JP2002091090A - Resin-coated carrier, two-component developer, and image forming method - Google Patents

Abstract

(57) [Problem] To provide a resin-coated carrier capable of achieving carrier suppression and long-term image stability by controlling the amount of fine powder and magnetic properties of the coated carrier within specific ranges. SOLUTION: In a resin-coated carrier comprising at least a carrier core and a resin coating layer, the resin-coated carrier A has an average particle diameter of 25 to 55 µm and a resin-coated carrier particle B of 20 µm or less by a mesh method.
And the resin-coated carriers A and B have magnetization intensities σa and σb (Am ² / kg) at 1000 / 4π (kA / m), respectively, of the following relational expression 30 ≦ σa ≦ 70 20 ≦ σb ≦ 60 0.2 ≦ σa−σb ≦ 20.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin-coated carrier, a two-component developer having the resin-coated carrier and a toner, and an image forming method using the two-component developer. More specifically, the present invention relates to a resin-coated carrier for forming a two-component developer for developing an electrostatic image by an electrophotographic method together with a toner, and a two-component developer having the resin-coated carrier and a toner. And an image forming method using the two-component developer.

[0002]

2. Description of the Related Art As an electrophotographic method, US Pat.
Various methods are described in JP-B-97,691, JP-B-42-23910 and JP-B-43-24748. In these methods, an electrostatic image is formed by irradiating a photoconductive layer with a light image corresponding to an original, and then toner is adhered on the electrostatic image to develop the electrostatic image, and if necessary, After transferring the toner image onto a transfer material such as paper, the toner image is fixed by heat, pressure, heat and pressure or solvent vapor to obtain a copy or print.

In recent years, with the development of computers and multimedia, there is a demand for means for outputting higher definition full color images in a wide range of fields from offices to homes. Heavy users demand high durability without deterioration in image quality even when copying or printing a large number of sheets, and in small offices and homes, obtain high-quality images, reduce the size of the device from the viewpoint of space saving and energy saving, and reduce waste toner. There is a demand for recycling, waste toner-less (cleaner-less), and lowering the fixing temperature, and various studies have been made from each viewpoint to achieve these objects.

In the electrophotographic method, the step of developing an electrostatic image is to form an image of the charged toner particles on the electrostatic image by utilizing the electrostatic interaction of the electrostatic image.
Among the developers for developing an electrostatic image using toner, a magnetic one-component developer using a magnetic toner in which a magnetic material is dispersed in a resin, and a non-magnetic material using a charging member such as an elastic blade. There is a non-magnetic one-component developer that is charged and developed, and a two-component developer in which a non-magnetic toner is mixed with a magnetic carrier. Full-color image formation such as a full-color copying machine or a full-color printer that requires particularly high image quality In the device, the latter is preferably used.

As a magnetic carrier used in a two-component developer, an iron powder carrier, a ferrite carrier, or a resin-coated carrier in which magnetic fine particles are dispersed in a binder resin are known. A developer using a resin-coated carrier in which the surface of the carrier core material is coated with a resin can optimize resistance, has excellent charge controllability, and is relatively easy to improve environmental dependence and stability over time. Therefore, it is preferably used.

On the other hand, in recent years, in the process of forming a positive latent image on a photoconductor, a technique for exposing the photoconductor using a small-diameter laser beam or the like has been developed, and the electrostatic latent image has become finer. Along with this, the diameter of both toner particles and carrier particles has been reduced in order to faithfully develop electrostatic latent images and obtain higher image quality output. In particular, the image quality is often improved by reducing the average particle diameter of the toner.

To reduce the average particle size of the toner,
Among the image quality characteristics, this is an effective means for improving graininess and character reproducibility in particular, but has a problem to be improved in specific image quality items, particularly, fog and toner scattering during durability.

The cause of this is that, first of all, the use of the toner over a long period of time causes deterioration of the external additive of the toner and contamination of the carrier by the toner and the external additive, that is, spent, and as a result, the charge of the toner is reduced. It happens. This phenomenon is likely to occur when the diameter of the toner is reduced. More specifically, since the triboelectric charging is performed by a physical external force such as contact and collision between the toner and the carrier, the toner and the carrier are inevitably damaged. For example, in a toner, an external additive added to the surface of the toner is embedded in the toner, or a toner component is dropped. The carrier is contaminated by a toner component containing an external additive, and the resin-coated carrier is worn or destroyed by the carrier coat component. As these damages increase, the initial characteristics of the developer cannot be maintained as the number of copies increases,
This may cause background fog, in-machine dirt, and fluctuations in image density. This phenomenon becomes more noticeable as the pixel unit of the electrostatic latent image becomes finer.

Secondly, when an original having a high image area ratio is used, it takes time until the toner is uniformly charged when a large amount of toner is supplied, and uncharged toner contributes to development. The above problem occurs. This phenomenon is a phenomenon that occurs notably when the diameter of the toner is reduced and the fluidity is reduced. Such image defects particularly require improvement when a multicolor superimposed image is formed using a two-component developer. This problem has conventionally been focused on the consideration of carrier resistance, but has not been solved yet.

[0010] In order to solve the insufficient charging of the toner having a small particle diameter as described above, reducing the particle diameter of the carrier is also a suitable means. Is likely to cause deterioration.

Although these problems have been attempted to increase the amount of carriers used, they are against the downsizing of copiers or printers and are not practical.

That is, a developer that maintains image quality and has excellent durability stability has not been provided yet.

[0013]

As described above, in consideration of the above-mentioned required characteristics of the carrier, the conventional carrier still has a problem to be improved, and further improvement is desired.

Particularly, in a resin-coated carrier, (1) durability (2) environmental properties (3) anti-spent resistance including adhesion of external additives (4) charge-imparting property to toner (5) developability (6) photosensitivity There is a need for a carrier that further improves carrier adhesion on the body (7) prevents toner deterioration.

An object of the present invention is to propose a resin-coated carrier which solves the above problems, a two-component developer having the resin-coated carrier and a toner, and an image forming method using the two-component developer. It is in.

An object of the present invention is to propose a resin-coated carrier having excellent durability, a two-component developer having the resin-coated carrier and a toner, and an image forming method using the two-component developer. It is in.

An object of the present invention is to propose a resin-coated carrier having excellent environmental characteristics, a two-component developer having the resin-coated carrier and a toner, and an image forming method using the two-component developer. It is in.

An object of the present invention is to provide a resin-coated carrier having excellent spent resistance including the attachment of an external additive, a two-component developer having the resin-coated carrier and a toner, and the use of the two-component developer. It is to propose an image forming method.

An object of the present invention is to provide a resin-coated carrier having excellent charge-imparting property to a toner, a two-component developer having the resin-coated carrier and a toner, and an image forming method using the two-component developer. It is to propose.

An object of the present invention is to provide a resin-coated carrier capable of improving developability, a two-component developer having the resin-coated carrier and a toner, and an image forming method using the two-component developer. It is to propose.

An object of the present invention is to provide a resin-coated carrier effective for preventing carrier adhesion on a photoreceptor, a two-component developer having the resin-coated carrier and a toner, and a method for using the two-component developer. The purpose of the present invention is to propose an image forming method.

An object of the present invention is to provide a resin-coated carrier effective for preventing toner deterioration, a two-component developer having the resin-coated carrier and a toner, and an image forming method using the two-component developer. It is to propose.

[0023]

The above objects can be achieved by the following constitutions of the present invention.

According to the present invention, there is provided a resin-coated carrier comprising at least a carrier core and a resin coating layer, wherein the resin-coated carrier A has an average particle diameter of 25 to 55 μm and a resin-coated carrier particle B having a mesh size of 20 μm or less. 0.01 to 10% by mass, and 1000 / 4π (kA / m) of each of the resin-coated carriers A and B.
Σa, σb (Am ² / kg) satisfying the following relational expression: 30 ≦ σa ≦ 70 20 ≦ σb ≦ 60 0.2 ≦ σa−σb ≦ 20.

The present invention relates to a two-component developer comprising a carrier core, a resin-coated carrier having a resin for coating the surface of the carrier core, and a toner containing at least a binder resin and a colorant. The resin-coated carrier A has an average particle size of 25 to 55 μm and contains 0.01 to 10% by mass of resin-coated carrier particles B having a mesh size of 20 μm or less. The magnetization intensity σa, σb (Am ² / kg) at 4π (kA / m) satisfies the following relational expression: 30 ≦ σa ≦ 70 20 ≦ σb ≦ 60 0.2 ≦ σa−σb ≦ 20. The toner has a weight average particle diameter of 3 to 10
The present invention relates to a two-component developer having a μm.

According to the present invention, the electrostatic image carrier is charged by a charging means, the charged electrostatic image carrier is exposed to form an electrostatic image on the electrostatic image carrier, and the electrostatic image is formed into two components. A toner image is formed on an electrostatic image carrier by developing with a developing unit having a system developer, and the toner image on the electrostatic image carrier is transferred to a transfer material with or without an intermediate transfer member. In an image forming method in which a toner image on a transfer material is transferred and fixed by a heat and pressure fixing unit, the two-component developer has at least a toner and a resin-coated carrier, and the toner has a toner forming agent. Containing at least a resin and a coloring agent, and having a weight average particle size of 3 to 10
μm, and the resin-coated carrier A has an average particle size of 25 to 55 μm and a particle size of 20 μm by a mesh method.
0.01 to 10 μm or less of resin-coated carrier particles B
% Of the resin-coated carriers A and B, and the magnetization intensity σa at 1000 / 4π (kA / m) of each of the resin-coated carriers A and B.
σb (Am ² / kg) satisfies the following relational expression 30 ≦ σa ≦ 70 20 ≦ σb ≦ 60 0.2 ≦ σa−σb ≦ 20.

[0027]

BEST MODE FOR CARRYING OUT THE INVENTION As a result of intensive studies by the present inventors,
In a resin-coated carrier having a carrier core surface coated with a resin, the resin-coated carrier A has an average particle size of 25 to
Resin-coated carrier particles B having a size of 55 μm and 20 μm or less according to a mesh method are contained in an amount of 0.01 to 10% by mass.
Magnetization intensity σa, σb (Am at 4π (kA / m)
² / kg) satisfying the following relational expression: 30 ≦ σa ≦ 70 20 ≦ σb ≦ 60 0.2 ≦ σa−σb ≦ 20, it has been found that good image quality can be obtained over a long period of time.

The details will be described below.

We examined the spent property of the toner and the external additive to the carrier in the endurance. As for the physical properties of the carrier, those having a high magnetization and a small particle diameter are better in the spent property of the toner and the external additive. Is high. The reason for this is that when the magnetization is high, the compression of the developer in the developing device becomes strong and the spent property increases, and when the particle size is small, the chance of contact with the toner in the developing device increases and the spent It is thought that the nature increases.

On the other hand, in order to faithfully reproduce the latent image,
Since the toner having a smaller particle size must be uniformly charged, a carrier having a small particle size is required to some extent.
That is, satisfying the contradictory characteristics of the carrier can provide developing characteristics with high image quality and excellent durability.

From this viewpoint, we have made intensive studies and found that by controlling the content and the magnetic properties of the part having a particle size of 20 μm or less in the carrier particle size,
It has been found that the above problem can be solved. That is, the resin-coated carrier A used has an average particle size of 25 to 55 μm and contains 0.01 to 10% by mass of resin-coated carrier particles B having a mesh size of 20 μm or less. 1000 / 4π (kA
/ M) of the magnetization σa, σb (Am ² / kg)
Satisfy the following relational expression: 30 ≦ σa ≦ 70 20 ≦ σb ≦ 60 0.2 ≦ σa−σb ≦ 20.

The resin-coated carrier A has an average particle diameter of 25 to 55 μm so that the present invention can be suitably exhibited, and particularly preferably 30 to 50 μm. If it is larger than 55 μm, it is insufficient to uniformly and favorably charge the toner, which makes it difficult to faithfully reproduce a latent image, and causes fog and toner scattering. Conversely, if it is smaller than 25 μm, carrier adhesion to the latent image carrier becomes severe.

The resin-coated carrier A contains 0.01 μm or less of resin-coated carrier particles B having a size of 20 μm or less by a mesh method.
A content of 10 to 10% by mass is a configuration that allows the present invention to be suitably exhibited, and a content of 0.5 to 7% by mass is more preferable. If the amount is more than 10% by mass, even if the magnetic characteristics are controlled to such an extent that the charge distribution on the toner is not adversely affected, the suppression of carrier adhesion to the latent image carrier is deteriorated.
On the other hand, when the amount is less than 0.01% by mass, it is insufficient to give a uniform and good charge to the toner, and it becomes difficult to faithfully reproduce the latent image.

Each of the resin-coated carriers A and B
Magnetization intensity σa, σb at 00 / 4π (kA / m)
(Am ² / kg) satisfies the following relational expression 30 ≦ σa ≦ 70 20 ≦ σb ≦ 60 0.2 ≦ σa−σb ≦ 20, which is a configuration that makes the present invention suitable.

When σa is greater than 70, the carrier ears are long and coarse, making it difficult to provide a high-definition image. Further, the compression of the developer in the developing device is strengthened, the spent property of the carrier is increased, and the external additive of the toner is significantly deteriorated, which causes fog and toner scattering in the latter half of the durability. If σa is less than 30, carrier adhesion to the latent image carrier cannot be satisfactorily suppressed.

When σb is greater than 60, the carrier ears are long and coarse, making it difficult to provide a high-definition image. As a further adverse effect, since the carrier having a fine particle diameter of 20 μm or less, the spent property of the carrier is increased, and the external additive of the toner is remarkably deteriorated, causing fog and toner scattering in the latter half of the durability. When σb is smaller than 20, even if the content of 20 μm or less in the entire carrier is suppressed, it is not possible to favorably suppress the adhesion of the carrier to the latent image carrier.

If σa−σb is larger than 20, the difference in magnetic properties is too large, and the toner cannot be mixed well in the developing device. This causes a phenomenon such as toner scattering. Conversely, if σa−σb is smaller than 0.2, the object of the present invention cannot be achieved well.

In the present invention, the measurement of the mass%, particle size and magnetic properties of the carrier of not more than 20 μm by the mesh method was carried out by the following measuring methods.

