JP3131753B2 - Magnetic toner and image forming method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic toner for visualizing an electrostatic latent image in an image forming method such as electrophotography and electrostatic recording, and an image forming method.

[0002]

2. Description of the Related Art U.S. Pat. No. 3,909,258 proposes a method of developing using a magnetic toner having electrical conductivity. This supports the conductive magnetic toner on a cylindrical conductive sleeve having magnetism inside,
This is brought into contact with the electrostatic image and developed. At this time, in the developing unit, a conductive path is formed by the 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. The toner particles adhere to the image area by the cloning force and are developed. The developing method using the conductive magnetic toner is an excellent method that avoids the problems associated with the conventional two-component developing method, but because the toner is conductive,
There is a problem that it is difficult to electrostatically transfer the developed image from the recording medium to a final supporting member such as plain paper.

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, the toner particles are frictionally charged by friction between the toner particles, friction between the toner particles and a sleeve, and 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 proper manner, the toner particles can be aggregated with each other and sufficiently rubbed with the sleeve, thereby obtaining an excellent image.

However, the developing method using the improved insulating toner has an unstable factor relating to the insulating toner to be used. The reason is that a fine powdered magnetic material is mixed and dispersed in the insulating toner in a considerable amount, and a part of the magnetic material is exposed on the surface of the toner particles. Fluidity and triboelectricity are affected, and as a result, various characteristics required for the magnetic toner, such as development characteristics and durability of the magnetic toner, are changed or deteriorated.

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.

In addition, 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.

Further, 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.

Japanese Patent Application Laid-Open No. 61-34070 proposes a method for producing ferric oxide by adding a hydrosilosilicate 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.

On the other hand, with respect to fixing, which is the final step for obtaining a print, low-temperature fixing is demanded from the viewpoint of energy saving. The most common fixing method at present is a pressure heating method using a heat roller.

In the pressure heating method using a heating roller, fixing is performed by allowing the toner image surface of the sheet to be fixed to pass through the surface of a heat roller having a surface formed of a material having a releasable property with respect to the toner, while contacting the surface under pressure. Things.
In this method, since the surface of the heat roller and the toner image of the sheet to be fixed come into contact with each other under pressure, the heat efficiency at the time of fusing the toner image onto the sheet to be fixed is extremely good, and the fixing can be performed quickly. And is very effective in high speed electrophotographic copiers. However, in the above method, a part of the toner image adheres to and transfers to the fixing roller surface because the surface of the heat roller and the toner image come into contact with each other under pressure in a molten state. An offset phenomenon may occur, and the sheet to be fixed may be stained. Preventing toner from adhering to the surface of the heat fixing roller is one of the essential conditions of the heat roller fixing method.

Conventionally, for the purpose of preventing toner from adhering to the surface of the fixing roller, for example, the surface of the roller is formed of a material having excellent releasability with respect to the toner, such as silicone rubber or fluorine-based resin, and the surface thereof is further prevented from being offset. In addition, in order to prevent the roller surface from being fatigued, the roller surface is coated with a thin film of a liquid having good releasability such as silicone oil. However, this method is extremely effective in preventing toner offset, but has a problem that a fixing device is complicated because a device for supplying an anti-offset liquid is required. . Therefore, it is not preferable that the offset is prevented by supplying the offset preventing liquid. Rather, it is desired to develop a toner having a wide fixing temperature range and high anti-offset properties. In order to increase the releasability of the toner, a method of adding a wax such as low-molecular-weight polyethylene or polypropylene, which sufficiently melts when heated, has also been used. The charging characteristics become unstable, and the durability tends to decrease. Therefore, various attempts have been made to improve the binder resin as another method.

For example, a method is known in which the glass transition temperature (Tg) and the molecular weight of the binder resin in the toner are increased to improve the melt viscoelasticity of the toner. However, such a method has a problem that, when the offset phenomenon is improved, the fixing property becomes insufficient, and the fixing property at a low temperature, that is, the low-temperature fixing property required for high-speed development and energy saving is deteriorated.

In general, in order to improve the low-temperature fixability of a toner, it is necessary to lower the viscosity of the toner at the time of melting and to increase the area of adhesion to a fixing base material. Low molecular weight is required.

When the Tg of the binder is lowered, the toner tends to block at a high temperature, which affects the storage stability.

In particular, with the recent miniaturization of copiers and laser beam printers, heat sources such as a fixing device and an electrical unit are very close to a cleaner and a developing device. It has become to.

That is, it was very difficult to simultaneously satisfy the low-temperature fixing property, the blocking resistance, and the offset prevention property.

In order to solve this problem, Japanese Patent Application Laid-Open No.
Japanese Patent No. 16043 proposes a toner using a resin obtained by polymerizing a vinyl monomer in the presence of a reactive polyester resin and polymerizing it through a crosslinking reaction, an addition reaction, and a grafting reaction in the course of polymerization. However, the functions of the resins cannot be sufficiently utilized in terms of low-temperature fixability and offset prevention.

Further, when used in a magnetic one-component developer, the dispersion of magnetic iron oxide tends to be non-uniform.

In addition, two types of polyester resin and gel content are simply different (gelation degree of 80% or more and gelation degree of 1
(Less than 0%), a toner using a resin blended with a vinyl resin is proposed in Japanese Patent Publication No. 1-15063, which has good low-temperature fixability but is used in a one-component magnetic developer. In this case, the dispersion of the magnetic iron oxide tends to be non-uniform.

As described above, in a system in which a vinyl polymer and a polyester resin are mixed and used as a binder resin, two kinds of resins having different physical properties are used. Therefore, dispersion of a toner constituent material such as a colorant in the resin is performed. Are more likely to be non-uniform than when a resin having a uniform composition is used. In particular, in the case of a one-component toner used for jumping development, when the dispersion of the magnetic material becomes non-uniform, the deterioration of dot reproducibility due to the occurrence of fog and toner scattering tends to be conspicuous,
Further, in an image output test for thousands of sheets, a decrease in density is conspicuous, which is not practically preferable. That is, when a one-component magnetic toner is obtained by mixing a vinyl polymer and a polyester resin, it has not yet been achieved that the fixing property, the offset property and the image quality are simultaneously satisfied.

In recent years, the functions of image forming apparatuses using electrophotography, such as copiers and laser beam printers, have been diversified, and higher definition and higher image quality of toner images have been demanded. In order to faithfully reproduce a latent image without being crushed or cut off, it is effective to reduce the particle size of toner particles as proposed in JP-A-1-112253. However, as the particle size of the toner is reduced, the pulverization efficiency is reduced due to the occurrence of fusion of the toner composition to the inner wall of the pulverizer in the pulverization step, and the various disadvantages described above are more likely to occur.

Also, since the fluidity of the toner decreases as the particle size of the toner decreases, it is possible to easily improve the fluidity by adding a large amount of inorganic fine powder to maintain the fluidity of the toner. However, this may cause damage to the photoconductor, easily cause fusion of the toner to the photoconductor, filming, and the like, and worsen toner scattering.

In addition, with the recent rapid rationalization of office work,
An image forming method capable of copying or printing out a large amount in a short time is desired. However, in an image forming method in which the rotation speed of the outer diameter of the latent image holding member is relatively high, an image to be output is an image having only a contour portion. There is also a problem that a transfer failure called “missing during transfer” easily occurs.

[0028]

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

Another object of the present invention is to provide a magnetic toner having a high image density and excellent image reproducibility.

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

It is a further object of the present invention to provide a magnetic toner having good fixability and offset resistance.

Another object of the present invention is to provide a magnetic toner having a high image density even in long-term durability in a high humidity environment.

It is a further object of the present invention to provide a magnetic toner which is fixed at a low temperature, has excellent anti-offset properties and anti-blocking properties, and does not adversely affect its performance even in a high-temperature atmosphere in a small machine. is there.

It is a further object of the present invention to provide a magnetic toner which is excellent in pulverizability in a pulverizing step in producing a toner and which can be efficiently produced without fusing to an inner wall of the apparatus.

It is another object of the present invention to provide a transfer process in which a high-quality image faithful to a latent image can be obtained regardless of the conditions of a transfer material in an image forming method by pressure transfer such as a contact transfer method. An object of the present invention is to provide an image forming method having the following.

It is a further object of the present invention to provide an image forming method in which a phenomenon such as "transfer missing" or the like is suppressed.

It is a further object of the present invention to provide an image forming method using a toner which gives a high quality image without any omission during transfer even when various transfer materials such as thick transfer paper are used.

[0038]

The present invention relates to a magnetic toner containing at least a binder resin and magnetic iron oxide, wherein the magnetic toner has a weight average particle diameter of 13.5 μm.
In the particle size distribution of the magnetic toner,
Content of magnetic toner particles of 2.7 μm or more is 50% by weight
The magnetic iron oxide has a silicon element content of the magnetic iron oxide of 0.5 to 4% by weight based on the iron element, and the iron element dissolution rate of the magnetic iron oxide is 20% by weight. (B / A) × 100 of the content B of the silicon element existing up to the total content A of the silicon element in the magnetic iron oxide 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 1
0 to 55%, wherein the binder resin is a mixture of a vinyl polymer and a polyester resin. Hereinafter, the “present invention 1” means this magnetic toner.

The present invention also relates to a magnetic toner containing at least a binder resin and a magnetic iron oxide, wherein the magnetic toner has a weight average particle diameter of 13.5 μm or less, and the magnetic toner has a particle diameter distribution of less than 13.5 μm. The content of magnetic toner particles having a diameter of 12.7 μm or more 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. Wherein the iron content of the magnetic iron oxide is up to 20% by weight, and the content B of the silicon element 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 A of the silicon element existing on the surface of the magnetic iron oxide to the content A is 10%. To 55%, wherein the surface of the magnetic iron oxide is treated with silicone oil or silicone varnish. Hereinafter, the “present invention 2” means this magnetic toner.

Further, the present invention relates to a magnetic toner containing at least a binder resin and a magnetic iron oxide, wherein the magnetic toner has a weight average particle size of 13.5 μm or less, and the magnetic toner has a particle size distribution of not more than 13.5 μm. The content of magnetic toner particles having a diameter of 12.7 μm or more 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. Wherein the iron content of the magnetic iron oxide is up to 20% by weight, and the content B of the silicon element 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 A of the silicon element existing on the surface of the magnetic iron oxide to the content A is 10%. The binder resin is a copolymer obtained from at least a styrene-based monomer and an acrylic-based monomer;
F having an acid value of 1 to 70 in the insoluble matter and the soluble matter;
In the GPC chart, the molecular weight distribution of the HF soluble component is at least 1 in the range of 2,000 or more to less than 15,000.
With one peak and a molecular weight of 15,000 to 100,000.
A toner having at least one peak or shoulder at 0, a Tg of the toner of 45 to 65 ° C., and a THF insoluble content of 20 parts by weight or more based on 100 parts by weight of the resin component. . Hereinafter, "the present invention 3" means this magnetic toner.

