JP2866257B2 - Magnetic developer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a magnetic developer for visualizing a latent electrostatic image in an image forming method such as electrophotography and electrostatic recording.

[0002]

2. Description of the Related Art As a conventional electrophotographic method, US Pat.
297,691, Japanese Patent Publication No. 42-23910 (U.S. Pat. No. 3,666,363) and Japanese Patent Publication No. 43-24748 (U.S. Pat. No. 4,071,3).
61), a number of methods are known. Generally, a photoconductive substance is used to form an electric latent image on a photoreceptor by various means. The latent image is developed with a toner to form a visible image, and if necessary, a toner image is transferred to a transfer material such as paper, and then fixed by heating, pressure, or the like to obtain a copy.

Various developing methods for visualizing an electrostatic latent image using toner have been known. For example, U.S. Pat.
No. 4,063, the magnetic brush method, the cascade developing method described in 2,618,552, and the powder described in 2,221,776. Cloud method, fur brush development method,
Many developing methods such as a liquid developing method are known. Among these developing methods, a magnetic brush method, a cascade method, a liquid developing method and the like using a developer mainly composed of a toner and a carrier have been widely put to practical use. All of these methods are excellent methods for obtaining a good image relatively stably, but have the common problems associated with the two-component developer such as deterioration of the carrier and fluctuation of the mixing ratio of the toner and the carrier.

In order to solve such a problem, various developing methods using a one-component developer composed of only a toner have been proposed. Among them, many are excellent in a method using a developer composed of toner particles having magnetism.

[0005] US Pat. No. 3,909,258 proposes a method of developing using a magnetic toner having electrical conductivity. In this technique, a conductive magnetic toner is supported on a cylindrical conductive sleeve having magnetism therein, and is brought into contact with an electrostatic image for development. On this occasion,
In the developing section, a conductive path is formed by toner particles between the surface of the recording medium and the surface of the sleeve, and electric charges are guided to the toner particles from the sleeve via the conductive path, and due to the cloning force between the electrostatic image and the image section. The toner particles adhere to the image area and are developed. This developing method using a conductive magnetic toner is an excellent method that avoids the problems associated with the conventional two-component developing method.On the other hand, since the toner is conductive, the developed image can be transferred from a recording medium to plain paper or the like. There is a problem that it is difficult to transfer electrostatically to the final supporting member.

As a developing method using a high-resistance magnetic toner capable of electrostatic transfer, there is a developing method utilizing dielectric polarization of toner particles. However, such a method has a problem that the developing speed is essentially low and the density of a developed image is not sufficiently obtained, and is practically difficult.

As another developing method using a high-resistance insulating magnetic toner, toner particles are frictionally charged by friction between toner particles, friction between the toner particles and a sleeve or the like, and this is charged to an electrostatic image holding member. A method of developing by contact is known. However, these methods have problems that the number of times of contact between the toner particles and the frictional member is small and the triboelectric charging is apt to be insufficient, and the charged toner particles are liable to agglomerate on the sleeve due to the strong cloning force between the sleeve and the sleeve. And it was practically difficult.

However, Japanese Patent Application Laid-Open No. 55-18656 and the like have proposed a new jumping developing method which eliminates the above-mentioned problems. This involves applying a very thin coating of magnetic toner on a sleeve, triboelectrically charging it, and then developing it very close to the electrostatic image. This method increases the chance of contact between the sleeve and the toner by applying the magnetic toner on the sleeve very thinly, enables sufficient frictional charging, supports the magnetic toner by magnetic force, and keeps the magnet and toner relatively By moving the toner particles in a suitable manner, the toner particles can be aggregated with each other and sufficiently rubbed with the sleeve, thereby obtaining an excellent image.

However, in the developing method using the improved insulating toner, there are unstable factors relating to the insulating toner to be used. The reason is that, in the insulating toner, a considerable amount of fine powder-like magnetic charging characteristics are mixed and dispersed, and a part of the magnetic material is exposed on the surface of the toner particles. It affects the fluidity and triboelectricity of the toner, and as a result, causes fluctuations or deterioration of various characteristics required for the magnetic toner, such as development characteristics and durability of the magnetic toner.

More specifically, in a conventional jumping developing method using a magnetic toner containing a magnetic substance, if a long-term repeated developing process (for example, copying) is continued, the developer containing the magnetic toner is removed. Liquidity worsens,
Normal frictional electrification cannot be obtained, the electrification tends to be non-uniform, and fog development tends to occur in a low-temperature and low-humidity environment, which tends to be a major problem on toner images. Also,
When the adhesiveness between the binder resin constituting the magnetic toner particles and the magnetic charging characteristics is weak, the magnetic material is removed from the surface of the magnetic toner by the repeated development process, which has an adverse effect such as a decrease in toner image density. Tend.

When the dispersion of the magnetic substance in the magnetic toner particles is not uniform, small magnetic toner particles containing a large amount of the magnetic substance accumulate on the sleeve, resulting in a decrease in image density and a reduction in sleeve ghost. In some cases, the occurrence of so-called shading unevenness is observed.

Conventionally, proposals have been made regarding magnetic iron oxide contained in magnetic toners, but they still have points to be improved.

For example, JP-A-62-279352 proposes a magnetic toner containing a magnetic iron oxide containing a silicon element. Such magnetic iron oxide is
Although silicon element is intentionally present inside the magnetic iron oxide, there is still a point to be improved in the fluidity of the magnetic toner containing the magnetic iron oxide.

Japanese Patent Publication No. 3-9045 proposes that the shape of magnetic iron oxide is controlled to be spherical by adding a silicate. In the magnetic iron oxide obtained by this method, a large amount of silicon element is distributed inside the magnetic iron oxide because silicate is used for controlling the particle shape, and the amount of the silicon element on the surface of the magnetic iron oxide is small, Improved fluidity of magnetic toner, and high smoothness of magnetic iron oxide,
The adhesiveness between the binder resin constituting the magnetic toner and the magnetic iron oxide tends to be insufficient.

JP-A-61-34070 proposes a method for producing ferric oxide by adding a hydroxosilicate solution during the oxidation reaction to ferric oxide. Although triiron tetroxide according to this method has a Si element near the surface, the Si element exists in a layer near the surface of the triiron tetroxide, and the surface is vulnerable to mechanical shock such as friction. Have a point.

Further, in recent years, as image forming apparatuses such as electrophotographic copying machines have become widespread, their uses have been diversified and the demands on the image quality have become strict. 2. Description of the Related Art In copying images such as ordinary documents and books, it is required to reproduce very finely and faithfully without crushing or breaking even fine characters. In particular,
When the latent image on the photoreceptor of the image forming apparatus is a line image having a size of 100 μm or less, conventional developers generally have poor fine line reproducibility, and the line image is not yet sufficiently sharp. Recently, in an image forming apparatus such as an electrophotographic printer using digital image signals, a latent image is formed by collecting a fixed unit of dots, and a solid portion, a halftone portion, and a light portion have a dot density. It is expressed by changing. However, in a state where the toner particles do not adhere to the dots and the toner particles protrude from the dots, it is not possible to obtain the gradation of the toner image corresponding to the dot density ratio of the black portion and the white portion of the digital latent image. There is a problem. Further, when the resolution is improved by reducing the dot size in order to improve the image quality, the reproducibility of a latent image formed from minute dots becomes more difficult, and the resolution and gradation are poor. Images tend to be poor.

Although the image quality is good in the initial stage, the image quality may be deteriorated while printing is continued. This phenomenon is considered to be caused by the fact that only the toner particles that are easily developed are consumed first while the printout is continued, and the toner particles having poor developability accumulate and remain in the developing machine.

Some developers have been proposed for the purpose of improving the image quality. JP 5
Japanese Patent Application Laid-Open No. 1-3244 proposes a non-magnetic toner intended to improve the image quality by regulating the particle size distribution. The toner is mainly composed of a toner having a particle size of 8 to 12 μm, and is relatively coarse. According to the study of the present inventors, it is difficult for the toner to have a dense “glue” to a latent image, In addition, from the characteristic that 5 μm or less is 30% by number or less and 20 μm or more is 5% by number or less, there is a tendency that the particle size distribution is broad and the uniformity is lowered.
In order to form a clear image using such a coarse toner particle and a toner having a broad particle size distribution, it is necessary to fill the gap between the toner particles by thickly overlapping the toner particles. There is also a problem that it is necessary to increase the image density, and the amount of toner consumption required to obtain a predetermined image density increases.

Japanese Unexamined Patent Publication (Kokai) No. 54-72054 proposes a non-magnetic toner having a sharper distribution than the former, but the size of particles having an intermediate weight is 8.5 to 8.5.
There is still room for improvement as a 11.0 μm coarse and high-resolution toner.

Japanese Patent Application Laid-Open No. 58-129439 proposes a non-magnetic toner having an average particle diameter of 6 to 10 μm and a maximum number of particles of 5 to 8 μm. However, images with low sharpness tend to be formed.

According to the study of the present inventors, toner particles having a size of 5 μm or less clearly reproduce the outline of the latent image and have a main function of “glue” of the dense toner over the entire latent image. Was found. In particular, in the electrostatic latent image on the photoreceptor, due to the concentration of lines of electric force, the contour edge portion has a higher electric field strength than the inside, and the sharpness of the image quality is determined by the quality of the toner particles collected in this portion. According to the study of the present inventors, it has been found that the amount of particles of 5 μm or less is effective in solving the problem of sharpness of image quality.

Further, US Pat. No. 4,299,900 proposes a jumping development method using a developer having 10 to 50% by weight of a magnetic toner of 20 to 35 μm. In other words, the toner particle size suitable for frictionally charging the magnetic toner, uniformly and thinly applying the toner layer on the sleeve, and further improving the environmental resistance of the developer has been devised. However, there is a need for improvements that can meet more stringent requirements such as fine line reproducibility, resolution, and compatibility with the reversal development system.

Further, in such a method using a dry developer, a fine silica powder has conventionally been added to and mixed with a toner powder in order to form a visible image having good image quality. However, since the silica fine powder is hydrophilic as it is, the developer to which it is added causes aggregation due to the moisture in the air to reduce the fluidity, and in extreme cases, the developer due to the moisture absorption of the silica fine powder. The charging performance of the device is reduced. Therefore, use of silica fine powder which has been subjected to hydrophobic treatment is disclosed in JP-A-46-5782 and JP-A-48-48948.
-47345, JP-A-48-47346, and the like. Specifically, it is a method of reacting a silicic acid fine powder with a silane coupling agent to replace the silanol group on the surface of the silicic acid fine powder with another organic group to make the surface hydrophobic, and the silane coupling agent is, for example, dimethyldichloromethane. Silane, trimethylalkoxysilane and the like are used.

Further, in order to sufficiently perform the hydrophobic treatment,
After being treated with a silane coupling agent, D / 2
Japanese Patent Application Laid-Open No. 63-13936 discloses the use of silica fine powder which is treated with 5 ± D / 30 parts by weight (D: specific surface area of silica fine powder) and has a hydrophobicity of 90% or more.
7 and JP-A-63-139369.

On the other hand, in recent years, the functions of image forming apparatuses using electrophotography such as copiers and laser printers have been diversified, and the toner has been reduced in particle size for the purpose of higher definition and higher image quality. Conventionally, it has been more difficult to uniformly charge the toner, and it has been required to further increase the uniform chargeability of the toner.

[0026]

SUMMARY OF THE INVENTION An object of the present invention is to provide a magnetic developer which has solved the above-mentioned problems.

Further, an object of the present invention is to provide a high image density,
An object of the present invention is to provide a magnetic developer having excellent image reproducibility.

It is a further object of the present invention to provide a magnetic developer which has no fog even when used for a long time and has a stable charging performance.

It is a further object of the present invention to provide a magnetic developer which is not easily affected by large environmental changes such as low temperature, low humidity, high temperature and high humidity.

It is a further object of the present invention to provide a magnetic developer capable of faithfully developing a digital high-definition latent image and obtaining a clear, high-density image.

It is a further object of the present invention to provide a magnetic developer capable of obtaining a clear, high-density image in which the "glue" of the toner on the image portion is tight and the edge portion is sharp.

Another object of the present invention is to provide a magnetic developer capable of obtaining a high image density with a small consumption.

Another object of the present invention is to provide a high-resolution magnetic developer having excellent powder flow characteristics.

[0034]

Means and Functions for Solving the Problems The present invention (1)
Is a magnetic toner containing at least a binder resin and magnetic iron oxide, and a magnetic developer containing fine resin particles,
The magnetic toner has a weight average particle diameter of 13.5 μm or less, and a particle diameter distribution of 12.7 μm in the particle diameter distribution of the magnetic toner.
m or more, the content of the magnetic toner particles is 50% by weight or less, and the magnetic iron oxide has a silicon element content of 0.5 to 4% by weight based on the iron element; The ratio (B / A) × 100 of the content B of the silicon element present when the iron dissolution rate of the magnetic iron oxide is up to 20% by weight and the total content A of the silicon element of the magnetic iron oxide is 44 to 44%. 84%, and the ratio (C / A) × 100 of the content C of the silicon element existing on the surface of the magnetic iron oxide to the content A is 10 to 5
5%, and the resin fine particles have an average particle size of 0.03 to 0.03%.
A magnetic developer having a charging property of 2.0 μm and the same polarity as that of the magnetic toner.

