JP2022115751A - Magnetic carrier, two-component developer, and developer for replenishment - Google Patents

Abstract

To provide a magnetic carrier that is excellent in both contamination resistance and abrasion resistance even in long-term use under high temperature and high humidity environment and of which charge maintainability is further improved.SOLUTION: A magnetic carrier includes a magnetic core and magnetic carrier particles having a coating resin layer coating the surface of the magnetic core. In the magnetic carrier, the coating resin layer contains a silicone-modified resin and fine particles, the fine particles have a functional group indicated by a formula (1) or a functional group indicated by a formula (2), of which functional group concentration in the fine particle is 20% or more, on the surface, and the magnetic carrier particles have the functional group indicated by the formula (1) or the functional group indicated by the formula (2), of which functional group concentration in the magnetic carrier particle is 0.05% or less, on the surface. (In the formula (1) and the formula (2), R1 is a hydrogen atom or a methyl group.)SELECTED DRAWING: None

Description

The present invention relates to a magnetic carrier, a two-component developer, and a replenishing developer used in an image forming method for visualizing an electrostatic charge image using electrophotography.

Conventionally, in the electrophotographic image forming method, an electrostatic latent image is formed on an electrostatic latent image carrier using various means, and toner is adhered to the electrostatic latent image to form the electrostatic latent image. A method of developing is generally used. For this development, carrier particles called magnetic carrier particles are mixed with the toner, triboelectrically charged to impart an appropriate amount of positive or negative charge to the toner, and the charge is used as a driving force for development. Adopted.

In the two-component development method, functions such as agitating, transporting, and charging the developer can be added to the magnetic carrier, so the division of functions with the toner is clear. There is Here, the magnetic carrier particles often have a structure in which the core is coated with a core for imparting magnetism to acquire transportability and a coating resin for acquiring the ability to impart charge to the toner.

In recent years, due to technological advances in the field of electrophotography, a higher level of longevity of the main body has been demanded, and it is demanded that the magnetic carrier maintain the charge-imparting ability even in long-term use. However, in general, the magnetic carrier has reduced charging sites due to the adhesion of toner components during long-term durability, and moisture adsorption progresses in cracks generated in the coating resin on the surface of the magnetic carrier particles, resulting in a decrease in charging ability. Concentrations are known to vary.

In order to solve the above problems, as a technique for improving the contamination resistance and charge maintenance property of the surface of magnetic carrier particles, an example of using a material with low surface free energy, such as silicone resin, as a coating resin has been adopted ( Patent documents 1-2). Further, in Patent Document 3, by adding hydrophilic fine particles as an intermediate layer to the interface between the core of the magnetic carrier particles and the coating resin, the moisture adhering to the surface of the magnetic carrier particles is absorbed by the intermediate layer, thereby improving charge retention. Techniques for improving are disclosed.

JP-A-2002-91093 JP 2015-138230 A JP 2016-194692 A

However, in general, materials with low surface free energy such as silicone resin can suppress the adhesion of toner components, etc., but the interaction between molecules is weak and they are easily destroyed by external forces. . For this reason, if a silicone resin is used as the coating resin for the magnetic carrier particles, the coating resin may be worn away by the mechanical load that occurs during stirring or transportation in the developing machine, and the surface resistance of the magnetic carrier particles increases. As a result of the lowering, the charging ability of the magnetic carrier sometimes deteriorated.

The present invention provides a magnetic carrier that solves the above problems.
Specifically, the present invention provides a magnetic carrier containing a silicone-modified resin and hydrophilic fine particles in a coating resin layer even when used for a long period of time in a hot and humid environment.

（式（１）および式（２）中、Ｒ１は水素原子またはメチル基である。）
微粒子の官能基濃度＝（Ｘ線光電子分光測定によるフッ素値／ｇ）÷（微粒子の比表面積／ｇ） （計算式１）
磁性キャリア粒子の官能基濃度＝（Ｘ線光電子分光測定によるフッ素値／ｇ）÷（磁性キャリア粒子の比表面積／ｇ） （計算式２） The magnetic carrier of the present invention is
A magnetic carrier comprising a magnetic core and magnetic carrier particles having a coating resin layer covering the surface thereof,
The coating resin layer contains a silicone-modified resin and fine particles,
The fine particles have a functional group represented by formula (1) or a functional group represented by formula (2) on the surface at a functional group concentration of 20% or more of the fine particles,
The magnetic carrier particles have the functional group represented by the formula (1) or the functional group represented by the formula (2) on the surface thereof at a functional group concentration of 0.05% or less,
The functional group concentration of the fine particles and the functional group concentration of the magnetic carrier particles are obtained by Equations 1 and 2, respectively.

(In Formula (1) and Formula (2), R1 is a hydrogen atom or a methyl group.)
Functional group concentration of fine particles = (fluorine value by X-ray photoelectron spectroscopy measurement / g) ÷ (specific surface area of fine particles / g) (calculation formula 1)
Functional group concentration of magnetic carrier particles=(fluorine value/g by X-ray photoelectron spectroscopy)/(specific surface area of magnetic carrier particles/g) (calculation formula 2)

Further, the developer of the present invention is a developer containing the magnetic carrier and the toner.
Further, the replenishing developer of the present invention is a replenishing developer containing the magnetic carrier and the toner.

According to the present invention, it is possible to achieve both excellent contamination resistance and abrasion resistance even when used for a long period of time in a hot and humid environment, and to further improve charge retention.

It is a schematic diagram showing an example of an image forming method. 1 is a schematic diagram showing an example of an image forming method using a full-color image forming apparatus; FIG. FIG. 2 is a schematic diagram showing an example of an image forming method using a replenishing developer; 1 is a schematic diagram showing an example of a toner particle surface treatment apparatus; FIG.

In the present invention, the description of "○○ to XX" representing a numerical range means a numerical range including the lower limit and the upper limit, which are endpoints, unless otherwise specified.

（式（１）および式（２）中、Ｒ１は水素原子またはメチル基である。） The magnetic carrier of the present invention includes magnetic carrier particles having a magnetic core and a coating resin layer coating the surface thereof. The coating resin layer contains a silicone-modified resin and fine particles, and the fine particles have a functional group represented by formula (1) or a functional group represented by formula (2) on their surface at a functional group concentration of 20% or more, and fine particles The functional group concentration of is calculated by the formula 1.
Functional group concentration of fine particles = (fluorine value by X-ray photoelectron spectroscopy measurement / g) ÷ (specific surface area of fine particles / g) (calculation formula 1)
Further, the magnetic carrier particles have the functional group represented by the formula (1) or the functional group represented by the formula (2) on the surface at a functional group concentration of 0.05% or less, and the functional group of the magnetic carrier particles The concentration is obtained by Equation 2.
Functional group concentration of magnetic carrier particles=(fluorine value/g by X-ray photoelectron spectroscopy)/(specific surface area of magnetic carrier particles/g) (calculation formula 2)

(In Formula (1) and Formula (2), R1 is a hydrogen atom or a methyl group.)

By controlling the functional group concentration of the fine particles and the functional group concentration of the magnetic carrier particles within the above range, both excellent stain resistance and wear resistance can be achieved even when used for a long period of time in a hot and humid environment, and charge retention is improved. An even better magnetic carrier can be provided.

The inventors of the present invention consider the effects of using the magnetic carrier having such a configuration as follows.
When the coating resin layer that coats the surface of the magnetic carrier particles contains a silicone-modified resin and hydrophilic fine particles having a functional group represented by formula (1) or formula (2) on the surface at a functional group concentration of 20% or more, The siloxane moieties of the silicone-modified resin having a hydrophobic structure are oriented on the surface of the magnetic carrier particles, improving the contamination resistance of the magnetic carrier. As a result of the siloxane moiety of the silicone-modified resin being oriented on the surface of the magnetic carrier particles, the hydrophilic fine particles are present inside the coating resin layer, so a filler effect is exhibited inside the magnetic carrier particles, and the abrasion resistance of the magnetic carrier is improved. improve. In addition, even if the magnetic carrier is used for a long period of time in a high-humidity environment, the hydrophilic microparticles existing inside the magnetic carrier particles will absorb the moisture adhering to the surface of the magnetic carrier particles. It is considered that the chargeability of the magnetic carrier is maintained because the charge on the surface is not relaxed.

When the functional group concentration of the functional group represented by the formula (1) or (2) on the surface of the fine particles is less than 20%, the fine particles do not become hydrophilic, and the magnetic carrier retains its charge in a high humidity environment. worsens. Further, it is preferable that the functional group concentration of the functional group represented by the formula (1) or (2) is 0.05% or less on the surface of the magnetic carrier particles. When the functional group concentration is 0.05% or less, sufficient charge retention can be maintained.

The concentration of Si atoms on the surface of the magnetic carrier particles as determined by X-ray photoelectron spectroscopy (XPS) analysis is preferably 1.0 atomic % or more and 8.0 atomic % or less. When the concentration of Si atoms is 1.0 atomic % or more, the surface free energy of the magnetic carrier particles can be lowered, so that the contamination resistance is further improved. When the concentration of Si atoms is 8.0 atomic % or less, the intermolecular interaction in the vicinity of the surface of the magnetic carrier particles is increased, so that the abrasion resistance is further improved.

EMBODIMENT OF THE INVENTION Below, the form for implementing this invention is demonstrated in detail.
The magnetic carrier of the present invention includes magnetic carrier particles having a magnetic core and a coating resin layer coating the surface thereof.

[Coating resin layer]
The coating resin layer contains a silicone-modified resin and fine particles.

<Silicone modified resin>
The silicone-modified resin is selected from (i) one or more units selected from the following formulas (3) to (6) and (ii) units represented by the following formulas (3′) to (5′). It is a unit containing one and and having the terminal represented by the formula (6). Further, (iii) units represented by formulas (3′) to (5′) are connected to units represented by formulas (3) to (6) so as to share one oxygen atom. be. The total content of the units represented by formulas (3) to (6) and the units represented by (3′) to (5′) in the silicone-modified resin is 3% by mass or more and 50% by mass or less. is preferred from the viewpoint of stain resistance and abrasion resistance.

In formulas (3) to (6) and formulas (3′) to (5′), R2 to R7 are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a phenyl group, or the number of carbon atoms It is an alkenyl group of 2 to 4, and —O _1/2 represents that O is shared with adjacent Si atoms. Further, in formulas (3') to (5'), ** is a site bonding to an alkylene group or a site bonding to an oxygen atom bonded to a carbon atom.

Examples of alkyl groups having 1 to 4 carbon atoms in R2 to R7 include methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, s-butyl group, t-butyl group and isobutyl group. Examples of the alkenyl group having 2 to 4 carbon atoms include vinyl group, propenyl group, butenyl group and butandienyl group.

Silicone-modified resins are not particularly limited, but examples include silicone-modified (meth)acrylic resins, silicone-modified urethane resins, silicone-modified polyester resins, silicone-modified epoxy resins, silicone-modified polyolefin resins, silicone-modified phenol resins, and silicone-modified melamine resins. mentioned. Among these, silicone-modified (meth)acrylic resins are preferred from the viewpoint of abrasion resistance.

The silicone-modified resin is mainly composed of a unit represented by the following formula (7) and a unit represented by the following formula (8), the mass of the unit represented by the formula (7) is a, and the unit represented by the formula (8) When the mass of is b, the ratio a/b of the mass a of the unit represented by formula (7) to the mass b of the unit represented by formula (8) is preferably 1.00 or more and 30.0 or less .

式（７）中、Ｒ８は、水素原子またはメチル基であり、Ｒ９は、炭素数１～６の炭化水素基、水酸基を置換基として有する炭素数２～４のアルキル基、または、カルボキシ基を置換基として有する炭素数１～４のアルキル基であり、ｌは、１以上の整数である。

In formula (7), R8 is a hydrogen atom or a methyl group, and R9 is a hydrocarbon group having 1 to 6 carbon atoms, an alkyl group having 2 to 4 carbon atoms having a hydroxyl group as a substituent, or a carboxy group. It is an alkyl group having 1 to 4 carbon atoms as a substituent, and l is an integer of 1 or more.

