JPH11153882A - Magnetic toner and image forming method - Google Patents

Abstract

(57) [Problem] To provide a magnetic toner excellent in developability and durability. SOLUTION: In a magnetic toner having magnetic toner particles containing at least a binder resin and a magnetic material, the magnetic material has an electronegativity of 1.0 to 2.5 after a third cycle of a long-period element periodic table. Is a magnetic iron oxide having the element α of 0.10 to 4.00% by weight, and the dissolution rate S ₁ of the element α having the iron element dissolution rate of 0 to 20% in the magnetic material is 10% or more and less than 44% And the solubility S ₂ of the element α having an iron element solubility of 80 to 100% is 5% or more and less than 30%, and the magnetic material contains (i) 60% by number or more of multinucleated magnetic iron oxide particles. Or (ii) one or more selected from the group consisting of magnetic iron oxide particles in which the ridges of the hexahedron are planar polyhedrons and magnetic iron oxide particles in which the ridges of the octahedron are planar polyhedrons, or A combination of two types of magnetic iron oxide particles and a multi-nuclear magnetic iron oxide particle It was about a magnetic toner which is characterized in that it comprises 60% by number or more to.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a magnetic toner for developing in an image forming method such as electrophotography, electrostatic recording, and toner jet, and an image forming method using the magnetic toner.

[0002]

2. Description of the Related Art Various developing methods have been put to practical use in electrophotographic developing methods. Among them, magnetic toners have been used because they have few troubles in a developing device having a simple structure, have a long life, and are easy to maintain. Is preferably used. In such a developing method, the quality of image formation largely depends on the performance of the magnetic toner. Further, in a magnetic toner, the toner is made magnetic by including a magnetic material. For these reasons, the magnetic material affects the developability and durability of the magnetic toner, and various proposals have been made for the magnetic material.

For example, Japanese Patent Application Laid-Open No. Hei 8-101529 proposes a magnetic material containing silicon and zinc, and is disclosed in Japanese Patent Application Laid-Open Nos. 7-175262, 5-72801, and 62-278131. No., JP-A-61-3
Japanese Patent Publication No. 4070, Japanese Patent Application Laid-Open Nos. Hei 8-25747, Hei 9-59024, and Hei 9-59025 propose magnetic materials containing silicon. JP-A-5-281778 proposes a magnetic substance containing silicon and aluminum, and JP-A-5-345616 proposes a magnetic toner using a magnetic substance containing magnesium. Have been. Although good developability has been obtained for each case, when applied to a positively charged magnetic toner, when applied to a high-speed machine, when replenishment is repeated and the copy volume becomes extremely large for a long time, or when an amorphous silicon drum is used. When used, or when reversal development is performed at a low potential with a digital machine, further improvement in developability and durability is expected.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a magnetic toner having excellent developability and durability.

An object of the present invention is to provide a magnetic toner capable of obtaining good developability and durability in an amorphous silicon drum.

Another object of the present invention is to provide a magnetic toner capable of obtaining good developability in low potential development.

Another object of the present invention is to provide a magnetic toner capable of obtaining good developability and durability in a system for developing at high speed.

Another object of the present invention is to provide a magnetic toner capable of obtaining good developability in a positively chargeable toner.

An object of the present invention is to provide an image forming method using the above magnetic toner.

[0010]

Specifically, the present invention provides:
In a magnetic toner having magnetic toner particles containing at least a binder resin and a magnetic material, the magnetic material has an electronegativity of 1.0 to 2.3 after the third cycle of the long-period element periodic table.
Is a magnetic iron oxide having an element α of 0.15 to 4.00% by weight, and an iron element dissolution rate of 0 to 2 in the magnetic material.
0% element α dissolution rate S ₁ is 10% or more and less than 44%, and iron element dissolution rate 80% to 100% element α dissolution rate S ₂
Is not less than 5% and less than 30%, and the magnetic material has (i) 60% by number or more of magnetic iron oxide particles in a binuclear shape;
Or (ii) one or two kinds of magnetism selected from the group consisting of magnetic iron oxide particles having hexahedral ridges having planar polyhedrons and magnetic iron oxide particles having octahedral ridges having planar polyhedrons. The present invention relates to a magnetic toner having a total of 60% by number or more of iron oxide particles and dinuclear magnetic iron oxide particles.

Further, the present invention provides an image forming method comprising at least a step of forming an electrostatic charge image on a latent image carrier and a developing step of developing the electrostatic charge image with a magnetic toner. The toner has magnetic toner particles containing a resin and a magnetic material, and the magnetic material has an electronegativity of 1.0 to 2.5 after the third cycle of the long-period type periodic table of elements.
Is a magnetic iron oxide having an element α of 0.10 to 4.00% by weight, and an iron element dissolution rate of 0 to 20 in the magnetic material.
% Of dissolution rate S ₁ elements alpha is less than 10% or more 44%, dissolution rate of iron element dissolution ratio 80% to 100% of the elements alpha S ₂
Is not less than 5% and less than 30%, and the magnetic material has (i) 60% by number or more of magnetic iron oxide particles in a binuclear shape;
Or (ii) one or two kinds of magnetism selected from the group consisting of magnetic iron oxide particles having hexahedral ridges having planar polyhedrons and magnetic iron oxide particles having octahedral ridges having planar polyhedrons. The present invention relates to an image forming method comprising 60% by number or more in total of iron oxide particles and dinuclear magnetic iron oxide particles.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The magnetic material of the magnetic toner of the present invention is magnetic iron oxide, and the element α exists in a form to be taken into the magnetic iron oxide. In the present invention, by containing the element α from the surface to the center in the crystal particles of the magnetic iron oxide, it is possible to balance the magnetic properties of the magnetic material, increase the image density, suppress image fog, and reduce the crystal particle surface. To control the electrical characteristics and improve the charging stability. Furthermore, in order to improve the durability, the magnetic material is a dinuclear magnetic iron oxide particle, or a magnetic iron oxide particle having a hexahedral or octahedral ridge and a polynuclear magnetic iron oxide particle and a polynuclear magnetic iron oxide particle. This is achieved by containing 60% by number or more.

In order to further exhibit this effect, it is preferable that the number of double-nucleated particles is 50% by number or more, particularly 60% by number or more.

Here, the dinuclear magnetic iron oxide particles are those having a shape in which crystals are grown from a plurality of particle nuclei, or those in which small particle nuclei are formed on a parent particle and are crystal-grown. It has a convex portion formed of a ridge line. For example, the outline shown in FIG. 1 is exemplified. The hexahedron or the octahedron whose polyhedron has a planar ridge is, for example, an outer contour shown in FIG.

The preferred form of the multi-nucleated magnetic iron oxide particles is as follows. Two arbitrary vertices on the particle are selected, and a straight line connecting the two points is assumed. At this time, a shape in which the surface of the magnetic material particle is in the direction of the particle center with respect to this straight line and has a side surface which becomes the particle concave portion is regarded as a multinucleus shape. The multi-nuclear shape refers to a shape having at least one or more such concave portions. For example, a shape represented by the three-dimensional view shown in FIG. 3 or FIG. 4 is exemplified. Further, the distance from the straight line connecting any two points to the surface of the perpendicular drawn down on the particle surface is 1.0 to the maximum diameter of the particle.
50.0%, preferably 2.0 to 40.0%
Is still more preferable, and it is more preferable that it is 3.0 to 30.0%, and it is especially preferable that it is 4.0 to 20.0%. Explaining with reference to FIG. 4, this value is obtained by setting the intersection point of the perpendicular line l and the particle surface from the line segment ab connecting any vertices a and b to the particle surface as c, and the perpendicular line l and the line segment ab
Is the value obtained by measuring the distance of the line segment cd and determining the ratio on the basis of the maximum diameter of the particles, where d is the intersection point of.

If the above conditions are satisfied in the outline on the two-dimensional projected view as shown in FIG. 5, the shape of the present invention is sufficiently satisfied.

The preferred form of the magnetic iron oxide in which the ridges of the hexahedron or octahedron are planar has the following shape. When a polyhedron containing magnetic iron oxide particles is extrapolated, the polyhedron becomes a hexahedron or an octahedron. For example, those illustrated in the three-dimensional views shown in FIGS. In FIG. 6, a surface X is a side surface, and a surface Y is a surface having a ridge line portion, which is a flat surface or a curved surface. Also with reference to FIG. 7, when the ridge portion of the hexahedron or octahedron described polyhedron is planar, on the basis of the polyhedron 1 having a side X ₁ (FIG. 7a),
Extrapolating a polyhedral 2 having side X ₂ (Figure 7b). In the polyhedron having a planar ridge line portion of the hexahedron or octahedron according to the present invention, the extrapolated polyhedron 2 (FIG. 7c) is a hexahedron or octahedron.

The magnetic iron oxide particles having such a shape have very good dispersibility, can produce uniform toner particles, can be sufficiently dispersed in a binder resin even with a small kneading share, and have a wide range of material selection. This not only improves the electrophotographic characteristics but also increases the production stability. This is because the apexes and ridge lines of the particles are not sharp, so that the particles are easily separated from each other, have less cohesiveness, and can be uniformly dispersed in the binder resin. In addition, such magnetic iron oxide particles have irregularities on the surface of the particles, have many surfaces and ridges, and have an appropriate angle. Since it is also fixed above, it can be prevented from falling off the magnetic toner particles. further,
Due to these shapes, the surface can be exposed on the surface of the magnetic toner particles, so that the effect of adjusting the charge of the magnetic toner particles can be more exerted, the fluidity of the magnetic toner can be increased, and the developing property can be stabilized in high-speed development. Greatly contributes to Incidentally, hexahedral particles, octahedral particles and spherical particles are 4
Although it may be contained at less than 0% by number, the content is preferably 20% by number or less, more preferably 10% by number or less. When the number of spherical particles increases, the number of free magnetic particles detached from the magnetic toner particles increases, making it easier to scrape the photosensitive drum, and when the number of hexahedral or octahedral particles increases, the exposure of magnetic iron oxide particles on the surface of the magnetic toner particles peaks. It is difficult to obtain a charge adjusting effect and a fluidity improving effect due to exposure.

In order to improve the required magnetic and electrical properties, atoms other than iron atoms are incorporated into the magnetic iron oxide. It is preferable that this atom is present in the crystal lattice of the magnetic iron oxide in a state where the atom is replaced with an iron atom. As an atom other than the iron atom, an element α having an M shell or more from the third period of the periodic table is preferably used. You. The element α is preferably a third period, fourth period, or fifth period element, and particularly preferably a third period or fourth period element. Since the element α preferably has an electronegativity close to that of the iron element, the electronegativity of the element α is 1.0 to 2.5, preferably 1.2 to 2.3, and more preferably 1 to 2.3. 0.5 to 2.1. The element α is preferably a typical element, among which a P-block element is preferable, and a group IIIB, IVB, or VB group element is particularly preferable. Specifically, preferred elements α include Si, Al, P, Mg, Ti, V, C
r, Mn, Co, Ni, Cu, Zn, Ga, Ge, Z
r, Sn or Pb, more preferably Si, A
1, P, V, Cr, Co, Ni, Cu, Zn, Ga, G
e, Zr, Sn or Pb, particularly preferred element α is Si, Al or P, with Si being most preferred.