The present invention (2) relates to a magnetic developer containing a magnetic toner containing at least a binder resin and magnetic iron oxide, wherein the magnetic iron oxide has a silicon element content of the magnetic iron oxide. , 0.5 to 4% by weight based on the iron element, the content B of the silicon element present when the iron dissolution rate of the magnetic iron oxide is up to 20% by weight, and the total amount of the silicon element of the magnetic iron oxide. The ratio (B / A) × 100 with the content A is 4
4 to 84%, and the ratio of the content C of the silicon element existing on the surface of the magnetic iron oxide to the content A (C / A) × 100
Is 10 to 55%, the magnetic toner has a weight average particle diameter of 6 to 8 μm, and contains 17 to 60% by number of magnetic toner particles having a particle diameter of 5 μm or less.
The magnetic toner particles having a particle size of 08 μm are contained in an amount of 5 to 50% by number, the magnetic toner particles having a particle size of 12.7 μm or more are contained in an amount of 2.0 vol% or less, and the magnetic toner particles having a particle size of 5 μm or less are as follows. Formula N / V = −0.05N + k [wherein, N represents the number% of magnetic toner particles having a particle size of 5 μm or less, V represents the volume% of magnetic toner particles having a particle size of 5 μm or less, k Indicates a positive number from 4.6 to 6.7. Here, N indicates a positive number of 17 to 60. ] Which is characterized by having a particle size distribution satisfying the following.

The present invention (3) provides a magnetic toner containing at least a binder resin and a magnetic iron oxide, and a magnetic developer containing a hydrophobic inorganic fine powder, wherein the magnetic iron oxide is formed of a magnetic iron oxide. The content of silicon element is 0.5 to 4% by weight based on the iron element, and the content B of silicon element existing when the iron element dissolution rate of the magnetic iron oxide is up to 20% by weight; The ratio (B / A) × 100 of iron to the total content A of silicon element is 44 to 84%, and the content C of silicon element present on the surface of the magnetic iron oxide and the content A
(C / A) × 100 is 10 to 55%, and the hydrophobic inorganic fine powder is a fine powder treated with silicone oil or silicone varnish, and the amount of carbon deposited by the treatment is 3 to 8 % By weight of the magnetic developer.

The present invention (4) relates to a magnetic toner containing at least a binder resin and a magnetic iron oxide, and a magnetic developer containing a hydrophobic inorganic fine powder, wherein the magnetic iron oxide is made of a magnetic iron oxide. The content of silicon element is 0.5 to 4% by weight based on the iron element, and the content B of silicon element existing when the iron element dissolution rate of the magnetic iron oxide is up to 20% by weight; The ratio (B / A) × 100 of iron to the total content A of silicon element is 44 to 84%, and the content C of silicon element present on the surface of the magnetic iron oxide and the content A
(C / A) × 100 is 10 to 55%, and the hydrophobic inorganic fine powder is a fine powder treated with silicone oil or silicone varnish, and the specific surface area of the hydrophobic inorganic fine powder is A magnetic developer characterized in that the specific surface area is 0.4 to 0.6 times the specific surface area before the treatment with the silicone oil or silicone varnish.

(Specific Description of the Present Invention) The magnetic toner of the present invention (1) has a weight average particle diameter of 13.5 μm or less (preferably 3.5 to 13.5 μm) and a particle size distribution of the magnetic toner. Is characterized in that a specific magnetic iron oxide containing a silicon element is used for a magnetic toner having a content of magnetic toner particles having a particle diameter of 12.7 μm or more of 50% by weight or less.

The weight average particle size of the magnetic toner is 13.5 μm
In the case where the ratio is more than 50%, or when the content of the magnetic toner particles having a particle diameter of 12.7 μm or more exceeds 50% by weight, a magnetic toner containing a relatively large amount of relatively coarse magnetic toner particles is generally used conventionally. It is possible to stabilize the charging of the magnetic toner by using the magnetic iron oxide.

The weight average particle diameter of the magnetic toner particles is 3.5 μm.
When the value is smaller than m, the fluidity of the magnetic toner becomes low even when the special magnetic iron oxide of the present invention (1) is used, and problems such as fogging and light density due to poor charging are likely to occur. The weight average particle size is preferably 3.5 μm or more.

That is, in the magnetic toner of the present invention (1), remarkable effects such as improvement of charging stability and fluidity are seen as compared with the conventional example because the weight average particle diameter is 13.5 μm or less (preferably 3.5 to 13.5 μm, more preferably 5.0 to 13.0 μm) and a particle size of 12.7 μm.
This is the case where the content of magnetic toner particles having a particle size of m or more is 50% by weight or less (more preferably 40% or less).

The content of the silicon element of the magnetic iron oxide used in the magnetic toner of the present invention is 0.5% based on the iron element.
One of the features is that the content is from 4.0 to 4.0% by weight (more preferably from 0.8 to 3.0% by weight, and still more preferably from 0.9 to 3.0% by weight). When the content of the silicon element is less than 0.5% by weight, the effect of improving the magnetic toner (particularly, the improvement of the fluidity of the magnetic toner) is weak, and when the content of the silicon element is more than 4.0% by weight. Is undesirable because the silicic acid component tends to remain on the surface of the magnetic iron oxide more than necessary or adversely affect the magnetic properties.

Further, in the present invention, the total content A of the silicon element present in the magnetic iron oxide used in the magnetic toner and the content of the silicon element present when the dissolution rate of the iron element of the magnetic iron oxide is up to about 20% by weight B / A × 100 (%) with B is 44
８４84% (preferably 60-80%), and the ratio C / A × 100 (%) of the content C and the content A of the silicon element present on the surface of the magnetic iron oxide particles is 10-55%. (Preferably 25 to 40%).
When B / A × 100 (%) is smaller than 44%, an excessive amount of silicon element is present in the central part of the magnetic iron oxide, and the production efficiency is liable to deteriorate, and the magnetic characteristics are unstable. Magnetic iron oxide.

When B / A × 100 (%) exceeds 84%, too much silicon element is present in the surface layer of the magnetic iron oxide, and the silicon element is formed in a large amount on the surface of the magnetic iron oxide in a layered manner. When present, the surface of the magnetic iron oxide becomes brittle against mechanical shock, and when used in a magnetic toner, many adverse effects are likely to occur.

On the other hand, when C / A × 100 (%) is less than 10%, the silicon element on the surface of the magnetic iron oxide is small, and it is difficult to obtain good fluidity in the magnetic iron oxide and the magnetic toner. In addition, the charge amount and the volume resistivity of the magnetic iron oxide are reduced, and the charge stability and environmental stability of the magnetic toner are easily impaired.

When C / A × 100 (%) is more than 55%, the irregularities on the surface of the magnetic iron oxide become conspicuous, and the irregularities on the surface of the magnetic iron oxide become fragments when manufacturing the magnetic toner. And easily adversely affect the properties of the magnetic toner.

In other words, in order to obtain good magnetic toner characteristics, the distribution of the silicon element present in the magnetic iron oxide must increase continuously or stepwise from the inside toward the surface as described above. preferable.

Further, in the present invention, the magnetic iron oxide has a charge amount of -25 to -70 .mu.c / g (more preferably -40 to -6.
0 μc / g) and the magnetic iron oxide has a volume resistivity of 1 × 10 ⁴ to 1 × 10 ⁸ Ω · cm (more preferably 5 × 10 ⁸ Ω · cm).
× 10 ^{4 to} 5 × 10 ⁷ Ω · cm).

When the charge amount of the magnetic iron oxide is less than -25 .mu.c / g, if the magnetic toner is used repeatedly for a long period of time, the magnetic toner cannot easily have the required charge amount, resulting in problems such as a decrease in image density and image fog. Occurs. On the other hand, when the charge amount of the magnetic iron oxide exceeds -70 μc / g,
Since the charge amount of the magnetic toner becomes too high, the image density tends to be reduced in a low-temperature and low-humidity environment.

The volume resistivity of the magnetic iron oxide is 5 ×
If it is smaller than 10 ³ Ω · cm, it becomes difficult to maintain the required charge amount of the magnetic toner, and the image density tends to decrease. On the other hand, if the volume resistivity of the magnetic iron oxide exceeds 1 × 10 ⁸ Ω · cm, the charge amount is likely to be higher than necessary when repeatedly used in a low-temperature, low-humidity environment, and a decrease in image density is observed. Easy to be.

Further, in the present invention, the degree of aggregation of the magnetic iron oxide is preferably 3 to 40% (more preferably 5 to 30%).

When the degree of agglomeration of the magnetic iron oxide is less than 3%, blowing of the magnetic toner, which is called flushing, is apt to occur during the production of the magnetic toner, and it is difficult to efficiently produce the magnetic toner.

On the other hand, when the degree of aggregation exceeds 40%,
It is not easy to sufficiently disperse the magnetic iron oxide in the magnetic toner, and the magnetic iron oxide tends to have an adverse effect on image density, fog, and the like. In the present invention, the fluidity of the magnetic iron oxide is reflected on the fluidity of the magnetic toner, and the degree of aggregation is 40%.
When a magnetic iron oxide exceeding 50% is used, it is difficult to obtain sufficient fluidity of the magnetic toner, which adversely affects the chargeability of the magnetic toner, and tends to cause fogging and the like.

Further, in the present invention, the magnetic iron oxide has a smoothness D of 0.2 to 0.6 (more preferably 0.3 to 0. 0).
5) is preferable.

If the smoothness D is smaller than 0.2, the irregularities on the surface of the magnetic iron oxide are conspicuous, and the irregularities become fragments in the production of the magnetic toner, and are easily dispersed in the magnetic toner to easily affect the toner characteristics.

On the other hand, if the smoothness D is larger than 0.6, it is difficult to obtain sufficient adhesion between the binder resin used for the magnetic toner and the magnetic iron oxide, and the surface of the magnetic toner gradually becomes less repetitive when used. Magnetic iron oxide is removed, which tends to cause adverse effects such as a decrease in image density.

Further, in the present invention, the sphericity of the magnetic iron oxideψ
Is preferably 0.8 or more.

When the sphericity ψ is less than 0.8, the individual particles of the magnetic iron oxide come into face-to-face contact,
With a small magnetic iron oxide particle having a particle size of about 0.1 to 1.0 μm, the magnetic iron oxide particles cannot be easily separated from each other even with a mechanical shearing force. May not be sufficiently dispersed.

Further, the magnetic iron oxide used in the present invention preferably has an average particle size of 0.1 to 0.4 μm, more preferably 0.1 to 0.3 μm.

The resin fine particles used in the present invention (1) preferably have an average particle diameter of 0.03 to 2.0 μm, more preferably 0.05 to 1.0 μm.

The function of the fine resin particles in the present invention (1) is not clear, but can be estimated as follows.

The magnetic material used in the present invention is particularly effective in improving the fluidity and charge stability of the magnetic toner, but is extremely stable even when a large number of prints are made by adding resin fine particles. The resulting image is low temperature, low humidity, high temperature,
It can be obtained even in high humidity environments. This is because the dispersion of the resin fine particles in the magnetic toner having improved fluidity using the magnetic material used in the present invention is greatly improved as compared with the magnetic toner having poor fluidity, and the toner is more uniformly dispersed. It is thought that the resin particles act like a roller because they are dispersed inside, reducing the chance of direct contact between toners. Especially when printing in large quantities, it is thought that there is no deterioration in fluidity due to environmental fluctuations. Can be

In the present invention (1), if the particle size of the resin fine particles is smaller than 0.03 μm, the tribo of the developer becomes too high, and the density tends to decrease due to charge-up. When the particle size of the resin fine particles is larger than 2.0 μm, dispersion between the toner particles becomes insufficient, and the charging stability of the developer becomes insufficient.

Further, the resin fine particles used in the present invention (1) are desirably charged to the same polarity as the toner particles.

In the present invention (1), when the resin fine particles are charged to the opposite polarity to the toner particles, the image is not fogged.

In the present invention (1), the added amount of the resin fine particles is 0.01 to 1.0 with respect to 100 parts by weight of the magnetic toner.
0 parts by weight, more preferably 0.02 to 0.6 parts by weight. When the addition amount is less than 0.01 part by weight, the effect of adding the resin fine particles is not observed, and when the addition amount is more than 1.0 part by weight, the charge amount of the developer becomes unstable, and the toner particles appear on the image. Scatters, a so-called "splash" occurs.

The method for measuring various physical property data in the present invention will be described in detail below.

The particle size distribution of the toner can be measured by various methods. In the present invention, the particle size distribution is measured using a Coulter counter.

That is, a Coulter counter TA-II type (manufactured by Coulter) was used as a measuring device, 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. The electrolyte is 1 grade using primary sodium chloride.
% NaCl aqueous solution is prepared. As a measuring method, a surfactant (preferably an alkylbenzene sulfonate) is used as a dispersant in 100 to 150 ml of the aqueous electrolytic solution.
Add 5 ml, and further add 2-20 mg of the measurement sample.
The electrolytic solution in which the sample was suspended was subjected to dispersion treatment for about 1 to 3 minutes with an ultrasonic disperser, and the volume and number of the toner were measured using the Coulter Counter TAII, using a 100 μm aperture as the aperture, and measuring 2 to 40 μm. The volume distribution and the number distribution of the particles are calculated. Then, a weight-based weight average diameter D4 (the median value of each channel is set as a representative value for each channel) obtained from the volume distribution is obtained.

In the present invention, the content C of the silicon element on the surface of the magnetic iron oxide can be determined by the following method. For example, about 3 liters of deionized water is placed in a 5 liter beaker and heated in a water bath to 50 to 60 ° C. About 25 g of magnetic iron oxide slurried with about 400 ml of deionized water is added to the 5 liter beaker with the deionized water while washing with about 300 ml of deionized water.

