JPS6128960A - Image forming method - Google Patents

Abstract

PURPOSE:To improve cleaning property by forming a toner of shapeless particle powder and a carrier of shapeless particle powder formed by dispersing pulverous magnetic material powder into a resin and having a specific average grain size, incorporating a fluidity improving agent into the toner and forming the toner so has to have respectively specific values or above of static bulk density and packed bulk density. CONSTITUTION:This two-component developer is the developer having the shapeless toner and the shapeless carrier constituted by dispersing and incorporating pulverous magnetic material powder into the binder resin and having 10-50mum average grain size, having the fluidity improving agent and having >=0.60mg/ml static bulk density and >=0.80mg/ml packed bulk density. The fluidity improving agent is incorporated into the developer at 0.02-0.8wt% by the weight of the developer. Pulverous hydrophobic powder, pulverous amino-modified silica powder obtd. by treating the pulverous silica powder by an amino group-contg. compd., titanium oxide and alumina are used for said agent. Thermoplastic resins such as styrene, parachlorostyrene and alpha-methylstyrene are used for the binder resin of the toner. Since the toner is formed of the particle powder having no specific shapes, the thorough cleaning of a latent image carrying body is made possible.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention includes a step of developing a latent image formed in an electrophotographic method, an electrostatic recording method, an electrostatic printing method, etc. using a two-component developer. The present invention relates to an image forming method.

[Prior art]

Currently, in order to form a visible image from image information, methods using electrostatic latent images or magnetic latent images, such as electrophotography, are widely used. For example, according to an example of electrophotography, an electrostatic image formed on an electrostatic image support made of a photoconductive photoreceptor through a charging process and a non-lighting process is processed using a developer made of electrodetectable colored particles called a toner. The toner image is usually transferred to a transfer material and fixed to form a visible image.

The developer VCf'i used for developing such an electrostatic latent image or magnetic latent image is a so-called two-component developer consisting of a mixture of toner and carrier, and a magnetic toner entirely containing a magnetic substance.・There are so-called one-component developers that are used alone without being mixed with a carrier, but in systems using two-component developers, the toner is triboelectrified by mechanically stirring the toner and carrier. Because I urge you to
By selecting carrier characteristics, stirring conditions, etc.
It is possible to control the charge polarity and charge amount of the toner to a considerable extent, and in this respect, it is also superior to one-component developers.

Development methods using such a two-component developer include a magnetic brush method and a cascade method, among which the magnetic brush method is preferably used. What is this magnetic brush method?
Generally, a developer layer with spikes that stands up like a ridge is formed on a developer transport carrier by magnetic force, and this developer layer is rubbed against the surface of a latent image carrier to form a latent image with toner. This is a method in which particles are attached and development is performed.

Conventionally, the two-component developer used in such a magnetic brush method is generally composed of toner particles with an average particle size of about 10-odd μm and magnetic carrier particles with an average particle size of about 70 to 200 μm. In addition, since only toner is consumed in development using such a two-component developer,
There is a problem in that the toner concentration in the developer changes and the image quality deteriorates, so it is necessary to replenish the toner in the developer and control the toner concentration to be within a certain allowable range.

However, in the above-mentioned two-component developer containing a carrier with a larger diameter than the toner, the allowable range of toner density is small and sophisticated technology is required to control the toner concentration. The problem is that the device for controlling the concentration is expensive. Moreover, since the diameter of the carrier is large, the brush-like developer is inevitably rough, and therefore, when development is carried out by rubbing the spikes of the developer against the surface of the latent image carrier. In addition, the resulting images tend to have streaks, and moreover, the scraping tends to be excessive, resulting in uneven images with poor reproducibility, and in the end, it is difficult to obtain high-quality images. There are some difficult issues.

For this reason, a small-diameter carrier was developed in which fine magnetic particles were dispersed in a binder resin (No. 4? 1983-66134). however,
In a developer containing such a small-diameter carrier, as the carrier becomes smaller in diameter, the carrier particles tend to aggregate, resulting in a decrease in fluidity and insufficient frictional charging between the toner and the carrier. Moreover, as the diameter of the carrier becomes smaller, the magnetic force that can be imparted to the carrier becomes smaller, and therefore the developer layer tends to be insufficiently transported to cope with the magnetic force. In the development space, it is difficult for the toner particles to separate from the carrier particles, so even if the developer layer is rubbed against the latent image carrier, sufficient development cannot be achieved.
After all, simply using a small-diameter carrier kumquat results in low image density, a tendency to generate capricorns, and poor clarity.

