JP4513010B2 - Electrophotographic carrier, developer, image forming method, and developer container - Google Patents

Description

  The present invention relates to a carrier used for developing an electrostatic latent image in electrophotography, electrostatic recording, electrostatic printing, and the like, a developer, an image forming method, and a container for storing the developer.

  In general, in image forming methods such as electrophotography and electrostatic photography, a developer obtained by stirring and mixing a toner and a carrier in order to develop an electrostatic latent image formed on a latent image carrier. Is used. This developer is required to be a suitably charged mixture. In general, 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 former developing method using a two-component developer can provide a relatively stable and good image, but has a drawback that carrier deterioration and fluctuation in the mixing ratio of the toner and the carrier are likely to occur. On the other hand, the latter one-component developer does not have the disadvantages of the former, but has the disadvantage that the chargeability is difficult to stabilize.

  When developing an electrostatic latent image repeatedly using a two-component developer, the toner in the developer is consumed and the toner density fluctuates, so it is necessary to obtain a stable image during printing. Accordingly, it is necessary to replenish toner and suppress this fluctuation. In general, as a method for controlling the toner replenishment amount, a copying machine has a permeability detection sensor, a fluidity detection sensor, an image density detection sensor, a bulk density detection sensor, etc., but an image density detection sensor is used. Is the mainstream these days. This sensor is a method for controlling a toner replenishment amount by developing a fixed image pattern on a latent image carrier and detecting an image density from reflected light.

  The granular carrier used in such a two-component development system is capable of preventing toner filming on the carrier surface, forming a uniform carrier surface, preventing surface oxidation, preventing moisture sensitivity deterioration, extending the life of the developer, and photosensitive. For the purpose of protecting the body from scratches or abrasion by the carrier, controlling the charge polarity, or adjusting the charge amount, it has been practiced to provide a hard and high-strength coating layer usually by coating with an appropriate resin material. . Such conventional carriers are, for example, those coated with a specific resin material (see, for example, Patent Document 1), and those in which various additives are added to the coating layer (for example, see Patent Documents 2 to 8). ), Those using an additive added to the carrier surface (for example, see Patent Document 9), and those using a coating film containing conductive particles larger than the coating thickness (for example, patents) Reference 10) is disclosed. In addition, a method using a coating material mainly composed of a benzoguanamine-n-butyl alcohol-formaldehyde copolymer as a carrier (for example, see Patent Document 11), a cross-linked product of a melamine resin and an acrylic resin is used as a carrier coating material. There is known a method used as (see, for example, Patent Document 12).

  However, the carrier according to the above-described conventional technique still has insufficient durability, and there are problems such as spent on the carrier surface of the toner, destabilization of the charge amount associated therewith, and resistance reduction due to scraping of the coating resin. That is, a good image can be obtained in the initial stage, but as the number of copies increases, the image quality of the copied image decreases, so further improvement is desired. Therefore, there is a report that these problems can be solved by defining the relationship between the particle diameter and the binder resin film thickness and defining the specific resistance of the particles (see, for example, Patent Document 13). Certainly, the effect is remarkable as compared with the conventional electrophotographic carrier, but the demand for the durability of the developer is increasing recently, and further improvement is desired. It has also been clarified that the combination of a toner containing a release agent and its carrier cannot provide the same effect as a toner containing no release agent. A commercially available digital full-color copying machine using the prior art is composed of a combination of toner and developer that does not contain a release agent.

  In recent years, there are many requests for space saving in both copying machines and printers. To meet this demand, it is possible to omit the fixing oil in the electrophotographic process or to reduce the fixing part by applying a small amount of fixing oil. It has been. In this case, since the apparatus is configured using toner containing a release agent, there is a great demand for a carrier that is highly durable even when combined with toner containing a release agent.

