JP2744397B2 - Image forming method - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to electrophotography and electrostatic recording.
To visualize an electrostatic latent image in an image forming method such as
And an image forming method using the magnetic toner. 2. Description of the Related Art In recent years, image forming apparatuses such as electrophotographic copying machines have been developed.
As it becomes more widespread, its uses are also becoming more diverse.
Demands for image quality have also become more stringent. General book
When copying an image such as a book or a book, the
Very fine without crushing or breaking
And it is required to be faithfully reproduced. In particular, the image
Lines with a latent image on the photoreceptor that the forming device has
Fine line reproducibility is generally poor in the case of images, and the sharpness of line images
But it is not enough. Recently, digital image
Image forming apparatus such as an electrophotographic printer using
Image, a latent image is formed by a collection of dots of a constant potential.
And solid, halftone and light areas are dots
It is expressed by changing the density. However,
The toner particles do not adhere to the dots,
When the particles protrude, the black and white parts of the digital latent image
Of the toner image corresponding to the dot density ratio of
There is a problem that is not. Further improve image quality
To improve the resolution by reducing the dot size
In some cases, the reproducibility of the latent image
Even more difficult, poor resolution and gradation, sharp
There is a tendency for images to lack ness. [0003] In the early stage, good image quality is obtained.
Continue to copy or print out
In addition, the image quality may deteriorate. This development is
As you continue printing or printing,
Only the easy-to-use toner particles are consumed first, and
By accumulating and remaining toner particles with poor imageability
It is thought to happen. Until now, the purpose of improving the image quality has been
For this reason, some developers have been proposed. JP 5
In Japanese Patent Application Laid-Open No. 1-3244, the particle size distribution is regulated to improve the image quality.
Non-magnetic toners intended for improvement have been proposed. The tona
, Toner mainly having a particle size of 8 to 12 μm
Is relatively coarse, and this particle size is
According to the report, it is difficult to achieve a dense "paste" on a latent image.
And 5 μm or less is 30% by number or less and 20 μm or more
Is less than 5% by number.
The fact that it is a mode also tends to reduce uniformity.
Such coarse toner particles and broad particles
A clear image using toner with a density distribution
To achieve this, the toner particles are
It is necessary to increase the apparent image density by filling the gap between
The amount of toner consumed to achieve the desired image density
There is also a problem that it increases. In Japanese Patent Application Laid-Open No. 54-72054,
Is a non-magnetic toner with a sharper distribution than the former
Proposed, but the size of particles of medium weight is 8.5-
As a 11.0 μm coarse and high-resolution toner,
However, there is still room for improvement. Japanese Patent Application Laid-Open No. 58-129439 discloses a flat
The average particle size is 6 to 10 μm, and the largest number of particles is 5 to 8 μm.
Non-magnetic toner has been proposed, but particles of 5 μm or less
Is as low as 15% by number, and an image lacking sharpness is formed.
Tend to [0007] According to the study of the present inventors, 5 μm or less
The toner particles clearly reproduce the outline of the latent image and
It has the main function of dense toner paste on the body
It was found. In particular, the electrostatic latent image on the photoreceptor
Due to the concentration of energy lines, the contoured edge is an electric field from the inside
Due to the high strength and the quality of the toner particles that collect in this area,
The sharpness of the image quality is determined. According to the study of the present inventors, 5 μm
The amount of particles less than m is effective in solving the problem of sharpness of image quality
Turned out to be. Further, US Pat. No. 4,299,900 is disclosed.
According to the book, 20 to 35 μm magnetic toner is 10 to 50 weight
% Developing method using a developer with
Have been. That is, the magnetic toner is frictionally charged and the toner is
A thin and even layer of toner on top of the developer
Innovative toner particle size suitable for improving environmental resistance
It has been done. However, fine line reproducibility, resolution, etc.
Given the more demanding requirements, it is not enough
In addition, improvements are required. The present inventors have
Spikes (toner particle chains) and turbulence in magnetic toner
The problem is that ears are present on the sleeve surface in the development area
It was found that this was the case.
It has been reached. [0009] The object of the present invention is to solve the above-mentioned problems.
Image forming method using magnetic toner which solved the above problems
It provides the law. [0010] Further, an object of the present invention is to provide a high image density.
Use magnetic toner with excellent fine line reproducibility and gradation
An image forming method is provided. It is a further object of the present invention to provide a long-term
Image forming method using magnetic toner with no change in performance
To offer. It is a further object of the present invention to provide a
Image forming method using magnetic toner with no change in performance
To provide. Another object of the present invention is to provide a magnetic recording medium having excellent transferability.
An image forming method using a neutral toner.
You. Furthermore, an object of the invention is to reduce the consumption
Uses magnetic toner capable of obtaining high image density
To provide an image forming method. It is a further object of the present invention to provide a digital image processing system.
In an image forming apparatus using signals, resolution, gradation,
An image forming method capable of forming a toner image with excellent fine line reproducibility
It provides the law. Means and Action for Solving the Problems Specifically, the present invention
According to the present invention, a gap is provided between a toner carrier containing a magnetic field generating means and a toner carrier.
Forming a latent image on a photoreceptor disposed
Binder resin and magnetic material provided with a triboelectric charge by the carrier
Having magnetic toner particles containing at least a conductive powder
Forming a toner layer of toner on the toner carrier;
-While applying a pulse electric field or AC bias to the carrier
The magnetic toner having a triboelectric charge from the toner carrier
To the photoconductor and develop the latent image with the magnetic toner.
The latent image having a particle size of 5 μm or less.
17 to 60% by number of magnetic toner particles,
1 to 23 magnetic toner particles having a particle size of 12.7 μm
Magnetic toner containing a number% and having a particle size of 16 μm or more
Particles containing less than 2.0% by volume of magnetic toner
Magnetic toner having a volume average particle diameter of 4 to 9 μm and 5 μm or less
-The particle group has the following formula: [Wherein N is a magnetic toner particle having a particle size of 5 μm or less.
V is a magnetic percentage having a particle size of 5 μm or less.
Indicates the volume% of the toner particles, and k is a positive number of 4.5 to 6.5.
Is shown. Here, N indicates a positive number of 17 to 60. ]
Magnetic toner with triboelectric charge with the added particle size distribution
It relates to an image forming method characterized by developing. Used in the present invention having the above particle size distribution
The magnetic toner extends to the fine lines of the latent image formed on the photoconductor.
Can be reproduced faithfully,
Excellent in reproducing dot latent images such as
Gives an image with excellent image quality. In addition, copy or
Maintains high image quality even when lint out is continued, and
Even with high density images, less than conventional magnetic toner
It is possible to perform good development with toner consumption,
Cost-effectiveness and downsizing of copiers or printers
It has advantages. In the magnetic toner used in the present invention,
It is not always clear why such effects can be obtained
Is estimated as follows. That is, the magnetic toner used in the present invention
In this case, magnetic toner particles having a particle size of 5 μm or less
One feature is that it is 60% by number. Conventionally, magnetic
In toner, magnetic toner particles of 5 μm or less are charged.
