JP2002162789A - Coating carrier and method of manufacturing the same, and developer for electrophotography - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coating carrier which is capable of suppressing toner splashing or occurrence of fogging, provide a method of manufacturing the same, and also provide a developer for electrophotography. SOLUTION: The coating carrier has a core particle and a coating layer to coat the surface of the core particle with a silicone-based resin, and when the coating carrier is manufactured, it is heated from a first temperature to a second temperature under the manufacturing conditions such that the weight change ratio between the weight of the carrier at the first temperature and the weight of the carrier at the second temperature is in the range of 0-0.15% by measurement of thermogravimetry.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a coating carrier, a method for producing the same, and a developer for electrophotography.

[0002]

2. Description of the Related Art Generally, there are a one-component system and a two-component system as an electrostatic latent image developer in electrophotography. Among them, the two-component developer mainly includes a toner and a carrier for conveying the toner to the latent image portion and imparting a uniform triboelectric charge.

On the other hand, recording abnormalities in the electrophotographic recording method include toner scattering and fogging. As a cause of toner scattering or image fogging, for example, the toner adheres to the photosensitive member in a film form, the sensitivity of the photosensitive member decreases due to so-called filming, the residual potential increases, or the toner adheres to the carrier, It is known that fusion of toner to recording paper in a fixing device is not sufficient.

In order to prevent these phenomena, Japanese Patent Publication No. 2874167 discloses that trace amounts of low molecular weight oligomers, raw material monomers, reaction residues, organic solvents, etc., which have not yet sufficiently jumped out during the synthesis of the binder resin for the toner remain. After finding that the cause is local plasticization of the binder resin, it is suggested that after the synthesis of the binder resin, sufficient desolvation, washing and drying be performed to remove the plasticized substance to a certain standard. Have been.

[0005]

In recent years, a coating carrier has been used as a carrier.
The coating carrier generally refers to a carrier in which a coating layer is provided on the surface of a core particle composed of an iron powder carrier, a ferrite carrier, or the like. The coated carrier is required to have such properties that toner particles are not fixed to the surface of the carrier particles to make toner charging unstable and have excellent durability.

In Japanese Patent Publication No. 2874167, the relationship between the quality of the thermoplastic resin used for the toner and the toner scattering and fog is examined, but the relationship with the coating carrier is not studied at all. The quality of the coating carrier is expected to have a great influence on the printing characteristics and may be involved in toner scattering and fogging, but this has not been studied at all.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a coating carrier capable of suppressing toner scattering and generation of fog, a method for producing the same, and an electrophotographic developer.

[0008]

Means for Solving the Problems In order to solve this problem, the present inventors have conducted intensive studies on the relationship between the coating carrier and toner scattering and fog.
Focusing on the dispersion of toner scattering and fogging when using a two-component developer between lots of coating carriers using silicone resin, repeated thinking and error resulted in the thermal weight of the coating carrier It has been found that there is a correlation between the thermogravimetric change rate in measurement and toner scattering and fog. That is, in the coating step of forming a coating layer on the surface of the core particles (carrier core material), the coating resin is thermoset, and the conditions for this thermosetting are appropriately controlled, and the thermogravimetric change in the thermogravimetry of the coating carrier is measured. It has been found that when the rate is within a predetermined standard, toner scattering and fogging can be significantly suppressed.

The present invention has been made based on such findings, and is a coating carrier comprising core particles, and a coating layer for coating the surface of the core particles with a silicone resin. According to thermogravimetry, when the coated carrier is heated from the first temperature to the second temperature, the weight change rate between the carrier weight at the first temperature and the carrier weight at the second temperature is 0. ~
Coating carrier characterized by 0.15%.

Here, for example, the first temperature for thermogravimetry may be 100 ° C., and the second temperature may be 500 ° C.

Particularly preferably, the first temperature of the thermogravimetric measurement is 100 ° C., the second temperature is 350 ° C., and the weight change rate is −0.005 to −0.05%.

The present invention also provides a coating carrier comprising core particles and a coating layer obtained by coating the surfaces of the core particles with a silicone resin and curing the silicone particles. In order to provide a coating carrier, a heat treatment is performed at a heating temperature of 300 to 320 ° C. and a heating time of 45 to 90 minutes.

Further, the present invention provides an electrophotographic developer characterized by containing such a coating carrier and a toner.