式（８）中、Ｒ１０は、水素原子またはメチル基であり、Ｒ１１は、水素原子または炭素数１～６の炭化水素基であり、Ｒ１２は、単結合、または、炭素数１～５のアルキレンであり、ｍは、１以上の整数である。＊は、シロキサン部位が結合する結合部位であって、下記式（３’）～（５’）で表されるいずれかのユニットの＊＊につながる。

式（３’）～式（５’）で表されるユニットには、下記式（３）～（６）で表されるいずれかのユニットが、１つの酸素原子を共有するように、１つ或いは繰り返してつながっている。

シロキサン部位の末端は、上記式（６）で表されるユニットであり、式（３’）～（５’）及び式（３）～（６）におけるＲ２～Ｒ７は、それぞれ独立して、水素原子、炭素数１～４のアルキル基またはフェニル基であり、－Ｏ_１／２は隣り合うＳｉ原子とＯを共有していることを表し、シロキサン部位中のケイ素元素の数は２～１５０である。

In formula (8), R10 is a hydrogen atom or a methyl group, R11 is a hydrogen atom or a hydrocarbon group having 1 to 6 carbon atoms, and R12 is a single bond or alkylene having 1 to 5 carbon atoms. and m is an integer of 1 or more. * is a bonding site to which a siloxane moiety is bonded, and is connected to ** of any unit represented by formulas (3′) to (5′) below.

In the units represented by formulas (3′) to (5′), any unit represented by the following formulas (3) to (6) shares one oxygen atom, so that one or connected repeatedly.

The terminal of the siloxane moiety is a unit represented by the above formula (6), and R2 to R7 in formulas (3') to (5') and formulas (3) to (6) are each independently hydrogen. an alkyl group having 1 to 4 carbon atoms or a _phenyl group; be.

Examples of hydrocarbon groups having 1 to 6 carbon atoms in R9 and R11 include methyl group, ethyl group, propyl group, isopropyl group, cyclopropyl group, n-butyl group, s-butyl group, t-butyl group, isobutyl group, cyclobutyl group, pentyl group, neopentyl group, cyclopentyl group, hexyl group, cyclohexyl group and the like. In R9, the alkyl group having 2 to 4 carbon atoms substituted with a hydroxyl group includes, for example, 2-hydroxyethyl group, 3-hydroxypropyl group, 2-hydroxyisopropyl group, hydroxycyclopropyl group, 4-hydroxybutyl group, hydroxycyclo Examples of the alkyl group having 1 to 4 carbon atoms (not including the number of carbon atoms in the carboxy group) substituted with a carboxy group, such as a sibutyl group, include a carboxymethyl group, a 2-carboxyethyl group, and a 3-carboxypropyl group. , 4-carboxybutyl group and the like. In R12, the alkylene having 1 to 5 carbon atoms includes, for example, methylene group, ethylene group, propylene group, butylene group, pentylene group, cyclopropylene group, cyclobutylene group, cyclopentylene group and the like. Examples of alkyl groups having 1 to 4 carbon atoms in R2 to R7 include methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, s-butyl group, t-butyl group and isobutyl group.
Since the units represented by formulas (3) to (5) have a plurality of -O _1/2 , the bond with other units is repeated, but the unit represented by formula (6) is When bound, the repetition stops and becomes a terminal.

If a/b is less than 1.00, the structure will have too high a proportion of the units represented by the formula (8), and the adhesion to the magnetic core will be too low, resulting in poor wear resistance. Conversely, if a/b is greater than 30.0, the surface free energy becomes too high, resulting in poor stain resistance. When the number of silicon atoms in the siloxane moiety is from 2 to 150, it is easy to adjust the range of a/b from 1.00 to 30.0, which is preferable.

The coating resin layer may further contain a (meth)acrylic resin not modified with silicone. Since the coating resin layer further has a (meth)acrylic resin that is not modified with silicone, the (meth)acrylic resin chains that are not modified with silicone and the molecular chains other than the siloxane portion of the silicone-modified resin are entangled, thereby improving abrasion resistance. is further improved.

<Fine particles>
The fine particles contained in the coating resin layer of the magnetic carrier particles are not particularly limited to organic particles or inorganic particles, but inorganic particles are preferred from the viewpoint of improving wear resistance due to the filler effect.
Examples of inorganic particles include particles of carbon black, _SrTiO3 , _TiO2 , _{Al2O3 ,} MgO, _SiO2 , and the like.

The volume average particle diameter of the primary particles of the fine particles used in the present invention is preferably 10 nm or more and 100 nm or less. If the particle size is smaller than 10 nm, the particles tend to aggregate with each other and are dispersed in the coating resin layer in the form of aggregates. The agglomerates cause protrusions, and frictional stress on the protrusions increases during long-term use, resulting in a decrease in abrasion resistance. If the particle size exceeds 100 nm, the fine particles themselves form protrusions, and frictional stress on the protrusions increases during long-term use, resulting in a decrease in wear resistance.

The functional group concentration of the functional group represented by formula (1) or (2) on the surface of the fine particles is 20% or more, preferably 30% or more. The fine particles are composed of carbon black, SrTiO ₃ , TiO ₂ , Al ₂ O ₃ , MgO, SiO ₂ , or the like, from the surface of the particles to the terminal via the organic group, represented by formula (1) or formula (2). It may be a structure having a functional group.
The functional group concentration of microparticles|fine-particles shows the ratio of the functional group with respect to the specific surface area of microparticles|fine-particles in the XPS measurement.

When the magnetic carrier particles contain 1.0 parts by mass or more and 20.0 parts by mass or less of the fine particles per 100 parts by mass of the resin of the coating resin layer, the functional group represented by the formula (1) or the functional group represented by the formula (2) It is preferable because the magnetic carrier particles have a functional group concentration of 0.05% or less.

<Method for surface treatment of fine particles>
One method of treating the surface of fine particles is, for example, a method of oxidizing commercially available inorganic particles or carbon black to introduce hydrophilic groups.
Specific examples of the oxidation treatment method include a gas phase oxidation method and a liquid phase oxidation method. The gas-phase oxidation method is an oxidation method by air contact, and oxidizes the surface of fine particles by reaction with nitrogen oxides or ozone. In the liquid-phase oxidation method, fine particles are produced using an oxidizing agent such as nitric acid, potassium permanganate, potassium dichromate, chlorous acid, perchloric acid, hypohalogenous hydrochloric acid, hydrogen peroxide, aqueous bromine solution, and aqueous ozone solution. oxidize the surface of In addition, the surface of carbon black can be oxidized by plasma treatment or the like.

Specific examples of methods for introducing hydrophilic groups by oxidizing the surfaces of fine particles as described above include the following methods. When the surface of carbon black is surface-treated by a liquid phase oxidation method, hydrophilically treated fine particles can be obtained by putting carbon black in a suitable container, adding an aqueous solution of nitric acid to the mixture, refluxing the mixture, and then washing and drying the mixture. can. When the surface of fine particles is treated by vapor phase oxidation, hydrophilically treated fine particles can be obtained by placing the fine particles in an ozonizer and exposing them to an ozone atmosphere generated by an ozonizer. can.

Moreover, as one of the hydrophilic treatment methods, for example, a method of introducing a carboxyl group to a hydroxy group on the particle surface using a lower fatty acid carboxylating agent is exemplified. Furthermore, a methyl group can be introduced into the introduced hydroxy group by using a methylating agent such as methyl iodide or dimethyl sulfate.

Specific examples of carboxylating agents for lower fatty acids include dicarboxylic acids such as succinic acid, maleic acid, phthalic acid, succinic anhydride, maleic anhydride and phthalic anhydride, and acid anhydrides thereof. These lower fatty acid carboxylating agents may be used in combination of two or more. A methyl group can be introduced by using a methylating agent or by subjecting the introduced carboxyl group to methyl esterification.

As a method for introducing a methyl group into the introduced carboxyl group, for example, the following method is preferred. After putting each particle type in a suitable container and making the inside of the system a nitrogen atmosphere, anhydrous toluene, triethylamine, dimethylaminopyridine, and an acid anhydride of a dicarboxylic acid are added and reacted at room temperature to form chemically modified particles. obtain. After that, the obtained chemically modified particles are placed in a suitable container, methanol and calcium carbonate are added, and the mixture is allowed to react at room temperature. After that, the reaction is stopped, and the ends are methyl-esterified by washing and drying. Dicarboxylic acid-treated microparticles can be obtained.

<Magnetic carrier particles>
As the magnetic core of the magnetic carrier particles, known magnetic particles such as magnetite particles, ferrite particles, and magnetic substance-dispersed resin particles can be used. Among them, magnetic particles obtained by filling the pores of porous magnetic particles with a resin or magnetic substance-dispersed resin particles, that is, magnetic particles containing a magnetic oxide and a resin composition, have a small specific gravity of the magnetic carrier particles. This is preferable from the viewpoint of prolonging the life of the magnetic carrier particles.

Reducing the specific gravity of the magnetic carrier particles, for example, reduces the load on the toner in the developer state in the developing device, prevents the adhesion of toner constituents to the surface of the magnetic carrier particles, and reduces the load between the magnetic carrier particles. is also reduced, leading to further suppression of peeling, chipping, and scraping of the resin coating layer. In addition, dot reproducibility can be improved, and high-definition images can be obtained.

Materials for the porous magnetic particles include, for example, magnetite and ferrite. Among them, ferrite is preferable from the viewpoint of ease of control of the porous structure of the porous magnetic particles and ease of adjustment of the resistance of the porous magnetic particles.
Ferrite is a sintered body represented by the following general formula.
(M12O) _x ( _M2O ) _{y ( Fe2O3} ) _z
(In the above general 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 general formula, M1 or M2 includes, for example, 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, and rare earth elements.

In the porous magnetic particles, it is preferable to appropriately control the roughness of the surface of the porous magnetic particles in order to maintain an appropriate amount of magnetization and keep the pore diameter within an appropriate range. In addition, it is preferable that the speed of the ferritization reaction is easily controlled, and that the specific resistance and magnetic force of the porous magnetic particles are easily controlled. From these points of view, Mn-containing ferrite, Mn--Mg-based ferrite, Mn--Mg--Sr-based ferrite, and Li--Mn-based ferrite are more preferable among ferrites.

As the resin to be contained in the pores of the porous magnetic particles, the copolymer resin used in the coating resin layer can be used, but not limited to this, known resins can be used. As the thermoplastic resin, the copolymer used as the coating resin is preferable, but other than that, for example, the following may be mentioned. Polystyrene, polymethyl methacrylate, acrylic resin, methacrylic resin, styrene-acrylate copolymer, styrene-methacrylate copolymer, styrene-butadiene copolymer, ethylene-vinyl acetate copolymer, polyvinyl chloride, polyvinyl Aromatic polyester such as vinyl acetate, polyvinylidene fluoride, fluorocarbon resin, perfluorocarbon resin, solvent-soluble perfluorocarbon resin, polyvinylpyrrolidone, petroleum resin, novolak resin, saturated alkyl polyester, polyethylene terephthalate, polybutylene terephthalate, polyarylate, polyamide, polyacetal , polycarbonate, polyethersulfone, polysulfone, polyphenylene sulfide, polyetherketone.

Examples of thermosetting resins include the following. Phenolic resins, modified phenolic resins, maleic resins, alkyd resins, epoxy resins, acrylic resins, methacrylic resins, unsaturated polyesters obtained by polycondensation of maleic anhydride, terephthalic acid and polyhydric alcohols, urea resins, melamine resins, Urea-melamine resin, xylene resin, toluene resin, guanamine resin, melamine-guanamine resin, acetoguanamine resin, glyptal resin, furan resin, silicone resin, polyimide, polyamideimide, polyetherimide, polyurethane.

When the magnetic core has a volume-based 50% (D50) of 20 μm or more and 80 μm or less, the magnetic core is uniformly coated with the coating resin layer, and the density of the developer magnetic brush is appropriately adjusted to prevent adhesion of the carrier and to obtain a high-quality image. It is preferable in making
Good developability can be obtained when the specific resistance value of the magnetic core at an electric field strength of 1000 (V/cm) is 1.0×10 ⁵ (Ω·cm) or more and 1.0×10 ¹⁴ (Ω·cm) or less. It is preferable because it becomes

Next, physical properties of the magnetic carrier and magnetic carrier particles will be described.
The magnetic carrier preferably has a magnetization intensity of 40 (Am ² /kg) or more and 70 (Am ² /kg) or less under a magnetic field of 5000/4π (kA/m). When the strength of magnetization of the magnetic carrier is within the above range, the magnetic binding force to the developing sleeve is moderate, so the occurrence of carrier adhesion can be suppressed more satisfactorily. Moreover, since the stress applied to the toner in the magnetic brush can be reduced, deterioration of the toner and adhesion to other members can be suppressed satisfactorily.

