JP2003345070A - Electrophotographic carrier, developer and image forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide electrophotographic carrier for two-component developer whose durability is high, developer, an image forming method, a storing container and an image forming apparatus. <P>SOLUTION: In the electrophotographic carrier possessing coating film consisting of at least binding resin and particles, the particle size (D) of the particles and the film thickness (h) of the coating film satisfy the relation of 1<[D/h]<10, and surface processing with single or two or more kinds of aluminum based coupling agents shown by a general expression (1) is applied to the particles or/and the coating film incorporates single or two or more kinds of the aluminum based coupling agents shown by the expression (1). <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a carrier, a developer, an image forming method, a storage container and an image forming apparatus used for electrostatic image development in electrophotography, electrostatic recording, electrostatic printing and the like.

[0002]

2. Description of the Related Art Generally, in image forming methods such as electrophotography and electrostatic photography, toner and carrier are mixed by stirring in order to develop an electrostatic latent image formed on a latent image bearing member. The developer obtained by is used. The developer is required to be a properly charged mixture. Generally, as a method for developing an electrostatic latent image, a method using a two-component developer obtained by mixing a toner and a carrier and a method using a one-component developer containing no carrier are known. . The developing method using the former two-component developer, while a relatively stable and good image can be obtained,
There is a drawback that carrier deterioration and variation in the mixing ratio of toner and carrier are likely to occur. On the other hand, the latter one-component developer does not have the drawbacks of the former, but has the disadvantage that the chargeability is difficult to stabilize.

Further, when the electrostatic latent image is repeatedly developed using a two-component developer, the toner in the developer is consumed and the toner density fluctuates, so that a stable image is obtained during printing. In addition, it is necessary to replenish the toner as necessary to suppress this fluctuation. Generally, as a method for controlling the toner supply amount, a copying machine is equipped with a transparency detection sensor, a fluidity detection sensor, an image density detection sensor, a bulk density detection sensor, etc. Is the mainstream these days. The sensor is a system that controls a toner replenishment amount by developing a certain image pattern on a latent image carrier and detecting an image density from reflected light.

The carrier used in such a two-component developing system is granular, and prevents the filming of the toner on the surface of the carrier, the formation of a uniform surface of the carrier, the prevention of surface oxidation, the prevention of deterioration of moisture sensitivity, and the development of the developer. For the purpose of extending the service life, protecting the photoreceptor from scratches or abrasion by the carrier, controlling the charge polarity or adjusting the charge amount, etc., a coating layer with a solid and high strength is usually provided by coating with a suitable resin material. Is being done. For example, those coated with a specific resin material (Japanese Patent Laid-Open No. 58-108548) and those to which various additives are added to the coating layer (Japanese Patent Laid-Open No.
4-155048, JP-A-57-40267, JP-A-58-108549, JP-A-59-1.
No. 66968, Japanese Patent Publication No. 1-19584, Japanese Patent Publication No. 3-628, and Japanese Unexamined Patent Publication No. 6-202381), and one in which an additive is attached to the carrier surface (Japanese Unexamined Patent Publication No. 5-273789). Japanese Patent Laid-Open No. 9-160304) and the like, in which conductive particles larger than the coating film thickness are contained in the coating film are disclosed. Further, JP-A-8-6307 describes that a benzoguanamine-n-butyl alcohol-formaldehyde copolymer is used as a main component in a carrier coating material, and JP-A-2683624 discloses a melamine resin and an acrylic resin. It is described that the crosslinked product of 1) is used as a carrier coating material.

However, the durability is still insufficient, and there are problems such as spent on the carrier surface of the toner, destabilization of the charge amount, and resistance reduction due to abrasion of the coating resin. However, the image quality of the copied image deteriorates as the number of copies increases, and therefore improvement is required. Therefore, JP-A-2
In 001-188388, it is reported that these problems can be solved by defining the relationship between the particle diameter and the binder resin film thickness and by defining the specific resistance of the particles. Certainly the effect is remarkable compared to the past,
Recently, the demand for the durability of the developer is further increasing, and further improvement is desired. Further, it has been clarified that the combination of the toner containing the releasing agent and the carrier proposed in Japanese Patent Laid-Open No. 2001-188388 does not provide the same effect as the toner containing no releasing agent. Japanese Patent Laid-Open No. 2001-2001
The commercially available digital full-color copying machine described in Japanese Patent Laid-Open No. 188388 is composed of a toner containing no release agent and a developer.

