JP7669161B2 - Magnetic carrier, two-component developer, and replenishment developer - Google Patents

Description

This disclosure relates to magnetic carriers, two-component developers, and replenishment developers.

Two-component developers are widely used in electrophotographic image forming devices, in which a magnetic carrier is mixed with a toner, triboelectrically charged, and an appropriate amount of positive or negative charge is imparted to the toner, which is then used as the driving force for development. From the perspective of obtaining high-quality images, the magnetic carrier used in two-component developers is required to be resistant to excessive leakage of carrier charge in order to sufficiently charge the toner.

Magnetic material-dispersed resin carriers, which have a relatively high carrier resistivity, are known as magnetic carriers that are less likely to leak carrier charge. For example, Patent Document 1 discloses that by using a magnetic material-dispersed resin carrier with controlled magnetization strength and resistivity, carrier charge leakage is less likely to occur and good images can be formed.

JP 2003-295523 A WO01/083566 JP 2017-31258 A

One aspect of the present disclosure is to provide a magnetic carrier that has excellent carrier strength and is less likely to cause image fog and toner scattering even under high stress.

Another aspect of the present disclosure is directed to providing a two-component developer having the magnetic carrier according to the present disclosure.

Another aspect of the present disclosure is directed to providing a refill developer having the magnetic carrier according to the present disclosure.

According to one aspect of the present disclosure, there is provided a magnetic carrier comprising a magnetic material-dispersed resin carrier core including a magnetic material and a dispersion resin, and a coating resin that coats the surface of the magnetic material-dispersed resin carrier core,
The magnetic carrier contains polyrotaxane,
The polyrotaxane is
(i) a plurality of cyclic molecules;
(ii) a chain molecule that is included in the ring of the cyclic molecule in a skewered manner;
(iii) The chain molecule has two or more blocking groups that prevent the cyclic molecule from being detached from the chain molecule.

According to another aspect of the present disclosure, there is provided a two-component developer containing a toner and a magnetic carrier,
The magnetic carrier is a magnetic carrier according to the present disclosure.

According to another aspect of the present disclosure, there is provided a replenishment developer containing a toner and a magnetic carrier, comprising:
The magnetic carrier is a magnetic carrier according to the present disclosure.

According to one aspect of the present disclosure, it is possible to provide a magnetic carrier that has excellent carrier strength and is less likely to cause image fog and toner scattering even under high stress.

According to another aspect of the present disclosure, a two-component developer having the magnetic carrier according to the present disclosure can be provided.

According to another aspect of the present disclosure, a refill developer having the magnetic carrier according to the present disclosure can be provided.

In this disclosure, the expressions "XX or more and XX or less" and "XX to XX" that express a numerical range mean a numerical range including the lower and upper limits, which are the endpoints, unless otherwise specified. In addition, the magnetic material-dispersed resin carrier core is also referred to simply as the carrier core.

<Background to the invention>
A magnetic material-dispersed resin carrier is a carrier in which magnetic particles are bound with a binder resin, and is therefore known to have a higher specific resistance and less leakage of electric charge than iron powder carriers, ferrite carriers, etc.

However, the inventors have discovered that when a magnetic material-dispersed resin carrier is used to output images at high speed, the carrier may be more susceptible to damage. The inventors speculate that this is because when an impact is applied to the magnetic material-dispersed resin carrier, stress is likely to concentrate at the interface between the magnetic particles and the binder resin.

The inventors also discovered that damage to the carrier exposes magnetic particles, which makes it easier for the carrier charge to leak and makes it difficult for the toner to be charged, which makes image fogging and toner scattering more likely to occur in the developing machine. From the perspective of obtaining high-quality images even when images are output at high speed, it is naturally necessary to prevent image fogging and toner scattering. Therefore, the inventors recognized the need to develop technology to improve the strength of magnetic material-dispersed resin carriers and to prevent carrier damage and the associated image fogging and toner scattering.

Based on the above considerations, the inventors have investigated various additives to obtain a magnetic material-dispersed resin carrier that has excellent carrier strength and is less likely to cause image fog and toner scattering. As a result of extensive investigations, they have found that incorporating polyrotaxane into a magnetic material-dispersed resin carrier is effective in realizing a carrier with the above-mentioned properties.

The inventors speculate that because the cyclic molecules of polyrotaxane can move along chain molecules, when an impact is applied to a magnetic material-dispersed resin carrier containing polyrotaxane, the cyclic molecules can move in response to the impact. As a result, the inventors speculate that the stress applied to the carrier is easily dispersed and the carrier is less likely to break, resulting in excellent carrier strength and less risk of image fogging and toner scattering.

<Polyrotaxane>
The polyrotaxane according to the present disclosure has (i) a plurality of cyclic molecules, and (ii) a chain molecule that is skewered and included in the rings of the cyclic molecules, and (iii) the chain molecule has two or more blocking groups that prevent the cyclic molecules from being detached from the chain molecule. In general, a molecular assembly in which a chain molecule penetrates the inside of the ring of a cyclic molecule and a bulky molecule is bonded to the end of the axis to bind the cyclic molecule on the chain molecule is called a rotaxane. In addition, a molecular assembly in which many cyclic molecules are connected on one chain molecule is called a polyrotaxane. The cyclic molecule is not bonded to the chain molecule and can rotate and move on the chain molecule.

The content of polyrotaxane is preferably 0.2% by mass or more and 30.0% by mass or less relative to the mass of the dispersion resin. This range is believed to facilitate sufficient dispersion of stress applied to the carrier, making it easier for the carrier strength to increase and less likely to cause image fogging or toner scattering. A more preferred range is 0.5% by mass or more and 25.0% by mass or less.

The polyrotaxane of the present disclosure can be produced by a method already known in the art, such as the method described in Patent Document 2 or Patent Document 3, or can be obtained and used as a commercially available product (product name: CELME Super Polymer, manufactured by ASM Corporation).

The location where the polyrotaxane is contained is not particularly limited, but it is preferable that it is contained in the carrier core, since it is believed that this makes it easier to disperse stress applied to the vicinity of the magnetic material. It is more preferable that it is contained in a dispersed state in the dispersion resin.

In the polyrotaxane of the present disclosure, the number of cyclic molecules threaded into one linear molecule (the amount of inclusion) is not particularly limited. The amount of inclusion can be controlled by the molar ratio of the linear molecule and the cyclic molecule used in producing the polyrotaxane.

<Cyclic molecules>
The cyclic molecules contained in the polyrotaxane are not particularly limited as long as they are capable of including chain molecules and have a ring structure through which the chain molecules can penetrate in a skewered manner.

