JP2002296831A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device with which an excellent image is obtained without having a scattering phenomenon due to the mutual repulsion of toner particles in the case of using the toner whose transfer efficiency and dot reproducibility are excellent. SOLUTION: In the image forming device, a developing means possesses a plurality of developer carriers having a magnetic member in their inside and constitutes a non-contact developing means in which AC bias is applied to individual developer carriers. The toner contains at least a binding resin and a magnetic body, and has >=90% particles whose weight average grain size (X) is 5-12 μm and whose circularity (a) in the particles having the circle equivalent size of >=3 μm is >=0.900 by the number-based cumulative value (Y). The relation of a cut rate (Z) and the grain size (X) satisfies Z<=5.3×X. The relation of the cumulative value (Y) based on the number of the particles whose circularity is >=0.950 and the grain size (X) satisfies Y>=exp5.51×X<-0.645> , or the relation of the cut rate (Z) and the grain size (X) satisfies Z>5.3×X, and also the relation of the accumulated value (Y) and the grain size (X) satisfies Y>=exp5.37×X<-0.545> . The coating rate of the magnetic body of a toner particle surface is >=20% and <45%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus used for a recording method using an electrophotographic method, an electrostatic recording method, and an electrostatic printing method.

[0002]

2. Description of the Related Art Electrophotography is disclosed in U.S. Pat.
Numerous methods are known as described in Japanese Patent Publication No. 691, Japanese Patent Publication No. 42-23910 and Japanese Patent Publication No. 43-24748. Generally, a photoconductive substance is used to form an electrostatic charge image on a photoreceptor, which is an image carrier, by various means, and then the electrostatic charge image is developed using toner, and if necessary, such as paper. After transferring the toner image to the transfer material, the toner image is fixed on the transfer material by heating, pressure, heating and pressurizing, or solvent vapor to obtain a toner image. FIG. 8 shows an example of such a conventional image forming apparatus.

The surface of an image carrier (amorphous silicon) 1 for forming an electrostatic latent image is charged by a primary charger 2 and irradiated with a laser beam 3 to form an electrostatic latent image on the image carrier 1. It is formed. The developing device 4 applies a voltage between the developing sleeve 4a and the image carrier 1 to develop the electrostatic latent image to form a toner image on the image carrier 1, and the toner image is charged by a pre-transfer charger. The charge amount of the toner image formed on the image carrier 1 is made uniform by 10, and the toner image is transferred to the transfer material 9 by the transfer charger 8. The transfer material 9 is separated from the image carrier 1 by the first separation charger 5 and the second separation charger 6. The transfer material 9 that cannot be separated by the separation first charger 5 and the second charger 6 is separated by the separation claw 7. Toner remaining on the image carrier 1 without being transferred to the transfer material 9 (transfer residual toner)
Is removed by the cleaning device 11. The semiconductor laser 12 emits a laser beam 3 modulated by an image signal.
Is reflected by the reflecting mirror 17 via the imaging lens 16 and raster-scans the image carrier 1.

In the above-described apparatus, an image is formed on a photosensitive member by applying an image forming process of charging, light image exposure, and development, and the formed image is transferred to a transfer material, and the transferred image is fixed to obtain an image-formed product. .

Recently, in the field of high-speed machines for image forming apparatuses, highly durable amorphous silicon (a-Si) is often used as a photosensitive member of the image carrier 1. Further, in the field of high-speed machines, the pre-transfer charger 10 is often used as an aid because the separation of the transfer material 9 from the image carrier 1 is severe. Amorphous silicon has a feature of high image quality in addition to high durability because a latent image is sharply formed, and is sensitive to image quality deterioration factors other than the latent image.
Therefore, when using amorphous silicon,
As a reason other than the separation assistance, the pre-transfer charger 10 is often used to prevent image deterioration (tailing phenomenon) during fixing.

On the other hand, as a method for producing a toner for developing an electrostatic image, a binder resin for fixing to a material to be transferred, various colorants for giving a color as a toner, and a charge for giving a charge to particles. Using a control agent as a raw material, or
In a so-called one-component developing method as disclosed in JP-A-2141 and JP-A-55-18656, in addition to these, various magnetic materials for imparting transportability to the toner itself are used. Depending on, for example, other additives such as a release agent and a fluidity-imparting agent are added, dry-mixed, melt-kneaded in a general-purpose kneading device such as a roll mill, extruder, and the like, and after cooling and solidifying, the kneaded material is jetted. Air-flow crusher,
Finely pulverized by various pulverizers such as a mechanical collision pulverizer, and the obtained coarsely pulverized product is introduced into various air classifiers and classified to obtain a classified product having a particle size required for toner particles. Further, if necessary, a fluidizing agent, a lubricant, and the like are externally added and dry-mixed to obtain a toner to be used for image formation.

As described above, in order to obtain fine toner particles, the method shown in the flowchart of FIG. 9 has conventionally been generally adopted.

[0008] The coarsely pulverized toner is supplied to the first classifying means continuously or successively, and the classified coarse powder mainly composed of coarse particles having a specified particle size or more is sent to the pulverizing means and pulverized. It is circulated again to the first classification means.

[0009] The finely pulverized toner mainly composed of particles within the specified particle size range and particles not larger than the specified particle size is sent to the second classifying means, and the intermediate powder mainly composed of particles having the specified particle size is used. Body, a fine powder mainly composed of particles smaller than the specified particle size,
It is classified into a coarse powder mainly composed of particles exceeding a specified particle size. However, as the toner particles are reduced to fine particles, electrostatic aggregation between the particles is increased, and the fine particles that are originally excessively pulverized due to the toner particles originally sent to the second classifying unit being circulated again to the first classifying unit. Body and ultrafine powder may be generated.

As the pulverizing means, various pulverizing apparatuses are used. For pulverizing a coarsely pulverized toner mainly composed of a binder resin,
A jet airflow type pulverizer using a jet airflow as shown in FIG. 10, particularly an impact type airflow pulverizer is used.

A collision type air flow pulverizer using a high-pressure gas such as a jet air stream conveys a powder raw material by a jet air stream, injects the powder raw material from an outlet of an acceleration tube, and opposes the powder raw material to an opening surface of an outlet of the acceleration tube. Then, the powder material is crushed by the impact force of the collision member.

[0012] For example, in the collision type air flow pulverizer shown in Fig. 10, an accelerating tube 162 connected to a high pressure gas supply nozzle 161 is used.
A collision member 164 is provided opposite to the outlet 163 of the, and the high-pressure gas supplied to the acceleration pipe 162 sucks the powder raw material into the acceleration pipe 162 from the powder raw material supply port 165 communicated in the middle of the acceleration pipe 162. Then, the powder raw material is ejected together with the high-pressure gas to collide with the collision surface 166 of the collision member 164, crushed by the impact, and the crushed material is discharged from the crushed material discharge port 167.

[0013] However, the above-mentioned impingement type air current pulverizer is configured to eject the powder raw material together with the high-pressure gas to collide with the collision surface of the collision member and pulverize by the impact. It is a regular and square shape.

As for the classification means, various airflow classifiers and methods have been proposed. Among these, there are a classifier using a rotary wing and a classifier without a movable part. Among them, a classifier without a movable part includes a fixed wall centrifugal classifier and an inertial force classifier. Classifiers utilizing such inertia are disclosed in JP-B-54-24745 and JP-B-55-643.
No. 3, JP-A-63-101858. These airflow classifiers, as shown in FIG.
The supply nozzle having an opening in the classifying area of the classifier room blows the powder at high speed into the classifying area together with the airflow, and the coarse powder is formed in the classifying chamber by the centrifugal force of the curved airflow flowing along the Coanda block 145. The coarse powder, the medium powder, and the fine powder are classified by the edges 146 and 147 which are separated into the powder and the fine powder and whose tips are thinned.

In the conventional classifier, the pulverized material is introduced from a raw material supply nozzle, and the pulverized material flowing inside the pyramids 148 and 149 has a tendency to flow with a propulsive force straight parallel to the tube wall. However, when the raw material is introduced from above in the raw material supply nozzle, the raw material is roughly divided into an upper flow and a lower flow, and the upper flow contains a lot of light fine powder, and the lower flow contains a lot of heavy coarse powder. It is easy to contain, and each powder flows independently, so different trajectories are drawn depending on the location of introduction into the classifier, and coarse powder disturbs the trajectory of fine powder, improving classification accuracy Classification of coarse powder having a particle size of 20 μm or more tends to reduce accuracy (hereinafter, a toner produced using a collision type air flow pulverizer shown in FIG. 10 and an air flow type classifier shown in FIG. 11 is used). Air-crushed toner).

Many different properties are required for the toner, and in order to obtain such required properties, the raw materials to be used as well as the manufacturing method are often determined. In the classification process of toner particles, it is required that the classified particles have a sharp particle size distribution, and it is desired to efficiently and stably produce high quality toner at low cost. In the pulverizing step, it is necessary to control the particle size and shape of the produced toner particles.

As the particle size of the toner is reduced, the specific surface area of the toner particles increases. This increases the cohesiveness and adhesion of the toner. For this reason, when the toner image is transferred from the photoreceptor to the transfer material, the adhesive force acting between the photoreceptor and the toner is increased, and the transfer efficiency is reduced. In particular, the toner produced by the conventional pulverization method is irregular and angular, and this tendency is remarkable. In other words, even if the toner has a small particle size, it is possible to improve the transfer efficiency by giving a low adhesion property equal to or higher than that of a toner having a normal particle size (12 to 14 μm).

When the toner has a relatively large particle size, the specific surface area of the toner becomes small. For this reason, the adhesive force acting between the photoconductor and the toner is weak for the toner having a small particle diameter. That is, when a toner having a large particle diameter has a circularity distribution equivalent to that of a toner having a small particle diameter, the effect of reducing the adhesion is further enhanced, and the transfer efficiency is improved. Other problems can arise, such as deterioration.

Further, when a toner having a small particle diameter is used, dot reproducibility is improved, but fog and scattering tend to be deteriorated. This is thought to be due to the fact that toner particles such as fine powder and ultrafine powder and a large number of particles having the desired particle size are mixed in order to produce fine toner particles from coarsely pulverized toner particles. Can be
That is, toners having different particle diameters have different charging characteristics and different adhesions to individual particles. For this reason, by reducing the particle size, the distribution of the charge amount of the toner becomes wider on the contrary. In order to control these, it is important to control the circularity distribution of the toner based on the amount of the fine powder and the ultrafine powder.

[0020]

SUMMARY OF THE INVENTION The present invention has been made in view of the above point of view, and an image forming apparatus capable of improving transfer efficiency and obtaining a good image free from the phenomenon of scattering caused by repulsion of toner particles. The purpose is to provide.

