JP5614186B2 - Electrostatic latent image developer carrier and electrostatic latent image developer - Google Patents

Description

  The present invention relates to a carrier for developing an electrostatic latent image used in a two-component developer used in electrophotography and electrostatic recording, an electrostatic latent image developer, a color toner developer, and a replenishing development using the carrier. The present invention relates to an agent, an image forming method, a process cartridge including an electrostatic latent image developer, and an image forming apparatus.

In electrophotographic image formation, an electrostatic latent image is formed on an electrostatic latent image carrier such as a photoconductive substance, and a charged toner is attached to the electrostatic latent image to form a toner image. After that, the toner image is transferred to a recording medium and fixed to form an output image. In recent years, the technology of copying machines and printers using an electrophotographic system is rapidly expanding from monochrome to full color, and the full color market tends to expand.
In full-color image formation, generally, color toners of three colors of yellow, magenta, and cyan or four color toners obtained by adding black to this are laminated to reproduce all colors. Therefore, in order to obtain a clear full color image with excellent color reproducibility, it is necessary to smooth the surface of the fixed toner image to reduce light scattering. For these reasons, the image gloss of conventional full-color copying machines and the like is often 10 to 50% of medium to high gloss.

In general, as a method for fixing a dry toner image on a recording medium, a contact heating fixing method in which a roller or belt having a smooth surface is heated and pressed against the toner is frequently used. Such a method has high thermal efficiency and enables high-speed fixing, and can give gloss and transparency to the color toner. On the other hand, the surface of the heat-fixing member is brought into contact with the molten toner under pressure. Then, in order to peel off, a so-called offset phenomenon occurs in which a part of the toner image adheres to the surface of the fixing roller and is transferred onto another image.
In order to prevent such an offset phenomenon, the surface of the fixing roller is formed of silicone rubber or fluorine resin having excellent releasability, and further, an oil for preventing toner adhesion such as silicone oil is applied to the surface of the fixing roller. This method is generally adopted. However, such a method is extremely effective in preventing toner offset, but requires a device for supplying oil, and there is a problem that the fixing device is increased in size.

For this reason, in monochrome image formation, an oilless system in which viscoelasticity at the time of melting is large and toner containing a release agent is used so that the melted toner does not break internally, so that no oil is applied to the fixing roller, or There is a tendency to adopt a system in which a small amount of oil is applied.
On the other hand, in full-color image formation, as in the case of monochrome image formation, an oilless system tends to be employed for the purpose of downsizing the fixing device and simplifying the configuration. However, in full-color image formation, it is necessary to reduce the viscoelasticity of the toner at the time of melting in order to smooth the surface of the fixed toner image. This makes it difficult to adopt an oilless system. Further, when a toner containing a release agent is used, adhesion of the toner is increased and transferability to a recording medium is decreased. Furthermore, there is a problem in that the durability is lowered due to the occurrence of toner filming and a decrease in chargeability.

On the other hand, in the carrier, prevention of toner filming, formation of a uniform surface, prevention of surface oxidation, prevention of decrease in moisture sensitivity, extension of developer life, prevention of adhesion to the surface of the photoreceptor, photosensitivity The length of the carrier can be increased by coating the surface of the carrier core with a resin having a low surface energy, such as a fluororesin or a silicone resin, for the purpose of protecting the body from scratches or abrasion, controlling the charge polarity, and adjusting the charge amount. Life has been extended.
As an example of a carrier coated with a low surface energy resin, a carrier coated with a room temperature curable silicone resin and a positively chargeable nitrogen resin disclosed in Patent Document 1 (Japanese Patent Laid-Open No. 55-127469), Patent Document 2 A carrier coated with a coating material containing at least one modified silicone resin disclosed in JP-A-55-157751 and a room-temperature curable type disclosed in JP-A-56-140358 A carrier having a resin coating layer containing a silicone resin and a styrene / acrylic resin, the core particle surface disclosed in Patent Document 4 (Japanese Patent Laid-Open No. 57-96355) is coated with two or more layers of silicone resin, A carrier made to be non-adhesive, the surface disclosed in Patent Document 5 (JP 57-96356 A) is crosslinked with isocyanate A carrier surface-treated or coated with the polyvinyl acetal resin prepared, a carrier whose surface is coated with a silicone resin containing silicon carbide disclosed in Patent Document 6 (Japanese Patent Laid-Open No. 58-207054), Patent Document 7 A positively chargeable carrier coated with a material exhibiting a critical surface tension of 20 dyn / cm or less disclosed in Japanese Laid-Open Patent Publication No. 61-110161), and a fluorine alkyl disclosed in Patent Document 8 (Japanese Patent Laid-Open No. 62-273576) Examples thereof include a carrier coated with a coating material containing acrylate.
However, in recent years, there has been a tendency for the toner to have a smaller particle size in order to improve the image quality, and with the increase in printing speed, toner spent on the carrier is more likely to occur. Furthermore, in the case of a developer in which maintenance is facilitated by adding a wax to the toner, the amount of toner spent is very large, the toner charge amount is reduced, the margin for toner scattering and background contamination is reduced, and the carrier Charging, resistance adjustment, and durability improvement are important.

  In a full-color electrophotographic system, when the toner spent on the carrier or the coating film is scraped or peeled off, the carrier resistance and the developer pumping amount change, and the image density, especially the density in the highlight area, changes, and high image quality cannot be maintained. This is the current situation, and color stains occur due to the removal of the filler due to scraping of the coating, and so high quality cannot be maintained with the color toner. In order to solve such problems, white conductive fine particles have been added to the resin coating the carrier. As the white conductive fine particles, for example, the surface of inorganic pigment particles disclosed in Patent Document 9 (JP-A-6-338213) and Patent Document 10 (JP-A-7-14430) is coated with tin dioxide, Examples thereof include white conductive powder coated with an indium oxide layer containing tin dioxide. However, the carrier whose resistance is adjusted with these white conductive powders has a problem that the durability is not sufficient and the charge imparting ability is lowered by long-term use. It is not only the charge imparting ability that decreases, but also there is a problem that the resistance decreases due to film scraping and carrier adhesion. In order to solve this problem, for example, Patent Document 11 (Japanese Patent Laid-Open No. 7-160059) describes that coating can be performed in anticipation of a decrease in resistance due to film shaving by giving a characteristic to the coating process. . However, the problem with this method is the resin used. In the method described in Patent Document 11, a coating liquid containing a silicone-based resin is used. However, when a plurality of coating liquids are used, a portion where bonding at the interface is weak occurs, resulting in a decrease in strength of the entire film. As a result, there is a problem that the life as a developer or carrier is shortened.

An object of the present invention is to solve the aforementioned problems. That is, the object of the present invention is to have a stable charging ability over a long period of time, excellent in both hardness and toughness (flexibility / elasticity) of the coating, and excellent in wear resistance (scraping / peeling), Little change in carrier resistance, little fluctuation in charging due to spent toner composition, and suppression of fluctuations in charging environment, no fluctuations in image density, background contamination, and in-machine contamination due to toner scattering in various usage environments It is an object of the present invention to provide a carrier for developing an electrostatic latent image that satisfies the various characteristics.
It is another object of the present invention to provide an electrostatic latent image developer, an image forming apparatus, a process cartridge, and an image forming apparatus using the electrostatic latent image developer carrier.

The present inventors have a component A having a specific acrylic siloxane structure part containing a repellency group (and a monomer A component therefor; the same applies hereinafter) represented by the general formula (A) described later; And a resin comprising a B component (and a monomer B component for the same, the same applies hereinafter) which is a specific acrylic silicon component having a dehydrating-condensable silanol group or silanol precursor group structure portion represented by the general formula (B) In the electrostatic latent image developer carrier, the carrier for electrostatic latent image developer comprising core particles and a resin layer covering the surface of the core particles coated and heated in a plurality of stages. The present inventors have found that the various characteristics are more fully satisfied, and have completed the present invention.
Thus, according to the present invention, there are provided the following carrier for electrostatic latent image developer, developer, image forming apparatus, process cartridge, and image forming apparatus.

（式中、Ｒ ^１ は水素原子又はメチル基を、Ｒ ^２ は炭素数１〜４のアルキル基を、Ｒ ^３ は炭素数１〜８のアルキル基又は炭素数１〜４のアルコキシ基を、ｍは１〜８の整数を示す。複数のＲ ^２ は同一でも異なっていてもよい。Ｘは１０〜９０モル％を、Ｙは９０〜１０モル％を示す。）
２．本発明の静電潜像現像剤用キャリアは、さらに、前記導電性微粒子が、アルミナを含む基体の表面に導電性被覆層を有する粒子であることを特徴とする。
３．本発明の静電潜像現像剤用キャリアは、さらに、前記導電性微粒子の導電性被覆層が、少なくとも二酸化スズを含むことを特徴とする。
４．本発明の静電潜像現像剤用キャリアは、さらに、前記導電性微粒子が、二酸化スズを４〜８０質量％含むことを特徴とする。
５．本発明の静電潜像現像剤用キャリアは、さらに、前記導電性被覆層が、少なくとも二酸化スズ及び酸化インジウムを含むことを特徴とする。
６．本発明の静電潜像現像剤用キャリアは、さらに、前記共重合体は、下記一般式（１）で表される共重合体を含むことを特徴とする。

（式中、Ｒ ^１ は水素原子又はメチル基を、Ｒ ^２ は炭素数１〜４のアルキル基を、Ｒ ^３ は炭素数１〜８のアルキル基又は炭素数１〜４のアルコキシ基を、ｍは１〜８の整数を示す。複数のＲ ^１ 及びＲ ^２ は、それぞれ同一でも異なっていてもよい。Ｘは１０〜４０モル％を、Ｙは１０〜４０モル％を、Ｚは３０〜８０モル％を示し、６０モル％＜Ｙ＋Ｚ＜９０モル％である。）
７．本発明の静電潜像現像剤用キャリアは、さらに、前記樹脂層による前記芯材粒子の被覆が、前記樹脂及び導電性微粒子を含むコート液で前記芯材粒子をコートすることによって行われ、少なくとも、前記コート液が、導電性微粒子含有率の異なる二種以上のコート液であることを特徴とする。
８．本発明の静電潜像現像剤用キャリアは、さらに、前記導電性微粒子含有率の異なる二種以上のコート液それぞれにより前記芯材粒子がコートされる時間は、そのコート時間が最短のコート液のコート時間に対して他のコート液によるコート時間が１〜１０倍であることを特徴とする。
９．本発明の静電潜像現像剤用キャリアは、さらに、前記導電性微粒子含有率の異なる二種以上のコート液それぞれにより前記芯材粒子がコートされる際に供給される前記コート液の単位時間当たりの液滴量は、その液滴量が最少のコート液の液滴量に対して他のコート液の液滴量が１〜１０倍であることを特徴とする。 That is, the said subject is solved by the following 1-27.
1. The carrier for an electrostatic latent image developer of the present invention is a carrier for electrostatic latent image developer comprising magnetic core material particles and a resin layer covering the surface of the core material particles, wherein the resin layer comprises: A resin obtained by heat-treating a copolymer containing at least the component A represented by the following general formula (A) and the component B represented by the following general formula (B), and conductive fine particles, It is characterized in that the concentration of the conductive fine particles in the resin layer becomes higher as it is closer to the surface of the resin layer.

( Wherein R ¹ represents a hydrogen atom or a methyl group, R ² represents an alkyl group having 1 to 4 carbon atoms, R ³ represents an alkyl group having 1 to 8 carbon atoms or an alkoxy group having 1 to 4 carbon atoms, m Represents an integer of 1 to 8. A plurality of R ² may be the same or different, X represents 10 to 90 mol%, and Y represents 90 to 10 mol%.)
2. The carrier for an electrostatic latent image developer of the present invention is further characterized in that the conductive fine particles are particles having a conductive coating layer on the surface of a substrate containing alumina.
3. The carrier for an electrostatic latent image developer of the present invention is further characterized in that the conductive coating layer of the conductive fine particles contains at least tin dioxide.
4). The carrier for an electrostatic latent image developer of the present invention is further characterized in that the conductive fine particles contain 4 to 80% by mass of tin dioxide.
5. The carrier for an electrostatic latent image developer of the present invention is further characterized in that the conductive coating layer contains at least tin dioxide and indium oxide.
6). The carrier for an electrostatic latent image developer of the present invention is further characterized in that the copolymer contains a copolymer represented by the following general formula (1).

