JPH0572801A - Magnetic toner, magnetic developer, device unit, image forming device and facsimile equipment - Google Patents

Abstract

PURPOSE:To obtain a magnetic toner with which toner images excellent in environmental stability and having high image density can be formed and excellent dot reproducibility can be obtained by incorporating magnetic iron oxides having a specified distribution of silicon compds. CONSTITUTION:This magnetic toner contains at least a binder resin and magnetic iron oxide and has <=13.5mum weight mean average particle size and <=50wt.% of magnetic toner particles having >=12.7mum particle size. The magnetic iron oxide contains 0.5-4wt.% silicon element to iron element as the reference, and shows the relation of (B/A)X100=44 to 84 (%), wherein A is the total amt. of silicon element in the magnetic iron oxide and B is the amt. of silicon element in which the proportion of dissolving iron element is to 20wt.%. Further, it shows the relation of (C/A)X100=10 to 55 (%), wherein C is the amt. of silicon element present in the surface of the iron oxide particles.

Description

Detailed Description of the Invention

[0001]

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

[0002]

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

Various developing methods are known in which an electrostatic latent image is visualized using toner. For example, US Pat. No. 2,87
No. 4,063, a magnetic brush method, No. 2,618,552, a cascade developing method, and No. 2,221,776, a powder. Cloud method, fur brush development method,
Many developing methods such as liquid developing methods are known. Among these developing methods, a magnetic brush method, a cascade method, a liquid developing method, and the like, which use a developer mainly composed of toner and carrier, have been widely put into practical use. All of these methods are excellent methods in which a good image can be obtained relatively stably, but on the other hand, they have the common problems associated with two-component developers, such as deterioration of the carrier and fluctuations in the mixing ratio of the toner and the carrier.

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

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

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

As another developing method using a high resistance insulating magnetic toner, the toner particles are triboelectrically charged by friction between the toner particles, friction between the toner particles and the sleeve, etc., and this is used as an electrostatic image holding member. A method of contacting and developing is known. However, these methods have problems that the number of contact between the toner particles and the friction member is small and triboelectrification tends to be insufficient, and the cloned force between the charged toner particles and the sleeve is strengthened and the toner particles are easily aggregated on the sleeve. It had, and was practically difficult.

However, in Japanese Patent Laid-Open No. 55-18656, a new jumping developing method which eliminates the above-mentioned problems has been proposed. This involves applying a very thin coating of magnetic toner on a sleeve, tribocharging it, and then developing it in close proximity to the electrostatic image. This method increases the chance of contact between the sleeve and the toner by applying the magnetic toner very thinly on the sleeve, and enables sufficient triboelectrification.The magnetic toner supports the magnetic toner and the magnet and the toner are opposed to each other. By moving the toner particles together, the toner particles agglomerate with each other, and the toner particles are sufficiently rubbed with each other, so that an excellent image can be obtained.

However, in the developing method using the improved insulating toner, there is an unstable factor related to the insulating toner used. This is because the magnetic charging characteristics in the form of fine powder are 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. The fluidity and triboelectricity of the toner are affected, and as a result, various characteristics such as developing characteristics and durability of the magnetic toner, which are required for the magnetic toner, are changed or deteriorated.

More specifically, in the conventional jumping developing method using a magnetic toner containing a magnetic material, if a repeated developing process (for example, copying) is continued for a long period of time, the developer containing the magnetic toner will be Liquidity deteriorated,
Normal frictional electrification cannot be obtained, electrification is likely to be non-uniform, fog development is likely to occur in a low temperature and low humidity environment, and a serious problem on a toner image is likely to occur. Also,
When the adhesiveness between the binder resin constituting the magnetic toner particles and the magnetic charging property is weak, the magnetic substance is removed from the surface of the magnetic toner by repeated development steps, which adversely affects the toner image density reduction. Tend.

When the dispersion of the magnetic substance in the magnetic toner particles is not uniform, small magnetic toner particles containing a large amount of the magnetic substance are accumulated on the sleeve, resulting in a decrease in image density and a sleeve ghost. Occurrence of so-called shading unevenness may be seen.

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

For example, Japanese Patent Laid-Open No. 62-279352 proposes a magnetic toner containing magnetic iron oxide containing silicon element. Such magnetic iron oxide is
Although the elemental silicon is intentionally allowed to exist 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 to control the shape of magnetic iron oxide into a spherical shape by adding a silicate. The magnetic iron oxide obtained by this method has a large amount of silicon element distributed inside the magnetic iron oxide because a silicate is used for controlling the particle size, and the amount of silicon element present on the surface of the magnetic iron oxide is small, The fluidity of the magnetic toner is improved and the smoothness of the magnetic iron oxide is high, so that the adhesion between the binder resin forming the magnetic toner and the magnetic iron oxide tends to be insufficient.

Further, Japanese Patent Application Laid-Open No. 61-34070 proposes a method for producing ferrosoferric oxide by adding a hydroxosilicate solution during the oxidation reaction to ferrosoferric oxide. The iron tetroxide produced by this method has a Si element in the vicinity of the surface, but the Si element exists in a layer in the vicinity of the surface of the iron tetroxide, and the surface is vulnerable to mechanical impact such as friction. Have a point.

In recent years, the functions of image forming apparatuses using electrophotography, such as copying machines and laser beam printers, have diversified, and there is a demand for higher definition and higher image quality of toner images obtained.

[0017]

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

Further, the object of the present invention is to obtain a high image density,
It is to provide a magnetic toner having excellent image reproducibility.

A further object of the present invention is to provide a magnetic toner which is free from fog even when used for a long time and has stable charging performance.

A further object of the present invention is to provide a magnetic developer having the magnetic toner, an apparatus unit, an image forming apparatus and a facsimile apparatus.

[0021]

The present invention provides 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.
(Preferably 3.5 to 13.5 μm), and in the particle size distribution of the magnetic toner, the content of magnetic toner particles having a particle size of 12.7 μm or more is 50% by weight or less, and the magnetic iron oxide is , The content of elemental silicon in the magnetic iron oxide is
0.5 to 4% by weight based on the iron element, the content B of the silicon element present in the magnetic iron oxide having an iron element dissolution rate of up to 20% by weight, and the total content of the silicon elements of the magnetic iron oxide. The ratio (B / A) × 100 to the amount A is 44 to 84%,
The present invention relates to a magnetic toner characterized in that a ratio (C / A) × 100 of the content C of silicon element present on the surface of the magnetic iron oxide and the content A is 10 to 55%.

Furthermore, the present invention provides a magnetic developer comprising a magnetic toner containing at least a binder resin and magnetic iron oxide, and an inorganic fine powder or a hydrophobic inorganic fine powder, wherein the magnetic toner has a weight average particle diameter. Is 13.5 μm or less (preferably 3.5 to 13.5 μm), and in the particle size distribution of the magnetic toner, the content of magnetic toner particles having a particle size of 12.7 μm or more is 50% by weight or less, The magnetic iron oxide has a silicon element content of 0.5 to 4% by weight based on the iron element, and the iron content of the magnetic iron oxide is up to 20% by weight. The ratio (B / A) of the content B of the element to the total content A of the silicon element of the magnetic iron oxide × 100 is 44 to 84%, and the content of the silicon element existing on the surface of the magnetic iron oxide is contained. Amount C and the content A
And a ratio (C / A) × 100 of 10 to 55%.

