27 mm. The measurement is performed using the Omnian method to measure the range of elements F to U, and detection is performed with a proportional counter (PC) when measuring light elements and a scintillation counter (SC) when measuring heavy elements. The acceleration voltage and current value of the X-ray generator are set to an output of 2.4 kW. The measurement sample was prepared by placing 4 g of toner in a special aluminum ring for pressing, flattening it, and pressing it at 20 MPa for 60 seconds using a tablet press "BRE-32" (Maekawa Test Machinery Manufacturing Co., Ltd.) to form a pellet with a thickness of 2 mm and a diameter of 39 mm.

The pellets formed under the above conditions are irradiated with X-rays, and the characteristic X-rays (fluorescent X-rays) that are generated are dispersed using a spectroscopic element. Next, the intensity of the fluorescent X-rays dispersed at angles corresponding to the wavelengths specific to each element contained in the sample is analyzed using the fundamental parameter method (FP method), and the content ratio of each element contained in the toner is obtained as the analysis result, and the silicon atom content in the toner is calculated.

The content of organosilicon polymer particles in a toner can be calculated from the relationship between the silicon content in the toner determined by fluorescent X-rays and the silicon content ratio in the constituent compounds of the organosilicon polymer particles whose structure has been identified using solid ^- state 29Si NMR and pyrolysis GC/MS.

If the toner contains silicon-containing materials other than the organosilicon polymer particles, the amount of organosilicon polymer particles in the toner can be quantified by removing the silicon-containing materials other than the organosilicon polymer particles from the toner using the same method as above.

<Method for determining the presence or absence of T3 unit structures in organosilicon polymer particles>
The presence or absence of T3 unit structures in the organosilicon polymer particles is determined using the results of solid-state ²⁹ Si-NMR measured in "Identification of organosilicon polymer particles". In solid-state ²⁹ Si-NMR, peaks are detected in different shift regions depending on the number of siloxane bonds (monofunctional to tetrafunctional) bonded to Si in the constituent compound of the organosilicon polymer particles, and the presence or absence of T3 unit structures can be confirmed from these peaks. Furthermore, the content ratio of T3 unit structures can also be calculated from the integrated value of the above NMR.

<Method of Measuring Number Average Particle Size of Primary Particles of Organosilicon Polymer Particles>
The number average particle size of the primary particles of the organosilicon polymer particles is measured using a scanning electron microscope (S-4800, manufactured by Hitachi, Ltd.). The toner particles to which the organosilicon polymer particles have been added are observed, and the number average particle size is determined by measuring the major axis of the primary particles of 100 randomly selected organosilicon polymer particles in a field of view magnified up to 50,000 times. The observation magnification is appropriately adjusted depending on the size of the organosilicon polymer. In addition, when the organosilicon polymer can be obtained alone, the organosilicon polymer can also be measured alone.

When the toner contains silicon-containing substances other than organosilicon polymer particles, EDS analysis is performed on each particle of the external additive in the observation of the toner particles, and it is possible to determine whether the analyzed particles are organosilicon polymer particles or not from the presence or absence of a Si element peak. In addition, when the toner contains both organosilicon polymer particles and silica fine particles, the organosilicon polymer particles are identified by comparing the ratio of the elemental contents (atomic%) of Si and O (Si/O ratio) with a standard. EDS analysis is performed on each standard of the organosilicon polymer particles and the silica fine particles under the same conditions to obtain the elemental contents (atomic%) of Si and O. The Si/O ratio of the organosilicon polymer particles is A, and the Si/O ratio of the silica fine particles is B. Measurement conditions are selected under which A is significantly larger than B. Specifically, 10 measurements are performed on the standard under the same conditions, and the arithmetic mean values of A and B are obtained. Measurement conditions are selected under which the obtained average value A/B>1.1.

If the Si/O ratio of the microparticles to be identified is on the A side of [(A+B)/2], the microparticles are judged to be organosilicon polymer particles. Tospearl 120A (Momentive Performance Materials Japan LLC) is used as a standard for organosilicon polymer particles, and HDK V15 (Asahi Kasei) is used as a standard for silica microparticles.