JP 58-108548 A JP 54-1555048 A JP 57-40267 A JP 58-108549 A JP 59-166968 A Japanese Patent Publication No. 1-19584 Japanese Examined Patent Publication No. 3-628 JP-A-6-202381 JP-A-5-273789 JP-A-9-160304 JP-A-8-6307 Japanese Patent No. 2683624 JP 2001-188388 A

In view of the above circumstances, an object of the present invention is to provide an electrophotographic carrier that is highly durable even when combined with a toner containing a release agent.
Another object of the present invention is to provide a developer using the electrophotographic carrier, an image forming method, and a container for the developer.

The invention 請 Motomeko 1, in the carrier having a coating layer containing at least a binder resin and particles, the binder resin contains a resin obtained by crosslinking an acrylic resin and an amino resin, the particles of alumina And the following chemical formula No. A carrier for electrophotography, which is surface-treated with a compound represented by 1 .
C ₁₂ H ₂₅ NHCH (CH ₂ COOC ₁₂ H ₂₅ ) CH ₂ COOH. 1
The invention according to claim 2 is a carrier having a coating film containing at least a binder resin and particles, wherein the binder resin includes a resin obtained by cross-linking an acrylic resin and an amino resin,
The particles are alumina and have the following chemical formula No. An electrophotographic carrier comprising the compound represented by 1 .
C ₁₂ H ₂₅ NHCH (CH ₂ COOC ₁₂ H ₂₅ ) CH ₂ COOH. 1
According to the invention of claim 3, the particles further include the chemical formula no. The carrier for electrophotography according to claim 2, wherein the carrier is surface-treated with a compound represented by 1 .
The invention according to claim 4 is the carrier for electrophotography according to any one of claims 1 to 3, wherein the specific resistance of the particles is 1012 Ω · cm or more.
The invention of claim 5 provides the chemical formula No. The proportion of the compound represented by 1 is an electrophotographic career according to any one of claims 1 to 4, characterized in that 1 to 50 wt%.
The invention according to claim 6 is the electrophotographic carrier according to any one of claims 1 to 5, wherein the content of the particles is 40 to 95 mass% of the coating film composition component.
A seventh aspect of the present invention is the electrophotographic carrier according to any one of the first to sixth aspects, wherein the coating film has a thickness of 0.05 to 1.00 μm.
The invention according to claim 8 is the carrier for electrophotography according to claim 1 or 3, wherein the particles are subjected to a wet surface treatment.
The invention of claim 9 is the electrophotographic carrier according to any one of claims 1 to 8, wherein the binder resin has a Tg of 20 to 100 ° C.
A tenth aspect of the present invention is an electrophotographic developer comprising: a toner comprising at least a binder resin and a pigment; and the electrophotographic carrier according to any one of the first to ninth aspects.
An eleventh aspect of the invention is the electrophotographic developer according to the tenth aspect, wherein the toner contains a release agent.
A twelfth aspect of the present invention is an image forming method using the electrophotographic developer according to the tenth or eleventh aspect.
A thirteenth aspect of the present invention is a multicolor image forming method using the electrophotographic developer according to the tenth or eleventh aspect.
The invention of claim 14 is a developer accommodating container, wherein the electrophotographic developer of claim 10 or 11 is housed.

  According to the present invention, there is provided an electrophotographic carrier that is highly durable even when combined with a toner containing a release agent. The present invention also provides a developer, an image forming method, and a container for the developer using the electrophotographic carrier.

Hereinafter, the present invention will be described in more detail.
As a result of continuing investigations to improve the problems of the prior art, that is, the durability of the carrier, the present inventors have determined that the particle diameter D and the carrier having a coating film having at least a binder resin and particles The coating film thickness h is 1 <[D / h] <10 (for example, both units are μm), and the particles are surface-treated with the amino acid compound, so that the improvement effect is remarkable. I found out. This is the first embodiment of the present invention.