Then, while maintaining the temperature at about 60 ° C. and the stirring speed at about 200 rpm, a special grade sodium hydroxide is added to make a 1N sodium hydroxide solution. At this time, the magnetic iron oxide concentration is about 5 g / liter. The dissolution of silicon compounds such as silicic acid on the surface of the iron oxide particles is started. After 30 minutes from the start of dissolution, 20 ml was sampled, and 0.1 ml was sampled.
Filter through a μ membrane filter and collect the filtrate. The filtrate is subjected to quantitative determination of silicon element by plasma emission spectroscopy (ICP).

The content C of the silicon element is determined by the unit weight of the magnetic iron oxide in the aqueous sodium hydroxide solution (magnetic iron oxide 5 g /
Per liter) (mg / liter).

In the present invention, the content of the silicon element (based on the iron element), the dissolution rate of the iron element and the contents A and B of the silicon element of the magnetic iron oxide can be determined by the following methods. it can. For example, about 3 liters of deionized water is placed in a 5 liter beaker and heated in a water bath to 45 to 50 ° C. About 25 g of magnetic iron oxide slurried with about 400 ml of deionized water is added to about 3
While washing with 00 ml of deionized water, add to the 5 liter beaker with the deionized water.

Next, while maintaining the temperature at about 50 ° C. and the stirring speed at about 200 rpm, special grade hydrochloric acid is added to start dissolution. At this time, the concentration of the magnetic iron oxide is about 5 g / liter, and the aqueous hydrochloric acid solution is about 3N. Approximately 20m several times from the start of dissolution until it is completely dissolved and transparent
Sample 1 and filter through a 0.1 μm membrane filter to collect the filtrate. Filter the filtrate to plasma emission spectroscopy (IC
According to P), the iron element and the silicon element are quantified.

The iron element dissolution rate for each sample is calculated by the following equation.

[0076]

(Equation 1) The content and content of the silicon element for each sample are calculated by the following equations.

[0077]

(Equation 2) The total content A of the silicon element of the magnetic iron oxide corresponds to the silicon element concentration (mg / liter) per unit weight (5 g / liter of magnetic iron oxide) of the magnetic iron oxide after all of it is dissolved.

The content B of the silicon element in the magnetic iron oxide is the silicon element concentration per unit weight (5 g / liter of the magnetic iron oxide) of the magnetic iron oxide detected when the dissolution rate of the magnetic iron oxide is 20%. (Mg / liter).

The methods for measuring the contents A, B and C are as follows: (1) A magnetic iron oxide sample is divided into two parts, and while the contents and contents A and B of the silicon element are measured, the contents are measured. A method of separately measuring the amount C, and (2) measuring the content C of the sample of magnetic iron oxide, using the sample after the measurement, and then using the content B ′ (the amount obtained by subtracting the content C from the content B). ) And the content A ′ (the amount obtained by subtracting the content C from the content A) to finally calculate the contents A and B.

In the present invention, the charge amount of the magnetic iron oxide (μc
/ G) is measured as follows.

About 2 g of magnetic iron oxide and carrier iron powder (TEF)
V200-300 mesh) (Nihon Tekko Co., Ltd.) about 19
8 g is weighed into a 500 ml poly bottle, shaken by hand for 10 seconds, shaken by a V-shaped blender for 20 minutes, and charged with a magnetic iron oxide using a blow-off powder charge measuring device (Toshiba Chemical Corporation). Is measured. At this time, a 400 mesh stainless steel net is set on the Faraday gauge for measurement, and about 0.4 g of the measurement sample is weighed and calculated from the value when blow-off is performed for 30 seconds.

In the present invention, the volume resistivity of the magnetic iron oxide is measured as follows.

10 g of magnetic iron oxide is put into a measuring cell and molded (pressure 600 kg / cm ² ) by a hydraulic cylinder. After releasing the pressure, use a resistance meter (Yokogawa Electric's YEW MODE).
L2506A DIGITAL MALTIMETO
R) and set it again with the hydraulic cylinder to 150 kg.
/ Cm ² pressure. Start the measurement and read the measured value 3 minutes later. Further, the thickness of the sample is measured, and the volume resistivity is measured by the following equation.

[0084]

(Equation 3) In the present invention, the degree of aggregation of the magnetic iron oxide is measured as follows.

10 g of magnetic iron oxide was pulverized with a mixer,
Weigh 2 g of what passed the 00 mesh sieve. A screen tester (Hosokawa Micron Co., Ltd.) was set with three screens of 60 mesh, 100 mesh, and 200 mesh in this order from above, and 2 g of the weighed sample was placed on the screen immediately, and a vibration of 1 mm amplitude was given for 65 seconds. The weight of the magnetic iron oxide remaining on each sieve is measured, and the degree of aggregation is calculated according to the following equation.

[0086]

(Equation 4) In the present invention, the smoothness D of the magnetic iron oxide is determined as follows.

[0087]

(Equation 5) The BET specific surface area of the magnetic iron oxide is determined by a BET multipoint method using nitrogen as an adsorbed gas. In addition, as pretreatment of a sample, degassing is performed at 50 ° C. for 1 hour.

The measurement of the average particle size and the calculation of the surface area of the magnetic iron oxide are performed as follows.

Using a sample of magnetic iron oxide treated on a copper mesh of a collodion film with an electron microscope (H-700H, manufactured by Hitachi, Ltd.), an image was taken at 10,000 × at an applied voltage of 100 KV, and the printing magnification was set to 3 ×. The magnification is 30,000 times. Thus, the shape is observed, the maximum length (μm) of each particle is measured, 100 particles are randomly selected, and the average is used as the average particle diameter.

For the calculation of the surface area, it is assumed that the magnetic iron oxide has a spherical shape with an average particle diameter as a diameter, and the density of the magnetic iron oxide is measured by a usual method to obtain the value of the surface area.

The calculation of the sphericity 磁性 of the magnetic iron oxide in the present invention is performed as follows.

[0092]

(Equation 6) The sphericity is obtained by randomly selecting 100 magnetic iron oxide particle specimens from a photograph, measuring the maximum length and the minimum length, and then averaging the calculated values.

The maximum length and the minimum length of the oxidized magnetic material follow the method for obtaining the average particle size.

The sphericity ψ of a cubic ordinary magnetic iron oxide is about 0.6 to 0.7 and less than 0.8, whereas the sphericity 好 ま し く preferably used in the present invention is 0.8 or more. The magnetic iron oxide (preferably 0.85 or more, more preferably 0.9 or more) has a shape close to a spherical shape without a square end.

When the sphericity ψ is less than 0.8, even if the silicon element is unevenly distributed on the surface of the magnetic iron oxide particles, the dispersibility in the binder resin is inferior to the case where the silicon element is 0.8 or more. The magnetic toner obtained tends to have poor developing characteristics, and tends to be a magnetic toner having poor dot reproducibility.

The magnetic iron oxide used in the magnetic toner of the present invention is used in an amount of 20 to 2 parts by weight based on 100 parts by weight of the binder resin.
It is preferable to use 00 parts by weight. It is more preferable to use 30 to 150 parts by weight.

In some cases, the magnetic iron oxide used in the magnetic toner of the present invention may be treated with a silane coupling agent, a titanium coupling agent, titanate, aminosilane, or the like.

The particle size of the resin fine particles in the present invention (1) can be measured by various methods. In the present invention (1), the measurement is performed using an electron micrograph. That is, using an electron microscope S-800 (Hitachi, Ltd.)
A photograph was taken at a magnification of 0000 times, and 100 to 200 pieces were randomly extracted from the photographed resin fine particles, their diameters were measured using calipers, and the average was taken as the particle diameter of the resin fine particles.

The tribo value of the resin fine particles used in the present invention (1) is measured by the following method. That is, 23.5
0.2 g of resin fine particles left overnight under an environment of 60 ° C. and 60% RH and a main particle size of 200 to 300 mesh.
20.0 g of carrier iron powder not coated with resin (for example, EFV200 / 300 manufactured by Nippon Iron Powder Co., Ltd.) is precisely weighed in the above environment, and sufficiently weighed in a polyethylene lid-equipped jar having a volume of about 50 ml. Mix (hold hand and shake up and down approximately 125 times for about 50 seconds).

Next, as shown in FIG. 3, about 2.0 g of the mixture is placed in a metal measuring container 32 having a 400-mesh screen 33 at the bottom, and a metal lid 34 is placed. At this time, the weight of the entire measurement container 32 is weighed and defined as W ₁ (g). next,
In the suction device 31 (at least a portion in contact with the measurement container 32 is an insulator), the air is sucked from the suction port 37 and the air volume control valve 36
Is adjusted to bring the pressure of the vacuum gauge 35 to 250 mmHg.
In this state, sufficient suction is performed for 5 minutes to remove the resin fine particles by suction. The potential of the electrometer 39 at this time is set to V (volt). Here, 38 is a capacitor whose capacity is C (μF).
And Also, the weight of the whole measurement container after suction is weighed and W ₂
(G). The triboelectric charge (μc /
g) is calculated as follows:

Triboelectric charge = CV / (W ₁ −W ₂ ) The resin fine particles used in the present invention (1) are produced by a soap-free polymerization method, an emulsion polymerization method or the like. Preferably, resin fine particles obtained by polymerizing monomers such as styrene, acrylic acid, methyl methacrylate, butyl acrylate, and 2-ethylhexyl acrylate alone or in combination of two or more thereof exhibit a good effect.

The surface may be cross-linked with divinylbenzene or the like, and the surface may be treated with a metal, metal oxide, pigment, dye, surfactant, or the like to adjust the specific electric resistance, triboelectric charge and the like. Is also a preferred embodiment of the present invention (1).

Further, the magnetic toner of the present invention (2) has a feature that the weight average particle diameter is 6 to 8 μm and the number of magnetic toner particles having a particle diameter of 5 μm or less is 17 to 60% by number. is there. Conventionally, magnetic toner particles having a particle size of 5 μm or less have difficulty in controlling the charge amount, impair the fluidity of the magnetic toner, and cause fogging of the image as a component that scatters the toner and soils the machine. It was thought that aggressive reduction was necessary as a component.

However, according to the study of the present inventors, it has been found that magnetic toner particles having a size of 5 μm or less are essential components for forming a high quality image.

For example, using a magnetic toner having a particle size distribution ranging from 0.5 μm to 30 μm, the surface potential on the photoreceptor is changed so that a large development potential contrast in which many toner particles are easily developed is changed to halftone. Develop the latent image with the changed surface potential on the photoreceptor to a small development potential contrast where only a few toner particles are developed, collect the developed toner particles on the photoreceptor,
When the toner particle size distribution was measured, it was found that there were many magnetic toner particles having a size of 8 μm or less, and particularly many magnetic toner particles having a size of 5 μm or less. In other words, 5
When magnetic toner particles having a particle size of μm or less are smoothly supplied to the development of the latent image on the photoreceptor, the image is faithful to the latent image, and an image with truly excellent reproducibility can be obtained without protruding from the latent image. Things. This development was the same in the case of reversal development of a digital latent image.

In the magnetic toner according to the present invention (2), particles having a size in the range of 6.35 to 10.08 μm have a particle size of 5 to 5.
One feature is that it is 50% by number. This is related to the need for the presence of magnetic toner particles having a particle size of 5 μm or less, as described above. The magnetic toner particles having a particle size of 5 μm or less strictly cover the latent image and have an ability to faithfully reproduce the latent image. However, in the latent image itself, the electric field strength at the peripheral edge portion is higher than that at the central portion, so that the “glue” of the toner particles inside the latent image becomes thinner than the edge portion, and the image density appears to be lighter. is there. In particular, magnetic toner particles of 5 μm or less have a strong tendency. However, the inventors have determined that toner particles in the range of 6.35 to 10.08 μm
It has been found that this problem can be solved and the content can be further sharpened by containing 50 to 50% by number. That is, it is considered that the toner particles having a particle size in the range of 6.35 to 10.08 μm have a moderately controlled charge amount with respect to the magnetic toner particles having a particle size of 5 μm or less. Is supplied to the inner side where the electric field strength is smaller than that of the edge portion, thereby compensating for the small amount of “glue” of the toner particles on the inner side with respect to the edge portion, thereby forming a uniform developed image. Thus, a sharp image having excellent properties is provided.

Further, for particles having a particle size of 5 μm or less, N / V is set between the number% (N) and the volume% (V).
= −0.05N + k (however, 4.6 ≦ k ≦ 6.7; 17
≦ N ≦ 60) is one of the features of the magnetic toner according to the present invention (2). FIG. 9 shows this range. In addition to the other features, the magnetic developer containing the magnetic toner according to the present invention (2) having a particle size distribution satisfying this range has excellent developability for a high-definition latent image. Can be achieved.

The present inventors have studied the state of the particle size distribution of 5 μm or less, and have found that there is a state of existence of the fine powder most suitable for achieving the object as shown by the above formula. That is, a large value of N / V for a certain value of N indicates that particles of 5 μm or less are widely included, and a small value of N / V indicates that the particle abundance near 5 μm is small. High, indicating that there are few particles of smaller size, the value of N / V is in the range of 1.6-5.85 and N is in the range of 17-60, When the above relational expression is further satisfied, good fine line reproducibility and high resolution are achieved.

For magnetic toner particles having a particle size of 12.7 μm or more, the content is preferably 2.0% by volume or less, and is preferably as small as possible.

The magnetic developer of the present invention (2) solves the conventional problems and can withstand recent severe demands for high image quality.

The configuration of the present invention (2) will be described in more detail.