Further, according to the present invention, the rotation speed of the outer diameter of the electrostatic image holder for holding the electrostatic image on the surface is 35 mm / sec.
In the image forming method, the electrostatic image on the electrostatic image holder is developed with a developer having toner, and the image is electrostatically transferred to a transfer material. Are contacted at a linear pressure of 10 g / cm or more, and the developer is a magnetic developer having a magnetic toner containing at least a binder resin and magnetic iron oxide, and an inorganic fine powder or a hydrophobic inorganic fine powder. The magnetic toner has a weight average particle diameter of 13.5 μm or less, and in the particle size distribution of the magnetic toner, the content of the magnetic toner particles having a particle diameter of 12.7 μm or more is 50% by weight or less, Iron is
The magnetic iron oxide has a silicon element content of 0.5 to 4% by weight based on the iron element, and the iron element dissolution rate of the magnetic iron oxide is up to 20% by weight.
And the ratio (B) of the total iron element content A of the magnetic iron oxide.
/ A) × 100 is 44 to 84%, and the ratio (C / A) × 100 between the content C of the silicon element existing on the surface of the magnetic iron oxide and the content A is 10 to 55%. And an image forming method characterized by the above. Hereinafter, “the present invention 4” means this image forming method.

The reason why the intended purpose can be achieved in the magnetic toner of the present invention is not necessarily clear, but is presumed as follows.

That is, in the magnetic toner of the present invention, the weight average particle diameter is 13.5 μm or less (preferably 3.3.5 μm).
5-13.5 μm), and in the particle size distribution of the magnetic toner, the magnetic toner having a content of magnetic toner particles having a particle diameter of 12.7 μm or more and 50% by weight or less is added to a specific magnetic iron oxide containing a silicon element. Is one of the features.

The weight average particle diameter of the magnetic toner is 13.5 μm.
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 has conventionally been generally used. 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 with the use of the special magnetic iron oxide of the present invention, and problems such as fogging due to poor charging and lightening of density 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, remarkable effects such as improvement of charge 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). １３13.5 μm, more preferably 5.0 to
13.0 μm) and the content of magnetic toner particles having a particle diameter of 12.7 μm or more is 50% by weight or less (more preferably 40% or less).

Further, in the present invention, the content of the silicon element of the magnetic iron oxide used in the magnetic toner is 0.5 to 4.0% by weight (more preferably 0.8 to 3.0) based on the iron element.
%, More preferably 0.9 to 3.0% by weight). When the content of silicon element is 0.
When the content is less than 5% by weight, the effect of improving the magnetic toner (particularly, the fluidity of the magnetic toner) is weak, and when the content of the silicon element is more than 4.0% by weight, the silicic acid component is magnetically oxidized. It is not preferable because it remains on the iron surface more than necessary or adversely affects the magnetic properties.

Further, in the present invention, the total content A of the silicon element present in the magnetic iron oxide used for the magnetic toner and the content B of the silicon element present when the dissolution rate of the iron element of the magnetic iron oxide is up to about 20%. B / A × 100 (%) is 44 to 8
4% (preferably 60-80%), the content C and the content A of the silicon element present on the surface of the magnetic iron oxide particles.
Is 100 to 55% (preferably 25 to 40%). B /
When A × 100 (%) is smaller than 44%, a large amount of silicon element more than necessary is present in the central portion of the magnetic iron oxide, and the production efficiency is easily deteriorated. May be iron oxide.

If 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 present in a large amount in a layered manner on the surface of the magnetic iron oxide. When present, the surface of the magnetic iron oxide becomes brittle against mechanical impact, and when used in a magnetic toner, many adverse effects are likely to occur.

On the other hand, when C / A × 100 (%) is smaller 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 are 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 (preferably -40 to -60 .mu.c).
c / g) and the magnetic iron oxide has a volume resistivity of 1
× 10 ⁴ to 1 × 10 ⁸ Ω · cm (preferably 5 × 10 ⁴ Ω · cm)
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 magnetic iron oxide has a volume resistivity of 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, when 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 and 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% (preferably 5 to 30%).

When the degree of agglomeration of the magnetic iron oxide is less than 3%, the blowing of the magnetic toner called "flushing" is apt to occur at the time of manufacturing the magnetic toner, and it is difficult to efficiently manufacture 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, fog and the like, and poor transfer such as "hollowness". Tends to occur.

Further, in the present invention, the magnetic iron oxide preferably has a smoothness D of 0.2 to 0.6 (preferably 0.3 to 0.5).

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 during the production of the magnetic toner, and are easily dispersed in the magnetic toner to adversely affect the toner characteristics.

On the other hand, when 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 gradually repetitive. 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 magnetic iron oxide
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 has an average particle size of 0.1 to 0.4 μm, preferably 0.1 to 0.4 μm.
It preferably has a thickness of about 0.3 μm.

Further, in the present invention 2, one of the features is that the surface of the magnetic iron oxide used for the magnetic toner is subjected to hydrophobic treatment with silicone oil or silicone varnish. By subjecting the magnetic iron oxide having silica near the surface to hydrophobic treatment, the moisture absorption resistance is improved, and the image density under high humidity is more stable.

The treatment amount of the silicone oil or silicone varnish is 0.05 to 100% by weight of the magnetic iron oxide.
It is preferably 5% by weight (more preferably 0.08 to 3% by weight). If the processing amount is less than 0.05% by weight, sufficient hydrophobic treatment cannot be performed, and the processing amount is 5% by weight.
If the ratio exceeds, the magnetic iron oxide aggregates, which causes a problem in use.

The method for measuring various physical property data in the present invention will be described in detail below. (1) Particle size distribution of toner The particle size distribution of toner can be measured by various methods.
In the present invention, this is performed 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 a number distribution and a 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, according to the present invention, the weight-based weight average diameter D ₄ obtained from the volume distribution (the median value of each channel is a representative value for each channel), and the weight-based 12.7 μm obtained from the volume distribution.
Find a weight distribution of m or more. (2) Content of Silicon Element 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.

Next, while maintaining the temperature at about 60 ° C. and the stirring speed at about 200 rpm, special grade sodium hydroxide is added to make a 1N sodium hydroxide solution, and the concentration of magnetic iron oxide is adjusted to about 5 g / l. The dissolution of a silicon compound such as silicic acid on the surface of the magnetic iron oxide particles is started. Thirty minutes after the start of dissolution, 20 ml is sampled, filtered through a 0.1 μm membrane filter, and the filtrate is collected. 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 /
1) corresponding to the silicon element concentration (mg / l).

In the present invention, the content of silicon element (based on iron element), the solubility of iron element and the contents A and B of 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 / l, and the aqueous hydrochloric acid solution is about 3N. Approximately 20 ml of the sample is sampled several times from the start of dissolution until it is completely dissolved and clear, filtered through a 0.1 μ membrane filter, and the filtrate is collected. The filtrate is subjected to quantitative determination of iron element and silicon element by plasma emission spectroscopy (ICP).

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

[0074]

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

[0075]

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

The silicon element content B of the magnetic iron oxide is defined as the silicon element concentration per unit weight (5 g / l of magnetic iron oxide) of the magnetic iron oxide to be detected when the solubility of the magnetic iron oxide is 20%. (Mg / l).

As a method for measuring the contents A, B and C, a sample of magnetic iron oxide was divided into two, and the content of silicon element and the contents A and B were measured. Separately measuring method, measuring the content C of the sample of magnetic iron oxide, using the sample after the measurement, 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), and finally calculating the contents A and B. (3) Charge of magnetic iron oxide About 2 g of magnetic iron oxide and carrier iron powder (TEFV200-3)
00mesh) (Nippon Iron Powder Co., Ltd.)
weighed into a ml polybin, shaken by hand for 10 seconds, shaken with a V-type blender for 20 minutes, and measured the charge of magnetic iron oxide using a blow-off powder charge meter (Toshiba Chemical Corporation) I do. 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. (4) Volume specific resistance of magnetic iron oxide 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 ohmmeter (YEW MODEL2506A manufactured by Yokogawa Electric Corporation).
DIGITAL MULTIMETOR), and apply a pressure of 150 Kg / cm ² again with a hydraulic cylinder. 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.

[0078]

(Equation 3) (5) Aggregation degree of magnetic iron oxide 10 g of magnetic iron oxide was pulverized with a mixer and 200 mesh
2 g of the sample passed through the sieve is weighed. 60mesh from above on powder tester (Hosokawa Micron Co., Ltd.)
Three screens are set in the order of 100 mesh and 200 mesh, and 2 g of the weighed sample is gently placed on the screen, and a vibration having an amplitude of 1 mm is applied for 65 seconds to measure the weight of the magnetic iron oxide remaining on each screen. Then, the degree of aggregation is calculated according to the following equation.

[0079]

(Equation 4) (6) Smoothness of Magnetic Iron Oxide In the present invention, the smoothness D of magnetic iron oxide is determined as follows.

[0080]

(Equation 5) (7) BET BET specific surface area of magnetic iron oxide is determined by a BET multipoint method using a fully automatic gas adsorption amount measuring apparatus: Autosorb 1, manufactured by Yuasa Ionics Co., Ltd., using nitrogen as the adsorbed gas. In addition, as pretreatment of a sample, degassing is performed at 50 ° C. for 1 hour. (8) Average particle size and surface area of magnetic iron oxide Using an electron microscope (H-700H, Hitachi, Ltd.), using a sample of magnetic iron oxide treated on a copper mesh of a collodion film, photographing at 10,000 × at an applied voltage of 100 KV. Then, the printing magnification is 3 times, and the final magnification is 30,000 times. With this, the shape is observed and the maximum length of each particle (μm)
Is measured, 100 pieces are randomly selected, and the average is defined as the average particle size.

For the calculation of the surface area, it is assumed that the magnetic iron oxide has a spherical shape with the average particle diameter being the diameter, and the density of the magnetic iron oxide is measured by an ordinary method to determine the value of the surface area. (9) Sphericity of Magnetic Iron Oxide The sphericity 磁性 of magnetic iron oxide in the present invention is calculated as follows.

[0082]

(Equation 6) The sphericity ψ 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 未 満 is less than 0.8, the dispersibility in the binder resin is inferior to the case where the silicon element is unevenly distributed on the surface of the magnetic iron oxide particles as compared with 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.

It is essential that the magnetic iron oxide used in the present invention 2 be treated with a silicone oil or a silicone varnish.
Those having a viscosity at 5 ° C. of about 30 to 1,000 centistokes are used. For example, dimethyl silicone oil, methyl hydrogen silicone oil, methyl phenyl silicone oil, α-methyl styrene modified silicone oil, chlorophenyl silicone oil, fluorine modified Silicone oil and the like are preferred.

The method for treating the silicone oil may be, for example, a method in which the magnetic iron oxide and the silicone oil are directly mixed using a mixer such as a Henschel mixer, or a method in which the silicone oil is sprayed onto silica as a base. Or after dissolving or dispersing the silicone oil in an appropriate solvent, mix with the base magnetic iron oxide,
It may be manufactured by removing the solvent.

The silicone varnish used in the present invention 2 can be a known substance. For example, KR-251 and KP-112 manufactured by Shin-Etsu Silicone Co., Ltd. may be mentioned, but not limited thereto.

As a method of the silicone varnish treatment, a known technique similar to the oil treatment can be used.

Examples of the binder resin of the toners according to the present inventions 2 and 4 include homopolymers of styrene such as polystyrene and polyvinyltoluene and substituted products thereof; styrene-propylene copolymer, styrene-vinyltoluene copolymer, and styrene. -Vinyl naphthalene 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-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, styrene- Dimethylaminoethyl methacrylate copolymer,
Styrene-vinyl methyl ether copolymer, styrene-
Styrenes such as vinyl ethyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-maleic acid copolymer, styrene-maleic acid ester copolymer Copolymer: polymethyl methacrylate, polybutyl methacrylate, polyvinyl acetate, polyethylene, polypropylene, polyvinyl butyral, silicone resin, polyester resin, polyamide resin, epoxy resin, polyacrylic resin, rosin, modified rosin, tempel resin, phenol resin , Aliphatic or alicyclic hydrocarbon resins, aromatic petroleum resins, paraffin wax, carnauba wax and the like 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.