The present invention further provides a step of coating the surface of the core particles with a silicone resin, and heating the core particles coated with the silicone resin to a heating temperature of 300 to 32.
Performing a heat treatment at 45 ° C. for 45 to 90 minutes;
And a method for producing a coated carrier.

In the present invention, the rate of weight change in thermogravimetry (TG) is obtained by calculating the rate of weight change when the coating carrier is heated using a differential thermobalance.
Is the rate of change of the thermogravimetric measurement result between the carrier weight at the temperature (for example, 100 ° C.) and the carrier weight at the second temperature (for example, 500 ° C.), and is expressed by the following equation (1).

[0016]

(Equation 1)

The thermogravimetry is described in detail in Kotaro Kobe, "Thermal Analysis", Kodansha, Tokyo (1975) or Yasutoshi Saito, "Thermal Analysis for Beginners", The Society of Thermometry (1985).

The small thermogravimetric change rate in the above thermogravimetric measurement indicates that the main factor is that the uncured portion in the coating resin is small. In a coating carrier having a small thermogravimetric change rate as specified in the present invention, the coating resin is sufficiently cured in the coating layer, and is stable, so that even if used for a long time, the initial intended purpose can be achieved. In addition, the toner can be prevented from sticking to the surface of the carrier particles, and the desired polarity and charge can be given to the toner. As a result, electrophotographic recording without toner scattering and fogging can be performed for a long period of time.

The coating carrier of the present invention has a thermogravimetric change rate of 0 to -0.15%, preferably-when the first temperature is 100 ° C. and the second temperature is 500 ° C.
0.005 to -0.05%. Thermogravimetric change rate is-
If it exceeds 0.15%, the uncured portion of the coating resin remains in the coating layer and is decomposed and removed by the time the second temperature is reached, resulting in weight loss. When the carrier is used for a long time when the curing of the coating resin varies, the coating layer cannot prevent the toner from sticking to the surface of the carrier particles, and may give the toner the desired polarity and charge. This is not preferable because toner scattering and fogging occur.

Although the lower limit of the thermogravimetric change rate is logically 0%, it is about -0.005% in consideration of measurement errors and the cause of weight loss other than uncured portions. Accordingly, the thermogravimetric change rate can be suppressed to about -0.05% in practice.

Examples of the core particles used in the carrier of the present invention include ferromagnetic metals such as iron, cobalt and nickel, alloys and compounds such as magnetite, hematite and ferrite, and glass beads.

The average particle size of these core particles is usually 10
To 1000 μm, preferably 30 to 500 μm, but is not particularly limited.

In the carrier of the present invention, conventionally known silicone resins can be used for coating the core particles. For example, a straight silicone resin having an organosiloxane bond, and a silicone resin modified with an alkyd resin, a polyester resin, an epoxy resin, a polyurethane resin, an acrylic resin, or the like can be given. Particularly, a straight silicone resin is preferable.

The straight silicone resin has a structure represented by the following formula.

[0025]

Embedded image In the above formula, R ₁ is a hydrogen atom, an alkyl group having 1 to 4 carbon atoms or a phenyl group, R ₂ and R ₃ are a hydrogen group, a carbon atom 1
An alkyl group of 4 to 4, an alkoxy group having 1 to 4 carbon atoms,
A phenyl group, a phenoxy group, an alkenyl group having 2 to 4 carbon atoms, an alkenyloxy group having 2 to 4 carbon atoms, a hydroxy group, a carboxyl group, an ethylene oxide group, a glycidyl group, or a group represented by the following formula.

[0026]

Embedded image

(Wherein R ₄ and R ₅ are a hydroxy group, a carboxyl group, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, an alkenyl group having 2 to 4 carbon atoms, An alkenyloxy group having 2 to 4 atoms, a phenyl group, a phenoxy group, and k, l, m, n, o, and p each represent an integer of 1 or more.) Each of the above substituents is unsubstituted.
For example, it may have a substituent such as an amino group, a hydroxy group, a carboxyl group, a mercapto group, an alkyl group, a phenyl group, an ethylene oxide group, a glycidyl group, and a halogen atom.