The number of magnetic toner particles having a particle size of 5 μm or less is preferably 17 to 60% by number of the total number of particles, preferably 25 to 60% by number, and more preferably 30 to 60% by number.
Number% is good. One magnetic toner particle having a particle size of 5 μm or less
When the content is less than 7% by number, the amount of magnetic toner particles effective for high image quality is small. In particular, as the toner is used by continuing printout, the effective magnetic toner particle component decreases, and the present invention (2) As shown, the variation in the particle size distribution of the magnetic toner becomes worse, and the image quality gradually decreases. On the other hand, if it exceeds 60% by number, the magnetic toner particles tend to aggregate with each other, resulting in a toner mass larger than the original particle size, resulting in rough image quality, reduced resolution, or an edge of a latent image. The density difference between the part and the inside becomes large, and the image tends to be slightly hollow.

Further, the number of particles in the range of 6.35 to 10.08 μm is preferably 5 to 50% by number, more preferably 8 to 50% by number.
~ 40% by number is good. If the content is more than 50% by number, the image quality is deteriorated, and the development is performed more than necessary, that is, the toner is excessively "glue", the fine line reproducibility is reduced, and the toner consumption is increased. If so, it becomes difficult to obtain a high image density. 3. There is a relationship of N / V = −0.05N + k between the number% (N%) and the volume% (V%) of the magnetic toner particles having a particle diameter of 5 μm or less.
Indicates a positive number in the range of 6 ≦ k ≦ 6.7. Preferably 4.6
≤ k ≤ 6.2, more preferably 4.6 ≤ k ≤ 5.7. As indicated above, 17 ≦ N ≦ 60, preferably 25 ≦ N ≦ 60, more preferably 30 ≦ N ≦ 60.

When k <4.6, the number of magnetic toner particles having a particle diameter smaller than 5.0 μm is small, and the image density, the resolution and the sharpness are inferior. The appropriate presence of fine magnetic toner particles, which was conventionally considered unnecessary, contributes to the closest packing of the toner in development and contributes to the formation of a uniform image without roughness. In particular, by uniformly filling the fine lines and the contours of the image, the sharpness is further enhanced visually. That is, when k <4.6, these characteristics are inferior due to the lack of the particle size distribution component.

From another viewpoint, in production, it is necessary to cut a large amount of fine powder by classification or the like to satisfy the condition of k <4.6, which is disadvantageous in terms of yield and toner cost. Becomes Further, when k> 6.7, the image density tends to be reduced due to the presence of unnecessarily fine powder while printing is repeated repeatedly. Such a phenomenon is
It is considered that excess fine magnetic toner particles having a charge more than necessary are charged and adhered to the developing sleeve, and this is caused by obstructing the normal carrying of the magnetic toner on the developing sleeve and the charging.

Further, the content of the magnetic toner particles having a particle diameter of 12.7 μm or more is preferably 2.0% by volume or less, more preferably 1.0% by volume or less, and further preferably 0.5% by volume or less. It is. If it is more than 2.0% by volume, it will hinder the reproduction of fine lines.

The weight average diameter of the magnetic toner is 6 to 8 μm.
m, and this value cannot be considered separately from the above-mentioned components. Weight average particle size 6μ
If it is less than m, the use of a digital latent image having a high image area ratio, such as a graphic image, will result in a "glue" of the toner on the transfer paper.
The problem is that the amount is small and the image density is low. This is considered to be due to the same reason as described above for lowering the density inside the edge portion of the latent image. 100 μm when the weight average particle size exceeds 8 μm
The resolution of the following minute spots is not good and there are many jumps to non-image areas. At the beginning of the printout, if the user keeps using it at best, the image quality tends to deteriorate.

It is preferable that an inorganic fine powder or a hydrophobic inorganic fine powder is mixed with the magnetic toner of the present invention. For example, it is preferable to add silica fine powder for use.

The silica fine powder used in the present invention is preferably subjected to a hydrophobic treatment. The hydrophobizing treatment is applied by chemically treating with an organic silicon compound or the like which reacts or physically adsorbs with the silica fine powder. A preferred method is to treat the dry silica fine powder produced by the vapor phase oxidation of the silicon halide compound with a silane coupling agent, or simultaneously with the silane coupling agent, with an organosilicon compound such as silicone oil. Is mentioned.

In the present invention (3), the hydrophobic inorganic fine powder used for the magnetic developer is a fine powder treated with silicone oil or silicone varnish, and the carbon deposition amount by the treatment is 3 to 8% by weight. This is one of the features.

In the present invention (4), the hydrophobic inorganic fine powder used for the magnetic developer is fine powder treated with silicone oil or silicone varnish, and the specific surface area of the fine powder is silicone oil or silicone varnish. One of the features is that the specific surface area is 0.4 to 0.6 times the specific surface area before the treatment.

In the silicone oil or silicone varnish treatment, the surface can be completely covered by applying the silicone oil or silicone varnish to the surface of the fine powder, and the moisture resistance is dramatically improved.

The fine powder according to the present invention (3, 4) is treated with silicone oil or silicone varnish having a strong negative charge, so that the fine powder is strongly negatively charged. In this case, the developer can be given a strong and uniform negative charge. This characteristic is effective for a magnetic one-component toner in which charging becomes unstable easily. In particular, it is effective for a toner having a fine particle diameter for the purpose of improving image quality.

The material of the fine powder used in the present invention is preferably an inorganic compound. For example, fine powders of Group 3 and Group 4 metal oxides such as silicic acid, alumina, and titanium oxide are preferable. As the preferred fine powder, both a so-called dry method produced by vapor phase oxidation of a silicon halide and a so-called fumed silica and a so-called wet silica produced from water glass or the like can be used. but less silanol groups on the inner surface and fine silica powder, also Na ₂ O, is more less dry silica with production residue SO ₃ ^2-like desirable. In the case of fumed silica, for example, in the production process, by using another metal halide such as aluminum chloride or titanium chloride together with a silicon halide, it is also possible to obtain a composite fine powder of silica and another metal oxide, They are also included. The particle size is 0.0 as an average primary particle size.
It is desirable to use a silica fine powder in a range of from 0.01 to 2 μm, particularly preferably in a range of from 0.002 to 0.2 μm.

The solid content of the silicone oil or silicone varnish used in the present invention is generally represented by the following formula:

[0126]

Embedded image R: C ₁ alkyl group -C ₃ R ': alkyl, halogen-modified alkyl, phenyl, silicone oil modified group R of the modified phenyl such as ": C ₁ ~C ₃ alkyl group or Arukookishiru group such as dimethyl silicone oil, alkyl Modified silicone oil, α-methylstyrene-modified silicone oil, chlorophenyl silicone oil, fluorine-modified silicone oil and the like can be mentioned.

The silicone oil preferably has a viscosity at 25 ° C. of 50 to 1000 centistokes. If the molecular weight is too low, volatile components may be generated in the silicone oil due to heat treatment or the like, and if the molecular weight is too high, the viscosity becomes too high and the processing operation becomes difficult.

As the method of treating silicone oil or silicone varnish, known techniques are used. For example, fine silica powder and silicone oil may be directly mixed using a mixer such as a Henschel mixer, or the base silica may be used. A method in which silicone oil is sprayed on fine powder may be used.
More preferably, the silicone oil is dissolved or dispersed in an appropriate solvent, mixed with a base silicic acid fine powder, and then the solvent is removed.

The treatment of the silicone oil or silicone varnish in the present invention (3) is preferably carried out so that the amount of carbon deposited by the silicone oil or silicone varnish treatment is 3 to 8% by weight of the fine silica powder. Here, the carbon deposition amount refers to an elemental analyzer (CHN
Total).

In the treatment of silicone oil or silicone varnish in the present invention (4), the specific surface area of the fine silica powder after the treatment with the silicone oil or silicone varnish is 0.1% of the specific surface area of the fine silica powder before the treatment. 4 ~
Preferably, the treatment is performed so as to be 0.6 times. Here, the specific surface area of the silica fine powder is defined as N ₂ in the BET method.
This is a value obtained from adsorption. In the present invention (3, 4), the reason for limiting the above treatment conditions is that when the specific surface area of the silicic acid fine powder by the silicone oil or silicone varnish treatment is small, when the treatment with the silicone oil or silicone varnish is small, In the former case, the moisture resistance is not improved in the former case, and the high-humidity silica fine powder absorbs moisture so that a high-quality image cannot be obtained.In the latter case, the silicone oil or silicone is further added. The photoreceptor to be removed and collected in the step of transferring a toner image, particularly when applied to toner having a small particle diameter, because the uniform chargeability of the developer is insufficient because the addition of negative chargeability by varnish processing is not performed uniformly. There are drawbacks such as the inability to reduce the amount of residual toner above.
On the other hand, if the specific surface area of the fine silica powder is excessively reduced by the silicone oil or silicone varnish treatment, agglomerates of the fine silica powder are generated, and when applied to a developer, the fluidity cannot be improved. Disadvantages occur.

In the treatment of the silicone oil or silicone varnish, the amount of the solid content of the silicone oil or silicone varnish to be charged generally depends on the fine silica powder
It is 3 to 50 parts by weight with respect to 0 parts by weight.

Further, it is more preferable that the fine silica powder used in the present invention is first treated with a silane coupling agent, and then treated with a silicone oil or silicone varnish.

In general, only the treatment with silicone oil or silicone varnish requires a large amount of silicone oil to cover the surface of the fine silica powder. Due to drawbacks such as poor fluidity, it is necessary to pay close attention to the processing steps of silicone oil or silicone varnish. Therefore, it is better to treat the silicic acid fine powder with a silane coupling agent and then treat it with a silicone oil or silicone varnish in order to remove the aggregation of the silicic acid fine powder while maintaining good moisture resistance. That is, the effect of the treatment can be sufficiently exhibited.

The silane coupling agent used in the present invention is represented by the general formula: R _m SiY _n R: an alkoxy group or a chlorine atom m: an integer of 1 to 3 Y: a carbon atom containing an alkyl group, a vinyl group, a glycid group, and a methacryl group Hydrogen n: represented by an integer of 3 to 1, for example, typically dimethyldichlorosilane,
Trimethylchlorosilane, allyldimethylchlorosilane, hexamethyldisilazane, allylphenyldichlorosilane, benzyldimethylchlorosilane, vinyltriethoxysilane, γ-methacryloxypropyltriethoxysilane, vinyltriacetoxysilane, divinylchlorosilane, dimethylvinyl Chlorosilane and the like can be mentioned.

The silane coupling agent treatment of the silicic acid fine powder may be carried out by a dry treatment in which a vaporized silane coupling agent is reacted with a cloud of the silicic acid fine powder by stirring or the like, or the silicic acid fine powder is dissolved in a solvent. And a generally known method such as a wet method in which a silane coupling agent is dropped and reacted.

The amount of the treated silicic acid fine powder applied to the developer is 0.1 to 100 parts by weight of the magnetic toner.
The amount is from 01 to 20 parts by weight, more preferably from 0.1 to 3 parts by weight.

An external additive other than the fine silica powder may be added to the magnetic toner of the present invention, if necessary.

For example, a charging auxiliary, a conductivity-imparting agent, a fluidity-imparting agent, an anti-caking agent, a release agent for fixing with a hot roll,
These are resin fine particles and inorganic fine particles that function as a lubricant, an abrasive and the like.

As the binder resin of the toner according to the present invention,
Styrene such as polystyrene and polyvinyltoluene and its substituted homopolymer; styrene-propylene copolymer, styrene-vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, styrene-methyl acrylate copolymer, styrene- Ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-octyl acrylate copolymer, styrene-dimethylaminoethyl acrylate copolymer, styrene-methyl methacrylate copolymer, styrene-methacrylic Acid ethyl copolymer,
Styrene-butyl methacrylate copolymer, styrene-
Dimethylaminoethyl methacrylate copolymer, styrene-vinyl methyl ether copolymer, styrene-vinyl ethyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-
Isoprene copolymer, styrene-maleic acid copolymer,
Styrene-based copolymers such as styrene-maleic acid ester copolymers; polymethyl methacrylate, polybutyl methacrylate, polyvinyl acetate, polyethylene, polypropylene, polyvinyl butyral, silicone resin, polyester resin, polyamide resin, epoxy resin, polyacrylic acid Resin, rosin, modified rosin, temper resin, phenol resin, aliphatic or alicyclic hydrocarbon resin, aromatic petroleum resin, paraffin wax, carnauba wax, etc. can be used alone or in combination. In particular, styrene-based copolymers and polyester resins are preferred in terms of development characteristics, fixability, and the like.

A hydrocarbon wax and an ethylene olefin polymer may be used together with a binder resin as a fixing aid in the toner of the present invention.

Here, those applied as ethylene-based olefin homopolymer or ethylene-based olefin copolymer include polyethylene, polypropylene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, and ethylene-ethyl acrylate copolymer. The copolymer includes an ionomer having a polyethylene skeleton, and the copolymer preferably contains 50 mol% or more (more preferably, 60 mol% or more) of an olefin monomer.

As a coloring material that can be further added to the magnetic toner according to the present invention, conventionally known pigments or dyes such as carbon black and copper phthalocyanine can be used.

The magnetic toner of the present invention may contain a charge control agent if necessary.
Negative charge control agents such as metal complex salts of monoazo dyes and metal complex salts of salicylic acid, alkyl salicylic acid, dialkyl salicylic acid or naphthoic acid are used.

In the case of a positively chargeable toner, a positive charge control agent such as a nigrosine compound or an organic quaternary ammonium salt is used.

The image forming apparatus, apparatus unit and facsimile apparatus for using the magnetic developer of the present invention will be described.

A preferred specific example of the image forming apparatus will be described with reference to FIG.