Further, 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 an 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.

On the other hand, the present inventions 1 and 3 are also characterized by a binder resin.

The binder resin according to the present invention 1 is a mixture of a vinyl polymer and a polyester resin.

The vinyl copolymer has a glass transition point (T
g) is 45-65 ° C. (preferably 50-65 ° C.), and the molecular weight distribution of the tetrahydrofuran (THF) soluble component is determined by gel permeation chromatography (G
PC) Molecular weight of the chart 5,000 to 3,000,000
0 region, more preferably 10,000 to 2,000,
It is desirable to have a peak or shoulder at 000.

The polyester resin has a glass transition point (Tg) of 50 to 70 ° C., preferably 55 to 65 ° C., and a number average molecular weight Mn of 1,500 to 10,000, preferably 2,000 to 8,500. , The weight average molecular weight Mw is 4,
000 to 300,000, preferably 6,000 to 20
Desirably, it is 0000. The mixing ratio between the vinyl polymer and the polyester resin is preferably 9: 1 to 2: 8.

Here, the molecular weight of the peak or / and the shoulder of the chromatogram by GPC of the THF-soluble component is measured under the following conditions.

That is, the column is stabilized in a heat chamber at 40 ° C., THF as a solvent is flowed through the column at this temperature at a flow rate of 1 ml / min, and about 100 μl of a THF sample solution is injected to measure. In measuring the molecular weight of the sample, the molecular weight distribution of the sample was calculated from the relationship between the logarithmic value of a calibration curve prepared from several types of monodisperse polystyrene standard samples and the count number. As a standard polystyrene sample for preparing a calibration curve, for example, Pressu
re Chemical Co. It is appropriate to use those having a molecular weight of about 10 ² to 10 ⁸ manufactured by Toyo Soda Kogyo KK or Showa Denko KK and using at least about 10 standard polystyrene samples. The detector uses RI
A (refractive index) detector is used.

The column should be 10 ^{2 to} 3 × 10 ^7.
In order to measure the molecular weight region of polystyrene gel columns, it is preferable to combine a plurality of commercially available polystyrene gel columns. For example, Shodex GPC KF-801, 80 manufactured by Showa Denko KK
2, 803, 804, 805, 806, 800p, and Ultra Stylagel 5 manufactured by Water.
00A-THF, 10 ³ A-THF, 10 ⁴ A-TH
F, 10 ⁵ A-THF, 10 ⁶ A-THF or a combination of the A-Toluene series.

Further, in order to measure the molecular weight region of 10 ^{2 to} 2 × 10 ⁸ , Shodex GPCKF-801 and 80 were used.
2,803,804,805,806,800p.

Examples of the comonomer for obtaining the vinyl copolymer which is a part of the constituent components of the binder resin of the present invention include the following.

For example, styrene, o-methylstyrene, m
-Methylstyrene, p-methylstyrene, p-methoxystyrene, p-phenylstyrene, p-chlorostyrene, 3,4-dichlorostyrene, p-ethylstyrene,
2,4-dimethylstyrene, pn-butylstyrene,
Styrene such as p-tert-butylstyrene, pn-hexylstyrene, pn-octylstyrene, pn-nonylstyrene, pn-decylstyrene, pn-dodecylstyrene and derivatives thereof; ethylene, Ethylene unsaturated monoolefins such as propylene, butylene and isobutylene; unsaturated polyenes such as butadiene; vinyl halides such as vinyl chloride, vinylidene chloride, vinyl bromide, and vinyl fluoride; vinyl acetate, vinyl propionate, and benzoate Vinyl esters such as vinyl acrylate; methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate , METAK Le acid phenyl, dimethylaminoethyl methacrylate, alpha-methylene aliphatic monocarboxylic acid esters such as diethylaminoethyl methacrylate;
Methyl acrylate, ethyl acrylate, acrylic acid n-
Butyl, isobutyl acrylate, propyl acrylate,
Acrylic esters such as n-octyl acrylate, dodecyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, 2-chloroethyl acrylate and phenyl acrylate; vinyl ethers such as vinyl methyl ether, vinyl ethyl ether and vinyl isobutyl ether Vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone and methyl isopropenyl ketone; N-vinyl pyrrole, N-vinyl carbazole, N
N- such as vinylindole and N-vinylpyrrolidone
Vinyl compounds of vinyl compounds; vinyl naphthalenes; acrylic acid or methacrylic acid derivatives such as acrylonitrile, methacrylonitrile, and acrylamide; used alone or in combination of two or more.

The composition of the polyester resin used in the present invention 1 is as follows.

Examples of the dihydric alcohol component include ethylene glycol, propylene glycol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, diethylene glycol, triethylene glycol, and 1,5-pentanediol. , 1,6-hexanediol, neopentyl glycol, 2-ethyl-1,3-
Hexanediol, hydrogenated bisphenol A, or (i)
Bisphenol represented by the formula and derivatives thereof;

[0107]

Embedded image (Wherein R is an ethylene or propylene group, x and y are each an integer of 0 or more, and the average value of x + y is 0 to 10.) Also, diols represented by the formula (ii);

[0108]

Embedded image Is mentioned.

Examples of the divalent acid component include benzenedicarboxylic acids such as phthalic acid, terephthalic acid, isophthalic acid and phthalic anhydride or anhydrides thereof, and lower alkyl esters;
Alkyl dicarboxylic acids such as succinic acid, adipic acid, sebacic acid, azelaic acid or anhydrides thereof, lower alkyl esters; alkenyl succinic acids such as n-dodecenyl succinic acid, n-dodecyl succinic acid or alkyl succinic acids, and anhydrides of the acids And lower alkyl esters, unsaturated dicarboxylic acids such as fumaric acid, maleic acid, citraconic acid and itaconic acid or anhydrides thereof, dicarboxylic acids such as lower alkyl esters, and derivatives thereof.

Further, a trivalent or higher valent alcohol component and a trivalent or higher valent acid component serving as a crosslinking component can be used in combination.

The polyhydric alcohol component having a valency of 3 or more in the present invention includes sorbitol, 1,2,3,6-hexanetetrol, 1,4-sorbitan, pentaerythritol, dipentaerythritol, tripentaerythritol, , 2,4-butanetriol, 1,2,5-
Trivalent or higher polyvalent such as pentanetriol, glycerol, 2-methylpropanetriol, 2-methyl-1,2,4-butanetriol, trimethylolethane, trimethylolpropane, 1,3,5-trihydroxybenzene Alcohols.

The polyvalent carboxylic acid component having three or more valences in the present invention includes trimellitic acid, pyromellitic acid,
1,2,4-benzenetricarboxylic acid, 1,2,5-benzenetricarboxylic acid, 2,5,7-naphthalenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid,
1,2,4-butanetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,3-dicarboxyl-2-methyl-2-methylenecarboxypropane, tetra (methylenecarboxyl) methane, 1,2,7, 8-octanetetracarboxylic acid, embolic trimer acid, and anhydrides and lower alkyl esters thereof;

[0113]

Embedded image (Wherein X is an alkylene group or alkenylene group having 5 to 30 carbon atoms having one or more side chains having 3 or more carbon atoms), and polyvalent such as anhydrides and lower alkyl esters thereof. Examples include carboxylic acids and derivatives thereof.

On the other hand, the THF-insoluble content of the binder resin used in the toner of the present invention 3 is 20 parts by weight per 100 parts by weight of the binder resin.
By weight or more (preferably 25 to 70 parts by weight), and the molecular weight distribution of the THF-soluble component is preferably 2,000 or more to 15,000 in a GPC chromatogram.
Less than (more preferably, 3,000 to 12,000) a region having at least one peak and a molecular weight of 1
5,000-100,000 (more preferably, 20,
000-70,000) having at least one peak or shoulder.

More preferably, a peak in a region of a molecular weight of 2,000 or more to less than 15,000 and a peak having a molecular weight of 1
The peak or the gap with the shoulder in the region of 5,000 to 100,000 preferably has a difference of 5,000 or more in molecular weight, more preferably 10,000 or more in molecular weight.

The reason for this is that if the THF-insoluble content in the resin composition is 70 parts by weight or more, even if the modification of the THF-insoluble content is performed as in the case of the present invention 3, the fixing temperature may be lowered due to its melting property. As a result, the dispersion of the additive becomes worse. Further, the components of the highly crosslinked region are apt to be cut off during the kneading of the resin, which causes a hindrance to the design of the toner. When the THF-insoluble content is less than 20 parts by weight, offset tends to occur in a low-speed machine.
The blocking resistance at 0 ° C. is not sufficient.

The THF solvent soluble component has a molecular weight of 2,000.
If the peak value is 15,000 or more, the fixing temperature of the produced toner increases, the fixing temperature range becomes narrower, the pulverizability deteriorates, and the production efficiency decreases. Causes a decline. When the molecular weight of the peak value is 2,
If the molecular weight is less than 000, the produced toner may have remarkably poor offset resistance and may have a problem in blocking. The other peak or shoulder has a molecular weight of 15.0
It is not in the range of 100 to 100,000 and its value is 100,000
Exceeding the formula (1), the dispersibility of the additive is poor, the fixing temperature is significantly increased, and the pulverizability is also significantly deteriorated. If the molecular weight of the peak or shoulder is less than 15,000, the produced toner will have poor offset resistance and may cause a problem in blocking.

Further, the weight ratio of the low molecular weight polymer to the high molecular weight polymer is 5:95 to 70:30, preferably 10: 9.
It may be present at 0 to 50:50.

If the ratio of the low-molecular-weight polymer is less than 5, the pulverizability is poor and a bad powder is generated.
If it exceeds 70, the offset resistance and the blocking resistance are insufficient.

The Tg of the toner of the present invention 3 is in the range of 45 to 65 ° C., and the total content of the styrene monomer (Ms) and the total content of the acrylic monomer (Ma) in the THF-insoluble matter of the binder resin. Is preferably 1.0 ≦ (Ms / Ma) <2.5. When Ms / Ma <1.0, the blocking resistance at 50 ° C. is deteriorated even if the amount of the THF-insoluble component is increased. When Ms / Ma ≧ 2.5, the low-temperature fixability is not sufficient. More preferably, 1.0 <(Ms / M
a) <2.0 is good.

Further, the ratio (Ms ₂ / Ma ₂ ) between the total content of styrene-based monomer (Ms ₂ ) and the total content of acrylic-based monomer (Ma ₂ ) in the THF-soluble matter is (Ms ₂ / Ma ₂ ).
/ Ma)> (Ms ₂ / Ma ₂ ). When (Ms / Ma) ≦ (Ms ₂ / Ma ₂ ), the blocking resistance at 50 ° C. is insufficient even if the amount of the THF-insoluble component is increased within the range of (Ms / Ma).

Here, the THF-insoluble matter is defined by a value measured as follows.

That is, when the sample is only resin, 0.5
１．０1.0 g of a certain amount of resin is weighed (W ₁ g), placed in a cylindrical filter paper (No. 86R manufactured by Toyo Roshi Kaisha), subjected to a Soxhlet extractor, and extracted with 100 to 200 ml of THF as a solvent for 6 hours. After evaporating the soluble component extracted by the solvent, vacuum drying is performed at 100 ° C. for several hours, the amount of the soluble resin component is weighed (W ₂ g), and calculated according to the following equation.

