JPS6128958A - Image forming method - Google Patents

Abstract

PURPOSE:To improve the cleaning property of a toner by forming the toner of shapeless particle powder and a carrier of spherical particle powder which is formed by dispersing pulverous magnetic material powder in a resin and has a specific average grain size, incorporating a fluidity improving agent into the toner and forming the toner so as to have respectively specific values or above of static bulk density and packed bulk density. CONSTITUTION:This two-component type developer is the developer having the shapeless toner and the spherical carrier formed by dispersing the pulverous magnetic material powder into the binder resin and having 10-50mum average grain size, contg. 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. The formation of a sharp image at high density is thus made possible without generating the image stain arising from defective cleaning.

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 consisting of a photoconductive photoreceptor by a charging process and an exposure process is used as a developer consisting of electrodetectable colored particles called toner. The toner image is usually transferred and fixed onto a transfer material to obtain a visible image.

Developers used to develop such electrostatic latent images or magnetic latent images include so-called two-component developers in which toner and carrier are mixed, and magnetic toner and carriers containing magnetic materials. There are so-called one-component developers that are used alone without being mixed, but in systems that use two-component developers, the toner is triboelectrified by mechanically stirring the toner and carrier, so the carrier By selecting the characteristics of the toner, stirring conditions, etc., it is possible to control the polarity and amount of charge of the toner to a considerable extent.
In this respect, single-component developers are also superior.

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 in the form of brush-like spikes 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. Furthermore, since only the toner is consumed in development using such a two-component developer,
There is a problem 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 so that it is within a certain allowable range. .

However, in the above-mentioned two-component developer containing a carrier with a larger diameter than the toner, the tolerance range for toner concentration is small and sophisticated technology is required to control the toner concentration. The problem is that the equipment for controlling this is expensive. Moreover, since the carrier has a large diameter, the bristles of the developer raised up like a brush are unavoidably rough, and therefore, when developing is carried out by sliding the developer onto the surface of the latent image carrier. , the resulting images tend to have streaks called "sweep marks" and are also prone to excessive scraping, resulting in images that are grainy and have poor reproducibility. There are some problems that make it difficult to obtain.

For this reason, a small-diameter carrier was developed in which fine magnetic particles were dispersed in a binder resin (Japanese Patent Laid-Open No. 54-66134).

L, L, 18.3°, 4, ya. Yay, ah.
In the I developer, as the diameter of the carrier becomes smaller, the carrier particles tend to aggregate, resulting in decreased fluidity and insufficient frictional charging between the toner and the carrier). As a result, the magnetic force that can be imparted to the carrier is small, and therefore the developer layer tends to be insufficiently conveyed by the magnetic force.Furthermore, since the carrier has a small diameter, toner particles may be dispersed in the developing space. is difficult to separate from the carrier particles, so even if the spikes of the developer layer are rubbed against the latent image carrier, sufficient development cannot be achieved. 1. Image density is low and capri is likely to occur. It has the disadvantage of low clarity.

For this reason, it is considered effective to add a fluidity improver, such as fine silica powder, to the carrier in order to improve the fluidity of the carrier. In order to achieve this, it is necessary to add a considerable amount of a fluidity improver, and as a result, the fluidity improver becomes embedded in a large amount on the surface of the toner particles or carrier particles, thereby improving the triboelectric charging properties of the toner or carrier. Fluidity improvers such as fine silica powder are usually hard and may cause problems such as damage to the surface of the latent image carrier.

The developed toner image is transferred and fixed onto a transfer material such as paper to form a visible image.

Toner remaining on the latent image carrier without being transferred in this transfer process is removed by cleaning with a rubber blade, for example. Cleaning is likely to be insufficient, and therefore, in the next repeated image formation, there is a problem in that image stains occur due to toner remaining on the latent image carrier without being removed.

[Object of the Invention] The present invention has been made based on the above-mentioned circumstances, and its object is to remove toner remaining on a latent image carrier using a two-component developer containing a small-diameter carrier. It is an object of the present invention to provide an image forming method which can perform cleaning well and can form a clear image with high density without capri.