The effect of this improvement is that the particles are more convex than the coating film, so that the developer is frictionally charged, and the contact with a strong impact on the binder resin is caused by friction with toner or friction between carriers. This is because it can be relaxed. As a result, it is possible to prevent toner spent on the carrier and to prevent the binder resin film from being charged. However, the convex part, that is, the part of the particle protruding from the coat film relaxes the contact accompanied by a strong impact on the binder resin, so that the particle itself is always easily detached from the coat film. Therefore, in order to realize further high durability, it is necessary to suppress such detachment of the particles. According to the study by the present inventors, the particles are surface-treated with an amino acid-based compound. Desorption can be suppressed. This is because the detachment of the particles is suppressed by increasing the adhesion between the particles and the binder resin in the coating film. In addition, in the case of a toner containing a release agent, the release agent is mainly used to accelerate the detachment of the particles in the coat film, but the adhesion between the particles and the binder resin in the coat film is accelerated. As a result, the same effect as in the case of toner containing no release agent is obtained.
In addition, when the particles are surface-treated with an amino acid compound, hydrophobicity is obtained and environmental stability is also increased. Furthermore, surface treatment of the particles with an amino acid compound improves fluidity, reduces friction between the toner and the carrier and between the carriers, reduces toner fatigue and spent toner components, and particles from the carrier. A decrease in the number of withdrawals became possible.

  Further, according to the present inventors, there is a specific range for realizing the high durability of the carrier with respect to the ratio [D / h] of the particle diameter D in the coat film of the carrier to the film thickness h of the coat film. It became clear that there was. When [D / h] is 1 or less, the particles are buried in the binder resin, which is not preferable because the effect is remarkably lowered. In the conventional technique, when [D / h] is 5 or more, the contact area between the particles and the binder resin is small, so that a sufficient binding force cannot be obtained and the particles are easily detached. However, in the present invention, since the particles are surface-treated with an amino acid compound, the adhesion to the binder resin is increased, and even when this ratio is 5 or more and less than 10, the particles are not detached from the coating film. Thus, it was possible to obtain a coating film convex portion.

  As the surface treatment method of the particles used in the present invention, any conventionally known method may be used as long as the treatment agent can be surface-treated on the particles, and specifically, wet and dry methods can be mentioned. In the wet method, particles and an amino acid compound are dispersed in a solvent, and the amino acid compound is adhered to the particle surface. As a dispersion method, general dispersion means such as a ball mill and a sand mill can be used. Next, after this dispersion solution is dried by a dryer to remove the solvent, heat treatment is further performed to firmly attach the amino acid compound to the particle surface. If necessary, the particles after the surface treatment may be pulverized.

  On the other hand, in the dry treatment, the amino acid compound is adhered to the particle surface by mixing and kneading the amino acid compound and the particles without using a solvent. Thereafter, the surface treatment is completed by performing heat treatment, pulverization treatment, and the like similar to the wet treatment as necessary. Further, a catalyst for promoting the reaction may be added to the treatment liquid. Moreover, although the ratio of the amino acid compound to the particle depends on the particle size of the particle, the molecular structure of the amino acid compound, and the like, in any of the above methods, it is preferably 1 to 50% by mass, more preferably 3 to 40% by mass. %.

  In addition, the same effect can be obtained when the amino acid compound is not only surface-treated on the particles but also contained in the coat film. This is the second aspect of the present invention. Furthermore, the effect is more remarkably manifested by the combined use of these methods in which these amino acid compounds are surface-treated on the particles and contained in the coat film. Even when the amino acid compound is contained in the coat film (including the combination of the above methods), the ratio of the amino acid compound to the particles is preferably 1 to 50% by mass, more preferably 3 to 40% by mass.

The amino acid compound used in the present invention is an organic compound containing both an amino group (—NH ₂ ) and a carboxyl group (—COOH) in its molecular structure, or C ₁₂ H ₂₅ NHCH (CH ₂ COOC ₁₂ H ₂₅ an organic compound represented ^{_{-) CH 2 COOH, C 11}} H 23 CONH (CH 2) 4 CH (NH 3 +) COO. As for carbon number of an amino acid type compound, 5-100 are preferable. More preferably, it is 10-40. A plurality of amino groups may be present in one molecule. The molecular weight of the amino acid compound is preferably 300 to 100,000.