The element α incorporated in the magnetic iron oxide is 0.10 to 4.00% by weight based on the magnetic material. By being within this range, it becomes possible for the magnetic iron oxide to preferably exhibit the shape of the magnetic material characteristic of the present invention. Also, various magnetic characteristics, electrical characteristics, and physical characteristics can be preferably exhibited by the distribution of the element α as described below, and excellent electrophotographic characteristics can be imparted to the magnetic toner. Can be. With such a content, the element α
By containing, it is possible to prepare a magnetic material for constituting a magnetic toner having excellent developability under severe conditions and excellent durability. When the content of the element α exceeds 4.00% by weight, the surface of the polyhedron becomes more curved and spherical. In this case, the magnetic material is easily released from the magnetic toner particles. When free magnetic material is generated, unevenness occurs in the method of shaving the drum when used for a long period of time, and the surface potential of the drum varies. Above all, when an amorphous silicon drum is used, low-potential development is often performed, and when reversal development of a digital latent image is performed, the potential difference becomes particularly small, and image density unevenness tends to occur. In addition, excessive discharge tends to occur, and the image density under high humidity tends to decrease due to an insufficient amount of charge of the magnetic toner. When the content of the element α is less than 0.10% by weight, the magnetic toner is apt to be excessively charged, and the charge balance between the magnetic toner particles becomes non-uniform and fog increases. Preferably, the content is 0.15 to 3.00% by weight, so that the charging can be further stabilized and the developing property can be stabilized. The content is more preferably 0.20 to 2.50% by weight, and an image having a higher image density and less fog can be obtained. Particularly preferably, it is 0.50 to 2.00% by weight.

Further, the magnetic material preferably contains the element α in any part, and the solubility S ₁ of the element α having a dissolution rate of iron element of 0 to 20% is 10% or more and less than 44%. Elemental dissolution rate S ₂ of element α of 80 to 100% is 5
% Or more and less than 30%. Such a magnetic substance has good wettability and affinity with the binder resin, and the magnetic substance is well fixed even on the surface of the magnetic toner particles. Defective and chipping of the cleaning blade can be prevented well. In particular, when an amorphous silicon drum is used, these effects are remarkable.

When S ₁ is 10% or more and less than 44%, the residual magnetization can be made relatively small and a high image density can be obtained. In addition, binuclear particles are easily formed, which contributes to improvement in dispersibility and adhesion, thereby obtaining excellent durability. In some cases, the surface of the magnetic toner particles may have an oxide of the element α in an appropriate amount, and when the surface of the magnetic toner particles is exposed from the surface, the charge adjusting effect works effectively. In addition, the toner particles can maintain toner properties and contribute to the stabilization of charging of the toner particles, so that the development stability over time can be obtained.

When S ₂ is 5% or more and less than 30%, the magnitude of the saturation magnetization can be maintained, the excessive decrease in the residual magnetization can be prevented, and the ratio of the residual magnetization to the saturation magnetization can be maintained. Fog can be suppressed while maintaining image density. Further, since the magnetic characteristics of each magnetic particle are also stabilized, the magnetic characteristics within the toner particles and between the toner particles are also uniformly stabilized, so that only specific particles are not selectively developed. Also, the variation in the particle size of the magnetic material particles is reduced,
It contributes to good dispersibility and provides excellent durability stability.

The magnetic toner of the present invention in which S ₁ and S ₂ satisfy the above conditions is particularly effective in low potential development such as reversal development.

When the dissolution rate S ₁ is 44% or more, the oxide of the element α on the surface of the magnetic particles increases, so that a specific shape cannot be maintained, and drum scraping due to separation of the magnetic material occurs. In addition, when the surface area per unit weight of the magnetic material increases, the release of triboelectric charge increases, the charge retention is reduced, and the magnetic toner is repeatedly supplied and used or applied to a positively chargeable toner. For example, image defects such as uneven image density, fogging, and reduced density are likely to appear. Further, the ratio of the residual magnetization to the saturation magnetization decreases, and fog increases in low potential development. In addition, the wettability with the binder resin is reduced, and the magnetic substance is likely to fall off from the magnetic toner particles. If dissolution rate S ₁ is less than 10%, the ratio becomes large relative to the saturation magnetization of the residual magnetization, it is difficult to increase the image density at a low potential development. Further, it is difficult to form multinucleated particles, the dispersibility in the binder resin is reduced, and the adhesion to the binder resin is also reduced. If dispersion failure occurs, the image density tends to decrease during durability, and fog increases. The dissolution rate S ₁ is preferably from 15 to 42%, and in this case, the balance between the durability of the drum and the developability is easily achieved. More preferably, 20
-40%, which makes it possible to obtain sharper, higher quality images with excellent resolution.

When the dissolution rate S ₂ is 30% or more, the abundance of the element α in the vicinity of the surface of the magnetic particles decreases, and it becomes difficult to form polyhedral particles or polynuclear particles having planar ridges,
Dispersibility in the binder resin decreases. When dispersion failure occurs, the image density tends to decrease due to durability. Further, the content of the element α in the vicinity of the surface of the magnetic particles tends to vary from one magnetic particle to another, which causes instability of the charging property and has an adverse effect such as generation of fog. On the other hand, when the dissolution rate S ₂ is less than 5%, the size of the magnetic particles is not uniform, and tends to be reddish or the magnetic characteristics are apt to vary, making it difficult to produce uniform magnetic toner particles. And developability is also reduced. Dissolution rate S
₂ is preferably 5% or more and less than 25%, in which case the degree of blackness is more stable, and the change in development characteristics due to durability is small. More preferably, the dissolution rate S ₂
By being 10% or more and less than 20%, it can be more suitably applied to a high-speed development using an amorphous silicon drum or the like and a high durability machine.

In addition, it is preferable that the dissolution rate S ₁ of the element α and the dissolution rate S ₂ of the element α satisfy S ₁ ≧ S _2. In particular, the developability can be improved particularly effectively in the case of a positively chargeable toner in which the chargeability is hardly balanced.

Usually, the binder resin used for the toner is negatively chargeable. In the case of a positively chargeable toner, a positively chargeable charge control agent is dispersed in a binder resin to obtain positively triboelectrically charged toner particles. When such a toner is frictionally charged, there are portions which are positively charged in total but negatively charged microscopically. This is a cause of non-uniform charging, causing toner particles with an unbalanced charging to be present, which may cause fogging toner, cause a reduction in density, or cause a trigger for selective development. is there. The magnetic material of the present invention is capable of exposing the surface to alleviate these non-uniform charges and making the positive charges uniform and stable. Therefore, the magnetic material of the present invention is preferably used for a positively chargeable toner.

Further, the dissolution rate S ₃ obtained by converting the dissolution rate of the element α having an iron element dissolution rate of 20% to 80% per 20% of the iron element dissolution rate is preferably 10% or more and less than 25%. Since the change in the proportion of the element α becomes smoother, the homogenization of the magnetic material is promoted, and the magnetic characteristics are more stabilized for each particle, so that the magnetic characteristics for each magnetic toner particle are stabilized. As a result, selective development is suppressed, and a highly durable magnetic toner can be obtained.

Further, since the element α is present in such a ratio, the coercive force is stabilized and may be excessively large.
Further, the size does not decrease, and both fog suppression and high image density can be achieved. In addition, polyhedral particles and hexanuclear particles having hexahedral or octahedral ridges in a planar shape are likely to be formed, work to improve dispersibility and adhesion, and stabilize the charge and improve fluidity when the surface is exposed. The effect is exhibited, and excellent developability and durability stability are obtained. If S ₃ is less than 10%, the coercive force becomes small, fogging becomes easy, and spherical particles increase, so that the photosensitive drum may be abraded. When S ₃ is 25% or more, the coercive force increases and the image density decreases, and hexahedral and / or octahedral particles increase, making it difficult to obtain a charge adjusting effect and making it impossible to expect a fluidity improving effect.

Further, in the dissolution rate S ₁ , the dissolution rate S ₂ and the dissolution rate S ₃ , it is preferable that S ₁ > S ₂ , S ₁ ≧ S ₃ and S ₃ ≧ S ₂ to stabilize the particle size, The generation of a polyhedron in which the ridges of the hexahedron or octahedron are planar is promoted,
Improvements in developability and durability are achieved, and a uniform action due to charge relaxation works, and the effect is particularly great for positively chargeable toner.

It is preferable that the oxide of the element α is present on the surface of the magnetic particles, and the amount of the element α present on the surface is 0.01 to 1.00% by weight based on the magnetic iron oxide. The content is preferably 0.02 to 0.75% by weight, and more preferably 0.03 to 0.50% by weight. In particular, the content is preferably 0.05 to 0.50% by weight or less. Further, when the element α present on the surface of the magnetic iron oxide particles is 2 to 25% by weight, preferably 4 to 20% by weight of the content of the element α contained in the whole magnetic iron oxide, retention of charge and leakage And acts as a charge buffer for magnetic toner particles, suppresses the generation of reversal charged particles, reduces the amount of toner flying to the reversal portion, and reduces fog. When the element α present on the surface of the magnetic iron oxide particles is less than 2% by weight, the charge retention ability tends to be superior, and when it is more than 25% by weight, the charge leakage ability tends to be superior. It is good to balance.

Further, the second and third periodic tables are provided on the surface of the magnetic material.
It is a preferred embodiment that it is selected from Group 4 and 5 and forms an amphoteric oxide or an amphoteric hydroxide or a mixture thereof, and has an element β different from the element α. Element β
Is 0.01% by weight or more and less than 2.00% by weight on the basis of magnetic material, the environmental stability (that is, under low humidity,
(A difference in developability under high humidity) can be improved. When the content of the element β is less than 0.01% by weight, the effect is small, and when the content is 2.00% by weight or more, the fluidity is reduced and the durability may be adversely affected.
Preferred elements are B, Al, Si, Cd, Ga,
In, Ge, Sn, Pb, As, Sb or Bi,
Particularly preferred is B, Al or Si.

The magnetic material has a number average particle size of 0.05 to
0.50 μm is preferred, and more preferably 0.08 to 0.40
μm, particularly 0.10 to 0.30 μm
Are preferred. With these average particle sizes, uniform dispersibility can be obtained. The BET specific surface area of the magnetic material is 5.0 to 2
Those having a flow rate of 0.0 m ² / g are preferably used, more preferably 6.0 to 15.0 m ² / g, and particularly preferably 8.0.
When it is １12.0 m ² / g, the environmental stability of development is improved.