It is difficult to control the amount and the fluidity of the magnetic toner
As a component that damages the machine by scattering toner.
Furthermore, as a component that causes image fog,
Was thought to be necessary. However, according to the study of the present inventors,
For example, magnetic toner particles of 5μm or less form high quality image
Has been found to be an essential component for For example, grains ranging from 0.5 μm to 30 μm
Using a magnetic toner with a density distribution,
Large toner particles that are easy to develop
From image potential contrast to halftone,
Small development potential where only a few toner particles are developed
Latent that changes the surface potential on the photoconductor until the contrast
Develop the image, collect the developed toner particles on the photoreceptor,
When the toner particle size distribution was measured, the magnetic toner particles of 8 μm or less were measured.
Toner particles, especially magnetic toner particles of 5 μm or less.
Turned out to be. In other words, 5
Development of latent image on photoreceptor
Faithful to the latent image when supplied smoothly to the
A truly reproducible image can be obtained without protruding
Things. In the magnetic toner used in the present invention,
1 to 23% by number of particles in the range of 8 to 12.7 μm
Is one feature. This is as described above
Necessity of magnetic toner particles having a particle size of 5 μm or less
The magnetic toner particles having a particle size of 5 μm or less are
It has the ability to strictly cover latent images and reproduce them faithfully.
In the image itself, the electric field strength at the peripheral edge
Higher than the edge, so that the inside of the latent image
The paste of the toner particles becomes lighter, and the image density
There is. In particular, magnetic toner particles of 5 μm or less
Strong tendency. However, we have identified 8-12.
1% to 23% by number of toner particles in the range of 7 μm
To solve this problem,
I learned that I can do it. That is, 8 to 12.7 μm
Magnetic toner having a particle size in the range of 5 μm or less.
-A moderately controlled charge amount for particles
It is thought that the electric field strength is lower than the edge of the latent image.
Supplied inside a small inner tonner against the edge
-A uniform developed image is formed by compensating for the small amount of particle
As a result, excellent resolution and gradation
A sharp image is provided. Further, particles having a particle size of 5 μm or less
Between the number% (N) and the volume% (V), N / V
= −0.04N + k (however, 4.5 ≦ k ≦ 6.5; 17
≦ N ≦ 60), the magnetic toner used in the present invention is
Satisfaction is one of the features. Figure 2 shows this range
However, along with other characteristics, a particle size that satisfies this range
The magnetic toner used in the present invention of cloth achieves excellent developability
Can. The present inventors have proposed a particle size distribution of 5 μm or less.
Achieved the most objective as shown in the above formula
It has been found that there is a state of existence of the fine powder which is suitable for performing. You
That is, for a certain value of N, N / V is large.
Means that particles up to 5μm or less are widely contained
And that N / V is small means that
High abundance of particles and few particles with a size smaller than that
And the value of N / V is 2.1 to 5.82.
And N is in the range of 17 to 60, and
Good fine line reproduction when the above relational expression is further satisfied
And high resolution are achieved. Further, magnetic toner particles having a particle diameter of 16 μm or more
About 2.0% by volume,
Preferably. [0027] A completely different idea from the conventional viewpoint is used.
Thus, the magnetic toner of the present invention solves the conventional problems,
To withstand the demands of high image quality
It is. The structure of the present invention will be described in more detail.
do. All magnetic toner particles having a particle size of 5 μm or less
It is preferably 17 to 60% by number of children, and is preferably
25 to 50% by number is preferable, and more preferably 30 to 50%.
Number% is good. One magnetic toner particle having a particle size of 5 μm or less
Magnetic toner particles effective for high image quality when the content is less than 7% by number
Low, especially copy or printouts
As the toner is used, the effective magnetic
In the present invention, the magnetic particle component decreases,
The balance of the particle size distribution of the toner deteriorates, and the image quality gradually decreases.
Come down. If the content is more than 60% by number, the magnetic toner
Agglomeration between particles is likely to occur, and particles larger than the original
The image quality becomes rough and the resolution decreases
Or the difference in density between the edge of the latent image and
The image tends to be slightly hollow. Further, particles having a size in the range of 8 to 12.7 μm are 1
２３23% by number, preferably 8 to 20
A few percent is good. If the content is more than 23% by number, the image quality will deteriorate.
In both cases, unnecessary development, that is, excessive toner
This causes an increase in toner consumption. On the other hand, 1%
If it is less than 1, it becomes difficult to obtain a high image density. Also,
Number% of magnetic toner particles having a particle size of 5 μm or less (N
%) And volume% (V%), N / V = −0.04N +
k, and a positive number in the range of 4.5 ≦ k ≦ 6.5
Show. Preferably, 4.5 ≦ k ≦ 6.0, more preferably
Is 4.5 ≦ k ≦ 5.5. As indicated earlier, 17
≦ N ≦ 60, preferably 25 ≦ N ≦ 50, more preferably
In other words, 30 ≦ N ≦ 50. When k <4.5, particles smaller than 5.0 μm
The number of magnetic toner particles with a small diameter reduces image density, resolution, and sharpness.
Inferior in sharpness. In the past, it was often considered unnecessary.
Moderate presence of fine magnetic toner particles
To achieve the closest packing of toner,
Contribute to form an image. Especially thin lines and image contours
By evenly filling the parts, visually sharper
This is to encourage. That is, for k <4.5, this
Poor in these properties due to lack of particle size distribution components
It becomes a thing. From another point of view, also in production, k <4.5.
To satisfy the requirements, cut a large amount of fine powder by classification etc.
In terms of yield and toner cost.
It becomes something. In addition, when k> 6.5, more fine powder than necessary
Image, while continuing to copy repeatedly,
The image density tends to decrease. This phenomenon is not necessary
Excess of the finely charged magnetic toner particles
Charge on the sleeve, causing the toner
By inhibiting loading and charging
It is thought to be born. Further, magnetic toner particles having a particle diameter of 16 μm or more
It is preferable that the content is 2.0% by volume or less, and more preferable.
1.0% by volume or less, more preferably 0.5% by volume.
% By volume or less. If it is more than 2.0% by volume, fine line is reproduced
In addition to hindering the transfer,
16 μm or more on the thin layer surface of the toner particles developed on the body
Due to the existence of the coarse toner particles protruding, the toner layer
The delicate state of contact between the photoreceptor and the transfer paper through the
As a result, fluctuations in the transfer conditions are
This is a factor that generates an image. Also, the volume average of the magnetic toner
The diameter is 4 to 9 μm, preferably 4 to 8 μm.