For example, as a commercially available straight silicone resin, KR271, KR255, K
R251, KR152, SR2400, SR2410, SR2405 manufactured by Dow Corning Toray Silicone Co., Ltd., and the modified silicone resin is KR20 manufactured by Shin-Etsu Chemical Co., Ltd.
6 alkyd modified), KR5208 (acrylic modified),
ES1001N (epoxy-modified), KR305 (urethane-modified), SR2 manufactured by Dow Corning Toray Silicone Co., Ltd.
115 (epoxy modification) and SR2110 (alkyd modification).

When the silicone resin is roughly classified according to the curing mechanism, it is roughly classified into a heat curing type and a room temperature curing type. The heat-curing type refers to a type that is cured by heating at a temperature higher than room temperature, and is further classified into a dehydration-condensation reaction type, an addition reaction type, and a peroxide reaction type. On the other hand, the room temperature curing type refers to a type that cures when left at room temperature as well as when heated, and is further classified into a deoxime reaction type, a dealcohol reaction type, and the like. The present invention regulates the thermogravimetric change rate of a coated carrier after curing, and can prevent toner scattering and fogging when a proper carrier having almost no uncured portion in a coating layer is used for a two-component developer. The subject. Therefore, it is clear that the present invention is included in the scope of the present invention since the silicone resin is cured in both the heat-curable type and the room-temperature curable type.

In order to improve the adhesion between the carrier core material and the silicone resin layer, a coupling agent, a catalyst or the like may be added to the carrier of the present invention if necessary.

The solvent used for forming the coating layer can be appropriately selected according to the type of the resin used. For example, toluene, ligroin, xylene, methyl ethyl ketone, methyl isobutyl ketone, cellsol butyl acetate, and the like.

The amount of the silicone resin to be used is usually 0.1 to 10% by weight based on the carrier core particles, especially 0.1 to 10% by weight.
5 to 5.0% by weight is preferred.

The formation of the coating layer on the carrier core particles is performed according to a general method. For example, after dissolving a silicone-based resin in a solvent, the core particles are uniformly coated with the same resin solution by a dipping method, a spray method, brush coating, etc., then the solvent is removed by drying, followed by heat treatment (baking). I do.

In the present invention, the conditions of this heat treatment (heat treatment temperature and heat treatment time) must be selected so that the thermogravimetric change rate of the coating carrier falls within a predetermined range, and depends on the coating resin used. It will be different. For example, in the case of a silicone resin, especially a straight silicone resin, the heating temperature is 300 to 32.
By baking treatment at 0 ° C. for a heating time of 45 to 90 minutes, a coating carrier having a thermogravimetric change rate within the range specified in the present invention can be obtained. At this time, if the heating temperature is too high, the image density is undesirably reduced in the continuous actual shooting test. Also, if the heating time is long, it is not economical,
It is not preferable because the resistance of the carrier increases.

The temperature may be constant or fluctuate within the range of 300 to 320 ° C., but it is necessary to maintain the temperature for 45 to 90 minutes. Further, the rate of temperature rise up to 300 ° C. is preferably 2 to 10 ° C./min.

The printing apparatus may be either an external heating system or an internal heating system. For example, a fixed or fluid electric furnace, a rotary electric furnace, a burner furnace, a microwave device, or the like can be used.

The two-component electrophotographic developer obtained by mixing the carrier and the toner of the present invention is also included in the present invention.
The toner used here is a toner in which a colorant or the like is dispersed in a binder resin. The binder resin used for the toner is not particularly limited, but includes polystyrene, chloropolystyrene, styrene-chlorostyrene copolymer, styrene-acrylate copolymer, styrene-methacrylic acid copolymer, and Rosin-modified maleic resin, epoxy resin, polyester resin, polyurethane resin and the like can be mentioned. These may be used alone or as a mixture.

As the charge control agent that can be used in the present invention, any appropriate charge control agent can be used. Examples include salicylic acid metal chelates, metal-containing monoazo dyes, nigrosine bases, and quaternary ammonium salts.

As the colored body, conventionally known dyes and / or pigments can be used, and those used for full color can be used. For example, carbon black, phthalocyanine blue, permanent red, permanent yellow and the like can be used.

In order to prepare the toner according to the present invention, for example, the above-mentioned binder resin, charge control agent, and colorant are sufficiently mixed by a mixer such as a Henschel mixer, kneaded by a twin-screw extruder, and then cooled. After coarsely pulverizing the mixture with a feather mill or the like, the particle size is 4 to 20 μm using a jet pulverizer, an air classifier or the like.
(Average particle diameter of 7 μm), and can be obtained by adding an external additive or the like and mixing with a mixer.