<Calculation of mass% of 20 μm or less by carrier mesh method> A sieve having an aperture of 20 μm (# 635 mesh) and a tray are cleaned and weighed. The mass of the mesh at this time is defined as W1 (g). Next, a pan and an opening of 20 μm (# 635) were placed on an electromagnetic laboratory sieve shaker (Fritch Japan Analyset 3) from below.
Mesh) in the order of the sieve. 100g sample
Is weighed (W2 (g)), put in a sieve, covered, and fastened with a belt for setting. Set the timer to 5 minutes,
The amplitude is set to 2 in Amplitude.
After the shaking, the sieve mass (W3 (g)) having an aperture of 20 μm (# 635 mesh) is measured, and the abundance of the aperture of 20 μm or less is determined by the following equation.

Abundance (% by mass) of 20 μm or less = 100
− {(W3-W1) / W2} × 100

<Measurement Method of Carrier Particle Size> The carrier particle size is measured by a laser diffraction particle size distribution analyzer (Heros <H
The measurement was performed using ELOS>) under the conditions of a feed air pressure of 3 bar and a suction pressure of 0.1 bar. The average particle size of the carrier refers to a 50% particle size based on the volume of the carrier particles.

<Measurement Method of Carrier Magnetic Properties> The magnetic properties of the carriers were measured using an oscillating magnetic field type automatic magnetic property recording apparatus BHV-35 manufactured by Riken Denshi Co., Ltd. As the measurement conditions, the magnetic properties of the carrier powder were 1000 /
An external magnetic field of 4π (kA / m) was created, and the intensity of magnetization at that time was determined. The carrier is packed in a cylindrical plastic container so that the carrier particles are tightly packed so that the carrier particles do not move, the magnetization moment is measured in this state, and the actual mass when the sample is placed is measured. And the intensity of magnetization (Am ² / kg).

When measuring the physical properties of the carrier from the developer, the above measurement is performed after the developer is washed with ion-exchanged water containing 1% of contaminone N (surfactant) to separate the toner and the carrier.

In the present invention, the specific resistance of the carrier is 1
It is preferably from × 10 ⁸ to 1 × 10 ¹⁶ Ω · cm,
More preferably, it is 1 × 10 ⁹ to 1 × 10 ¹⁵ Ω · cm.

When the specific resistance of the carrier is less than 1 × 10 ⁸ Ω · cm, the developing bias is injected through the carrier, and the carrier is easily attached to the surface of the photoreceptor. As a result, the photoreceptor is easily damaged, or the image is easily transferred to the paper, thereby easily causing an image defect. Further, the developing bias may leak through the carrier and disturb the electrostatic latent image drawn on the photosensitive drum.

When the specific resistance of the carrier exceeds 1 × 10 ¹⁶ Ω · cm, a sharp edge-enhanced image is easily formed, and furthermore, the charge on the surface of the carrier hardly leaks.
In some cases, the image density may decrease due to the charge-up phenomenon, and fogging and scattering may occur due to the inability to apply the charge to the newly replenished toner.
Further, the toner may be charged with a substance such as the inner wall of the developing device, and the charge amount of the toner which should be applied may become non-uniform. In addition, image defects such as electrostatic adhesion of external additives are likely to occur.

The specific resistance of the carrier was measured using a powder insulation resistance measuring instrument manufactured by Vacuum Riko Co., Ltd.
Measurement conditions, 23 ° C., put left carrier for 24 hours or more 60% under the conditions in the measuring cell diameter ^{20mm (0.283cm 2), 11.8kPa (} 120g / cm 2)
, A thickness of 2 mm, and an applied voltage of 50 mm.
It was measured at 0V.

As described above, iron powder, ferrite, or a magnetic material-dispersed resin carrier is used as the carrier core particles in the present invention, but ferrite or a magnetic material-dispersed resin carrier is preferable. Even if iron powder carrier is coated with resin,
Since the specific resistance of the core is low, the charge of the electrostatic charge image leaks through the carrier and disturbs the electrostatic charge image, often causing image defects.

Taking into account the object of the present invention to provide a carrier having low magnetic properties for favorably suppressing the developer deterioration during durability, a magnetic material-dispersed resin carrier is preferable.

In general, a ferrite carrier has a large saturation magnetization, so that a magnetic brush becomes rigid. Therefore, deterioration of a developer such as carrier spent or deterioration of an external additive of a toner is liable to increase, and a magnetic image is formed on a toner image. In some cases, a brush texture may occur.

In other words, a magnetic material-dispersed resin carrier in which magnetic fine particles are dispersed in a binder resin is a preferable mode for favorably controlling the magnetic characteristics and resistance of the carrier of the present invention. Compared with ferrite carriers, magnetic material-dispersed resin carriers have relatively high specific resistance, low saturation magnetization, and low true specific gravity, so the magnetic brush of the carrier does not become rigid, and deterioration of the developer is suppressed. A good toner image without texture can be formed.

In the present invention, a preferred embodiment in the case of using a magnetic material-dispersed resin carrier core will be described. Examples of the metal compound particles to be used include magnetite or ferrite having magnetism represented by the following formula (1) or (2). MO · Fe ₂ O ₃ ··· (1) M · Fe ₂ O ₄ ··· (2) (in the formula, M represents a trivalent, divalent or monovalent metal ion.)

As M, Mg, Al, Si, Ca, S
c, Ti, V, Cr, Mn, Fe, Co, Ni, Cu,
Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, B
a, Pb, and Li, which can be used alone or in combination.

Specific examples of the magnetic compound particles having magnetism include magnetite and Zn-Fe.
Ferrite, Mn-Zn-Fe ferrite, Ni-
Zn-Fe ferrite, Mn-Mg-Fe ferrite, Ca-Mn-Fe ferrite, Ca-Mg-Fe
Ferrite, Li-Fe ferrite and Cu-Zn
And iron-based oxides such as Fe-based ferrite.

Further, in the present invention, as the metal compound particles used for the carrier core, a mixture of the above magnetic metal compound and the following nonmagnetic metal compound may be used.

As the non-magnetic metal compound, for example, A
l ₂ O ₃ , SiO ₂ , CaO, TiO ₂ , V ₂ O ₅ , CrO,
MnO ₂ , α-Fe ₂ O ₃ , CoO, NiO, CuO, Z
nO, SrO, include Y ₂ O ₃ and ZrO _2. In this case, one kind of metal compound can be used, but it is particularly preferable to use a mixture of at least two or more kinds of metal compounds. In that case, it is more preferable to use particles having similar specific gravities and shapes in order to increase the adhesion to the binder resin and the strength of the carrier core particles.

Specific examples of the combination include magnetite and hematite, magnetite and γ-Fe
₂ O ₃ , magnetite and SiO ₂ , magnetite and Al ₂ O
_3, magnetite and TiO _2, magnetite and Ca-Mn
-Fe-based ferrite, magnetite and Ca-MgFe-based ferrite can be preferably used. Among them, a combination of magnetite and hematite can be particularly preferably used.

In the case where the above-mentioned magnetic metal compound is used alone or in combination with a non-magnetic metal compound, the number average particle diameter of the magnetic metal compound is determined by the number average particle diameter of the carrier core. It is preferably 0.02 to 2 μm, and more preferably 0.05 to 1 μm.

If the number average particle size of the magnetic metal compound is less than 0.02 μm, it becomes difficult to obtain favorable magnetic properties. Number average particle size of magnetic metal compound is 2μ
When m exceeds m, it is difficult to obtain a carrier having a high strength and a preferable particle diameter due to uneven granulation.

When a mixture of a magnetic metal compound and a nonmagnetic compound is used, the number average particle size of the nonmagnetic metal compound is preferably 0.05 to 5 μm, more preferably 0.1 to 3 μm. Good to be. In this case, the number average particle diameter (average particle diameter ra) of the metal compound having magnetism,
The particle size ratio (rb / ra) to the number average particle size (average particle size rb) of the nonmagnetic metal compound is preferably 1.0 to 5.0.
0, more preferably 1.2 to 5.0.

The number average particle diameter of the non-magnetic metal compound is 0.5.
When the thickness is less than 05 μm, favorable resistance cannot be obtained, and the carrier tends to adhere. When the number average particle size of the nonmagnetic metal compound exceeds 5 μm, it is difficult to obtain a carrier having a preferable particle size with high strength due to non-uniform granulation.

Further, when rb / ra is less than 1.0, ferromagnetic metal compound particles having low specific resistance tend to emerge on the surface, it is difficult to increase the specific resistance of the carrier core, and the effect of preventing the carrier from adhering. Is difficult to obtain. rb / r
When a exceeds 5, the strength of the carrier is apt to decrease, and the carrier is easily broken.

The number average particle diameter of the metal oxide was measured by a transmission electron microscope H-800 manufactured by Hitachi, Ltd.
Using a photographic image magnified 00 to 20000 times, 300 or more particles having a particle size of 0.01 μm or more were randomly extracted, and an image processing analysis device Luzex3 manufactured by Nireco Co., Ltd. was used.
Was measured as the metal oxide particle size with the Feret diameter in the horizontal direction, and averaged to calculate the number average particle size.

The specific resistance of the metal compound dispersed in the binder resin is such that the specific resistance of the magnetic metal compound particles is 1 × 1.
It is preferably in the range of 0 ³ Ω · cm or more. In particular, when a magnetic metal compound and a nonmagnetic compound are used in combination, the specific resistance of the magnetic metal compound particles is 1
× 10 ³ Ω · cm or more is preferable, and the other nonmagnetic metal compound particles preferably have higher specific resistance than the magnetic metal compound particles, and are preferably used.
The specific resistance of the nonmagnetic metal compound used in the present invention is 1 × 10
^It is preferably ⁸ Ω · cm or more, more preferably 1 × 10 ¹⁰ Ω · cm or more.

The specific resistance of the magnetic metal compound particles is 1
When the content is less than × 10 ³ Ω · cm, it is difficult to obtain a desired high specific resistance even if the content is reduced, which leads to charge injection, image quality deterioration and carrier adhesion. When a mixture of a magnetic metal compound and a nonmagnetic compound is used, the specific resistance of the nonmagnetic metal compound is 1 × 10 ⁸ Ω · cm.
If it is less than the specific resistance of the magnetic carrier core becomes low,
It becomes difficult to obtain the effects of the present invention.

In the present invention, the method of measuring the specific resistance of the magnetic metal compound and the nonmagnetic metal compound is performed according to the method of measuring the specific resistance of the carrier particles.

In the carrier core of the present invention, the content of the metal compound is preferably 80 to the carrier core.
The content is preferably up to 99% by mass.

When the content of the metal compound is less than 80% by mass, the chargeability tends to be unstable, and the carrier is charged particularly in a low-temperature and low-humidity environment, and the residual charge tends to remain. And an external additive easily adhere to the surface of the carrier particles, and a proper specific gravity cannot be obtained. When the content of the metal compound exceeds 99% by mass, the strength of the carrier decreases, and problems such as cracking of the carrier due to durability tend to occur.

As a preferred form of the magnetic material-dispersed resin carrier, in a carrier core containing a mixture of a magnetic metal compound and a non-magnetic compound, the content of the magnetic metal compound in the entire metal compound contained Is preferably 50 to 95% by mass, more preferably 55 to 95% by mass.
It is preferably 95% by mass.

When the content of the metal compound having magnetism in the whole metal compound is less than 50% by mass, the resistance of the core is improved, but the magnetic force as a carrier is reduced, and the adhesion of the carrier is reduced. May be invited. If the content of the magnetic metal compound in the whole metal compound exceeds 95% by mass, depending on the specific resistance of the magnetic metal compound, it may not be possible to achieve a more desirable high core resistance.

The binder resin of the carrier core particles used in the magnetic material-dispersed resin carrier is a thermosetting resin,
Part or all of the resin is preferably three-dimensionally crosslinked. Thereby, the dispersed metal compound particles can be firmly bound, so that the strength of the carrier core can be increased, the metal compound is less likely to be detached even when copying a large number of sheets, and the coating resin can be further improved. Can be coated.

The method for obtaining the magnetic material-dispersed carrier core is not particularly limited to the method described below, but in the present invention, a solution in which the monomer and the solvent are uniformly dispersed or dissolved is used. From the inside, the production method of the polymerization method of generating particles by polymerizing the monomer, particularly, by subjecting the metal oxide dispersed in the carrier core particles to lipophilic treatment, a sharp particle size distribution, fine powder A method of obtaining a small resin-coated carrier core is suitably used.

In the present invention, in the case of a carrier used in combination with a small particle size toner having a weight average particle size of 3 to 10 μm in order to achieve high image quality, the carrier particle size is also small according to the particle size of the toner. It is preferable to reduce the particle size, and the above-described production method is particularly preferable because even if the carrier particle size is reduced, a carrier having a small amount of fine powder can be produced regardless of the average particle size.

As the monomer used for the binder resin of the carrier core particles, a radical polymerizable monomer can be used. For example, styrene; o-methylstyrene,
Styrene derivatives such as m-methylstyrene, p-methoxystyrene, p-ethylstyrene, p-tert-butylstyrene; acrylic acid, methyl acrylate, ethyl acrylate, n-butyl acrylate, n-propyl acrylate, acrylic Isobutyl acid, octyl acrylate,
Dodecyl acrylate, 2-ethylhexyl acrylate,
Stearyl acrylate, 2-chloroethyl acrylate,
Acrylates such as phenyl acrylate; methacrylic acid, methyl methacrylate, ethyl methacrylate,
N-propyl methacrylate, n-butyl methacrylate,
Isobutyl methacrylate, n-octyl methacrylate,
Dodecyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, phenyl methacrylate,
Methacrylic esters such as dimethylaminomethyl methacrylate, diethylaminoethyl methacrylate, and benzyl methacrylate; 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate; acrylonitrile, methacrylonitrile, acrylamide; methyl vinyl ether, ethyl vinyl ether, propyl vinyl ether, vinyl ethers such as n-butyl ether, isobutyl ether, β-chloroethyl vinyl ether, phenyl vinyl ether, p-methylphenyl ether, p-chlorophenyl ether, p-bromophenyl ether, p-nitrophenyl vinyl ether and p-methoxyphenyl vinyl ether; butadiene And diene compounds such as

These monomers can be used alone or as a mixture, and a suitable polymer composition that can obtain preferable characteristics can be selected.

