JPH11194533A - Magnetic toner for developing electrostatic charge image, preparation thereof, image forming method, and process cartridge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic toner excellent in wettability between a binding resin and magnetic fine powder, excellent in mutual dispersibility for ingredients, and providing an image of high quality under both environments of a low temperature.low humidity environment and a high temperature.high humidity environment, and provide a preparation of the toner, an image forming method using the toner, and a process cartridge having the toner. SOLUTION: This toner has a magnetic toner particle containing at least a binding resin, a magnetic fine powder and wax. The magnetic toner particles have 3.5-6.5 μm of weight average particle size, and a dispersion solution in which 15 mg of the magnetic toner particles are dispersed into 19 ml of a mixture comprising ethyl alcohol and water (27:73 by volume ratio) has 0.2-0.7 of absorbance in 600 nm of wave length.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic toner for forming a toner image by developing an electrostatic image in an image forming method such as electrophotography, a method of manufacturing the same, and an image forming method using the magnetic toner. And a process cartridge having the magnetic toner.

[0002]

2. Description of the Related Art In recent years, the functions of image forming apparatuses using electrophotography, such as copying machines and laser beam printers, have become more versatile, and there has been a demand for higher definition and higher image quality.

Accordingly, magnetic toner particles tend to use finer particles than ever before. However, when the particle size of the magnetic toner particles is reduced, high definition of the image can be achieved. However, particularly in a low-temperature and low-humidity environment, the fogging phenomenon due to the adhesion of the magnetic toner to the non-image portion tends to occur. Further, in a high-temperature and high-humidity environment, image density tends to be low in copying or printing at the first time in the morning. Furthermore, a method of charging a photoreceptor with a contact charging member without using a corona charger that generates ozone has recently been adopted due to consideration of environmental issues.

However, in this case, in a low-temperature and low-humidity environment, charging occurs due to fine particles of magnetic toner that are not sufficiently cleaned by the cleaning member adhering to the contact charging member (hereinafter referred to as “charging roller contamination”). This may cause a defective image. Further, in a high-temperature and high-humidity environment, a phenomenon (hereinafter, referred to as "drum fusion") occurs in which the above-described fine particles are compressed by a charging member and adhere to the surface of a photosensitive drum serving as an electrostatic image holder. It will be easier.

It has been confirmed that these fine particles are mainly silica fine powder used as a fluidity improver and / or magnetic fine powder which is a constituent material of magnetic toner particles. Further, as described above, in the case of a magnetic toner having a smaller diameter than before, the magnetic fine powder tends to adhere more to the contact charging member and the photosensitive drum.

[0006] In order to improve the adhesion between the binder resin and the magnetic fine powder, a method of previously treating the surface of the magnetic fine powder with an organic substance has been known. However, a toner carrier in a low-temperature and low-humidity environment has been known. Coating defects (blotch phenomenon) on the magnetic toner layer tend to occur thereon. Further, the surface treatment of the magnetic fine powder causes an increase in production cost.

[0007] As means for solving the above problems, there is a long-awaited proposal of a new toner and a new manufacturing method in which the state of existence of magnetic fine powder present on the surface of magnetic toner particles is controlled.

As for the binder resin, it is difficult to uniformly disperse all the raw materials such as magnetic fine powder and wax in the kneaded material.
For example, the kneading conditions in consideration of the wettability of the binder resin and the magnetic fine powder and the kneading conditions in consideration of the dispersibility of the binder resin and the wax generally have an opposite relationship.

In Japanese Patent Application Laid-Open No. 8-123083,
There has been proposed a method for producing a toner in which temperature conditions for melt-kneading using a screw extruder having a feed screw portion and a kneading portion are specified. In the examples of this publication, the volume average particle size (d ₅₀ ) is 7.15 to 7.2.
Although a method for producing a 3 μm magnetic toner is described, even with this production method, when the average particle diameter of the magnetic toner becomes smaller (for example, 5 μm), the magnetic fine particles are released from the surface of the magnetic toner particles. This tends to increase the number of free magnetic fine particles. Furthermore, in this manufacturing method, the temperature at the outlet side of the kneaded material of the extruder is set low, but this is a condition in which the heated kneaded material is forcibly cooled in the extruder, and it is generally difficult to control the temperature. In many cases, the load is large and process management in actual production is difficult.

[0010]

SUMMARY OF THE INVENTION An object of the present invention is to provide a magnetic toner which is less likely to generate fog and is less likely to cause poor charging in a low-temperature and low-humidity environment, and a method for producing the same.

It is a further object of the present invention to provide a magnetic toner capable of forming an image having a high image density in a high-temperature and high-humidity environment and suppressing the occurrence of drum fusion on the surface of a photosensitive drum, and a method of manufacturing the same. It is in.

It is a further object of the present invention to provide a magnetic toner having a small weight average particle diameter and less release of magnetic fine particles from the magnetic toner particles, and a method for producing the same.

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

Another object of the present invention is to provide a process cartridge having the magnetic toner.

[0015]

SUMMARY OF THE INVENTION The present invention is a magnetic toner for developing an electrostatic charge image having magnetic toner particles containing at least a binder resin, magnetic fine powder and wax, wherein the magnetic toner particles are 3.5-6.5μ average particle size
m; a mixture of ethyl alcohol and water (volume ratio 2
7:73) The present invention relates to a magnetic toner for developing an electrostatic image, wherein a dispersion of 15 mg of the magnetic toner particles in 19 ml has an absorbance at a wavelength of 600 nm of 0.2 to 0.7.

Further, the present invention relates to a method for producing a magnetic toner having magnetic toner particles containing at least a binder resin, a magnetic fine powder and a wax, and a mixture comprising at least the binder resin, the magnetic fine powder and a wax. The following conditions 2.2 × 10 ³ ≦ E / ε ≦ 2.0 × 10 ⁴ E = kω ² T, ε = F / (πD ² L) where k is the screw rotation speed (m / Min), T indicates a set temperature (K), F indicates a supply amount of a mixture (kg / min), D indicates a cylinder inner diameter (m), and L indicates an effective screw length (m). , Π indicate the pi, k indicates (D ₀ / D) ² , and D ₀ is 0.1 m. ), The kneaded product is cooled, the cooled product is pulverized, and the pulverized product is classified to obtain magnetic toner particles. The magnetic toner particles have a weight average particle size of 3.5 to 6 The magnetic toner particles 15 were added to 19 ml of a mixture of ethyl alcohol and water (volume ratio 27:73).
The present invention relates to a method for producing a magnetic toner, characterized in that the absorbance at a wavelength of 600 nm of a dispersion liquid in which mg is dispersed is 0.2 to 0.7.

Further, according to the present invention, the electrostatic image carrier is charged by contact charging means to which a bias is applied, an electrostatic image is formed on the charged electrostatic image carrier by exposure, and the magnetic toner is provided. An image forming method for developing the electrostatic charge image by a developing unit to form a magnetic toner image,
The magnetic toner has magnetic toner particles containing at least a binder resin, a magnetic fine powder and a wax, and the magnetic toner particles have a weight average particle diameter of 3.5 to 6.5 μm.
m; a mixture of ethyl alcohol and water (volume ratio 2
7:73) The present invention relates to an image forming method, characterized in that a dispersion obtained by dispersing 15 mg of the magnetic toner particles in 19 ml has an absorbance at a wavelength of 600 nm of 0.2 to 0.7.

Further, the present invention provides a process which comprises an electrostatic image holder, a contact charging means for charging the electrostatic image holder, and a developing means for holding a magnetic toner, and which is detachable from an image forming apparatus main body. A cartridge, wherein the magnetic toner has magnetic toner particles containing at least a binder resin, a magnetic fine powder and a wax, and the magnetic toner particles have a weight average particle diameter of 3.5 to 6.5 μm. Yes; mixture of ethyl alcohol and water (volume ratio 27:73) 19
The present invention relates to a process cartridge, characterized in that a dispersion obtained by dispersing 15 mg of the magnetic toner particles per ml has an absorbance at a wavelength of 600 nm of 0.2 to 0.7.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION A magnetic toner constituting a magnetic toner which easily causes contamination of a charging roller as one of the contact charging means and fusion of the toner on the surface of a photosensitive drum as one of the electrostatic image holders. We examined means to easily determine the difference between toner particles and magnetic toner particles that are unlikely to cause the same problem by a method other than image evaluation, and found that magnetic toner particles were dispersed in a mixture of ethyl alcohol and water. It has been found that the difference can be known by a method using the obtained dispersion. The high absorbance of the dispersion indicates that the magnetic toner particles are in a state of being very easily wetted by the mixed solution, indicating that a large amount of magnetic fine powder is present on the surface of the magnetic toner particles. Such magnetic toner particles tend to release magnetic fine particles from the surface thereof. Actually, when a magnetic toner produced from such magnetic toner particles is imaged and evaluated, adverse effects such as contamination of the charging roller and fusion to the surface of the photosensitive drum are likely to occur. It was confirmed that a large amount of magnetic fine particles were present in the contaminants on the charging roller surface and in the fused material on the photosensitive drum surface. This can be said to be a measurement method that clearly and appropriately indicates the amount of magnetic fine powder present on the surface of magnetic toner particles.

The magnetic toner particles used in the present invention have a weight average particle diameter of 3.5 to 6.5 μm, and a mixture of ethyl alcohol and water (volume ratio of ethyl alcohol and water 27:73) 19 ml The dispersion having 15 mg of the magnetic toner particles dispersed therein has an absorbance at a wavelength of 600 nm of 0.2.
To 0.7.

The weight average particle size of the magnetic toner particles or the magnetic toner is measured by a Coulter counter method.

As an apparatus for measuring the average particle size of the magnetic toner particles and the magnetic toner by the Coulter counter method, for example, a Coulter Counter TA-II or a Coulter Multisizer (manufactured by Coulter Inc.) is used. As the electrolyte, about 1% NaCl aqueous solution is prepared using primary sodium chloride. For example, ISOTON-II (manufactured by Coulter Inc.) can be used. As a measuring method, a surfactant (preferably an alkylbenzene sulfonate) is used as a dispersant in 100 to 150 ml of the electrolytic aqueous solution.
Add 0.1 to 5 ml, and further add 2 to 20 mg of the measurement sample. The electrolyte in which the sample was suspended was mixed with an ultrasonic
Then, the volume and the number of the magnetic toner particles or the magnetic toner are measured by the measuring device using a 100 μm aperture as the aperture, and the volume distribution and the number distribution are calculated. Then, the weight average particle diameter (D4) based on the weight of the magnetic toner particles or the magnetic toner is determined.