Examples of the cyclic molecule of the present disclosure include cyclodextrins, crown ethers, benzocrowns, dibenzocrowns, dicyclohexanocrowns, and derivatives or modifications thereof. Among these, cyclodextrins are preferred because they are easy to include chain molecules. That is, the cyclic molecule is preferably a molecule having a cyclodextrin skeleton. More preferably, the cyclic molecule is a molecule having at least one cyclodextrin skeleton selected from the group consisting of an α-cyclodextrin skeleton, a β-cyclodextrin skeleton, and a γ-cyclodextrin skeleton. The cyclic molecule may be one type, or two or more types may be used in combination.

In this disclosure, a molecule having a cyclodextrin skeleton is considered to be a cyclodextrin compound or a molecule having a structure that is synthesized when a derivatization reaction is performed on a hydroxyl group of a cyclodextrin compound.

<Side chains attached to cyclodextrin>
It is preferable that the cyclic molecule of the polyrotaxane is a molecule having a cyclodextrin skeleton, and the molecule having the cyclodextrin skeleton has cyclodextrin and a side chain bonded to the cyclodextrin. Here, the side chain bonded to the cyclodextrin in the present disclosure is treated as a partial structure introduced when a derivatization reaction is performed on a hydroxy group of the cyclodextrin. The side chain may be a linear structure or a branched structure.

The above-mentioned side chains are believed to increase the affinity between the polyrotaxane and the resin component. As a result, the polyrotaxane is less likely to be present in a biased state, and is more likely to be contained in a uniformly dispersed state, which is preferable. In addition, it is preferable for the side chains to have a polymer structure, and it is more preferable for them to have a polyester structure or a vinyl polymer structure. Examples of polyester structures include a polymer structure in which a diol and a dicarboxylic acid are condensed, and a polycaprolactone structure. In addition, a vinyl polymer structure is a polymer structure in which a vinyl monomer is polymerized, and an example of such a structure is a styrene-methyl methacrylate polymer structure.

The weight-average molecular weight of the molecule having the above-mentioned side chain and cyclodextrin skeleton is preferably 1000 to 50000. It has been found that this range makes it easier to increase the carrier strength and makes it harder for image fogging and toner scattering to occur. The inventors believe that this is because not only does the movement of the cyclic molecules in the polyrotaxane disperse impacts, but the polyrotaxane and resin become entangled, and the self-repairing function of the polyrotaxane makes it easier for the resin to have excellent scratch resistance. The weight-average molecular weight is preferably 2500 or more, more preferably 30000 or less, more preferably 20000 or less, and even more preferably 10000 or less.

Molecules having a cyclodextrin skeleton that satisfy the above weight-average molecular weight can be produced by bonding a polymer structure to cyclodextrin. For example, they can be produced by introducing a polyester structure into the hydroxyl group of cyclodextrin. They can also be produced by a vinyl polymerization reaction between a cyclodextrin derivative that has a vinyl-polymerizable double bond and a vinyl monomer.

The molecular weight of the cyclic molecules can be measured by an analytical device such as GPC after isolating the cyclic molecules. In order to isolate the cyclic molecules, the terminal blocking groups of the polyrotaxane must be removed as a first step. For example, in the case of polyrotaxanes having terminal blocking groups bonded with amide groups or carbonyl groups, a method of heating under acid or base conditions to cause hydrolysis can be used. The cyclic molecules can then be isolated by conventional methods such as reprecipitation, filtration, centrifugation, and membrane separation.

<Chain molecules>
The chain molecule of the polyrotaxane is not particularly limited as long as it can pierce the cyclic molecule in a skewered manner, is included in the cyclic molecule, and allows the cyclic molecule to rotate, slide, or move freely. In addition, the chain molecule is preferably a linear molecule. In the present disclosure, a linear molecule is considered to be a molecule having no branch in the main chain of the molecule. In addition, the length of the linear chain is not particularly limited.

The chain molecule is preferably at least one selected from the group consisting of polyalkylenes, polyesters, polyethers, polyamides, and polyacrylics, and among these, polyethers are more preferable. That is, the chain molecule is preferably a molecule having a polyether chain. More preferably, it is a molecule having a polyalkylene glycol chain, and even more preferably, it is a molecule having a polyethylene glycol chain.

<Blocking group>
The chain molecule has two or more blocking groups at its terminals to prevent the cyclic molecules from being released. The blocking groups of the polyrotaxane can be used without any particular limitation as long as they have a structure that can prevent the cyclic molecules from being released. Examples of the blocking groups according to the present disclosure include bulky groups that physically prevent the cyclic molecules from being released, and ionic groups that electrically prevent the cyclic molecules from being released. Specific examples include dinitrophenyl groups, adamantyl groups, trityl groups, and pyrenyl groups. Specific examples include cyclodextrins and fluoresceins that are introduced as substituents at the terminals of the chain molecules. The blocking groups may also be derivatives or modified forms of the above.

<Bonded polyrotaxane>
The cyclic molecules of the two or more polyrotaxanes may be bonded to each other by forming a chemical bond between each other.

That is, the magnetic carrier contains a bound polyrotaxane formed by binding a first polyrotaxane and a second polyrotaxane,
The first polyrotaxane and the second polyrotaxane may be bonded to each other by forming a chemical bond between a cyclic molecule contained in the first polyrotaxane and a cyclic molecule contained in the second polyrotaxane.

In this disclosure, a chemical bond may be a single bond or a bond via various atoms or molecules (a bond via a connector).

In addition, multiple cyclic molecules contained in one polyrotaxane may be bonded to each other by forming chemical bonds.

<Magnetic Carrier>
The magnetic carrier according to the present disclosure contains a magnetic material-dispersed resin carrier core containing a magnetic material and a dispersion resin, and a coating resin that coats the surface of the magnetic material-dispersed resin carrier core. The magnetic material-dispersed resin carrier core is a carrier core in which a magnetic material is dispersed in a dispersion resin. In addition, the carrier core is preferably composed of a magnetic material and a dispersion resin.

<Magnetic material>
Examples of the magnetic body according to the present disclosure include the following.

Magnetite particles, maghemite particles, or magnetic iron oxide particles containing at least one selected from silicon oxide, silicon hydroxide, aluminum oxide, and aluminum hydroxide. Magnetoplumbite-type ferrite particles containing barium, strontium, or barium-strontium. Spinel-type ferrite particles containing at least one selected from manganese, nickel, zinc, lithium, and magnesium.

Among these, magnetic iron oxide particles are preferred.

The content of magnetic material in the carrier core is preferably 80 to 98% by mass.

The magnetic material is preferably treated in whole or in part with a lipophilic treatment agent. The lipophilic treatment agent used in this case can be an organic compound having at least one functional group selected from the group consisting of an epoxy group, an amino group, a mercapto group, an organic acid group, an ester group, a ketone group, a halogenated alkyl group, and an aldehyde group, or a mixture thereof.