  Here, the compounds shown below are exemplified as preferred amino acid compounds, but are not limited to these compounds.

No. 1 C ₁₂ H ₂₅ NHCH (CH ₂ COOC ₁₂ H ₂₅ ) CH ₂ COOH
No. 2 C ₁₁ H ₂₃ CONH (CH ₂ ) ₄ CH (NH ₃ ⁺ ) COO ⁻

In the present invention, it is effective that the specific resistance of the particles is 10 ¹² Ω · cm or more in order to suppress a decrease in charge amount during storage of the developer over a long period of time. This is because even if the particles are exposed to the surface while having contact with the core material, the leakage of electric charges can be suppressed, so that stable chargeability can be obtained. On the other hand, when the specific resistance of the particles is less than 10 ¹² Ω · cm, since charge leakage cannot be suppressed, it is not preferable because stable chargeability cannot be obtained. Examples of such particles include alumina, silica, and titanium, and among these, alumina, silica, and a mixture thereof are preferable. The particle diameter D of the particles is, for example, 0.010 to 3 μm, preferably 0.01 to 0.5 μm.

  Further, as mentioned in the background art section, the present invention has the following differences from the carrier containing conductive particles larger than the coating resin film thickness described in Patent Document 10 in the coating film. is there. That is, the present invention is characterized in that the particles in the coating film are not used as a resistance adjusting material as in the prior art, but are used as a protective material for the coating film resin and a surface shape adjusting material. Further, an amino acid compound is essential for suppressing the detachment of the particles.

  Furthermore, when the particles are alumina, for example, the effect is remarkable when the content is in the range of 40 to 95% by mass, preferably 70 to 90% by mass, of the coating film composition component. Further, when the particles are silica, the effect is remarkable when the content is in the range of 40 to 95% by mass, preferably 70 to 90% by mass of the coating film composition component. When the particle content is less than 40% by mass, since the proportion of the particles is smaller than the proportion of the binder resin on the surface of the carrier particles, the contact with a strong impact on the binder resin is alleviated. Since the effect is small, sufficient durability cannot be obtained, which is not preferable. On the other hand, if the amount is more than 95% by mass, the proportion of particles is too much compared to the proportion of the binder resin on the carrier surface, and therefore the proportion of the binder resin that is the charge generation location becomes insufficient. Insufficient charging ability. In addition, since the amount of particles is too much compared to the amount of binder resin, the ability to hold particles by the binder resin becomes insufficient, and the particles are easily detached, which is not preferable because sufficient durability cannot be obtained.

  In addition, the carrier in which conductive particles larger than the coating resin film thickness described in Patent Document 10 described above are contained in the coating film is also different from the present invention in the content range of the particles. In this prior art, “0.01 to 50 mass% of the coating resin”, that is, “0.01 to 33.33 mass% of the coating film composition component” in terms of the content calculation method of the present invention. In this case, the durability is improved as compared with the conventional case, but as described above, since the proportion of the particles is smaller than the proportion of the binder resin on the surface of the carrier particles, there is a strong impact on the binder resin. The effect of relaxing the contact is small, and sufficient durability cannot be obtained.

  According to the present invention, the binder resin is not particularly limited, but it is very preferable that the binder resin contains a resin obtained by cross-linking an acrylic resin and an amino resin and / or a silicone resin. As this amino resin, a conventionally known amino resin can be used. However, the use of guanamine or melamine remarkably improves the charge imparting ability. Further, as the silicone resin, conventionally known silicone resins can be used. Further, the thickness of the binder resin constituting the coat film is preferably 0.05 to 1.00 μm.