<Method for Measuring Water Adsorption Amount of Organosilicon Polymer Particles>
The amount of water adsorption by the organosilicon polymer particles is measured using an adsorption equilibrium measuring device (BELSORP-aqua3, manufactured by BEL Japan Inc.). This device measures the amount of adsorption of the target gas (water vapor in this case). The specific measurement method is described below.

(Degassing)
Before measurement, degas the moisture adsorbed in the sample. Attach the cell, filler rod, and cap, and weigh the empty sample. Weigh out approximately 0.3 g of sample and place it in the cell. Place the filler rod in the cell, attach the cap, and attach it to the degassing port. Once all the cells to be measured are attached to the degassing port, open the helium valve. Turn on the button for the port to be degassed, and press the "VAC" button. Degas in this manner for at least one day.

(measurement)
Turn on the power of the main unit and start the vacuum pump. Turn on the power of the main unit and the operation panel for the circulating water, and start "BELaqua3.exe (measurement software)" in the center of the PC screen. Temperature control of the high-temperature air chamber: Double-click "SV" in the "TIC1" frame on the "Flow path diagram" window to open the "Temperature setting" window. Enter the temperature (80°C) and click "Set". Adsorption temperature control: Double-click "SV" in "Adsorption temperature" on the "Flow path diagram" window to enter the "SV value" (adsorption temperature). Click "Start circulation" and "External temperature control", then click "Set". Press the "PURGE" button to stop degassing, turn off the port button, remove the sample, attach the cap, weigh the sample, and then attach the sample to the main unit measurement unit. On the PC, click "Measurement conditions" to open the "Measurement condition setting" window. The measurement conditions are as follows.
Air thermostatic chamber temperature: 80.0°C
・Adsorption temperature: 30.0℃
・Adsorbent name: H ₂ O
・Equilibrium time: 500sec
・Temperature waiting time: 60 minutes ・Saturated vapor pressure: 4.245 kPa
Sample tube pumping speed: normal; Chemical adsorption measurement: not performed; Initial introduction amount: 0.20 cm ³ (STP)·g ⁻¹
・Number of measurement relative pressure ranges: 4
Select the number of samples to be measured, enter the "measurement data file name" and "sample weight." Start the measurement.

(analysis)
The analytical software is started and the water adsorption amount (cm ³ g ^-1 ) at a temperature of 30° C. and a relative humidity of 80% is calculated.

<Method of Measuring the Dielectric Constant of Organosilicon Polymer Particles>
The dielectric constant of the organosilicon polymer particles is measured using a power source and ammeter, SI 1260 electrochemical interface (manufactured by Toyo Corporation), and a current amplifier, 1296 dielectric interface (manufactured by Toyo Corporation).

The measurement sample is prepared by heating and molding the sample into a disk shape with a thickness of 3.0 ± 0.5 mm using a tablet molder. A gold electrode is created in a circular shape with a diameter of 10 mm on the top and bottom surfaces of the sample using mask deposition.

Measurement electrodes are attached to the prepared measurement sample, and an AC voltage of 100 mVp-p is applied at a frequency of 0.1 MHz to measure the capacitance. The relative dielectric constant ε of the measurement sample is calculated from the following formula.
ε=dC/ε ₀ S
d: thickness of the measurement sample (m)
C: Capacitance (F)
ε ₀ : Dielectric constant of vacuum (F/m)
S: Electrode area (m ² )

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. Parts in the following formulations are by weight unless otherwise specified.

<Production Example of Organosilicon Polymer Particles 1>
(First process)
A reaction vessel equipped with a thermometer and a stirrer was charged with 360.0 parts of water, and 15.0 parts of hydrochloric acid (concentration: 5.0% by mass) was added to obtain a homogeneous solution. 135.0 parts of methyltrimethoxysilane (a silane compound) was added to the homogeneous solution while stirring at a temperature of 25° C., and the mixture was stirred for 5 hours and then filtered to obtain a transparent reaction liquid.