In addition, the strength of magnetization of the magnetic carrier can be appropriately adjusted by the amount of resin contained in the magnetic carrier particles. The residual magnetization of the magnetic carrier is preferably 20.0 (Am ² /kg) or less, more preferably 10.0 (Am ² /kg) or less. When the residual magnetization of the magnetic carrier is within the above range, particularly good fluidity as a developer can be obtained, and good dot reproducibility can be obtained.

The magnetic carrier preferably has a true density of 2.5 (g/cm ³ ) or more and 5.5 (g/cm ³ ) or less, and preferably 3.0 (g/cm ³ ) or more and 5.0 (g/cm 3 ) or more. ³ ) is more preferably below. A two-component developer containing a magnetic carrier having a true density within this range imposes less load on the toner and suppresses adhesion of toner components to the magnetic carrier. Further, the true density in this range is preferable for the magnetic carrier in order to achieve both good developability in a low electric field strength and prevention of carrier adhesion.

The magnetic carrier preferably has a volume-based 50% diameter (D50) of 21 μm or more and 81 μm or less from the viewpoints of charge imparting ability to toner, suppression of carrier adhesion to image areas, and high image quality. More preferably, it is 25 μm or more and 60 μm.

Next, the configuration of the toner preferable for achieving the object of the present invention will be described in detail below.
<Binder resin>
The toner particles can use, for example, the following polymers as a binder resin. Polymers of styrene such as polystyrene, poly-p-chlorostyrene, and polyvinyltoluene, and substituted polymers thereof; styrene-p-chlorostyrene copolymer, styrene-vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, styrene- Styrene-based copolymers such as acrylic acid ester copolymers and styrene-methacrylic acid ester copolymers; Vinyl chloride, phenolic resin, naturally modified phenolic resin, natural resin modified maleic acid resin, acrylic resin, methacrylic resin, polyvinyl acetate, silicone resin, polyester, polyurethane, polyamide, furan resin, epoxy resin, xylene resin, polyethylene, polypropylene, etc. is mentioned. Among them, it is preferable to use polyester as the main component from the viewpoint of low-temperature fixability.

Monomers used in polyesters include polyhydric alcohols (divalent or trivalent or higher alcohols), polyvalent carboxylic acids (divalent or trivalent or higher carboxylic acids), their acid anhydrides or their lower alkyl esters. Used. Here, in order to express "strain hardening" and to create a branched polymer, it is effective to partially crosslink within the molecule of the amorphous resin. is preferably used. Therefore, it is preferable that a carboxylic acid having a valence of 3 or more, an acid anhydride thereof or a lower alkyl ester thereof, and/or an alcohol having a valence of 3 or more be contained as raw material monomers for the polyester.

As the polyhydric alcohol monomer used for the polyester, the following polyhydric alcohol monomers can be used.

（式中、Ｒはエチレンまたはプロピレン基であり、ｘおよびｙはそれぞれ０以上の整数であり、かつ、ｘ＋ｙの平均値は０以上１０以下である。）
式（Ｂ）で示されるジオール類；

（式（Ｂ）中、Ｒ’は－ＣＨ_２ＣＨ_２－、－ＣＨ_２－ＣＨ（ＣＨ_３）－、または－ＣＨ_２－Ｃ（ＣＨ_３）_２－であり、ｘ’およびｙ’はそれぞれ０以上の整数であり、ｘ’＋ｙ’の平均値は０以上１０以下である。） Dihydric alcohol components include ethylene glycol, propylene glycol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, diethylene glycol, triethylene glycol, 1,5-pentanediol, 1, 6-hexanediol, neopentyl glycol, 2-ethyl-1,3-hexanediol, hydrogenated bisphenol A, also bisphenols represented by formula (A) and derivatives thereof;

(Wherein, R is an ethylene or propylene group, x and y are each an integer of 0 or more, and the average value of x + y is 0 or more and 10 or less.)
diols represented by formula (B);

(In formula (B), R' is -CH ₂ CH ₂ -, -CH ₂ -CH(CH ₃ )-, or -CH ₂ -C(CH ₃ ) ₂ -, and x' and y' are each It is an integer of 0 or more, and the average value of x'+y' is 0 or more and 10 or less.)

Examples of trihydric or higher alcohol components include sorbitol, 1,2,3,6-hexanetetrol, 1,4-sorbitan, pentaerythritol, dipentaerythritol, tripentaerythritol, and 1,2,4-butanetriol. , 1,2,5-pentanetriol, glycerol, 2-methylpropanetriol, 2-methyl-1,2,4-butanetriol, trimethylolethane, trimethylolpropane, 1,3,5-trihydroxymethylbenzene mentioned. Among these, glycerol, trimethylolpropane, and pentaerythritol are preferably used. These dihydric alcohols and trihydric or higher alcohols can be used alone or in combination.

As the polyvalent carboxylic acid monomer used in the polyester resin, the following polyvalent carboxylic acid monomers can be used.

Examples of divalent carboxylic acid components include maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, phthalic acid, isophthalic acid, terephthalic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, malonic acid, n-dodecenylsuccinic acid, isododecenylsuccinic acid, n-dodecylsuccinic acid, isododecylsuccinic acid, n-octenylsuccinic acid, n-octylsuccinic acid, isooctenylsuccinic acid, isooctylsuccinic acid, anhydrides of these acids and Lower alkyl esters of these are included. Among these, maleic acid, fumaric acid, terephthalic acid and n-dodecenylsuccinic acid are preferably used.

Trivalent or higher carboxylic acids, acid anhydrides or lower alkyl esters thereof include, for example, 1,2,4-benzenetricarboxylic acid, 2,5,7-naphthalenetricarboxylic acid and 1,2,4-naphthalenetricarboxylic acid. , 1,2,4-butanetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,3-dicarboxyl-2-methyl-2-methylenecarboxypropane, 1,2,4-cyclohexanetricarboxylic acid, tetra( methylenecarboxyl)methane, 1,2,7,8-octanetetracarboxylic acid, pyromellitic acid, empol trimer acid, their acid anhydrides or their lower alkyl esters. Among these, 1,2,4-benzenetricarboxylic acid, ie, trimellitic acid or derivatives thereof, is particularly preferred because it is inexpensive and reaction control is easy. These bivalent carboxylic acids and trivalent or higher carboxylic acids can be used alone or in combination.

The method for producing the polyester is not particularly limited, and known methods can be used. For example, the above alcohol monomer and carboxylic acid monomer are charged at the same time, polymerized through an esterification reaction or a transesterification reaction, and a condensation reaction to produce a polyester. Moreover, the polymerization temperature is not particularly limited, but is preferably in the range of 180° C. or higher and 290° C. or lower. Polymerization catalysts such as titanium-based catalysts, tin-based catalysts, zinc acetate, antimony trioxide and germanium dioxide can be used in the production of polyester. In particular, polyesters polymerized using tin-based catalysts are more preferred.

In addition, the polyester resin has an acid value of 5 mgKOH/g or more and 20 mgKOH/g or less, and a hydroxyl value of 20 mgKOH/g or more and 70 mgKOH/g or less. It is preferable from the viewpoint of fog resistance because the adhesive force can be kept low.

Also, the binder resin may be a mixture of a low-molecular-weight resin and a high-molecular-weight resin. From the viewpoint of low-temperature fixability and hot-offset resistance, the content ratio of the high-molecular-weight resin and the low-molecular-weight resin is preferably 40/60 or more and 85/15 or less on a mass basis.

<Release agent>
Examples of waxes used for toner particles include the following. Hydrocarbon waxes such as low molecular weight polyethylene, low molecular weight polypropylene, alkylene copolymers, microcrystalline wax, paraffin wax and Fischer-Tropsch wax; oxides of hydrocarbon waxes such as oxidized polyethylene wax or block copolymers thereof; Waxes containing fatty acid esters as a main component such as carnauba wax; partially or wholly deoxidized fatty acid esters such as deoxidized carnauba wax. Furthermore, the following are mentioned. saturated straight-chain fatty acids such as palmitic acid, stearic acid and montanic acid; unsaturated fatty acids such as brassic acid, eleostearic acid and valinaric acid; saturated alcohols such as silyl alcohol; polyhydric alcohols such as sorbitol; fatty acids such as palmitic acid, stearic acid, behenic acid and montanic acid; Esters with alcohols such as silalcohol; Fatty acid amides such as linoleic acid amide, oleic acid amide and lauric acid amide; saturated fatty acid bisamides such as acid amides; unsaturated fatty acid amides such as ethylenebisoleic acid amide, hexamethylenebisoleic acid amide, N,N'dioleyladipic acid amide, N,N'dioleylsebacic acid amide; - aromatic bisamides such as xylene bisstearic acid amide and N,N' distearyl isophthalic acid amide; aliphatic metal salts such as calcium stearate, calcium laurate, zinc stearate and magnesium stearate (generally called metal soap) waxes obtained by grafting vinyl monomers such as styrene and acrylic acid to aliphatic hydrocarbon waxes; partial esters of fatty acids and polyhydric alcohols such as behenic acid monoglyceride; hydrogen of vegetable oils and fats A methyl ester compound having a hydroxyl group obtained by addition.

Among these waxes, hydrocarbon waxes such as paraffin wax and Fischer-Tropsch wax, or fatty acid ester waxes such as carnauba wax are preferred from the viewpoint of improving low-temperature fixability and fixability. In the present invention, hydrocarbon waxes are more preferable in terms of further improving hot offset resistance.

The wax content in the toner particles is preferably 3 parts by mass or more and 8 parts by mass or less per 100 parts by mass of the binder resin.
Moreover, in the endothermic curve during temperature rise measured by a differential scanning calorimeter (DSC), the peak temperature of the maximum endothermic peak of the wax is preferably 45° C. or higher and 140° C. or lower. When the peak temperature of the maximum endothermic peak of the wax is within the above range, the storage stability and hot offset resistance of the toner can be compatible, which is preferable.

<Colorant>
The toner particles may contain a colorant. Colorants include the following.

Black colorants include those toned black using carbon black; yellow colorants, magenta colorants and cyan colorants. A pigment may be used alone as a coloring agent, but it is more preferable to use a dye and a pigment in combination to improve the definition from the viewpoint of image quality of a full-color image.

Examples of magenta toner pigments include the following. 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, 146, 147, 150, 163, 184, 202, 206, 207, 209, 238, 269, 282; I. Pigment Violet 19; C.I. 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. I. disperse thread 9;C. I. Solvent Violet 8, 13, 14, 21, 27; C.I. I. Oil-soluble dyes such as Disper Violet 1, C.I. I. Basic Red 1, 2, 9, 12, 13, 14, 15, 17, 18, 22, 23, 24, 27, 29, 32, 34, 35, 36, 37, 38, 39, 40; C.I. I. Basic dyes such as Basic Violet 1, 3, 7, 10, 14, 15, 21, 25, 26, 27, 28.

Examples of cyan toner pigments include the following. C. I. Pigment Blue 2, 3, 15:2, 15:3, 15:4, 16, 17; C.I. I. Bat Blue 6; C.I. I. Acid Blue 45, a copper phthalocyanine pigment having a phthalocyanine skeleton substituted with 1 to 5 phthalimidomethyl groups.
As dyes for cyan toners, C.I. I. Solvent Blue 70 can be mentioned.

Examples of yellow toner pigments include the following. 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, 94, 95, 97, 109, 110, 111, 120, 127, 128, 129, 147, 151, 154, 155, 168, 174, 175, 176, 180, 181, 185; I. Bat Yellow 1, 3, 20.
As a yellow toner dye, C.I. I. Solvent Yellow 162 is mentioned.

These colorants can be used singly or in combination, or in the form of a solid solution. Colorants are selected in terms of hue angle, chroma, brightness, lightfastness, OHP transparency, and dispersibility in toner.
The content of the colorant is preferably 0.1 parts by mass or more and 30.0 parts by mass or less with respect to the total amount of the resin components.

<Inorganic fine particles>
The toner preferably contains inorganic fine particles for the main purpose of improving fluidity and chargeability, and is preferably in the form of adhering to the toner surface.
Silica particles having a maximum peak particle size of 80 nm or more and 200 nm or less based on the number distribution are preferable as the inorganic fine particles as spacer particles for enhancing the releasability between the toner and the magnetic carrier. It is more preferable that the particle size is 100 nm or more and 150 nm or less in order to suppress detachment from the toner more satisfactorily while functioning as spacer particles.
In addition, in order to improve the fluidity of the toner, it is preferable to contain inorganic fine particles having a maximum peak particle size of 20 nm or more and 50 nm or less based on the number distribution, and it is also preferable to use them together with silica particles.