As described above, the binder resin of the carrier core particles is preferably three-dimensionally cross-linked. However, as a cross-linking agent for three-dimensionally cross-linking the binder resin,
It is preferable to use a crosslinking agent having two or more polymerizable double bonds per molecule. Examples of such a crosslinking agent include aromatic divinyl compounds such as divinylbenzene and divinylnaphthalene; ethylene glycol diacrylate, ethylene glycol dimethacrylate, triethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, and 1,3-butylene glycol. Dimethacrylate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, 1,4-butanediol diacrylate, neopentyl glycol diacrylate, 1,6-hexanediol diacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, penta Erythritol dimethacrylate, pentaerythritol tetramethacrylate, glycerol Alkoxy dimethacrylate, N, N-divinyl aniline, divinyl ether, and a divinyl sulfide and divinyl sulfone. These may be used by mixing two or more kinds as appropriate. The cross-linking agent can be previously mixed with the polymerizable mixture, or can be added as needed during the polymerization.

Other monomers for the binder resin of the carrier core particles include bisphenols and epichlorohydrin as starting materials for the epoxy resin; phenols and aldehydes of the phenolic resin; ureas and aldehydes of the urea resin; melamine and aldehydes. No.

The most preferred binder resin is a phenolic resin. The starting materials are phenol, m
-Phenol compounds such as cresol, 3,5-xylenol, p-alkylphenol, resorcil, p-tert-butylphenol; and aldehyde compounds such as formalin, paraformaldehyde and furfural. Particularly, a combination of phenol and formalin is preferred.

When these phenol resins or melamine resins are used, a basic catalyst can be used as a curing catalyst. As the basic catalyst, various catalysts used in the production of ordinary resol resins can be used. Specific examples include amines such as aqueous ammonia, hexamethylenetetramine, diethyltriamine and polyethyleneimine.

In the present invention, the metal compound contained in the carrier core is subjected to lipophilic treatment to sharpen the particle size distribution of the magnetic carrier particles and prevent the metal compound particles from being detached from the carrier. Preferred above.
In the case of forming carrier core particles in which a lipophilic metal compound is dispersed, particles insoluble in a solution are generated at the same time as the polymerization reaction proceeds from a liquid in which a monomer and a solvent are uniformly dispersed or dissolved. At that time, it is considered that the metal oxide has an effect of uniformly and densely taking in the inside of the particles and an effect of preventing aggregation of the particles and sharpening the particle size distribution. Furthermore, when a metal compound subjected to lipophilic treatment is used, there is no need to use a suspension stabilizer such as calcium fluoride, and the suspension stabilizer remains on the carrier surface, thereby impairing the chargeability. It is possible to prevent the nonuniformity of the coating resin and the inhibition of the reaction when coating with a reactive resin such as a silicone resin.

In the lipophilic treatment, an organic compound having one or more functional groups selected from an epoxy group, an amino group and a mercapto group, or a lipophilic treatment agent which is a mixture thereof is used. Is preferred. In particular, an epoxy group is preferably used in order to obtain a carrier having a stable charging ability.

The magnetic metal oxide particles are preferably treated with 0.1 to 10 parts by mass, more preferably 0.2 to 6 parts by mass, based on 100 parts by mass of the magnetic metal oxide particles. Is preferred in order to increase the lipophilicity and hydrophobicity of the magnetic metal oxide particles.

Examples of the lipophilic treatment agent having an epoxy group include γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropyltrimethoxysilane, β
-(3,4-epoxycyclohexyl) trimethoxysilane, epichlorohydrin, glycidol and styrene-glycidyl (meth) acrylate copolymer.

Examples of the lipophilic treatment agent having an amino group include γ-aminopropyltrimethoxysilane, γ-aminopropylmethoxydiethoxysilane, γ-aminopropyltriethoxysilane, and N-β (aminoethyl)-
γ-aminopropyltrimethoxysilane, N-β (aminoethyl) -γ-aminopropylmethyldimethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, ethylenediamine, ethylenetriamine, styrene-dimethylamino (meth) acrylate Ethyl copolymer and isopropyl tri (N-aminoethyl) titanate are used.

As the lipophilic treatment agent having a mercapto group, for example, mercaptoethanol, mercaptopropionic acid and γ-mercaptopropyltrimethoxysilane are used.

The resin for coating the surface of the carrier core is not particularly limited. Specifically, for example, polystyrene, acrylic resin such as styrene-acrylic copolymer, vinyl chloride, vinyl acetate, polyvinylidene fluoride resin, fluorocarbon resin, perfluorocarbon resin, solvent-soluble perfluorocarbon resin, polyvinyl alcohol, polyvinyl acetal, Polyvinyl pyrrolidone, petroleum resin, cellulose, cellulose derivative, novolak resin, low molecular weight polyethylene, saturated alkyl polyester resin, aromatic polyester resin, polyamide resin, polyacetal resin, polycarbonate resin, polyether sulfone resin, polysulfone resin, polyphenylene sulfide resin, poly Ether ketone resin, phenol resin, modified phenol resin, maleic resin, alkyd resin, epoxy resin, acrylic resin, anhydrous male Unsaturated polyester obtained by polycondensation of emissions and terephthalic acid and polyhydric alcohol, urea resins, melamine resins,
Urea-melamine resin, xylene resin, toluene resin, guanamine resin, melamine-guanamine resin, acetoguanamine resin, gliptal resin, furan resin, silicone resin, polyimide resin, polyamideimide resin, polyetherimide resin and polyurethane resin. it can.

Among them, silicone resins are preferably used from the viewpoint of adhesion to the core and prevention of spent. The silicone resin can be used alone, but is preferably used in combination with a coupling agent in order to increase the strength of the coating layer and control the charging to a preferable level. Further, the above-mentioned coupling agent is preferably used as a so-called primer agent, a part of which is treated on the carrier core surface before coating the resin, and the subsequent coating layer has a covalent bond. , Can be formed with higher adhesion.

As the coupling agent, aminosilane is preferably used. As a result, a positively chargeable amino group can be introduced into the carrier surface, and the toner can be favorably imparted with negative charge characteristics. Furthermore, in the case of a magnetic material-dispersed resin carrier, the presence of the amino group activates both the lipophilic treatment agent preferably treated with the metal compound and the silicone resin, so that the silicone resin adheres to the carrier core. By further enhancing the properties and simultaneously promoting the curing of the resin, a stronger coating layer can be formed.

During the coating treatment of the coating layer, the coating is preferably performed under a reduced pressure at a temperature of 30 to 80 ° C.

The reason is not clear, but it is expected to be described below.

(1) An appropriate reaction proceeds in the coating step, and the coating material is uniformly and smoothly coated on the carrier core surface.

(2) In the baking step, a low-temperature treatment at a temperature of at least 160 ° C. becomes possible, so that excessive crosslinking of the resin is prevented, and the durability of the coating layer is enhanced.

The toner for forming the two-component developer in combination with the above-described carrier contains at least a binder resin for toner and a colorant, and may have a weight average particle diameter of 3 to 10 μm. good. When the weight average particle size of the toner is less than 3 μm, problems such as charge-up are likely to occur particularly in a low-humidity environment, and the effect of using the carrier of the present invention is not sufficiently obtained. Also has low handling properties as a powder. If the weight average particle diameter of the toner exceeds 10 μm, problems such as toner scattering and fogging are likely to occur particularly under high temperature and high humidity, and the effect of using the carrier of the present invention cannot be sufficiently obtained. Further, since one toner particle becomes large, it is difficult to obtain a high-resolution and dense image. Further, when electrostatic transfer is performed, toner scattering is likely to occur.

The measurement of the average particle size and the particle size distribution of the toner is as follows.
It went as follows.

0.1 to 5 ml of a surfactant (alkylbenzene sulfonate) is added to 100 to 150 ml of the electrolyte solution.
And 2 to 20 mg of a measurement sample is added thereto. The electrolytic solution in which the sample is suspended is subjected to dispersion treatment for 1 to 3 minutes using an ultrasonic disperser, and the volume is measured using a Coulter Counter Multisizer (manufactured by Coulter) using an aperture appropriately adjusted to a toner size such as 17 μm or 100 μm. And a particle size distribution of 0.3 to 40 μm is measured. The number average particle diameter and the weight average particle diameter measured under these conditions are obtained by computer processing, and the cumulative ratio of the number average particle diameter smaller than 1/2 times the diameter cumulative distribution is calculated from the number-based particle diameter distribution,
A cumulative value equal to or smaller than the 1/2 diameter cumulative distribution is obtained. Similarly, a cumulative ratio equal to or larger than the double diameter cumulative distribution of the weight average particle diameter is calculated from the volume-based particle size distribution, and a cumulative value equal to or larger than the double diameter cumulative distribution is obtained.

The toner to be combined with the carrier of the present invention is particularly effective when at least a polyester resin is contained as a binder resin of the toner.
That is, the polyester resin is excellent in fixing property and color mixing property, and is particularly preferably used as a binder resin for a color toner. However, on the other hand, the polyester resin has a strong negative charging ability, and has a problem that the charging tends to be excessive particularly in a low humidity environment. I was However, when used in combination with the carrier of the present invention, it is possible to suppress excessive charging of the toner and obtain excellent developability.

Other binder resins for the toner include polystyrene; polymer compounds obtained from styrene derivatives such as poly-p-chlorostyrene and polyvinyl toluene;
Styrene-p-chlorostyrene copolymer, styrene-vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, styrene-acrylate copolymer, styrene-methacrylate copolymer, styrene-
Styrene copolymers such as methyl chloromethacrylate copolymer, styrene-acrylonitrile copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-acrylonitrile-indene copolymer Polymer; polyvinyl chloride, phenolic resin, modified phenolic resin, maleic resin, acrylic resin, methacrylic resin, polyvinyl acetate,
Silicone resin; Polyester resin having a monomer selected from aliphatic polyhydric alcohol, aliphatic dicarboxylic acid, aromatic dicarboxylic acid, aromatic dialcohols and diphenols as a structural unit; polyurethane resin, polyamide resin, polyvinyl Butyral, terpene resin, cumarone indene resin, petroleum resin.

Further, the toner has a shape factor SF-1 of 10
More preferably, it is 0 to 120.

In a toner having a shape factor SF-1 of more than 120, the change in the fluidity of the developer tends to be large.
In a long-term durability test, the charge amount easily changes. S
The toner having an F-1 in the range of 100 to 120 has high transfer efficiency on paper, and can provide the same density as the conventional toner even if the amount of toner put on the photoreceptor is small.
It is also advantageous in terms of cost. Further, since the toner easily rolls on the carrier and the packing density of the developer is easily increased, there are many chances of contact with the carrier, and it is easy to always maintain stable charge.

The shape factor SF-1 of the toner is obtained by randomly sampling 300 or more toner images (magnification: 300 times) using FE-SEM (S-800) manufactured by Hitachi, Ltd. Then, the image was introduced into an image analysis device (Luzex3) manufactured by Nireco Co., Ltd. and analyzed, and the value calculated by the following equation was defined as the shape factor SF-1 of the toner.

[0101]

(Equation 1) (Where MXLNG indicates the maximum diameter of the toner, and AREA
Indicates the projected area of the toner. )

A toner having a core / shell structure in which a core is formed of a substance having a low softening point is also preferably used. Since the toner uses a low softening point substance, it is advantageous for low-temperature fixing, but is in a direction disadvantageous to heat generation due to mechanical share, and may cause toner spent in a developing device. The use of the carrier of the present invention eliminates that concern.

As a method of encapsulating the low softening point substance in the toner particles, the polarity of the material in the aqueous medium is set to be smaller for the low softening point substance than for the main monomer, and a small amount of the larger polar substance is used. By adding a resin or a monomer, toner particles having a so-called core / shell structure in which a low softening point substance is coated with an outer shell resin can be obtained.

The particle size distribution and the particle size of the toner can be controlled by changing the type and amount of the hardly water-soluble inorganic salt or dispersant to be used as a protective colloid, or by using mechanical device conditions such as a roller. A predetermined toner can be obtained by controlling the peripheral speed, the number of passes, stirring conditions such as the shape of the stirring blade, the shape of the container, or the solid concentration in the aqueous medium.

As the outer shell resin of the toner, styrene-
(Meth) acrylic copolymers, polyester resins, epoxy resins, styrene-butadiene copolymers may be mentioned.

In a method of directly obtaining toner particles by a polymerization method, those monomers are preferably used. Specifically, styrene; styrene monomers such as o (m-, p-)-methylstyrene and m (p-)-ethylstyrene; methyl (meth) acrylate, ethyl (meth) acrylate, (meth) ) Propyl acrylate, butyl (meth) acrylate, octyl (meth) acrylate, dodecyl (meth) acrylate, stearyl (meth) acrylate, behenyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, ( (Meth) acrylate monomers such as dimethylaminoethyl (meth) acrylate and diethylaminoethyl (meth) acrylate; butadiene, isoprene, cyclohexene, (meth) acrylonitrile,
An ene monomer such as acrylamide is preferably used.

In these toners, it is preferable to use at least silica fine particles and / or titanium oxide fine particles as an external additive, since the fluidity can be favorably imparted to the developer and the life of the developer is improved. Further, by using these fine powders, a developer having less environmental fluctuation can be obtained.

Other external additives include metal oxide fine powder (aluminum oxide, strontium titanate, cerium oxide, magnesium oxide, chromium oxide, tin oxide, zinc oxide, etc.) and nitride fine powder (silicon nitride, etc.) , Carbide fine powder (silicon carbide, etc.), metal salt fine powder (calcium sulfate, barium sulfate, calcium carbonate, etc.), fatty acid metal salt fine powder (zinc stearate, calcium stearate, etc.), carbon black, resin fine powder (polytetra Fluoroethylene, polyvinylidene fluoride, polymethyl methacrylate, polystyrene, silicone resin, etc.) are preferred. Even if these external additives are used alone,
Also, a plurality of them may be used in combination. It is more preferable that the above-mentioned external additives including the silica fine powder have been subjected to a hydrophobic treatment.

The above-mentioned external additive has a number average particle size of 0.2.
It is preferably not more than μm. Number average particle size is 0.2
If it exceeds μm, the fluidity will decrease and the image quality will deteriorate during development and transfer.

