JPH01138573A - Image forming method - Google Patents

Abstract

PURPOSE:To form multicolor images whose image density is high and whose image quality is excellent by forming developer of toner particles and organic particulates whose diameter is smaller than that of the toner particles. CONSTITUTION:The developer is formed of the toner particles and the organic particulates whose diameter is smaller than that of the toner particles. Therefore, the physical adhesive strength of the toner particles with respect to a latent image carrier is weakened by virtue of spacer effects by the organic particulates so that the transferring ability of a multicolor toner image to a transferring material can be improved in a transfer process. The organic particulates are used whose average diameter is 0.1-3mum, whereby the organic particulates can uniformly exist with respect to the toner particles. As a result, uniform developing ability without irregularity is exercised. Thus, multicolor images can be formed whose density is high and whose quality is excellent.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for forming particles used in, for example, electrophotography, electrostatic recording, electrostatic printing, etc., and more specifically, a method for forming multicolor images. The present invention relates to a method for forming particles.

[Technology background]

At present, as a method for forming a visible image from certain image information, methods using electrostatic latent images, such as electrophotography, electrostatic recording, and electrostatic printing, are widely used.

For example, in electrophotography, a latent image carrier having a photosensitive layer made of a photoconductive material is given a static charge of -, and then the surface of the latent image carrier corresponds to the original by exposing the original. An electrostatic latent image is formed, and this electrostatic latent image is developed with a developer to form a toner image. This toner image is transferred to a transfer material such as paper by electrostatic force, and then fixed by heating or pressure to form a copy image. On the other hand, after the transfer process, the latent image carrier is neutralized, residual toner remaining on the latent image carrier without being transferred is cleaned, and then the next copy image is formed.

Conventionally, a method for forming a multicolor image has been to use multiple developers of different colors and repeatedly perform development for each color, thereby creating a multicolor toner image superimposed on the surface of a latent image carrier. A known method is to form a multicolor toner image, then transfer this multicolor toner image to a transfer material all at once using electrostatic force, and then fix this to form a multicolor image.

[Problem that the invention seeks to solve]

However, in conventional developers, the physical adhesion of toner particles to the latent image carrier is high, and in the above particle forming method, multiple development steps are required after the first color development step is started. Because it takes a certain amount of time to complete the process, the charge on the multicolor toner image tends to disappear, resulting in poor transfer of the multicolor toner image to the transfer material, resulting in a decrease in image density or poor image quality due to transfer misalignment. There is a problem that the performance decreases.

The present invention has been made based on the above circumstances, and it is an object of the present invention to provide a particle forming method capable of forming a multicolor image with good transferability, high image density, and good image quality. be.

[Means for solving problems]

The particle forming method of the present invention includes a step of forming a superimposed multicolor toner image on the surface of a latent image carrier by performing development multiple times, and a step of transferring the multicolor toner image to a transfer material all at once. The developer includes toner particles and organic fine particles having a smaller diameter than the toner particles.

[Function and effect of the invention]

According to the present invention, since the developer includes toner particles and organic fine particles having a smaller diameter than the toner particles, the toner particles are physically attached to the latent image carrier due to the so-called spacer effect of the organic fine particles. The adhesion force is weakened, and therefore, in the transfer process, the transferability of the multicolor toner image to the transfer material is improved, and an image with high image density and good quality can be formed.

In addition, by using fine particles preferably having an average diameter of 0.1 to 3 μm, it is possible to evenly distribute the organic fine particles to the toner particles, and as a result, even and uniform development performance can be achieved. - It is possible to form a multicolor image with excellent image quality.

Since the so-called spacer effect of the organic fine particles suppresses the filming phenomenon of the developer transport carrier caused by toner substances, a developer layer of a predetermined thickness can be stably formed on the developer transport carrier. Therefore, the ability of the developer transport carrier to transport the toner to the development area becomes stable, and from this point of view as well, it is possible to prevent a decrease in image density.

[Specific structure of the invention]

In the particle forming method of the present invention, a specific developer is used. That is, the developer includes toner particles and organic fine particles smaller in diameter than the toner particles as essential components. In the present invention, any type of developer can be used, such as a one-component developer that does not contain a carrier or a two-component developer that contains a carrier.