Another object of the present invention is to provide an image forming method in which toner manufacturing costs are 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 a binder resin containing magnetic fine powder dispersed therein and having an average particle size. Spherical particle powder of 10 to 50 μm, wherein the two-component developer contains a fluidity improver and has a quietness density of 0.60 wq/- or more and a solidified bulk density of 0.
This is achieved by an image forming method characterized in that the image forming temperature is 801 Iv/- or more.

The present invention will be explained in detail below.

In the present invention, a developer and agent transport carrier is disposed opposite to a latent image carrier carrying a latent image through a certain space in which development is performed, that is, a development space, and within this developer transport carrier, for example, a developer is By arranging holding magnets and using the magnetic force of the magnets, a specific two-component developer (details of which will be described later) is made to stand up like a brush on the surface of the developer transport carrier to form a flexible developer layer. The state in which this developer layer is not in contact with the latent image carrier, that is, the moderate height of the developer, is the shortest distance between the latent image carrier and the developer transport carrier in the development space. is supplied to the developing space in a small state, and on the other hand, an oscillating electric field is applied to this developing space, and the particles forming the spikes of developer are dispersed by vibration, thereby transporting the latent image carrier and the developer. The toner particles are caused to reciprocate with the carrier, thereby causing the toner particles to adhere to the latent image carried on the latent image carrier and developing 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 heating fixing method using a heating lawn, thereby forming a visible image. On the other hand, the developer remaining on the latent image carrier during the temporary transfer is removed using, for example, a rubber blade, and then 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 includes an amorphous toner and a spherical carrier with an average particle size of 10 to 50 μm, which is composed of a binder resin containing magnetic fine powder dispersed therein. Contains a fluidity improver and has a quietness density of 0.60 k/mA or more and a bulk density of 0.
．． There is also a developer of 801+9/m 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 "
Tapdenser (manufactured by Seishin Enterprise Co., Ltd.) is used to
A container of 8 m+ and a volume of 100- is loosely filled with developer through a 100 mesh sieve from above, and the weight at this time is M.
q is measured, and the value obtained by dividing the weight M2 by the volume 100 tnt, that is, Ti-/-, is taken as the quietness density. Next, the container is covered with a lid of the same diameter, and the tapping device is used to tap the container 600 times at a drop height of 5 gourds.The volume of developer is N.
d, and the previously measured weight M1q is expressed as this volume Nrn
Divided by l]7, the value J#ri/rnt is consolidated and taken as the bulk density.

The fluidity improver may be contained in the developer, and its containing form is not particularly limited. Specifically, the fluidity improver may be dispersed and contained in particles of toner and/or carrier. For example, a form in which a fluidity improver is added to and mixed with toner and/or carrier particle powder to adhere the fluidity improver to the particle surface, etc. can be mentioned.

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 weight factor, preferably 0.06-0.
He is said to be in charge of the 5th grade. Specific examples of such fluidity improvers include rR-972 ball "R-805J, rR
Hydrophobic silica fine powder such as -812J (manufactured by Nippon Aerosil Co., Ltd.), amine-modified silica fine powder having an amino group on its surface obtained by treating fine silica powder with an amino group-containing compound such as aminosilane. , titanium oxide, alumina, etc.

The developer used in the present invention has a quietness density of 0.6
If the density is less than 0.0 μm/g or the solidified bulk density is less than 0.80 μm, 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 amorphous particle powder in which a colorant and other toner components are dispersed and contained in a binder resin, or the toner further contains 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, n-propyl acrylate, lauryl acrylate, and diacrylic acid.
- α-Methylene aliphatic monocarboxylic acid esters such as ethylhexinone, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, lauryl methacrylate, 2-ethylhexyl methacrylate, etc.I/y: Vinyl nitrile such as acrylonitrile, methacrylic nitrile, etc. Class;
Vinyl pyridines such as 2-vinylpyridine and 4-vinylpyridine; Vinyl ethers such as vinyl methyl ether and vinyl isobutyl ether; Vinyl ketones such as vinyl methyl ketone, vinyl ethyl ketone, and methyl isopropenyl ketone Q: ethylene, fluoropylene, Unsaturated hydrocarbons such as isoprene and phtadiene and their
Polymers of monomers such as halogenated compounds and chloroprene and other unsaturated hydrocarbons, copolymers obtained by combining two or more of these monomers, and mixtures thereof, or, for example, 10 Non-vinyl condensation resins such as gin-modified phenol-formalin resin, oil-modified epoxy resin, polyester resin, polyurethane resin, polyimide resin, cellulose resin, and polyether resin, or mixtures of these and the above-mentioned vinyl resins can be mentioned. Coloring agents can include, for example, carbon black, nigrosine dye, aniline blue, calco oil blue, chrome yellow, ultramarine blue, methylene blue, rose bengal, phthalocyanine blue, or mixtures thereof. These colorants need to be contained in a sufficient proportion to form a visible image with 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, fatty acid ester compounds, etc. Depending on the situation, fine magnetic powder may be contained.

