JP2007102159A - Electrophotographic carrier, developer, developer container, process cartridge, image forming method, and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrophotographic carrier, having superior durability and resistance to carrier adherence on a solid image portion in a continuous long-term operation, producing a dense image over a long period of time, causing no color contamination and having proper chargeability control property, and to provide a developer, a developer container, a process cartridge, an image forming method and an image forming apparatus that use the electrophotographic carrier. <P>SOLUTION: The electrophotographic carrier comprises a core and a cover layer overlying the core, and is characterized in that the cover layer comprises at least a binder resin, first particles and second particles; the particle size D1 (μm) of the first particles and the average thickness h (μm) of a resin portion in the cover layer satisfy the relation 1<(D1/h)<10; the particle diameter D2 (μm) of the second particles and the average thickness h (μm) of the resin portion in the cover layer satisfy the relation 0.001<(D2/h)<1; and the volume resistivity of the second particles is not greater than 1.0×10<SP>12</SP>Ωcm. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electrophotographic carrier used for electrostatic image development in electrophotography, electrostatic recording, electrostatic printing, and the like, and a developer, a developer-containing container, a process cartridge, and an image formation using the electrophotographic carrier The present invention relates to a method and an image forming apparatus.

In electrophotographic image formation, a latent image is formed on an image carrier such as a photoconductive substance by electrostatic charge, and a charged toner is attached to the electrostatic latent image to form a visible image (toner image). ) Is transferred to a recording medium such as paper and fixed, and an image is output.
In recent years, the technology of copiers and printers using an electrophotographic system has been rapidly expanding from monochrome to full color, and the full color market tends to expand. Color image formation by full-color electrophotography generally reproduces all colors by laminating three color toners of three primary colors, yellow, magenta, and cyan, or four color toners with black added to them. It is. Therefore, in order to obtain a clear full color image with excellent color reproducibility, it is necessary to reduce the light scattering by smoothing the surface of the fixed toner image to some extent. For this reason, the image gloss of a conventional full-color copying machine or the like is often 10-50% medium gloss or 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. This method has high thermal efficiency and high-speed fixing, and is advantageous in that it can give gloss and transparency to the color toner. However, the surface of the heat-fixing member is brought into contact with the molten toner under pressure. Since the toner image is peeled off afterwards, there is a problem that 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 this offset phenomenon, a method is generally adopted in which the fixing roller surface is formed of silicone rubber or fluororesin with excellent releasability, and then a release oil such as silicone oil is applied to the fixing roller surface. Has been. This method is extremely effective in preventing toner offset. However, the above method requires a device for supplying release oil, and the fixing device is large and is not suitable for downsizing the machine. For this reason, in the case of a monochrome toner, the viscosity of the toner when melted is adjusted by adjusting the molecular weight distribution of the binder resin so that the melted toner does not break internally, and a release agent such as wax is further included in the toner. Therefore, there is a tendency to employ a method in which the release oil is not applied to the fixing roller (oilless), or the amount of oil applied is very small.

  On the other hand, color toners, like monochrome toners, tend to be oil-less for the purpose of miniaturizing machines and simplifying their configurations. However, as described above, with color toners, it is necessary to smooth the surface of the fixed image in order to improve color reproducibility. It is easy to offset, and it becomes more difficult to make the fixing device oil-less and to apply a small amount. In addition, when a release agent is contained in the toner, the adhesion of the toner increases and the transferability to the transfer paper decreases. Furthermore, there is a problem in that durability is lowered by the release agent in the toner contaminating a frictional charging member such as a carrier and reducing the charging property.

  Regarding the carrier, prevention of filming of toner components on the carrier surface, formation of a uniform carrier surface, prevention of surface oxidation, prevention of moisture sensitivity deterioration, extension of developer life, prevention of carrier adhesion to the surface of the photoreceptor, For the purpose of protecting the photoreceptor from scratches and abrasion by the carrier, controlling the charge polarity, or adjusting the charge amount, a coating layer containing a resin material is provided on the core material. For example, those coated with a specific resin material (see Patent Document 1), and various additives added to the coating layer (Patent Document 2, Patent Document 3, Patent Document 4, Patent Document 5, Patent Document 6) , Patent Document 7 and Patent Document 8), an additive adhered to the carrier surface (see Patent Document 9), and conductive particles larger than the coating layer thickness included in the coating layer (Patent Document 10). Etc.) have been proposed. Patent Document 11 proposes to use a carrier coating material mainly composed of a benzoguanamine-n-butyl alcohol-formaldehyde copolymer. Patent Document 12 proposes to use a cross-linked product of melamine resin and acrylic resin as a carrier coating material.

  However, these prior arts still have insufficient durability and carrier adhesion suppression. In particular, the problem is the spent on the carrier surface of the toner, destabilization of the charge amount associated therewith, and a decrease in the coating layer due to film removal of the coating resin and a corresponding decrease in resistance. In particular, a good image can be obtained in the initial stage, but there is a problem that the image quality of the copied image is lowered as the number of copies increases.

Recently, in response to a demand from customers for faster and more beautiful, the speed of the electrophotographic apparatus is remarkably increased. Along with this, the stress received by the developer has also increased dramatically, and it has become impossible to obtain a sufficient life even for carriers that have been long-lived. Carbon black is frequently used as a carrier resistance adjusting agent. However, there is a concern about color contamination due to migration of carbon black into a color image due to film scraping and carbon black detachment.
Various countermeasures have been proposed as countermeasures. For example, a carrier has been proposed in which a conductive agent (carbon black) is present on the surface of the core material and no conductive material is present in the coating layer (see Patent Document 13). Further, a carrier is proposed in which the coating layer has a carbon black concentration gradient in the thickness direction, the carbon black concentration decreases toward the surface of the coating layer, and there is no carbon black on the surface of the coating layer. (See Patent Document 14). Further, there has been proposed a two-layer coated carrier in which an inner coating layer containing conductive carbon is provided on the surface of core material particles, and a surface coating layer containing a white conductive material is further provided thereon ( (See Patent Document 15). However, these proposals cannot cope with the recent increase in stress, and color stains become a problem.

  As a drastic measure against such color stains, it is clear that eliminating carbon black that causes color stains is most effective. However, when carbon black is simply removed, the carbon black has a property that its electric resistance is low, so that the carrier resistance increases and at the same time the charging characteristics also increase. Generally, when controlling the charge of a carrier, control by a coating material is a conventional means. However, the level of charge due to the presence or absence of carbon black is significant, and there are many side effects caused by changing the material. At present, changes other than black have not been implemented.

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 Japanese Unexamined Patent Publication No. 7-140723 JP-A-8-179570 JP-A-8-286429

  An object of the present invention is to solve various problems in the prior art and achieve the following objects. In other words, the present invention is excellent in durability, does not cause carrier adhesion on a solid image portion during running, can form a fine image over a long period of time, does not cause color stains, and has good charge controllability. An object of the present invention is to provide an electrophotographic carrier, and a developer, a developer-containing container, a process cartridge, an image forming method, and an image forming apparatus using the electrophotographic carrier.

Means for solving the problems are as follows. That is,
<1> A core material and a coating layer that covers the core material, the coating layer including at least a binder resin, first particles, and second particles,
The particle diameter D1 (μm) of the first particles and the average thickness h (μm) of the resin portion in the coating layer satisfy the following formula, 1 <(D1 / h) <10,
The particle diameter D2 (μm) of the second particles and the average thickness h (μm) of the resin portion in the coating layer satisfy the following expression: 0.001 <(D2 / h) <1, and the second An electrophotographic carrier characterized in that the volume resistivity of particles is 1.0 × 10 ¹² Ω · cm or less.
<2> The electrophotographic carrier according to <1>, wherein an average thickness T (μm) from the core material surface to the coating layer surface is 0.1 ≦ T ≦ 3.0.
<3> The electrophotographic carrier according to any one of <1> to <2>, wherein the volume resistivity of the first particles is 1.0 × 10 ¹² Ω · cm or more.
<4> The electrophotographic carrier according to any one of <1> to <3>, wherein the first particles are alumina particles.
<5> The electrophotographic carrier according to any one of <1> to <4>, wherein the content of the first particles in the coating layer is 10 to 80% by mass.
<6> The above-mentioned second particles are at least one particle selected from titanium oxide, zinc oxide, tin oxide, surface-treated titanium oxide, surface-treated zinc oxide, and surface-treated tin oxide. <1> to the electrophotographic carrier according to any one of <5>.
<7> The electrophotographic carrier according to any one of <1> to <6>, wherein the content of the second particles in the coating layer is 2 to 50% by mass.
<8> The electrophotographic carrier according to any one of <1> to <7>, wherein the binder resin is any one of a reaction product of an acrylic resin and an amino resin, and a silicone resin.
<9> A developer comprising the electrophotographic carrier according to any one of <1> to <8> and a toner.
<10> The developer according to <9>, wherein the toner includes at least a binder resin and a colorant.
<11> A developer-containing container filled with the developer according to any one of <9> to <10>.
<12> The electrostatic latent image carrier and the electrostatic latent image formed on the electrostatic latent image carrier are developed using the developer according to any one of <9> to <10> and visible A process cartridge having at least developing means for forming an image.
<13> An electrostatic latent image carrier, electrostatic latent image forming means for forming an electrostatic latent image on the electrostatic latent image carrier, and the electrostatic latent image of <9> to <10> Developing means for developing a visible image by developing using any of the developers, a transferring means for transferring the visible image to a recording medium, and a fixing means for fixing the transferred image transferred to the recording medium And an image forming apparatus characterized by comprising:
<14> An electrostatic latent image forming step of forming an electrostatic latent image on the electrostatic latent image carrier, and the developer according to any one of <9> to <10> Development step for forming a visible image by developing, a transfer step for transferring the visible image to a recording medium, and a fixing step for fixing the transferred image transferred to the recording medium. An image forming method.

The electrophotographic carrier of the present invention comprises a core and a coating layer covering the core, and the coating layer includes at least a binder resin, first particles, and second particles,
The particle diameter D1 (μm) of the first particles and the average thickness h (μm) of the resin portion in the coating layer satisfy the following formula, 1 <(D1 / h) <10,
The particle diameter D2 (μm) of the second particles and the average thickness h (μm) of the resin portion in the coating layer satisfy the following expression: 0.001 <(D2 / h) <1, and the second The volume resistivity of the particles is 1.0 × 10 ¹² Ω · cm or less.
In the electrophotographic carrier of the present invention, since the coating layer includes two particles each having a different function, the durability is excellent, and carrier adhesion does not occur in the solid image portion during running, and a fine image is obtained. Can be formed over a long period of time, and image formation with good charge controllability without color smearing can be performed.

  The developer of the present invention includes the electrophotographic carrier of the present invention and a toner. For this reason, when image formation is performed by electrophotography using the developer, carrier adhesion does not occur in the solid image portion during running time, and a fine image can be formed over a long period of time. It is possible to obtain a high image quality that can form a stable image with good reproducibility that does not occur and has good charge controllability.