The organic fine particles constituting the developability are preferably smaller in diameter than the toner particles, and the average diameter of secondary particles (particles separated into individual unit particles) is preferably 0.05 to 3 μm. A circumference of 0.1 to 2.0 μm is preferable. When the average diameter of the organic fine particles is too large, toner transportability deteriorates, which tends to cause a decrease in image density.

- When the average diameter of the organic fine particles is too small, cleaning defects of residual developer tend to occur.

The proportion of the organic fine particles is preferably 0.01 to 3.0% by weight, particularly preferably 0.1 to 2.0% by weight, based on the total toner. If the proportion of organic fine particles is too small, the toner transportability is likely to deteriorate, resulting in a decrease in image density, and cleaning of residual developer is likely to occur.

- When the proportion of organic fine particles is excessive, the triboelectric charging properties of the toner are likely to be inhibited.

The organic substance for forming the organic fine particles is not particularly limited, but vinyl polymers are preferred because they are relatively hard and provide appropriate polishing performance.

Such vinyl polymers can be produced by various polymerization methods such as emulsion polymerization and suspension polymerization, but the emulsion polymerization method is preferred because small-diameter, spherical organic fine particles can be efficiently obtained. In particular, in systems where the monomer itself for obtaining the vinyl polymer has an emulsifying effect, it is preferable to obtain the vinyl polymer by emulsion polymerization without using an emulsifier.

Examples of the vinyl polymer include acrylic polymers, styrene polymers, vinyl bases, fluororesins, and the like, with acrylic polymers being preferred.

Acrylic polymers are homopolymers or copolymers obtained by polymerizing monomers selected from acrylic acid, acrylic esters, methacrylic acid, and methacrylic esters. Acrylic monomers used to obtain such acrylic polymers include acrylic acid,
Methyl acrylate, ethyl acrylate, n-acrylate
Butinope isobutyl acrylate, propyl acrylate,
n-octyl acrylate, dodecyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, 2-chloroethinopea acrylate, phenyl acrylate, methyl α-chloroacrylate, methacrylic acid, methyl methacrylate, methacrylate Ethyl acid, propyl methacrylate, n-butinope methacrylate, inbutyl methacrylate, n-octinope methacrylate, dodecyl methacrylate, urinope methacrylate 2 methacrylate
- Ethylhexynope Stearinope methacrylate Phenyl methacrylate, dimethylaminoethyl methacrylate, diethylamide/ethyl methacrylate, and the like.

Among the acrylic polymers, polymethyl methacrylate is particularly preferred. With polymethyl methacrylate, uniform and small-diameter organic fine particles can be easily obtained,
In addition, it is possible to obtain an appropriate polishing performance and suitably weaken the physical adhesion of the toner to the latent image carrier or the developer transport carrier, so that a -Five effect is exhibited.

Furthermore, since there is no risk of inhibiting the triboelectric charging properties of the toner, stable developing performance can be obtained.

As the acrylic polymer, other a
The i-form may be copolymerized.

In this case, it is preferable to use the acrylic monomer in a proportion of 1% or more in the monomer composition. Such other monomers include styrene, 0-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, p-n-butylstyrene. , p-tert-butylstyrene, p-n-hexylstyrene, p-n-octylstyrene, p-n-nonylstyrene, p-n-decylstyrene, p-n-dode/rustyrene, p-methoxystyrene, 111 styrene compounds such as p-phenylstyrene, p-chlorostyrene, 3,4-dichlorostyrene,
Acrylic acid or methacrylic acid derivatives such as acrylonitrile, methacrylonitrile, and acrylamide; Vinyl esters such as vinyl acetate and vinyl benzoate; Vinyl ethers such as vinyl methyl needle and vinyl ethyl ether; Vinyl ketones such as vinyl methyl ketone ; dienes such as butadiene and isoprene; unsaturated carboxylic acids such as maleic acid and fumaric acid; and others.

In order to improve the fluidity of the developer, it is preferable that inorganic fine particles are further present. Such a-free particles are -
The average diameter of the secondary particles (particles separated into individual unit particles) is preferably 2 μm or less, particularly preferably lam or less. When the average diameter of the inorganic fine particles is too large, the surface of the latent image carrier is likely to be damaged.