The surface of the OPC photosensitive member 3 is negatively charged by the primary charger 11, a digital latent image is formed by image scanning by exposure 5 with a laser beam, and a urethane rubber elastic blade 9 and a The latent image is reversely developed with the one-component magnetic developer 13 having the magnetic toner of the developing device 1 including the developing sleeve 6 including the magnet 15 therein. In the developing section, between the conductive base of the photosensitive drum 3 and the developing sleeve 6, an alternating bias, a pulse bias and / or a DC bias are applied by the bias applying means 12. When the transfer paper P is conveyed and arrives at the transfer section, the electrostatic transfer means 4 performs corona charging from the back surface (the surface opposite to the photosensitive drum side) of the transfer paper P, thereby forming a developed image (toner Image) is electrostatically transferred onto the transfer paper P. The transfer paper P separated from the photosensitive drum 3 is subjected to a fixing process by a heating and pressing roller fixing device 7 to fix the toner image on the transfer paper P.

The one-component developer remaining on the photosensitive drum after the transfer step is removed by a cleaning device 14 having a cleaning blade 8. After the cleaning, the photosensitive drum 3 is neutralized by the erase exposure 19, and the process starting from the charging process by the primary charger 11 is repeated again.

The electrostatic image carrier (photosensitive drum) has a photosensitive layer and a conductive substrate, and moves in the direction of the arrow. A non-magnetic cylindrical developing sleeve 6 serving as a toner carrier rotates in the developing section so as to advance in the same direction as the surface of the electrostatic image holding member. Inside the non-magnetic cylindrical developing sleeve 6, a multi-pole permanent magnet 15 (magnet roll) as a magnetic field generating means is arranged so as not to rotate. The one-component insulating developer 13 in the developing device 1 is applied on a non-magnetic cylindrical surface, and the magnetic toner particles are given, for example, a negative triboelectric charge by friction between the surface of the developing sleeve 6 and the magnetic toner particles. . Further, by disposing the elastic doctor blade 9, the thickness of the developer layer is controlled to be thin (30 μm to 300 μm) and uniform, and the developer layer thinner than the gap between the photosensitive drum 3 and the developing sleeve 6 in the developing section is formed. It is formed so as not to contact. By adjusting the rotational speed of the sleeve 6, the surface speed of the sleeve is substantially equal to or close to the speed of the electrostatic image holding surface.

In the developing section, the sleeve 6 and the photosensitive drum 3
An AC bias or a pulse bias may be applied by the bias unit 12 between the two. This AC bias is f
Is 200 to 4,000 Hz, and Vpp is 500 to 3,000 Hz.
It is preferably 0V.

At the time of transfer of the magnetic toner particles in the developing portion, the magnetic toner particles are transferred to the electrostatic image side by an electrostatic force on the surface of the photosensitive drum 3 holding the electrostatic image and the action of an AC bias or a pulse bias.

Next, another example of the image forming apparatus will be described with reference to FIG.

The image forming apparatus shown in FIG. 5 differs from the image forming apparatus shown in FIG. 4 in that the layer thickness of the magnetic developer on the developing sleeve 6 is regulated by a magnetic doctor blade 16. In FIG. 5, members having the same reference numerals as those in FIG. 4 indicate the same members.

As the magnetic doctor blade 16, for example, a doctor blade made of iron is placed close to the cylindrical surface (at a distance of 5 mm).
0 μm to 500 μm), and the thickness of the developer layer is regulated to be thin (30 μm to 300 μm) and uniformly by arranging the multipole permanent magnet so as to face one magnetic pole position. A developer layer thinner than the gap between the body 1 and the developing sleeve 2 is formed so as to be in non-contact. By adjusting the rotational speed of the developing sleeve 2, the surface speed of the sleeve is substantially equal to or close to the speed of the electrostatic image holding surface. The opposed magnetic poles may be formed by using permanent magnets instead of iron as the magnetic doctor blade 6.

As the electrophotographic apparatus, a plurality of components such as an electrostatic latent image carrier such as the above-described photosensitive drum, a developing device, and a cleaning unit are integrally connected as a device unit. The unit may be configured to be detachable from the apparatus main body. For example, a unit is formed by integrally supporting at least one of the charging unit, the developing device, and the cleaning unit together with the photosensitive drum, and the unit is detachably attached to the apparatus main body. It may be configured to be detachable. At this time, the charging unit and / or
Alternatively, it may be configured with a developing device.

FIG. 6 shows an embodiment of the above-mentioned apparatus unit. In this embodiment, an electrophotographic image provided with an image forming unit (a so-called cartridge) in which a developing device 1, a drum-shaped latent image carrier (photosensitive drum) 3, a cleaner 14, and a primary charger 11 are integrated. A forming apparatus is exemplified.

In this apparatus, when the magnetic developer 13 of the developing device 1 in the image forming unit runs out, it is replaced with a new cartridge.

In this embodiment, the developing device 1 uses a one-component magnetic developer as the developer 13, and at the time of development, a predetermined electric field is formed between the photosensitive drum 3 and the developing sleeve 6. In order to carry out the above operation properly, the distance between the photosensitive drum 3 and the developing sleeve 6 is very important.
In this embodiment, measurement and adjustment are performed so that the center is 300 μm and the error is ± 30 μm.

The developing device 1 shown in FIG. 6 has a developer container 2 for containing a magnetic developer 13 and the magnetic developer 13 in the developer container 2 facing the latent image carrier 3 from the developer container 2. A developing sleeve 6 that is carried and transported to the developing area; and a magnetic developer that is carried by the developing sleeve 6 and transported to the developing area is regulated to a predetermined thickness to form a thin developer layer on the developing sleeve. And an elastic blade 9.

The developing sleeve 6 can have any structure. Usually, it is composed of a non-magnetic developing sleeve 6 having a magnet 15 built therein. The developing sleeve 6 may be a cylindrical rotating body as shown. It is also possible to adopt a belt shape that moves in a circulating manner. The material is usually
Preferably, aluminum or SUS is used.

The elastic blade 9 is made of a rubber elastic material such as urethane rubber, silicone rubber or NBR; a metal elastic material such as phosphor bronze or a stainless steel plate; a resin elastic material such as polyethylene terephthalate or high density polyethylene. It is composed of boards. The elastic blade 9 is brought into contact with the developing sleeve 6 by the elasticity of the member itself, and is fixed to the developer container 2 by a blade supporting member 10 made of a rigid body such as iron. The elastic blade 9 has a linear pressure of 5 to 80 g /
cm, it is preferable to abut against the rotation direction of the developing sleeve 6 in the counter direction.

When the above-described image forming apparatus is used as a facsimile printer, the light image exposure is exposure for printing received data. FIG. 7 is a block diagram showing an example of this case.

The controller 611 controls the image reading unit 610 and the printer 619. The entire controller 611 is controlled by the CPU 617. The read data from the image reading unit is transmitted to the partner station through the transmission circuit 613. Data received from the partner station is sent to the printer 619 through the receiving circuit 612. Predetermined image data is stored in the image memory. Printer controller 6
Reference numeral 18 controls the printer 619. 614 is a telephone.

The image received from the line 615 (image information from the remote terminal connected via the line) is demodulated by the receiving circuit 612, and then the CPU 617 performs a decoding process of the image information, and the image memory 616 Is stored in The image of at least one page is stored in the memory 616.
, The image of the page is recorded. CPU
617 reads out the image information of one page from the memory 616 and sends out the decoded image information of one page to the printer controller 618. Printer controller 618
The printer 61 receives the image information of one page from the CPU 618 and records the image information of the page.
9 is controlled.

The CPU 617 receives the next page during recording by the printer 619.

As described above, image reception and recording are performed.

To prepare a magnetic toner for developing an electrostatic image according to the present invention, a magnetic powder, a vinyl-based or non-vinyl-based thermoplastic resin, a pigment or a dye as a colorant as required, a charge control And other additives are thoroughly mixed by a mixer such as a ball mill, and then melted, kneaded and kneaded using a hot kneader such as a heating roll, kneader or extruder to mutually dissolve the resins. The pigment or dye is dispersed or dissolved therein, and after cooling and solidifying, pulverization and strict classification are performed to obtain the magnetic toner according to the present invention.

The magnetic iron oxide having a silicon element according to the present invention is produced, for example, by the following method.

After a predetermined amount of a silicate compound is added to the aqueous ferrous salt solution, an equivalent or an equivalent or more of an alkali such as sodium hydroxide is added to the iron component to prepare an aqueous solution containing ferrous hydroxide. . Adjust the pH of the prepared aqueous solution to pH 7
Air is blown in while maintaining the above (preferably pH 8 to 10), and the ferrous hydroxide is oxidized while the aqueous solution is heated to 70 ° C. or higher, and a seed crystal serving as a core of magnetic iron oxide particles is first generated. I do.

Next, an aqueous solution containing about 1 equivalent of ferrous sulfate, based on the amount of the alkali previously added, is added to the slurry-like liquid containing the seed crystals. The reaction of ferrous hydroxide is promoted while blowing air while maintaining the pH of the solution at 6 to 10 to grow magnetic iron oxide particles with the seed crystal as a core. As the oxidation reaction proceeds, the pH of the solution shifts to the acidic side,
It is preferable that the pH of the liquid is not less than 6. By adjusting the pH of the solution at the end of the oxidation reaction, it is preferable that a predetermined amount of the silicate compound is unevenly distributed on the surface layer and the surface of the magnetic iron oxide particles.

Examples of the silicate compound used for the addition include commercially available silicates such as sodium silicate and silicic acids such as sol silicic acid generated by hydrolysis or the like. In addition, other additives such as aluminum sulfate and alumina may be added as long as they do not adversely affect the present invention.

As the ferrous salt, iron sulfate generally produced as a by-product in the production of titanium sulfate, iron sulfate produced as a by-product of cleaning the surface of a steel sheet, and iron chloride and the like can be used. .

The method for producing magnetic iron oxide by the aqueous solution method generally uses an iron concentration of 0.5 to 2 mol / liter from the viewpoint of preventing an increase in viscosity during the reaction and the solubility of iron sulfate. Generally, the lower the concentration of iron sulfate, the smaller the particle size of the product tends to be. Further, in the reaction, as the amount of air is larger and the reaction temperature is lower, the particles are easily atomized.

According to the above-mentioned production method, magnetic iron oxide particles having a silicic acid component were mainly composed of spherical particles formed of a curved surface having no plate-like surface, as observed by transmission electron micrographs. Produces magnetic iron oxide containing almost no face particles,
It is preferable to use the magnetic iron oxide in the toner.

[0175]

EXAMPLES The present invention will be described below in more detail with reference to Production Examples and Examples. Number of copies or% described in Examples
Indicates parts by weight or% by weight.

First, a production example of the magnetic iron oxide according to the present invention will be described.

Production Example 1 Sodium silicate was added to an aqueous ferrous sulfate solution so that the content ratio of silicon element to iron element was 1.8%.
L. For iron ions. An aqueous solution containing ferrous hydroxide was prepared by mixing 0 to 1.1 equivalents of a sodium hydroxide solution.

The pH of the aqueous solution is adjusted to pH 7 to 10 (for example, pH
While maintaining the condition of 9), air was blown in to perform an oxidation reaction at 80 to 90 ° C. to prepare a slurry liquid for generating seed crystals.

Next, an aqueous ferrous sulfate solution was added to the slurry so that the amount thereof became 0.9 to 1.2 equivalents with respect to the initial alkali amount (sodium component of sodium silicate and sodium component of caustic soda). PH of liquid 6-10
(Eg, pH 8), the oxidation reaction was promoted while blowing air, the pH was adjusted at the end of the oxidation reaction, and the silicic acid component was unevenly distributed on the surface of the magnetic iron oxide particles. The resulting magnetic iron oxide particles were washed, filtered, and dried by a conventional method, and then the aggregated magnetic iron oxide particles were crushed to obtain magnetic iron oxide having the properties shown in Table 2.

Data obtained by measuring the dissolution amounts of the iron element and the silicon element every 10 minutes are shown in Table 1, and FIG. 1 shows the relationship between the dissolution rates of the iron element and the silicon element in the magnetic iron oxide.

In the magnetic iron oxide obtained in Production Example 1, FIG.
The content C of a silicon element derived from a silicon compound such as silicic acid eluted with alkali present on the surface C of the magnetic iron oxide particles shown in FIG. 1 is 17.9 mg / liter, and the surface layer B of the magnetic iron oxide particles shown in FIG. The content B of the silicon element derived from the silicon compound present in is 38.8 mg / liter,
Content A was 59.7 mg / liter.

[0182]

[Table 1] Production Example 2 In Production Example 1, the content ratio of silicon to iron was 2.9.
% Magnetic iron oxide having the properties shown in Table 2 was obtained in the same manner as in Production Example 1 except that sodium silicate was added so as to obtain a magnetic iron oxide.

Production Example 3 In Production Example 1, the content ratio of silicon element to iron element was set to 0.9.
% Magnetic iron oxide having the properties shown in Table 2 was obtained in the same manner as in Production Example 1 except that sodium silicate was added so as to obtain a magnetic iron oxide.

Production Example 4 In Production Example 1, the content ratio of silicon to iron was 1.7.
% Magnetic iron oxide having the properties shown in Table 2 was obtained in the same manner as in Production Example 1 except that sodium silicate was added so as to obtain a magnetic iron oxide.

Comparative Production Example 1 Production Example 1 was repeated except that sodium silicate was not added.
In the same manner as described above, a magnetic iron oxide having the characteristics shown in Table 2 was obtained.