(Second step)
In a reaction vessel equipped with a thermometer, agitator, and dropping device, 440.0 parts of water are put, and 17.0 parts of ammonia water with a concentration of 10.0% by mass are added to obtain a homogeneous solution.While stirring this homogeneous solution at a reaction start temperature of 35°C, 100 parts of the reaction liquid obtained in the first step are dropped over 1.20 hours (dropping time), and stirred for 6 hours to obtain a suspension.The obtained suspension is centrifuged to take out the precipitated fine particles, and dried in a dryer at a temperature of 200°C for 24 hours to obtain organosilicon polymer particles 1.The physical properties of the obtained organosilicon polymer particles 1 are shown in Table 1.

<Production Examples of Organosilicon Polymer Particles 2 to 12>
Organosilicon polymer particles 2 to 12 were obtained in the same manner as in the preparation example of organosilicon polymer particles 1, except that the type and amount of various materials in each step, and the reaction initiation temperature and dropping time in the second step were changed as shown in Table 1. The physical properties of the resulting organosilicon polymer particles 2 to 12 are shown in Table 1.

The abbreviations in Table 1 are as follows.
MTMS: methyltrimethoxysilane MTOS: tetramethoxysilane The measurement results in Table 1 were measured by the above-mentioned measurement method.

<Production Example of Toner 1>
The following materials were mixed using a Henschel mixer (FM-75, manufactured by Mitsui Mining Co., Ltd.) at a rotation speed of 1500 rpm for a rotation time of 5 minutes, and then kneaded in a twin-screw kneader (PCM-30, manufactured by Ikegai Corporation) set at a temperature of 130° C. to obtain a kneaded product.
Binder resin: 100 parts of the following polyester (Tg: 58°C, acid value: 15 mgKOH/g, hydroxyl value: 15 mgKOH/g, Mn: 3600, Mw: 96000); Fischer-Tropsch wax (peak temperature (melting point) of maximum endothermic peak: 90°C); 6.5 parts of C.I. Pigment Blue 15:3; 5.5 parts of C.I. Pigment Blue 15:3. The kneaded product obtained was cooled and coarsely pulverized to 1 mm or less using a hammer mill to obtain a coarsely pulverized product. The coarsely pulverized product obtained was finely pulverized using a mechanical pulverizer (T-250, manufactured by Turbo Kogyo Co., Ltd.) to obtain a finely pulverized product. The finely pulverized product obtained was further classified using a Faculty (F-300, manufactured by Hosokawa Micron Corporation) to obtain toner particles 1 having a weight average particle size of 4.8 μm. The operating conditions of the above faculty were a classifying rotor rotation speed of 11,000 rpm and a dispersing rotor rotation speed of 7,200 rpm.

The polyester used as the binder resin was a polycondensate of 40 parts of polyoxypropylene (2.2)-2,2-bis(4-hydroxyphenyl)propane, 10 parts of polyoxyethylene (2.2)-2,2-bis(4-hydroxyphenyl)propane, 40 parts of terephthalic acid, 2 parts of trimellitic anhydride, and 8 parts of fumaric acid.
Toner particles 1 100 parts Organosilicon polymer particles 1 2 parts The above materials were mixed in a Henschel mixer (FM-75, manufactured by Mitsui Miike Chemical Engineering Co., Ltd.) at a rotation speed of 1900 rpm for a rotation time of 10 minutes.
Silica fine particles A: fumed silica surface-treated with hexamethyldisilazane (median diameter (D50) on a number basis: 120 nm) 4 parts Small particle size inorganic fine particles: titanium oxide fine particles surface-treated with isobutyltrimethoxysilane (median diameter (D50) on a number basis: 10 nm) 1 part The above materials were mixed in a Henschel mixer (FM-75 model, manufactured by Mitsui Miike Chemical Engineering Co., Ltd.) at a rotation speed of 1,900 rpm for a rotation time of 10 minutes to obtain toner 1.

<Production Examples of Toners 2 to 12>
Toners 2 to 12 were obtained by repeating the procedure of Toner 1, except that the type of organosilicon polymer used in Toner 1 was changed as shown in Table 2.

