JP2009151189A - Electrostatic charge image developing carrier, electrostatic charge image developer, cartridge, process cartridge, image forming method and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrostatic charge image developing carrier which hardly cause stripping of a cover resin layer and can stably perform image formation over a long time without almost depending on an environment such as temperature and humidity. <P>SOLUTION: The electrostatic charge image developing carrier is a particle provided by forming at least a resin cover layer onto a magnetic particle, wherein the resin cover layer contains a polyester resin obtained from at least polyhydric carboxylic acid and polyhydric alcohol, the polyester resin contains monomer unit represented by the following formula (1) originated from the polyhydric alcohol in an amount of 5 mol% to 50 mol% and the coverage of the resin cover layer to the magnetic particle is 80% or more. In the formula (1), each of R<SP>1</SP>to R<SP>6</SP>presents a substituent independently, each of X and Y presents single bond or bivalent organic group independently, and each of m and n presents an integer of 0 to 4 independently. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an electrostatic charge image developing carrier, an electrostatic charge image developer, a cartridge, a process cartridge, an image forming method, and an image forming apparatus.

A method of visualizing image information through an electrostatic latent image such as electrophotography is currently used in various fields. In electrophotography, an electrostatic latent image is formed on a photoreceptor by charging and exposure processes, the electrostatic latent image is developed with a developer containing toner, and visualized through a transfer and fixing process.
The developer used here includes a two-component developer composed of a toner and a carrier, and a one-component developer used alone, such as a magnetic toner. Among them, the two-component developer has a feature such as good controllability because the carrier shares functions such as stirring, transporting and charging of the developer and is separated as a developer, and is widely used at present. Yes. In particular, a developer using a carrier coated with a resin has excellent charge controllability and is relatively easy to improve environment dependency.

For example, Patent Document 1 describes a carrier for developing an electrostatic charge image, wherein a coating layer made of a polymer containing a cycloalkyl methacrylate as a monomer component is formed on the surface of a carrier core material. Yes.
Patent Document 2 discloses (A) a polyimide resin having a repeating unit containing a diorganosiloxy group: 100 parts by weight (B) a compound containing two or more epoxy groups in one molecule: 0.1 to 70 An electrophotographic carrier coating agent mainly composed of parts by weight, and an electrophotographic carrier obtained by coating and curing the surface of carrier core particles are described.
Further, Patent Document 3 discloses a carrier having a carrier core material and a resin coating layer covering the surface thereof, wherein the resin coating layer is a vinylidene fluoride (VDF) as a monomer unit unit constituting the resin. 2-50 mol%, tetrafluoroethylene (TFE) 2-50 mol% (however, the total amount of VDF and TFE is 15-85 mol%), and a vinyl ether and / or acrylic ester containing a cyclohexyl group A carrier is described which is a curable fluorine-containing resin coating layer containing 1 to 70 mol% of one or more kinds.

JP 59-104664 A JP-A-10-239913 JP 2002-82494 A

  An object of the present invention is to provide an electrostatic charge image developing carrier that is less dependent on the environment such as temperature and humidity, and that the coating resin layer is less likely to be peeled off and can stably form an image over a long period of time. An electrostatic charge image developer, a cartridge, a process cartridge, an image forming method, and an image forming apparatus using an image developing carrier are provided.

The above-described problems of the present invention have been solved by means described in the following <1>, <6> to <10>. It is shown below together with <2> to <5> which are preferred embodiments.
<1> Particles obtained by forming a resin coating layer on magnetic particles, wherein the resin coating layer includes a polyester resin obtained from a polyvalent carboxylic acid and a polyhydric alcohol, and the polyester resin is derived from the polyhydric alcohol described below. A carrier for developing an electrostatic charge image, wherein the carrier unit has a monomer unit represented by the formula (1) in an amount of 5 mol% to 50 mol%, and the coverage of the resin coating layer on the magnetic particles is 80% or more;

（式（１）中、Ｒ¹、Ｒ²、Ｒ³、Ｒ⁴、Ｒ⁵及びＲ⁶はそれぞれ独立に、置換基を表し、Ｘ及びＹはそれぞれ独立に、単結合又は二価の有機基を表し、ｍ及びｎはそれぞれ独立に、０以上４以下の整数を表す。）
＜２＞ 前記樹脂被覆層中に導電粉を含む上記＜１＞記載の静電荷像現像用キャリア、
＜３＞ 前記磁性粒子と前記樹脂被覆層との間に金属酸化物を含有する層を有し、前記磁性粒子の金属主組成分と前記金属酸化物とが異なるものである上記＜１＞又は＜２＞に記載の静電荷像現像用キャリア、
＜４＞ 前記金属酸化物が、前記磁性粒子の金属主組成分より絶縁性が高く、前記磁性粒子における前記金属酸化物の含有割合をａ（％）、前記金属酸化物を含有する層における前記金属酸化物の含有割合をｂ（％）とした時、ｂ≧５０であり、かつ、（ｂ／１０００）＜ａ＜（ｂ／１０）である上記＜３＞に記載の静電荷像現像用キャリア、
＜５＞ 前記金属酸化物が、アルミナを含む上記＜３＞又は＜４＞に記載の静電荷像現像用キャリア、
＜６＞ 上記＜１＞乃至＜５＞のいずれか１つに記載の静電荷像現像用キャリアを含む静電荷像現像剤、
＜７＞ 上記＜１＞乃至＜５＞のいずれか１つに記載の静電荷像現像用キャリア、又は、上記＜６＞に記載の静電荷像現像剤を少なくとも収納したカートリッジ、
＜８＞ 潜像保持体上に形成された静電潜像をトナーを含む上記＜６＞に記載の静電荷像現像剤により現像してトナー像を形成する現像手段と、潜像保持体、前記潜像保持体を帯電させる帯電手段、及び、前記潜像保持体の表面に残存したトナーを除去するクリーニング手段よりなる群から選ばれた少なくとも１種とを備えるプロセスカートリッジ、
＜９＞ 潜像保持体と、前記潜像保持体を帯電させる帯電手段と、帯電した前記潜像保持体を露光して該潜像保持体上に静電潜像を形成させる露光手段と、トナーを含む現像剤により前記静電潜像を現像してトナー像を形成させる現像手段と、前記トナー像を前記潜像保持体から被転写体に転写する転写手段とを有し、前記現像剤が上記＜１＞乃至＜５＞のいずれか１つに記載の静電荷像現像用キャリアを含む画像形成装置、
＜１０＞ 潜像保持体表面に静電潜像を形成する潜像形成工程、前記潜像保持体表面に形成された静電潜像をトナーを含む現像剤により現像してトナー像を形成する現像工程、前記潜像保持体表面に形成されたトナー像を被転写体表面に転写する転写工程、及び、前記被転写体表面に転写されたトナー像を熱定着する定着工程を含み、前記現像剤が上記＜１＞乃至＜５＞のいずれか１つに記載の静電荷像現像用キャリアを含む画像形成方法。

(In the formula (1), R ¹ , R ² , R ³ , R ⁴ , R ⁵ and R ⁶ each independently represents a substituent, and X and Y each independently represent a single bond or a divalent organic group. M and n each independently represent an integer of 0 or more and 4 or less.)
<2> The carrier for developing an electrostatic charge image according to <1>, wherein the resin coating layer contains conductive powder.
<3> The above item <1>, wherein a metal oxide-containing layer is provided between the magnetic particles and the resin coating layer, and the metal main composition of the magnetic particles is different from the metal oxide. <2> The electrostatic charge image developing carrier according to
<4> The metal oxide is higher in insulation than the metal main composition of the magnetic particles, the content ratio of the metal oxide in the magnetic particles is a (%), and the layer in the layer containing the metal oxide. When the content ratio of the metal oxide is b (%), b ≧ 50, and (b / 1000) <a <(b / 10) Career,
<5> The electrostatic image developing carrier according to <3> or <4>, wherein the metal oxide contains alumina,
<6> An electrostatic charge image developer comprising the electrostatic charge image developing carrier according to any one of <1> to <5> above,
<7> The electrostatic charge image developing carrier according to any one of <1> to <5> or a cartridge containing at least the electrostatic charge image developer according to <6>,
<8> A developing unit that develops the electrostatic latent image formed on the latent image holding member with the electrostatic charge image developer according to the above <6> containing toner to form a toner image, a latent image holding member, A process cartridge comprising: charging means for charging the latent image holding body; and at least one selected from the group consisting of cleaning means for removing toner remaining on the surface of the latent image holding body;
<9> A latent image holding member, a charging unit that charges the latent image holding member, an exposure unit that exposes the charged latent image holding member to form an electrostatic latent image on the latent image holding member, A developing unit that develops the electrostatic latent image with a developer containing toner to form a toner image; and a transfer unit that transfers the toner image from the latent image holding member to the transfer target. An image forming apparatus comprising the electrostatic charge image developing carrier according to any one of <1> to <5> above,
<10> A latent image forming step of forming an electrostatic latent image on the surface of the latent image holding member, and developing the electrostatic latent image formed on the surface of the latent image holding member with a developer containing toner to form a toner image. A development step, a transfer step of transferring the toner image formed on the surface of the latent image holding member to the surface of the transfer target, and a fixing step of thermally fixing the toner image transferred to the surface of the transfer target. An image forming method wherein the agent comprises the electrostatic image developing carrier according to any one of the above items <1> to <5>.

  According to the present invention, the electrostatic charge image developing carrier that is less dependent on the environment such as temperature and humidity, is less likely to peel off the coating resin layer, and can stably form an image over a long period of time, and the electrostatic charge An electrostatic charge image developer using an image developing carrier, a cartridge, a process cartridge, an image forming method, and an image forming apparatus can be provided.

  Hereinafter, the present invention will be described in detail.

(Carrier for developing electrostatic image)
The electrostatic charge image developing carrier of the present invention (hereinafter also simply referred to as “carrier”) is a particle in which a resin coating layer is formed on magnetic particles (hereinafter also referred to as “core material”), and the resin coating layer. Includes a polyester resin obtained from a polyvalent carboxylic acid and a polyhydric alcohol, and the polyester resin has a monomer unit represented by the following formula (1) derived from the polyhydric alcohol in an amount of 5 mol% to 50 mol%, The covering ratio of the resin coating layer to the magnetic particles is 80% or more.

（式（１）中、Ｒ¹、Ｒ²、Ｒ³、Ｒ⁴、Ｒ⁵及びＲ⁶はそれぞれ独立に、置換基を表し、Ｘ及びＹはそれぞれ独立に、単結合又は二価の有機基を表し、ｍ及びｎはそれぞれ独立に、０以上４以下の整数を表す。）

(In the formula (1), R ¹ , R ² , R ³ , R ⁴ , R ⁵ and R ⁶ each independently represents a substituent, and X and Y each independently represent a single bond or a divalent organic group. M and n each independently represent an integer of 0 or more and 4 or less.)

  With this configuration, the electrostatic charge image developing carrier of the present invention is less dependent on the environment such as temperature and humidity, and the coating resin layer is less likely to be peeled off. Image formation can be performed stably. The reason is presumed as follows.

In the two-component developer, a charge generated by frictional charging between the toner and the carrier is generated on the toner surface and the carrier surface. Since the toner has high insulating properties, it can retain the generated charge even under high temperature and high humidity conditions. However, the carrier is controlled by semi-conducting resistance for the purpose of improving the image quality. Is likely to leak under high temperature and high humidity. Therefore, not leaking the generated charge does not reduce the charge amount under high temperature and high humidity, that is, reduces the environmental dependency.
The charge leakage under high temperature and high humidity is also considered to be because the coating resin layer on the carrier surface adsorbs moisture in the environment, and the generated charges are discharged in the air through the adsorbed moisture.

Therefore, the present inventors use a polyester resin having a monomer unit represented by the formula (1) in the coating resin layer in an amount of 5 mol% to 50 mol% in order to make it difficult for moisture to be adsorbed on the surface of the coating resin layer. Found it very suitable.
Although the detailed reason is not clear, having a fluorene skeleton increases the ratio of hydrocarbon groups in the resin and increases the hydrophobicity of the resin coating layer, making it difficult to retain moisture in the coating resin layer. In the coating process in which the core material is mixed and desolvated by dissolving the resin for coating the core material in an organic solvent by using a thermoplastic resin, the fluorene skeleton group in the resin is the surface. It is considered that the solvent is removed while being oriented, and the surface of the completed carrier can be fixed in a state where the alicyclic group is oriented, making it difficult to retain atmospheric moisture. The same can be said for the manufacturing method in which the resin is fixed to the core material surface by heating without using a solvent.
Furthermore, since the resin containing the fluorene skeleton itself has high resistance, resistance control when using conductive powder is facilitated, and therefore it is preferable to use conductive powder for the resin coating layer.

On the other hand, when performing image formation over a long period of time, if the developer continues to be stirred in the developing means, there is concern about wear and peeling of the coating resin layer on the carrier surface, and also because of excellent adhesion to magnetic particles. Solved.
[1] A polyester resin having a monomer unit represented by the formula (1) of 5 mol% or more and 50 mol% or less has low curing shrinkage, and stress hardly acts between the carrier core and the coating resin during curing.
[2] Since the 9,9-diphenylfluorene skeleton has a molecular bending (cardo) structure in the three directions shown below, the pseudo-anchor effect works when the fluorene skeleton part of the resin enters the fine recesses on the surface of the magnetic particles. it is conceivable that.

  As shown above, the 9,9-diphenylfluorene skeleton has a cardo structure in which the plane direction of the fluorene skeleton and the plane directions of the two phenyl groups are different from each other. In the two phenyl moieties, the fluorene skeleton and the main chain of the resin are bonded in a para-position, so that the effect of having a cardo structure can be obtained more remarkably.

The said resin coating layer contains at least the polyester resin which has 5 mol% or more and 50 mol% or less of monomer units represented by the said Formula (1).
If it is less than 5 mol%, the effect of the 9,9-diphenylfluorene skeleton cannot be sufficiently obtained, the anchor effect between the resin coating layer and the core particles is reduced, and sufficient heat resistance, resistance and high surface hardness are obtained. -Hydrophobicity may not be obtained.
On the other hand, if it is more than 50 mol%, the resin hardness becomes too high or the wettability to the core material may deteriorate, and the coating resin may be easily peeled off. There is a possibility that image quality defects such as image quality, and image quality defects due to charge reduction after long-term continuous printing may occur.

  From the above, in the carrier of the present invention, since the resin coating layer on the carrier surface contains a resin having a 9,9-diphenylfluorene skeleton of the formula (1), the carrier is hardly affected by the environment, and is not subject to high temperature and high humidity. Therefore, the difference in charge amount between high temperature and high humidity and low temperature and low humidity is small (that is, there is little environmental dependency).

In addition, the coating resin of the present invention suppresses abrasion and peeling of the resin coating layer and can withstand long-term agitation in the developing machine, thereby preventing defects such as white spots and black spots as well as high image quality. Images can be provided stably over a long period of time.
The reason for suppressing abrasion and peeling of the resin coating layer and withstanding long-term stirring in the developing machine is that the resin containing 9,9-diphenylfluorene skeleton has high melt viscosity characteristics and high surface hardness. It is estimated that.

  Further, in a carrier whose resistance is adjusted by containing conductive powder in the resin coating layer, further significant charge leakage occurs, so it is more important to suppress this leakage. Further, when the toner contains a crystalline resin, the generated charge amount of the toner is reduced, so that it is necessary to further suppress charge leakage. Therefore, in such a case, it is particularly effective to use the carrier of the present invention that hardly adsorbs moisture on the surface of the resin coating layer and has little environmental dependency.

In particular, when carbon black or the like is used as the conductive powder in the carrier, if the coating resin layer is peeled off, black carrier resin peeling powder is generated, which is recognized as fogging.
Even when conductive powder is not used, or when transparent or white conductive powder is used, the carrier resin peels off to cause contamination inside the machine, which can contaminate the exposed area and prevent the formation of a fine latent image. The device is contaminated and the photosensitive member cannot be uniformly charged, and white spots and black spots are generated.
Therefore, in such a case, it is particularly effective to use the carrier of the present invention in which the resin coating layer is difficult to peel off.

  Hereinafter, each component constituting the carrier will be described.

(Magnetic particles)
Examples of the magnetic particles (core material) that can be used for the carrier of the present invention are generally magnetic metals, magnetic oxides, or resin particles in which magnetic particles are dispersed internally.
When the above-mentioned magnetic metal, magnetic oxide, or resin particles in which magnetic particles are dispersed internally are used as they are as a carrier, they are hydrophilic and have the disadvantage of lowering the chargeability under high humidity, so that the chargeable environment Due to the large fluctuation and the high surface energy material, there is a problem that the toner component is easily contaminated and the chargeability is poorly maintained.
Therefore, the above-mentioned problems relating to charging can be improved by coating the carrier surface with a resin having hydrophobicity or low surface energy.
On the other hand, when the surface of the core material is coated with an insulating resin at a high coverage, the electrical resistance as a carrier increases, and the reproducibility of a solid image may deteriorate. In this case, more excellent performance can be exhibited by taking measures such as dispersing conductive particles in the coating layer in order to avoid an increase in electrical resistance.

The material of the magnetic particles (core material) that can be used for the carrier of the present invention is not particularly limited as long as the following conditions are satisfied.
Specific examples include magnetic metals such as iron, steel, nickel and cobalt; alloys of these magnetic metals with manganese, chromium and rare earths; and magnetic oxides such as ferrite and magnetite.
In particular, as a core material that can be suitably used in the present invention, ferrite particles can be exemplified because the surface is easily uniformized and the chargeability is stable.

Examples of ferrite in the core material that can be used in the present invention are generally represented by the following formula.
(MO) _X (Fe ₂ O ₃ ) _Y
(Wherein M represents at least one selected from Cu, Zn, Fe, Mg, Mn, Ca, Li, Ti, Ni, Sn, Sr, Al, Ba, Co, Mo, etc., and X and Y represents a molar ratio by weight and satisfies the condition X + Y = 100.)

  The M is preferably a ferrite particle which is one kind or a combination of several kinds of Li, Mg, Ca, Mn, Sr and Sn, and the content of other components is 1% by weight or less. When the metal atom is used, the electrical resistance of the core material is appropriate, the coverage can be easily set to a desired numerical range, and the environment dependency is excellent.

  The core material is formed by granulation and sintering, but is preferably finely pulverized as a pretreatment. The pulverization method is not particularly limited, and pulverization can be performed according to a known pulverization method. Specific examples include a mortar, a ball mill, and a jet mill. Although the final pulverized state in the pretreatment varies depending on the material and the like, the volume average particle size of the core material before granulation and sintering is preferably 2 μm or more and 10 μm or less. Within the above range, the particle size is suitable for use, the desired particle size can be easily obtained, and the circularity has an appropriate value.