As the channels, 2.00 to 2.52
less than 2.5 μm; less than 2.52 to 3.17 μm;
4. less than 4.00 μm; 4.00 to less than 5.04 μm;
04 to less than 6.35 μm; 6.35 to less than 8.00 μm; 8.00 to less than 10.08 μm; 10.08 to 1
2.70 μm or less; 12.70 to less than 16.00 μm;
16.00 to less than 20.20 μm; 20.20 to 25.
Less than 40 μm; 25.40 to less than 32.00 μm; 3
Thirteen channels of 2.00 to less than 40.30 μm are used, and particles having a particle size of 2.00 μm or more to less than 40.30 μm are targeted.

In the above-mentioned measuring method, the weight average particle diameter of the magnetic toner usually has substantially the same value as the weight average particle diameter of the magnetic toner particles even when the external additive is externally added to the magnetic toner particles. Show.

The absorbance of the magnetic toner particles is measured by the following method.

I) Preparation of Dispersion An aqueous solution having a mixing ratio of 27:73 of ethyl alcohol (special grade 99.5%, manufactured by Kishida Chemical) and water is prepared. 19 ml of this aqueous solution was added to a 20 ml sample bottle (iuchi
(Trade name, Labo Run Pack)
mg on the liquid surface and cover the bottle. 20 in that state
Let stand for minutes. Over time, the wettable particles begin to fall and disperse in the solution. After the elapse of 20 minutes, the sample bottle is grasped with a finger, and the sample bottle is shaken up and down five times 180 ° to make the dispersion liquid uniform to obtain a dispersion liquid for measurement.

Ii) Absorbance measurement The dispersion obtained in i) is placed in a 1 cm square quartz cell, and the absorbance of the dispersion at a wavelength of 600 nm is measured using a spectrophotometer MPS2000 (manufactured by Shimadzu Corporation).

When the absorbance is larger than 0.7, a large amount of magnetic fine particles are present on the surface of the magnetic toner particles, and free magnetic fine particles are easily generated, so that the charging roller becomes dirty and the drum is easily fused. When the absorbance is smaller than 0.2, the exposure of the magnetic fine particles to the surface of the magnetic toner particles is excessively suppressed. Problems are easy to occur. The absorbance is preferably between 0.30 and 0.
69, more preferably 0.35 to 0.65.

The magnetic toner particles have a weight average particle diameter (D ₄ ) of 3.5 to 6.5 μm. If the particle diameter is larger than 6.5 μm, it is difficult to achieve high image quality.
If the particle size is smaller, increase in fog, low density, and lower productivity are likely to occur.

The content of the magnetic powder in the magnetic toner particles is 4
It is preferably from 0 to 60% by weight. When the amount of the magnetic fine powder in the magnetic toner particles is smaller than 40% by weight, it is difficult to suppress an increase in fog in a magnetic toner having a smaller weight average diameter of the magnetic toner particles than in the related art. When the amount is large, the image density is reduced or free magnetic fine particles are easily generated, and the charging roller contamination and drum fusion due to the increase of free magnetic fine particles are easily generated.

The magnetic toner particles have a shape factor SF-1 value measured by an image analyzer of 140 <SF-1 ≦ 180 and a shape factor SF-2 value of 130 <SF-2 ≦ 17.
It is preferably 0.

When the shape factor SF-1 or SF-2 of the magnetic toner particles is 130 or less, the surface of the magnetic toner particles is in a smooth state. This phenomenon tends to occur, and the image density becomes low or the blotch phenomenon easily occurs in a low-temperature and low-humidity environment. Shape factor S of magnetic toner particles
When F-1 is larger than 180, the fluidity of the magnetic toner tends to decrease, and the image density tends to decrease. When the shape factor SF-2 of the magnetic toner particles is larger than 170, it is difficult to obtain uniform charging, and fogging tends to occur.

In the present invention, the shape factors SF-1, SF
-2 means, for example, FE-SEM (S-80) manufactured by Hitachi, Ltd.
0), 100 toner particle images having a particle diameter of 2 μm or more obtained by enlarging the magnetic toner particles 1000 times are randomly sampled, and the image information is obtained through an interface.
For example, an image analyzer (Luzex III) manufactured by Nicole
The values obtained by the following equation are defined as shape factors SF-1 and SF-2.

[0034]

[Outside 1] (Where MXLNG is the absolute maximum length of the particle, PERIME
Indicates the periphery of the particle, and AREA indicates the projected area of the particle. )

The shape factor SF-1 indicates the degree of roundness of the toner particles, and the shape coefficient SF-2 indicates the degree of unevenness of the toner particles.

More preferably, the ratio of the shape factor SF-1 to SF-2 (SF-1 / SF-2) of the magnetic toner particles is 1.01 to 1.20. More preferably, the magnetic toner particles have a shape factor SF-1 of 145 to 1
60, and SF-2 is preferably 135 to 155, and the ratio of the shape factor SF-1 to SF-2 (SF
−1 / SF−2) is preferably 1.05 to 1.15.

When the SF-1 and SF-2 of the magnetic toner in which the external additive is externally added to the magnetic toner particles are measured, the particle size of the external additive is very small or large. Since the number of external additives is small, SF-1 and SF of magnetic toner particles
A value substantially the same as -2 is generally indicated.

In the magnetic toner of the present invention, 795.
The product (σ _r × H _C ) of the residual magnetization [σ _r (Am ² / kg)] and the coercive force [H _C (kA / m)] of the magnetic fine powder under a magnetic field of 8 kA / m (10 k Oersted) is 24. ~ 56
(KA ² m / kg).

As a developing method in which the magnetic toner of the present invention is preferably used, a magnet is provided in a toner carrier, the magnetic toner is held by the magnet, and the toner is triboelectrically charged on the toner carrier, and the charged magnetic toner is charged with an electrostatic charge. There is a method of developing an electrostatic image on the image carrier. In such a developing method, when magnetic toner particles having a weight average particle size of 3.5 to 6.5 μm constituting the magnetic toner of the present invention are used, fog in a low-temperature and low-humidity environment, and a solid black density during endurance. A thin drum phenomenon and a drum fusion phenomenon easily occur in a high temperature and high humidity environment. These issues are
The problem can be solved effectively by controlling the magnetic force (σ _r × H _C ) of the magnetic fine powder. In a low-temperature, low-humidity environment, magnetic force is applied to the magnetic toner so that the development of the magnetic toner with a high triboelectric charge can be suppressed, thereby maintaining the image density and better preventing fog. can do.

Furthermore, by appropriately constraining the magnetic toner on the surface of the toner carrier with a magnetic constraining force, circulation of the magnetic toner on the surface of the toner carrier is improved, and excessive charging of the magnetic toner in a low-temperature and low-humidity environment is achieved. It is possible to prevent the phenomenon of low solid black density at the time of durability, which is considered to be the cause. Further, even in a high-temperature and high-humidity environment, magnetic toner particles having a high triboelectric charge amount are easily developed selectively. As the diameter of the magnetic toner particles is reduced, the drum fusion phenomenon is more likely to occur. In this case as well, it can be prevented by applying a magnetic force to the magnetic toner that can suppress the development of the magnetic toner particles having a relatively high triboelectric charge.

When a magnetic fine powder having σ _r × H _C of less than 24 is used, the magnetic binding force does not work effectively.
In a low-temperature and low-humidity environment, fogging easily occurs, and a solid black density thin phenomenon during durability tends to occur. In a high-temperature and high-humidity environment, a drum fusion phenomenon easily occurs. On the other hand, when σ _r × H _C exceeds 56, the magnetically constraining force becomes dominant, and the image density tends to decrease in all environments, which is not preferable. A more preferred range is 30 to 52. In the present invention, the magnetic characteristics are VSMP-1-10
(Toei Kogyo Co., Ltd.) using an external magnetic field of 795.8 kA /
m was measured.

The magnetic fine powder used in the magnetic toner of the present invention includes magnetic metal oxides containing elements such as iron, cobalt, nickel, copper, magnesium, manganese, aluminum and silicon. The number average particle diameter of these magnetic fine powders is preferably 0.05 to 0.30 μm, and more preferably 0.10 to 0.25 μm. If the number average particle size is smaller than 0.05 μm, the color of the magnetic fine powder tends to be reddish, and the color of the magnetic toner is not preferable because it is reflected in the color of the image. On the other hand, if the number average particle diameter is larger than 0.30 μm, the image density and the fog latitude become narrow, which is not preferable.

The shape of the magnetic fine particles constituting the magnetic fine powder used in the present invention includes an octahedron, a hexahedron, and a sphere. The shape of the magnetic fine particles is preferably spherical because the image density and the latitude of fog can be widened.

Further, in order to satisfy the object of the present invention at a higher level, the magnetic fine particles constituting the magnetic fine powder have silicon dioxide on at least the surface, and the weight% of the silicon dioxide present on the surface is When W (%) and the number average particle size of the magnetic fine powder are R (μm), W × R preferably satisfies 0.003 to 0.042. Hereinafter, W × R will be described.

(A) Measurement method of W: The silicon dioxide (SiO ₂ ) present on the surface of the magnetic fine particles constituting the magnetic fine powder is eluted with a 2N-NaOH solution (40 ° C., 30 minutes). The amount of SiO ₂ in the magnetic fine powder before and after elution is determined by fluorescence X
Measured by line analysis. W (%) = [(SiO ₂ amount before elution−SiO ₂ after elution)
Amount) / (weight of magnetic fine powder before elution)] × 100

(B) Measurement method of R : R was taken with a transmission electron microscope to take a photograph of the magnetic fine particles constituting the magnetic fine powder, and after arbitrarily selecting 250 particles per 40,000-fold magnification, The Martin diameter (the length of a line segment that bisects the projected area in a fixed direction) in the projected diameter is measured, and the number average particle diameter is calculated based on the measured value.

By defining the value of W × R, it is possible to more clearly grasp whether the presence state of SiO _{2 on} the surface of the magnetic fine particles is dense or coarse.

First, assuming that the specific surface area determined from the average particle size of the magnetic fine powder is S and the density of the magnetic fine powder is ρ, S = 4πR ² × [1 / (4/3) πR ³ · ρ] = 3
/ R · ρ. The existence state of SiO _{2 on} the surface is
Actually, it is given by W / S = R · W · ρ / 3. The preferred range of W / S is 0.001ρ ≦ W / S ≦ 0.014ρ
Therefore, 0.001ρ ≦ RW · ρ / 3 ≦ 0.01
4ρ, and when the equation is simplified, 0.003 ≦ W × R ≦
0.042.

When W × R is smaller than 0.003, the presence of SiO _{2 on} the surface of the magnetic fine powder particles is in a very sparse state. Under this condition, the image density tends to decrease and the fog tends to increase. When W × R is larger than 0.042, the wettability between the binder resin and the magnetic fine powder during kneading decreases,
The magnetic fine powder easily separates from the magnetic toner particles during the production of the toner, and drum fusion due to the released magnetic fine powder easily occurs. A more preferable range of W × R is 0.
008 to 0.035.