Further, the present invention has a latent image carrier for carrying a latent image and a developing device for developing the latent image,
The developing device includes a developer container for containing a developer,
A developer carrier that carries and conveys the developer in the developer container from the developer container to the developing area facing the latent image carrier, and a developer that is carried and conveyed by the developer carrier are predetermined. Of a magnetic toner containing at least a binder resin and magnetic iron oxide, and a regulating blade for controlling the thickness of the developer carrier to form a thin developer layer on the developer carrier. The magnetic toner has a weight average particle diameter of 13.5 μm or less (preferably 3.5 to 13.5 μm), and the content of magnetic toner particles having a particle diameter of 12.7 μm or more in the particle size distribution of the magnetic toner. Is 50% by weight or less, and the magnetic iron oxide is
The content of the silicon element in the magnetic iron oxide is 0.5 to 4% by weight based on the iron element, and the content B of the silicon element in which the dissolution rate of the iron element in the magnetic iron oxide is up to 20% by weight.
And the total content A of silicon element of the magnetic iron oxide (B /
A) × 100 is 44 to 84%, and the ratio (C / A) × 100 of the content C of the silicon element present on the surface of the magnetic iron oxide and the content A is 10 to 55%. The present invention relates to a characteristic device unit.

Further, the present invention has a latent image carrier for carrying a latent image and a developing device for developing the latent image,
The developing device includes a developer container for containing a developer,
In an image forming apparatus having a developer carrier that carries and conveys the developer in the developer container from the developer container to a developing area facing the image carrier, the developer is a binder resin and a magnetic oxide. The magnetic toner contains at least iron, and the magnetic toner has a weight average particle size of 13.5 μm or less (preferably 3.5 to 13.5 μm). The content of the magnetic toner particles 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. And the ratio (B / A) × 100 of the content B of the silicon element present in the magnetic iron oxide having an iron element solubility of up to 20% by weight and the total content A of the silicon element of the magnetic iron oxide is 100. ~ 84%, silicon present on the magnetic iron oxide surface An image forming apparatus which the ratio between the content C and the content A of the unit (C / A) × 100 is characterized in that 10 to 55%.

Further, the present invention is a facsimile apparatus having an electrophotographic apparatus and a receiving means for receiving image information from a remote terminal, the electrophotographic apparatus being an image carrier for carrying a latent image and the latent image. A developing device for developing the developer, the developing device including a developer container for containing the developer, and the developer in the developer container from the developer container to a developing area facing the image carrier. And a developer carrier that carries and conveys the developer, and regulates the developer carried and conveyed by the developer carrier to a predetermined thickness to form a thin layer of developer on the developer carrier. The developer has a magnetic toner containing at least a binder resin and magnetic iron oxide, and the magnetic toner has a weight average particle diameter of 13.
5 μm or less (preferably 3.5 to 1.35 μm), and in the particle size distribution of the magnetic toner, the particle size is 12.7 μm.
The content of the magnetic toner particles of m or more is 50 wt% or less, the content of silicon element of the magnetic iron oxide is 0.5 to 4 wt% based on the iron element, The ratio (B / A) × 100 of the content B of the silicon element present in the magnetic iron oxide having an iron element dissolution rate of up to 20% by weight and the total content A of the silicon element of the magnetic iron oxide × 100 is 44 to 84. %, And the content C of elemental silicon present on the surface of the magnetic iron oxide.
And the content A (C / A) × 100 is 10 to 55%
And a facsimile machine.

[Detailed Description of the Invention] The reason why the above-described effects are obtained in the magnetic developer of the present invention is not always clear, but it 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.
5-13.5 μm), and in the particle size distribution of the magnetic toner, the magnetic toner containing 50% by weight or less of the magnetic toner particles having a particle size of 12.7 μm or more is added to the specific magnetic iron oxide containing 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 exceeds 1%, or when the content of the magnetic toner particles having a particle size of 12.7 μm or more exceeds 50% by weight, the magnetic toner containing a large amount of relatively coarse magnetic toner particles is generally used conventionally. It is possible to stabilize the charging of the magnetic toner even by using the above-mentioned magnetic iron oxide.

The weight average particle diameter of the magnetic toner particles is 3.5 μ.
If it is smaller than m, the fluidity of the magnetic toner becomes low even if the special magnetic iron oxide of the present invention is used, and problems such as fog due to charging failure and density thinning are likely to occur. The diameter is preferably 3.5 μm or more.

That is, in the magnetic toner of the present invention, remarkable effects such as improvement of charging stability and fluidity as compared with the conventional example are observed, and the weight average particle diameter is 13.5 μm or less (preferably 3.5). 〜13.5 μm, more preferably 5.0〜
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 silicon element in 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.
%, And more preferably 0.9 to 3.0% by weight). When the content of the silicon element is less than 0.5% by weight, the effect of improving the magnetic toner (particularly the improvement of the fluidity of the magnetic toner) is weak, and the content of the silicon element is more than 4.0% by weight. In addition, the silicic acid component is undesirably left on the surface of the magnetic iron oxide more than necessary and is likely to adversely affect the magnetic properties.

Further, in the present invention, the total content A of the silicon element present in the magnetic iron oxide used for the magnetic toner and the content B of the silicon element present in the magnetic iron oxide having a dissolution rate of the iron element of up to about 20%. The ratio B / A x 100 (%) with is 44 to 8
4% (preferably 60 to 80%), and the content C and the content A of the silicon element existing on the surface of the magnetic iron oxide particles.
One of the characteristics is that the ratio C / A × 100 (%) with 10 to 55% (preferably 25 to 40%). B /
When A × 100 (%) is less than 44% and the silicon element is present in the central portion in an unnecessarily large amount, not only the production efficiency is easily deteriorated, but also magnetic iron oxide having unstable magnetic properties is obtained. There are cases.

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

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

That is, in order to obtain good magnetic toner characteristics, the distribution of the silicon element present in the magnetic iron oxide should increase continuously or stepwise from the inside to the surface as described above. preferable.

Further, in the present invention, the charge amount of magnetic iron oxide is −25 to −70 μc / g (preferably −40 to −60 μm).
c / g) and the volume resistivity of magnetic iron oxide is 1
× 10 ⁴ to 1 × 10 ⁸ Ω · cm (preferably 5 × 10 ⁴ to
It is preferably 5 × 10 ⁷ Ω · cm).

When the charge amount of the magnetic iron oxide is less than -25 μc / g, when the magnetic toner is repeatedly used for a long period of time, the charge amount required by the magnetic toner tends to be lost, resulting in a decrease in image density and image fog. Occurs. On the other hand, when the charge amount of magnetic iron oxide exceeds -70 μc / g,
Since the charge amount of the magnetic toner becomes too high, the image density tends to decrease in a low temperature and low humidity environment.