<Production Example of Toner 13>
Toner 13 was obtained in the same manner as in Toner 1 Production Example, except that the organosilicon polymer was not used.

<Production Example of Coating Resin Solution>
First, the raw materials (100 parts in total) shown in Table 3 were added to a four-neck flask equipped with a reflux condenser, a thermometer, a nitrogen suction tube, and a grinding type stirrer. Then, 200.0 parts of toluene, 200.0 parts of methyl ethyl ketone, and 4.0 parts of azobisisovaleronitrile were added, and the mixture was stirred at 80° C. for 10 hours under a nitrogen stream to obtain solutions each containing 20% by mass of the coating resins A-1 to A-3.

In addition, solutions of coating resins C-1 and C-2 were obtained by carrying out the same operations as above, except that the raw materials listed in Table 3 were used and the reaction time and temperature were adjusted.

The abbreviations in Table 3 are as follows:
DM: dimethylaminoethyl methacrylate DMC: dimethylaminoethyl methacrylate-methyl chloride quaternary salt TMP: 2,2,6,6-tetramethyl-4-piperidyl methacrylate MAA: methacrylic acid CHMA: cyclohexyl methacrylate MMA: methyl methacrylate St: styrene Macromonomer A (weight average molecular weight Mw, 5000): methyl methacrylate polymer represented by the following formula (M), in which M' is represented by the following formula (M').

<Production Example of Magnetic Carrier Core 1>
・Process 1 (weighing and mixing process)
Fe ₂ O ₃ 68.3% by mass
MnCO ₃ 28.5% by mass
Mg(OH) ₂ 2.0% by mass
SrCO ₃ 1.2% by mass
The ferrite raw material in the above ratio was weighed, 80 parts of the ferrite raw material was mixed with 20 parts of water, and then wet-mixed in a ball mill using zirconia having a diameter (φ) of 10 mm for 3 hours to prepare a slurry. The solid content of the slurry was 80 mass %.
Step 2 (pre-firing step)
The mixed slurry was dried using a spray dryer (manufactured by Okawara Kakoki Co., Ltd.) and then fired in a batch-type electric furnace in a nitrogen atmosphere (oxygen concentration: 1.0% by volume) at a temperature of 1,050° C. for 3.0 hours to produce calcined ferrite.
Step 3 (crushing step)
The calcined ferrite was crushed to about 0.5 mm with a crusher, and water was added to prepare a slurry with a solid content of 70 mass %. The slurry was then crushed for 3 hours with a wet ball mill using 1/8 inch stainless steel beads. The slurry was further crushed for 4 hours with a wet bead mill using zirconia with a diameter of 1 mm to obtain a calcined ferrite slurry with a volume-based 50% particle size (D50) of 1.3 μm.
・Process 4 (granulation process)
To 100 parts of the calcined ferrite slurry, 1.0 part of ammonium polycarboxylate as a dispersant and 1.5 parts of polyvinyl alcohol as a binder were added, and the mixture was granulated into spherical particles using a spray dryer (manufactured by Okawara Kakoki Co., Ltd.) and dried to obtain a granulated product. The obtained granulated product was subjected to particle size adjustment, and then heated at 700° C. for 2 hours using a rotary electric furnace to remove organic substances such as the dispersant and binder.
Step 5 (firing step)
The material was fired in a nitrogen atmosphere (oxygen concentration 1.0% by volume) for 2 hours from room temperature to the firing temperature (1300° C.), and then held at 1300° C. for 5 hours. The material was then cooled to 60° C. over 8 hours, returned from the nitrogen atmosphere to the air, and taken out at a temperature of 40° C. or less.
Step 6 (sorting step)
After the aggregated particles were crushed, the mixture was sieved with a sieve having an opening of 150 μm to remove coarse particles, air classification to remove fine powder, and a magnetic separator to remove non-magnetic materials.Furthermore, the coarse particles were removed with a vibrating sieve to obtain magnetic carrier cores 1 having a D50 of 34 μm.