The sintering temperature is preferably kept lower than in the conventional case. Specifically, although it varies depending on the material used, it is preferably 500 ° C. or more and 1,200 ° C. or less, and 600 ° C. or more and 1,000 ° C. or less. More preferred. When the sintering temperature is 500 ° C. or higher, sufficient magnetic force required as a carrier is obtained, and when it is 1,200 ° C. or lower, the rate of crystal growth is moderate, the internal structure is uniform, and Particles free from cracks and cracks can be obtained.
In order to keep the sintering temperature low, in the sintering process, it is preferable to perform preliminary sintering stepwise. Therefore, it is preferable to increase the time required for the entire sintering.

  The volume average particle diameter of the core material is preferably 10 μm or more and 500 μm or less, more preferably 20 μm or more and 150 μm or less, and further preferably 30 μm or more and 100 μm or less. When the volume average particle diameter of the core material is 10 μm or more, the adhesion between the toner and the carrier is appropriate when used as an electrostatic charge image developer, and a sufficient amount of toner can be obtained. On the other hand, when the thickness is 500 μm or less, the magnetic brush does not become rough and a fine image is formed.

  As for the magnetic force of the core material, the saturation magnetization at 1,000 oersted is preferably 50 emu / g or more, and more preferably 60 emu / g or more. When the saturation magnetization is 50 emu / g or more, it is possible to prevent the carrier from being developed on the photoreceptor together with the toner.

The apparatus capable of measuring the magnetic properties is not particularly limited, but a vibration sample type magnetic measurement apparatus VSMP10-15 (manufactured by Toei Industry Co., Ltd.) can be preferably used.
For example, the measurement sample is packed in a cell having an inner diameter of 7 mm and a height of 5 mm and set in the apparatus. The measurement applies an applied magnetic field and sweeps up to 1,000 oersted. Next, the applied magnetic field is decreased to create a hysteresis curve on the recording paper. From the curve data, saturation magnetization, residual magnetization, and coercive force can be obtained. In the present invention, saturation magnetization indicates magnetization measured in a 1,000 oersted magnetic field.

The volume electric resistance (volume resistivity) of the core material is preferably in the range of 10 ⁵ Ω · cm to 10 ^9.5 Ω · cm, and preferably in the range of 10 ⁷ Ω · cm to 10 ⁹ Ω · cm. Is more preferable. When the volume electrical resistance is 10 ⁵ Ω · cm or more, when the toner concentration in the developer is reduced by repeated copying, charge injection into the carrier does not occur and development of the carrier itself is suppressed. it can. On the other hand, when the volume electric resistance is 10 ^9.5 Ω · cm or less, the outstanding edge effect and pseudo contour can be suppressed, and the image quality is excellent.

In the present invention, the volume electric resistance (Ω · cm) of the core material is measured as follows. The measurement environment is a temperature of 20 ° C. and a humidity of 50% RH.
The object to be measured is placed flat on the surface of a circular jig having a 20 cm ² electrode plate so as to have a thickness of about 1 mm to 3 mm, thereby forming a layer. A 20 cm ² electrode plate similar to the above is placed on this, and the layers are sandwiched. In order to eliminate gaps between objects to be measured, a thickness (cm) of the layer is measured after a load of 4 kg is applied on the electrode plate placed on the layer. Both electrodes above and below the layer are connected to an electrometer and a high voltage power generator. A high voltage is applied to both electrodes so that the electric field is 10 ^3.8 V / cm, and the current value (A) flowing at this time is read to calculate the volume electrical resistance (Ω · cm) of the measurement object. The calculation formula of the volume electrical resistance (Ω · cm) of the measurement object is as shown in the following formula.
Formula: R = E × 20 / (I−I ₀ ) / L
In the above formula, R is the volume electric resistance (Ω · cm) of the measurement object, E is the applied voltage (V), I is the current value (A), I ₀ is the current value (A) at the applied voltage of 0 V, and L is Each layer thickness (cm) is expressed. A coefficient of 20 represents the area (cm ² ) of the electrode plate.

  The volume average particle diameter d of the core material can be measured using a laser diffraction / scattering type particle size distribution measuring device (LS Particle Size Analyzer: LS13 320, manufactured by Beckman Coulter, Inc.). For the particle size range (channel) obtained by dividing the obtained particle size distribution, the volume cumulative distribution is subtracted from the small particle size side, and the particle size at 50% accumulation is defined as the volume average particle size d.

Moreover, true specific gravity (rho) of a core material measures a true specific gravity based on 5-2-1 of JIS-K-0061 using a Le Chatelier specific gravity bottle. The operation is as follows.
(1) About 250 ml of ethyl alcohol is put into a Lechatelier specific gravity bottle and adjusted so that the meniscus is at the position of the scale.
(2) The specific gravity bottle is immersed in a constant temperature water bath, and when the liquid temperature reaches 20.0 ± 0.2 ° C., the position of the meniscus is accurately read with the scale of the specific gravity bottle. (Accuracy 0.025ml)
(3) About 100 g of a sample is weighed and its mass is defined as W (g).
(4) Put the weighed sample in a specific gravity bottle to remove bubbles.
(5) The specific gravity bottle is immersed in a constant temperature water bath, and when the liquid temperature becomes 20.0 ± 0.2 ° C., the position of the meniscus is accurately read with the scale of the specific gravity bottle. (Accuracy 0.025ml)
(6) The true specific gravity is calculated by the following formula.
D = W / (L2-L1)
ρ = D / 0.9982
In the above formula, D is the density of the sample (20 ° C.) (g / cm ³ ), ρ is the true specific gravity of the sample (20 ° C.), W is the apparent mass (g) of the sample, and L1 is the sample in a specific gravity bottle. The previous meniscus reading (20 ° C.) (ml), L2 is the meniscus reading after placing the sample in the density bottle (20 ° C.) (ml), 0.9982 is the density of water at 20 ° C. (g / cm ³ ).

<Coating resin layer>
The coating resin layer used for the carrier of the present invention contains at least a polyester resin obtained from a polyvalent carboxylic acid and a polyhydric alcohol, and the polyester resin is a monomer represented by the following formula (1) derived from the polyhydric alcohol. The unit has 5 mol% or more and 50 mol% or less, and the coating ratio of the resin coating layer to the magnetic particles is 80% or more.

（式（１）中、Ｒ¹、Ｒ²、Ｒ³、Ｒ⁴、Ｒ⁵及びＲ⁶はそれぞれ独立に、置換基を表し、Ｘ及びＹはそれぞれ独立に、単結合又は二価の有機基を表し、ｍ及びｎはそれぞれ独立に、０以上４以下の整数を表す。）

(In the formula (1), R ¹ , R ² , R ³ , R ⁴ , R ⁵ and R ⁶ each independently represents a substituent, and X and Y each independently represent a single bond or a divalent organic group. M and n each independently represent an integer of 0 or more and 4 or less.)

The polyester resin (hereinafter also referred to as “specific polyester resin”) contained in the resin coating layer has a monomer unit represented by the formula (1) derived from the polyhydric alcohol in an amount of 5 mol% to 50 mol%. If it does, there will be no restriction | limiting in particular and it can select suitably according to the objective. The specific polyester resin is preferably a thermoplastic resin.
In addition, the monomer unit in a polyester resin means each unit cut | disconnected between the carbonyl part and the alkoxy part in all the ester bonds in a polyester resin.

  Examples of the polyhydric alcohol forming the monomer unit represented by the formula (1) include compounds represented by the following formula (2).

In the formula (2), R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , X, Y, m and n are R ¹ , R ² , R ³ , R ⁴ in the formula (1). , R ⁵ , R ⁶ , X, Y, m, and n, and the preferred range is also the same.
Preferred examples of the compound represented by the formula (2) include bisphenol fluorene (BPF), biscresol fluorene (BCF), and bisphenoxyethanol fluorene (BPEF) shown below.

  Among them, BPEF is particularly preferable from the viewpoint of reactivity and thermal characteristics.

  In addition to the monomer unit represented by the formula (1), the specific polyester may include a monomer unit as shown in the following formula (A) or formula (B), for example. Moreover, it is preferable that the terminal of the said specific polyester is -COOR or -OH. R represents a hydrogen atom, a monovalent or higher-valent metal atom, or a lower alkyl group.

In the formula (A), A ¹ is a polyvalent carboxylic acid residue, represents a divalent or higher organic group, and m represents an integer of 0 or higher. Moreover, a wavy line represents the binding site with other monomer units or the binding site with RO at the resin end. R represents a hydrogen atom, a monovalent or higher-valent metal atom, or a lower alkyl group.
In formula (B), A ² is a polyhydric alcohol residue, represents a divalent or higher organic group, and n represents an integer of 0 or higher. Moreover, a wavy line represents a bonding site with another monomer unit or a bonding site with a hydrogen atom at a resin terminal.
A ¹ is preferably a group obtained by removing two or more hydrogen atoms from a hydrocarbon selected from the group consisting of aliphatic hydrocarbons, aromatic hydrocarbons, and hydrocarbons obtained by combining two or more thereof.
A ² represents an aliphatic hydrocarbon, an aromatic hydrocarbon, and a hydrocarbon selected from the group consisting of an aliphatic hydrocarbon, an aromatic hydrocarbon and / or a hydrocarbon or ether compound in which two or more ether bonds are combined. Alternatively, a group obtained by removing two or more hydrogen atoms from an ether compound is preferable.
The m is preferably an integer of 0 or more and 3 or less, and more preferably 0 or 1.
The n is preferably an integer of 0 or more and 3 or less, and more preferably 0 or 1.
Each monomer unit represented by the formula (A) may be used alone or in combination of two or more in the specific polyester. Moreover, even if it does not have in the monomer unit specific polyester represented by Formula (B), you may have individually by 1 type and may have 2 or more types.

  There are no particular limitations on the polyvalent carboxylic acid and polyhydric alcohol other than the compound represented by the formula (2) that can be used in the production of the specific polyester resin, and a known monomer can be used. .

The polyvalent carboxylic acid is a compound containing two or more carboxyl groups in one molecule.
It does not specifically limit as polyvalent carboxylic acid, A well-known thing can be used. Among these, the following monomers can be preferably exemplified.
Among these, dicarboxylic acid is a compound containing two carboxyl groups in one molecule, and oxalic acid, succinic acid, fumaric acid, maleic acid, adipic acid, β-methyladipic acid, malic acid, malonic acid, pimelic acid , Tartaric acid, azelaic acid, pimelic acid, sebacic acid, nonanedicarboxylic acid, decanedicarboxylic acid, undecanedicarboxylic acid, dodecanedicarboxylic acid, citraconic acid, cyclohexane-3,5-diene-1,2-carboxylic acid, hexahydroterephthalic acid , Mucic acid, phthalic acid, isophthalic acid, terephthalic acid, tetrachlorophthalic acid, chlorophthalic acid, nitrophthalic acid, p-carboxyphenylacetic acid, p-phenylene dipropionic acid, m-phenylene dipropionic acid, m-phenylene Acetic acid, p-phenylenediacetic acid, o-phenylenediacetic acid , Diphenyldiacetic acid, diphenyl-p, p′-dicarboxylic acid, 1,1-cyclopentenedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 1,2 -Cyclohexene dicarboxylic acid, norbornene-2,3-dicarboxylic acid, 1,3-adamantane dicarboxylic acid, 1,3-adamantane diacetic acid, naphthalene-1,4-dicarboxylic acid, naphthalene-1,5-dicarboxylic acid, naphthalene- Examples include 2,6-dicarboxylic acid and anthracene dicarboxylic acid.
Examples of the polyvalent carboxylic acid other than dicarboxylic acid include trimellitic acid, pyromellitic acid, naphthalenetricarboxylic acid, naphthalenetetracarboxylic acid, pyrenetricarboxylic acid, pyrenetetracarboxylic acid, and citric acid.
The carboxylic acid may have a functional group other than a carboxyl group, and carboxylic acid derivatives such as acid halides, acid anhydrides, and ester compounds may be used. The ester compound is preferably a lower ester compound.
These may be used alone or in combination of two or more.
In addition, a lower ester shows that carbon number of the alkoxy part of ester is 1-8. Specific examples include methyl ester, ethyl ester, n-propyl ester, isopropyl ester, n-butyl ester, and isobutyl ester.
Among these, terephthalic acid, cyclohexanedicarboxylic acid, and trimellitic acid can be particularly preferably exemplified as the polyvalent carboxylic acid.

A polyhydric alcohol is a compound containing two or more hydroxyl groups in one molecule.
The polyhydric alcohol is not particularly limited, and known ones can be used. Among these, the following monomers can be preferably exemplified.
Diol is a compound containing two hydroxyl groups in one molecule. Propanediol, butanediol, pentanediol, hexanediol, heptanediol, octanediol, nonanediol, decanediol, dodecanediol, tetradecanediol, octadecanediol, cyclohexane Diol, cyclohexanedimethanol, bisphenol A, bisphenol C, bisphenol E, bisphenol F, bisphenol P, bisphenol S, bisphenol Z, hydrogenated bisphenol, biphenol, naphthalenediol, 1,3-adamantanediol, 1,3-adamantane dimethanol 1,3-adamantanediethanol and the like.
Examples of polyhydric alcohols other than diols include glycol, pentaerythritol, hexamethylol melamine, hexaethylol melamine, tetramethylol benzoguanamine, and tetraethylol benzoguanamine.
In the present invention, the bisphenols preferably have at least one alkylene oxide group. Examples of the alkylene oxide group include, but are not limited to, an ethylene oxide group, a propylene oxide group, and butylene oxide. Preferred are ethylene oxide and propylene oxide. The added mole number is preferably 2 mol or more and 6 mol or less with respect to 1 mol of the hydroxyl group.
Among the above-mentioned monomers, hexanediol, cyclohexanediol, octanediol, decanediol, dodecanediol, and bisphenol A, bisphenol C, bisphenol E, bisphenol S, bisphenol Z are preferably used. These are alkylene oxide adducts.
Moreover, it is preferable that the polyhydric alcohol component used for preparation of the specific polyester is only the compound represented by the formula (2).

In addition to the specific polyester resin, the resin coating layer in the present invention may include other polyester resins, polycondensation resins other than polyester resins, and addition polymerization resins.
As other polyester resin, what consists of the said polyhydric carboxylic acid, the said polyhydric alcohol, well-known hydroxy carboxylic acid, etc. can be illustrated.
Examples of the polycondensation resin other than the polyester resin include polyamide.
The addition polymerization resin is not particularly limited as long as it is a thermoplastic resin, and a known radical polymerization resin, cationic polymerization resin, or anion polymerization resin can be used.

  As the radical polymerization type resin, the smaller the firing residue during firing, the better. However, the radical polymerization resin is not particularly limited, and examples thereof include a thermoplastic resin. Specifically, homopolymers or copolymers of styrenes such as styrene, parachlorostyrene, α-methylstyrene (styrene resin); methyl acrylate, ethyl acrylate, n-propyl acrylate, n-acrylate -Homopolymers or copolymers of esters having vinyl groups such as butyl, lauryl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, lauryl methacrylate, 2-ethylhexyl methacrylate, etc. Polymer (vinyl resin); homopolymer or copolymer of vinyl nitriles such as acrylonitrile and methacrylonitrile (vinyl resin); vinyl ether homopolymer or copolymer such as vinyl ethyl ether and vinyl isobutyl ether ( Vinyl resin); vinyl methyl ketone, vinyl Homopolymers or copolymers of ethyl ketone and vinyl isopropenyl ketones (vinyl resins); Homopolymers or copolymers of olefins such as ethylene, propylene, butadiene, isoprene (olefin resins); epoxy resins, polyesters Examples thereof include non-vinyl condensation resins such as resins, polyurethane resins, polyamide resins, cellulose resins, and polyether resins, and graft polymers of these non-vinyl condensation resins and vinyl monomers. These resins may be used alone or in combination of two or more.

The resin can be produced by radical polymerization of the polymerizable monomer.
There is no restriction | limiting in particular as an initiator for radical polymerization used here. Specifically, for example, hydrogen peroxide, acetyl peroxide, cumyl peroxide, tert-butyl peroxide, propionyl peroxide, benzoyl peroxide, chlorobenzoyl peroxide, dichlorobenzoyl peroxide, bromomethylbenzoyl peroxide, Lauroyl oxide, ammonium persulfate, sodium persulfate, potassium persulfate, diisopropyl peroxycarbonate, tetralin hydroperoxide, 1-phenyl-2-methylpropyl-1-hydroperoxide, pertriphenylacetic acid tert-butyl hydroperoxide, formic acid tert- Peroxides such as butyl, tert-butyl peracetate, tert-butyl perbenzoate, tert-butyl perphenyl acetate, tert-butyl permethoxyacetate, tert-butyl per-N- (3-toluyl) carbamate; 2 , 2'-azo Bispropane, 2,2′-dichloro-2,2′-azobispropane, 1,1′-azo (methylethyl) diacetate, 2,2′-azobis (2-amidinopropane) hydrochloride, 2,2 '-Azobis (2-amidinopropane) nitrate, 2,2'-azobisisobutane, 2,2'-azobisisobutyramide, 2,2'-azobisisobutyronitrile, 2,2'-azobis-2 -Methyl methyl propionate, 2,2'-dichloro-2,2'-azobisbutane, 2,2'-azobis-2-methylbutyronitrile, dimethyl 2,2'-azobisisobutyrate, 1,1'-azobis ( 1-methylbutyronitrile-3-sodium sulfonate), 2- (4-methylphenylazo) -2-methylmalonodinitrile, 4,4′-azobis-4-cyanovaleric acid, 3,5-dihydroxymethyl Enylazo-2-methylmalonodinitrile, 2- (4-bromophenylazo) -2-allylmalonodinitrile, 2,2′-azobis-2-methylvaleronitrile, 4,4′-azobis-4-cyano Dimethyl herbate, 2,2′-azobis-2,4-dimethylvaleronitrile, 1,1′-azobiscyclohexanenitrile, 2,2′-azobis-2-propylbutyronitrile, 1,1′-azobis-1 -Chlorophenylethane, 1,1'-azobis-1-cyclohexanecarbonitrile, 1,1'-azobis-1-cycloheptanenitrile, 1,1'-azobis-1-phenylethane, 1,1'-azobiscumene, 4-nitrophenylazobenzylcyanoacetate ethyl, phenylazodiphenylmethane, phenylazotriphenylmethane, 4-nitrophenyla Triphenylmethane, 1,1′-azobis-1,2-diphenylethane, poly (bisphenol A-4,4′-azobis-4-cyanopentanoate), poly (tetraethylene glycol-2,2′-azo Azo compounds such as bisisobutyrate; 1,4-bis (pentaethylene) -2-tetrazene, 1,4-dimethoxycarbonyl-1,4-diphenyl-2-tetrazene and the like.