  Besides the above resins, resins generally used as carrier coating resins 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 Resins, urethane / urea resins, polyethylene resins, Teflon (registered trademark) resins and other thermoplastic resins and thermosetting resins, and mixtures thereof, as well as copolymers, block polymers, and graft weights of these resins Examples include, but are not limited to, coalescence and polymer blends.

  In the present invention, those having a Tg of 20 to 100 ° C., preferably 25 to 80 ° C., may be used. When the Tg of the resin is within this range, the resin has an appropriate elasticity, and the friction between the toner and the carrier or the friction between the carriers in the stirring for frictionally charging the developer causes the resin to be bonded to the binder resin. In the case of contact with a strong impact, the impact can be absorbed and the coating film can be maintained without being damaged. Moreover, when Tg is less than 20 ° C., the binder resin is blocked even at room temperature, which is not preferable because the storage stability is poor and it cannot be used practically. On the other hand, when Tg exceeds 100 ° C., the binder resin is too hard and brittle, so that the impact cannot be absorbed, and the binder resin is scraped from the brittleness and particles cannot be retained. , Because it is easy to desorb.

  As the carrier core material, a carrier core having an average particle size of 20 μm is used at least in order to prevent carrier adhesion (scattering) to the electrostatic latent image carrier, and image quality such as prevention of generation of carrier streaks, etc. From the standpoint of preventing the decrease, the one having a maximum of 100 μm is used. Specific materials that are known as two-component carriers for electrophotography, such as ferrite, magnetite, iron, nickel, etc., may be appropriately selected and used in accordance with the use and purpose of use of the carrier.

  In the carrier of the present invention, carbon black or an acidic catalyst can be used alone or in combination as a charge and resistance control agent. Any carbon black that is commonly used for carriers or toners can be used. As the acidic catalyst, one having a catalytic action can be used. For example, it has a reactive group such as a fully alkylated type, a methylol group type, an imino group type, and a methylol / imino group type, but is not limited thereto.

  Although the carrier of the present invention can be provided as a two-component developer constituted with toner, the toner constituting the developer consists of a binder resin and a pigment, and even a black toner is used in a multicolor image forming method. It doesn't matter. Further, the two-component developer may be provided in a container so that it can be easily replaced by a specific image forming apparatus.

  Hereinafter, an image forming method using the carrier of the present invention will be described 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. In particular, FIG. 1 shows a developing unit 1 mounted in the main body of the image forming apparatus and a developer filled with a developer using the electrophotographic carrier of the present invention supplied to the developing unit 1 in the configuration of the image forming apparatus. 2 is a partial cross-sectional view showing a developer container 2 and a developer flow means 3 that connects both of them. FIG.

  In FIG. 1, a developing unit 1 contains a liquid two-component developer D obtained by mixing a toner and a carrier using the electrophotographic carrier of the present invention. The developing housing 4 includes first and second agitating screws 5 and 6 for agitating and mixing the developer D, and a developing roller 7. The developing roller 7 serves as a latent image carrier photoreceptor 8. Opposed to each other. The photoreceptor 8 is driven to rotate in the direction indicated by the arrow, and an electrostatic latent image is formed on the surface thereof. Reference numeral 26 in FIG. 1 denotes a cap that is fitted onto the connecting member 24 via the filter 25 or not. Around the photosensitive member 8, other known units such as a charging unit, an exposure unit, a transfer unit, a charge removing unit, and a cleaning unit (not shown) are arranged.

  As the first and second agitating screws 5 and 6 rotate, the developer D in the developing housing 4 is agitated, and the toner is triboelectrically charged to opposite polarities by the carrier. The developer D is supplied to the peripheral surface of the developing roller 7 that is rotationally driven in the direction of the arrow, and the supplied developer is carried on the peripheral surface of the developing roller 7, and the rotation direction of the developing roller 7 is rotated. It is conveyed to. Next, the amount of the developer D thus transported is regulated by the doctor blade 9, and the regulated developer D is conveyed to the development area between the photoreceptor 8 and the developing roller 7, where the developer D in the developer The toner is electrostatically transferred to the electrostatic latent image on the surface of the photoreceptor, and the electrostatic latent image is visualized as a toner image.