The external additive is preferably used in an amount of 0.01 to 10 parts by mass, more preferably 0.05 to 5 parts by mass, based on 100 parts by mass of the toner particles.

[0111] the external additive has a specific surface area by nitrogen adsorption according to the BET method is preferably 30 m ² / g or more, more preferably is suitable in the range of 50 to 400 m ² / g.

The mixing process of the toner particles and the external additive can be performed by using a mixer such as a Henschel mixer.

In the present invention, examples of the colorant used in the toner include the following.

Examples of yellow colorants include condensed azo compounds, isoindolinone compounds, anthraquinone compounds,
Compounds represented by azo metal complexes, methine compounds and allylamide compounds are used. Specifically, C.I. I. Pigment Yellow 12, 13, 14, 15, 17, 6
2, 74, 83, 93, 94, 95, 109, 110,
111, 128, 129, 147, and 168 can be suitably used.

Examples of the magenta colorant include condensed azo compounds, diketopyrrolopyrrole compounds, anthraquinones, quinacridone compounds, basic dye lake compounds, naphthol compounds, benzimidazolone compounds, thioindigo compounds, and perylene compounds. Specifically, C.I.
I. Pigment Red 2, 3, 5, 6, 7, 23, 4
8: 2, 48: 3, 48: 4, 57: 1, 81: 1, 1
44, 146, 166, 169, 177, 184, 18
5, 202, 206, 220, 221, 254 can be suitably used.

Examples of the cyan coloring agent include copper phthalocyanine compounds and derivatives thereof, anthraquinone compounds, and basic dye lake compounds. Specifically, C.I. I. Pigment Blue 1, 7, 15, 15: 1, 15: 2, 1
5: 3, 15: 4, 60, 62, 66 can be suitably used.

These colorants can be used alone or as a mixture or in the form of a solid solution.

Examples of the black colorant include carbon black and the above-mentioned yellow / magenta / cyan colorants which are toned to black.

In the case of a color toner, the hue angle,
The selection is made in consideration of saturation, lightness, weather resistance, OHP transparency, and dispersibility in toner. The content of the colorant is preferably 1 to 20 parts by mass based on 100 parts by mass of the binder resin for toner.

Examples of the charge control agent used in the toner include:
Known ones can be used. In the case of a color toner, a charge control agent which is colorless or light-colored and has a high toner charging speed and can stably maintain a constant charge amount is particularly preferable. Further, in the present invention, when a toner is produced by a polymerization method, a charge control agent having no polymerization inhibition and having no soluble matter in an aqueous medium is particularly preferable.

Further, the toner used in the present developer was 280-35 when the extract was extracted with 0.1 mol / l sodium hydroxide and the absorbance was measured.
It is preferable to have at least one peak in the range of 0 nm. This peak is derived from oxycarboxylic acid, which is preferably used in the toner for the purpose of controlling charging, accelerating the curing of the binder resin and increasing the fluidity, and the like. Such an oxycarboxylic acid can impart high chargeability to the toner. However, depending on the binder resin, other materials, and the method of manufacturing the toner, an extreme decrease in the charge amount under high humidity and an increase in the charge of the toner under low humidity may be observed. Was. However, by using the carrier of the present invention, it has become possible to effectively suppress the toner charge-up phenomenon particularly under low humidity.

The amount of sodium hydroxide extracted was 0.1 mol
1 g of the toner is weighed and added to 50 ml of an aqueous solution of 1 / liter sodium hydroxide, and then 50 rpm using a stirrer.
And uniformly disperse. After the dispersion treatment for 3 hours, the membrane filter (pore size: 0.45 μm)
m), and the absorbance of the obtained filtrate was measured.

Examples of the negative charge control agent include metal compounds of salicylic acid, dialkylsalicylic acid, naphthoic acid, dicarboxylic acid and derivatives thereof; high molecular weight compounds having sulfonic acid or carboxylic acid in the side chain; boron compounds; A urea compound; a silicon compound; and carricks arene are preferably used. As positive charge control agents,
For example, a quaternary ammonium salt; a polymer compound having the quaternary ammonium salt in a side chain; a guanidine compound; and an imidazole compound are preferably used. The content of the charge control agent is 0.5 to 10 with respect to 100 parts by mass of the binder resin.
It is preferably in parts by mass. However, the addition of the charge control agent to the toner particles is not essential.

The toner particles can be produced by melt-kneading a binder resin, a colorant, and other internal additives, cooling the kneaded material, pulverizing and classifying, and directly using a suspension polymerization method. A method for producing particles, a method for dispersion polymerization in which toner particles are directly produced using an aqueous organic solvent in which the obtained polymer is insoluble in a monomer, or a method in which polymerization is carried out directly in the presence of a water-soluble polar polymerization initiator. A method of producing toner particles using an emulsion polymerization method typified by a soap-free polymerization method for producing toner particles is exemplified.

In the present invention, the shape factor SF of the toner
-1 can be controlled to 100 to 120, and a method of producing toner particles by a suspension polymerization method that can relatively easily obtain a fine particle toner having a sharp particle size distribution and a weight average particle size of 3 to 10 μm is preferable.

When toner particles are produced by the polymerization method, 2,2′-azohis- (2,2
4-dimethylvaleronitrile), 2,2'-azobisisobutyronitrile, 1,1'-azobis (cyclohexane-1-carbonitrile, 2,2'-azobis-4-methoxy-2,4-dimethylvalero Azo polymerization initiators such as nitrile and azobisisobutyronitrile; benzoyl peroxide, methyl ethyl ketone peroxide, diisopropyl peroxycarbonate, cumene hydroperoxide, 2,4-dichlorobenzoyl peroxide;
A peroxide-based polymerization initiator such as lauroyl peroxide is used.

The amount of the polymerization initiator varies depending on the desired degree of polymerization.
0 mass% is added and used. The type of the polymerization initiator varies slightly depending on the polymerization method, but is used alone or in combination with reference to the 10-hour half-life temperature. Known crosslinking agents, chain transfer agents, polymerization inhibitors and the like for controlling the degree of polymerization can be further added and used.

When suspension polymerization is used as a method for producing a toner, tricalcium phosphate, magnesium phosphate, aluminum phosphate, zinc phosphate, calcium carbonate, carbonate Examples include magnesium, calcium hydroxide, magnesium hydroxide, aluminum hydroxide, calcium metasilicate, calcium sulfate, barium sulfate, bentonite, silica, and alumina. Examples of the organic compound include polyvinyl alcohol, gelatin, methylcellulose, methylhydroxypropylcellulose, ethylcellulose, sodium salts of carboxymethylcellulose, starch and the like. These are used by being dispersed in an aqueous phase. These dispersants are used in an amount of 0.2 to 100 parts by mass of the polymerizable monomer.
It is preferred to use 10.0 parts by weight.

As these dispersants, commercially available ones may be used as they are, but in order to obtain finely dispersed particles having a uniform particle size, the inorganic compound may be produced under high-speed stirring in a dispersion medium. I can do it. For example, in the case of tricalcium phosphate, a dispersant suitable for a suspension polymerization method can be obtained by mixing an aqueous solution of sodium phosphate and an aqueous solution of calcium chloride under high-speed stirring. Further, 0.001 to 0.1 parts by mass of a surfactant for miniaturization of these dispersants may be used in combination. Specifically, commercially available nonionic, anionic or cationic surfactants can be used, for example, sodium dodecyl sulfate, sodium tetradecyl sulfate, sodium pentadecyl sulfate, sodium octyl sulfate, sodium oleate, sodium laurate, potassium stearate. Calcium oleate is preferably used.

In the case where the direct polymerization method is used for the production method of the toner, it is possible to specifically produce the toner by the following production method. A monomer composition obtained by adding a release agent, a colorant, a charge control agent, a polymerization initiator, and other additives made of a low-softening substance to a monomer and uniformly dissolving or dispersing the mixture using a homogenizer, an ultrasonic disperser, or the like. The product is dispersed in an aqueous phase containing a dispersion stabilizer using a conventional stirrer, homomixer, homogenizer, or the like. Preferably, the stirring speed and the time are adjusted so that the droplets composed of the monomer composition have a desired size of the toner particles, and the droplets are granulated. Thereafter, by the action of the dispersion stabilizer, the stirring may be performed to such an extent that the particle state is maintained and the sedimentation of the particles is prevented. The polymerization temperature is 40 ° C. or higher, generally 50 to 9
The polymerization is carried out at a temperature of 0 ° C. The temperature may be raised in the latter half of the polymerization reaction, and further, for the purpose of improving the durability properties, in order to remove unreacted polymerizable monomers and by-products, in the latter half of the reaction or after completion of the reaction, a part of the aqueous medium is distilled You may leave. After the reaction, the generated toner particles are collected by washing and filtration, and dried. In the suspension polymerization method, the monomer system 1 is usually used.
It is preferable to use 300 to 3000 parts by mass of water as a dispersion medium with respect to 00 parts by mass.

The toner may be classified to control the particle size distribution, and a multi-segment classifier utilizing inertial force is preferably used as the method. By using this apparatus, a toner having a preferable particle size distribution in the present invention can be efficiently produced.

Next, the image forming method of the present invention will be described.

In the image forming method of the present invention, the electrostatic image carrier is charged by a charging means, and the charged electrostatic image carrier is exposed to form an electrostatic image on the electrostatic image carrier. A toner image is formed on an electrostatic image carrier by developing the image with a developing unit having a two-component developer, and the toner image on the electrostatic image carrier is passed through an intermediate transfer member, or
The toner image is transferred onto the transfer material without any intervention, and the toner image on the transfer material is fixed by the heat and pressure fixing unit.

Hereinafter, the image forming method of the present invention will be described with reference to the accompanying drawings.

In FIG. 1, a magnetic brush made of magnetic particles 23 is formed on the surface of the transport sleeve 22 by the magnetic force of the magnet roller 21, and this magnetic brush contacts the surface of the electrostatic image carrier (photosensitive drum) 1. Then, the photosensitive drum 1 is charged. A charging bias is applied to the transport sleeve 22 by a bias applying unit (not shown). By irradiating the charged photosensitive drum 1 with laser light 24 by an exposure device (not shown), a digital electrostatic charge image is formed. The electrostatic charge image formed on the photosensitive drum 1 includes a magnet roller 12 and a two-component developer 19 carried on a developing sleeve 11 to which a developing bias is applied by a bias applying device (not shown). Is developed by the toner 19a.

The developing device 4 as a developing means includes a partition 17
The developer chamber R₁, Stirring chamber R_TwoAre divided into
Image agent conveying screws 13 and 14 are provided. Stirring
Room R _TwoAbove the toner containing the supply toner 18
Storage room R_ThreeIs installed in the storage room R_Three20 at the bottom of
Is provided.

The developer transport screw 13 rotates to transport the two-component developer 19 in the developer chamber R1 in _one direction along the longitudinal direction of the developing sleeve 11 while stirring. The partition 17 is provided with openings (not shown) on the near side and the back side in the figure, and the two-component developer 19 transported to _one of the developer chambers R1 by the screw 13 is provided on the one side of the partition 17. The developer is fed into the stirring chamber R ₂ through the opening, and is transferred to the developer conveying screw 14. The rotation direction of the screw 14 is opposite to that of the screw 13 and the stirring chamber R
The two-component developer 19 in ₂ , the two-component developer 19 delivered from the developer chamber R _1, and the toner supplied from the toner storage chamber R ₃ are stirred and mixed in the opposite direction to the screw 13. to transported inside the stirring chamber R _2, sent into the developer chamber R ₁ through the other opening of the partition wall 17.

[0138] To develop the electrostatic latent image formed on the photosensitive drum 1, the developer 19 in the developer chamber R ₁ is drawn up by the magnetic force of the magnet roller 12, the developing sleeve 1
1 is carried on the surface. The two-component developer 19 carried on the developing sleeve 11 is conveyed to the regulating blade 15 with the rotation of the developing sleeve 11, where it is regulated to a developer thin layer having an appropriate layer thickness. The photosensitive drum 1 reaches a development area facing the photosensitive drum 1. A magnetic pole (development pole) is provided at a portion of the magnet roller 12 corresponding to the development area.
N ₁ is located, and the developing pole N ₁ forms a developing magnetic field in the developing area, and the developing magnetic field causes the developer to spike, thereby generating a magnetic brush of the two-component developer 19 in the developing area. . Then, the magnetic brush comes into contact with the photosensitive drum 1, and the toner 19a attached to the magnetic brush and the toner 19 attached to the surface of the developing sleeve 11 are formed by the reversal developing method.
a is transferred to and adheres to the region of the electrostatic charge image on the photosensitive drum 1, and the electrostatic charge image is developed to form a toner image.

The two-component developer 19 that has passed through the development area
Is returned to the developing device 4 with the rotation of the developing sleeve 11, is stripped from the developing sleeve 11 by the repulsive magnetic field between the magnetic poles S _1, S _2, it falls into the developer chamber R ₁ and the stirring chamber R ₂ Collected.

[0140] When the T / C ratio of the two-component type developer 19 in the fourth development device by the development of the (toner and mixing ratio of the carrier, i.e., toner concentration in the developer) decreases, the toner from the toner storage chamber R ₃ 18 was supplied to the stirring chamber R ₂ in an amount corresponding to the amount consumed in the development, and the T /
C is kept at a predetermined amount. To detect the T / C ratio of the two-component developer 19 in the container 4, a toner concentration detection sensor that measures a change in the magnetic permeability of the two-component developer 19 using the inductance of the coil is used. The toner concentration detection sensor has a coil (not shown) therein.

The regulating blade 15 which is disposed below the developing sleeve 11 and regulates the layer thickness of the two-component developer 19 on the developing sleeve 11 is a non-magnetic blade 15 made of a non-magnetic material such as aluminum or SUS316. It is. The distance between the end and the surface of the developing sleeve 11 is 250 to
It is 1000 μm, preferably 300 to 900 μm.
If this distance is smaller than 250 μm, the magnetic carrier is clogged during this time, and the developer layer is likely to be uneven, and it is difficult to apply a two-component developer necessary for good development, and the density is low and there are many unevenness. An image is easily formed.
This distance is preferably 300 μm or more in order to prevent non-uniform application (so-called blade jam) due to unnecessary particles mixed in the developer. If this distance is larger than 1000 μm, the amount of the developer applied on the developing sleeve 11 increases, and it is difficult to regulate the predetermined thickness of the developer layer, and the adhesion of the magnetic carrier particles to the photosensitive drum 1 increases, and the developer The development regulation by the circulation and regulation blade 15 is weakened, so that the toner tribo is reduced and fogging is easily caused.