  The developer-containing container of the present invention is obtained by housing the developer of the present invention in a container. For this reason, when an image is formed by electrophotography using the developer contained in the developer-containing container, carrier adhesion does not occur in the solid image portion during the running time, and a fine image is long. It can be formed over a period of time, and high image quality with good charge controllability without color stains can be obtained.

  The process cartridge of the present invention comprises an electrostatic latent image carrier and developing means for developing a latent image formed on the electrostatic latent image carrier using the developer of the present invention to form a visible image. At least. The process cartridge is attachable to and detachable from the image forming apparatus, is excellent in convenience, and uses the developer of the present invention. As a result, carrier adhesion does not occur in the solid image portion during running, and the texture is not lost. A fine image can be formed over a long period of time, and high image quality with good charge controllability without color stains can be obtained.

  The image forming apparatus of the present invention includes at least an electrostatic latent image carrier, an electrostatic latent image forming unit, a developing unit, a transfer unit, and a fixing unit. In the image forming apparatus, the electrostatic latent image forming unit forms an electrostatic latent image on the electrostatic latent image carrier. The developing means develops the electrostatic latent image using the developer of the present invention to form a visible image. The transfer means transfers the visible image to a recording medium. The fixing unit fixes the transferred image transferred to the recording medium. As a result, carrier adhesion does not occur in the solid image portion during running, a fine image can be formed over a long period of time, and a high-quality electrophotographic image free from color stains can be formed.

  The image forming method of the present invention includes at least an electrostatic latent image forming step, a developing step, a transfer step, and a fixing step. In the image forming method, an electrostatic latent image is formed on the electrostatic latent image carrier in the electrostatic latent image forming step. In the developing step, the electrostatic latent image is developed using the developer of the present invention to form a visible image. In the transfer step, the visible image is transferred to a recording medium. In the fixing step, the transferred image transferred to the recording medium is fixed. As a result, carrier adhesion does not occur in the solid image portion during running, a fine image can be formed over a long period of time, and a high-quality electrophotographic image free from color stains can be formed.

  According to the present invention, conventional problems can be solved, durability is excellent, carrier adhesion does not occur on a solid image portion during running time, a fine image can be formed over a long period of time, and color stains An electrophotographic carrier with good charge controllability, a developer, a developer-containing container, a process cartridge, an image forming method, and an image forming apparatus using the electrophotographic carrier can be provided.

(Electrophotographic carrier)
The electrophotographic carrier of the present invention comprises a core material and a coating layer covering the core material, and further comprises other layers as required.

<Coating layer>
The coating layer includes at least a binder resin, first particles, and second particles, and further includes other components as necessary.

-1st particle-
The particle diameter D1 (μm) of the first particles and the average thickness h (μm) of the resin portion in the coating layer satisfy the following formula, 1 <(D1 / h) <10, and 1 <(D1 / h ) <5 is more preferable. When the first particles satisfy the relationship of the above formula, the first particles become more convex than the resin portion in the coating layer. Therefore, the friction with the toner or the carrier by the stirring for tribocharging the developer. The friction between each other can alleviate the contact with a strong impact on the binder resin, and can suppress film scraping of the binder resin, which is the place where the charge is generated. In addition, since there are many particles that are more convex than the coating layer on the carrier surface, a cleaning effect that efficiently scrapes off the spent component of the toner adhering to the carrier surface due to frictional contact between the carriers occurs, preventing toner spent can do.
When the (D / h) is 1 or less, the first particles are buried in the binder resin, and thus the effect may be significantly reduced. When the (D / h) is 10 or more, the first particles are bound to the first particles. Since the contact area with the resin is small, sufficient binding force cannot be obtained, and the first particles may be easily detached.

The volume average particle diameter D1 of the first particles is preferably 0.05 to 3 μm, and more preferably 0.05 to 1 μm.
The average thickness h (μm) of the resin portion in the coating layer is preferably 0.04 to 2 μm, and more preferably 0.04 to 1 μm.
The average thickness h of the resin portion in the coating layer is the thickness of the film existing in the direction perpendicular to the core material surface, and the average thickness of the resin portion excluding the particle portion in the thickness from the core material surface to the coating layer surface. Indicates.
As shown in FIG. 7, the thickness of the resin part in the coating layer is as follows. The thickness ha of the resin part existing between the core surface and the particles, the thickness hb of the resin part existing between the particles, There is a thickness hc of the resin part and a thickness hd of the resin part on the core material.
The average thickness h of the resin portion in the coating layer can be measured by observing the cross section of the carrier using, for example, a transmission electron microscope (TEM). Specifically, the thickness of the resin portion in the coating layer (the thickness ha of the resin portion existing between the core material surface and the particles, the thickness of the resin portion existing between the particles, at intervals of 0.2 μm along the carrier surface. hb, the thickness hc of the resin part on the particles, and the thickness hd of the resin part on the core material) were measured using a transmission electron microscope (TEM), and 50 measurement values were obtained. Let the averaged value be the average thickness h of the resin part in a coating layer. The value of the average thickness h of the resin part in the coating layer is a value obtained by dividing the sum of the measured values by the number of the measured values. The number of measured values is the thickness ha of the resin part existing between the surface of the core material and the particles, the thickness hb of the resin part existing between the particles, the thickness hc of the resin part on the particles, and on the core material The thickness hd of the resin part is counted as one. For example, at the measurement point A in FIG. 7, since the hb and the hc exist, the number of measurement values at the measurement point A is two.
Of the 50 measured values, the last measured location is when a plurality of measured values (for example, ha and hc) are obtained as measured values of the thickness of the resin portion in the coating layer. Is a value obtained by dividing the total value of the measured values by the value of “49+ (number of measured values at the last measured point)”, which is the number of measured values, and the value of the average thickness h of the resin portion in the coating layer To do.

The average thickness T (μm) from the core material surface to the coating layer surface is 0.1 ≦ T ≦ 3.0, and preferably 0.1 ≦ T ≦ 2.0. When the average thickness T from the surface of the core material to the surface of the coating layer is less than 0.1 μm, the total thickness of the film is too thin, so that the core material is likely to be exposed over time, and the durability of the carrier may be reduced. is there. When the average thickness from the core material to the surface of the coating layer exceeds 3.0 μm, the film thickness formed on the core material becomes too thick, so that the magnetization of the carrier tends to decrease and carrier adhesion may occur.
As shown in FIG. 7, the thickness from the core material surface to the coating layer surface represents a thickness different from the thickness h of the resin portion in the coating layer, and the thickness from the core material surface to the coating layer surface. Show. When the particle size of the particles is larger than the thickness of the resin portion in the coating layer, the thickness from the core material surface to the coating layer surface indicates the value of the particle size of the particles.
The average thickness T from the surface of the core material to the surface of the coating layer is observed, for example, using a transmission electron microscope (TEM), and the thickness of the surface from the surface of the core material to the surface of the coating layer is measured along the carrier surface. This is a value obtained by measuring 50 points at intervals of 0.2 μm and averaging the obtained measurement values.

The volume resistivity of the first particles is preferably 1.0 × 10 ¹² Ω · cm or more, and more preferably 1.0 × 10 ^{12 to} 1.0 × 10 ¹⁶ Ω · cm. If the volume resistivity is less than 1.0 × 10 ¹² Ω · cm, the first particles are larger than the coating layer, and the core material and the coating layer surface may be connected by one first particle. In some cases, the carrier adheres to the solid part.

Here, the volume resistivity of the first particles can be measured, for example, as follows. A sample is put in a cylindrical vinyl chloride tube having an inner diameter of 1 inch, and the upper and lower sides are sandwiched between electrodes. A pressure of 15 kg / cm ² is applied to these electrodes with a press machine for 1 minute. Subsequently, measurement with an LCR meter is performed in this pressurized state to obtain resistance (r). The volume resistivity can be obtained by calculating the obtained resistance value according to the following Equation 1.

<Formula 1>
Volume resistivity (Ω · cm) = (2.54 / 2) ² × (π / H × r)
However, in Formula 1, H represents the thickness of the sample. r represents a resistance value.

Examples of the first particles include alumina particles, silica particles, and the like. Among these, the alumina particles have good compatibility with the binder resin used for the carrier coating material, and have good dispersibility and adhesiveness. It is not only excellent in terms of surface, but also very hard, so it is particularly preferable because it is difficult to wear and crack against stress in the developing machine, and it can exert a protective effect on the coating layer and a scraped scraping effect over a long period of time. .
As the alumina particles, alumina particles having a particle size of 5 μm or less are preferable, and any particles that have not been surface-treated or those that have been surface-treated such as a hydrophobic treatment can be used.
As the silica, those used for toner and those other than that can be used, and those not surface-treated and those surface-treated such as hydrophobic treatment can be used.

The content of the first particles in the coating layer is preferably 10 to 80% by mass, and more preferably 20 to 60% by mass. When the content is less than 10% by mass, since the proportion of the first particles occupies less than the proportion of the binder resin on the surface of the carrier particles, the effect of reducing contact with a strong impact on the binder resin Is small, sufficient durability may not be obtained. On the other hand, if it exceeds 80% by mass, the proportion of the first particles occupies too much compared to the proportion of the binder resin on the carrier surface. May not be able to demonstrate proper charging ability. Furthermore, since the amount of the first particles is too much compared to the amount of the binder resin, the ability to hold the first particles by the binder resin becomes insufficient, the first particles are likely to be detached, and the amount of fluctuation such as the charge amount and resistance is increased. In some cases, sufficient durability may not be obtained.
Here, the content of the first particles in the coating layer is expressed by the following mathematical formula 2.
<Formula 2>
Content of first particles (% by mass) = [content of first particles / total amount of materials contained in coating layer (first particles + second particles + binder resin + other components)] × 100

-Second particle-
The particle diameter D2 (μm) of the second particles and the average thickness h (μm) of the resin portion in the coating layer satisfy the following formula: 0.001 <(D2 / h) <1, 0.01 < It is more preferable to satisfy (D2 / h) <0.5. Further, the volume resistivity of the second particles is not more than 1.0 × 10 ¹² Ω · cm, preferably not more than 1.0 × ¹⁰ 10 Ω · cm, more preferably at most 1.0 × 10 ⁸ Ω · cm . The volume resistivity of the second particles can be measured in the same manner as the first particles.
Since the particle diameter of the second particles is smaller than the average thickness h of the resin portion in the coating layer and the volume specific resistance is as low as 1.0 × 10 ¹² Ω · cm or less, the second particles having low resistance are core materials. Since it can exist in the coating layer without causing a point connecting the surface and the surface of the coating layer with one grain, the charging characteristics of the coating layer can be lowered on average without causing a significant decrease in carrier resistance. In addition, a coating layer having no local low-resistance portion can be formed.
When (D2 / h) is 1 or more, the second particles are larger than the average thickness h of the resin portion in the coating layer, and therefore, the core material surface and the carrier surface are connected by one second particle having low resistance. As a result, a portion having low resistance locally occurs in the coating layer, and carrier adhesion may occur in the solid image portion. When the (D2 / h) is 0.001 or less, the particle diameter of the second particles with respect to the average thickness of the resin portion in the coating layer becomes too small, so that it is difficult to exert the effect of the charge control function. In addition, when a large amount is added in order to exert the charge control effect, the ratio of the second particles to the binder resin is excessively increased, and the holding ability of the second particles may be insufficient.
The particle size D2 of the second particles is preferably 0.005 to 1 μm, and more preferably 0.01 to 0.2 μm.