Next, although an Example and a comparative example are given and this invention is demonstrated further more concretely, this invention is not limited to these. The part used below refers to part by mass.
In Examples shown below, Examples 3 and 5 are test examples corresponding to Reference Examples.

<Toner Production Example 1>
Black toner 1
Water 1200 parts Phthalocyanine green water-containing cake (solid content 30%) 200 parts Carbon black (MA60, manufactured by Mitsubishi Chemical Corporation) 540 parts is thoroughly stirred with a flasher. here,
After adding 1200 parts of epoxy resin (Mn: 3500) and kneading at 150 ° C. for 30 minutes,
After adding 1000 parts of xylene, the mixture was further kneaded for 1 hour, water and xylene were removed, rolled and cooled, and pulverized with a pulverizer to obtain a master batch pigment.

Epoxy resin (Mn: 3500) 100 parts Master batch 5 parts Zinc salicylate derivative (Bontron E84, Orient Chemical) 4 parts The above materials were mixed in a mixer and then melt-kneaded in a two-roll mill, and the kneaded product was rolled and cooled. Thereafter, pulverization and classification were performed to obtain a toner having a mass average particle diameter of 7.8 μm. Further, an additive was added and mixed with a Henschel mixer to obtain a black toner 1.

<Toner Production Example 2>
Black toner 2
Except for adding 5 parts of Carnauba wax to Toner Production Example 1, all were produced in the same manner as Toner Production Example 1.

<Surface treatment particle production example 1>
Alumina particles 1
No. above. 1 part of an amino acid compound 35, 100 parts of alumina (average particle size 0.3 μm, specific resistance 10 ¹⁴ Ω · cm) particles, and 250 parts of acetone were dispersed in a ball mill for 40 hours, followed by filtering and drying the solution. The alumina particles 1 surface-treated with the amino acid compound were obtained by heat treatment at 150 ° C. for 2 hours.

<Surface treatment particle production example 2>
Alumina particles 2
No. above. 2 parts of an amino acid compound (2), 100 parts of alumina (average particle size 0.3 μm, specific resistance 10 ¹⁴ Ω · cm) particles and 250 parts of acetone were dispersed in a ball mill for 40 hours, followed by filtration and drying of the solution. The alumina particles 2 surface-treated with the amino acid compound were obtained by heat treatment at 150 ° C. for 2 hours.

<Example 1>
<Carrier Production Example 1> Carrier 1
Acrylic resin solution (solid content 50% by mass) 56.0 parts Guanamin solution (solid content 77% by mass) 15.6 parts Alumina particles 1 160.0 parts Toluene 900 parts Butyl cellosolve 900 parts The above materials are dispersed with a homomixer for 10 minutes. A coating film forming solution was prepared. Sintered coater (Okada Seiko Co., Ltd.) using sintered ferrite powder (F-300 manufactured by Powdertech Co., Ltd .: average particle size 50 μm) as the core material, and coating film forming solution having a film thickness of 0.15 μm on the core material surface. Applied and dried. The obtained carrier was baked by standing in an electric furnace at 150 ° C. for 1 hour. After cooling, the ferrite powder bulk was pulverized using a sieve having an opening of 100 μm, and carrier 1 was obtained. In the measurement of the binder resin film thickness, since the coat film covering the carrier surface can be observed by observing the cross section of the carrier with a transmission electron microscope, the average value of the film thickness was taken as the film thickness.