The volume resistivity of magnetic iron oxide is 5 ×.
When it is less than 10 ³ Ω · cm, it becomes difficult to hold the charge amount required by the magnetic toner, and the image density is apt to decrease. On the other hand, when the volume resistivity of the magnetic iron oxide exceeds 1 × 10 ⁸ Ω · cm, the charge amount tends to increase more than necessary during repeated use in a low temperature and low humidity environment, resulting in a decrease in image density. It is easy to get hit.

Further, in the present invention, it is preferable that the magnetic iron oxide has an aggregation degree of 3 to 40% (preferably 5 to 30%).

If the degree of aggregation of magnetic iron oxide is less than 3%, blowing out of the magnetic toner, which is called flushing, tends to occur during the production of the magnetic toner, making it difficult to produce the magnetic toner efficiently.

On the other hand, if the cohesion exceeds 40%,
It is not easy to sufficiently disperse the magnetic iron oxide in the magnetic toner, and the image density and fog are likely to be adversely affected. Further, in the present invention, the fluidity of the magnetic iron oxide is reflected in the fluidity of the magnetic toner, and the aggregation degree is 40%.
When the magnetic iron oxide exceeding the above range is used, it is difficult to obtain sufficient fluidity of the magnetic toner, which adversely affects the chargeability of the magnetic toner, and fog tends to occur.

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

When the smoothness D is less 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, which is easily dispersed in the magnetic toner and adversely affects the toner characteristics.

On the other hand, when the smoothness D is larger than 0.6, it is difficult to obtain sufficient adhesiveness between the binder resin used for the magnetic toner and the magnetic iron oxide, and the magnetic toner surface gradually increases after repeated use. The magnetic iron oxide is removed, and adverse effects such as reduction in image density are likely to occur.

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

When the sphericity ψ is less than 0.8, the individual particles of magnetic iron oxide come into surface-to-surface contact,
With small magnetic iron oxide particles 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 by a mechanical shearing force, and therefore, the magnetic iron oxide particles in the magnetic toner are not easily separated. May not be fully 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.
It is preferable to have a thickness of 0.3 μm.

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

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

That is, a Coulter Counter TA-II type (manufactured by Coulter) is used as a measuring device, and an interface (manufactured by Nikkaki) for outputting number distribution and volume distribution and a CX-1 personal computer (manufactured by Canon) are connected. , The electrolyte is 1st grade sodium chloride
% NaCl aqueous solution is prepared. As a measuring method, a surfactant (preferably an alkylbenzene sulfonate) as a dispersant was added in an amount of 0.1 to 100 ml in the electrolytic aqueous solution.
Add ~ 5 ml, and then add 2 to 20 mg of the measurement sample.
The electrolytic solution in which the sample is suspended is dispersed by an ultrasonic disperser for about 1 to 3 minutes, and the volume and number of the toner is measured to 2 to 40 μm by using the Coulter Counter TAII type with an aperture of 100 μm. Calculate the volume distribution and number distribution of the particles. 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 weight average diameter 12.7 μ obtained from the volume distribution.
Determine the weight distribution of m or more.

In the present invention, the content C of 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 at 50 to 60 ° C. About 25 g of magnetic iron oxide slurried with about 400 ml of deionized water is added to a 5 liter beaker together with the deionized water while being washed with about 300 ml of deionized water.

Next, while maintaining the temperature at about 60 ° C. and the stirring speed at about 200 rpm, sodium hydroxide such as silicic acid on the surface of the magnetic iron oxide particles was dissolved by adding special grade sodium hydroxide to prepare a sodium hydroxide solution of about 1N. To start. After 30 minutes from the start of dissolution, 20 ml was sampled,
Filter with a 0.1μ membrane filter and collect the filtrate. The filtrate is quantified for silicon element by plasma emission spectroscopy (ICP).

The elemental silicon content C corresponds to the elemental silicon concentration (mg / l) per unit weight of the magnetic iron oxide in the aqueous sodium hydroxide solution.

In the present invention, the content of silicon element in the magnetic iron oxide (based on iron element), the dissolution rate of iron element and the content of silicon element A and B can be determined by the following method. 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 was slurried with about 400 ml of deionized water to about 3
While washing with 00 ml of deionized water, add together with the deionized water into a 5 liter beaker.

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 the dissolution. At this time, the magnetic iron oxide concentration is about 5 g / l and the hydrochloric acid aqueous solution is about 3 N. Approximately 20 ml is sampled several times from the start of dissolution to the time when everything is dissolved and becomes transparent, filtered through a 0.1 μ membrane filter, and the filtrate is collected. The filtrate is subjected to plasma emission spectroscopy (ICP) to quantify iron element and silicon element.

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

[0058]

[Outer 1]

The content and content of elemental silicon for each sample are calculated by the following equation.

[0060]

[Outside 2]

The total content A of silicon in the magnetic iron oxide is
It corresponds to the elemental silicon concentration (mg / l) per unit weight of magnetic iron oxide after they are all dissolved.

The silicon element content B of the magnetic iron oxide corresponds to the silicon element concentration (mg / l) per unit weight of the magnetic iron oxide detected when the dissolution rate of the magnetic iron oxide is 20%. ..

As a method for measuring the contents A, B and C, (1) a magnetic iron oxide sample is divided into two and the contents of silicon element and the contents A and B are measured, while A method of separately measuring the amount C, and (2) measuring the content C of the magnetic iron oxide sample, and then using the sample after the measurement, the content B '(content B minus content C) ) And the content A ′ (the content A minus the content C), and finally calculate the contents A and B.

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

About 2 g of magnetic iron oxide and carrier iron powder (TEF
V200-300 mesh) (Nippon Iron Powder Co., Ltd.) about 19
8 g was weighed in 500 ml polybin, shaken by hand for 10 seconds, then shaken with a V-type blender for 20 minutes, and the amount of charge of magnetic iron oxide was measured using a blow-off powder charge amount measuring device (Toshiba Chemical Co., Ltd.). To measure. At this time, a 400 mesh mesh made of stainless steel was set to the Faraday gauge for measurement, a measurement sample amount of about 0.4 g was weighed, and the value was calculated by performing blow-off for 30 seconds.

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

10 g of magnetic iron oxide is put into a measuring cell and molded by a hydraulic cylinder (pressure 600 Kg / cm ² ). After releasing the pressure, the resistance meter (YEW MODE
L2506A DIGITAL MALTIME
R) is set, and again 150kg by hydraulic cylinder
Apply a pressure of / cm ² . Start the measurement and read the measured value after 3 minutes. Furthermore, the thickness of the sample is measured and the volume resistivity value is measured by the following formula.