( Wherein R ¹ represents a hydrogen atom or a methyl group, R ² represents an alkyl group having 1 to 4 carbon atoms, R ³ represents an alkyl group having 1 to 8 carbon atoms or an alkoxy group having 1 to 4 carbon atoms, m Represents an integer of 1 to 8. The plurality of R ¹ and R ² may be the same or different, X is 10 to 40 mol%, Y is 10 to 40 mol%, and Z is 30 to 80 Mol%, 60 mol% <Y + Z <90 mol%)
7). In the carrier for an electrostatic latent image developer of the present invention, the coating of the core material particles with the resin layer is further performed by coating the core material particles with a coating liquid containing the resin and conductive fine particles. At least the coating liquid is two or more kinds of coating liquids having different conductive fine particle contents.
8). The carrier for an electrostatic latent image developer according to the present invention further includes a coating solution in which the core material particles are coated with each of the two or more coating solutions having different conductive fine particle contents. The coating time with the other coating liquid is 1 to 10 times the coating time.
9. The electrostatic latent image developer carrier according to the present invention further includes a unit time of the coating liquid supplied when the core material particles are coated with each of the two or more coating liquids having different conductive fine particle contents. The hit droplet amount is characterized in that the droplet amount of the other coating liquid is 1 to 10 times the droplet amount of the coating liquid having the smallest droplet amount.

10. In the carrier for an electrostatic latent image developer of the present invention, the coating of the core material particles with the resin layer is further performed by coating the core material particles with a coating liquid containing the resin and conductive fine particles. At least the coating liquid is two or more kinds of coating liquids having different powder specific resistances of conductive fine particles.
11. The carrier for an electrostatic latent image developer of the present invention further has the shortest coating time of the core material particles coated with each of two or more coating liquids having different powder specific resistances of the conductive fine particles. The coating time of the other coating liquid is 1 to 10 times the coating time of the coating liquid.
12 The carrier for an electrostatic latent image developer according to the present invention further includes the coating liquid supplied when the core particles are coated with each of two or more coating liquids having different powder specific resistances of the conductive fine particles. The droplet amount per unit time is characterized in that the droplet amount of the other coating liquid is 1 to 10 times the droplet amount of the coating liquid having the smallest droplet amount.
13. The carrier for an electrostatic latent image developer of the present invention further has a powder specific resistance of conductive fine particles contained in each of two or more kinds of coating liquids having different powder specific resistances of the conductive fine particles. The powder specific resistance of other conductive fine particles is 1 to 10 ⁴ times the powder specific resistance of the conductive fine particles having the smallest resistance.
14 The carrier for an electrostatic latent image developer of the present invention is further obtained by coating the resin layer and then heat-treating, and the heat treatment temperature during the heat-treatment is 100 to 350 ° C. To do.
15. The carrier for an electrostatic latent image developer of the present invention is further characterized by having a volume resistivity of 1 × 10 ⁷ to 1 × 10 ¹⁷ Ω · cm.
16. The carrier for an electrostatic latent image developer of the present invention is further characterized in that the resin layer has an average film thickness of 0.05 to 4 μm.
17. The carrier for an electrostatic latent image developer according to the present invention is further characterized in that the core particles have a weight average particle diameter of 20 to 65 μm.
18. The carrier for an electrostatic latent image developer of the present invention is further characterized in that the magnetization in a magnetic field of 1 kOe is 40 to 90 Am ² / kg.
19. The electrostatic latent image developer of the present invention is a developer for developing an electrostatic latent image comprising a toner and a carrier, and the carrier for the electrostatic latent image developer is used as the carrier.
20. The electrostatic latent image developer of the present invention is further characterized in that the toner is a color toner.

21. The replenishment developer of the present invention is a replenishment developer containing 2 to 50 parts by mass of toner with respect to 1 part by mass of the carrier, and the carrier is the electrostatic latent image developer carrier. It is characterized by that.
22. The image forming apparatus of the present invention includes an electrostatic latent image carrier, charging means for charging the electrostatic latent image carrier, and exposure means for forming an electrostatic latent image on the charged electrostatic latent image carrier. Developing means for developing the electrostatic latent image formed on the electrostatic latent image carrier using a developer to form a toner image; and transfer means for transferring the toner image to a recording medium; In the image forming apparatus including a fixing unit that fixes the toner image transferred to the recording medium, the developing unit uses the developer.
23. The process cartridge of the present invention develops an electrostatic latent image carrier, charging means for charging the surface of the electrostatic latent image carrier, and an electrostatic latent image formed on the electrostatic latent image carrier. A process cartridge that is integrally supported by a developing unit that forms a toner image by developing using an agent and a cleaning unit that cleans the electrostatic latent image carrier, and is detachable from the main body of the image forming apparatus; The developing means uses the developer.
24. The image forming method of the present invention includes a step of forming an electrostatic latent image on an electrostatic latent image carrier and an electrostatic latent image formed on the electrostatic latent image carrier using the developer. A step of developing to form a toner image, a step of transferring the toner image formed on the electrostatic latent image carrier to a recording medium, and a step of fixing the toner image transferred to the recording medium. It is characterized by that.

According to the present invention, a tough film is formed by a silane-based cross-linking component having a small surface energy and conductive fine particles, and the resistance is adjusted in anticipation of scraping and excellent in long-term charging stability, It is difficult to change the carrier resistance and the amount of developer to be pumped, the film is not scraped or peeled off, the resistance when scraped is very stable, and a highly durable carrier with little toner spent and developer can be obtained. it can.
Furthermore, the fluctuation of charging environment is suppressed, and the image density fluctuation, background stain, and in-machine contamination due to toner scattering do not occur in various usage environments.
In addition, a highly reliable development method and an image forming apparatus can be provided.

It is a figure which shows the cell used when measuring the powder specific resistance of resin fine particles. FIG. 2 is a schematic diagram for explaining a developing unit of the image forming method and the image forming apparatus of the present invention. 1 is a schematic diagram illustrating an example of a configuration of an image forming apparatus of the present invention. It is the schematic which shows the other example of a structure of the image forming apparatus of this invention. It is the schematic which shows an example of a structure of the process cartridge of this invention. It is a figure which shows the cell used when measuring the volume specific resistance of the carrier of this invention. FIG. 6 is a schematic diagram for explaining a method for measuring a charge amount of toner.

EMBODIMENT OF THE INVENTION Below, the form for implementing this invention is demonstrated based on drawing. Note that it is easy for a person skilled in the art to make other embodiments by changing or correcting the present invention within the scope of the claims, and these changes and modifications are included in the scope of the claims. The following description is an example of an embodiment of the present invention, and does not limit the scope of the claims.
The carrier for an electrostatic latent image developer of the present invention comprises an A component represented by the following general formula (A) (and a monomer A component therefor; the same applies hereinafter) and a B component represented by the following general formula (B) ( And coating the surface of the core particle with a resin layer containing a (meth) acrylic copolymer obtained by radical copolymerization with the monomer B component and the same below) and conductive fine particles, followed by heat treatment The resulting electrostatic latent image developing carrier.

式中、Ｒ^１は水素原子又はメチル基を示す。Ｒ^２は炭素数１〜４のアルキル基を示し、アルキル基としては、メチル基、エチル基、プロピル基、イソプロピル基及びブチル基等が挙げられる。ｍは１〜８の整数を示し、（ＣＨ）_ｍで表されるアルキレン基としては、メチレン基、エチレン基、プロピレン基、ブチレン基等が挙げられる。複数のＲ^２は同一でも異なっていてもよい。

In the formula, R ¹ represents a hydrogen atom or a methyl group. R ² represents an alkyl group having 1 to 4 carbon atoms, and examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, and a butyl group. m represents an integer of 1 to 8, and the alkylene group represented by (CH) _m includes a methylene group, an ethylene group, a propylene group, a butylene group, and the like. A plurality of R ² may be the same or different.

  In the component A, X is 10 to 90 mol%, preferably 10 to 40 mol%, more preferably 20 to 30 mol%. The A component has an atomic group having a large number of methyl groups in the side chain and tris (trimethylsiloxy) silane. When the ratio of the A component to the entire resin increases, the surface energy decreases, and the resin component of the toner. , Adhesion of wax components and the like is reduced. If the A component is less than 10 mol%, a sufficient effect cannot be obtained, and the adhesion of the toner component increases rapidly. On the other hand, if it exceeds 90 mol%, the amount of the B component will decrease, so that the crosslinking will not proceed, the toughness will be insufficient, the adhesion between the core material and the resin layer will be lowered, and the durability of the carrier coating will be reduced. Becomes worse.

Examples of the monomer A component that generates such an A component include a tris (trialkylsiloxy) silane compound represented by the following formula. In the formula, Me is a methyl group, Et is an ethyl group, and Pr is a propyl group.
_{CH 2 = CMe-COO-C} 3 H 6 -Si (OSiMe 3) 3
_{CH 2 = CH-COO-C} 3 H 6 -Si (OSiMe 3) 3
_{CH 2 = CMe-COO-C} 4 H 8 -Si (OSiMe 3) 3
_{CH 2 = CMe-COO-C} 3 H 6 -Si (OSiEt 3) 3
_{CH 2 = CH-COO-C} 3 H 6 -Si (OSiEt 3) 3
_{CH 2 = CMe-COO-C} 4 H 8 -Si (OSiEt 3) 3
_{CH 2 = CMe-COO-C} 3 H 6 -Si (OSiPr 3) 3
_{CH 2 = CH-COO-C} 3 H 6 -Si (OSiPr 3) 3
_{CH 2 = CMe-COO-C} 4 H 8 -Si (OSiPr 3) 3
The production method of the monomer A component for the A component is not particularly limited, but a method of reacting tris (trialkylsiloxy) silane with allyl acrylate or allyl methacrylate in the presence of a platinum catalyst, or JP-A-11-217389. It can be obtained by a method of reacting methacryloxyalkyltrialkoxysilane and hexaalkyldisiloxane in the presence of a carboxylic acid and an acid catalyst. The said silane compound may be used individually by 1 type, and may use 2 or more types of mixtures.

式中、Ｒ^１、Ｒ^２及びｍは、前記一般式（Ａ）において説明したものと同様である。Ｒ^３は炭素数１〜８のアルキル基又は炭素数１〜４のアルコキシ基を示し、アルキル基としては上述したものと同様のものが挙げられる。アルコキシ基としては、メトキシ基、エトキシ基、プロポキシ基、ブトキシ基等が挙げられる。
Ｂ成分において、Ｙは１０〜９０モル％であり、好ましくは１０〜８０モル％であり、より好ましくは１５〜７０モル％である。Ｂ成分が１０モル％未満であると、十分な強靭さが得られない。一方、９０モル％より多いと、被膜は固くて脆くなり、膜削れが発生し易くなる。また、環境特性が悪化する。加水分解した架橋成分がシラノール基として多数残り、環境特性（湿度依存性）を悪化させることも考えられる。 B component is a crosslinking component and is represented by the following general formula (B).

In the formula, R ¹ , R ² and m are the same as those described in the general formula (A). R ³ represents an alkyl group having 1 to 8 carbon atoms or an alkoxy group having 1 to 4 carbon atoms, and examples of the alkyl group include those described above. Examples of the alkoxy group include a methoxy group, an ethoxy group, a propoxy group, and a butoxy group.
In B component, Y is 10-90 mol%, Preferably it is 10-80 mol%, More preferably, it is 15-70 mol%. If the B component is less than 10 mol%, sufficient toughness cannot be obtained. On the other hand, when it exceeds 90 mol%, the coating becomes hard and brittle, and film scraping tends to occur. Moreover, environmental characteristics deteriorate. It is also conceivable that a large number of hydrolyzed crosslinking components remain as silanol groups, thereby deteriorating environmental characteristics (humidity dependency).

The monomer B component (including the precursor) that generates such a B component is a radically polymerizable bifunctional (when R ³ is an alkyl group) or trifunctional (when R ³ is also an alkoxy group) silane compound It is.
Examples of the monomer B component include 3-methacryloxypropyltrimethoxysilane, 3-acryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltriethoxysilane, and 3-methacryloxypropyl. Examples include methyldimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltri (isopropoxy) silane, and 3-acryloxypropyltri (isopropoxy) silane. These compounds may be used alone or in a mixture of two or more.

  As a technique for improving durability by crosslinking a coating, for example, there is a technique described in Japanese Patent No. 3691115. The carrier described in Japanese Patent No. 3691115 has at least one functional group selected from the group consisting of an organopolysiloxane having at least a vinyl group at the terminal, a hydroxyl group, an amino group, an amide group, and an imide group on the surface of the magnetic particles. A carrier for developing an electrostatic image, characterized in that a copolymer with a radical copolymerizable monomer having a group is coated with a thermosetting resin crosslinked with an isocyanate compound. In the present situation, sufficient durability is not obtained.

The reason is not sufficiently clear, but in the case of a thermosetting resin obtained by crosslinking the copolymer with an isocyanate compound, as can be seen from the structural formula, the isocyanate compound in the copolymer resin and There are few functional groups (amino group, hydroxy group, carboxy group, mercapto group and other active hydrogen-containing groups) per unit mass to react (crosslink), and form a two-dimensional or three-dimensional dense crosslinked structure at the crosslinking point. Therefore, if it is used for a long time, the film is easily peeled off or scraped off (the abrasion resistance of the film is small), and it is assumed that sufficient durability is not obtained.
When the film is peeled off or scraped off, the image quality changes due to a decrease in carrier resistance and carrier adhesion occurs. In addition, peeling or scraping of the coating reduces the fluidity of the developer and causes a decrease in the amount of pumping, which causes ground contamination and toner scattering due to a decrease in image density and toner density (TC).