In order to improve the fluidity of carrier particles, it is effective to make carrier particles spherical, but in order to obtain small-diameter, spherical carrier particles, a special manufacturing process is required, which ultimately increases the manufacturing cost of the developer. The problem is that the

The developed toner image is transferred and fixed to a transfer material such as paper to form a visible image, but the toner remaining on the latent image carrier without being transferred during this transfer process may be removed by a rubber blade, etc. However, in this cleaning process, the smaller the diameter of the toner, or the closer the toner is to a spherical shape, the more likely the cleaning is insufficient. However, there is a problem in that image stains occur due to toner remaining on the latent image carrier without being removed.

[Purpose of the invention]

The present invention has been made based on the above circumstances, and its purpose is to effectively clean toner remaining on a latent image carrier using a two-component developer containing a small-diameter carrier. An object of the present invention is to provide an image forming method capable of forming a clear image with high performance without generating capri.

Another object of the present invention is to provide an image forming method in which the manufacturing cost of a developer is low and images can be formed at low cost.

[Structure of the invention]

The above purpose is to form a developer layer of a two-component developer consisting of toner and carrier on a developer transport carrier, and to supply this developer layer to a development space that generates an oscillating electric field to carry a latent image. In an image forming method including a developing step of developing a latent image on a body, the toner is amorphous particle powder, and the carrier is composed of a binder resin containing magnetic fine powder dispersed therein and having an average particle diameter of 10. Amorphous particle powder of ~50 μm, #J two-component developer contains a fluidity improver, hardens at a quietness density of o, 6o+v/1nt or more, and has a bulk density of 0.80■/mt or more. This is achieved by an image forming method characterized by the following.

The present invention will be explained in detail below.

In the present invention, a developer transport carrier is disposed opposite to a latent image carrier carrying a latent image with a certain space in which development is performed, that is, a development space, and within this developer transport carrier, for example, developer is held. By the magnetic force of this magnet, a developer layer consisting of ears of a specific two-component developer, the details of which will be described later, is made to stand up like a brush on the surface of the developer transport carrier. The developer is developed in a state where it is not in contact with the latent image carrier, that is, in a state where the height of the developer spike is smaller than the shortest distance between the latent image carrier and the developer transport carrier in the development space. On the other hand, an oscillating electric field is applied to this developing space, and the oscillating electric field causes the particles forming the ears of developer to be vibrated and dispersed to cause reciprocating movement between the latent image carrier and the developer transport carrier. This causes the toner particles to adhere to the latent image ζ carried on the latent image carrier, and development is performed to form a toner image.

Next, the toner image is transferred to a transfer material such as paper, and the transferred image is fixed in a fixing device by, for example, a contact heat fixing method using a heating roller, thereby forming a visible image. On the other hand, after the transfer, the developer remaining on the latent image carrier is removed using, for example, a rubber blade, and used for the next image formation.

Next, the two-component developer used in the method of the present invention will be explained.

The two-component developer used in the method of the present invention comprises an amorphous toner and an amorphous carrier having an average particle size of io to 50 μIn, which is composed of a binder resin or resin containing magnetic fine powder dispersed therein. The developer further contains a fluidity improver and has a quietness density of 0.60 q/- or more and a solidified bulk density of 0.80"?/- or more.

The quietness density and hardened bulk density of the developer can be determined, for example, as follows. In other words, the powder compressibility tester ``
Using a "Tap Denser" (manufactured by Seishin Enterprise Co., Ltd.), loosely fill a container with a diameter of 28 mm and a volume of 100 g through a 100 mesh sieve from above, measure the weight M~, and calculate the weight Mm9. The quietness density is defined as the value obtained by dividing the volume by the volume 100-, that is, τj-■/mt. Next, cover the container with a lid of the same diameter, and measure the volume Nmj+ of the developer when tapped 600 times with a falling height of 5 using a tapping device. The value divided by N-, that is, 3. / is the solidified bulk density.

The fluidity improver may be contained in the developer, and its containing form is not particularly limited, but specifically, the fluidity improver may be dispersed and contained in one particle of toner and/or carrier. Seshimen form.

Examples include a form in which a fluidity improver is added to and mixed with toner and/or carrier particles and the fluidity improver is attached to the particle surface.