  The carrier 1 and the black toner 1 obtained as described above were mixed so that the toner concentration was 5% to obtain a developer. The type of carrier and toner used, the presence / absence of surface treatment for the carrier, the presence / absence of an amino acid compound in the coating film, the particle diameter of the particle, the film thickness of the coating film and the value of [D / h] are described in Example 2 below. The results are shown in Table 1 below together with -8 and Comparative Examples 1-2. This developer and black toner 1 were set on a commercially available digital full-color copying machine (imageColor 2800 manufactured by Ricoh Co., Ltd.), and 600,000 running evaluations (continuous copying evaluation) were performed. Table 2 shows the results of determining the charge reduction amount and resistance reduction amount of the carrier after the running.

  The amount of decrease in the charge amount referred to here is a general blow-off method (TB-200 manufactured by Toshiba Chemical Co., Ltd.) obtained by mixing a frictionally charged sample mixed at a ratio of 5% by mass of toner with respect to 95% by mass of the initial carrier. The amount Q1-Q2 obtained by subtracting the amount of charge Q2 measured by the same method as described above from the amount of charge Q1 measured in this manner, and the carrier from which the toner in the developer after running was removed by the blow-off device. The target value is 7.0 μc / g or less. Further, since the cause of the decrease in the charge amount is the toner spent on the carrier surface, the decrease in the charge amount can be suppressed by reducing the toner spent.

  The amount of resistance decrease is a value obtained by converting an initial carrier into a resistance measurement parallel electrode: an electrode having a gap of 2 mm, applying a DC 200V, and measuring a resistance value after 30 seconds with a high resist meter into a volume resistivity. This is the amount R1-R2 obtained by subtracting the value R2 measured by the same method as the resistance measurement method, from the carrier from which the toner in the developer after running was removed by the blow-off device from R1. The value is 2.0 Log (Ω · cm) or less. In addition, since the cause of the resistance reduction is scraping of the binder resin film of the carrier, the resistance reduction amount can be suppressed by reducing the film scraping.

<Example 2>
In Example 2, a developer was obtained and evaluated in the same manner as in Example 1 except that the black toner 1 of Example 1 was changed to black toner 2. The constitution of the developer is shown in Table 1, and the evaluation results are shown in Table 2.

<Example 3>
<Carrier Production Example 2> Carrier 2
All were produced in the same manner as in Carrier Production Example 1 except that the alumina particles 1 in Carrier Production Example 1 were changed to alumina particles 2.
In Example 3, a developer was obtained and evaluated in the same manner as in Example 2 except that the carrier 1 of Example 2 was changed to the carrier 2. The constitution of the developer is shown in Table 1, and the evaluation results are shown in Table 2.

<Example 4>
<Carrier Production Example 3> Carrier 3
Acrylic resin solution (solid content 50% by mass) 56.0 parts Guanamine solution (solid content 77% by mass) 15.6 parts Alumina particles (average particle size 0.3 μm, specific resistance 10 ¹⁴ Ω · cm) 160.0 parts No. 1 Amino acid compound 14.5 parts Toluene 900 parts Butyl cellosolve 900 parts All were produced in the same manner as in Carrier Production Example 1 except that the prescription was changed.
In Example 4, a developer was obtained and evaluated in the same manner as in Example 2 except that the carrier 1 of Example 2 was changed to the carrier 3. The constitution of the developer is shown in Table 1, and the evaluation results are shown in Table 2.

<Example 5>
<Carrier Production Example 4> Carrier 4
The amino acid compound of Carrier Production Example 3 was prepared as described in No. 1 above. All were produced in the same manner as in Carrier Production Example 3 except that the amino acid compound was changed to 2.
In Example 5, a developer was obtained and evaluated in the same manner as in Example 2 except that the carrier 1 of Example 2 was changed to the carrier 4. The constitution of the developer is shown in Table 1, and the evaluation results are shown in Table 2.

<Example 6>
<Carrier Production Example 5> Carrier 5
All the alumina particles of Carrier Production Example 3 were produced in the same manner as Carrier Production Example 3 except that the alumina particles were changed to alumina particles 1.
In Example 6, a developer was obtained and evaluated in the same manner as in Example 2 except that the carrier 1 of Example 2 was changed to the carrier 5. The constitution of the developer is shown in Table 1, and the evaluation results are shown in Table 2.