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

In addition to the magnetic material, the following non-magnetic particles may be used in combination with the magnetic material.

Non-magnetic iron oxide particles such as hematite particles. Non-magnetic ferric oxide hydrous particles such as goethite particles. Non-magnetic inorganic compound particle powders such as titanium oxide particles, silica particles, talc particles, alumina particles, barium sulfate particles, barium carbonate particles, cadmium yellow particles, calcium carbonate particles, and zinc oxide particles.

When using a mixture of magnetic material and non-magnetic particles, it is preferable that the mixing ratio of the magnetic material is 30% by mass.

<Dispersion Resin>
The dispersion resin according to the present disclosure preferably contains at least one selected from the group consisting of phenolic resins, epoxy resins, and polyester resins. A phenolic resin, such as a phenol-formaldehyde resin, is more preferable. Furthermore, it is preferable that the dispersion resin is mainly composed of such a resin.

The content of the dispersion resin in the magnetic material-dispersed resin carrier core is preferably 2.0 to 20.0% by mass.

<Coating resin>
The magnetic carrier also contains a coating resin that coats the surface of the carrier core. The content of the coating resin in the magnetic carrier is preferably 1.0 to 5.0% by mass.

Methods for coating the surface of the magnetic carrier core with resin include, but are not limited to, dipping, spraying, brushing, dry coating, and coating by coating methods such as fluidized bed.

The resin used as the coating resin is preferably a vinyl resin that is a copolymer of a vinyl monomer having a cyclic hydrocarbon group in its molecular structure and another vinyl monomer. More preferred is a copolymer of a monomer including a (meth)acrylic acid ester having an alicyclic hydrocarbon group and a macromonomer. More preferred is a copolymer of a (meth)acrylic acid ester having an alicyclic hydrocarbon group, another (meth)acrylic monomer other than the (meth)acrylic acid ester having the alicyclic hydrocarbon group, and a macromonomer. In addition, the above alicyclic hydrocarbon group is preferably a cyclohexyl group.

In addition, conductive particles or particles or materials with charge control properties may be contained in the coating resin. Examples of conductive particles include carbon black, magnetite, graphite, zinc oxide, and tin oxide.

The amount of conductive particles added is preferably 0.1 parts by mass or more and 10.0 parts by mass or less per 100 parts by mass of coating resin in order to adjust the resistance of the magnetic carrier.

Examples of particles with charge control properties include particles of organic metal complexes, organic metal salts, chelate compounds, monoazo metal complexes, acetylacetone metal complexes, and hydroxycarboxylic acid metal complexes. Other examples include particles of polycarboxylic acid metal complexes, polyol metal complexes, polymethyl methacrylate resins, polystyrene resins, melamine resins, phenolic resins, nylon resins, silica, titanium oxide, and alumina.

The amount of charge-controlling particles added is preferably 0.5 parts by mass or more and 50.0 parts by mass or less per 100 parts by mass of the coating resin in order to adjust the amount of triboelectric charge.

<Method of Manufacturing Magnetic Carrier>
The magnetic carrier according to the present disclosure can be manufactured, for example, by the method described in the examples below. Specifically, first, phenols and aldehydes are stirred in an aqueous medium in the presence of magnetic and non-magnetic inorganic compound particles, polyrotaxane, and a basic catalyst. Then, the phenols and aldehydes are reacted and cured to produce particles containing inorganic compound particles and phenol resin.

It can also be produced by grinding a binder resin containing inorganic compound particles, a so-called kneading and grinding method. The former method is preferred because it is easy to control the particle size of the magnetic carrier and to obtain a sharp particle size distribution.

<Toner>
The toner according to the present disclosure is a toner having toner particles, the weight average particle size (D4) of which is preferably 3.0 to 10.0 μm.

<Binder resin>
Examples of the binder resin used in the toner particles of the toner of the present disclosure include the following polymers.
Homopolymers of styrene and its substituted derivatives, such as polystyrene, poly-p-chlorostyrene, and polyvinyltoluene;
Styrenic copolymers such as styrene-p-chlorostyrene copolymer, styrene-vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, styrene-acrylic acid ester copolymer, styrene-methacrylic acid ester copolymer, styrene-α-chloromethyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-vinyl methyl ether copolymer, styrene-vinyl ethyl ether copolymer, styrene-vinyl methyl ketone copolymer, and styrene-acrylonitrile-indene copolymer;
Polyvinyl chloride, phenolic resin, naturally modified phenolic resin, naturally modified maleic acid resin, acrylic resin, methacrylic resin, polyvinyl acetate, silicone resin, polyester, polyurethane, polyamide, furan resin, epoxy resin, xylene resin, polyvinyl butyral, terpene resin, coumarone-indene resin, petroleum-based resin.

Among these, polyester is preferred from the viewpoint of the toner's chargeability.

<Wax>
The toner particles may contain wax. Examples of the wax 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 mainly composed of fatty acid esters, such as carnauba wax;
Deoxidized carnauba wax and other fatty acid esters that have been partially or completely deoxidized.

Among these, from the viewpoint of low-temperature fixing property and hot offset resistance of the toner, hydrocarbon waxes such as paraffin wax and Fischer-Tropsch wax, and fatty acid ester waxes such as carnauba wax are preferred.

In the present disclosure, from the viewpoint of electrostatic chargeability, hydrocarbon waxes are more preferred.

The wax content in the toner particles is preferably 1.0 to 20.0 parts by mass per 100 parts by mass of the binder resin in the toner particles. A wax content in the above range is more preferable from the viewpoint of chargeability.

<Coloring Agent>
The toner particles may contain a colorant, such as a known yellow colorant, magenta colorant, cyan colorant, or black colorant.

Examples of black colorants include carbon black, and those toned to black using yellow, magenta, and cyan colorants.

As colorants, pigments or dyes may be used alone, or dyes and pigments may be used in combination.

The content of colorant in the toner particles is preferably 0.1 parts by mass or more and 30.0 parts by mass or less per 100 parts by mass of the binder resin in the toner particles.

<Magnetic material>
The toner of the present disclosure may be a magnetic toner. When used as a magnetic toner, it is preferable to use magnetic iron oxide as a magnetic material contained in the toner particles. Examples of magnetic iron oxide include magnetite, maghematite, and ferrite.

The content of the magnetic material in the toner particles is preferably 25 parts by weight or more and 95 parts by weight or less, and more preferably 30 parts by weight or more and 45 parts by weight or less, per 100 parts by weight of the binder resin in the toner particles.

<Charge Control Agent>
The charge control agent includes a negative charge control agent and a positive charge control agent.