In addition, the proportion of inorganic fine particles is 0.05 to 2
．． 0% by weight is preferred, particularly 0.1-1.0% by weight. If the proportion of the inorganic fine particles is too small, the effect of improving the fluidity of the developer cannot be obtained, while if the proportion is too large, damage is likely to occur on the surface of the latent image carrier.

Examples of constituent materials of inorganic fine particles include oxides such as silica, titanium oxide, aluminum oxide, zirconium oxide, barium titanate, lead titanate, and barium carbonate; nitrides such as silicon nitride and boron nitride; silicon carbide and aluminum carbide. , carbides such as titanium carbide; and others. These inorganic fine particles may be surface-treated.

Particularly preferred are silica fine particles or surface-treated silica fine particles. As the surface treatment agent, for example, a silane coupling agent, a titanium coupling agent, etc. can be used. The surface-treated silica fine particles are highly stable against environmental changes such as temperature and humidity, so that the environmental dependence of the triboelectric charging property of the toner can be suppressed to a small level.

Two or more types of inorganic fine particles may be used in combination. In this case, it is preferable to always use silica fine particles or surface-treated silica fine particles.

The above organic fine particles and inorganic fine particles are preferably used by being added to and mixed with the toner particles from the outside.

Specifically, by mixing toner particles, organic fine particles, and inorganic fine particles using a mixing device such as a V-type blender, it is possible to make the sensitive particles and inorganic fine particles exist on the surface of the toner particles. preferable.

The toner particles constituting the developer are particles in which, for example, a magnetic material, a colorant, an offset inhibitor, a charge control agent, etc. are contained in a binder resin.

The binder resin is not particularly limited, and various resins can be used. Specifically, styrene resins, acrylic resins, styrene-acrylic copolymer resins, epoxy resins, polyester resins, etc. can be mentioned.

These resins may be used in combination.

The styrene/acrylic copolymer resin used as the binder resin is a resin made of a copolymer of a styrene monomer and an acrylic monomer. Styrene monomers include styrene, 0-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, p-n-butylstyrene, p-tert-butylstyrene, p-n
-hequinrustyrene, p-n-octylstyrene, p-
n-nonylstyrene, p-n-decylstyrene, p-n
-dodecylstyrene, p-methoxystyrene, p--phenylstyrene, p-chlorostyrene, 3°4-dichlorostyrene, and the like.

Examples of acrylic compounds include acrylic acid, methyl acrylate, γ-ethyl acrylate, n-butyl acrylate, isobutyl acrylate, propyl acrylate, and n-acrylate.
-Octyl, dodecyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, acrylic! 2-'F-ethyl, phenyl acrylate, methyl α-chloroacrylate, methacrylic acid, methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-octyl methacrylate, methacrylate Examples include dodecyl acid, lauryl methacrylate, 2-ethylhexynope methacrylate, stearinope methacrylate, phenyl methacrylate, dimethylaminoethinope methacrylate, diethylaminoethyl methacrylate, acrylonitrile, methacrylonitrile, acrylamide, and others.

Magnetic substances include substances that are strongly magnetized in the direction of a magnetic field, such as metals or alloys that exhibit ferromagnetism such as iron, ferrite, and magnetite, such as iron, nickel, and cobalt, compounds containing these elements, and ferromagnetic elements. A type of alloy called Heusler alloy containing manganese and copper, such as manganese-copper-aluminum, manganese-copper-tin, etc., which does not contain manganese but becomes ferromagnetic through appropriate heat treatment Examples include chromium dioxide and others. The magnetic material has an average particle size of 0.1
It is preferable that it is uniformly dispersed and contained in the form of a fine powder of ~1 p. When the toner is used as a -component developer, the content of the magnetic material is preferably 20 to 80% by weight, particularly preferably 30 to 711%, based on the total toner.

Examples of colorants include carbon black, nigrosine dye, aniline blue, calco oil blue, chrome yellow, ultramarine blue, DuPont oil red, quinoline yellow, methylene blue chloride, phthalocyanine blue, malachite green oxalate,
Mention may be made of lamp black, rose bengal, mixtures thereof, and others.

Examples of the charge control agent include metal complex dyes, nigrosine dyes, and an(nium salt) compounds.