[0021]

Means for Solving the Problems The present inventors have found that the above problem can be solved by defining the amount of magnetic material present on the surface of the spherical toner and using a plurality of developer carriers in the developing means. The present invention has been achieved.

That is, the present invention provides an image carrier, charging means for applying a voltage to a charging member to charge the image carrier, and an electrostatic device for forming an electrostatic latent image on the charged image carrier. Latent image forming means, developing means for transferring toner to an electrostatic latent image formed on the image carrier to visualize and form a toner image, transfer means for transferring the toner image to a transfer material,
Wherein the developing unit has a plurality of developer carriers having a magnetic member therein, and is a non-contact developing unit in which an AC bias is applied to each developer carrier. The toner has toner particles containing at least a binder resin and a magnetic material, and the toner has a weight average particle diameter of 5.0 to 12.0 μm, and the toner particles have a circle equivalent diameter of 3 μm or more. Particles having a circularity a of 0.900 or more determined by the following formula (1) have a cumulative value on a number basis of 90% or more,

[0023]

## EQU7 ## Circularity a = L0 / L (1) (L0: Perimeter of a circle having the same projected area as the particle image, L:
An image forming apparatus characterized by satisfying the following (a) and (b) or (a ′) and (b). (A) The relationship between the cut ratio Z and the weight average particle size X of the toner particles satisfies the following expression (2);

[0024]

[Equation 8] Cut rate Z ≦ 5.3 × X (2) (However, the cut rate Z is the particle concentration of all the measured particles measured by a flow particle image analyzer FPIA-1000 manufactured by Toa Medical Electronics Co., Ltd. (Number / μl), and B (number / μl) is the concentration of measured particles having a circle-equivalent diameter of 3 μm or more.

[0025]

(9) Z = (1−B / A) × 100 (3)) and the number-based cumulative value Y of particles having a circularity of 0.950 or more
And the weight average particle size X of the toner satisfies the following expression (4).

[0026]

Y ≧ exp 5.51 × X ^−0.645 (4) (However, the weight average particle size X of the toner particles is 5.0 to 12
0 μm. (A ′) the relationship between the cut rate Z and the weight average particle diameter X of the toner satisfies the following expression (2 ′);

The cut rate Z> 5.3 × X (2 ′) and the number-based cumulative value Y of particles having a circularity of 0.950 or more
And the weight average particle size X of the toner satisfies the following expression (4 ′).

Y ≧ exp 5.37 × X ^−0.545 (4 ′) (where the weight average particle diameter X of the toner is 5.0 to 12.0 μm)
m. (B) The coverage of the magnetic substance on the toner surface is 20%
As mentioned above, it is less than 45%.

[0027]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail. <1> Toner in the Present Invention The toner used in the image forming apparatus of the present invention has toner particles containing at least a binder resin and a magnetic substance, and the toner has a weight average particle diameter of 5.0 to 12.0 μm. In the toner particles having a circle equivalent diameter of 3 μm or more, particles having a circularity a of 0.900 or more determined by the following formula (1) have a cumulative number-based value of 90% or more, and

[0028]

## EQU13 ## Circularity a = L0 / L (1) (L0: Perimeter of a circle having the same projected area as the particle image, L:
(Perimeter of particle image) and the following (a) and (b) or (a ′) and (b) are satisfied. (A) The relationship between the cut rate Z and the weight average particle diameter X of the toner satisfies the following expression (2);

[0029]

[Equation 14] Cut rate Z ≦ 5.3 × X (2) (However, the cut rate Z is the particle concentration of all the measured particles measured by the flow particle image analyzer FPIA-1000 manufactured by Toa Medical Electronics Co., Ltd. (Number / μl), and B (number / μl) is the concentration of measured particles having a circle-equivalent diameter of 3 μm or more.

[0030]

Z = (1−B / A) × 100 (3)) and the number-based cumulative value Y of particles having a circularity of 0.950 or more
And the weight average particle size X of the toner satisfies the following expression (4).

[0031]

Y ≧ exp 5.51 × X ^−0.645 (4) (where the weight average particle diameter X of the toner is 5.0 to 12.0 μm)
m. (A ′) the relationship between the cut rate Z and the weight average particle diameter X of the toner satisfies the following expression (2 ′);

## EQU17 ## The cut rate Z> 5.3 × X (2 ′) and the number-based cumulative value Y of the particles having a circularity of 0.950 or more.
And the weight average particle size X of the toner satisfies the following expression (4 ′).

Y ≧ exp 5.37 × X ^−0.545 (4 ′) (where the weight average particle diameter X of the toner is 5.0 to 12.0 μm)
m. (B) The coverage of the magnetic substance on the toner surface is 20%
As mentioned above, it is less than 45%. When the toner satisfies the above-mentioned particle size, particle size distribution, and circularity, it is easy to control the charge of the toner, and it is possible to obtain uniform charge and stable durability. Further, it has been found that when the circularity is in the above range, the transfer efficiency is increased. This is because the contact area between the toner and the image carrier is reduced by reducing the contact area between the toner particles and the image carrier. Furthermore, since the specific surface area of the toner particles is reduced, the contact area between the toner particles is reduced, the bulk density of the toner powder is increased, and the heat conduction at the time of fixing is improved, thereby improving the fixing property. An effect can also be obtained.

The average circularity in the present invention is used as a simple method for quantitatively expressing the shape of a particle, and is a flow type particle image analyzer FPIA-Made by Toa Medical Electronics.
The measurement is performed using a value of 1000, the circularity of the measured particles is determined by the above equation (1), and the sum of the circularities of all the particles measured by the following equation (5) is divided by the total number of particles. The defined value is defined as the average circularity.

[0033]

[Equation 19] In addition, the circularity standard deviation SD is obtained by calculating the average circularity determined by the above equations (1) and (5) as a, the circularity of each particle as ai,
Assuming that the number of measured particles is m, it is calculated from the following equation (6).

[0034]

(Equation 20) The circularity in the present invention is an index of the degree of unevenness of the toner particles, and is 1.00 when the toner particles are perfectly spherical, and the circularity becomes smaller as the surface shape becomes more complicated. Further, the SD of the circularity distribution in the present invention is an index of the variation, and the smaller the numerical value, the smaller the variation of the toner shape. In the present invention, the circularity standard deviation SD is preferably 0.030 to 0.045. In addition, "FPIA-1000" calculates the circularity of each particle, and then calculates the average circularity and the circularity standard deviation.
1.0 is divided into 61 classes, and a calculation method of calculating the average circularity and the circularity standard deviation using the center value and frequency of the division points is used. However, each value of the average circularity and circularity standard deviation calculated by this calculation method, and each value of the average circularity and circularity standard deviation calculated by the above-described calculation formula that directly uses the circularity of each particle, The error of
Very small and substantially negligible, and in the present specification, the circularity of each particle described above is directly calculated for data handling reasons such as shortening of calculation time and simplification of calculation formula. Such a calculation method partially modified using the concept of the calculation formula to be used may be used.

The specific measuring method is as follows. In 100 to 150 ml of water from which impurities have been removed in advance, 0.1 to 0.5 ml of a surfactant, preferably an alkylbenzene sulfonate, is added as a dispersant, and about 0.1 to 0.5 g of a toner as a measurement sample is further added. . The suspension in which the sample was dispersed was subjected to dispersion treatment for about 1 to 3 minutes with an ultrasonic disperser, and the dispersion liquid concentration was set to 1.2 to 20 thousand / μl, using the above-mentioned flow type particle image measuring apparatus, 0.60 μm or more 1
The circularity distribution of particles having an equivalent circle diameter of less than 59.21 μm is measured. In addition, the concentration of the dispersion was 12 to 20 thousand particles /
By using μl, it is possible to maintain a particle concentration that can maintain the accuracy of the apparatus even when the cut rate increases.

The outline of the measurement is described in the catalog of FPIA-1000 (June 1995 edition) issued by Toa Medical Electronics Co., Ltd., the operation manual of the measuring apparatus, and Japanese Patent Application Laid-Open No. Hei 8-1364.
No. 39, which is as follows.

The sample dispersion liquid is passed through a flow path (spread along the flow direction) of a flat and flat transparent flow cell (thickness: about 200 μm). The strobe and the CCD camera are mounted on the flow cell so as to be positioned on opposite sides of the flow cell so as to form an optical path that intersects with the thickness of the flow cell. While the sample dispersion is flowing, strobe light is irradiated at 1/30 second intervals to obtain an image of the particles flowing through the flow cell, so that each particle has a range parallel to the flow cell 2
Photographed as a two-dimensional image. From the two-dimensional image area of each particle, the diameter of a circle having the same area is calculated as the equivalent circle diameter. The circularity of each particle is calculated from the two-dimensional image projection area of each particle and the perimeter of the projected image using the above-described circularity calculation formula. Since the circularity of all the measured particles is measured as described above, the number of all the measured particles is 1
A cumulative value based on the number can be calculated as 00% by number. In addition, the particle size distribution in the present invention is performed using a Coulter counter multisizer. As a measuring device, a Coulter Counter Multisizer II (manufactured by Coulter) was used, and an interface (manufactured by Nikkaki) for outputting the number distribution and volume distribution and a CX-1 personal computer (manufactured by Canon) were connected. A 1% NaCl aqueous solution is prepared using special grade or primary grade sodium chloride. As the measuring method,
In 150 ml, 0.1 to 5 ml of a surfactant (preferably alkylbenzene sulfonate) is added as a dispersant, and 2 to 20 mg of a measurement sample is further added. The electrolytic solution in which the sample is suspended is subjected to a dispersion treatment for about 1 to 3 minutes by an ultrasonic disperser. When the particle size of the toner is measured as an aperture by the Multisizer II of the Coulter Counter, it is 10 times.
The measurement is performed using a 0 μm aperture.

The volume distribution and the number distribution are calculated by measuring the volume and the number of the toner. Then, the weight-based weight average particle diameter determined from the volume distribution is determined. It is conventionally known that the shape of a toner affects various characteristics of the toner.
Through various studies, it has been found that the shape of the toner having a size of 3 μm or more and the coverage of the magnetic substance on the toner greatly affect the transferability and the developability. It has also been found that if a particle group having a circle equivalent diameter of less than 3 μm exceeds a certain amount, it may cause deterioration in performance such as transferability and developability. That is, when the fine powder of the toner particles or the fine powder of less than 3 μm such as an external additive becomes a certain amount or more, it is apparent that it is difficult to obtain the desired performance unless the circularity of the toner particles of 3 μm or more is increased. became.