The content of the magnetic fine powder in the magnetic toner particles is preferably 40 to 60% by weight. When the amount is less than 40% by weight, it is difficult to suppress the fogging phenomenon in the magnetic toner particles having a weight average particle diameter of 3.5 to 6.5 μm. Roller dirt and drum fusing easily occur.
More preferably, the content of the magnetic fine powder in the magnetic toner particles is preferably 45 to 55% by weight.

The magnetic toner particles of the magnetic toner of the present invention include:
Contains wax. Examples of the wax include paraffin wax and its derivatives, microcrystalline wax and its derivatives, Fischer-Tropsch wax and its derivatives, polyolefin wax and its derivatives, carnauba wax and its derivatives long-chain carboxylic acids and its derivatives, and long-chain alcohols and their derivatives. No. Derivatives include oxides, block copolymers of vinyl monomers and waxes, and graft modified products of vinyl monomers and waxes.

The wax preferably used in the present invention is:
Gel permeation chromatography of a wax represented by the formula RY (wherein R represents a hydrocarbon group, Y represents a hydroxyl group, a carboxyl group, an alkyl ether group, an ester group or a sulfonyl group) (GPC)
Weight average molecular weight (Mw) is preferably 3,000 or less.

The following are specific examples of the compounds. (A) CH ₃ (CH ₂ ) _n CH ₂ OH (n = 20-30)
0) (B) CH ₃ (CH ₂ ) _n CH ₂ COOH (n = 20 to
300) (C) CH ₃ (CH ₂ ) _n CH ₂ OCH ₂ (CH ₂ ) _{m
CH 3 (n = 20~200, m} = 0~100)

The compounds (B) and (C) are the same as the compound (A)
Wherein the main chain is a linear saturated hydrocarbon.
As long as it is a compound derived from the above compound (A), those other than those shown in the above examples can also be used. Particularly preferred wax is CH ₃ (CH ₂ ) _n OH (n = 20-300)
Wherein the main component is a long-chain alkyl alcohol represented by the formula: and mixtures thereof.

When this long-chain alkyl alcohol wax is used, the dispersibility of the binder resin and the wax at the time of kneading is very good. Need not be set, and conditions can be set in consideration of the wettability between the binder resin and the magnetic fine powder.

In general, under the conventional kneading conditions, the kneading temperature immediately after the kneaded material is discharged from the kneader is an important parameter for knowing the kneading state. Even under kneading conditions in which the kneading temperature is 30 to 70 ° C. higher than the softening point of the long-chain alkyl alcohol wax, the dispersibility of the wax in the binder resin is good, and in such a case, The wettability with the magnetic fine powder is also improved, and the object of the present invention can be achieved more favorably. See FIG.

The binder resin used in the magnetic toner of the present invention will be described below.

Examples of the binder resin for the toner used in the present invention include: polystyrene; styrene-substituted homopolymers such as poly-p-chlorostyrene and polyvinyltoluene; styrene-p-chlorostyrene copolymer; Styrene-vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, styrene-acrylate copolymer,
Styrene-methacrylate copolymer, styrene-
α-chloromethyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene vinyl methyl ether copolymer, styrene-vinyl ethyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, Styrene copolymers such as styrene-isoprene copolymer and styrene-acrylonitrile-indene copolymer; polyvinyl chloride, phenolic resin, naturally modified phenolic resin, naturally modified maleic acid resin, acrylic resin, methacrylic resin, polyvinyl acetate, Examples include silicone resin, polyester resin, polyurethane, polyamide resin, furan resin, epoxy resin, xylene resin, polyvinyl butyral, terpene resin, coumarone indene resin, and petroleum resin. Crosslinked styrenic resins are also preferred binder resins.

Examples of comonomers for the styrene monomer of the styrene copolymer include acrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, dodecyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, phenyl acrylate, and the like. Monocarboxylic acid having a double bond such as methacrylic acid, methyl methacrylate, ethyl methacrylate, butyl methacrylate, octyl methacrylate, acrylonitrile, methacrylonitrile, acrylamide or a substituted product thereof; maleic acid, butyl maleate, maleic acid Dicarboxylic acids having a double bond such as methyl acrylate and dimethyl maleate and substituted products thereof: vinyl esters such as vinyl chloride, vinyl acetate and vinyl benzoate; ethylene such as ethylene, propylene and butylene Olefins; vinyl methyl ketone, vinyl ketones such as vinyl hexyl ketone, vinyl methyl ether, vinyl ethyl ether, vinyl ethers such as vinyl isobutyl ether.
These vinyl monomers are used alone or in combination with the styrene monomer. As the crosslinking agent, a compound having two or more polymerizable double bonds is mainly used. For example, aromatic divinyl compounds such as divinylbenzene and divinylnaphthalene; carboxylic acid esters having two double bonds such as ethylene glycol diacrylate, ethylene glycol dimethacrylate, and 1,3-butanediol dimethacrylate; divinylaniline; 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 in combination.

Further, the styrene resin has a molecular weight distribution of at least 0.5 × 10 5 in the molecular weight distribution measured by gel permeation chromatography (GPC).
⁴ to 5 × 10 ⁴ and a molecular weight of 1.0 × 10 ⁵ ~5.0 × 1
0 is preferably used, optionally having a main peak and sub-peak in the ⁶ regions of. The styrene resin has a weight-average molecular weight (Mw) of a soluble component of tetrahydrofuran (THF) of 1.5 × 10 ^{5 to 3.5} × 10 ⁵ , more preferably 1.8 × 10 ^{5 to} 3.2 ×. 10 ⁵ is good.

In the magnetic toner of the present invention, it is preferable to use an organometallic compound as a charge control agent. Among the organometallic compounds, those containing an organic organic compound which is particularly rich in vaporizability or sublimability as a ligand or a counter ion are useful.

As such an organometallic compound, there is an azo-based metal complex represented by the following general formula.

[0063]

[Outside 2] [In the above general formula, M represents a coordination center metal and has a coordination number of 6
Cr, Co, Ni, Mn, Fe, Al, Ti, Sc or V. Ar is an aryl group, and may have a substituent such as a phenyl group or a naphthyl group. Examples of the substituent include a nitro group, a halogen group, a carboxyl group, an anilide group, and an alkyl or alkoxy group having 1 to 18 carbon atoms. X, X ', Y and Y' are -O
-, -CO-, -NH- or -NR- (R is a carbon number of 1 to
4 alkyl group).

[0064]

[Outside 3] Represents a hydrogen ion, a sodium ion, a potassium ion, an ammonium ion, an aliphatic ammonium ion or a mixed ion thereof. ]

Specific examples of the complex which is preferably used in the present invention are shown below.

[0066]

[Outside 4]

[0067]

[Outside 5]

[0068]

[Outside 6]

The charge control agent is preferably added in the range of 0.2 to 5 parts by weight based on 100 parts by weight of the magnetic toner.

In the magnetic toner, it is preferable to externally add an inorganic fine powder to the magnetic toner particles in order to improve charge stability, developability, fluidity, and durability.

Examples of the inorganic fine powder include silica fine powder, titanium oxide fine powder, and alumina fine powder. Particularly, inorganic fine powder having a specific surface area of 30 m ² / g or more (particularly 50 to 400 m ² / g) by nitrogen adsorption measured by the BET method gives a good result. Magnetic toner 1
It is preferable to use 0.01 to 8 parts by weight, preferably 0.1 to 5 parts by weight of the inorganic fine powder with respect to 00 parts by weight.

The inorganic fine powder may be used, if necessary, for the purpose of hydrophobization and charge control, such as silicone varnish, various modified silicone varnishes, silicone oil, various modified silicone oils, silane coupling agents, and silane cups having functional groups. It is also preferable to be treated with a treating agent such as a ring agent or another organosilicon compound. Two or more treatment agents may be used. Particularly, silica fine powder surface-treated with silicone oil is preferable.

As other additives, lubricants such as Teflon, zinc stearate, polyvinylidene fluoride and silicone oil particles (containing about 40% of silica) are preferably used. Further, abrasives such as cerium oxide, silicon carbide, calcium titanate and strontium titanate are preferably used, and among them, strontium titanate is preferred. Also, an anti-caking agent: carbon black,
Conductivity imparting agents such as zinc oxide, antimony oxide, and tin oxide; white and black fine particles having a polarity opposite to that of the magnetic toner particles may be used in a small amount as a developability improver.

Next, a method for producing magnetic toner particles used in the magnetic toner will be described.

As the kneading machine used in the present invention, it is preferable to knead using an extruder in response to recent mass production of magnetic toner. In particular, a twin-screw extruder is a preferable kneader from the viewpoint of quality stability and mass productivity. Specific examples include TEM-100B (manufactured by Toshiba Machine) and PCM-87 (manufactured by Ikegai Iron Works).

In the present invention, in the melt-kneading step for producing magnetic toner particles, a mixture containing at least a binder resin, a magnetic fine powder and a wax is mixed with a kneader under the following condition: 2.2 × 10 ³ ≦ E / ε ≦ 2.0 × 10 ⁴ E = kω ² T, ε = F / (πD ² L) [where, ω indicates a screw rotation speed (m / min), T indicates a set temperature (K), and F Indicates the supply amount of the mixture (kg / min), D indicates the cylinder inner diameter (m), L indicates the screw effective length (m), π indicates the pi, and k indicates (D ₀ / D). ² and D ₀ is 0.1 m. ] Is preferable.

The kneading condition is defined by the value of E / ε because it is an effective value as an index for judging the wettability between the binder resin and the magnetic fine particles constituting the magnetic fine powder at the time of kneading. . It can be said that when E / ε is large, wettability increases. E is the product of the square value of the rotational speed ω of the screw of the kneader and the kneading set temperature T, and can be regarded as a value representing the kneading energy of the kneader. ω ² is a value correlated with the kinetic energy of the screw, and the set temperature T is a value correlated with the heat energy supplied by the kneader. If the kneading state when the raw materials are kneaded by the kneading machine is to be grasped by a physical quantity, it is considered that there is a close relationship with the sum of the kinetic energy and the heat energy supplied from the kneading machine. The reason why the product is multiplied by ω ² T is that consideration is given so that the difference in the kneading state can be grasped more clearly.

K is a correction constant. From experience, wettability
This is because a kneader having a smaller cylinder inner diameter tends to be more improved than a kneader having a cylinder inner diameter of 0.1 m.