The two-component developer of the present invention may further include, if necessary, a release agent such as carnauba wax, a magnetic material such as magnetite, a lubricant such as tetrafluoroethylene resin, and a cerium oxide such as cerium oxide. Various additives such as abrasives, fluidity-imparting agents such as colloidal silica, anti-caking agents, and conductivity-imparting agents such as carbon black can also be mixed.

[0042]

Embodiments of the present invention will be described below in detail.

Example 1 The core particles had an average particle size of 8
0 .mu.m, using Cu-Zn-Mg ferrite powder saturation magnetization 64Am ² / kg, relative to 1000 parts by weight of the karyoplast particles, silicone resin (trade name: SR-2410, solid content 20
Wt%, manufactured by Dow Corning Toray Silicone Co., Ltd.)
A coating solution in which 50 parts by weight was dispersed in methyl ethyl ketone was coated by a spray method using a fluid coating apparatus. Next, the core particles coated with the coating solution are subjected to heat treatment in a fluidized bed at 310 ° C. for 60 minutes.
A coating carrier I of Example 1 was obtained.

The obtained coating carrier I was subjected to thermogravimetry (TG) as follows. For this thermogravimetry, a differential thermal balance (TG812, manufactured by Rigaku Corporation) was used.
0) was used. Regarding the measurement conditions, the sample amount is 10
0 mg. The starting temperature was set to 100 ° C. in consideration of low boiling impurities such as moisture in the air and moisture in the sample. The end temperature was set to 500 ° C. in order to use an aluminum (Al) sample container. Also, the heating rate is 10 ° C /
Minutes. FIG. 1 shows the results of thermogravimetry under these conditions.
The characteristic diagram is shown in FIG. In FIG. 1, the horizontal axis indicates the heating temperature, and the vertical axis indicates the weight change rate.

Next, a two-component developer was prepared and its characteristics were evaluated. The positively charged toner used here was prepared as follows.

<Positively Charged Toner Composition> Styrene acrylic resin 100 parts Quaternary ammonium salt (TP302: manufactured by Hodogaya Chemical Co., Ltd.) 2 parts Carbon black (# 44: manufactured by Mitsubishi Chemical Corporation) 8 parts Polypropylene (TP32: Sanyo Chemical Co., Ltd.) 4 parts

The raw material having the above composition was stirred with a 20 L Henschel mixer at 800 rpm for 10 minutes. Next, PC
After sufficiently kneading with an M30 (extrusion kneader), the mixture was cooled and coarsely pulverized with a 2 mm feather mill. Next, it was finely pulverized by an I-2 type jet mill, and the fine powder was classified by an airflow classifier. Silica (Wicker: HV) is applied to the surface of the finally obtained toner.
K2150) was subjected to 0.9% surface treatment to obtain a positively charged toner.

96.5 parts by weight of a coating carrier,
3.5 parts by weight of the positively charged toner was added to a ball mill at 100 rotations /
For 20 minutes to obtain a sample of a two-component developer.

For this sample, the developer charge was measured. Further, a continuous actual shooting test was performed using FP-7750 (manufactured by Matsushita Electric Transmission System Co., Ltd .: two-component developer type copying machine), and the initial image density, initial charge amount, initial drum fog, and image density at 10 k (1 k Indicates 1000 sheets), 10k charge amount, 10k drum fog in the morning and 1k
The amount of charge per day at 0 k was measured. Table 1 shows the results together with the carrier characteristics.

Here, "initial" means copying when 1 to 10 sheets have been used, and "10k" means 5,000 sheets of 6% original,
Immediately after printing 10,000 sheets of 5,000 sheets of 1% originals. The term "10k morning" refers to the point in time when the copier is turned off after 10,000 sheets have been printed, left overnight, and then turned on the next morning to resume printing. .

The image density was measured using a Macbeth reflection densitometer RD-9.
The measurement was performed using a 14-inch type, a document having an image density of 0.9 was copied, and the image density of the copy was measured and evaluated.