The content ratio of this fluidity improver is such that the quietness density and hardened bulk density of the final developer are within the ranges mentioned above, and specifically, the content ratio is determined based on the total weight of the developer. 0.02-0.8% by weight, preferably 0.06-0.
It is assumed to be 5% by weight. A specific example of such a fluidity improver is l''4-972J.

Hydrophobic silica fine powder such as "Bon-805", [lMoichi 812J (manufactured by Nippon Aerosil Co., Ltd.), etc., and amino groups on the surface obtained by treating fine silica powder with an amino group-containing compound such as aminosilane. It is possible to use amino-modified silica fine powder, titanium oxide, alumina, etc. with

The developer used in the present invention has a quietness density of 0.6
If the density is less than 0 .mu./mt or the solidified bulk density is less than 0.80 .mu./mt, the fluidity of the developer becomes insufficient and good development cannot be achieved.

The toner constituting the developer used in the present invention is basically an amorphous particle powder in which a colorant and other toner components are dispersed in a binder resin, or the fluidity improver is further added to the fluidity improver. The fluidity improver may be dispersed and contained in the binder resin, or alternatively, the fluidity improver may be added to the toner powder and mixed, and the fluidity improver may be attached to the surface of the toner particles. good.

Various thermoplastic resins are used as the binder resin of the toner. Specific examples thereof include styrenes such as EVA, styrene, parachlorostyrene, and α-methylstyrene; methyl acrylate, ethyl acrylate, acrylic [n-propyl, lauryl acrylate, diacrylic acid]
-α-methylene aliphatic monocarbon esters such as ethylhexyl, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, lauryl methacrylate, and 2-ethylhexyl methacrylate; vinyl nitriles such as acrylonitrile and methacrylonitrile; Vinyl pyridines such as 2-vinylpyridine and 4-vinylpyridine; Vinyl ethers such as vinyl methyl ether and vinyl imbutyl ether; Vinyl ketones such as vinyl methyl ketone, vinyl ethyl ketone, and methyl isopropenyl ketone; ethylene, propylene, isoprene, Polymers made from monomers such as unsaturated hydrocarbons such as bukudiene, their halides, and halogenated unsaturated hydrocarbons such as chlorobrene, or copolymers obtained by combining two or more of these monomers. and mixtures thereof, or non-vinyl condensation resins such as rosin-modified phenol-formalin resins, oil-modified epoxy resins, polyester resins, polyurethane resins, polyimide resins, cellulose resins, polyether resins, or combinations of these and the vinyl resins. Mixtures may be mentioned. Examples of colorants include carbon black, nigrosine dye, aniline blue, calco oil blue, chrome yellow, and ultramarine.

Mention may be made of blue, methylene blue, rose bengal, phthalocyanine blue, or mixtures thereof. These colorants must be contained in a sufficient proportion to form a visible image of sufficient density, and are usually about 3 to 25% by weight, preferably 8 to 15% by weight, based on the toner. The percentage of Toner components other than colorants include charge control agents such as nigrosine dyes and metal-containing bisazo compounds, and mold release agents such as polypropylene, polyethylene, fatty acid amide compounds, and 11 fatty acid ester compounds. Further, fine magnetic powder may be contained if necessary.

Such a toner can be obtained by a conventionally known toner manufacturing method, and has an average particle size of 8 to 25 μm, particularly 10 to 1 μm.
A 6 μm toner is preferred.

The carrier constituting the developer used in the present invention is basically amorphous particle powder with an average particle size of 10 to 50 μm, which is made by dispersing fine magnetic powder and other carrier components in a binder resin. Alternatively, the fluidity improver may be dispersed and contained in the binder resin, or alternatively, the fluidity improver may be added to and mixed with the carrier powder and stirred. A cleaning agent may be added to the first half of the carrier.

The average particle size of the carrier is, for example,
It can be measured using an aperture tube with a diameter of 100 μm using J (manufactured by Coalcoo Electric Co., Ltd., Japan).

Examples of the carrier binder resin include styrene,
Styrenes such as parachlorostyrene and α-methylstyrene; methyl acrylate, ethyl acrylate, acrylic [n-propyl, lauryl acrylate, acrylic acid 2-
α-methylene aliphatic monocarboxylic acid esters such as ethylhexyl, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, lauryl methacrylate 1-2-ethylhexyl methacrylate; acrylonitrile;
Vinyl nitriles such as methacrylonitrile; vinyl pyridine groups such as 2-vinylpyridine and 4-vinylpyridine; vinyl ethers such as vinyl methyl needle and vinyl isobutyl ether; vinyl methyl ketone and vinyl ethyl ketone.