Ε = F / (πD ² L) where F is the amount of raw material supplied per unit time, and πD ² L is a value that has a correlation with the possible volume of the raw material in the cylinder of the kneader. ε
Indicates the fullness of the raw material in the cylinder. ε
Large means that the state of charge is high. If the kneading energy is the same, if the ε is large, the kneading energy per unit weight per unit time tends to decrease, and in fact, the wettability between the binder resin and the magnetic fine powder tends to decrease. .

As described above, E / ε is a kneading state for producing fine magnetic toner particles having a weight average particle diameter of 3.5 to 6.5 μm, and a screw rotation speed which is a basic kneading condition. Focusing on parameters such as set temperature, set temperature, discharge rate, and internal volume of the cylinder, they are defined from two viewpoints: kneading energy and the degree of fullness of the raw material that can be given the energy in the kneading machine.

When E / ε is smaller than 2.2 × 10 ³ , the wettability between the binder resin and the magnetic fine powder is reduced, and free magnetic fine powder is easily generated in the pulverizing step. The magnetic toner is liable to cause contamination of the charging roller and fusing of the drum.
When E / ε is larger than 2.0 × 10 ⁴ , the dispersibility of the binder resin and the wax tends to decrease, and fog in a low-temperature / low-temperature environment tends to occur.

The range of the value of each parameter specified in the kneading conditions is determined in consideration of the type of the kneading machine used.

Ω indicates the screw rotation speed (m / min), and is preferably used in the range of 5 to 50. T indicates a set temperature (K), and the range of 333 to 513 is favorably used. F represents the supply amount of the mixture (kg / min),
The range of 0.15 to 25 is preferably used. D indicates the cylinder inner diameter (m), and the range of 0.03 to 0.2 is preferably used. L represents the screw effective length (m),
The range of 1.00 to 4.00 is preferably used. π is pi, k indicates (D ₀ / D) ² , and D ₀ is 0.1
[M]. Further, the value of E = kω ² T is preferably 3.0 × 10 ^{5 to} 16.0 × 10 ⁵ , and the supply amount F of the mixture is preferably 0.30 to 12.0 (kg / kg).
min) is good, the value of ε = F / (πD ² L) is preferably 85 to 130, and the value of E / ε is preferably 2.
5 × 10 ^{3 to} 1.5 × 10 ⁴ are good.

When setting the kneading conditions, various kneading paddle configurations for the shaft screw are conceivable. Preferably, the kneading region is set at two locations: a region where melting starts and a region where dispersibility is improved. Is the case.
The kneaded material is subjected to rolling and cooling, coarse pulverization, fine pulverization by a jet stream, and classification by a multi-division method shown in FIG. 7 to obtain magnetic toner particles by a conventionally known method. Regarding the dispersibility of the magnetic fine powder and the wax of the magnetic toner particles, the amount of the magnetic fine powder and the amount of the wax in the classified fine powder of the M powder magnetic toner particles and the F powder in FIG. You can know that.

I) Dispersibility of Magnetic Fine Powder For example, the density value M of the magnetic toner particles of the M powder is measured by using a densitometer Acupic 1330 (Shimadzu Corporation),
The dispersion state can be known from the ratio F / M with the density value F of the classified fine powder. It can be determined that as the value of F / M deviates from 1, the uniform dispersibility of the magnetic fine particles constituting the magnetic fine powder in the binder resin decreases.

Ii) Dispersibility of wax In a DSC curve measured by a differential scanning calorimeter (manufactured by PerkinElmer), the area of the endothermic peak curve and the area enclosed by the base line is determined by the DS of magnetic toner particles of M powder.
From the ratio F / M of the area value M obtained from the C curve to the area value F obtained from the DSC curve of the classified fine powder of the F powder, it is possible to know the uniform dispersibility of the wax in the binder resin. is there. As the value of F / M deviates from 1, it can be determined that the dispersibility is reduced.

As an example of an airflow classifier that can be used for preparing the magnetic toner particles of the present invention, a specific example of an apparatus of the type shown in FIGS. 7 (cross-sectional view) and FIGS. 8 and 9 (perspective view) is shown. .

In the airflow classification device and the air classification system using the device, high-pressure air is introduced into the rear end of the raw material supply nozzle which is preferably installed at an angle of θ = 45 ° or less with respect to the vertical direction. A pipe and a powder material introduction nozzle are provided, and a powder material to be magnetic toner particles is supplied from a material supply port provided above the powder material introduction nozzle, and the supplied powder material is supplied from a lower portion of the powder material introduction port. The powder raw material radiated from the outer periphery of the high-pressure air introduction pipe, accelerated by the high-pressure air, is dispersed well, and the powder material dispersed well can be supplied to the raw material supply nozzle. When the shape of the classification area is changed, the classification area is expanded, the classification point can be changed significantly, and the classification point can be adjusted with high accuracy without generating airflow turbulence near the end of the classification edge. It is. The principle of suction and discharge of the powder raw material in the powder raw material supply section is based on the expansion / decompression ejector effect of the high pressure air from the high pressure air introduction pipe at the powder raw material supply nozzle.

In FIG. 7, FIG. 8 and FIG.
2 and 123 form part of a classification chamber, and classification edge blocks 124 and 125 have classification edges 117 and 118. Classification edges 117 and 118 correspond to axis 11
It is rotatable around 7a and 118a, and the classification edge can be rotated to change the classification edge tip position. Each of the classification edge blocks 124 and 125 can be slid up and down, and accordingly, each knife edge type classification edge 117 can be slid.
And 118 also slide up and down. This classification edge 11
According to 7 and 118, the classification zone of the classification room 132 is divided into three.

Raw material supply port 14 for introducing powder raw material
0 at the last end of the raw material supply nozzle 116, a high pressure air introduction pipe 141 and a powder raw material introduction nozzle 142 having a powder raw material supply section at the rear end of the raw material supply nozzle 116, and a classification chamber. Material supply nozzle 1 having an opening at 132
16 is provided on the right side of the side wall 122.
6 is provided with a Coanda block 126 that draws a long elliptical arc with respect to the extension direction of the right tangent to the right. The left block 127 of the classifying chamber 132 has a knife-edge type inlet edge 114 on the left side of the classifying chamber 132, and further includes a classifying chamber 1.
On the left side of 32, there are provided air inlet pipes 114 and 115 which open to a classification chamber 132. The first and second gas introduction adjusting means 120 and 121 such as dampers, the static pressure gauge 128 and the static pressure gauge 129 are provided in the intake pipes 114 and 115.
Is provided.

The pressure of the high-pressure air introduced into the high-speed air introduction pipe 141 is 1.0 to 3.0 Kg / c in ordinary classification.
m ² , the pressure of the high-pressure air is higher than 3.0 kg / cm ² , and preferably 3.0 in order to efficiently release and remove the magnetic fine particles adhering to the surface of the magnetic toner particles. It is preferably 5 to 6.0 Kg / cm ² . Classification edges 117 and 118 and inlet edge 119
Is adjusted according to the type and desired particle size of the magnetic toner particles.

On the right side of the classifying chamber 132, the outlets 111, 11 opening into the classifying chamber corresponding to the respective dividing areas.
2 and 113, and outlets 111, 112 and 113
Are connected to communication means such as pipes, and each may be provided with opening and closing means such as valve means.

The raw material supply nozzle 116 is composed of a right-angled cylinder and a pyramid-shaped cylinder. The ratio of the inner diameter of the right-angled cylinder to the innermost diameter of the narrowest part of the pyramid-shaped cylinder is 20: 1 to 1: 1, preferably 10: 1.
When the ratio is set to 1 to 2: 1, a good introduction speed can be obtained.

The classification operation in the multi-division classification region configured as described above is performed, for example, as follows. Outlet 11
The pressure in the classifying chamber is reduced through at least one of 1, 112, 113, and the material supply nozzle 1 having an opening in the classifying chamber.
The powder is blown into the classification chamber through the raw material supply nozzle 116 at a flow rate of preferably 50 to 300 m / sec by high-pressure air and an air flow flowing by the reduced pressure.

The magnetic toner particles in the powdery raw material introduced into the classifying chamber draw curved lines 130a, 130b, 130c, etc. due to the action of the Coanda effect of the Coanda block 126 and the action of gas such as air flowing in at that time. Move according to the size of each particle and the magnitude of the inertial force,
Large particles (coarse particles) are outside the airflow (i.e., the first fraction outside the classification edge 118), middle particles are the second fraction between the classification edges 118 and 117, and small particles are inside the classification edge 117. The G powder composed of the large particles classified and classified into the third fraction is discharged from the outlet 111, and the M powder composed of the classified intermediate particles is discharged from the outlet 112, and the classified small particles are discharged. Are discharged from the discharge ports 113, respectively.

In the classification of the magnetic toner particles, the classification point is mainly determined by the edge tip positions of the classification edges 117 and 118 with respect to the lower end of the Coanda block 126 where the magnetic toner particles jump into the classification chamber 132. Further, the classification point is affected by the flow rate of the classification airflow, the ejection speed of the magnetic toner particles from the material supply nozzle 16, and the like.

In the airflow classifier, the raw material supply port 14
The powder raw material is supplied from the beginning, and the supplied powder raw material is radiated from the lower part of the powder raw material introduction port 142 from the outer periphery of the high pressure air introduction pipe 141 and rides on the high pressure air ejected from the high pressure air introduction pipe 141. It is accelerated and dispersed well, and is instantaneously introduced into the classifying chamber from the raw material supply nozzle 116, classified and discharged out of the classifier system. Therefore, the powder raw material introduced into the classifier is classified through the raw material supply nozzle 116. It is important that the agglomerated powder flies with propulsion in a state where the agglomerated powder is dispersed to the primary particles without disturbing the trajectories of the individual particles depending on the inlet portion in the room. When the powder material is introduced from above, the particle flow flowing from the inside of the raw material supply nozzle 116 moves the Coanda block 12 to the side of the opening of the raw material supply nozzle 116.
When the toner particle flow is introduced into the classifying chamber 132 having the particles 6, the particle trajectory is dispersed according to the size of the particles without being disturbed, and the particle flow is formed. Then, the classification edge is moved, and then the edge tip position of the classification edge is fixed, and can be set to a predetermined classification point. When the classification edges 117 and 118 move, the edges move in the flow direction of the particle flow flying along the Coanda block 126 by the simultaneous movement with the classification edge blocks 124 and 125.

More specifically, referring to FIG. 12, for example, centering on a position O in the Coanda block 126 corresponding to the side surface of the tip opening 116a of the raw material supply nozzle 116, for example.
Classification distance L ₁ between the side surfaces and the Coanda block 126 of distances L ₄ and classifying edges 117 of the side surface of the tip and the Coanda block 126 of the edge 117, moves the classifying edge block 124 up and down along the locating member 133 As a result, the classification edge 1 along the positioning member 134
17 can be adjusted by moving the tip of the classification edge 117 about the shaft 117a.