  The second particles are preferably at least one particle selected from titanium oxide, zinc oxide, tin oxide, surface-treated titanium oxide, surface-treated zinc oxide, and surface-treated tin oxide. . These particles can sufficiently exhibit the charge control effect, have good compatibility with the resin used for the carrier coating material, and are excellent in dispersibility and adhesiveness. Whatever the particle matrix, the surface is treated with, for example, a conductive treatment, a hydrophobic treatment, etc. If the particle size and specific resistance are in the above ranges, good effects can be obtained for the same reason as described above. Can be demonstrated.

The content of the second particles in the coating layer is preferably 2 to 50% by mass, and more preferably 2 to 30% by mass. Basically, the charge control effect increases as the content of the second particles increases. However, when the content exceeds 50% by mass, the dispersion state in the coating layer deteriorates, and the aggregation of the second particles increases, resulting in a substantial increase. The same effect as that of the particle having a particle diameter may be exerted, the carrier resistance may be lowered, and the carrier may adhere to the solid image portion. On the other hand, if it is less than 2% by mass, the content of the second particles is small, and thus the effect may not be sufficiently exhibited.
Here, the content of the second particles in the coating layer is expressed by Equation 3 below.
<Formula 3>
Content of second particles (% by mass) = [content of second particles ÷ total amount of material contained in coating layer (first particle + second particle + binder resin + other components)] × 100

-Binder resin-
Suitable examples of the binder resin include a reaction product of an acrylic resin and an amino resin, and a silicone resin.

There is no restriction | limiting in particular as a reaction material of the said acrylic resin and an amino resin, Although it can select suitably according to the objective, The crosslinking reaction material of an acrylic resin and an amino resin is suitable.
There is no restriction | limiting in particular as said acrylic resin, Although it can select suitably according to the objective from all the acrylic resins, 20-100 degreeC is preferable among these, and glass transition temperature (Tg) is preferable 25-25. 80 ° C. is more preferable. When the glass transition temperature (Tg) of the acrylic resin is within this range, the acrylic resin has appropriate elasticity, and friction between the toner and the carrier or between carriers in the stirring for frictionally charging the developer. With this friction, when a contact with a strong impact is applied to the binder resin, the impact can be absorbed and the coating layer can be maintained without being damaged.
When the glass transition temperature (Tg) is less than 20 ° C., the binder resin blocks even at room temperature, so that the storage stability is poor and it may not be practically used. On the other hand, when the glass transition temperature (Tg) exceeds 100 ° C., the binder resin is too hard and brittle, and cannot absorb the impact, and the binder resin is scraped from the brittleness and retains the particles. May not be able to be performed and may be easily detached.
The amino resin is not particularly limited, and can be appropriately selected from conventionally known amino resins according to the purpose. For example, by using guanamine or melamine, the charge imparting ability can be increased. It can be significantly improved.

The silicone resin is not particularly limited and can be appropriately selected according to the purpose from generally known silicone resins. For example, a straight silicone resin consisting only of an organosilosan bond, an alkyd resin, Examples include silicone resins modified with polyester resins, epoxy resins, acrylic resins, urethane resins, and the like.
Commercially available products can be used as the silicone resin. Examples of the straight silicone resin include KR271, KR255, and KR152 manufactured by Shin-Etsu Chemical Co., Ltd .; SR2400, SR2406, and SR2410 manufactured by Toray Dow Corning Silicone. .
Examples of the modified silicone resin include KR206 (alkyd modified), KR5208 (acrylic modified), ES1001N (epoxy modified), KR305 (urethane modified) manufactured by Shin-Etsu Chemical Co., Ltd .; SR2115 (manufactured by Toray Dow Corning Silicone). Epoxy modified), SR2110 (alkyd modified), and the like.
It is possible to use the silicone resin alone, but it is also possible to simultaneously use a crosslinking reaction component, a charge amount adjusting component, and the like.

  As the binder resin, in addition to the above resins, those generally used as carrier coating resins can be used as necessary. For example, polyvinyl resins, polystyrene resins, halogenated olefins can be used. Resin, polyester resin, polycarbonate resin, polyethylene resin, polyvinyl fluoride resin, polyvinylidene fluoride resin, polytrifluoroethylene resin, polyhexafluoropropylene resin, copolymer of vinylidene fluoride and vinyl fluoride, And fluoroterpolymers such as terpolymers of tetrafluoroethylene, vinylidene fluoride and non-fluorinated monomers. These may be used individually by 1 type and may use 2 or more types together.

For example, the coating layer is prepared by dissolving the first particles, second particles, binder resin, and the like in a solvent to prepare a coating solution, and then uniformly applying the coating solution on the surface of the core material by a known coating method. After applying and drying, it can be formed by baking. Examples of the application method include an immersion method, a spray method, and a brush coating method.
There is no restriction | limiting in particular as said solvent, Although it can select suitably according to the objective, For example, toluene, xylene, methyl ethyl ketone, methyl isobutyl ketone, cersol butyl acetate, etc. are mentioned.
The baking is not particularly limited, and may be an external heating method or an internal heating method. For example, a stationary electric furnace, a fluid electric furnace, a rotary electric furnace, a burner furnace, etc. The method of using, the method of using a microwave, etc. are mentioned.

<Core>
The core material preferably has a volume average particle size of 20 μm or more from the viewpoint of prevention of carrier adhesion (scattering) to the electrostatic latent image carrier, and is intended to prevent deterioration of image quality such as prevention of occurrence of carrier streaks. To 100 μm or less is preferable, and in particular, 20 to 50 μm is more preferable for high image quality in recent years.
There is no restriction | limiting in particular as said core material, According to the objective, it can select suitably from what is known as a two-component carrier for electrophotography, For example, a ferrite, magnetite, iron, nickel is mentioned suitably. In addition, in consideration of the environmental aspects that have advanced remarkably in recent years, if ferrite, for example, Mn ferrite, Mn-Mg ferrite, Mn-Mg-Sr ferrite, etc. should be used instead of conventional copper-zinc ferrite. Is preferred.
There is no restriction | limiting in particular in the volume average particle diameter of the said core material, According to the objective, it can select suitably, For example, 10-200 micrometers is preferable and 10-60 micrometers is more preferable.

(Developer)
The developer of the present invention comprises the electrophotographic carrier of the present invention and a toner.
The toner includes at least a binder resin and a colorant, and further includes a release agent, a charge control agent, and other components as necessary.
The mixing ratio of toner and carrier in the developer is 1 to 10.0 parts by mass of toner with respect to 100 parts by mass of carrier.

  The method for producing the toner is not particularly limited and may be appropriately selected depending on the intended purpose. It is a pulverization method, a suspension in which an oil phase is emulsified, suspended or aggregated in an aqueous medium to form toner base particles. There are a polymerization method, an emulsion polymerization method, a polymer suspension method, and the like. Among these, a pulverization method is particularly preferable.

-Binder resin-
The binder resin is not particularly limited and may be appropriately selected from known ones according to the purpose. For example, a homopolymer of styrene such as polystyrene, poly-p-styrene, polyvinyltoluene, or a substituted product thereof. Styrene-p-chlorostyrene copolymer, styrene-propylene copolymer, styrene-vinyltoluene copolymer, styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-methacrylic acid copolymer Polymerization unit, styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, styrene-α-chloromethyl methacrylate copolymer, styrene-acrylonitrile copolymer Polymer, styrene-vinyl methyl ether copolymer, styrene-vinyl methyl ketone Copolymer, styrene-butadiene copolymer, styrene-isopropyl copolymer, styrene-copolymer such as styrene-maleic ester copolymer, polythyme methacrylate resin, polybutyl methacrylate resin, polyvinyl chloride resin , Polyvinyl acetate resin, polyethylene resin, polyester resin, polyurethane resin, epoxy resin, polyvinyl butyral resin, polyacrylic acid resin, rosin resin, modified rosin resin, terpene resin, phenol resin, aliphatic or aromatic hydrocarbon resin, aromatic A group petroleum resin can be used alone or in combination.

-Colorant-
The colorant is not particularly limited and may be appropriately selected from known dyes and pigments according to the purpose. For example, carbon black, nigrosine dye, iron black, naphthol yellow S, Hansa yellow (10G, 5G, G), cadmium yellow, yellow iron oxide, ocher, yellow lead, titanium yellow, polyazo yellow, oil yellow, Hansa yellow (GR, A, RN, R), pigment yellow L, benzidine yellow (G, GR), Permanent Yellow (NCG), Vulcan Fast Yellow (5G, R), Tartrazine Lake, Quinoline Yellow Lake, Anthrazan Yellow BGL, Isoindolinone Yellow, Bengala, Lead Red, Lead Red, Cadmium Red, Cad Muum Mercury Red, Antimon Zhu, Permanent Red 4R, PA Red, Faise Red, Parachlor Ortho Nitroaniline Red, Resol Fast Scarlet G, Brilliant Fast Scarlet, Brilliant Carmine BS, Permanent Red (F2R, F4R, FRL, FRLL, F4RH), Fast Scarlet VD, Belkan Fast Rubin B, Brilliant Scarlet G, Risor Rubin GX, Permanent Red F5R, Brilliant Carmine 6B, Pigment Scarlet 3B, Bordeaux 5B, Toluidine Maroon, Permanent Bordeaux F2K, Helio Bordeaux BL, Bordeaux 10B, Bon Maroon Light, Bon Maroon Medium, Eosin Lake, Rhodamine Lake B, Rhodamine Lake Y, Alizarin Lake, Thioindigo Red B, Thioindigo Maroon, Oh Lured, Quinacridone Red, Pyrazolone Red, Polyazo Red, Chrome Vermilion, Benzidine Orange, Perinone Orange, Oil Orange, Cobalt Blue, Cerulean Blue, Alkaline Blue Lake, Peacock Blue Lake, Victoria Blue Lake, Metal Free Phthalocyanine Blue, Phthalocyanine Blue, Fast Sky Blue, Indanthrene Blue (RS, BC), Indigo, Ultramarine Blue, Bitumen, Anthraquinone Blue, Fast Violet B, Methyl Violet Lake, Cobalt Purple, Manganese Purple, Dioxane Violet, Anthraquinone Violet, Chrome Green, Zinc Green, Oxidation Chrome, Pyridian, Emerald Green, Pigment Green B, Naphthol Green B, Green Gold, Ash Examples include green lake, malachite green lake, phthalocyanine green, anthraquinone green, titanium oxide, zinc white, and lithobon.
These may be used alone or in combination of two or more.
The content of the colorant in the toner is preferably 1 to 15% by mass, and more preferably 3 to 10% by mass.