It is not possible to think separately from each of the above components
I can't do it. When the volume average particle size is 4 μm or less,
For applications with a high image area ratio, such as fixed images, transfer paper
The problem is that the amount of applied toner is small and the image density is low.
Titles are likely to occur. This is because of the latent image described earlier.
For the same reason that the concentration inside the
It is thought to be. Resolution is more than 9μm in volume average particle size
Is not good, and at the beginning of copying
Image quality tends to deteriorate. The particle size distribution of the toner is measured by various methods.
In the present invention, the coulter counter
It was performed using. That is, as the measuring device,
Use Unter TA-II type (manufactured by Coulter, Inc.)
Interface to output distribution and volume distribution (Nikkaki
) And CX-1 personal computer (Canon
And the electrolyte is made of 1st grade sodium chloride.
% NaCl aqueous solution is prepared. The measurement method is
Surfactant as dispersant in 100-150ml of aqueous solution
Agent, preferably an alkyl benzene sulfonate, in 0.1
Add 5 ml, and further add 2-20 mg of the measurement sample.
The electrolyte in which the sample is suspended is used for about 1 to 3 minutes with an ultrasonic disperser.
Sprinkle treatment and apply to the Coulter Counter TAII
Using a 100μ aperture as an aperture,
Measure the particle size distribution of 2 to 40μ particles based on the number
Then, the values according to the present invention were determined. The true density of the magnetic toner used in the present invention
Is 1.45 to 1.70 g / cm ^Three Preferably
And more preferably 1.50 to 1.65 g / cm ^Three so
is there. Within this range, the specific particle size distribution of the present invention is possessed.
Magnetic toners have high image quality and durability stability.
Most effective. 1.45 true density of magnetic toner
If smaller, the magnetic toner particles themselves are too light
Reverse fog and fine lines due to excessive toner particle
Crushing, jumping, and deterioration of resolution are likely to occur.
If the true density of the magnetic toner is larger than 1.70, the image density is increased.
Images with low sharpness, such as thin lines and broken fine lines,
And the magnetic force is relatively large,
Are also likely to be long or branched, in this case,
When developing a latent image, the image quality is disturbed and the image tends to be rough
No. Measurement of the true density of the magnetic toner is performed by several methods.
In this application, we measure fine powder
In this case, the following method was adopted as an accurate and simple method. Stainless steel inner diameter 10 mm, length about 5 c
m cylinder with an outer diameter of approximately 10
mm, height 5mm disk (A), outer diameter about 10mm, length
A piston (B) having a length of about 8 cm is prepared. Cylinder
Put the disk (A) at the bottom, then put about 1g of measurement sample
Gently push the piston (B). Hydraulic press
400kg / cm ^Two Apply force and compress for 5 minutes
Take out what you have done. Weigh the weight of this compressed sample
(Wg) and the diameter of the compressed sample (D
cm) and height (Lcm), and the true density is calculated by the following equation.
Is calculated. [Outside 3] In order to obtain better developing characteristics,
Bright magnetic toner has a residual magnetization σ _r Is 1-5 emu / g good
More preferably, the saturation magnetization σ is 2 to 4.5 emu / g. _s But
20 to 40 emu / g, and the coercive force H _c Is 40 to 10
It is preferable to satisfy the magnetic properties of 0 esluted.
The magnetic properties are measured with a measurement field of 1000 Oersted.
Do. Binder used in the toner used in the present invention
As the resin, a heating and pressurizing unit equipped with an oil application device
When using a fusing device, use the following binder tree for toner.
Fats can be used. For example, polystyrene, poly-p-chloro
Styrene such as styrene and polyvinyl toluene
A styrene-p-chlorostyrene copolymer
Polymer, styrene-vinyltoluene copolymer, styrene
-Vinyl naphthalene copolymer, styrene-acrylic acid
Stel copolymer, styrene-methacrylic acid ester copolymer
Coalescence, styrene-α-chloromethyl methacrylate copolymer
Body, styrene-acrylonitrile copolymer, styrene-
Vinyl methyl ether copolymer, styrene-vinyl ethyl
Copolymer, styrene-vinyl methyl ketone copolymer
Polymer, styrene-butadiene copolymer, styrene-a
Soprene copolymer, styrene-acrylonitrile-yne
Styrene copolymers such as den copolymers; polyvinyl chloride
Phenolic resin, natural modified phenolic resin, natural tree
Fat-modified maleic resin, acrylic resin, methacrylic tree
Fat, polyvinyl acetate, silicone resin, polyester
Resin, polyurethane, polyamide resin, furan resin, d
Epoxy resin, xylene resin, polyvinyl butyral,
Lupine resin, Coumarone indene resin, petroleum resin, etc.
Can be used. Heat and pressure roller with almost no oil applied
In the fixing method, the toner image on the toner image support member is
The so-called offset phenomenon, in which a part transfers to the roller, and
Is important for toner adhesion to the toner image support member
It is a title. Toner fixing with less heat energy
Is usually blocked or stored in a developer.
Has the property of being easy to cake.
Issues must also be considered. These phenomena include toner
Although the physical properties of the binder resin in the
According to a study by the authors, the content of magnetic substances in toner was reduced.
When fixing, the toner density on the toner image
Although the adhesiveness improves, offset tends to occur, and
Blocking or caking tends to occur. It
Therefore, in the present invention, heating and pressurization with almost no oil applied
When using the roller fixing method, the choice of binder resin is
is important. Preferred binders include crosslinked
Tylene copolymer or cross-linked polyester
You. As the styrene monomer of the styrene copolymer
Examples of the comonomer include acrylic acid and acrylic acid.
Methyl acrylate, ethyl acrylate, butyl acrylate,
Dodecyl acrylate, octyl acrylate, acrylic acid
-2-ethylhexyl, phenyl acrylate, methacrylic
Phosphoric acid, methyl methacrylate, ethyl methacrylate, meth
Butyl acrylate, octyl methacrylate, acrylonitrile
Like ril, methacrylonitrile, acrylamide etc
A monocarboxylic acid having a double bond or a substituted product thereof;
For example, maleic acid, butyl maleate,
Has double bonds such as tyl, dimethyl maleate, etc.
Dicarboxylic acids and their substituted products; for example, vinyl chloride,
Vinyl aesthetics such as vinyl acetate, vinyl benzoate, etc.
Such as ethylene, propylene, butylene, etc.
Ethylene olefins such as vinyl methyl keto
Vinyl ketones such as vinyl hexyl ketone
And the like; for example, vinyl methyl ether, vinyl ethyl ether
Vinyl ether such as vinyl isobutyl ether
Vinyl monomers such as ters; used alone or in combination of two or more
Can be Here, as the crosslinking agent, two or more
Compounds having a polymerizable double bond are used, for example,
Such as divinylbenzene, divinylnaphthalene, etc.