  The molecular weight of the resin can be adjusted using a chain transfer agent. The chain transfer agent is not particularly limited, and specifically has a covalent bond between a carbon atom and a sulfur atom, and more specifically, n-propyl mercaptan, n-butyl mercaptan, n-amyl. N-alkyl mercaptans such as mercaptan, n-hexyl mercaptan, n-heptyl mercaptan, n-octyl mercaptan, n-nonyl mercaptan, n-decyl mercaptan; isopropyl mercaptan, isobutyl mercaptan, s-butyl mercaptan, tert-butyl mercaptan, Chain-chain alkyl mercaptans such as cyclohexyl mercaptan, tert-hexadecyl mercaptan, tert-lauryl mercaptan, tert-nonyl mercaptan, tert-octyl mercaptan, tert-tetradecyl mercaptan S; allyl mercaptan, 3-phenylpropyl mercaptan, phenyl mercaptan, mercaptans 含芳 incense ring system such as mercapto triphenylmethane; and the like.

  Specific examples of resins that can be used for the resin coating layer include polyethylene, polypropylene, polystyrene, polyacrylonitrile, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polyvinyl carbazole, polyvinyl ether, polyvinyl ketone, and vinyl chloride-acetic acid. Vinyl copolymer, styrene-acrylic acid copolymer, straight silicone resin composed of organosiloxane bond or modified product thereof, fluorine resin, polyester, polyurethane, polycarbonate, phenol resin, amino resin, melamine resin, benzoguanamine resin, urea resin, Preferred examples include amide resins and epoxy resins, but are not limited thereto. Particularly preferred are polystyrene resin, acrylic acid resin, and styrene-acrylic copolymer. When these resins are used, the coating film strength is high, and the conductive powder and the charge control agent described later can be dispersed.

  Moreover, as a monomer (monomer) used for preparation of the addition polymerization type resin, conventionally used monomers, specifically, dimethylaminoethyl methacrylate, dimethylamino methacrylate, dimethylaminomethyl methacrylate, diethylaminomethyl methacrylate are used. , Dimethylacrylamide, isopropylacrylamide, acryloylmorpholine and other amino group-containing acrylic monomers including nitrogen-containing acrylic monomers; other acrylic monomers; monomers constituting olefin resins such as polyethylene and polypropylene; polystyrene Polyvinyl resins such as resin, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polyvinyl carbazole, polyvinyl ether and polyvinyl ketone And a monomer constituting a polyvinylidene resin; a monomer constituting a straight silicone resin comprising an organosiloxane bond or a modified product thereof; a fluorine resin such as polytetrafluoroethylene, polyvinyl fluoride, polyvinylidene fluoride, and polychlorotrifluoroethylene Monomers constituting amino resins such as polyurethane resins, phenol resins, urea-formaldehyde resins (urea resins), melamine resins, benzoguanamine resins, polyamide resins; monomers constituting epoxy resins; The monomer which comprises this resin can be illustrated preferably.

Among these, as a resin component other than the specific polyester resin, it is preferable to use a (meth) acrylic resin, and it is more preferable to use a methacrylic resin.
As the monomer used for the production of the methacrylic resin, it is preferable to use at least one monomer selected from the group consisting of methyl methacrylate, dimethylaminoethyl methacrylate, and perfluorooctylethyl methacrylate.

The coating resin layer may contain conductive powder as needed for the purpose of controlling resistance.
Specific examples of the conductive powder include metal particles such as gold, silver and copper; carbon black; ketjen black; acetylene black; semiconductive oxide particles such as titanium oxide and zinc oxide; titanium oxide, zinc oxide and sulfuric acid. And particles having a surface of barium, aluminum borate, potassium titanate powder or the like covered with tin oxide, carbon black, metal, or the like.
These may be used individually by 1 type and may use 2 or more types together.

As the conductive powder, carbon black particles are preferable in terms of good production stability, cost, conductivity and the like.
The type of carbon black is not particularly limited, but carbon black having a dibutyl phthalate (DBP) oil absorption of 50 ml / 100 g or more and 250 ml / 100 g or less is preferable because of excellent production stability.

  The conductive powder preferably has a volume average particle size of 0.5 μm or less, more preferably 0.05 μm or more and 0.5 μm or less, and even more preferably 0.05 μm or more and 0.35 μm or less. When the volume average particle diameter is 0.5 μm or less, the conductive powder is less likely to fall off from the coating resin layer, and stable chargeability is obtained.

The volume average particle size of the conductive powder is measured using a laser diffraction particle size distribution analyzer (LA-700: manufactured by Horiba, Ltd.).
As a measurement method, 2 g of a measurement sample is added to a surfactant, preferably 50 ml of a 5% aqueous solution of sodium alkylbenzenesulfonate, and dispersed for 2 minutes with an ultrasonic disperser (1,000 Hz) to prepare a sample. taking measurement.
The obtained volume average particle diameter for each channel is accumulated from the smaller volume average particle diameter, and the volume average particle diameter is defined as 50%.
The volume electric resistance of the conductive powder is preferably 10 ¹ Ω · cm to 10 ¹¹ Ω · cm, and more preferably 10 ³ Ω · cm to 10 ⁹ Ω · cm.
The volume electrical resistance of the conductive powder is measured in the same manner as the volume electrical resistance of the core material.

  The content of the conductive powder is preferably 1% by volume or more and 50% by volume or less, and more preferably 3% by volume or more and 20% by volume or less with respect to the entire coating resin layer. When the content is 50% by volume or less, carrier resistance does not decrease, and image loss due to carrier adhesion to a developed image can be suppressed. On the other hand, if the content is 1% by volume or more, the electrical resistance of the carrier is an appropriate value, and the carrier works sufficiently as a developing electrode during development, and suppresses the edge effect particularly when a black solid image is formed. Excellent reproducibility of solid images.

In addition, the coating resin layer may contain resin particles.
Examples of the resin particles include thermoplastic resin particles and thermosetting resin particles. Among these, thermosetting resins are preferable from the viewpoint of relatively easily increasing the hardness, and resin particles made of nitrogen-containing resin containing N atoms are preferable from the viewpoint of imparting negative chargeability to the toner. In addition, these resin particles may be used individually by 1 type, and may use 2 or more types together.
The volume average particle diameter of the resin particles is preferably from 0.1 μm to 2.0 μm, and more preferably from 0.2 μm to 1.0 μm. When the average particle size of the resin particles is 0.1 μm or more, the dispersibility of the resin particles in the coating resin layer is excellent. On the other hand, when the thickness is 2.0 μm or less, the resin particles hardly fall off from the coating resin layer, and the original effect can be sufficiently exhibited.
The volume average particle diameter of the resin particles can be obtained by performing the same measurement as the volume average particle diameter of the conductive powder.
The content of the resin particles is preferably 1% by weight to 50% by weight, more preferably 1% by weight to 30% by weight, and more preferably 1% by weight to 20% by weight with respect to the entire coating resin layer. More preferably, it is as follows. When the content of the resin particles is 1% by weight or more, the effect of the resin particles is sufficiently obtained, and when the content is 50% by weight or less, the resin resin hardly falls off from the coating resin layer, and stable chargeability is obtained.

The method for forming the coating resin layer on the surface of the core is not particularly limited. For example, a method using a film forming liquid containing conductive powder and an alicyclic group-containing acrylic resin or polycarbonate resin in a solvent. Etc.
For example, an immersion method in which the core material is immersed in the film forming liquid, a spray method in which the film forming liquid is sprayed on the surface of the core material, and the solvent is mixed with the film forming liquid while the core material is suspended by flowing air. The kneader coater method to remove is mentioned. Among these, the kneader coater method is preferable in the present invention.

  The solvent used for the film forming liquid is not particularly limited as long as it can dissolve only the resin, and can be selected from known solvents. Specific examples include aromatic hydrocarbons such as toluene and xylene; ketones such as acetone and methyl ethyl ketone; ethers such as tetrahydrofuran and dioxane;

When resin particles are dispersed in the coating resin layer, since the resin particles are uniformly dispersed in the thickness direction and the tangential direction of the carrier surface, the coating resin layer is worn out by using the carrier for a long period of time. However, it is possible to always maintain the same surface formation as when it is not used, and to maintain a good charge imparting ability for the toner over a long period of time.
In the case where conductive powder is dispersed in the coating resin layer, the conductive powder is uniformly dispersed in the thickness direction and the tangential direction of the carrier surface. Even if it is worn, it is possible to always maintain the same surface formation as when not in use, and to prevent carrier deterioration for a long time.
In the case where resin particles and conductive powder are dispersed in the coating resin layer, the above-described effects can be achieved at the same time.
Further, the coating resin layer is not limited to a single layer, and may be composed of two or more layers.

  The total content of the coating resin layer in the carrier of the present invention is preferably in the range of 0.5 to 10 parts by weight, more preferably 1 to 5 parts by weight, with respect to 100 parts by weight of the core material. 1 to 3 parts by weight is more preferable. When the content of the coating resin layer is 0.5 parts by weight or more, the surface exposure of the core particles is small, and injection of the development electric field can be suppressed. Further, when the content of the coating resin layer is 10 parts by weight or less, the resin powder released from the coating resin layer is small, and the resin powder peeled off in the developer can be suppressed from the initial stage.

The coverage of the core material surface by the coating resin layer is preferably 80% or more, more preferably 85% or more, and the closer to 100%, the more preferable. When the coverage is less than 80%, charge injection into the carrier occurs when it is used for a long period of time, and the carrier in which the charge injection has occurred migrates to the photoconductor, causing white spots on the image. May end up.
In addition, the coverage of a coating resin layer can be calculated | required by XPS measurement. As the XPS measurement device, JPS80 manufactured by JEOL Ltd. was used, and the measurement was performed using MgKα ray as the X-ray source, setting the acceleration voltage to 10 kV, and the emission current to 20 mV. Measure the main constituent elements (usually carbon) and the main constituent elements of the core (for example, iron and oxygen when the core is an iron oxide-based material such as magnetite). The explanation is based on the assumption that the system is a system). Here, the C1s spectrum is measured for carbon, the Fe2p _3/2 spectrum is measured for iron, and the O1s spectrum is measured for oxygen.

Based on the spectrum of each of these elements, the number of elements of carbon, oxygen, and iron (A _C + A _O + A _Fe ) is obtained, and the following formula (9) is obtained from the obtained number ratio of carbon, oxygen, and iron. Based on this, the iron content rate after coating the core material alone and the core material with the coating resin layer (carrier) was determined, and then the coverage rate was determined by the following formula (10).
Formula (9): Iron content rate (atomic%) = A _Fe / (A _C + A _O + A _Fe ) × 100
Formula (10): Coverage rate (%) = {1− (iron content rate of carrier) / (iron content rate of core material alone)} × 100
In addition, when using materials other than iron oxide as a core material, the spectrum of the metal element which comprises a core material besides oxygen is measured, and it is the same according to the above-mentioned formula (9) and formula (10). If the above calculation is performed, the coverage can be obtained.

  The average film thickness of each coating resin layer is preferably 0.1 μm or more and 10 μm or less, more preferably 0.1 μm or more and 3.0 μm or less, and further preferably 0.1 μm or more and 1.0 μm or less. preferable. When the average film thickness of the coating resin layer is 0.1 μm or more, resistance reduction due to peeling of the coating resin layer does not occur during long-time use, and carrier pulverization can be easily controlled. On the other hand, when the average film thickness of the coating resin layer is 10 μm or less, the time until the saturation charge amount is reached is short.

The average film thickness (μm) of the coating resin layer is such that the true specific gravity of the core material is ρ (dimensionless), the volume average particle diameter of the core material is d (μm), the average specific gravity of the coating resin layer is ρ _C , and the core material 100 When the total content of the coating resin layer with respect to parts by weight is W _C (parts by weight), it can be obtained as in the following formula (11).
Formula (11): Average film thickness (μm) = {[amount of coating resin per carrier (including all additives such as conductive powder) / surface area per carrier]} / average specific gravity of coating resin layer
= {[4 / 3π · (d / 2) ³ · ρ · W _C ] / [4π · (d / 2) ² ]} / ρ _C
= (1/6) · (d · ρ · W _C / ρ _C )

The resin coating layer may contain a wax.
Waxes are hydrophobic, are relatively soft at room temperature, and have low film strength. This is due to the molecular structure of the wax. Because of this property, when wax is present in the carrier coating layer, toner components such as fine particles called external additives added to the toner surface or toner bulk components are transferred to the carrier. Hard to adhere to the surface. Even if it adheres, there is an effect that the surface of the carrier is renewed due to the peeling of the adhered part at the wax molecule level, and the carrier surface is hardly adhered and contaminated.

  The wax is not particularly limited, and examples thereof include paraffin wax and derivatives thereof, montan wax and derivatives thereof, microcrystalline wax and derivatives thereof, Fischer-Tropsch wax and derivatives thereof, and polyolefin wax and derivatives thereof. Derivatives include oxides, polymers with vinyl monomers, and graft modified products. In addition, alcohols, fatty acids, plant waxes, animal waxes, mineral waxes, ester waxes, acid amides, and the like can be used. Other known materials can also be used. The melting point of the wax is preferably 60 ° C. or higher and 200 ° C. or lower. More preferably, the melting point of the wax is 80 ° C. or higher and 150 ° C. or lower. It is excellent in the fluidity | liquidity as a carrier in it being 60 degreeC or more.

The resin coating layer in the carrier of the present invention may contain a charge control agent. The charge control agent is preferably used in combination with conductive powder.
Charge control agents include, for example, nigrosine dyes, benzimidazole compounds, quaternary ammonium salt compounds, alkoxylated amines, alkylamides, molybdate chelate pigments, triphenylmethane compounds, salicylic acid metal salt complexes, azo chromium complexes, copper Any known material such as phthalocyanine may be used. Particularly preferred are quaternary ammonium salt compounds, alkoxylated amines and alkylamides.
These charge control agents are easy to control the dispersion state and have good adhesion to the coating resin interface, so that detachment of the charge control agent from the resin coating layer can be suppressed. Further, the charge control agent acts as a dispersion aid for the conductive powder, the dispersion state of the conductive powder in the resin coating layer is made uniform, and the carrier resistance change can be suppressed even if the coat layer is slightly peeled off. The reason is that the surface of the conductive powder is easily oxidized or affected by moisture, so that the conductive powder has high hydrophilicity and tends to aggregate due to water on the particle surface. When this is dispersed in the coating resin, since the polarity of the resin is generally low, the agglomeration described above remains as it is, so that uneven distribution tends to occur inside the coating resin. On the other hand, the above-mentioned charge control agent has good adhesion to the coating resin interface, and also has a high degree of polarity. Presumed.

  The addition amount of the charge control agent is preferably 0.001 part by weight or more and 5 parts by weight or less, more preferably 0.01 part by weight or more and 0.5 part by weight or less when the core material is 100 parts by weight. . Within the above range, the strength of the resin coating layer is sufficient, a carrier that does not easily deteriorate due to stress during use is obtained, and the dispersibility of the conductive material is excellent.

(Layer containing metal oxide)
The electrostatic image developing carrier of the present invention preferably has a layer containing a metal oxide (hereinafter also referred to as “metal oxide-containing layer”) between the magnetic particles and the resin coating layer. .
The metal main composition of the magnetic particles is preferably different from the metal oxide.
In the layer containing the metal oxide, the metal oxide preferably has an electric resistance higher than that of the main metal composition of the magnetic particles.
The metal oxide may be a ferrite composition generally represented by the following formula, or may be a single metal oxide.
(MO) _X (Fe ₂ O ₃ ) _Y
(In the formula, M is Cu, Zn, Fe, Mg, Mn, Ca, Li, Ti, Ni, Sn, Sr,
It represents at least one selected from Al, Ba, Co, Mo and the like, and X and Y indicate a weight molar ratio and satisfy the condition X + Y = 100. )

  The metal oxide is particularly preferably alumina from the viewpoint of electrical resistance and strength.

  The average particle diameter of the metal oxide particles is preferably 1 μm or less, more preferably 0.5 μm or less, and further preferably 0.01 μm or more and 0.5 μm or less.

  By adjusting the average particle size within the above range, it is possible to improve the agglomeration of the adhered particles to the agglomerated particles, and to suppress the uneven distribution of the composition between the particles, and to suppress variations in carrier performance and reliability. There is an advantage that can be.

The metal oxide particles are added in the adhering step, and the addition amount can be adjusted by the core particle surface coverage, but it is preferable to cover 50% or more, and to cover 70% or more and 90% or less. Is more preferable. When the coverage is 50% or more, charge injection can be suppressed when the resin coating layer is peeled off. Moreover, the content rate of a metal oxide can be measured using X-ray microanalyzer EPMA-1610 (made by Shimadzu Corporation). It is preferable that many metal oxide particles are present on the surface of the core material, and it is preferable that the ratio when the cross-section is analyzed after the surface of the core material and the carrier are cut with a microtome is in the range of the following formula.
That is, when the content ratio of the metal oxide in the magnetic particles is a (%) and the content ratio of the metal oxide in the layer containing the metal oxide is b (%),
b ≧ 50, and
It is preferable that (b / 1000) <a <(b / 10).
Within the above range, the core has an appropriate electrical resistance and can be easily melted during firing.

  Although it does not specifically limit as a manufacturing method of the carrier of this invention, It demonstrates in detail with the suitable manufacturing method below.

  As a typical example, a general method for producing a ferrite core material is to mix an appropriate amount of each oxide, add water, and wet ball mill or wet vibration mill, etc., preferably 1 hour or more, more preferably 1 hour or more and 20 hours. Then pulverize and mix. The slurry thus obtained is dried and further pulverized and then calcined at a temperature of 700 ° C. or more and 1,200 ° C. or less. A method of carrying out the main firing after preliminary calcination, further pulverizing to 1 μm or less with a wet ball mill or wet vibration mill, etc., granulating and holding at a temperature of 1,000 ° C. to 1,500 ° C. for 1 hour to 24 hours. Can be illustrated.

  In the present invention, a resin particle dispersion containing a binder resin is produced by granulation by emulsion polymerization or other methods by a known method, heteroaggregated with the dispersion of the core material composition, and then fused and united. The carrier of the present invention is preferably produced by an emulsion polymerization aggregation method.