<Production Example of Magnetic Carrier 1>
<Formation of first resin coating layer>
The solution of the coating resin A-1 (first resin) was diluted with toluene to a resin solid content of 5% by mass, and the thoroughly stirred resin solution was prepared as a first resin liquid. Then, the first resin liquid was added in an amount such that the resin solid content was 1.0 part per 100.0 parts of the magnetic carrier core 1 to a planetary motion mixer (Nauta Mixer VN type manufactured by Hosokawa Micron Corporation) maintained at a temperature of 60°C, and the solvent was removed and the coating operation was performed for 40 minutes.

The magnetic carrier coated with the first resin was then transferred to a mixer (UD-AT type drum mixer manufactured by Sugiyama Heavy Industries Co., Ltd.) with a spiral blade placed inside a rotatable mixing container, and heat-treated at 180°C for 2 hours in a nitrogen atmosphere while stirring at 10 revolutions per minute.

<Formation of second resin coating layer>
The solution of the coating resin C-1 (second resin) was diluted with toluene to a resin solid content of 5% by mass, and the thoroughly stirred resin solution was prepared as a second resin liquid. Then, the second resin liquid in an amount to give a resin solid content of 1.5 parts and 100.0 parts of the magnetic carrier particles having the first resin coating layer obtained above were charged into a planetary motion mixer maintained at a temperature of 60°C, and the solvent was removed and the coating operation was carried out for 40 minutes.

The magnetic carrier coated with the second resin was then transferred to a mixer equipped with a spiral blade in a rotatable mixing container, and heat-treated at 120°C for 2 hours in a nitrogen atmosphere while stirring at 10 revolutions per minute.

The magnetic carrier obtained after the heat treatment was subjected to magnetic separation to separate out low magnetic particles, which were then passed through a sieve with 150 μm openings and classified using an air classifier to obtain Magnetic Carrier 1. The physical properties of Magnetic Carrier 1 are shown in Table 4.

<Production Examples of Magnetic Carriers 2 to 12>
Magnetic Carriers 2 to 12 were obtained by the same procedure as in the production example of Magnetic Carrier 1, except that the types and amounts of the first and second resins were changed as shown in Table 4. The physical properties of Magnetic Carriers 2 to 12 are shown in Table 4.

The measurement results in Table 4 were measured using the method described above.

<Production Example of Two-Component Developer 1>
The toner 1 and magnetic carrier 1 were placed in a shaker (YS-8D type: manufactured by Yayoi Co., Ltd.) and shaken so that the toner concentration was 7.0% by mass, to prepare two-component developer 1. The vibration conditions of the shaker were 200 rpm and 2 minutes.

<Production Examples of Two-Component Developers 2 to 24>
In the manufacturing example of the two-component developer 1, the same operation was carried out except that the types of the toner and the magnetic carrier were changed as shown in Table 5, to obtain two-component developers 2 to 24.

Example 1
The following evaluations were carried out using the above-mentioned two-component developer 1. The evaluation conditions common to each evaluation are described below.

The image forming apparatus used was a modified color copying machine (product name: ImagePRESS C850, manufactured by Canon Inc.) The modified features of the modified machine were that the image forming speed and development conditions were as follows:
Image formation speed: 85 sheets/min. Development conditions: The development contrast can be adjusted to any value, and automatic correction by the main body is not activated. The peak-to-peak voltage (Vpp) of the alternating electric field is changed in 0.1 kV increments from 0.7 kV to 1.8 kV at a frequency of 2.0 kHz. The voltage (Vdc, development bias) that is the midpoint between the maximum and minimum values of Vpp can be changed.

Additionally, white paper (product name: CS-814 (A4, 81.4 g/m ² ), Canon Marketing Japan Inc.) was used as the evaluation paper. When outputting images, unless otherwise specified, a FFH output chart with an image ratio of 5% was used. FFH is a value in which 256 gradations are expressed in hexadecimal, with 00h being the first gradation (white background) of the 256 gradations and FFH being the 256th gradation (solid area) of the 256 gradations.

In the above image forming device, two-component developer 1 was placed in the cyan developer and each evaluation was performed.