In recent years, there has been a great demand for space saving in both copying machines and printers, and in response to this demand, it has been attempted to omit the fixing oil or apply a small amount of it to reduce the size of the fixing unit. In this case, since the toner has a toner composition containing a release agent, there is a great demand for a carrier having high durability even in combination with the toner containing the release agent.

[0007]

SUMMARY OF THE INVENTION The first object of the present invention has been made in view of the above circumstances, and it is an electrophotographic carrier for a two-component developer having higher durability, a developer, an image forming method, A storage container and an image forming apparatus are provided. A second object is to provide an electrophotographic carrier, a developer, an image forming method, a storage container, and an image forming apparatus which are highly durable even in combination with a toner containing a release agent.

[0008]

According to the present invention, the above object is achieved by the following means. That is, the present invention according to claim 1 provides an electrophotographic carrier having a coating film comprising at least a binder resin and particles, wherein the particle diameter (D) of the particles and the film thickness (h) of the coating film are 1 <[D / h] <
The relationship is 10, and the particles are surface-treated with an aluminum-based coupling agent represented by the following general formula (1) alone or in combination of two or more.

[Chemical 2] The present invention according to claim 2 provides an electrophotographic carrier having a coat film comprising at least a binder resin and particles, wherein the particle diameter (D) of the particles and the film thickness (h) of the coat film are 1 <[. D / h] <10 and the coating film contains the aluminum-based coupling agent represented by the general formula (1) alone or in combination of two or more. According to a third aspect of the present invention, in a carrier for electrophotography having a coating film composed of at least a binder resin and particles, the particle diameter (D) of the particles and the film thickness (h) of the coating film are 1 <[ D / h] <10, the particles are surface-treated with the aluminum-based coupling agent represented by the general formula (1) alone or in combination of two or more, and the coating film has the general formula (1). ) An aluminum-based coupling agent is contained alone or in combination of two or more, and a carrier for electrophotography is provided.

The present invention according to claim 4 provides the electrophotographic carrier according to any one of claims 1 to 3, wherein the specific resistance of the particles is 10 ¹² (Ω · cm) or more. . The present invention according to claim 5 is characterized in that the particles are alumina and / or silica.
The electrophotographic carrier according to any one of 1 to 4. The present invention according to claim 6 provides the electrophotographic carrier according to any one of claims 1 to 5, wherein the content of the particles is 40 to 95 wt% of the coating film composition component. According to a seventh aspect of the present invention, there is provided the electrophotographic carrier according to any one of the first to sixth aspects, wherein the binder resin has a film thickness of 0.05 μm to 1.00 μm. The present invention according to claim 8 is characterized in that the binder resin contains at least a resin obtained by a crosslinking reaction of an acrylic resin and an amino resin, and / or a silicone resin. The carrier for electrophotography according to any one of the above. The present invention according to claim 9 provides the electrophotographic carrier according to any one of claims 1 to 8, wherein the binder resin has a Tg of 20 to 100 ° C.

The present invention according to claim 10 comprises a toner comprising at least a binder resin and a pigment, and the electrophotographic carrier according to any one of claims 1 to 9. Use as a developer. The present invention according to claim 11 provides the electrophotographic developer according to claim 10, wherein the toner contains a release agent. Claim 12
The present invention described in 1 is an image forming method characterized by using the electrophotographic developer described in 10 or 11 above.
According to a thirteenth aspect of the present invention, there is provided a multicolor image forming method using the electrophotographic developer according to the tenth or eleventh aspect. According to a fourteenth aspect of the present invention, there is provided a container which is filled with the electrophotographic developer according to the tenth or eleventh aspect. According to a fifteenth aspect of the present invention, there is provided an image forming apparatus including the container filled with the electrophotographic developer according to the fourteenth aspect.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in more detail below. As a result of continuing studies to solve the above-mentioned problems of the prior art, the present inventors have found that, in an electrophotographic carrier having a coat film composed of at least a binder resin and particles, the particle diameter (D) of the particles. And the film thickness (h) of the coating film are in the relationship of 1 <[D / h] <10, and the particles are surface-treated with an aluminum-based coupling agent represented by the following general formula (1) alone or in combination of two or more. It was found that the improvement effect was remarkable by the treatment.