Even when the developing sleeve 11 is driven to rotate in the direction of the arrow, the magnetic carrier particle layer is separated from the surface of the developing sleeve 11 by a balance between the restraining force based on the magnetic force and gravity and the conveying force in the moving direction of the developing sleeve 11. Movement slows down. Some fall under the influence of gravity.

Therefore, by appropriately selecting the arrangement positions of the magnetic poles N and S and the fluidity and magnetic properties of the magnetic carrier particles, the closer the magnetic carrier particle layer is to the sleeve, the more the magnetic pole N ₁ becomes.
To form a moving layer. Due to the movement of the magnetic carrier particles, the developer is conveyed to the developing area with the rotation of the developing sleeve 11 and is used for development.

The developed toner image is transferred onto a transferred transfer material (recording material) 25 by a transfer blade 27 which is a transfer unit to which a transfer bias is applied by a bias applying unit 26, and is transferred onto the transfer material. The transferred toner image is fixed to a transfer material by a fixing device (not shown). In the transfer step, the transfer residual toner remaining on the photosensitive drum 1 without being transferred to the transfer material is adjusted in charge in the charging step, and is collected during development.

FIG. 3 is a schematic diagram in which the image forming method of the present invention is applied to a full-color image forming apparatus.

The main body of the full-color image forming apparatus includes a first image forming unit Pa, a second image forming unit Pb,
An image forming unit Pc and a fourth image forming unit Pd are provided side by side, and images of different colors are formed on a transfer material through a process of forming, developing, and transferring a latent image.

The configuration of each image forming unit provided in the image forming apparatus will be described with reference to the first image forming unit Pa as an example.

The first image forming unit Pa includes an electrophotographic photosensitive drum 6 having a diameter of 30 mm as an electrostatic image carrier.
1a, the photosensitive drum 61a is rotated in the direction of arrow a. Reference numeral 62a denotes a primary charger as a charging unit, and a magnetic brush formed on the surface of a sleeve having a diameter of 16 mm is arranged so as to contact the surface of the photosensitive drum 61a. Reference numeral 67a denotes a laser beam for forming an electrostatic charge image on the photosensitive drum 61a, the surface of which is uniformly charged by the primary charger 62a, and is irradiated by an exposure device (not shown). 63a is the photosensitive drum 6
This is a developing device as a developing unit for forming a color toner image by developing an electrostatic charge image carried on 1a, and holds a two-component developer having a carrier and a color toner. Reference numeral 64a denotes a transfer blade as transfer means for transferring the color toner image formed on the surface of the photosensitive drum 61a to the surface of a transfer material (recording material) conveyed by a belt-shaped transfer material carrier 68. ,
The transfer blade 64a can apply a transfer bias by contacting the back surface of the transfer material carrier 68.

The first image forming unit Pa uniformly and primary charges the photosensitive drum 61a by the primary charger 62a, and then forms an electrostatic image on the photosensitive member by the exposure device 67a. The developing unit 63a develops the image with the color toner of the two-component developer, and transfers the developed toner image to a first transfer unit (a contact position between the photoconductor and the transfer material). The transfer bias is applied from the transfer bias applying means 60a to the transfer blade 64a which is in contact with the back side of the belt-shaped transfer material carrier 68 to transfer the image onto the surface of the transfer material.

When the toner is consumed by the development and the T / C ratio decreases, the decrease is detected by a toner concentration detection sensor 85 which measures the change in the magnetic permeability of the developer by using the inductance of the coil, and is consumed. The supply toner 65 is supplied according to the toner amount. The toner density detection sensor 85 has a coil (not shown) therein.

This image forming apparatus has the same configuration as the first image forming unit Pa, and has a second image forming unit Pb, a third image forming unit Pc, and a second image forming unit Pc having different colors of the color toner held in the developing device. Four image forming units of the fourth image forming unit Pd are provided side by side. For example, yellow toner is used for the first image forming unit Pa, magenta toner is used for the second image forming unit Pb, cyan toner is used for the third image forming unit Pc, and black toner is used for the fourth image forming unit Pd. The transfer of each color toner onto the transfer material is sequentially performed in the transfer section of each image forming unit. In this step, while the registration is being performed, each color toner is superimposed on the same transfer material by one transfer of the transfer material, and when the transfer is completed, the transfer material is separated from the transfer material carrier 68 by the separation charger 69. The sheet is sent to a fixing device 70, which is a heating / pressing fixing unit, by a conveying unit such as a conveying belt, and a final full-color image is obtained by a single fixing.

The fixing device 70 has a pair of a fixing roller 71 having a diameter of 40 mm and a pressure roller 72 having a diameter of 30 mm. The fixing roller 71 has heating means 75 and 76 inside.

The unfixed color toner image transferred onto the transfer material passes through the pressure contact portion between the fixing roller 71 and the pressure roller 72 of the fixing device 70, and is applied to the transfer material by the action of heat and pressure. Is established.

In FIG. 3, the transfer material carrier 68 is an endless belt-shaped member, which is moved in the direction of arrow e by a driving roller 80. 7
9 is a transfer belt cleaning device, 81 is a belt driven roller, and 82 is a belt static eliminator. 8
Reference numeral 3 denotes a pair of registration rollers for conveying the transfer material in the transfer material holder to the transfer material carrier 68.

As the transfer means, instead of the transfer blade abutting on the back side of the transfer material carrier, a contact capable of directly applying a transfer bias by abutting on the back side of the transfer material carrier such as a roller-shaped transfer roller. It is possible to use transfer means.

Further, instead of the contact transfer means, a transfer bias is applied by applying a transfer bias from a corona charger arranged in a non-contact manner on the back side of a generally used transfer material carrier. It is also possible to use contact transfer means.

However, it is more preferable to use the contact transfer means in that the amount of ozone generated when the transfer bias is applied can be controlled.

Next, an example of another image forming method of the present invention will be described with reference to FIG.

FIG. 4 is a schematic diagram showing an example of an image forming apparatus capable of performing the image forming method of the present invention.

This image forming apparatus is configured as a full-color copying machine. As shown in FIG. 4, the full-color copying machine has a digital color image reader unit 35 at the upper part and a digital color image printer unit 36 at the lower part.

In the image reader section, the original 30 is placed on an original platen glass 31 and is exposed and scanned by an exposure lamp 32, so that a reflected light image from the original 30 is condensed by a lens 33 to a full color sensor 34, and a color image is formed. Obtain a decomposed image signal. The color separation image signal is processed by a video processing unit (not shown) through an amplification circuit (not shown), and is sent to a digital image printer unit.

In the image printer section, the photosensitive drum 1, which is an electrostatic image carrier, is, for example, an organic photoconductor (OPC).
And is rotatably supported in the direction of the arrow. Around the photosensitive drum 1, a pre-exposure lamp 41,
A corona charger 2 as a primary charging member, a laser exposure optical system 3 as a latent image forming means, a potential sensor 42, four developing devices 4Y, 4C, 4M, and 4K having different colors; The device 5A and the cleaning device 6 are arranged.

In the laser exposure optical system 3, an image signal from the reader unit is converted into an image scan exposure light signal by a laser output unit (not shown), and the converted laser light is reflected by the polygon mirror 3a. , Lens 3b
And is projected onto the surface of the photosensitive drum 1 via the mirror 3c.

[0164] When an image is formed, the photosensitive drum 1
Is rotated in the direction of the arrow, and after the charge is eliminated by the pre-exposure lamp 11, the photosensitive drum 1 is uniformly negatively charged by the charger 2 to irradiate a light image E for each separation color, and the latent image is formed on the photosensitive drum 1. To form

Next, the latent image on the photosensitive drum 1 is developed by operating a predetermined developing device, and a visible image, that is, a toner image is formed on the photosensitive drum 1 by a negatively chargeable toner having a resin as a base material. I do. The developing devices 4Y, 4C, 4M, and 4K alternately approach the photosensitive drum 1 in accordance with each separated color and perform development by the operation of the eccentric cams 24Y, 24C, 24M, and 24K.

The transfer device 5A includes a transfer drum 5, a transfer charger 5b, a suction charger 5c for electrostatically attracting a recording material and a suction roller 5g opposed thereto, an inner charger 5d, an outer charger 5e, It has a separation charger 5h.
The transfer drum 5 is rotatably supported so as to be rotatable, and a transfer sheet 5f, which is a recording material carrier for supporting a recording material (transfer material) in an opening area around the transfer drum 5, is integrally adjusted in a cylindrical shape. A polycarbonate film is used for the transfer sheet 5f.

The recording material is conveyed from the recording material cassette 7a, 7b or 7c to the transfer drum 5 through the recording material conveyance system, and is carried on the transfer sheet 5f. Transfer drum 5
The recording material carried thereon is repeatedly conveyed to a transfer position facing the photosensitive drum 1 as the transfer drum 5 rotates, and is transferred onto the photosensitive material by the action of the transfer charger 5b while passing through the transfer position. 1 is transferred.

In the above image forming step, yellow (Y),
By repeating the process for cyan (C), magenta (M), and black (K), a color image in which four color toner images are superimposed and transferred on the recording material on the transfer drum 5 is obtained.

In the case of single-sided image formation, the recording material onto which the four color toner images have been transferred in this way is separated by the action of the separation claw 8a, the separation push-up roller 8b, and the separation charger 5h.
The sheet is separated from the transfer drum 5 and sent to the heat fixing device 9.
The heat fixing device 9 includes a heat fixing roller 9a having a heating unit therein and a pressure roller 9b. The full-color image carried on the recording material is fixed on the recording material by passing the recording material through the pressure contact portion between the heat fixing roller 9a and the pressure roller 9b as a heating member. That is, in this fixing step, toner color mixing, color development, and fixing to the recording material are performed to form a full-color permanent image, which is then discharged to the tray 10 to complete one full-color copy. On the other hand, the photosensitive drum 1 is subjected to the image forming process again after the residual toner on the surface is cleaned and removed by the cleaning device 6.

In the image forming method of the present invention, it is possible to transfer a toner image obtained by developing the electrostatic charge image formed on the latent image carrier to a recording material via an intermediate transfer member.

That is, in this image forming method, the toner image formed by developing the electrostatic image formed on the electrostatic image carrier is transferred to an intermediate transfer member, and the toner image is transferred to the intermediate transfer member. And a step of transferring the toner image to a recording material.

An example of an image forming method using an intermediate transfer member will be specifically described with reference to FIG.

In the apparatus system shown in FIG. 5, the cyan developing device 54-1, the magenta developing device 54-2, the yellow developing device 54-3, and the black developing device 54-4 are respectively provided with a cyan developer containing a cyan toner and a magenta developer. A magenta developer having a toner, a yellow developer having a yellow toner, and a black developer having a black toner have been introduced. An electrostatic latent image is formed on a photosensitive member 51 as a latent image holding member by a latent image forming means 53 such as a laser beam. By a developing method such as a magnetic brush developing method, a non-magnetic one-component developing method or a magnetic jumping developing method,
The electrostatic charge image formed on the photoconductor 51 is developed with these developers, and a toner image of each color is formed on the photoconductor 51.
The photosensitive member 51 is a photosensitive drum or a photosensitive belt having a conductive substrate 51b and a photoconductive insulating material layer 51a such as amorphous selenium, cadmium sulfide, zinc oxide, an organic photoconductor, and amorphous silicon formed on the conductive substrate 51b. is there. The photoconductor 51 is rotated in a direction indicated by an arrow by a driving device (not shown). As the photoconductor 51, a photoconductor having an amorphous silicon photosensitive layer or an organic photosensitive layer is preferably used.

The organic photosensitive layer may be a single layer type in which the photosensitive layer contains a charge generating substance and a substance having a charge transporting property in the same layer, or a functional separation type in which the charge transporting layer contains the charge generating layer as a component. It may be a photosensitive layer. A laminated photosensitive layer having a structure in which a charge generation layer and then a charge transport layer are laminated on a conductive substrate in this order is one of preferred examples.

As the binder resin for the organic photosensitive layer, a polycarbonate resin, a polyester resin, or an acrylic resin has good cleaning properties, and poor cleaning, fusion of toner to a photoreceptor, and filming of an external additive hardly occur.

In the charging step, there are a non-contact type with the photoreceptor 51 using a corona charger and a contact type with a contact charging member such as a roller, and both types are used. For efficient uniform charging, simplification, and low ozone generation, a contact type as shown in FIG. 5 is preferably used.

The charging roller 52 as a primary charging member is
Conductive elastic layer 5 having central core 52b and outer periphery thereof
2a as a basic configuration. Charging roller 52
Is pressed against the surface of the photoconductor 51 with a pressing force, and the photoconductor 5
The rotation follows the rotation of 1.

A preferable process condition when the charging roller is used is that the contact pressure of the roller is 4.9 to 490 N / m.
(5 to 500 g / cm), when an AC voltage superimposed on a DC voltage is used, AC voltage = 0.5 to 5 kV
pp, AC frequency = 50 Hz to 5 kHz, DC voltage = ±
0.2 to ± 5 kV.

Other contact charging members include a method using a charging blade and a method using a conductive brush. These contact charging members are effective in that high voltage is not required and generation of ozone is reduced.

As the material of the charging roller and the charging blade as the contact charging member, conductive rubber is preferable, and a release coating may be provided on the surface thereof. As the release coating, a nylon resin, PVDF (polyvinylidene fluoride), PVDC (polyvinylidene chloride), or a fluorine acrylic resin can be used.

The toner image on the photosensitive member is applied with a voltage (for example, ±
(0.1 to ± 5 kV). The intermediate transfer member 55 includes a pipe-shaped conductive core 55b and a medium-resistance elastic layer 55 formed on the outer peripheral surface thereof.
a. The cored bar 55b may be provided with a conductive layer (for example, conductive plating) on the surface of plastic.