Vinyl ketones such as methyl isopropenyl ketone; unsaturated hydrocarbons such as ethylene, propylene, isoprene, pucdiene and their halides; polymers of monomers such as halogenated unsaturated hydrocarbons such as chlorobrene; Copolymers obtained by combining two or more types of polymers, mixtures thereof, or, for example, rosin-modified phenol-formalin resins, oil-modified epoxy resins, polyester resins, polyurethane resins, polyimide resins, cellulose resins, polyether resins, etc. Examples include non-vinyl condensation resins with and mixtures of these and the vinyl resins.

The magnetic fine powder used for the carrier is a material that is strongly magnetized in the direction of a magnetic field, such as ferrite,
Metals that exhibit ferromagnetism, such as magnetite, iron, cobalt, and nickel, or alloys or compounds containing these metals, and metals that do not contain ferromagnetic elements, but can become ferromagnetic through appropriate heat treatment. Alloys such as manganese-copper aluminum or manganese-copper
Examples include alloys of a type called Heusler alloys such as tin, and fine powders such as chromium dioxide.

Such magnetic fine powder has an average particle size of 0.05 to 3 μm.
The content of the magnetic fine powder is preferably 40 to 90% by weight, preferably 55 to 80% by weight, based on the weight of the carrier.

The carrier used in the present invention has a resistivity of 1013Ω・
- or more is preferable. If this resistivity is low, charges are likely to be injected into the carrier particles by the bias voltage applied to the developer transport carrier.This may cause the carrier to easily adhere to the latent image carrier, or the breakdown of the bias voltage may occur. This may lead to adverse effects such as making it more likely to occur.

A conventional method can be used to manufacture the carrier used in the present invention, for example, a binder resin, a magnetic fine powder, a male blade 1 agent added as necessary, or a fluidity improver. Preliminarily mixed and dispersed using a ball mill etc. 2, then kneaded using a heating roll, cooled and pulverized, and then classified as necessary to obtain a carrier with a desired particle size. Then, an amorphous carrier having an average particle size of 10 to 50 μm is produced.

The average particle diameter of the carrier used in the present invention is 10 to 50 μm, preferably 15 to 40 μm, and the particle diameters are preferably uniform).

Furthermore, if the magnetic fine powder is exposed in a bare state on the surface of the carrier particles, the triboelectric charging properties of the carrier particles may be adversely affected by the triboelectric charging properties of the magnetic fine powder. It is advisable to coat the surface of the magnetic fine powder with a resin or higher fatty acid before incorporating it into the binder resin. Examples of higher fatty acids that can be used for this purpose include stearic acid, palmitic acid, and olein & lx. Fine magnetic powder is immersed in a solution of these higher fatty acids dissolved in an organic solvent such as trichlorethylene or dichromitane. Coating can be easily achieved by processing.

Further, the carrier used in the present invention has a glass transition temperature K (
Tg) is preferably at least 60°C or higher,
If the glass transition temperature is low, the carrier becomes sticky when heat is generated due to friction between the carriers or friction between the carrier and the wall of the developing device, resulting in poor fluidity.

The carrier used in the method of the present invention is preferably one that imparts an electric charge of 5 to 40 microcoulombs/11 in absolute value to the toner used together under normal usage conditions. The mixing ratio of carrier and toner in the component-based developer is not particularly limited, but it is preferable that the mixing ratio C()toner weight÷carrier weight) is within the range expressed by the following formula.

ρT2 Toner density ρ0: Carrier 'a degree Further, tζ is preferably within the range expressed by the following formula.

The two-component developer used in the present invention has been described above. Next, a specific developing process for developing, for example, an electrostatic image using such a developer will be described.

The developer transport carrier for supplying the developer to the development space is
A device similar to the conventional one to which a bias voltage can be applied can be used, especially one having a structure in which a rotating magnet having a plurality of magnetic poles is provided inside a sleeve on which a developer layer is supported on the surface. can be preferably used. In such a developer transport carrier, the rotation of the rotating magnet causes the developer layer supported on the surface of the sleeve to move in an undulating manner, so that new developer is supplied one after another. Even if there is some degree of non-uniformity in the layer thickness of the developer layer on the sleeve surface, the above-mentioned wave-like undulations sufficiently cover the effect so that it does not become a problem in practice. It is preferable that the transport speed of the developer due to the rotation of the rotating magnet or the rotation of the sleeve is almost the same as or faster than the moving speed of the electrostatic image carrier. Also,
It is preferable that the rotation of the rotating magnet body and the rotation of the sleeve be carried in the same direction. Image reproducibility is better in the same direction than in the opposite direction. However, it is not limited to these.