  The colorant may be used as a master batch combined with a resin. The resin is not particularly limited and may be appropriately selected from known ones according to the purpose. For example, styrene or a substituted polymer thereof, styrene copolymer, polymethyl methacrylate resin, polybutyl Methacrylate resin, polyvinyl chloride resin, polyvinyl acetate resin, polyethylene resin, polypropylene resin, polyester resin, epoxy resin, epoxy polyol resin, polyurethane, polyamide, polyvinyl butyral, polyacrylic acid resin, rosin, modified rosin, terpene resin, fat Aromatic hydrocarbon resin, alicyclic hydrocarbon resin, aromatic petroleum resin, chlorinated paraffin, paraffin and the like. These may be used individually by 1 type and may use 2 or more types together.

-Release agent-
There is no restriction | limiting in particular as said mold release agent, According to the objective, it can select suitably from well-known things, For example, waxes etc. are mentioned suitably.
Examples of the waxes include carbonyl group-containing waxes, polyolefin waxes, and long-chain hydrocarbons. These may be used alone or in combination of two or more. Among these, a carbonyl group-containing wax is preferable.
Examples of the carbonyl group-containing wax include polyalkanoic acid esters, polyalkanol esters, polyalkanoic acid amides, polyalkylamides, dialkyl ketones, and the like. Examples of the polyalkanoic acid ester include carnauba wax, montan wax, trimethylolpropane tribehenate, pentaerythritol tetrabehenate, pentaerythritol diacetate dibehenate, glycerin tribehenate, and 1,18-octadecane. Examples thereof include diol distearate. Examples of the polyalkanol ester include tristearyl trimellitic acid and distearyl maleate. Examples of the polyalkanoic acid amide include dibehenyl amide. Examples of the polyalkylamide include trimellitic acid tristearylamide. Examples of the dialkyl ketone include distearyl ketone. Of these carbonyl group-containing waxes, polyalkanoic acid esters are particularly preferred.
Examples of the polyolefin wax include polyethylene wax and polypropylene wax.
Examples of the long chain hydrocarbon include paraffin wax and sazol wax.

There is no restriction | limiting in particular as melting | fusing point of the said mold release agent, Although it can select suitably according to the objective, 40-160 degreeC is preferable, 50-120 degreeC is more preferable, 60-90 degreeC is especially preferable.
When the melting point is less than 40 ° C., the wax may adversely affect the heat-resistant storage stability, and when it exceeds 160 ° C., cold offset may easily occur during fixing at a low temperature.
The melt viscosity of the release agent is preferably 5 to 1,000 cps, more preferably 10 to 100 cps, as a measured value at a temperature 20 ° C. higher than the melting point of the wax.
If the melt viscosity is less than 5 cps, the releasability may be lowered, and if it exceeds 1,000 cps, the effect of improving hot offset resistance and low-temperature fixability may not be obtained.

There is no restriction | limiting in particular as content in the said toner of the said mold release agent, Although it can select suitably according to the objective, 1-40 mass% is preferable and 3-30 mass% is more preferable.
When the content exceeds 40% by mass, the fluidity of the toner may be deteriorated.

-Charge control agent-
The charge control agent is not particularly limited, and a positive or negative charge control agent can be appropriately selected and used depending on whether the charge charged on the photoconductor is positive or negative.
As the negative charge control agent, for example, a resin or compound having an electron donating functional group, an azo dye, a metal complex of an organic acid, or the like can be used. Specifically, Bontron (product numbers: S-31, S-32, S-34, S-36, S-37, S-39, S-40, S-44, E-81, E-82, E -84, E-86, E-88, A, 1-A, 2-A, 3-A) (above, manufactured by Orient Chemical Industry Co., Ltd.)), Kaya Charge (part numbers: N-1, N-2), Kaya Set Black (Part No .: T-2, 004) (Nippon Kayaku Co., Ltd.), Eisenspiron Black (T-37, T-77, T-95, TRH, TNS-2) FCA-1001-N, FCA-1001-NB, FCA-1001-NZ (manufactured by Fujikura Kasei Co., Ltd.), and the like.
Examples of the positive charge control agent include basic compounds such as nigrosine dyes, cationic compounds such as quaternary ammonium salts, and metal salts of higher fatty acids. Specifically, Bontron (part numbers: N-01, N-02, N-03, N-04, N-05, N-07, N-09, N-10, N-11, N-13, P -51, P-52, AFP-B) (above, manufactured by Orient Chemical Co., Ltd.), TP-302, TP-415, TP-4040 (above, manufactured by Hodogaya Chemical Co., Ltd.), Copy Blue PR, Copy Charge ( Product number: PX-VP-435, NX-VP-434) (manufactured by Hoechst), FCA (Product number: 201, 201-B-1, 201-B-2, 201-B-3, 201-PB, 201-PZ, 301) (above, manufactured by Fujikura Kasei Co., Ltd.), PLZ (product numbers: 1001, 2001, 6001, 7001) (above, manufactured by Shikoku Kasei Kogyo Co., Ltd.), and the like.
These may be used alone or in combination of two or more.

  The addition amount of the charge control agent is determined by the toner production method including the type of the binder resin and the dispersion method, and is not uniquely limited. However, with respect to 100 parts by mass of the binder resin. 0.1-10 mass parts is preferable and 0.2-5 mass parts is more preferable. When the addition amount exceeds 10 parts by mass, the chargeability of the toner is too large, the effect of the charge control agent is reduced, the electrostatic attraction with the developing roller is increased, the developer fluidity is reduced, and the image density is increased. If the amount is less than 0.1 parts by mass, the charge rise and charge amount are insufficient, and the toner image may be easily affected.

  In addition to the binder resin, the release agent, the colorant, and the charge control agent, the toner material includes inorganic fine particles, a fluidity improver, a cleaning property improver, a magnetic material, a metal soap, and the like as necessary. Can be added.

As the inorganic fine particles, for example, silica, titania, alumina, cerium oxide, strontium titanate, calcium carbonate, magnesium carbonate, calcium phosphate, etc. can be used. It is more preferable to use fine particles or titanium oxide subjected to a specific surface treatment.
Examples of the silica fine particles include, for example, Aerosil (product numbers: 130, 200 V, 200 CF, 300, 300 CF, 380, OX50, TT600, MOX80, MOX170, COK84, RX200, RY200, R972, R974, R976, R805, R811, R812, T805, R202, VT222, RX170, RXC, RA200, RA200H, RA200HS, RM50, RY200, REA200) (above, manufactured by Nippon Aerosil Co., Ltd.), HDK (product numbers: H20, H2000, H3004, H2000 / 4, H2050EP, H2015EP, H3050EP) , KHD50), HVK2150 (above, manufactured by Wacker Chemical Co., Ltd.), Cabogil (Part No .: L-90, LM-130, LM-150, M-5, PTG, MS-55, H-5) HS-5, EH-5, LM-150D, M-7D, MS-75D, TS-720, TS-610, TS-530) (or, can be used Cabot Corp.).
The addition amount of the inorganic fine particles is preferably 0.1 to 5.0 parts by mass, more preferably 0.8 to 3.2 parts by mass with respect to 100 parts by mass of the toner base particles.

The pulverization method is, for example, a method of obtaining the toner base particles by pulverizing, classifying, or the like, the melted and kneaded toner material.
In the melt kneading, the toner materials are mixed, and the mixture is charged into a melt kneader and melt kneaded. As the melt kneader, for example, a uniaxial or biaxial continuous kneader or a batch kneader using a roll mill can be used. For example, KTK type twin screw extruder manufactured by Kobe Steel, TEM type extruder manufactured by Toshiba Machine Co., Ltd., twin screw extruder manufactured by Casey Kay, PCM type twin screw extruder manufactured by Ikegai Iron Works Co., Ltd. Preferably used. This melt-kneading is preferably performed under appropriate conditions so as not to cause the molecular chains of the binder resin to be broken. Specifically, the melt kneading temperature is performed with reference to the softening point of the binder resin. If the temperature is higher than the softening point, cutting is severe, and if the temperature is too low, dispersion may not proceed.

  In the pulverization, the kneaded product obtained by the kneading is pulverized. In this pulverization, it is preferable that the kneaded material is first coarsely pulverized and then finely pulverized. At this time, a method of pulverizing by colliding with a collision plate in a jet stream, pulverizing particles by colliding with each other in a jet stream, or pulverizing with a narrow gap between a mechanically rotating rotor and a stator is preferably used.

In the classification, the pulverized product obtained by the pulverization is classified and adjusted to particles having a predetermined particle diameter. The classification can be performed by removing the fine particle portion by, for example, a cyclone, a decanter, centrifugation, or the like.
After the pulverization and classification are completed, the pulverized product is classified into an air stream by centrifugal force or the like to produce toner base particles having a predetermined particle size.

  Further, in order to improve the fluidity, storage stability, developability and transferability of the toner, inorganic fine particles such as hydrophobic silica fine powder may be further added to and mixed with the toner base particles produced as described above. For mixing the additives, a general powder mixer is used, but it is preferable to equip a jacket or the like to adjust the internal temperature. In order to change the load history applied to the additive, the additive may be added midway or gradually. In this case, you may change the rotation speed, rolling speed, time, temperature, etc. of a mixer. Alternatively, a strong load may be applied first, then a relatively weak load, or vice versa. Examples of the mixing equipment that can be used include a V-type mixer, a rocking mixer, a Ladige mixer, a Nauter mixer, and a Henschel mixer. Next, the toner is obtained by passing through a sieve of 250 mesh or more to remove coarse particles and aggregated particles.

  The coloration of the toner is not particularly limited and may be appropriately selected according to the purpose, and may be at least one selected from black toner, cyan toner, magenta toner, and yellow toner. Can be obtained by appropriately selecting the type of the colorant, and is preferably a color toner.

(Container with developer)
The developer-containing container of the present invention is obtained by housing the developer of the present invention in a container.
There is no restriction | limiting in particular as said container, It can select suitably from well-known things, For example, what has a developer container main body and a cap etc. are mentioned suitably.
The size, shape, structure, material and the like of the developer container body are not particularly limited and can be appropriately selected according to the purpose. For example, the shape is preferably cylindrical. A spiral irregularity is formed on the peripheral surface, and the toner as the contents can be transferred to the discharge port side by rotating, and part or all of the spiral part has a bellows function, etc. Is particularly preferred.
The material of the developer container main body is not particularly limited, and those having good dimensional accuracy are preferable. For example, a resin is preferable, and among them, for example, polyester resin, polyethylene resin, polypropylene resin, polystyrene resin, Preferable examples include vinyl chloride resin, polyacrylic acid, polycarbonate resin, ABS resin, polyacetal resin, and the like.
The developer-containing container of the present invention is easy to store, transport, etc., has excellent handleability, and is preferably used for replenishing the developer by being detachably attached to the process cartridge and image forming apparatus of the present invention described later. can do.