[Chemical 3]

In the formula, R1 to R3 are a hydrogen atom, a halogen atom, an alkyl group which may have a substituent, an aralkyl group which may have a substituent, an alkenyl group which may have a substituent, and a substituent. Represents an aromatic ring group which may have a group, an acyl group which may have a substituent or an alkylsulfonyl group which may have a substituent, and at least one or more of R1 to R3 is -R4- ( CF2) nCF3 (in the formula, R4 may have a substituent, an alkyl group which may have a substituent, an aralkyl group which may have a substituent, an alkenyl group which may have a substituent, and a substituent which may have a substituent). An aromatic ring group, an acyl group which may have a substituent, an alkylsulfonyl group which may have a substituent or = CF2, and n is an integer of 0 or more and 10 or less).

Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a tert-butyl group, a hexyl group and an octyl group.
Examples of the aralkyl group include a benzyl group, a styryl group, a cinnamyl group, a trityl group and a phenethyl group,
Examples of the alkenyl group include a vinyl group and an allyl group, examples of the aromatic ring group include a phenyl group, naphthyl group, and pyridyl group, and examples of the acyl group include a formyl group and
Acetyl group, malonyl group, benzoyl group and the like,
Examples of the alkylsulfonyl group include a benzenesulfonyl group, a methylsulfonyl group, an ethylsulfonyl group, and the like. The substituent which the above group may have, a fluorine atom, a halogen atom such as a chlorine atom and a bromine atom, a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a tertiary butyl group, a hexyl group and octyl. And alkyl groups such as groups, and phenyl groups and aryl groups such as naphthyl groups.

This is because the particles are more convex than in the coating film, so that the developer is agitated to frictionally charge the toner, or the toner is rubbed with each other or the carriers are rubbed with each other, which causes a strong impact on the binder resin. Contact can be eased. As a result, it is possible to prevent the spent of the toner on the carrier, and it is also possible to prevent the film of the binder resin, which is the charging generation site, from being scraped. However, since the convex portion, that is, the portion of the particle relaxes the contact with the binder resin with a strong impact, the particle itself is always in a state of being easily detached from the coat film. In order to cope with higher durability, it is necessary to suppress the detachment of the particles,
According to the present inventor, it is possible to suppress desorption of the particles by surface-treating the particles with the aluminum-based coupling agent represented by the general formula (1) alone or in combination of two or more kinds. became. This is because the adhesion between the particles and the binder resin in the coat film was increased, and the detachment of the particles was suppressed. In the case of a toner containing a release agent, the release agent was the center for accelerating the detachment of the particles, but the release property was increased due to the increased adhesiveness between the particles and the binder resin in the coating film. The effect is comparable to that of the toner containing the agent.

According to the present inventors, the relationship between the particle diameter (D) of the particles and the film thickness (h) of the coat film [D /
It was revealed that there is a specific range for h]. When [D / h] is 1 or less, the particles are buried in the binder resin, and the effect is remarkably reduced, which is not preferable.
Conventionally, if [D / h] is set to 5 or more, a sufficient binding force cannot be obtained because the contact area between the particles and the binder resin is small,
It was not preferable because the particles would easily detach,
Since the particles are surface-treated with the aluminum-based coupling agent represented by the general formula (1) alone or in combination of two or more, the adhesiveness with the binder resin is increased, and even in the case of 5 or more and 10 or less. The particles do not detach, and it becomes possible to obtain the convexities of the coating film. The molecular weight of the aluminum-based coupling agent represented by the general formula (1) is not particularly limited, but from the viewpoint of easiness of surface treatment, it is better that the viscosity is not too high. Tens of thousands are suitable.

There are two types of surface treatment methods used in the present invention, wet type and dry type. In the wet method, the particles and the aluminum-based coupling agent represented by the general formula (1) are dispersed in a solvent, and the aluminum-based coupling agent is attached to the surface of the particles. As a dispersing means, a general dispersing means such as a ball mill and a sand mill can be used. Next, this dispersion solution is dried by a drier to remove the solvent, and then further heat-treated to fix the aluminum-based coupling agent to the surface of the particles. If necessary, the treated particles may be subjected to a pulverization treatment. In the dry treatment, the aluminum-based coupling agent and the conductive metal oxide fine particles are mixed and kneaded without using a solvent, so that the aluminum-based coupling agent is attached to the surface of the fine particles. Thereafter, similar to the wet treatment, heat treatment, pulverization treatment, etc. are performed to complete the surface treatment.