The medium-resistance elastic body layer 55a is made of silicone rubber, Teflon (registered trademark) rubber, chloroprene rubber, urethane rubber, EPDM (ethylene propylene diene).
An electrical resistance value (volume resistivity) of 10 ⁵ to 10 ¹¹ by blending and dispersing a conductivity-imparting material such as carbon black, zinc oxide, tin oxide, and silicon carbide in an elastic material such as
It is a solid or foamed layer adjusted to a medium resistance of Ω · cm.

The intermediate transfer member 55 is provided in parallel with the photoreceptor 51 so as to be in contact with the lower surface of the photoreceptor 51, and is arranged in the counterclockwise direction indicated by an arrow at the same peripheral speed as the photoreceptor 51. Rotate.

In the process in which the toner image of the first color formed and carried on the surface of the photosensitive member 51 passes through the transfer nip portion where the photosensitive member 51 and the intermediate transfer member 55 are in contact, the transfer bias applied to the intermediate transfer member 55 The intermediate transfer is sequentially performed on the outer surface of the intermediate transfer body 55 by the electric field formed in the transfer nip area.

The untransferred toner on the photosensitive member 51 that has not been transferred to the intermediate transfer member 55 is removed by the photosensitive member cleaning member 5.
8 and is collected in the photoconductor cleaning container 59.

A transfer means is provided in parallel with the intermediate transfer body 55 and is brought into contact with the lower surface of the intermediate transfer body 55. The transfer means 57 is, for example, a transfer roller or a transfer belt. It rotates clockwise with the same peripheral speed as the arrow. The transfer means 57 may be provided so as to directly contact the intermediate transfer body 55, or a belt or the like may be provided so as to contact between the intermediate transfer body 55 and the transfer means 57.

In the case of the transfer roller, the transfer roller is basically composed of a central core bar 57b and a conductive elastic layer 57a formed on the outer periphery thereof.

As the intermediate transfer member and the transfer roller, general materials can be used. By setting the volume resistivity of the elastic layer of the transfer roller smaller than the volume resistivity of the elastic layer of the intermediate transfer member, the voltage applied to the transfer roller can be reduced, and a good toner image can be formed on the transfer material. It is possible to form the transfer material and to prevent the transfer material from winding around the intermediate transfer member. In particular, the volume resistivity of the elastic layer of the intermediate transfer member is 10 times smaller than the volume resistivity of the elastic layer of the transfer roller.
It is particularly preferable that the ratio be twice or more.

The hardness of the intermediate transfer member and the transfer roller is determined by JI
It is measured according to SK-6301. The intermediate transfer member used in the present invention is preferably composed of an elastic layer belonging to a range of 10 to 40 degrees. On the other hand, the hardness of the elastic layer of the transfer roller is higher than the hardness of the elastic layer of the intermediate transfer member. 4
Those having a value of 1 to 80 degrees are preferable from the viewpoint of preventing the transfer material from winding around the intermediate transfer member. When the hardness of the intermediate transfer member and that of the transfer roller are reversed, a concave portion is formed on the transfer roller side, and the winding of the transfer material around the intermediate transfer member is likely to occur.

The transfer means 57 rotates the intermediate transfer member 55 at a constant speed or a peripheral speed. The transfer material 56 is conveyed between the intermediate transfer body 55 and the transfer means 57,
The toner image on the intermediate transfer body 55 is transferred to the surface of the transfer material 56 by applying a bias having a polarity opposite to the frictional charge of the toner to the transfer unit 57 from the transfer bias unit.

The untransferred toner remaining on the intermediate transfer member that has not been transferred to the transfer material 56 is removed by the cleaning member 6 for the intermediate transfer member.
0 and is collected in the intermediate transfer body cleaning container 62. The toner image transferred to the transfer material 56 is fixed on the transfer material 56 by the heat fixing device 61.

As the material of the transfer roller, the same material as that of the charging roller can be used. The preferable transfer process condition is that the contact pressure of the roller is 2.94 to 490 N / m.
(3-500 g / cm) (more preferably 19.6-2
94 N / m), and the DC voltage is ± 0.2 to ± 10 kV.

When the linear pressure as the contact pressure is less than 2.94 N / m, it is not preferable because the transfer of the transfer material and the occurrence of transfer failure tend to occur.

For example, the conductive elastic layer 57 of the transfer roller 57
b is an elastic material such as polyurethane rubber or EPDM (ethylene propylene diene terpolymer), and a conductive agent such as carbon black, zinc oxide, tin oxide or silicon carbide mixed and dispersed in the material to obtain an electric resistance value (volume resistivity). ) Is 10 ⁶ to 1
It is a solid or foamed layer adjusted to a medium resistance of 0 ¹⁰ Ω · cm.

In the image forming apparatus shown in FIGS.
Although not particularly shown, the mounting of an atmosphere heater for controlling the inside of the apparatus to a constant temperature is also a preferable mode for stably providing good image quality. For example, by controlling the inside of the apparatus to a constant temperature, the developing property in the present invention,
Environmental fluctuations such as transferability and fixability can be suppressed.
In particular, in the image forming apparatus shown in FIG. 3, the charge adjustment of the transfer residual toner becomes easy, and the toner can be efficiently collected at the time of development.

As the heater, a heating element may be used. More specifically, an electric resistance heating element such as a wound heater of a sheath-shaped heater, a plate-shaped heater, and a ceramic heater, and a heat radiation element such as a halogen lamp and an infrared lamp. Examples of the heating element include a lamp heating element, a heating element using heat exchange means using a liquid, a gas, or the like as a heating medium. As the surface material of the heating element, metals such as stainless steel, nickel, aluminum, and copper, ceramics, heat-resistant polymer resin, and the like can be used. Regarding the temperature control of the heating element, any of the methods of installing a thermoswitch near the heating element and controlling the temperature by sensing the temperature in the vicinity may be used.

[0197]

The present invention will now be described in detail with reference to Examples, but it should not be construed that the present invention is limited thereto.

Carrier Production Example 1 -Phenol 7.0 parts by mass-Formalin solution 11.55 parts by mass (formaldehyde about 40%, methanol about 10%, remainder water)-γ-glycidoxypropyltrimethoxysilane 1.0 Magnetite fine particles 58.5 parts by mass (average particle size: 0.23 μm, specific resistance: 5 × 10 ⁵ Ω · cm, magnetization intensity: 51 Am ² / kg at 1000 / 4π (kA / m)) 3) parts by mass of α-Fe ₂ O ₃ fine particles lipophilized with 1.0% by mass of γ-glycidoxypropyltrimethoxysilane (average particle size: 0.61 μm, specific resistance: 2 × 10 ⁹ Ω ·) cm) The lipophilic treatment of magnetite I and α-Fe ₂ O ₃ (hematite) used here was performed by 99 parts by mass of magnetite and α
To each of 99 parts by mass of Fe ₂ O ₃ , 1.0 part by mass of γ-glycidoxypropyltrimethoxysilane was added, and the mixture was premixed and stirred at 100 ° C. for 40 minutes in a Henschel mixer.

While maintaining the above materials and 11 parts by mass of water at 40 ° C., mixing was carried out for 1 hour. 2.0 parts by mass of 28% by mass ammonia water as a basic catalyst and 11 parts by mass of water were added to the slurry, and the mixture was heated and maintained at 85 ° C. for 40 minutes with stirring and mixing, and reacted for 3 hours.
A phenolic resin was formed and cured. Thereafter, the mixture was cooled to 30 ° C., 100 parts by mass of water was added, the supernatant was removed, and the precipitate was washed with water and air-dried. Next, this was dried at 180 ° C. under reduced pressure (5 mmHg or less) to obtain spherical magnetic carrier core particles containing magnetite fine particles using a phenol resin as a binder resin.

Coarse particles are removed from the particles by a sieve of 60 mesh and 100 mesh, and then a multi-segment wind classifier utilizing the Coanda effect (Elbow Jet Lab EJ-L-3, manufactured by Nippon Mining Co., Ltd.) Fine powder and coarse powder are removed by using an average particle size (volume average 50%
Carrier core particles having a particle size of 34 μm were obtained.

The obtained carrier core particles were charged into a coater, and humidified nitrogen was introduced to adjust the water content to 0.3% by mass. Thereafter, the core surface was treated with 3% by mass of γ-aminopropyltrimethoxysilane diluted with a toluene solvent while continuously applying a shearing stress. At that time,
The reaction was carried out at 40 ° C., 100 torr under a dry nitrogen stream while evaporating the solvent. Subsequently, 0.5% by mass of a straight silicone resin in which all the substituents are methyl groups and γ
-Aminopropyltrimethoxysilane 0.015% by mass
Was coated with toluene as a solvent. At that time, 4
The reaction was carried out at 0 ° C., 500 torr under a dry nitrogen stream while evaporating the solvent.

Further, this magnetic coated carrier was
Baked at 100 ° C., cut the aggregated coarse particles with a 100-mesh sieve, and then removed the fine powder and coarse powder with a multi-split air classifier to adjust the particle size distribution.
o. 1 was obtained. The obtained magnetic coated carrier No. Table 1 shows the production method and physical properties of No. 1.

Carrier Production Example 2 In the same manner as in Carrier Production Example 1, except that the stirring speed before and after the addition of the basic catalyst was increased by 2.5 times, 2 was obtained. When the average particle size of the carrier was measured, it was 29 μm. The obtained magnetic coated carrier No. Table 1 shows the production methods and physical properties of No. 2.

Carrier Production Example 3 In the same manner as in Carrier Production Example 1, except that the stirring speed before and after the addition of the basic catalyst was increased by a factor of five, the magnetic coated carrier No. 1 was prepared in the same manner. 3 was obtained. When the average particle size of the carrier was measured, it was 14 μm. The obtained magnetic coated carrier No. Table 1 shows the production methods and physical properties of No. 3.

Carrier Production Example 4 In the same manner as in Carrier Production Example 1, except that the stirring speed before and after the addition of the basic catalyst was increased by 0.5 times, the magnetic coated carrier No. 1 was prepared in the same manner. 4 was obtained. When the average particle size of the carrier was measured, it was 59 μm. The obtained magnetic coated carrier No. Table 1 shows the manufacturing methods and physical properties of No. 4.

Carrier Production Example 5 In Carrier Production Example 1, the average particle size was 0.22 μm as magnetite, the specific resistance was 5.2 × 10 ⁵ Ω · cm, and
Magnetization intensity 93 Am ^{2 at} 00 / 4π (kA / m)
/ Kg of magnetite II and changing the ratio of magnetite to hematite to a ratio of 80:20, in the same manner as in Carrier Production Example 1. 5 was obtained. 1000 / 4π (kA / m)
When the magnetization intensity was measured at 73.0 Am ²
/ Kg. The obtained magnetic coated carrier No. 5
Is shown in Table 1.

Carrier Production Example 6 In Carrier Production Example 3, the average particle size of magnetite was 0.22 μm, the specific resistance was 5.2 × 10 ⁵ Ω · cm, and
Magnetization intensity 73 Am ^{2 at} 00 / 4π (kA / m)
/ Kg of magnetite III, except that magnetic coated carrier no. 6 was obtained. When the magnetization intensity at 1000 / 4π (kA / m) was measured, it was 63.0 Am ² / kg. The obtained magnetic coated carrier No. Table 1 shows the manufacturing methods and physical properties of No. 6.

Carrier Production Example 7 The same procedure as in Carrier Production Example 3 was carried out except that the ratio of magnetite to hematite was set to 40:60. 7 was obtained. When the magnetization intensity at 1000 / 4π (kA / m) was measured, it was 18.0 Am ² / kg. The obtained magnetic coated carrier No. Table 1 shows the manufacturing methods and physical properties of No. 7.

Carrier Production Example 8 In the same manner as in Carrier Production Example 3, except that the ratio of magnetite to hematite was set to 50:50, the carrier-coated carrier No. 8 was prepared. 8 was obtained. When the magnetization intensity at 1000 / 4π (kA / m) was measured, it was 25 Am ² / kg. The obtained magnetic coated carrier No. Table 1 shows the manufacturing methods and physical properties of No. 8.

Carrier Production Example 9 Carrier Production Example 9 was the same as Carrier Production Example 1 except that the core was produced using a binder resin as a melamine resin.
In the same manner as for 9 was obtained. The obtained magnetic coated carrier No. Table 1 shows the manufacturing methods and physical properties of No. 9.

Carrier Production Example 10 Carrier Production Example 1 was the same as Carrier Production Example 1 except that the core was produced using a binder resin as an epoxy resin.
In the same manner as for 10 was obtained. The obtained magnetic coated carrier No. Table 1 shows the manufacturing methods and physical properties of No. 10.

Carrier Production Example 11 In the same manner as in Carrier Production Example 1 except that the catalyst used in the core polymerization was changed to sodium hydroxide, Carrier Coated Carrier No. 11 was obtained.
The obtained magnetic coated carrier No. Table 1 shows the manufacturing methods and physical properties of No. 11.

Carrier Production Example 12 In Carrier Production Example 1, except that the amount of the primer added to the coat layer was 0.5% by mass and the polyester resin was used only as the coat resin at 0.5% by mass, the production was carried out. In the same manner as in Carrier Production Example 1, the magnetic coated carrier No. 12 was obtained. The obtained magnetic coated carrier No. Table 1 shows the manufacturing methods and physical properties of No. 12.

[0214]

[Table 1]

Toner Production Example 1 100 parts by mass of polyester resin (condensation polymer of propoxylated bisphenol A and fumaric acid, acid value 10.8 mgKOH / g) I. Pigment Blue 15:35 5 parts by mass ・ Aluminum compound of dialkylsalicylic acid 5 parts by mass ・ Low molecular weight polypropylene 5 parts by mass To perform melt kneading. This melt-kneaded material was crushed by a hammer mill to obtain a crushed material having a mesh path of 1 mm. Further, after finely pulverizing with a jet mill, classification was performed with a multi-segment classifier (Elbow Jet) to obtain cyan toner particles.

To 100 parts by mass of the cyan toner particles, 1.2 parts by mass of hydrophobically treated titanium oxide fine powder (number average particle size of primary particles: 0.02 μm) was mixed by a Henschel mixer, and the weight average particle size was adjusted. 6.5 μm cyan toner No. 1 was obtained. The obtained toner No. Table 2 shows the composition and physical properties of No. 1.