The magnetic properties of the magnetic material are as follows.
5~100Am preferably has a ² / kg, more preferably 80~95Am ² / kg, particularly preferably 85
When it is ９０90 Am ² / kg, generation of fogging can be favorably suppressed. The residual magnetization is 5.0 to 12.0 Am ² / kg
And more preferably 6.0 to 11.0 Am ² /
kg, particularly preferably 7.0 to 10.0 Am ² /
kg, so that a high image density can be obtained. Those having a coercive force of 5.0 to 10.0 kA / m are preferably used, and more preferably 5.5 to 9.0 kA / m.
Particularly preferably, when it is 6.0 to 8.5 kA / m, the digital latent image can be developed faithfully. Also, increase the image density,
In order to reduce fog, the ratio σr / σs of the residual magnetization (σr) to the saturation magnetization (σs) is preferably 0.070 to 0.125, more preferably 0.080 to 0.115, and particularly preferably 0.085. ０．１0.110. Each magnetic property is a value measured under a magnetic field of 795.8 kA / m. The mixing ratio of these magnetic materials is preferably 20 to 200 parts by weight, more preferably 40 to 150 parts by weight, and even more preferably 50 to 120 parts by weight based on 100 parts by weight of the binder resin. If the amount is less than 20 parts by weight, it is difficult to balance the magnetic characteristics and charging characteristics of the toner.
Fogging increases and the charge becomes excessive, causing troubles under low humidity, making it difficult to obtain sufficient coloring power. Also, when the amount exceeds 200 parts by weight, it is difficult to balance the magnetic characteristics and the charging characteristics of the toner, and a decrease in image density and image quality are observed. Property is difficult to obtain.

(1) Content of Element α : Element α in Magnetic Material
Is determined by a fluorescent X-ray analyzer SYSTEM3080.
(Manufactured by Rigaku Denki Kogyo Co., Ltd.) using JIS K011
9 Measured by performing X-ray fluorescence analysis according to “General rules for X-ray fluorescence analysis”. The content is based on the magnetic material.

(2) Dissolution rate of iron element and dissolution of element α
Ratio: In the present invention, the dissolution rate of the iron element of the magnetic iron oxide and the dissolution rate S of the element α 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 45 to 50 ° C. About 25 g of the magnetic substance slurried with about 400 ml of deionized water is added to a 5 liter beaker together with the deionized water while washing with about 300 ml of 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 concentration of the aqueous hydrochloric acid solution is about 3 mol / l. From the start of dissolution, about 10 ml is sampled 10 times until all the magnetic iron oxides are dissolved and become transparent, filtered with a 0.1 μm membrane filter, and the filtrate is collected. The filtrate is quantified for iron element and element α by plasma emission spectroscopy (ICP).

The iron element dissolution rate and the element α dissolution rate for each sample are calculated by the following equations.

[0040]

[Outside 1]

[0041]

[Outside 2]

A dissolution rate curve as shown in FIG. 10 is drawn from the dissolution rates of the iron element and the element α for each sample, and the following numerical values are derived from the curve.

The dissolution rate S ₁ is the dissolution rate of the element α from 0 to 20% of the iron element dissolution rate. That is, the iron element dissolution rate 2
It corresponds to the dissolution rate of element α at 0%.

The dissolution rate S ₂ is 80 to 100 for the elemental dissolution rate of iron.
% Of the element α. That is, it corresponds to a value obtained by subtracting the solubility of the element α at the iron element solubility of 80% from the solubility of the element α at the iron element solubility of 100%.

The dissolution rate S ₃ is determined by the iron element dissolution rate of 20 to 80%.
Is calculated by converting the dissolution rate of the element α to the iron element dissolution rate of 20%. That is, it corresponds to 1/3 of the value obtained by subtracting the solubility of element α at a solubility of 20% of iron from the solubility of element α at a solubility of 80% of iron.

(3) Particle Size and Shape of Magnetic Material : Using an electron microscope H-700H (manufactured by Hitachi Ltd.),
The image is photographed at a magnification of 0000 times, and the printing magnification is 2 times, and the final magnification is 100,000 times. Thereby, 0.03μ
100 particles of m or more are randomly selected, the maximum length (μm) of each particle is measured, and the average is defined as the number average particle size.

Further, electron microscopes H-700H and S-4
The image is taken at a magnification of 100,000 times using 700, and the printing magnification is set to 2 times, and the final magnification is set to 200,000 times. In this way, 100 particles of 0.05 μm or more are randomly selected, the shape of each particle is observed, and the existence ratio (number%) of particles having each shape is obtained. The depth of the largest concave portion of the magnetic substance having a multinuclear shape was measured for particles determined to have a multinuclear shape in the above measurement, and the line cd was taken as schematically shown in FIG. Minute c
It is determined as a ratio (%) of the maximum value of each particle to the maximum particle diameter of d. Table 1 shows the average value of the measured particles.

In the measurement of the particle size of the magnetic material and the observation of the shape, if necessary, a transmission electron microscope (T
EM) H-700H, H-800, H-7500 (all manufactured by Hitachi, Ltd.) or scanning electron microscope (SEM) S
-800 or S-4700 (both manufactured by Hitachi, Ltd.) and photographed at 20,000 to 200,000 times,
The sample can be observed at an arbitrary magnification of 10 times as the baking magnification.

(4) Content of element α on the surface of the magnetic material: 250 ml of ion-exchanged water and 20 g of a sample are placed in a 300 ml poly container and thoroughly stirred with a homomixer to prepare a slurry. 200 ml of this slurry and 2 mol / l NaO
200 ml of the H solution is placed in a 1-liter stainless steel container, and the temperature is raised to 40 ° C. while stirring and maintained for 30 minutes. Thereafter, the slurry is filtered and washed with 500 ml of pure water. Dry the filtered cake at 60 ° C. for at least 8 hours. After drying,
The content of the element α in the cake filtered by the method (1) is determined. Element α in the sample before mixing with ion-exchanged water
Is determined as the content of the element α on the surface of the magnetic material, and the content is calculated based on the magnetic material.

(5) Determination of element β: The same operation as in the above (4) is performed, and the content is determined based on the magnetic substance.

(6) BET Specific Surface Area : The BET specific surface area 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.

(7) Magnetic Properties of Magnetic Body : The magnetic properties of the magnetic body were measured under an external magnetic field of 795.8 kA / m using a “vibrating sample magnetometer VSM-3S-15” (manufactured by Toei Kogyo Co., Ltd.). It is the value measured in.

As the binder resin used in the magnetic toner of the present invention, the following polymers can be used.

For example, polystyrene; styrene-substituted homopolymers such as poly-p-chlorostyrene and polyvinyltoluene; styrene-p-chlorostyrene copolymer, styrene-vinyltoluene copolymer, styrene-vinylnaphthalene copolymer Styrene-acrylic acid ester copolymer, styrene-methacrylic acid ester copolymer, styrene-α-chloromethyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-vinylmethyl ether copolymer, styrene- Styrene copolymers such as vinyl ethyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-acrylonitrile-indene copolymer; polyvinyl chloride, Phenolic resin, natural modification Phenol resins, natural resin modified maleic acid resins, acrylic resins, methacrylic resins, polyvinyl acetate, silicone resins, polyester resins, polyurethane, polyamide resins, furan resins, epoxy resins,
Xylene resin, polyvinyl butyral, terpene resin,
Coumarone indene resin, petroleum resin and the like can be mentioned.
Preferred binder resins include styrene copolymers and polyester resins.

As comonomers for the styrene monomer of the styrene copolymer, for example, acrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, dodecyl acrylate, octyl acrylate, acrylic acid-
Monocarboxylic acid having a double bond such as 2-ethylhexyl, phenyl acrylate, methacrylic acid, methyl methacrylate, ethyl methacrylate, butyl methacrylate, octyl methacrylate, acrylonitrile, methacrylonitrile, acrylamide or a substituted product thereof; Dicarboxylic acids having a double bond such as maleic acid, butyl maleate, methyl maleate, and dimethyl maleate and substituted products thereof; vinyl esters such as vinyl chloride, vinyl acetate, and vinyl benzoate; Ethylene-based olefins such as propylene and butylene; vinyl ketones such as vinyl methyl ketone and vinyl hexyl ketone; bi-ethylenes such as vinyl methyl ether, vinyl ethyl ether and vinyl isobutyl ether Ethers, and the like. These vinyl monomers are used alone or in combination of two or more.

The styrene-based polymer or styrene-based copolymer may be cross-linked, or may be a mixed resin.

As a crosslinking agent for the binder resin, a compound having two or more polymerizable double bonds may be mainly used. For example, aromatic divinyl compounds such as divinylbenzene and divinylnaphthalene; carboxylic esters having two double bonds such as ethylene glycol diacrylate, ethylene glycol dimethacrylate and 1,3-butanediol dimethacrylate; divinylaniline And divinyl compounds such as divinyl ether, divinyl sulfide and divinyl sulfone; and compounds having three or more vinyl groups. These crosslinking agents are used alone or as a mixture.

As a method for synthesizing the styrenic copolymer, any of a bulk polymerization method, a solution polymerization method, a suspension polymerization method and an emulsion polymerization method may be used.

In the bulk polymerization method, a low molecular weight polymer 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 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 polymer having a maximum molecular weight in a molecular weight range of 5,000 to 100,000 in the chromatogram of C.

As the solvent used in the solution polymerization method, xylene, toluene, cumene, cellosolve acetate, isopropyl alcohol, benzene and the like are used. In the case of a styrene monomer mixture, xylene, toluene or cumene is preferred. It is appropriately selected depending on the polymer to be polymerized.

The reaction temperature varies depending on the solvent used, the initiator and the polymer to be polymerized.
It is good to carry out at ° C. The solution polymerization is preferably carried out with 30 to 400 parts by weight of the monomer per 100 parts by weight of the solvent.

Further, it is preferable to mix another polymer in the solution at the end of the polymerization, and several types of polymers can be mixed well.

Further, as a polymerization method for obtaining a high molecular weight polymer or a crosslinked polymer having a maximum value of molecular weight in a region having a molecular weight of 100,000 or more in a GPC chromatogram,
Emulsion polymerization and suspension polymerization are preferred.

Among them, the emulsion polymerization method is a method in which a monomer (monomer) almost insoluble in water is dispersed as small particles in an aqueous phase 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.
Further, the reason is that the polymerization process is relatively simple, and that 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. This is advantageous as compared with other methods as 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 take out the polymer. Therefore, suspension polymerization is a simple method.

In 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 polymerization initiator used and the target polymer. As the kind of the initiator, any one which is insoluble or hardly soluble in water can be used.