The charge amount was measured by a blow-off powder charge amount measuring device (Model TB-200) manufactured by Toshiba Chemical Corporation.
Using a blow pressure of 0.2 kgf / cm ² and a measurement time of 6
Under the measurement condition of 0 second, the charge amount per 1 g of toner (μC /
g) was measured.

For the drum fog, an adhesive tape was attached to the surface of the drum and peeled off. The toner density on the surface of the adhesive tape was measured in the same manner as the image density, and the drum fog was evaluated based on the measured value.

Further, a two-component developer was evaluated based on the data of 10k charge amount and 10k drama fog. Suitable when the charge amount is 11 μC / g or more and the drum fog is 0.16 or less, and the charge amount is 11 μC / g.
When the value was less than 0.16 and the drum fog exceeded 0.16, it was considered unsuitable. The results are shown in Table 1 with ×. This standard was in accordance with the standard used as an evaluation standard for ordinary two-component developers.

[0055]

[Table 1] The thermogravimetric change rate A is when the first temperature is 100 ° C. and the second temperature is 500 ° C., and the thermogravimetric change rate B is
Shows the rate of change when the temperature is 350 ° C. Where 350
The reason why the temperature is set to ° C is that it is considered that almost the same measurement result can be obtained by measuring at least up to 350 ° C because the inflection point is 350 ° C in the characteristic diagram shown in FIG.

(Example 2) The coating carrier I of Example 2 was manufactured in the same manner as in Example 1 except that the heat treatment temperature during carrier production was changed to 300 ° C and the heat treatment time was changed to 45 minutes.
I was prepared and subjected to thermogravimetry. The results are shown in FIG. 1 and Table 1.

Further, the coating carrier II of Example 2
To prepare a two-component developer in the same manner as in Example 1,
A continuous actual shooting test was performed in the same manner as in the first embodiment. The results are also shown in Table 1.

(Example 3) The coating carrier I of Example 2 was manufactured in the same manner as in Example 1 except that the heat treatment temperature during carrier production was changed to 320 ° C and the heat treatment time was changed to 90 minutes.
II was prepared and subjected to thermogravimetry. The results are shown in FIG. 1 and Table 1.

Further, the coating carrier II of Example 3
Using I, a two-component developer was prepared in the same manner as in Example 1,
A continuous actual shooting test was performed in the same manner as in the first embodiment. The results are also shown in Table 1.

Example 4 Example 1 was repeated except that the heat treatment temperature during carrier production was changed to 320 ° C., the heat treatment time was changed to 90 minutes, and the blending amount of the silicone resin was changed to 75 parts by weight.
In the same manner as in the above, a coating carrier IV of Example 4 was manufactured and subjected to thermogravimetry. FIG. 1 and Table 1 show the results.
It is described together.

The coating carrier IV of Example 4
To prepare a two-component developer in the same manner as in Example 1,
A continuous actual shooting test was performed in the same manner as in the first embodiment. The results are also shown in Table 1.

Comparative Example 1 The procedure of Example 1 was repeated, except that the heat treatment temperature during carrier production was changed to 280 ° C.
A coating carrier V of Comparative Example 1 was manufactured and subjected to thermogravimetry. The results are shown in FIG. 1 and Table 1.

The coating carrier V of Comparative Example 1
To prepare a two-component developer in the same manner as in Example 1,
A continuous actual shooting test was performed in the same manner as in the first embodiment. The results are also shown in Table 1.

Comparative Example 2 A coated carrier VI of Comparative Example 1 was manufactured and subjected to thermogravimetry in the same manner as in Example 1 except that the heat treatment time during the production of the carrier was changed to 30 minutes. The results are shown in FIG. 1 and Table 1.

The coating carrier VI of Comparative Example 2
To prepare a two-component developer in the same manner as in Example 1,
A continuous actual shooting test was performed in the same manner as in the first embodiment. The results are also shown in Table 1.

As is clear from FIG. 1 and Table 1, the rate of change in thermogravimetry in thermogravimetry was 0.015% or less.
In the samples using the coating carriers I to IV of Examples 1 to 4, the value of fog per drum of 10k was small, and the evaluation of the two-component developer was also suitable. Also in the continuous and intermittent actual test using this sample, there was no fogging or toner scattering, and good results were shown.