Toner Production Example 2 In place of the polyester resin used in Toner Production Example 1, a styrene-n-butyl acrylate copolymer resin (acid value 3
mgKOH / g, Mw30000, Mn9000) 10
Using 0 parts by mass, 1.2 parts by mass of hydrophobically treated silica fine powder (number average particle size of primary particles: 0.03 μm) is mixed with 100 parts by mass of the cyan toner particles by using a Henschel mixer. In the same manner as in toner production example 1, cyan toner No. 2 was obtained. The obtained toner No. Table 2 shows the composition and physical properties of Sample No. 2.

Toner Production Example 3 The same procedure as in toner production example 1 was repeated except that the aluminum compound of dialkylsalicylic acid used in toner production example 1 was not added. 3 was obtained. The obtained toner No. Table 2 shows the composition and physical properties of Sample No. 3.

Toner Production Example 4 Toner No. 4 was prepared in the same manner as in the production of the cyan toner except that calixarene was used in place of the aluminum compound of dialkylsalicylic acid used in Production Example 1 of the toner. 4 was obtained. The obtained toner No. Table 2 shows the composition and physical properties of Sample No. 4.

Toner Production Example 5 In the toner production example 1, the conditions for pulverizing and classifying the melt-kneaded product were changed so that the addition amount of the hydrophobically treated titanium oxide fine powder to be externally added was set to 0.6% by mass. Except for the above, in the same manner as in Production Example 1 of toner, cyan toner No. 1 having a weight average particle diameter of 10.8 μm 5 was obtained. The obtained toner No. Table 2 shows the composition and physical properties of No. 5.

Toner Production Example 6 450 parts by mass of a 0.1 M Na ₃ PO ₄ aqueous solution were charged into 710 parts by mass of ion-exchanged water, and heated to 60 ° C.
1200 using a homo homomixer (manufactured by Tokushu Kika Kogyo)
The mixture was stirred at 0 rpm. To this, 68 parts by mass of a 1.0 M CaCl ₂ aqueous solution was gradually added to obtain an aqueous medium containing Ca ₃ (PO ₄ ) ₂ . Styrene 165 parts by mass n-butyl acrylate 35 parts by mass C.I. I. Pigment Blue 15: 3 (colorant) 15 parts by mass ・ Metal dialkylsalicylate compound (charge control agent) 5 parts by mass ・ Saturated polyester (polar resin) 10 parts by mass ・ Ester wax (melting point 70 ° C.) 50 parts by mass Was heated to 60 ° C., and was uniformly dissolved and dispersed at 11,000 rpm using a TK homomixer (manufactured by Tokushu Kika Kogyo). In this, 10 parts by mass of a polymerization initiator 2,2'-azobis (2,4-dimethylvaleronitrile) was dissolved to prepare a polymerizable monomer composition.

The polymerizable monomer composition was charged into an aqueous medium, and the mixture was stirred at 60 ° C. under a N ₂ atmosphere at 11,000 rpm for 10 minutes using a TK homomixer to form a polymerizable monomer composition. Granulated. Thereafter, the temperature was raised to 80 ° C. while stirring with a paddle stirring blade, and the reaction was performed for 10 hours. After completion of the polymerization reaction, the remaining monomer was distilled off under reduced pressure, and after cooling, hydrochloric acid was added to dissolve calcium phosphate, followed by filtration, washing with water,
After drying, cyan toner particles were obtained. Hydrophobized silica fine powder (number average particle size of primary particles: 0.03 μm) was added to 100 parts by mass of the obtained cyan toner particles.
3 parts by mass of cyan toner No. 3 having a weight average particle size of 6.8 μm. 6 was obtained. The obtained toner No. Table 2 shows the composition and physical properties of No. 6.

Toner Production Example 7 1.2 parts by mass of hydrophobized alumina fine powder (number average particle size of primary particles: 0.1 μm) was used instead of the hydrophobized silica fine powder used in Toner Production Example 6. Except for using the cyan toner No. 6 in the same manner as in Production Example 6 of the toner.
7 was obtained. The obtained toner No. Table 2 shows the composition and physical properties of No. 7.

Toner Production Example 8 The C.I. I. Pigment Blue 1
Magenta Toner No. 5 in the same manner as in Production Example 6 of toner except that quinacridone was used in an amount of 8 parts by mass instead of 5: 3. 8 was obtained. The obtained toner No. Table 2 shows the composition and physical properties of No. 8.

Toner Production Example 9 The C.I. I. Pigment Blue 1
Pigment Yellow 93 was replaced with 6.5 parts by mass of Pigment Yellow 93 in the same manner as in Toner Production Example 6, except that 6.5 parts by mass of Pigment Yellow 93 was used. 9 was obtained. The obtained toner No.
Table 2 shows the composition and physical properties of No. 9.

Toner Production Example 10 The C.I. I. Pigment Blue 1
Except that 10 parts by mass of carbon black was used instead of 5: 3, black toner No. was produced in the same manner as in Production Example 6 of the toner. 10 was obtained. The obtained toner No. Table 2 shows the composition and physical properties of No. 10.

Toner Production Example 11 An aqueous medium having a higher content of the Ca ₃ (PO ₄ ) ₂ compound than that of Toner Production Example 6 was used, and the rotation speed of the homomixer was set to 1
2.8 rpm in the same manner except that the rotation speed is set to 5000 rpm, and the addition amount of the hydrophobized titanium oxide fine powder is set to 1.6 mass%.
μm cyan toner No. 11 was obtained. The obtained toner No. Table 2 shows the composition and physical properties of No. 11.

Toner Production Example 12 Using an aqueous medium having a smaller content of Ca ₃ (PO ₄ ) ₂ compound than that of Toner Production Example 6, setting the rotation speed of the homomixer to 6500 rpm, and making the titanium oxide fine powder subjected to hydrophobic treatment In the same manner as above except that the amount of addition was 0.6% by mass.
0 μm cyan toner No. 12 was obtained. The obtained toner No. Table 2 shows the composition and physical properties of No. 12.

[0229]

[Table 2]

Example 1 Carrier No. 1 and No. 3
In a mass ratio of 94/6 and a toner N
o. 6 was mixed so that the ratio of the toner to the total mass was 8% by mass to produce a two-component developer A.

As the image forming apparatus, a commercially available digital copying machine GP55 (manufactured by Canon) was modified so that the developing device and the charging device shown in FIG. 1 could be inserted, and the image forming device using the developing bias shown in FIG. 2 was used, and the fixing device was heated. Both the roller and the pressure roller were changed to a roller whose surface layer was covered with PFA by 1.2 μm, and the configuration was modified to eliminate the oil application mechanism.

The image forming apparatus and the two-component developer A
, The image area is 10% and the X-Rite
The image density measured with a 504 type reflection densitometer manufactured by
The original manuscript provided with five circles having a diameter of 20 mm was copied at 23 ° C./5% (N / L) and 32.5 ° C./90
% (H / H) in each environment, a 30,000-sheet passing test was performed, and the evaluation was performed based on the following evaluation method.

As shown in Table 3, good results were obtained in all image characteristics. Here, as the photoreceptor, an organic photoreceptor of 30φ provided with a surface layer having a volume resistance of 3 × 10 ¹² Ω · cm so as to be easily charged was used.

(1) Image Density In an endurance test in an H / H environment, the image density after 40,000 sheets of durability was measured. The image density was 50 by X-Rite.
The reflection density of an image formed on plain paper was measured using a type 4 reflection densitometer.

(2) Carrier Adhesion The initial carrier adhesion level on the photoreceptor under the N / L environment was determined. In this evaluation method, tapping was performed on a solid white drum at a Vback of 300 V, and a 25 × loupe was observed in a visual field of 5 × 5 cm, and visually judged with a loupe.

(Decision level) A: No carrier adhesion B: 5 or less carrier particles are observed C: 5 to 10 carrier particles are observed D: 10 to 20 carrier particles are observed E: 20 to 50 carrier particles are observed F: More than 50 carrier particles are observed

(3) Fog In an endurance test under N / L and H / H environments, fog after 40,000 sheets were run was measured. As a method, the average reflectance Dr (%) of plain paper before image output is measured using a reflectometer equipped with a green filter (“REFLECOMETER MODEL TC-6 manufactured by Tokyo Denshoku Co., Ltd.).
DS "). On the other hand, a solid white image was formed on plain paper, and the reflectance Ds (%) of the solid white image was measured. Fog (%) is calculated from the following equation: Fog (%) = Dr (%)-Ds (%).

(Evaluation criteria) A: less than 0.6% B: 0.6 to less than 1.1% C: 1.1 to less than 1.6% D: 1.6 to less than 2.1% E: 2 0.1 to less than 4.1% F: 4.1% or more

(4) Image Quality In an endurance test in an H / H environment, gradation, highlight uniformity and fine line reproducibility were visually evaluated comprehensively on a 6-point scale based on the original document. A: Excellent B: Good C: Normal D: Bad E: Very bad F: Not usable

(5) Toner Scattering The amount of toner scattering in the machine when 40,000 sheets were printed in an H / H environment was visually evaluated comprehensively on a six-point scale. A: There is no toner scattering B: There is almost no toner scattering C: There is some scattering but there is no problem in actual use D: There is scattering, and there is a case where the image is contaminated in the latter half of the endurance E: There is scattering, from the first half of the endurance The image may be contaminated. F: Scatters poorly and does not endure actual use.

(6) Transfer efficiency measurement The transfer efficiency was measured at 23 ° C./60% (N /
N). In the evaluation method, first, a solid black image is formed on a photosensitive drum, the solid black image is collected with a transparent adhesive tape, and the image density (D1) is measured using a color reflection densitometer (color reflection densitometer).
meter X-RITE 404A manufac
turned by X-Rite Co. ). Next, a solid black image is formed on the photosensitive drum again,
The solid black image was transferred to a recording material, and the solid black image transferred on the recording material was collected with a transparent adhesive tape, and the image density (D2) was measured. The transfer efficiency was calculated from the obtained image densities (D1) and (D2) based on the following equation.

Transfer efficiency (%) = (D2 / D1) × 100

Examples 2 to 15 and Comparative Examples 1 to 11 Two-component developers B to Q and a to k were prepared in the same manner as in Example 1 except that the combinations of carriers and toners shown in Table 3 were used. Was produced and imaged, and evaluated. Table 3 shows the evaluation results.

[0244]

[Table 3]

[Example 16] The developer A of Example 1 and the toner of the developer A 8, No. 9, No. 1
0 to produce two-component developers α, β and γ.

The resulting four-color two-component developer β, α, A
And γ were supplied to the developing devices 63a, 63b, 63c and 63d of the full-color image forming apparatus shown in FIG. 3, respectively, and a full-color image was formed under the following conditions. In copying, a full-color image having a stable image density was obtained.

(Image Forming Conditions) In the charging step, OP
The following magnetic particles 23 were used for the magnetic brush charging device for charging the C photosensitive drum.

Preparation of Magnetic Particles 5 parts by mass of MgO, 8 parts by mass of MnO, 4 parts by mass of SrO,
After 83 parts by mass of e ₂ O ₃ were each atomized, water was added and mixed, granulated, fired at 1300 ° C., adjusted in particle size, and ferrite magnetic particles having an average particle size of 28 μm (σ1
000 is 60 Am ² / kg, and coercive force is 4.38 × 10 ⁻¹
kA / m [= 55 Oersted]).

A mixture of 100 parts by mass of the above magnetic particles and 10 parts by mass of isopropoxytriisostearoyl titanate in 99 parts by mass of hexane / 1 part by mass of water was treated so that the treatment amount became 0.1 part by mass. The treatment yielded magnetic particles.

The magnetic particles have a volume resistance of 3 × 10 ⁷ Ω.
Cm.

In the charging device, the photosensitive drum 1 is rotated in the counter direction at a peripheral speed of 120% of the peripheral speed of the photosensitive member, and a DC / AC electric field (-700 V, 1 kHz / 1.
2 kV _PP ) was applied thereto to charge the photosensitive drum 1.
Digital processing of the original image with an image area of 30%, O
A digital latent image was formed as an electrostatic charge image on a PC photosensitive drum.

The developing devices 63a, 63b, 63c and 63
As d, the developing device 4 shown in FIG. 1 was used.
An electrostatic charge image was developed by a reversal developing method using a negatively chargeable color toner. As a developing bias applied to the developing sleeve, a DC / AC voltage (-300 V, 8 kHz / 2 kV _PP ) using a discontinuous AC bias voltage shown in FIG. 2 is superimposed and applied to a developing contrast of 200 V and a fogging reversal contrast of −150 V. Set.

The color toner image formed on the photosensitive drum 1 is transferred to a first transfer section (contact position between the photosensitive member and the transfer material).
By applying a transfer current of −15 μA from the transfer bias applying means 60a to the transfer blade 64a, the transfer is performed on the surface of the transfer material, and further in the second transfer section, the third transfer section, and the fourth transfer section. Multiple transfer of the color toner image was performed on the transfer material.

In the heat and pressure fixing device, a heating roller coated with a PFA resin to a thickness of 1.2 μm was used, and a PFA resin was coated to a thickness of 1.2 μm as the pressure roller.
Was used. The silicone oil applying means was removed from the heat and pressure fixing device, and oilless fixing was performed.

Example 17 The four-color two-component developers β, A, α and γ produced in Example 16 were used as the developing devices 4Y, 4C, 4M and 4K of the full-color image forming apparatus shown in FIG.
And a DC / AC voltage (-500 V, 12 k) using a discontinuous AC bias voltage for the developing sleeve.
Hz / 2 kV _PP ) and a developing contrast of 27
0 V, fog reversal contrast -120 V, full-color image was formed by transfer current of 17 μA, and oil-less fixing. A good full-color image was obtained, and the image density was stable even when copying many sheets. The obtained full-color image was obtained.

[Embodiment 18] The four-color two-component developers A, α, β and γ produced in Example 16 were used as the developing devices 54-1, 54-2 and 54 of the full-color image forming apparatus shown in FIG.
-3 and 54-4, and a DC / AC voltage (-350 V, 3 kHz / 1.8 kV _PP ) using a discontinuous AC bias voltage is superimposed and applied to the developing sleeve, and the developing contrast is 250 V and the fog is removed. Invert contrast was set to -150V, and transfer current was 15μ
A: When a full-color image was formed by oil-less fixing, a good full-color image was obtained, and a full-color image having a stable image density was obtained even when copying a large number of sheets.