Examples of the polymerization initiator used in these polymerization methods include t-butylperoxy-2-ethylhexanoate, cumin perpivalate, t-butylperoxylaurate, benzoyl peroxide, lauroyl peroxide, Octanoyl peroxide, di-t
-Butyl peroxide, t-butylcumyl peroxide, dicumyl peroxide, 2,2′-azobisisobutyronitrile, 2,2′-azobis (2-methylbutyronitrile), 2,2′-azobis (2,4-dimethylvaleronitrile), 2,2′-azobis (4-methoxy-2,4-dimethylvaleronitrile), 1,1-bis (t-butylperoxy) 3,3,5-trimethylcyclohexane 1,1-bis (t-butylperoxy) cyclohexane, 1,4-bis (t-butylperoxycarbonyl) cyclohexane, 2,2-bis (t-butylperoxy) octane, n-butyl 4,4 -Screw (t-
Butylperoxy) valerate, 2,2-bis (t-butylperoxy) butane, 1,3-bis (t-butylperoxy-isopropyl) benzene, 2,5-dimethyl-2,5-di (t- Butylperoxy) hexane, 2,
5-dimethyl-2,5-di (t-butylperoxy) hexane, 2,5-dimethyl-2,5-di (benzoylperoxy) hexane, di-t-butyldiperoxyisophthalate, 2,2 -Bis (4,4-di-t-butylperoxycyclohexyl) propane, di-t-butylperoxy α-methylsuccinate, di-t-butylperoxydimethylglutarate, di-t-butylperoxyhexa Hydroterephthalate, di-t-butylperoxyazelate, 2,5-dimethyl-2,5-di (t-
Butyl peroxy) hexane, diethylene glycol
Bis (t-butylperoxycarbonate), di-t-
Butyl peroxytrimethyl adipate, tris (t-
(Butylperoxy) triazine, vinyltris (t-butylperoxy) silane, and the like. These polymerization initiators can be used alone or in combination.

The amount used is 0.05 parts by weight or more (preferably 0.1 to 15 parts by weight) with respect to 100 parts by weight of the monomer.

The composition of the polyester resin 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, bisphenol represented by the formula (A) and derivatives thereof;

[0071]

[Outside 3] (Wherein, R represents an ethylene group or a propylene group, and x
And y are each an integer of 0 or more, and x + y
Is from 0 to 10. )

Diols represented by formula (B):

[0073]

[Outside 4] (Wherein R ′ is —CH ₂ CH ₂ — or

[0074]

[Outside 5] And x ′ and y ′ are integers of 0 or more, and
The average value of x '+ y' is 0-10. ).

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

Further, it is preferable to use a trivalent or higher valent alcohol component and a trivalent or higher valent acid component which also function as a crosslinking component.

The trihydric or higher polyhydric alcohol component includes
For example, sorbitol, 1,2,3,6-hexanetetrol, 1,4-sorbitan, pentaerythritol, dipentaerythritol, tripentaerythritol,
1,2,4-butanetriol, 1,2,5-pentanetriol, glycerol, 2-methylpropanetriol, 2-methyl-1,2,4-butanetriol, trimethylolethane, trimethylolpropane, 1,
3,5-trihydroxybenzene and the like.

Examples of the trivalent or higher polycarboxylic acid component include trimellitic acid, pyromellitic acid,
2,4-benzenetricarboxylic acid, 1,2,5-benzenetricarboxylic acid, 2,5,7-naphthalenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid,
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, empol trimer acid, and anhydrides and lower alkyl esters thereof;

[0079]

[Outside 6] (In the formula, X represents an alkylene group or alkenylene group having 1 to 30 carbon atoms having one or more side chains having 1 or more carbon atoms.)
Represented by the following, and their anhydrides,
Examples include polycarboxylic acids such as lower alkyl esters and derivatives thereof.

As the alcohol component, 40 to 60 mol
%, Preferably 45 to 55 mol%, and 6% as the acid component.
It is preferably 0 to 40 mol%, preferably 55 to 45 mol%.

The polyvalent component having a valence of 3 or more is preferably 1 to 60 mol% of all components.

The polyester resin can be obtained by conducting generally known condensation polymerization using the above-mentioned alcohol component and acid component.

In the magnetic toner of the present invention, the following compounds may be contained in a smaller proportion in addition to the binder resin component. For example, a silicone resin, polyurethane, polyamide, epoxy resin, polyvinyl butyral, rosin, modified rosin, terpene resin, phenol resin, and a copolymer of two or more α-olefins can be used.

The glass transition point (T) of the magnetic toner of the present invention
g) is preferably from 45 to 80 ° C, more preferably from 50 to 80 ° C.
70 ° C.

The acid value of the toluene-soluble binder resin component of the toner of the present invention is preferably from 0.5 to 50 mgKOH / g, more preferably from 0.5 to 30 mgKOH / g, and particularly preferably a positively chargeable toner. 0.5-20 in some cases
It is preferably mgKOH / g.

When the binder resin has an acid value, the dispersive adhesion of the magnetic substance can be further improved by the interaction between the polar portion of the binder resin and the polar portion of the magnetic iron oxide, and the durability is more excellent. It will be.

The binder resin having an acid value becomes negatively charged. However, the presence of the magnetic iron oxide of the present invention eases the charge, so that the charge stabilization is promoted. In this case, the negative chargeability of the binder resin can be reduced, and the adverse effects due to the negative charge can be reduced.

In the present invention, the acid value (JIS acid value) of the soluble resin component of the toner is determined by the following method.

<Measurement of acid value> The basic operation is JIS K-0.
070. 1) The sample is used after removing additives other than the resin component in advance, or the acid value and the content of the component other than the resin are determined in advance. A crushed sample of 0.5 to 2.0 (g) is precisely weighed, and the weight of the resin component is defined as W (g). 2) The sample is placed in a 300 (ml) beaker, and 150 (ml) of a mixed solution of toluene / ethanol (4/1) is added and dissolved. 3) Using an ethanol solution of 0.1 N KOH to titrate using a potentiometric titrator (for example, a potentiometric titrator AT-400 manufactured by Kyoto Electronics Co., Ltd. (winwork)
station) and automatic titration using an ABP-410 motorized burette can be used). 4) The amount of the KOH solution used at this time is defined as S (ml), a blank is measured at the same time, and the amount of the KOH solution used at this time is defined as B (ml). 5) Calculate the acid value by the following equation. f is a factor of KOH.

Acid value (mgKOH / g) = ｛(S−B) ×
f × 5.61｝ / W

The wax contained in the magnetic toner of the present invention includes low molecular weight polyethylene, low molecular weight polypropylene,
Aliphatic hydrocarbon waxes such as olefin copolymers, microcrystalline wax, paraffin wax and sasol wax; oxides of aliphatic hydrocarbon waxes such as oxidized polyethylene wax or block copolymers thereof; carnauba wax And waxes mainly containing fatty acid esters such as montanic acid ester waxes; and those obtained by partially or entirely deoxidizing fatty acid esters such as deoxidized carnauba wax.
Further, saturated linear fatty acids such as palmitic acid, stearic acid, montanic acid, or long-chain alkyl carboxylic acids having a longer-chain alkyl group; unsaturated fatty acids such as brassic acid, eleostearic acid, and barinaric acid;
Saturated alcohols such as stearin alcohol, aralkyl alcohol, behenyl alcohol, carnaubyl alcohol, seryl alcohol, melisyl alcohol, or long-chain alkyl alcohols having a longer-chain alkyl group; polyhydric alcohols such as sorbitol; linoleic acid Fatty acid amides such as amide, oleic acid amide and lauric acid amide; saturated fatty acid bisamides such as methylenebisstearic acid amide, ethylenebiscapric acid amide, ethylenebislauric acid amide, hexamethylenebisstearic acid amide, ethylenebisoleic acid Amide, hexamethylenebisoleamide, N,
Unsaturated fatty acid amides such as N'-dioleyl adipamide, N, N'-dioleyl sebacamide; m
Aromatic bisamides such as -xylene bisstearic acid amide and N, N'-distearylisophthalic acid amide; waxes obtained by grafting an aliphatic hydrocarbon wax with a vinyl monomer such as styrene or acrylic acid A partially esterified product of a fatty acid such as behenic acid monoglyceride and a polyhydric alcohol; and a methyl ester compound having a hydroxy group obtained by hydrogenating vegetable fats and oils.

The wax preferably used is a low-molecular-weight alkylene polymer obtained by radical polymerization of alkylene under high pressure or polymerized under low pressure using a Ziegler catalyst or another catalyst; obtained by thermally decomposing a high-molecular-weight alkylene polymer. Alkylene polymer; a product obtained by separating and purifying a low-molecular-weight alkylene polymer produced as a by-product when polymerizing the alkylene polymer; from a hydrocarbon distillation residue obtained from a synthesis gas consisting of carbon monoxide and hydrogen by the Age method, or A wax obtained by extracting and fractionating a specific component from a synthetic hydrocarbon or the like obtained by addition is mentioned. An antioxidant may be added to these waxes. Further, waxes formed of linear alcohols, fatty acids, acid amides, esters or montan derivatives are mentioned. It is also preferable that impurities such as fatty acids have been removed in advance.

Among them, preferred are those obtained by polymerizing olefins such as ethylene, by-products at this time, and hydrocarbons having up to several thousands of carbon atoms, such as Fischer-Tropsch wax. Further, a long-chain alkyl alcohol having a hydroxyl group at a terminal having a carbon number of up to about several hundreds is also preferable. Further, those obtained by adding an alkylene oxide to an alcohol are also preferably used.

From these waxes, the waxes are subjected to press sweating, solvent method, vacuum distillation, supercritical gas extraction, fractional crystallization (for example, melt liquid crystal deposition and crystal filtration), etc., to obtain waxes having different molecular weights. A wax that has been fractionated and has a sharp molecular weight distribution is more preferable because the proportion of components in the necessary melting behavior range increases.

The wax having a sharp molecular weight distribution is
A suitable reversibility is provided to the binder resin, and the adhesion to the magnetic iron oxide can be further strengthened.

At this time, the wax is more preferably a hydrocarbon wax so as not to impair the releasability.

The molecular weight distribution of the wax was such that Mw / Mn was 3.
It is preferably 0 or less, more preferably 2.5 or less, and even more preferably 2.0 or less.

As the inorganic fine powder used as an external additive to the magnetic toner of the present invention, inorganic oxides such as silica, alumina and titanium oxide, carbon black, carbon fluoride and the like are formed into fine particles. It is preferable in that it is easy.

Silica, alumina, and titanium oxide are preferably formed into fine particles when dispersed on the surface of the toner, since the fluidity-imparting property becomes higher. 5-20 as average particle size
0 nm is preferable, and more preferably 10 to 10 nm
0 nm is good. The specific surface area by nitrogen adsorption measured by the BET method is 20 m ² / g or more (especially 30 to 400 m ² / g).
Is preferably used as the base fine powder, and the surface-treated fine powder is preferably 10 m ² / g or more (particularly 20 to 3).
00 m ² / g).

The application amount of these fine powders becomes an appropriate surface coverage when 0.03 to 5% by weight is added to the magnetic toner.

The hydrophobicity of the inorganic fine powder preferably shows a value of 30% or more. As the hydrophobizing agent, a silane compound which is a silicon-containing surface treating agent and silicone oil are preferable.

For example, alkylalkoxysilanes such as dimethyldimethoxysilane, trimethylethoxysilane, butyltrimethoxysilane and the like, dimethyldichlorosilane, trimethylchlorosilane, allyldimethylchlorosilane, hexamethyldisilazane, allylphenyldichlorosilane And silane compounds such as benzyldimethylchlorosilane, vinyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, vinyltriacetoxysilane, divinyldichlorosilane, and dimethylvinylchlorosilane.