As an emulsion polymerization aggregation method that can be used in the present invention, a step of mixing a resin particle dispersion in which binder resin particles having a particle size of 1 μm or less are dispersed and a dispersion in which a core material composition is dispersed (hereinafter referred to as a dispersion method) , Also referred to as “dispersing step”), a step of aggregating resin particles, a core material composition or the like to a target particle size (hereinafter also referred to as “aggregation step”), and a metal oxide other than the main component of the core material. A step of forming a layer to be contained (hereinafter also referred to as “attachment step”), a step of heating to a temperature equal to or higher than the glass transition point of the resin particles to fuse the aggregates to form particles (hereinafter also referred to as “fusion step”). .). Moreover, when not providing the layer containing a metal oxide, it is preferable that it is the method of removing the adhesion process from the said method.
Hereinafter, the emulsion polymerization aggregation method will be described as an example.

  In the aggregation step, the particles of the resin particle dispersion and the core composition dispersion mixed in the dispersion step are aggregated to form aggregated particles. The agglomerated particles are formed by heteroaggregation or the like. Generally, an ionic surfactant having a polarity different from that of the agglomerated particles, a pH adjuster, a compound having a monovalent or higher charge such as a metal salt is added and necessary. Accordingly, the temperature is increased while controlling the pH, and the particles are aggregated to the target particle size.

  In the aggregation step, when the core material composition is aggregated, it is necessary to keep the viscosity of the dispersion system as high as possible at the start of aggregation to prevent the core material composition from settling. As the above method, it is possible to add a carboxylic acid group-containing compound and adjust the molecular weight and acid value thereof.

  As the carboxylic acid group-containing compound described above, it is effective that the weight average molecular weight Mw is in the range of 500 to 3,000 and the acid value is in the range of 150 mg · KOH / g to 600 mg · KOH / g. There is no particular limitation.

  Examples of the carboxylic acid group-containing compound include oligomers or copolymer resins of monomers having a carboxylic acid group, and salts thereof. Examples of the monomer having a carboxylic acid group include an α, β-ethylenically unsaturated compound having a carboxylic acid group. Examples of the α, β-ethylenically unsaturated compound having a carboxylic acid group include acrylic acid, methacrylic acid, fumaric acid, maleic acid, itaconic acid, cinnamic acid, monomethyl maleate, monobutyl maleate, malein And acid monooctyl ester. Examples of copolymer resins with monomers having a carboxylic acid group include styrene-acrylic acid copolymer resins, styrene-acrylic acid ester-acrylic acid copolymer resins, α-methylstyrene-acrylic acid copolymer resins, and styrene. -Maleic acid copolymer resins and their salts. Moreover, a part of those copolymer resins may be esterified.

  The core material is preliminarily fired at a temperature of 700 ° C. or more and 1200 ° C. or less after pulverizing and mixing each oxide in an appropriate amount in advance and further pulverizing. After calcination, a dispersing agent is used if necessary in a wet ball mill or a wet vibration mill, and the mixture is pulverized and dispersed in water to 1 μm or less. The particle diameter of the core material in water is preferably 1 μm or less, more preferably 0.5 μm or less, and further preferably in the range of 0.01 μm or more and 0.5 μm or less.

  As the dispersant, it is preferable to use a surfactant such as an anionic surfactant, a cationic surfactant, or a nonionic surfactant. Among these, it is more preferable to use an anionic surfactant because of its strong dispersion power and excellent dispersion.

  The content of the surfactant in each dispersion is generally a small amount, specifically, preferably in the range of 0.01 wt% or more and 10 wt% or less, and 0.05 wt% or more. More preferably, it is in the range of 5% by weight or less, and further preferably in the range of 0.1% by weight or more and 2% by weight or less. When the content is 0.01% by weight or more, dispersion of the dispersion is stable, and it is difficult to cause aggregation in a state where no flocculant is used, and the stability between the particles at the time of aggregation is almost constant, Problems such as the release of specific particles are unlikely to occur. If it is 10% by weight or less, the particle size distribution of the particles is narrow, and the particle size can be easily controlled.

  In the present invention, when a layer containing a metal oxide is provided, metal oxide particles other than the ferrite composition of the core material are dispersed in the aggregated particle dispersion between the aggregation step and the fusion step. It is preferable to provide a step (adhesion step) of adding the adhering particle dispersion and adhering the particles to the aggregated particles to form adhering particles.

  In the attaching step, the particle dispersion is added to and mixed with the aggregated particle dispersion prepared in the aggregation step, and the particles are attached to the aggregated particles to form attached particles. The added particles correspond to particles newly added to the aggregated particles when viewed from the aggregated particles, and may be referred to as “additional particles” in this specification. As the additional particles, in addition to the metal oxide particles, resin particles or the like may be used alone or in combination. There is no restriction | limiting in particular as a method of adding and mixing an additional particle dispersion liquid, For example, you may carry out gradually continuously, and may carry out in steps divided into several times.

  By providing an adhesion step, a shell structure can be formed, and the surface exposure of the core material composition can be reduced with a layer containing a metal oxide, resulting in improved resistance stability and carrier life. it can.

  In the fusing step after the attaching step, the resin particles in the aggregated particles melt at a temperature condition equal to or higher than the glass transition temperature of the resin, and the aggregated particles gradually change from an indeterminate shape to a spherical shape. At this time, the shape of the agglomerated particles is indefinite, but it becomes closer to a sphere due to coalescence. When the desired shape is obtained, heating is stopped and the particles are formed by cooling.

  The average particle size of the resin particles in the binder resin particle dispersion is preferably 1 μm or less, and more preferably in the range of 0.01 μm to 1 μm. When the average particle size is 1 μm or less, the particle size distribution of the particles obtained by aggregation and fusion is narrow. By adjusting the average particle size in the above range, the dispersion of the core material composition and additional particles in the aggregated particles can be improved, and the uneven distribution of the composition between the particles can be suppressed, and carrier performance and reliability can be reduced. There is an advantage that variation can be suppressed low. In addition, the said average particle diameter can be measured with a laser diffraction type particle size distribution measuring machine, a Coulter counter, etc., for example.

  Using the materials as described above, in the agglomeration step, the dispersion prepared by adding and mixing the resin particle dispersion and the core composition dispersion is stirred from room temperature to the glass transition temperature of the resin plus about 5 ° C. By heating in this temperature range, the resin particles and the core material composition particles are aggregated to form aggregated particles.

  In the aggregation step, the particles of the resin particle dispersion and the core material composition particle dispersion mixed together are aggregated to form aggregated particles. The agglomerated particles are formed by heteroaggregation or the like. For the purpose of stabilizing the agglomerated particles and controlling the particle size / particle size distribution, the aggregated particles are charged with a monovalent or higher charge such as an ionic surfactant having a polarity different from the agglomerated particles or a metal salt. It is formed by adding the compound which has.

  In the aggregation step, aggregated particles can be generated by changing the pH, and the particle size of the particles can be adjusted. At the same time, an aggregating agent may be added as a method of stably and rapidly agglomerating particles or obtaining agglomerated particles having a narrower particle size distribution.

  As the flocculant, a compound having a monovalent or higher charge is preferable, and specific examples thereof include water-soluble surfactants such as ionic surfactants and nonionic surfactants; hydrochloric acid, sulfuric acid, nitric acid, acetic acid, Acids such as oxalic acid; metal salts of inorganic acids such as magnesium chloride, sodium chloride, aluminum sulfate, calcium sulfate, ammonium sulfate, aluminum nitrate, silver nitrate, copper sulfate, sodium carbonate; sodium acetate, potassium formate, sodium oxalate, phthalic acid Metal salts of aliphatic acids and aromatic acids such as sodium and potassium salicylate; Metal salts of phenols such as sodium phenolate; Metal salts of amino acids; Aliphatic and aromatic amines such as triethanolamine hydrochloride and aniline hydrochloride Inorganic acid salts; and the like.

  The flocculant is more preferably a metal salt of an inorganic acid such as magnesium chloride, sodium chloride, aluminum sulfate, calcium sulfate, ammonium sulfate, aluminum nitrate, silver nitrate, copper sulfate, sodium carbonate; sodium acetate, potassium formate, sodium oxalate, Inorganic and organic metal salts such as aliphatic acid metal salts such as sodium phthalate and potassium salicylate; more preferably, polyvalent inorganic metal salts such as aluminum sulfate, aluminum nitrate, aluminum chloride and magnesium chloride are aggregated It can be suitably used in terms of the stability of the particles, the stability of the flocculant with respect to heat and time, and the removal during washing.

  The amount of these flocculants to be added varies depending on the valence of the charge, but they are all small, and are 3% by weight or less for monovalent and 1% by weight for divalent with respect to the binder resin particles. Hereinafter, in the case of trivalent, it is preferably 0.5% by weight or less. Since a smaller amount of the flocculant is preferable, a compound having a higher valence is preferable.

  Metal oxide particles (additional particles) are additionally added to the aggregated particles thus formed to form a metal oxide particle coating layer on the surface of the aggregated particles (attachment step). Next, heat treatment is performed at a temperature equal to or higher than the glass transition temperature of the resin to fuse the aggregated particles, and an aggregated particle-containing liquid is obtained and cooled. Next, the obtained aggregated particle-containing liquid is processed by centrifugal separation and / or suction filtration to separate the aggregated particles, and washed with ion exchange water 1 to 3 times. Thereafter, the aggregated particles are filtered, washed with ion-exchanged water 1 to 3 times, and dried to obtain core material composition-dispersed particles having a layer containing a metal oxide.

  The dispersed particles are held at a temperature of 1,000 ° C. or higher and 1,500 ° C. or lower for 1 hour to 24 hours and fired. At this time, in order to reduce the firing residue of the binder resin, it may be fired at 500 ° C. or more and 1,000 ° C. or less for 1 hour or more and 24 hours or less and further at the above temperature.

  The core material can have a narrow particle size distribution, but may be subjected to particle size adjustment such as sieving and classification in order to pulverize the sintered particles and adjust the particle size as necessary.

When a resin is coated on a core material, a typical method is to inject a resin and conductive particles into a resin-soluble solvent to form a resin coating layer forming raw material solution, and the core powder is used as a resin coating layer. A dipping method of immersing in a forming solution, a spray method of spraying a resin coating layer forming solution on the surface of the core material, a fluidized bed method of spraying the coating layer forming solution in a state where the core material is suspended by flowing air, Examples include a kneader coater method in which a core material and a resin coating layer forming solution are mixed in a kneader coater, and then the solvent is removed. In the carrier of the present invention, the core material and the resin coating layer forming solution are used. And magnetic particles are mixed and then the solvent is removed in a kneader coater process.
Usually, when manufacturing by a kneader coater method, the carrier core material and the coating layer forming solution in which the conductive particles are dispersed are mixed, and the solvent is removed by heating and reducing pressure while stirring.

  The solvent used for preparing the resin coating layer forming solution is not particularly limited as long as it dissolves the resin. For example, aromatic hydrocarbons such as toluene and xylene, acetone, methyl ethyl ketone, and the like. Ketones, ethers such as tetrahydrofuran and dioxane, and halides such as chloroform and carbon tetrachloride can be used.

<Characteristics of carrier>
The weight average particle diameter of the carrier is preferably 15 μm or more and 50 μm or less, and more preferably 25 μm or more and 40 μm or less. When the weight average particle diameter of the carrier is 15 μm or more, carrier contamination is small. Further, when the carrier has a weight average particle diameter of 50 μm or less, toner deterioration due to stirring can be suppressed.

  The weight average particle diameter of the carrier is measured using a laser diffraction / scattering particle size distribution analyzer (LS Particle Size Analyzer: LS13 320, manufactured by Beckman Coulter, Inc.).

  For the particle size range (channel) obtained by dividing the obtained particle size distribution, the volume cumulative distribution is subtracted from the small particle size side, and the particle size at 50% cumulative is taken as the volume average particle size.

  Further, the shape factor SF1 of the carrier is preferably 100 or more and 145 or less. This is to achieve both high image quality and developer agitation efficiency.

The carrier shape factor SF1 means a value obtained by the following equation (12).
Formula (12): SF1 = 100π × (ML) ² / (4 × A)
Here, ML is the maximum length of the carrier particles, and A is the projected area of the carrier particles.
The maximum length and projected area of the carrier particles are determined by observing the carrier particles sampled on the slide glass with an optical microscope and importing them into an image analyzer (LUZEX III, manufactured by NIRECO) through a video camera for image analysis. Is obtained by The number of samplings at this time is 100 or more, and the shape factor shown in Expression (12) is obtained using the average value.

The saturation magnetization of the carrier is preferably 40 emu / g or more, and more preferably 50 emu / g or more.
As a device for measuring magnetic properties, a vibration sample type magnetic measuring device VSMP10-15 (manufactured by Toei Industry Co., Ltd.) is used. The measurement sample is packed in a cell having an inner diameter of 7 mm and a height of 5 mm and set in the apparatus. The measurement applies an applied magnetic field and sweeps up to 1,000 oersted. Next, the applied magnetic field is decreased to create a hysteresis curve on the recording paper. Saturation magnetization, residual magnetization, and coercive force are obtained from the curve data. In the present invention, saturation magnetization refers to magnetization measured in a 1,000 oersted magnetic field.

The volume electric resistance of the carrier is preferably controlled in the range of 1 × 10 ⁷ Ω · cm to 1 × 10 ¹⁵ Ω · cm, and preferably 1 × 10 ⁸ Ω · cm to 1 × 10 ¹⁴ Ω · cm. The range is more preferable, and the range of 1 × 10 ⁸ Ω · cm to 1 × 10 ¹³ Ω · cm is more preferable.
If the volume electrical resistance of the carrier is 1 × 10 ¹⁵ Ω · cm or less, the resistance does not become high, it works well as a developing electrode during development, and the edge effect does not occur particularly in the solid image area, and solid reproducibility is achieved. Excellent. On the other hand, when it is 1 × 10 ⁷ Ω · cm or more, the resistance is moderate, and when the toner concentration in the developer is lowered, injection of charge from the developing roll to the carrier is difficult to occur, and development of the carrier itself is difficult to occur.
The volume electrical resistance of the carrier is measured in the same manner as the volume electrical resistance of the core material.

(Static charge image developer)
The electrostatic image developer of the present invention includes at least an electrostatic image developing toner (hereinafter also simply referred to as “toner”) and the electrostatic image developing carrier of the present invention. Hereinafter, the developer for developing an electrostatic charge image of the present invention (hereinafter also simply referred to as “developer”) will be described.
The toner is not particularly limited, and a known toner can be used. Examples of the toner include a colored toner having a binder resin and a colorant. In addition, an infrared absorbing toner having a binder resin and an infrared absorber can be used.

  Binder resins include monoolefins such as ethylene, propylene, butylene, and isoprene; vinyl esters such as vinyl acetate, vinyl propionate, vinyl benzoate, and vinyl butyrate; methyl acrylate, phenyl acrylate, octyl acrylate, and methacrylic acid. Α-methylene aliphatic monocarboxylic esters such as methyl, ethyl methacrylate, butyl methacrylate, dodecyl methacrylate; vinyl ethers such as vinyl methyl ether, vinyl ethyl ether, vinyl butyl ether; vinyl methyl ketone, vinyl hexyl ketone, vinyl Homopolymers or copolymers of vinyl ketones such as isopropenyl ketone; Among these, particularly typical binder resins include polystyrene, styrene-alkyl acrylate copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polystyrene, polypropylene, and the like. Further examples include polyester, polyurethane, epoxy resin, silicone resin, polyamide, modified rosin and the like.

  The crystalline binder resin is not particularly limited as long as it is a crystalline resin, and specific examples include crystalline polyester resins and crystalline addition polymerization resins. A crystalline polyester resin is preferable from the viewpoints of adhesion and chargeability and adjustment of the melting point within a preferable range. An aliphatic crystalline polyester resin having an appropriate melting point is more preferable.

  Examples of the crystalline addition polymerization resin include amyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, octyl (meth) acrylate, nonyl (meth) acrylate, and (meth) acrylic acid. Decyl, undecyl (meth) acrylate, tridecyl (meth) acrylate, myristyl (meth) acrylate, cetyl (meth) acrylate, stearyl (meth) acrylate, oleyl (meth) acrylate, behenyl (meth) acrylate And vinyl resins using long-chain alkyl and alkenyl (meth) acrylic acid esters. In the present specification, the description “(meth) acryl” means that both “acryl” and “methacryl” are included.

  On the other hand, the crystalline polyester resin is synthesized from an acid (dicarboxylic acid) component and an alcohol (diol) component. In the present invention, the “acid-derived constituent component” The component part which was an acid component is pointed out, and the "alcohol-derived component" refers to the component part which was an alcohol component before the synthesis of the polyester resin. In the present invention, the “crystalline polyester resin” refers to a resin having a clear endothermic peak instead of a stepwise endothermic amount change in differential scanning calorimetry (DSC). In the case of a polymer obtained by copolymerizing another component with the crystalline polyester main chain, when the other component is 50% by weight or less, this copolymer is also called crystalline polyester.

-Acid-derived components-
The acid-derived constituent component is preferably an aliphatic dicarboxylic acid, and more preferably a linear aliphatic dicarboxylic acid. Examples of linear aliphatic dicarboxylic acids include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelic acid, sebacic acid, 1,9-nonanedicarboxylic acid, 1, 10-decanedicarboxylic acid, 1,11-undecanedicarboxylic acid, 1,12-dodecanedicarboxylic acid, 1,13-tridecanedicarboxylic acid, 1,14-tetradecanedicarboxylic acid, 1,16-hexadecanedicarboxylic acid, 1,18 -Octadecanedicarboxylic acid and the like, or lower alkyl esters and acid anhydrides thereof. Among these, those having 6 to 10 carbon atoms are preferable from the viewpoint of crystal melting point and chargeability. In order to increase the crystallinity, these linear dicarboxylic acids are preferably used in an amount of 95 mol% or more, more preferably 98 mol% or more of the acid component.

  The other monomer is not particularly limited. For example, a conventionally known divalent or carboxylic acid which is a monomer component described in Polymer Data Handbook: Basics (Science of Polymer Science: Bafukan). And divalent alcohol. Specific examples of these monomer components include divalent carboxylic acids such as phthalic acid, isophthalic acid, terephthalic acid, naphthalene-2,6-dicarboxylic acid, naphthalene-2,7-dicarboxylic acid, and cyclohexanedicarboxylic acid. And dibasic acids such as these, anhydrides thereof, and lower alkyl esters thereof. These may be used individually by 1 type and may use 2 or more types together.