At the same time, the distance L ₅ between the tip of the classification edge 118 and the side wall of the Coanda block 126 and the classification edge 1
Distance L ₃ between the distance L ₂ or classification side surfaces and the side wall 123 of the edge 118 of the 17 side surface of the side surface of the classifying edge 118, positions the classifying edge block 125 member 1
38 by moving the positioning member 1 up and down.
The classification edge 118 can be adjusted by moving the classification edge 118 up and down along 36 and further rotating the tip of the classification edge 118 about the shaft 118a.

[0100] Tip opening 116 of raw material supply nozzle 116
a, Coanda block 126, classification edge 11
7 and 118 are installed, and the classification edge block 12
With the change of the installation position of 4 or / and the classification edge block 125, the classification area of the classification room is expanded, and the classification point can be easily and largely changed.

Therefore, it is possible to prevent the turbulence of the flow due to the tip of the classification edge, and the discharge conduits 111a, 112a and 11
By adjusting the flow rate of the suction flow due to the reduced pressure through 3a, the flying speed of the particles is increased to improve the dispersion of the toner particles in the classification area, and better classification accuracy is obtained even at a higher dust concentration. In addition, it is possible not only to prevent a decrease in product yield, but also to achieve better classification accuracy and an improved product yield at the same dust concentration.

The distance L ₆ between the tip of the inlet edge 119 and the wall surface of the Coanda block 126 can be adjusted by rotating the tip of the inlet edge 119 about the shaft 119a. By adjusting the inflow amount and the inflow speed of the gas from 115, the classification point can be further adjusted.

The above set distance is appropriately determined according to the characteristics of the powder raw material and the like, but the true density of the magnetic toner particles is 1.4.
In the case of non-magnetic toner particles exceeding g / cm ³ , the installation positions of the classifying edge blocks each having the classification edge and capable of changing the installation position are determined by the following conditions: L ₀ > 0, L ₁ > 0, L ₂ > 0, L ₃ > 0 L ₀ <L ₃
<L ₁ + L ₂ [where L ₀ is the height diameter (m
m) indicates, L ₁ denotes a distance between the first classifying edge sides for demarcating medium powder group and the fine powder group and the binary, with the side surface of the Coanda block that faces to (mm), L ₂ Is the first
The distance (mm) between the side surface of the classification edge and the side surface of the second classification edge for fractionation into the coarse powder group and the medium powder group,
L ₃ is preferably set to satisfy the side surface of the second classifying edge, the distance between the side surface of the side wall which faces to the (mm) indicates a].

If this condition is satisfied, magnetic toner particles having a sharp particle size distribution can be obtained efficiently.

[0105] The airflow classifier is used by connecting the mutual devices by means of communicating means such as pipes, and is incorporated into the device system. A preferred example of such a device system is shown in FIG.
It is shown in FIG. The integrated device system shown in FIG. 12 includes a three-divider classifier 1 (the classifier shown in FIGS. 7 and 8), a quantitative feeder 202, a vibration feeder 203, and a collecting cyclone 20.
4, 205 and 206 are connected by communication means.

In this apparatus system, the powder is fed into the quantitative feeder 202 by appropriate means, and then introduced into the three-division classifier 201 through the vibrating feeder 203 by the raw material supply nozzle 116. At the time of introduction, the powder is introduced into the three-way classifier 201 at a flow rate of 50 to 300 m / sec. The size of the classifying chamber of the classifier 201 is usually [10 to 50 cm] × [10 to 50 c].
m].
The particles can be classified into groups of more than one kind of particles. And 3 division classifier 2
The particles are classified into large particles (coarse particles), intermediate particles, and small particles. Thereafter, the large particles are discharged from the discharge conduit 11a.
Through the collection cyclone 206 to be collected.
The intermediate particles are discharged out of the system via the discharge conduit 112a and collected by the collection cyclone 205. Capture cyclone 2
04, 205, and 206 can also function as suction pressure reducing means for sucking and introducing the powder into the classification chamber via the raw material supply nozzle 116.

An example of an image forming method using the magnetic toner of the present invention will be described with reference to FIG.

The contact charging means 2 is applied with a voltage by the bias applying means E, and the electrostatic charge image carrier (photosensitive drum) 1
The surface of is charged negatively, and a digital latent image is formed by image scanning by exposure 3 with laser light,
The magnetic toner 1 of the developing device 4 including an elastic blade 6 and a toner carrier (developing sleeve) 5 containing a magnet.
At 3, the latent image is reverse developed. In the developing section, the conductive base of the photosensitive drum 1 is grounded, and an alternating bias, a pulse bias and / or a DC bias are applied to the developing sleeve 5 by a bias applying means 8.

When the transfer paper P is conveyed and arrives at the transfer portion, the transfer paper P is charged by the voltage application means 10 from the rear surface (the surface opposite to the photosensitive drum side) of the transfer paper P, whereby the transfer paper P is charged.
The developed image (toner image) on the surface of the photosensitive drum 1 is transferred onto the transfer paper P by the roller transfer unit 9. The transfer paper P separated from the photosensitive drum 1 is subjected to a fixing process by a heating / pressing roller fixing device 12 in order to fix a toner image on the transfer paper P.

When the amount of magnetic toner remaining on the photosensitive drum 1 after the transfer step is small, the cleaning step can be omitted. After the cleaning by the cleaning unit 11, the photosensitive drum 1 repeats the process starting from the charging process by the contact charging unit 2 again.

The photosensitive drum has a photosensitive layer and a conductive substrate, and moves in the direction of the arrow. A non-magnetic cylindrical developing sleeve 5 serving as a toner carrier rotates so as to move in the same direction as the surface of the photosensitive drum 1 in the developing section. Inside the developing sleeve 5, a multi-pole permanent magnet (magnet roll) as a magnetic field generating means is arranged so as not to rotate. The magnetic toner 13 in the developing device 4 is applied on a non-magnetic cylindrical surface, and the magnetic toner is given, for example, a negative triboelectric charge by friction between the surface of the developing sleeve 5 and the magnetic toner.
Further, the elastic blade 6 is moved closer to the cylindrical surface (at an interval of 50 mm).
μm to 500 μm), and placed on one of the multi-pole permanent magnets so as to oppose the magnet position, thereby controlling the thickness of the magnetic toner layer to be thin (30 μm to 300 μm) and evenly, so that the photosensitive drum 1 A magnetic toner layer thinner than the gap between the magnetic toner layer and the developing sleeve 5 is formed. By adjusting the rotation speed of the developing sleeve 5, the surface speed of the sleeve is substantially equal to or close to the speed of the photosensitive drum surface. An iron blade may be used as the elastic blade 6.

In the developing section, an AC bias or a pulse bias may be applied to the developing sleeve 5 by the bias means 8. This AC bias is f 200 to 4,000.
It suffices if 0 Hz and Vpp are 500 to 3,000 V.

When transferring the magnetic toner in the developing section,
The magnetic toner is transferred to the electrostatic image side by the action of electrostatic and AC bias or pulse bias on the photosensitive drum surface.

The elastic blade 6 is formed of an elastic material such as silicone rubber. The thickness of the magnetic toner layer is regulated by pressing using the elastic blade 6, and the magnetic toner 13 is coated on the developing sleeve 5. I have.

FIG. 5 is a structural view of a charging roller which is one form of the contact charging means suitably used in the present invention.

Reference numeral 42 denotes a charging roller, and a central metal core 42 is provided.
a and the conductive elastic layer 42b forming the outer periphery thereof and the surface layer 4
2c as a basic configuration. Charging roller 42
Is pressed against the surface of the photosensitive drum 1 with a pressing force, and is driven to rotate as the photosensitive drum 1 rotates. The photosensitive drum 1 includes a conductive base layer 1a formed of a conductive metal such as aluminum and a photoconductive layer 1b formed on an outer surface thereof as basic constituent layers. (Process speed). Charging roller 42
When a voltage is applied by the bias applying means E and a bias is applied to the charging roller 42, the surface of the photosensitive drum is charged to a predetermined polarity and potential. Next, an electrostatic image is formed by image exposure, and the electrostatic image is sequentially visualized as a toner image by a developing unit.

As a preferable process condition when the charging roller is used, when a contact pressure of the roller is 5 to 500 g / cm and a DC voltage is superimposed on an AC voltage, the AC voltage is 0.5 to 5 kVpp. , AC frequency = 50Hz ~
5 kHz, DC voltage = ± 0.2 to ± 5 kV, and when only DC voltage is used, DC voltage = ± 0.2 to ± 5 kV
V.

The charging roller may be made of conductive rubber,
For example, an ethylene-propylene-diene terpolymer (EPDM) is preferable, and a release coating may be provided on the surface. Nylon resin, polyvinylidene fluoride (PVDF), polyvinylidene chloride (P
VDC) is preferably used.

Next, the process cartridge of the present invention will be described with reference to FIG.

In the process cartridge of the present invention, at least the developing means and the latent image holding member are generally formed into a cartridge, and are attached to and detached from the image forming apparatus main body (for example, a copying machine, a laser beam printer, a facsimile machine). It is configured to be possible.

In the embodiment shown in FIG.
9, drum-shaped electrostatic image carrier (photosensitive drum) 1, cleaning means 7 having cleaning blade 708a
08, a process cartridge 750 in which a contact charging means 742 as a primary charging means is integrated.

In the present embodiment, the developing means 709 has an elasticity regulating blade 711 as a toner layer thickness regulating means and a magnetic toner 710 in a toner container 760, and uses the magnetic toner 710. A predetermined electric field is formed between the photosensitive drum 1 and the developing sleeve 704 as a toner carrier by the developing bias voltage, and the developing process is performed. To carry out this developing step suitably, the distance between the photosensitive drum 1 and the developing sleeve 704 is adjusted.

In the above description, the embodiment in which the four components of the developing means 709, the latent image holding member 1, the cleaning means 708 and the primary charging means 742 are integrally formed as a cartridge has been described. It is sufficient that at least two components of the toner and the electrostatic image holder are integrally formed into a cartridge, and three components of a developing unit, an electrostatic image holder and a cleaning unit,
It is also possible to integrally form a cartridge by adding three components of the developing unit, the electrostatic image holder and the primary charging unit, or other components.

[0124]

EXAMPLES The present invention will be described more specifically based on the following examples.