[0068]

[Outside 3]

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

10 g of magnetic iron oxide was crushed with a mixer, and 2
Weigh 2 g of a sieve that has passed through a mesh of 00 mesh. The powder tester (Hosokawa Micron Co., Ltd.) was set with three sieves stacked in the order of 60 mesh, 100 mesh, and 200 mesh from the top, and 2 g of the sample weighed was gently placed on the sieve, and vibration with an amplitude of 1 mm was given for 65 seconds. The weight of the magnetic iron oxide remaining on each sieve is measured, and the aggregation degree is calculated according to the following formula.

[0071]

[Outside 4]

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

[0073]

[Outside 5]

The BET of magnetic iron oxide is actually measured as follows.

BET specific surface area is manufactured by Yuasa Ionics Co., Ltd., fully automatic gas adsorption measuring device: Autosorb 1
Is used, nitrogen is used as an adsorption gas, and the BET multipoint method is used. The sample pretreatment was 1
Degas for hours.

The average particle size is measured and the surface area of the magnetic iron oxide is calculated as follows.

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

To calculate the surface area, the magnetic iron oxide was assumed to be spherical with the average particle diameter as the diameter, the surface area and volume of the sphere were calculated from the average particle diameter, and the density of the magnetic iron oxide was measured by the usual method. The weight of the sphere is determined from the volume and density, and the surface area value calculated from the average particle size of the magnetic iron oxide is determined.

The sphericity ψ of the magnetic iron oxide in the present invention is calculated as follows.

[0080]

[Outside 6]

For the sphericity ψ, 100 magnetic iron oxide particle specimens were randomly selected from the photograph, the maximum length and the minimum length were measured, and then the calculated values were averaged.

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

Cubic ordinary magnetic iron oxide has a sphericity ψ of about 0.6 to less than 0.8, whereas the sphericity ψ 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 approximate to a spherical shape without angular ends.

When the sphericity ψ 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 the case where it is 0.8 or more. The developing characteristics of the obtained magnetic toner tend to be deteriorated, and the magnetic toner tends to be poor in dot reproducibility.

The magnetic iron oxide used in the magnetic toner of the present invention is 20 parts by weight to 2 parts by weight based on 100 parts by weight of the binder resin.
It is preferred 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.

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

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

The ethylene-based olefin homopolymer or ethylene-based olefin copolymer used herein includes polyethylene, polypropylene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer. There are coalesced products, ionomers having a polyethylene skeleton, and the like, and the above copolymer preferably contains 50 mol% or more (more preferably 60 mol% or more) of an olefin monomer.

As the coloring material which 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.

If desired, the magnetic toner of the present invention may contain a charge control agent.
Negative charge controlling agents such as metal complex salts of monoazo dyes, metal complex salts of salicylic acid, alkylsalicylic acid, dialkylsalicylic 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, silica fine powder is preferably added and used.

The silica fine powder used in the present invention includes both so-called dry process produced by vapor phase oxidation of a silicon halogen compound or dry silica called fumed silica and so-called wet silica produced from water glass. Although usable, dry silica, which has few silanol groups on the surface and inside and has no production residue, is preferable.

Further, it is preferable that the silica fine powder used in the present invention is subjected to a hydrophobic treatment. The hydrophobic treatment is applied by chemically treating it with an organic silicon compound or the like that reacts with or physically adsorbs on the silica fine powder. As a preferred method, a method of treating dry silica fine powder produced by vapor phase oxidation of a silicon halogen compound with a silane coupling agent, or simultaneously treating with a silane coupling agent with an organosilicon compound such as silicone oil Is raised.

Examples of the silane coupling agent used for the hydrophobic treatment include hexamethyldisilazane, trimethylsilane, trimethylchlorosilane, trimethylethoxysilane, dimethyldichlorosilane, methyltrichlorosilane, allyldimethylchlorosilane, allylphenyl. Dichlorosilane, benzyldimethylchlorosilane, bromomethyldimethylchlorosilane, α-chloroethyltrichlorosilane, β-chloroethyltrichlorosilane,
Chlormethyldimethylchlorosilane, triorganosilane mercaptan, trimethylsilylmercaptan, triorganosilylacrylate, vinyldimethylacetoxysilane, dimethylethoxysilane, dimethyldimethoxysilane, diphenyldiethoxysilane, hexamethyldisiloxane, 1,3-divinyltetramethyldimethyl Examples include siloxane and 1,3-diphenyltetramethyldisiloxane.

Examples of the organic silicon compound include silicone oil. As a preferred silicone oil, one having a viscosity of about 30 to 1,000 centistokes at 25 ° C. is used, and for example, dimethyl silicone oil, methylphenyl silicone oil, α-methylstyrene modified silicone oil, chlorophenyl silicone oil, fluorine modified. Silicone oil or the like is preferable.

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

If necessary, external additives other than fine silica powder may be added to the magnetic toner of the present invention.

For example, a charging aid, a conductivity-imparting agent, a fluidity-imparting agent, an anti-caking agent, a release agent at the time of heat roll fixing,
Resin fine particles or inorganic fine particles that act as a lubricant, an abrasive, etc.

The inorganic fine powder or hydrophobic inorganic fine powder to be 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) per 100 parts by weight of the magnetic toner. Is good.

To prepare a magnetic toner for developing an electrostatic image according to the present invention, magnetic powder and a vinyl-based or non-vinyl-based thermoplastic resin, a pigment or dye as a colorant, if necessary, charge control Agents, other additives, etc., are thoroughly mixed by a mixer such as a ball mill, and then melted, kneaded and kneaded using a heat kneader such as a heating roll, kneader or extruder to make the resins compatible with each other. The magnetic toner according to the present invention can be obtained by dispersing or dissolving a pigment or dye therein, cooling and solidifying, and then pulverizing and strictly classifying.

An image forming apparatus, an apparatus unit and a 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 installed in the counter direction and The latent image is reversely developed with the one-component magnetic developer 13 having magnetic toner of the developing device 1 having the developing sleeve 6 containing the magnet 15. In the developing section, an alternating bias, a pulse bias and / or a DC bias is applied between the conductive substrate of the photosensitive drum 3 and the developing sleeve 6 by the bias applying means 12. When the transfer sheet P is conveyed and reaches the transfer portion, the electrostatic transfer means 4 charges the developed image (toner) on the surface of the photosensitive drum by corona charging from the back surface of the transfer sheet P (the surface opposite to the photosensitive drum side). The image) is electrostatically transferred onto the transfer paper P. The transfer paper P separated from the photosensitive drum 3 is fixed by a heating and pressure 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 the cleaning device 14 having the cleaning blade 8. The photosensitive drum 3 after cleaning is gradually charged by 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. The non-magnetic cylindrical developing sleeve 6, which is a toner carrier, rotates so as to move in the same direction as the surface of the electrostatic image carrier in the developing section. Inside the developing sleeve 6 which is a non-magnetic cylinder, a multi-pole permanent magnet 15 (magnet roll) which is 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 the non-magnetic cylindrical surface, and the friction between the surface of the developing sleeve 6 and the magnetic toner particles gives the magnetic toner particles a negative triboelectric charge, for example. .. Further, by disposing the elastic doctor blade 9, the thickness of the developer layer is regulated to be thin (30 μm to 300 μm) and uniform, so that 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 to be non-contact. By adjusting the rotation speed of the sleeve 6, the surface speed of the sleeve is made substantially equal to or close to the speed of the electrostatic image holding surface.