As the acid-derived constituent component, in addition to the above-mentioned aliphatic dicarboxylic acid-derived constituent component, a constituent component such as a dicarboxylic acid-derived constituent component having a sulfonic acid group is preferably included.
The dicarboxylic acid having a sulfonic acid group is effective in that it can favorably disperse a coloring material such as a pigment. Further, when emulsifying or suspending the entire resin in water to produce toner mother particles into fine particles, if there are sulfonic acid groups, emulsification or suspension is possible without using a surfactant, as will be described later. . Examples of such a dicarboxylic acid having a sulfone group include, but are not limited to, 2-sulfoterephthalic acid sodium salt, 5-sulfoisophthalic acid sodium salt, and sulfosuccinic acid sodium salt. Moreover, these lower alkyl esters, acid anhydrides, etc. are also mentioned. Among these, 5-sulfoisophthalic acid sodium salt is preferable in terms of cost. The content of the dicarboxylic acid having a sulfonic acid group is preferably 0.1 to 2.0 mol%, and more preferably 0.2 to 1.0 mol%. When the content is more than 2 mol%, the chargeability is deteriorated. In the present invention, “component mol%” refers to a percentage when each component (acid-derived component, alcohol-derived component) in the polyester resin is 1 unit (mol).

-Alcohol-derived components-
The alcohol component is preferably an aliphatic dialcohol, such as ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptane. Diol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-dodecanediol, 1,12-undecanediol, 1,13-tridecanediol, 1,14-tetradecane Examples thereof include diol, 1,18-octadecanediol, 1,20-eicosanediol, and among them, those having 6 to 10 carbon atoms are preferable from the viewpoint of crystal melting point and chargeability. In order to enhance crystallinity, these linear dialcohols are preferably used in an amount of 95 mol% or more, more preferably 98 mol% or more of the alcohol constituent.

  Other divalent dialcohols include, for example, bisphenol A, hydrogenated bisphenol A, ethylene oxide and / or propylene oxide adducts of bisphenol A, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, diethylene glycol, propylene Examples include glycol, dipropylene glycol, 1,3-butanediol, and neopentyl glycol. These may be used individually by 1 type and may use 2 or more types together.

  If necessary, monovalent acids such as acetic acid and benzoic acid, monovalent alcohols such as cyclohexanol and benzyl alcohol, benzenetricarboxylic acid, and naphthalenetricarboxylic acid for the purpose of adjusting the acid value and hydroxyl value. Trivalent alcohols such as acids and the like, anhydrides thereof, lower alkyl esters thereof, glycerin, trimethylolethane, trimethylolpropane, and pentaerythritol can also be used.

  The polyester resin can be used in any combination of the monomer components described above, for example, polycondensation (chemical doujin), polymer experimental studies (polycondensation and polyaddition: Kyoritsu Publishing) and polyester resin handbook (Nikkan Kogyo Co., Ltd.). Can be synthesized by using a conventionally known method described in a newspaper company), or a transesterification method or a direct polycondensation method can be used alone or in combination. The molar ratio (acid component / alcohol component) when the acid component and the alcohol component are reacted varies depending on the reaction conditions and the like, so it cannot be generally stated, but in the case of direct polycondensation, usually about 1/1. In the case of the transesterification method, ethylene glycol, neopentyl glycol, cyclohexanedimethanol, etc. are often used in excess of monomers that can be distilled off under vacuum. The production of the polyester resin is preferably carried out at a polymerization temperature of 180 ° C. or higher and 250 ° C. or lower, and the reaction system is subjected to a reaction while reducing the pressure in the reaction system as necessary to remove water and alcohol generated during condensation. be able to. When the monomer is not dissolved or compatible at the reaction temperature, a solvent having a high boiling point may be added as a solubilizer and dissolved. In the polycondensation reaction, the dissolution auxiliary solvent is distilled off. In the case where a monomer having poor compatibility is present in the copolymerization reaction, the monomer having poor compatibility and the monomer and the acid or alcohol to be polycondensed are condensed in advance and then polycondensed together with the main component.

  Catalysts that can be used in the production of the polyester resin include alkali metal compounds such as sodium and lithium, alkaline earth metal compounds such as magnesium and calcium, and metal compounds such as zinc, manganese, antimony, titanium, tin, zirconium, and germanium. , Phosphorous acid compounds, phosphoric acid compounds, amine compounds, etc., specifically, sodium acetate, sodium carbonate, lithium acetate, lithium carbonate, calcium acetate, calcium stearate, magnesium acetate, zinc acetate, stearic acid Zinc, zinc naphthenate, zinc chloride, manganese acetate, manganese naphthenate, titanium tetraethoxide, titanium tetrapropoxide, titanium tetraisopropoxide, titanium tetrabutoxide, antimony trioxide, triphenylantimony, trib Ruantimony, tin formate, tin oxalate, tetraphenyltin, dibutyltin dichloride, dibutyltin oxide, diphenyltin oxide, zirconium tetrabutoxide, zirconium naphthenate, zirconyl carbonate, zirconyl acetate, zirconyl stearate, zirconyl octylate, germanium oxide, triphenyl Examples of the compound include phosphite, tris (2,4-di-t-butylphenyl) phosphite, ethyltriphenylphosphonium bromide, triethylamine, and triphenylamine. Among these, a tin-based catalyst and a titanium-based catalyst are preferable from the viewpoint of chargeability, and among them, dibutyltin oxide is preferably used.

  The melting point of the crystalline polyester resin is preferably 50 ° C. or higher and 120 ° C. or lower, and more preferably 60 ° C. or higher and 110 ° C. or lower. When the melting point is 50 ° C. or higher, the storage stability of the toner and the storage stability of the toner image after fixing are excellent. Moreover, it is excellent in low temperature fixability as it is 120 degrees C or less.

  In the present invention, the melting point of the crystalline polyester resin is measured according to JIS K using a differential scanning calorimeter (DSC) and measuring from room temperature to 150 ° C. at a rate of temperature increase of 10 ° C. per minute. It can be obtained as the melting peak temperature of the input compensation differential scanning calorimetry shown in −7121. The crystalline resin may show a plurality of melting peaks, but in the present invention, the maximum peak is regarded as the melting point.

  The colorant is not particularly limited. For example, carbon black, aniline blue, calcoil blue, chrome yellow, ultramarine blue, deyupon oil red, quinoline yellow, methylene blue chloride, phthalocyanine blue, malachite green oxalate, lamp black. Rose Bengal, C.I. I. Pigment red 48: 1, C.I. I. Pigment red 122, C.I. I. Pigment red 57: 1, C.I. I. Pigment yellow 97, C.I. I. Pigment yellow 12, C.I. I. Pigment blue 15: 1, pigment blue 15: 3, and the like.

  Further, the toner can contain a charge control agent as required. At that time, a colorless or light-colored charge control agent that does not affect the color tone is preferred particularly when used for a color toner or the like. As the charge control agent, known ones can be used, but it is preferable to use an azo metal complex; a metal complex or metal salt of salicylic acid or alkylsalicylic acid;

The toner can also contain other known components such as an anti-offset agent such as low molecular weight propylene, low molecular weight polyethylene, and wax.
Examples of the wax include the following. Paraffin wax and derivatives thereof, montan wax and derivatives thereof, microcrystalline wax and derivatives thereof, Fischer-Tropsch wax and derivatives thereof, polyolefin wax and derivatives thereof, and the like. Derivatives include oxides, polymers with vinyl monomers, and graft modified products. In addition, alcohols, fatty acids, plant waxes, animal waxes, mineral waxes, ester waxes, acid amides, and the like can be used.

Further, the toner may contain inorganic oxide particles therein. Examples of the inorganic oxide particles include SiO ₂ , TiO ₂ , Al ₂ O ₃ , CuO, ZnO, SnO ₂ , CeO ₂ , Fe ₂ O ₃ , MgO, BaO, CaO, K ₂ O, Na ₂ O, ZrO _2. CaO.SiO ₂ , K ₂ O. (TiO ₂ ) _n , Al ₂ O ₃ .2SiO ₂ , CaCO ₃ , MgCO ₃ , BaSO ₄ , MgSO _{4 and the} like. Of these, silica particles and titania particles are particularly preferable. The surface of the oxide particles does not necessarily need to be hydrophobized in advance, but may be hydrophobized. When the hydrophobic treatment is performed, even when some of the internal inorganic particles are exposed on the toner surface, it is possible to effectively reduce the environmental dependency of charging and carrier contamination.

The hydrophobic treatment can be performed by immersing an inorganic oxide in the hydrophobic treatment agent. Although there is no restriction | limiting in particular as a hydrophobization processing agent, For example, a silane coupling agent, a silicone oil, a titanate coupling agent, an aluminum coupling agent etc. are mentioned. These may be used individually by 1 type and may use 2 or more types together. Of these, silane coupling agents are preferred.
As the silane coupling agent, for example, any type of chlorosilane, alkoxysilane, silazane, and a special silylating agent can be used.
Specifically, methyltrichlorosilane, dimethyldichlorosilane, trimethylchlorosilane, phenyltrichlorosilane, diphenyldichlorosilane, tetramethoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, phenyltrimethoxysilane, diphenyldimethoxysilane, tetraethoxysilane, Methyltriethoxysilane, dimethyldiethoxysilane, phenyltriethoxysilane, diphenyldiethoxysilane, isobutyltriethoxysilane, decyltrimethoxysilane, hexamethyldisilazane, N, O- (bistrimethylsilyl) acetamide, N, N- ( Trimethylsilyl) urea, tert-butyldimethylchlorosilane, vinyltrichlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane , Γ-methacryloxypyrroletrimethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-mercapto Examples thereof include propyltrimethoxysilane and γ-chloropropyltrimethoxysilane.
The amount of the hydrophobizing agent varies depending on the type of the inorganic oxide particles and cannot be defined unconditionally, but is preferably 5 parts by weight or more and 50 parts by weight or less with respect to 100 parts by weight of the inorganic oxide particles.

In the toner, inorganic oxide particles can be added to the toner surface. Preferred examples of the inorganic oxide particles added to the toner surface include the inorganic oxide particles described above. It is preferable that the surface of the oxide particles has been previously hydrophobized. In addition to improving the powder fluidity of the toner, this hydrophobic treatment can effectively suppress the environmental dependency of charging and carrier contamination.
The hydrophobic treatment can be performed by immersing an inorganic oxide in a hydrophobic treatment agent, as described above. Although there is no restriction | limiting in particular as a hydrophobization processing agent, For example, a silane coupling agent, a silicone oil, a titanate coupling agent, an aluminum coupling agent etc. are mentioned. These may be used individually by 1 type and may use 2 or more types together. Of these, silane coupling agents are preferred.
As said silane coupling agent, the above-mentioned silane coupling agent can be illustrated preferably.
As in the above, the amount of the hydrophobizing agent varies depending on the type of inorganic oxide particles and cannot be generally defined. The following is preferred.

Regarding the particle size distribution of the toner, toner particles having a particle size of 4 μm or less are preferably 6% by number or more and 25% by number or less, more preferably 6% by number or more and 16% by number or less of the total number of toner particles. . When the number of toner particles having a particle diameter of 4 μm or less is 6% by number or more, the number of particles contributing to fine dot reproducibility and graininess is moderate, and the number of toner particles having a particle diameter that hardly contributes to development when repeated copying is performed. Is less likely to stay in the developing machine, and the image quality is excellent even after repeated copying. On the other hand, when it is 25% by number or less, the toner fluidity, developer transportability, and developability are excellent.
The toner particles having a particle diameter of 16 μm or more are preferably 1.0% by volume or less. When it is 1.0% by volume or less, the fine line reproducibility and gradation are excellent, and during transfer, there are few coarse powder toners of 16 μm or more in the toner layer, so that the electrostatic adhesion state between the photosensitive member and the transfer member is hindered. Excellent transfer efficiency and image quality.

The volume average particle diameter of the toner is preferably 5 μm or more and 9 μm or less, and more preferably compatible with the preferred range of the particle size distribution described above in order to reproduce high image quality. When the volume average particle size is 5 μm or more, the toner has excellent fluidity, is provided with sufficient chargeability from the carrier, does not cause fogging on the background, and has excellent density reproducibility. When the volume average particle diameter is 9 μm or less, the carrier characteristics described above can be sufficiently exhibited, and the effect of improving the reproducibility, gradation and graininess of fine dots can be sufficiently obtained.
Therefore, by having the above-mentioned toner particle size distribution and volume average particle diameter, the image area of photographs, paintings, pamphlets, etc. has a large image area. , Faithful reproducibility can be expected.

The particle size distribution and volume average particle size of the toner are measured using Coulter Multisizer II (manufactured by Beckman-Coulter). As the electrolytic solution, ISOTON-II (manufactured by Beckman Coulter, Inc.) is used.
As a specific measurement method, 0.5 mg to 50 mg of a measurement sample is added to 2 ml of a 5% aqueous solution of a surfactant, preferably sodium alkylbenzenesulfonate as a dispersant, and this is added to 100 ml or more and 150 ml or less of the electrolytic solution. Add to. The electrolytic solution in which the measurement sample is suspended is subjected to a dispersion treatment with an ultrasonic disperser for about 1 minute. Using the Coulter Multisizer II type, an aperture having an aperture diameter of 100 μm is used, and a particle diameter is 2.0 μm to 60 μm. The particle size distribution of the following range of particles is measured. The number of particles to be measured is 50,000.
For the measured particle size distribution, a cumulative distribution is drawn from the small diameter side with respect to the divided particle size range (channel), and the particle size at which 50% is accumulated is defined as the weight average particle size.

As a method for producing the toner, generally used kneading and pulverizing methods, wet granulation methods, and the like can be used. Here, as the wet granulation method, suspension polymerization method, emulsion polymerization method, emulsion polymerization aggregation method, soap-free emulsion polymerization method, non-aqueous dispersion polymerization method, in-situ polymerization method, interfacial polymerization method, emulsion dispersion granulation Method, agglomeration and coalescence method, and the like can be used.
In order to produce the toner of the present invention by the kneading and pulverization method, the binder resin, and if necessary, the colorant and other additives are sufficiently mixed by a mixer such as a Henschel mixer and a ball mill, and a heating roll, a kneader, While melting and kneading using a heat kneader such as an extruder to make the resins compatible with each other, an infrared absorber, an antioxidant, etc. are dispersed or dissolved, and after cooling and solidification, pulverization and classification are performed to obtain a toner. be able to.
When toner particles are produced by a wet granulation method, the shape factor of the toner particles is preferably in the range of 110 to 135.
Here, the shape factor of the toner particles is obtained in the same manner as the shape factor SF1 of the carrier.

  In the developer of the present invention, the mixing weight ratio of the toner and the carrier is preferably a toner weight / carrier weight of 0.01 or more and 0.3 or less, more preferably 0.03 or more and 0.2 or less. preferable.

  The developer of the present invention can be applied not only as a developer stored in advance in a developing means (developer storage container) but also as a supply developer used in, for example, a trickle development system.

(Cartridge, process cartridge, image forming method, and image forming apparatus)
Next, the cartridge of the present invention will be described.
The cartridge of the present invention is a cartridge containing at least the electrostatic charge image developing carrier of the present invention or the electrostatic image developer of the present invention. The cartridge of the present invention is preferably detachable from the image forming apparatus.
In the image forming apparatus, by using the cartridge of the present invention containing the developer of the present invention, it is less dependent on the environment such as temperature and humidity, and the coating resin layer is difficult to peel off, and stable image formation over a long period of time. It can be performed.
Here, the cartridge of the present invention may be a cartridge that stores the developer of the present invention, particularly when used in an image forming apparatus of a trickle development system, or a cartridge that stores toner alone and a carrier of the present invention. It may be a separate cartridge from the cartridge stored alone.

The image forming method of the present invention includes a latent image forming step of forming an electrostatic latent image on the surface of the latent image holding member, and developing the electrostatic latent image formed on the surface of the latent image holding member with a developer containing toner. A developing step for forming a toner image, a transfer step for transferring the toner image formed on the surface of the latent image holding member to the surface of the transfer target, and a fixing for thermally fixing the toner image transferred to the surface of the transfer target. The electrostatic charge image developing carrier of the present invention as the developer.
In the image forming method of the present invention, a developer is prepared using the specific carrier as described above, and an electrostatic image is formed and developed by a conventional electrophotographic copying machine using the developer. The image is electrostatically transferred onto the transfer paper, and is fixed by a heating roller fixing device in which the temperature of the upper heating roller is set to a constant temperature to form a copy image.

  The carrier for developing an electrostatic charge image of the present invention can be used in an image forming method of an ordinary electrostatic charge image development method (electrophotographic method). Specifically, the image forming method of the present invention is preferably a method including, for example, an electrostatic latent image forming step, a developing step, a transferring step, and a cleaning step. Each of the above steps is a general step per se, and is described in, for example, JP-A-56-40868 and JP-A-49-91231. The image forming method of the present invention can be carried out using an image forming apparatus such as a copier or a facsimile machine known per se.

The electrostatic latent image forming step is a step of forming an electrostatic latent image on the electrostatic latent image carrier.
The developing step is a step of developing the electrostatic latent image with a developer layer on a developer carrier to form a toner image. The developer layer is not particularly limited as long as it contains the electrostatic charge image developing toner and the electrostatic charge image developer of the invention containing the electrostatic charge image developing carrier of the invention.
The transfer step is a step of transferring the toner image onto a transfer target. Examples of the transfer medium in the transfer process include an intermediate transfer medium and a recording medium such as paper.
In the fixing step, the toner image transferred onto the transfer paper is fixed by a heating roller fixing device in which the temperature of the heating roller is set to a constant temperature to form a copy image.
The cleaning step is a step of removing the electrostatic charge image developer remaining on the electrostatic latent image carrier.

  In the image forming method of the present invention, an embodiment that further includes a recycling step is preferable. The recycling step is a step of transferring the electrostatic image developing toner collected in the cleaning step to the developer layer. The image forming method including the recycling step can be performed using an image forming apparatus such as a toner recycling system type copying machine or facsimile machine. The present invention can also be applied to a recycling system in which the cleaning process is omitted and toner is collected simultaneously with development.

The image forming apparatus of the present invention forms an electrostatic latent image on the latent image holding body by exposing the latent image holding body, charging means for charging the latent image holding body, and exposing the charged latent image holding body. Exposure means for developing, developing means for developing the electrostatic latent image with a developer containing toner to form a toner image, and transfer means for transferring the toner image from the latent image holding member to the transfer target. The developer includes the electrostatic image developing carrier of the present invention.
Therefore, by utilizing the image forming apparatus of the present invention using the developer of the present invention, the environmental dependency such as temperature and humidity is small and the coating resin layer is hardly peeled off, so that stable image formation can be performed over a long period of time. It can be carried out.

The image forming apparatus of the present invention is not particularly limited as long as it includes at least the latent image holding member, the charging unit, the exposure unit, the developing unit, and the transfer unit as described above, but other necessary. Depending on the situation, a fixing means, a cleaning means, a static elimination means, etc. may be included.
In the transfer unit, the transfer may be performed twice or more using an intermediate transfer member. Examples of the transfer medium in the transfer unit include an intermediate transfer medium and a recording medium such as paper.
The developing means is housed in the developer containing container for containing the developer of the present invention, the developer supplying means for supplying the developer to the developer containing container, and the developer containing container. A configuration including a developer discharging means for discharging at least a part of the developer, that is, a trickle developing method may be employed.
Here, the developer (supplying developer) to be supplied to the developer containing container preferably has a toner / carrier mixing weight ratio of (toner weight / carrier weight) ≧ 2, and (toner weight / carrier Weight) ≧ 3 is more preferable, and (toner weight / carrier weight) ≧ 5 is further preferable.