Example 1 (i) 100 parts by weight of binder resin (a) Styrene-n-butyl acrylate copolymer (copolymer weight ratio = 80: 20) (b) In GPC, the molecular weight was reduced to 15,000. It has a main peak and a subpeak at a molecular weight of 650,000. (C) Weight average molecular weight (Mw) 250,000

(Ii) 100 parts by weight of magnetic fine powder (a) Number average particle diameter R: 0.18 μm (b) Shape of magnetic fine particles: spherical (c) σ _r : 5.9 [Am ² / kg] (d) ) H _C : 6.4 [kA / m] (e) σ _r × H _C : 38 [kA ² m / kg] (f) W of silicon dioxide present on the back surface of the magnetic fine particles:
0.13% by weight (g) W × R: 0.024

(Iii) 2 parts by weight of a negative charge control agent (a) a monoazo complex represented by the above formula (a)

[0128]

[Outside 7]

(Iv) 5 parts by weight of wax (a) long-chain alkyl alcohol (b) average number of carbon atoms: 50 (c) softening point: 98 ° C. (e) measuring method of softening point: DSC endothermic peak temperature

The above materials were mixed with a Henschel mixer to obtain a mixture, and the obtained mixture was introduced into a twin-screw extruder (model name "TEM-100B" manufactured by Toshiba Machine Co., Ltd.). Was used to melt and knead the mixture. The temperature of the kneaded material immediately after kneading was 159 ° C. The kneaded product was coarsely pulverized to 1 mm or less by a hammer mill, and the obtained coarsely pulverized product was finely pulverized by a collision type air flow pulverizer using a jet stream to obtain a finely pulverized product.

[0131] In the classification system shown in FIG.
In order to classify into the coarse powder group G, the medium powder group M and the fine powder group F using the Coanda effect at a rate of 360 kg / h via the raw material supply pipe 116 and the raw material supply pipe 116, the multi-particles shown in FIG. It was introduced into a split classifier 201.

At the time of introduction, the outlets 111, 112, 1
13, collection cyclones 204, 205, 2
A suction force derived from the pressure reduction in the system by the suction pressure reduction of 06 and air compression (pressure 1.5 kg / cm ² ) from the injection nozzle 131 attached to the raw material supply pipe 116 were used.

In order to change the shape of the classification area, classification was performed by setting each set distance shown in FIG. 11 as follows. L ₀ = 6 mm (height diameter of raw material supply nozzle outlet 116 a) L ₁ = 32 mm (distance between the side surface of classification edge 117 and the side surface of Coanda block 126) L ₂ = 33 mm (side surface of classification edge 117 and classification edge 118) L ₃ = 39 mm (side surface of classification edge 118 and side wall 123)
L ₄ = 18 mm (distance between the tip of the classification edge 117 and the side of the Coanda block 126) L ₅ = 33 mm (distance between the tip of the classification edge 118 and the side of the Coanda block 126) L ₆ = 25 mm (Distance between the tip of the inlet edge 119 and the side surface of the Coanda block 126) R = 14 mm (the radius of the fox of the Coanda block 126)

The introduced finely pulverized product was classified instantaneously in 0.1 seconds or less.

Medium powder group M used as magnetic toner particles
Has a weight average particle diameter (D ₄ ) of 5.7 μm, an absorbance of 0.55, a shape factor SF-1 of 154, a shape factor SF-2 of 143, and SF-1 / SF- The value of 2 was 1.08. Table 2 shows the physical properties of the obtained magnetic toner particles. Table 3 shows the dispersion state of the magnetic fine powder and the dispersion state of the wax.

100 parts by weight of the obtained magnetic toner particles,
1.5 parts by weight of a hydrophobic silica fine powder (BET specific surface area: 110 m ² / g) surface-treated with a silane coupling agent and dimethyl silicone oil were mixed to prepare a magnetic toner having a negative frictional charge. .

In order to evaluate the magnetic toner by the image forming method shown in FIG. 4, a laser beam printer (trade name: LBP-450, manufactured by Canon Inc.) which develops an electrostatic charge image by a reversal developing method having a resolution of 600 dpi. Magnetic toner into the developing unit of the process cartridge for
An image-drawing test was performed under each environment.

Further, the image quality of the dot latent image was evaluated using a laser beam printer modified so as to have a resolution of 1200 dpi.

The evaluation results are shown in Tables 4, 5, and 6.

Evaluation method (a) Initial image density (second image) The image densities of the 3000th and 6000th solid black images were measured using a Macbeth densitometer.

(B) Using a fogging “reflectometer” (Tokyo Denshoku Co., Ltd.), the whiteness of the transfer paper before printing was measured in advance, and the difference from the whiteness of the printed white image portion was determined. The value showing the maximum difference was shown.

(C) The evaluation was performed using a halftone image in which a poorly charged image is likely to occur after 6,000 sheets of the charging roller have been stained . Rank 5: No defective image caused by contamination of the contact charging roller. Rank 3: A defective image is generated due to contamination of the contact charging roller, but is at a level that does not cause a problem in practical use. Rank 1: A level at which occurrence of a defective image due to contamination of the contact charging roller was confirmed, and the defective image became a practical problem. Rank 4 is an intermediate level between ranks 5 and 3, and rank 2
Is an intermediate level between ranks 3 and 1.

(D) A one-dot toner image is formed under an image forming condition capable of forming 600 dot latent images per inch of a 600 dpi dot image , and the toner image is enlarged and visually evaluated in four steps. did. A: Excellent B: Good C: Normal D: Bad (Spattering of toner is observed and the shape of the dot image is irregular)

(E) A one-dot toner image is formed under image forming conditions capable of forming 1200 dot latent images per inch at a 1200 dpi dot image , and the toner image is enlarged and visually evaluated in four steps. did. A: Excellent B: Good C: Normal D: Bad (Spattering of toner is observed and the shape of the dot image is irregular)

(F) O generated on a solid black image after performing 6,000 drums of fusing
The evaluation was made based on the degree of generation of white spots caused by the deposits on the PC photosensitive drum. Rank 5: No occurrence at all. Rank 3: Several points are observed, but there is no practical problem. Rank 1: Many occurrences (several tens), causing practical problems. Rank 4 is an intermediate level between ranks 5 and 3, and rank 2
Is an intermediate level between ranks 3 and 1.

(G) Image density of the first sheet in the morning In a high-temperature and high-humidity environment, the density of the first sheet (corresponding to 3001 sheets) of the first sheet in the morning on the third day was measured with a durability of 1500 sheets / day. .

Example 2 The magnetic particles were formed of spherical magnetic fine particles having a number average particle diameter of 0.20 μm, σ _r × H _C was 22 (kA ² m / kg), and W
Magnetic toner particles were obtained in the same manner as in Example 1, except that a magnetic fine powder having an XR of 0.044 was used. The obtained magnetic toner particles and hydrophobic silica fine powder were mixed to prepare a magnetic toner, and the image formation was evaluated in the same manner as in Example 1.

The physical properties of the magnetic toner particles are shown in Table 2, and the evaluation results are shown in Tables 4, 5, and 6.

Example 3 The number average particle size was 0.18 μm, the shape was spherical, σ _r × H _C
= 38 (kA ² m / kg), and a magnetic toner was prepared and evaluated in the same manner as in Example 1 except that a magnetic fine powder having W × R = 0.044 was used. The absorbance of the magnetic toner particles was 0.64, and SF-1 = 155, SF-
2 = 144, and the temperature of the kneaded material was 156 ° C. The physical properties of the magnetic toner particles are shown in Table 2, and the evaluation results are shown in Tables 4, 5, and 6.

Example 4 The number average particle size was 0.18 μm, the shape was spherical, σ _r × H _C
= 38 (kA ² m / kg), and a magnetic toner was prepared and evaluated in the same manner as in Example 1 except that a magnetic fine powder having W × R = 0.024 was used. The absorbance of the magnetic toner particles was 0.60, SF-1 = 154, SF-
2 = 143, and the temperature of the kneaded material was 156 ° C. The physical properties of the magnetic toner particles are shown in Table 2, and the evaluation results are shown in Tables 4, 5, and 6.

Example 5 A polyethylene wax (softening point 130
° C), and a magnetic toner was prepared and evaluated in the same manner as in Example 4. The absorbance of the magnetic toner particles was 0.57, SF-1 = 154, SF-2 = 143.
And the temperature of the kneaded material was 154 ° C. The physical properties of the magnetic toner particles are shown in Table 2, and the evaluation results are shown in Tables 4, 5, and 6.
Shown in

Example 6 A magnetic toner was prepared and evaluated in the same manner as in Example 4, except that the kneading conditions were changed to B shown in Table 1. The absorbance of the magnetic toner particles was 0.55, SF-1 = 154,
SF-2 = 143, and the temperature of the kneaded material was 159 ° C. The physical properties of the magnetic toner particles are shown in Table 2, and the evaluation results are shown in Tables 4, 5, and 6.

Example 7 A magnetic toner was prepared and evaluated in the same manner as in Example 4 except that the kneading conditions were changed to C shown in Table 1. The absorbance of the magnetic toner particles was 0.50, and SF-1 = 155.
SF-2 = 143, and the temperature of the kneaded material was 161 ° C. The physical properties of the magnetic toner particles are shown in Table 2, and the evaluation results are shown in Tables 4, 5, and 6.

Example 8 A magnetic toner was prepared and evaluated in the same manner as in Example 4, except that the kneading conditions were changed to D shown in Table 1. The absorbance of the magnetic toner particles was 0.50, and SF-1 = 155.
SF-2 = 144, and the temperature of the kneaded material was 161 ° C. The physical properties of the magnetic toner particles are shown in Table 2, and the evaluation results are shown in Tables 4, 5, and 6.

Example 9 A magnetic toner was prepared and evaluated in the same manner as in Example 4, except that the kneading conditions were changed to E shown in Table 1. The absorbance of the magnetic toner particles was 0.58, and SF-1 = 155.
SF-2 was 143, and the temperature of the kneaded material was 155 ° C. The physical properties of the magnetic toner particles are shown in Table 2, and the evaluation results are shown in Tables 4, 5, and 6.

Example 10 A magnetic toner was prepared and evaluated in the same manner as in Example 4 except that the kneading conditions were changed to F shown in Table 1. The absorbance of the magnetic toner particles is 0.52, SF-1 = 154, S
F-2 = 143, and the temperature of the kneaded material was 153 ° C. The physical properties of the magnetic toner particles are shown in Table 2, and the evaluation results are shown in Tables 4, 5, and 6.

Examples 11 to 15 Magnetic toner particles shown in Table 2 were obtained by changing the magnetic fine powder used, kneading conditions, classification conditions, and the like. The obtained magnetic toner particles and hydrophobic silica fine powder were mixed to prepare a magnetic toner, and the image formation was evaluated in the same manner as in Example 1. The evaluation results are shown in Tables 4, 5, and 6.

Comparative Example 1 A magnetic toner was prepared and evaluated in the same manner as in Example 2 except that the kneading conditions were changed to G shown in Table 1. The absorbance in the wetting test of the magnetic toner particles was 0.72,
F-1 = 155, SF-2 = 144, and the temperature of the kneaded material was 152 ° C. Table 2 shows the results.