The same effects can be obtained not only by surface-treating the particles of the aluminum-based coupling agent, but also by adding one or two or more of them in the coating film. Furthermore, the effect is more remarkable when the particles are surface-treated and the particles are contained in the coating film in combination. These amounts depend on the particle size of the particles and the structure of the aluminum-based coupling agent, but are preferably 0.01 to 50 parts by weight with respect to 100 parts by weight of the particles. More preferably, the amount is 0.05 to 40 parts by weight.

Compounds preferable as the aluminum-based coupling agent represented by the general formula (1) are shown in Tables 1 to 1 below.
However, the present invention is not limited to these compounds.

[Table 1]

[0019]

[Table 2]

[0020]

[Table 3]

According to the present invention, it is effective that the specific resistance of the particles is 10 ¹² (Ω · cm) or more in order to suppress the decrease in the charge amount when the developer is stored for a long period of time. This is because even if the particles have a contact with the core material and are exposed on the surface, leakage of charges is suppressed, so that stable chargeability can be obtained. On the other hand, the specific resistance of the particles is 1
If it is less than 0 ¹² (Ω · cm), leakage of electric charge cannot be suppressed, so that stable chargeability cannot be obtained, which is not preferable. Further, as mentioned in the above-mentioned prior art, a technique similar to the present invention, in which conductive particles larger than the film thickness of the coating resin are contained in the coating film (JP-A-9-160304).
The present invention is characterized in that, in the present invention, the particles are not used as a resistance adjusting material as in the prior art, but are used as a protective material for a coating film resin and a surface shape adjusting material. Further, the aluminum-based coupling agent represented by the general formula (1) is essential for suppressing the detachment of the particles.

Further, the effect is remarkable when the particles are alumina and the content thereof is in the range of 40 to 95 wt% of the coating film composition component, preferably 70 to 90 wt%. Further, the particles are silica and the content is in the range of 40 to 95 wt% of the coating film composition component, preferably 70 to 90.
The effect is remarkable when it is wt%. Further, alumina and silica may be mixed and used. When the content of the particles is less than 50 wt%, the ratio of the particles is smaller than the ratio of the binder resin on the surface of the carrier particles, so that the contact with the binder resin with a strong impact is mitigated. Since the effect of doing so is small, sufficient durability cannot be obtained, which is not preferable. On the other hand, when the content is more than 95 wt%, the ratio of the particles is too large as compared with the ratio of the binder resin on the surface of the carrier, so that the ratio of the binder resin, which is the charging generation site, becomes insufficient. It cannot exhibit sufficient charging ability. In addition, since the amount of the particles is too large compared to the amount of the binder resin, the ability of the binder resin to hold the particles becomes insufficient and the particles are easily detached, which is not preferable because sufficient durability cannot be obtained.

The present invention is different from the above-mentioned similar prior art in the content range of particles, and the technology is "0.01 to 50% by weight of the coating resin", that is, the present invention. When converted to the content rate calculation method, the content is “0.01 to 33.33 wt% of the coating film composition component”. In this case,
Durability is improved compared to the past, but as mentioned earlier,
Since the proportion of the binder resin on the surface of the carrier particles is smaller than that of the binder resin, the effect of alleviating contact with a strong impact on the binder resin is small and sufficient durability cannot be obtained, which is not preferable. .

According to the present invention, it is important that the binder resin contains a resin obtained by crosslinking an acrylic resin and an amino resin and / or a silicone resin. As the amino resin, it is possible to use a conventionally known amino resin, but by using guanamine or melamine, the charge amount imparting ability is remarkably improved. A conventionally known silicone resin can be used as the silicone resin. In addition to the resins listed here, resins generally used as a coating resin for carriers can be used, and, of course, they may be used in combination with the above resins. For example, polystyrene resin,
Poly (meth) acrylic resin, polyolefin resin,
Polyamide resin, polycarbonate resin, polyether resin, polysulfinic acid resin, polyester resin, epoxy resin, polybutyral resin, urea resin, urethane / urea resin, polyethylene resin,
Various thermoplastic resins such as Teflon (registered trademark) resins, thermosetting resins and mixtures thereof, and copolymers, block polymers, graft polymers and polymer blends of these resins, but not limited to these is not.