Examples of anti-offset agents include low softening point polyolefins, high melting point paraffin waxes, silicone resins, fatty acid esters or partially saponified products thereof, fatty acid amide compounds, higher alcohols, and the like.

When a two-component developer is used, a carrier is mixed with the above toner to form the developer. Such a carrier is not particularly limited, and conventionally known carriers can be used. Specifically, either a carrier composed of only magnetic particles or a resin-coated carrier in which the surface of magnetic particles is coated with resin can be used.

The magnetic particles constituting the carrier include materials that are strongly magnetized in the direction of a magnetic field, such as iron, ferrite,
Metals or alloys that exhibit ferromagnetism, such as magnetite, iron, nickel, and cobalt, or compounds that contain these elements; alloys that do not contain ferromagnetic elements but become ferromagnetic through appropriate heat treatment, e.g. An alloy called Heusler alloy such as manganese-copper-aluminum or manganese-copper-tin, or particles made of chromium dioxide or the like can be used.

The average particle size of the carrier is preferably 40 to 200 us, particularly preferably 50 to 150 am. When the average particle size of the carrier is too small, a so-called carrier adhesion phenomenon occurs in which the carrier adheres to and is fixed on the electrostatic latent image, resulting in an unclear image; on the other hand, when the average particle size of the carrier is too large In this case, image distortion may occur.

Here, the average particle diameter (weight) of the carrier is a value measured using "Microtrack" (manufactured by Nikkiso Co., Ltd.).

Next, each step of the particle forming method of the present invention will be specifically explained.

(Development step) Using a one-component developer or a two-component developer comprising toner particles and fine particles smaller in diameter than the toner particles as essential components, preferably a thin layer is formed on a developer transport carrier. A developer layer is formed, and the electrostatic latent image on the latent image carrier is developed by this developer layer.

During development, it is preferable to apply an alternating current bias voltage in order to apply an oscillating electric field to the development area.

The gap (hereinafter also referred to as "development gap") Dsd between the latent image carrier and the developer transport carrier in the development area is 200
It is preferably in the range of ~2000 μm.

Further, the thickness of the developer layer is preferably 2000 μm or less, more preferably 1000 nm or less, and particularly preferably 10 to 500 μm.

The developer transport carrier for transporting the developer layer to the development area is not particularly limited, but for example, one having the same structure as the conventional one to which a bias voltage can be applied can be used.

In particular, a structure in which a cylindrical developing sleeve carrying a developer layer and a magnetic roll having a plurality of magnetic poles is preferably used.

The means for forming a thin developer layer on the developer transport carrier is not particularly limited, but for example, the developer layer may be formed into a thin layer using a regulation blade whose tip is placed close to the surface of the developer transport carrier. For example, an elastic plate-like thin layer forming member is placed in elastic pressure contact with the surface of the developer transporting carrier, and the developer is passed between the thin layer forming member and the developer transporting carrier. Accordingly, means for making the developer layer thin can be used. When a thin layer forming member is used, it is preferably an elastic plate that is pressed against the developer transport carrier such that its tip faces upstream in the rotational direction of the developer transport carrier.

By making the developer layer supported on the developer transporting carrier thin, the development gap Dsd can be made sufficiently small, and therefore the bias voltage required to form the oscillating electric field can be lowered, so that the toner This has the advantage of reducing scattering and preventing the occurrence of leakage discharge or the like based on the bias voltage from the surface of the developing sleeve. In addition, by reducing the development gap Dsd, the electric field strength formed in the development area by the electrostatic latent image formed on the latent image carrier increases, resulting in subtle changes in gradation and fine patterns. can also be developed well.

However, if the developer layer on the developer transport carrier is thin, the amount of toner transported to the development area generally decreases, and as a result, the amount of toner that adheres to the electrostatic latent image on the latent image carrier is insufficient. There is a risk of Therefore, it is preferable to rotate the developing sleeve at high speed to increase the amount of toner conveyed. Actually, it is preferable that the linear velocity of the developing sleeve in the developing area is within 10 times the linear velocity of the latent image carrier.

By repeating the above-described development process a number of times corresponding to the types of developers with different colors, a multicolor toner image in which toner images of two or more colors are sequentially superimposed is formed on the latent image carrier. do.