Furthermore, other external additives may be added to the toner particles with the aim of improving fluidity and transferability. The external additive externally added to the surface of the toner particles preferably contains inorganic fine particles such as titanium oxide, alumina oxide and silica, and a plurality of types may be used in combination.

The total content of the external additive is preferably 0.3 parts by mass or more and 5.0 parts by mass or less, and is 0.8 parts by mass or more and 4.0 parts by mass or less with respect to 100 parts by mass of the toner particles. is more preferable. Among them, the content of silica particles having a maximum peak particle size of 80 nm or more and 200 nm or less based on number distribution is 0.1 parts by mass or more and 2.5 parts by mass or less, more preferably 0.5 parts by mass or more and 2.0 parts by mass It is below the department. Within this range, the effect of spacer particles becomes more pronounced.

In addition, it is preferable that the surfaces of silica particles and inorganic fine particles used as an external additive are subjected to a hydrophobic treatment. The hydrophobizing treatment is preferably carried out with coupling agents such as various titanium coupling agents and silane coupling agents; fatty acids and metal salts thereof; silicone oils; or combinations thereof.

Examples of titanium coupling agents include the following. Tetrabutyl titanate, tetraoctyl titanate, isopropyl triisostearoyl titanate, isopropyl tridecylbenzenesulfonyl titanate, bis(dioctyl pyrophosphate) oxyacetate titanate.

Moreover, as a silane coupling agent, the following are mentioned, for example. γ-(2-aminoethyl)aminopropyltrimethoxysilane, γ-(2-aminoethyl)aminopropylmethyldimethoxysilane, γ-methacryloxypropyltrimethoxysilane, N-β-(N-vinylbenzylaminoethyl)γ - aminopropyltrimethoxysilane hydrochloride, hexamethyldisilazane, methyltrimethoxysilane, butyltrimethoxysilane, isobutyltrimethoxysilane, hexyltrimethoxysilane, octyltrimethoxysilane, decyltrimethoxysilane, dodecyltrimethoxysilane, phenyl trimethoxysilane, o-methylphenyltrimethoxysilane, p-methylphenyltrimethoxysilane.

Examples of fatty acids include the following. Long-chain fatty acids such as undecylic acid, lauric acid, tridecylic acid, dodecylic acid, myristic acid, palmitic acid, pentadecylic acid, stearic acid, heptadecylic acid, arachidic acid, montanic acid, oleic acid, linoleic acid, arachidonic acid. Metals of these fatty acid metal salts include, for example, zinc, iron, magnesium, aluminum, calcium, sodium, and lithium.

Examples of silicone oils include dimethylsilicone oil, methylphenylsilicone oil, and amino-modified silicone oil.

In the hydrophobization treatment, a hydrophobizing agent is added to the particles to be treated in an amount of 1% to 30% by mass (more preferably 3% to 7% by mass) relative to the particles to be treated. It is preferably carried out by coating.
The degree of hydrophobization of the hydrophobized external additive is not particularly limited. Hydrophobicity indicates the wettability of a sample to methanol, and is an index of hydrophobicity.

<Two-component developer>
When the magnetic carrier of the present invention is mixed with a toner and used as a two-component developer, the toner concentration in the two-component developer is preferably 2% by mass or more and 15% by mass or less, more preferably 4% by mass. % or more and 13 mass % or less. Good images can be obtained when the toner concentration is within the above range. If the toner concentration is less than 2% by mass, the image density tends to decrease, and if it exceeds 15% by mass, fogging and in-machine scattering tend to occur.

<Replenishment developer>
The replenishment developer is a developer that is replenished when the toner is consumed and the toner concentration in the developing device is lowered in the course of image formation. A developer container contains a predetermined amount of two-component developer containing a predetermined ratio of toner and carrier at the time of shipment. . Therefore, replenishing developer containing toner is supplied to the developing container according to the toner density in the developing container. The replenishing developer contains 2 parts by mass or more and 50 parts by mass or less of toner with respect to 1 part by mass of the magnetic carrier.

Next, an image forming apparatus equipped with a developing device using a two-component developer and a replenishing developer will be described as an example, but the developing device used in the developing method of the present invention is not limited to this. .

<Image forming method>
As shown in FIG. 1, the electrostatic latent image carrier 1 rotates in the direction of the arrow. An electrostatic latent image carrier 1 is charged by a charger 2 as a charging means, and the surface of the charged electrostatic latent image carrier 1 is exposed by an exposure device 3 as an electrostatic latent image forming means to generate an electrostatic latent image. An image is formed. In the developing device 4, a developing container 5 containing a two-component developer and a developer carrier 6 are rotatably arranged, and the developer carrier 6 contains a magnet 7 as magnetic field generating means. At least one of the magnets 7 is installed so as to face the latent image carrier. The two-component developer is held on the developer carrier 6 by the magnetic field of the magnet 7 , and the amount of the two-component developer is regulated by the regulating member 8 . be transported. In the developing section, the magnetic field generated by the magnet 7 forms a magnetic brush. After that, the electrostatic latent image is visualized as a toner image by applying a developing bias obtained by superimposing an alternating electric field on a DC electric field. A toner image formed on the electrostatic latent image carrier 1 is electrostatically transferred to a recording medium (transfer material) 12 by a transfer charger 11 . Here, as shown in FIG. 2, the toner image may be temporarily transferred from the electrostatic latent image carrier 1 to the intermediate transfer member 9 and then electrostatically transferred to the recording medium 12 .

After that, the recording medium 12 is conveyed to a fixing device 13 where the toner is fixed on the recording medium 12 by being heated and pressurized. After that, the recording medium 12 is discharged outside the apparatus as an output image. It should be noted that the toner remaining on the electrostatic latent image carrier 1 is removed by the cleaner 15 after the transfer process. After that, the electrostatic latent image carrier 1 cleaned by the cleaner 15 is electrically initialized by light irradiation from the pre-exposure 16, and the above image forming operation is repeated.

FIG. 2 is a schematic diagram showing an example of an image forming method using a full-color image forming apparatus.
The arrows indicating the arrangement of the image forming units such as K, Y, C, and M in FIG. 2 and the direction of rotation are not limited to these. K stands for black, Y for yellow, C for cyan, and M for magenta. In FIG. 2, electrostatic latent image carriers 1K, 1Y, 1C and 1M rotate in the direction of the arrow. Each electrostatic latent image carrier is charged by chargers 2K, 2Y, 2C and 2M, which are charging means. It is exposed by 3Y, 3C and 3M to form an electrostatic latent image. After that, the electrostatic latent image is formed into a toner image by a two-component developer carried on developer carriers 6K, 6Y, 6C, and 6M provided in developing devices 4K, 4Y, 4C, and 4M, which are developing means. visualized. Further, the toner image is transferred onto the intermediate transfer member 9 by intermediate transfer chargers 10K, 10Y, 10C and 10M, which are transfer means. Further, the toner image is transferred to a recording medium 12 by a transfer charger 11 as transfer means, and the recording medium 12 is fixed under heat and pressure by a fixing device 13 as fixing means, and the toner image is output as an image. An intermediate transfer member cleaner 14, which is a cleaning member for the intermediate transfer member 9, collects transfer residual toner and the like. As a developing method, an AC voltage is applied to the developer carrier 6 to form an alternating electric field in the developing region, and development is performed in a state in which the magnetic brush is in contact with the electrostatic latent image carrier 1 . preferable. The distance (SD distance) between the developer bearing member (developing sleeve) 6 and the electrostatic latent image bearing member 1 is preferably 100 μm or more and 1000 μm or less to prevent magnetic carrier adhesion and improve dot reproducibility. is. If it is narrower than 100 μm, the supply of developer tends to be insufficient, resulting in low image density. If the thickness exceeds 1000 μm, the lines of magnetic force from the magnetic pole S1 spread and the density of the magnetic brush becomes low, resulting in poor dot reproducibility and weakening of the force for constraining the magnetic coated carrier, making carrier adhesion likely to occur.

The peak-to-peak voltage (Vpp) of the alternating electric field is 300V or more and 3000V or less, preferably 500V or more and 1800V or less. The frequency of the alternating electric field is 500 Hz or more and 10000 Hz or less, preferably 1000 Hz or more and 7000 Hz or less. The peak-to-peak voltage and frequency of the alternating electric field can be appropriately selected and used depending on the process. Examples of AC bias waveforms for forming an alternating electric field include triangular waves, rectangular waves, sine waves, and waveforms with different duty ratios. In order to cope with changes in the toner image forming speed, it is preferable to apply a development bias voltage having a discontinuous AC bias voltage (intermittent alternating voltage) to the developer carrying member for development. If the applied voltage of the developing bias voltage is lower than 300 V, it may be difficult to obtain a sufficient image density, and the fog toner in the non-image portion may not be recovered satisfactorily. Further, when the voltage exceeds 3000 V, the electrostatic latent image is disturbed via the magnetic brush, and the image quality may be deteriorated.

By using a two-component developer having a well-charged toner, the fog removal voltage (Vback) can be lowered, and the primary charge of the electrostatic latent image carrier can be lowered. The life of the image carrier can be extended. Vback is preferably 200 V or less, more preferably 150 V or less, depending on the development system. A contrast potential of 100 V or more and 400 V or less is preferably used so as to obtain a sufficient image density.

If the frequency is lower than 500 Hz, the structure of the electrostatic latent image-carrying photoreceptor may be the same as that of the photoreceptor used in the image forming apparatus, although this affects the process speed. For example, an electrostatic latent image carrier having a structure in which a conductive layer, an undercoat layer, a charge generation layer, a charge transport layer and, if necessary, a charge injection layer are provided in order on a conductive substrate such as aluminum or SUS. .
The conductive layer, the undercoat layer, the charge generation layer, and the charge transport layer may be those used in photoreceptors used in image forming apparatuses. As the outermost layer of the electrostatic latent image carrier, for example, a charge injection layer or a protective layer may be used.

The flow of the developer in the image forming apparatus using the replenishment developer will be described with reference to FIG. As the electrostatic latent image on the photosensitive member is developed with toner, the toner in the developing device 102 (indicated by black circles in FIG. 3) is consumed. When the toner density detection sensor 105 detects that the toner in the developing device 102 is low, the developer for replenishment is supplied to the developing device 102 from the developer storage container 101 for replenishment. The excess magnetic carrier in the developing device 102 (represented by white circles in FIG. 3) moves to the developer collection container 104 via the discharging device 106 . Note that the developer collection container 104 may collect the toner collected by the cleaning device 103 together.

<Method for measuring volume-based 50% diameter (D50) of magnetic carrier and magnetic core>
The particle size distribution is measured by, for example, a laser diffraction/scattering type particle size distribution analyzer (trade name: Microtrac MT3300EX, manufactured by Nikkiso Co., Ltd.).
The volume-based 50% diameter (D50) of the magnetic carrier and magnetic core was measured using a sample feeder for dry measurement (trade name: one-shot dry sample conditioner Turbotrac, manufactured by Nikkiso Co., Ltd.). Turbotrac is supplied with a dust collector as a vacuum source, an air volume of about 33 l/sec, and a pressure of about 17 kPa. Control is performed automatically on software. As for the particle size, a 50% particle size (D50), which is a volume-average cumulative value, is obtained. Control and analysis are performed using attached software (version 10.3.3-202D). The measurement conditions are as follows.
SetZero time: 10 seconds Measurement time: 10 seconds Number of measurements: 1 Particle refractive index: 1.81%
Particle shape: Non-spherical Measurement upper limit: 1408 µm
Measurement lower limit: 0.243 μm
Measurement environment: 23°C, 50% RH

<Measurement of Pore Diameter and Pore Volume of Porous Magnetic Core>
The pore size distribution of the porous shaped magnetic core is measured by mercury porosimetry.
The measurement principle is as follows.
In this measurement, the pressure applied to the mercury is changed, and the amount of mercury that has penetrated into the pores is measured. The conditions under which mercury can penetrate into the pores can be expressed by PD=-4σ cos θ from the force balance, where θ and σ are the pressure P, the pore diameter D, the contact angle of mercury, and the surface tension. If the contact angle and surface tension are constants, the pressure P is inversely proportional to the pore diameter D into which mercury can enter. Therefore, the horizontal axis P of the PV curve, which can be obtained by measuring the pressure P and the infiltration liquid amount V at that time, by changing the pressure, is directly replaced by the pore diameter from this equation, and the pore distribution is obtained. there is
As a measuring device, for example, a fully automatic multifunctional mercury porosimeter PoreMaster series/PoreMaster-GT series manufactured by Yuasa Ionics, an automatic porosimeter Autopore IV 9500 series manufactured by Shimadzu Corporation, etc. can be used.