Examples of negative charge control agents include metal salicylate compounds, metal naphthoate compounds, metal dicarboxylate compounds, polymeric compounds having sulfonic acid or carboxylic acid on the side chain, polymeric compounds having sulfonate or sulfonate ester on the side chain, polymeric compounds having carboxylate or carboxylate ester on the side chain, boron compounds, urea compounds, silicon compounds, calixarenes, etc.

When the toner particles contain a charge control agent, the charge control agent may be added internally or externally to the toner particles.

The content of the charge control agent in the toner particles is preferably 0.2 parts by mass or more and 10.0 parts by mass or less per 100 parts by mass of the binder resin in the toner particles.

<External Additives>
The toner of the present disclosure may contain an external additive in order to improve the fluidity of the toner or adjust the triboelectric charge amount. As the inorganic particulate external additive, inorganic particulates such as silicon oxide (silica), aluminum oxide (alumina), titanium oxide (titania), strontium titanate, and calcium carbonate are preferable. As the external additive other than the inorganic particulates, for example, resin particulates such as vinyl resin, polyester, and silicone resin can be mentioned.

These inorganic and resin particles control the chargeability of the toner and function as fluidity and cleaning aids.

<Toner Manufacturing Method>
The toner of the present disclosure can be produced by a known method for producing toner particles, such as a melt kneading method, an emulsion aggregation method, or a solution suspension method.

The procedure for producing toner using the pulverization method is explained below.

In the raw material mixing process, the materials that make up the toner particles, such as binder resin, release agent, colorant, crystalline polyester, and other components such as charge control agents as necessary, are weighed out in predetermined amounts, blended, and mixed. Examples of mixing devices include double-con mixers, V-type mixers, drum mixers, super mixers, Henschel mixers, Nauta mixers, and Mechano Hybrids (manufactured by Nippon Coke and Engineering Co., Ltd.).

Next, the mixed materials are melt-kneaded to disperse the wax in the binder resin. In the melt-kneading process, a batch 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 due to their advantage of continuous production. Examples include a KTK twin-screw extruder (manufactured by Kobe Steel, Ltd.), a TEM twin-screw extruder (manufactured by Toshiba Machine Co., Ltd.), a PCM kneader (manufactured by Ikegai Iron Works), a twin-screw extruder (manufactured by KCK Corporation), a Co-Kneader (manufactured by Buss Co., Ltd.), and a Kneadex (manufactured by Nippon Coke and Engineering Co., Ltd.). Furthermore, the resin composition obtained by melt-kneading may be rolled with a twin roll or the like and cooled with water in a cooling process.

The cooled resin composition is then pulverized to the desired particle size in a pulverization process. In the pulverization process, the resin composition is coarsely pulverized using a pulverizer such as a crusher, hammer mill, or feather mill, and then further pulverized using a pulverizer such as a Cryptron System (manufactured by Kawasaki Heavy Industries, Ltd.), a Super Rotor (manufactured by Nisshin Engineering Co., Ltd.), a Turbo Mill (manufactured by Turbo Kogyo Co., Ltd.), or an air jet type pulverizer.

Then, if necessary, the mixture is classified using a classifier or sieve such as an inertial classification system such as Elbow Jet (manufactured by Nittetsu Mining Co., Ltd.), a centrifugal classification system such as Turboplex (manufactured by Hosokawa Micron Corporation), TSP Separator (manufactured by Hosokawa Micron Corporation), or Faculty (manufactured by Hosokawa Micron Corporation).

Methods for external addition include stirring and mixing using a mixing device such as a Double Con mixer, V-type mixer, drum mixer, Super mixer, Henschel mixer, Nauta mixer, Mechano Hybrid (manufactured by Nippon Coke & Engineering Co., Ltd.), or Nobilta (manufactured by Hosokawa Micron Corporation) as an external addition device. In this case, external additives other than silica fine particles, such as a fluidizing agent, may be added as necessary.

<Various measurement methods>
<Measurement of weight average particle size (D4) of toner particles>
The weight average particle size (D4) of the toner particles is measured using a precision particle size distribution measuring device by a pore electrical resistance method equipped with a 100 μm aperture tube, “Coulter Counter Multisizer 3” (registered trademark, manufactured by Beckman Coulter, Inc.), and the accompanying dedicated software for setting measurement conditions and analyzing measurement data, “Beckman Coulter Multisizer 3 Version 3.51” (manufactured by Beckman Coulter, Inc.), with an effective measurement channel count of 25,000, and the measurement data is analyzed and calculated.

The aqueous electrolyte solution used for the measurements is prepared by dissolving special grade sodium chloride in deionized water to a concentration of approximately 1% by mass, for example "ISOTON II" (manufactured by Beckman Coulter).

Before performing measurements and analysis, configure the dedicated software as follows:

In the "Change Standard Measurement Method (SOM) screen" of the dedicated software, set the total count in control mode to 50,000 particles, the number of measurements to 1, and the Kd value to the value obtained using "Standard Particle 10.0 μm" (manufactured by Beckman Coulter). Press the threshold/noise level measurement button to automatically set the threshold and noise level. Also, set the current to 1600 μA, the gain to 2, the electrolyte to ISOTON II, and check the aperture tube flush after measurement.

In the dedicated software's "Pulse to particle size conversion setting screen," set the bin interval to logarithmic particle size, the particle size bin to 256 particle size bins, and the particle size range to 2 μm to 60 μm.

The specific measurement methods are as follows (1) to (7).

(1) Pour about 200 ml of the above electrolyte solution into a 250 ml round-bottom glass beaker made specifically for the Multisizer 3, set it on the sample stand, and stir the stirrer rod counterclockwise at 24 revolutions per second. Then, use the "aperture tube flush" function of the dedicated software to remove dirt and air bubbles from inside the aperture tube.

(2) Place about 30 ml of the above electrolyte solution in a 100 ml flat-bottom glass beaker. Add about 0.3 ml of a solution of "Contaminon N" (a 10% aqueous solution of a pH 7 neutral detergent for cleaning precision measuring instruments made from a nonionic surfactant, an anionic surfactant, and an organic builder, manufactured by Wako Pure Chemical Industries, Ltd.) diluted 3 times by weight with deionized water as a dispersant.

(3) A specified amount of deionized water is placed in the water tank of an ultrasonic disperser "Ultrasonic Dispersion System Tetorara 150" (manufactured by Nikkaki Bios Co., Ltd.) that has two built-in oscillators with an oscillation frequency of 50 kHz and a phase shift of 180 degrees and an electrical output of 120 W, and approximately 2 ml of the above Contaminon N is added to this water tank.