THF-insoluble content = (W ₁ −W ₂ ) / W ₁ × 100 (%) When the sample is a toner, a series of extraction operations is the same as that for a resin, but for a non-magnetic toner, a sample toner is used. From the weight, the weight of the pigment is subtracted from the weight of the toner, the weight (W ₃ g) of the weight of the sample toner minus the weight of the pigment and the magnetic material, and the weight of the solvent-soluble component in the toner (W ₄ g). Can be calculated.

THF-insoluble content = (W ₃ −W ₄ ) / W ₃ × 100 (%) The solvent-soluble component obtained by the above operation was evaporated to dryness using TH.
After dissolving in F and passing through a sample processing filter, it is used as a GPC sample.

In the present invention 3, the molecular weight of the peak or / and the shoulder of the chromatograph by GPC is measured under the following conditions.

That is, the column was stabilized in a heat chamber at 40 ° C., and THF was passed through the column at this temperature at a flow rate of 1 ml per minute to adjust the sample concentration to 0.05 to 0.1% by weight. 50 to 200 μl of a THF sample solution of the obtained resin is injected and measured. In measuring the molecular weight of the sample, the molecular weight distribution of the sample was calculated from the relationship between the logarithmic value of a calibration curve prepared from several types of monodisperse polystyrene standard samples and the count number. As a standard polystyrene sample for preparing a calibration curve, for example, a molecular weight of 6 × 10 ² , 2.1 × 10 ³ , 4 × 10 ³ , 1.75 × manufactured by Pressure Chemical Co. or Toyo Soda Kogyo Co., Ltd.
10 ⁴ , 5.1 × 10 ⁴ , 1.1 × 10 ⁵ , 3.9 × 1
0 ⁵ , 8.6 × 10 ⁵ , 2 × 10 ⁶ , 4.48 × 10 ⁶
It is appropriate to use at least about 10 standard polystyrene samples. An RI (refractive index) detector is used as the detector.

The column used is 10 ³ to 2 × 10
⁶ molecular weight region of to measure the accurately, good combination of several commercially available polystyrene gel column, e.g., Waters (Waters) manufactured by μ- Suchirageru ^{(styragel) 500,10 3, 10 4} , 10
⁵ combinations and Showdex (S
handex) KF-80M, KF-802, 803,
804, 805, KA-802, 803,
804, 805 combination or TS made by Toyo Soda
KgelG1000H, G2000H, G2500H,
G3000H, G4000H, G5000H, G600
A combination of 0H, G7000H, and GMH is desirable.

The binder resin of the present invention 3 contains a THF-insoluble content and / or
Alternatively, it is preferable that the THF-soluble component has an acid value of 1 to 70 in order to further improve the blocking resistance and the offset resistance.

Examples of the polymerizable monomer containing an acid group that can be used in the present invention 3 include the following.

Α, β such as acrylic acid and methacrylic acid
Unsaturated carboxylic acids; α, β-unsaturated dicarboxylic acids such as maleic acid, butyl maleate, octyl maleate, fumaric acid, butyl fumarate or half esters thereof; n-butenyl succinic acid, n-octenyl succinic acid; Alkenyl dicarboxylic acids such as n-butyl succinate, n-butenyl malonic acid, n-butenyl adipic acid and the like, and half esters thereof and the like can be mentioned. Preferably, dicarboxylic acids which can be dehydrated and derivatives thereof are good.

In this case, the amount of the polymerizable monomer containing an acid group is preferably 1 to 30 parts by weight based on the total amount of the binder resin.
The acid value of the entire binder resin is preferably 1 to 70, more preferably 5 to 50.

The reason why the above-mentioned dicarboxylic acid half-ester monomer is selected will be described later in detail, but it is because a suspension polymerization method is preferred as a resin production method. This is because, in the suspension polymerization, it is not appropriate to use an acid monomer having a high solubility in an aqueous suspension, and it is preferable to use an ester having a low solubility in an ester. The carboxylic acid monomer in the present invention 3 is not included in any of the styrene monomer and the acrylic monomer, and is excluded from the calculation of the weight ratio of the styrene monomer to the acrylic monomer.

Examples of the styrenic monomer constituting the binder resin of the present invention 3 include styrene, o-methylstyrene and m-styrene.
-Methylstyrene, p-methylstyrene, p-methoxystyrene, p-phenylstyrene, p-chlorostyrene, 3,4-dichlorostyrene, p-ethylstyrene,
2,4-dimethylstyrene, pn-butylstyrene,
There are styrene such as p-tert-butylstyrene, pn-hexylstyrene, pn-octylstyrene, pn-nonylstyrene, pn-decylstyrene, pn-dodecylstyrene and derivatives thereof, As acrylic monomers, methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate,
Isobutyl methacrylate, n-octyl methacrylate,
Α-methylene aliphatic monocarboxylic esters such as dodecyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, phenyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate; methyl acrylate, ethyl acrylate, N-butyl acrylate, isobutyl acrylate,
Acrylic esters such as propyl acrylate, n-octyl acrylate, dodecyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, 2-chloroethyl acrylate, and phenyl acrylate are used.

In addition, ethylene unsaturated monoolefins such as ethylene, propylene, butylene, and isobutylene; unsaturated polyenes such as butadiene; vinyl chloride, vinylidene chloride, vinyl bromide, Vinyl halides such as vinyl fluoride; vinyl esters such as vinyl acetate, vinyl propionate and vinyl benzoate; vinyl methyl ether;
Vinyl ethers such as vinyl ethyl ether and vinyl isobutyl ether; vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone and methyl isopropenyl ketone; N-vinyl pyrrole, N-vinyl carbazole, N-vinyl indole, N-vinyl pyrrolidone and the like Monomers such as N-vinyl compounds; vinyl naphthalenes; acrylic acid or methacrylic acid derivatives such as acrylonitrile, methacrylonitrile, and acrylamide;

The binder resin used in the present invention 3 comprises:
In order to achieve the object of the present invention, it is necessary that the polymer is crosslinked with a crosslinkable monomer as exemplified below.

Aromatic divinyl compounds such as divinylbenzene and divinylnaphthalene; diacrylate compounds linked by an alkyl chain such as ethylene glycol diacrylate, 1,3-butylene glycol diacrylate and 1,4-butanediol Diacrylate,
1,5-pentanediol diacrylate, 1,6-hexanediol diacrylate, neopentyl glycol diacrylate, and acrylates of the above compounds replaced with methacrylates; diacrylates linked by an alkyl chain containing an ether bond Compounds, for example,
Diethylene glycol diacrylate, triethylene glycol diacrylate, tetraethylene glycol diacrylate, polyethylene glycol # 400 diacrylate, polyethylene glycol # 600 diacrylate, dipropylene glycol diacrylate, and those obtained by replacing the acrylate of the above compound with methacrylate; Diacrylate compounds linked by a chain containing an aromatic group and an ether bond, for example, polyoxyethylene (2) -2,2-bis (4-hydroxyphenyl) propane diacrylate, polyoxyethylene (4) -2 ,
2-bis (4-hydroxyphenyl) propane diacrylate and those obtained by replacing acrylates of the above compounds with methacrylates; further, polyester-type diacrylate compounds, for example, trade name MANDA (Nippon Kayaku) Can be Examples of polyfunctional crosslinking agents include pentaerythritol triacrylate, trimethylolethane triacrylate, trimethylolpropane triacrylate, tetramethylol methanetetraacrylate,
Oligoester acrylates and those obtained by replacing the acrylates of the above compounds with methacrylates; triallyl cyanurate, triallyl trimellitate; and the like.

[0138] These crosslinking agents are used in combination with other monomer components 10
It is preferable to use about 0.01 to 5% by weight (more preferably about 0.03 to 3% by weight) with respect to 0% by weight.

Among these crosslinkable monomers, those which are preferably used in the resin for toner from the viewpoint of fixability and anti-offset property include an aromatic divinyl compound (particularly divinylbenzene), an aromatic group and an ether bond. And diacrylate compounds linked by a chain.

The method for synthesizing the binder resin according to the present invention 3 is basically a method for synthesizing two or more polymers by controlling the weight ratio of the styrene monomer to the acrylic monomer in the THF-insoluble and soluble components. Can.

That is, a low molecular weight polymer having a small amount of THF-insoluble and soluble in a polymerizable monomer is dissolved in the polymerizable monomer,
In this method, a monomer is polymerized to obtain a resin composition. In this case, a composition is formed in which the former and the latter polymers are uniformly mixed.

The low molecular weight polymer in the binder resin composition used in the present invention 3 can be obtained by a commonly used polymerization method such as a bulk polymerization method and a solution polymerization method.

In the bulk polymerization method, a polymer having a low molecular weight can be obtained by increasing the termination reaction rate by polymerizing at a high temperature, but there is a problem that the reaction is difficult to control.
In this regard, in the solution polymerization method, a low molecular weight polymer can be easily obtained under mild conditions by utilizing the difference in radical chain transfer depending on the solvent, and by adjusting the amount of the initiator and the reaction temperature. It is preferable to obtain a low-molecular-weight compound in the resin composition used in 3.

As a solvent used in the solution polymerization, xylene, toluene, cumene, cellosolve acetate, isopropyl alcohol, benzene and the like are used. In the case of a styrene monomer, xylene, toluene or cumene is preferred.
It is appropriately selected depending on the polymer to be polymerized. The initiator is di-tert-butyl peroxide, tert-
Butylperoxybenzoate, benzoyl peroxide, 2,2′-azobisisobutyronitrile, 2,
2'-Azobis (2,4 dimethylvaleronitrile) or the like is used at a concentration of 0.1 part by weight or more (preferably 0.4 to 15 parts by weight) based on 100 parts by weight of the monomer. The reaction temperature varies depending on the solvent used, the initiator, and the polymer to be polymerized, but is preferably from 70 ° C to 180 ° C. In the solution polymerization, it is preferable to carry out the polymerization with 30 parts by weight to 400 parts by weight of the monomer per 100 parts by weight of the solvent.

This low molecular weight polymer is polymerized again together with the monomer giving the high molecular weight polymer. However, as a polymerization method for obtaining a gel component in a crosslinked region until it becomes an insoluble component in a solvent, an emulsion polymerization method and a polymerization method are available. The suspension polymerization method is preferred.

Among them, the emulsion polymerization method is a method in which a monomer (monomer) almost insoluble in water is dispersed in an aqueous phase as small particles with an emulsifier, and polymerization is carried out using a water-soluble polymerization initiator. . In this method, it is easy to control the heat of reaction, and since the phase in which the polymerization is carried out (the oil phase composed of the polymer and the monomer) and the aqueous phase are different, the termination reaction rate is small, and as a result, the polymerization rate is large. , With a high degree of polymerization.
Furthermore, the polymerization process is relatively simple, and the polymerization product is fine particles, so that it is easy to mix with a colorant, a charge control agent, and other additives in the production of a toner. Therefore, there is an advantage in a method for producing a binder resin for a toner.

However, the resulting polymer tends to be impure due to the added emulsifier, and an operation such as salting out is required to remove the polymer. To avoid this inconvenience, suspension polymerization is advantageous.