  Here, FIG. 1 is a schematic view showing an example of an image forming apparatus equipped with the developer-containing container of the present invention filled with the developer of the present invention. The developing unit 1 mounted in the image forming apparatus main body and the developer-filled container 2 filled with the developer of the present invention replenished to the developing unit 1 are connected by the developer flow means 3 and the connecting member 124. Has been. In FIG. 1, 4 is a developing housing, 5 is a stirring screw, 6 is a stirring screw, 7 is a developing roller, 8 is a photoreceptor, and 9 is a doctor blade.

(Process cartridge)
The process cartridge of the present invention develops an electrostatic latent image carrier carrying an electrostatic latent image and the electrostatic latent image carried on the electrostatic latent image carrier using a developer to form a visible image. At least a developing unit for forming the image forming apparatus, and other units such as a charging unit, a developing unit, a transfer unit, a cleaning unit, and a discharging unit, which are appropriately selected as necessary.
The developing means includes at least a developer container that contains the developer of the present invention, and a developer carrier that carries and conveys the developer contained in the developer container. Furthermore, a layer thickness regulating member for regulating the layer thickness of the developer to be carried may be provided.
The process cartridge of the present invention can be detachably mounted on various electrophotographic apparatuses, facsimiles, and printers, and is preferably detachably mounted on the image forming apparatus of the present invention described later.

Here, for example, as shown in FIG. 2, the process cartridge includes a photosensitive member 101, and includes a charging unit 102, a developing unit 104, a cleaning unit 107, and a transfer unit 108, and other members as necessary. It has. In FIG. 2, reference numeral 103 denotes exposure by the exposure means.
As the photoreceptor 101, the same one as an image forming apparatus described later can be used.
An arbitrary charging member is used as the charging unit 102.
As the exposure means, a light source capable of writing with high resolution is used.

  The image forming apparatus of the present invention is constructed by integrally combining the electrostatic latent image carrier and the components such as a developing device and a cleaning device as a process cartridge, and this unit can be attached to and detached from the apparatus main body. It may be configured. Further, at least one of a charger, an image exposure device, a developing device, a transfer or separation device, and a cleaning device is integrally supported together with an electrostatic latent image carrier to form a process cartridge, and is detachably attached to the apparatus main body. One unit may be detachable using guide means such as a rail of the apparatus main body.

(Image forming apparatus and image forming method)
The image forming apparatus of the present invention includes at least an electrostatic latent image carrier, an electrostatic latent image forming unit, a developing unit, a transfer unit, and a fixing unit, and further appropriately selected as necessary. It has other means, for example, static elimination means, cleaning means, recycling means, control means and the like.
The image forming method of the present invention includes at least an electrostatic latent image forming step, a developing step, a transfer step, and a fixing step, and other steps appropriately selected as necessary, for example, a static elimination step, a cleaning step, Includes recycling and control processes.

  The image forming method of the present invention can be preferably carried out by the image forming apparatus of the present invention, the electrostatic latent image forming step can be performed by the electrostatic latent image forming means, and the developing step is the developing The transfer step can be performed by the transfer unit, the fixing step can be performed by the fixing unit, and the other steps can be performed by the other unit.

-Electrostatic latent image forming step and electrostatic latent image forming means-
The electrostatic latent image forming step is a step of forming an electrostatic latent image on the electrostatic latent image carrier.
The material, shape, structure, size, etc. of the electrostatic latent image carrier (photosensitive member) are not particularly limited, and can be appropriately selected from known ones. Examples of the material include inorganic photoreceptors such as amorphous silicon and selenium, and organic photoreceptors such as polysilane and phthalopolymethine. Among these, amorphous silicon and the like are preferable in terms of long life.

The formation of the electrostatic latent image can be performed, for example, by uniformly charging the surface of the electrostatic latent image carrier and then performing imagewise exposure, and is performed by the electrostatic latent image forming unit. be able to.
The electrostatic latent image forming means includes, for example, at least a charger that uniformly charges the surface of the electrostatic latent image carrier and an exposure device that exposes the surface of the electrostatic latent image carrier imagewise. Prepare.

The charging can be performed, for example, by applying a voltage to the surface of the electrostatic latent image carrier using the charger.
The charger is not particularly limited and may be appropriately selected depending on the purpose. For example, a known contact charging device including a conductive or semiconductive roll, brush, film, rubber blade, etc. And non-contact chargers using corona discharge such as corotrons and corotrons.

The exposure can be performed, for example, by exposing the surface of the latent electrostatic image bearing member imagewise using the exposure device.
The exposure device is not particularly limited as long as it can expose the surface of the latent electrostatic image bearing member charged by the charger so as to form an image to be formed, and is appropriately selected according to the purpose. For example, various exposure devices such as a copying optical system, a rod lens array system, a laser optical system, and a liquid crystal shutter optical system can be used.
In the present invention, a back light system in which imagewise exposure is performed from the back side of the electrostatic latent image carrier may be employed.

-Development process and development means-
The developing step is a step of developing the electrostatic latent image using the developer of the present invention to form a visible image.
The visible image can be formed, for example, by developing the electrostatic latent image using the developer of the present invention, and can be performed by the developing unit.
The developing means is not particularly limited as long as it can be developed using, for example, the developer of the present invention, and can be appropriately selected from known ones. For example, the developer of the present invention is accommodated. And a developer having at least a developer capable of applying the developer to the electrostatic latent image in a contact or non-contact manner, and a developer equipped with the developer-containing container of the present invention is more preferable. .

  The developing unit may be a dry developing type, a wet developing type, a single color developing unit, or a multi-color developing unit. Well, for example, a developer having a stirrer for charging the developer by frictional stirring and a rotatable magnet roller is preferable.

  In the developing device, for example, the toner and the carrier are mixed and agitated, and the toner is charged by friction at that time, and held on the surface of the rotating magnet roller in a raised state to form a magnetic brush. . Since the magnet roller is disposed in the vicinity of the electrostatic latent image carrier (photoconductor), a part of the toner constituting the magnetic brush formed on the surface of the magnet roller is electrically attracted. It moves to the surface of the electrostatic latent image carrier (photoconductor) by force. As a result, the electrostatic latent image is developed by the developer, and a visible image is formed by the developer on the surface of the electrostatic latent image carrier (photoconductor).

-Transfer process and transfer means-
The transfer step is a step of transferring the visible image onto a recording medium. After the primary transfer of the visible image onto the intermediate transfer member using an intermediate transfer member, the visible image is transferred onto the recording medium. A secondary transfer mode is preferable, and a primary transfer step of forming a composite transfer image by transferring a visible image onto an intermediate transfer body using two or more colors, preferably a full color developer, as the developer, A mode including a secondary transfer step of transferring the composite transfer image onto a recording medium is more preferable.
The transfer can be performed, for example, by charging the latent electrostatic image bearing member (photoconductor) of the visible image using a transfer charger, and can be performed by the transfer unit. The transfer means includes a primary transfer means for transferring a visible image onto an intermediate transfer member to form a composite transfer image, and a secondary transfer means for transferring the composite transfer image onto a recording medium. Embodiments are preferred.
The intermediate transfer member is not particularly limited and may be appropriately selected from known transfer members according to the purpose. For example, a transfer belt and the like are preferable.

The transfer means (the primary transfer means and the secondary transfer means) is a transfer for peeling and charging the visible image formed on the electrostatic latent image carrier (photoconductor) to the recording medium side. It is preferable to have at least a vessel. There may be one transfer means or two or more transfer means.
Examples of the transfer device include a corona transfer device using corona discharge, a transfer belt, a transfer roller, a pressure transfer roller, and an adhesive transfer device.
The recording medium is typically plain paper, but is not particularly limited as long as it can transfer an unfixed image after development, and can be appropriately selected according to the purpose. PET for OHP A base or the like can also be used.

The fixing step is a step of fixing the visible image transferred to the recording medium using a fixing device, and may be performed each time the developer of each color is transferred to the recording medium, or the developer of each color. On the other hand, it may be carried out at the same time in a state where these are laminated.
There is no restriction | limiting in particular as said fixing device, Although it can select suitably according to the objective, A well-known heating-pressing means is suitable. Examples of the heating and pressing means include a combination of a heating roller and a pressure roller, a combination of a heating roller, a pressure roller, and an endless belt.
The heating in the heating and pressing means is usually preferably 80 to 200 ° C.
In the present invention, for example, a known optical fixing device may be used together with or in place of the fixing step and the fixing unit depending on the purpose.

The neutralization step is a step of performing neutralization by applying a neutralization bias to the electrostatic latent image carrier, and can be suitably performed by a neutralization unit.
The neutralization means is not particularly limited, and may be appropriately selected from known neutralizers as long as it can apply a neutralization bias to the electrostatic latent image carrier. Preferably mentioned.

The cleaning step is a step of removing the developer remaining on the electrostatic latent image carrier and can be suitably performed by a cleaning unit.
The cleaning means is not particularly limited as long as it can remove the electrophotographic toner remaining on the electrostatic latent image carrier, and can be appropriately selected from known cleaners. Suitable examples include brush cleaners, electrostatic brush cleaners, magnetic roller cleaners, blade cleaners, brush cleaners, web cleaners, and the like.

The recycling step is a step of recycling the electrophotographic toner removed by the cleaning step to the developing unit, and can be suitably performed by the recycling unit.
There is no restriction | limiting in particular as said recycling means, A well-known conveyance means etc. are mentioned.

The control step is a step of controlling each of the steps, and can be suitably performed by a control unit.
The control means is not particularly limited as long as the movement of each means can be controlled, and can be appropriately selected according to the purpose. Examples thereof include devices such as a sequencer and a computer.

  One mode for carrying out the image forming method of the present invention by the image forming apparatus of the present invention will be described with reference to FIG. An image forming apparatus 100 shown in FIG. 3 includes a photosensitive drum 10 (hereinafter referred to as “photosensitive member 10”) as the electrostatic latent image carrier, a charging roller 20 as the charging unit, and an exposure as the exposure unit. The apparatus 30 includes a developing device 40 as the developing means, an intermediate transfer member 50, a cleaning device 60 as the cleaning means having a cleaning blade, and a static elimination lamp 70 as the static elimination means.

  The intermediate transfer member 50 is an endless belt, and is designed to be movable in the direction of an arrow by three rollers 51 that are arranged inside and stretched. Part of the three rollers 51 also functions as a transfer bias roller that can apply a predetermined transfer bias (primary transfer bias) to the intermediate transfer member 50. The intermediate transfer body 50 is provided with a cleaning device 90 having a cleaning blade in the vicinity thereof, and for transferring (secondary transfer) a developed image (toner image) to a transfer sheet 95 as a final transfer material. A transfer roller 80 serving as a transfer unit to which a transfer bias can be applied is disposed to face the transfer roller 80. Around the intermediate transfer member 50, a corona charger 58 for applying a charge to the toner image on the intermediate transfer member 50 is arranged between the photosensitive member 10 and the intermediate transfer member 50 in the rotation direction of the intermediate transfer member 50. It is disposed between the contact portion and the contact portion between the intermediate transfer member 50 and the transfer paper 95.