Such a toner can be obtained by a conventionally known toner manufacturing method, and has an average particle size of 8 to 25 μm1 π10 to 1
The carrier constituting the developer used in the present invention is basically composed of a binder resin containing magnetic fine powder and other carrier components dispersed therein, and has an average particle size of 10 to 10. It is a 50 μm spherical particle powder, or the fluidity improver 5 may be further dispersed and contained in the binder resin. Alternatively, the fluidity improver is warmly mixed with the carrier powder and stirred. In particular, the fluidity improver may be attached to the surface of the carrier particles.

The average particle size of the carrier can be measured, for example, by using a "Coulter Counter" (manufactured by Coulter Electric Co., USA).
It can be measured using a 00mm aperture tube. Here, the spherical particles do not necessarily have to be true spheres in the strict sense; for example, the ratio of the major axis a to the minor axis τ is 1.00≦
Refers to particles that are considered to be approximately spherical and are within the range of sound ≦1.2.

Examples of the carrier binder resin include styrene,
Styrenes such as parachlorostyrene and α-methylstyrene; methyl acrylate, ethyl acrylate, n-propyl acrylate, lauryl acrylate, acrylic acid 2-
α-methylene aliphatic monocarboxylic acid esters such as ethylhexyl, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, lauryl methacrylate, and 2-ethylhexyl methacrylate; acrylonitrile;
Vinyl nitriles such as methacrylonitrile; Vinyl pyridines such as 2-vinylpyridine and 4-vinylpyridine; Vinyl ethers such as vinyl methyl ether and vinyl isobutyl ether; Vinyl ketones such as vinyl methyl ketone, vinyl ethyl ketone, and methyl isopropenyl ketone. unsaturated hydrocarbons such as ethylene, propylene, imbrene, butadiene, and their halides;
Polymers of monomers such as halogenated unsaturated hydrocarbons such as chloroprene, copolymers obtained by combining two or more of these monomers, and mixtures thereof, or, for example, rosin-modified phenol-formalin resins, Non-vinyl condensation resins such as oil-modified epoxy resins, polyester resins, polyurethane resins, polyimide resins, cellulose resins, and polyether resins, or mixtures of these and the vinyl resins can be used.

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,
Ferromagnetic metals such as magnetite, iron, cobalt, and nickel, or alloys or compounds containing these metals; alloys that do not contain ferromagnetic elements but become ferromagnetic through appropriate heat treatment; For example, 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, and 55 to 80% by weight based on the weight of the carrier.

The carrier used in the present invention preferably has a resistivity of 10131°ΩΦ or more. When this resistivity is low, charges are likely to be injected into the carrier particles by the bias voltage applied to the developer transporting carrier, and therefore carriers tend to adhere to the cleaning image carrier, or the bias voltage is applied to the carrier particles. This results in negative effects such as breakdown being more likely to occur.

In an example of the method for manufacturing the carrier used in the present invention,
For example, binder resin, magnetic fine powder, other additives added as necessary, or a fluidity improver are premixed using a ball mill or the like to uniformly mix and disperse, and then heated in a four-wheeler. After that,
By cooling and pulverizing, and then spraying into hot air using, for example, a known spray dryer method, the surface of the carrier particles is instantaneously melted and the carrier particles are sphericalized by surface tension. Classify as necessary to obtain a carrier with an average particle size of 10 to 50.
A μm spherical carrier is manufactured.

The carrier used in the present invention has an average particle size of 10 to 50 μm, preferably 15 to 40 μm, and the particle sizes are preferably uniform.

Other manufacturing methods for the carrier used in the present invention include a method in which monomer components of the binder resin are polymerized to form a polymer in the presence of magnetic fine powder or a fluidity improver. This method is preferred because it is industrially stable and easy to manufacture. Specifically, for example, the following methods can be used.