(4) Place the beaker from (2) in the beaker fixing hole of the ultrasonic disperser and operate the ultrasonic disperser. Then, adjust the height of the beaker so that the resonance state of the electrolyte solution surface in the beaker is maximized.

(5) While the electrolyte solution in the beaker in (4) is being irradiated with ultrasonic waves, approximately 10 mg of toner particles are added little by little to the electrolyte solution and dispersed. Then, ultrasonic dispersion processing is continued for another 60 seconds. During ultrasonic dispersion, the water temperature in the water tank is appropriately adjusted so that it is between 10°C and 40°C.

(6) Using a pipette, drip the electrolyte solution (5) in which the toner particles have been dispersed into the round-bottom beaker (1) placed in the sample stand, and adjust the measurement concentration to approximately 5%. Then, measurements are continued until the number of particles measured reaches 50,000.

(7) The measurement data is analyzed using the dedicated software that comes with the device, and the weight average particle size (D4) is calculated. Note that when the dedicated software is set to Graph/Volume %, the "Average diameter" on the Analysis/Volume Statistics (Arithmetic Mean) screen is the weight average particle size (D4).

<Measurement of weight average molecular weight by GPC>
The molecular weight distribution of a sample is measured by gel permeation chromatography (GPC) as follows.

First, a sample is dissolved in tetrahydrofuran (THF) at room temperature for 24 hours. The obtained solution is then filtered through a solvent-resistant membrane filter "Maeshori Disk" (manufactured by Tosoh Corporation) with a pore size of 0.2 μm to obtain a sample solution. The sample solution is adjusted so that the concentration of components soluble in THF is about 0.8 mass%. This sample solution is used to perform measurements under the following conditions.
Apparatus: HLC8120 GPC (detector: RI) (manufactured by Tosoh Corporation)
Column: 7 columns of Shodex KF-801, 802, 803, 804, 805, 806, and 807 (manufactured by Showa Denko Co., Ltd.)
Eluent: tetrahydrofuran (THF)
・Flow rate: 1.0ml/min
Oven temperature: 40.0°C
Sample injection volume: 0.10 ml
In calculating the molecular weight of the sample, a molecular weight calibration curve prepared using standard polystyrene resins (for example, trade names "TSK Standard Polystyrene F-850, F-450, F-288, F-128, F-80, F-40, F-20, F-10, F-4, F-2, F-1, A-5000, A-2500, A-1000, A-500", manufactured by Tosoh Corporation) is used.

<Method of measuring volume average particle size (D50) of magnetic carrier and magnetic carrier core>
The particle size distribution and the like are measured using a laser diffraction/scattering type particle size distribution measuring device (product name: Microtrac MT3300EX, manufactured by Nikkiso Co., Ltd.). The measurement is performed by attaching a sample supplying device for dry measurement (product name: One-shot dry type sample conditioner Turbotrac, manufactured by Nikkiso Co., Ltd.). The supply conditions for Turbotrac are a dust collector as a vacuum source, an air volume of 33 l/sec, and a pressure of 17 kPa. The control is performed automatically on the software. The particle size is calculated as the 50% particle size (D50), which is the cumulative value of the volume average. The control and analysis are performed using the attached software (version 10.3.3-202D). The measurement conditions are as follows.
Set Zero time: 10 seconds Measurement time: 10 seconds Number of measurements: 1 Particle refractive index: 1.81%
・Particle shape: non-spherical ・Measurement upper limit: 1408μm
・Measurement lower limit: 0.243μm
・Measurement environment: Temperature 23℃/Humidity 50%RH

The present disclosure will be explained in more detail below with reference to examples, but the present disclosure is not limited to these.

<Method of producing polyrotaxane A1>
The following materials were added to a reaction vessel equipped with a stirrer, a condenser, and a thermometer, and the mixture was stirred uniformly.
・10.0 g of the following polyrotaxane 1
(Polyrotaxane 1: SeRM Super Polymer SA1305P-20 (product name), manufactured by ASM Corporation. The chain molecule has a polyethylene glycol structure and an adamantyl group at the end of the chain molecule, and contains, as a cyclic molecule, a plurality of α-cyclodextrins having a polycaprolactone structure at the side chain. In addition, since the end of the side chain has an acrylic skeleton, it has a vinyl polymerizable carbon-carbon double bond.)
・1.0N-NaOH aqueous solution 40mL
1,4-butanediol diglycidyl ether (Tokyo Chemical Industry Co., Ltd.) 1.2 mL
The mixture was stirred at 23°C for 24 hours to obtain a polyrotaxane in which the cyclic molecules were crosslinked with each other. Next, after isolation, 600.0 g of xylene, 150.0 g of styrene, 50.0 g of methyl methacrylate, and 1.5 g of initiator t-butyl peroxypivalate were added, and polymerization was carried out for 3 hours while rotating the stirrer and maintaining the temperature at 90°C to obtain a reaction product. The reaction product obtained was washed and dried to obtain polyrotaxane A1 in which cyclodextrins were chemically bonded to each other and side chains having a polycaprolactone structure and a styrene-methyl methacrylate polymer structure were bonded to the cyclodextrins.

<Method of producing polyrotaxane A2>
The following materials were added to a reaction vessel equipped with a stirrer, a condenser, and a thermometer, and stirred uniformly.
・10.0 g of the following polyrotaxane 2
(Polyrotaxane 2: SeRM Super Polymer SM1305P-20 (product name), manufactured by ASM Corporation. The chain molecule has a polyethylene glycol structure and an adamantyl group at the end of the chain molecule, and contains, as a cyclic molecule, a plurality of α-cyclodextrins having a polycaprolactone structure at the side chain. In addition, since the end of the side chain has a methacryl skeleton, it has a vinyl polymerizable carbon-carbon double bond.)
・1.0N-NaOH aqueous solution 40mL
1,4-butanediol diglycidyl ether (Tokyo Chemical Industry Co., Ltd.) 1.2 mL
The mixture was stirred at 23°C for 24 hours to obtain a polyrotaxane in which the cyclic molecules were crosslinked with each other. After isolation, 600.0 g of xylene, 250.0 g of styrene, 75.0 g of methyl methacrylate, and 1.5 g of initiator t-butyl peroxypivalate were added, and polymerization was carried out for 5 hours while rotating the stirrer and maintaining the temperature at 90°C to obtain a reaction product. The reaction product obtained was washed and dried to obtain polyrotaxane A2 in which cyclodextrin molecules were chemically bonded to each other and side chains having a polycaprolactone structure and a styrene-methyl methacrylate polymer structure were bonded to the cyclodextrin.