(Transfer step) The multicolor toner image on the latent image carrier obtained by development is transferred to a transfer material all at once. In this transfer step, either an electrostatic transfer method or a bias transfer method can be applied, and the electrostatic transfer method is particularly preferably used. Specifically, for example, a transfer device that generates DC corona discharge is arranged to face the latent image carrier through the transfer material, and the latent image is carried by applying DC corona discharge to the transfer material from the back side. The multicolor toner image carried on the surface of the body is transferred to the surface of the transfer material.

(Cleaning Step) After the transfer step, the developer remaining on the latent image carrier is cleaned. The cleaning means is not particularly limited, but a cleaning device having a cleaning blade disposed in contact with the surface of the latent image carrier can be preferably used. According to this cleaning device, the surface of the latent image carrier is rubbed by the cleaning blade, thereby scraping and removing residual developer.

In order to facilitate cleaning, it is preferable to add a static elimination process to neutralize the surface of the latent image carrier before the cleaning process. This static elimination step can be performed, for example, using a static eliminator that generates AC corona discharge.

(Fixing Step) In the transfer step, the transfer material onto which the multicolor toner image has been transferred is subjected to a fixing process using a heat fixing device, a pressure fixing device, or the like, thereby forming a fixed image.

FIG. 1 is an explanatory diagram showing an example of a multicolor image forming apparatus that can be used to carry out the particle forming method of the present invention. In the figure, lO is a latent image carrier, 20 is an image input unit, and 26
is an image processing unit, 27 is a laser optical system, 30A, 30
B, 30C, and 30D are developing devices, and 40 is a transfer device.

The image human power section 20 is configured by integrally uniting an illumination light source 21, a mirror 22, a lens 23, and a -dimensional color CCD image sensor 24. While the image manual unit 20 is moved in the direction of the arrow X by a drive device (not shown), the original 25 is read by the CCD image pickup device 24. Note that a configuration may be adopted in which the image manual unit 20 is fixed and the document table is moved.

The image information read by the image processing unit 20 is processed by the image processing unit 2.
6, the data is converted into data suitable for recording. The laser optical system 27 forms an electrostatic latent image on the latent image carrier 10 in the following manner based on the above image data. That is, the surface of the latent image carrier 10 is uniformly charged by the scorotron charger 28, and then an original light image according to the recorded data is irradiated from the laser optical system 27 onto the latent image carrier 10 through a lens. , an electrostatic latent image corresponding to the original is formed on the latent image carrier 10.

This electrostatic latent image is first developed by a developing device 30A containing a first color toner (for example, yellow toner). After the latent image carrier 10 on which the toner image of the first color toner has been formed rotates once, the latent image carrier 10 is transferred to the scorotron charger 2 again.
8, and is irradiated with a document light image according to recording data of different color components. The electrostatic latent image thus formed is developed by a developing device 30B containing a second color toner (for example, magenta toner).

As a result, a two-color toner image is formed on the latent image carrier 10, in which the first-color donor image and the second-color toner image are superimposed. Subsequently, in the same manner as described above, a toner image of a third color toner (for example, cyan toner) and a toner image of a fourth color toner (for example, black toner) are sequentially superimposed, thereby forming four colors on the latent image carrier 10. A multicolor toner image is formed in which the toners are superimposed.

The multicolor toner image thus obtained is exposed to the exposure lamp 5.
1 to remove the charge and make it easy to transfer, the transfer device 40 transfers the image onto the transfer paper P all at once. Transfer paper P
is separated from the latent image carrier 10 by a separator 52 and subjected to fixing processing by a fixing device 53, thereby forming a fixed image. On the other hand, the latent image carrier 10 is neutralized by a static eliminator 54, and its surface is cleaned by a cleaning device 55, and the latent image carrier 10 is used for forming the next multicolor image.

The cleaning device 55 in this example includes a cleaning blade 56 and a fur run 57.

These are the latent image carrier 10 during the image forming process.
When the final multicolor toner image is formed on the latent image carrier 10, the cleaning blade 56 and the fur brush 57 are kept in a non-contact state with the latent image carrier 10.
The latent image carrier 10 is brought into contact with the latent image carrier 10 after the multicolor toner image is transferred.
Scrape off the developer remaining on the top. Thereafter, the cleaning blade 56 separates from the latent image carrier 10, and a little later, the fur brush 57 separates from the latent image carrier 10.