Comparative Example 2 A magnetic toner was prepared and evaluated in the same manner as in Example 2 except that the kneading conditions were changed to H shown in Table 1. The absorbance of the magnetic toner particles is 0.77, and SF-1 = 155, S
F-2 = 143, and the temperature of the kneaded material was 153 ° C. The physical properties of the magnetic toner particles are shown in Table 2, and the evaluation results are shown in Tables 4, 5, and 6.

Comparative Example 3 A magnetic toner was prepared and evaluated in the same manner as in Example 2 except that the kneading conditions were changed to I shown in Table 1. The absorbance of the magnetic toner particles is 0.18, and SF-1 = 155, S
F-2 = 143, and the temperature of the kneaded material was 160 ° C. The physical properties of the magnetic toner particles are shown in Table 2, and the evaluation results are shown in Tables 4, 5, and 6.

Comparative Examples 4 to 6 Magnetic toner particles shown in Table 2 were obtained by changing the magnetic fine powder used, kneading conditions, classification conditions, and the like. The obtained magnetic toner particles and hydrophobic silica fine powder were mixed to prepare a magnetic toner, and the image formation was evaluated in the same manner as in Example 1. The evaluation results are shown in Tables 4, 5, and 6.

[0162]

[Table 1]

[0163]

[Table 2]

[0164]

[Table 3]

[0165]

[Table 4]

[0166]

[Table 5]

[0167]

[Table 6]

Example 16 Binder resin (styrene resin) 100 parts by weight Magnetic fine powder (number average particle diameter = 0.20 μm 100 parts by weight) Shape: spherical σ _r × H _c = 22 (kA ² m / kg) W × R = 0.044) Charge control agent (monoazo Fe complex) 2 parts by weight Wax (high molecular alcohol wax, softening point 98 ° C.) 5 parts by weight

The above constituent materials were mixed and dispersed by a Henschel mixer, and were melt-kneaded under the conditions A shown in Table 3. The temperature of the kneaded material immediately after kneading was 156 ° C. After cooling, the kneaded material is coarsely pulverized, finely pulverized by a pulverizer using a jet stream, and further, an elbow jet classifier (manufactured by Nippon Steel Mining Co., Ltd.)
Was used to obtain magnetic toner particles having a weight average diameter (D ₄ ) of 5.7 μm. The absorbance according to the wettability test was 0.65. 1.5 parts by weight of hydrophobized silica fine powder was added to 100 parts by weight of the toner particles to obtain a magnetic toner.

A laser beam printer (trade name “LBP-
450 "(manufactured by Canon Inc.) was modified into an image-evaluation apparatus, and the above-described magnetic toner was charged into a cartridge shown in FIG.

In this embodiment, primary charging was performed by the charging roller shown in FIG. 12 m outer diameter of charging roller 42
m, and the conductive rubber layer 42b has EPDM and the surface layer 4
For 2c, a 10 μm thick nylon resin was used. E denotes a power supply for applying a voltage to the charging roller 42, and supplies a predetermined voltage to the metal core 42a of the charging roller 42. In FIG. 5, E is obtained by superimposing an AC voltage on a DC voltage.

The photosensitive drum is charged by the charging roller 42 so that the primary charge becomes -650 V, a gap is set in a non-contact manner between the photosensitive drum and the developer layer on the developing sleeve (including magnets), and an AC bias (f = 2,200 Hz, Vpp =
1,600V) and DC bias (V _DC = -500V)
While applying に to the developing sleeve, _VL was set to −170 V, the electrostatic charge image was developed by reversal development to form a magnetic toner image on the OPC photoconductor.

The formed magnetic toner image was transferred to plain paper at the above-mentioned positive transfer potential, and the plain paper having the magnetic toner image was fixed through a heating / pressing roller fixing device. Table 8 shows the results.

Example 17 A magnetic material having a number average diameter of 0.18 μm, a spherical shape, and a
_r × H _C = 38 (kA ² m / kg), W × R = 0.04
Except for D4, D ₄ = 5.7 in the same manner as in Example 16.
A μm magnetic toner was prepared and evaluated. The absorbance of the magnetic toner particles in the wetting test was 0.64.
Met. Table 8 shows the results.

Example 18 An evaluation was performed using the magnetic toner used in Example 17 in the same manner as in Example 17 except that an EPDM foam was used as the conductive rubber layer of the charging roller. Done. Table 8 shows the results.

Example 19 An image was formed in the same manner as in Example 17 except that an acrylic resin in which a fluororesin was dispersed was used as the surface layer of the charging roller, and the magnetic toner used in Example 17 was used. An evaluation was performed. Table 8 shows the results.

Example 20 A magnetic toner was prepared in the same manner as in Example 2 except that the kneading conditions were changed to B shown in Table 7, and evaluation was performed by the same image forming method as in Example 19. Table 8 shows the results.

Comparative Example 7 A magnetic toner was prepared in the same manner as in Example 16 except that the kneading conditions were changed to C shown in Table 7, and evaluation was performed in the same manner as in Example 16. The absorbance in the wettability test of the magnetic toner particles was 0.72. Table 8 shows the evaluation results.

Comparative Example 8 A magnetic toner was prepared in the same manner as in Example 16 except that the kneading conditions were changed to D shown in Table 7, and evaluation was performed in the same manner as in Example 16. The absorbance of the magnetic toner particles in the wetting test was 0.18. Table 8 shows the evaluation results.

[0180]

[Table 7]

[0181]

[Table 8]

[0182]

The magnetic toner of the present invention can be used at low temperatures and low temperatures by using magnetic toner particles having a specific wettability.
It is possible to provide an image having a high density even in a low-humidity environment, less fogging, no occurrence of contamination of the charging roller, and a high density even in a high-temperature, high-humidity environment, without causing drum fusion.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory diagram of a temperature control unit configuration and a shaft configuration of a kneader.

FIG. 2 is a schematic explanatory view of a cross-sectional configuration of a cylinder.

FIG. 3 is a correlation diagram between resin temperature, the amount of free magnetic fine particles, and the dispersibility of wax.

FIG. 4 is a schematic explanatory view of an example of an electrophotographic apparatus using the magnetic toner of the present invention.

FIG. 5 is a schematic explanatory view of a contact charging means suitably used in the present invention.

FIG. 6 is a schematic explanatory view showing an example of the process cartridge of the present invention.

FIG. 7 is a schematic cross-sectional view of an airflow classifier that uses the Coanda effect for multi-divided classification of magnetic toner particles.

8 is a perspective view of the airflow classifier shown in FIG.

FIG. 9 is a perspective view of the airflow classifier shown in FIG.

FIG. 10 is a sectional view taken along the line AA ′ in FIG. 7;

11 is a diagram showing a main part of FIG. 7;

FIG. 12 is an explanatory diagram showing an example of a classification process used for classifying magnetic toner particles.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 electrostatic image carrier 2 primary charging device 3 exposure optical system 4 developing device 5 toner carrier 6 toner layer thickness regulating member 7 toner stirring means 8 developing bias power supply 9 transfer device 10 transfer current generator 11 cleaning means 12 fixing device 13 Magnetic toner 704 Developing sleeve 709 Developing device 710 Developer (magnetic toner) 742 Contact charging means 743 Bias applying means

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Yoshihiro Ogawa 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc.

Claims (59)