In the present invention, a copolymer having a large number of bifunctional or trifunctional crosslinkable functional groups (points) per unit mass of the resin (2 to 3 times greater per unit mass) is used. Further, since the resin layer is crosslinked by condensation polymerization, it is considered that the coating is extremely tough and difficult to scrape, and high durability is achieved.
Further, it is presumed that the aging stability of the coating is maintained since the crosslinking by the siloxane bond in the present invention has a larger binding energy and is more stable against heat stress than the crosslinking by the isocyanate compound.

式中、Ｒ^１は水素原子又はメチル基を示す。Ｒ^２は炭素数１〜４のアルキル基を示し、アルキル基としては、メチル基、エチル基、プロピル基、イソプロピル基及びブチル基等が挙げられる。Ｒ^３は炭素数１〜８のアルキル基又は炭素数１〜４のアルコキシ基を示し、アルキル基としては上述したものと同様のものが挙げられる。アルコキシ基としては、メトキシ基、エトキシ基、プロポキシ基、ブトキシ基等が挙げられる。ｍは１〜８の整数を示し、（ＣＨ）_ｍで表されるアルキレン基としては、メチレン基、エチレン基、プロピレン基、ブチレン基等が挙げられる。複数のＲ^１及びＲ^２は、それぞれ同一でも異なっていてもよい。
前記一般式（１）で表される共重合体において、Ｘは１０〜４０モル％であり、好ましくは２０〜３０モル％である。Ｙは１０〜４０モル％であり、好ましくは１５〜２５モル％である。Ｚは３０〜８０モル％であり、好ましくは３５〜７５モル％である。ＹとＺの合計は、６０モル％＜Ｙ＋Ｚ＜９０モル％であり、好ましくは７０モル％＜Ｙ＋Ｚ＜８５モル％である。Ｃ成分が８０モル％より多くなると、Ｘ及びＹのいずれかが１０モル％以下となるため、キャリア被膜の撥水性、硬さと可とう性（膜削れ）を両立させることが難しくなる。 In the present invention, in order to provide sufficient flexibility and to improve the adhesion between the core material and the resin layer, and between the resin layer and the conductive fine particles, it is further represented by the following general formula (C). C component can be contained in the resin layer. That is, a copolymer represented by the following general formula (1) can be contained in the resin layer.

In the formula, R ¹ represents a hydrogen atom or a methyl group. R ² represents an alkyl group having 1 to 4 carbon atoms, and examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, and a butyl group. R ³ represents an alkyl group having 1 to 8 carbon atoms or an alkoxy group having 1 to 4 carbon atoms, and examples of the alkyl group include those described above. Examples of the alkoxy group include a methoxy group, an ethoxy group, a propoxy group, and a butoxy group. m represents an integer of 1 to 8, and the alkylene group represented by (CH) _m includes a methylene group, an ethylene group, a propylene group, a butylene group, and the like. A plurality of R ¹ and R ² may be the same or different.
In the copolymer represented by the general formula (1), X is 10 to 40 mol%, preferably 20 to 30 mol%. Y is 10 to 40 mol%, preferably 15 to 25 mol%. Z is 30 to 80 mol%, preferably 35 to 75 mol%. The sum of Y and Z is 60 mol% <Y + Z <90 mol%, preferably 70 mol% <Y + Z <85 mol%. If the C component is more than 80 mol%, either X or Y will be 10 mol% or less, and it will be difficult to achieve both water repellency, hardness and flexibility (film scraping) of the carrier film.

The monomer C component which produces C component is a radically polymerizable (meth) acrylic compound (monomer) having an acryloyl group or a methacryloyl group.
As such a (meth) acrylic compound, acrylic acid ester and methacrylic acid ester are preferable. Specifically, methyl methacrylate, methyl acrylate, ethyl methacrylate, ethyl acrylate, butyl methacrylate, butyl acrylate, 2- (dimethylamino) ) Ethyl methacrylate, 2- (dimethylamino) ethyl acrylate, 3- (dimethylamino) propyl methacrylate, 3- (dimethylamino) propyl acrylate, 2- (diethylamino) ethyl methacrylate and 2- (diethylamino) ethyl acrylate The
Of these, alkyl methacrylate is preferable, and methyl methacrylate is particularly preferable. These compounds may be used alone or in a mixture of two or more.

The copolymer in the present invention is a (meth) acrylic copolymer obtained by radical copolymerization of each monomer containing the A component and the B component, and has many crosslinkable functional groups per unit mass of the resin. In addition to this, since the B component which is a crosslinking component is subjected to condensation polymerization by heat treatment and crosslinked, it is considered that the resin layer is extremely tough and difficult to scrape, thereby achieving high durability.
In addition, it is surmised that the cross-linking by the siloxane bond in the present invention has higher binding energy and is more stable against heat stress than the cross-linking by the isocyanate compound, so that the stability of the resin layer with time is maintained. .

In the present invention, the resin layer composition for forming the resin layer preferably includes a silicone resin having a silanol group and / or a functional group capable of generating a silanol group by hydrolysis. .
A silicone resin having a silanol group and / or a functional group capable of generating a silanol group by hydrolysis (eg, a negative group such as an alkoxy group or a halogeno group bonded to a Si atom) is a copolymer of the above-mentioned copolymer It can be polycondensed with the B component directly or with the B component in a state of being converted to a silanol group. The toner spent property is further improved by adding a silicone resin component to the copolymer.

式中、Ａ^１は、水素原子、ハロゲン原子、ヒドロキシ基、メトキシ基、炭素数１〜４のアルキル基又はアリール基を示し、Ａ^２は、炭素数１〜４のアルキレン基又はアリーレン基を示す。 In the present invention, a silicone resin having a silanol group used when forming a resin layer and / or a functional group capable of generating a silanol group by hydrolysis is represented by the following general formula (2). It preferably contains at least one repeating unit.

In the formula, A ¹ represents a hydrogen atom, a halogen atom, a hydroxy group, a methoxy group, an alkyl group having 1 to 4 carbon atoms or an aryl group, and A ² represents an alkylene group having 1 to 4 carbon atoms or an arylene group. .

Examples of the halogen atom include fluorine, chlorine, bromine and iodine. Examples of the alkyl group having 1 to 4 carbon atoms include methyl group, ethyl group, propyl group, isopropyl group, and butyl group. Examples of the aryl group include a phenyl group and a tolyl group. Examples of the alkylene group having 1 to 4 carbon atoms include a methylene group, an ethylene group, a propylene group, and a butylene group. Examples of the arylene group include a phenylene group and a naphthylene group.
In the aryl group, the carbon number is 6 to 20, preferably 6 to 14. This aryl group includes an aryl group derived from benzene (phenyl group), an aryl group derived from a condensed polycyclic aromatic hydrocarbon such as naphthalene, phenanthrene and anthracene, and a chain polycyclic aromatic such as biphenyl and terphenyl. An aryl group derived from a group hydrocarbon is included. The aryl group may be substituted with various substituents.

  The carbon number of the arylene group is 6 to 20, preferably 6 to 14. The arylene group includes an arylene group derived from benzene (phenylene group), an arylene group derived from a condensed polycyclic aromatic hydrocarbon such as naphthalene, phenanthrene, and anthracene, and a chain polycyclic aromatic such as biphenyl and terphenyl. An arylene group derived from a group hydrocarbon is included. The arylene group may be substituted with various substituents.

  Although it does not specifically limit as a commercial item of the silicone resin which can be used for this invention, KR251, KR271, KR272, KR282, KR252, KR255, KR152, KR155, KR211, KR216 (above, Shin-Etsu Silicone company make), AY42- 170, SR2510, SR2400, SR2406, SR2410, SR2405 and SR2411 (manufactured by Toray Dow Corning).

As described above, various silicone resins can be used. Among them, methyl silicone resin is particularly preferable because of low toner spent property and small environmental fluctuation of charge amount.
The weight average molecular weight of the silicone resin is about 1,000 to 100,000, preferably about 1,000 to 30,000. When the molecular weight of the resin to be used is larger than 100,000, the viscosity of the coating solution increases excessively at the time of coating, and the coating film uniformity may not be sufficiently obtained, or the density of the resin layer may not be sufficiently increased after curing. If it is less than 1,000, problems such as brittleness of the cured resin layer tend to occur.
As a content rate of a silicone resin, it is about 5-80 mass parts normally with respect to 100 mass parts of said copolymers, Preferably it is 10-60 mass parts. When the content ratio of the silicone resin is less than 5 parts by mass, an improvement effect such as spent property cannot be obtained. When the content is more than 80 parts by mass, the toughness of the resin layer is insufficient and the film is easily scraped.

In the present invention, a silane coupling agent can also be used to improve the dispersibility of the conductive fine particles and adjust the toner charge amount.
In particular, for the silicone resin, an appropriate amount of the aminosilane coupling agent shown below for adjusting the toner charge amount (0.001 to 30 parts by mass, preferably 0.1 to 20 parts by mass with respect to 100 parts by mass of the silicone resin). Part) it is effective to contain.
H ₂ N (CH ₂ ) ₃ Si (OCH ₃ ) ₃
MW = 179.3
H ₂ N (CH ₂ ) ₃ Si (OC ₂ H ₅ ) ₃ MW = 221.4
H ₂ NCH ₂ CH ₂ CH ₂ Si (CH ₃ ) ₂ (OC ₂ H ₅ ) MW = 161.3
H ₂ NCH ₂ CH ₂ CH ₂ Si (CH ₃ ) (OC ₂ H ₅ ) ₂ MW = 191.3
H ₂ NCH ₂ CH ₂ NHCH ₂ Si (OCH ₃ ) ₃ MW = 194.3
H ₂ NCH ₂ CH ₂ NHCH ₂ CH ₂ CH ₂ Si (CH ₃ ) (OCH ₃ ) ₂ MW = 206.4
H ₂ NCH ₂ CH ₂ NHCH ₂ CH ₂ CH ₂ Si (OCH ₃ ) ₃ MW = 224.4
(CH ₃ ) ₂ NCH ₂ CH ₂ CH ₂ Si (CH ₃ ) (OC ₂ H ₅ ) ₂ MW = 219.4
(C ₄ H ₉ ) ₂ NC ₃ H ₆ Si (OCH ₃ ) ₃
MW = 291.6

Further, the resin layer composition according to the present invention can also contain a resin other than the silicone resin having a silanol group and / or a hydrolyzable functional group, and such a resin is not particularly limited. Acrylic resin, amino resin, polyvinyl resin, polystyrene resin, halogenated olefin resin, polyester resin, polycarbonate resin, polyethylene resin, polyvinyl fluoride resin, polyvinylidene fluoride resin, polytrifluoroethylene resin, polyhexafluoropropylene resin, Copolymers of vinylidene fluoride and vinyl fluoride, fluoroterpolymers such as terpolymers of tetrafluoroethylene, vinylidene fluoride and non-fluorinated monomers, silicone resins having no silanol groups or hydrolyzable functional groups, etc. Is mentioned. Two or more of these may be used in combination. Among them, an acrylic resin is preferable because it has high adhesion to the core particles and conductive fine particles and low brittleness.
The acrylic resin preferably has a glass transition point of 20 to 100 ° C, more preferably 25 to 80 ° C. Since such an acrylic resin has an appropriate elasticity, when the developer is triboelectrically charged, a shock is applied to the resin layer due to the friction between the toner and the carrier or the friction between the carriers. It can be absorbed and deterioration of the resin layer and the conductive fine particles can be prevented.

The resin layer further preferably contains a cross-linked product of an acrylic resin and an amino resin. Thereby, fusion | melting of resin layers can be suppressed, maintaining moderate elasticity.
The amino resin is not particularly limited, but a melamine resin and a benzoguanamine resin are preferable because the charge imparting ability of the carrier can be improved. Further, when it is necessary to appropriately control the charge imparting ability of the carrier, another amino resin may be used in combination with the melamine resin and / or benzoguanamine resin.
As the acrylic resin capable of crosslinking with the amino resin, those having a hydroxyl group and / or a carboxyl group are preferable, and those having a hydroxyl group are more preferable. Thereby, adhesiveness with core material particle | grains or electroconductive fine particles can further be improved, and the dispersion stability of electroconductive fine particles can also be improved. At this time, the acrylic resin preferably has a hydroxyl value of 10 mgKOH / g or more, and more preferably 20 mgKOH / g or more.