Specifically, using Autopore IV9520 manufactured by Shimadzu Corporation, measurement was performed under the following conditions and procedures.
Measurement conditions Measurement environment 20°C
Measurement cell Sample volume 5 cm ³ Press-in volume 1.1 cm ³ Application Powder Measurement range 2.0 psia (13.8 kPa) to 59989.6 psia (413.7 kPa) Measurement steps 80 steps
(When the pore diameter is taken logarithmically, the steps are carved so that they are evenly spaced.)
Injection parameters Exhaust pressure 50 μmHg
Exhaust time 5.0min
Mercury injection pressure 2.0 psia (13.8 kPa)
Equilibration time 5 secs
High pressure parameter Equilibration time 5 secs
Mercury parameters Advancing contact angle 130.0 degrees
receding contact angle 130.0 degrees
Surface tension 485.0 mN/m (485.0 dynes/cm)
Mercury density 13.5335g/mL

Measurement procedure (1) About 1.0 g of a porous magnetic core is weighed and placed in a sample cell.
Enter the weighing value.
(2) Measure the range of 2.0 psia (13.8 kPa) to 45.8 psia (315.6 kPa) at the low pressure section.
(3) Measure the range of 45.9 psia (316.3 kPa) to 59989.6 psia (413.6 MPa) at the high pressure section.
(4) Calculate the pore size distribution from the mercury injection pressure and the mercury injection amount.
(2), (3), and (4) were automatically performed using the software attached to the apparatus.
From the pore size distribution measured as described above, the pore size at which the differential pore volume is maximized in the pore size range of 0.1 μm or more and 3.0 μm or less is read, and the differential pore volume becomes maximum. Pore size.
Also, the pore volume obtained by integrating the differential pore volume in the pore diameter range of 0.1 μm or more and 3.0 μm or less was calculated using the accompanying software.

<Method for measuring weight average particle size (D4)>
The weight-average particle diameter (D4) of the toner was measured using a precision particle size distribution measuring device (trade name: Coulter Counter Multisizer 3 (registered trademark), manufactured by Beckman Coulter, Inc.) using a pore electrical resistance method equipped with a 100 μm aperture tube. , attached dedicated software (trade name: Beckman Coulter Multisizer 3 Version 3.51, manufactured by Beckman Coulter, Inc.) for setting measurement conditions and analyzing measurement data was used. Measurement was performed with 25,000 effective measurement channels, and the measurement data was analyzed and calculated.
As the electrolytic aqueous solution used for measurement, a solution obtained by dissolving special grade sodium chloride in ion-exchanged water to a concentration of about 1% by mass, for example, "ISOTON II" (manufactured by Beckman Coulter, Inc.) can be used.

Before performing the measurement and analysis, the dedicated software was set as follows.
In the "change standard measurement method (SOM) screen" of the dedicated software, set the total number of counts in control mode to 50000 particles, set the number of measurements to 1, and set the Kd value to "standard particle 10.0 μm" (Beckman Coulter Co., Ltd. (manufactured) to set the value obtained using By pressing the threshold/noise level measurement button, the threshold and noise level are automatically set. Also, set the current to 1600 μA, the gain to 2, the electrolyte to ISOTON II, and check the flash of aperture tube after measurement.
In the "pulse-to-particle size conversion setting screen" of the dedicated software, set the bin interval to logarithmic particle size, the particle size bin to 256 particle size bins, and the particle size range from 2 μm to 60 μm.

A specific measuring method is as follows.
(1) About 200 ml of the electrolytic aqueous solution is placed in a 250 ml round-bottom glass beaker exclusively for Multisizer 3, set on a sample stand, and stirred with a stirrer rod counterclockwise at 24 rotations/sec. Then, use the analysis software's "flush aperture" function to remove dirt and air bubbles inside the aperture tube.
(2) About 30 ml of the electrolytic aqueous solution is placed in a 100 ml flat-bottom glass beaker. As a dispersant, "Contaminon N" (a 10% by mass aqueous solution of a neutral detergent for cleaning precision measuring instruments at pH 7 consisting of a nonionic surfactant, an anionic surfactant, and an organic builder, manufactured by Wako Pure Chemical Industries, Ltd.) was used as a dispersant. ) is diluted with ion-exchanged water to 3 times the mass, and about 0.3 ml of the diluted solution is added.
(3) Two oscillators with an oscillation frequency of 50 kHz are built in with a phase shift of 180 degrees, and placed in a water tank of an ultrasonic disperser with an electrical output of 120 W "Ultrasonic Dispersion System Tetora 150" (manufactured by Nikkaki Bios Co., Ltd.). Add a certain amount of deionized water. About 2 ml of the contaminon N is added to this water bath.
(4) The beaker of (2) is set in the beaker fixing hole of the ultrasonic disperser, and the ultrasonic disperser is operated. Then, the height position of the beaker is adjusted so that the resonance state of the liquid level of the electrolytic aqueous solution in the beaker is maximized.
(5) While the electrolytic aqueous solution in the beaker in (4) above is being irradiated with ultrasonic waves, about 10 mg of toner is added little by little to the electrolytic aqueous solution and dispersed. Then, the ultrasonic dispersion treatment is continued for another 60 seconds. In the ultrasonic dispersion, the temperature of the water in the water tank is appropriately adjusted to 10°C or higher and 40°C or lower.
(6) Using a pipette, drop the electrolytic aqueous solution of (5) in which the toner is dispersed into the round-bottomed beaker of (1) set in the sample stand, and adjust the measured concentration to about 5%. . The measurement is continued until the number of measured particles reaches 50,000.
(7) Analyze the measurement data with the dedicated software attached to the apparatus, and calculate the weight average particle size (D4). The weight average particle diameter (D4) is the "average diameter" on the analysis/volume statistics (arithmetic mean) screen when graph/vol% is set using dedicated software.

<Powder X-ray diffraction analysis>
An XRD pattern was measured using an X-ray diffraction analyzer (X'pert PRO-MPD: manufactured by PANalytical).
X-rays were generated at an acceleration voltage of 45 kV and a current of 40 mA.
The measurement conditions for powder X-rays are
Divergence slit: 1/4 rad (fixed)
Scattering prevention slit: 1/2 rad
Solar slit: 0.04rad
Mask: 15mm
Anti-scatter slit: 7.5mm
Spinner: Available Measurement method Scan axis: Continuous 2θ/θ
Measurement range: 5.0≤2θ≤80°
Step interval: 0.026deg/s
Scanning speed: 0.525deg/s
was measured.
The sample used for measuring P70 has the same formulation as the porous ferrite core material, and an external magnetic field of 5000/4π (kA/m) is applied by changing the oxygen concentration in the firing process during manufacturing. Particles adjusted to have a magnetization strength of 70 Am ² /kg are used.

<Method for measuring strength of magnetization of magnetic core>
The strength of magnetization of the magnetic core can be determined by a vibrating magnetic field type magnetic property measuring device (Vibrating sample magnetometer) or a DC magnetic property recording device (BH tracer). In the examples described later, measurements are carried out using an oscillating magnetic field type magnetic property measuring apparatus BHV-30 (manufactured by Riken Denshi Co., Ltd.) according to the following procedure.
The sample is a cylindrical plastic container filled with sufficiently dense magnetic cores. Measure the actual mass of the sample filled in the container. After that, the sample in the plastic container is adhered with an instant adhesive so that the sample does not move.
A standard sample is used to calibrate the external magnetic field axis and magnetization moment axis at 5000/4π (kA/m).
The intensity of magnetization was measured from a loop of magnetization moment applied with an external magnetic field of 5000/4π (kA/m) at a sweep speed of 5 (min/roop). From these, the strength of magnetization of the magnetic core (Am ² /kg) is obtained by dividing by the weight of the sample.

<Measurement method of surface functional group concentration>
Calculation method of fluorine value by XPS measurement Fine particles or carrier particles (hereinafter simply referred to as "particles" in "calculation method of fluorine value by XPS measurement" and "method of measuring specific surface area of fine particles and carrier particles") on indium foil. ) is applied at 10 mg. At that time, the particles are evenly adhered so that the indium foil portion is not exposed. 1.0 ml of 2,2,2-trifluoroethanol is added dropwise to a 30 ml screw vial to saturate the system with steam. The particles together with the indium foil are placed in the system and left for 12 hours while the particles are exposed to an atmosphere of 2,2,2-trifluoroethanol. At this time, care should be taken so that the particles do not directly adhere to the 2,2,2-trifluoroethanol solution.
Next, 1.0 ml of trifluoroacetic anhydride is added dropwise to a 30 ml screw vial to saturate the system with steam. The particles together with the indium foil are placed in the system and left for 12 hours while the particles are exposed to the atmosphere of trifluoroacetic anhydride.
The particles were taken out of the system together with the indium foil, and left for 6 hours in a depressurized dryer at a set temperature of 25°C. When XPS analysis is performed on the obtained particles, an XPS peak of fluorine derived from 2,2,2-trifluoroethyl ester is detected.

As for the measuring device and measuring conditions, for example, the surface functional group concentration can be obtained using the following measuring device and measuring conditions.
Device: PHI5000VERSAPROBEII (ULVAC-Phi, Inc.)
Irradiation line: Al Kd line Output: 25W 15kV
Pass Energy: 29.35 eV
Stepsize: 0.125 eV
XPS peaks (P2): _C1S (CB), _Ti2P ( _TiO2 , _SrTiO2 ), _Al2P ( _Al2O3 ), _Mg2P (MgO), _{Zn2P3/2 (} ZnO), _Si2P ( _SiO2 )

-Method for measuring specific surface area of fine particles and carrier particles The BET specific surface area is measured using a specific surface area measuring device (trade name: Tristar 3000, manufactured by Shimadzu Corporation).
The specific surface area of the particles is obtained by adsorbing nitrogen gas on the sample surface according to the BET method and calculating the specific surface area using the BET multipoint method. Before measuring the specific surface area, about 2 g of a sample is accurately weighed into a sample tube, and the tube is evacuated at room temperature for 24 hours. After evacuation, the mass of the entire sample cell is measured, and the exact mass of the sample is calculated from the difference from the empty sample cell.
Place empty sample cells in the balance and analysis ports of the BET measuring device. Next, a Dewar bottle containing liquid nitrogen is set at a predetermined position, and P0 is measured by a saturated vapor pressure (P0) measurement command. After the P0 measurement is completed, the prepared sample cell is set in the analysis port, and after inputting the sample mass and P0, the measurement is started by the BET measurement command. After that, the BET specific surface area is automatically calculated.
(Surface functional group concentration of particles) = (fluorine value by X-ray photoelectron spectroscopy measurement/g)/(specific surface area of particles/g)

<Method for measuring Si atom concentration by XPS measurement>
In the same manner as in the above "Method for Calculating Fluorine Value by XPS Measurement", the carrier particles are evenly adhered onto the indium foil so that the indium foil portion is not exposed.
The Si atomic concentration can be obtained, for example, using the following measuring apparatus and measuring conditions.
Device: PHI5000VERSAPROBEII (ULVAC-Phi, Inc.)
Irradiation line: Al Kd line Output: 25W 15kV
Pass Energy: 58.7 eV
Stepsize: 0.125 eV
XPS peaks: C1s, O1s, Si2p, Ti2p, Sr3d

<Magnetic carrier manufacturing method>
Any magnetic core may be used as the magnetic core of the magnetic carrier particles, and methods for producing porous magnetic particles and magnetic material-dispersed resin particles as the magnetic core are described below.