On the other hand, in the suspension polymerization method, a monomer containing a low-molecular-weight polymer in a suspension state is polymerized together with a crosslinking agent, so that the resin composition has a pearl-like shape and has a low-molecular-weight polymer. From the coalescing to the inclusion of the cross-linking zone component, the high molecular weight polymer can be obtained in a uniformly mixed and preferable state.

In the suspension polymerization, 100 parts by weight or less of the monomer (preferably 1 part by weight) is added to 100 parts by weight of the aqueous solvent.
(0 to 90 parts by weight). Examples of usable dispersants include polyvinyl alcohol, partially saponified polyvinyl alcohol, calcium phosphate, and the like. There is an appropriate amount in terms of the amount of a monomer relative to an aqueous solvent, and generally 0.05 to 1 based on 100 parts by weight of an aqueous solvent. Used in parts by weight. The polymerization temperature is suitably from 50 to 95 ° C, but should be appropriately selected depending on the initiator used and the intended polymer. As the kind of the initiator, any one can be used as long as it is insoluble or hardly soluble in water. For example, benzoyl peroxide, tert-butyl peroxyhexanoate and the like are used in an amount of 0 to 100 parts by weight of the monomer. 0.5-1
Used at 0 parts by weight.

The method described above is the method for producing the binder resin used in the present invention 3, but without using the above polymerization method, the three kinds of resins constituting the binder resin are mixed at the time of melt kneading or the like. Think about the case. The problem at this time is the dispersion of each component in the binder resin. If it is within the range of the predetermined compounding ratio, it does not greatly affect the dispersibility or the molecular weight distribution of the entire binder resin,
Increasing the amount of the vinyl copolymer (A) for improving the pulverizability, and increasing the amount of the vinyl copolymer (B) for improving the offset resistance
When the predetermined mixing ratio is changed, for example, the amount of the THF-insoluble component is increased or the amount of the polyester resin is increased for improving the fixing property, poor dispersion is likely to occur.

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.

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

The silica fine powder used in the present invention includes 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. Although it can be used, fumed silica having few silanol groups on the surface and inside and having no production residue is preferable.

Further, 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 and an organic silicon compound such as silicone oil. Is mentioned.

Examples of the silane coupling agent used in the hydrophobizing treatment include hexamethyldisilazane, trimethylsilane, trimethylchlorosilane, trimethylethoxysilane, dimethyldichlorosilane, methyltrichlorosilane, allyldimethylchlorosilane, allylphenyl Dichlorosilane, benzyldimethylchlorosilane, bromomethyldimethylchlorosilane, α-chloroethyltrichlorosilane, β-chloroethyltrichlorosilane,
Chloromethyldimethylchlorosilane, triorganosilane mercaptan, trimethylsilyl mercaptan, triorganosilyl acrylate, vinyldimethylacetoxysilane, dimethylethoxysilane, dimethyldimethoxysilane, diphenyldiethoxysilane, hexamethyldisiloxane, 1,3-divinyltetramethyldi Siloxane and 1,3-diphenyltetramethyldisiloxane.

Examples of the organosilicon compound include silicone oil. Preferred silicone oils are those having a viscosity of about 30 to 1,000 centistokes at 25 ° C., such as dimethyl silicone oil, methylphenyl silicone oil, α-methylstyrene-modified silicone oil, chlorophenyl silicone oil, and fluorine-modified silicone oil. Silicone oil and the like are preferred.

The silicone oil treatment method may be, for example, the silica fine powder treated with a silane coupling agent and the silicone oil may be directly mixed using a mixer such as a Henschel mixer, or the silicone oil may be added to the base silica. May be injected. Alternatively, it may be prepared by dissolving or dispersing a silicone oil in an appropriate solvent, mixing with a base silica fine powder, and removing the solvent.

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

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

The inorganic fine powder or the hydrophobic inorganic fine powder mixed with the magnetic toner is used in an amount of 0.1 to 5 parts by weight (preferably 0.1 to 3 parts by weight) based on 100 parts by weight of the magnetic toner. good.

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 adding a predetermined amount of a silicate compound 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 silicic acid compound used for 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 which is generally produced as a by-product in the production of titanium sulfate, iron sulfate which is produced as a result of cleaning the surface of a steel sheet, and iron chloride and the like can be used. is there.

The method for producing magnetic iron oxide by the aqueous solution method generally uses an iron concentration of 0.5 to 2 mol / l from the viewpoint of preventing the viscosity from increasing 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, the 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 microscopy. Produces magnetic iron oxide containing almost no face particles,
It is preferable to use the magnetic iron oxide in the toner.

The image forming apparatus, apparatus unit and facsimile apparatus for using the magnetic toner 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) on the surface of the photosensitive drum. 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.

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

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

The image forming apparatus shown in FIG. 4 differs from the image forming apparatus shown in FIG. 3 in that the thickness of the magnetic developer on the developing sleeve 6 is regulated by the magnetic doctor blade 16. 4, members having the same reference numerals as those in FIG. 3 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 spacing of 5).
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.

An electrophotographic apparatus is constructed by integrally combining 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 as an apparatus 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. 5 shows an embodiment of the apparatus unit of the present invention. In the present embodiment, an electrophotographic system including an image forming unit (a so-called cartridge) 18 integrally including a developing device 1, a drum-shaped latent image carrier (photosensitive drum) 3, a cleaner 14, and a primary charger 11 is provided. An image forming apparatus is exemplified.

In the present apparatus, the image forming unit 1
When the magnetic developer 13 in the developing device 1 in the cartridge 8 runs out, the cartridge is replaced with a new cartridge.

In this embodiment, the developing device 1 uses a one-component magnetic developer as the developer 13, and a predetermined electric field is formed between the photosensitive drum 3 and the developing sleeve 6 at the time of development. 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 of the present invention shown in FIG. 5 includes a developer container 2 for containing a magnetic developer 13 and a developer container 2.
A developing sleeve 6 for carrying and transporting the magnetic developer 13 therein from the developer container 2 to a developing area facing the latent image carrier 3;
An elastic blade 9 is provided to regulate the magnetic developer carried by the developing sleeve 6 and conveyed to the developing area to a predetermined thickness and to form a thin developer layer on the developing sleeve.

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-like shape that circulates. 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 stainless steel; 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 image forming apparatus of the present invention is used as a facsimile printer, the light image exposure is exposure for printing received data. FIG. 6 is a block diagram showing an example of this case.

A 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. 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.

The contact pressure between the electrostatic image holder according to the fourth embodiment and the transfer means is preferably 10 g / cm or more as a linear pressure. The linear pressure is calculated by the following equation.

(Linear pressure) [g / cm] = (total pressure applied to the transfer member) [g] / (contact length) [cm] The rotation speed of the outer diameter of the latent image carrier is 35 mm. If the contact pressure is less than 10 g / cm in the image forming method of / sec or more, transfer failure of the transfer member and insufficient transfer due to insufficient transfer current undesirably occur. Particularly preferably, it is 20 g / cm or more.

The transfer device used in the present invention 4 includes:
A transfer roller as shown in FIG. 9 or a transfer belt as shown in FIG. FIG. 9 is a schematic view of a main part of a typical image forming apparatus of this type. The illustrated apparatus includes a cylindrical image carrier (hereinafter referred to as a photoconductor) that extends in a direction perpendicular to the plane of the paper and rotates in the direction of arrow A. 21), and a conductive transfer roller 22 in contact with it.

A primary charger for uniformly charging the surface of the photoreceptor 21 and a light image such as a laser beam image-modulated and a reflected light from a document are projected on the charged surface. And an exposure section for attenuating the potential of the portion to form an electrostatic latent image, a developing device, a cleaner for removing residual toner remaining on the surface of the photoreceptor even after transfer, and other members required for image formation. Needless to say, they are all omitted.

The transfer roller 22 includes a core metal 22a and a conductive elastic layer 22b. The conductive elastic layer 22b has a volume resistance of about 10 ⁶ to 10 ¹⁰ Ω · cm such as urethane or EPDM in which a conductive material such as carbon is dispersed. It is made of elastic material. A bias is applied to the metal core 22a by a constant voltage power supply 28.

FIG. 10 shows a case where the present invention 4 is applied to a transfer belt. The transfer belt 29 is supported and driven by the conductive roller 30. The pressure on the transfer roller is usually
This is performed by pressing the end bearing 2a.

The present invention is particularly effective for an image forming apparatus in which the surface of a latent image carrier is an organic compound.

When an organic compound forms a surface layer,
This is because the adhesive property with the binder resin contained in the toner is good, and particularly when a material of the same quality is used, a chemical bond occurs at the contact point, and the transferability is reduced.

Examples of the surface material of the latent image carrier used in the present invention include, but are not limited to, silicone resin, vinylidene chloride, ethylene-vinyl chloride, styrene-acrylonitrile, styrene-methyl methacrylate, styrene, polyethylene terephthalate, and polycarbonate. However, other monomers or copolymerization or blending between the exemplified resins can also be used.

In the present invention, the diameter of the latent image carrier 21 is 50 m.
This is particularly effective for an image forming apparatus of m or less.

In the case of a small-diameter drum, even if the linear pressure is the same, the curvature is large, so that the pressure tends to concentrate at the contact portion. It is considered that the same phenomenon occurs in the belt photoreceptor, and the present invention is also effective for an image forming apparatus having a radius of curvature of 25 mm or less at the transfer section.

The magnetic developer used in the fourth aspect of the present invention having the above characteristics has a rotation speed of the outer diameter of the latent image carrier of 35 mm.
/ Sec or more, and even in an image forming method using the contact transfer method, there is no transfer failure such as “missing during transfer”, and an image having high image density and excellent reproducibility is provided.

Even when copying or printing out is continued for a long time, it is possible to keep high image quality without "missing during transfer" and "fog".

[0206]

The present invention will be described below in more detail with reference to examples. Parts or% described in Examples are parts by weight or% by weight.

First, a production example of the magnetic iron oxide used in each embodiment will be described. Among them, Production Examples 5 to 8 are used in Examples 5 to 8 according to the present invention 2.

(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%. 0 to
An aqueous solution containing ferrous hydroxide was prepared by mixing 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 relative 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 produced magnetic iron oxide particles were washed, filtered, and dried by a conventional method, and then the aggregated particles were crushed to obtain magnetic iron oxide having the properties shown in Table 2.

Table 1 shows data obtained by measuring the dissolution amounts of the iron element and the silicon element every 10 minutes. 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 / l, and the surface layer B of the magnetic iron oxide particles shown in FIG. Is 38.8 mg / l, and content A is 58.8 mg / l.
It was 9.7 mg / l.

[0213]

[Table 1] (Production Example 2) The properties shown in Table 2 were obtained in the same manner as in Production Example 1 except that sodium silicate was added so that the content ratio of silicon to iron was 2.9%. Magnetic iron oxide was obtained.

(Production Example 3) Table 2 was produced in the same manner as in Production Example 1 except that sodium silicate was added so that the content ratio of silicon element to iron element was 0.9%. A magnetic iron oxide having excellent characteristics was obtained.

(Production Example 4) Table 2 was produced in the same manner as in Production Example 1 except that sodium silicate was added so that the content ratio of silicon element to iron element was 1.7%. A magnetic iron oxide having excellent characteristics was obtained.

(Comparative Production Example 1) A 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 not added.

(Comparative Production Example 2) To 100 parts of the magnetic iron oxide obtained in Comparative Production Example 1, 1.5 parts of silicic acid fine powder was mixed with a Henschel mixer and had the characteristics shown in Table 2. A magnetic iron oxide was obtained.