  The developing device 40 includes a developing belt 41 as the developer carrying member, and a black developing unit 45K, a yellow developing unit 45Y, a magenta developing unit 45M, and a cyan developing unit 45C provided around the developing belt 41. . The black developing unit 45K includes a developer accommodating portion 42K, a developer supplying roller 43K, and a developing roller 44K. The yellow developing unit 45Y includes a developer accommodating portion 42Y, a developer supplying roller 43Y, and a developing roller 44Y. The magenta developing unit 45M includes a developer accommodating portion 42M, a developer supplying roller 43M, and a developing roller 44M, and the cyan developing unit 45C includes a developer accommodating portion 42C and a developer supplying roller 43C. And a developing roller 44C. The developing belt 41 is an endless belt, is rotatably stretched around a plurality of belt rollers, and a part thereof is in contact with the photoconductor 10.

  In the image forming apparatus 100 shown in FIG. 3, for example, the charging roller 20 uniformly charges the photosensitive drum 10. The exposure device 30 performs imagewise exposure on the photosensitive drum 10 to form an electrostatic latent image. The electrostatic latent image formed on the photosensitive drum 10 is developed by supplying toner from the developing device 40 to form a visible image (toner image). The visible image (toner image) is transferred (primary transfer) onto the intermediate transfer member 50 by the voltage applied from the roller 51, and further transferred (secondary transfer) onto the transfer paper 95. As a result, a transfer image is formed on the transfer paper 95. The residual toner on the photoconductor 10 is removed by the cleaning device 60, and the charge on the photoconductor 10 is temporarily removed by the charge eliminating lamp 70.

  Another mode for carrying out the image forming method of the present invention by the image forming apparatus of the present invention will be described with reference to FIG. The image forming apparatus 100 shown in FIG. 4 does not include the developing belt 41 in the image forming apparatus 100 shown in FIG. 3, and a black developing unit 45K, a yellow developing unit 45Y, a magenta developing unit 45M, and the like around the photoconductor 10. Except for the fact that the cyan developing unit 45C is arranged directly opposite, it has the same configuration as the image forming apparatus 100 shown in FIG. In FIG. 4, the same components as those in FIG. 3 are denoted by the same reference numerals.

Another mode for carrying out the image forming method of the present invention by the image forming apparatus of the present invention will be described with reference to FIG. The tandem image forming apparatus shown in FIG. 5 is a tandem type color image forming apparatus. The tandem image forming apparatus includes a copying apparatus main body 150, a paper feed table 200, a scanner 300, and an automatic document feeder (ADF) 400.
The copying apparatus main body 150 is provided with an endless belt-like intermediate transfer member 50 at the center. The intermediate transfer member 50 is stretched around the support rollers 14, 15, and 16 and can be rotated clockwise in FIG. 5. An intermediate transfer member cleaning device 17 for removing residual toner on the intermediate transfer member 50 is disposed in the vicinity of the support roller 15. The intermediate transfer member 50 stretched between the support roller 14 and the support roller 15 is a tandem type in which four image forming units 18 of yellow, cyan, magenta, and black are arranged to face each other along the conveyance direction. A developing device 120 is disposed. An exposure device 21 is disposed in the vicinity of the tandem developing device 120. A secondary transfer device 22 is disposed on the side of the intermediate transfer member 50 opposite to the side on which the tandem developing device 120 is disposed. In the secondary transfer device 22, a secondary transfer belt 24, which is an endless belt, is stretched around a pair of rollers 23, and the transfer paper conveyed on the secondary transfer belt 24 and the intermediate transfer body 50 are in contact with each other. Is possible. A fixing device 25 is disposed in the vicinity of the secondary transfer device 22. The fixing device 25 includes a fixing belt 26 that is an endless belt, and a pressure roller 27 that is pressed against the fixing belt 26.
In the tandem image forming apparatus, a sheet reversing device 28 for reversing the transfer paper for image formation on both sides of the transfer paper is disposed in the vicinity of the secondary transfer device 22 and the fixing device 25. Yes.

  Next, formation of a full color image (color copy) using the tandem image forming apparatus will be described. That is, first, a document is set on the document table 130 of the automatic document feeder (ADF) 400, or the automatic document feeder 400 is opened and the document is set on the contact glass 32 of the scanner 300. 400 is closed.

  When a start switch (not shown) is pressed, when the document is set on the automatic document feeder 400, the document is transported and moved onto the contact glass 32, and then the document is set on the contact glass 32. Immediately after that, the scanner 300 is driven, and the first traveling body 33 and the second traveling body 34 travel. At this time, light from the light source is irradiated by the first traveling body 33 and reflected light from the document surface is reflected by the mirror in the second traveling body 34 and is received by the reading sensor 36 through the imaging lens 35 to be color. An original (color image) is read and used as black, yellow, magenta, and cyan image information.

  Each image information of black, yellow, magenta and cyan is stored in each image forming means 18 (black image forming means, yellow image forming means, magenta image forming means and cyan image forming means in the tandem image forming apparatus. ) And black, yellow, magenta and cyan toner images are formed in the respective image forming means. That is, each of the image forming means 18 (black image forming means, yellow image forming means, magenta image forming means, and cyan image forming means) in the tandem image forming apparatus is photosensitive as shown in FIG. On the basis of the body 10 (the black photoreceptor 10K, the yellow photoreceptor 10Y, the magenta photoreceptor 10M, and the cyan photoreceptor 10C), the charger 60 that uniformly charges the photoreceptor, and each color image information. The photosensitive member is exposed to each color image corresponding image (L in FIG. 6), and an electrostatic latent image corresponding to each color image is formed on the photosensitive member. A developing device 61 that develops using a color developer (black developer, yellow developer, magenta developer, and cyan developer) to form a toner image with each color developer, and the toner image is an intermediate transfer member. The image forming apparatus includes a transfer charger 62 for transferring the image onto 0, a photoconductor cleaning device 63, and a static eliminator 64, and each monochrome image (black image, yellow image, magenta) based on the image information of each color. Image and cyan image) can be formed. The black image, the yellow image, the magenta image, and the cyan image formed in this way are formed on the black photoconductor 10K on the intermediate transfer member 50 that is rotationally moved by the support rollers 14, 15, and 16, respectively. The black image, the yellow image formed on the yellow photoconductor 10Y, the magenta image formed on the magenta photoconductor 10M, and the cyan image formed on the cyan photoconductor 10C are sequentially transferred (primary transfer). Is done. Then, the black image, the yellow image, the magenta image, and the cyan image are superimposed on the intermediate transfer member 50 to form a composite color image (color transfer image).

On the other hand, in the paper feed table 200, one of the paper feed rollers 142 is selectively rotated to feed out a sheet (recording paper) from one of the paper feed cassettes 144 provided in multiple stages in the paper bank 143. Each sheet is separated and sent to the paper feed path 146, transported by the transport roller 147, guided to the paper feed path 148 in the copying machine main body 150, and abutted against the registration roller 49 and stopped. Alternatively, the sheet feed roller 142 is rotated to feed out sheets (recording paper) on the manual feed tray 54, separated one by one by the separation roller 52, put into the manual feed path 53, and abutted against the registration roller 49 and stopped. . The registration roller 49 is generally used while being grounded, but may be used in a state where a bias is applied to remove paper dust from the sheet.
Then, the registration roller 49 is rotated in synchronization with the synthesized color image (color transfer image) synthesized on the intermediate transfer member 50, and a sheet (recording paper) is interposed between the intermediate transfer member 50 and the secondary transfer device 22. The secondary color transfer device 22 transfers the composite color image (color transfer image) onto the sheet (recording paper), thereby transferring the color image onto the sheet (recording paper). Is formed. The residual toner on the intermediate transfer member 50 after image transfer is cleaned by the intermediate transfer member cleaning device 17.

  The sheet (recording paper) on which the color image has been transferred is conveyed by the secondary transfer device 22 and sent to the fixing device 25, where the combined color image (color) is generated by heat and pressure. (Transfer image) is fixed on the sheet (recording paper). Thereafter, the sheet (recording paper) is switched by the switching claw 55 and discharged by the discharge roller 56 and stacked on the discharge tray 57, or switched by the switching claw 55 and reversed by the sheet reversing device 28 and transferred again. After being guided to the position and recording an image on the back surface, the image is discharged by the discharge roller 56 and stacked on the discharge tray 57.

  In the image forming apparatus and the image forming method of the present invention, the durability is excellent, the carrier does not adhere to the solid image portion during the running time, the fine image can be formed over a long period of time, and the color stain does not occur. Since the developer of the present invention containing the electrophotographic carrier having good charge controllability is used, a clear high-quality image can be formed.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, this invention is not limited at all by these Examples.

Example 1
<Preparation of carrier 1>
The following composition was dispersed with a homomixer for 10 minutes to prepare a coating layer forming solution.
-Composition of coating layer forming solution-
・ Acrylic resin solution (solid content concentration: 50 mass%): 1500 mass parts ・ Guanamine solution (solid content concentration: 70 mass%): 450 mass parts ・ Acid catalyst (solid content concentration) : 9 mass parts Alumina particles (volume average particle size: 0.35 μm, volume resistivity: 1.0 × 10 ¹⁴ Ω · cm) ··································· 1500 parts by mass Titanium oxide particles (volume average particle diameter: 0.015 μm, volume resistivity: 1.0 × 10 ⁶ Ω · cm) ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ 500 parts by mass ・ Toluene .... 6000 parts by mass

Next, a sintered ferrite powder having a volume average particle size of 35 μm was used as the core material, and the coating layer forming solution was applied to the surface of the core material with a Spira coater (manufactured by Okada Seiko Co., Ltd.) at a coater internal temperature of 40 ° C. and dried.
The obtained carrier was baked in an electric furnace at 180 ° C. for 1 hour. After cooling, the ferrite powder bulk was crushed using a sieve having an aperture of 63 μm to prepare “Carrier 1”.
The average thickness h of the resin part in the coating layer of the obtained “carrier 1” is 0.15 μm, the average thickness T from the core material surface to the coating layer surface is 0.2 μm, and the content of the first particles (alumina) is 48 mass%, D1 / h was 2.3, the content of second particles (titanium oxide) was 16 mass%, and D2 / h was 0.10.

  In addition, the volume average particle diameter of the core material was measured by using an SRA type of a Microtrac particle size analyzer (Nikkiso Co., Ltd.) with a range setting of 0.7 μm or more and 125 μm or less.

The average thickness h (μm) of the resin part in the coating layer is observed with a transmission electron microscope (TEM), and the thickness of the resin part in the coating layer is 0.2 μm along the carrier surface. 50 points were measured at intervals, and the measured values obtained were averaged.
The average thickness T (μm) from the surface of the core material to the surface of the coating layer is determined by observing the cross section of the carrier using a transmission electron microscope (TEM), and the thickness from the surface of the core material to the surface of the coating layer. Were measured at intervals of 0.2 μm, and the obtained measured values were averaged.