Further, it is preferable that the developer layer supported on the developer transport carrier has a uniform thickness; for example, the developer adhering to the developer transport carrier is sufficiently scraped off with a blade that regulates the thickness. A uniform layer is preferred. The gap between the developer transport carrier and the electrostatic image carrier is several dozen,
-2000 μm is preferable; if the gap between the developer transport carrier and the electrostatic image carrier becomes too narrow than several μm, it becomes difficult to form magnetic brush ears that uniformly develop in the developing space; It becomes impossible to supply a sufficient amount of toner particles to the developing space, and as a result, it becomes difficult to perform stable development f#.
When μmk becomes large and super heavy, the counter electrode effect decreases, making it impossible to obtain sufficient image density, and the edge effect, in which more toner adheres to the contours than the center of the electrostatic charge image, increases. .

In addition, it is particularly important to set the gap and the thickness of the developer so that the ears of the magnetic brush do not come into contact with the surface of the electrostatic image carrier without applying an oscillating electric field, and are as close as possible to the surface of the electrostatic image carrier. preferable. This is because scratches and fog caused by the rubbing of the magnetic brush on the toner image are prevented.

Preferably, the oscillating electric field is created by applying an oscillating bias voltage to the sleeve of the developer transport carrier. Further, as the bias voltage, it is preferable to use a voltage that is a combination of a DC voltage that prevents toner particles from adhering to non-image areas and an AC voltage that makes it easier for the toner particles to separate from the carrier particles. However, the present invention is not limited to these methods.

An example of a specific apparatus that can be used to perform the developing step in the method of the present invention is shown in FIG. In FIG. 1, reference numeral 1 denotes a drum-shaped electrostatic image carrier made of, for example, a selenium-based photoreceptor or an organic photoconductive photoreceptor. An electrostatic charge image is formed on the surface. 2 is a sleeve made of a non-magnetic material such as aluminum; 3 is a magnet provided inside the sleeve 2 and having a plurality of N, 8 magnetic poles along the circumference; the sleeve 2 and the magnet 3 form a developer transport carrier; is configured. The sleeve 2 and the magnet body 3 are relatively rotatable, and in the illustrated example, the sleeve 2 is rotated in the direction of the arrow, and the magnet body 3 is rotated in the direction opposite to the sleeve. The magnetic poles are normally magnetized to a magnetic flux density of 500 to 1,500 Gauss, and the magnetic force forms a layer of developer material, ie, a magnetic brush, consisting of brush-like spikes on the surface of the sleeve 2. 4 is the height of the magnetic brush,
A regulating blade 5 made of a magnetic or non-magnetic material regulates the amount, and a cleaning blade 5 removes the magnetic brush that has passed through the developing space A from above the sleeve 2. sleeve 2
Since the surface of 7 comes into contact with the developer reservoir in the developer reservoir 6, the developer reservoir is supplied thereby.
is a stirring screw that stirs the developer pool in the developer reservoir 6 to make the components uniform. Since toner particles in the developer reservoir 6 are consumed when development is performed, toner particles T in the toner hopper 8 are replenished as appropriate. Reference numeral 9 denotes a supply roller having a concave portion on its surface for dropping the toner particles T into the developer reservoir 6. A bias power supply 10 applies a bias voltage to the sleeve 2 via a protective resistor 11. A bias voltage having an alternating current component that oscillates by the bias power supply 10 is applied between the base 1a of the electrostatic image carrier 1 and the sleeve 2, which are grounded. This bias voltage is 1
For example, a superimposed voltage of a DC voltage and an AC voltage is used; the DC component prevents fogging, and the AC component vibrates the magnetic brush to improve the developing effect. For this DC voltage component, a voltage of, for example, 50 to 600 V, which is approximately equal to or higher than the non-current potential, is usually used, and for the AC voltage component, the frequency is 0 OHZ to 10 KHz, preferably l -
A voltage of 1 oOV to s KV at 5 KHz is used. Note that when the toner particles contain a magnetic material, the DC voltage component may be lower than the non-current potential. If the frequency of the AC voltage component is too low, the effect of vibration will be reduced, and if it is too high, the developer will not be able to follow the vibrations of the electric field, resulting in a decrease in image density, making it impossible to obtain clear, high-quality images. A trend emerges. Also, the voltage of the AC voltage component is
Although it is related to the frequency, the higher the frequency, the more the magnetic brush will vibrate, which will increase the effect accordingly, but if it is too high, fogging will easily occur, and dielectric breakdown such as that caused by lightning strikes will also occur, which is undesirable.

