JP2002207317A - Flat toner, production of the toner, and image forming method using the toner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide flat toner, production of the toner, and an image forming method using the flat toner, which make it possible to form a high density image even with a small amount of toner and which makes it possible to obtain a high quality image in which recesses and projections are less and toner scatter is prevented. SOLUTION: The shape of the toner is flat. The toner is obtained by salting out/fusing resin particles having a number average primary particle diameter of 10 to 500 nm, thereby producing secondary particles and by flattening the secondary particles.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flat toner used for a copying machine, a printer and the like, a method for producing the flat toner, and an image forming method using the flat toner.

[0002]

2. Description of the Related Art An image formed by using a toner produced by a usual pulverization method or polymerization method has a large amount of toner consumption, so that the surface has irregularities, and a glossy and good image is not obtained. It was difficult to get an image. Further, at the time of transfer, a large amount of toner was consumed, so that the toner layer was thickened and the transfer rate was deteriorated, so that a high-density image could not be obtained.

Until now, in order to obtain a print-like high-quality image, attempts have been made to reduce the toner consumption by reducing the particle size of the toner, eliminate unevenness on the surface, and obtain uniform gloss. In addition, as the toner particle size is reduced, the covering power of the toner is reduced, sufficient image density cannot be obtained, and image forming processes such as development, transfer, and cleaning of a photoreceptor become difficult. Does not provide high quality images. Also, if the toner particle size is 2 to
When toner particles having a particle size reduced to 3 μm are used, inhalation of the toner particles may cause diseases such as pneumoconiosis, which is not preferable in terms of safety and hygiene.

When a color image (25% printing rate) is formed by superposing color toners by electrophotography using a color toner having a spherical or irregular shape having a particle diameter of about 5 μm and having no worry about pneumoconiosis, etc. The toner consumption is about 90 mg per A-4 size print, and development, transfer,
In fixing, a thick toner layer is handled. For this reason, toner scattering occurs in the toner image, and irregularities occur on the image surface, so that the difference in gloss between the toner-attached portion and the base portion is increased, so that a high-quality image cannot be formed at present.

[0005]

DISCLOSURE OF THE INVENTION The present invention has been proposed in view of the above problems.
A flat toner capable of obtaining a high-density image even with a small amount of toner consumption, obtaining a high-quality image with little unevenness and no toner scattering, a method for producing the flat toner, and the flat toner. An object of the present invention is to provide an image forming method.

[0006]

The object of the present invention is achieved by adopting the following constitution.

[0007] 1. Resin particles having a number average primary particle diameter of 10 to 500 nm are salted out / fused to form secondary particles, and the toner obtained by flattening the secondary particles has a flat shape. Characterized flat toner.

[0008] 2. The shape of the flat toner has a long side (r ₁ ) and a short side (r ₂ ) with an average length of 5 to 20 μm and an average thickness (d).
Is 1 to 5 μm, the ratio of the short side to the long side of the average length (r ₂ / r ₁ ) is 0.6 to 1.0, and the ratio of the average thickness of the flat toner to the average short side length (d / r ₂ ) is 2. The flat toner as described in 1 above, wherein the thickness is 0.1 to 0.4.

3. 3. The flat toner according to 1 or 2,
A method for producing a flat toner, comprising circulating a pressurized bottleneck in a heated state to flatten the particle shape and producing the toner.

[0010] 4. The state of adhesion of the flat toner on the image forming body is such that the flat portion of the flat toner adheres to the image forming body.

5. An image forming method in which the flat portion of the flat toner adheres to the image forming body, wherein the flat toner according to the above item 1 or 2 is used.

That is, the present inventors have conducted intensive studies, and as a result,
Even when the color toners are overlaid by the electrophotographic method, the toner consumption is A- when the printing ratio of the color original is 25%, and when the ordinary spherical or irregular toner is used.
Although 80 to 100 mg was required for one 4-plate print, when flat toner is used, the toner consumption becomes A-4.
A high-density image can be obtained even with a remarkably small amount of 20 to 40 mg per plate print, an image with less unevenness and excellent gloss unevenness can be obtained, and the thickness of the toner layer can be reduced. It has been found that high quality images can be formed without toner scattering during transfer.