The following positively chargeable materials may be used for adjusting the charge amount. Silane coupling agents such as aminopropyltrimethoxysilane, aminopropyltriethoxysilane, dimethylaminopropyltrimethoxysilane, diethylaminopropyltrimethoxysilane, dipropylaminopropyltrimethoxysilane, dibutylaminopropyltrimethoxysilane, and amino-modified Silicone oil or the like can be used.

It is also preferable to add the following inorganic powder in order to improve developability and durability. Magnesium, zinc, aluminum, cerium, cobalt, iron, zirconium, chromium, manganese, strontium, tin,
Metal oxides such as antimony; composite metal oxides such as calcium titanate, magnesium titanate and strontium titanate; metal salts such as calcium carbonate, magnesium carbonate and aluminum carbonate; clay minerals such as kaolin;
Phosphate compounds such as apatite; silicon compounds such as silicon carbide and silicon nitride; and carbon powders such as carbon black and graphite. Among them, zinc oxide, aluminum oxide, cobalt oxide, manganese dioxide, strontium titanate, magnesium titanate and the like are preferable.

Further, the following lubricant powder can be added. Fluorine resins such as Teflon and polyvinylidene fluoride; and fluorine compounds such as carbon fluoride.

The magnetic toner of the present invention preferably contains a charge control agent.

The following substances control the toner to be positively charged.

Modified products such as nigrosine and fatty acid metal salts; quaternary ammonium salts such as tributylbenzylammonium-1-hydroxy-4-naphthosulfonate and tetrabutylammonium tetrafluoroborate;
And onium salts thereof such as phosphonium salts, which are analogs thereof, and lake pigments thereof, triphenylmethane dyes and these lake pigments (as the lake-forming agent, phosphotungstic acid, phosphomolybdic acid, phosphotungsten molybdic acid, tannin Acid, lauric acid, gallic acid, ferricyanide, ferrocyanide, etc.) metal salts of higher fatty acids; diorganotin oxides such as dibutyltin oxide, dioctyltin oxide, dicyclohexyltin oxide; dibutyltin borate, dioctyltin borate, dicyclohexyltin borate Diorganotin borates; guanidine compounds, imidazole compounds; These can be used alone or in combination of two or more. Among these, a triphenylmethane compound, an imidazole compound, and a quaternary ammonium salt whose counter ion is not halogen are preferably used. The general formula (1)

[0109]

[Outside 7] Monomer of a monomer represented by: styrene described above,
Copolymers with polymerizable monomers such as acrylates and methacrylates can be used as positive charge control agents. In this case, these charge control agents also act as (all or part of) the binder resin.

Particularly, a triphenylmethane lake pigment or an imidazole compound represented by the following general formula (2) is preferable in the constitution of the present invention.

That is, in the magnetic toner of the present invention,
When these charge control agents are included, the charge adjusting effect of the magnetic iron oxide and the charge generation effect of these charge control agents are moderately balanced, and the durability and environmental stability are excellent.

[0112]

[Outside 8]

The following substances control the magnetic toner to be negatively charged.

For example, organic metal complexes and chelate compounds are effective, and examples thereof include monoazo metal complexes, acetylacetone metal complexes, aromatic hydroxycarboxylic acids, and aromatic dicarboxylic acid-based metal complexes. Other examples include aromatic hydroxycarboxylic acids, aromatic mono- and polycarboxylic acids and their metal salts, anhydrides, esters, and phenol derivatives such as bisphenol.

An azo metal complex represented by the following general formula (3) is preferred.

[0116]

[Outside 9]

In particular, the central metal is preferably Fe or Cr, the substituent is preferably a halogen, an alkyl group or an anilide group, and the counter ion is preferably hydrogen, alkali metal, ammonium or aliphatic ammonium. Also, a mixture of complex salts having different counter ions is preferably used.

Alternatively, a basic organic acid metal complex represented by the following general formula (4) also gives negative chargeability and can be used in the present invention.

[0119]

[Outside 10]

In particular, Fe, Cr, Si,
Zn or Al is preferable, and the substituent is an alkyl group,
Anilide groups, aryl groups and halogens are preferred, and the counter ion is preferably hydrogen, ammonium or aliphatic ammonium.

As a method for incorporating the charge control agent into the toner, there are a method of adding it inside the toner and a method of adding it externally. The use amount of these charge control agents is determined by the type of the binder resin, the presence or absence of other additives, the toner manufacturing method including the dispersion method, and is not limited to a specific one. Preferably, it is used in the range of 0.1 to 10 parts by weight, more preferably 0.1 to 5 parts by weight, based on 100 parts by weight of the binder resin.

The magnetic toner of the present invention is prepared by thoroughly mixing a binder resin, a magnetic substance, a wax, a charge control agent, and other additives with a mixer such as a Henschel mixer or a ball mill, and then heating the mixture with a heating roll, a kneader or an extruder. The components are dispersed or dissolved in a resin kneaded by melt kneading using a heat kneader such as a ruder, and after cooling and solidification, pulverization and classification are performed, and if necessary, a desired external additive is added. It can also be obtained by sufficiently mixing with a mixer such as a Henschel mixer.

The magnetic material according to the present invention has a uniform particle size distribution,
Since it has excellent dispersibility in the binder resin, the chargeability of the toner can be stabilized. In recent years, the toner particle diameter has been reduced, and even when the average particle diameter of the toner is 9 μm or less, charging uniformity is promoted, toner cohesion is reduced, image density is improved, and fog is reduced. Developability such as improvement is improved. In particular, the effect is remarkable in a toner having a weight average particle diameter of 6.0 μm or less, and an extremely high-definition image can be obtained. It is preferable that the weight average particle diameter is 3.0 μm or more, since sufficient image density can be obtained. On the other hand, as the particle size of the toner progresses, the release of the magnetic substance also tends to occur,
Since the toner of the present invention has excellent adhesion to the binder resin, the magnetic substance is not easily released, and troubles such as sleeve contamination are suppressed.

The weight average particle diameter of the magnetic toner of the present invention was measured using a Coulter Multisizer (manufactured by Coulter), and the electrolytic solution was ISOTON R-II (1% NaCl aqueous solution,
(Coulter Scientific Japan). As a measuring method, the electrolytic aqueous solution 100 to
0.1 to 5 m of a surfactant as a dispersant in 150 ml
and 2 to 20 mg of the measurement sample. The electrolyte in which the sample is suspended is subjected to a dispersion treatment for about 1 to 3 minutes by an ultrasonic disperser, and the volume and the number are measured by the measuring device to calculate a volume average particle diameter.

When the weight average particle size is larger than 6.0 μm, particles of 2 to 60 μm are measured using an aperture of 100 μm, and when the weight average particle size is 3.0 to 6.0 μm, 5
Particles of 1 to 30 μm are measured using an aperture of 0 μm, and when the weight average particle diameter is less than 3.0 μm, particles of 0.6 to 18 μm are measured using an aperture of 30 μm.

Next, the image forming method of the present invention will be described with reference to FIGS. The surface of the latent image carrier (photoconductor) 1 is charged to a negative polarity or a positive polarity by the primary charger 2, and an electrostatic charge image (for example, a digital latent image by image scanning) is formed by analog exposure or exposure 5 by laser light. , The magnetic blade 11 and the magnetic poles N ₁ , N ₂ , S ₁ and S ₂
The electrostatic charge image is developed by reversal development or regular development with the magnetic toner 13 in the developing device 9 having the developer carrier (developing sleeve) 4 including the magnet 23 having the magnet 23. In the developing section, the conductive base 16 of the photoreceptor 1 and the developing sleeve 4
Between the bias applying means 12 alternate bias,
A pulse bias and / or a DC bias is applied. The formed magnetic toner image is transferred to a transfer material such as transfer paper. Although the image forming apparatus in FIG. 8 does not have an intermediate transfer body, an image forming apparatus having an intermediate transfer body can also be used. When the transfer paper P is conveyed and arrives at the transfer section, the transfer charger 3 charges the transfer paper P with positive or negative polarity from the back surface (the surface opposite to the photoconductor side),
The negatively charged magnetic toner image or the positively charged magnetic toner image on the photoreceptor surface is electrostatically transferred onto the transfer paper P. After the charge removal, the transfer paper P separated from the photoconductor 1 is fixed on the toner image on the transfer paper P by the heating / pressing roller fixing device 7 including the heater 21.

The magnetic toner remaining on the photoreceptor 1 after the transfer step is removed by cleaning means having a cleaning blade 8. After the cleaning, the photosensitive member 1 is neutralized by the erase exposure 6, and the process starting from the charging process by the primary charger 2 is repeated again.

The latent image carrier (for example, a photosensitive drum) 1 has a photosensitive layer 15 and a conductive substrate 16 and moves in the direction of the arrow. The non-magnetic cylindrical developing sleeve 4 as the developer carrier 4 rotates so as to advance in the same direction as the surface of the latent image carrier 1 in the developing section. Inside the non-magnetic cylindrical developing sleeve 4,
Multi-pole permanent magnet (magnet roll) that is a magnetic field generating means
23 is arranged so as not to rotate. The magnetic toner 13 in the developing device 9 is applied to the developing sleeve 4, and triboelectric charges are given to the magnetic toner particles by friction between the surface of the developing sleeve 4 and the magnetic toner particles. Further, by disposing an iron magnetic blade 11 close to the surface of the cylindrical developing sleeve 4 (interval: 50 to 500 μm) and opposed to one magnetic pole position of the multipolar permanent magnet, the thickness of the magnetic toner layer is reduced. Is regulated thinly (30 to 300 μm) and uniformly to form a magnetic toner layer equal to or thinner than the gap between the latent image carrier 1 and the developing sleeve 4 in the developing section.
By adjusting the rotation speed of the developing sleeve 4, the surface speed of the developing sleeve is made substantially equal to or close to the speed of the surface of the latent image carrier 1. The opposing magnetic poles may be formed by using permanent magnets instead of iron as the magnetic blades 11. In the developing section, an AC bias or a pulse bias means 12 may be applied to the developing sleeve 4. This AC bias is f 200 to 4,
000Hz, V _pp may if 500~3,000V.

At the time of transfer of the magnetic toner particles in the developing section, the magnetic toner particles move to the electrostatic image side due to the electrostatic force on the surface of the latent image carrier and the action of the AC bias or the pulse bias.

Instead of the magnetic blade 11, an elastic blade made of an elastic material such as silicone rubber may be used to regulate the thickness of the magnetic toner layer by pressing and apply the magnetic toner on the developing sleeve.

The magnetic toner of the present invention exerts its effect particularly when used as a positively chargeable magnetic toner in an image forming method in which a silicon photosensitive drum is used as a latent image carrier and a digital latent image is reversely developed. .