Therefore, in the present invention, the effect of the present invention is exhibited when the toner particles having a circularity of 0.900 or more have a cumulative value of 90% or more based on the number of toner particles having a circle equivalent diameter of 3 μm or more. However, in order to more effectively exert the circularity effect of toner particles having a particle size of 3 μm or more in the present invention which greatly affects transferability and developability, the presence of fine particles having a particle size of 3 μm or less is as follows. 3 by quantity
It is necessary to control the circularity of toner particles having a size of μm or more.

That is, the circularity of the toner having a particle size of 3 μm or more is controlled by the amount of the fine powder having a size of 3 μm or less, and a toner having excellent transferability and developability can be obtained.

FPIA-1 used as a circularity measuring device
In the measurement of circularity by 000, the smaller the particle size, the closer the particle image is to a point, and thus the higher the circularity tends to be. For this reason, when a large amount of particles having a small particle size exist in the toner particles, the circularity of the toner particles increases. Conversely, when only a small amount of particles having a small particle size are present in the toner particles, the circularity of the toner particles becomes small. Then, as calculated by the above equation (3), a cut rate Z expressed by subtracting the ratio of the particle concentration of the group of particles having a circle diameter of 3 μm or more to the particle concentration of all the measured particles from 100%, and In the case of the above equations (2) and (2 '), the relationship between the weight average particle size X and the toner particle shape required to satisfy the desired performance, that is, the relationship between the circularity and the weight average particle size, It is derived as in the above equations (4) and (4 ′).

When Z ≦ 5.3 × X, the circularity a is 0.
Cumulative value based on the number of particles of 950 or more Y ≧ exp5.5
When 1 × X ^−0.645 is not satisfied, that is, when the number-based cumulative value Y <exp 5.51 × X ^−0.645 is satisfied, the toner cannot be uniformly charged. Not only cannot it be obtained, but also the fluidity of the toner particles tends to deteriorate, the transfer efficiency is low, and the desired fixing performance tends to be difficult to obtain. On the other hand, when Z> 5.3 × X, when the circularity a does not satisfy the cumulative value Y ≧ exp5.37 × X ^{−0.545 based} on the number of particles with 0.950 or more, that is, the number-based cumulative value Y <exp5 When 37 × X ^−0.545 is satisfied, sufficient development efficiency cannot be obtained because the toner cannot be uniformly charged, and also the fluidity of the toner particles tends to deteriorate, and the transfer efficiency also increases. It tends to be low and it is difficult to obtain desired fixing performance.

In the present invention, the cut ratio Z is A (number / μl) of the particle concentration of all the measured particles measured by a flow-type particle image analyzer FPIA-1000 manufactured by Toa Medical Electronics Co., Ltd. When the particle concentration is B (number / μl), the particle density is represented by the above formula (3), and the toner weight average particle diameter X is 5.0 to 12.0 μm.

Further, the toner according to the present invention has a thickness of 3 μm
Among the above particles, particles having a circularity of 0.95 or more exist in a cumulative value based on the number of 70% or more, and a circularity of 0.99 or more.
5 or more particles exist at 8% or more, and the abundance of particles having a circularity of 0.995 or more exists at a ratio of 12 to 18% of the number-based cumulative value of the particles having a circularity of 0.950 or more. Is particularly preferred.

The toner has a weight average particle diameter of 5.
It is preferably from 0 to 12.0 μm, and
It is preferably from 0 to 10.0 μm. Further, the proportion of particles having a particle size of 4.0 μm or less is preferably 70% by number or less, and more preferably 2% or less of particles having a particle size of 10.1 μm or more.
It is preferably at most 5% by volume. When the weight average particle diameter of the toner exceeds 12.0 μm, the developability of fine lines is reduced,
Image reproducibility decreases. Further, the weight average particle size is 5.0 μm.
When the toner particle size is less than m, the generation of fine powder and ultrafine powder cannot be suppressed, and the charge of the toner becomes non-uniform or the cohesion increases, so that it is difficult to obtain good developability.

If the particles having a particle size of 4.0 μm or less exceed 70% by number, the charge of the toner becomes non-uniform and the degree of aggregation is increased, so that it is difficult to obtain good developability. If the particles having a particle diameter of 10.1 μm or more exceed 25% by volume, the developability of fine lines tends to decrease and the image reproducibility tends to decrease.

The binder resin used in the toner of the present invention is not particularly limited, and examples thereof include a polyester resin, a vinyl resin, and an epoxy resin. Among them, polyester resins and vinyl resins are more preferable in terms of chargeability and fixability.

The magnetic substance contained in the toner of the present invention includes iron oxides such as magnetite, maghemite, and ferrite, and iron oxides containing other metal oxides; Fe, Co,
Metals such as Ni, or these metals and Al, C
o, Cu, Pb, Mg, Ni, Sn, Zn, Sb, B
Examples thereof include alloys with metals such as e, Bi, Cd, Ca, Mn, Se, Ti, W, and V, and mixtures thereof.

Specifically, as the magnetic substance, triiron tetroxide
(Fe_ThreeO_Four), Iron sesquioxide (γ-Fe_TwoO_Three), Iron oxide
Lead (ZnFe_TwoO_Four), Yttrium iron oxide (Y_ThreeFe_FiveO
₁₂), Cadmium iron oxide (CdFe_TwoO_Four), Iron oxide gado
Linium (Gd_ThreeFe_FiveO₁₂), Iron oxide copper (CuFe
_TwoO_Four), Lead iron oxide (PbFe₁₂O₁₉), Nickel iron oxide
(NiFe_TwoO_Four), Iron neodymium oxide (NdFe_TwoO_Three),
Barium oxide (BaFe) ₁₂O₁₉), Iron oxide magnesium
(MgFe_TwoO_Four), Iron manganese oxide (MnFe)
_TwoO_Four), Iron oxide lanthanum (LaFeO)_Three), Iron powder (F
e), cobalt powder (Co) and nickel powder (Ni)
I can do it. The above-mentioned magnetic materials may be used alone or in combination of two or more.
Use together. Particularly preferred magnetic materials are triiron tetroxide or
It is a fine powder of γ-iron sesquioxide.

These magnetic materials have an average particle size of 0.01 to
At 0.40 μm, the magnetic properties when 795.8 kA / m is applied show a coercive force of 1.6 to 12.0 kA / m and a saturation magnetization of 50 to ²⁰⁰ Am ² / m.
kg (preferably 50-100 Am ² / kg), remanence 2-2
Those having 0 Am ² / kg are preferred.

In the toner of the present invention, the content of the magnetic material is determined based on 100 parts by mass of the binder resin and 30 to 15 magnetic materials.
0 parts by mass, preferably 60 to 120 parts by mass. If the average particle size, amount, and magnetization of the magnetic material are not appropriate, imbalance with the magnetic force on the sleeve may occur, toner may be scattered, and development may not be performed well. The same applies to the case where a magnetic substance is externally added.

The toner according to the present invention has a magnetic material coverage of 20% or more and less than 45% on the toner surface. More preferably, it has a coverage of 30 to less than 40%. If the coverage of the magnetic substance on the toner surface is lower than 20%, the charge may be applied by the pre-transfer charging.
The charge on the toner surface becomes uneven, causing repulsion between the toners and disturbing the image.Also, when the charge is applied on the sleeve, the charge on the toner surface becomes uneven, aggregates, and the toner on the sleeve is Coat may be uneven, 45%
If it is too high, the charge on the surface of the toner flows, and the toner cannot be charged by an appropriate amount, which may cause poor development or poor transfer, or may cause the color of the toner to become reddish.

The measuring method of the coverage of the magnetic material is performed as follows.

Take a photographic image of the toner after adding an external additive such as hydrophobic silica fine powder by a scanning microscope with an acceleration voltage of 5 kV and magnified 20,000 times. The area is obtained by digitizing the area of the magnetic material portion with the image analysis device described above, and the area ratio of the resin-coated portion to the toner area is calculated.

Further, in order to make the coverage of the magnetic substance on the toner surface 20% or more and less than 45%, the average particle diameter and amount of the magnetic substance are optimized, and in some cases, the magnetic substance is externally added, and What is necessary is just to make the existence rate and amount appropriate. Components necessary for the toner, such as a release agent, a plasticizer, a charge control agent, a cross-linking agent, and a coloring agent in some cases, and other additives can be appropriately added to those commonly used in the production of the toner.

For example, the following has been proposed as a production method for obtaining a toner in the present invention.・ Binder resin (polyester resin) 100 parts by mass (Tg 60 ° C, acid value 20 mg KOH / g, hydroxyl value 30 mg
KOH / g, molecular weight: Mp7000, Mn3000, M
90 parts by mass of magnetic iron oxide (average particle size 0.22 μm, characteristic Hc at 795.8 kA / m magnetic field Hc 9.2 kA / m, σs 82 Am ² / kg, σr 11.5 Am ² / k
g) ・ 2 parts by weight of charge control agent resin ・ 3 parts by weight of low molecular weight ethylene-propylene copolymer After thoroughly mixing these materials with a mixer such as a Henschel mixer or a ball mill, roll, kneader,
Melting, kneading and kneading using a hot kneader such as an extruder and the like, while dispersing or dissolving the pigments or dyes while the resins are mutually compatible, solidifying by cooling, pulverizing and classifying, Particles are obtained, and if necessary, an external additive or the like is added to obtain a toner.

FIGS. 2 and 3 are an example of a flowchart showing an outline of a preferred method for producing a toner in the present invention. As shown in the flowchart, this manufacturing method does not require a classification step before the pulverization process, and is characterized in that the pulverization step, the fine pulverization step, and the classification step are performed in one pass. The method for producing the toner includes a melt-kneading step, a pulverizing step, a fine pulverizing step, and a classification step. In the melt-kneading step, a mixture containing at least a binder resin and a magnetic material is melt-kneaded to obtain a kneaded product, and after the kneaded product obtained in the pulverizing step is cooled, the cooled product is coarsely pulverized by a pulverizing means to obtain a coarsely pulverized product. And the coarsely pulverized product is used as a powder raw material in the fine pulverization step.

Then, a powder material comprising a predetermined amount of coarsely pulverized material is placed around a rotor composed of a rotating body attached to at least a central rotating shaft, and at a predetermined distance from the surface of the rotor, around the rotor. And an annular space formed by maintaining an interval and introduced into a mechanical pulverizer configured to be in an airtight state, and the rotation of the mechanical pulverizer is performed. The powder material is finely pulverized by rotating the element at a high speed.