<Production of toner>
The following materials are mixed with a Henschel mixer, melt-kneaded for 40 minutes at 120 ° C using two rolls, cooled, coarsely pulverized with a hammer mill, and finely pulverized with an air jet pulverizer, and the resulting fine powder is classified. Thus, toner base particles having a weight average particle diameter of 5 μm were prepared.
-Composition of toner base particles-
・ Binder resin (polyester resin) ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ 100 parts by weight ・ Release agent (carnauba wax) ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ 6 parts by weight ・Charge control agent (E-84, manufactured by Orient Chemical Industry Co., Ltd.) 1.5 parts by weight Colorant (CI PY155) 6 parts by weight

  Next, to 100 parts by mass of the obtained toner base particles, 1 part by mass of silica whose surface has been hydrophobized and 1 part by mass of titanium oxide whose surface has been hydrophobized are added and mixed with a Henschel mixer to thereby produce a yellow toner “Toner 1” was prepared.

Next, 17 parts by mass of the obtained “Toner 1” and 93 parts by mass of “Carrier 1” were mixed and stirred to prepare a developer having a toner concentration of 7% by mass.
The resulting developer was evaluated for image definition, durability (charge reduction amount, resistance change amount), and solid image carrier adhesion as follows. The results are shown in Table 1.

<Charge amount>
The charge amount is a value measured by a general blow-off method [TB-200, manufactured by Toshiba Chemical Co., Ltd.] by mixing a frictionally charged sample mixed at a ratio of 7% by mass of toner with respect to 93% by mass of carrier. .

<Volume resistivity>
Volume resistivity is a value obtained by putting a carrier between electrodes of a resistance measuring parallel electrode (gap 2 mm), applying DC 1,000 V, and converting a resistance value measured after 30 sec with a high resist meter into volume resistivity. Asked.

<Image definition>
The image definition was evaluated by the reproducibility of the character image portion. The evaluation method is to set a developer on a commercially available digital full color printer (IPSiO CX8200, manufactured by Ricoh Co., Ltd.), and output a character chart (image size is about 2 mm × 2 mm) with an image area of 5%. The character reproducibility was evaluated by images, and ranked as follows. In addition, (double-circle) was set as pass and x was set as the failure.
◎: Very good ○: Good △: Acceptable ×: Unusable level for practical use

<Skin carrier adhesion>
For the carrier adhesion on the background, set the developer on a commercially available digital full-color printer (IPCO CX8200, manufactured by Ricoh Co., Ltd.), fix the background potential at 150 V, and set the A3 character chart (1 character The size was about 2 mm × 2 mm), and the evaluation was made based on the number of occurrences of carrier adhesion on the ground portion, and the ranking was performed as follows. In addition, (double-circle) was set as the pass and x was set as the failure.
◎: 0 ◯: 2 or more and 5 or less △: 6 or more and 10 or less ×: 11 or more

<Durability>
A developer was set on a commercially available digital full color printer (IPSiO CX8200, manufactured by Ricoh Co., Ltd.), and a running evaluation of 100,000 sheets in a single color was performed. Then, the durability was judged based on the charge reduction amount and resistance reduction amount of the carrier after the running.
Here, the amount of decrease in the charge amount is a sample obtained by mixing and charging at a ratio of 5% by mass of toner to 95% by mass of the initial carrier by a general blow-off method (TB-200, manufactured by Toshiba Chemical Corporation). ) Was subtracted from the charge amount (Q2) measured by the same method as in the above method, from the charge amount (Q1) measured in step 1). Means quantity. The target value is within 10.0 μc / g. 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.
Here, the amount of decrease in resistance was measured by using a high resist meter to measure the resistance value after 30 seconds after applying an initial carrier between the electrodes of the resistance measurement parallel electrode (gap 2 mm), applying DC 1,000V. The value obtained by converting the obtained value into the volume resistivity (R1), and measuring the carrier obtained by removing the toner in the developer after running with the blow-off device by the same method as the resistance measuring method. It means the amount obtained by subtracting (R2). The target value is within 3.0 [Log (Ω · cm)] in absolute value. The cause of the resistance change is scraping of the carrier coating layer, spent toner component, large particle detachment in the carrier coating layer, and the like. By reducing these, the resistance reduction amount can be suppressed.

<Solid image carrier adhesion>
After the above durability evaluation, the background potential is fixed to 150 V using the same digital full-color printer, and the white spots on the image obtained by developing the front solid image on A3 size paper and the number of carriers actually attached are determined. Counting was carried out by magnifying glass observation, and the total number was used as the solid image carrier adhesion amount. Evaluation was made according to the following criteria. In addition, (double-circle) was set as the pass and x was set as the failure.
◎: 0 ◯: 2 or more and 5 or less △: 6 or more and 10 or less ×: 11 or more

(Example 2)
In Example 1, “Carrier 2” was produced in the same manner as in Example 1 except that the composition of the coating layer was changed as follows.
In the obtained “Carrier 2”, the average thickness h of the resin part in the coating layer is 0.15 μm, the average thickness T from the core material surface to the coating layer surface is 0.2 μm, and the content of the first particles (alumina) is 48% by mass, D1 / h was 2.3, the content of second particles (titanium oxide) was 16% by mass, and D2 / h was 0.10.
-Composition of coating layer-
・ Acrylic resin solution (solid content: 50% by mass) ... 700 parts by mass-Guanamine solution (solid content: 70% by mass) ... 200 parts by massAcid catalyst ( Solid content concentration 40 mass%) ... 4 parts by mass Silicone resin solution (solid content concentration 20 mass%) ... 3000 parts by mass Aminosilane ( Solid content concentration 100% by mass) ······ 4 parts by mass Alumina particles (volume average particle size: 0.35 μm, volume resistivity: 1.0 × 10 ¹⁴ Ω · cm)・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ 1,500 parts by mass × 10 ⁶ Ω
・ Cm) ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ 500 parts by mass ・ Toluene ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・・ ・ ・ ・ ・ ・ 6,000 parts by mass

  Next, using the obtained “Carrier 2”, a developer was produced in the same manner as in Example 1, and in the same manner as in Example 1, the fineness and durability of the image (charge reduction amount, resistance change amount). ), Carrier adhesion on the background and solid image carrier adhesion were evaluated. The results are shown in Table 1.

(Example 3)
In Example 2, except that the second particles were changed to zinc oxide (volume average particle size: 0.02 μm, volume specific resistance: 1.0 × 10 ⁷ Ω · cm), “ Carrier 3 "was produced.
The average thickness h of the resin part in the coating layer of the obtained “carrier 3” is 0.15 μm, the average thickness T from the core surface to the coating layer surface is 0.2 μm, and the content of the first particles (alumina) is 48% by mass, D1 / h was 2.3, the content of second particles (zinc oxide) was 16% by mass, and D2 / h was 0.13.

  Next, using the obtained “Carrier 3”, a developer was prepared in the same manner as in Example 1, and in the same manner as in Example 1, the fineness and durability of the image (charge reduction amount, resistance change amount). ), Carrier adhesion on the background and solid image carrier adhesion were evaluated. The results are shown in Table 1.

Example 4
In Example 2, except that the second particles were changed to tin oxide (volume average particle size: 0.02 μm, volume resistivity: 1.0 × 10 ⁵ Ω · cm), “ Carrier 4 "was produced.
The average thickness h of the resin part in the coating layer of the obtained “carrier 4” is 0.15 μm, the average thickness T from the core surface to the coating layer surface is 0.2 μm, and the content of the first particles (alumina) is 48 mass%, D1 / h was 2.3, the content of second particles (tin oxide) was 16 mass%, and D2 / h was 0.13.

  Next, using the obtained “Carrier 4”, a developer was produced in the same manner as in Example 1, and in the same manner as in Example 1, the fineness and durability of the image (charge reduction amount, resistance change amount). ), Carrier adhesion on the background and solid image carrier adhesion were evaluated. The results are shown in Table 1.

(Example 5)
In Example 2, “Carrier 5” was produced in the same manner as in Example 2, except that the content of the second particles (titanium oxide) was changed to 54 mass% (prescription; 3,000 parts by mass).
In the obtained “Carrier 5”, the average thickness h of the resin portion in the coating layer is 0.15 μm, the average thickness T from the core material surface to the coating layer surface is 0.18 μm, and the first particle (alumina) content is 27. The mass%, D1 / h was 2.3, and D2 / h was 0.10.

  Next, using the obtained “Carrier 5”, a developer was produced in the same manner as in Example 1, and in the same manner as in Example 1, the fineness and durability of the image (charge reduction amount, resistance change amount). ), Carrier adhesion on the background and solid image carrier adhesion were evaluated. The results are shown in Table 1.

(Example 6)
In Example 2, “Carrier 6” was produced in the same manner as in Example 2 except that the content of the first particles (alumina) was changed to 86% by mass (prescription: 10,000 parts by mass).
The average thickness h of the resin part in the coating layer of the obtained “carrier 6” was 0.15 μm, the average thickness T from the core surface to the coating layer surface was 0.23 μm, D1 / h was 2.3, The content of particles (titanium oxide) was 4.3% by mass, and D2 / h was 0.10.

  Next, using the obtained “Carrier 6”, a developer was produced in the same manner as in Example 1, and the fineness and durability of the image (charge reduction amount, resistance change amount) in the same manner as in Example 1. ), Carrier adhesion on the background and solid image carrier adhesion were evaluated. The results are shown in Table 1.

(Example 7)
In Example 2, “Carrier 7” was produced in the same manner as in Example 2 except that the coating amount was changed so that the coating layer thickness was doubled.
The average thickness h of the resin part in the coating layer of the obtained “carrier 7” was 0.15 μm, the average thickness T from the core surface to the coating layer surface was 0.4 μm, and the first particle (alumina) content was 48. % By mass, D1 / h was 2.3, the content of second particles (titanium oxide) was 16% by mass, and D2 / h was 0.10.

  Next, using the obtained “Carrier 7”, a developer was produced in the same manner as in Example 1. Fineness and durability of the image (charge reduction amount, resistance change amount) in the same manner as in Example 1. The carrier adhesion on the background and the solid image carrier adhesion were evaluated. The results are shown in Table 1.

(Example 8)
In Example 2, “Carrier 8” was produced in the same manner as in Example 2 except that the coating amount was changed so that the coating layer thickness was 0.4 times.
The average thickness h of the resin part in the coating layer of the obtained “carrier 8” was 0.15 μm, the average thickness T from the core surface to the coating layer surface was 0.08 μm, and the first particle (alumina) content was 48. % By mass, D1 / h was 2.3, the content of second particles (titanium oxide) was 16% by mass, and D2 / h was 0.10.

  Next, using the obtained “Carrier 8”, a developer was produced in the same manner as in Example 1, and in the same manner as in Example 1, the fineness and durability of the image (charge reduction amount, resistance change amount). The carrier adhesion on the background and the solid image carrier adhesion were evaluated. The results are shown in Table 1.

Example 9
In Example 2, “Carrier 9” was produced in the same manner as in Example 2 except that the coating amount was changed so that the coating layer thickness was 16 times.
The average thickness h of the resin part in the coating layer of the obtained “carrier 9” was 0.15 μm, the average thickness T from the core surface to the coating layer surface was 3.2 μm, and the first particle (alumina) content was 48. % By mass, D1 / h was 2.3, the content of second particles (titanium oxide) was 16% by mass, and D2 / h was 0.10.