When such a trickle development method is used, if a resin-coated carrier from which the coating resin layer is easy to peel off is used, not only does the coating resin layer peel off in the developer originally in the developer container, but also from the developer supply means. The coating resin layer in the developer supplied from time to time to the developer container is also peeled off, and the influence of the carrier resin peeling powder becomes larger than when the trickle developing method is not used.
However, if the image forming apparatus of the present invention using the developer of the present invention is used, the resin coating layer in the developer of the present invention is difficult to peel off, and the above problem does not occur even if the trickle development method is used. It is possible to stably form an image over a long period of time while reducing the dependency.

  The latent image carrier and each of the above-described units can preferably use the configurations described in the respective steps of the image forming method. As each of the above-described means, a known means in the image forming apparatus can be used. Further, the image forming apparatus of the present invention may include means and devices other than those described above. Further, the image forming apparatus of the present invention may simultaneously perform a plurality of the above-described means.

The process cartridge of the present invention comprises a developing means for developing the electrostatic latent image formed on the latent image holding member with the developer of the present invention containing toner to form a toner image, the latent image holding member, and the latent image. At least one selected from the group consisting of a charging means for charging the holding body and a cleaning means for removing the toner remaining on the surface of the latent image holding body. The process cartridge of the present invention is preferably detachable from the image forming apparatus.
In addition, the process cartridge of the present invention may include other members such as a static eliminating unit as necessary.
In the image forming apparatus, by using the process cartridge of the present invention containing the present invention, there is little dependency on the environment such as temperature and humidity, and the coating resin layer is hardly peeled off, so that stable image formation can be performed over a long period of time. be able to.
Hereinafter, the cartridge, the image forming apparatus, and the process cartridge of the present invention will be specifically described with reference to the drawings.

FIG. 1 is a cross-sectional view schematically showing a basic configuration of a preferred embodiment (first embodiment) of an image forming apparatus of the present invention. The image forming apparatus shown in FIG. 1 includes the cartridge of the present invention.
The image forming apparatus 10 shown in FIG. 1 includes a latent image holding body 12, a charging unit 14, an exposure unit 16, a developing unit 18, a transfer unit 20, a cleaning unit 22, a charge eliminating unit 24, a fixing unit 26, and a cartridge 28.
The developer stored in the developing means 18 and the cartridge 28 is the developer of the present invention.
For convenience, FIG. 1 shows only a configuration having one developing means 18 and one cartridge 28 each containing the developer of the present invention. For example, in the case of a color image forming apparatus, the image forming apparatus includes It is also possible to adopt a configuration including a corresponding number of developing means 18 and cartridges 28.

  The image forming apparatus shown in FIG. 1 is an image forming apparatus having a configuration in which a cartridge 28 can be attached and detached. The cartridge 28 is connected to the developing means 18 through a developer supply pipe 30. Therefore, when performing image formation, the developer of the present invention stored in the cartridge 28 is supplied to the developing means 18 through the developer supply rod 30 so that the developer of the present invention can be applied over a long period of time. The used image can be formed. Further, when the amount of developer stored in the cartridge 28 is reduced, the cartridge 28 can be replaced.

Around the latent image holding body 12, charging means 14 for uniformly charging the surface of the latent image holding body 12 in order along the rotation direction (arrow A direction) of the latent image holding body 12, and the latent image according to the image information. Exposure means 16 for forming an electrostatic latent image on the surface of the holding body 12, developing means 18 for supplying the developer of the present invention to the formed electrostatic latent image, and the latent image holding body 12 in contact with the surface of the latent image holding body 12 Drum-shaped transfer means 20 that can be driven to rotate in the direction of arrow B along with the rotation in the direction of arrow A, a cleaning device 22 that contacts the surface of the latent image holding body 12, and a static elimination means that neutralizes the surface of the latent image holding body 12. 24 is arranged.
A recording medium 50 transported in the direction of arrow C by a transport unit (not shown) from the opposite side to the direction of arrow C can be inserted between the latent image holding body 12 and the transfer unit 20. A fixing unit 26 incorporating a heating source (not shown) is disposed on the side of the electrostatic latent image holding body 12 in the direction of arrow C. The fixing unit 26 is provided with a pressure contact portion 32. In addition, the recording medium 50 that has passed between the electrostatic latent image holding member 12 and the transfer unit 20 can be inserted through the pressure contact portion 32 in the direction of arrow C.

As the latent image carrier 12, for example, a photosensitive member or a dielectric recording member can be used.
As the photoreceptor, for example, a photoreceptor having a single layer structure or a photoreceptor having a multilayer structure can be used. As the material of the photoconductor, an inorganic photoconductor such as selenium or amorphous silicon, an organic photoconductor, or the like can be considered.
Examples of the charging means 14 include a contact charging device using a conductive or semiconductive roller, brush, film, rubber blade, or the like, a non-contact charging device such as corotron charging or scorotron charging using corona discharge, and the like. Any known means can be used.
As the exposure unit 16, in addition to the known exposure unit, any conventionally known unit that can form a signal capable of forming a toner image at a desired position on the surface of the recording medium can be used.

As the exposure means, for example, a conventionally known exposure means such as a combination of a semiconductor laser and a scanning device, a laser scanning writing device comprising an optical system, or an LED head can be used. In order to realize a preferable mode of producing a uniform and high-resolution exposure image, it is preferable to use a laser scanning writing device or an LED head.
Specifically, as the transfer unit 20, for example, a conductive or semiconductive roller, brush, film, rubber blade, or the like to which a voltage is applied is used, between the latent image carrier 12 and the recording medium 50. The toner particles are charged by corona charging the back surface of the recording medium 50 by means of an electric field to transfer a toner image composed of charged toner particles, a corotron charger using a corona discharge, a scorotron charger, or the like. Conventionally known means such as a means for transferring a toner image made of can be used.

Further, a secondary transfer unit can be used as the transfer unit 20. That is, although not shown, the secondary transfer unit is a unit that transfers the toner image once to the intermediate transfer member and then secondary-transfers the toner image from the intermediate transfer member to the recording medium 50.
Examples of the cleaning unit 22 include a cleaning blade and a cleaning brush.
Examples of the static eliminating unit 24 include a tungsten lamp and an LED.
As the fixing unit 26, for example, a heat fixing unit that fixes a toner image by heating and pressing such as a heating roll and a pressure roll, or an optical fixing unit that heats and fixes a toner image by light irradiation with a flash lamp or the like. Etc. are available.

  The material forming the roll surface such as a heating roll or a pressure roll is preferably a material excellent in releasability with respect to the toner, such as silicon rubber or fluorine-based resin, for the purpose of preventing the toner from adhering. At this time, it is desirable not to apply a releasable liquid such as silicone oil to both sides of the roll. The releasable liquid is effective for widening the fixing latitude, but since it is transferred to the recording medium to be fixed, stickiness is generated on the printed matter on which the image is formed, and the tape cannot be attached or the character is printed by magic. May cause problems such as being unable to write. This problem becomes more prominent when a film such as OHP is used as the recording medium. In addition, since it is difficult for the releasable liquid to smooth the roughness of the fixed image surface, it may cause a decrease in image transparency which is particularly important when an OHP film is used as a recording medium. . However, when the toner contains a wax (offset preventing agent), it exhibits a sufficient fixing latitude, so that a releasable liquid such as silicone oil applied to the fixing roll is not necessary.

  The recording medium 50 is not particularly limited, and conventionally known media such as plain paper and glossy paper can be used. A recording medium having a base material and an image receiving layer formed on the base material can also be used.

Next, image formation using the image forming apparatus 10 will be described. First, as the latent image holding body 12 rotates in the direction of arrow A, the surface of the latent image holding body 12 is charged by the charging unit 14, and the charged latent image holding body 12 surface is subjected to image information by the exposure unit 16. By forming the electrostatic latent image and supplying the developer P of the present invention from the developing means 18 to the surface of the latent image holding body 12 on which the electrostatic latent image is formed according to the color information of the electrostatic latent image. A toner image is formed.
Next, the toner image formed on the surface of the latent image holding body 12 moves to a contact portion between the latent image holding body 12 and the transfer unit 20 as the latent image holding body 12 rotates in the direction of arrow A. At this time, the recording medium 50 is inserted through the contact portion in the direction of the arrow C by a paper conveyance roll (not shown), and the latent image holding body is applied by the voltage applied between the latent image holding body 12 and the transfer means 20. The toner image formed on the surface 12 is transferred to the surface of the recording medium 50 at the contact portion.
The toner remaining on the surface of the latent image holding member 12 after the toner image is transferred to the transfer unit 20 is removed by the cleaning blade of the cleaning unit 22, and the charge is removed by the charge removing unit 24.

  The recording medium 50 having the toner image transferred onto the surface in this way is conveyed to the pressure contact portion 32 of the fixing unit 26 and is passed through the pressure contact portion 32 by a built-in heating source (not shown). The surface of the pressure contact portion 32 is heated by the heated fixing means 26. At this time, an image is formed by fixing the toner image on the surface of the recording medium 50.

FIG. 2 is a cross-sectional view schematically showing a basic configuration of another preferred embodiment (second embodiment) of the image forming apparatus of the present invention.
In the image forming apparatus shown in FIG. 2, the developer (supplying developer) of the present invention is appropriately supplied by a developer supplying means to a developer containing container in the developing means, and is housed in the developer containing container. The trickle developing method is adopted in which at least a part of the developer is appropriately discharged by the developer discharging means.

  As shown in FIG. 2, the image forming apparatus 100 according to the embodiment of the present invention includes a latent image holding body 110 that rotates clockwise as indicated by an arrow a, and a latent image holding body 110 above the latent image holding body 110. Formed with a developer (toner) on the surface of the latent image holding body 110 charged relative to the image holding body 110 and charged negatively on the surface of the latent image holding body 110. An exposure unit 130 for writing an image to be formed to form an electrostatic latent image, and a latent image holding member provided on the downstream side of the exposure unit 130 to attach toner to the electrostatic latent image formed by the exposure unit 130 A developing unit 140 that forms a toner image on the surface of 110, and an endless transfer that travels in the direction indicated by the arrow b while contacting the latent image holding body 110 and transfers the toner image formed on the surface of the latent image holding body 110. Belt-like The intermediary transfer belt 150, the neutralization means 160 for facilitating the removal of the transfer residual toner remaining on the surface by neutralizing the surface of the latent image holding body 110 after the toner image is transferred to the intermediate transfer belt 150, and the latent image holding Cleaning means 170 for cleaning the surface of the body 110 to remove the transfer residual toner.

The charging unit 120, the exposure unit 130, the development unit 140, the intermediate transfer belt 150, the charge removal unit 160, and the cleaning unit 170 are arranged on the circumference surrounding the latent image holding body 110 in the clockwise direction.
The intermediate transfer belt 150 is tensioned and held from the inside by the stretching rollers 150A and 150B, the backup roller 150C, and the driving roller 150D, and is driven in the direction of the arrow b as the driving roller 150D rotates. At a position opposite to the latent image holding body 110 inside the intermediate transfer belt 150, the intermediate transfer belt 150 is positively charged to attract the toner on the electrostatic latent image holding body 110 to the outer surface of the intermediate transfer belt 150. A primary transfer roller 151 is provided. The toner image formed on the intermediate transfer belt 150 is transferred onto the recording medium P by positively charging the recording medium P and pressing it against the intermediate transfer belt 150 outside the intermediate transfer belt 150. A secondary transfer roller 152 is provided to face the backup roller 150C.
Below the intermediate transfer belt 150, a recording medium supply device 153 that supplies the recording medium P to the secondary transfer roller 152 and a recording medium P on which a toner image is formed on the secondary transfer roller 152 are conveyed. On the other hand, a fixing unit 180 for fixing the toner image is provided.

  The recording medium supply device 153 includes a pair of transport rollers 153A and a guide slope 153B that guides the recording medium P transported by the transport rollers 153A toward the secondary transfer roller 152. On the other hand, the fixing unit 180 includes a fixing roller 181 that is a pair of heat rollers for fixing the toner image by heating and pressing the recording medium P on which the toner image has been transferred by the secondary transfer roller 152, and fixing. A conveyance conveyor 182 that conveys the recording medium P toward the roller 181.

The recording medium P is conveyed in the direction indicated by the arrow c by the recording medium supply device 153, the secondary transfer roller 152, and the fixing unit 180.
In the vicinity of the intermediate transfer belt 150, an intermediate transfer body cleaning unit 154 having a cleaning blade for removing toner remaining on the intermediate transfer belt 150 after the toner image is transferred to the recording medium P by the secondary transfer roller 152. Is provided.

Hereinafter, the developing unit 140 will be described in detail.
The developing means 140 is disposed in the developing area so as to face the latent image holding member 110. For example, the developing means 140 is a two-component developer composed of a toner charged to negative (−) polarity and a carrier charged to positive (+) polarity. A developer storage container 141 is provided. The developer container 141 includes a developer container main body 141A and a developer container cover 141B that closes the upper end of the developer container main body 141A.
The developer container main body 141A has a developing roll chamber 142A for storing the developing roll 142 therein, and is adjacent to the first stirring chamber 143A and the first stirring chamber 143A adjacent to the developing roll chamber 142A. 144A of 2nd stirring chambers. Further, a layer thickness regulating member 145 is provided in the developing roll chamber 142A for regulating the layer thickness of the developer on the surface of the developing roll 142 when the developer containing container cover 141B is attached to the developer containing container main body 141A. It has been.

The first stirring chamber 143A and the second stirring chamber 144A are partitioned by a partition wall 141C. Although not shown, the first stirring chamber 143A and the second stirring chamber 144A are arranged in the longitudinal direction of the partition wall 141C (developing device). (Longitudinal direction) Communication portions are provided at both ends to communicate with each other, and the first stirring chamber 143A and the second stirring chamber 144A constitute a circulation stirring chamber (143A + 144A).
The developing roll 142 is disposed in the developing roll chamber 142A so as to face the electrostatic latent image holding body 110. Although not shown, the developing roll 142 is provided with a sleeve outside a magnetic roll (fixed magnet) having magnetism. The developer in the first stirring chamber 143A is adsorbed on the surface of the developing roll 142 by the magnetic force of the magnetic roll and is transported to the developing area. Further, the roll axis of the developing roll 142 is rotatably supported by the developer container main body 141A. Here, the developing roll 142 and the latent image holding body 110 rotate in opposite directions, and the developer adsorbed on the surface of the developing roll 142 in the opposite portion is in the same direction as the moving direction of the latent image holding body 110. To the development area.
A bias power supply (not shown) is connected to the sleeve of the developing roll 142 so that a predetermined developing bias is applied (in this embodiment, an alternating electric field is applied to the developing region. , Applying a bias in which the AC component (AC) is superimposed on the DC component (DC)).

In the first stirring chamber 143A and the second stirring chamber 144A, a first stirring member 143 (stirring / conveying member) and a second stirring member 144 (stirring / conveying member) that convey the developer while stirring are disposed. The first stirring member 143 includes a first rotating shaft that extends in the axial direction of the developing roller 142, and an agitating / conveying blade (protrusion) that is helically fixed to the outer periphery of the rotating shaft. Similarly, the second stirring member 144 includes a second rotating shaft and a stirring conveyance blade (protrusion). The stirring member is rotatably supported by the developer container main body 141A. The first stirring member 143 and the second stirring member 144 are arranged such that the developer in the first stirring chamber 143A and the second stirring chamber 144A is conveyed in the opposite directions by rotation thereof. .
One end of a developer supplying unit 146 for appropriately supplying a supply developer including supply toner and a supply carrier to the second agitating chamber 144A is connected to one end side in the longitudinal direction of the second agitating chamber 144A. The developer supply means 146 is connected to a developer cartridge 147 containing a supply developer. In addition, one end of a developer discharging unit 148 for appropriately discharging the stored developer is connected to one end side in the longitudinal direction of the second stirring chamber 144A, and the other end of the developer discharging unit 148 is connected to the other end of the developer discharging unit 148. Although not shown, it is connected to a developer container that collects the discharged developer.

As described above, the developing unit 140 appropriately supplies the developer for supply from the developer cartridge 147 through the developer supplying unit 146 to the developing unit 140 (second stirring chamber 144A), and removes the old developer as the developer discharging unit. A so-called trickle developing system that appropriately discharges from 148 (to prevent the developer charging performance from deteriorating and to extend the developer replacement interval, supply developer (trickle developer) is gradually supplied into the developing device. On the other hand, it is a developing system in which development is performed while discharging a deteriorated developer that is excessive (including many deteriorated carriers).
Here, in this embodiment, the configuration using the developer cartridge 147 containing the supply developer of the present invention has been described as an example. However, the developer cartridge 147 includes a cartridge that stores supply toner alone and the main cartridge. The cartridge for independently containing the carrier for supply of the present invention may be separated.

Next, the cleaning unit 170 will be described in detail. The cleaning unit 170 includes a housing 171 and a cleaning blade 172 disposed so as to protrude from the housing 171. The cleaning blade 172 is a plate-like member extending in the extending direction of the rotation shaft of the latent image holding body 110, and is downstream in the rotation direction (arrow a direction) from the transfer position by the primary transfer roller 151 in the latent image holding body 110. The tip end portion (hereinafter referred to as an edge portion) is provided in pressure contact on the side and on the downstream side in the rotational direction from the position where the charge is removed by the charge removal means 160.
The cleaning blade 172 is carried on the latent image holding body 110 without being transferred to the recording medium P by the primary transfer roller 151 as the latent image holding body 110 rotates in a predetermined direction (arrow a direction). Foreign matter such as untransferred residual toner and paper dust of the recording medium P is dammed and removed from the latent image holding member 110.

A transport member 173 is disposed at the bottom of the housing 171, and toner particles (developer) removed by the cleaning blade 172 are developed on the downstream side in the transport direction of the transport member 173 in the housing 171. One end of a supply conveying means 174 for supplying to is connected. The other end of the supply / conveyance unit 174 is coupled to the developer supply unit 146.
As described above, the cleaning unit 170 transports the untransferred residual toner particles to the developing unit 140 (second stirring chamber 144A) through the supply transport unit 174 in accordance with the rotation of the transport member 173 provided at the bottom of the housing 171. Toner reclaim is used in which the developer (toner) contained in the container is stirred and conveyed for reuse.