Aromatic divinyl compounds; for example, ethylene glycol di
Acrylate, ethylene glycol dimethacrylate,
Such as 1,3-butanediol dimethacrylate
Carboxylic acid ester having two double bonds; divinyla
Niline, divinyl ether, divinyl sulfide, divinyl
Divinyl compounds such as nilsulfone; and 3 or more
Compound having vinyl group; alone or as a mixture
Used. When the pressure fixing method is used, the pressure
It is possible to use binder resin for force fixing toner.
Polyethylene, polypropylene, polymethylene, polyurethane
Tan elastomer, ethylene-ethyl acrylate
Coalescence, ethylene-vinyl acetate copolymer, ionomer tree
Fat, styrene-butadiene copolymer, styrene-isop
Len copolymer, linear saturated polyester, paraffin, etc.
There is. The magnetic toner used in the present invention has a load.
Blending (internally) the charge control agent with the toner particles
It is preferable to use it by mixing (externally adding) it with a child. Charge control
Optimum charge amount control depending on the development system
Rolling becomes possible, and especially in the present invention, particle size distribution and charging
Balance can be made more stable.
In addition, by using a charge control agent,
Function separation and complementation for high image quality by range
Sex can be made clearer. As a positive charge control agent
Is a modified product of nigrosine and a metal salt of a fatty acid;
Ributylbenzylammonium-1-hydroxy-4-
Naphthosulfonate, tetrabutylammonium tet
Quaternary ammonium salts such as lafluoroborate; Djibouti
Ruthenium oxide, dioctyltin oxide, disucci
Diorganotin oxa such as rohexyl tin oxide
Id; dibutyltin borate, dioctyltin volley
Diorganos such as dicyclohexyltin borate
Zuborate alone or in combination of two or more
Can be used. Among these, nigrosine,
Particularly preferred is a charge control agent such as a quaternary ammonium salt.
Can be. Also, aminoacrylic monomer or amino
Nomethacrylic monomer homopolymer: or as described above
Styrene, acrylate, methacrylate
A copolymer with a polymerizable monomer such as
And in this case these charge control agents
Also acts as (all or part of) the binder resin.
I do. Load control which can be used in the present invention
Examples of the agent include an organometallic complex and a chelate compound.
For example, aluminum acetylacetonate
G, iron (II) acetylacetonate, 3,5-diter
Chromium, such as shary butyl salicylate, especially acetyl
Luacetone metal complex, salicylic acid metal complex or salt
Preferred, especially salicyl metal complex or salicylic acid
Metal salts are preferred. The above-described charge control agent (work as a binder resin)
That have no use) is preferably used in the form of fine particles.
Good. In this case, the number average particle size of the charge control agent is
Specifically, 4 μm or less (more preferably 3 μm or less) is preferred.
No. When the toner is internally added to the toner, such charge control is performed.
The agent is 0.1 to 20 parts by weight based on 100 parts by weight of the binder resin.
Parts (more preferably 0.2 to 10 parts by weight)
No. The magnetic toner used in the present invention has
It is preferable to add fine lica powder. Features of the present invention
The specific surface area of a magnetic toner having a particle size distribution
Is larger than the conventional toner. Magnetic for tribocharging
A cylindrical conductive member having a magnetic field generating means therein;
When brought into contact with the conductive sleeve surface,
-The number of contacts between the toner particle surface and the sleeve increases
Toner particles and sleeve surface contamination
It will be cool. The magnetic toner according to the present invention and silica fine powder
Silica between toner particles and sleeve surface when combined
Abrasion is significantly reduced by the presence of the fine powder. this
Longer life of magnetic toner and sleeve
At the same time as maintaining stable charging properties.
Developer with better magnetic toner
It is possible to Furthermore, it plays a major role in the present invention.
The magnetic toner particles having a particle size of 5 μm or less
The effect of fine powder is more effective and high quality
Can be provided. As the silica fine powder, a dry method and a wet method
Any silica fine powder produced by the method can be used.
Silica by dry method from the viewpoint of filming property and durability
It is preferable to use fine powder. The dry method referred to herein means a silicon halide.
Of fine silica powder produced by vapor phase oxidation of compound
Is the law. For example, in the oxygen hydrogen of silicon tetrachloride gas
This method utilizes a thermal decomposition oxidation reaction. In addition, this product
In the manufacturing process, for example, aluminum chloride or chloride
Other metal halides such as titanium
Silica and other metal oxidation by use with compounds
It is also possible to obtain composite fine powder of
I do. The silicon halide compound used in the present invention
Commercial silica fine powder produced by vapor phase oxidation of
Then, for example, it is marketed under the following trade names
There is AEROSIL (Aerosil Japan) 130 200 300 380 OX50 TT600 MOX80 MOX170 COK84 Ca-O-SiL (CABOTO Co.) M-5 MS-7 MS-75 HS-5 EH-5 Wacker HDK N20 V20 (WACKER-CHEMIE GMBH) N20E T30 T40 DC Fine Silica (Dow Corning Co.) Fransol (Fransil) On the other hand, the silica fine powder used in the present invention was prepared as follows.
Various methods known in the art include a wet method.
Can be applied. For example, with sodium silicate acid
Decomposition. In addition, ammonium silicate of sodium silicate
Or alkali salts, sodium silicate
After the alkaline earth metal silicate is formed, it is separated with acid.
Method of dissolving silicic acid, ionizing sodium silicate solution
Method of converting silicic acid with exchange resin, natural silicic acid
There is a method using an acid salt. The silica fine powder referred to here includes anhydrous dioxide.
Silicon (silica), other aluminum silicate, silicon
Sodium silicate, potassium silicate, magnesium silicate,
Any silicate such as zinc silicate can be applied. A commercially available fine silica powder synthesized by a wet method is used.