(Method for producing magnetic substance-dispersed resin particles)
An exemplary method for producing the magnetic material-dispersed resin particles includes the following method. For example, submicron magnetic materials such as iron powder, magnetite particles, and ferrite particles are kneaded so as to be dispersed in a thermoplastic resin, pulverized to a desired magnetic core particle size, and thermally or mechanically treated as necessary. It can be obtained by performing a spheroidizing treatment. It can also be produced by dispersing submicron magnetic material in a resin monomer and polymerizing the monomer to form a resin. Examples of thermoplastic resins in this case include resins such as vinyl resins, polyesters, epoxy resins, phenolic resins, urea resins, polyurethanes, polyimides, cellulose resins, silicone resins, acrylic resins and polyethers. The resin may be of one kind or a mixed resin containing two or more kinds of resins. In particular, phenol resin is preferable in that it increases the strength of the magnetic core. The true density and specific resistance can be adjusted by adjusting the amount of magnetic material. Specifically, in the case of magnetic particles, it is preferable to add 70% by mass or more and 95% by mass or less to the carrier.

(Method for producing porous magnetic particles)
The manufacturing process when ferrite is used as the porous magnetic carrier particles will be described in detail below.

<Step 1 (weighing and mixing step)>
The ferrite raw materials are weighed and mixed.
Examples of raw materials for ferrite include metal particles of the above metal elements, oxides, hydroxides, oxalates, and carbonates thereof.
Mixing devices include, for example, ball mills, planetary mills, Giotto mills, vibrating mills, and the like. Among these, a ball mill is preferable from the viewpoint of mixability.
For example, a weighed ferrite raw material and balls are placed in a ball mill, pulverized and mixed for 0.1 hour or more and 20.0 hours or less.

<Step 2 (temporary firing step)>
The pulverized and mixed raw material of ferrite is calcined in the atmosphere or under a nitrogen atmosphere at a calcination temperature in the range of 700° C. or more and 1200° C. or less for 0.5 hours or more and 5.0 hours or less, It is ferritized to obtain calcined ferrite. For firing, for example, a firing furnace such as a burner firing furnace, a rotary firing furnace, or an electric furnace can be used.

<Step 3 (crushing step)>
The calcined ferrite obtained in step 2 is pulverized by a pulverizer.
Examples of pulverizers include crushers, hammer mills, ball mills, bead mills, planetary mills, and Giotto mills.
In the case of using a ball mill or bead mill, for example, it is preferable to control the material, particle size, and grinding time of the balls or beads to be used in order to obtain the desired particle size of the ferrite pulverized product. Specifically, in order to reduce the particle size of the slurry of calcined ferrite, balls having a high specific gravity may be used or the pulverization time may be lengthened. Further, in order to widen the particle size distribution of the calcined ferrite, balls or beads having a high specific gravity should be used and the pulverization time should be shortened. Also, by mixing a plurality of calcined ferrite particles having different particle sizes, calcined ferrite particles having a wide particle size distribution can be obtained.
When using a ball mill or a bead mill, a wet method is more preferable than a dry method because the pulverized product does not rise up in the mill and the pulverization efficiency increases.

<Step 4 (granulation step)>
Water, a binder resin, and, if necessary, a pore adjusting agent are added to the pulverized calcined ferrite. Examples of pore adjusting agents include foaming agents and fine resin particles.
Examples of foaming agents include sodium hydrogen carbonate, potassium hydrogen carbonate, lithium hydrogen carbonate, ammonium hydrogen carbonate, sodium carbonate, potassium carbonate, lithium carbonate, and ammonium carbonate.
Examples of fine resin particles include polyester, polystyrene, styrene-vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, styrene-acrylic acid ester copolymer, styrene-methacrylic acid ester copolymer, styrene-α-chloromethacryl Styrene copolymers such as methyl acid copolymer, styrene-acrylonitrile copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-acrylonitrile-indene copolymer Combined; polyvinyl chloride, phenolic resin, modified phenolic resin, maleic resin, acrylic resin, methacrylic resin, polyvinyl acetate, silicone resin; aliphatic polyhydric alcohol, aliphatic dicarboxylic acid, aromatic dicarboxylic acid, aromatic dialcohols and polyester resins having monomers selected from diphenols as structural units; polyurethanes, polyamides, polyvinyl butyral, terpene resins, coumarone-indene resins, petroleum resins, hybrid resins having a polyester portion and a vinyl polymer portion, etc. fine particles.
Examples of the binder resin include polyvinyl alcohol.
In step 3, when wet pulverization is carried out, it is preferable to add a binder resin and, if necessary, a pore adjusting agent, considering the water contained in the ferrite slurry.
The obtained ferrite slurry is dried and granulated using a spray dryer in a heated atmosphere of 100° C. or more and 200° C. or less to obtain a granulated product. Spray dryers include, for example, spray dryers.

<Step 5 (main firing step)>
The granulated product is fired in a temperature range of 800° C. or higher and 1400° C. or lower for 1 hour or longer and 24 hours or shorter.
By raising the sintering temperature and lengthening the sintering time, the sintering of the porous magnetic particles proceeds, and as a result, the pore diameter becomes smaller and the number of pores decreases.

<Step 6 (sorting step)>
After pulverizing the particles obtained by firing as described above, coarse particles and fine particles may be removed by classification or sieving with a sieve, if necessary.
The volume distribution-based 50% particle diameter (D50) of the porous magnetic particles is preferably 20 μm or more and 80 μm or less from the viewpoint of suppressing carrier adhesion to images and suppressing rough images.

<Step 7 (filling step)>
Porous shaped magnetic particles may have low physical strength depending on the internal pore volume. From the viewpoint of increasing the physical strength as a magnetic carrier, it is preferable to fill at least part of the pores of the porous magnetic particles with a resin. The amount of the resin with which the porous magnetic particles are filled is preferably 2 parts by mass or more and 15 parts by mass or less with respect to 100 parts by mass of the porous magnetic particles. Only a part of the pores may be filled with the resin, or only the pores near the surface of the porous magnetic particles may be filled with the resin, and the pores may remain inside. It may be completely filled with resin. However, it is preferable that the resin content of each magnetic core filled with resin has little variation.

As a method for filling the pores of the porous magnetic particles with the resin, for example, the porous magnetic particles are impregnated with a resin solution by a coating method such as a dipping method, a spray method, a brush coating method, or a fluidized bed. and then volatilize the solvent. When filling with a thermosetting resin, after evaporating the solvent, the temperature is raised to the temperature at which the resin used is cured to cause a curing reaction.
Moreover, as a method of filling the pores of the porous magnetic particles with the resin, a method of diluting the resin with a solvent and adding this to the pores of the porous magnetic particles can be used. Any solvent can be used as long as it can dissolve the resin.
When using a resin soluble in an organic solvent, examples of the organic solvent include toluene, xylene, cellosolve butyl acetate, methyl ethyl ketone, methyl isobutyl ketone, and methanol. Moreover, when using a water-soluble resin or an emulsion type resin, water can be used as a solvent.

The resin solid content in the resin solution is preferably 1% by mass or more and 50% by mass or less, more preferably 1% by mass or more and 30% by mass or less. When the resin solid content is 50% by mass or less, the viscosity of the resin solution does not become too high, and the pores of the porous magnetic particles are easily permeated with the resin solution. Further, when the amount of the resin solid content is 1% by mass or more, the decrease in adhesion of the resin to the porous magnetic particles due to the small amount of the resin can be suppressed.

Examples of the resin that fills the pores of the porous magnetic particles include thermoplastic resins and thermosetting resins. The resin that fills the pores preferably has a high affinity for the porous magnetic particles. At the time of filling with resin, the surfaces of the porous magnetic particles can also be covered with resin at the same time.
As the resin to be filled in the porous magnetic particles, the resins mentioned above as the resin to be contained in the pores of the porous magnetic particles can be used.

(Method for producing magnetic carrier particles)
The magnetic carrier used in the present invention is obtained by coating the surface of a magnetic core with a resin to form a resin coating layer. The method of coating the surface of the magnetic core is not particularly limited, and any known method can be used. For example, there is a so-called immersion method in which a magnetic core and a coating resin solution are stirred while the solvent is volatilized to coat the magnetic core surface with the coating resin. Specific examples thereof include a universal mixing stirrer (manufactured by Fuji Paudal Co., Ltd.), Nauta Mixer (manufactured by Hosokawa Micron Co., Ltd.), and the like. There is also a method of spraying a coating resin solution from a spray nozzle while forming a fluidized bed to coat the surface of the magnetic core with the coating resin. Specific examples include Spiracoater (manufactured by Okada Seiko) and Spiraflow (manufactured by Freund Corporation). There is also a method in which the magnetic core is coated with the coating resin in the form of particles in a dry manner. Specifically, processing methods using devices such as Hybridizer (manufactured by Nara Machinery Works), Mechanofusion (manufactured by Hosokawa Micron), Hiflex Gral (manufactured by Fukae Powtech), Theta Composer (manufactured by Tokuju Kosakusho), etc. can be mentioned.

<Toner manufacturing method>
A method for producing toner particles is not particularly limited, but a pulverization method is preferred.

The procedure for manufacturing toner by the pulverization method will be described below.
In the raw material mixing step, predetermined amounts of other components such as a binder resin, a release agent, a colorant, a crystalline polyester, and, if necessary, a charge control agent are weighed and blended as materials constituting the toner particles. , to mix. Examples of the mixing device include a double-con mixer, a V-type mixer, a drum-type mixer, a super mixer, a Henschel mixer, a Nauta mixer, and a Mechanohybrid (manufactured by Nippon Coke Kogyo Co., Ltd.).
Next, the mixed materials are melt-kneaded to disperse wax and the like in the binder resin. In the melt-kneading process, a batch type kneader such as a pressure kneader or a Banbury mixer, or a continuous kneader can be used, and single-screw or twin-screw extruders are the mainstream because of their superiority in continuous production. ing. For example, KTK type twin-screw extruder (manufactured by Kobe Steel, Ltd.), TEM type twin-screw extruder (manufactured by Toshiba Machine Co., Ltd.), PCM kneader (manufactured by Ikegai Iron Works), twin-screw extruder (manufactured by K.C.K. ), Co-Kneader (manufactured by Buss Co., Ltd.), Kneedex (manufactured by Nippon Coke Industry Co., Ltd.), and the like. Furthermore, the resin composition obtained by melt-kneading may be rolled with two rolls or the like and cooled with water or the like in the cooling step.
The cooled resin composition is then pulverized to a desired particle size in a pulverization step. In the pulverization step, for example, after coarse pulverization with a pulverizer such as a crusher, hammer mill, or feather mill, further, for example, Kryptron System (manufactured by Kawasaki Heavy Industries, Ltd.), Super Rotor (manufactured by Nisshin Engineering Co., Ltd.), Turbo Mill (manufactured by Turbo Kogyo Co., Ltd.) or a fine pulverizer using an air jet method.
After that, classification such as inertial classification Elbow Jet (manufactured by Nittetsu Mining Co., Ltd.), centrifugal force classification system Turboplex (manufactured by Hosokawa Micron Corporation), TSP Separator (manufactured by Hosokawa Micron Corporation), and Faculty (manufactured by Hosokawa Micron Corporation) as necessary. Classify using a sieving machine or sieving machine.

Thereafter, the toner particles are surface-treated by heating to increase the circularity of the toner. For example, a surface treatment apparatus shown in FIG. 4 can be used to perform surface treatment with hot air.
The toner particles quantitatively supplied by the raw material constant supply means 21 are guided to the introduction pipe 23 installed on the center axis of the processing chamber 26 by the compressed gas adjusted by the compressed gas adjustment means 22 . The toner particles that have passed through the introduction pipe 23 are uniformly dispersed by a conical protruding member 24 provided in the center of the introduction pipe 23, and are led to the supply pipes 25 extending radially in eight directions to supply powder particles. A port 34 leads to the processing chamber 26 where the heat treatment takes place.
At this time, the flow of the toner particles supplied to the processing chamber 26 is regulated by the regulating means 29 provided in the processing chamber 26 for regulating the flow of the toner particles. Therefore, the toner particles supplied to the processing chamber 26 are heat-treated while swirling in the processing chamber 26 .
Hot air for heat-treating the supplied toner particles is supplied from a hot air inlet 31 of the hot air supply means 27, and is spirally swirled in the processing chamber 26 by a swirling member 33 for swirling the hot air. be introduced. As for the configuration, the swirling member 33 for swirling the hot air has a plurality of blades, and the swirling of the hot air can be controlled by the number and angle of the blades. At this time, the substantially conical distribution member 32 can reduce the unevenness of the swirling hot air. The hot air supplied into the processing chamber 26 preferably has a temperature of 100° C. to 300° C. at the outlet of the hot air supply means 27 . If the temperature at the outlet of the hot air supply means 27 is within the above range, the toner particles can be uniformly sphericalized while preventing the toner particles from being fused or coalesced due to overheating of the toner particles. It becomes possible.
Further, the thermally treated toner particles are cooled by cold air supplied from the cold air supply means 28 (cool air supply means 28-1, cold air supply means 28-2, and cold air supply means 28-3), and are supplied from the cold air supply means 28. The temperature is preferably -20°C to 30°C. If the temperature of the cold air is within the above range, the heat-treated toner particles can be efficiently cooled, and fusion and coalescence of the heat-treated toner particles can be prevented without impeding the uniform spheroidizing treatment of the mixture. be able to. The absolute water content of the cool air is preferably 0.5 g/m ³ or more and 15.0 g/m ³ or less.