<Method of producing polyrotaxane A3>
The following materials were added to a reaction vessel equipped with a stirrer, a condenser, and a thermometer, and stirred uniformly.
10.0 g of the above polyrotaxane 2
・1.0N-NaOH aqueous solution 40mL
1,4-butanediol diglycidyl ether (Tokyo Chemical Industry Co., Ltd.) 1.2 mL
A polyrotaxane in which the cyclic molecules were crosslinked with each other was obtained by stirring at a temperature of 23°C for 24 hours. Next, after isolation, 600.0 g of xylene, 300.0 g of styrene, 100.0 g of methyl methacrylate, and 1.5 g of initiator t-butyl peroxypivalate were added, and polymerization was carried out for 8 hours while rotating the stirrer and maintaining the temperature at 90°C, to obtain a reaction product. The obtained reaction product was washed and dried to obtain polyrotaxane A3 in which cyclodextrins were chemically bonded to each other and side chains having a polycaprolactone structure and a styrene-methyl methacrylate polymer structure were bonded to the cyclodextrin.

<Method of producing polyrotaxane A4>
Into a reaction vessel equipped with a stirrer, a condenser, and a thermometer, 600.0 g of xylene, 10.0 g of the above polyrotaxane 2, 150.0 g of styrene, 50.0 g of methyl methacrylate, and 1.5 g of initiator t-butyl peroxypivalate were added. Thereafter, polymerization was carried out for 3 hours while rotating the stirrer and maintaining the temperature at 90°C, to obtain a reaction product. The obtained reaction product was washed and dried to obtain polyrotaxane A4 in which a side chain having a polycaprolactone structure and a styrene-methyl methacrylate polymer structure is bonded to cyclodextrin.

<Polyrotaxane A5>
Polyrotaxane A5 was prepared using the above-mentioned polyrotaxane 2.

<Method of producing polyrotaxane A6>
To a reaction vessel equipped with a stirrer, condenser, and thermometer were added the following materials:
・Xylene 1200.0g
10.0 g of the above polyrotaxane 2
Styrene 1000.0g
Methyl methacrylate 350.0g
Initiator t-butyl peroxypivalate 1.5 g
Thereafter, polymerization was carried out for 24 hours while rotating the stirrer and maintaining the temperature at 90° C., to obtain a reaction product. The reaction product obtained was washed and dried to obtain polyrotaxane A6 in which a side chain having a polycaprolactone structure and a styrene-methyl methacrylate polymer structure was bonded to cyclodextrin.

<Method of producing polyrotaxane A7>
To a reaction vessel equipped with a stirrer, condenser, and thermometer were added the following materials:
・Xylene 1200.0g
10.0 g of the above polyrotaxane 2
Styrene 1000.0g
Methyl methacrylate 500.0g
Initiator t-butyl peroxypivalate 1.5 g
Thereafter, polymerization was carried out for 24 hours while rotating the stirrer and maintaining the temperature at 90° C., to obtain a reaction product. The reaction product was washed and dried to obtain polyrotaxane A7 in which a side chain having a polycaprolactone structure and a styrene-methyl methacrylate polymer structure was bonded to cyclodextrin.

<Method of producing polyrotaxane A8>
2,2,6,6-Tetramethyl-1-piperodinyloxy radical (TEMPO) (6.4×10 ⁻⁴ mol) was added to 100 mL of pure water, and the pH was adjusted to 10 to 11. Sodium bromide (9.7×10 ⁻⁴ mol), sodium hypochlorite (10 mL), and 7.0×10 ⁻⁴ mol of polyethylene glycol (manufactured by Aldrich, hereinafter referred to as PEG) with n=35000 were added to this solution, and the mixture was stirred at room temperature for 10 to 15 minutes to oxidize the PEG terminals.

After adding 10 ml of ethanol, the mixture was adjusted to pH 2, and dichloromethane extraction was performed using 100 ml of dichloromethane in three portions. The dichloromethane extract was evaporated to dryness under reduced pressure, dissolved in ethanol at 40-50°C, frozen for one day, and the PEG (PEG-COOH) with the terminal group being a carboxylic acid was collected by centrifugation. The resulting PEG-COOH was freeze-dried. The PEG-COOH (8.6×10 ^-5 mol) and α-cyclodextrin (1.2×10 ^-2 mol) synthesized above were dissolved in 100 ml of pure water, and left to stand in a freezer for one day. The white paste-like compound was then freeze-dried to obtain a powdered inclusion complex.

The following materials were dissolved in 100 mL of anhydrous DMF and reacted at 4° C. for 24 hours.
14 g of the above inclusion complex
Adamantaneamine 1.1×10 ⁻³ mol
Benzotriazol-1-yloxy-trisdimethylaminophosphonium salt 1.1×10 ⁻³ mol
Ethylisopropylamine 1.2×10 ⁻³ mol
Thereafter, the mixture was washed twice with a DMF/methanol solution (1:1, v/v) and methanol, and then further washed with a mixed solution of 80 mL of anhydrous DMSO and 800 mL of pure water, followed by freeze-drying to obtain polyrotaxane A8 having α-cyclodextrin encapsulated therein.

<Preparation of treated magnetite>
4.0 parts of a silane coupling agent (3-(2-aminoethylamino)propyltrimethoxysilane) was added to 100 parts of magnetite powder having a number-average particle size of 0.30 μm, and the mixture was mixed and stirred at high speed in a container at a temperature of 100° C. or higher to obtain a treated magnetite.

<Production Example of Toner 1>
Polyoxypropylene (2.2)-2,2-bis(4-hydroxyphenyl)propane: 100.0 mol%
Terephthalic acid: 80.0 mol% based on the total number of moles of polycarboxylic acids
Trimellitic anhydride: 20.0 mol% based on the total number of moles of polycarboxylic acids
The monomer materials in the above ratio were charged into a reaction vessel equipped with a cooling pipe, a stirrer, a nitrogen inlet pipe, and a thermocouple. Then, 1.5 parts by mass of tin 2-ethylhexanoate was added as a catalyst (esterification catalyst) to 100 parts by mass of the total amount of the monomer materials. Next, the inside of the reaction vessel was replaced with nitrogen gas, and the temperature was gradually raised while stirring, and the reaction was carried out for 2 hours while stirring at a temperature of 200°C.

The pressure in the reaction vessel was then lowered to 8.3 kPa and maintained for 1 hour, after which it was cooled to 180 and allowed to react. Once it was confirmed that the softening point, measured according to ASTM D36-86, had reached 122°C, the temperature was lowered to stop the reaction, and polyester resin 1 was obtained.