For example, it is commercially available under the following trade names
There is something. Carplex Shionogi Pharmaceutical Neep Seal Nippon Silica Tokusil, Fine Seal Tokuyama Soda Vita Seal Takihito Shilton, Silnex Mizusawa Chemical Star Sill Kamijima Chemical Himejir Ehime Pharmaceutical Syloid Fuji Devison Chemical Hi-Sil (Hi-Sil) Pittsburgh Plate Glass. C
o. (Pittsburgh plate glass) Durosil (Duroseal) Ultrasil (Ultraseal) Fiillstoff-Gesellschaft M
arquart (Fürstoff Gesell shaft)
Marc Ort) Manosil (Manosir) Hardman and Holden (Hard Man)
And Holden) Hoesch (Hesch) Chemische Fabrik Hoesche KG (Heemitsche, Fabrik
Hesh) Sil-Stone (Stone Stone) Stoner Rubber Co. (Stonener
Bar) Nalco (Nalco) Nalco Chem. Co. (Narco Chemical) Quoso (Philadelphia Quartz Co.) (F
(Iradelphia Quartz) Imsil Illinois Minerals Co. (Illino
Chair mineral) Calcium Silkat (calcium zirica)
Chemische Fabrik Hoesch. K
-G (Hiemische Fabrik Hesch) Calsil (Fillstoff-Gesellschaft M)
arquart
Marc Ort) Fortafil Imperial Chemical Industr
ies. Ltd. (Imperial Chemical Indus
(Tries) Microcal (Microcal) Joseph Crossfields & Sons. L
td. (Joseph Crossfield and Sun
) Manosil Hardman and Holden
And Holden) Vulkasil Farbenfabriken Bryer, A. et al. −
G. FIG. (Fanben Fabry Ken Bair) Tufknit (Tuffnit) Durham Chemicals. Ltd. (Doul
Ham Chemicals) Sirmos Shiraishi Kogyo Star Rex Kamishima Chemical Fricosyl Tawood Manure Of the above silica fine powders, measured by the BET method
30m specific surface area by fixed nitrogen adsorption ^Two / G or more (Special
50-400m ^Two / G) is a good result.
give. Silica fine powder for 100 parts by weight of magnetic toner
0.01 to 8 parts by weight, preferably 0.1 to 5 parts by weight
Good to use. Further, the magnetic toner of the present invention may be a positively charged magnetic toner.
When used as toner, prevent toner wear and
Silica fine powder added to prevent surface contamination
However, rather than negatively charged, finely charged silica fine powder
It is preferable to use it without impairing the charging stability. As a method for obtaining a positively chargeable silica fine powder,
Refers to the above-mentioned untreated silica fine powder,
Having an organo group having at least one or more
Oil treatment or nitrogen-containing silane
Treatment with a coupling agent, or both.
There is a method. In the present invention, the positively chargeable silica is
When measured by the blow-off method,
It has a tris charge of lath. Examples of such treating agents include aminopro
Piltrimethoxysilane, aminopropyltriethoxy
Silane, dimethylaminopropyltrimethoxysilane,
Diethylaminopropyltrimethoxysilane, dipropyl
L-aminopropyltrimethoxysilane, dibutylamino
Propyltrimethoxysilane, monobutylaminopropyl
Rutrimetroxysilane, dioctylaminopropyl
Limethoxysilane, dibutylaminopropyldimethoxy
Silane, dibutylaminopropylmonomethoxysilane,
Dimethylaminophenyltriethoxysilane, trimeth
Xysilyl-γ-propylphenylamine, trimethyoxy
And silicyl-γ-propylbenzylamine.
As the nitrogen-containing heterocycle, those having the above-mentioned structure can be used,
Examples of such compounds include trimethoxysilyl-
γ-propylpiperidine, trimethoxysilyl-γ-p
Propyl morpholine, trimethoxysilyl-γ-propyl
And imidazole. These treated positively charged silica fine powders
Is applied to 100 parts by weight of the positively charged magnetic toner.
The effect is exhibited when the amount is 0.01 to 8 parts by weight.
Preferably, when 0.1 to 5 parts by weight are added, excellent stability is obtained.
It has positive chargeability. Preferred for addition form
In other words, the amount of the toner is 100 parts by weight of the positively charged magnetic toner.
Then, 0.1 to 3 parts by weight of the treated silica fine powder
It is good to be in a state of being attached to the surface of the toner particles. What
The untreated silica fine powder described above is also suitable for
It can be used in dosages. The silica fine powder used in the present invention
Is the silane coupling agent, if necessary,
May be treated with a treating agent such as an organosilicon compound.
The above treatment which reacts or physically adsorbs with silica fine powder
Treated with the agent. Such treatment agents include, for example,
Xamethyldisilazane, trimethylsilane, trimethyl
Chlorosilane, trimethylethoxysilane, dimethyldi
Chlorosilane, methyltrichlorosilane, allyl dimethyl
Ruchlorosilane, allylphenyldichlorosilane, ben
Jil dimethyl chlorosilane, bromomethyl dimethyl chloro
Silane, α-chloroethyltrichlorosilane, β-c
Lorethyltrichlorosilane, chloromethyldimethylc
Lorsilane, triorganosilyl mercaptan, trime
Tilsilyl mercaptan, triorganosilyl acryle
Sheet, vinyl dimethylacetoxysilane, dimethyl eth
Xysilane, dimethyldimethoxysilane, diphenyldi
Ethoxysilane, hexamethyldisiloxane, 1,3-
Divinyltetramethyldisiloxane, 1,3-diphenyl
Letetramethyldisiloxane, and from 2 per molecule
It has 12 siloxane units and is located at the terminal
Dyes containing hydroxyl groups bonded to Si
Tyl polysiloxane and the like. One or two of these
Used in the above mixture. In the present invention, the fluorine-containing polymer
Fine powder such as polytetrafluoroethylene, polyvinyl
Nilidene fluoride and tetrafluoroethylene
-Add fine powder of vinylidene fluoride copolymer
Is preferred. In particular, polyvinylidene fluoride fine
Powders are preferred in terms of fluidity and abrasiveness. Toner
The added amount is 0.01 to 2.0 wt%, particularly 0.02 to 2.0 wt%.
1.0 wt% is preferred. In particular, a combination of silica fine powder and the above fine powder
Although the reason is not clear,
Stabilizes the presence of silica attached to the toner.
For example, the adhered silica is released from the toner,
Without reducing wear and sleeve fouling
And it is possible to further increase the charging stability.
is there. The magnetic toner used in the present invention may be used if necessary.
The additives may be mixed together. Conventional colorant
Known dyes and pigments can be used, usually bound
0.5 to 20 parts by weight for 100 parts by weight of resin
Is also good. Other additives include, for example, zinc stearate.
Such as cerium oxide and silicon carbide
Abrasive or colloidal silica, aluminum oxide
Fluidity-imparting agents such as um, anti-caking agents, or
For example, conductivity imparting agents such as carbon black and tin oxide
is there. Further, the releasability at the time of hot roll fixing is improved.
Low molecular weight polyethylene, low molecular weight polypropylene for the purpose
, Microcrystalline wax, carnauba wax
Wax, sasol wax, paraffin wax, etc.
0.5% to 5% by weight of magnetic material
This is one of the preferred embodiments of the present invention. Further, the magnetic toner used in the present invention is colored.
Although it may also function as an agent, it contains a magnetic material.