[0218]

[Table 2] (Production Examples 5 to 8 and Comparative Production Examples 3 to 4) Silicone oil was further diluted with methyl alcohol and gently mixed with a Henschel mixer with respect to the magnetic iron oxide having the characteristics shown in Table 2 above. It was volatilized to obtain a magnetic iron oxide subjected to a hydrophobic treatment shown in Table 3.

[0219]

[Table 3] Examples 1 to 4 are specific examples according to the present invention 1.

Example 1-60 parts of styrene-n-butyl maleate-divinylbenzene copolymer (Tg 58 ° C, peak 200,000)-Obtained from bisphenol A, terephthalic acid, 40 parts of n-dodecenyl succinic acid and triethylene glycol Polyester resin (Tg 56 ° C, Mn 4,000, Mw 35,000)-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 3 parts of the above mixture The mixture was melt-kneaded with a twin-screw extruder heated to 140 ° C, the cooled kneaded material was coarsely pulverized by a hammer mill, the coarsely pulverized material was finely pulverized by a jet mill, and the obtained finely pulverized powder was fixed-wall type air classification Classifying by a machine produced 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 simultaneously strictly classified and removed to obtain a negatively chargeable magnetic toner having a weight average particle size (D4) of 6.8 μm (content of magnetic toner particles having a particle size of 12.7 μm of 0.2%). Was.

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

Commercially available laser beam printer LBP-
An apparatus unit portion (toner cartridge) of 8II (manufactured by Canon Inc.) was modified as shown in FIG. 3, and an elastic blade made of urethane rubber was brought into contact with an aluminum developing sleeve at a contact pressure of 30 g / cm.

Using the above magnetic developer, the primary charge was
At 0 V, an electrostatic latent image for reversal development is formed on the OPC photosensitive drum 3, 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 heating and pressing roller fixing device.

An image output test was performed on up to 6,000 sheets in 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 dot reproducibility obtained by performing a 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 Styrene-2-ethylhexyl acrylate-20 parts n-butyl acrylate-divinylbenzene copolymer (Tg 65 ° C., peak 1,900,000) Bisphenol A, terephthalic acid, trimellitic acid and 80 parts Polyester resin obtained from triethylene glycol (Tg 54 ° C, Mn2,100, Mw 7,000)-60 parts of magnetic iron oxide of Production Example 2-0.8 part of negative charge control agent (monoazo dye-based chromium complex) 0.8 parts-Low 3 parts of molecular weight polypropylene The mixture was melt-kneaded with a biaxial extruder heated to 140 ° C, and the cooled kneaded material was coarsely pulverized by a hammer mill, and the coarsely pulverized product was finely pulverized by a jet mill. The obtained finely pulverized powder was subjected to air classification to obtain a weight average particle diameter (D ₄ ) of 11 μm.
m (content of magnetic toner particles having a particle diameter of 12.7 μm or more 3
3%) was obtained.

A magnetic developer was prepared by mixing 100 parts of the obtained magnetic toner and 0.6 parts of hydrophobic colloidal silica treated with dimethyl silicone oil using a Henschel mixer.

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

Example 3 80 parts of styrene-n-butyl acrylate copolymer (Tg 53 ° C., peak 8,000) Polyester resin obtained from bisphenol A, 20 parts of terephthalic acid, 20 parts of n-dodecenylsuccinic acid and triethylene glycol (Tg 62 ° C, Mn 7,300, Mw 220,000) ・ 120 parts of magnetic iron oxide of Production Example 3 ・ 2 parts of negative charge control agent (monoazo dye-based chromium complex) ・ 3 parts of low molecular weight polypropylene Examples using the above materials In the same manner as in Example 1, a magnetic toner having a weight average particle diameter (D ₄ ) of 4 μm (content of magnetic toner particles having a particle diameter of 12.7 μm or more 0%) was obtained.

A magnetic developer was prepared by mixing 100 parts of the obtained magnetic toner and 1.6 parts of hydrophobic colloidal silica treated with silicone oil using a Henschel mixer.

Using this magnetic developer, a multi-image printing test was performed in the same manner as in Example 1. Table 4 shows the results.

Example 4 60 parts of styrene-2-ethylhexyl acrylate copolymer (Tg 63 ° C., peak 60,000) 40 parts of bisphenol A, terephthalic acid, n-dodecenyl succinic acid Polyester obtained from trimellitic acid and triethylene glycol Resin (Tg 56 ° C, Mn 6,000, Mw 60,000) 90 parts of magnetic iron oxide of Production Example 4 1 part of negative charge control agent (dialkylsalicylic acid chromium complex) 1 part of low molecular weight polypropylene 3 parts In the same manner as in Example 1, a magnetic toner having a weight average particle size (D ₄ ) of 8.5 μm (content of magnetic toner particles having a particle size of 12.7 μm or more 4%) was obtained.

A magnetic developer was prepared by mixing 100 parts of the obtained magnetic toner and 1 part of hydrophobic colloidal silica fine powder treated with hexamethyldisilazane and then treated with silicone oil using a Henschel mixer.

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

Comparative Example 1 A weight average particle diameter of 7 μm (particle diameter of 12.7) 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 0.3 μm or more (0.3%) was obtained. Using the obtained magnetic toner, 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 using the prepared magnetic developer. Table 4 shows the results.

Comparative Example 2 A weight average particle size of 8.7 μm (particle size of 1) was obtained in the same manner as in Example 4 except that the magnetic iron oxide of Comparative Production Example 2 was used.
A magnetic toner having a content of magnetic toner particles of 2.7 μm or more (5%) was obtained. Example 4 was prepared using the obtained magnetic toner.
In the same manner as in Example 4, a magnetic developer was prepared, and an image-drawing test was performed in the same manner as in Example 4 using the prepared magnetic developer. Table 4 shows the results.

[0237]

[Table 4] (A) Fog was calculated by the following equation.

Fog (%) = whiteness of transfer paper after solid white printing−whiteness of transfer paper If fog is 1.5% or less, a good image is obtained. (B) For the dot reproducibility, an image output test was performed using an 80 × 50 μm checker pattern shown in FIG. 7, and sharpness of the toner image was observed with a microscope, the toner was stuck to the non-image area, and the black area was defective Was evaluated. (C) Fixing property: The evaluation machine was left overnight in a low-temperature environment (10 ° C.), and after the evaluation machine and the fixing device inside the evaluation machine were completely adjusted to the environment, the power was turned on and 200 immediately after the weight-up.
Horizontal line pattern of μm width (line width 200μm, interval 200μ)
m) was printed out and the first printed image was used for evaluation of fixability. The evaluation of fixability was performed using an image of 5
Rubbing was performed with a reciprocating load of 100 g, and the peeling of the image was evaluated based on the reduction rate (%) of the reflection density. (D) The offset resistance is 100 using a new fixing pad.
After printing 300 sheets of a horizontal line pattern having a width of μm, the printing was paused for 30 seconds after continuous printing, and printing was started.

The evaluation criteria are shown below. 1) Dot reproducibility: 2 defects or less / 100 defects △: 3 to 5 defects / 100 defects…: 6 to 10 defects / 100 defects ×… 11 to 20 defects / 100 defects ××: 21 defects 2 or more / 100 pieces 2) Fixing property…: Average density reduction rate: 0 to 5% △: Average density reduction rate: 5 to 8% ×: Average density reduction rate: 10% or more 3) Offset resistance (back stain after rest) … No staining ○ △… Somewhat unclear △… Dirty but practically practical ×… Dirt is noticeable and impractical 4) Blocking resistance (50 ° C for 3 days) ○… No change ○ △… Agglomerates are observed but lightly shakeと: Aggregates are observed but loosen when pressed lightly. ×: Aggregates are observed and are difficult to unravel. X 凝集 Aggregates are observed and are not loose. Examples 5 to 8 are specific examples according to the second aspect of the present invention.

Example 5 Styrene-2-ethylhexyl acrylate-100 parts n-butyl maleate half ester copolymer (copolymerization weight ratio 7.5: 1.5: 1, Mw 250,000) Iron oxide 100 parts ・ Negative charge control agent (dialkylsalicylic acid chromium complex) 1 part ・ Low molecular weight polypropylene 3 parts The above mixture is melt-kneaded with a biaxial extruder heated to 140 ° C., and the cooled kneaded material is hammer milled. And coarsely pulverized material 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. Furthermore, resulting classified powder with a multi-division classifier utilizing the Coanda effect ultrafine and simultaneously strictly classified removed to a weight average particle diameter coarse (D ₄₎ 6.7μm (particle size 12.7
A negatively chargeable magnetic toner having a magnetic toner particle content of 0.2 μm) was obtained.

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

A magnetic toner image was fixed using the image forming apparatus shown in FIG. 3 under the same charging and developing conditions as in Example 1.

An intermittent image output test was conducted in which one A4 sheet was output in 30 seconds over a period of several days under normal temperature and normal humidity (23.5 ° C., 60% RH) while replenishing the magnetic developer. Table 5 shows the results of fog and dot reproducibility obtained in the same manner as in Example 1.

Similarly, in a high temperature and high humidity environment (32.5
℃, 90% RH) and low temperature and low humidity environment (10 ℃, 15%
RH), an intermittent image output test was performed in which one A4 sheet was output in 30 seconds over several days. Table 5 shows the results.

Example 6 100 parts of styrene-n-butyl acrylate copolymer (copolymerization weight ratio 8: 2, Mw 280,000) 60 parts of magnetic iron oxide of Production Example 6 Negative charge control agent (monoazo dye-based 0.8 part ・ Low molecular weight polypropylene 3 parts And pulverized. 10. The obtained finely pulverized powder was subjected to air classification to obtain a weight average particle size (D ₄ ).
A negatively chargeable magnetic toner having a particle size of 1 μm (the content of the magnetic toner particles having a particle diameter of 12.7 μm or more, 33%) was obtained.

A magnetic developer was prepared by mixing 100 parts of the obtained magnetic toner and 0.6 parts of hydrophobic colloidal silica treated with dimethyl silicone oil using a Henschel mixer.

This magnetic developer was supplied to an apparatus unit (toner cartridge) of a laser beam printer LBP-8II, and an image output test was performed in the same manner as in Example 5. Table 5 shows the results.

Example 7 100 parts of styrene-n-butyl acrylate (copolymerization weight ratio 8: 2, Mw 300,000) 120 parts of magnetic iron oxide of Production Example 7 Negative charge control agent (monoazo dye-based chromium complex) 2 parts-Low molecular weight polypropylene 3 parts Magnetism having a weight average particle diameter (D ₄ ) of 4.2 μm (0% content of magnetic toner particles having a particle diameter of 12.7 μm or more) in the same manner as in Example 5 using the above materials. A toner was obtained.

A magnetic developer was prepared by mixing 100 parts of the obtained magnetic toner and 1.6 parts of hydrophobic colloidal silica treated with silicone oil using a Henschel mixer.

Using this magnetic developer, a multi-image printing test was performed in the same manner as in Example 5. Table 5 shows the results.

Example 8 Styrene-n-ethylhexyl acrylate-100 parts n-butyl maleate half ester copolymer (copolymerization weight ratio 7.5: 1.5: 1, Mw 250,000) Magnetic property of Production Example 8 iron oxide 90 parts Negative charge control agent (dialkylsalicylic acid chromium complex) weight average particle diameter in the same manner as in example 5 using 1 part low molecular weight polypropylene 3 parts the above materials (D ₄₎ 8.5 .mu.m (particle A magnetic toner having a content of magnetic toner particles having a diameter of 12.5 μm or more (4%) was obtained.