According to the present invention, the Tg of the binder resin is 2
It is preferable to use one having a temperature of 0 to 100 ° C, preferably 25 to 80 ° C. When the Tg of the resin is within this range, the resin has an appropriate elasticity, and due to the friction between the toner and the carrier or the friction between the carriers during the stirring for triboelectrifying the developer, the resin to the binder resin is Upon contact with a strong shock, the shock can be absorbed and the coat film can be maintained without being damaged. Also, Tg is 2
If the temperature is 0 ° C. or lower, the binder resin blocks even at room temperature, so that the storage stability is poor and the composition cannot be practically used, which is not preferable. On the other hand, when Tg is 100 ° C. or higher, the binder resin becomes too hard and brittle so that the impact cannot be absorbed, the binder resin is scraped from the brittleness, and the particles can be retained. However, it is not preferable because it is easily released.

The core material of the carrier is at least 2 in terms of preventing the carrier from adhering (scattering) to the electrostatic latent image carrier.
The particle size of 0 μm (average particle size) is used, and the particle size of 100 μm at most is used from the viewpoint of preventing deterioration of image quality such as generation of carrier stripes. As a specific material, a known one as a two-component carrier for electrophotography, for example, ferrite, magnetite, iron, nickel, etc., may be appropriately selected and used according to the use and purpose of use of the carrier.

Further, carbon black, an acid catalyst, zinc oxide, titanium oxide, tin oxide, indium oxide, bismuth oxide, tin-doped indium oxide, and antimony are doped as a charging and resistance adjusting agent for obtaining a desired resistance. Ultrafine particles such as tin oxide and zirconium oxide can be used. These resistance adjusting agents are used alone or in combination of two or more. When two or more kinds are mixed, they may be in the form of solid solution or fusion. As the carbon black, any of those generally used for carriers or toners can be used. The acidic catalyst is
Those having a catalytic action can be used. For example, those having a reactive group such as fully alkylated type, methylol group type, imino group type, and methylol / imino group type,
It is not limited to these. The carrier is used as a two-component developer composed of toner, but the composed toner may be black toner or multicolor toner used in the multicolor image forming method.

The image forming apparatus of the present invention will be described below with reference to the drawings. FIG. 1 shows an example of an image forming apparatus equipped with a container filled with a developer using the electrophotographic carrier of the present invention. Here, a developing section (1) mounted in the main body of the image forming apparatus and a developer storage container (2) filled with a developer using the electrophotographic carrier of the present invention to be replenished to the developing section (1). ) And a developer flow means (3) for connecting the two).

The developing section (1) includes a developing housing (4) containing a two-component developer (D) in which toner and carrier are mixed, and first and second stirring screws for stirring and mixing the developer (D). It has (5) and (6) and a developing roller (7), and the developing roller (7) is arranged to face the photoconductor (8) of the latent image carrier. Photoreceptor (8)
Is rotationally driven in the direction indicated by the arrow, and an electrostatic latent image is formed on the surface thereof. Reference numeral (26) in the figure denotes a connecting member (2
4) A cap fitted on or above the filter (25). Around the photoconductor (8), a charging means, an exposing means, a transferring means, a discharging means, which are not shown,
Other known units such as cleaning means are arranged. First and second stirring screws (5),
By rotating (6), the developer (D) in the developing housing (4) is agitated, and the toner is triboelectrically charged so that the carrier has opposite polarities. The developer (D) is
The developer supplied to the peripheral surface of the developing roller (7) which is rotationally driven in the direction of the arrow is carried on the peripheral surface of the developing roller (7), and by the rotation of the developing roller (7),
It is conveyed in the rotation direction. Next, the amount of the transported developer is regulated by the doctor blade (9), and the regulated developer is removed from the photoconductor (8) and the developing roller (7).
The toner in the developer is electrostatically transferred to the electrostatic latent image on the surface of the photoconductor, and the electrostatic latent image is visualized as a toner image. .

[0030]

EXAMPLES Next, the present invention will be explained more specifically with reference to Examples and Comparative Examples, but the present invention is not limited to these. An example of toner production will be described below. <Toner Production Example 1: Black Toner 1> Water: 1200 parts, phthalocyanine green hydrous cake (solid content: 30%): 200 parts, carbon black (trade name MA60; manufactured by Mitsubishi Chemical Corporation): 540 parts were thoroughly stirred with a flasher. . Here, epoxy resin (Mn; 350
0): 1200 parts were added and kneaded at 150 ° C. for 30 minutes, then xylene: 1000 parts were added and further kneaded for 1 hour. After removing water and xylene, the mixture was cooled by rolling and pulverized with a palpelizer to obtain a masterbatch pigment. Next, epoxy resin (Mn; 3
500): 100 parts, the above masterbatch pigment: 5 parts,
Zinc salicylate derivative (trade name: Bontron E84; Orient Chemical Co., Ltd.): 4 parts were mixed with a mixer, melt-kneaded with a two-roll mill, and the kneaded product was rolled and cooled. Then, pulverization and classification were performed to obtain a toner having a weight average particle diameter of 7.8 μm. Further, an additive such as silica was added to impart fluidity and mixed with a Henschel mixer to obtain Black Toner 1.