The magnetic material contained in the magnetic toner of the present invention includes
Gnetite, γ-iron oxide, ferrite, iron-rich ferrule
Iron oxides such as iron; metals such as iron, cobalt and nickel
Or these metals and aluminum, cobalt, copper, lead,
Magnesium, tin, zinc, antimony, beryllium,
Bismuth, cadmium, calcium, manganese, selenium
Metals such as titanium, titanium, tungsten, and vanadium
Alloys and mixtures thereof. These ferromagnetic materials have an average particle size of 0.1 to 1
μm, preferably about 0.1 to 0.5 μm
The amount of the resin component 1
60 to 110 parts by weight, preferably resin, per 100 parts by weight
65 to 100 parts by weight per 100 parts by weight of the component. Magnetic toner for developing an electrostatic image used in the present invention
To make a magnetic powder, use magnetic powder and vinyl or non-vinyl
Thermoplastic resin, if necessary pigments as colorants or
Dyes, charge control agents, other additives, etc.
After mixing well with a mixing machine, heat the roll and kneader.
Melting and kneading using a hot kneader such as extruder
Pigment was mixed with resin by mixing and mixing
Alternatively, disperse or dissolve the dye, cool and solidify, then pulverize
The magnetic toner according to the present invention is subjected to strict classification.
-Can be obtained. The magnetic toner used in the present invention is a cylindrical toner.
To a latent image carrier such as a photoconductor
An image forming method that develops a latent image while flying toner
It is preferably applied. That is, magnetic toner is mainly
The triboelectric charge is imparted by contact with the
It is applied in a thin layer on the surface of the leave. Thin layer of magnetic toner
Is the gap between the photoreceptor and the sleeve in the development area.
It is formed thinner. When developing a latent image on a photoreceptor
Applies an alternating electric field between the photoreceptor and the sleeve
Transfer magnetic toner with tribo-charge from sleeve to photoconductor
Good to fly. As the alternating electric field, a pulse electric field, an alternating current
Examples of synergistic or AC and DC bias
Is done. In the present invention, the fine line reproducibility is as follows.
The measurement was performed by such a method. That is, exactly width 1
Appropriate duplication of original original with a fine line of 00 μm
The image copied under the conditions is used as a measurement sample, and the measurement device
Using a Luzex 450 particle analyzer
From the enlarged monitor image using the indicator.
And measure the line width. At this time, the line width measurement position is
-The fine line image has unevenness in the width direction.
The line width is used as the measurement point. This allows fine line reproducibility
The value (%) is calculated by the following equation. [Outside 4] In the present invention, the resolution is measured by the following method.
Made by. That is, 5 with the same line width and spacing
It is a pattern consisting of two thin lines.
3.2, 3.6, 4.0, 4.5, 5.0, 5.6,
6.3, 7.1 or 8.0 are drawn
Create an original image. Have these 10 line images
Image of original document copied under proper copying conditions
Is observed with a magnifying glass, and the image where fine lines are clearly separated
The number of images (lines / mm) is defined as the value of the resolving power. The larger the number, the higher the resolution.
Is shown. EXAMPLES The present invention will be specifically described below with reference to examples.
However, this does not limit the present invention in any way. Note that
All parts in the following formulations are parts by weight. Example 1 Styrene / butyl acrylate / divinylbenzene copolymer
Body (copolymer weight ratio 80 / 19.5 / 0.5, weight average
100,000 parts by weight Iron trioxide (average particle size 0.2 μm) 80 parts by weight Nigrosine (number average particle size about 3 μm) 4 parts by weight Low molecular weight propylene-ethylene copolymer 4 parts by weight Blend the above material After mixing well, set at 150 ° C.
The mixture was kneaded with a specified twin-screw kneading extruder. The obtained kneaded material is
After cooling and coarsely pulverizing with a cutter mill, jet stream
Finely pulverized using a fine pulverizer using
Was classified with a fixed wall type air classifier to produce a classified powder. Sa
In addition, the obtained classified powder is multi-divided using the Coanda effect
Ultra fine using a classifier (Elbow jet classifier manufactured by Nippon Steel Mining)
Strict classification and removal of pulverized and coarse powder at the same time
A fine black powder (magnetic toner) having a diameter of 7.4 μm was obtained. Get
The black fine powder mixed with iron powder carrier
When the charge was measured, it had a value of +8 μc / g. Magnetic properties of the obtained positively chargeable black fine powder
A toner having a 100 μ aperture as described above is used.
The data measured using the counter II
It is shown in Table 1 below. [Table 1] For reference, classification using a multi-segment classifier was performed.
The classifying process is schematically shown in FIG.
A perspective view (three-dimensional view) is shown in FIG. 100 weights of the obtained black fine powder magnetic toner
Amount of positively charged hydrophobic fumed silica (BET specific surface area 20
0m ^Two / G) Add 0.5 parts by weight and add Henschel mixer
Positively chargeable one-component magnetic toner with magnetic toner
An image agent. The particle size distribution and various characteristics of this magnetic toner are as follows.
As shown in Table 3. The prepared one-component developer is shown in FIG.
It was put into the developing device shown and a development test was performed. The developing conditions will be described with reference to FIG.
You. Having hydrophobic silica fine powder on the surface of magnetic toner particles
The magnetic toner (one-component developer) 31 is moved in the direction of arrow 36.
Magnetic on the surface of stainless steel cylindrical sleeve 33 which rotates
A thin layer is applied via a blade 32 and
The gap between the blades 32 was set to about 250 μm. Three
The block 33 has a fixed magnet 35 as a magnetic field generating means,
Photosensitive drum having an organic photoconductive layer having an electrostatic latent image
34 and in the vicinity of the sleeve surface in the development area close to
The fixed magnet 35 forms a magnetic field of 1000 Gauss. arrow
Photosensitive drum 34 and sleeve 33 rotating in the direction of mark 37
Was set to about 300 μm. In addition, photosensitive dora
Bias applying means 38 between the system 34 and the sleeve 33.
2000 that synergized AC bias and DC bias
A bias of Hz / 1350 Vpp was applied. sleeve
33 has a thickness of about 75 to 150 μm.
In the developing area, the magnetic toner has a height of about 95 μm.
m ears were formed. Loaded electrostatic latent image formed on photosensitive drum 34
To the one-component developer 31 having a positively charged triboelectric charge.
Developed. Repeat the image output test 10,000 times
To produce 10,000 toner images. The result
It is shown in Table 4. As is apparent from Table 4, lines such as characters
Area and large area both have high image density, fine line reproducibility,
The magnetic toner of the present invention is also excellent in resolution, and 10,000
Even after the single-image output, the original image quality was maintained. Ma
Also, the per copy cost is small and the economy is excellent
It was. The multi-segment classifier used in this embodiment and
See FIGS. 3 and 4 for the classification process by the classifier.
I will explain while. The multi-segment classifier 1 is shown in FIGS.
In the side wall has the shape shown at 22, 24,
The part wall has a shape indicated by 25, the side wall 23 and the lower wall 2
5 is a knife edge type classification edge 17, 18 respectively.