[Claims] 1. A magnetic toner for developing an electrostatic image, comprising magnetic toner particles containing at least a binder resin, a magnetic fine powder and a wax, wherein the magnetic toner particles have a weight average particle diameter of from 3.5 to 3.5. 6.5
μm; the absorbance at a wavelength of 600 nm of a dispersion obtained by dispersing 15 mg of the magnetic toner particles in 19 ml of a mixture of ethyl alcohol and water (volume ratio 27:73) is 0.2 μm.
From 0.7 to 0.7. 2. The magnetic fine powder has a 795.8 kA / m (1
0K Oersted) magnetic field (σ _r)
(Am ² / kg)) and magnetic toner according to claim 1 the product of coercive force _{(H C (kA / m)} ) (σ r × H C) is ^{24~56 (kA 2 m / kg)} . 3. The magnetic fine powder is composed of magnetic fine particles, has spherical magnetic fine particles, has at least silicon dioxide on the surface of the magnetic fine particles, and has the following conditions. ≦ W × R ≦ 0.042 [where W represents the weight percentage of silicon dioxide present on the surface of the magnetic fine particles, and R represents the number average particle diameter of the magnetic fine particles (μ
m) is satisfied. 4. The magnetic toner according to claim 1, wherein the wax contains a long-chain alkyl alcohol. 5. The long-chain alkyl alcohol has the structural formula CH ₃
(CH ₂₎ nOH wherein, n represents an integer of 20 to 300] magnetic toner according to claim 4 having a. 6. The magnetic toner particles have a shape factor SF-1 value of 140 <SF-1 ≦ 180, and a shape factor SF-
6. The magnetic toner according to claim 1, wherein the value of 2 satisfies 130 <SF-2 ≦ 170. 7. The binder resin has a molecular weight distribution measured by gel permeation chromatography of at least 0.5 × 10 ^{4 to} 5 × 10 ⁴ and 1.
0 × 10 ⁵ to 5.0 or of the magnetic toner of claims 1 to 6, which is a styrene resin having a peak in the region of the × 10 ^6. 8. The styrene-based resin is a resin selected from the group consisting of a styrene polymer, a styrene copolymer, a styrene-acrylate copolymer, a styrene-methacrylate copolymer, and a mixture thereof. The magnetic toner according to claim 7. 9. The magnetic toner according to claim 1, wherein the magnetic fine powder is contained in the magnetic toner particles at 40 to 60% by weight based on the weight of the magnetic toner particles. 10. The magnetic toner particles have an absorbance of 0.30 to 0.30.
10. The magnetic toner according to claim 1, having a ratio of 0.69. 11. The magnetic toner particles have an absorbance of 0.35 to 0.35.
10. The magnetic toner according to claim 1, having a ratio of 0.65. 12. The magnetic fine powder, the residual magnetization (sigma _r) and coercivity (H _C) and the product (σ _r × H _C) is thirty to fifty-two (kA
² m / kg). 13. The magnetic fine powder has a number average particle size of 0.0
13. The magnetic toner according to claim 1, which has a thickness of 5 to 0.30 [mu] m. 14. The magnetic fine powder has a number average particle size of 0.1.
13. The magnetic toner according to claim 1, which has a thickness of 0 to 0.25 [mu] m. 15. The magnetic fine powder according to claim 8, wherein 0.008 ≦ W × R ≦
15. The magnetic toner according to claim 1, which satisfies a condition of 0.035. 16. The magnetic toner according to claim 1, wherein the magnetic fine powder is contained in the magnetic toner particles in an amount of 45 to 55% by weight based on the weight of the magnetic toner particles. 17. The magnetic toner according to claim 7, wherein the styrene resin has a weight average molecular weight of 150,000 to 350,000. 18. The magnetic toner particles have a BET specific surface area of 3
The magnetic toner according to any one of claims 1 to 17, wherein the magnetic toner is mixed with an inorganic fine powder of 0 ² / g or more. 19. The inorganic fine powder has a BET specific surface area of 50.
19. The magnetic toner according to claim 18, wherein the amount is from about 400 m < ² > / g. 20. The magnetic toner according to claim 18, wherein the magnetic toner particles are mixed with 0.01 to 8 parts by weight of inorganic fine powder per 100 parts by weight. 21. The magnetic toner according to claim 18, wherein the magnetic toner particles are mixed with 0.1 to 5 parts by weight of inorganic fine powder per 100 parts by weight. 22. The magnetic toner according to claim 18, wherein the inorganic fine powder is a silica fine powder treated with silicone oil. 23. A method for producing a magnetic toner having magnetic toner particles containing at least a binder resin, a magnetic fine powder, and a wax, wherein a mixture containing at least the binder resin, the magnetic fine powder, and the wax is kneaded with a kneading machine. The following condition: 2.2 × 10 ³ ≦ E / ε ≦ 2.0 × 10 ⁴ E = kω ² T, ε = F / (πD ² L) [where ω is the screw rotation speed (m / min) , T indicates a set temperature (K), F indicates a supply amount of a mixture (kg / min), D indicates a cylinder inner diameter (m), L indicates an effective screw length (m), and π indicates a circle. The circumstantial ratio is indicated, k indicates (D ₀ / D) ² , and D ₀ is 0.1 m. ), The kneaded product is cooled, the cooled product is pulverized, and the pulverized product is classified to obtain magnetic toner particles. The magnetic toner particles have a weight average particle size of 3.5 to 6 .5
μm; the absorbance at a wavelength of 600 nm of a dispersion obtained by dispersing 15 mg of the magnetic toner particles in 19 ml of a mixture of ethyl alcohol and water (volume ratio 27:73) is 0.2 μm.
From 0.7 to 0.7. 24. The method for producing a magnetic toner according to claim 23, wherein the temperature of the kneaded material immediately after kneading is 30 to 70 ° C. higher than the softening point of the wax. 25. The magnetic fine powder is 795.8 kA / m.
(10K Oersted) magnetic field (σ)
_r (Am ² / kg)) and a coercive force _{(H C (kA / m)} ) magnetic or 24 according to claim 23 which is a product (σ _r × H _C) is 24~56 (kA ² m / kg) of Manufacturing method of toner. 26. The magnetic fine powder is composed of magnetic fine particles, has magnetic fine particles having a spherical shape, and has at least silicon dioxide on the surface of the magnetic fine particles. 0.003 ≦ W × R ≦ 0.042 [wherein W represents the weight percentage of silicon dioxide present on the surface of the magnetic fine particles, and R represents the number average particle size (μ) of the magnetic fine powder.
m).], wherein the magnetic toner according to any one of claims 23 to 25 is satisfied. 27. The method according to claim 23, wherein the wax contains a long-chain alkyl alcohol. 28. The long chain alkyl alcohol has the structural formula CH
₃ (CH ₂₎ nOH wherein, n represents an integer of 20 to 300] method for producing a magnetic toner according to claim 27 having a. 29. The rotational speed ω (m / m) of the screw of the kneader.
min) is 5 to 50, and the set temperature T (K) is 333.
513, the feed rate F (kg / min) of the mixture is 0.15 to 25, the inner diameter D (m) of the cylinder is 0.03 to 0.2, and the effective length L (m) of the screw is Is 1.00 to 4.0
The method for producing a magnetic toner according to any one of claims 23 to 28, wherein the value is 0. 30. The value of E is from 3.0 × 10 ^{5 to} 16.0.
× 10 ⁵ , and the rotational speed ω (m / min) of the screw of the kneader is 5 to 5
0, the set temperature T (K) is 333 to 513, the supply amount F (kg / min) of the mixture is 0.15 to 25, and the inner diameter D (m) of the cylinder is 0.03 to 0. 2, and the effective length L (m) of the screw is 1.00 to 4.0.
30. The method for producing a magnetic toner according to claim 23, wherein the value is 0. 31. The supply amount F of the mixture is from 0.30 to 1
31. The method for producing a magnetic toner according to claim 29 or 30, wherein the concentration is 2.00 (kg / min). 32. The method for producing a magnetic toner according to claim 23, wherein the value of ε is 85 to 130. 33. The method according to claim 23, wherein the value of E / ε is 2.5 × 10 ^{3 to} 1.5 × 10 ⁴ . 34. The rotational speed ω (m / m) of the screw of the kneader.
min) is 5 to 50, and the set temperature T (K) is 333.
513, the feed rate F (kg / min) of the mixture is 0.15 to 25, the inner diameter D (m) of the cylinder is 0.03 to 0.2, and the effective length L (m) of the screw is Is 1.00 to 4.0
0, the value of E is from 3.0 × 10 ^{5 to} 16.0 × 10 ⁵ ,
When the supply amount F of the mixture is 0.30 to 12.0 (kg / mi)
The magnetic toner according to any one of claims 23 to 33, wherein n), the value of ε is 85 to 130, and the value of E / ε is 2.5 × 10 ^{3 to} 1.5 × 10 ^4. Method. 35. The magnetic toner particles have a shape factor of SF-1.
Is 140 <SF-1 ≦ 180, and the shape factor SF
24. The value of -2 is 130 <SF-2 ≦ 170.
35. The method for producing magnetic toner particles according to any one of items 34 to 34. 36. The binder resin has a molecular weight distribution measured by gel permeation chromatography of at least 0.5 × 10 ^{4 to} 5 × 10 ⁴ and 1.0 × 10 ^{5 to} 5.0 × 10 ^6. The method for producing a magnetic toner according to any one of claims 23 to 35, wherein the method is a styrene resin having a peak in the region of 37. The styrenic resin is a styrene polymer,
37. The method for producing a magnetic toner according to claim 36, wherein the resin is a resin selected from the group consisting of a styrene copolymer, a styrene-acrylate copolymer, a styrene-methacrylate copolymer, and a mixture thereof. 38. The method according to claim 23, wherein the magnetic fine powder is contained in the magnetic toner particles in an amount of 40 to 60% by weight based on the weight of the magnetic toner particles. 39. The magnetic toner particles having an absorbance of 0.30 to 0.30.
39. The method for producing a magnetic toner according to claim 23, wherein the magnetic toner has a ratio of 0.69. 40. The magnetic toner particles having an absorbance of 0.35 to 0.35.
The method for producing a magnetic toner according to any one of claims 23 to 38, wherein the magnetic toner has a ratio of 0.65. 41. A magnetic fine powder, the residual magnetization (sigma _r) and coercivity (H _C) and the product (σ _r × H _C) is thirty to fifty-two (kA
^The method for producing a magnetic toner according to any one of claims 23 to 40, wherein the amount is ² m / kg). 42. The magnetic fine powder has a number average particle size of 0.0
The method for producing a magnetic toner according to any one of claims 23 to 41, wherein the thickness is 5 to 0.30 µm. 43. The magnetic fine powder has a number average particle diameter of 0.1.
The method for producing a magnetic toner according to any one of claims 23 to 41, wherein the thickness is 0 to 0.25 µm. 44. The magnetic fine powder is 0.008 ≦ W × R ≦
The method for producing a magnetic toner according to any one of claims 23 to 43, wherein the condition of 0.035 is satisfied. 45. The method for producing a magnetic toner according to claim 23, wherein the magnetic fine powder is contained in the magnetic toner particles in an amount of 45 to 55% by weight based on the weight of the magnetic toner particles. 46. The method according to claim 23, wherein the styrene resin has a weight average molecular weight of 150,000 to 350,000. 47. The magnetic toner particles have a BET specific surface area of 3
24. It is mixed with 0 ² / g or more of inorganic fine powder.
47. The method for producing a magnetic toner according to any one of the above items. 48. The inorganic fine powder has a BET specific surface area of 50.
Magnetic toner manufacturing method according to claim 47 which is ~400m ² / g. 49. The method according to claim 47, wherein the magnetic toner particles are mixed with 0.01 to 8 parts by weight of inorganic fine powder per 100 parts by weight. 50. The method according to claim 47, wherein the magnetic toner particles are mixed with 0.1 to 5 parts by weight of inorganic fine powder per 100 parts by weight. 51. The method for producing a magnetic toner according to claim 47, wherein the inorganic fine powder is a silica fine powder treated with silicone oil. 52. An electrostatic image carrier is charged by contact charging means to which a bias is applied, an electrostatic image is formed on the charged electrostatic image carrier by exposure, and the electrostatic image is formed by developing means having a magnetic toner. An image forming method for developing a static toner image to form a magnetic toner image, wherein the magnetic toner has magnetic toner particles containing at least a binder resin, a magnetic fine powder, and a wax. The particles have a weight average particle size of 3.5 to 6.5.
μm; the absorbance at a wavelength of 600 nm of a dispersion obtained by dispersing 15 mg of the magnetic toner particles in 19 ml of a mixture of ethyl alcohol and water (volume ratio 27:73) is 0.2 μm.
An image forming method of the image forming method. 53. The image forming method according to claim 52, wherein the contact charging means is a charging roller. 54. The magnetic toner image on the electrostatic image holder,
54. The image forming method according to claim 52, wherein the magnetic toner image on the transfer material is transferred by a transfer roller to which a bias is applied, and the magnetic toner image on the transfer material is fixed by a heat and pressure fixing unit. 55. The image forming method according to claim 52, wherein the magnetic toner is the magnetic toner according to any one of claims 2 to 22. 56. A process cartridge comprising an electrostatic image holder, a contact charging unit for charging the electrostatic image holder, and a developing unit for holding a magnetic toner, the process cartridge being detachable from the image forming apparatus main body. The magnetic toner has magnetic toner particles containing at least a binder resin, a magnetic fine powder and a wax, and the magnetic toner particles have a weight average particle diameter of 3.5 to 6.5.
μm; the absorbance at a wavelength of 600 nm of a dispersion obtained by dispersing 15 mg of the magnetic toner particles in 19 ml of a mixture of ethyl alcohol and water (volume ratio 27:73) is 0.2 μm.
A process cartridge of 0.7 to 0.7. 57. The process cartridge according to claim 56, wherein said contact charging means is a charging roller. 58. The process cartridge according to claim 56, wherein the electrostatic image holder is an OPC photosensitive drum. 59. The process cartridge according to claim 56, wherein the magnetic toner is the magnetic toner according to any one of claims 2 to 22.