FIG. 3 is a cross-sectional view schematically showing a basic configuration of still another preferred embodiment (third embodiment) of the image forming apparatus of the present invention.
The image forming apparatus shown in FIG. 3 includes the process cartridge of the present invention.
An image forming apparatus 200 shown in FIG. 3 includes a process cartridge 210 detachably disposed in an image forming apparatus main body (not shown), an exposure unit 216, a transfer unit 220, and a fixing unit 226. .
The process cartridge 210 has a rail 211 on which a charging unit 214, a developing unit 218, and a cleaning unit 222 are mounted around a latent image holding body 212 in a casing 211 provided with an opening 211 A for forming an electrostatic latent image. (Not shown) are combined and integrated. Note that the process cartridge 210 is not limited to this, and may include the developing unit 218 and at least one selected from the group consisting of the latent image holding member 212, the charging unit 214, and the cleaning unit 222.

On the other hand, the exposure means 216 is disposed at a position where a latent image can be formed on the latent image holding member 212 from the opening 211A of the casing 211 of the process cartridge 210. Further, the transfer unit 220 is disposed at a position facing the latent image holding body 212.
The individual details of the latent image holding member 212, the charging unit 214, the exposure unit 216, the developing unit 218, the transfer unit 220, the cleaning unit 222, the fixing unit 226, and the recording medium 250 are described in the image forming apparatus of FIG. 10 is the same as the latent image holding body 12, the charging unit 14, the exposure unit 16, the developing unit 18, the transfer unit 20, the cleaning unit 22, the fixing unit 26, and the recording medium 50.
Further, the image formation using the image forming apparatus 200 of FIG. 3 is the same as the image formation using the image forming apparatus 10 of FIG.

  Hereinafter, the present invention will be described in detail with reference to examples. However, the present invention is not limited only to the following examples.

〔Measuring method〕
<Measurement method of BET specific surface area>
Using a BET specific surface area meter (SA3100, manufactured by Beckman Coulter, Inc.) as a measuring device, 0.1 g of a measurement sample is precisely weighed, placed in a sample tube, degassed, and obtained by automatic measurement using a multipoint method. The obtained numerical value was defined as the BET specific surface area A of the core material.

<Method for measuring volume average particle diameter of core material>
The volume average particle size of the core material was measured using a laser diffraction / scattering particle size distribution analyzer (LS Particle Size Analyzer: LS13 320, manufactured by Beckman Coulter, Inc.). For the particle size range (channel) obtained by dividing the obtained particle size distribution, the volume cumulative distribution was subtracted from the small particle size side, and the particle size at 50% cumulative was taken as the volume average particle size.

<Measurement method of true specific gravity of core material>
In addition, the true specific gravity of the core material was measured using a Lechatelier specific gravity bottle according to JIS-K-0061 5-2-1. The operation was performed as follows.
(1) About 250 ml of ethyl alcohol is put into a Lechatelier specific gravity bottle and adjusted so that the meniscus is at the position of the scale.
(2) The specific gravity bottle is immersed in a constant temperature water bath, and when the liquid temperature reaches 20.0 ± 0.2 ° C., the position of the meniscus is accurately read with the scale of the specific gravity bottle. (Accuracy 0.025ml)
(3) About 100 g of a sample is weighed and its mass is defined as W (g).
(4) Put the weighed sample in a specific gravity bottle to remove bubbles.
(5) The specific gravity bottle is immersed in a constant temperature water bath, and when the liquid temperature becomes 20.0 ± 0.2 ° C., the position of the meniscus is accurately read with the scale of the specific gravity bottle. (Accuracy 0.025ml)
(6) The true specific gravity is calculated by the following formula.
D = W / (L2-L1)
ρ = D / 0.9982
In the formula, D is the density of the sample (20 ° C.) (g / cm ³ ), ρ is the true specific gravity of the sample (20 ° C.), W is the apparent mass (g) of the sample, and L1 is before the sample is placed in the specific gravity bottle. Meniscus reading (20 ° C.) (ml), L2 is the meniscus reading (20 ° C.) (ml) after the sample is placed in the density bottle, 0.9982 is the density of water at 20 ° C. (g / cm ³ ) It is.

<Measurement method of magnetic properties>
As a device for measuring the magnetic properties, a vibration sample type magnetic measuring device VSMP10-15 (manufactured by Toei Industry Co., Ltd.) was used. The measurement sample is packed in a cell having an inner diameter of 7 mm and a height of 5 mm and set in the apparatus. The measurement was performed by applying an applied magnetic field and sweeping up to 3,000 oersted. Next, the applied magnetic field was decreased to produce a hysteresis curve on the recording paper. From the curve data, saturation magnetization, residual magnetization, and coercive force were obtained. In the present invention, saturation magnetization refers to magnetization measured in a 1,000 oersted magnetic field.

<Measuring method of volumetric electric resistance of core material, conductive powder, carrier>
The volume electric resistance (Ω · cm) of the core material, conductive powder, and carrier was measured as follows. The measurement environment was a temperature of 20 ° C. and a humidity of 50% RH.
On the surface of a circular jig provided with a 20 cm ² electrode plate, the measurement object was placed flat so as to have a thickness of about 1 mm to 3 mm, thereby forming a layer. A 20 cm ² electrode plate similar to the above was placed thereon, and the layers were sandwiched. In order to eliminate gaps between objects to be measured, the thickness (cm) of the layer was measured after a load of 4 kg was applied on the electrode plate placed on the layer. Both electrodes above and below the layer are connected to an electrometer and a high voltage power generator. A high voltage was applied to both electrodes so that the electric field was 10 ^3.8 V / cm, and the current value (A) flowing at this time was read to calculate the volume electric resistance (Ω · cm) of the measurement object. The calculation formula of the volume electrical resistance (Ω · cm) of the measurement object is as shown in the following formula.
Formula: R = E × 20 / (I−I ₀ ) / L
In the above formula, R is the volume electric resistance (Ω · cm) of the measurement object, E is the applied voltage (V), I is the current value (A), I ₀ is the current value (A) at the applied voltage of 0 V, and L is Each layer thickness (cm) is expressed. A coefficient of 20 represents the area (cm ² ) of the electrode plate.

<Measurement method of volume average particle diameter in conductive powder and resin particles>
The volume average particle diameter of the conductive powder and the resin particles was measured using a laser diffraction particle size distribution analyzer (LA-700: manufactured by Horiba, Ltd.).
As a measuring method, first, a sample in a dispersion state was adjusted so as to have a solid content of about 2 g, and ion-exchanged water was added thereto to make about 40 ml. This was put into the cell until an appropriate concentration was reached, waited for 2 minutes, and measured when the concentration in the cell became almost stable.
The obtained volume average particle diameter for each channel is accumulated from the smaller volume average particle diameter, and the volume average particle diameter is defined as 50%.

<Measurement method of coverage>
The coverage of the coating resin layer was determined by XPS measurement. As an XPS measurement device, JPS80 manufactured by JEOL Ltd. was used, and measurement was performed using MgKα ray as an X-ray source, setting an acceleration voltage to 10 kV, and an emission current to 20 mV. Measurements were made on the main constituent elements (usually carbon) and the main constituent elements of the core (for example, iron and oxygen when the core is an iron oxide-based material such as magnetite) (hereinafter, the core is iron oxide) The explanation is based on the assumption that the system is a system). Here, the C1s spectrum was measured for carbon, the Fe2p _3/2 spectrum was measured for iron, and the O1s spectrum was measured for oxygen.
Based on the spectrum of each of these elements, the number of elements of carbon, oxygen, and iron (A _C + A _O + A _Fe ) is obtained, and the following formula (9) is obtained from the obtained number ratio of carbon, oxygen, and iron. Based on this, the iron content rate after coating the core material alone and the core material with the coating resin layer (carrier) was determined, and then the coverage rate was determined by the following formula (10).
Formula (9): Iron content rate (atomic%) = A _Fe / (A _C + A _O + A _Fe ) × 100
Formula (10): Coverage rate (%) = {1− (iron content rate of carrier) / (iron content rate of core material alone)} × 100

In addition, when using materials other than iron oxide as a core material, the spectrum of the metal element which comprises a core material besides oxygen is measured, and it is the same according to the above-mentioned formula (9) and formula (10). If the above calculation is performed, the coverage can be obtained.
The average film thickness (μm) of the coating resin layer is such that the true specific gravity of the core material is ρ (dimensionless), the volume average particle diameter of the core material is d (μm), the average specific gravity of the coating resin layer is ρ _C , and the core material 100 When the total content of the coating resin layer with respect to parts by weight is W _C (parts by weight), it can be obtained as in the following formula (11).
Formula (11): Average film thickness (μm) = {[amount of coating resin per carrier (including all additives such as conductive powder) / surface area per carrier]} / average specific gravity of coating resin layer
= {[4 / 3π · (d / 2) ³ · ρ · W _C ] / [4π · (d / 2) ² ]} / ρ _C
= (1/6) · (d · ρ · W _C / ρ _C )

<Measurement method of volume average particle diameter of carrier and volume average particle diameter of toner>
The volume average particle diameter of the carrier was measured using an electron microscope (SEM). More specifically, after obtaining an image by SEM, the diameter (longest portion) r ₁ of each particle was measured. After measuring this for 100 particles, r _{1 to} r ₁₀₀ were converted to a sphere diameter to determine the volume, and the value at 50% from the first to the 100th was taken as the volume average particle diameter.
The volume average particle diameter of the toner was measured using a Coulter Multisizer II (manufactured by Beckman-Coulter). As the electrolytic solution, ISOTON-II (manufactured by Beckman-Coulter) was used.
As a measuring method, first, 0.5 mg to 50 mg of a measurement sample is added to 2 ml of a 5% aqueous solution of a surfactant, preferably sodium alkylbenzenesulfonate, as a dispersant, and this is added to 100 ml to 150 ml of the electrolytic solution. Added. The electrolytic solution in which the measurement sample is suspended is subjected to a dispersion treatment with an ultrasonic disperser for about 1 minute. Using the Coulter Multisizer II type, an aperture having an aperture diameter of 100 μm is used. The particle size distribution of the following range of particles was measured. The number of particles to be measured was 50,000.
For the divided particle size range (channel), draw the cumulative distribution from the smaller diameter side in terms of weight or volume, and define the 50% cumulative particle size as the heavy average particle size or volume average particle size, respectively. To do.

<How to find the shape factor>
The shape factor SF1 was obtained by the following equation (11).
Formula (11): SF1 = 100π × (ML) ² / (4 × A)
Here, ML is the maximum length of the particle, and A is the projected area of the particle. The maximum length and the projected area of the particles were determined by observing the particles sampled on the slide glass with an optical microscope, taking them into an image analyzer (LUZEX III, manufactured by NIRECO) through a video camera, and performing image analysis. The number of samplings at this time was 100 or more, and the shape factor shown in Expression (11) was obtained using the average value.

<Measurement method of glass transition point of resin>
The glass transition point (Tg) of the resin is measured using a differential scanning calorimeter (manufactured by Shimadzu Corporation: DSC-50) under a temperature rising rate of 3 ° C./min. The temperature at the intersection of the extension line with the rising line was taken as the glass transition point.

[Manufacture of core material]
<Manufacture of core material A>
The core material A was manufactured as follows.
After mixing 70 parts by weight of Fe ₂ O ₃ , 22 parts by weight of MnO _{2 and} 7 parts by weight of Mg (OH) ₂ , mixing / pulverizing with a wet ball mill for 30 hours, granulating and drying with a spray dryer, and then using a rotary kiln Pre-baking 1 was performed at 850 ° C. for 7 hours. The calcined product 1 thus obtained was pulverized for 2 hours with a wet ball mill to a volume average particle size of 2.1 μm, further granulated and dried with a spray dryer, and then at 910 ° C. for 6 hours using a rotary kiln. The preliminary firing 2 was performed. The calcined product 2 thus obtained was pulverized with a wet ball mill for 5 hours to have a volume average particle size of 5.4 μm, granulated and dried with a spray dryer, and then heated at a temperature of 905 ° C. using an electric furnace. The main baking was performed for 12 hours. A core material A having a volume average particle size of 34.0 μm was prepared through a crushing step and a classification step.
The properties of the obtained core material A are as shown in Table 1.

<Manufacture of core material B>
The core material B was manufactured as follows.
After mixing 70 parts by weight of Fe ₂ O ₃ , 22 parts by weight of MnO _{2 and} 7 parts by weight of Mg (OH) ₂ , mixing / pulverizing with a wet ball mill for 30 hours, granulating and drying with a spray dryer, and then using a rotary kiln Pre-baking 1 was performed at 850 ° C. for 7 hours. The calcined product 1 thus obtained was pulverized for 2.5 hours with a wet ball mill to a volume average particle size of 2.0 μm, further granulated and dried with a spray dryer, and then at 910 ° C. using a rotary kiln. Pre-baking 2 for 5 hours was performed. The calcined product 2 thus obtained was pulverized for 6 hours with a wet ball mill to a volume average particle size of 4.9 μm, further granulated and dried with a spray dryer, and then at a temperature of 950 ° C. using an electric furnace. The main baking for 17 hours was performed. A core material B having a volume average particle size of 36.0 μm was prepared through a crushing step and a classification step. BET = 0.111.

<Manufacture of core material C>
In manufacturing the core material C, the following dispersions were prepared.

[Preparation of resin particle dispersion (1)]
-Styrene 280 parts-n-butyl acrylate 100 parts-Acrylic acid 8 parts-Dodecyl mercaptan 10 parts-Carbon tetrabromide 3 parts The above components are mixed and dissolved in advance to prepare a solution, and a nonionic interface A surfactant solution obtained by dissolving 7 parts of an activator (Sanyo Chemical Industries, Ltd .: Novonyl) and 10 parts of an anionic surfactant (Daiichi Kogyo Seiyaku Co., Ltd .: Neogen RK) in 520 parts of ion-exchanged water; The solution was put into a flask and emulsified. While slowly mixing for 10 minutes, 70 parts of ion-exchanged water in which 3 parts of ammonium persulfate was dissolved was added to perform nitrogen substitution. Thereafter, while stirring the flask, the contents were heated in an oil bath until the content reached 70 ° C., and emulsion polymerization was continued for 6 hours. Thereafter, the reaction solution is cooled to room temperature, and a resin particle dispersion (1) having an average particle size of 150 nm, a glass transition point of 58.0 ° C., a weight average molecular weight Mw of 25,000 and Mw / Mn of 2.5. )

[Preparation of carboxylic acid group-containing dispersant liquid (1)]
Ammonia water is added to a styrene-maleic acid copolymer GSM601 (Mw = 6,000, acid value = 470, manufactured by Gifu Serask Manufacturing Co., Ltd.) and dissolved while heating to adjust the resin concentration to 30%. A carboxylic acid group-containing dispersant liquid (1) was obtained.

[Preparation of Carrier Core Composition Dispersion (1)]
· Fe ₂ O ₃ 75 parts · MnO ₂ 22 parts · MgO 3 parts by weight were mixed and granulated by a spray drier for 30 hours mixed / pulverized by a wet ball mill, dried, 850 ° C. using a rotary kiln, Pre-baking 1 was performed for 7 hours.
The following was added to this mixture, and this was pulverized for 6 hours by a wet ball mill to prepare a carrier core material composition dispersion (1).
-Anionic surfactant (Neogen RK: manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) 10 parts-Ion-exchanged water 200 parts When the particle size distribution of the carrier core composition dispersion (1) was measured, the average particle size was 500 nm. It was.

[Preparation of Metal Oxide Dispersion (1)]
・ Alumina 100 parts ・ Anionic surfactant (Takemoto Yushi Co., Ltd .: Pionein A-45-D) 2 parts ・ Ion-exchanged water 200 parts The above was mixed and dissolved, and pulverized in a wet ball mill for 24 hours. As a result, a metal oxide dispersion (1) obtained by dispersing metal oxide particles (alumina) having an average particle diameter of 300 nm was obtained.

[Metal oxide dispersed resin particle dispersion (1)]
Using the metal oxide dispersion (1) obtained above, a metal oxide dispersion resin particle dispersion (1) was prepared as follows.
-Resin particle dispersion (1) 150 parts-Metal oxide dispersion (1) 500 parts-Cationic surfactant (manufactured by Kao Corporation: Sanisol B50)-3 parts-Carboxylic acid group-containing dispersant liquid (1) 5 parts, ion-exchanged water 600 parts The above components were mixed and dispersed in a round bottom stainless steel flask using a homogenizer (IKA, Ultra Turrax T50), and then heated with stirring in a heating oil bath. The aggregation temperature was heated to 62 ° C. and held for 30 minutes to form aggregated particles. When a part of the obtained aggregated particles was observed with an optical microscope, a metal oxide dispersed particle liquid (1) having an average particle diameter of about 6 μm was obtained.

[Preparation of core material C]
-Resin particle dispersion (1) 150 parts-Carrier core composition dispersion (1) 800 parts-Cationic surfactant (manufactured by Kao Corporation: Sanizol B50) 3 parts-Carboxylic acid group-containing dispersant liquid ( 1) 5 parts, ion-exchanged water 600 parts The above components were mixed and dispersed in a round bottom stainless steel flask using a homogenizer (IKA, Ultra Turrax T50), and then heated with stirring in a heating oil bath. Then, the aggregation temperature was heated to 74 ° C. and held for 30 minutes to form aggregated particles. When a part of the obtained aggregated particles was observed with an optical microscope, the average particle diameter of the aggregated particles was about 35 μm. 50 parts of the metal oxide-dispersed resin particle dispersion (1) was slowly added to the aggregated particle liquid, and the mixture was further heated and stirred at 85 ° C. for 30 minutes to obtain an aggregated particle liquid (C). The average particle size of the aggregated particles in the obtained aggregated particle liquid was about 38 μm.
Subsequently, after adjusting pH to 9.0 with ammonia water, it sealed, heated to 105 degreeC, and was hold | maintained as it was for 7 hours, and the aggregated particle was united. Thereafter, the mixture was cooled, filtered and sufficiently washed with ion exchange water. This was dried with a vacuum dryer, then fired at 900 ° C. in an oxygen-free state for 2 hours, and then fired at 1200 ° C. for 4 hours to obtain a core material C having an alumina-containing layer. When the volume average particle diameter D _50v of the fused particles was measured with a Coulter counter, it was 33.0 μm. Moreover, the content rate of the alumina in a magnetic particle was 0.1, and the content rate of the alumina in an alumina content layer was 85%.
The content ratio of alumina in the magnetic particles and the content ratio of alumina in the alumina-containing layer were measured using an X-ray microanalyzer EPMA-1610 (manufactured by Shimadzu Corporation) with an acceleration voltage of 15 kV and a sample current of 0. The measurement was performed by irradiating the magnetic particle part and the alumina-containing layer under the conditions of 0.1 μA and irradiation range φ100 μm (electron beam diameter).