(a) A method in which ordinary bulk polymerization is carried out without a solvent at a temperature of 60 to 120° C. under a nitrogen stream.

(b) In water at a temperature of 60 to 120°C under a nitrogen stream, for example, gelatin, starch, polyvinyl alcohol, barium sulfate, calcium sulfate, barium carbonate, magnesium carbonate, etc.
A method in which suspension polymerization is carried out by conventional methods in the presence of a dispersant such as calcium phosphate, talc, clay, silicic acid, or metal oxide powder.

f → Emulsion polymerization by a conventional method at a temperature of 40 to 90°C under a stream of nitrogen using an aqueous polymerization initiator in the presence of a surfactant such as sodium dodecylbenzenesulfonate, an alkyl sulfate anion emulsifier, or sodium dodecylsulfonate. How to do it.

B) A method in which solution polymerization is carried out by a conventional method under a nitrogen stream at a temperature of 60 to 120° C. in a diluted state with a suitable solvent (eg, evabenzene, xylene, ethanol, methyl ethyl ketone).

When producing a carrier using such a method, it is preferable that the fine magnetic powder used has a pH of 6 or more. The most preferable production method is suspension polymerization as described above←
) method.

In addition, 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 desirable to coat the surface of the fine magnetic 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 oleic acid. Coating can be easily carried out by dipping the fine powder.

Further, the carrier used in the present invention has its glass transition temperature (T
g) is preferably at least 60°C or higher, and if the glass transition temperature is low, the carrier will become sticky when heat is generated due to J9 friction between the carriers or friction between the carrier and the wall of the developing device. ), liquidity deteriorates.

The carrier used in the method of the present invention is preferably one that imparts an electric charge of 5 to 40 microcoulombs/2 in absolute value to the toner used together under normal usage conditions.

The mixing ratio of carrier and toner in the two-component developer used in the method of the present invention is not particularly limited, but the mixing ratio C()ner weight ÷ carrier weight) is within the range expressed by the following formula. Toto is preferred.

0, I
More preferably, it is within the range expressed by the following formula.

0.2X'! l≦C≦0.7×! L ρCρC The two-component developer used in the present invention has been described above, and next, a specific developing process for developing, for example, an electrostatic charge 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 that can apply a bias voltage can be used. In particular, a device with a structure in which a rotating magnet body having a plurality of magnetic poles is provided inside a sleeve on which a developer layer is supported is used. It 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 thickness of the developer layer on the surface of the sleeve, the above-mentioned wave-like undulations sufficiently cover up the effect so that it does not become a problem in practice. It is preferable that the developer conveying speed 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,
The conveyance direction due to the rotation of the rotating magnet and the rotation of the sleeve is
The same direction is preferred. 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 tens of inches.
-2000 .mu.m is preferable; if the gap between the developer transport carrier and the electrostatic image carrier is too narrow by several micrometers, it may be difficult to form magnetic brush ears that uniformly develop in the developing space. Moreover, it becomes impossible to supply a sufficient amount of toner particles to the developing space, and it becomes difficult to perform stable development.On the other hand, when the gap greatly exceeds 2000 μm, The electrode effect is reduced, making it impossible to obtain a sufficient image density, and the edge effect, in which more toner adheres to the contours of the electrostatic image than to the center, also increases.

In addition, it is especially important to set the gap and the thickness of the developer layer 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 the toner image is prevented from having scratches or fogging caused by the rubbing of the magnetic brush.