In the above-described apparatus, if the gap between the sleeve 2 and the electrostatic image carrier J is set to be in the range of several thousand to 2000 μm, the electrostatic image on the electrostatic image carrier 1 is developed. Since the magnetic flux density on the surface of the sleeve 2 changes as the sleeve 2 rotates, the magnetic brush formed on the surface of the sleeve 2 moves on the sleeve 2 while vibrating, thereby causing the electrostatic image carrier to The electrostatic charge image carrier 1 stably and smoothly passes through the gap between the electrostatic charge image carrier 1 and the surface of the electrostatic charge image carrier 1, thereby imparting a uniform developing effect to the surface of the electrostatic image carrier 1, thereby making it possible to stably develop a high image density.

Although an example of the apparatus that can be used in the method of the present invention has been described above with reference to FIG. 1, the present invention is not limited thereto. For example, several electrode wires may be stretched around the developing area between the developer transport carrier and the electrostatic image carrier, and an oscillating voltage may be applied to them to vibrate the magnetic brush and produce a developing effect. can be improved.

In that case as well, a direct current bias voltage may be applied to the developer transport carrier, or oscillating voltages of different frequencies may be applied. Furthermore, the method of the present invention can be similarly applied to reversal development and the like. In that case, the DC voltage component is set to a voltage approximately equal to the receiving potential in the non-image background portion of the electrostatic image carrier. Furthermore, the method of the present invention can be applied even when the image to be developed is a magnetic latent image.

[Function and effect of the invention]

The present invention is a method as described above, and since the toner constituting the two-component developer has an amorphous shape, that is, an unspecified shape, and most of the particles are powder particles with a so-called distorted shape, the cleaning step of the latent image carrier is not necessary. When cleaning the toner remaining on the latent image carrier, for example, the scraping force of a rubber blade is sufficiently applied, so the latent image carrier can be sufficiently cleaned. The surface of the body can be subjected to the next repeated image formation in a clean state without stains, and therefore, the occurrence of image stains due to residual toner can be prevented. In addition, because the carrier has a small diameter, it tends to adhere to the latent image carrier during development, but since the carrier is amorphous, in the cleaning process of the latent image carrier, it is difficult to clean it with a rubber blade or the like. The carrier can be easily removed, and image stains caused by residual carrier can be prevented.

The two-component developer contains a fluidity improver and has a quietness density of 0.6011V7! The solidified bulk density is 0.8
0'F/m/! Therefore, as will be understood from the description of the examples below, the fluidity of the developer is sufficient, and therefore the toner and carrier are charged with a sufficient amount of charge due to friction, and as a result, the toner The adhesion of the particles to the latent image charge is improved. Furthermore, in the development process, since an oscillating electric field is applied to the developing space, the toner particles and carrier particles are vibrated while receiving forces in opposite directions due to the oscillating electric field. Since the separated toner particles are made to behave as unitary particles by the oscillating electric field, the toner particles can be selectively attached to the latent image charge with extremely high reliability.

As a result, it is possible to form a clear image with high density without causing stains on the image due to poor cleaning and without fogging.

Since the carrier particles have an average particle diameter of 10 to 50 μm, which is approximately the same size as the toner particles,
Compared to the same amount of large-diameter carrier, its surface area is significantly increased, and the triboelectric charging ability of the carrier is correspondingly large.As a result, the allowable range of toner concentration is much wider and toner replenishment is possible. becomes easier.

Since the toner and carrier used in the present invention are both amorphous particle powders, the toner and carrier are prepared by a simple manufacturing method of melting and kneading the toner and carrier components, respectively, cooling, pulverizing, and then classifying. Therefore, there is no need to add a special process, and therefore, the manufacturing cost of the developer can be reduced, and as a result, images can be formed at low cost.

[Embodiments of the invention]

Specific examples of the present invention will be described below, but the present invention is not limited to these examples. Furthermore, “department”
represents "parts by weight". Further, [MwJ represents the weight average molecular weight, rMnJ represents the number average molecular weight, and rTapl represents the softening point.