The resulting polyester resin 1 had a softening point (Tm) of 112°C and a glass transition temperature (Tg) of 63°C.
Polyester resin 1: 100.0 parts by mass 3,5-di-t-butyl salicylic acid aluminum compound: 0.1 parts by mass Fischer-Tropsch wax (peak temperature of maximum endothermic peak: 90 ° C.): 5.0 parts by mass C.I. Pigment Blue 15:3 5.0 parts by mass The above raw materials were mixed using a Henschel mixer (trade name: FM75J type, manufactured by Nippon Coke & Engineering Co., Ltd.) at a rotation speed of 20 s ^-1 and a rotation time of 5 minutes, and then kneaded in a twin-screw kneader (trade name: PCM-30 type, manufactured by Ikegai Co., Ltd.) set at a temperature of 125 ° C. The kneaded product obtained was cooled and coarsely crushed to 1 mm or less with a hammer mill to obtain a coarsely crushed product. The obtained coarsely crushed product was finely crushed with a mechanical crusher (trade name: T-250, manufactured by Turbo Kogyo Co., Ltd.). Further, classification was carried out using a rotary classifier (product name: 200TSP, manufactured by Hosokawa Micron Corporation) to obtain toner particles. The operating conditions of the rotary classifier (product name: 200TSP, manufactured by Hosokawa Micron Corporation) were a classification rotor rotation speed of 50.0 ^s-1 . The weight average particle size (D4) of the obtained toner particles was 6.2 μm.

1.0 part by mass of hydrophobic silica fine particles with a primary average particle size of 15 nm that had been surface-treated with 20.0% by mass of hexamethyldisilazane was added to 100.0 parts by mass of the obtained toner particles, and mixed in a Henschel mixer (product name: FM75J type, manufactured by Nippon Coke & Engineering Co., Ltd.). The mixture was then passed through an ultrasonic vibration sieve with a mesh size of 54 μm to obtain toner 1.

<Preparation of Coating Resin Solution 1>
・28 parts by mass of methyl methacrylate macromer (average value n=50) having an ethylenically unsaturated group at one end and a weight average molecular weight of 5,000・70 parts by mass of cyclohexyl methacrylate・2 parts by mass of methyl methacrylate The above materials were added to a four-neck flask equipped with a reflux condenser, a thermometer, a nitrogen suction tube, and a grinding type stirrer. 90 parts by mass of toluene, 110 parts by mass of methyl ethyl ketone, and 2.0 parts by mass of azobisisovaleronitrile were further added. The resulting mixture was kept at a temperature of 70 ° C. under a nitrogen stream for 10 hours to obtain a resin solution (resin solid content 33% by mass).

The following materials were added to the obtained resin solution (amount so that the resin solid content was 10 parts), and then thoroughly mixed with a homogenizer to obtain a coating resin solution 1.
Crosslinked melamine particles (maximum peak particle size on the basis of number distribution: 0.2 μm) 0.5 parts by mass; carbon black fine particles (maximum peak particle size on the basis of number distribution: 0.04 μm, specific resistance: 9.0×10 ⁻¹ Ω·cm) 0.5 parts by mass; toluene 70 parts by mass

Example 1
<Production Example of Magnetic Carrier 1>
Phenol 6.0 parts by weight Formaldehyde solution (Solution 1) below 9.0 parts by weight (Solution 1: 40% formaldehyde, 10% methanol, 50% water)
84.52 parts by mass of the above treated magnetite 0.48 parts by mass of the above polyrotaxane A1 The above materials, 5 parts by mass of 28% ammonia water, and 20 parts by mass of water were placed in a flask, and the mixture was heated to 85°C in 30 minutes while stirring and mixing, and then polymerized for 3 hours to harden the resulting phenolic resin. The hardened phenolic resin was then cooled to a temperature of 30°C, and water was added, after which the supernatant liquid was removed, and the precipitate was washed with water and then air-dried. This was then dried under reduced pressure (5 mmHg or less) at a temperature of 60°C to obtain magnetic carrier core particles, which are resin particles in which a magnetic substance is dispersed.

Next, the following materials were charged into a planetary mixer (Nauta Mixer VN type, manufactured by Hosokawa Micron Corporation) maintained at a temperature of 60° C. under reduced pressure (1.5 kPa).
Obtained magnetic carrier core particles: 100.0 parts by mass Coating resin solution 1 (amount such that the content of the coating resin per 100 parts by mass of the magnetic carrier core particles is 2.0 parts by mass)
The resin solution was first added in an amount of 1/2 of the magnetic carrier core particles, and the solvent was removed and the coating was performed for 30 minutes. Next, another 1/2 of the resin solution was added, and the solvent was removed and the coating was performed for 30 minutes.

The magnetic carrier coated with the coating resin composition was then transferred to a mixer (UD-AT type drum mixer manufactured by Sugiyama Heavy Industries Co., Ltd.) with a spiral blade placed in a rotatable mixing container. The mixture was heat-treated for 2 hours at 120°C in a nitrogen atmosphere while stirring at 10 revolutions per minute. The magnetic carrier obtained was separated into low magnetic products by magnetic separation, passed through a sieve with 150 μm openings, and then classified with an air classifier to obtain magnetic carrier 1. The volume average particle size of the magnetic carrier obtained was 35.2 μm.

<Production Example of Two-Component Developer>
The above toner 1 and magnetic carrier 1 were mixed using a V-type mixer (product name: V-10 type, Tokuju Seisakusho Co., Ltd.) under conditions of 0.5 s ⁻¹ and 5 minutes so that the toner concentration became 9% by mass, to obtain a two-component developer.

<Production Example of Replenishing Developer>
The above toner 1 and magnetic carrier 1 were mixed using a V-type mixer (product name: V-10 type, Tokuju Seisakusho Co., Ltd.) under conditions of 0.5 s ^-1 and 5 minutes so that the toner concentration became 90% by mass, to obtain a replenishment developer.

<Evaluation>
The following evaluations were carried out using the magnetic carrier 1, the obtained two-component developer, and the obtained replenishment developer.

<Measurement of Carrier Strength>
First, the volume average particle diameter of the magnetic carrier 1 was measured by the above measurement method, and the value was designated as D0 (μm). Next, 100 g of the magnetic carrier 1 was put into a sample mill (SK-M10, manufactured by Kyoritsu Riko Co., Ltd.), and the rotation speed was set to 16,500 rpm, and the pulverization process was performed for 60 seconds. Thereafter, the volume average particle diameter of the carrier after the pulverization process was measured by the above measurement method, and the value was designated as D1 (μm). Then, the above D0 and D1 were substituted into the following formula to calculate the particle diameter change rate of the carrier. The results are shown in Table 2. If the particles crack, chip, or fine particles are generated due to stress caused by the pulverization process, the volume average particle diameter after the pulverization process will be smaller, so the change rate of the volume average particle diameter before and after the pulverization process was used as an index of the carrier strength.
Carrier strength (particle size change rate) (%) = [(D0-D1)/D0] x 100
D0: Volume average particle size (μm) of the carrier before pulverization
D1: Volume average particle size (μm) of the carrier after pulverization
(The volume average particle size was measured by the above-mentioned measurement method.)