Hereinafter, the present invention will be described in more detail. The flat toner of the present invention has a number average primary particle diameter of 10 to 500 n.
The secondary particles obtained by salting out / fusing the m resin particles can be manufactured by circulating through a pressurized bottleneck in a heated state and performing a flattening treatment.

The volume average particle diameter of the flat toner of the present invention is 3 to 3.
It is preferably 10 μm, more preferably 4 to 9 μm.

The flat toner of the present invention preferably has a specific shape. That is, the flat toner of the present invention preferably has a long side (r ₁ ) and a short side (r ₂ ) having an average length of 5 to 20 μm and an average thickness (d) of 1 to 5 μm. The ratio of the short side to the long side (r ₂ / r ₁ ) of the average length is preferably 0.6 to 1.0,
It is more preferably from 8 to 1.0, and the ratio of the average thickness to the average short side length (d / r ₂ ) of the flat toner is preferably from 0.1 to 0.4.

In fact, when such flat toner is used, when a color image (printing rate 25%) is formed by superposing color toners by electrophotography, the toner consumption per A-4 size print is as follows. A high-density image can be obtained with a remarkably small amount of at most 40 mg, usually 10 to 30 mg, and a high-quality image without toner scattering can be formed.

The average length (r ₁ , r ₂ ) of the flat toner is 5 μm.
If it is less than m, there is a risk of suffering from diseases such as pneumoconiosis, which is not preferable in terms of safety and hygiene. If it exceeds 20 μm, developability is reduced, and faithful development cannot be performed, and the resolution is undesirably reduced.

The ratio of the long side to the short side of the average length of the flat toner (r
_{When the} ratio ( ₂ / r ₁ ) is less than 0.6, the flat portion of the flat toner does not easily adhere to the image forming body, the toner layer becomes thicker, the toner consumption increases, and the toner is scattered in the transfer and fixing steps. It is not preferable because it also increases the spread.

If the average thickness (d) of the flat toner is less than 1 μm, the flat toner is crushed at the time of development, and ultrafine powder is generated, causing toner scattering and fogging. Is difficult to develop in a layered form, and the toner layer becomes thicker, and the amount of consumed toner is increased.

When the ratio of the average thickness to the average short side length (d / r ₂ ) of the flat toner is less than 0.1, the flat toner is crushed at the time of development, an ultrafine powder is generated, and toner scattering and fogging are caused. When the ratio exceeds 0.4, the flat portion of the toner hardly adheres to the image forming body, the toner is hardly developed in a layer shape, and the toner layer becomes thick and the toner consumption increases, which is not preferable. Further, toner scattering and toner spreading occur in the transfer and fixing steps, which is not preferable.

By forming the flat toner into the above-described shape, development is performed using the flat toner, and an image forming body (photoreceptor) is developed.
When an image is formed on the image forming body, the flat toner on the image forming body adheres in a more layered manner with the flat portion of the flat toner facing the image forming body. Also, when the flat toner is transferred from the image forming body to the intermediate transfer body or the transfer material, or when transferring from the intermediate transfer body to the transfer material, the flat portion of the flat toner is layered with the flat portion facing the intermediate transfer body or the transfer material. Adhered to.

The surface charge state of the flat toner is substantially uniformly charged, so that the Coulomb force between the image forming body and the flat portion of the flat toner is higher than that of the flat toner end portion. Is considered to be attached. In this way, the flat toner on the image forming body, on the intermediate transfer material or on the transfer material is arranged in the horizontal direction with the edges laid down, and the flat toners are easily overlapped with each other to form a layer, so that a stable toner image can be obtained even when the toner is moved. Presumed to be kept.