Comparative Production Example 2 1.5 parts by weight of fine silica powder was mixed with 100 parts by weight of the magnetic iron oxide obtained in Comparative Production Example 1 using a Henschel mixer, and had the properties shown in Table 2. A magnetic iron oxide was obtained.

[0187]

[Table 2] Next, examples of the magnetic developer of the present invention containing the magnetic iron oxide of the above production example will be described.

The following Examples 1 to 5 relate to the present invention (1), Examples 6 to 11 relate to the present invention (2), and Examples 12 to 19 relate to the present invention (3). And Examples 20 to 2
7 relates to the present invention (4).

Example 1 Styrene-n-butyl acrylate-maleic acid n 100 parts-butyl half ester copolymer (copolymerization weight ratio 7.0: 2.5: 0.5, Mw 260,000) Production Example 1 100 parts of the magnetic iron oxide of the above-1 part of negative charge control agent (dialkyl salicylic acid chromium complex)-3 parts of low molecular weight polypropylene The above mixture was melt-kneaded with a biaxial extruder heated to 140 ° C, and the cooled kneaded product was cooled Coarse pulverization was performed with a hammer mill, the coarsely pulverized product was finely pulverized with a jet mill, and the obtained finely pulverized powder was classified with a fixed wall type air classifier to produce a classified powder. In addition, the obtained classified powder is multi-divided using the Coanda effect (Nippon Mining Co., Ltd. elbow jet classifier)
The ultrafine powder and the coarse powder are strictly classified and removed simultaneously to obtain a negatively chargeable magnetic toner having a weight average particle diameter (D4) of 6.9 μm (the content of magnetic toner particles having a particle diameter of 12.7 μm of 0.2% by weight). Obtained.

Using a Henschel mixer, 100 parts of this magnetic toner, 0.10 part of resin fine particles A shown in Table 3 and 1.2 parts of hydrophobic silica fine powder treated with hexamethyldisilazane and then treated with silicone oil were used. The mixture was mixed to prepare a magnetic developer.

Commercial laser beam printer LBP-
The device unit portion (toner cartridge) of 8II (manufactured by Canon Inc.) was modified as shown in FIG. 6, and an urethane rubber elastic blade was brought into contact with an aluminum developing sleeve at a contact pressure of 35 g / cm.

Using the above magnetic developer, the primary charging was -7
An electrostatic latent image for reversal development is formed on the OPC photosensitive drum 3 at 00 V, and a gap (300 μm) is set so that the developer layer on the developing sleeve 6 (including the magnet) is not in contact with the photosensitive drum 3. Bias (f = 1,800 Hz, Vpp =
1600 V) and DC bias (V _DC = −500)
V) is applied to the developing sleeve while _VL is -170.
V, the electrostatic image was developed by reversal development to form a magnetic toner image on the OPC photoreceptor. The formed magnetic toner image was transferred to plain paper at a positive transfer potential, and the plain paper having the magnetic toner image was fixed on the plain paper through a heat and pressure roller fixing device.

An image output test was performed on up to 8,000 sheets under a normal temperature and normal humidity environment (23.5 ° C., 60% RH) while replenishing the magnetic developer successively. Image density measured by a Macbeth reflection densitometer, fog calculated from a comparison between the whiteness of the transfer paper measured by a reflectometer (manufactured by Tokyo Denshoku Co., Ltd.) and the whiteness of the transfer paper after printing solid white, and Table 4 shows the results of the dot image reproducibility obtained by performing the pattern image test shown in FIG.

Similarly, in a high temperature and high humidity environment (32.5
℃, 85% RH) and low temperature and low humidity environment (10 ℃, 15%
RH). Table 4 shows the results.

Example 2 100 parts of styrene-2-ethylhexyl acrylate-n-butyl maleate half ester copolymer (copolymer weight ratio 7.5: 1.5: 1.0, Mw 280,000) 2 parts of magnetic iron oxide 60 parts ・ Negative charge controlling agent (monoazo dye-based chromium complex) 0.9 parts ・ Low molecular weight polypropylene 3 parts The above mixture was melt-kneaded with a biaxial extruder heated to 140 ° C. and cooled. The kneaded product was coarsely pulverized by a hammer mill, and the coarsely pulverized product was finely pulverized by a jet mill. 10. The obtained finely pulverized powder was subjected to air classification to obtain a weight average particle size (D4).
A negatively chargeable magnetic toner having a particle size of 2 μm (the content of the magnetic toner particles having a particle diameter of 12.7 μm or more, 33% by weight) was obtained.

100 parts of the obtained magnetic toner, 0.07 part of resin fine particles B shown in Table 3, and 0.6 part of hydrophobic colloidal silica treated with dimethyl silicone oil were mixed with a Henschel mixer to perform magnetic development. An agent was prepared.

The magnetic developer was supplied to an apparatus unit (toner cartridge) of a laser beam printer LBP-8II, and an image output test was performed on up to 12,000 sheets in the same manner as in Example 1. Table 4 shows the results.

Example 3 100 parts of styrene-n-butyl acrylate (copolymerization weight ratio 7: 3, Mw 300,000) 120 parts of magnetic iron oxide of Production Example 3 Negative charge control agent (monoazo dye-based chromium complex) 2 parts ・ Low molecular weight polypropylene 3 parts Magnetism having a weight average particle diameter (D4) of 4.1 μm (content of magnetic toner particles having a particle diameter of 12.7 μm or more: 0% by weight) in the same manner as in Example 1 using the above materials. A toner was obtained.

A magnetic developer was prepared by mixing 100 parts of the obtained magnetic toner, 0.3 part of resin fine particles C shown in Table 3, and 1.6 parts of hydrophobic colloidal silica treated with silicone oil using a Henschel mixer. Was prepared.

Using this magnetic developer, a multiple-image printing test was performed on up to 8,000 sheets in the same manner as in Example 1. Table 4 shows the results.

Example 4 Styrene-n-ethylhexyl acrylate 100 parts (copolymerization weight ratio 7.5: 2.5, Mw 250,000) 90 parts of magnetic iron oxide of Production Example 4 Negative charge control agent (dialkyl salicylic acid) 1.2 parts-Low molecular weight polypropylene 3 parts Using the above materials, the content of magnetic toner particles having a weight average particle diameter (D4) of 8.5 µm (particle diameter of 12.7 µm or more) in the same manner as in Example 1. 4% by weight) of a magnetic toner.

A Henschel mixer was prepared by mixing 100 parts of the obtained magnetic toner and 1 part of hydrophobic colloidal silica fine powder obtained by treating 0.03 parts of resin fine particles D shown in Table 3 with hexamethyldisilazane and then treating with silicone oil. To prepare a magnetic developer.

The magnetic developer was applied to a laser beam printer LBP-8II in vertical image formation on A4 copy paper.
The image was supplied to an apparatus unit (toner cartridge) of a remodeled machine that was remodeled so as to be 6 sheets / min, and an image output test was performed up to 12,000 sheets in the same manner as in Example 1. Table 4 shows the results.

Example 5 100 parts of styrene-n-butyl acrylate-n-butyl half maleate (copolymerization weight ratio 8: 1.5: 1, Mw 290,000) 50 parts of magnetic iron oxide of Production Example 1 Negative charge control agent (monoazo dye-based chromium complex) 0.8 part ・ Low molecular weight polypropylene 3 parts Weight average particle diameter 1 in the same manner as in Example 1 using the above materials.
A magnetic toner of 3 μm (content of magnetic toner particles having a particle diameter of 12.7 μm or more: 45% by weight) was obtained.

A magnetic toner was prepared by mixing 100 parts of the obtained magnetic toner, 0.05 parts of resin fine particles A shown in Table 3, and 0.4 parts of hydrophobic colloidal silica fine powder treated with silicone oil with a Henschel mixer. A developer was prepared.

This magnetic developer was supplied to an apparatus unit (toner cartridge) of a commercially available laser beam printer LBPA404, and a 5,000-sheet durability test was performed in the same manner as in Example 1. Table 4 shows the results.

Comparative Example 1 A weight average particle size of 7.1 μm (particle size 1) was obtained in the same manner as in Example 1 except that the magnetic iron oxide of Comparative Production Example 1 was used.
A magnetic toner having a content of magnetic toner particles of 2.7 μm or more (0.3% by weight) was obtained. Using the obtained magnetic toner, a magnetic developer was prepared in the same manner as in Example 1, and using the prepared magnetic developer, an image output test was performed on up to 8,000 sheets in the same manner as in Example 1. Table 4 shows the results.

Comparative Example 2 Using the magnetic iron oxide of Production Example 1, a magnetic material having a weight average particle diameter of 14 μm (the content of magnetic toner particles having a particle diameter of 12.7 μm or more: 60% by weight) was obtained in the same manner as in Example 1. A toner was obtained, a magnetic developer was prepared in the same manner as in Example 1, and an image output test was performed in the same manner as in Example 1. Table 4 shows the results.

As compared with the magnetic developer of Example 1, dot reproducibility was inferior, and toner dust was observed.

[0210]

[Table 3]

[0211]

[Table 4] Evaluation method (a) Fog was calculated by the following equation. REFLECTMETER (Tokyo Denshoku Co., Ltd.) was used for measuring the whiteness.

[0212]

(Equation 7) If fog is 1.5% or less, a good image is obtained. (B) For dot reproducibility, an image-drawing test was performed using an 80 × 50 μm checker pattern shown in FIG. 8, and using a microscope, the sharpness of the toner image, the scattering of the toner to the non-image area, and the loss of the black area Was evaluated.

Example 6 100 parts of styrene-2-ethylhexyl acrylate-n-butyl maleate half ester copolymer (copolymerization weight ratio 7: 2: 1, Mw 270,000) 100 parts of magnetic iron oxide of Production Example 1 -1 part of negative charge control agent (dialkyl salicylic acid chromium complex)-3 parts of low molecular weight polypropylene The above mixture is melt-kneaded with a biaxial extruder heated to 140 ° C, and the cooled kneaded material is roughly pulverized with a hammer mill. The coarsely pulverized product was finely pulverized by a jet mill, and the obtained finely pulverized powder was classified by a fixed wall type air classifier to produce a classified powder. In addition, the obtained classified powder is multi-divided using the Coanda effect (Nippon Mining Co., Ltd. elbow jet classifier)
Then, the ultrafine powder and the coarse powder were strictly classified and removed at the same time to obtain a negatively chargeable magnetic toner having a weight average particle diameter (D4) of 6.8 μm.

Table 5 below shows data obtained by measuring the obtained negatively-chargeable magnetic toner by using a Coulter Counter TAII having an aperture of 100 μ as described above. Table 6 shows data relating to the particle size distribution of the present invention (2) such as the content of toner particles having a particle size of 5 μm or less.

[0215]

[Table 5] A magnetic developer was prepared by mixing 100 parts of this magnetic toner and 1.2 parts of hydrophobic silica fine powder treated with silicone oil after being treated with hexamethyldisilazane using a Henschel mixer.

A commercially available laser beam printer LBP-
8II (manufactured by Canon Inc.) was remodeled to 600 dpi,
Further, the developing device was modified as shown in FIG. 4, and a device in which an urethane rubber elastic blade was brought into contact with an aluminum developing sleeve at a contact pressure of 30 g / cm using the above magnetic developer in a low-temperature, low-humidity environment (15 ° C. / At 10% RH), the durability of 10,000 sheets was evaluated in the same manner as in the above example. Table 7 shows the results. Very good results were obtained as shown in the table. The image density was obtained by measuring the average of five points using a Macbeth reflection densitometer. The amount of consumption was 1,000 prints at 1,000 and 4,000 prints at an image ratio of 4%. It is the average consumption.

Examples 7 to 9 Toners were prepared in the same manner as in Example 6 except that the magnetic iron oxides of Production Examples 2, 3, and 4 were used as the magnetic iron oxides.
The toner having the weight average particle size and the particle size distribution shown in Table 1 was prepared. When these toners were evaluated in the same manner as in Example 6, good results were obtained as shown in Table 7.

Examples 10 and 11 Toners having weight average particle diameters and particle size distributions as shown in Table 6 were prepared in the same manner as in Example 6 using the formulation of Example 6, and evaluated in the same manner as in Example 6. As a result, although the dot reproducibility was slightly inferior, excellent durability was exhibited as shown in Table 7.

Comparative Examples 3 and 4 Toners were prepared in the same manner as in Example 6 except that the magnetic iron oxides of Comparative Production Examples 1 and 2 were used.
The toner having the weight average particle size and the particle size distribution shown in Table 1 was prepared. When these toners were evaluated in the same manner as in Example 6, as shown in Table 7, the durability was significantly inferior to Examples 6 to 11.

[0220]

[Table 6]

[0221]

[Table 7] Example 12 100 parts of styrene-butyl acrylate-divinylbenzene copolymer (copolymerization ratio 80 / 19.5 / 0.5, Mw 320,000) 100 parts of magnetic iron oxide of Production Example 1 4 parts of low molecular weight polypropylene・ Chromium complex of monoazo dye 2 parts The above mixture is melt-kneaded by a biaxial kneading extruder heated to 140 ° C., and the cooled kneaded material is coarsely pulverized by a hammer mill, and the coarsely pulverized material is finely pulverized by a jet mill. The obtained finely pulverized product was classified and removed by a multi-segmentation classifier to obtain a classified magnetic toner having a weight average particle size of 6.3 μm.