Moreover, in order to accelerate | stimulate the condensation reaction of B component which is a crosslinking component, a titanium-type catalyst, a tin-type catalyst, a zirconium-type catalyst, and an aluminum-type catalyst can be used. Of these various catalysts, titanium-based catalysts that give excellent results are preferred, and titanium alkoxides and titanium chelates are particularly preferred.
This is considered to be because the effect of accelerating the condensation reaction of the silanol group derived from the component B is large and the catalyst is hardly deactivated. An example of the titanium alkoxide catalyst is titanium diisopropoxybis (ethyl acetoacetate) represented by the following formula (3), and an example of the titanium chelate catalyst is represented by the following formula (4). And titanium diisopropoxybis (triethanolaminate).
_{Ti (O-i-C 3} H 7) 2 (C 6 H 9 O 3) 2 (3)
_{Ti (O-i-C 3} H 7) 2 (C 6 H 14 N) 2 (4)

The resin layer includes a copolymer containing the A component and the B component, a titanium diisopropoxybis (ethyl acetoacetate) catalyst, and if necessary, a resin other than the copolymer containing the A component and the B component, and It can form using the composition for resin layers containing a solvent.
Specifically, the resin layer may be formed by condensing silanol groups while coating the core particles with the resin layer composition, or after coating the core particles with the resin layer composition, The resin layer may be formed by condensing silanol groups.
The method of condensing silanol groups while coating the core material particles with the resin layer composition is not particularly limited, but the method of coating the core particles with the resin layer composition while applying heat, light, etc. Etc. Further, the method for condensing the silanol groups after coating the core material particles with the resin layer composition is not particularly limited, and examples thereof include a method of performing a heat treatment after coating the core material particles with the resin layer composition. It is done.

In general, a resin having a high molecular weight has a very high viscosity, and when applied to core particles having a small particle size, it is easy to cause aggregation of particles and non-uniformity of the resin layer, and it is extremely difficult to produce a coated carrier. difficult.
Therefore, the copolymer according to the present invention preferably has a weight average molecular weight of 5,000 to 100,000, more preferably 10,000 to 70,000, and 30,000 to 40,000. More preferably it is. When the weight average molecular weight is less than 5,000, the strength of the resin layer is insufficient, and when it exceeds 100,000, the liquid viscosity of the composition for the resin layer becomes high and the carrier productivity is lowered.

In the present invention, the resin layer contains conductive fine particles for improving the strength of the resin layer and adjusting the carrier resistance. The conductive fine particles are preferably conductive fine particles having a conductive coating layer on the surface of an alumina base.
As the alumina used for the substrate, any of α-alumina, β-alumina and γ-alumina can be used, and those having an average particle diameter of 0.1 to 0.5 μm and a BET specific surface area of 5 to 30 m ² / g. Can be used.
The conductive coating layer in the conductive fine particles preferably contains tin dioxide or tin dioxide and indium oxide. The conductive coating layer containing tin dioxide or tin dioxide and indium oxide can uniformly coat the surface of the substrate, and good conductivity can be obtained without being affected by the substrate. Those that are tin dioxide can be preferably used because they have sufficient resistance adjusting ability and are inexpensive.
When a conductive coating layer is tin dioxide, it is preferable that 4-80 mass% of tin dioxide is included in the whole electroconductive fine particles, and it is more preferable that it is 30-50 mass%.
If the tin dioxide is less than 4% by mass, the volume resistivity of the conductive fine particles is increased, so that the amount of the conductive fine particles is increased, and the conductive particles are easily detached from the surface of the carrier particles. The volume resistivity of the conductive fine particles does not decrease so much and the efficiency is low, and it may become non-uniform.
When the conductive coating layer is composed of tin dioxide and indium oxide, the content of tin dioxide is 2 to 7% by mass in the entire conductive fine particles, and the content of indium oxide is 15 to 40% by mass in the entire conductive fine particles. % Is preferable.

  The object of the present invention can be achieved by using tin oxide, more preferably, antimonyless tin oxide alone or in combination in addition to the conductive fine particles. In general, tin oxide is coated with antimony and indium to adjust the powder specific resistance, thereby obtaining a resistance adjusting effect. Other conductive fine particles that can achieve the object of the present invention include barium sulfate, carbon black, indium tin oxide (ITO), tin oxide, zinc oxide and the like.

In the carrier of the present invention, the concentration of the conductive fine particles in the resin layer is configured so as to be higher as it is closer to the surface of the resin layer.
As a method of such a configuration, the for forming the resin layer, wherein as a coating solution containing a resin and conductive fine particles, and a method of using two or more coating solutions having different conductive fine particles content It is done.
The difference of the conductive fine particle content in two or more kinds of coating liquids having different conductive fine particle contents can be set to about 0 to 30% by mass. The conductive content in the coating liquid having the minimum conductive fine particle content can be about 0% by mass. When coating the core particles with these coating liquids, first, a coating liquid having a low conductive particle content is applied to the core, and then a coating liquid having a lower conductive particle content than the coating liquid is applied. To do.
In this case, the time required for coating the coating liquid is usually 1 to 10 times, preferably 1 to 3 times the coating time of the other coating liquid with respect to the coating time of the coating liquid having the shortest coating time. is there.
In addition, the amount of droplets per unit time of the coating liquid supplied when the core material particles are coated with each of the two or more types of coating liquids having different conductive fine particle contents is the smallest. The amount of the other coating liquid is usually 1 to 10 times, preferably 1 to 5 times the amount of the coating liquid.
In the present invention, two or more kinds of coating liquids having different kinds of conductive fine particles can be used as the coating liquid containing the resin and conductive fine particles for forming the resin layer. By comprising in this way, the effect that resistance is stabilized with respect to the abrasion of the carrier resin layer with time is acquired.
When two or more kinds of coating liquids are used, the conductive fine particles in each coating liquid can be determined depending on the combination of powder specific resistance and concentration.
In this case, the time required for coating the coating liquid is usually 1 to 10 times, preferably 1 to 3 times the coating time of the other coating liquid with respect to the coating time of the coating liquid having the shortest coating time. is there.
In addition, the amount of droplets per unit time of the coating liquid supplied when the core material particles are coated with each of the two or more types of coating liquids having different conductive fine particle contents is the smallest. The amount of the other coating liquid is usually 1 to 10 times, preferably 1 to 5 times the amount of the coating liquid.
Moreover, in this invention, 2 or more types of coating liquid from which the powder specific resistance of electroconductive fine particles differs can be used as a coating liquid containing the said resin and electroconductive fine particles for forming the said resin layer. By comprising in this way, the effect that resistance is stabilized with respect to the abrasion of the carrier resin layer with time is acquired.
The difference in the specific resistance content of the conductive fine particles in two or more kinds of coating liquids having different powder specific resistances of the conductive fine particles can be about 1 to 10 (Ω · cm). The powder specific resistance in the coating liquid with the minimum powder specific resistance of the conductive content can be about 1 × 10 ³ (Ω · cm). When coating the core material particles with these coating liquids, first, a coating liquid having a high powder specific resistance of the conductive particles is applied to the core material, and then the powder specific resistance of the conductive particles is higher than the coating liquid. Apply a low coating liquid.
In this case, the time required for coating the coating liquid is usually 1 to 10 times, preferably 1 to 3 times the coating time of the other coating liquid with respect to the coating time of the coating liquid having the shortest coating time. is there.
In addition, the amount of droplets per unit time of the coating liquid supplied when the core material particles are coated with each of two or more types of coating liquids having different powder specific resistances is the coating liquid with the smallest droplet amount. The amount of droplets of the other coating liquid is usually 1 to 10 times, preferably 1 to 5 times that of the liquid.
The powder specific resistance of the conductive fine particles contained in each of the two or more kinds of coating liquids having different powder specific resistances of the conductive fine particles is different from the powder specific resistance of the conductive fine particles having the smallest powder specific resistance. it is preferred to a powder specific resistance of the conductive particles 1 to 10 ⁴ times, more preferably 1 to 10 ^twice.
The powder specific resistance can be determined by the following method.
[Powder specific resistance of conductive fine particles]
The powder specific resistance is measured by putting 5 g of a sample (conductive fine particles) 3 in a cylindrical vinyl chloride tube 1 having an inner diameter of 1 inch shown in FIG. 1 and sandwiching the upper and lower sides thereof with electrodes 2a and 2b. Apply a pressure of 10 kg / cmP ^2P . Subsequently, in this pressurized state, measurement with an LCR meter (4216A, manufactured by Yokogawa Hewlett-Packard Company) was performed, the resistance (r) was measured, and the powder specific resistance was calculated from the following formula.
Powder specific resistance (Ω · cm) = (2.54 / 2) P ^2P × (π / H × r)

The volume resistivity of the carrier for an electrostatic latent image developer of the present invention is preferably 1 × 10 ⁷ Ω · cm to 1 × 10 ¹⁷ Ω · cm. By controlling the carrier resistance, it is possible to obtain a high-definition image free from color stains with excellent reproducibility of fine lines such as character portions, with the edge effect suppressed. If the volume resistivity is less than 1 × 10 ⁷ Ω · cm, carrier adhesion may occur in the non-image area, and if it exceeds 1 × 10 ¹⁷ Ω · cm, the edge effect may be at an unacceptable level. is there.
The volume specific resistance of the carrier can be adjusted by adjusting the resistance of the resin layer on the core particle (addition of conductive fine particles, etc.) and controlling the film thickness. It is preferable that it is 200 mass parts, More preferably, it is 5-150 mass parts, More preferably, it is 10-120 mass parts.
When the addition amount of the conductive fine particles is less than 5 parts by mass, the strength of the resin layer cannot be sufficiently improved, and the carrier resistance may be insufficiently adjusted. In addition, the conductive fine particles are likely to be detached, and the volume specific resistance of the carrier may be easily changed.

In the present invention, the core layer particles are coated with the resin layer composition, and then heat-treated at a temperature lower than the Curie point of the core material particles to be used, preferably at a temperature of 100 to 350 ° C. Promoted. A more preferable heat treatment temperature is 150 to 250 ° C.
When the heat treatment temperature is lower than 100 ° C., the crosslinking reaction due to condensation does not proceed, and sufficient strength of the resin layer cannot be obtained. On the other hand, when the temperature is higher than 350 ° C., the resin layer is easily scraped due to the carbonization of the copolymer.

In the carrier of the present invention, the resin layer preferably has an average film thickness of 0.05 to 4 μm. When the average film thickness is less than 0.05 μm, the resin layer is easily peeled off.
The average film thickness of the resin layer can be determined by observing the cross section of the carrier using a transmission electron microscope (TEM) and measuring the average film thickness of the resin layer.
In the present invention, the core particle is not particularly limited as long as it is a magnetic substance, but is not limited to ferromagnetic metals such as iron and cobalt; iron oxides such as magnetite, hematite and ferrite; various alloys and compounds; Examples thereof include resin particles dispersed in the resin. Of these, Mn-based ferrite, Mn-Mg-based ferrite, Mn-Mg-Sr ferrite, and the like are preferable from the viewpoint of environmental considerations.

In the present invention, the core particles preferably have a weight average particle diameter of 20 to 65 μm. When the weight average particle diameter is less than 20 μm, carrier adhesion may occur. When the thickness exceeds 65 μm, carrier adhesion is less likely to occur, but the toner is not developed faithfully with respect to the latent image, so that the variation in dot diameter increases and the graininess decreases. Further, when the toner concentration is high, the background is easily soiled.
Carrier adhesion refers to a phenomenon in which a carrier adheres to an image portion or a background portion of an electrostatic latent image. The stronger each electric field, the easier the carrier adheres. In the image portion, the electric field is weakened by developing the toner, so that the carrier adhesion is less likely to occur compared to the background portion.
The weight average particle diameter can be measured using a Microtrac particle size analyzer (model HRA9320-X100 manufactured by Honeywell).

In the present invention, the weight average particle diameter Dw referred to for the carrier, the carrier core material, and the toner is calculated based on the particle diameter distribution (relationship between the number frequency and the particle diameter) of the particles measured on the basis of the number. The weight average particle diameter Dw in this case is represented by the following formula.
Dw = {1 / Σ (nD ³ )} × {Σ (nD ⁴ )}
In the formula, D represents a representative particle size (μm) of particles present in each channel, and n represents the total number of particles present in each channel. The channel indicates a length for dividing the particle size range in the particle size distribution diagram into measurement width units. In the present invention, the channel has an equal length of 2 μm (particle size distribution width). Adopted.
Further, as the representative particle size of the particles existing in each channel, the lower limit value of the particle size stored in each channel was adopted.

The carrier of the present invention preferably has a magnetization of 40 to 90 Am ² / kg in a magnetic field of 1 kOe (10 ⁶ / 4π [A / m]). When this magnetization is less than 40 Am ² / kg, the carrier may adhere to the image, and when it exceeds 90 Am ² / kg, the magnetic ear becomes hard and image blurring may occur.
The magnetization can be measured using a measuring instrument VSM-P7-15 (manufactured by Toei Kogyo Co., Ltd.) or the like.

The electrostatic latent image developer of the present invention is a two-component developer and includes the carrier of the present invention and a toner.
The toner used in the present invention contains a colorant, fine particles, a charge control agent, a release agent and the like in a binder resin mainly composed of a thermoplastic resin. Can be used. This toner can be an amorphous or spherical toner produced by various toner production methods such as a polymerization method and a granulation method. Either magnetic toner or non-magnetic toner can be used.