A magnetic developer was prepared by mixing 100 parts of the obtained magnetic toner and 1 part of hydrophobic colloidal silica fine powder treated with hexamethyldisilazane and then treated with silicone oil using a Henschel mixer.

The magnetic developer was applied to a laser beam printer LBP-8II to form a vertical image on A4 copy paper.
The image was supplied to an apparatus unit (toner cartridge) of a remodeled machine which was remodeled so that the number of sheets / min was changed, and an image output test was performed in the same manner as in Example 5. Table 5 shows the results.

Comparative Example 3 A weight average particle size of 6.9 μm (particle size of 1) was obtained in the same manner as in Example 5 except that the magnetic iron oxide of Comparative Production Example 3 was used.
A magnetic toner having a content of magnetic toner particles of 2.7 μm or more (0.3%) was obtained. Using the obtained magnetic toner, a magnetic developer was prepared in the same manner as in Example 5, and an image-drawing test was performed in the same manner as in Example 5 using the prepared magnetic developer. Table 5 shows the results.

Comparative Example 4 A weight average particle size of 8.8 μm (particle size 1) was obtained in the same manner as in Example 8 except that the magnetic iron oxide of Comparative Production Example 4 was used.
A magnetic toner having a content of magnetic toner particles of 2.7 μm or more (5.1%) was obtained. Using the obtained magnetic toner, a magnetic developer was prepared in the same manner as in Example 8, and an image output test was performed in the same manner as in Example 8 using the prepared magnetic developer. Table 5 shows the results.

Comparative Example 5 The magnetic iron oxide of Production Example 5 was used and had a weight average particle diameter of 14.1 μm (content of magnetic toner particles having a particle diameter of 12.7 μm or more: 59%) as in Example 1. A magnetic toner was obtained, a magnetic developer was prepared in the same manner as in Example 5, and an image output test was performed in the same manner as in Example 5. Table 5 shows the results.

As compared with the magnetic developer of Example 5, dot reproducibility was inferior, and toner dust was observed.

[0258]

[Table 5] Hereinafter, Synthesis Examples 1 to 4 are synthesis examples of the binder resins used in Examples 9 to 12.

(Synthesis Example 1) 76 parts of styrene monomer 14 parts of n-butyl acrylate 10 parts of monobutyl maleate 8 parts of di-tert-butyl peroxide Cumene 200 in which each of the above components was heated to the reflux temperature The mixture was added dropwise over 4 hours. Furthermore, under cumene reflux (146
１５156 ° C.) to complete the solution polymerization and remove cumene.
The obtained copolymer (I) had a molecular weight at the position of the main peak of GPC of 5,000 and a Tg of 60 ° C.

30 parts of the copolymer was dissolved in the following monomer mixture to prepare a mixed solution.・ 43 parts of styrene monomer ・ 15 parts of n-butyl acrylate ・ 9 parts of n-butyl methacrylate ・ 3 parts of monobutyl maleate ・ 0.35 part of divinylbenzene ・ 1.5 parts of benzoyl peroxide 1.5 parts of polyvinyl alcohol in the above mixed solution Compound 0.
170 parts of water in which 1 part was dissolved was added to obtain a suspension dispersion.
The above suspension dispersion was added to a reactor filled with 15 parts of water and purged with nitrogen, and a suspension polymerization reaction was performed at a reaction temperature of 70 to 95 ° C for 6 hours. After completion of the reaction, the mixture was filtered off, dehydrated and dried, and styrene-
A composition of n-butyl acrylate copolymer and styrene-n-butyl acrylate-n-butyl methacrylate-monobutyl maleate copolymer was obtained.

In the composition, a THF-insoluble component and a THF-soluble component were uniformly mixed, and styrene-acrylic acid n-
The butyl copolymer and the styrene-n-butyl acrylate-n-butyl methacrylate-monobutyl maleate copolymer were uniformly mixed. T of the obtained resin composition (A)
The HF insoluble content (measured with a powder of 24 mesh pass, 60 mesh on) was 45 parts. When the molecular weight distribution of the THF-soluble component was measured, the peak was located at about 0.550000 and the shoulder was located at about 34,000 in the GPC chart. The resin had a Tg of 59 ° C. And the acid value was 18.6.

In the present invention, the glass transition point Tg of the resin and the toner is determined by a differential thermal analyzer (DSC analyzer).
ASTM D using SC-7 (manufactured by PerkinElmer)
It was measured according to the 3418-82 method.

The measurement sample is 5 to 20 mg, preferably 10
Weigh the mg precisely.

This was put in an aluminum pan, an empty aluminum pan was used as a reference, and the temperature was raised once to 200 ° C. and rapidly cooled. At normal temperature and normal humidity.

In this heating process, an endothermic peak of a main peak in a temperature range of 40 to 100 ° C. is obtained.

The intersection of the line at the midpoint of the baseline before and after the endothermic peak appeared and the differential heat curve was determined.

Further, the acid value of the resin was measured according to JIS K-0070 by the following method.

Samples 2 to 10 g are weighed in 200 to 300 ml.
Weighed in an Erlenmeyer flask, and ethanol: benzene = 1: 1
About 50 ml of the mixed solvent of No. 2 is added to dissolve the resin. If the solubility is poor, a small amount of acetone may be added. Using a phenolphthalene indicator, titration was performed with a pre-specified N / 10 potassium hydroxide-alcohol solution, and the acid value was determined from the consumption of the alcohol potassium solution by the following formula.

Acid value = KOH (ml number) × N × 56.1 / sample weight (where N is a factor of N / 10 KOH) (Synthesis example 2) ・ Styrene monomer 87 parts ・ N-butyl acrylate 13 parts ・6 parts of di-tert-butyl peroxide The above components were added dropwise to 200 parts of xylene heated to reflux temperature over 4 hours. Further, under xylene reflux (1
(38-144 ° C.) to complete the solution polymerization and remove xylene. The obtained copolymer (II) had a molecular weight at which the main peak of GPC was located at 8,700 and a Tg of 61 ° C.

30 parts of the copolymer was dissolved in the following monomer mixture to prepare a mixed solution. -35 parts of styrene monomer-10 parts of 2-ethylhexyl acrylate-15 parts of n-butyl methacrylate-10 parts of monobutyl maleate-0.4 parts of divinylbenzene-1.7 parts of benzoyl peroxide 1.7 parts of polyvinyl alcohol in the above mixed solution Compound 0.
170 parts of water in which 1 part was dissolved was added to obtain a suspension dispersion.

The above dispersion was added to a reactor filled with 15 parts of water and purged with nitrogen, and reacted at a reaction temperature of 70 to 95 ° C. for 6 hours. After completion of the reaction, the mixture was filtered, dehydrated and dried to obtain a resin composition (B). The THF insoluble content of the obtained resin composition is 5
5 copies. When the molecular weight distribution of the THF-soluble component was measured, the GPC chart had a peak at about 0.9000, a shoulder at about 36,000, and a resin Tg of 55.5. At ° C., the acid number was 30.0.

(Synthesis Example 3) 100 parts of styrene monomer 12 parts of di-tert-butyl peroxide 150 parts of cumene was placed in a reactor and heated to a reflux temperature. Further, the mixture was added dropwise over 4 hours under cumene reflux. Then, polymerization was completed under cumene reflux (146 to 156 ° C.), and cumene was removed. The obtained polystyrene (III) has a main peak at a molecular weight of 4,000,
Tg was 67 ° C. 40 parts of the above polystyrene was dissolved in the following monomer mixture to obtain a mixture.・ Styrene monomer 35 parts ・ N-butyl acrylate 10 parts ・ N-butyl methacrylate 10 parts ・ Methyl methacrylate 5 parts ・ Divinylbenzene 0.4 part ・ Benzoyl peroxide 1.3 parts The above mixture is partially saponified with polyvinyl alcohol. 0.1
170 parts of water in which the above parts were dissolved was added to obtain a suspension dispersion. The above dispersion was added to a reactor filled with 15 parts of water and purged with nitrogen, and reacted at a reaction temperature of 70 to 95 ° C. for 6 hours. After the completion of the reaction, the mixture was filtered, dehydrated, and dried.
A composition of n-butyl acrylate-n-butyl methacrylate-methyl methacrylate copolymer was obtained.

The obtained resin composition (C) had a THF-insoluble content of 60 parts. When the molecular weight distribution of the THF-soluble component was measured, a peak was found at a position of about 0.450000 in the GPC chart, a shoulder was found at a position of about 38,000, and the Tg of the resin was 56 ° C. Was 0.6.

(Synthesis Example 4) A copolymer composition was obtained in the same manner as in Synthesis Example 3, except that 30 parts of the copolymer (III) was dissolved in the following monomer mixture to carry out polymerization. 48 parts of styrene monomer 10 parts of n-butyl acrylate 12 parts of n-butyl methacrylate 0.6 parts of divinylbenzene 1.5 parts of benzoyl peroxide THF-insoluble component of the obtained polymer composition (D) Was 60 parts. When the molecular weight distribution of the THF-soluble component was measured, a peak was found at a molecular weight of about 0.540, and a shoulder was found at about 37,000 in the GPC chart.
Was 65 ° C. and the acid value was 1.2.

(Comparative Synthesis Example 1) 200 parts of cumene was charged into a reactor and heated to the reflux temperature. The following mixture was added dropwise over 4 hours under cumene reflux. -75 parts of styrene monomer-25 parts of n-butyl methacrylate-6 parts of di-tert-butyl peroxide Further, polymerization was completed under cumene reflux (146 to 156 ° C), and cumene was removed. The obtained styrene-n-butyl acrylate copolymer (IV) had a main peak at a position of a molecular weight of 6,300, and Tg was 55 ° C.

30 parts of the above copolymer was dissolved in the following monomer mixture to obtain a mixture. -55 parts of styrene monomer-15 parts of 2-ethylhexyl acrylate-0.1 part of divinylbenzene-1.7 parts of benzoyl peroxide 1.7 parts of partially saponified polyvinyl alcohol in the above mixed solution.
170 parts of water in which 1 part was dissolved was added to obtain a suspension dispersion.
The above suspension and dispersion were added to a reactor in which 15 parts of water had been introduced and purged with nitrogen, and reacted at a reaction temperature of 70 to 95 ° C. for 6 hours. After completion of the reaction, the mixture was filtered, dehydrated and dried to obtain a composition (E) of styrene-2-ethylhexyl acrylate-monobutyl maleate copolymer. The molecular weight distribution of the obtained resin is
It has a peak at 0.65 million, a shoulder at about 32,000,
The insolubles in THF were 15 parts, the Tg was 60 ° C., and the acid value was 0.3.

Embodiments 9 to 12 are specific examples according to the present invention 3.

Example 9 100 parts of resin composition (A) of Synthesis Example 1 100 parts of magnetic iron oxide of Production Example 1 1 part of negative charge control agent (monoazo dye-based chromium complex) 1 part of low molecular weight polypropylene 3 parts Using the above materials, a negatively chargeable magnetic toner having a weight average particle diameter (D ₄ ) of 6.8 μm (content of magnetic toner particles having a particle diameter of 12.7 μm of 0.2%) was obtained in the same manner as in Example 1. .

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

Using this magnetic developer, a multi-image printing test for up to 6000 sheets was performed in the same manner as in Example 1. Table 7 shows the results.