<Toner Production Example 2: Black Toner 2> Toner Production Example 1 was produced in the same manner as in Production Example 1 except that 5 parts of carnauba wax was added.

The production examples of the surface-treated particles are shown below. <Production Example of Surface-treated Particles 1: Alumina Particles 1> Alumina (0.3 μm, specific resistance 10 ¹⁴ Ω was added to a solution containing 5 parts by weight of an aluminum coupling agent and 495 parts by weight of acetone shown in Exemplified Compound 1 of Table 1.・ Cm) particles: 50 parts by weight of the particles are added, and the mixture is stirred for 2 hours, subsequently filtered to remove the solvent, and dried at 120 ° C. for 2 hours.
Alumina particles 1 surface-treated with the aluminum-based coupling agent were obtained.

<Production Example 2 of surface-treated particles: Alumina particles 2
> Alumina (0.3 μm, specific resistance 10 ¹⁴ Ω · cm) particles: 50 parts by weight was added to a solution consisting of 5 parts by weight of an aluminum-based coupling agent shown in Exemplified Compound 7 in Table 1 and 495 parts by weight of acetone. The mixture was stirred for a time, then filtered to remove the solvent, and dried at 120 ° C. for 2 hours to obtain alumina particles 2 surface-treated with the aluminum-based coupling agent of Exemplified Compound 7.

<Production Example 3 of surface-treated particles: Alumina particles 3
> Alumina (0.3 μm, specific resistance of 10 ¹⁴ Ω · cm) particles: 50 parts by weight was added to a solution consisting of 5 parts by weight of aluminum-based coupling agent shown in Exemplified Compound 13 in Table 2 and 495 parts by weight of acetone. The mixture was stirred for a time, then filtered to remove the solvent, and dried at 120 ° C. for 2 hours to obtain alumina particles 3 surface-treated with the aluminum-based coupling agent of Exemplified Compound 13.

An example of manufacturing a carrier is shown below. <Carrier Production Example 1: Carrier 1> Acrylic resin solution (solid content 50% by weight): 56.0 parts,
Guanamine solution (solid content 77% by weight): 15.6 parts, alumina particles 1: 1160.0 parts, toluene: 900 parts,
Butyl cellosolve: 900 parts was dispersed with a homomixer for 10 minutes to prepare a coating film forming solution. Using a sintered ferrite powder (trade name F-300; average particle size 50 μm; manufactured by Powdertec Co., Ltd.) as a core material, the above coating film forming solution was applied on a surface of the core material by a Spira coater (Okada). It was applied and dried by Seiko. The obtained carrier was left standing in an electric furnace at 300 ° C. for 2 hours for firing. After cooling, the ferrite powder bulk was crushed using a sieve having openings of 100 μm to obtain Carrier 1. In the binder resin film thickness measurement, the coating film covering the carrier surface can be observed by observing the carrier cross section with a transmission electron microscope. Therefore, the average value of the film thickness was taken as the film thickness.

<Carrier Production Example 2: Carrier 2> All were produced in the same manner as Carrier Production Example 1 except that the alumina particles 1 in Carrier Production Example 1 were changed to alumina particles 2.

<Carrier Production Example 3: Carrier 3> All were produced in the same manner as Carrier Production Example 1 except that the alumina particles 1 of Carrier Production Example 1 were changed to alumina particles 3.

<Production Example of Carrier 4: Carrier 4> Acrylic resin solution (solid content 50% by weight): 56.0 parts,
Guanamine solution (solid content 77% by weight): 15.6 parts, alumina particles (0.3 μm, specific resistance 10 ¹⁴ Ω · cm):
160.0 parts, aluminum-based coupling agent shown in Exemplified Compound 4 in Table 1: 1.0 part, toluene: 900 parts, butyl cellosolve: all except that the formulation was changed to 900 parts were produced in the same manner as in Carrier Preparation Example 1. .

<Carrier Production Example 5: Carrier 5> Except that the aluminum-based coupling agent of Exemplified Compound 4 of Carrier Production Example 4 was changed to Exemplified Compound 10 of Table 2, all were produced in the same manner as in Carrier Production Example 4.