On the other hand, in the samples using the coating carriers V and VI of Comparative Examples 1 and 2 in which the rate of change in thermogravimetry in thermogravimetry exceeded 0.15, the value of fog per drum of 10 k was large. The evaluation of the two-component developer was also unsuitable. Also in the continuous and intermittent actual test using this sample, fogging and toner scattering occurred, which was an undesirable result.

[0068]

As described above, according to the present invention,
Since the conditions for curing the coating resin when forming the coating layer on the core particle surface are appropriately controlled and the rate of change in thermogravimetry in the thermogravimetry of the coating carrier is within a predetermined standard, toner scattering and fogging occur. Is remarkably suppressed.

[Brief description of the drawings]

FIG. 1 is a characteristic diagram showing the results of Examples and Comparative Examples of the present invention.

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[Procedure amendment]

[Submission date] January 25, 2001 (2001.1.2)
5)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0016

[Correction method] Change

[Correction contents]

[0016]

(Equation 1)

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0027

[Correction method] Change

[Correction contents]

(Wherein R ₄ and R ₅ are a hydroxy group, a carboxyl group, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, an alkenyl group having 2 to 4 carbon atoms, An alkenyloxy group having 2 to 4 atoms, a phenyl group, a phenoxy group, and k, l, m, and n each represent an integer of 1 or more.) In addition to the unsubstituted substituents, for example, an amino group, a hydroxy group, It may have a substituent such as a carboxyl group, a mercapto group, an alkyl group, a phenyl group, an ethylene oxide group, a glycidyl group, and a halogen atom.

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0028

[Correction method] Change

[Correction contents]

For example, as a commercially available straight silicone resin, KR271, KR255, K
R251, KR152, SR2400, SR2410, SR2405 manufactured by Dow Corning Toray Silicone Co., Ltd., and the modified silicone resin is KR20 manufactured by Shin-Etsu Chemical Co., Ltd.
6 ( alkyd modified), KR5208 (acrylic modified), ES1001N (epoxy modified), KR305
(Urethane-modified), SR2115 (epoxy-modified) and SR2110 (alkyd-modified) manufactured by Toray Dow Corning Silicone Co., Ltd.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0031

[Correction method] Change

[Correction contents]

The solvent used for forming the coating layer can be appropriately selected according to the type of the resin used. For example, toluene, ligroin, xylene, methyl ethyl ketone, methyl isobutyl ketone, Serusoru Bed Bed <br/> chill acetate.

[Procedure amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0040

[Correction method] Change

[Correction contents]

[0040] To create made the toner of the present invention, for example, the above-mentioned binder resin, charge control agents, coloring agents and thoroughly mixed by a mixer such as a Henschel mixer, kneaded in a twin-screw extruder, cooled After coarsely pulverizing the mixture with a feather mill or the like, using a jet pulverizer, an air classifier or the like, the particle size is 4 to 20 μm.
(Average particle diameter of 7 μm), and can be obtained by adding an external additive or the like and mixing with a mixer.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Kenkichi Hara 425 Kanai, Shibukawa-shi, Gunma F-term in Kanto Denka Kogyo Co., Ltd. Recording Materials Research Laboratory 2H005 BA02 BA06 CA12 CB04 EA10

Claims (6)

[Claims] 1. A coating carrier comprising core particles and a coating layer for coating the surface of the core particles with a silicone resin, wherein the coating carrier is measured from a first temperature by a thermogravimetric method. 2 and the carrier weight at the first temperature and the second
Is 0 to -0.0.
A coating carrier characterized by 15%. 2. The coated carrier according to claim 1, wherein the first temperature is 100 ° C. and the second temperature is 500 ° C. 3. The first temperature is 100 ° C., the second temperature is 350 ° C., and the weight change rate is −0.005.
The coating carrier according to claim 1, wherein the content is from -0.05%. 4. A core particle, and a coating layer obtained by coating the surface of the core particle with a silicone resin and curing the core resin.
A coating carrier having a heating temperature of 300 to 32 for curing the silicone resin.
A coated carrier which is heat-treated at 0 ° C. and a heating time of 45 to 90 minutes. 5. An electrophotographic developer comprising the coating carrier according to claim 1 and a toner. 6. A step of coating the surface of the core particles with a silicone resin, and applying the silicone resin to the core particles at a heating temperature of 300 to 320 ° C.
Performing a heat treatment for 5 to 90 minutes.