Examples 10 to 12 Toners were produced in the same manner as in Example 1 except that the ingredients of the toner were mixed as shown in Table 6.
Evaluation was performed in the same manner as described above. Table 7 shows the results.

The toner described above had good pulverizability without fusing to the inner wall of the apparatus in the pulverization step during production.
(However, since the pulverized particle diameter of the toner of Example 11 was very small, the time required for pulverization was the longest, and slight contamination was observed on the impingement plate of the pulverizer, but there was no particular problem.)
As shown in Table 7, the fixing property, the offset resistance and the blocking resistance showed very good results.

[0283]

[Table 6] Comparative Example 6 A toner was produced in the same manner as in Example 1, except that the magnetic iron oxide of Comparative Production Example 1 and the resin composition E of Comparative Synthesis Example 1 were used.
The same evaluation as in Example 1 was performed. In the pulverizing step in the production of the toner, the throughput per hour was reduced by about 20% as compared with Example 9, and the impact plate of the pulverizer was examined to find that the toner composition was slightly fused. As shown in Table 7, the results of the other evaluations were inferior to the examples and were insufficient.

[0284]

[Table 7] Table 8 below shows the physical properties of the toners of Examples 9 to 12 and Comparative Example 6.

[0285]

[Table 8] Examples 13 to 16 are specific examples according to the present invention 4.

Example 13 Styrene-2-ethylhexyl acrylate-100 parts n-butyl maleate half-ester copolymer (copolymer weight ratio 7.5: 1.5: 1, Mw 300,000) iron oxide 100 parts Negative charge control agent (dialkylsalicylic acid chromium complex) weight average particle diameter in the same manner as in example 1 using 1 part low molecular weight polypropylene 4 parts the above materials (D ₄₎ 7.0 .mu.m (particle A negatively-chargeable magnetic toner having a magnetic toner particle content of 5% with a diameter of 12.7 μm was obtained.

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

The transfer agent as shown in FIG. 9 was incorporated into the apparatus unit (toner cartridge) of a commercially available laser beam printer LBP-8II (manufactured by Canon Inc.), and the obtained developer was modified as shown in FIG. The condition of the transfer roller 16 is as follows:
7 °, the transfer current was 1 μA, and the contact pressure was 50 [g / cm].

The rotation speed of the outer diameter of the photosensitive drum 3, which is the process speed, is set to 100 mm / sec.
700 V, a gap (300 μm) was set without contact between the photosensitive drum and the developer layer on the developing sleeve (magnet encapsulation 15), and an AC bias (f = 1,800 Hz, Vpp =
1600 V) and DC bias (V _DC = −500)
V) to the developing sleeve while applying _VL to -170 V
And imaged. Table 9 shows the results of evaluation of the toner-fixed image formed and fixed by the heating and pressing roller.

Example 14 A magnetic powder having a weight average particle diameter of 13 μm (40% content of magnetic toner particles having a particle diameter of 12.7 μm or more) was prepared in the same manner as in Example 1 except that the magnetic iron oxide of Production Example 2 was used. A toner was obtained.

A magnetic developer was prepared by mixing 100 parts of the obtained magnetic toner and 0.8 parts of hydrophobic colloidal silica treated with silicone oil using a Henschel mixer.
Process speed of 250 using prepared magnetic developer
An image-drawing test was performed in the same manner as in Example 13 except that mm / sec was used. Table 9 shows the results.

Example 15 An image output test was performed in the same manner as in Example 13 except that the transfer condition was changed to 20 g / cm. Table 9 shows the results.

Example 16 A weight average particle diameter (D ₄ ) of 4 μm (particle diameter of 1 μm) was obtained in the same manner as in Example 1 except that the amount of the magnetic iron oxide in Production Example 3 was changed to 80 parts.
A magnetic toner having a content of magnetic toner particles of 2.7 μm or more (0%) was obtained.

A magnetic developer was prepared by mixing 100 parts of the obtained magnetic toner and 1.8 parts of hydrophobic colloidal silica treated with silicone oil using a Henschel mixer.

An image output test was performed in the same manner as in Example 13 except that the process speed was set to 36 mm / sec using this magnetic developer. Table 9 shows the results.

Comparative Example 7 A weight-average particle diameter of 10 μm (particle diameter of 12 μm) 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 7 μm or more (27%) was obtained. Example 13 was prepared using the obtained magnetic toner.
A magnetic developer was prepared in the same manner as described above, and an image output test was performed in the same manner as in Example 13 using the prepared magnetic developer.
Table 9 shows the results.

Comparative Example 8 A weight average particle diameter of 7 μm (particle diameter of 12.7) was obtained in the same manner as in Example 1 except that the magnetic iron oxide of Comparative Production Example 2 was used.
A magnetic toner having a content of magnetic toner particles of 0.3 μm or more (0.3%) was obtained. Example 14 was prepared using the obtained magnetic toner.
A magnetic developer was prepared in the same manner as described above, and an image output test was performed in the same manner as in Example 14 using the prepared magnetic developer.
Table 9 shows the results.

Comparative Example 9 A magnetic toner 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%) was prepared in the same manner as in Example 1 using the magnetic iron oxide of Production Example 1. And a magnetic developer was prepared in the same manner as in Example 13.
An image-drawing test was performed in the same manner as described above. Table 9 shows the results.

As compared with the magnetic developer of Example 13, the dot reproducibility was inferior, and toner dust was observed.

[0300]

[Table 9] (1) Image density: ordinary LBP plain paper (75 g / m
² ) Evaluation was made by maintaining the image density when 3,000 sheets were passed.

○ (good): 1.35 or more Δ (acceptable): 1.0 to 1.34 × (impossible): 1.0 or less (2) Transfer state: ordinary LBP plain paper (75 g / m)
² ) After passing 3,000 sheets, the transfer conditions are severe 120.
g / m ² of thick paper was passed through, and evaluation was made based on the state of missing transfer.

○: good (see FIG. 8 a) Δ: practical use ×: bad (see FIG. 8 b) (3) Paper transport state: 1,000 sheets of 50 g / m ² thin paper are passed, and skewed such as skewed Was evaluated.

○: Within 1 time / 1,000 sheets △: 2 to 4 times / 1,000 sheets ×: 5 times or more / 1,000 sheets (4) Image quality: Normal LBP plain paper (75 g / m
² ) The scattering of toner and the roughness of the image were visually evaluated when 3,000 sheets were passed.

：: good Δ: practicable ×: practicable (5) Fog: under low temperature and low humidity environment (10 ° C., 15% RH)
, Fog when 3,000 sheets of plain paper for LBP (75 g / m ² ) were passed was measured and evaluated.

○ (good): 2.0% or less △ (acceptable): 2.0 to 5.0% × (impossible): 5.0% or more

[0306]

According to the present invention, a magnetic iron oxide having a characteristic distribution of silicon element is prepared by using a magnetic iron oxide having a weight average particle diameter of 13.5 μm or less and a content of magnetic toner particles having a particle diameter of 12.7 μm or more. The environmental stability and development characteristics of the magnetic toner can be improved by using it as a magnetic material of a magnetic toner containing a large amount of magnetic toner particles having a small particle diameter of not more than weight%.

[Brief description of the drawings]

FIG. 1 is a view showing a dissolution curve of 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 view showing a specific example of an image forming apparatus (with an elastic blade) used in the present invention.

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

FIG. 5 is a schematic explanatory view showing a specific example of an apparatus unit used in the present invention.

FIG. 6 is a block diagram showing a specific example of the facsimile apparatus of the present invention.

FIG. 7 is an explanatory diagram of a checker pattern for testing development characteristics of a magnetic toner.

FIG. 8 is a diagram schematically illustrating a toner image after transfer.

FIG. 9 is an explanatory diagram of a roller transfer device.

FIG. 10 is an explanatory diagram of a belt-type transfer device.

FIG. 11 is a schematic explanatory view showing another specific example of the device unit used in the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Developing device 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 19 Erase exposure

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-62-278131 (JP, A) JP-A-63-105901 (JP, A) JP-A-5-213620 (JP, A) JP-A 53-105 81125 (JP, A) JP-A-3-177847 (JP, A) JP-A-3-87839 (JP, A) JP-A-3-121462 (JP, A) JP-A-4-274442 (JP, A) JP-A-3-59568 (JP, A) JP-A-60-244956 (JP, A) JP-A-3-231758 (JP, A) JP-A-53-118052 (JP, A) (58) (Int.Cl. ⁷ , DB name) G03G 9/083-9/087

Claims (6)

(57) [Claims] 1. A magnetic toner containing at least a binder resin and a magnetic iron oxide, wherein the magnetic toner has a weight average particle size of 13.5 μm or less, and a particle size distribution of 12.7 μm in the particle size distribution of the magnetic toner. 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 existing when the iron element 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 84. %, And the ratio (C / A) × 100 of the content C of the silicon element present on the surface of the magnetic iron oxide to the content A is 10 to 55.
%, Wherein the binder resin is a mixture of a vinyl polymer and a polyester resin. 2. A magnetic toner containing at least a binder resin and a magnetic iron oxide, wherein the magnetic toner has a weight average particle size of 13.5 μm or less, and a particle size distribution of 12.7 μm in the particle size distribution of the magnetic toner. 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 existing when the iron element 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 84. %, And the ratio (C / A) × 100 of the content C of the silicon element present on the surface of the magnetic iron oxide to the content A is 10 to 55.
%, Wherein the surface of the magnetic iron oxide is treated with silicone oil or silicone varnish. 3. A magnetic toner containing at least a binder resin and magnetic iron oxide, wherein the magnetic toner has a weight average particle size of 13.5 μm or less, and a particle size distribution of 12.7 μm in the particle size distribution of the magnetic toner. 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 existing when the iron element 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 84. %, And the ratio (C / A) × 100 of the content C of the silicon element present on the surface of the magnetic iron oxide to the content A is 10 to 55.
%, The binder resin is a copolymer obtained from at least a styrene-based monomer and an acrylic-based monomer, and has an acid value of 1 to 70 in THF-insoluble and soluble components, and THF
The molecular weight distribution of the soluble component has at least one peak at a molecular weight of 2,000 or more to less than 15,000 in the GPC chart, and a molecular weight of 15,000 to 100,000.
A magnetic resin having a Tg of 45 to 65 ° C. and a THF-insoluble content of 20 parts by weight or more based on 100 parts by weight of the resin component. 4. The magnetic toner according to claim 3, wherein the THF-insoluble component contains two or more acrylic monomers. 5. A magnetic toner having a weight average particle size of 3.5 to 9.
μm, and a particle size of 1 in the particle size distribution of the magnetic toner.
Content of magnetic toner particles of 2.7 μm or more is 10% by weight
The magnetic toner according to claim 3, wherein: 6. The electrostatic image holding member for holding an electrostatic image on a surface has a rotation speed of an outer diameter of 35 mm / sec or more, and the electrostatic image on the electrostatic image holding member is developed by a developer. An image forming method comprising a step of electrostatically transferring a developed image to a transfer material, wherein the electrostatic image holding member is in contact with a transfer means at a linear pressure of 10 g / cm or more, and the developer is a binder resin. And a magnetic developer comprising at least a magnetic toner containing at least a magnetic iron oxide, and an inorganic fine powder or a hydrophobic inorganic fine powder, wherein the magnetic toner has a weight average diameter of 13.5 μm or less; In the particle size distribution, the particle size is 12.7μ.
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 55.
%.