[0132]

EXAMPLES The present invention will be described below with reference to specific examples, but the present invention is not limited to these examples.

Production Example In the step of producing a magnetic substance by oxidizing an iron salt into an iron colloid with an alkaline solution and adding the aqueous solution of the elements α and β, the amount, the method of addition, the pH value and the time Was adjusted, and various oxidation and heating conditions were changed to prepare various magnetic materials.

For example, the magnetic body 1 is synthesized as follows.

In a reaction vessel containing 20 l of a 3.0 mol / l aqueous sodium hydroxide solution, 1.5 mol of Fe ²⁺ was added.
Per liter of an aqueous ferrous sulfate solution, and the temperature was adjusted to 95
C. to produce a ferrous salt suspension containing ferrous hydroxide colloid.

While passing 100 l of air per minute, an aqueous sodium silicate solution containing 28 g of silicon was added.
2 l were added dropwise over 60 minutes. Thereafter, stirring was performed for 30 minutes to obtain a ferrous suspension containing magnetite.

The pH was adjusted to 10.0 by adding a 6.0 mol / l aqueous solution of sodium hydroxide. Further, 0.1 l of an aqueous sodium silicate solution containing 28 g of silicon was added dropwise over 30 minutes while passing 100 l of air per minute, followed by stirring for 30 minutes to produce magnetite particles.

[0138] To this was added 150 ml of a 0.5 mol / l aqueous solution of aluminum sulfate, and the mixture was sufficiently stirred. Then, magnetite was separated by filtration. The magnetite was washed with water, dried, and crushed to obtain a magnetic material 1.

Tables 1 and 2 show the compositions of the magnetic materials adjusted in this example, and Table 3 shows various physical properties.

[0140]

[Table 1]

[0141]

[Table 2]

[0142]

[Table 3]

Example 1 100 parts by weight of styrene-butyl acrylate copolymer (acid value 0) 90 parts by weight of magnetic substance 1 2 parts by weight of triphenylmethane-based lake pigment Fischer-Tropsch wax (Mw / Mn = 1. 7) 4 parts by weight

After the above materials were premixed by a Henschel mixer, they were melted and kneaded by a twin screw extruder set at 130 ° C. The obtained kneaded material was cooled, coarsely pulverized by a cutter mill, then pulverized by a fine pulverizer using a jet stream, and the obtained finely pulverized powder was classified using a multi-part classifier utilizing the Coanda effect. , Volume average particle size 7.2 μm
0.8 parts by weight of silica having a BET specific surface area of 90 m ² / g hydrophobized with amino-modified silicone was added and mixed with 100 parts by weight of magnetic toner particles to obtain a positively chargeable magnetic toner. Obtained. FIG. 10 shows a dissolution rate curve of the magnetic body 1.

This magnetic toner was used as an electrophotographic copying machine NP-6085 having a commercially available amorphous silicon drum.
(Canon Co., Ltd.) modified machine (non-image area drum potential 400 V, image area drum potential 1) in which bias and others are modified so that reversal development can be performed using a positively chargeable magnetic toner.
00 V, a developing bias DC of 300 V, and an image potential contrast of 200 V).
% RH, temperature 30 ℃, humidity 80% RH
, 100,000 copy tests were performed in each environment.

As a result, a high-definition image with high image density and no fog was obtained in both environments. Details are shown in Tables 4 and 5. Image density is Macbeth densitometer (made by Macbeth)
Use a SPI filter to measure the reflection density,
An image of a 5 mm diameter circle (5φ) was measured. Fog is performed using a reflection densitometer (Reflectometer Model TC-6DS, manufactured by Tokyo Denshoku Co., Ltd.), and the worst value of the reflection density of a white background after image formation is Ds, and the reflection average density of the transfer material before image formation is Dr. Fog was evaluated using Ds-Dr as the amount of fog. The smaller the value, the better the fog suppression. The image quality was evaluated by copying a halftone dot image of 20 tones every 5% with an image ratio of 5 to 100%, and determining how many gradations could be expressed. The higher the number of gradations, the higher the definition.
The halftone dot image is formed of binary dots, and the excellent reproducibility means that a digital latent image can be faithfully developed, so that it exhibits excellent developability in digital printers and digital copiers. Indicates that it can be done.

Further, following the above-described copying test, a temperature of 23
When a copy test was performed on 1,000,000 sheets in an environment at a temperature of 60 ° C and a humidity of 60% RH, the image density was 1.40 to 1.4.
2. A good image having a fog of 0.2 to 0.8 and a gradation of 18 to 19 was obtained, and the drum abrasion was 2.0 nm / 100,000.
There was no problem with 0 sheets.

Example 2 100 parts by weight of styrene-butyl acrylate copolymer (acid value 0) 90 parts by weight of magnetic substance 2 2 parts by weight of triphenylmethane lake pigment Fischer-Tropsch wax (Mw / Mn = 1. 5) 4 parts by weight

After the above materials were premixed by a Henschel mixer, they were melted and kneaded by a twin-screw kneading extruder set at 130 ° C. The obtained kneaded material was cooled, coarsely pulverized by a cutter mill, then pulverized by a fine pulverizer using a jet stream, and the obtained finely pulverized powder was classified using a multi-part classifier utilizing the Coanda effect. , Volume average particle size 7.5 μm
0.8 parts by weight of silica having a BET specific surface area of 90 m ² / g hydrophobized with amino-modified silicone was added and mixed with 100 parts by weight of magnetic toner particles to obtain a positively chargeable magnetic toner. Obtained.

This toner was evaluated in the same manner as in Example 1. The results are shown in Tables 4 and 5.

Example 3 100 parts by weight of styrene-butyl acrylate copolymer (acid value 0) 90 parts by weight of magnetic substance 3 parts by weight of triphenylmethane lake pigment 2 parts by weight of Fischer-Tropsch wax (Mw / Mn = 1. 7) 4 parts by weight

After the above materials were premixed with a Henschel mixer, they were melted and kneaded by a twin screw extruder set at 130 ° C. The obtained kneaded material was cooled, coarsely pulverized by a cutter mill, then pulverized by a fine pulverizer using a jet stream, and the obtained finely pulverized powder was classified using a multi-part classifier utilizing the Coanda effect. , Volume average particle size 7.7 μm
0.8 parts by weight of silica having a BET specific surface area of 90 m ² / g hydrophobized with amino-modified silicone was added and mixed with 100 parts by weight of magnetic toner particles to obtain a positively chargeable magnetic toner. Obtained.

This toner was evaluated in the same manner as in Example 1. The results are shown in Tables 4 and 5.

Example 4 100 parts by weight of styrene-butyl acrylate copolymer (acid value 0) 90 parts by weight of magnetic substance 4 2 parts by weight of triphenylmethane-based lake pigment Fischer-Tropsch wax (Mw / Mn = 1. 7) 4 parts by weight

After the above materials were premixed by a Henschel mixer, they were melted and kneaded by a twin screw extruder set at 130 ° C. The obtained kneaded material was cooled, coarsely pulverized by a cutter mill, then pulverized by a fine pulverizer using a jet stream, and the obtained finely pulverized powder was classified using a multi-part classifier utilizing the Coanda effect. , Volume average particle size 7.0 μm
0.8 parts by weight of silica having a BET specific surface area of 90 m ² / g hydrophobized with amino-modified silicone was added and mixed with 100 parts by weight of magnetic toner particles to obtain a positively chargeable magnetic toner. Obtained.

This toner was evaluated in the same manner as in Example 1. The results are shown in Tables 4 and 5.

Example 5 100 parts by weight of styrene-butyl acrylate copolymer (acid value 0) 90 parts by weight of magnetic substance 5 parts by weight of triphenylmethane lake pigment 2 parts by weight of Fischer-Tropsch wax (Mw / Mn = 1. 7) 4 parts by weight

After the above materials were premixed by a Henschel mixer, they were melted and kneaded by a twin screw extruder set at 130 ° C. The obtained kneaded material was cooled, coarsely pulverized by a cutter mill, then pulverized by a fine pulverizer using a jet stream, and the obtained finely pulverized powder was classified using a multi-part classifier utilizing the Coanda effect. , Volume average particle size 6.8 μm
The magnetic toner particles are obtained by adding 0.9 parts by weight of silica having a BET specific surface area of 90 m ² / g hydrophobized with amino-modified silicone to 100 parts by weight of the magnetic toner particles, and the positively chargeable magnetic toner is mixed. Obtained.

This toner was evaluated in the same manner as in Example 1. The results are shown in Tables 4 and 5.

Comparative Example 1 100 parts by weight of styrene-butyl acrylate copolymer (acid value 0) 90 parts by weight of magnetic substance 6 2 parts by weight of triphenylmethane-based lake pigment Fischer-Tropsch wax (Mw / Mn = 1. 7) 4 parts by weight

After the above materials were premixed by a Henschel mixer, they were melted and kneaded by a biaxial kneading extruder set at 130 ° C. The obtained kneaded material was cooled, coarsely pulverized by a cutter mill, then pulverized by a fine pulverizer using a jet stream, and the obtained finely pulverized powder was classified using a multi-part classifier utilizing the Coanda effect. , Volume average particle size 7.6 μm
0.8 parts by weight of silica having a BET specific surface area of 90 m ² / g hydrophobized with amino-modified silicone was added and mixed with 100 parts by weight of magnetic toner particles to obtain a positively chargeable magnetic toner. Obtained. FIG. 11 shows a dissolution rate curve of the magnetic material 6.

This toner was evaluated in the same manner as in Example 1. The results are shown in Tables 4 and 5.

Comparative Example 2 100 parts by weight of styrene-butyl acrylate copolymer (acid value 0) 90 parts by weight of magnetic substance 7 2 parts by weight of triphenylmethane lake pigment Fischer-Tropsch wax (Mw / Mn = 1.7) 4 parts by weight

After the above materials were premixed with a Henschel mixer, they were melted and kneaded with a twin screw extruder set at 130 ° C. The obtained kneaded material was cooled, coarsely pulverized by a cutter mill, then pulverized by a fine pulverizer using a jet stream, and the obtained finely pulverized powder was classified using a multi-part classifier utilizing the Coanda effect. , Volume average particle size 7.2 μm
0.8 parts by weight of silica having a BET specific surface area of 90 m ² / g hydrophobized with amino-modified silicone was added and mixed with 100 parts by weight of magnetic toner particles to obtain a positively chargeable magnetic toner. Obtained. FIG. 12 shows a dissolution rate curve of the magnetic body 7.

This toner was evaluated in the same manner as in Example 1. Tables 4 and 5 show the results.

Comparative Example 3 100 parts by weight of styrene-butyl acrylate copolymer (acid value 0) 90 parts by weight of magnetic substance 13 2 parts by weight of triphenylmethane lake pigment Fischer-Tropsch wax (Mw / Mn = 1.7) 4 parts by weight

After the above materials were premixed by a Henschel mixer, they were melted and kneaded by a twin-screw kneading extruder set at 130 ° C. The obtained kneaded material was cooled, coarsely pulverized by a cutter mill, then pulverized by a fine pulverizer using a jet stream, and the obtained finely pulverized powder was classified using a multi-part classifier utilizing the Coanda effect. , Volume average particle size 7.5 μm
0.8 parts by weight of silica having a BET specific surface area of 90 m ² / g hydrophobized with amino-modified silicone was added and mixed with 100 parts by weight of magnetic toner particles to obtain a positively chargeable magnetic toner. Obtained.