Next, the finely pulverized product is classified in a classification step to obtain a classified product as a toner raw material comprising particles having a specified particle size. In this case, in the classification step, a multi-divided airflow classifier that has at least a coarse powder region, a medium powder region, and a fine powder region as a classification means and performs airflow classification using a crossed airflow and a Coanda effect is preferably used. For example, when using a three-split airflow classifier,
Powder materials are classified into at least three types: fine powder, medium powder, and coarse powder. In the classification process using such a classifier, a coarse powder consisting of a group of particles having a particle size larger than a specified particle size and an ultrafine powder consisting of a group of particles smaller than a specified particle size are excluded,
The intermediate powder is used as it is as a toner product, or used as a toner after being mixed with an external additive such as hydrophobic colloidal silica.

The ultrafine powder composed of particles smaller than the specified particle size classified in the classification step is generally used in a melt-kneading step for producing a powder raw material composed of a toner material introduced into the pulverization step. To be reused or discarded. In contrast, in the preferred method for producing the toner of the present invention, the fine pulverization method does not require the first classification before the fine pulverization step. In addition to the simpler structure, the structure does not require a large amount of air to pulverize the powder material,
The amount of electric power consumed per kg of toner consumed in the pulverizing step is about 1/3 or less of that produced by the conventional collision type air-flow pulverizer shown in FIG. 10, and the energy cost can be reduced. The toner produced by the method shown in FIGS. 2 and 3 may be hereinafter referred to as mechanically ground toner.

Hereinafter, the mechanical crusher shown in FIGS. 5, 6 and 7 will be described. FIG. 5 shows a schematic cross-sectional view of an example of a mechanical crusher used in the present invention,
FIG. 6 is a schematic sectional view taken along the line DD ′ in FIG. 5, and FIG. 7 is a perspective view of the rotor 314 shown in FIG. The apparatus includes a casing 313, a jacket 316, and a distributor 22 as shown in FIG.
0, a rotor 314 having a large number of grooves formed on a high-speed rotating surface formed of a rotating body attached to a center rotating shaft 312 in a casing 313, and arranged at an outer periphery of the rotor 314 at a constant interval. Stator 310 having a large number of grooves on its surface, a powder inlet 311 for introducing a powder material composed of coarsely pulverized material, and a powder for discharging the powder after the treatment. And an outlet 302.

The pulverizing operation of the mechanical pulverizer constructed as described above is performed, for example, as follows.

That is, when a predetermined amount of powder raw material is introduced through the powder inlet 311 by the table-type first constant-rate feeder 315 of the mechanical pulverizer shown in FIG. The impact generated between the rotor 314 which is introduced into the processing chamber and rotates at a high speed in the pulverizing chamber and has a large number of grooves on the surface thereof and the stator 310 which has a large number of grooves formed on the surface. , Which are instantaneously crushed by a number of ultra-high-speed vortices generated behind them, and the high-frequency pressure oscillations generated thereby. Thereafter, the powder is discharged through the powder discharge port 302. The air (air) carrying the toner particles passes through the pulverizing processing chamber, and is supplied to the powder outlet 302 and the pipe 21.
9, is discharged out of the system of the apparatus system through the collection cyclone 229, the bag filter 222 and the suction filter 224. In the present invention, the pulverization of the powder raw material is performed in this manner, so that a desired pulverization treatment can be easily performed without increasing the number of fine powders and coarse powders.

Further, when the powder raw material is pulverized by the mechanical pulverizer, it is preferable that the cool air generating means 321 blows cold air into the mechanical pulverizer together with the powder raw material. Further, the temperature of the cold air is preferably 0 to -18C.
Further, as the internal cooling means of the mechanical crusher main body, the mechanical crusher preferably has a structure having a jacket structure 316, and it is preferable to pass cooling water (preferably, antifreeze such as ethylene glycol). Further, the room temperature T1 in the spiral chamber 212 communicating with the powder introduction port in the mechanical pulverizer is reduced to 0 ° C. or lower, more preferably −5 to −15 ° C., and still more preferably −7 by the above-described cool air device and jacket structure. The temperature is preferably from -12 ° C. from the viewpoint of toner productivity. The room temperature T1 of the vortex chamber in the crusher is 0 ° C. or lower, more preferably −5 to −5 ° C.
By setting the temperature to −15 ° C., more preferably −7 to −12 ° C., it is possible to suppress the surface deterioration of the toner due to heat,
The powder raw material can be efficiently crushed. If the room temperature T1 of the spiral chamber in the pulverizer exceeds 0 ° C., it is not preferable from the viewpoint of toner productivity because the surface of the toner is liable to be deteriorated due to heat during the pulverization and the internal fusing is likely to occur. If the room temperature T1 of the spiral chamber in the crusher is to be operated at a temperature lower than −15 ° C., the refrigerant (alternative Freon) used in the cold air generating means 321 must be changed to Freon.

The cooling water (preferably, an antifreeze such as ethylene glycol) is supplied from the cooling water supply port 317 to the inside of the jacket, and is discharged from the cooling water discharge port 318.

The finely pulverized product generated in the mechanical pulverizer passes through the rear chamber 320 of the mechanical pulverizer to the powder discharge port 3.
02 is discharged outside the machine. At this time, the room temperature T2 of the rear chamber 320 of the mechanical pulverizer is preferably 30 to 60 ° C. from the viewpoint of toner productivity. Rear chamber 32 of mechanical crusher
By setting the room temperature T2 of 0 to 30 to 60 ° C., deterioration of the surface of the toner due to heat can be suppressed, and the pulverized raw material can be efficiently pulverized. Temperature T2 of mechanical crusher
Is less than 30 ° C., a short path may be caused without being pulverized, which is not preferable in terms of toner performance. On the other hand, when the temperature is higher than 60 ° C., the toner may be excessively pulverized at the time of pulverization, and the surface of the toner may be deteriorated by heat or may be easily fused in the apparatus.

When the powder material is pulverized by the mechanical pulverizer, the room temperature T1 of the spiral chamber 212 of the mechanical pulverizer and the rear chamber 3
The temperature difference ΔT (T2−T1) of the room temperature T2 of 20 to 40 to 7
0 ° C., more preferably 42 to 67 ° C.
° C, more preferably 45 to 65 ° C, from the viewpoint of toner productivity. ΔT between the temperature T1 and the temperature T2 of the mechanical pulverizer is 40 to 70 ° C., more preferably 42 ° C.
By setting the temperature to about 67 ° C., and more preferably 45 ° C. to 65 ° C., deterioration of the surface of the toner due to heat can be suppressed, and the pulverized raw material can be efficiently pulverized. If ΔT between the temperature T1 and the temperature T2 of the mechanical pulverizer is smaller than 40 ° C., a short path may occur without being pulverized, which is not preferable in terms of toner performance. Also, 7
If the temperature is higher than 0 ° C., it may be excessively pulverized at the time of pulverization, and the surface of the toner may be deteriorated by heat or may be easily fused in the apparatus.

When the pulverized raw material is pulverized by a mechanical pulverizer, the glass transition point (Tg) of the binder resin is 45 to 75.
° C, more preferably 55-65 ° C. The room temperature T1 of the spiral chamber 212 of the mechanical crusher is 0 ° C. with respect to Tg.
It is preferable that the temperature is lower than 60 ° C. and lower than Tg by 60 to 75 ° C. from the viewpoint of toner productivity. By setting the room temperature T1 of the spiral chamber 212 of the mechanical pulverizer to 0 ° C. or lower and 60 to 75 ° C. lower than Tg, it is possible to suppress the surface deterioration of the toner due to heat, and to efficiently pulverize the raw material. Can be. Further, the room temperature T2 of the rear chamber 320 of the mechanical crusher is 5 to 30 ° C. higher than Tg, and furthermore, 10 to 20 ° C.
Preferably, the temperature is lower by ° C. The room temperature T2 of the rear chamber 320 of the mechanical pulverizer is 5 to 30 ° C., more preferably 10 to 30 ° C. than Tg.
By lowering the temperature by 20 ° C., deterioration of the surface of the toner due to heat can be suppressed, and the pulverized raw material can be efficiently pulverized.

The peripheral speed of the tip of the rotating rotor 314 is preferably 80 to 180 m / sec, more preferably 90 to 170 m / sec, and still more preferably 100 to 180 m / sec.
It is preferably from 160 to 160 m / sec from the viewpoint of toner productivity. The peripheral speed of the rotating rotor 314 is set to 80 to 180.
m / sec, more preferably 90 to 170 m / sec, and still more preferably 100 to 160 m / sec, it is possible to suppress insufficient pulverization and excessive pulverization of the toner, and to efficiently pulverize the powder raw material. . When the peripheral speed of the rotor is lower than 80 m / sec, it is not preferable from the viewpoint of toner performance because a short path is easily generated without being pulverized. If the peripheral speed of the rotor 314 is higher than 180 m / sec, the load on the apparatus itself is increased, and at the same time, the toner is over-pulverized at the time of pulverization. Not preferred from the point.

The minimum distance between the rotor 314 and the stator 310 is preferably 0.5 to 10.0 mm, more preferably 1.0 to 5.0 mm, and still more preferably 1.0 to 5.0 mm. It is preferably 3.0 mm. Rotor 314
The distance between the stator 310 and the stator 310 is 0.5 to 10.0 mm, more preferably 1.0 to 5.0 mm, and still more preferably 1.0 to 5.0 mm.
By setting the thickness to 3.0 mm, insufficient pulverization of the toner and excessive pulverization can be suppressed, and the powder raw material can be pulverized efficiently. The distance between the rotor 314 and the stator 310 is 1
If it is larger than 0.0 mm, a short path is likely to occur without being pulverized, which is not preferable in terms of toner performance. When the distance between the rotor 314 and the stator 310 is smaller than 0.5 mm, the load on the apparatus itself is increased, and at the same time, the toner is over-pulverized during pulverization, and the surface of the toner is liable to be deteriorated by heat and to be fused inside the apparatus. Therefore, it is not preferable from the viewpoint of toner productivity.

In producing the toner, the weight average particle diameter of the toner particles is from 5.0 to 12.0 in the fine pulverization step.
It is preferable to obtain a finely pulverized product having a particle size of 4.0 μm, particles having a particle size of 4.0 μm or less are 70% by number or less, and particles having a particle size of 10.1 μm or more are 25% by volume or less. Weight average particle size,
The particle size distribution is adjusted to the above range by appropriately selecting the load and the throughput in the mechanical pulverizer.

Next, in order to produce the toner used in the present invention, a classifying means for adjusting the particle size distribution of toner particles by classifying the finely pulverized product obtained by pulverizing the above powdery raw material with a mechanical pulverizer. An air-flow classifier that is preferably used for the present invention will be described. As an example of a preferred multi-split air classifier used in the present invention, an apparatus of the type shown in FIG. 4 (cross-sectional view) will be exemplified as a specific example.