The fur run 57 has a function of removing the developer remaining on the latent image carrier 10 when the cleaning blade 56 leaves the latent image carrier 10 . 58 is a roller that collects the toner scraped off by the blade 56.

Details of the developing devices 30A to 30D are shown in FIG. In the figure, 61 is a developing sleeve, 62 is a magnetic roll,
These developing sleeve 61 and magnetic roll 62 constitute a developer transport carrier. The magnetic roll 62 has a structure in which north poles and south poles are alternately arranged along the circumference. 64 is a thin layer forming member, 65 is a first stirring member, 66 is a second stirring member, 67 is a toner supply container, 68 is a toner supply roller, 69 is a developer reservoir, 70 is a bias power source, and 71 is a developing area It is.

The first stirring member 65 and the second stirring member 66 have a structure in which they are rotated in opposite directions so that their stirring regions overlap without colliding with each other, as shown by the arrows.

In the developing devices 30A to 30D, the developer reservoir 69
The developer inside is sufficiently stirred and mixed by the stirring members 65 and 66, and the developer is transferred to the surface of the developing sleeve 61 by the conveying force of the developing sleeve 61 rotating in the direction of the arrow and the magnetic roll 62 rotating in the opposite direction. attached to.

A plate-shaped thin layer forming member 64 made of an elastic material is held in pressure contact with the surface of the developing sleeve 61 on one side near the tip thereof. The thickness of the developer layer conveyed to the development area 71 is regulated by the thin layer forming member 64 to form a thin layer.

The developer layer formed into a thin layer by the thin layer forming member 64 preferably faces the electrostatic latent image formed on the latent image carrier 20 rotating in the direction of the arrow with a slight gap therebetween. The electrostatic latent image on the latent image carrier 10 is transferred to the developing area 71 in a non-contact state, and is subjected to the action of an oscillating electric field from the bias power source 70, in which the electrostatic latent image on the latent image carrier 10 is formed by a thin developer layer. It is developed and a toner image is formed. Note that when the developer layer comes into contact with the latent image carrier, it becomes difficult to superimpose toner images of different colors on the latent image carrier in an appropriate state.

The thickness of the thin developer layer formed on the developing sleeve is
For example, using a "Nikon Profile Projector" (manufactured by Nippon Kogaku Co., Ltd.), compare the projected image of the developing sleeve onto the screen and the stopping position of the projected image onto the screen with a thin developer layer formed on the developing sleeve. The thickness of the developer layer can be determined by:

The thin layer forming member 64 can be made of magnetic or non-magnetic metal, metal compound, plastic, rubber, etc., with one end fixed by a fixing member and imparted with elasticity, and its thickness must be extremely thin. is preferable, and it is preferable that the thickness is uniform. Specifically, the thickness is preferably 50 to 500 us.

The thin layer forming member 64 is elastically pressed against the developing sleeve 61 on one side near its tip, so that the developer is allowed to pass little by little between the thin layer forming member 64 and the developing sleeve 61. The amount of developer conveyed is regulated. Impurities, aggregates, etc. in the developer are prevented from entering the developing area 71 by the thin layer forming member 64.
The developer layer conveyed to No. 1 is a thin layer, and its thickness is uniform and stable. Furthermore, the amount of developer conveyed to the developing area 71 can be sufficiently controlled by changing the pressing force and contact angle of the thin layer forming member 64 against the developing sleeve 61.

By making the developer layer formed on the developer transport carrier a thin layer, it becomes possible to considerably reduce the development gap Dsd between the latent image carrier 10 and the development sleeve 61, which is a so-called non-contact development method. development can be carried out satisfactorily. When the development gap Dsd is made small in this way, the electric field strength in the development area 71 becomes large, so that sufficient development can be performed even if the bias voltage applied to the development sleeve 61 is made small. This has the advantage of reducing bias voltage leakage and the like. Furthermore, since the contrast of the electrostatic latent image is increased, the resolution or quality of the image obtained by development is generally improved.

〔Example〕

Examples of the present invention will be specifically described below, but the present invention is not limited to these Examples.