This toner was evaluated in the same manner as in Example 1. Tables 4 and 5 show the results.

Comparative Example 4 100 parts by weight of styrene-butyl acrylate copolymer (acid value 0) 90 parts by weight of magnetic substance 14 2 parts by weight of triphenylmethane lake pigment Fischer-Tropsch wax (Mw / Mn = 1.7) 4 parts by weight

After the above materials were premixed by a Henschel mixer, they were melted and kneaded by a twin screw extruder set at 130 ° C. The obtained kneaded material was cooled, coarsely pulverized by a cutter mill, then pulverized by a fine pulverizer using a jet stream, and the obtained finely pulverized powder was classified using a multi-part classifier utilizing the Coanda effect. , Volume average particle size 7.7 μm
0.8 parts by weight of silica having a BET specific surface area of 90 m ² / g hydrophobized with amino-modified silicone was added and mixed with 100 parts by weight of magnetic toner particles to obtain a positively chargeable magnetic toner. Obtained.

This toner was evaluated in the same manner as in Example 1. Tables 4 and 5 show the results.

Comparative Example 5 100 parts by weight of styrene-butyl acrylate copolymer (acid value 0) 90 parts by weight of magnetic substance 15 2 parts by weight of triphenylmethane lake pigment Fischer-Tropsch wax (Mw / Mn = 1.7) 4 parts by weight

After the above materials were premixed by a Henschel mixer, they were melted and kneaded by a biaxial kneading extruder set at 130 ° C. The obtained kneaded material was cooled, coarsely pulverized by a cutter mill, then pulverized by a fine pulverizer using a jet stream, and the obtained finely pulverized powder was classified using a multi-part classifier utilizing the Coanda effect. , Volume average particle size 7.9 μm
0.8 parts by weight of silica having a BET specific surface area of 90 m ² / g hydrophobized with amino-modified silicone was added and mixed with 100 parts by weight of magnetic toner particles to obtain a positively chargeable magnetic toner. Obtained.

This toner was evaluated in the same manner as in Example 1. Tables 4 and 5 show the results.

Example 6 100 parts by weight of styrene-butyl acrylate-monobutyl maleate copolymer (acid value 2.0) 100 parts by weight of magnetic substance 1 part by weight of imidazole compound 2 parts by weight Fischer-Tropsch wax (Mw / Mn = 1.4) 4 parts by weight

After the above materials were premixed by a Henschel mixer, they were melted and kneaded by a twin screw extruder set at 130 ° C. The obtained kneaded material was cooled, coarsely pulverized by a cutter mill, then pulverized by a fine pulverizer using a jet stream, and the obtained finely pulverized powder was classified using a multi-part classifier utilizing the Coanda effect. , Volume average particle size 6.6 μm
The magnetic toner particles are obtained by adding 1.0 part by weight of silica having a BET specific surface area of 90 m ² / g hydrophobized with amino-modified silicone to 100 parts by weight of the magnetic toner particles to form a positively chargeable magnetic toner. Obtained.

The toner was evaluated in the same manner as in Example 1. Tables 4 and 5 show the results.

Example 7 100 parts by weight of styrene-butyl acrylate-monobutyl maleate copolymer (acid value 1.2) 100 parts by weight of magnetic substance 2 2 parts by weight of imidazole compound Fischer-Tropsch wax (Mw / Mn = 1.4) 4 parts by weight

After the above materials were premixed by a Henschel mixer, they were melted and kneaded by a biaxial kneading extruder set at 130 ° C. The obtained kneaded material was cooled, coarsely pulverized by a cutter mill, then pulverized by a fine pulverizer using a jet stream, and the obtained finely pulverized powder was classified using a multi-part classifier utilizing the Coanda effect. , Volume average particle size 6.7 μm
The magnetic toner particles are obtained by adding 1.0 part by weight of silica having a BET specific surface area of 90 m ² / g hydrophobized with amino-modified silicone to 100 parts by weight of the magnetic toner particles to form a positively chargeable magnetic toner. Obtained.

This toner was evaluated in the same manner as in Example 1. Tables 4 and 5 show the results.

Example 8 100 parts by weight of styrene-butyl acrylate-monobutyl maleate copolymer (acid value 0.8) 100 parts by weight of magnetic substance 3 2 parts by weight of imidazole compound Fischer-Tropsch wax (Mw / Mn = 1.4) 4 parts by weight

After the above materials were premixed with a Henschel mixer, they were melted and kneaded by a twin screw extruder set at 130 ° C. The obtained kneaded material was cooled, coarsely pulverized by a cutter mill, then pulverized by a fine pulverizer using a jet stream, and the obtained finely pulverized powder was classified using a multi-part classifier utilizing the Coanda effect. , Volume average particle size 6.4 μm
The magnetic toner particles are obtained by adding 1.0 part by weight of silica having a BET specific surface area of 90 m ² / g hydrophobized with amino-modified silicone to 100 parts by weight of the magnetic toner particles to form a positively chargeable magnetic toner. Obtained.

This toner was evaluated in the same manner as in Example 1. Tables 4 and 5 show the results.

Example 9 100 parts by weight of styrene-butyl acrylate-monobutyl maleate copolymer (acid value 4.0) 90 parts by weight of magnetic substance 4 2 parts by weight of imidazole compound Fischer-Tropsch wax (Mw / Mn = 1.4) 4 parts by weight

After the above materials were premixed by a Henschel mixer, they were melted and kneaded by a twin screw extruder set at 130 ° C. The obtained kneaded material was cooled, coarsely pulverized by a cutter mill, then pulverized by a fine pulverizer using a jet stream, and the obtained finely pulverized powder was classified using a multi-part classifier utilizing the Coanda effect. , Volume average particle size 6.4 μm
The magnetic toner particles are obtained by adding 1.0 part by weight of silica having a BET specific surface area of 90 m ² / g hydrophobized with amino-modified silicone to 100 parts by weight of the magnetic toner particles to form a positively chargeable magnetic toner. Obtained.

This toner was evaluated in the same manner as in Example 1. Tables 4 and 5 show the results.

Example 10 100 parts by weight of a polyester resin (acid value 18.0) 90 parts by weight of a magnetic substance 5 2 parts by weight of a monoazo iron complex 4 parts by weight of a polypropylene wax (Mw / Mn = 3.5)

After the above materials were premixed by a Henschel mixer, they were melted and kneaded by a twin screw extruder set at 130 ° C. The obtained kneaded material was cooled, coarsely pulverized by a cutter mill, then pulverized by a fine pulverizer using a jet stream, and the obtained finely pulverized powder was classified using a multi-part classifier utilizing the Coanda effect. , Volume average particle size 7.3 μm
BET obtained by subjecting 100 parts by weight of magnetic toner particles to hydrophobic treatment with hexamethyldisilazane
1.0 part by weight of silica having a specific surface area of 160 m ² / g was externally added and mixed to obtain a negatively chargeable magnetic toner.

This toner was converted to a commercially available electrophotographic copying machine NP-
6085 (manufactured by Canon Inc.) at a temperature of 23
Temperature, humidity 5% RH, temperature 30 ° C, humidity 8
A copy test of 100,000 copies was performed in an environment of 0% RH. Tables 4 and 5 show the results.

Example 11 100 parts by weight of styrene-butyl acrylate-monobutyl maleate copolymer (acid value 2.0) 100 parts by weight of magnetic substance 8 2 parts by weight of triphenylmethane lake pigment 2 parts by weight of polyethylene wax (Mw / Mn = 2.2) 4 parts by weight

After the above materials were premixed by a Henschel mixer, they were melted and kneaded by a twin screw extruder set at 130 ° C. The obtained kneaded material was cooled, coarsely pulverized by a cutter mill, then pulverized by a fine pulverizer using a jet stream, and the obtained finely pulverized powder was classified using a multi-part classifier utilizing the Coanda effect. , Volume average particle size 7.6 μm
0.8 parts by weight of silica having a BET specific surface area of 90 m ² / g hydrophobized with amino-modified silicone was added and mixed with 100 parts by weight of magnetic toner particles to obtain a positively chargeable magnetic toner. Obtained.

This toner was evaluated in the same manner as in Example 1. Tables 4 and 5 show the results.

Example 12 100 parts by weight of styrene-butyl acrylate-monobutyl maleate copolymer (acid value 2.0) 90 parts by weight of magnetic substance 9 2 parts by weight of triphenylmethane lake pigment 2 parts by weight of polyethylene wax (Mw / Mn = 2.2) 4 parts by weight

After the above materials were premixed by a Henschel mixer, they were melted and kneaded by a twin screw extruder set at 130 ° C. The obtained kneaded material was cooled, coarsely pulverized by a cutter mill, then pulverized by a fine pulverizer using a jet stream, and the obtained finely pulverized powder was classified using a multi-part classifier utilizing the Coanda effect. , Volume average particle size 7.8 μm
0.8 parts by weight of silica having a BET specific surface area of 90 m ² / g hydrophobized with amino-modified silicone was added and mixed with 100 parts by weight of magnetic toner particles to obtain a positively chargeable magnetic toner. Obtained.

This toner was evaluated in the same manner as in Example 1. Tables 4 and 5 show the results.

Example 13 100 parts by weight of styrene-butyl acrylate-monobutyl maleate copolymer (acid value 2.0) 100 parts by weight of magnetic substance 10 parts by weight of triphenylmethane lake pigment 2 parts by weight of polyethylene wax (Mw / Mn = 2.2) 4 parts by weight

After the above materials were premixed by a Henschel mixer, they were melted and kneaded by a twin-screw kneading extruder set at 130 ° C. The obtained kneaded material was cooled, coarsely pulverized by a cutter mill, then pulverized by a fine pulverizer using a jet stream, and the obtained finely pulverized powder was classified using a multi-part classifier utilizing the Coanda effect. , Volume average particle size 7.4 μm
0.8 parts by weight of silica having a BET specific surface area of 90 m ² / g hydrophobized with amino-modified silicone was added and mixed with 100 parts by weight of magnetic toner particles to obtain a positively chargeable magnetic toner. Obtained.

This toner was evaluated in the same manner as in Example 1. Tables 4 and 5 show the results.