The cooled, heat-treated toner particles are then collected by collection means 30 at the lower end of processing chamber 26 . A blower (not shown) is provided at the end of the collecting means 30, and the particles are suction-conveyed by the blower.
The powder particle supply port 34 is provided so that the swirling direction of the supplied toner particles and the swirling direction of the hot air are the same. It is provided on the outer periphery of the processing chamber 26 so as to maintain the turning direction. Furthermore, the cold air supplied from the cold air supply means 28 is configured to be supplied horizontally and tangentially from the outer peripheral portion of the apparatus to the inner peripheral surface of the processing chamber 26 . The swirling direction of the toner supplied from the powder particle supply port 34, the swirling direction of the cold air supplied from the cold air supplying means 28, and the swirling direction of the hot air supplied from the hot air supplying means 27 are all the same direction. Therefore, no turbulent flow occurs in the processing chamber 26, the swirling flow in the apparatus is strengthened, a strong centrifugal force is applied to the toner particles, and the dispersibility of the toner particles is further improved. uniform toner particles can be obtained.
When the average circularity of the toner is 0.960 or more and 0.980 or less, the non-electrostatic adhesion force can be kept low, which is preferable from the viewpoint of fog resistance.

After that, it is divided into two parts, one on the fine side and the other on the coarse side. For example, it is divided into two using an inertial classification type elbow jet (manufactured by Nittetsu Mining Co., Ltd.). A desired amount of fine silica particles A is externally added to the surface of each of the bisected heat-treated toner particles. As a method for external addition treatment, a mixing device such as a double-con mixer, V-type mixer, drum-type mixer, super mixer, Henschel mixer, Nauta mixer, Mechanohybrid (manufactured by Nippon Coke Industry Co., Ltd.), Nobilta (manufactured by Hosokawa Micron Co., Ltd.), etc. is used as an external addition device to stir and mix. At that time, if necessary, an external additive other than silica fine particles, such as a fluidizing agent, may be externally added.
Methods for measuring various physical properties of toners and materials are described below.

The present invention will be described below with reference to Examples and the like. However, the description of the examples and the like does not limit the technical scope of the present invention.

<Manufacturing Example of Magnetic Core 1>
Step 1 (weighing/mixing step)
_{Fe2O3 68.3} % by mass
_MnCO3 28.5% by mass
Mg(OH) ₂ 2.0% by mass
_SrCO3 1.2% by mass
The above materials were weighed, 20 parts by mass of water was added to 80 parts by mass of the materials, and then zirconia with a diameter (φ) of 10 mm was wet mixed for 3 hours in a ball mill to prepare a slurry. The solid content concentration of the slurry was 80% by mass.

Step 2 (temporary firing step)
After drying the mixed slurry with a spray dryer (manufactured by Okawara Kakoki Co., Ltd.), it is calcined at a temperature of 1050 ° C. for 3.0 hours in a batch type electric furnace under a nitrogen atmosphere (oxygen concentration 1.0% by volume), and calcined. A ferrite was produced.

Step 3 (pulverization step)
After the calcined ferrite was coarsely pulverized to about 0.5 mm by a crusher, water was added to prepare a coarsely pulverized slurry. The solid content concentration of the coarsely pulverized slurry was set to 70% by mass. The mixture was pulverized for 3 hours in a wet ball mill using ⅛ inch stainless steel beads to obtain a pulverized slurry. Further, this pulverized slurry was pulverized for 4 hours in a wet bead mill using zirconia with a diameter of 1 mm to obtain a calcined ferrite slurry with a volume-based 50% particle diameter (D50) of 1.3 μm.

Step 4 (granulation step)
After adding 1.0 parts by mass of ammonium polycarboxylate as a dispersant and 1.5 parts by mass of polyvinyl alcohol as a binder to 100 parts by mass of the calcined ferrite slurry, the mixture was dried with a spray dryer (manufactured by Okawara Kakoki Co., Ltd.). Granulated into spherical particles and dried. After adjusting the particle size of the obtained granules, they were heated at 700° C. for 2 hours using a rotary electric furnace to remove organic substances such as dispersants and binders.

Step 5 (Baking step)
In a nitrogen atmosphere (oxygen concentration 1.0% by volume), the time from room temperature to the firing temperature (1100° C.) was 2 hours, and the temperature was maintained at 1100° C. for 4 hours, followed by firing in an electric tunnel furnace. After that, the temperature was lowered to 60° C. over 8 hours, the nitrogen atmosphere was returned to the air, and the temperature was 40° C. or less and taken out.

Step 6 (sorting step)
After pulverizing the aggregated particles, sieving with a sieve with an opening of 150 μm to remove coarse particles, air classification to remove fine powder, and magnetic separation to remove low magnetic force components to form a porous magnetic core 1 got

<Production example of fine particles 1>
100 parts by mass of carbon black (trade name: #4400, manufactured by Tokai Carbon Co., Ltd.) was placed in a 500 ml ground-up round-bottomed flask, and 200 parts by mass of an aqueous nitric acid solution (50% by mass) was added. A condenser with a ball was connected to the flask, the round-bottomed flask was placed on the mantle heater, and after starting reflux, oxidation treatment was performed for 30 minutes. After completion of the reflux, the carbon black was separated by filtration and dried in a dryer at 125° C. to obtain fine particles 1 having a volume average primary particle size of 33 nm. Table 1 shows the physical property values of the fine particles 1 obtained. In Table 1, "CB" represents carbon black.

<Production Examples of Fine Particles 2 to 6 and 8 to 13>
Fine particles 2 to 6 and 8 to 13 were obtained in the same manner as in the production example of fine particle 1 except that the fine particles and the type and amount of the treating agent of fine particles 1 were changed. Table 1 shows the physical properties of fine particles 2 to 6 and 8 to 13 obtained.

<Production example of fine particles 7>
100 parts by mass of carbon black (#4400, manufactured by Tokai Carbon Co., Ltd.) was placed in a 500 ml ground-up round-bottomed flask, and 200 parts by mass of an aqueous nitric acid solution (50% by mass) was added. A condenser with a ball was connected to the flask, the round-bottomed flask was placed on the mantle heater, and after starting reflux, oxidation treatment was performed for 30 minutes. Next, 200 parts by mass of methanol was added. After cooling with ice, 30 parts by mass of calcium carbonate was added, the temperature was raised to 25° C., and the mixture was stirred for 2 hours. 100 parts by mass of a saturated ammonium chloride aqueous solution was added to the stirred material to stop the reaction, washed with water, air-dried and dried under reduced pressure to obtain fine particles 7 .

<Production Example of Silicone Modified Resin Solution 1>
95.2% by mass of the monomer corresponding to the unit represented by formula (7) shown in Table 2 and 4.8% by mass of the monomer corresponding to the unit represented by formula (8) shown in Table 2 were refluxed. Added to a four-necked flask equipped with a condenser, thermometer, nitrogen suction tube, and ground-type stirrer.
Further, 100 parts by mass of toluene, 100 parts by mass of methyl ethyl ketone, and 2.0 parts by mass of azobisisovaleronitrile were added. The obtained mixture was kept under stirring at 70° C. for 10 hours under a nitrogen stream, and after completion of the polymerization reaction, washing was repeated to obtain a silicone-modified resin solution 1 having a solid content of 35% by mass. The l+m value of this solution calculated by gel permeation chromatography (GPC) was 70.

<Production Examples of Silicone Modified Resin Solutions 2 to 7>
In the production example of the silicone-modified resin solution 1, the mass of the unit represented by formula (7) and the mass of the unit represented by formula (8), the type of functional group, and the mass b of the unit represented by formula (8) Silicone-modified resin solutions 2 to 7 were obtained in the same manner, except that the mass a (a/b) of the unit represented by formula (7) was changed to that shown in Table 2. As the unit represented by formula (8), the unit represented by formula (8-1) below was used.

<Production example of macromonomer>
・Methacrylic acid chloride 1.7% by mass
・Polymethyl methacrylate having a hydroxyl group at one end (Mw; about 5000)
98.3% by mass
The above materials were added to a four-necked flask equipped with a reflux condenser, thermometer, nitrogen suction tube, and ground-type stirrer. Further, 100 parts by mass of THF and 1.0 parts by mass of 4-tert-butylcatechol were added to the four-necked flask. The resulting mixture was heated under reflux for 5 hours under nitrogen stream, and after the reaction was completed, the mixture was washed with sodium hydrogencarbonate to obtain a macromonomer solution.

<Method for producing unmodified (meth)acrylic resin>
・Cyclohexyl methacrylate 74.5% by mass
・Methyl methacrylate 0.5% by mass
・ 25% by mass of the methacrylic acid macromonomer produced above
The above materials were added to a four-necked flask equipped with a reflux condenser, thermometer, nitrogen suction tube, and ground-type stirrer. Further, 100 parts by mass of toluene, 100 parts by mass of methyl ethyl ketone, and 2.0 parts by mass of azobisisovaleronitrile were added to the four-necked flask. The obtained mixture was kept at 70° C. for 10 hours under a nitrogen stream, and after completion of the polymerization reaction, washing was repeated to obtain a solution of an unmodified (meth)acrylic resin having a solid content of 35% by mass.

<Manufacturing Example of Magnetic Carrier 1>
(Resin coating process)
Using a magnetic core 1, a planetary motion mixer (trade name: Nauta Mixer VN type, manufactured by Hosokawa Micron Corporation) maintained at a temperature of 60° C. under reduced pressure (1.5 kPa), a silicone-modified resin solution 1 and fine particles 1. and an unmodified (meth)acrylic resin were added to 100 parts by mass of the magnetic core 1 so that the solid content of the resin component was 2.0 parts by mass. As for the method of charging the resin solution, 1/3 of the amount of the resin solution was first charged, and the solvent was removed for 20 minutes so that the surface of the magnetic core 1 was coated with the resin. Next, 1/3 of the amount of the resin solution was added, and the solvent removal and coating operations were performed for 20 minutes. After that, 1/3 of the amount of the resin solution was added, and solvent removal and coating operations were performed for 20 minutes.
The magnetic core 1 coated with the resin composition was placed in a rotatable mixing vessel and transferred to a mixer having spiral blades (trade name: Drum Mixer UD-AT, manufactured by Sugiyama Heavy Industries, Ltd.). The mixture was heat-treated at a temperature of 120° C. for 2 hours under a nitrogen atmosphere while stirring by rotating the mixing vessel 10 times per minute. The obtained magnetic carrier particles were subjected to magnetic separation to separate low magnetic particles, passed through a sieve having an opening of 150 μm, and then classified by an air classifier. Magnetic carrier particles 1 having a 50% particle size (D50) of 39.1 μm based on volume distribution were obtained. Table 3 shows the surface analysis results of the obtained Magnetic Carrier Particle 1 (functional group concentration of the magnetic carrier particle and concentration of Si atoms on the surface of the magnetic carrier particle). These magnetic carrier particles 1 were designated as magnetic carrier 1 .

<Method for producing magnetic carriers 2 to 25>
Magnetic Carriers 2 to 25 were obtained in the same manner as in the method for producing Magnetic Carrier 1, except that the silicone-modified resin solution and fine particles were changed to those shown in Table 3. Physical properties are shown in Table 3.