<Carrier Production Example 6: Carrier 6> All were produced in the same manner as Carrier Production Example 4 except that the aluminum-based coupling agent of Exemplified Compound 4 of Carrier Production Example 4 was changed to Exemplified Compound 13 of Table 2.

<Carrier Production Example 7: Carrier 7> All were produced in the same manner as Carrier Production Example 4 except that the alumina particles of Carrier Production Example 4 were changed to Alumina particles 1.

<Production Example of Carrier 8: Carrier 8> Acrylic resin solution (solid content 50% by weight): 56.0 parts,
Guanamine solution (solid content 77% by weight): 15.6 parts, alumina particles (0.3 μm, specific resistance 1014 Ω · c)
m): 160.0 parts, toluene: 900 parts, butyl cellosolve: 900 parts except that the formulation was changed to the same as in Carrier Production Example 1.

Example 1 The carrier 1 thus obtained and the black toner 1 were placed in a ball mill and mixed for 10 minutes so as to have a toner concentration of 5% to obtain a developer. The developer and the black toner 1 were set in a commercially available digital full-color copying machine (imagioColor2800; manufactured by Ricoh Co., Ltd.), and running evaluation of 600,000 sheets was performed. Table 4 below shows the results of obtaining the charge reduction amount and the resistance reduction amount of the carrier after the running.
As used herein, the amount of decrease in charge amount means a charge amount measuring device (TB-200; by a general blow-off method) of a sample obtained by mixing and triboelecting a toner in an amount of 5 wt% with respect to 95 wt% of an initial carrier. From the charge amount (Q1) measured by Toshiba Chemical Co., Ltd., the carrier obtained by removing the toner in the developer after running by the blow-off device is
It refers to the amount obtained by subtracting the charge amount (Q2) measured by the same method as described above, and the target value is 7.0 (μc / g) or less. Further, the cause of the decrease in the charge amount is toner spent on the surface of the carrier. Therefore, by reducing the toner spent, the decrease in charge amount can be suppressed. The amount of resistance decrease means that an initial carrier is injected between parallel electrodes for resistance measurement: electrodes with a gap of 2 mm, and DC200V is applied to
A carrier obtained by removing the toner in the developer after running by the blow-off device from the value (1) obtained by converting the resistance value after sec measured by a high resist meter into a volume resistivity (1) is measured by the resistance measurement. It is the amount obtained by subtracting the value (2) measured by the same method as the method, and the target value is 2.0.
(Log (Ω · cm)) or less. Further, since the cause of the resistance decrease is the abrasion of the binder resin film of the carrier, it is possible to suppress the amount of resistance reduction by reducing the abrasion of the film.

Example 2 Black Toner 1 of Example 1
All were evaluated in the same manner as in Example 1 except that black toner 2 was used. The evaluation results are shown in Table 4.

Example 3 All evaluations were made in the same manner as in Example 2 except that the carrier 1 in Example 2 was changed to the carrier 2. The evaluation results are shown in Table 4.

Example 4 All evaluations were made in the same manner as in Example 2 except that the carrier 1 in Example 2 was changed to the carrier 3. The evaluation results are shown in Table 4.

<Embodiment 5> Evaluation was made in the same manner as in Embodiment 2 except that the carrier 1 in Embodiment 2 was changed to the carrier 4. The evaluation results are shown in Table 4.

Example 6 Evaluations were made in the same manner as in Example 2 except that the carrier 1 in Example 2 was changed to the carrier 5. The evaluation results are shown in Table 4.

Example 7 Evaluations were made in the same manner as in Example 2 except that the carrier 1 of Example 2 was changed to the carrier 6. The evaluation results are shown in Table 4.

<Embodiment 8> Evaluation was made in the same manner as in Embodiment 2 except that the carrier 1 in Embodiment 2 was changed to the carrier 7. The evaluation results are shown in Table 4.

Comparative Example 1 Evaluations were made in the same manner as in Example 1 except that the carrier 1 in Example 1 was changed to the carrier 8. The evaluation results are shown in Table 4.

Comparative Example 2 The same evaluation as in Example 1 was carried out except that the carrier 2 in Example 2 was changed to the carrier 8. The evaluation results are shown in Table 4.

[0053]

[Table 4] From Table 4, by using the carrier of the present invention, the effect more than double the conventional durability was obtained. Further, in the combination with the toner containing the release agent, the effect of 6 times or more was obtained as compared with the conventional result.