Example 1 (Production of developer) (1) Blue developer D1 Styrene-acrylic copolymer resin (monomer composition: 65 parts by weight of styrene, 5 parts by weight of α-methylstyrene, 10 parts by weight of methyl methacrylate, n -18 parts by weight of butyl acrylate 17-ate, 2 parts by weight of divinylbenzene) and a coloring agent "Pigment Blue 15:3J (manufactured by Yamamasha Co., Ltd.)"
5 parts by weight, low molecular weight medium polypropylene "Viscol 66"
4 parts by weight of 0PJ (manufactured by Kochu Kasei Kogyo Co., Ltd.) were mixed, kneaded, crushed, and classified to obtain toner particle powder with an average particle size of 12 nm.

Next, an organic fine particle powder (polymethyl methacrylate fine particles, average diameter of -order particles = 0.5
μm) 0.8% by weight, inorganic fine particle powder rR-972J
(Hydrophobic silica fine particles, average diameter of -order particles = Q, O16
Jjn (manufactured by Nippon Aerosil Co., Ltd.) was mixed and stirred at a ratio of 0.8% by weight, and a carrier consisting of copper-zinc ferrite particles (manufactured by Nippon Iron Powder Co., Ltd.) with an average particle size of 120 μm was further mixed to form a toner. Blue developer D with a concentration of 3% by weight
I was produced.

(2) Red Developer D2 A red developer D2 was produced in the same manner as in the production of the blue developer except that the colorant was changed to Pigment Red 149J (manufactured by Hoechst) 5-layer IN.

(3) Yellow developer D3 Yellow developer D3 was produced in the same manner as in the production of the blue developer except that the colorant was changed to 5 parts by weight of "Pigment Yellow 19" (manufactured by Hoechst).

(Actual photo test) Equipped with a latent image carrier made of an organic photoconductive photoreceptor, three developing devices, an electrostatic transfer device, and an IJ + printing device with a blade, toner images of multiple colors are produced on the latent image carrier. Using a modified electrophotographic copying machine rU-8ix 5000J (manufactured by Konishi Roku Photo Industries Co., Ltd.) that enables the formation of multicolor images by overlapping them, the order of blue developer D1, red developer D2, and yellow developer D3 was used. By repeating development, a multicolor toner image in which three colors of blue, red, and yellow toner are superimposed is formed on the latent image carrier, and this multicolor toner image is transferred all at once by an electrostatic transfer device. A photocopying test was repeated many times in which a multicolor image was formed by transferring the image to a transfer paper and then heat-fixing it.

In carrying out the development process, the gap between the latent image carrier and the developer transport carrier, that is, the development gap Dsd, is defined as Q,
5 mm, the thickness of the developer layer supported on the developer transport carrier and transported to the development area is 0.3+++m, and an alternating electric field (peak-to-peak value = 2 kV, frequency = 2 kHz) and a DC bias voltage are applied to the development area. (-500V) was applied, and a reversal development method was adopted.

Visual observation of the obtained multicolor image revealed that in the solid image area, the three color toners were uniformly dispersed, the image quality was good, and the image density was sufficiently high.
In the thin line image area of mm, the three colors of toner were perfectly superimposed, no transfer deviation was observed, and the fine line reproducibility was excellent.

Comparative Example 1 For comparison, a comparative blue developer d was produced in the same manner as in Example 1 except that organic fine particles were not used.
1. A red developer d2 and a yellow developer d3 were produced, and a photographic test was conducted using these developers in the same manner as in Example 1, and the resulting multicolor image was visually observed.
In the solid image area, the three colors of toner were unevenly distributed, resulting in non-uniform coloring, and in the 5 lines/mm thin line image area, transfer deviation of the three colors of toner occurred, resulting in poor fine line reproducibility.

Example 2 (Manufacture of developer) (1) Blue developer D1 Blue developer D1 was produced in the same manner as in Example 1.

(2) Red developer D2 Red developer iD2 was produced in the same manner as in Example I.

(3) Yellow developer D3 Yellow developer D3 was produced in the same manner as in Example 1.