<Production Example of Toner 1>
・Polyester resin 100 parts by mass Tg: 58°C
Acid value: 15mgKOH/g
Hydroxyl value: 15mgKOH/g
Molecular weight: Mp5800, Mn3350, Mw94000
・C. I. Pigment Blue 15:3 4.5 parts by mass 1,4-di-t-butylsalicylic acid aluminum compound 0.5 parts by mass Normal paraffin wax 6.0 parts Melting point: 78°C
After mixing the above materials well with a Henschel mixer (trade name: FM-75J type, manufactured by Nippon Coke Kogyo Co., Ltd.), a twin-screw kneader (trade name: PCM-30 type, Co., Ltd.) set at a temperature of 130 ° C. The mixture was kneaded at a feed amount of 10 kg/h (the temperature of the kneaded product at the time of discharge was about 150° C.) using Ikegai (former Ikegai Iron & Steel Co., Ltd.). The resulting kneaded product was cooled, coarsely pulverized with a hammer mill, and then pulverized with a mechanical pulverizer (trade name: T-250, manufactured by Freund Turbo Co., Ltd. (former Turbo Kogyo Co., Ltd.)) to 15 kg / It was pulverized with a feed amount of h. Then, particles having a weight average particle size of 5.5 μm, containing 55.6% by number of particles having a particle size of 4.0 μm or less, and containing 0.8% by volume of particles having a particle size of 10.0 μm or more are obtained. rice field. In addition, "Tg" represents a glass transition temperature, "Mp" represents a peak molecular weight, "Mn" represents a number average molecular weight, and "Mw" represents a weight average molecular weight.
The obtained particles were classified by a rotary classifier (trade name: TTSP100, manufactured by Hosokawa Micron Corporation) to remove fine powder and coarse powder. Toner particles 1 having a weight average particle diameter of 6.3 μm were obtained.
Strontium titanate particles (1.0 part) and hydrophobic silica fine particles (1.0 part) were added to the obtained toner particles 1 (100.0 parts). The obtained additive was mixed with a Henschel mixer (trade name: FM75J type, manufactured by Mitsui Miike Kakoki Co., Ltd.) at a rotation speed of 30 s ⁻¹ for a rotation time of 5 minutes, and passed through an ultrasonic vibrating sieve with a mesh size of 54 μm. , Toner 1 was obtained. The weight average particle size (D4) of Toner 1 was 6.5 μm, and the average circularity of the toner was 0.96.

<Production Examples of Two-Component Developers 1 to 25>
Toner 1 and magnetic carriers 1 to 25 in the combinations shown in Table 4 were mixed with a V-type mixer (trade name: V-10 type: manufactured by Tokuju Seisakusho Co., Ltd.) so that the toner concentration was 8.0% by mass. Two-component developers 1 to 25 were obtained by mixing at 5 s ⁻¹ and a rotation time of 5 min.

<Manufacturing Examples of Replenishing Developers 1 to 25>
90 parts by mass of toner 1 is added to 10 parts by mass of magnetic carriers 1 to 25, and a V-type mixer (trade name: V-10 type: Tokuju Seisakusho Co., Ltd.) is placed in an environment of normal temperature and humidity of 23° C./50% RH. ) for 5 minutes to obtain replenishing developers 1-25.

<Example 1>
Using two-component developer 1 and replenishment developer 1, the following evaluations were performed.
As an image forming apparatus, a modified color copier (trade name: imageRUNNER ADVANCE C5560, manufactured by Canon Inc.) was used.
Two-component developer 1 was placed in a cyan developing device, a replenishing developer container containing replenishing developer 1 was set, an image was formed, and various evaluations were performed before and after the durability test.
As a durability test, a chart of FFH output with an image ratio of 40% was used under a printing environment of temperature 30° C./humidity 80 RH% (hereinafter “H/H”). FFH is a value representing 256 gradations in hexadecimal, 00h is the 1st gradation (white background portion) of 256 gradations, and FFH is the 256th gradation (solid portion) of 256 gradations. .

The number of image output sheets was changed according to each evaluation item.
conditions:
Paper: Laser beam printer paper CS-814 (81.4 g/m ² ) (Canon Marketing Japan Inc.)
The modified points of the color copier are as follows.
- The image forming speed has been modified so that it can output 80 (pages/min) in A4 size and full color.
In addition, a color copier,
・I made it possible to adjust the development contrast at any value, and modified it so that the automatic correction by the main unit does not work. The peak-to-peak voltage (Vpp) of the alternating electric field was modified so that the frequency was 2.0 kHz and Vpp was changed from 0.7 kV to 1.8 kV in increments of 0.1 kV. Modified so that the image can be output in cyan monochrome.
- Modified so that only the cyan developer can be developed in a single color.
・Idle rotation of the developing unit The circumferential speed of the sleeve of the developing unit of the main unit was freely changed, and it was modified so that it could idle.
Each evaluation item is shown below.

[Evaluation 1. Fog evaluation]
After evaluation of the initial durability and durability image output (A4 landscape, 40% printing ratio, 50,000 sheets) under a high-temperature and high-humidity environment (30° C., 80% RH), a solid white image on the entire surface of A4 was output. The fogging was evaluated by measuring the whiteness of the white background portion with a reflectometer (manufactured by Tokyo Denshoku Co., Ltd.), calculating the fog concentration (%) from the difference in whiteness before and after the transfer, and evaluating it according to the following criteria. When the evaluation was A to C, it was judged that the effect of the present invention was obtained.
A: Less than 1.0% B: 1.0% or more and less than 1.5% C: 1.5% or more and less than 2.0% D: 2.0% or more Table 4 shows the evaluation results.

[Evaluation 2. Halftone developability evaluation]
After evaluating the initial endurance and endurance image output (A4 landscape, 40% print ratio, 50,000 sheets) in a high temperature and high humidity environment (30 ° C, 80% RH), halftone image (30H) 1 sheet of A4 After printing, the area of 1000 dots was measured using a digital microscope VHX-500 (lens wide range zoom lens VH-Z100 manufactured by Keyence Corporation). The number average (S) of the dot area and the standard deviation (σ) of the dot area were calculated, and the dot reproducibility index was calculated by the following formula. Roughness of the halftone image was evaluated by the dot reproducibility index (I).
Dot reproducibility index (I) = σ/S x 100

Roughness was evaluated according to the following criteria. When the evaluation was A to C, it was judged that the effect of the present invention was obtained.
A: I is less than 4.0 B: I is 4.0 or more and less than 5.0 C: I is 5.0 or more and less than 7.0 D: I is 7.0 or more Table 4 shows the evaluation results.

[Evaluation 3. Gradation change evaluation before and after durability]
After evaluating the initial durability and durability image output (A4 landscape, 40% print ratio, 50,000 sheets) in a high temperature and high humidity environment (30°C, 80% RH), the initial stage and immediately after 50,000 sheets have been passed. Checked for inconsistency. Images were judged by measuring the respective image densities with an X-Rite color reflection densitometer (X-Rite 404A).
Pattern 1: 0.10 to 0.13 Pattern 2: 0.25 to 0.28 Pattern 3: 0.45 to 0.48 Pattern 4: 0.65 to 0.68 Pattern 5: 0.85 Pattern 6: 1.05 to 1.08 Pattern 7: 1.25 to 1.28 Pattern 8: 1.45 to 1.48 , was evaluated according to the following criteria. When the evaluation was A to C, it was judged that the effect of the present invention was obtained.
A: All pattern images satisfy the above density range.
B: 1 to 2 pattern images are out of the above density range.
C: 3 to 4 Two pattern images are out of the above density range.
D: Five or more pattern images are out of the above density range.
Table 4 shows the evaluation results.

<Examples 2 to 22 and Comparative Examples 1 to 3>
Examples 2 to 22 and Comparative Examples 1 to 3 were evaluated in the same manner as in Example 1, except that the two-component developer used in the evaluation was changed to the two-component developer shown in Table 4. Table 4 shows the evaluation results.

1 Electrostatic latent image carrier 2 Charger 3 Exposure device 4 Developing device 5 Developing container 6 Developer carrier 7 Magnet 8 Regulation member 9 Intermediate transfer member 10 Intermediate transfer charger 11 Transfer charger 12 Recording medium (transfer material)
13 Fixing device 14 Intermediate transfer body cleaner 15 Cleaner 16 Pre-exposure 21 Raw material constant supply means 22 Compressed gas adjustment means 23 Introduction pipe 24 Conical protruding member 25 Supply pipe 26 Processing chamber 27 Hot air supply means 28 Cold air supply means 29 Regulation means 30 recovery means 31 hot air inlet 32 distribution member 33 swirl member 34 powder particle supply port 101 replenishment developer storage container 102 developer 103 cleaning device 104 developer recovery container 105 toner concentration detection sensor 106 discharge device

Claims (8)

A magnetic carrier comprising a magnetic core and magnetic carrier particles having a coating resin layer coating the surface of the magnetic core,
The coating resin layer contains a silicone-modified resin and fine particles,
The fine particles have a functional group represented by formula (1) or a functional group represented by formula (2) on the surface of the fine particles at a functional group concentration of 20% or more,
The magnetic carrier particles have the functional group represented by the formula (1) or the functional group represented by the formula (2) on the surface of the magnetic carrier particles at a functional group concentration of 0.05% or less. death,
A magnetic carrier, wherein the functional group concentration of the fine particles and the functional group concentration of the magnetic carrier particles are determined by Equations 1 and 2, respectively.

(In Formula (1) and Formula (2), R1 is a hydrogen atom or a methyl group.)
Functional group concentration of fine particles = (fluorine value by X-ray photoelectron spectroscopy measurement / g) ÷ (specific surface area of fine particles / g) (calculation formula 1)
Functional group concentration of magnetic carrier particles=(fluorine value/g by X-ray photoelectron spectroscopy)/(specific surface area of magnetic carrier particles/g) (calculation formula 2) The silicone-modified resin is
(i) one or more selected from units represented by one or more of the following formulas (3) to (6);
(ii) one selected from units represented by the following formulas (3′) to (5′);
contains
(iii) the units represented by formulas (3′) to (5′) are connected to the units represented by formulas (3) to (6) so as to share one oxygen atom; ,
The total content of the units represented by formulas (3) to (6) and the units represented by formulas (3′) to (5′) in the silicone-modified resin is 3% by mass or more and 50% by mass. The magnetic carrier according to claim 1, wherein:

(In formulas (3) to (6) and formulas (3′) to (5′), R2 to R7 are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a phenyl group, or a carbon atom is an alkenyl group with a number of 2 to 4, and —O _1/2 represents that O is shared with adjacent Si atoms,
In formulas (3') to (5'), ** is a site that bonds to an alkylene group or a site that bonds to an oxygen atom that is bonded to a carbon atom. ) The silicone-modified resin is mainly composed of a unit represented by the following formula (7) and a unit represented by the formula (8), the mass of the unit represented by the formula (7) is a, and the mass of the unit represented by the formula (8) is represented by the formula (8). The ratio a/b of the mass of the unit represented by the formula (5) to the mass of the unit represented by the formula (6) is 1.00 or more and 30.0 or less 3. The magnetic carrier according to item 2.

(In formula (7),
R8 is a hydrogen atom or a methyl group,
R9 is a hydrocarbon group having 1 to 6 carbon atoms, an alkyl group having 2 to 4 carbon atoms having a hydroxyl group as a substituent, or an alkyl group having 1 to 4 carbon atoms having a carboxy group as a substituent;
l is an integer of 1 or more. )

(In formula (8),
R10 is a hydrogen atom or a methyl group,
R11 is a hydrogen atom or a hydrocarbon group having 1 to 6 carbon atoms,
R12 is a single bond or alkylene having 1 to 5 carbon atoms,
m is an integer of 1 or more,
* is a site to which a siloxane moiety is bonded, and is connected to ** of any unit represented by the following formulas (3′) to (5′),

In the units represented by the formulas (3′) to (5′), any unit represented by the following formulas (3) to (6) has one are connected one or more times,

The terminal of the siloxane moiety is a unit of the above formula (6),
R2 to R7 in formulas (3′) to (5′) and formulas (3) to (6) are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or a phenyl group, and —O _1/2 represents that O is shared with adjacent Si atoms,
The number of silicon atoms in the siloxane moiety is 2-150. ) 4. The magnetic carrier according to claim 1, wherein the concentration of Si atoms on the surface of the magnetic carrier particles is 1.0 atomic % or more and 8.0 atomic % or less as measured by X-ray photoelectron spectroscopy. The magnetic carrier according to any one of claims 1 to 4, wherein the primary particles of the fine particles have a volume average particle size of 10 nm or more and 100 nm or less. The magnetic carrier according to any one of claims 1 to 5, wherein the coating resin layer contains a silicone-modified (meth)acrylic resin and a (meth)acrylic resin. A two-component developer containing the magnetic carrier according to any one of claims 1 to 6 and a toner. A replenishing developer containing the magnetic carrier according to any one of claims 1 to 6 and a toner.

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