Example 14 100 parts by weight of styrene-butyl acrylate-monobutyl maleate copolymer (acid value 2.0) 100 parts by weight of magnetic substance 11 2 parts by weight of triphenylmethane lake pigment 2 parts by weight of polyethylene wax (Mw / Mn = 2.6) 4 parts by weight

After the above materials were premixed by a Henschel mixer, they were melted and kneaded by a twin screw extruder set at 130 ° C. The obtained kneaded material was cooled, coarsely pulverized by a cutter mill, then pulverized by a fine pulverizer using a jet stream, and the obtained finely pulverized powder was classified using a multi-part classifier utilizing the Coanda effect. , Volume average particle size 7.7 μm
0.8 parts by weight of silica having a BET specific surface area of 90 m ² / g hydrophobized with amino-modified silicone was added and mixed with 100 parts by weight of magnetic toner particles to obtain a positively chargeable magnetic toner. Obtained.

This toner was evaluated in the same manner as in Example 1. Tables 4 and 5 show the results.

Example 15 100 parts by weight of styrene-butyl acrylate-monobutyl maleate copolymer (acid value 2.0) 100 parts by weight of magnetic substance 12 2 parts by weight of triphenylmethane lake pigment 2 parts by weight of polyethylene wax (Mw / Mn = 2.6) 4 parts by weight

After the above materials were premixed with a Henschel mixer, they were melted and kneaded with a twin screw extruder set at 130 ° C. The obtained kneaded material was cooled, coarsely pulverized by a cutter mill, then pulverized by a fine pulverizer using a jet stream, and the obtained finely pulverized powder was classified using a multi-part classifier utilizing the Coanda effect. , Volume average particle size 7.2 μm
0.8 parts by weight of silica having a BET specific surface area of 90 m ² / g hydrophobized with amino-modified silicone was added and mixed with 100 parts by weight of magnetic toner particles to obtain a positively chargeable magnetic toner. Obtained.

This toner was evaluated in the same manner as in Example 1. Tables 4 and 5 show the results.

[0205]

[Table 4]

[0206]

[Table 5]

[0207]

The magnetic toner of the present invention has excellent developability and durability in high-speed development and low-potential development, and in particular, has excellent electrophotographic characteristics in an electrophotographic apparatus using an amorphous silicon drum. it can.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of an outer contour when magnetic iron oxide particles are binuclear particles.

FIG. 2 is a diagram illustrating an example of an outer contour when the magnetic iron oxide particles are a polyhedron with a hexahedral ridge line or a polyhedron with an octahedral ridge line.

FIG. 3 is a three-dimensional view showing an example in which magnetic iron oxide particles are binuclear particles.

FIG. 4 is a schematic three-dimensional view showing an example in which magnetic iron oxide particles are binuclear particles.

FIG. 5 is an example of a two-dimensional projection showing an outer contour when the magnetic iron oxide particles are dinuclear particles.

FIG. 6 is a three-dimensional view showing an example of a polyhedron in which magnetic iron oxide particles have planar ridge portions.

FIG. 7 is a schematic three-dimensional view showing an example of lateral extrapolation.

FIG. 8 is a schematic explanatory view showing a specific example of an image forming apparatus for performing the image forming method of the present invention.

FIG. 9 is an enlarged view of a developing unit in the image forming apparatus of FIG.

FIG. 10 is a view showing a dissolution rate curve of an element α in a magnetic body 1.

11 is a view showing a dissolution rate curve of an element α in a magnetic body 6. FIG.

FIG. 12 is a view showing a dissolution rate curve of an element α in a magnetic body 7;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Latent image carrier (photoreceptor) 2 Primary charger 3 Transfer charger 4 Developing sleeve 5 Exposure 7 Fixer 13 Magnetic toner 23 Magnet P Transfer paper a, b Arbitrary vertex c Intersection between perpendicular and particle surface d Line segment ab L perpendicular line X side surface Y surface with ridge line part X ₁ side surface X ₂ side surface of extrapolated polyhedron

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Naokuni Kobori 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (32)

[Claims] 1. A magnetic toner having magnetic toner particles containing at least a binder resin and a magnetic material, wherein the magnetic material has an electronegativity of 1.0 to 2.3 after the third cycle of a long-period element periodic table. Element α of 0.15 to 0.10 to 4.0
0 is a magnetic iron oxide having wt%, dissolution rate S ₁ of an iron element dissolution ratio 0-20% elemental α in the magnetic material is less than 10% or more 44%, the iron element dissolution ratio of 80 to 100 % of dissolution rate S ₂ of the element α is more than 5% 30%
Less than 60% by number of dinuclear magnetic iron oxide particles, or (ii) magnetic iron oxide particles whose hexahedral ridges are planar polyhedrons; One or two kinds of magnetic iron oxide particles selected from the group consisting of magnetic iron oxide particles whose octahedral ridges are planar polyhedrons and polynuclear magnetic iron oxide particles have a total content of at least 60% by number. A magnetic toner, comprising: 2. The magnetic toner according to claim 1, wherein the dissolution rate S ₁ and the dissolution rate S ₂ satisfy a relationship of S ₁ ≧ S ₂ . 3. The dissolution rate of an iron element in the magnetic material is 20 to 8.
_3. The magnetic material according to claim 1, wherein the dissolution rate S3 of the element [alpha] obtained by converting the dissolution rate of the element [alpha] of 0% per 20% of the dissolution rate of the iron element is 10% or more and less than 25%. toner. 4. A dissolution rate S ₁ , a dissolution rate S ₂ and a dissolution rate S
_3, the magnetic toner according to claim 3, characterized in that meets _{S 1> S 2, S 1} ≧ S 3, the relationship of S ₃ ≧ S _2. 5. The magnetic material according to claim 5, wherein the element α is 0.15 to 3.0.
00 and contained by weight%, dissolution rate S ₁ is 15% or more 42
Less than%, magnetic toner according to any one of claims 1 to 4, wherein the dissolution rate S ₂ is less than 5% to 25%. 6. The magnetic material according to claim 1, wherein the element α is in the range of 0.20 to 2.
And contained 50 wt%, dissolution rate S ₁ is 20% or more 40
5. The magnetic toner according to claim 1, wherein the dissolution rate S ₂ is less than 10% and less than 20%. 7. The magnetic material having a number average particle size of 0.05 to 0.05.
The magnetic toner according to any one of claims 1 to 6, wherein the thickness is 0.50 µm. 8. The method according to claim 1, wherein said element α is Si, Al, P, V, C
r, Co, Ni, Cu, Zn, Ga, Ge, Zr, S
8. The magnetic toner according to claim 1, wherein the magnetic toner is an element selected from the group consisting of n and Pb. 9. The magnetic toner according to claim 1, wherein the element α is an element selected from the group consisting of Si, Al and P. 10. The magnetic toner according to claim 1, wherein the element α is Si. 11. The weight average particle size is 3.0 to 9.0 μm.
The magnetic toner according to any one of claims 1 to 10, wherein 12. The magnetic toner according to claim 1, wherein the magnetic material is contained in an amount of 20 to 200 parts by weight based on 100 parts by weight of the binder resin. 13. The magnetic toner according to claim 1, wherein the magnetic material is contained in an amount of 40 to 150 parts by weight based on 100 parts by weight of the binder resin. 14. The magnetic toner according to claim 1, wherein the magnetic material is contained in an amount of 50 to 120 parts by weight based on 100 parts by weight of the binder resin. 15. The magnetic toner according to claim 1, having a positive charge property. 16. An image forming method comprising at least a step of forming an electrostatic image on a latent image carrier and a developing step of developing the electrostatic image with a magnetic toner, wherein the magnetic toner comprises at least a binder resin and a magnetic resin. The magnetic material contains an element α having an electronegativity of 1.0 to 2.5 after the third period of the long-period type periodic table of the element, and the magnetic material has a particle size of 0.10 to 4.0. 0
0 is a magnetic iron oxide having wt%, dissolution rate S ₁ of an iron element dissolution ratio 0-20% elemental α in the magnetic material is less than 10% or more 44%, the iron element dissolution ratio of 80 to 100 % of dissolution rate S ₂ of the element α is more than 5% 30%
Less than 60% by number of dinuclear magnetic iron oxide particles, or (ii) magnetic iron oxide particles whose hexahedral ridges are planar polyhedrons; One or two kinds of magnetic iron oxide particles selected from the group consisting of magnetic iron oxide particles whose octahedral ridges are planar polyhedrons and polynuclear magnetic iron oxide particles have a total content of at least 60% by number. An image forming method. 17. The image forming method according to claim 16, wherein the magnetic toner is a positively chargeable magnetic toner. 18. The apparatus according to claim 16, wherein said latent image carrier is an amorphous silicon photosensitive drum.
8. The image forming method according to item 7. 19. The image according to claim 18, wherein said amorphous silicon photosensitive drum is charged to a positive potential to form an electrostatic charge image, and said electrostatic charge image is reversely developed with a positively chargeable magnetic toner. Forming method. 20. The dissolution rate S ₁ and the dissolution rate S ₂ satisfy S ₁ ≧ S ₂
20. The image forming method according to claim 16, wherein the following relationship is satisfied. 21. An iron element dissolution rate of 20 to 20 in the magnetic material.
The dissolution rate of 80% elemental alpha dissolution rate S ₃ of the element in terms of the iron element dissolution rate per 20% alpha, to any one of claims 16 to 20, characterized in that 10% or more and less than 25% The image forming method as described in the above. 22. A dissolution rate S ₁ , a dissolution rate S ₂ and a dissolution rate S ₃
22 satisfies the following relationships: S ₁ > S ₂ , S ₁ ≧ S ₃ , and S ₃ ≧ S ₂ . 23. The magnetic material contains 0.15 to 3.00% by weight of the element α, the dissolution rate S ₁ is 15% or more and less than 42%, and the dissolution rate S ₂ is 5% or more and 25% or less. The image forming method according to any one of claims 16 to 22, wherein the ratio is less than 0.1%. 24. The magnetic material contains 0.20 to 2.50% by weight of the element α, the dissolution rate S ₁ is 20% or more and less than 40%, and the dissolution rate S ₂ is 10% or more and 20% or less. The image forming method according to any one of claims 16 to 22, wherein the ratio is less than 0.1%. 25. The magnetic material having a number average particle size of 0.05
The image forming method according to any one of claims 16 to 24, wherein the thickness is from 0.5 to 0.50 µm. 26. The method according to claim 26, wherein the element α is Si, Al, P, V, C
r, Co, Ni, Cu, Zn, Ga, Ge, Zr, S
The image forming method according to any one of claims 16 to 25, wherein the element is selected from the group consisting of n and Pb. 27. The image forming method according to claim 16, wherein said element α is an element selected from the group consisting of Si, Al and P. 28. The image forming method according to claim 16, wherein said element α is Si. 29. The magnetic toner having a weight average particle size of 3.
29. The image forming method according to claim 16, wherein the thickness is 0 to 9.0 [mu] m. 30. The image forming method according to claim 16, wherein the magnetic material is contained in an amount of 20 to 200 parts by weight based on 100 parts by weight of the binder resin. 31. The image forming method according to claim 16, wherein the magnetic material is contained in an amount of 40 to 150 parts by weight based on 100 parts by weight of the binder resin. 32. The image forming method according to claim 16, wherein the magnetic material is contained in an amount of 50 to 120 parts by weight based on 100 parts by weight of the binder resin.