In FIG. 4, the side wall 32 and the G block 3
3 forms a part of the classifying chamber, the classifying edge blocks 34 and 35 have classifying edges 27 and 28. The installation position of the G block 33 can be slid right and left. Also, the classification edges 27 and 28 are
And 28a, and the classification edge can be rotated to change the classification edge tip position. The installation positions of the classification edge blocks 34 and 35 can be slid left and right, and accordingly, the respective knife edge type classification edges 27 and 28 also slide left and right. The classification area 40 of the classification chamber 42 is divided into three by the classification edges 27 and 28.

A finely pulverized material supply port 50 for introducing the finely pulverized material is provided at the rearmost end of the finely pulverized material supply nozzle 26, and a high pressure air supply nozzle 51 is provided at the rear end of the finely pulverized material supply nozzle 26. A classifying chamber 42 having a fine pulverized material introduction nozzle 52
A fine pulverized material supply nozzle 26 having an opening at the right side of the side wall 32 is provided, and the Coanda block 3 is drawn in a long elliptical arc with respect to an extension direction of a lower tangent line of the finely pulverized material supply nozzle 26.
6 are installed. Left block 37 of classification room 42
Is provided with a knife-edge type inlet edge 29 on the right side of the classifying chamber 42, and further on the left side of the classifying chamber 42,
Air inlet pipes 24 and 25 are provided.

The positions of the classification edges 27 and 28, the G block 33, and the inlet edge 29 are adjusted according to the type and desired particle size of the toner to be classified.

On the upper surface of the classifying chamber 42, the outlets 21 and 2 that open into the classifying chamber correspond to the respective dividing areas.
2 and 23, and communication means such as a pipe is connected to the discharge ports 21, 22 and 23, and it is also preferable to provide an opening and closing means such as a valve for each.

The classification operation in the multi-division classification region configured as described above is performed, for example, as follows. That is, the pressure in the classifying chamber is reduced through at least one of the outlets 21, 22, and 23, and the airflow flowing through the fine pulverized material supply nozzle 26 having an opening in the classifying chamber and the high-pressure air supply nozzle 51 is reduced. By the ejector effect of the compressed air to be injected, the finely pulverized material is preferably fed at a flow rate of 10 to 350 m / sec from the second quantitative feeder 53 through the finely pulverized material supply port 50 and the finely pulverized material supply nozzle 26. Spout into the classifier and disperse.

The particles in the finely pulverized material introduced into the classification chamber are:
Due to the Coanda effect of the Coanda block 36 and the cross-flow effect of the gas such as air flowing at that time, the Coanda block 36 moves in a curved line, and according to the size of each particle and the magnitude of the inertial force, large particles ( (Coarse powder) outside the air stream,
That is, the first fraction outside the classification edge 28, the intermediate particles (medium powder) are the second fraction between the classification edges 28 and 27, and the small particles (fine powder) are the third fraction inside the classification edge 27. The classified large particles are discharged from the outlet 21, the classified intermediate particles are discharged from the outlet 22, and the classified small particles are discharged from the outlet 23. The large particles discharged from the discharge port 21 are again introduced into the mechanical pulverizer, and pulverized and classified.

In the above-mentioned classification of the powder, the classification point is determined by the classification edges 27 and 28 with respect to the lower end portion of the Coanda block 36 at which the finely pulverized material projects into the classification chamber 42.
Is mainly determined by the edge tip position of the edge. Further, the classification point is affected by the suction flow rate of the classification airflow, the ejection speed of the powder from the finely pulverized material supply nozzle 26, and the like.

Further, in the multi-split air classifier of the type shown in FIG. 4, a finely pulverized material supply nozzle, a finely pulverized material introduction nozzle and a high pressure air supply nozzle are provided on the upper surface of the multi-split air flow type classifier. Since the position of the classification edge block having the classification edge can be changed so that the shape of the classification area can be changed, the classification accuracy can be remarkably improved as compared with the conventional airflow type classification device.

From the above, in the method and system for producing a toner according to the present invention, by controlling the conditions of pulverization and classification, the weight-average particle diameter becomes 1
A toner having a sharp particle size distribution with a particle size of 2.0 μm or less (especially 8.0 μm or less), and having a specific circularity and a cumulative value on a number basis can be efficiently generated. <2> Image Forming Apparatus of the Present Invention The image forming apparatus of the present invention comprises an image carrier, a charging unit that applies a voltage to a charging member to charge the image carrier, and an electrostatically charged image carrier. Electrostatic latent image forming means for forming a latent image, developing means for transferring the toner to the electrostatic latent image formed on the image carrier, visualizing and forming a toner image,
Transfer means for transferring the toner image to a transfer material, wherein the developing means has a plurality of developer carriers having a magnetic member therein, and each developer carrier has Non-contact developing means to which an AC bias is applied, wherein a toner having the above characteristics is used.

FIG. 1 is a sectional view showing a main part of an embodiment of the image forming apparatus of the present invention.

The surface of an image carrier (amorphous silicon) 1 for forming an electrostatic latent image is charged by a primary charger 2 serving as a charging unit, and irradiated with a laser beam 3 serving as an electrostatic latent image forming unit. An electrostatic latent image is formed on the image carrier 1. The developing device 4 as a developing unit applies a voltage between each of the developing sleeves 4 a and 4 b as a developer carrier and the image carrier 1 to develop an electrostatic latent image. A toner image is formed, and the charge amount of the toner image formed on the image carrier 1 is made uniform by the pre-transfer charger 10, and the toner image is transferred to the transfer material 9 by the transfer charger 8 as a transfer unit. Is done. The transfer material 9 is separated from the image carrier 1 by the first separation charger 5 and the second separation charger 6. The transfer material 9 that could not be separated by the separation first charger 5 and the second charger 6 is
It is separated by the separation claw 7. The toner (transfer residual toner) remaining on the image carrier 1 without being transferred to the transfer material 9 is removed by the cleaning device 11. Semiconductor laser 1
2 irradiates a laser beam 3 modulated by an image signal. The laser beam 3 is reflected by a rotary polygon mirror 14 and reflected by a reflecting mirror 17 via an imaging lens 16 to raster scan the image carrier 1. I do. The toner image transferred to the transfer material 9 is fixed by the fixing device 13.

Further, the developing means in the image forming apparatus of the present invention has two developer carrying members (developing sleeves) as shown in FIG. With this configuration, the swelling of the toner at the edge portion due to the edge effect at the image contour portion is eliminated,
A high-quality image with less scattering can be obtained, and the amount of toner consumption can be reduced. In the present invention, the number of developer carrying members included in the developing means may be three or more. However, the number of developer carriers is preferably two in consideration of the balance between cost, space, image quality, and the like.
In the case of three or more, the image quality is further improved, but the effect is small, the cost is increased, and the size is increased.

The form of the first developer carrying member (developing sleeve) 4a is, for example, a non-magnetic member sleeve having a diameter of 20 mm.
After blasting with FGB # 300 on aluminum A2017 of mm, coated with a coating layer. This coating layer prevents a sleeve ghost image generated at a sleeve cycle which is a problem in JP-A-3-36570 or the like, and enhances the durability of the sleeve surface (a film for protecting the aluminum surface).

Inside the first developing sleeve 4a, a fixed magnet having a magnetic field pattern as shown in FIG. 13 is provided as a magnetic member.

As the sleeve of the non-magnetic member, SUS or the like can be used in addition to aluminum. As a method of coating the coating layer of the first developing sleeve, for example, the following method may be mentioned. A coating liquid for a coating layer in which a conductive material (P) such as crystalline graphite or carbon for adjusting the resistance value is mixed with a binder resin (B) such as a phenol resin, a polyurethane, or a polyamide is coated on the sleeve surface. 4 to 25 μm thick
And cured in a 150 ° C. environment.
The thickness for forming a stable and uniform film is about 20 μm. The P / B mass ratio is preferably 1/2 to 1/10.
Thereafter, a step of polishing the sleeve surface is preferably performed. As a polishing method, for example, a lapping tape (# 3000) of 3 cm is applied to the surface of the sleeve at a pressure of 1.5 kg, and polishing is performed once.

The conductive substance added to adjust the resistance value of the coating layer to an appropriate value includes, for example, metal powders of aluminum, copper, nickel, silver, etc., antimony oxide,
Examples include metal oxides such as indium oxide and tin oxide, and carbon materials such as carbon fiber, carbon black, and graphite. In the present invention, among these, carbon black, especially conductive amorphous carbon, is particularly excellent in electrical conductivity, imparts conductivity by filling in a polymer material, and only controls the addition amount,
It is preferably used because an arbitrary conductivity can be obtained to some extent. The conductive material has an average particle size of 0.01 to 0.80.
μm is preferably used.

The resistance value of the coating layer is 10 ⁻² to 10 ³
Ωcm is preferred. The measurement environment of the coating layer is as follows. Under conditions of 20 to 25 ° C. and 50 to 60% RH, 100
A coating layer having a thickness of 7 to 20 μm is formed on a PET sheet having a thickness of μm, and the coating layer is measured by a four-terminal probe method using a resistivity meter Loresta AP or Hiresta IP (manufactured by Mitsubishi Yuka). It is also preferable to add carbonized or graphitized spherical particles to the coating liquid for the coating layer in order to prevent the durability of the sleeve from being reduced. The carbonized or graphitized spherical particles are preferably carbon microbeads (PC) manufactured by Nippon Carbon Co., Ltd. In this embodiment, those having an average particle diameter of 3 to 15 μm and a resistance of 10 ^-6 to 10 ³ Ωcm are preferred.

In the preparation of the above-mentioned PC, when preparing spherical particles to be contained in the coating solution for the coating layer of the developing sleeve, the number average particle size of 3 μm is determined based on 100 parts by mass of the spherical phenol resin having a number average particle size of 7 to 12 μm. 10 to 20 parts by mass of the following coal-based bulk mesophase pitch powder is uniformly dispersed using a raikai machine (automatic mortar, manufactured by Ishikawa Kogyo Co., Ltd.) or the like, and then heat-stabilized in an oxidizing atmosphere, and then 150 to 3 parts.
Spherical conductive carbon particles (conductive spherical particles) obtained by graphitization by baking at 00 ° C. can be used. Hereinafter, preparation of a coating liquid for a coating layer to which conductive spheres are added will be described.

Zirconia beads having a diameter of 1 mm are added as media particles to the material (phenol resin, conductive substance, etc.) used for the coating layer, dispersed in a sand mill for 2 hours, separated using a sieve, and coated. A stock solution for a layer is obtained, and the conductive spherical particles are added in an amount of 1 to 5 parts by mass with respect to 100 parts by mass of the stock solution of the conductive coating layer, and isopropyl alcohol is added so that a solid concentration becomes 25 to 40% by mass. After that, the mixture was dispersed for 1 hour using glass beads having a diameter of about 3 mm, and the glass beads were separated using a sieve.
A coating liquid for a coating layer can be obtained.