[0257]

According to the present invention, by controlling the amount of fine powder and the magnetic properties of the coated carrier within a specific range, it is possible to suppress carrier adhesion and achieve long-term image stability.

[Brief description of the drawings]

FIG. 1 is a schematic view illustrating a preferred example of an image forming method of the present invention.

FIG. 2 is a diagram showing an alternating electric field used in Example 1.

FIG. 3 is a schematic explanatory view showing an example of a full-color image forming method.

FIG. 4 is a schematic explanatory view showing another example of the image forming apparatus for performing the image forming method of the present invention.

FIG. 5 is a schematic explanatory view showing another example of the image forming apparatus for performing the image forming method of the present invention.

[Explanation of symbols]

 Reference Signs List 1 electrostatic image carrier (photosensitive drum) 2 charger 3 laser exposure optical system 3a polygon mirror 3b lens 3c mirror 4 developing device 4Y developing device 4C developing device 4M developing device 4K developing device 5 transfer drum 5a transfer device 5b transfer charging device 5c Adsorption charger 5d Inner charger 5e Outer charger 5f Transfer sheet 5g Suction roller 5h Separation charger 6 Cleaning device 7a Recording agent cassette 7b Recording agent cassette 7c Recording agent cassette 8a Separating claw 8b Separation push-up roller 9 Heat fixing device 9a Heating Fixing roller 9b Pressure roller 10 Tray 11 Developer carrier (development sleeve) 12 Magnet roller 13, 14 Developer transport screw 15 Regulator blade 17 Partition wall 18 Replenishment toner 19 Developer 19a Toner 19b Carrier 20 Refill 21 Magnet roller L 22 Conveying sleeve 23 Magnetic particle 24 Laser beam 24Y Eccentric cam 24M Eccentric cam 24C Eccentric cam 24K Eccentric cam 25 Transfer material (recording material) 26 Bias applying means 27 Transfer blade 28 Toner density detection sensor 30 Document 31 Document glass 32 Exposure lamp 33 Lens 34 Full color sensor 35 Image reader section 36 Digital image printer section 41 Pre-exposure lamp 42 Potential sensor 43 Drum light amount detecting means 53 Latent image forming means 54-1 Cyan developing device 54-2 Magenta developing device 54-3 Yellow developing device 54-4 Black Developing Device 55 Intermediate Transfer Body 55a Elastic Layer 55b Core Metal 56 Transfer Material 57 Transfer Means (Transfer Roller) 57a Conductive Elastic Layer 57b Core Metal 58 Photoconductor Cleaning Member 59 Photoconductor Cleaning Container 60 Intermediate transfer member cleaning member 61 Heat fixing device 61a Photosensitive drum 62 Intermediate transfer member cleaning container 62a Primary charger 63a Developing device 64a Transfer blade 65a Replenishing toner 67a Laser beam 68 Transfer material carrier 69 Separator charger 70 Fixing device 71 Fixing roller 72 Pressure roller 73 Web 75, 76 Heating means 79 Transfer belt cleaning device 80 Driving roller 81 Belt driven roller 82 Belt static eliminator 83 Registration roller 85 Toner density detection sensor R1 Developer chamber R2 Stir chamber R3 Storage chamber Pa First Image forming unit Pb Second image forming unit Pc Third image forming unit Pd Fourth image forming unit

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G03G 9/107 G03G 9/08 331 15/06 101 9/10 331 352 362 (72) Inventor Kenji Okado Tokyo 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Ryoichi Fujita 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Yasushi Katsuta Shimomaruko, Ota-ku, Tokyo 3-30-2 Canon Inc. (72) Inventor Kenichi Nakayama 3-30-2 Shimomaruko, Ota-ku, Tokyo F-term (reference) 2H005 AA01 AA08 AA11 AA15 BA03 BA06 BA07 CA08 CA12 CA14 CA15 CA17 CA26 CA28 CB03 CB07 CB13 EA01 EA02 EA05 EA07 EA10 2H073 AA01 AA07 BA03 BA06 BA13 CA03 CA22

Claims (56)

[Claims] 1. A resin-coated carrier comprising at least a carrier core and a resin coating layer, wherein the resin-coated carrier A has an average particle size of 25 to 55 μm and a resin-coated carrier particle B of 20 μm or less by a mesh method. 0.1 to 10% by mass, and 1000 / 4π of each of the resin-coated carriers A and B.
(KA / m), the intensity of magnetization σa, σb (Am ² /
(kg) satisfying the following relational expression. 30 ≦ σa ≦ 70 20 ≦ σb ≦ 60 0.2 ≦ σa−σb ≦ 20 2. The carrier has a specific resistance of 1 × 10 ⁸ to 1
Resin-coated carrier according to claim 1, characterized in that a × 10 ¹⁶ Le · cm. 3. The resin-coated carrier according to claim 1, wherein the carrier core is a resin-coated carrier in which metal compound particles are dispersed in a binder resin. 4. The carrier core contains at least two or more kinds of metal compound particles, the ratio of the metal compound to the binder resin is 80 to 99% by mass, and one of the metal compound particles is strong. A magnetic material, and the other is nonmagnetic metal compound particles having higher resistance than the ferromagnetic material, wherein the ratio of the ferromagnetic material to the total amount of the metal compound particles is 50 to 95% by mass. The resin-coated carrier according to claim 3, wherein 5. The resin-coated carrier according to claim 4, wherein the carrier core contains magnetite as the ferromagnetic material, and contains hematite as at least one of the high-resistance metal compounds. 6. The resin-coated carrier according to claim 3, wherein the binder resin is a thermosetting resin and has a crosslinked structure. 7. The resin-coated carrier according to claim 3, wherein the binder resin is a phenol resin. 8. The method according to claim 7, wherein the phenol resin is obtained in the presence of an ammonia catalyst.
The resin-coated carrier according to 1. 9. The surface of the metal compound particles is treated with a lipophilic treatment agent having at least one functional group selected from the group consisting of an epoxy group, an amino group and a mercapto group. The resin-coated carrier according to any one of claims 3 to 8, wherein 10. The resin-coated carrier according to claim 3, wherein the surface of the metal compound particles is treated with a lipophilic treatment agent having at least an epoxy group. 11. The carrier core according to claim 1, wherein the surface of the carrier core is coated with a silicone resin.
0. The resin-coated carrier according to any one of 0. 12. The resin-coated carrier according to claim 1, wherein the surface of the carrier core is coated with a silicone resin containing a coupling agent. 13. The resin-coated carrier according to claim 1, wherein the surface of the carrier core is treated with a coupling agent and then coated with a silicone resin. 14. The resin-coated carrier according to claim 12, wherein the coupling agent is an aminosilane. 15. A two-component developer comprising a carrier core, a resin-coated carrier having a resin for coating the surface of the carrier core, and a toner containing at least a binder resin and a colorant. The carrier A has an average particle size of 25 to 55 μm.
And 0.01 to 10% by mass of resin-coated carrier particles B having a particle size of 20 μm or less according to a mesh method.
A / m) of the magnetization σa, σb (Am ² / k)
g) satisfies the following relational expression: 30 ≦ σa ≦ 70 20 ≦ σb ≦ 60 0.2 ≦ σa−σb ≦ 20, and the toner has a weight average particle diameter of 3 to 10 μm. Component developer. 16. The carrier has a specific resistance of 1 × 10 ⁸ or more.
^{16. The} pressure is 1 × 10 ¹⁶ le · cm.
2. The two-component developer according to item 1. 17. The two-component developer according to claim 15, wherein the carrier core is a resin-coated carrier in which metal compound particles are dispersed in a binder resin. 18. The carrier core contains at least two kinds of metal compound particles, the ratio of the metal compound to the binder resin is 80 to 99% by mass, and one of the metal compound particles is strong. A magnetic material, and the other is a nonmagnetic metal compound particle having a higher resistance than the ferromagnetic material, wherein the ratio of the ferromagnetic material to the total amount of the metal compound particles is 50 to 95% by mass. The two-component developer according to claim 17, wherein 19. The two-component developer according to claim 18, wherein the carrier core contains magnetite as the ferromagnetic substance, and contains hematite as at least one of the high-resistance metal compounds. . 20. The two-component developer according to claim 17, wherein the binder resin of the carrier core is a thermosetting resin and has a crosslinked structure. . 21. The two-component developer according to claim 17, wherein the binder resin of the carrier core is a phenol resin. 22. The two-component developer according to claim 21, wherein the phenol resin is obtained in the presence of an ammonia catalyst. 23. The surface of the metal compound particles is treated with a lipophilic treatment agent having at least one functional group selected from the group consisting of an epoxy group, an amino group and a mercapto group. A two-component developer according to any one of claims 17 to 22. 24. The two-component developer according to claim 17, wherein the surface of the metal compound particles is treated with a lipophilic treatment agent having at least an epoxy group. 25. The two-component developer according to claim 15, wherein a surface of said carrier core is coated with a silicone resin. 26. The two-component developer according to claim 15, wherein the surface of the carrier core is coated with a silicone resin containing a coupling agent. 27. The two-component developer according to claim 15, wherein the surface of the carrier core is treated with a coupling agent and then coated with a silicone resin. 28. The two-component developer according to claim 26, wherein the coupling agent is an aminosilane. 29. The two-component developer according to claim 15, wherein the toner contains a polyester resin as the binder resin. 30. The toner according to claim 30, wherein the toner has at least one peak in a range of 280 to 350 nm when the absorbance of an extract obtained by extracting 0.1 mol / liter of sodium hydroxide is measured. Item 30. The two-component developer according to any one of Items 15 to 29. 31. The toner according to claim 31, wherein SF-1 is 100 to 120.
The two-component developer according to any one of claims 15 to 30, wherein 32. The two-component system according to claim 15, wherein said toner has a core / shell structure, and said core is formed of a material having a low softening point. Agent. 33. The two-component developer according to claim 15, wherein at least silica fine particles and / or titanium oxide fine particles are externally added to said toner. 34. An electrostatic image carrier is charged by charging means, the charged electrostatic image carrier is exposed to form an electrostatic image on the electrostatic image carrier, and the electrostatic image is developed by two-component development. A toner image is formed on an electrostatic image carrier by developing with a developing means having an agent, and the toner image on the electrostatic image carrier is transferred to a transfer material with or without an intermediate transfer member. An image forming method for fixing a toner image on a transfer material by a heating / pressing fixing means, wherein the two-component developer has at least a toner and a resin-coated carrier; And a colorant, and has a weight average particle diameter of 3 to 10 μm. The resin-coated carrier A has an average particle diameter of 25 to 55 μm.
And 0.01 to 10% by mass of resin-coated carrier particles B having a particle size of 20 μm or less according to a mesh method.
A / m) of the magnetization σa, σb (Am ² / k)
g) satisfies the following relational expression: 30 ≦ σa ≦ 70 20 ≦ σb ≦ 60 0.2 ≦ σa−σb ≦ 20. 35. The carrier has a specific resistance of 1 × 10 ⁸ or more.
35. The apparatus according to claim 34, wherein the size is 1 × 10 ¹⁶ le · cm.
2. The image forming method according to 1., 36. The image forming method according to claim 34, wherein the carrier core is a resin-coated carrier in which metal compound particles are dispersed in a binder resin. 37. The carrier core contains at least two or more kinds of metal compound particles, the ratio of the metal compound to the binder resin is 80 to 99% by mass, and one of the metal compound particles is strong. A magnetic material, and the other is nonmagnetic metal compound particles having higher resistance than the ferromagnetic material, wherein the ratio of the ferromagnetic material to the total amount of the metal compound particles is 50 to 95% by mass. 37. The image forming method according to claim 36, wherein: 38. The image forming method according to claim 37, wherein the carrier core contains magnetite as the ferromagnetic material, and contains hematite as at least one of the high-resistance metal compounds. 39. The image forming method according to claim 36, wherein the binder resin of the carrier core is a thermosetting resin and has a crosslinked structure. 40. The image forming method according to claim 36, wherein the binder resin of the carrier core is a phenol resin. 41. The image forming method according to claim 40, wherein the phenol resin is obtained in the presence of an ammonia catalyst. 42. The surface of the metal compound particles is treated with a lipophilic treatment agent having one or more functional groups selected from the group consisting of an epoxy group, an amino group and a mercapto group. The image forming method according to any one of claims 36 to 41. 43. The image forming method according to claim 36, wherein the surface of the metal compound particles is treated with a lipophilic treatment agent having at least an epoxy group. 44. The image forming method according to claim 34, wherein the surface of the carrier core is coated with a silicone resin. 45. The image forming method according to claim 34, wherein the surface of the carrier core is coated with a silicone resin containing a coupling agent. 46. The image forming method according to claim 34, wherein the surface of the carrier core is treated with a coupling agent and then coated with a silicone resin. 47. The image forming method according to claim 45, wherein the coupling agent is an aminosilane. 48. The image forming method according to claim 34, wherein the toner contains a polyester resin as the binder resin. 49. The toner according to claim 49, wherein the toner has at least one peak in the range of 280 to 350 nm when the absorbance of an extract obtained by extracting 0.1 mol / liter of sodium hydroxide is measured. Item 48. The image forming method according to any one of Items 34 to 48. 50. The toner according to claim 1, wherein SF-1 is 100 to 120.
The image forming method according to any one of claims 34 to 49, wherein: 51. The image forming method according to claim 34, wherein the toner has a core / shell structure, and the core is formed of a material having a low softening point. 52. The two-component developer according to claim 34, wherein at least silica fine particles and / or titanium oxide fine particles are externally added to said toner. 53. The developing means has a developing sleeve containing a magnetic field generating means, and develops an electrostatic charge image with a two-component developer while applying an AC bias to the developing sleeve. The image forming method according to any one of the above. 54. The image forming method according to claim 53, wherein the waveform of the AC bias is continuous or discontinuous. 55. The image forming method according to claim 34, wherein the electrostatic charge image is a digital latent image, and the digital latent image is developed by a reversal developing method. 56. The image forming method according to claim 34, wherein the electrostatic image carrier is a photosensitive drum having an OPC photosensitive layer.