Next, fine silica silicate Aerosil # 300
After treating 100 parts (manufactured by Nippon Aerosil Co., Ltd.) with 30 parts of dimethyldichlorosilane (carbon content: 2.2% by weight), dimethyl silicone oil KF-96 100c
s (manufactured by Shin-Etsu Chemical Co., Ltd.) was mixed with 15 parts diluted with a solvent, and the solvent was evaporated and removed under reduced pressure.
C. and a carbon content of 6.5% by weight (ie,
Silica fine powder having a carbon adhesion amount of 4.3% by weight by silicone oil treatment was obtained.

A magnetic developer was obtained by externally adding, using a Henschel mixer, 1.0 part of dimethyldichlorosilane and then treating with dimethylsilicone oil to 100 parts of the above classified magnetic toner.

This was put into a Canon laser beam printer LBP-8II modified from 8 sheets / min to 16 sheets / min and imaged up to 8,000 sheets under normal temperature and normal humidity (23 ° C., 60% RH). The test was performed.

Similarly, high temperature and high humidity (32.5 ° C., 90
% RH) and low temperature and low humidity (10 ° C., 15% RH).

The image density measured by a Macbeth reflection densitometer, the whiteness of the transfer paper measured by a reflectometer (manufactured by Tokyo Denshoku Co., Ltd.), and the whiteness of the entire white image after printing were measured in the same manner as in the above embodiment. Fog calculated from the comparison of
Table 8 shows the results of the dot image reproducibility obtained by performing the pattern image test shown in FIG. 8 and the results of the omission during the transfer of the print to the transparency film.

Example 13 Styrene-butyl acrylate-divinylbenzene copolymer 100 parts (copolymerization ratio 80 / 19.5 / 0.5, Mw 320,000) 120 parts of magnetic iron oxide of Production Example 2 Low molecular weight 4 parts of polypropylene 3 parts of chromium complex of monoazo dye Using the above materials, a magnetic toner having a weight average particle diameter of 5.4 μm was obtained in the same manner as in Example 12.

Next, after treating 100 parts of Aerosil # 200 with 20 parts of dimethyldichlorosilane (carbon content: 1.1% by weight) as a treated silicic acid fine powder, dimethyl silicone oil KF-96 100 cs After mixing 15 parts (manufactured by Shin-Etsu Chemical Co., Ltd.) with a solution diluted with a solvent, the solvent was evaporated under reduced pressure, and then a heat treatment was performed at 190 ° C. to obtain a carbon content of 5.2% by weight ( (Attached carbon amount by silicone oil treatment: 4.1% by weight) to obtain a treated silicic acid fine powder.

A magnetic developer was obtained by externally adding, with a Henschel mixer, 1.6 parts of dimethyldichlorosilane and then treating with dimethylsilicone oil to 100 parts of the above classified magnetic toner.

Using this magnetic developer, an image output test was performed in the same manner as in Example 12. Table 8 shows the results.

Example 14 Styrene-butyl acrylate-divinylbenzene copolymer 100 parts (copolymerization ratio 80 / 19.5 / 0.5, Mw 320,000) Magnetic iron oxide of Production Example 3 80 parts Low molecular weight Polypropylene 3 parts • Monoazo dye chromium complex 0.8 part Using the above materials, a magnetic toner classified product having a weight average particle size of 7.8 μm was obtained in the same manner as in Example 12.

Next, the treated silica fine powder was used in Example 1
The fine silica powder treated with dimethylsilicone oil after the dimethyldichlorosilane treatment used in Example 3 was externally added to 100 parts of the above classified magnetic toner using a Henschel mixer to obtain 1.0 part of a magnetic developer.

Using this magnetic developer, an image output test was performed in the same manner as in Example 12. Table 8 shows the results.

Example 15 Styrene-butyl acrylate-divinylbenzene copolymer 100 parts (copolymerization ratio 80 / 19.5 / 0.5, Mw 320,000) 90 parts of magnetic iron oxide of Production Example 4 Low molecular weight 3 parts of polypropylene • 1 part of chromium complex of monoazo dye 1 part of the above material was used to obtain a classified magnetic toner having a weight average particle size of 6.9 μm in the same manner as in Example 12.

Next, after treating 100 parts of Aerosil # 200 with 30 parts of trimethylchlorosilane (carbon content: 3.5% by weight) as treated silica fine powder, dimethyl silicone oil KF-96 100cs ( (Shin-Etsu Chemical Co., Ltd.) was mixed with 10 parts diluted with a solvent, the solvent was evaporated under reduced pressure, and a heat treatment was performed at 190 ° C. to obtain a carbon content of 7.1% by weight (silicone). (Attached carbon by oil treatment: 3.6% by weight) to obtain a treated fine silica powder.

To 100 parts of the above classified magnetic toner, 1.0 part of trimethylchlorosilane was treated and then treated with dimethyl silicone oil. Silica fine powder was externally added with a Henschel mixer to obtain a magnetic developer.

Using this magnetic developer, an image output test was conducted in the same manner as in Example 12. Table 8 shows the results.

Example 16 Aerosil # 200 100 as treated silica fine powder
After treating with 25 parts of dimethyldichlorosilane (carbon content: 1.5% by weight), mixed with 5 parts of dimethylsilicone oil KF-96 100cs (manufactured by Shin-Etsu Chemical Co., Ltd.) diluted with a solvent. After that, the solvent was volatilized under reduced pressure, and a heat treatment was performed at 190 ° C. to obtain a carbon content of 4.6% by weight (carbon adhesion amount by silicone oil treatment: 3.1% by weight). A fine silica powder was obtained.

Magnetic toner classified product 10 used in Example 15
With respect to 0 part, 1.0 part of the above treated silica fine powder was externally added with a Henschel mixer to obtain a magnetic developer.

Using this magnetic developer, an image output test was performed in the same manner as in Example 12. Table 8 shows the results.

Example 17 Aerosil # 200 100 as a treated silicic acid fine powder
After treating with 20 parts of dimethyldichlorosilane (carbon content: 1.1% by weight), dimethyl silicone oil KF-96 100cs (manufactured by Shin-Etsu Chemical Co., Ltd.) 20
Part was diluted with a solvent, mixed with the solvent, the solvent was evaporated under reduced pressure, and then heated at 190 ° C. to obtain a carbon content of 7.3% by weight (the amount of carbon deposited by silicone oil treatment). : 6.2% by weight).

Magnetic toner classified product 10 used in Example 15
With respect to 0 part, 1.0 part of the above treated silica fine powder was externally added with a Henschel mixer to obtain a magnetic developer.

Using this magnetic developer, an image output test was performed in the same manner as in Example 12. Table 8 shows the results.

Example 18 Aerosil # 300 100 as treated silica fine powder
Part was treated with 30 parts of dimethyldichlorosilane (carbon content: 2.2% by weight), and then α-methylstyrene-modified silicone oil KF-410 (manufactured by Shin-Etsu Chemical Co., Ltd.)
After mixing with 15 parts diluted with a solvent, the solvent was evaporated under reduced pressure, and then heat treatment was performed at 190 ° C.
A treated silicic acid fine powder having a carbon content of 6.1% by weight (carbon adhesion amount by silicone oil treatment: 3.9% by weight) was obtained.

Magnetic toner classified product 10 used in Example 15
With respect to 0 part, 1.0 part of the above treated silica fine powder was externally added with a Henschel mixer to obtain a magnetic developer.

Using this magnetic developer, an image output test was performed in the same manner as in Example 12. Table 8 shows the results.

Example 19 Styrene-butyl acrylate-divinylbenzene copolymer 100 parts (copolymerization ratio 80 / 19.5 / 0.5, Mw 320,000) Magnetic iron oxide of Production Example 3 60 parts Low molecular weight 3 parts of polypropylene. 1 part of a chromium complex of a monoazo dye. 1 part of the above material was used to obtain a classified magnetic toner having a weight average particle diameter of 11.6 μm in the same manner as in Example 12.

Next, the treated silica fine powder was prepared as in Example 1
0.6 parts of the silicic acid fine powder treated with dimethylsilicone oil after the dimethyldichlorosilane treatment used in 3 was added externally to 100 parts of the above classified magnetic toner using a Henschel mixer to obtain a magnetic developer.

This was put into a Canon LBPA404 laser beam printer, and an image output test was performed in the same manner as in Example 12. Table 8 shows the results.

Comparative Example 5 A magnetic toner having a weight average particle size of 6.5 μm was obtained in the same manner as in Example 12, except that the magnetic iron oxide of Comparative Production Example 1 was used.

Next, the treated silica fine powder was prepared as in Example 1
The fine silica powder treated with dimethylsilicone oil after the dimethyldichlorosilane treatment used in Example 3 was externally added to 100 parts of the above-mentioned magnetic toner classified product with a Henschel mixer to obtain 1.0 part of a magnetic developer.

Using this magnetic developer, an image output test was performed in the same manner as in Example 12. Table 8 shows the results.

Comparative Example 6 100 parts of Aerosil # 200 were treated with 20 parts of dimethyldichlorosilane to obtain a treated fine silica powder.

Comparative Example 5 was obtained by adding 1.0 part of the treated silica fine powder to Comparative Example 5.
The magnetic developer was externally added to 100 parts of the classified magnetic toner used in the above with a Henschel mixer to obtain a magnetic developer.

Using this magnetic developer, an image output test was performed in the same manner as in Example 12. Table 8 shows the results.

Comparative Example 7 A classified magnetic toner having a weight average particle size of 6.4 μm was obtained in the same manner as in Example 12, except that the magnetic iron oxide of Comparative Production Example 2 was used.

With respect to 100 parts of the classified magnetic toner,
1.0 part of the fine silica powder treated with dimethyldichlorosilane used in Comparative Example 6 was externally added with a Henschel mixer to obtain a magnetic developer.

Using this magnetic developer, an image output test was performed in the same manner as in Example 12. Table 8 shows the results.

[0259]

[Table 8] Example 20 100 parts of styrene-butyl acrylate-divinylbenzene copolymer (copolymerization ratio 80 / 19.5 / 0.5, Mw 320,000)-90 parts of magnetic iron oxide of Production Example 1-3 parts of low molecular weight polypropylene・ Chromium complex of monoazo dye 0.8 part The above mixture is melt-kneaded by a twin-screw kneading extruder heated to 140 ° C., and the cooled kneaded material is coarsely pulverized by a hammer mill, and the coarsely pulverized material is finely pulverized by a jet mill. The finely pulverized material obtained by the pulverization was classified and removed with a multi-segmentation classifier to obtain a classified magnetic toner having a weight average particle size of 6.6 μm.

Next, fine silica aerosol # 200
After treating 100 parts (manufactured by Nippon Aerosil Co., Ltd.) with 20 parts of trimethylchlorosilane (specific surface area: 160 m ² /
g), dimethyl silicone oil KF-96 100c
s (manufactured by Shin-Etsu Chemical Co., Ltd.) was mixed with 10 parts diluted with a solvent, and the solvent was evaporated and removed under reduced pressure.
Heat treatment was carried out at 90 ° C. to obtain silicic acid fine powder having a specific surface area of 90 m ² / g (that is, 0.56 times the specific surface area before the silicone oil treatment).

To 100 parts of the above classified magnetic toner, 1.0 part of trimethylchlorosilane was treated and then treated with dimethylsilicone oil. Fine silica powder was externally added using a Henschel mixer to obtain a magnetic developer.

This was put into a Canon laser beam printer LBP-8II modified from 8 sheets / min to 16 sheets / min and imaged up to 8,000 sheets under normal temperature and normal humidity (23 ° C., 60% RH). The test was performed.

Similarly, high temperature and high humidity (32.5 ° C., 90
% RH) and low temperature and low humidity (10 ° C., 15% RH).

The image density measured by a Macbeth reflection densitometer, the whiteness of the transfer paper measured by a reflectometer (manufactured by Tokyo Denshoku Co., Ltd.), and the whiteness of the entire white image after printing were measured in the same manner as in the above embodiment. Fog calculated from the comparison of
Table 9 shows the results of the dot image reproducibility by performing the pattern image test shown in FIG. 8 and the results of the omission during transfer of the print to the transparency film.

Example 21 100 parts of styrene-butyl acrylate-divinylbenzene copolymer (copolymerization ratio 80 / 19.5 / 0.5, Mw 320,000) 100 parts of magnetic iron oxide of Production Example 2 low molecular weight Polypropylene 4 parts • Chromium complex of monoazo dye 1 part Using the above materials, a magnetic toner classified product having a weight average particle diameter of 6.2 μm was obtained in the same manner as in Example 20.

Next, after treating 100 parts of Aerosil # 300 with 30 parts of dimethyldichlorosilane (specific surface area: 230 m ² / g) as treated silica fine powder, dimethyl silicone oil KF-96 100 cs (Shin-Etsu) After mixing 15 parts with a solvent diluted with a solvent, the solvent was evaporated under reduced pressure, and then heated at 150 ° C. to obtain a specific surface area of 120 m ² / g (before silicone oil treatment). (0.52 times the specific surface area) of the treated silica fine powder.

A magnetic developer was obtained by externally adding, with a Henschel mixer, 1.0 part of dimethyldichlorosilane and then treating with dimethylsilicone oil to 100 parts of the above classified magnetic toner.

Using this magnetic developer, an image output test was performed in the same manner as in Example 20. Table 9 shows the results.

Example 22 Styrene-butyl acrylate-divinylbenzene copolymer 100 parts (copolymerization ratio 80 / 19.5 / 0.5, Mw 320,000) Magnetic iron oxide of Production Example 3 80 parts Low molecular weight 3 parts of polypropylene • 1 part of a chromium complex of a monoazo dye 1 part of the above material was used to obtain a classified magnetic toner having a weight average particle diameter of 7.5 μm in the same manner as in Example 20.