The sleeve 6 and the photosensitive drum 3 in the developing section.
Alternatively, an AC bias or a pulse bias may be applied between and by the bias means 12. This AC bias is f
Is 200 to 4,000 Hz, Vpp is 500 to 3,000
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 electrostatic force on the surface of the photosensitive drum 3 holding the electrostatic image and the action of the AC bias or the pulse bias.

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

As the magnetic doctor blade 16, for example, an iron doctor blade is placed close to the cylindrical surface (interval 5
(0 μm to 500 μm), the developer layer is placed thinly (30 μm to 300 μm) and uniformly regulated by arranging it so as to face one magnetic pole position of the multi-pole permanent magnet, and the electrostatic charge image carrying in the developing section is carried out. A developer layer that is thinner than the gap between the body 1 and the developing sleeve 2 is formed so as not to contact. By adjusting the rotation speed of the developing sleeve 2, the surface speed of the sleeve is made substantially equal to or close to the speed of the electrostatic image holding surface. Instead of iron as the magnetic doctor blade 6, a permanent magnet may be used to form the opposing magnetic poles.

The electrophotographic apparatus is constructed by integrally combining a plurality of constituent elements such as the electrostatic latent image bearing member such as the above-mentioned photosensitive drum, the developing device, and the cleaning means as an apparatus unit. The unit may be configured to be detachable from the apparatus body. For example, at least one of the charging means, the developing device, and the cleaning means is integrally supported together with the photosensitive drum to form a unit, which is a detachable single unit in the main body of the apparatus, and a guide means such as a rail of the main body is used. It may be detachable.
At this time, the above-mentioned device unit may be provided with a charging means and / or a developing device.

FIG. 5 shows an embodiment of the device unit of the present invention. In this embodiment, an electrophotographic system including an image forming unit (so-called cartridge) 18 in which a developing device 1, a drum-shaped latent image carrier (photosensitive drum) 3, a cleaner 14, and a primary charger 11 are integrated. An image forming apparatus is exemplified.

In this apparatus, the image forming unit 1
When the magnetic developer 13 in the developing device 1 in 8 disappears, it is replaced with a new cartridge.

In this embodiment, the developing device 1 uses a one-component magnetic developer as the developer 13, and a predetermined electric field is formed between the photosensitive drum 3 and the developing sleeve 6 during the developing process. The distance between the photosensitive drum 3 and the developing sleeve 6 is very important in order to properly carry out.
In this embodiment, the center is 300 μm, and measurement and adjustment are performed so that 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 carrying 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 to form a thin developer layer on the developing sleeve.

The developing sleeve 6 may have any structure. Usually, it is composed of a non-magnetic developing sleeve 6 containing a magnet 15. The developing sleeve 6 may be a cylindrical rotating body as shown. It is also possible to form a belt shape that moves circularly. As its material,
It is preferable to use aluminum or SUS.

The elastic blade 9 is made of a rubber elastic body such as urethane rubber, silicone rubber or NBR; a metal elastic body such as phosphor bronze or a stainless plate; a resin elastic body such as polyethylene terephthalate or high density polyethylene. Composed of plates. 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 the 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 /
It is preferable that the contact is made in the counter direction with respect to the rotation direction of the developing sleeve 6 in cm.

When the image forming apparatus of the present invention is used as a fax machine printer, the optical image exposure is exposure for printing received data. FIG. 6 is a block diagram showing an example of this case.

The controller 611 controls the image reading section 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 via the transmission circuit 613. The 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
18 controls the printer 619. Reference numeral 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 decodes the image information and sequentially stores the image memory 616. Stored in. Then, at least one page of image is stored in the memory 616.
When it is stored in, the image of that page is recorded. CPU
617 reads the image information of one page from the memory 616 and sends the decoded image information of one page to the printer controller 618. Printer controller 618
When receiving the image information of one page from the CPU 618, the printer 61 prints the image information of the page.
Control 9

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

As described above, the image is received and recorded.

The magnetic iron oxide containing elemental silicon according to the present invention is produced, for example, by the following method.

After adding a predetermined amount of the silicic acid compound to the aqueous ferrous salt solution, an equivalent amount or an equivalent amount or more of an alkali such as sodium hydroxide is added to the iron component to prepare an aqueous solution containing ferrous hydroxide. .. The pH of the prepared aqueous solution is pH 7
Air is blown while maintaining the above (preferably pH 8 to 10), the oxidation reaction of ferrous hydroxide is performed while heating the aqueous solution to 70 ° C. or more, and seed crystals that form the core of the magnetic iron oxide particles are first generated. To do.

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

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

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

In the method for producing magnetic iron oxide by the aqueous solution method, an iron concentration of 0.5 to 2 mol / l is generally used in view of preventing the viscosity from increasing during the reaction and the solubility of iron sulfate. Generally, the thinner the concentration of iron sulfate, the smaller the particle size of the product. In addition, in the reaction, the larger the amount of air and the lower the reaction temperature, the easier the particles become.

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

[0132]

EXAMPLES The present invention will be specifically described below with reference to production examples and examples. Number of copies or% given in the examples
Indicates parts by weight or% by weight.

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%.
1.0-1.1 equivalent of caustic soda solution was mixed with iron ion to prepare an aqueous solution containing ferrous hydroxide.

The pH of the aqueous solution is adjusted to pH 7 to 10 (eg pH
While maintaining at 9), air was blown in to carry out an oxidation reaction at 80 to 90 ° C. to prepare a chiller liquid for producing seed crystals.

Then, an aqueous solution of ferrous sulfate was added to the chiller liquid so that the amount of the alkali was 0.9 to 1.2 equivalents based on the initial alkali amount (sodium component of sodium silicate and sodium component of caustic soda). PH of liquid 6-10
While maintaining the pH at 8 for example, the oxidation reaction was promoted while blowing air, the pH was adjusted at the final stage 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 crushed to agglomerate to obtain magnetic iron oxide having the characteristics shown in Table 2.

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

In the magnetic iron oxide obtained in Production Example 1, the results shown in FIG.
The content C of the silicon element derived from a silicon compound such as silicic acid, which is eluted by the alkali present on the surface C of the magnetic iron oxide particles shown in FIG. 1, is 17.9 mg / l, and the surface B of the magnetic iron oxide particles shown in FIG. Content B of the silicon compound derived from the silicon compound present in 3 is 38.8 mg / l, and the content A is 5
It was 9.7 mg / l.

[0138]

[Table 1]

Production Example 2 In Production Example 1, the content ratio of silicon element to iron element was 2.9.
A magnetic iron oxide having the characteristics as shown in Table 2 was obtained in the same manner as in Production Example 1 except that sodium silicate was added so that the content of the magnetic iron oxide became so.

Production Example 3 In Production Example 1, the content ratio of the silicon element to the iron element was 0.9.
A magnetic iron oxide having the characteristics as shown in Table 2 was obtained in the same manner as in Production Example 1 except that sodium silicate was added so that the content of the magnetic iron oxide became so.