It is observed that the toner having an insufficient flatness or irregular toner is in a state of random attachment without flattening the flat portion and that toner scattering and toner image spread in the transfer and fixing processes. Was.

The toner having an insufficient flatness or an irregular toner is a toner having a shape deviating from the flat toner shape defined in the present invention. The prepared toner and the like correspond.

FIG. 1 is a schematic view showing an example of the flat toner of the present invention. In FIG. 1, r ₁ indicates the long side of the flat toner, r ₂ indicates the short side, and d indicates the thickness.

FIG. 2 is a schematic view showing an example of the flat toner adhered on the image forming body. In FIG. 2, reference numeral 10 denotes a photosensitive drum (photoconductor) as an image forming body, and 301 denotes flat toner.

The flat toner of the present invention has a number average primary particle diameter of 10 to 500 nm prepared by a suspension polymerization method or an emulsion polymerization method.
The resin particles were salted out / fused to form secondary particles, and then an organic solvent, a coagulant, a polymerization catalyst and the like were added to carry out polymerization, and the solution having a polymerization rate of 80% was heated. It can be produced by circulating a pressurized bottleneck in the state to flatten the particle shape and further adding a polymerization catalyst to complete the polymerization.

The salting out / fusion refers to salting out the resin fine particles produced in the polymerization step with a coagulant, removing excess dispersant, surfactant and the like, and simultaneously reducing the size of the resin particles by heat fusion. Adjusting.

The flattening treatment may be performed after 100% of the polymerization is completed. However, it is more preferable to perform the flattening in a state where the polymerization has progressed to 80% because the shape becomes uniform.

The number average primary particles are a light scattering electrophoresis particle size analyzer "ELS-800" (manufactured by Otsuka Electronics Co., Ltd.).
Can be measured.

The volume average particle size is measured by Coulter Counter TA
-2 or Coulter Multisizer (manufactured by Coulter Inc.).

The salting-out / fusion is carried out by mixing the resin particles with a dispersion liquid such as a release agent or a colorant necessary for forming the toner, or by using a toner composition such as a release agent or a colorant in a monomer. Number average primary particle size 1 prepared by a method such as emulsion polymerization after dispersing the components
It can be carried out by salting out / fusing resin particles of 0 to 500 nm.

That is, a coloring agent and, if necessary, various components such as a release agent, a charge control agent, and a polymerization initiator are added to the polymerizable monomer, and a homogenizer, a sand mill, a sand grinder, and an ultrasonic disperser are added. Various constituent materials are dissolved or dispersed in the polymerizable monomer by a machine or the like. The liquid in which the various constituent materials are dissolved or dispersed is dispersed in an oil medium having a desired size as a toner in an aqueous medium containing a dispersion stabilizer using a homomixer or a homogenizer. afterwards,
The mixture is transferred to a reactor equipped with a stirring mechanism having stirring blades, and heated so that the polymerization reaction proceeds to 80%. Then, circulate the pressurized bottleneck in the heated state to flatten the shape,
Further, a polymerization catalyst is added to proceed with the polymerization to complete the polymerization. After the polymerization is completed, the dispersion stabilizer is removed, filtered, washed,
By further drying, the flat toner of the present invention can be manufactured.

FIG. 3 is a perspective view showing an example of a stirring tank provided with stirring blades. In FIG. 3, a vertical cylindrical stirring tank 4 having a heat exchange jacket 401 mounted on the outer periphery of the stirring tank.
02, a rotating shaft 403 is provided vertically at the center of the rotating shaft 40.
3 includes a lower stirring blade 404 disposed close to the bottom surface of the stirring tank 402 and a stirring blade 405 disposed in an upper stage. The upper-stage stirring blade 405 is provided with the lower-stage stirring blade 4.
04 with a crossing angle α preceding the rotation direction. Preferably, the intersection angle α is less than 90 degrees. The lower limit of the intersection angle is not particularly limited, but may be 5 degrees or more, preferably 10 degrees or more.