Example 1 (Manufacture of toner) Polymer (weight ratio 75:15:10, /Mn=10.), (z
9) Tsp=128°C) 100 parts carbon black "Mogul L" (manufactured by Cabot Corporation) 10 parts polypropylene [Viscol 660PJ (manufactured by Sanyo Chemical Co., Ltd.)
3 parts charge control agent [Nigrosine 5OJ (manufactured by Orient Chemical Co., Ltd.) 2 parts or more of the substance are thoroughly premixed using a ball mill, then melt-kneaded using a twin-screw extruder, coarsely ground after cooling, and then finely ground using a jet mill. and the average particle size is 10.2μ
A fine powder of m was obtained. Next, a zigzag classifier was used to obtain irregularly shaped toner powder with an average particle size of 10.9 μm.

This toner powder contains 1'l'L-80 hydrophobic silica fine powder.
5J (Nippon Aerosil Co., Ltd. 5R) was added at a ratio of 0.8% by weight to 11%, and the mixture was thoroughly stirred using a mixer to obtain a toner having hydrophobic silica fine powder attached to the particle surface.

(Production of carrier) Styrene-butyl methacrylate (weight ratio 85:15%M7/IMn=6.3%Ts
p = 141°C) 30 parts magnetite [BL-100 Mountain (manufactured by Titanium Kogyo Co., Ltd.) 70 parts charge control agent [Bontron S-34J (manufactured by Orient Chemical Co., Ltd.) 2 parts or more of the substance was added in the same manner as in the production of the above toner. By processing according to the method, amorphous magnetic material-dispersed microcarriers having an average particle size of 21.3 μm were obtained.

When the resistivity of this microcarrier was measured, it was found to be 10
It was 14Ω·c#1 or more.

A two-component developer was prepared by mixing 30 parts of the toner obtained as described above and 70 parts of the microcarrier.

When the quietness density and hardened bulk density of this developer were measured using a tap capacitor under the conditions described above, the quietness density was 0.62 /mt, and the hardened bulk density was o, ssj/fn.
It was t.

Next, using this developer, the surface temperature of the heat roller of the heat roller fuser was set to 80℃ using an electrophotographic copying machine equipped with a developing mechanism similar to that shown in Fig. When we conducted a live-action test to form an image on the image, the resulting image had a density of 1.8
It was very clear. Further, when continuous copying was performed 30,000 times, a good image that remained stable from beginning to end could be obtained. Further, no staining of the image occurred.

In this example, the developing conditions are as follows. That is, the electrostatic image bearing member is an organic photoconductive photoreceptor (hereinafter simply referred to as rOPC photoreceptor) having a negatively charged two-layer structure, which uses an anthrone pigment as a carrier-generating substance and a carbazole derivative as a carrier-transporting substance. ), the circumferential speed of this OPC photoreceptor is] 5011114 + The highest potential of the electrostatic charge image formed on the electrostatic charge image carrier is -520V
, the outer diameter of the sleeve is 30mm, and the number of rotations of the sleeve is ]00
rpm, the magnetic flux density of the N and S magnetic poles of the magnet body is 500 Gauss, the rotation speed of the magnet body is 11000 rpm, the thickness of the developer layer in the development space is 0.2 Gauss, between the sleeve and the electrostatic image carrier. One gap is 500 μm, and the bias voltage applied to the sleeve has a DC voltage component of -150V and an AC voltage component of 2.5V.
The voltage was 400V at kHz.

Comparative Example 1 A two-component developer was prepared in the same manner as in Example 1 except that hydrophobic silica fine powder was not added.

The quietness density of this developer was 0.57 kg/go, and the solid bulk density was 0.77 cm/go.

When a photographic test was carried out using this developer in the same manner as in Example 1, the image density was as low as 0.89, and the image was rough due to fogging.

Example 2 A toner was obtained in the same manner as in Example 1. Next, hydrophobic silica fine powder [R-805J] was added to the microcarrier obtained in Example at a ratio of 0.3% by weight, and the mixture was sufficiently stirred with a mixer to form hydrophobic silica fine powder on the surface of each particle. Adhering microcarriers were obtained.

A two-component developer was prepared by mixing 30 parts of the toner obtained as described above and 70 parts of the microcarrier.

The quiet density of this developer was 0.65 .mu./mt, and the solid bulk density was 0.92 g/mt.