<Comparative Example 1>
<Carrier Production Example 6> Carrier 6
Acrylic resin solution (solid content 50% by mass) 56.0 parts Guanamine solution (solid content 77% by mass) 15.6 parts Alumina particles (average particle size 0.3 μm, specific resistance 10 ¹⁴ Ω · cm) 160.0 parts Toluene 900 parts Butyl cellosolve 900 parts All were produced in the same manner as in Carrier Production Example 1 except that the above prescription was changed.
In Comparative Example 1, a developer was obtained and evaluated in the same manner as in Example 1 except that the carrier 1 of Example 1 was changed to the carrier 6. The constitution of the developer is shown in Table 1, and the evaluation results are shown in Table 2.

<Comparative example 2>
In Comparative Example 2, a developer was obtained and evaluated in the same manner as in Example 2 except that the carrier 1 of Example 2 was changed to the carrier 6. The constitution of the developer is shown in Table 1, and the evaluation results are shown in Table 2.

  From the above Tables 1 and 2, the carrier of the present invention was more than twice as effective as the conventional carrier. Further, in the combination with the toner containing the release agent, the effect of 6 times or more in the durability was obtained as compared with the conventional result.

  According to the present invention, there is provided an electrophotographic carrier that is highly durable even when combined with a toner containing a release agent. The present invention also provides a developer, an image forming method, and a container for the developer using the electrophotographic carrier.

It is a figure which shows an example of the image forming apparatus which mounts the container filled with the developer using the carrier for electrophotography of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Developing part 2 Developer storage container 3 Developer delivery means 4 Developing housing 5, 6 Stir screw 7 Developing roller 8 Photoconductor 9 Doctor blade 24 Connection member 25 Filter 26 Cap D Developer

Claims (14)

In a carrier having a coating film containing at least a binder resin and particles,
The binder resin includes a resin obtained by cross-linking an acrylic resin and an amino resin,
The particles are alumina and have the following chemical formula No. A carrier for electrophotography, which is surface-treated with a compound represented by 1 .
C ₁₂ H ₂₅ NHCH (CH ₂ COOC ₁₂ H ₂₅ ) CH ₂ COOH. 1 In a carrier having a coating film containing at least a binder resin and particles,
The binder resin includes a resin obtained by cross-linking an acrylic resin and an amino resin,
The particles are alumina;
The coating film has the following chemical formula No. An electrophotographic carrier comprising the compound represented by 1 .
C ₁₂ H ₂₅ NHCH (CH ₂ COOC ₁₂ H ₂₅ ) CH ₂ COOH. 1 Further, the particles have the chemical formula no. The electrophotographic carrier according to claim 2, which is surface-treated with a compound represented by 1 . The electrophotographic carrier according to claim 1, wherein a specific resistance of the particles is 10 ¹² Ω · cm or more.   The chemical formula No. The electrophotographic carrier according to claim 1, wherein the ratio of the compound represented by 1 is 1 to 50% by mass.   The electrophotographic carrier according to claim 1, wherein the content of the particles is 40 to 95% by mass of the coating film composition component.   The electrophotographic carrier according to claim 1, wherein the coating film has a thickness of 0.05 to 1.00 μm.   The electrophotographic carrier according to claim 1, wherein the particles are surface-treated by a wet process.   The electrophotographic carrier according to claim 1, wherein the binder resin has a Tg of 20 to 100 ° C.   An electrophotographic developer comprising: a toner comprising at least a binder resin and a pigment; and the electrophotographic carrier according to claim 1.   The electrophotographic developer according to claim 10, wherein the toner contains a release agent.   An image forming method using the electrophotographic developer according to claim 10.   A multicolor image forming method using the electrophotographic developer according to claim 10. 12. A developer storage container in which the electrophotographic developer according to claim 10 or 11 is stored.

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