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 obtained by superimposing a DC voltage, which prevents toner particles from adhering to non-image areas, with an AC voltage, which 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 such as a selenium-based photoconductor or an organic photoconductive photoconductor, which rotates in the direction of the arrow and whose surface is exposed by a charging exposure device (not shown). An electrostatic charge image is formed. 2 is a sleeve made of a non-magnetic material such as aluminum; 3 is a magnet body provided inside the sleeve 2 and having a plurality of N and S magnetic poles along the circumference; the sleeve 2 and the magnet body 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 opposite direction to the direction of the sleeve. The N and 8 magnetic poles of the magnet body 3 are normally magnetized to a magnetic flux density of 500 to 1500 Gauss, and the magnetic force causes a layer of developer material to stand up in the form of a brush on the optical surface of the sleeve 2, that is, a magnetic layer. Form a brush. 4 is a regulating blade made of magnetic or non-magnetic material that regulates the height and amount of the magnetic brush;
A cleaning blade 5 removes the magnetic brush that has passed through the developing space A from above the sleeve 2. sleeve 20
Since the surface comes into contact with the developer at the top of the developer reservoir, this is how the developer is supplied.Step 7: Stir the developer at the top of the developer reservoir to make the components uniform. It is a stirring screw. Since toner particles are removed from the developer in the developer reservoir 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. IO is a bias power supply that applies a bias voltage to the sleeve 2 via the protective resistor 11. A bias voltage having an oscillating alternating current component is applied by the bias power supply 10 between the grounded base 1a of the electrostatic image carrier 1 and the sleeve 2. This bias voltage is, for example, a combination of a DC voltage and an AC voltage.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-moving part potential, is normally used, and for the AC voltage component, the frequency is 100 Hz to 10) G (z, 8 dimensions 1- (
A voltage of M 1 to 5IG (z 〒1noV to 5'' is used. Note that if the toner particles contain a magnetic material, the DC voltage component may be lower than the non-moving part potential).AC voltage If the frequency of the component is too low, the effect of imparting vibration will be small, and if it is too high, the developer will be unable to follow the vibration of the electric field, resulting in a decrease in image density and the inability to obtain a clear, high-quality image. Also, although the voltage of the AC voltage component is also related to the frequency, the higher the voltage, the more the magnetic brush will vibrate and the more effective it will be, but if it is too high, it will easily cause fogging and will cause lightning strikes. This is not preferable because such dielectric breakdown is likely to occur.

In the apparatus described above, the gap between the sleeve 2 and the electrostatic image carrier 1 is set to be in the range of several tens of μm to 2000 μm, and the development of the electrostatic image on the electrostatic image carrier 1 is carried out. When this is done, the magnetic flux density on the surface of the sleeve 20 changes as the sleeve 2 rotates, so the magnetic brush moves on the sleeve 2 while vibrating, thereby creating an electrostatic charge image. It stably and smoothly passes through the gap between the image carrier 1 and the electrostatic image carrier 1, giving a uniform developing effect to the surface of the electrostatic image carrier 1, thereby enabling stable development with high image density. do.

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, even if several electrode wires are stretched around the development area between the developer transport carrier and the 1jp charge image carrier and a vibrating voltage is applied to them, the magnetic brush is vibrated to 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 the majority of the particles are powder particles with a distorted shape, it is difficult to clean the latent image carrier in the cleaning process of the latent image carrier. In the case of cleaning the toner remaining on the latent image carrier, for example, scraping with a rubber blade or the like is sufficiently effective, so that the latent image carrier can be sufficiently cleaned. The carrier can be subjected to the next repeated image formation with its surface clean and free of stains, thus preventing the occurrence of image stains due to residual toner. Moreover, since the carrier is a spherical particle powder, the drop in fluidity is small despite the small diameter of the carrier particles. Therefore, the required fluidity can be obtained with a small amount of fluidity improver, and two-component The developer has a quietness density of 0.60 mf/lnt or more, a solidified bulk density of 0.80 W/mg or more, and is understood from Ez7'c "・Later 46 Example 0 Description" to 1'I. As such, the fluidity of the developer is sufficient, and therefore, although the toner itself is amorphous and has poor fluidity, this drawback does not appear and the toner and carrier have a sufficient amount of charge due to friction. This results in better adhesion of the toner particles to the latent image charge. Although the magnetizing force of the carrier decreases as the diameter of the carrier decreases, the spherical shape of the carrier provides good lubricity and transferability of the carrier particles.
A layer is formed that allows the developer layer standing up in the form of spikes to be conveyed well, and therefore the developer can be stably supplied to the development space. Furthermore, in the developing process, in order to apply an oscillating electric field to the developing space, the oscillating electric field causes j5
) The toner particles and carrier particles may be vibrated while receiving forces in opposite directions.Since the carrier is small in diameter but spherical, the toner particles are held in a small area relative to the carrier particles. Therefore, when vibrated, the toner particles may be easily separated from the carrier particles, and the separated toner particles may behave as unit particles due to the oscillating electric field. The toner particles selectively adhere to the latent image charge with extremely high reliability.As a result, when a large amount of fluidity improver is added, the triboelectric charging performance decreases and the surface of the latent image carrier deteriorates. A clear image with high density can be formed without causing damage, without image staining due to poor cleaning, and without generating capri.