  Next, using the obtained “Carrier 9”, a developer was prepared in the same manner as in Example 1, and in the same manner as in Example 1, the fineness and durability of the image (charge reduction amount, resistance change amount). The carrier adhesion on the background and the solid image carrier adhesion were evaluated. The results are shown in Table 1.

(Example 10)
In Example 1, except that the first particles were changed to alumina particles (volume average particle size: 0.35 μm, volume specific resistance: 1 × 10 ¹¹ Ω · cm), “Carrier 10 Was made.
The average thickness h of the resin part in the coating layer of the obtained “carrier 10” is 0.15 μm, the average thickness T from the core surface to the coating layer surface is 0.2 μm, and the content of the first particles (alumina) is 48% by mass, D1 / h was 2.3, the content of second particles (tin oxide) was 16% by mass, and D2 / h was 0.1.

(Example 11)
In Example 1, except that the first particles were changed to silica particles (volume average particle diameter: 0.35 μm, volume resistivity: 1 × 10 ¹⁴ Ω · cm), “Carrier 11 "created.
The average thickness h of the resin part in the coating layer of the obtained “carrier 11” is 0.15 μm, the average thickness T from the core material surface to the coating layer surface is 0.2 μm, and the content of the first particles (silica particles) Was 48 mass%, D1 / h was 2.3, the content of second particles (tin oxide) was 16 mass%, and D2 / h was 0.1.

(Example 12)
In Example 1, except that the second particles were changed to zinc oxide (volume average particle size: 0.02 μm, volume resistivity: 1.0 × 10 ⁷ Ω · cm), Carrier 12 "was produced.
The average thickness h of the resin part in the coating layer of the obtained “carrier 12” is 0.15 μm, the average thickness T from the core surface to the coating layer surface is 0.2 μm, and the content of the first particles (alumina) is 48% by mass, D1 / h was 2.3, the content of second particles (zinc oxide) was 16% by mass, and D2 / h was 0.13.

(Example 13)
In Example 2, “Carrier 13” was produced in the same manner as in Example 2, except that the content of the second particles (titanium oxide) was changed to 74% by mass (prescription; 7,200 parts by mass).
The average thickness h of the resin part in the coating layer of the obtained “carrier 13” is 0.15 μm, the average thickness T from the core surface to the coating layer surface is 0.18 μm, and the first particle (alumina) content is 27. The mass%, D1 / h was 2.3, and D2 / h was 0.10.

  Next, using the obtained “Carrier 13”, a developer was prepared in the same manner as in Example 1, and the fineness and durability of the image (the amount of decrease in charge and the amount of change in resistance were the same as in Example 1. ), Carrier adhesion on the background and solid image carrier adhesion were evaluated. The results are shown in Table 1.

(Example 14)
In Example 2, “Carrier 14” was produced in the same manner as in Example 2 except that the content of the first particles (alumina) was changed to 90% by mass (prescription: 13,600 parts by mass).
The average thickness h of the resin part in the coating layer of the obtained “carrier 14” was 0.15 μm, the average thickness T from the core surface to the coating layer surface was 0.23 μm, D1 / h was 2.3, The content of particles (titanium oxide) was 4.3% by mass, and D2 / h was 0.10.

  Next, using the obtained “Carrier 14”, a developer was produced in the same manner as in Example 1, and the fineness and durability of the image (charge reduction amount, resistance change amount) were obtained in the same manner as in Example 1. ), Carrier adhesion on the background and solid image carrier adhesion were evaluated. The results are shown in Table 1.

(Comparative Example 1)
In Example 2, “Carrier 15” was produced in the same manner as in Example 2 except that the volume average particle diameter of the first particles was changed to 0.1 μm.
The average thickness h of the resin part in the coating layer of the obtained “carrier 15” is 0.15 μm, the average thickness T from the core surface to the coating layer surface is 0.22 μm, and the content of the first particles (alumina) is 48.0% by mass, D1 / h was 0.7, the content of second particles (titanium oxide) was 16% by mass, and D2 / h was 0.10.

  Next, using the obtained “carrier 15”, a developer was produced in the same manner as in Example 1, and the fineness and durability of the image (the amount of decrease in charge, the amount of change in resistance) were the same as in Example 1. ), Carrier adhesion on the background and solid image carrier adhesion were evaluated. The results are shown in Table 1.

Since the electrophotographic carrier of the present invention hardly generates toner spent on the surface, a stable charge amount can be obtained over a long period of time, and the binder resin film is not easily scraped, so that stable electric resistance can be maintained over a long period of time. can get. Furthermore, since the carrier adhesion on the solid image during the running time is very small, there is no image deterioration due to carrier adhesion, and image deterioration and durability deterioration due to a decrease in the developer amount do not occur. Furthermore, a high-definition image can be obtained. Furthermore, the carrier adhesion on the background portion is good. In addition, since it does not contain carbon black that causes color stains, it has very good properties as a carrier for color that is affected by color stains. Accordingly, the image quality deterioration of the copy image that occurs as the number of copies increases is greatly improved, and an excellent effect is achieved that a good image can be maintained over a long period of time.
The developer of the present invention can be suitably used for image formation by various known electrophotographic methods such as a two-component development method. The developer-containing container, process cartridge, image forming apparatus, and image forming method of the present invention described below It can be particularly preferably used.

FIG. 1 is a schematic view showing an example of an image forming apparatus equipped with the developer-containing container of the present invention. FIG. 2 is a schematic explanatory view showing an example of the process cartridge of the present invention. FIG. 3 is a schematic explanatory view showing an example in which the image forming method of the present invention is carried out by the image forming apparatus of the present invention. FIG. 4 is a schematic explanatory view showing another example in which the image forming method of the present invention is implemented by the image forming apparatus of the present invention. FIG. 5 is a schematic explanatory view showing an example in which the image forming method of the present invention is implemented by the image forming apparatus (tandem color image forming apparatus) of the present invention. 6 is a partially enlarged schematic explanatory view of the image forming apparatus shown in FIG. FIG. 7 is an explanatory view showing the coating layer of the electrophotographic carrier of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Developing part 2 Container with developer 3 Developer feeding means 4 Developing housing 5 Agitating screw 6 Agitating screw 7 Developing roller 8 Photoreceptor 9 Doctor blade 10 Photoreceptor (photoreceptor drum)
10K black photoconductor 10Y yellow photoconductor 10M magenta photoconductor 10C cyan photoconductor 14 support roller 15 support roller 16 support roller 17 intermediate transfer cleaning device 18 image forming means 20 charging roller 21 exposure device 22 secondary transfer device 23 Secondary transfer belt 25 Fixing device 26 Fixing belt 27 Pressure belt 28 Sheet reversing device 30 Exposure device 32 Contact glass 33 First traveling body 34 Second traveling body 35 Imaging lens 36 Reading sensor 40 Developing device 41 Developing belt 42K Developer Container 42Y Developer Container 42M Developer Container 42C Developer Container 43K Developer Supply Roller 43Y Developer Supply Roller 43M Developer Supply Roller 43C Developer Supply Roller 44K Developer Roller 44Y Developer Roller 44M Developer Roller 44 Developing roller 45K Black developing unit 45Y Yellow developing unit 45M Magenta developing unit 45C Cyan developing unit 49 Registration roller 50 Intermediate transfer member 51 Roller 52 Separating roller 53 Manual feed path 54 Manual feed tray 55 Switching claw 56 Discharge roller 57 Discharge Tray 58 Corona charger 60 Cleaning device 61 Developing device 62 Transfer charger 63 Photoconductor cleaning device 64 Electric discharger 70 Electric discharge lamp 71 Cleaning blade 72 Support member 80 Transfer roller 90 Cleaning device 95 Transfer paper 100 Image forming device 101 Photoconductor 102 Charging Means 103 Exposure 104 Developing means 105 Recording medium 108 Transfer means 107 Cleaning means 120 Tandem type developer 130 Document table 142 Paper feed roller 143 Paper bank 144 Paper feed cassette 145 Separating roller 146 Feeding path 147 Conveying roller 148 Feeding path 150 Copier main body 200 Feeding table 300 Scanner 400 Automatic document feeder (ADF)
501 Binder resin 502 Particles 503 Core material surface ha to hd Thickness of resin part of coating layer T Thickness from core material surface to coating layer surface A Measurement point A

Claims (14)

A core material and a coating layer covering the core material, the coating layer including at least a binder resin, first particles, and second particles;
The particle diameter D1 (μm) of the first particles and the average thickness h (μm) of the resin portion in the coating layer satisfy the following formula, 1 <(D1 / h) <10,
The particle diameter D2 (μm) of the second particles and the average thickness h (μm) of the resin portion in the coating layer satisfy the following expression: 0.001 <(D2 / h) <1, and the second A carrier for electrophotography, wherein the volume resistivity of the particles is 1.0 × 10 ¹² Ω · cm or less.   2. The electrophotographic carrier according to claim 1, wherein an average thickness T (μm) from the surface of the core material to the surface of the coating layer is 0.1 ≦ T ≦ 3.0. The electrophotographic carrier according to claim 1, wherein the volume resistivity of the first particles is 1.0 × 10 ¹² Ω · cm or more.   The carrier for electrophotography according to any one of claims 1 to 3, wherein the first particles are alumina particles.   The electrophotographic carrier according to claim 1, wherein the content of the first particles in the coating layer is 10 to 80% by mass.   The second particle is at least one particle selected from titanium oxide, zinc oxide, tin oxide, surface-treated titanium oxide, surface-treated zinc oxide, and surface-treated tin oxide. 6. The electrophotographic carrier according to any one of 5 above.   The electrophotographic carrier according to claim 1, wherein the content of the second particles in the coating layer is 2 to 50% by mass.   The electrophotographic carrier according to claim 1, wherein the binder resin is any one of a reaction product of an acrylic resin and an amino resin, and a silicone resin.   A developer comprising the electrophotographic carrier according to claim 1 and a toner.   The developer according to claim 9, wherein the toner includes at least a binder resin and a colorant.   A developer-filled container, which is filled with the developer according to claim 9.   An electrostatic latent image carrier and a developing unit that develops the electrostatic latent image formed on the electrostatic latent image carrier using the developer according to claim 9 to form a visible image. And a process cartridge.   11. The electrostatic latent image carrier, electrostatic latent image forming means for forming an electrostatic latent image on the electrostatic latent image carrier, and developing the electrostatic latent image according to any one of claims 9 to 10. Development means for forming a visible image by developing using an agent, transfer means for transferring the visible image to a recording medium, and fixing means for fixing the transferred image transferred to the recording medium. An image forming apparatus. An electrostatic latent image forming step for forming an electrostatic latent image on the electrostatic latent image carrier, and the electrostatic latent image is developed using the developer according to claim 9 and visible. An image forming method comprising: a developing step for forming an image; a transfer step for transferring the visible image to a recording medium; and a fixing step for fixing the transferred image transferred to the recording medium.