The first developing sleeve is rotated at a speed of 100 to 175% with respect to the photosensitive drum as the image carrier. The layer thickness of the toner is regulated by the first magnetic blade 4aa,
The B gap is preferably 150 to 300 μm.

The structure of the first magnetic blade 4aa is preferably a ferromagnetic iron (SPCC-SD) obtained by applying KN plating to 3 to 6 μm and having a blade thickness of 0.1 to 2.0 mm. The toner coating amount on the first developing sleeve is 0.4
~ 1.7 mg / cm ² is preferred. The distance SD gap between the first developing sleeve 4a and the photosensitive drum is 120 to 300 μm.
Is preferred. As the first developing bias, for example, +20
Magnetic one-component non-contact development is performed using a DC bias of 0 V, a rectangular wave of Vpp 1200 V and a frequency of 2.5 kHz as an AC bias.

It is preferable that the second developing sleeve 4b also has the same structure, configuration, and the like as the first developing sleeve 4a, and uses the same developing bias. As a result, there is an advantage that the cost can be reduced because only one power supply is used, and a space for the power supply can be reduced. In addition, by making the first and second development conditions the same as much as possible, correction can be made in the case where the density changes due to the environment or durability.

The developing pole of the first developing sleeve is N2,
The developing pole of the second developing sleeve is N2, and it is preferable that the magnetic force and the half width are the same. The upstream side with respect to the rotation direction of the image carrier is referred to as first development, and the downstream side is referred to as second development.
Since the developing means in the image forming apparatus of the present invention has a configuration in which two developing sleeves are provided, as shown in FIG. 14, after the developing is performed by the first developing sleeve upstream in the rotation direction of the image carrier. The toner image A on the photoreceptor is in the state of the schematic diagram, whereas the toner image A is B after passing through the second developing sleeve nip downstream in the rotation direction of the image carrier, and has a thin layer as shown in the schematic diagram. In addition, it is possible to eliminate the toner swelling at the edge portion due to the edge effect in the non-contact development at the image contour portion. This is because the toner image on the photosensitive member is rearranged by the second developing sleeve. The fact that the initial state of the toner image is on the photoreceptor is fundamentally different from the case of developing with the first developing sleeve. Furthermore, the toner becomes faithful to the electrostatic latent image on the photoreceptor, and excess toner can be collected in the second developing sleeve. This makes it possible to obtain a high-quality image with less toner scattering around the image area even by recharging after the development process. This also reduces the toner consumption by collecting waste toner at the image edge portion by the second developing sleeve.

The constructions of the first developing sleeve and the second developing sleeve may not be the same. For example, as shown in FIG. 15, instead of using a second magnetic blade that regulates the toner coating amount, a second developing sleeve downstream of the image carrier in the rotation direction of the image carrier is replaced with a first developing sleeve and a second developing sleeve. By arranging them at appropriate intervals, the toner coating amount can be regulated by the first developing sleeve upstream with respect to the rotation direction of the image carrier, whereby space can be saved. However, when the toner coating amount of the second developing sleeve is regulated by the first developing sleeve, the toner coating amount of the second developing sleeve may be defective due to too high a charging characteristic for the toner.

In this case, when the coating layer is provided on the developing sleeve in the production of the second developing sleeve, it is preferable to add the following additives only to the coating liquid for the coating layer for the second developing sleeve. When the toner is negatively chargeable, a quaternary ammonium salt compound represented by the following general formula (I) is used as an additive.

[0098]

Embedded image ^{(R 1, R 2, R} 3, R 4 in the formula which may have a substituent an alkyl group, an optionally substituted aryl group, an aralkyl group, R ¹ to R ⁴ good be the same or different from each .X ^-, in represents an anion of an acid) the general formula (I), X ^-. the acid ion, organic sulfate ion, organic sulfonate ions, organic Phosphate ions, molybdate ions, tungstate ions, heteropoly acids containing molybdenum atoms or tungsten atoms, and the like can be given. Preferred quaternary ammonium salt compounds include those represented by the following general formulas (1) to (8), but are not limited thereto in the present invention.

[0099]

Embedded image When a phenolic resin to which a specific quaternary ammonium salt compound used in the present invention is added, or an amide-based resin such as polyamide or polyurethane is used, when the binder resin is cured by heating to form a coating layer, An ammonium salt compound is incorporated into the structure of the binder resin. For this reason, the charge-up prevention characteristic for the negatively chargeable toner is improved not as a part but as the whole coating layer.

In the production process, when the phenolic resin constituting the binder resin used in the present invention is produced by using a nitrogen-containing compound as a catalyst, particularly when heated and cured, quaternary ammonium is used. The salt compound is easily incorporated into the structure of the phenol resin, and is preferable for preventing charge-up of the toner. Therefore, in the present invention, a phenol resin produced by using a nitrogen-containing compound as a catalyst in the production process having such an action is one of the materials constituting the coating layer on the developer carrier.
If one is used, it is possible to realize a developing device that prevents toner charge-up.

Examples of the nitrogen-containing compound which can be suitably used in the present invention and which is used as a catalyst in the process of producing a phenolic resin include, for example, an acidic catalyst such as ammonium sulfate, ammonium phosphate, ammonium sulfamate, ammonium carbonate, ammonium acetate; Examples include ammonium salts or amine salts such as ammonium maleate, and examples of the basic catalyst include ammonia or dimethylamine, diethylamine, diisopropylamine, diisobutylamine, diamylamine, trimethylamine, triethylamine, tri-n-butylamine, triamylamine, and the like. Dimethylbenzylamine, diethylbenzylamine, dimethylaniline, diethylaniline,
N, N-di-n-butylaniline, N, N-diamylaniline, N, N-dit-amylaniline, N-methylethanolamine, N-ethylethanolamine, diethanolamine, triethanolamine, dimethylethanolamine, Diethylethanolamine, ethyldiethanolamine, n-butyldiethanolamine, di-n-butylethanolamine, triisopropanolamine,
Amino compounds such as ethylenediamine, hexamethylenetetramine, pyridine, α-picoline, β-picoline, γ
Pyridine and derivatives thereof such as picoline, 2,4-lutidine and 2,6-lutidine, quinoline compounds, imidazole, 2-methylimidazole, 2,4-dimethylimidazole, 2-ethyl-4-methylimidazole, 2-phenyl Nitrogen-containing heterocyclic compounds such as imidazoles and derivatives thereof such as imidazole, 2-phenyl-4-methylimidazole and 2-heptadecylimidazole.

On the other hand, the same compounds and additives as described above can be used for the coating layer of the developing sleeve when a positively chargeable toner is used. This is because a negatively chargeable toner is easily charged up due to its material, so a charge-up prevention sleeve is required, whereas a positively chargeable toner tends to be undercharged. This is to obtain an appropriate charging property. A quaternary ammonium salt compound is added to the negatively chargeable toner sleeve,
0 to 100 parts by mass of binder resin such as phenolic resin
30 parts by mass, 20 to the positively chargeable toner sleeve
It is preferable to add 40 parts by mass.

It is preferable that the image forming apparatus of the present invention uses an amorphous silicon photosensitive member which is sensitive to the cause of image quality deterioration as an image carrier, since good image quality can be obtained. The a-Si-based photoreceptor used in the present invention includes a conductive support made of Al or the like, and a photosensitive layer (a charge injection blocking layer and a photoconductive material exhibiting photoconductivity) sequentially deposited on the surface of the conductive support. Layer) and a surface layer. Here, the charge injection blocking layer is for preventing charge injection from the conductive support into the photoconductive layer, and is provided as necessary. The photoconductive layer is made of an amorphous material containing at least silicon atoms, and exhibits photoconductivity. Further, the surface layer contains silicon atoms and carbon atoms (and, if necessary, hydrogen atoms and / or halogen atoms), and has a capability of retaining a visible image in an image forming apparatus. An example of a procedure for actually forming the photoconductor of the present invention using an aluminum alloy cylinder as a conductive support will be described. First, an aluminum alloy cylinder tube is set in a tube expansion device. Then, compressed air is introduced into the urethane rubber for tube expansion located inside the cylinder, and the tube is expanded by applying a pressure of about 300 kgf / cm ² to the cylinder. The expanded aluminum alloy cylinder tube is set on a lathe with an air damper for precision cutting so as to obtain a rake angle of 5 ° with respect to the cylinder center angle. Then, the support was vacuum-chucked to the rotating flange of the lathe, and the peripheral speed was 1000 m / min while simultaneously using white kerosene spraying from the attached nozzle and cutting powder suction from the attached vacuum nozzle.
Under the condition of a feed rate of 0.01 mm / R, mirror cutting is performed so that the outer shape becomes 108 mm. After the cutting is completed, the surface of the support is processed by the support cleaning device.

Next, the apparatus for forming a photoconductive member deposited film by microwave plasma CVD on the surface of the conductive support having been subjected to the pipe expanding, cutting and cleaning processes is used.
A deposited film mainly composed of a-Si is formed. First, the reaction vessel is evacuated by a vacuum pump through an exhaust pipe, and the pressure in the reaction vessel is adjusted to 1 × 10 ⁻⁷ Torr or less. Next, the temperature of the support is heated and maintained at a predetermined temperature by a heater. Therefore, the source gas is supplied to the a-Si
A raw material gas such as silane gas as a raw material gas, diborane gas as a doping gas, and helium gas as a diluting gas is introduced into the reaction vessel. Simultaneously therewith, a microwave having a frequency of 2.45 GHz is generated by a microwave power supply and introduced into the reaction vessel through a waveguide and a dielectric window. Further, a DC voltage is applied to the support to the bias electrode by a DC power supply electrically connected to the bias electrode in the discharge space. Thus, in the discharge space surrounded by the conductive support, the raw material gas is excited by microwave energy and is difficult to dissociate, and furthermore, the source gas is constantly ionized on the conductive support by the electric field between the bias electrode and the support. While receiving the impact, a deposited film is formed on the surface of the support. At this time, the rotating shaft on which the conductive support is installed is rotated by a motor, and the conductive support is rotated around the central axis in the direction of the support genera, thereby uniformly depositing the entire circumference of the conductive support. Form a film layer.

Although the manufacturing cost of the a-Si drum as described above is high, the latent image formation is relatively faithful to the exposure energy distribution, so that the image quality is high, and the overwhelming durability results in a unit. The printing cost is reduced, and it can be said that the image carrier is an ideal image carrier for a high-speed image forming apparatus.

[0106]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below.