Furthermore, since the carrier is spherical, toner substances are less likely to adhere to the surface of the carrier, so that contamination of the carrier does not occur, and desired characteristics of the carrier can be stably obtained for a long period of time.

Since the carrier particles have an average particle size of 10 to 50 μm, which is approximately the same size as the toner particles, their surface area is significantly increased compared to the same amount of large-diameter carrier. As a result, the triboelectric charging ability of the carrier becomes relatively large, and as a result, the allowable range of toner concentration is significantly wide, and toner replenishment becomes easy.

Since the toner used in the present invention is an amorphous particle powder, the toner components are melted and kneaded and then cooled.
r--Mumune 1L+-A is also closed, and toner can be obtained by the Kariho method.Therefore, there is no need to add a special process, and it is possible to reduce the manufacturing cost of toner, and as a result, the image 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". In addition, "bar" is the weight average molecular weight,
"Seed" represents the number average molecular weight, and l'rspJ represents the softening point.

Example 1 (Production of toner) Styrene-butyl acrylate-methyl methacrylate copolymer (weight ratio 75:15:100,000 Miv/Mn==
10.1, TSp=128℃)
100 parts carbon black "Mogul L" (manufactured by Cabot) 10 parts polypropylene [Viscol 66QPJ (manufactured by Sanyo Chemical)
3-part charge control agent [nigrosine 8
0 J (manufactured by Orient Chemical Co., Ltd.) After mixing 2 or more parts of the substance in a ball mill, it is melt-kneaded in a twin-screw extruder, cooled and coarsely pulverized, and then finely pulverized in a jet mill. 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.

Hydrophobic silica fine powder rR, -972J was added to this toner powder.
(manufactured by Nippon Aerosil Co., Ltd.), in a proportion of 0.3 parts by weight,
The mixture was added with a mixer and sufficiently stirred using a mixer to obtain a toner with hydrophobic silica fine powder attached to the particle surface.

(Production of carrier) Styrene-butyl methacrylate (weight ratio 85:15, Mw/Mn=6.3, Tsp=1
41℃) ao part Magnetite l'-BL-100J (manufactured by Titan Kogyo Co., Ltd.) 70 parts Charge control agent "Bontron S-34J (manufactured by Orient Chemical Co., Ltd.) After mixing 2 parts or more of the substances in a ball mill with enough , melt-kneaded with a twin-screw extruder, coarsely pulverized after cooling, and then finely pulverized with a jet mill to obtain an average particle size of 21.8.
A micron powder was obtained. This fine powder is heated to 40°C with hot air.
The carrier particles were dispersed and sprayed in the hot air of a spray dryer (manufactured by Niro Corporation) maintained at 0° C., and the carrier particles were sphericalized by the surface tension of the molten carrier particles. Next, spherical magnetic material-dispersed microcarriers having an average particle size of 23.0 μm were obtained using a zigzag classifier. When the resistivity of this microcarrier was measured, it was 1014 Ω·(7) or more.

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 capacitor under the conditions described above, the quietness density was 0.63 WIg/mA, and the hardened bulk density was 0.89 mg.
/fnl.

The surface temperature of the heat roller of the heat roller fixing device was adjusted to 18
When an actual photographic test was carried out in which an image was formed on plain paper at a temperature of 0° C., the resulting image was clear and free of edge effects and capri and had a density of 1.22. 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 carrier is an organic photoconductive photoreceptor (hereinafter simply referred to as ROPC photoreceptor) with 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 peripheral speed of the OPC photoreceptor is 150 w/sec, the highest potential of the electrostatic image formed on the electrostatic image carrier is -520cm,
The outer diameter of the sleeve is 30m, and the number of rotations of the sleeve is 100.
rfm, the magnetic flux density of the N and S magnetic poles of the magnet body is 500 Gauss, and the magnetic flux density of the magnet body is 1;
/l ---m /&HM 1In-n M ml&
Female lW 17% rms t3Q, 2 mm, the gap between the sleeve and the electrostatic image carrier was 500 μm1 The bias voltage applied to the sleeve was 400 V with a DC voltage component of 1150 mm and an AC voltage component of 2.5 kHz. .