<Manufacture of core material D>
In producing the core material D, the following dispersion was prepared.

[Preparation of metal oxide dispersion (2)]
-Manganese dioxide 100 parts-Anionic surfactant (Takemoto Yushi Co., Ltd. product: Pionin A-45-D) 2 parts-Ion-exchanged water 200 parts The above was mixed and dissolved, and pulverized in a wet ball mill for 24 hours. As a result, a metal oxide dispersion (2) obtained by dispersing metal oxide particles (alumina) having an average particle size of 300 nm was obtained.

[Preparation of metal oxide dispersed resin particle dispersion (2)]
Using the metal oxide dispersion (2) obtained above, a metal oxide dispersion resin particle dispersion (2) was prepared as follows.
-Resin particle dispersion (1) 150 parts-Metal oxide dispersion (2) 500 parts-Cationic surfactant (manufactured by Kao Corporation: Sanizol B50)-3 parts-Carboxylic acid group-containing dispersant liquid (1) 5 parts, ion-exchanged water 600 parts The above components were mixed and dispersed in a round bottom stainless steel flask using a homogenizer (IKA, Ultra Turrax T50), and then heated with stirring in a heating oil bath. The aggregation temperature was heated to 62 ° C. and held for 30 minutes to form aggregated particles. When a part of the obtained aggregated particles was observed with an optical microscope, a metal oxide-dispersed resin particle dispersion (2) having an average particle diameter of about 6 μm was obtained.

[Preparation of core material D]
-Resin particle dispersion (1) 150 parts-Carrier core composition dispersion (1) 800 parts-Cationic surfactant (manufactured by Kao Corporation: Sanizol B50) 3 parts-Carboxylic acid group-containing dispersant liquid ( 1) 5 parts, ion-exchanged water 600 parts The above components were mixed and dispersed in a round bottom stainless steel flask using a homogenizer (IKA, Ultra Turrax T50), and then heated with stirring in a heating oil bath. Then, the aggregation temperature was heated to 74 ° C. and held for 30 minutes to form aggregated particles. When a part of the obtained aggregated particles was observed with an optical microscope, the average particle diameter of the aggregated particles was about 35 μm. 50 parts of the metal oxide-dispersed resin particle dispersion (2) was slowly added to the aggregated particle liquid, and the mixture was further heated and stirred at 85 ° C. for 30 minutes to obtain an aggregated particle liquid (D). The average particle size of the aggregated particles in the obtained aggregated particle liquid was about 38 μm.
Subsequently, after adjusting pH to 9.0 with ammonia water, it sealed, heated to 105 degreeC, and was hold | maintained as it was for 7 hours, and the aggregated particle was united. Thereafter, the mixture was cooled, filtered and sufficiently washed with ion exchange water. This was dried with a vacuum dryer, then fired at 900 ° C. in an oxygen-free state for 2 hours, and then fired at 1200 ° C. for 4 hours to obtain a core material D having a manganese dioxide-containing layer. When the volume average particle diameter D _50v of the fused particles was measured with a Coulter counter, it was 33.0 μm. Moreover, the content rate of manganese dioxide in the magnetic particles was 0.1, and the content rate of manganese dioxide in the alumina-containing layer was 54%.

[Manufacture of resin used as material for coating resin layer]
Production of the resin of the coating resin layer was performed as follows.

<Manufacture of resin A>
-Bisphenoxyethanol fluorene (BPEF) 219.3 parts by weight-Terephthalic acid 74.75 parts by weight-Trimellitic anhydride 9.60 parts by weight-Dodecylbenzenesulfonic acid (DBSA) 0.65 parts by weight 6 hours at 120 ° C Stir. Further, 300 parts by weight of benzene was added, heated to 60 ° C. and shaken for 6 hours for polymerization.
The reaction product was dissolved in methyl ethyl ketone and precipitated with 7 times the amount of hexane to obtain Resin A.
The obtained resin had a weight average molecular weight Mw = 58,000, a glass transition temperature of 111 ° C., and a volume electric resistance of 10 ¹⁶ .
Table 2 shows the composition and characteristics of the obtained resin A.

<Manufacture of resin B>
-Bisphenol A ethylene oxide 2 mol adduct (BPA-2EO) 126.6 parts by weight-Bisphenol fluorene (BPF) 35.0 parts by weight-Terephthalic acid 8.31 parts by weight-Cyclohexanedicarboxylic acid 68.8 parts by weight-Tri anhydride 9.6 parts by weight of merit acid and 0.65 parts by weight of dodecylbenzenesulfonic acid (DBSA) were added and stirred at 120 ° C. for 6 hours to obtain a polycondensation resin.
For 108.8 parts by weight of the resin obtained as described above,
• 140.1 parts by weight of methyl methacrylate • 1.5 parts by weight of dimethylaminoethyl methacrylate (dimethylaminoethyl methacrylate) • 300 parts by weight of benzene • 0.6 parts by weight of azobisisobutyronitrile The mixture was heated and shaken for 6 hours to polymerize.
The reaction product was dissolved in methyl ethyl ketone and precipitated with 7 times the amount of hexane to obtain Resin B.
The obtained resin had a weight average molecular weight Mw = 96,000, a glass transition temperature of 112 ° C., and a volume electric resistance of 10 ¹⁶ .
Table 2 shows the composition and characteristics of the obtained resin B.

<Manufacture of resin C>
Biscresol fluorene (BCF) 189.3 parts by weight Terephthalic acid 75.0 parts by weight Dodecylbenzenesulfonic acid (DBSA) 0.65 parts by weight were added and stirred at 120 ° C for 6 hours to obtain a polycondensation resin.
For 108.8 parts by weight of the resin obtained as described above,
• 90 parts by weight methyl methacrylate • 7.0 parts by weight perfluorooctylethyl methacrylate-methyl methacrylate • 300 parts by weight benzene • 0.6 parts by weight azobisisobutyronitrile The polymerization was carried out with shaking over time. The reaction product was dissolved in methyl ethyl ketone and precipitated with 7 times the amount of hexane to obtain Resin C. The obtained resin had a weight average molecular weight Mw = 98,000, a glass transition temperature of 102 ° C., and a volume electric resistance of 10 ¹⁶ .
Table 2 shows the composition and characteristics of the obtained resin C.

<Manufacture of resin D>
The resin D was produced as follows.
-240 parts by weight of methyl methacrylate-60 parts by weight of styrene-300 parts by weight of benzene-0.6 parts by weight of azobisisobutyronitrile are heated and heated at 60 ° C for 6 hours for polymerization. The reaction product was dissolved in methyl ethyl ketone and precipitated with 7 times the amount of hexane to obtain Resin D. The obtained resin had a weight average molecular weight Mw = 105,000, a glass transition temperature of 99 ° C., and a volume electric resistance of 10 ¹⁶ .
Table 2 shows the composition and characteristics of the obtained resin D.

<Manufacture of resin E>
・ Add 170.0 parts by weight of BCF, 35.0 parts by weight of BPF, 66.4 parts by weight of terephthalic acid, 20.0 parts by weight of trimellitic anhydride, 0.65 parts by weight of DBSA, and stir at 120 ° C. for 6 hours. A polycondensation resin was obtained.
For 108.8 parts by weight of the resin obtained as described above,
-Add 300 parts by weight of benzene, heat to 60 ° C and shake for 6 hours for polymerization.
The reaction product was dissolved in methyl ethyl ketone and precipitated with 7 times the amount of hexane to obtain Resin E.
The obtained resin had a weight average molecular weight Mw = 56,000, a glass transition temperature of 101 ° C., and a volume electric resistance of 10 ¹⁶ .
Table 2 shows the composition and characteristics of the obtained resin E.

[Manufacture of carriers]
(Example 1: Production of carrier A)
-Core material A 100 parts by weight-Toluene 20 parts by weight-Resin A 3 parts by weight-Carbon black (VXC-72; manufactured by Cabot Corporation) 0.3 part by weight Of the above materials, after the resin A is diluted with toluene, Carbon black was added and stirred for 5 minutes with a homogenizer to prepare a resin solution. The resin solution and the core material A are put into a vacuum degassing kneader and stirred at 80 ° C. for 30 minutes, and then the pressure is reduced to remove toluene, and a film is formed on the surface of the ferrite particles. Obtained.

(Example 2: Production of carrier B)
Carrier B was obtained in the same manner as carrier A except that resin B was used instead of resin A.

(Example 3: Production of carrier C)
Carrier C was obtained in the same manner as carrier A, except that core B was used instead of core A and resin C was used instead of resin A.

(Example 4: Production of carrier D)
Carrier D was obtained in the same manner as carrier A, except that core B was used instead of core A, and the amount of resin A charged was changed from 3 parts by weight to 3.8 parts by weight.

(Example 5: Production of carrier E)
Carrier E was obtained in the same manner as carrier A, except that core B was used instead of core A, and the amount of resin A charged was changed from 3 parts by weight to 2.8 parts by weight.

(Example 6: Production of carrier F)
-Core material C 100 parts by weight-Toluene 20 parts by weight-Resin A 3 parts by weight-Carbon black (VXC-72; manufactured by Cabot Corporation) 0.3 part by weight Of the above materials, after the resin A is diluted with toluene, Carbon black was added and stirred for 5 minutes with a homogenizer to prepare a resin solution. The resin solution and the core material A are put into a vacuum degassing type kneader and stirred at 80 ° C. for 30 minutes, and then the pressure is reduced to remove toluene to form a film on the surface of the ferrite particles. Obtained.

(Example 7: Production of carrier G)
Core material D 100 parts by weight Toluene 20 parts by weight Resin B 2.8 parts by weight Carbon black (VXC-72; manufactured by Cabot Corporation) 0.3 part by weight Of the above materials, resin A was diluted with toluene After that, carbon black was added and stirred for 5 minutes with a homogenizer to prepare a resin solution. The resin solution and the core material A are put in a vacuum degassing kneader and stirred at 80 ° C. for 30 minutes, and then the pressure is reduced to remove toluene, and a film is formed on the surface of the ferrite particles. Obtained.

(Comparative Example 1: Production of carrier H)
Carrier H was obtained in the same manner as carrier A except that resin D was used instead of resin A.

(Comparative Example 2: Production of Carrier I)
Carrier I was obtained in the same manner as carrier A except that core B was used instead of core A and resin E was used instead of resin A.

(Comparative Example 3: Production of Carrier J)
A carrier J was obtained in the same manner as the carrier A except that the core material B was used instead of the core material A and the charge amount of the resin A was changed from 3 parts by weight to 2.5 parts by weight.

(Comparative Example 4: Production of carrier K)
The carrier B was obtained in the same manner as the carrier A by using the core B instead of the core A and setting the charge amount of the resin A to 3 parts by weight.

  Table 3 shows the core materials and resins used for the carriers produced in Examples 1 to 5 and Comparative Examples 1 to 3. Table 4 shows the coverage of each carrier.

[Production of Toner a]
<Manufacture of toner a>
・ Polyester resin (Bisphenol A and 1,3-propanediol copolymer, Mw = 60,000) 77 parts ・ Plant wax (carnauba wax) 6 parts ・ Aromatic hydrocarbon copolymer petroleum resin 7 parts ・ SiO ₂ Particles (R972; manufactured by Nippon Aerosil Co., Ltd.) 5 parts C.I. I. Pigment Blue 15: 3 5 parts Preliminarily mix each of the above components with a Henschel mixer, melt and knead with a twin-screw roll mill, cool and pulverize with a jet mill, and further classify twice with a wind classifier In addition, toner particles (cyan toner) having an average particle diameter of 6.5 μm and a toner particle number of 15% by number of particles having a particle diameter of 4 μm or less and 0.7 volume% of toner particles having a particle diameter of 16 μm or more were produced.
Toner particles a were prepared by mixing 100 parts of these particles, 0.5 parts of hydrophobic titanium oxide particles having a BET specific surface area of 100 m ² / g as external additives, and 40 nm of hydrophobic silica particles using a Henschel mixer.

[Manufacture of developer]
Developers A to H were obtained by mixing 92 parts by weight of the carrier (carriers A to H) produced above and 8 parts by weight of the toner a produced above.

〔Evaluation methods〕
Using these developers and the developer for supply, a remodeling machine of an electrophotographic copying machine / printer combined machine (manufactured by DocuCentreColor 400CP Fuji Xerox Co., Ltd.) is used, and developability, fog, and image quality are as follows. In addition, evaluation of potential unevenness due to carrier resin powder contamination on the charger was performed in a high temperature and high humidity environment (30 ° C., 80% RH) and a low temperature and low humidity environment (10 ° C., 10% RH).

<Developability, fog, image quality, evaluation of potential unevenness due to carrier resin powder adhering to charging roll>
In each environment, a solid patch of 5 cm × 2 cm is developed, and the developed toner image on the surface of the photoreceptor is transferred using the adhesiveness of the tape surface, and its weight (W1) is measured to determine the developability. evaluated.
Similarly, the background portion of the photosensitive member surface was transferred using the adhesiveness of the tape surface and attached to the surface of paper (J paper: manufactured by Fuji Xerox Office Supply Co., Ltd.), and fog and black spots were visually evaluated.
Further, the potential of the charging roll was measured, and the charging unevenness was measured.
Further, the above-mentioned photoreceptor fog at the time of the test was visually confirmed.

<Development evaluation criteria>
○: W1 is 4.5 g / m ² or more Δ: W1 is 4.0 g / m ² or more and less than 4.5 g / m ² ×: W1 is less than 4.0 g / m ²

<Fog / Image quality evaluation criteria>
Each developer is filled in a developing machine, set in the above-described modification machine, left in each environment overnight, and the density of the non-image area when a fine line image is printed is X-Rite 404A: (manufactured by X-Rite) The five points were measured using an average value.
Evaluation criteria for fog density in non-image areas are
◯: X-Rite measurement concentration is 0.01 or more, and no fog is visually observed.
(Triangle | delta): X-Rite measurement density | concentration exceeds 0.01 and is less than 0.02, and it cannot recognize fogging visually.
X: X-Rite measurement concentration is 0.02 or more, and fog can be recognized visually.

<Spots / Image quality evaluation criteria>
○: There is no black spot even when observed visually or with a magnifying glass.
Δ: Although it is difficult to identify black spots by visual observation, black spots are confirmed when observed with a magnifying glass.
X: There are black spots even visually.

<Evaluation criteria for charging unevenness>
○: No charging unevenness on the charging roll.
Δ: Charge unevenness is observed on the charging roll, but there is no problem in image quality.
X: The charging roll has uneven charging, and unevenness is also observed visually in the developed image.

After these evaluations were completed, 10,000 images were continuously printed in each environment so that an image with an image density of 1%: an image with an image density of 7% = 1: 1, and then the developability, fog, Image quality and potential unevenness due to carrier resin powder adhering to the charging roll were evaluated.
The results are shown in Table 5.

  As can be seen from these results, in this example, the environmental dependency such as temperature and humidity (particularly, the difference in charge amount between the high temperature and high humidity environment and the low temperature and low humidity environment) is smaller than that of the comparative example, and the coating resin layer Is difficult to peel off, and image formation can be performed stably over a long period of time.

1 is a cross-sectional view schematically showing a basic configuration of a preferred embodiment of an image forming apparatus of the present invention. It is sectional drawing which shows schematically the basic composition of other suitable one Embodiment of the image forming apparatus of this invention. It is sectional drawing which shows schematically the basic composition of other suitable one Embodiment of the image forming apparatus of this invention.

Explanation of symbols

10, 100, 200: Image forming apparatuses 12, 110, 212: Latent image holders 14, 120, 214: Charging means 16, 130, 216: Exposure means 18, 140, 218: Developing means 20, 220: Transfer means 26 180, 226: fixing means 28, 147: cartridge 141: developer container 146: developer supply means 148: developer discharge means 152: secondary transfer roller 210: process cartridge

Claims (10)

It is a particle in which a resin coating layer is formed on magnetic particles,
The resin coating layer includes a polyester resin obtained from a polyvalent carboxylic acid and a polyhydric alcohol,
The polyester resin has a monomer unit represented by the following formula (1) derived from the polyhydric alcohol in an amount of 5 mol% to 50 mol%,
A carrier for developing an electrostatic charge image, wherein a coating ratio of the resin coating layer to magnetic particles is 80% or more.

(In the formula (1), R ¹ , R ² , R ³ , R ⁴ , R ⁵ and R ⁶ each independently represents a substituent, and X and Y each independently represent a single bond or a divalent organic group. M and n each independently represent an integer of 0 or more and 4 or less.)   The electrostatic charge image developing carrier according to claim 1, wherein the resin coating layer contains conductive powder.   The metal particle-containing layer is provided between the magnetic particles and the resin coating layer, and the metal main composition of the magnetic particles and the metal oxide are different from each other. Carrier for developing an electrostatic image. The metal oxide has a higher insulating property than the metal main composition of the magnetic particles,
When the content ratio of the metal oxide in the magnetic particles is a (%) and the content ratio of the metal oxide in the layer containing the metal oxide is b (%),
b ≧ 50, and
4. The electrostatic charge image developing carrier according to claim 3, wherein (b / 1000) <a <(b / 10).   The carrier for developing an electrostatic charge image according to claim 3 or 4, wherein the metal oxide contains alumina.   An electrostatic charge image developer comprising the carrier for developing an electrostatic charge image according to any one of claims 1 to 5. A cartridge containing at least the carrier for developing an electrostatic charge image according to any one of claims 1 to 5 or the developer for developing an electrostatic charge image according to claim 6. Developing means for developing the electrostatic latent image formed on the latent image holding member with an electrostatic charge image developer according to claim 6 containing toner to form a toner image;
A process cartridge comprising: a latent image holding member; a charging unit that charges the latent image holding member; and at least one selected from the group consisting of a cleaning unit that removes toner remaining on the surface of the latent image holding member. A latent image carrier,
Charging means for charging the latent image carrier;
Exposure means for exposing the charged latent image carrier to form an electrostatic latent image on the latent image carrier;
Developing means for developing the electrostatic latent image with a developer containing toner to form a toner image;
Transfer means for transferring the toner image from the latent image holding member to a transfer target;
An image forming apparatus, wherein the developer includes the electrostatic charge image developing carrier according to claim 1. A latent image forming step for forming an electrostatic latent image on the surface of the latent image holding member;
A developing step of forming a toner image by developing the electrostatic latent image formed on the surface of the latent image holding member with a developer containing toner;
A transfer step of transferring the toner image formed on the surface of the latent image holding member to the surface of the transfer target; and
A fixing step of thermally fixing the toner image transferred to the surface of the transfer target,
An image forming method, wherein the developer comprises the carrier for developing an electrostatic image according to claim 1.

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