Examples of the polymerizable monomer constituting the resin include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-chlorostyrene, 4-dichlorostyrene, p-phenylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, p-tert-butylstyrene, pn-hexylstyrene, pn-octylstyrene, pn-nonylstyrene, Styrene such as pn-decylstyrene, pn-dodecylstyrene, styrene derivatives, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isopropyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, methacrylic acid n-octyl, 2-ethylhexyl methacrylate, methacrylic acid Stearyl, lauryl methacrylate, phenyl methacrylate, diethylaminoethyl methacrylate, methacrylic acid ester derivatives such as dimethylaminoethyl methacrylate, methyl acrylate, ethyl acrylate, isopropyl acrylate, n
-Butyl, t-butyl acrylate, isobutyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, lauryl acrylate,
Acrylate derivatives such as phenyl acrylate,
Ethylene, propylene, olefins such as isobutylene, vinyl chloride, vinylidene chloride, vinyl bromide, vinyl fluoride, halogenated vinyls such as vinylidene fluoride, vinyl propionate, vinyl acetate, vinyl esters such as vinyl benzoate, Vinyl ethers such as vinyl methyl ether and vinyl ethyl ether; vinyl ketones such as vinyl methyl ketone, vinyl ethyl ketone and vinyl hexyl ketone; N-vinyl compounds such as N-vinyl carbazole, N-vinyl indole and N-vinyl pyrrolidone; vinyl Examples include vinyl compounds such as naphthalene and vinyl pyridine, and acrylic acid or methacrylic acid derivatives such as acrylonitrile, methacrylonitrile, and acrylamide. Among them, vinyl monomers can be used alone or in combination.

Further, it is more preferable to use a polymerizable monomer constituting the resin in combination with one having an ionic dissociating group. For example, those having a substituent such as a carboxyl group, a sulfonic acid group, and a phosphoric acid group as a constituent group of a monomer, specifically, acrylic acid, methacrylic acid, maleic acid, itaconic acid, cinnamic acid, and fumaric acid. Acid, maleic acid monoalkyl ester, itaconic acid monoalkyl ester, styrenesulfonic acid, allylsulfosuccinic acid, 2-acrylamido-2-methylpropanesulfonic acid, acid phosphooxyethyl methacrylate, 3
-Chloro-2-acid phosphooxypropyl methacrylate and the like.

Further, divinylbenzene, ethylene glycol dimethacrylate, ethylene glycol diacrylate, diethylene glycol dimethacrylate, diethylene glycol diacrylate, triethylene glycol dimethacrylate, triethylene glycol diacrylate, neopentyl glycol dimethacrylate,
Polyfunctional vinyls such as neopentyl glycol diacrylate can be used to form a crosslinked resin.

These polymerizable monomers can be polymerized using a radical polymerization initiator. In this case, an oil-soluble polymerization initiator can be used in the suspension polymerization method. As the oil-soluble polymerization initiator, 2,2'-azobis- (2,4
-Dimethylvaleronitrile), 2,2'-azobisisobutyronitrile, 1,1'-azobis (cyclohexane-1-carbonitrile), 2,2'-azobis-4-methoxy-2,4-dimethylvalero Azo or diazo polymerization initiators such as nitrile and azobisisobutyronitrile, benzoyl peroxide, methyl ethyl ketone peroxide, diisopropyl peroxycarbonate, cumene hydroperoxide, t-butyl hydroperoxide, di-t-butyl peroxide , Dicumyl peroxide, 2,4-dichlorobenzoyl peroxide, lauroyl peroxide, 2,2-bis-
Examples include peroxide-based polymerization initiators such as (4,4-t-butylperoxycyclohexyl) propane and tris- (t-butylperoxy) triazine, and polymer initiators having a peroxide in a side chain. .

When the emulsion polymerization method is used, a water-soluble radical polymerization initiator can be used. Examples of the water-soluble polymerization initiator include persulfates such as potassium persulfate and ammonium persulfate, azobisaminodipropane acetate, azobiscyanovaleric acid and salts thereof, and hydrogen peroxide.