<Fog evaluation>
A modified full-color copier (product name: imageRUNNER ADVANCE C5560) manufactured by Canon Inc. was used as the image forming apparatus. The modification was to make the process speed and development bias variable. The process speed of the modified machine was adjusted so that it could output at 380 mm/sec in normal durability mode and 460 mm/sec in stress durability mode, and the development bias was adjusted so that the initial image density was 1.55. A4-size plain paper for copying (product name: GF-C081, basis weight: 81.4 g/m ² , sold by Canon Marketing Japan Inc.) was used as the paper for evaluation.

When forming images, the developer in the cyan developer container was replaced with the two-component developer described above, and the developer in the cyan replenishment developer container was replaced with the replenishment developer described above. The reason why the two-component developer and the replenishment developer were used in this evaluation is because using both of them is the normal mode when using the image forming device described above.

First, a durability test of 300,000 sheets was conducted in a high temperature and high humidity environment (30°C/80% RH) with a process speed of 380 mm/sec and an FFH output chart with an image ratio of 40%. The sheet was then left to stand in the same environment for three days, after which a blank image (00h image) was output. The average reflectance (%) of the blank image before output and the blank image after output was measured, and the difference (%) between the average reflectances was taken as the fog density to evaluate the image fog. The results are shown in Table 2. The average reflectance was measured using a "REFLECTMETER MODEL TC-6DS" (manufactured by Tokyo Denshoku Co., Ltd.).

The process speed was also changed to 460 mm/sec, and the same operations were carried out as above to calculate the image fog density. The results are shown in Table 2.

<Toner scattering>
After the durability test at each process speed, the developing unit was removed from the machine and set on an idle rotating jig that rotates the developer carrier. Then, A4 paper was placed directly under the developer carrier and rotated for 10 minutes at the same peripheral speed as the process speed at which the image was output. The mass of the toner that fell on the paper was measured to evaluate the toner scattering. The results are shown in Table 2.

<Examples 2 to 13>
Magnetic carriers 2 to 13 were obtained in the same manner as in Example 1, except that the types and the numbers of the materials used were changed as shown in Table 1. Then, two-component developers and replenishment developers were prepared in the same manner, and evaluations were performed. The evaluation results are shown in Table 2.

<Example 14>
A two-component developer and a replenishment developer were prepared and evaluated in the same manner as in Example 1, except that the magnetic carrier 1 was changed to the magnetic carrier 14 described below and the types and the numbers of parts of the materials used were changed as shown in Table 1. The evaluation results are shown in Table 2.

[Production Example of Magnetic Carrier 14]
Polyester resin ("Tufton" TTR-2: manufactured by Kao Corporation, glass transition point 65°C, acid value 3 mgKOH/g) 10.0 parts by mass The above treated magnetite 64.05 parts by mass Polyrotaxane A8 6.5 parts by mass The above materials were stirred and mixed with a stirrer ("Super Mixer" SMV-20: manufactured by Kawata Corporation), and then melt-kneaded with a twin-screw kneading extruder (PCM-30: manufactured by Ikegai Iron Works). After cooling, the kneaded product was coarsely pulverized to 2 mmφ pass with a coarse pulverizer (UG-210KGS: manufactured by Toku Iron Works), and this was medium-pulverized with a medium pulverizer ("Fine Mill" FM-300N: manufactured by Nippon Pneumatic Industrial Co., Ltd.). Then, it was passed through a fine powder classifier ("Separator" DS-5UR: manufactured by Nippon Pneumatic Industrial Co., Ltd.) to obtain magnetic carrier core particles 14.

<Comparative Example 1>
A magnetic carrier 15 was obtained in the same manner as in Example 1, except that the types and the numbers of the materials used were changed as shown in Table 1. Then, a two-component developer and a replenishment developer were prepared in the same manner as in Example 1, and were evaluated. The evaluation results are shown in Table 2.

In Table 1, the epoxy resin was EPICLON HP-6000 (trade name, manufactured by DIC Corporation). The molecular weight of the cyclic molecules was measured using the method described above.

Claims (12)

A magnetic carrier comprising a magnetic material-dispersed resin carrier core containing a magnetic material and a dispersion resin, and a coating resin that coats the surface of the magnetic material-dispersed resin carrier core,
The magnetic material-dispersed resin carrier core contains polyrotaxane,
The polyrotaxane is
(i) a plurality of cyclic molecules;
(ii) a chain molecule that is included in the ring of the cyclic molecule in a skewered manner;
(iii) The magnetic carrier, wherein the chain molecule has two or more blocking groups that prevent the cyclic molecule from being detached from the chain molecule. The magnetic carrier according to claim 1, wherein the cyclic molecule is a molecule having a cyclodextrin skeleton. The magnetic carrier according to claim 2, wherein the weight-average molecular weight of the molecule having a cyclodextrin skeleton is 1,000 to 50,000. The magnetic carrier according to claim 2 or 3, wherein the molecule having a cyclodextrin skeleton has a cyclodextrin and a side chain bonded to the cyclodextrin. The magnetic carrier according to claim 4, wherein the side chain has a polyester structure or a vinyl polymer structure. The magnetic carrier according to any one of claims 1 to 5, wherein the content of the polyrotaxane is 0.2% by mass or more and 30.0% by mass or less relative to the mass of the dispersion resin. The magnetic carrier according to any one of claims 1 to 6, wherein the dispersion resin includes at least one selected from the group consisting of phenolic resin, epoxy resin, and polyester resin. The magnetic carrier according to any one of claims 1 to 7, wherein the content of the dispersion resin in the magnetic material-dispersed resin carrier core is 2.0 to 20.0 mass %. the polyrotaxane comprises a first polyrotaxane and a second polyrotaxane,
the magnetic carrier contains a bound polyrotaxane formed by binding the first polyrotaxane and the second polyrotaxane,
The magnetic carrier according to any one of claims 1 to 8, wherein the first polyrotaxane and the second polyrotaxane are bonded to each other by forming a chemical bond between a cyclic molecule of the first polyrotaxane and a cyclic molecule of the second polyrotaxane. The magnetic carrier according to any one of claims 1 to 9, wherein the chain molecule is a molecule having a polyalkylene glycol chain. A two-component developer containing a toner and a magnetic carrier,
A two-component developer, wherein the magnetic carrier is the magnetic carrier according to any one of claims 1 to 10. A replenishment developer containing a toner and a magnetic carrier,
A replenishing developer, wherein the magnetic carrier is the magnetic carrier according to any one of claims 1 to 10.