Next, the treated silica fine powder was used in Example 2
1.0 part of the silicic acid fine powder treated with dimethylsilicone oil after the dimethyldichlorosilane treatment used in 1 was added to 100 parts of the above classified magnetic toner using a Henschel mixer to obtain a magnetic developer.

Using this magnetic developer, an image output test was performed in the same manner as in Example 20. Table 9 shows the results.

Example 23 100 parts of a styrene-butyl acrylate-divinylbenzene copolymer (copolymerization ratio 80 / 19.5 / 0.5, Mw 320,000) 120 parts of magnetic iron oxide of Production Example 4 Low molecular weight 4 parts of polypropylene 4 parts of chromium complex of monoazo dye Using the above materials, a magnetic toner classified product having a weight average particle size of 5.2 μm was obtained in the same manner as in Example 20.

Next, after treating 100 parts of Aerosil # 200 with 20 parts of dimethyldichlorosilane as a treated fine silica powder (specific surface area: 180 m ² / g), dimethyl silicone oil KF-96 100 cs (Shin-Etsu) After mixing 15 parts with a solvent diluted with a solvent, the solvent was evaporated under reduced pressure, and then heated at 150 ° C. to obtain a specific surface area of 100 m ² / g (before silicone oil treatment). (0.56 times the specific surface area) of the treated silica fine powder.

To 100 parts of the above classified magnetic toner, 1.6 parts of dimethyldichlorosilane-treated and then treated with dimethylsilicone oil was externally added with a Henschel mixer to obtain a magnetic developer.

Using this magnetic developer, an image output test was performed in the same manner as in Example 20. Table 9 shows the results.

Example 24 Styrene-butyl acrylate-divinylbenzene copolymer 100 parts (copolymerization ratio 80 / 19.5 / 0.5, Mw 320,000) Magnetic iron oxide of Production Example 1 80 parts Low molecular weight 3 parts of polypropylene. 1 part of a chromium complex of a monoazo dye. 1 part of the above material was used to obtain a classified magnetic toner having a weight average particle size of 7.2 μm in the same manner as in Example 20.

Next, after treating 100 parts of Aerosil # 300 with 30 parts of dimethyldichlorosilane as a treated fine silica powder (specific surface area: 230 m ² / g), dimethyl silicone oil KF-96 100 cs (Shin-Etsu) After mixing 20 parts (manufactured by Chemical Industry Co., Ltd.) with a solution diluted with a solvent, the solvent was volatilized under reduced pressure, and a heat treatment was performed at 150 ° C. to obtain a specific surface area of 100 m ² / g (before silicone oil treatment). (0.43 times the specific surface area) of the treated silica fine powder.

To 100 parts of the above classified magnetic toner, 0.8 part of dimethyldichlorosilane and then treated with dimethylsilicone oil were externally added with a Henschel mixer to obtain a magnetic developer.

Using this magnetic developer, an image output test was performed in the same manner as in Example 20. Table 9 shows the results.

Example 25 Aerosil # 300 100 as treated silica fine powder
Was treated with 35 parts of dimethyldichlorosilane (specific surface area: 210 m ² / g), and then mixed with 5 parts of dimethyl silicone oil KF-96 100cs (manufactured by Shin-Etsu Chemical Co., Ltd.) diluted with a solvent. After the solvent was volatilized under reduced pressure, a heat treatment was performed at 150 ° C. to obtain a treated silica fine powder having a specific surface area of 125 m ² / g (0.59 times the specific surface area before the silicone oil treatment). Was.

Magnetic toner classified product 10 used in Example 24
0.8 parts of the above treated silicic acid fine powder was externally added to 0 parts with a Henschel mixer to obtain a magnetic developer.

Using this magnetic developer, an image output test was performed in the same manner as in Example 20. Table 9 shows the results.

Example 26 Aerosil # 200 100 as treated silica fine powder
Part was treated with 20 parts of trimethylchlorosilane (specific surface area: 160 m ² / g), and α-methylstyrene-modified silicone oil KF-410 (manufactured by Shin-Etsu Chemical Co., Ltd.)
After mixing with 15 parts diluted with a solvent, the solvent was volatilized under reduced pressure, and then obtained by performing a heat treatment at 150 ° C.
A treated silica fine powder having a specific surface area of 80 m ² / g (0.50 times the specific surface area before the silicone oil treatment) was obtained.

Classified Product of Magnetic Toner 10 Used in Example 24
0.8 parts of the above treated silicic acid fine powder was externally added to 0 parts with a Henschel mixer to obtain a magnetic developer.

Using this magnetic developer, an image output test was performed in the same manner as in Example 20. Table 9 shows the results.

Example 27 Styrene-butyl acrylate-divinylbenzene copolymer 100 parts (copolymerization ratio 80 / 19.5 / 0.5, Mw 320,000) Magnetic iron oxide of Production Example 3 60 parts Low molecular weight Polypropylene 3 parts • Monoazo dye chromium complex 2 parts Using the above materials, a magnetic toner classified product having a weight average particle diameter of 11.8 μm was obtained in the same manner as in Example 20.

Next, the treated silica fine powder was used in Example 2
0.6 parts of the silicic acid fine powder treated with dimethylsilicone oil after the dimethyldichlorosilane treatment used in 1 was added to 100 parts of the above classified magnetic toner using a Henschel mixer to obtain a magnetic developer.

This was put into a Canon LBPA404 laser beam printer, and an image output test was performed in the same manner as in Example 20. Table 9 shows the results.

Comparative Example 8 A classified magnetic toner having a weight average particle size of 6.8 μm was obtained in the same manner as in Example 20, except that the magnetic iron oxide of Comparative Production Example 1 was used.

Next, the treated silica fine powder was prepared in Example 2
The silica powder finely treated with dimethylsilicone oil after the treatment with trimethylchlorosilane used in Example No. 0 was externally added to 100 parts of the above classified magnetic toner with 1.0 part of a Henschel mixer to obtain a magnetic developer.

Using this magnetic developer, an image output test was performed in the same manner as in Example 20. Table 9 shows the results.

Comparative Example 9 100 parts of Aerosil # 200 were treated with 20 parts of dimethyldichlorosilane to obtain a treated fine silica powder.

Comparative Example 8 was obtained by adding 1.0 part of this treated silicic acid fine powder.
The magnetic developer was externally added to 100 parts of the classified magnetic toner used in the above with a Henschel mixer to obtain a magnetic developer.

Using this magnetic developer, an image output test was performed in the same manner as in Example 20. Table 9 shows the results.

Comparative Example 10 A classified magnetic toner having a weight average particle size of 6.7 μm was obtained in the same manner as in Example 20, except that the magnetic iron oxide of Comparative Production Example 2 was used.

With respect to 100 parts of the classified magnetic toner,
1.0 part of the fine silica powder treated with dimethyldichlorosilane used in Comparative Example 9 was externally added with a Henschel mixer to obtain a magnetic developer.

Using this magnetic developer, an image output test was performed in the same manner as in Example 20. Table 9 shows the results.

[0298]

[Table 9]

[0299]

According to the present invention (1), a magnetic iron oxide characterized by a distribution of a silicon element is prepared by adding a weight average particle diameter of 13.5 μm.
m, the content of magnetic toner particles having a particle diameter of 12.7 μm or more is 50% by weight or less, and the magnetic toner particles are used as a magnetic material of many magnetic toner particles having a small particle diameter. The environmental stability and development characteristics of the magnetic developer can be improved by using a magnetic developer to which resin fine particles having a charge characteristic of 0.03 to 2.0 μm and having the same polarity as the magnetic toner are added.

According to (2) of the present invention, the weight average particle diameter is from 6 to 8 using magnetic iron oxide having a characteristic distribution of silicon element.
By using a magnetic toner having a particle size of μm or 5 μm or less, high resolution, high density, low fogging, little scattering, and excellent durability are exhibited.

According to the present invention (3, 4), a magnetic iron oxide having a characteristic distribution of silicon element is used as a magnetic substance of a magnetic toner, and is treated with a silicone oil or a silicone varnish in a specific treatment. The environmental stability and development characteristics of the magnetic developer can be improved by using the magnetic developer to which the inorganic fine powder is added.

[Brief description of the drawings]

FIG. 1 is a diagram showing a melting curve of a magnetic iron oxide.

FIG. 2 is a schematic diagram of magnetic iron oxide particles for explaining the distribution of a silicon compound.

FIG. 3 is a schematic explanatory view of a charge amount measuring device.

FIG. 4 is a schematic explanatory view showing a specific example of an image forming apparatus (with an elastic blade).

FIG. 5 is a schematic explanatory view showing a specific example of an image forming apparatus (with a magnetic blade).

FIG. 6 is a schematic explanatory view showing a specific example of an image forming apparatus unit.

FIG. 7 is a block diagram illustrating a specific example of a facsimile apparatus.

FIG. 8 is an explanatory diagram of a checker pattern for testing development characteristics of a magnetic developer.

FIG. 9 is a diagram showing a range of the amount of toner particles having a particle size of 5 μm or less as defined in the present invention (2).

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Developing apparatus 2 Developer container 3 Latent image carrier 4 Transfer means 5 Laser light or analog light 6 Developing sleeve 7 Heating and pressurizing fixing means 8 Cleaning blade 9 Elastic blade 11 Charger 12 Bias applying means 13 Magnetic developer 14 Cleaning means 15 Magnetic field generating means 16 Erase exposure

──────────────────────────────────────────────────続 き Continuation of the front page (72) The inventor Naokuni Kobori 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (56) References JP-A-2-284152 (JP, A) JP-A Heisei 1-2221754 (JP, A) JP-A-1-231060 (JP, A) JP-A-2-284152 (JP, A) JP-A-5-72801 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G03G 9/083

Claims (4)

(57) [Claims] 1. A magnetic toner containing at least a binder resin and magnetic iron oxide, and a magnetic developer containing fine resin particles, wherein the magnetic toner has a weight average particle diameter of 13.5 μm or less. In the particle size distribution, the content of the magnetic toner particles having a particle size of 12.7 μm or more is 50% by weight or less, and the content of the silicon element of the magnetic iron oxide is based on the iron element. 0.5 to 4% by weight, and the ratio of the content B of the silicon element present when the iron dissolution rate of the magnetic iron oxide is up to 20% by weight and the total content A of the silicon element in the magnetic iron oxide (B / A) × 100 is 44 to 84%, and the ratio (C / A) × 100 of the content C of the silicon element existing on the surface of the magnetic iron oxide to the content A is 10 to 55%.
%, Wherein the resin fine particles have an average particle diameter of 0.03 to 2.0 μm and have a charging characteristic of the same polarity as that of the magnetic toner. 2. A magnetic developer containing a magnetic toner containing at least a binder resin and magnetic iron oxide, wherein the magnetic iron oxide has a silicon element content of 0% based on the iron element. 0.5 to 4% by weight, and the ratio of the content B of the silicon element present when the solubility of the iron element of the magnetic iron oxide is up to 20% by weight and the total content A of the silicon element of the magnetic iron oxide ( (B / A) × 100 is 44 to 84%, and the ratio (C / A) × 100 of the content C of the silicon element existing on the surface of the magnetic iron oxide to the content A is 10 to 55%.
%, The magnetic toner has a weight average particle size of 6 to 8 μm,
The magnetic toner particles having a particle size of not more than 1 m are contained in an amount of 17 to 60% by number, and the magnetic toner particles having a particle size of 6.35 to 10.08 μm are contained in an amount of 5 to 50% by number, and 12.7 μm.
The magnetic toner particles having a particle diameter of not less than 2.0% by volume are contained in a magnetic toner particle group having a particle diameter of not more than 5 μm. Represents the number% of the magnetic toner particles having the following formula, V represents the volume% of the magnetic toner particles having a particle size of 5 μm or less, and k represents a positive number of 4.6 to 6.7. Here, N indicates a positive number of 17 to 60. A magnetic developer having a particle size distribution satisfying the following. 3. A magnetic toner containing at least a binder resin and a magnetic iron oxide, and a magnetic developer containing a hydrophobic inorganic fine powder, wherein the magnetic iron oxide has a silicon element content of the magnetic iron oxide,
0.5 to 4% by weight based on the iron element, the content B of the silicon element present when the iron dissolution rate of the magnetic iron oxide is up to 20% by weight, and the total content of the silicon element in the magnetic iron oxide The ratio (B / A) × 100 to the amount A is 44 to 84%,
The ratio (C / A) × 100 of the content C of silicon element present on the surface of the magnetic iron oxide to the content A is 10 to 55%, and the hydrophobic inorganic fine powder is silicone oil or silicone. A magnetic developer, which is a fine powder treated with a varnish, wherein the amount of carbon deposited by the treatment is 3 to 8% by weight. 4. A magnetic toner containing at least a binder resin and a magnetic iron oxide and a magnetic developer containing a hydrophobic inorganic fine powder, wherein the magnetic iron oxide has a silicon element content of the magnetic iron oxide,
0.5 to 4% by weight based on the iron element, the content B of the silicon element present when the iron dissolution rate of the magnetic iron oxide is up to 20% by weight, and the total content of the silicon element in the magnetic iron oxide The ratio (B / A) × 100 to the amount A is 44 to 84%,
The ratio (C / A) × 100 of the content C of silicon element present on the surface of the magnetic iron oxide to the content A is 10 to 55%, and the hydrophobic inorganic fine powder is silicone oil or silicone. A fine powder treated with a varnish, wherein the specific surface area of the hydrophobic inorganic fine powder is 0.4 to 0.6 times the specific surface area before the treatment with the silicone oil or silicone varnish. Magnetic developer.