<Evaluation of Image Density Reproducibility in a High-Hand Environment>
In a normal temperature and humidity environment (temperature 23° C., humidity 50 RH%, hereinafter also referred to as "N/N environment"), five images were output under the above image forming conditions, and the density of the output images was measured using an optical densitometer, and the average was taken as image density A. Next, in a high temperature and high humidity environment (temperature 30° C./humidity 80 RH%, hereinafter also referred to as "H/H environment"), the copying machine body was left in the H/H environment for 24 hours, and then five images were output under the above image forming conditions, and the average was taken as image density B. An X-Rite color reflection densitometer (manufactured by X-Rite) was used as the optical densitometer.

The density fluctuation difference shown in the following formula was calculated, and the image density stability was evaluated using the density fluctuation difference. The evaluation results are shown in Table 6. When the density fluctuation difference was less than 0.14, it was determined that the effect of the present invention was obtained.
Density fluctuation difference=|Image density A−Image density B|
<Evaluation of concentration stability with environmental changes>
・(N/L→H/H)
The development contrast was adjusted in the copying machine main body left for 72 hours in a normal temperature and low humidity environment (temperature 23°C/humidity 5RH%, hereinafter also referred to as "N/L environment"), and the output images were set to have the reflection densities of the following patterns 1 to 8, and one image was output for each. Next, without changing the development contrast adjustment, the copying machine main body was left in an H/H environment for 3 hours, and then one image was output again, and the reflection density of the output image was measured. Then, the density stability accompanying environmental changes was evaluated based on how many images output in the H/H environment had reflection densities within the range of the reflection densities of the patterns set in the images output in the N/L environment. The reflection densities of the images were measured using a spectrodensitometer 500 series (manufactured by X-Rite). The evaluation results are shown in Table 6.
Pattern 1: Reflection density 0.10 to 0.14
Pattern 2: Reflection density 0.25 to 0.29
Pattern 3: Reflection density 0.45 to 0.49
Pattern 4: Reflection density 0.65 to 0.69
Pattern 5: Reflection density 0.85 to 0.89
Pattern 6: Reflection density 1.05 to 1.09
Pattern 7: Reflection density 1.25 to 1.29
Pattern 8: Reflection density 1.48 to 1.52
・(H/H→N/L)
The development contrast was adjusted in the copying machine main body left in the H/H environment for 72 hours, and the output image was set to have the reflection density of each of the patterns 1 to 8 shown below, and one image was output for each. Next, without changing the development contrast adjustment, the copying machine main body was left in the N/L environment for 3 hours, and then one image was output again, and the reflection density of the output image was measured. Then, the density stability accompanying environmental changes was evaluated based on how many images output in the N/L environment had reflection densities within the range of the reflection densities of the patterns set in the images output in the H/H environment. The reflection densities of the images were measured using a spectrodensitometer 500 series (manufactured by X-Rite Corporation). The evaluation results are shown in Table 6.

The effect of the present invention was determined to be achieved when four or more patterns were within the range of reflection density of each pattern in the evaluation of (N/L→H/H) and four or more patterns were within the range of reflection density of each pattern in the evaluation of (H/H→N/L). The reflection density of the image was measured using a spectrodensitometer 500 series (manufactured by X-Rite Corporation).
Pattern 1: Reflection density 0.10 to 0.14
Pattern 2: Reflection density 0.25 to 0.29
Pattern 3: Reflection density 0.45 to 0.49
Pattern 4: Reflection density 0.65 to 0.69
Pattern 5: Reflection density 0.85 to 0.89
Pattern 6: Reflection density 1.05 to 1.09
Pattern 7: Reflection density 1.25 to 1.29
Pattern 8: Reflection density 1.48 to 1.52
<Evaluation of charging stability>
The peak-to-peak voltage (Vpp) of the alternating electric field was fixed at 1.3 kV, and Vdc was set so that the reflection density of a solid image of a single color of cyan output in an N/L environment was 1.50, and 20,000 sheets of solid images of a single color of cyan were output with this setting. After that, only Vdc was adjusted while keeping the above setting, and Vdc at which the image density was 1.50 was obtained, and the charge stability of the two-component developer was evaluated by the difference value from the initially set Vdc. In this evaluation, the smaller the difference value from the initially set Vdc, the smaller the change in the charge amount of the two-component developer before and after continuous image output. The reflection density was measured using a spectrodensitometer 500 series (manufactured by X-Rite Corporation).