As the binder resin for the toner, the following can be used alone or in combination.
Styrene binder resins such as polystyrene, polyvinyltoluene and other styrene and substituted homopolymers, styrene-p-chlorostyrene copolymers, styrene-propylene copolymers, styrene-vinyltoluene copolymers, styrene-acrylic Acid methyl copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate Copolymer, styrene-α-chloromethacrylic acid methyl copolymer, styrene-acrylonitrile copolymer, styrene-vinyl methyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene -Isoprene copolymer, styrene- Styrene copolymers such as oleic acid copolymers and styrene-maleic acid ester copolymers; examples of acrylic binders include polymethyl methacrylate and polybutyl methacrylate; in addition, polyvinyl chloride resins, polyvinyl acetate resins, Polyethylene resin, polypropylene resin, polyester resin, polyurethane resin, epoxy resin, polyvinyl butyral, polyacrylic acid resin, rosin, modified rosin, terpene resin, phenol resin, aliphatic or aliphatic hydrocarbon resin, aromatic petroleum resin, chlorine Paraffin and paraffin wax.
Among these, a polyester resin is preferable because it can further reduce the melt viscosity while ensuring the stability during storage of the toner.

Polyester resins can be preferably used because they can lower the melt viscosity while ensuring the stability during storage of the toner, as compared with styrene and acrylic resins. Such a polyester resin can be obtained, for example, by a polycondensation reaction between an alcohol component and a carboxylic acid component.
Examples of the alcohol component include diols such as polyethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-propylene glycol, neopentyl glycol, 1,4-butenediol, Etherified bisphenols such as 1,4-bis (hydroxymethyl) cyclohexane, bisphenol A, hydrogenated bisphenol A, polyoxyethylenated bisphenol A, polyoxypropylenated bisphenol A, and the like. Divalent alcohol units substituted with saturated hydrocarbon groups, other divalent alcohol units, sorbitol, 1,2,3,6-hexanetetrol, 1,4-sorbitan, pentaesitol, dipenta Thritol, tripentaerythritol, sucrose, 1,2,4-butanetriol, 1,2,5-pentanetriol, glycerol, 2-methylpropanetriol, 2-methyl-1,2,4-butanetriol, tri Mention may be made of trihydric or higher alcohol monomers such as methylolethane, trimethylolpropane and 1,3,5-trihydroxymethylbenzene.

  Examples of the carboxylic acid component used to obtain the polyester resin include monocarboxylic acids such as palmitic acid, stearic acid, and oleic acid, maleic acid, fumaric acid, mesaconic acid, citraconic acid, terephthalic acid, cyclohexanedicarboxylic acid, Succinic acid, adipic acid, sebacic acid, malonic acid, divalent organic acid monomers in which these are substituted with saturated or unsaturated hydrocarbon groups having 3 to 22 carbon atoms, anhydrides of these acids, lower alkyl esters And dimer acid from linolenic acid, 1,2,4-benzenetricarboxylic acid, 1,2,5-benzenetricarboxylic acid, 2,5,7-naphthalenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid 1,2,4-butanetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,3-dicarboxyl- -Trivalent or higher polyvalent carboxylic acids such as methyl-2-methylenecarboxypropane, tetra (methylenecarboxyl) methane, 1,2,7,8-octanetetracarboxylic acid embol trimer acid, anhydrides of these acids, etc. A polymer can be mentioned.

  Examples of the epoxy resins include polycondensates of bisphenol A and epochorhydrin. For example, Epomic R362, R364, R365, R366, R367, R369 (above, manufactured by Mitsui Petrochemical Co., Ltd.), Epototo YD- Commercially available products such as 011, YD-012, YD-014, YD-904, YD-017 (above, manufactured by Tohto Kasei Co., Ltd.), Epcot 1002, 1004, 1007 (above, manufactured by Shell Chemical Co., Ltd.), etc. .

Colorants (pigments or dyes) used in the present invention include carbon black, lamp black, iron black, ultramarine blue, nigrosine dye, aniline blue, phthalocyanine blue, Hansa Yellow G, rhodamine 6G lake, calco oil blue, chrome yellow. And conventionally known colorants such as quinacridone, benzidine yellow, rose bengal, triallylmethane dyes, monoazo pigments and dyes, disazo pigments and dyes. These can be used alone or in combination.
Further, the black toner can be made into a magnetic toner by containing a magnetic material. As the magnetic material, ferromagnetic powders such as iron and cobalt, fine powders such as magnetite, hematite, Li-based ferrite, Mn-Zn-based ferrite, Cu-Zn-based ferrite, Ni-Zn ferrite, and Ba ferrite can be used.

For the purpose of sufficiently controlling the triboelectric chargeability of the toner, so-called charge control agents, such as metal complex salts of monoazo dyes, nitrohumic acids and salts thereof, salicylic acid, naphthoic salts, metal complexes of dicarboxylic acids such as Co, Cr and Fe , A quaternary ammonium compound, an organic dye, and the like can be contained.
In color toners other than black, it is preferable to use a metal salt of a white salicylic acid derivative as a charge control agent.

  If necessary, a release agent may be added to the toner used in the present invention. The release agent is not particularly limited, and examples thereof include low molecular weight polypropylene, low molecular weight polyethylene, carnauba wax, microcrystalline wax, jojoba wax, rice wax, and montanic acid wax. These can be used alone or in combination.

Additives can be added to the toner. In order to obtain a good image, it is important to impart sufficient fluidity to the toner. For this purpose, it is generally effective to externally add hydrophobized metal oxide fine particles and fine particles such as lubricants as fluidity improvers, and metal oxides, organic resin fine particles, metal soaps and the like as additives. Can be used. Specific examples of these additives include fluorine resins such as polytetrafluoroethylene, lubricants such as zinc stearate, abrasives such as cerium oxide and silicon carbide; for example, SiO ₂ and TiO ₂ having a hydrophobic surface. Examples thereof include fluidity-imparting agents such as inorganic oxides; those known as anti-caking agents, and surface treated products thereof. In order to improve the fluidity of the toner, hydrophobic silica is particularly preferably used.
The toner used in the electrostatic latent image developer comprising the toner and the carrier of the present invention has a weight average particle size of 3.0 to 9.0 μm, more preferably 3.0 to 6.0 μm.
The toner particle size can be measured using Coulter Multisizer II (manufactured by Coulter Counter).

  By using the carrier of the present invention as a replenishment developer composed of a carrier and a toner, and applying it to an image forming apparatus that forms an image while discharging excess developer in the developing device, a stable image can be obtained over a very long period of time. Quality is obtained. That is, the deteriorated carrier in the developing device and the non-deteriorated carrier in the replenishing developer are replaced, and the charge amount is kept stable for a long period of time, so that a stable image can be obtained. This method is particularly effective when printing a large image area. Deterioration at the time of printing a large image area is mainly due to a decrease in carrier charging ability due to toner spent on the carrier. However, using this method, the amount of carrier replenishment increases when the image area is large. The frequency with which the changed carriers are replaced increases. Thereby, a stable image can be obtained for an extremely long period of time.

  The mixing ratio of the replenishment developer is preferably 2 to 50 parts by mass, more preferably 5 to 12 parts by mass with respect to 1 part by mass of the carrier. When the amount of toner is less than 2 parts by mass, the amount of replenishment carrier for the toner is too large, the carrier is excessively supplied, and the carrier concentration in the developing device becomes too high, so that the charge amount of the toner tends to increase. Further, as the toner charge amount increases, the developing ability decreases and the image density decreases. On the other hand, when the toner amount exceeds 50 parts by mass, the carrier ratio in the replenishment developer becomes small, so that the replacement of the carrier in the image forming apparatus is reduced, and the effect on the carrier deterioration cannot be expected.

Next, examples of the image forming method and the image forming apparatus of the present invention will be described in detail with reference to the drawings. However, these examples are for explaining the present invention and not for limiting the present invention. .
FIG. 2 is a schematic diagram for explaining the image forming method and the developing unit of the image forming apparatus of the present invention, and the following modifications also belong to the category of the present invention.
In FIG. 2, a developing device 40 disposed opposite to the photosensitive drum 20 as a latent image carrier includes a developing sleeve 41 as a developer carrier, a developer accommodating member 42, and a doctor blade 43 as a regulating member. It is mainly composed of the support case 44 and the like.
To a support case 44 having an opening on the photosensitive drum 20 side, a toner hopper 45 serving as a toner storage portion for storing the toner 21 is joined. The developer container 46 adjacent to the toner hopper 45 and containing the developer composed of the toner 21 and the carrier particles 23 agitates the toner particles 21 and the carrier particles 23 and imparts friction / release charge to the toner particles. For this purpose, a developer stirring mechanism 47 is provided.

Inside the toner hopper 45, a toner agitator 48 and a toner replenishing mechanism 49 are disposed as toner supplying means rotated by a driving means (not shown). The toner agitator 48 and the toner replenishing mechanism 49 send out the toner 21 in the toner hopper 45 toward the developer accommodating portion 46 while stirring.
A developing sleeve 41 is disposed in the space between the photosensitive drum 20 and the toner hopper 45. A developing sleeve 41 that is rotationally driven in the direction of the arrow in the figure by a driving means (not shown) is a magnetic field that is disposed in a relative position with respect to the developing device 40 in order to form a magnetic brush made of carrier particles 23. It has a magnet (not shown) as generating means.
A regulating member (doctor blade) 43 is integrally attached to the side of the developer accommodating member 42 opposite to the side attached to the support case 44. In this example, the regulating member (doctor blade) 43 is disposed in a state where a certain gap is maintained between the tip thereof and the outer peripheral surface of the developing sleeve 41.

  Using such an apparatus without limitation, the developing method of the present invention is performed as follows. In other words, the toner 21 sent out from the toner hopper 45 by the toner agitator 48 and the toner replenishing mechanism 49 is conveyed to the developer accommodating portion 46 and agitated by the developer agitating mechanism 47 according to the above configuration. Is applied to the developing sleeve 41 as a developer together with the carrier particles 23 and conveyed to a position facing the outer peripheral surface of the photosensitive drum 20, and only the toner 21 is formed on the photosensitive drum 20. A toner image is formed on the photosensitive drum 20 by electrostatically coupling with the electrostatic latent image thus formed.

  FIG. 3 is a schematic diagram showing an example of the configuration of the image forming apparatus of the present invention. A charging member 32, an image exposure system 33, a developing (apparatus) mechanism 40, a transfer mechanism 50, a cleaning mechanism 60, and a charge eliminating lamp 70 are disposed around a drum-shaped image carrier, that is, the photosensitive drum 20. In this case, the surface of the image carrier charging member 32 is in a non-contact state with a surface of about 0.2 mm from the surface of the photosensitive drum 20, and when charging the photosensitive drum 20 by the charging member 32, By charging the photosensitive drum 20 with an electric field in which an AC component is superimposed on a DC component by a voltage application unit (not shown) on the charging member 32, it is possible to reduce charging unevenness, which is effective. The image forming method including the developing method is performed by the following operation.

  A series of image forming processes can be described by a negative-positive process. An image carrier represented by a photoconductor (OPC) 20 having an organic photoconductive layer is neutralized by a static elimination lamp 70, and is uniformly negatively charged by a charging member 32 such as a charging charger or a charging roller, and a laser optical system (image exposure). A latent image is formed by the laser beam 37 irradiated from the system 33) (in this example, the absolute value of the exposed portion potential is lower than the absolute value of the non-exposed portion potential).

  Laser light 37 is emitted from a semiconductor laser, and scans the surface of the image carrier, that is, the photosensitive drum 20 in the direction of the rotational axis of the photosensitive drum 20 by a polygonal polygon mirror (polygon) that rotates at high speed. The latent image formed in this way is developed with a developer composed of a mixture of toner particles and carrier particles supplied onto a developing sleeve 41 which is a developer carrying member in the developing device, developing means or developing device 40. A toner visible image is formed. At the time of developing the latent image, a voltage of an appropriate magnitude or an AC voltage is superimposed on this voltage from the voltage application mechanism (not shown) to the developing sleeve 41 between the exposed portion and the non-exposed portion of the photosensitive drum 20. The developing bias applied is applied.

On the other hand, a recording medium (for example, paper) 80 is fed from a paper feed mechanism (not shown), and the photosensitive drum 20 and the transfer mechanism 50 are synchronized with the leading edge of the image by a pair of upper and lower registration rollers (not shown). And the toner image is transferred. At this time, it is preferable that a potential having a polarity opposite to the polarity of toner charging is applied to the transfer mechanism 50 as a transfer bias. Thereafter, the recording medium or the intermediate transfer medium 80 is separated from the photosensitive drum 20, and a transfer image is obtained.
Further, the toner particles remaining on the photosensitive drum 20 which is an image carrier are collected in a toner collection chamber 62 in the cleaning mechanism 60 by a cleaning blade 61 as a cleaning member.
The collected toner particles may be transported to a developing unit and / or a toner replenishing unit by a toner recycling means (not shown) and reused.
The image forming apparatus may be an apparatus in which a plurality of the developing devices described above are arranged, the toner images are sequentially transferred onto a recording medium, then sent to a fixing mechanism, and the toner is fixed by heat or the like. An apparatus may be used in which a plurality of toner images are transferred upward, and the toner images are collectively transferred to a transfer medium and then fixed in the same manner.