When an actual photographic test was conducted using this developer in the same manner as in Example 1, the density of the image obtained was as high as 1.22, and the image was clear with good gradation and no edge effect or fog. was gotten. Further, when continuous copying was performed 30,000 times, a good image that remained stable from beginning to end could be obtained. Further, no staining of the image occurred.

Example 3 In Example 1, the addition ratio of hydrophobic silica fine powder was changed to 0.
．． A toner was obtained in the same manner except that the amount was changed to 4% by weight.

Next, hydrophobic silica fine powder [R-8054] was added to the microcarrier obtained in Example 1 at a ratio of 0.2% by weight, and the mixture was sufficiently stirred with a mixer to form hydrophobic silica fine powder on the particle surface. Tsuzen 1 each square h1-1 Nanatoro 11 ma also fn
A two-component developer was prepared by mixing 30 parts of the toner obtained as described above with 70 parts of the microcarrier.

This developer had a quiet density of 0.62° C. and a hardened bulk density of 0.87 η/g.

When an actual photographic test was conducted using this developer in the same manner as in Example 1, the density of the image obtained was as high as 1.19, and the image was clear with good gradation and no edge effect or fog. was gotten. Further, when continuous copying was performed 30,000 times, a good image that remained stable from beginning to end could be obtained. Further, no staining of the image occurred.

Example 4 (Production of toner) Styrene-butyl methacrylate-methyl methacrylate copolymer (weight ratio 50:20:30.-false=11.2, Tsp=
132℃) 100 parts carbon black ÷30J (:*4k i?j+#)
l nm polypropylene [Viscol 660PJ (manufactured by Sanyo Chemical Co., Ltd.)
3-part charge control agent [Nigrosine EX
J (manufactured by Orient Chemical Co., Ltd.) Two or more parts of the substance were treated in the same manner as in the production of the toner of Example 1 to obtain an amorphous toner powder with an average particle size of 10.6 μm.

Hydrophobic silica fine powder R4-972J is added to this toner powder.
(manufactured by Nippon Aerosil Co., Ltd.) at a ratio of 0.4% by weight was added and sufficiently stirred with a mixer to obtain a toner having hydrophobic silica fine powder adhered to the particle surface.

(Production of carrier) 270 g of 1,4-butanediol and 150 g of terephthalic acid
and 231 g of benzene-1,2,4-)licarponic acid at a temperature of 200°C, and the chloroform insoluble matter was reduced to 1.
2 weight of polyester resin was obtained.

The above-mentioned polyester resin 40 parts I got it. When the resistivity of this microcarrier was measured, it was more than 10Ω.

A two-component developer was prepared by mixing 25 parts of the toner obtained as described above and 75 parts of the microcarrier.

When the quietness density and hardened bulk density of this developer were measured using a tap densityer under the conditions described above, the quietness density was 0.65 η/-1, and the hardened bulk density was 0.92 η/-.

When a photographic test was carried out using this developer in the same manner as in Example 1, the density of the image obtained was as high as 1.27, and the image was clear with no edge effect or fog. Furthermore, when continuous copying was performed 30,000 times, the density of the image did not decrease even after 30,000 copies, and a good image that remained stable and unchanged from beginning to end was able to be obtained. Further, no staining of the image occurred.

Comparative Example 2 A two-component developer was prepared in the same manner as in Example 4 except that hydrophobic silica fine powder was not added.

The quiet density of this developer was 0.59 .mu./-1, and the solid bulk density was 0.79"/.d.

When a photographic test was carried out using this developer in the same manner as in Example 1, the image density was as low as 1.01, and the image was rough due to fogging.

[Brief explanation of drawings]

FIG. 1 is an explanatory cross-sectional view schematically showing an example of a developing device that can be used to perform a developing step in carrying out the method of the present invention. 1... Electrostatic image carrier 2... Sleeve 3...
Magnet body 4... Regulation blade 5... Cleaning blade

Claims (1)

[Claims] 1) A developer layer of a two-component developer consisting of toner and carrier is formed on a developer transport carrier, and this developer layer is supplied to a development space that generates an oscillating electric field to form a developer layer on a latent image carrier. In an image forming method including a developing step of developing a latent image, the toner is amorphous particle powder, and the carrier is a binder resin containing magnetic fine powder dispersed therein and having an average particle size of 10 to 50 μm. Irregularly shaped particle powder,
The two-component developer contains a fluidity improver, has a quietness density of 0.60 mg/ml or more, and has a solidified bulk density of 0.80 mg.
/ml or more.