[0107]

Example 1 <1> Production of Toner Materials and methods for producing a toner used in this example will be described in detail below.・ Binder resin (polyester resin) 100 parts by mass (Tg 60 ° C., acid value 20 mg KOH / g, hydroxyl value 30 mg KOH / g, molecular weight: Mp7000, Mn3000, Mw55000) ・ Magnetic iron oxide 90 parts by mass (average particle size 0.14 μm, characteristics in 795.8 kA / m magnetic field ^{Hc9.2kA / m, σs8 2Am 2 /kg,σr11.5Am} 2 / kg) · charge control agent resin 2 parts by mass low molecular weight ethylene - propylene copolymer 3 parts by weight of the The ingredients of the formulation were mixed with a Henschel mixer (FM-75).
After mixing well with a mold and a Mitsui Miike Kakoki Co., Ltd.), the mixture was kneaded using a twin-screw kneader (PCM-30, manufactured by Ikegai Iron Works Co., Ltd.) set at a temperature of 130 ° C. The obtained kneaded material was cooled and coarsely pulverized to 1 mm or less with a hammer mill to obtain a coarsely pulverized material, thereby obtaining a powder material (coarse pulverized material) as a powder material for toner production.

Next, pulverization is performed by the same mechanical pulverizer as shown in FIG. 5 described in the detailed description. The mechanical pulverizer used in the present invention is Turbo Mill T
-250 type was used. Table type first metering machine 31
From 5, a powder raw material composed of a coarsely pulverized product was charged at a rate of 20 kg / h through a powder inlet 311.

As cooling means inside the mechanical pulverizer main body,
The mechanical pulverizer had a structure having a jacket structure 316, and the cooling water was passed through. With the above-described cool air device and jacket structure, the room temperature T1 in the spiral chamber 212 communicating with the powder inlet in the mechanical pulverizer was set to −10 ° C. The room temperature T2 of the rear chamber 320 of the mechanical pulverizer was 46 ° C.

The peripheral speed of the tip of the rotating rotor 314 is set to 11
It was 5 m / s. The minimum distance between the rotor 314 and the stator 310 was 1.5 mm.

The finely pulverized material A obtained by pulverizing with the above mechanical pulverizer 301 has a weight average particle size of 7.5 μm, 48.3% by number of particles having a particle size of 4.0 μm or less, and It had a sharp particle size distribution containing 9.2% by volume of particles having a particle size of 10.1 μm or more. Next, the toner pulverized as described above was classified using a multi-division airflow classifier as shown in FIG.

The pressure in the classification chamber is reduced through the outlets 21, 22 and 23, and the air flow flowing by the reduced pressure in the raw material supply nozzle 26 having an opening in the classification chamber and the compressed air injected from the high pressure air supply nozzle 51. Is ejected from the second quantitative feeder 53 into the classifying chamber through the fine pulverized material supply port 50 and the finely pulverized material supply nozzle 26 at the speed of 200 m / sec. Classification was performed to obtain fine powder, medium powder, and coarse powder. The finely pulverized product was introduced into the air-flow classifier at a rate of 20 kg / h. Outlet 21
The larger discharged particles (coarse powder) are again introduced into the mechanical pulverizer and reused.

A toner was prepared by externally adding 1.0 part by mass of hydrophobic silica fine powder (BET 300 m ² / g) to 100 parts by mass of the medium powder using a Henschel mixer.

The toner thus obtained has a weight average particle size of 7.4 μm, and a particle size of 4.0 μm or less has a particle size of 15.0.
The toner has a sharp particle size distribution containing 6.6% by volume of particles having a particle diameter of 10.1 μm or more. Particles with a circularity a = 0.900 or more accounted for 96.2% by number, and particles with a circularity a = 0.950 or more accounted for 78.2% by number. The particle concentration A before cutting particles having a size of 3 μm or less (all particles) is 14702.3 number /
μl, and the measured particle concentration B of 3 μm or more is 12921.
4 pieces / μl. The cut ratio was 12.1.

FIG. 12 shows a particle size distribution, circularity distribution and circle equivalent diameter graph measured by FPIA1000.

The coverage of the magnetic material on the toner surface obtained as described above was 35%. <2> Image Evaluation The toner obtained above was subjected to image evaluation using the same image forming apparatus shown in FIG. 1 as described in the embodiment.

An amorphous silicon photosensitive drum was used as an image carrier. The developing means has two developing sleeves each having therein a fixed magnet having a magnetic field pattern as shown in FIG. 13, and includes first and second developing sleeves 4a and 4b.
Used was a nonmagnetic member made of aluminum A2017 having a diameter of 20 mm, blasted with FGB # 300 thereon, and provided with a coating layer.

The coating layer of the developing sleeve was coated on a surface of the aluminum sleeve with a coating liquid having a thickness of 10 μm, in which 90 parts by mass of crystalline graphite and 10 parts by mass of carbon were mixed with 250 parts by mass of phenol resin. Molded by curing in a ℃ environment. P / B ratio is 1 /
2.5. Thereafter, the sleeve surface was polished once with 3 cm of wrapping tape (# 3000) at a pressure of 1.5 kg. The two developing sleeves were rotated at a speed of 150% with respect to the photosensitive drum. The layer thickness of the toner is regulated by a magnetic blade, and the SB gap is 2
It was 50 μm. Distance S between developing sleeve and photosensitive drum
−D gap is 200 μm each, DC bias of +200 V, Vpp 1200 V, frequency 2.5
A rectangular wave of kHz was applied as an AC bias to perform magnetic one-component non-contact development. The amount of toner coating on the sleeve was about 1.0 mg / cm ² .

When the image was formed by the above-described image forming apparatus, it was found that the toner had a proper coverage of the magnetic material on the toner surface, so that the resistance distribution on the toner surface became appropriate. A good image was obtained without scattering of the toner due to repulsion between the toners due to the electrification.

[0120]

Example 2 The diameter of the magnetic material was changed (average particle diameter 0.05 to
Except for 0.30 μm), a toner was manufactured in the same manner as in Example 1 to obtain a toner having a different magnetic material coverage on the toner surface. When the diameter of the magnetic material is reduced, the area occupancy of the toner surface per magnetic material is reduced, but is very small. On the other hand, as the diameter decreases, the number increases for the same mass, and the effect of the increase in the number of magnetic substances existing on the toner surface is much greater. Therefore, when the diameter of the magnetic material is reduced,
The magnetic material area abundance on the toner surface increases. Although the resistance of the toner surface is made uniform, the coverage of the magnetic material on the toner surface is increased. The magnetic material on the toner surface oxidizes,
Since the toner becomes reddish by becoming reddish, scattering and blackness are evaluated as well as the coverage of the magnetic material on the toner surface.

In this example, NP6750 manufactured by Canon Inc. was used.
Was modified and an evaluation was performed using an image forming apparatus shown in FIG. 1 in which two developing sleeves were used. At this time, the diameter of the sleeve was 20 mm. Table 1 summarizes the evaluation results. The evaluation was performed according to the following criteria. (Splattering) ：: Scattering around characters is slightly observed at a microscope observation level, but hardly noticeable. ：: Cannot be determined by visual observation. Δ: Visual observation discrimination is possible, but characters are not seen. ×: Characters can be easily distinguished by visual observation, and characters can be seen. (Blackness) ：: C ^* ≦ 1 Pure black. ： １: 1 <C ^* ≦ 3 Black by visual observation. Δ: 3 <C ^* ≦ 7 Black which is visually brownish. ×: C ^* > 7 Not black. The above C ^* (saturation) is a value calculated by the following equation (7).

[0122]

(Equation 21) The smaller the value of C ^* , the less the color tone and the color becomes black and white. C ^* is
It was quantitatively measured based on the color system definition defined by the International Commission on Illumination (CIE) in 1976. That is, a ^* ,
b ^* (a ^* and b ^* are chromaticities representing hue and saturation) and L ^* (brightness) were measured. X-rite spectrophotometer type for measurement
938 was used, the light source for measurement was C light source, and the viewing angle was 2 °. As a sample image, an image where L ^* = 20 was used.

[0123]

[Table 1] As shown in Table 1, by using the mechanical pulverized toner used in the present example, the resistance of the toner particle surface was made uniform, and a good image was obtained without the scattering phenomenon due to the repulsion of the toners. Obtained. Because of mechanical grinding,
Good transfer, development, and toner productivity were obtained with high circularity, and an image with extremely good scattering and blackness could be obtained.

[0124]

Example 3 A toner was prepared in the same manner as in Example 1 by using the following magnetic materials and changing the amount of the magnetic material used (70 to 150 parts by weight of the magnetic material with respect to 100 parts by weight of the binder resin of the toner). By manufacturing, toners having different magnetic material coverages on the toner particle surfaces were obtained. Magnetic iron oxide used (average particle size: 0.22 μm, characteristics Hc at 795.8 kA / m magnetic field Hc: 9.2 kA / m, σs: 82 Am ² / kg, σr: 11.5 Am ² / k
g) The experimental method and the evaluation method were the same as in Example 2. Table 2 shows the results.

[0125]

[Table 2]

[0126]

Embodiment 4 A toner is manufactured in the same manner as in Embodiment 1 using the following magnetic materials. When the hydrophobic silica fine powder is externally added to the medium powder after the pulverization / classification step using a Henschel mixer, 0 to 5 parts by weight of the following magnetic iron oxide is externally added to 100 parts by weight of the medium powder. Thus, toners having different magnetic material coverages on the toner particle surfaces were obtained. Magnetic iron oxide (average particle size 0.22 μm, characteristics Hc at 795.8 kA / m magnetic field Hc 9.2 kA / m, σs 82 Am ² / kg, σr 11.5 Am ² / k
g) The experimental method and the evaluation method were the same as in Example 2. Table 3 shows the results.

[0127]

[Table 3]

[0128]

Fifth Embodiment In this embodiment, the first developing sleeve regulates the amount of toner coating on the second developing sleeve without using the second magnetic blade as the developing means having two developing sleeves. Developing means as shown in FIG. The same image forming apparatus as in Example 1 was used except for the developing unit.

Next, the developing means will be described.

As the first developing sleeve 4a, the same developing sleeve as that of the first embodiment was used and rotated at a peripheral speed ratio of 120% with respect to the photosensitive drum. The layer thickness of the toner was regulated by the first magnetic blade 4aa having a thickness of 1.0 mm, and the SB gap was set to 250 μm. The distance SD gap between the first developing sleeve 4a and the photosensitive drum was set to 250 μm, and the developing sleeve was subjected to magnetic one-component non-contact development in which a DC bias of +200 V, a Vpp of 1500 V, and a rectangular wave having a frequency of 2.7 kHz were applied as an AC bias. Do.