  FIG. 4 shows another process example using the image forming method of the present invention. FIG. 4 is a schematic view showing another example of the configuration of the image forming apparatus of the present invention. The photosensitive member 201 is provided with at least a photosensitive layer on a conductive support, and is driven by driving rollers 24a and 24b. The photosensitive member 201 is charged by a charging roller 321, image exposure by a light source 331, development by a developing device 40, and a charger 51. Transfer, pre-cleaning exposure by the pre-cleaning exposure light source 26, cleaning by the brush-like cleaning means 64 and the cleaning blade 61, and static elimination by the static elimination light source 70 are repeated. In FIG. 4, the photoconductor 201 (of course, the support is translucent in this case) is irradiated with pre-cleaning exposure light from the support side.

  FIG. 5 is a schematic view showing an example of the configuration of the process cartridge of the present invention. As shown in FIG. 5, the process cartridge 10 includes at least a photosensitive drum 20, a proximity-type brush-like contact charging member 322, a developing device 40 that stores the developer of the present invention, and a cleaning blade 61 as a cleaning unit. A process cartridge that integrally supports a cleaning mechanism and that is detachable from the main body of the image forming apparatus. In the present invention, the above-described components can be integrally combined as a process cartridge, and the process cartridge can be configured to be detachable from a main body of an image forming apparatus such as a copying machine or a printer.

EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated further more concretely, this invention is not limited to these. “Part” represents part by mass.
<Synthesis of copolymer>
The weight average molecular weight was determined in terms of standard polystyrene using gel permeation chromatography. The viscosity was measured at 25 ° C. according to JIS-K2283. The non-volatile content was calculated according to the following formula by weighing 1 g of the coating composition in an aluminum dish and measuring the mass after heating at 150 ° C. for 1 hour.
Nonvolatile content (%) = (mass before heating−mass after heating) × 100 / mass before heating Hereinafter, synthesis examples of resins used in the present invention will be shown.

(Resin Synthesis Example 1) (Component A: Component B: Component C = 20: 15: 65)
300 g of toluene was charged into a flask equipped with a stirrer, and the temperature was raised to 90 ° C. under a nitrogen gas stream. Subsequently, 3-methacryloxypropyltris (trimethylsiloxy) silane (sila) represented by CH ₂ ═CMe—COO—C ₃ H ₆ —Si (OSiMe ₃ ) ₃ (wherein Me is a methyl group) is added thereto. Plain TM-0701T manufactured by Chisso Corporation) 84.4 g (200 mmol), 3-methacryloxypropylmethyldiethoxysilane 39 g (150 mmol), methyl methacrylate 65.0 g (650 mmol) and 2,2′-azobis-2 -A mixture of 0.58 g (3 mmol) of methylbutyronitrile was added dropwise over 1 hour.
After completion of the addition, a solution of 2,2′-azobis-2-methylbutyronitrile (0.06 g, 0.3 mmol) dissolved in 15 g of toluene (2,2′-azobis-2-methylbutyronitrile A total amount of 0.64 g = 3.3 mmol) was added and mixed at 90 to 100 ° C. for 3 hours for radical copolymerization to obtain a methacrylic copolymer.
The weight average molecular weight of the obtained methacrylic copolymer was 33,000. Subsequently, it diluted with toluene so that the non volatile matter of this methacrylic copolymer solution might be 25 mass%. The viscosity of the copolymer solution thus obtained was 8.8 mm ² / s, and the specific gravity was 0.91.

(Resin Synthesis Example 2) (Component A: Component B: Component C = 20: 15: 65)
Resin Synthesis Example 1 is exactly the same as Resin Synthesis Example 1 except that 39 g (150 mmol) of 3-methacryloxypropylmethyldiethoxysilane was replaced with 37.2 g (150 mmol) of 3-methacryloxypropyltrimethoxysilane. Then, a methacrylic copolymer was obtained by radical copolymerization.
The weight average molecular weight of the obtained methacrylic copolymer was 34,000. Subsequently, it diluted with toluene so that the non volatile matter of this methacrylic copolymer solution might be 25 mass%. The viscosity of the copolymer solution thus obtained was 8.7 mm ² / s and the specific gravity was 0.91.

(Resin Synthesis Example 3) (Component A: Component B = 30: 70)
500 g of toluene was put into a flask equipped with a stirrer, and the temperature was raised to 90 ° C. under a nitrogen gas stream. Subsequently, 3-methacryloxypropyltris (trimethylsiloxy) silane (sila) represented by CH ₂ ═CMe—COO—C ₃ H ₆ —Si (OSiMe ₃ ) ₃ (wherein Me is a methyl group) (Plain TM-0701T manufactured by Chisso Corporation) 126.6 g (300 mmol), 3-methacryloxypropyltrimethoxysilane 173.6 g (700 mmol) and 2,2′-azobis-2-methylbutyronitrile 0.58 g (3 Mmol) of the mixture was added dropwise over 1 hour.
After completion of the addition, a solution of 2,2′-azobis-2-methylbutyronitrile (0.06 g, 0.3 mmol) dissolved in 15 g of toluene (2,2′-azobis-2-methylbutyronitrile A total amount of 0.64 g = 3.3 mmol) was added and mixed at 90 to 100 ° C. for 3 hours for radical copolymerization to obtain a methacrylic copolymer.
The weight average molecular weight of the obtained methacrylic copolymer was 35,000. Subsequently, it diluted with toluene so that the non volatile matter of this methacrylic copolymer solution might be 25 mass%. The viscosity of the copolymer solution thus obtained was 8.5 mm ² / s, and the specific gravity was 0.91.

(Resin synthesis example 4)
100 parts of MEK (methyl ethyl ketone) was charged into a 500 ml flask equipped with a stirrer, a condenser, a thermometer, a nitrogen inlet tube, and a dropping device. Separately, 32.6 parts of MMA (methyl methacrylate), 2.5 parts of HEMA (2-hydroxyethyl methacrylate) and MPTS (organopolysiloxane: methacryloxypropyltris (trimethylsiloxy) silane at 80 ° C. in a nitrogen atmosphere. = 1: 3) 64.9 parts, 1 part of 1,1′-azobis (cyclohexane-1-carbonitrile) (V-40 manufactured by Wako Pure Chemical Industries, Ltd.) in 100 parts of MEK was dissolved in 2 parts. It was dropped into the flask over time and aged for 5 hours.
Subsequently, it diluted with MEK (methyl ethyl ketone) so that a non volatile matter might be 25 mass%, and the copolymer solution was obtained.

<Manufacture of conductive fine particles>
(Conductive fine particle production example 1)
100 g of aluminum oxide (AKP-30 manufactured by Sumitomo Chemical Co., Ltd.) was dispersed in 1 liter of water to form a suspension, and this suspension was heated to 70 ° C. To this suspension, a solution of 100 g stannic chloride and 3 g phosphorus pentoxide in 1 liter of 2 mol / liter hydrochloric acid and 12% by mass aqueous ammonia were added so that the suspension had a pH of 7-8. It was added dropwise over time. After dropping, the cake obtained by filtering and washing the suspension was dried at 110 ° C. to obtain a dry powder. Next, this dry powder was treated in a nitrogen stream at 500 ° C. for 1 hour to obtain conductive fine particles.
The volume resistivity of the obtained conductive fine particles was 8 Ω · cm.

<Example of carrier production>
(Carrier Production Example 1)
50 parts of a methacrylic copolymer (resin) having a weight average molecular weight of 33,000 obtained in Resin Synthesis Example 1, 20 parts of conductive fine particles obtained in Conductive Fine Particle Production Example 1, and titanium diisopropoxybis ( Ethyl acetoacetate) (TC-750, Matsumoto Fine Chemical Co., Ltd.) 4 parts was diluted with toluene to obtain a coating liquid A which is a resin solution having a solid content of 10% by mass.
50 parts of a methacrylic copolymer having a weight average molecular weight of 33,000 obtained in Resin Synthesis Example 1, 40 parts of conductive fine particles obtained in Conductive Fine Particle Production Example 1, and titanium diisopropoxybis (ethylacetoacetate) as a catalyst ) (TC-750 Matsumoto Fine Chemical Co., Ltd.) 4 parts was diluted with toluene to obtain a coating solution B which is a resin solution having a solid content of 10% by mass.
Using Mn ferrite particles having a weight average particle diameter of 35 μm as the core material and using a fluidized bed type coating apparatus so that the average film thickness is 0.30 μm on the surface of the core material, the temperature in the fluidized tank is adjusted to 70 each. The carrier was obtained by coating and drying the coating A solution and the coating B solution in this order under the control of the temperature. Coating and drying of the coating liquid A and the coating liquid B were performed by coating and drying the coating liquid A for 30 minutes, and then coating and drying the coating liquid B for 30 minutes.
The obtained carrier was baked at 180 ° C. for 2 hours in an electric furnace to obtain carrier A.

(Carrier Production Example 2)
50 parts of a methacrylic copolymer having a weight average molecular weight of 33,000 obtained in Resin Synthesis Example 1, 40 parts of commercially available oxygen-deficient tin oxide-coated barium sulfate powder (Pastran 4310, Mitsui Kinzoku Co., Ltd.) as a conductive fine particle and a catalyst 4 parts of titanium diisopropoxybis (ethyl acetoacetate) (TC-750 manufactured by Matsumoto Fine Chemical Co., Ltd.) was diluted with toluene to obtain a coating solution A which is a resin solution having a solid content of 10% by mass. The volume specific resistance of the barium sulfate powder was 42 Ω · cm.
50 parts of a methacrylic copolymer having a weight average molecular weight of 33,000 obtained in Resin Synthesis Example 1, 40 parts of conductive fine particles (volume resistivity 8 Ω · cm) obtained in Production Example 1 of conductive fine particles, and titanium as a catalyst 4 parts of diisopropoxybis (ethyl acetoacetate) (TC-750 manufactured by Matsumoto Fine Chemical Co., Ltd.) was diluted with toluene to obtain a coating solution B which is a resin solution having a solid content of 10% by mass.
Using Mn ferrite particles having a weight average particle diameter of 35 μm as the core material and using a fluidized bed type coating apparatus so that the average film thickness is 0.30 μm on the surface of the core material, the temperature in the fluidized tank is adjusted to 70 each. The carrier was obtained by coating and drying the coating A solution and the coating B solution in this order under the control of the temperature. Coating and drying of the coating liquid A and the coating liquid B were performed by coating and drying the coating liquid A for 30 minutes, and then coating and drying the coating liquid B for 30 minutes.
The obtained carrier was baked at 180 ° C. for 2 hours in an electric furnace to obtain carrier B.

(Carrier Production Example 3)
50 parts of a methacrylic copolymer having a weight average molecular weight of 33,000 obtained in Resin Synthesis Example 1, 20 parts of conductive fine particles obtained in Production Example 1 of conductive fine particles, and titanium diisopropoxybis (ethylacetoacetate as a catalyst) ) (TC-750 Matsumoto Fine Chemical Co., Ltd.) 4 parts was diluted with toluene to obtain a coating solution A which is a resin solution having a solid content of 10% by mass.
50 parts of a methacrylic copolymer having a weight average molecular weight of 33,000 obtained in Resin Synthesis Example 1, 40 parts of conductive fine particles obtained in Conductive Fine Particle Production Example 1, and titanium diisopropoxybis (ethylacetoacetate) as a catalyst ) (TC-750 Matsumoto Fine Chemical Co., Ltd.) 4 parts was diluted with toluene to obtain a coating solution B which is a resin solution having a solid content of 10% by mass.
Using Mn ferrite particles having a weight average particle diameter of 35 μm as the core material and using a fluidized bed type coating apparatus so that the average film thickness is 0.30 μm on the surface of the core material, the temperature in the fluidized tank is adjusted to 70 each. The carrier was obtained by coating and drying the coating A solution and the coating B solution in this order under the control of the temperature. The coating and drying of the coating liquid A and the coating liquid B were performed by coating and drying the coating liquid A for 20 minutes, and then coating and drying the coating liquid B for 40 minutes.
The obtained carrier was baked at 180 ° C. for 2 hours in an electric furnace to obtain carrier C.

(Carrier Production Example 4)
50 parts of a methacrylic copolymer having a weight average molecular weight of 33,000 obtained in Resin Synthesis Example 1, 40 parts of conductive fine particles obtained in Conductive Fine Particle Production Example 1, and titanium diisopropoxybis (ethylacetoacetate) as a catalyst ) (TC-750 Matsumoto Fine Chemical Co., Ltd.) 4 parts was diluted with toluene to obtain a coating solution A which is a resin solution having a solid content of 10% by mass.
50 parts of a methacrylic copolymer having a weight average molecular weight of 33,000 obtained in Resin Synthesis Example 1, 40 parts of conductive fine particles obtained in Conductive Fine Particle Production Example 1, and titanium diisopropoxybis (ethylacetoacetate) as a catalyst ) (TC-750 Matsumoto Fine Chemical Co., Ltd.) 4 parts was diluted with toluene to obtain a coating solution B which is a resin solution having a solid content of 10% by mass.
Using Mn ferrite particles having a weight average particle diameter of 35 μm as the core material and using a fluidized bed type coating apparatus so that the average film thickness is 0.30 μm on the surface of the core material, the temperature in the fluidized tank is adjusted to 70 each. The carrier was obtained by coating and drying the coating A solution and the coating B solution in this order under the control of the temperature. The coating and drying of the coating liquid A and the coating liquid B were performed by coating and drying the coating liquid A for 20 minutes, and then coating and drying the coating liquid B for 40 minutes.
The obtained carrier was baked at 180 ° C. for 2 hours in an electric furnace to obtain carrier D.