<Examples 2 to 18 and Comparative Examples 1 to 6>
As shown in Table 6, evaluation was performed in the same manner as in Example 1, except that the corresponding two-component developers 2 to 24 were used. The results are shown in Table 6. Examples 15 to 18 are described as reference examples.

Claims (10)

A two-component developer containing a toner and a magnetic carrier,
the toner comprises toner particles and organosilicon polymer particles on the surfaces of the toner particles;
The organosilicon polymer particles have a T3 unit structure represented by the following formula (1):
R-SiO _3/2 ... (1)
(In formula (1), R represents an alkyl group having 1 to 6 carbon atoms or a phenyl group.)
The magnetic carrier contains magnetic carrier core particles and magnetic carrier particles having a resin coating layer on the surface of the magnetic carrier core particles,
The resin coating layer contains a resin A having a monomer unit A1 containing a nitrogen atom,
The resin A has only the monomer unit A1 as a monomer unit containing a nitrogen atom, and the monomer unit A1 is a monomer unit represented by the following formula (2-1) or a monomer unit represented by the following formula (2-2),

(In formula (2-1), R ¹ , R ² , and R ³ each independently represent a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, R ⁴ represents an alkylene group having 1 to 20 carbon atoms, R′ represents a hydrogen atom or a methyl group, and X ⁻ represents a counter anion.
In formula (2-2), R ¹¹ and R ¹² each independently represent a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, R ¹⁴ represents an alkylene group having 1 to 20 carbon atoms, and R″ represents a hydrogen atom or a methyl group.
In the measurement of carbon element, oxygen element, silicon element, nitrogen element, and iron element of the magnetic carrier particles by X-ray photoelectron spectroscopy,
When the ratio of nitrogen elements originating from resin A on the surface of the magnetic carrier particles is defined as N1 (atom %), N1 is 0.0 to 0.7,
a thickness of the resin coating layer is d (μm), and a ratio of nitrogen element at a position 0.95d from the surface of the magnetic carrier particle is N2 (atom %), the ratio N2 being 0.8 to 13.0. 2. The two-component developer according to claim 1 , wherein the content of the resin A in the resin coating layer is 4.0 to 40.0% by mass. 3. The two-component developer according to claim 1 , wherein N1 is 0.0 to 0.1. 4. The two-component developer according to claim 1 , wherein the organosilicon polymer particles have a water adsorption capacity of 15 cm ³ g ^-1 or more and 30 cm ³ g ^-1 or less at a relative humidity of 80%. 5. The two-component developer according to claim 1 , wherein the organosilicon polymer particles have a relative dielectric constant εr of 4.0 or less, measured at 10 Hz. 6. The two-component developer according to claim 1, wherein the organosilicon polymer particles have a number average particle size of 30 nm or more and 300 nm or less. The two-component developer according to any one of claims 1 to 6 , wherein the resin coating layer further contains a resin B that does not contain a nitrogen atom. The two-component developer according to any one of claims 1 to 7 , wherein the resin coating layer further contains a resin B having a monomer unit B1 represented by the following formula (3):

(In formula (3), ^R6 represents a hydrogen atom or a methyl group, and Y represents a cycloalkyl group having 4 to 12 carbon atoms.) 9. The two-component developer according to claim 7, wherein the content of the resin B in the resin coating layer is 30.0 to 90.0% by mass. the resin coating layer includes two layers, a resin layer A on the magnetic carrier core particle side and a resin layer B on the surface side of the magnetic carrier particle,
the resin constituting the resin layer A is the resin A,
The two-component developer according to claim 7 , wherein the resin constituting the resin layer B is the resin B.

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