Production Example 4 In Production Example 1, the content ratio of silicon element to iron element was 1.7.
A magnetic iron oxide having the characteristics as shown in Table 2 was obtained in the same manner as in Production Example 1 except that sodium silicate was added so that the content of the magnetic iron oxide became so.

Comparative Production Example 1 Production Example 1 except that sodium silicate was not added in Production Example 1.
Magnetic iron oxide having the characteristics shown in Table 2 was obtained in the same manner as in.

Comparative Production Example 2 100 parts by weight of the magnetic iron oxide obtained in Comparative Production Example 1 was mixed with 1.5 parts by weight of fine silicic acid powder with a Hengel mixer to obtain the characteristics shown in Table 2. A magnetic iron oxide having was obtained.

[0144]

[Table 2]

Example 1 -Styrene-2-ethylhexyl acrylate-maleic acid n-butyl half ester copolymer (copolymerization weight ratio 7.5: 1.5: 1, Mw 250,000) 100 parts-Magnetic property of Production Example 1 Iron oxide 100 parts ・ Negative charge control agent (dialkylsalicylic acid-based chromium complex) 1 part ・ Low molecular weight polypropylene 3 parts

The above mixture was melt-kneaded with a twin-screw extruder heated to 140 ° C., the cooled kneaded product was coarsely pulverized with a hammer mill, and the coarsely pulverized product was finely pulverized with a jet mill. Was classified with a fixed wall type air classifier to produce classified powder. Furthermore, the weight-average particle size (D ₄ ) is obtained by strictly classifying the obtained classified powder at the same time by strictly classifying and removing ultrafine powder and coarse powder with a multi-division classifier utilizing the Coanda effect (Elbow Jet classifier manufactured by Nittetsu Mining Co., Ltd.). 6.8 μm (particle size 12.7
A negatively chargeable magnetic toner having a content of magnetic toner particles of μm of 0.2% by weight) was obtained.

A magnetic developer was prepared by mixing 100 parts by weight of this magnetic toner with 1.2 parts by weight of hydrophobic silica fine powder treated with hexamethyldisilazane and then treated with silicone oil in 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. 5, 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 adjusted to -7.
An electrostatic latent image for reversal development is formed on the OPC photosensitive drum 3 as 00V, 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 and AC Bias (f = 1,800 Hz, Vpp =
1,600 V) and DC bias (V _DC = -500)
And (V) are applied to the developing sleeve, the electrostatic potential image is developed by reversal development while setting the bright portion potential ( _VL ) to -170V to form a magnetic toner image on the OPC photosensitive member. 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 pressure roller fixing device.

An image forming test was conducted up to 6000 sheets under a normal temperature and normal humidity environment (23.5 ° C., 60% RH) while successively replenishing the magnetic developer. Image density measured by Macbeth reflection densitometer, whiteness of transfer paper measured by reflectometer (manufactured by Tokyo Denshoku Co., Ltd.) and fog calculated by comparing solid whiteness with whiteness of transfer paper after printing, and Table 2 shows the results of dot reproducibility obtained by performing an image drawing test of the pattern 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%
The image formation test was carried out in RH). The results are shown in Table 3.

Example 2 • Styrene-n-butyl acrylate copolymer (copolymerization weight ratio 8: 2, Mw 280,000) 100 parts • Magnetic iron oxide of Production Example 60 parts • Negative charge control agent (monoazo dye-based Chromium complex)
8 parts ・ Low molecular weight polypropylene 3 parts

The above mixture was melt-kneaded in a twin-screw extruder heated to 140 ° C., the cooled kneaded product was coarsely pulverized with a hammer mill, and the coarsely pulverized product was finely pulverized with a jet mill. The obtained finely pulverized powder was subjected to air classification to obtain a negatively chargeable magnetic toner having a weight average particle diameter (D4) of 11 μm (content of magnetic toner particles having a particle diameter of 12.7 μm or more: 33% by weight).

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

This magnetic developer was supplied to the device unit (toner cartridge) of the laser beam printer LBP-8II, and an image output test was conducted in the same manner as in Example 1. The results are shown in Table 3.

Example 3 100 parts by weight of styrene-n-butyl acrylate (copolymerization weight ratio of 8: 2, Mw 300,000) 120 parts by weight of magnetic iron oxide of Production Example 3 negative charge control agent (monoazo dye-based chromium Complex) 2 parts by weight ・ Low molecular weight polypropylene 3 parts by weight

Using the above materials, a magnetic toner having a weight average particle size (D4) of 4 μm (content of magnetic toner particles having a particle size of 12.7 μm or more, 0% by weight) was obtained in the same manner as in Example 1.

100 parts by weight of the obtained magnetic toner and 1.6 parts of hydrophobic colloidal silica treated with silicone oil.
A magnetic developer was prepared by mixing 1 part by weight with a Henschel mixer.

Using this magnetic developer, a test for printing a large number of sheets up to 6000 sheets was conducted in the same manner as in Example 1. The results are shown in Table 3.

Example 4 100 parts by weight of styrene-n-ethylhexyl acrylate-n-butyl hafester maleate copolymer (copolymerization weight ratio 7.5: 1.5: 1, Mw 250,000) 100 parts by weight Magnetic iron oxide 90 parts by weight ・ Negatively charged control agent (dialkylsalicylic acid-based chromium complex) 1 part by weight ・ Low molecular weight polypropylene 3 parts by weight

Using the above materials, a magnetic toner having a weight average particle diameter (D4) of 8.5 μm (content of magnetic toner particles having a particle diameter of 12.7 μm or more 4% by weight) was obtained in the same manner as in Example 1.

100 parts by weight of the obtained magnetic toner and 1 part by weight of hydrophobic colloidal silica fine powder treated with hexamethyldisilazane and then treated with silicone oil were mixed with a Henschel mixer to prepare a magnetic developer. Prepared.

This magnetic developer was printed by a laser beam printer LBP-8II on an A4 copy paper in a vertical direction to obtain 1 image.
The image was supplied to an apparatus unit (toner cartridge) of a modified machine modified to 6 sheets / minute, and an image production test was conducted in the same manner as in Example 1. The results are shown in Table 3.

Example 5 • Styrene-n-butyl acrylate copolymer (copolymerization weight ratio 8: 2, Mw 280,000) 100 parts by weight • Magnetic iron oxide of Production Example 1 50 parts by weight • Negative charge control agent (monoazo Dye-based chromium complex) 0.
8 parts by weight ・ Low molecular weight polypropylene 3 parts by weight

Using the above materials, a weight average particle diameter of 13 μm (content of magnetic toner particles having a particle diameter of 12.7 μm or more: 45% by weight) was obtained in the same manner as in Example 1.

A magnetic developer was prepared by mixing 100 parts by weight of the obtained magnetic toner and 0.4 part by weight of a hydrophobic colloidal silica fine powder treated with silicone oil with a Henschel mixer.