[0054]

As is apparent from the above description, according to the present invention, there are provided a highly durable electrophotographic carrier for a two-component developer, a developer, an image forming method, a storage container and an image forming apparatus. It will be possible. Further, it is possible to provide a highly durable electrophotographic carrier, developer, image forming method, storage container and image forming apparatus even in combination with a toner containing a release agent.

[Brief description of drawings]

FIG. 1 is a diagram showing a container filled with the electrophotographic developer of the present invention and an image forming apparatus equipped with the container.

[Explanation of symbols]

1 development department 2 developer storage container 3 developer feeding means 4 Development housing 5 stirring screw 6 stirring screw 7 developing roller 8 photoconductor 9 doctor blade 24 Connection member 25 filters 26 caps D developer

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Masahide Yamashita             1-3-3 Nakamagome, Ota-ku, Tokyo Stocks             Company Ricoh (72) Inventor Kosuke Suzuki             1-3-3 Nakamagome, Ota-ku, Tokyo Stocks             Company Ricoh (72) Inventor Tomomi Tamura             1-3-3 Nakamagome, Ota-ku, Tokyo Stocks             Company Ricoh F-term (reference) 2H005 AA06 BA06 BA07 CA02 CA12                       CA14 CA17 CA25 CB07 CB13                       EA01 EA03 EA05 EA10

Claims (15)

[Claims] 1. In an electrophotographic carrier having a coat film comprising at least a binder resin and particles, the particle diameter (D) of the particles and the film thickness (h) of the coat film are
1 <[D / h] <10, wherein the particles are surface-treated with an aluminum-based coupling agent represented by the following general formula (1) alone or in combination of two or more. For carrier. [Chemical 1] (In the formula, R1 to R3 represent a hydrogen atom, a halogen atom, an alkyl group which may have a substituent, an aralkyl group which may have a substituent, an alkenyl group which may have a substituent, and a substituent. An optionally substituted aromatic ring group, an optionally substituted acyl group or an optionally substituted alkylsulfonyl group, wherein at least one of R1 to R3 is -R4-
(CF2) nCF3 (In the formula, R4 is an alkyl group which may have a substituent, an aralkyl group which may have a substituent, an alkenyl group which may have a substituent, and a substituent which may have a substituent. Is a good aromatic ring group, an acyl group which may have a substituent, an alkylsulfonyl group which may have a substituent or = CF2, and n is an integer of 0 or more and 10 or less). 2. An electrophotographic carrier having a coating film comprising at least a binder resin and particles, wherein the particle diameter (D) of the particles and the film thickness (h) of the coating film are
1 <[D / h] <10, wherein the coating film contains the aluminum-based coupling agent represented by the general formula (1) alone or in combination of two or more. 3. An electrophotographic carrier having a coat film comprising at least a binder resin and particles, wherein the particle diameter (D) of the particles and the film thickness (h) of the coat film are
1 <[D / h] <10, and the particles are surface-treated with the aluminum-based coupling agent represented by the general formula (1) alone or in combination of two or more kinds, A carrier for electrophotography, which contains the aluminum-based coupling agent represented by the formula (1) alone or in combination of two or more kinds. 4. The specific resistance of the particles is 10 ¹² (Ω · c).
m) or more, The electrophotographic carrier according to any one of claims 1 to 3, wherein: 5. The electrophotographic carrier according to claim 1, wherein the particles are alumina and / or silica. 6. The electrophotographic carrier according to claim 1, wherein the content of the particles is 40 to 95 wt% of the coating film composition component. 7. The film thickness of the binder resin is from 0.05 μm to
7. The electrophotographic carrier according to claim 1, which has a thickness of 1.00 μm. 8. The electron according to claim 1, wherein the binder resin contains at least a resin obtained by crosslinking reaction of an acrylic resin and an amino resin or / and a silicone resin. Photo carrier. 9. The Tg of the binder resin is 20 to 100 ° C.
The carrier for electrophotography according to claim 1, wherein 10. An electrophotographic developer comprising a toner comprising at least a binder resin and a pigment, and the electrophotographic carrier according to claim 1. 11. The electrophotographic developer according to claim 10, wherein the toner contains a release agent. 12. An image forming method using the electrophotographic developer according to claim 10. 13. A multicolor image forming method using the electrophotographic developer according to claim 10. 14. A container filled with the electrophotographic developer according to claim 10 or 11. 15. An image forming apparatus equipped with a container filled with the electrophotographic developer according to claim 14.