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

This developer had a quiet density of 0.58 q/g and a solidified bulk density of 0.771 Q/g.

When a photographing test was conducted using this developer in the same manner as in Example 1, the image density was low and the image was rough due to the occurrence of spots and capri.

Example 2 A toner was obtained in the same manner as in Example 1 except that the hydrophobic silica fine powder was not added. Next, hydrophobic silica fine powder "R-805" was added to the microcarrier obtained in Example 1.
j was added in a proportion of 0.2% by weight, and the mixture was sufficiently stirred using a mixer to obtain microcarriers having hydrophobic silica fine powder attached to the particle surfaces.

25 parts of the toner obtained as described above and 75 parts of the microcarrier were mixed to form a two-component developer of 1ipI.
[It's L.

The quietness density of this developer was 0.62 q/fd, and the solidified bulk density was 0.86 taps/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 1.18, and the image was clear with good gradation and no edge effect or capri. 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 toner was changed to double fikq6. Next, 0.1 weight of hydrophobic silica fine powder rl'L-972J was added to the microcarrier obtained in Example 1.
% and thoroughly stirred using a mixer to obtain microcarriers with hydrophobic silica fine powder attached to the particle surfaces.

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

The quietness density of this developer is 0.64'F/111/'
The solidified bulk density was 0.89 l/g.

Using this developer, we conducted an actual photographic test in the same manner as in Example 1, and the image density obtained was as high as 1.16, with good gradation and clear images without edge effects or capri. 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, Mw/Mn=11
．． 2, TSp=132℃) 10
0 part south -4 ノ ・ノ い Stone edge A `` 工
-4 I Shooting T, + (Cabot)
Part 10 Foliflopyrene “Viscole 66
0PJ (manufactured by Sanyo Chemical Co., Ltd.) 3 parts Charge control agent [Nigrosine EXJ (manufactured by Orient Chemical Co., Ltd.) 2 parts or more of the substance was treated in the same manner as in the production of toner in Example 16 to obtain an average particle size of 10 A toner powder with an irregular shape of .6 μm was obtained.

Add hydrophobic silica fine powder rR-812J (
(manufactured by Nippon Aerosil Co., Ltd.) was added at a ratio of 0.2% by weight and thoroughly stirred using a mixer to obtain a toner having hydrophobic silica fine powder adhered to the particle surface.

(Production of carrier) Maleic acid 25 parts Terephthalic acid 36 parts Bisphenol A 100 parts Magnetite [E
PT-1000J (manufactured by Toda Kogyo Co., Ltd.) 290 parts or more of the substance was placed in a 1 ton four-day flask, the gas phase was replaced with nitrogen gas, and the system was heated over a mantle heater for about 1 hour while stirring. The temperature was then raised to 150-160°C, kept at this temperature for another hour, and then raised further and kept at 210°C to remove water produced by the esterification reaction at the same time as the polymerization reaction. do the
A portion of the reactant was taken out at intervals of about 10 to 15 minutes to measure the acid value, and when the acid value reached 40, the reaction system was cooled to a temperature of 140°C, and hydroquinone was added to complete the polymerization. Ta. After cooling, dehydration and washing were repeated and dried to obtain spherical magnetic material-dispersed microcarriers with an average particle size of 25 μm. When the resistivity of this microcarrier was measured, it was 1014 ohms or more.

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 0.6 a++v/ld, and the hardened bulk density was 0.90.
It was mg/-.

When a photographic test was carried out using this developer in the same manner as in Example 1, the initial image obtained had a high density of 1.24 and was a clear image without edge effects or fog. Furthermore, when continuous copying was performed 30,000 times, the density of the image was as high as 1.28 even after 30,000 copies.
I was also able to obtain good images that were stable and unchanged from beginning to end.

Further, no staining of the image occurred.

[Brief explanation of the drawing]

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 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 in which an oscillating electric field is generated. In an image forming method including a developing step of developing a latent image on a latent image carrier, the toner is an amorphous particle powder, and the carrier is an average particle consisting of a binder resin containing fine magnetic powder dispersed therein. A spherical particle powder with a diameter of 10 to 50 μm,
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.