This magnetic developer was supplied to a device unit (toner cartridge) of a commercially available laser beam printer LBPA404, and a multi-sheet durability test of 4000 sheets was conducted in the same manner as in Example 1. The results are shown in Table 3.

Comparative Example 1 The weight average particle size was 7 μm (particle size 12.7) 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 having a size of μm or more (0.3% by weight) was obtained. A magnetic developer was prepared in the same manner as in Example 1 using the obtained magnetic toner, and an image development test was conducted in the same manner as in Example 1 using the prepared magnetic developer.
The results are shown in Table 3.

Comparative Example 2 The weight average particle size was 8.7 μm (particle size 1) 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% by weight) was obtained. Using the magnetic toner thus obtained, a magnetic developer was prepared in the same manner as in Example 4, and an image forming test was conducted in the same manner as in Example 4 using the prepared magnetic developer. The results are shown in Table 3.

Comparative Example 3 Using the magnetic iron oxide of Production Example 1, magnetic properties were obtained in the same manner as in Example 1 and having a weight average particle diameter of 14 μm (content of magnetic toner particles having a particle diameter of 12.7 μm or more 60% by weight). A toner was obtained, a magnetic developer was prepared in the same manner as in Example 1, and an image development test was conducted in the same manner as in Example 1. The results are shown in Table 3.

As compared with the magnetic developer of Example 1, the dot reproducibility was inferior, and the toner was found to be hitch.

[0172]

[Table 3]

Evaluation method (a) Fog was calculated by the following formula. REFLECTMETER (Tokyo Electric Co., Ltd.) was used for the measurement of whiteness.

[0174]

[Outside 7]

If the fog is 1.5% or less, a good image is obtained.

(B) The dot reproducibility is 80 × shown in FIG.
An image output test was carried out using a checker pattern of 50 μm, and the sharpness of the toner image, the scattering of the toner to the non-image area, and the presence or absence of a black portion defect were evaluated by a microscope.

[0177]

According to the present invention, the magnetic iron oxide characterized by the distribution of elemental silicon has a weight average particle diameter of 13.5 μm or less, and the content of magnetic toner particles having a particle diameter of 12.7 μm or more is 50. By using the magnetic toner as a magnetic material of a magnetic toner having a large amount of magnetic toner particles having a fine particle diameter of not more than 10% by weight, environmental stability and developing characteristics of the magnetic toner can be improved.

[Brief description of drawings]

FIG. 1 is a diagram 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 explanatory view showing a specific example of an image forming apparatus (including an elastic blade) of the present invention.

FIG. 4 is a schematic explanatory view showing a specific example of an image forming apparatus (comprising a magnetic blade) of the present invention.

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

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

FIG. 7 is an explanatory diagram of a checkered pattern for testing the developing characteristics of magnetic toner.

[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 pressure 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

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] July 1, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0010

[Correction method] Change

[Correction content]

More specifically, in the conventional jumping developing method using a magnetic toner containing a magnetic material, if a repeated developing process (for example, copying) is continued for a long period of time, the developer containing the magnetic toner will be Liquidity deteriorated,
Normal frictional electrification cannot be obtained, electrification is likely to be non-uniform, fog development is likely to occur in a low temperature and low humidity environment, and a serious problem on a toner image is likely to occur. Also,
When the adhesiveness between the binder resin that constitutes the magnetic toner particles and the magnetic material is weak, the magnetic material is removed from the surface of the magnetic toner by repeated development steps, and adverse effects such as a decrease in toner image density tend to occur. There is.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] 0032

[Correction method] Change

[Correction content]

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 in the magnetic iron oxide having a dissolution rate of the iron element of up to about 20%. Ratio (B / A) x 100 (%) is 44
Is 84% (preferably 60 to 80%), and the ratio (C / A) × 100 (%) of the content C and the content A of the silicon element existing on the surface of the magnetic iron oxide particles is 10 to 10. 55%
(Preferably 25 to 40%) is one of the characteristics. (B / A) × 100 (%) is smaller than 44%,
When the silicon element is present in the central portion in an unnecessarily large amount, the production efficiency tends to deteriorate, and in addition, magnetic iron oxide may have unstable magnetic properties.

[Procedure 3]

[Document name to be amended] Statement

[Name of item to be corrected] 0033

[Correction method] Change

[Correction content]

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

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0034

[Correction method] Change

[Correction content]

On the other hand, (C / A) × 100 (%) is 10%
If it is smaller, the amount of 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, and the charge amount and volume specific resistance of the magnetic iron oxide decrease. It is easy to impair the charging stability and environmental stability of the magnetic toner.

[Procedure Amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0035

[Correction method] Change

[Correction content]

Also, (C / A) × 100 (%) is 55%
When the number is larger, 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 dispersed in the magnetic toner, and the magnetic toner characteristics are likely to be adversely affected.

[Procedure Amendment 6]

[Document name to be amended] Statement

[Name of item to be corrected] 0037

[Correction method] Change

[Correction content]

Further, in the present invention, the charge amount of magnetic iron oxide is −25 to −70 μc / g (preferably −40 to −60 μm).
c / g), and the volume resistivity of magnetic iron oxide is 5
× 10 ³ to 1 × 10 ⁸ Ω · cm (preferably 5 × 10 ⁴ to
It is preferably 5 × 10 ⁷ Ω · cm).

[Procedure Amendment 7]

[Document name to be amended] Statement

[Name of item to be corrected] 0053

[Correction method] Change

[Correction content]

Next, while maintaining the temperature at about 60 ° C. and the stirring speed at about 200 rpm, special grade sodium hydroxide is added to form a sodium hydroxide solution of about 1N, and the magnetic iron oxide concentration at this time is set to about 5 g / l. .. Initiate dissolution of silicon compounds such as silicic acid on the surface of magnetic iron oxide particles. 20 ml was sampled 30 minutes after the start of dissolution,
Filter with a membrane filter and collect the filtrate. The filtrate is quantified for silicon element by plasma emission spectroscopy (ICP).

[Procedure Amendment 8]

[Document name to be amended] Statement

[Correction target item name] 0054

[Correction method] Change

[Correction content]

The content C of elemental silicon is the unit weight of magnetic iron oxide in an aqueous sodium hydroxide solution (about 5 g of magnetic iron oxide).
/ L) corresponding to the elemental silicon concentration (mg / l).

[Procedure Amendment 9]

[Document name to be amended] Statement

[Correction target item name] 0056

[Correction method] Change

[Correction content]

Next, while maintaining the temperature at about 50 ° C. and the stirring speed at about 200 rpm, special grade hydrochloric acid or a mixed acid of hydrochloric acid and hydrofluoric acid is added to start dissolution. At this time, when hydrochloric acid is used, the magnetic iron oxide concentration is about 5 g /
l, hydrochloric acid aqueous solution is about 3N. Approximately 20m several times between the start of dissolution and the time when everything becomes transparent
l is sampled, filtered through a 0.1 μ membrane filter, and the filtrate is collected. The filtrate is analyzed by plasma emission spectroscopy (IC
According to P), the iron element and the silicon element are quantified.