(Carrier Production Example 5)
50 parts of a methacrylic copolymer having a weight average molecular weight of 33,000 obtained in Resin Synthesis Example 1, 20 parts of conductive fine particles obtained in Production Example 1 of conductive fine particles, and titanium diisopropoxybis (ethylacetoacetate as a catalyst) ) (TC-750 Matsumoto Fine Chemical Co., Ltd.) 4 parts was diluted with toluene to obtain a coating solution A which is a resin solution having a solid content of 10% by mass.
50 parts of a methacrylic copolymer having a weight average molecular weight of 33,000 obtained in Resin Synthesis Example 1, 40 parts of conductive fine particles obtained in Conductive Fine Particle Production Example 1, and titanium diisopropoxybis (ethylacetoacetate) as a catalyst ) (TC-750 Matsumoto Fine Chemical Co., Ltd.) 4 parts was diluted with toluene to obtain a coating solution B which is a resin solution having a solid content of 10% by mass.
Using Mn ferrite particles having a weight average particle diameter of 35 μm as the core material and using a fluidized bed type coating apparatus so that the average film thickness is 0.30 μm on the surface of the core material, the temperature in the fluidized tank is adjusted to 70 each. The carrier was obtained by coating and drying the coating A solution and the coating B solution in this order under the control of the temperature. Coating and drying of the coating liquid A and the coating liquid B were carried out by coating and drying the coating liquid A for 40 minutes and then coating and drying the coating liquid B for 20 minutes.
The obtained carrier was baked at 180 ° C. for 2 hours in an electric furnace to obtain carrier E.

(Carrier Production Example 6)
50 parts of a methacrylic copolymer having a weight average molecular weight of 33,000 obtained in Resin Synthesis Example 1, 40 parts of conductive fine particles obtained in Conductive Fine Particle Production Example 1, and titanium diisopropoxybis (ethylacetoacetate) as a catalyst ) (TC-750 Matsumoto Fine Chemical Co., Ltd.) 4 parts was diluted with toluene to obtain a coating solution A which is a resin solution having a solid content of 10% by mass.
50 parts of a methacrylic copolymer having a weight average molecular weight of 33,000 obtained in Resin Synthesis Example 1, 40 parts of conductive fine particles obtained in Conductive Fine Particle Production Example 1, and titanium diisopropoxybis (ethylacetoacetate) as a catalyst ) (TC-750 Matsumoto Fine Chemical Co., Ltd.) 4 parts was diluted with toluene to obtain a coating solution B which is a resin solution having a solid content of 10% by mass.
Using Mn ferrite particles having a weight average particle diameter of 35 μm as the core material and using a fluidized bed type coating apparatus so that the average film thickness is 0.30 μm on the surface of the core material, the temperature in the fluidized tank is adjusted to 70 each. The carrier was obtained by coating and drying the coating A solution and the coating B solution in this order under the control of the temperature. Coating and drying of the coating liquid A and the coating liquid B were carried out by coating and drying the coating liquid A for 40 minutes and then coating and drying the coating liquid B for 20 minutes.
The obtained carrier was baked at 180 ° C. for 2 hours in an electric furnace to obtain carrier F.

(Carrier Production Example 7)
Carrier G was obtained in exactly the same manner as Carrier Production Example 1, except that the resin was changed to the resin obtained in Resin Synthesis Example 2 in Carrier Production Example 1.
(Carrier Production Example 8)
In Carrier Production Example 2, Carrier H was obtained in exactly the same manner as Carrier Production Example 2, except that the resin was changed to the resin obtained in Resin Synthesis Example 2.
(Carrier Production Example 9)
In Carrier Production Example 3, Carrier I was obtained in exactly the same manner as Carrier Production Example 3, except that the resin was changed to the resin obtained in Resin Synthesis Example 2.
(Carrier Production Example 10)
In Carrier Production Example 4, Carrier J was obtained in exactly the same manner as Carrier Production Example 4, except that the resin was changed to the resin obtained in Resin Synthesis Example 2.
(Carrier Production Example 11)
In Carrier Production Example 5, Carrier K was obtained in exactly the same manner as Carrier Production Example 5, except that the resin was replaced with the resin obtained in Resin Synthesis Example 2.
(Carrier Production Example 12)
In Carrier Production Example 6, Carrier L was obtained in exactly the same manner as Carrier Production Example 6, except that the resin was changed to the resin obtained in Resin Synthesis Example 2.

(Carrier Production Example 13)
In Carrier Production Example 1, Carrier M was obtained in exactly the same manner as Carrier Production Example 1, except that the resin was changed to the resin obtained in Resin Synthesis Example 3.
(Carrier Production Example 14)
In Carrier Production Example 2, Carrier N was obtained in exactly the same manner as Carrier Production Example 2, except that the resin was changed to the resin obtained in Resin Synthesis Example 2.
(Carrier Production Example 15)
In Carrier Production Example 3, Carrier O was obtained in exactly the same manner as Carrier Production Example 3, except that the resin was changed to the resin obtained in Resin Synthesis Example 3.
(Carrier Production Example 16)
In Carrier Production Example 4, Carrier P was obtained in exactly the same manner as Carrier Production Example 4 except that the resin was changed to the resin obtained in Resin Synthesis Example 3.
(Carrier Production Example 17)
In Carrier Production Example 5, Carrier Q was obtained in exactly the same manner as Carrier Production Example 5, except that the resin was changed to the resin obtained in Resin Synthesis Example 3.
(Carrier Production Example 18)
In Carrier Production Example 6, Carrier R was obtained in exactly the same manner as Carrier Production Example 6, except that the resin was replaced with the resin obtained in Resin Synthesis Example 3.

(Carrier Production Example 19)
100 parts of a methacrylic copolymer (resin) having a weight average molecular weight of 33,000 obtained in Resin Synthesis Example 1, 20 parts of conductive fine particles obtained in Conductive Fine Particle Production Example 1, and titanium diisopropoxybis ( Ethyl acetoacetate) (TC-750, Matsumoto Fine Chemical Co., Ltd.) 4 parts was diluted with toluene to obtain a coating liquid A which is a resin solution having a solid content of 10% by mass.
100 parts of a methacrylic copolymer having a weight average molecular weight of 33,000 obtained in Resin Synthesis Example 1, 30 parts of conductive particles obtained in Production Example 1 of conductive fine particles, and titanium diisopropoxybis (ethylacetoacetate as a catalyst) ) (TC-750 Matsumoto Fine Chemical Co., Ltd.) 4 parts was diluted with toluene to obtain a coating solution B which is a resin solution having a solid content of 10% by mass.
100 parts of a methacrylic copolymer having a weight average molecular weight of 33,000 obtained in Resin Synthesis Example 1, 40 parts of conductive fine particles obtained in Conductive Fine Particle Production Example 1, and titanium diisopropoxybis (ethylacetoacetate) as a catalyst ) (TC-750 Matsumoto Fine Chemical Co., Ltd.) 4 parts was diluted with toluene to obtain a coating solution B which is a resin solution having a solid content of 10% by mass.
Using Mn ferrite particles having a weight average particle diameter of 35 μm as the core material and using a fluidized bed type coating apparatus so that the average film thickness is 0.30 μm on the surface of the core material, the temperature in the fluidized tank is adjusted to 70 each. The carrier was obtained by coating and drying the coating A solution, the coating B solution, and the coating C solution in this order under the control of the temperature. For coating / drying of the coating A liquid, the coating B liquid and the coating C liquid, the coating liquid A is applied / dried for 20 minutes, then the coating liquid B is applied / dried for 20 minutes, and then the coating liquid C is applied for 20 minutes. -Performed by drying.
The obtained carrier was baked at 180 ° C. for 2 hours in an electric furnace to obtain carrier S.

(Carrier Production Comparative Example 1)
50 parts of a methacrylic copolymer having a weight average molecular weight of 33,000 obtained in Resin Synthesis Example 1, 40 parts of conductive fine particles obtained in Conductive Fine Particle Production Example 1, and titanium diisopropoxybis (ethylacetoacetate) as a catalyst ) (TC-750 Matsumoto Fine Chemical Co., Ltd.) 4 parts was diluted with toluene to obtain a coating solution A which is a resin solution having a solid content of 10% by mass.
Using Mn ferrite particles having a weight average particle diameter of 35 μm as the core material and using a fluidized bed type coating apparatus so that the average film thickness is 0.30 μm on the surface of the core material, the temperature in the fluidized tank is adjusted to 70 each. The carrier was obtained by controlling the temperature at 0 ° C. and applying and drying the coating A solution for 60 minutes. The obtained carrier was baked at 180 ° C. for 2 hours in an electric furnace to obtain carrier T.
(Carrier Production Comparative Example 2)
In Carrier Production Example 1, Carrier U was obtained in exactly the same manner as Carrier Production Example 1, except that the resin was changed to the resin obtained in Resin Synthesis Example 2.
(Carrier Production Comparative Example 3)
In Carrier Production Example 1, Carrier V was obtained in exactly the same manner as Carrier Production Example 1, except that the resin was changed to the resin obtained in Resin Synthesis Example 3.
(Carrier Production Comparative Example 4)
50 parts of a methacrylic copolymer having a weight average molecular weight of 33,000 obtained in Resin Synthesis Example 4, 20 parts of conductive fine particles obtained in Production Example 1 of conductive fine particles, and titanium diisopropoxybis (ethylacetoacetate as a catalyst) ) (TC-750 Matsumoto Fine Chemical Co., Ltd.) 4 parts was diluted with toluene to obtain a coating solution A which is a resin solution having a solid content of 10% by mass.
50 parts of a methacrylic copolymer having a weight average molecular weight of 33,000 obtained in Resin Synthesis Example 4, 40 parts of conductive fine particles obtained in Conductive Fine Particle Production Example 1, and titanium diisopropoxybis (ethylacetoacetate) as a catalyst ) (TC-750 Matsumoto Fine Chemical Co., Ltd.) 4 parts was diluted with toluene to obtain a coating solution B which is a resin solution having a solid content of 10% by mass.
Using Mn ferrite particles having a weight average particle diameter of 35 μm as the core material and using a fluidized bed type coating apparatus so that the average film thickness is 0.30 μm on the surface of the core material, the temperature in the fluidized tank is adjusted to 70 each. The carrier was obtained by coating and drying the coating A solution and the coating B solution in this order under the control of the temperature. Coating and drying of the coating liquid A and the coating liquid B were performed by coating and drying the coating liquid A for 30 minutes, and then coating and drying the coating liquid B for 30 minutes.
The obtained carrier was baked at 180 ° C. for 2 hours in an electric furnace to obtain carrier W.

<Carrier characteristics evaluation>
Hereinafter, a method for evaluating carrier characteristics will be described.
[Weight average particle diameter of core particles]
The particle size distribution of the core particles was measured using a Microtrac particle size analyzer (model HRA9320-X100 manufactured by Honeywell).
The measurement conditions are as follows.
[1] Particle size range: 100-8 μm
[2] Channel length (channel width): 2 μm
[3] Number of channels: 46
[4] Refractive index: 2.42

[Magnetization in a magnetic field of 1 kOe]
About 0.15 g of carrier is filled in a cell with an inner diameter of 2.4 mm and a height of 8.5 mm, and then magnetization is measured in a magnetic field of 1 kOe using VSM-P7-15 (manufactured by Toei Kogyo Co., Ltd.). did.

[Volume resistivity]
The volume resistivity was measured using the cell shown in FIG. Specifically, first, a carrier 13 is filled in a cell made of a fluororesin container 11 containing electrodes 12a and 12b having a surface area of 2.5 cm × 4 cm and separated by a distance of 0.2 cm, and the drop height is set. Tapping was performed 10 times at 1 cm and a tapping speed of 30 times / minute. Next, a DC voltage of 1000 V was applied between the electrodes 12a and 12b, and the resistance r [Ω] after 30 seconds was measured using a high resistance meter 4329A (manufactured by Yokogawa Hewlett-Packard Company). Volume resistivity [Ωcm] was calculated.
Volume resistivity [Ω · cm] = r × (2.5 × 4) /0.2
[Average thickness of resin layer]
The cross section of the carrier was observed using a transmission electron microscope (TEM), and the average film thickness (carrier film thickness) of the resin layer was measured.