(4) Black developer D4 Styrene-acrylic copolymer resin (monomer composition: 65 parts by weight of styrene, 5 parts by weight of α-methylstyrene, 10 parts by weight of methyl methacrylate, 1 part by weight of n-butyl acrylate)
8 parts by weight, 2 parts by weight of divinylbenzene) 56 parts by weight,
Magnetite rBL-100J (Titan Industry Co., Ltd.)
40 parts by weight and low molecular weight polypropylene loviscol 6
2 parts by weight of 60PJ (manufactured by Kochu Kasei Kogyo Co., Ltd.) and 1 part of Carbon Black R Mogul L (manufactured by Cabot Corporation) were mixed, kneaded, crushed, and classified to determine the average particle size. A powder of toner particles of 12 micron particles was obtained.

Next, an organic fine particle powder (polymethyl methacrylate fine particles, average diameter of -order particles = 0.5
JIg) 0.5% by weight, inorganic fine particles≠powder rR-805
J (hydrophobic silica fine particles, average diameter of -order particles = 0.01
2 am, manufactured by Nippon Aerosil Co., Ltd.) were mixed and stirred at a ratio of 0.5% by weight to produce black developer D4.

(Actual photo test) The machine is equipped with a latent image carrier made of an electroconductive photoreceptor, four developers, an electrostatic transfer device, and a cleaning device with a blade, and toner images of multiple colors are superimposed on the latent image carrier. Electrophotographic copying machine rU-8ix 5000J (manufactured by Konishiroku Photo Industry Co., Ltd.), which made it possible to form multicolor images by
Using a modified machine, by repeatedly performing development in the order of black developer D4, blue developer Di, red developer D2, and yellow developer D3, four colors of black, blue, red, and yellow are formed on the latent image carrier.
A multicolor toner image is formed by overlapping colored toners, and this multicolor toner image is transferred all at once to transfer paper using an electrostatic transfer device, and then heated and fixed to form a multicolor image. This was repeated over and over again.

Visual observation of the obtained multicolor image revealed that in the solid image area, the four color toners were uniformly dispersed and the image quality was good, and the image density was sufficiently high.
In the fine line image area of m1Tl, the four color toners were perfectly superimposed, no transfer deviation was observed, and the fine line reproducibility was excellent.

Comparative Example 2 For comparison, a comparative blue developer d was produced in the same manner as in Example 2 except that organic fine particles were not used.
l, red developer d2, yellow developer d3, black developer d4
A photographic test was conducted in the same manner as in Example 2 using these developers, and the resulting multicolor image was visually observed. It was found that the four color toners were unevenly distributed in the solid image area. Not only was the color non-uniform, there were also transfer gaps. In addition, in the fine line image area of 5 lines/mm, 4
Transfer misalignment of color toner occurred, resulting in fine line blurring and poor fine line reproducibility.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing an example of a multicolor image forming apparatus that can be used in the particle forming method of the present invention, and FIG. 2 is an explanatory diagram showing details of a developing device. 10...Latent image carrier 20...Image personnel department 2
5... Original 26... Image processing section 27
... Laser optical system 28 ... Charger 3QA,
30B, 30C, 30D...Developer 40...Transfer device 53...Fixer 55...Cleaning device P...Transfer paper 61...Developing sleeve
62... Magnetic roll 64... Thin layer forming member 6
5.66... Stirring member 67... Toner supply container
68...Toner supply roller 69...Developer reservoir
70...Bias power supply 71...Development area

Claims (1)

[Claims] 1) A step of forming a superimposed multicolor toner image on the surface of a latent image carrier by performing development multiple times, and a step of transferring the multicolor toner image to a transfer material all at once. A method for forming particles, the developer comprising toner particles and organic fine particles having a smaller diameter than the toner particles. 2) The image forming method according to claim 1, wherein the organic fine particles have an average diameter of 0.05 to 3 μm. 3) The image forming method according to claim 1 or 2, wherein the organic fine particles are made of a vinyl polymer. 4) The image forming method according to claim 3, wherein the vinyl polymer is an acrylic polymer. 5) The image forming method according to claim 4, wherein the acrylic polymer is polymethyl methacrylate. 6) The image forming method according to any one of claims 1 to 5, wherein the developer further contains inorganic fine particles. 7) The image forming method according to any one of claims 1 to 6, wherein the inorganic fine particles are made of silica or surface-treated silica. 8) The image forming method according to claim 6, characterized in that two or more types of inorganic fine particles are used. 9) The image forming method according to claim 8, wherein one of the inorganic fine particles is made of silica or surface-treated silica.