The classification edges 17 and 18 provide a classification zone.
Are divided into three parts. Open to the classifying room under the side wall 22
And a bottom tangent to the nozzle.
Bent downward in the direction of extension of
A Coanda block 26 is provided. Classification room upper wall 27
A knife edge type inlet edge 19 is provided in the lower part of the classification chamber.
In addition, at the top of the classification room, an air intake tube 1 opening to the classification room
4 and 15 are provided. In addition, the intake pipes 14 and 15
First and second gas introduction adjusting means 20, 21 such as
And static pressure gauges 28 and 29 are provided. It is on the low side of the classification room
Equipped with an exhaust port that opens into the room to correspond to each
Discharge pipes 11, 12, and 13 are provided. Classified powder is provided
The pressure is introduced from the supply nozzle 16 into the classification area, and the Coanda effect
The result of the Coanda effect of the Coanda block 26
Curve due to the action of high-speed air flowing in
30 to move the coarse powder 11, a predetermined volume average particle size and
Fine powder 12 and ultrafine powder 13 having particle size distribution
Was classified. Example 2 Instead of the toner used in Example 1, the amount of magnetic powder added was
By controlling the change and fine grinding classification conditions
Except that toner having various properties as shown in Table 3 is used.
Was evaluated in the same manner as in Example 1. As shown in Table 4, stable and clear high image quality
Image was obtained. Example 3 In place of the toner used in Example 1, various characteristics shown in Table 3 were used.
Same as Example 1 except that a toner showing the property is used.
Was evaluated. As shown in Table 4, stable and clear high image quality
Image was obtained. Example 4 100 parts by weight of the black fine powder of Example 1 was
0.5 parts by weight of dry silica, polyvinylidene fluoride fine powder
(Average primary particle size about 0.3 μm, average weight molecular weight 300,000)
Add 0.3 parts by weight and mix with a Henschel mixer.
The evaluation was performed in the same manner as in Example 1 using the component developer.
As shown in Table 4, both image density and image quality stability
Excellent images were obtained. Example 5 Crosslinked polyester resin (Mw 50,000, Tg 60 ° C.) 10
0 parts by weight 3,5-di-t-butylsalicylic acid metal salt 1 part by weight Iron tetroxide (average particle diameter 0.2 μm) 70 parts by weight Low molecular weight propylene-ethylene copolymer 3 parts by weight And the same as in Example 1
Thus, a black fine powder was obtained. This black fine powder (magnetic toner)
100 parts by weight of negatively charged hydrophobic silica fine powder (BET)
Specific surface area 130m ^Two / G) 0.3 parts by weight
Mix with a gel mixer to obtain a one-component negative magnetic developer.
Prepared. Table 3 shows the particle size distribution and the like of this black fine powder.
It was as follows. One-component magnetic developer having negative triboelectric charge
Is converted to amorphous silicon which forms a positively charged electrostatic image.
Developing three with a photosensitive drum and a fixed magnet
AC bias and DC bias are applied to the
NP7550 (manufactured by Canon Inc.)
An image test was performed. As shown in Table 4, stable and clear high image quality
Images were obtained. Example 6 Using the positively chargeable one-component magnetic developer prepared in Example 1,
To apply a positive frictional charge to the magnetic toner with the developing sleeve
And an amorphous silicon photosensitive drum
AC bias and DC bias are applied to the developing sleeve containing the stone.
Digital copier NP9330 applying bias
(Manufactured by Canon Inc.) to reverse the positively charged electrostatic charge image
Performed image output test on 10,000 sheets by applying
Was. As shown in Table 4, fine line reproducibility and resolution
The image was excellent and had a sharp gradation. Example 7 A black fine powder described in Table 3 was prepared in the same manner as in the production method described in Example 1.
A powder is prepared, and 100 parts by weight of the black fine powder is positively charged.
Mixing with 0.6 parts by weight of hydrophobic silica to form positive charge
A demagnetized developer was produced. To the obtained one-component magnetic developer
A positive triboelectric charge is applied by the developing sleeve,
Developing with an electro-sensitive photosensitive drum and including a fixed magnet
Do not apply AC or DC bias to the sleeve.
Applied to a commercially available copier NP3525 (manufactured by Canon Inc.)
Then, an image output test of 10,000 sheets was performed. Table 4 shows the results
Shown in Comparative Example 1 A fixed-wall type air classifier and a multi-segment classifier used in Example 1
Using two fixed wall type air classifiers without using
Except for classification, the black color shown in Table 3 was the same as in Example 1.
Fine powder (magnetic toner) was prepared. Black fine powder of Comparative Example 1
The magnetic toner is a magnetic toner having a particle diameter of 5 μm.
-The number% of particles is less than the range specified in the present invention,
The volume average particle size is larger than the range specified in the present invention and 5
Number% (N) of magnetic toner particles having a particle size of μm or less
/ Volume% (V) is also large and defined by the present invention.
The conditions are not satisfied. Particle size distribution of the obtained magnetic toner
Are shown in Table 2. [Table 2] In the same manner as in Example 1, a fine black powder was obtained.
Positively charged hydrophobic dry silica in 100 parts by weight of magnetic toner
0.5 part by weight was mixed to prepare a one-component magnetic developer.
An image-drawing test was performed under the same conditions as in Example 1. Height of ear in sleeve 33 in development area
The length is about 165μm, longer ears are formed compared to Example 1.
It had been. The resulting toner image is formed on a photoreceptor.
Many toner particles protrude from the latent image, resulting in fine line reproducibility
Was 135%, which was worse than that of Example 1, and the resolution was 4.5.
It was a book. Furthermore, after 10,000 images are printed,
A decrease in black density, deterioration in fine line reproducibility, and resolution were observed.
Also, the toner consumption was large. Table 4 shows the results. Comparative Example 2 The results are shown in Table 3 in place of the magnetic toner used in Example 1.
Evaluation was performed in the same manner as in Example 1 except that such a toner was used.
Value. [0111] The thin line indicates that the toner particles are agglomerated.
Produces dirt which is considered to be caused by the body and has a resolution of 4.5 lines
/ Mm with respect to the density of the line and the image edge portion.
Low solid black and low density inside the image
Met. Spot-like fog stains also occurred. Also copy
The image quality was further degraded by repeating. Comparative Example 3 The results are shown in Table 3 in place of the magnetic toner used in Example 1.
Except for using the magnetic toner described above,
An evaluation was performed. In the development on the drum, there is a slight disturbance.
However, although the image quality was relatively good,
Disturbance, poor transfer, and lower density
Was. In particular, when you repeat a copy, bad toner particles
Since the toner remains and accumulates in the developing machine,
It got worse. Comparative Example 4 The results are shown in Table 3 in place of the magnetic toner used in Example 1.