<Example of toner production>
Polyester resin [weight average molecular weight (Mw) 18,000, number average molecular weight (Mn) 4000, glass transition point (Tg) 59 ° C., softening point: 120 ° C.] 100 parts, carnauba wax 5 parts as a release agent, carbon 10 parts of black (manufactured by Mitsubishi Chemical Co., Ltd.) and 4 parts of fluorine-containing quaternary ammonium salt were sufficiently mixed with a Henschel mixer, melt-kneaded with a twin-screw extruder, and the kneaded product was rolled and cooled. After cooling, the mixture was coarsely pulverized with a cutter mill, then finely pulverized with a jet airflow fine pulverizer, and further classified with an air classifier to obtain toner base particles having a weight average particle diameter of 7.4 μm.
Further, 1.0 part of hydrophobic silica fine particles (R972, manufactured by Nippon Aerosil Co., Ltd.) was added to 100 parts of the toner base particles, and mixed with a Henschel mixer to obtain toner 1.

<Production of developer>
To 93 parts of each carrier A to W obtained in the carrier production example, 7 parts of toner 1 (average particle size 7.2 μm) obtained in the toner production example was added, and stirred for 20 minutes with a ball mill. A to W were prepared.

<Developer characteristics evaluation>
The resulting developer was used to produce an initial image, and these developers were then transferred to a digital color copier / printer multifunction machine (Imagio).
Color 4000 (manufactured by Ricoh Co., Ltd.) and stirred for 10 minutes in monochromatic mode. Thereafter, a running test of 100,000 sheets was performed using a chart with an image area of 7%. After the test was completed, the toner charge amount (Q / M), the volume resistivity, the spent toner amount, the Q / M environmental variation rate, and the development The fluctuation rate of the amount of the agent drawn up was evaluated by the following evaluation method. The evaluation results are shown in Table 2. Developers A to S were Examples 1 to 19, and Developers T to W were Comparative Examples 1 to 4.

[Real machine quality evaluation]
Digital color copier / printer combined machine (Imagio
The development conditions in Color 4000 (made by Ricoh) are as follows.
・ Development gap (photosensitive member-developing sleeve): 0.3 mm
・ Doctor gap (developing sleeve-doctor): 0.65mm
-Photoconductor linear velocity: 200 mm / sec
(Development sleeve linear velocity) / (photosensitive member linear velocity): 1.80
-Write density: 600 dpi
・ Charging potential (Vd): -600V
-Potential after exposure of the portion corresponding to the image portion (solid document): -100V
Development bias: DC-500V / AC bias component: 2 kHz, -100 V to -900 V, 50% duty

[Changes in physical properties of developer]
(1) Toner charge amount (Q / M) and Q / M environment change rate Q / M environment change rate (%) = 2 × {(toner charge amount at 10 ° C./15%−toner charge at 30 ° C./90% Amount) / (toner charge amount at 10 ° C./15%+toner charge amount at 30 ° C./90%)}×100
The Q / M environmental fluctuation rate was obtained by the following evaluation criteria. In the above formula, 15% and 90% are humidity.
0%: ◎ ◎ (very good)
Less than 10%: ◎ (very good)
10 to less than 30%: ○ (good)
30% to less than 70%: △ (can be used)
70% or more: × (defect)

The charge amount of the toner can be measured by the following method. A method for measuring the charge amount of the toner will be described with reference to FIG.
First, a certain amount of developer is put into a conductive container (cage) 102 provided with a stainless steel mesh 101 at both ends. The mesh 101 has a mesh size between the toner 103 and the carrier 104 (mesh size 20 μm), and is set so that the toner 103 passes between the meshes 101. When the compressed nitrogen gas (1 kgf / cm ² ) 106 is blown from the nozzle 105 for 60 seconds to cause the toner 103 to jump out of the gauge 102, the carrier 104 having the opposite polarity to the charge of the toner is left in the cage. In FIG. 7, reference numeral 107 denotes an electrometer.
The charge amount Q of the toner and the mass M of the protruding toner are measured, and the charge amount per unit mass is calculated as the charge amount Q / M. The toner charge amount is expressed in μC / g.
(2) Amount of spent toner For the carrier after running 100,000 sheets and the initial carrier, the toner component was extracted with methyl ethyl ketone, and the difference was defined as the spent toner amount (expressed in mass% with respect to the carrier mass) and evaluated according to the following evaluation criteria.
0% by mass: ◎ ◎ (very good)
Less than 0.03% by mass: ◎ (very good)
0.03 or more to less than 0.07% by mass: ○ (good)
0.07 or more to less than 0.15% by mass: Δ (can be used)
0.15% by mass or more: x (defect)

(3) Fluctuation rate of developer pumping amount Fluctuation rate of developer pumping amount (%) = {(initial developer pumping amount−developer pumping amount after 100,000 sheets running) / initial developer pumping amount)} × 100
Thus, the fluctuation rate of the amount of developer pumped on the developing sleeve was calculated and evaluated according to the following evaluation criteria. In the above formula, the unit of the developer pumping amount is mg / cm ² .
0%: ◎ ◎ (very good)
Less than ± 5%: ◎ (very good)
± 5 or more to less than ± 10%: ○ (good)
± 10 or more to less than ± 20%: △ (can be used)
± 20% or more: × (defect)

1 Vinyl chloride tube 2a, 2b Electrode 3 Sample (conductive fine particles)
DESCRIPTION OF SYMBOLS 10 Process cartridge 11 Cell 12a Electrode 12b Electrode 13 Carrier 20 Photoconductor drum 201 Photoconductor 21 Toner 23 Carrier particle 24a Drive roller 24b Drive roller 26 Exposure light source 32 before cleaning 32 Charging member 321 Charging roller 322 Brush-like contact charging member 33 Image exposure system 331 Light source 37 Laser light 40 Developing device 41 Developing sleeve 42 Developer containing member 43 Developer supply regulating member (doctor blade)
44 Support case 45 Toner hopper 46 Developer container 47 Developer agitation mechanism 48 Toner agitator 49 Toner replenishment mechanism 50 Transfer mechanism 51 Charger 60 Cleaning mechanism 61 Cleaning blade 62 Toner recovery chamber 64 Brush-like cleaning means 70 Static elimination lamp 80 Recording medium 101 mesh 102 conductive container (cage)
103 Toner 104 Carrier 105 Nozzle 106 Compressed nitrogen gas 107 Electrometer

Japanese Patent Laid-Open No. 55-127469 Japanese Patent Laid-Open No. 55-157751 JP-A-56-140358 JP-A-57-96355 JP 57-96356 A JP 58-207054 A JP-A-61-1110161 JP-A-62-273576 JP-A-6-338213 Japanese Patent Laid-Open No. 7-14430 Japanese Patent Laid-Open No. 7-160059

Claims (24)

An electrostatic latent image developer carrier comprising magnetic core material particles and a resin layer covering the surface of the core material particles,
The resin layer is a resin obtained by heat-treating a copolymer containing at least an A component represented by the following general formula (A) and a B component represented by the following general formula (B), and conductive fine particles Including
The carrier for an electrostatic latent image developer, wherein the concentration of the conductive fine particles in the resin layer becomes higher as it is closer to the surface of the resin layer.

(In the formula, R ¹ represents a hydrogen atom or a methyl group, R ² represents an alkyl group having 1 to 4 carbon atoms, R ³ represents an alkyl group having 1 to 8 carbon atoms or an alkoxy group having 1 to 4 carbon atoms, m Represents an integer of 1 to 8. A plurality of R ² may be the same or different, X represents 10 to 90 mol%, and Y represents 90 to 10 mol%.) The carrier for an electrostatic latent image developer according to claim 1, wherein the conductive fine particles are particles having a conductive coating layer on a surface of a substrate containing alumina.   The carrier for an electrostatic latent image developer according to claim 2, wherein the conductive coating layer of the conductive fine particles contains at least tin dioxide.   The carrier for an electrostatic latent image developer according to claim 3, wherein the conductive fine particles contain 4 to 80% by mass of tin dioxide.   The carrier for an electrostatic latent image developer according to claim 3 or 4, wherein the conductive coating layer contains at least tin dioxide and indium oxide. The carrier for an electrostatic latent image developer according to any one of claims 1 to 5, wherein the copolymer contains a copolymer represented by the following general formula (1).

(In the formula, R ¹ represents a hydrogen atom or a methyl group, R ² represents an alkyl group having 1 to 4 carbon atoms, R ³ represents an alkyl group having 1 to 8 carbon atoms or an alkoxy group having 1 to 4 carbon atoms, m Represents an integer of 1 to 8. The plurality of R ¹ and R ² may be the same or different, X is 10 to 40 mol%, Y is 10 to 40 mol%, and Z is 30 to 80 Mol%, 60 mol% <Y + Z <90 mol%) The coating of the core material particles with the resin layer is performed by coating the core material particles with a coating liquid containing the resin and conductive fine particles,
The carrier for an electrostatic latent image developer according to any one of claims 1 to 6, wherein at least the coating liquid is two or more kinds of coating liquids having different conductive fine particle contents. The time during which the core material particles are coated with each of the two or more kinds of coating liquids having different conductive fine particle contents is as follows. The carrier for an electrostatic latent image developer according to claim 7, wherein the carrier is 10 to 10 times. The amount of droplets per unit time of the coating solution supplied when the core material particles are coated with each of two or more types of coating solutions having different conductive fine particle contents is the coating amount with the smallest droplet amount. The carrier for an electrostatic latent image developer according to claim 7 or 8, wherein the droplet amount of the other coating liquid is 1 to 10 times the droplet amount of the liquid. The coating of the core material particles with the resin layer is performed by coating the core material particles with a coating liquid containing the resin and conductive fine particles,
The carrier for an electrostatic latent image developer according to any one of claims 1 to 6, wherein at least the coating liquid is at least two kinds of coating liquids having different powder specific resistances of conductive fine particles. The time during which the core material particles are coated with two or more coating liquids having different powder specific resistances of the conductive fine particles is coated with another coating liquid with respect to the coating time of the coating liquid having the shortest coating time. The carrier for an electrostatic latent image developer according to claim 10, wherein the time is 1 to 10 times. The amount of liquid droplets per unit time of the coating liquid supplied when the core material particles are coated with each of two or more types of coating liquids having different powder specific resistances of the conductive fine particles is 12. The electrostatic latent image developer carrier according to claim 10 or 11, wherein the droplet amount of the other coating liquid is 1 to 10 times the minimum droplet amount of the coating liquid. The powder specific resistance of the conductive fine particles contained in each of the two or more kinds of coating liquids having different powder specific resistances of the conductive fine particles is smaller than the powder specific resistance of the conductive fine particles having the smallest powder specific resistance. The carrier for electrostatic latent image developer according to any one of claims 10 to 12, wherein the powder specific resistance of the other conductive fine particles is 1 to 10 ⁴ times. The carrier for an electrostatic latent image developer is obtained by coating the resin layer and then heat-treating, and a heat treatment temperature during the heat-treatment is 100 to 350 ° C. 14. The carrier for an electrostatic latent image developer according to any one of items 13 to 13. The electrostatic latent image developer carrier according to claim 1, wherein the volume resistivity is 1 × 10 ⁷ to 1 × 10 ¹⁷ Ω · cm. The carrier for an electrostatic latent image developer according to claim 1, wherein the resin layer has an average film thickness of 0.05 to 4 μm. The carrier for an electrostatic latent image developer according to any one of claims 1 to 16, wherein the core particles have a weight average particle diameter of 20 to 65 µm. The electrostatic latent image developer carrier according to any one of claims 1 to 17, wherein magnetization in a magnetic field of 1 kOe is 40 to 90 Am ² / kg. An electrostatic latent image developer for developing an electrostatic latent image containing a toner and a carrier,
As the carrier, an electrostatic latent image developer, which comprises using a carrier for electrostatic latent image developer according to any one of claims 1 to 18. The electrostatic latent image developer according to claim 19, wherein the toner is a color toner. A developer for replenishment containing 2 to 50 parts by mass of toner with respect to 1 part by mass of a carrier,
A replenishment developer, wherein the carrier is a carrier for an electrostatic latent image developer according to any one of claims 1 to 18. An electrostatic latent image carrier;
Charging means for charging the electrostatic latent image carrier;
Exposure means for forming an electrostatic latent image on the charged electrostatic latent image carrier;
Developing means for developing the electrostatic latent image formed on the electrostatic latent image carrier using a developer to form a toner image;
Transfer means for transferring the toner image to a recording medium;
An image forming apparatus having fixing means for fixing the toner image transferred to the recording medium;
The image forming apparatus, wherein the developing unit uses the developer according to claim 19 or 20. An electrostatic latent image carrier, charging means for charging the surface of the electrostatic latent image carrier, and an electrostatic latent image formed on the electrostatic latent image carrier are developed using a developer. A developing unit for forming a toner image and a cleaning unit for cleaning the electrostatic latent image carrier, and a process cartridge that is detachably attached to an image forming apparatus main body;
21. A process cartridge, wherein the developing means uses the developer according to claim 19 or 20. Forming an electrostatic latent image on the electrostatic latent image carrier;
Developing the electrostatic latent image formed on the electrostatic latent image carrier using the developer according to claim 19 or 20 to form a toner image;
Transferring the toner image formed on the electrostatic latent image carrier to a recording medium;
And a step of fixing the toner image transferred to the recording medium.

Images