The second developing sleeve 4b has substantially the same structure as the first developing sleeve, except that the coating layer of the second developing sleeve is as follows.

A coating liquid for a coating layer containing graphitized spherical particles was used to prevent the durability of the sleeve from being lowered. As the spherical particles, carbon microbeads (PC) manufactured by Nippon Carbon Co., Ltd. having an average particle size of 5 μm and a resistance of 10 ⁻³ Ωcm were used. Coating containing 90 parts by mass of graphite having an average particle diameter of 6.5 μm, 10 parts by mass of carbon, and 70 parts by mass of a quaternary ammonium salt compound represented by the general formula (I) based on 250 parts by mass of a phenol resin. Zirconia beads having a diameter of 1 mm are added as media particles to the layer coating solution,
The mixture is dispersed in a sand mill for 2 hours, and the zirconia beads are separated using a sieve to obtain a stock solution. 10 parts by mass of the above spherical particles were added to 100 parts by mass of the stock solution of the coating layer, isopropyl alcohol was added so that the solid content concentration became 32%, and then dispersed using glass beads having a diameter of 3 mm for 1 hour. The glass beads were separated using a sieve to obtain a coating solution.

Using this coating solution, a coating layer having a coating width of 216 mm was formed on an aluminum cylindrical tube having an outer diameter of 16 mm by a spraying method, and then a hot air drying furnace was used to form a coating layer at 150 ° C.
The conductive coating layer was cured by heating for 0 minutes to obtain a second developing sleeve. Inside it, there is a magnet having a four-pole magnetic field pattern. + 200V for developing sleeve 4b
And a rectangular wave having a Vpp of 1500 V and a frequency of 2.7 kHz. Since it is the same as the first developing sleeve, it is common and only one power supply is required. The developing sleeve 4b was rotated at a speed of 120% with respect to the photosensitive drum.

The distance between the first developing sleeve 4a and the second developing sleeve 4b was set to 500 μm. This is a value for making the amount of toner supplied to the first and second developing sleeves equal. Thus, the toner coat amount (M / S) on the sleeve was set to about 1.0 mg / cm ² . The SD gap of the second developing sleeve is 250 μm.

As a result of performing image evaluation in the same manner as in Example 1 by using the image forming apparatus having the above-described configuration, not only space saving was achieved by using the above-described developing device configuration, but also 1 equivalent effects were obtained.

[0136]

According to the present invention, the transfer efficiency is improved by making the toner particles spherical, and the dot reproducibility is improved by making the diameter smaller, and the magnetic particles existing on the surface are improved. By using a toner having a uniform resistance on the surface of the toner particles by optimizing the amount, it is possible to provide an image forming apparatus capable of obtaining a good image without a scattering phenomenon due to repulsion of the toners.

Further, by manufacturing a toner using a mechanical pulverizer and a multi-split air classifier, the manufacturing method is not difficult even when the diameter of the toner is reduced, and the productivity is low and easy. And a toner excellent in toner quality.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing one embodiment of an image forming apparatus of the present invention.

FIG. 2 shows a flowchart of toner preparation in a mechanical pulverization step, which is one preferred step of the method for producing a toner in the present invention.

FIG. 3 shows a flowchart of toner preparation in a mechanical pulverization step, which is one step of a preferred method for producing a toner in the present invention.

FIG. 4 is a schematic view of a mechanically pulverized multi-split air classifier used in the toner production method of the present invention.

FIG. 5 is a schematic view of a mechanical pulverizer of mechanical pulverization used in the toner production method of the present invention.

FIG. 6 is a schematic sectional view taken along the line DD ′ in FIG. 5;

FIG. 7 is a perspective view of the rotor 314 shown in FIG.

FIG. 8 is a schematic sectional view of a conventional image forming apparatus.

FIG. 9 is a flowchart illustrating a process of preparing air-pulverized toner as a conventional toner manufacturing method.

FIG. 10 is a schematic view of an air pulverizing collision type air current pulverizer used in a conventional toner manufacturing method.

FIG. 11 is a schematic view of an air-pulverized airflow classifier used in a conventional toner manufacturing method.

FIG. 12 is a graph showing the particle size distribution, circularity, and equivalent circle diameter of the toner used in the embodiment of the present invention.

FIG. 13 is a cross-sectional view illustrating one embodiment of a developing device used in the image forming apparatus of the present invention.

FIG. 14 is a schematic diagram of a toner image on an image carrier of the image forming apparatus of the present invention.

FIG. 15 is a cross-sectional view illustrating one embodiment of a developing device used in the image forming apparatus of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Image carrier 2 Charging device 4 Developing device 4a, 4b Developing sleeve 8 Transfer charging device 9 Transfer material 10 Pre-transfer charging device 11 Cleaning device 13 Fixing device 20 Multi-classifier 21, 22, 23 Outlet 24 Inlet pipe 25 Vibration Feeder 26 Finely pulverized material supply nozzle 27, 28 Classification edge 34, 35 Classification edge block 37 Multi-segment airflow classifier 40 Classification area 42 Classification room 50 Finely pulverized material supply port 51 High pressure air supply nozzle 52 Finely pulverized material introduction nozzle 53 2 fixed-quantity feeder 161 high-pressure gas supply nozzle 162 acceleration tube 163 acceleration tube outlet 164 collision member 165 powder raw material supply port 166 collision surface 167 pulverized material discharge port 168 pulverization chamber 212 spiral chamber 220 distributor 222 bag filter 224 suction filter 229 collection Cyclone 301 mechanical crusher 3 2 powder outlet 311 powder inlet 315 first metering feeder

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G03G 15/08 507 G03G 9/08 381 15/09 15/08 507L F-term (Reference) 2H005 AA08 AA15 AB04 CB13 EA05 EA10 FA06 2H031 AC10 AC11 AC29 AD03 BA03 2H077 AD06 AD14 AD16 AD36 EA13 EA16 EA21 FA13 FA27

Claims (7)

[Claims] An image carrier; a charging unit configured to apply a voltage to a charging member to charge the image carrier; and an electrostatic latent image forming unit configured to form an electrostatic latent image on the charged image carrier. Image forming apparatus comprising: developing means for transferring toner to an electrostatic latent image formed on the image carrier to visualize and form a toner image; and transferring means for transferring the toner image to a transfer material. An apparatus, wherein the developing unit is a non-contact developing unit having a plurality of developer carriers having a magnetic member therein, and applying an AC bias to each developer carrier. Toner particles containing at least a resin and a magnetic material. The toner has a weight average particle diameter of 5.0 to 12.0 μm, and the toner particles having a circle equivalent diameter of 3 μm or more have the following formula (1) ) Is 0.900.
The above particles have 90% or more in terms of the number-based cumulative value, and circularity a = L0 / L (1) (L0: circumference of a circle having the same projection area as the particle image, L:
An image forming apparatus characterized by satisfying the following (a) and (b) or (a ′) and (b). (A) The relationship between the cut rate Z and the weight average particle size X of the toner satisfies the following equation (2): ## EQU2 ## The cut rate Z ≦ 5.3 × X (2) (where the cut rate Z is When the particle concentration of all measured particles measured by the flow particle image analyzer FPIA-1000 manufactured by Toa Medical Electronics is A (number / μl), and the measured particle concentration with a circle equivalent diameter of 3 μm or more is B (number / μl). (3) Z = (1−B / A) × 100 (3)) and the number-based cumulative value Y of the particles having a circularity of 0.950 or more.
And the weight average particle size X of the toner satisfies the following expression (4). Y ≧ exp 5.51 × X ^−0.645 (4) (where the weight average particle size X of the toner is 5.0 to 12.0 μm)
m. (A ′) The relationship between the cut rate Z and the weight average particle diameter X of the toner satisfies the following equation (2 ′), and the cut rate Z> 5.3 × X (2 ′) and the circularity Number-based cumulative value Y of particles of 0.950 or more
And the weight average particle size X of the toner satisfies the following expression (4 ′). Y ≧ exp 5.37 × X ^−0.545 (4 ′) (where the weight average particle size X of the toner is 5.0 to 12.0 μm)
m. (B) The coverage of the magnetic substance on the toner surface is 20%
As mentioned above, it is less than 45%. 2. The toner is produced through a melt kneading step, a pulverizing step, a fine pulverizing step, and a classifying step. In the melt kneading step, a mixture containing at least a binder resin and a magnetic material is used. Melt kneading to obtain a kneaded product, in the pulverizing step, after cooling the kneaded material, coarsely pulverized by a pulverizing means to obtain a coarsely pulverized product, and in the fine pulverizing step, attached to at least a central rotating shaft. A rotor formed of a rotating body, and a stator arranged around the rotor while maintaining a constant distance from the rotor surface, and an annular space formed by maintaining the distance is airtight. Into a mechanical pulverizer configured to be in a state, a powder raw material composed of the coarsely pulverized material is introduced from a first constant feeder of the mechanical pulverizer through a powder introduction port, Type crusher The powder raw material is finely pulverized by rotating the rotor at a high speed, and the weight average particle diameter is 5.0 to 12.0 μm, and particles having a particle diameter of 4.0 μm or less are 70% by number or less. A finely pulverized material having particles having a diameter of 10.1 μm or more of 25% by volume or less is produced. And then introduced into a multi-divided airflow classifier that classifies air using the crossed airflow and Coanda effect, and in the multi-divided airflow classifier, the finely pulverized material is at least fine powder, medium powder and coarse powder. Classified into a body, the classified coarse powder is mixed with a new powder raw material, and introduced into the mechanical pulverizer again to perform the pulverizing step and the classifying step. The image forming apparatus according to claim 1, wherein the image forming apparatus generates the image. 3. The multi-divided air flow classifier includes an upper surface portion of the multi-divided air flow classifier, the fine pulverized material supply nozzle, the finely pulverized material introduction nozzle for introducing the finely pulverized material, and the high-pressure air supply nozzle. Wherein the classification edge block having a classification edge in the multi-split airflow classifier is a multi-split airflow classifier whose position can be changed so that the shape of the classification area can be changed. Item 3. The image forming apparatus according to Item 2. 4. The image forming apparatus according to claim 1, wherein a coverage of the magnetic material on the surface of the toner is 30% or more and less than 40%. 5. The image forming apparatus according to claim 1, wherein said image carrier is made of amorphous silicon. 6. The developer carrier according to claim 1, wherein the regulation of the developer layer thickness of the downstream developer carrier with respect to the rotation direction of the image carrier is performed by the upstream developer carrier. Item 2. The image forming apparatus according to Item 1. 7. The image forming apparatus according to claim 1, wherein the toner has at least the toner particles and inorganic fine powder.