[Procedure Amendment 10]

[Document name to be amended] Statement

[Correction target item name] 0061

[Correction method] Change

[Correction content]

The total content A of silicon in the magnetic iron oxide is
It corresponds to the concentration of elemental silicon (mg / l) per unit weight of magnetic iron oxide after dissolution (about 5 g / l of magnetic iron oxide).

[Procedure Amendment 11]

[Document name to be amended] Statement

[Correction target item name] 0063

[Correction method] Change

[Correction content]

As a method for measuring the contents A, B and C, (1) a sample of magnetic iron oxide is divided into two, and the content ratio of silicon element and the contents A and B are measured, while A method of separately measuring the amount C, and (2) measuring the content C of the magnetic iron oxide sample, and then using the sample after the measurement, the content B '(content B minus content C) ) And the content A ′ (the content A minus the content C), and finally calculate the contents A and B.

[Procedure amendment]

[Submission date] September 18, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0174

[Correction method] Change

[Correction content]

Fog (%) = whiteness of transfer paper (%)-whiteness of transfer paper after solid white printing (%) ───────────────────── ──────────────────────────────────

[Procedure amendment]

[Submission date] December 10, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0009

[Correction method] Change

[Correction content]

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

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takakuni Kobori, 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Hiroyuki Suematsu, 3-30-2 Shimomaruko, Ota-ku, Tokyo Within the corporation

Claims (14)

[Claims] 1. 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 the magnetic toner is 12. The content of the magnetic toner particles of 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. The ratio (B / A) × 100 of the content B of the silicon element present in the magnetic iron oxide having an iron element dissolution rate of up to 20% by weight and the total content A of the silicon element of the magnetic iron oxide is 100 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 100 to 55.
% Magnetic toner. 2. Magnetic iron oxide has a charging property of -25 to -70.
μc / g and volume resistivity value 5 × 10 ³ to 1 × 10 ⁸
The magnetic toner according to claim 1, having an Ω · cm. 3. The magnetic toner according to claim 1, wherein the magnetic iron oxide has an aggregation degree of 3 to 40%. 4. The magnetic iron oxide has a smoothness (D) of 0.2 to.
The magnetic toner of claim 1, having a 0.6. 5. The magnetic toner according to claim 1, wherein the magnetic iron oxide has a sphericity (Ψ) of 0.8 or more. 6. The magnetic toner has a weight average particle diameter of 3.5 to 1.
The magnetic toner according to claim 1, which has a thickness of 3.5 μm. 7. A magnetic developer comprising a magnetic toner containing at least a binder resin and magnetic iron oxide, and an inorganic fine powder or a hydrophobic inorganic fine powder, wherein the magnetic toner has a weight average particle diameter of 13.5 μm. In the particle size distribution of the magnetic toner, the particle size is 12.7.
The content of the magnetic toner particles of 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. The ratio (B / A) × 100 of the content B of the silicon element present in the magnetic iron oxide having an iron element dissolution rate of up to 20% by weight and the total content A of the silicon element of the magnetic iron oxide is 100 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 100 to 55.
% Magnetic developer. 8. The magnetic developer according to claim 7, wherein the hydrophobic inorganic fine powder is a hydrophobic colloidal silica fine powder. 9. A latent image carrier for carrying a latent image and a developing device for developing the latent image, the developing device comprising:
A developer container for accommodating the developer, a developer carrier for carrying and transporting the developer in the developer container from the developer container to a developing area facing the latent image carrier, and the developer carrier And a regulation blade for regulating the developer carried and conveyed by the device to a predetermined thickness to form a thin developer layer on the developer carrying member, wherein the developer is a binder resin and A magnetic toner containing at least magnetic iron oxide, the magnetic toner having a weight average particle size of 13.5 μm or less, and containing magnetic toner particles having a particle size distribution of 12.7 μm or more in the particle size distribution of the magnetic toner. The amount of the magnetic iron oxide is not more than 50% by weight, the content of silicon element in the magnetic iron oxide is 0.5 to 4% by weight based on the iron element, and the iron element is dissolved in the magnetic iron oxide. Content of elemental silicon present up to 20% by weight and the magnetic oxidation The ratio of the total content A of silicon element of (B / A) × 100 is 44 to 84%, the content of silicon element present in the magnetic iron oxide surface C
And the content A (C / A) × 100 is 10 to 55%
A device unit characterized by: 10. The apparatus unit according to claim 9, wherein the developer contains a magnetic toner and a hydrophobic colloidal silica fine powder. 11. A latent image carrier for carrying a latent image and a developing device for developing the latent image, the developing device comprising a developer container for accommodating a developer, and the developing device. In an image forming apparatus having a developer carrier that carries and conveys the developer in the developer container from the developer container to a developing area facing the image carrier, the developer contains a binder resin and magnetic iron oxide. The magnetic toner contains at least a magnetic toner having a weight average particle diameter of 13.5 μm or less, and in the particle size distribution of the magnetic toner, the content of magnetic toner particles having a particle diameter of 12.7 μm or more is 50% by weight. % Or less, and the magnetic iron oxide has a content A of silicon element of the magnetic iron oxide.
Is 0.5 to 4% by weight based on the iron element, the content B of the silicon element present in the magnetic iron oxide having a dissolution rate of the iron element of up to 20% by weight, and the total of the silicon elements of the magnetic iron oxide. The ratio (B / A) × 100 with the content A is 44 to 84%, and the content C of the silicon element present on the surface of the magnetic iron oxide.
And the content A (C / A) × 100 is 10 to 55%
An image forming apparatus comprising: 12. The image forming apparatus according to claim 11, wherein the developer contains a magnetic toner and a hydrophobic colloidal silica fine powder. 13. A facsimile device having a receiving means for receiving image information from an electrophotographic device and a remote terminal, the electrophotographic device for developing an image carrier for carrying a latent image and the latent image. And a developer container for accommodating the developer, and the developer in the developer container is carried from the developer container to a developing area facing the image carrier and conveyed. And a developer carrier for controlling the developer carried by the developer carrier and regulated to a predetermined thickness to form a thin developer layer on the developer carrier. A blade, the developer has a magnetic toner containing at least a binder resin and magnetic iron oxide, the magnetic toner has a weight average particle size of 13.5 μm or less, and a particle size of the magnetic toner. Magnetic toner with a particle size of 12.7 μm or more in distribution -The content of particles is 50 wt% or less, the content of silicon element of the magnetic iron oxide is 0.5 to 4 wt% based on the iron element, the magnetic iron oxide The ratio (B / A) × 100 of the content B of the silicon element existing up to 20% by weight of the iron element and the total content A of the silicon element of the magnetic iron oxide is 44 to 84%, Content C of elemental silicon present on the surface of the magnetic iron oxide
And the content A (C / A) × 100 is 10 to 55%
Facsimile machine characterized in that 14. The facsimile apparatus according to claim 13, wherein the developer contains a magnetic toner and a hydrophobic colloidal silica fine powder.