The evaluation was performed in the same manner as in Example 1 except that the magnetic toner was used.
Value. The image density is low, and the toner
Poor glue results in blurred outlines and lack of sharpness
It was a dim image. The resolution and gradation were poor. Also, by making repeated copies, the system
The sharpness, fine line reproducibility and resolution were further deteriorated. Comparative Example 5 The results are shown in Table 3 in place of the magnetic toner used in Example 1.
The evaluation was performed in the same manner as in Example 1 except that the magnetic toner was used.
Value. As a result, the image density, resolution, fine line reproducibility
Both were inferior. The toner carrier in the developing machine
Observing the ears of toner on the sleeve
It was sparse, and the ears were too long, even when flying over the photoreceptor
The tailing state where the toner protrudes from the latent image
Density due to coarseness of toner particles
I could see a lightning. [Table 3] [Table 4] Examples 8 to 10 In the same manner as in Example 1, magnetic toners shown in Table 5 were prepared.
Was. [Table 5] Using the magnetic toners of Examples 8 to 10,
Example 1 A one-component magnetic developer was prepared in the same manner as in Example 1.
An image output test was performed in the same manner as in Example 1. In each example,
Although the same good developing characteristics as in Example 1 were exhibited, Example 8
In this case, fine line reproducibility and resolution were slightly
Inferior, and in Example 9, due to repeated copying
The stability of the image quality is slightly inferior to that of the first embodiment.
10, the solid black image density was slightly inferior to that of Example 1.
I was FIG. 2 shows 5 μm in Example and Comparative Example.
% (N) of magnetic toner particles having a particle size of not more than m
2 shows a graph in which the values of /% by volume (V) are plotted. solid line
The inside surrounded by is within the scope of the present invention. Scope of the invention
The outer magnetic toner is finer than the magnetic toner of the present invention.
Line reproducibility, resolution, solid black image density, fog,
And / or toner consumption as described above. Example 11 Example 1 was repeated except that the amount of the magnetic material was reduced to 55 parts by weight.
A magnetic toner was prepared in the same manner as described above. Magnetic toner obtained
And a one-component magnetic developer in the same manner as in Example 1
It was prepared and subjected to an image output test in the same manner as in Example 1.
Fog slightly increased compared to the image obtained in Example 1.
And the reproducibility of fine lines was slightly inferior. Example 12 Example 1 was repeated except that the amount of the magnetic material was increased to 120 parts by weight.
A magnetic toner was prepared in the same manner as described above. Magnetic toner obtained
And a one-component magnetic developer in the same manner as in Example 1
It was prepared and subjected to an image output test in the same manner as in Example 1.
Image density of solid black portion compared to image obtained in Example 1
Is slightly thinner, and the sharpness of the toner image is slightly inferior.
I was The image forming method of the present invention has a high resolution.
Excellent toner reproducibility and high image density
Can be provided with no toner consumption.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view showing a specific example of an image forming apparatus for performing an image forming method of the present invention. FIG. 2 is a graph plotting the value of the number% (N) / volume% (V) of particles having a particle diameter of 5 μm or less in a magnetic toner. FIG. 3 is an explanatory diagram relating to a classification step using a multi-division classification means. FIG. 4 is a schematic cross-sectional perspective view of a multi-segment classification means. DESCRIPTION OF SYMBOLS 1 Multi-segmentation classifier 11 Coarse powder 12 Powder having predetermined particle size 13 Fine powder 26 Coanda block 31 One-component magnetic toner 32 Magnetic blade 33 Developing sleeve 34 Photosensitive drum 35 Fixed magnet 38 Bias applying means

Continuation of front page    (72) Inventor Naoki Matsushige               3-30-2 Shimomaruko, Ota-ku, Tokyo               Non Corporation (72) Inventor Satoshi Yoshida               3-30-2 Shimomaruko, Ota-ku, Tokyo               Non Corporation (72) Inventor Masaji Fujiwara               3-30-2 Shimomaruko, Ota-ku, Tokyo               Non Corporation (72) Inventor Yasuo Mihashi               3-30-2 Shimomaruko, Ota-ku, Tokyo               Non Corporation                (56) References JP-A-58-95748 (JP, A)                 JP-A-59-187347 (JP, A)                 JP-A-61-42665 (JP, A)                 JP-A-61-166553 (JP, A)                 JP-A-55-48772 (JP, A)

Claims (1)

(57) [Claims] Magnetic toner particles that form a latent image on a photoconductor that is arranged with a gap from a toner carrier that contains a magnetic field generating means, and that at least contain a binder resin and magnetic powder, and that have been given a triboelectric charge by the toner carrier. Forming a toner layer of a magnetic toner having the following formula on the toner carrier, and transferring the magnetic toner having a triboelectric charge from the toner carrier to the photoconductor while applying a pulse electric field or an AC bias to the toner carrier. And developing the latent image with the magnetic toner. The latent image contains 17 to 60% by number of magnetic toner particles having a particle size of 5 μm or less, and has a particle size of 8 to 12.7 μm. 1 to 23% by number of magnetic toner particles having
2.0% by volume of magnetic toner particles having a particle size of not less than μm
The magnetic toner has a volume average particle diameter of 4 to 9 μm.
m, and a group of magnetic toner particles of 5 μm or less is represented by the following formula: [Wherein, N represents the number% of magnetic toner particles having a particle size of 5 μm or less, V represents the volume% of magnetic toner particles having a particle size of 5 μm or less, and k represents 4.5 to 6.5. Indicates a positive number. Here, N indicates a positive number of 17 to 60. And developing with a magnetic toner having a triboelectric charge having a particle size distribution satisfying the following. 2. The image forming method according to claim 1, wherein the magnetic toner has a volume average particle diameter of 4 to 8 μm. 3. 3. The image forming method according to claim 1, wherein the magnetic toner contains 60 to 110 parts by weight of magnetic powder having an average particle diameter of 0.1 to 0.5 [mu] m per 100 parts by weight of the resin component. 4. The image forming method according to claim 1, wherein the magnetic toner has a residual magnetization ρ _{r of 1} to 5 emu / g. 5. Magnetic toner, the saturation magnetization ρ _s is 20~40emu /
The image forming method according to claim 1, wherein g is g. 6. The magnetic toner has a true density of 1.45 to 1.70 g / cm.
³ The image forming method according to any one of claims 1 to 5 is. 7. The image forming method according to any one of claims 1 to 6, wherein the magnetic toner comprises 0.1 to 5 parts by weight of silica fine powder added per 100 parts by weight of the magnetic toner. 8. 8. The image forming method according to claim 1, wherein a thickness of the magnetic toner layer on the toner carrier is formed to be smaller than a gap between the photoconductor and the toner carrier.