Examples of the dispersion stabilizer include tricalcium phosphate, magnesium phosphate, zinc phosphate, aluminum phosphate, calcium carbonate, magnesium carbonate, calcium hydroxide, magnesium hydroxide, aluminum hydroxide, calcium metasilicate, and calcium sulfate. , Barium sulfate,
Bentonite, silica, alumina and the like can be mentioned. Further, those generally used as surfactants such as polyvinyl alcohol, gelatin, methyl cellulose, sodium dodecylbenzenesulfonate, ethylene oxide adduct, and higher alcohol sodium sulfate can be used as the dispersion stabilizer.

As the resin excellent in the present invention, a resin having a glass transition point of 20 to 90 ° C. is preferable, and a resin having a softening point of 8
The thing of 0-220 ° C is preferred. The glass transition point is measured by a differential calorimetric analysis method, and the softening point can be measured by a Koka type flow tester. Furthermore, these resins have a number average molecular weight (Mn) of 10 as measured by gel permeation chromatography.
00 to 100000, weight average molecular weight (Mw) 200
Those having 0 to 1,000,000 are preferred. Further, as a molecular weight distribution, Mw / Mn is 1.5 to 100, particularly 1.8.
-70 are preferred.

The flat toner of the present invention contains at least a resin and a colorant, but may contain a releasing agent or a charge control agent as a fixing property improving agent, if necessary. Further, an external additive composed of inorganic fine particles, organic fine particles and the like may be added to the flat toner particles mainly composed of the resin and the colorant.

As the colorant used in the flat toner of the present invention, carbon black, a magnetic substance, a dye, a pigment, and the like can be arbitrarily used.

As carbon black, channel black, furnace black, acetylene black, thermal black, lamp black and the like are used. Ferromagnetic metals such as iron, nickel, and cobalt, alloys containing these metals, ferrite, compounds of ferromagnetic metals such as magnetite, alloys that do not contain ferromagnetic metals but show ferromagnetism by heat treatment, For example, alloys of a type called a Heusler alloy such as manganese-copper-aluminum and manganese-copper-tin, chromium dioxide, and the like can be used.

As the dye, C.I. I. Solvent Red 1, 49, 52, 58, 63, 111, 1
22, C.I. I. Solvent Yellow 19, 44, 7
7, 79, 81, 82, 93, 98, 10
3, 104, 112, 162, C.I. I. Solvent Blue 25, 36, 60, 70, 93, 9
5 and the like, and a mixture thereof can also be used. Examples of the pigment include C.I. I. Pigment Red 5, 48: 1, 53: 1, 57: 1, 122,
139, 144, 149, 166, 177,
178, 222, C.I. I. Pigment Orange 3
1, 43, C.I. I. Pigment Yellow 14, 1
7, 93, 94, 138, C.I. I. Pigment Green 7, C.I. I. Pigment Blue 15: 3, 60
Etc. can be used. The above dyes and pigments can be used alone or as a mixture. Although the number average primary particle size of the colorant varies depending on the type, it is generally 10 to 200 nm.
Is preferred.

As a method of adding the colorant, a method of adding the colorant at the stage of polymerizing the monomer and polymerizing it to obtain colored particles can be used. When the colorant is added at the stage of preparing the polymer, it is preferable to use the colorant after treating the surface with a coupling agent or the like so as not to inhibit the radical polymerizability.

Further, low molecular weight polypropylene (number average molecular weight = 1500 to 9000), low molecular weight polyethylene or the like may be added as a fixing property improving agent.

The charge control agents are also various known ones.
In addition, those that can be dispersed in water can be used. Specifically, nigrosine dyes, metal salts of naphthenic acid or higher fatty acids, alkoxylated amines,
Quaternary ammonium salt compounds, azo-based metal complexes, salicylic acid metal salts or metal complexes thereof.

The particles of the charge control agent and the fixability improving agent have a number average primary particle diameter of 10 to 500 in a dispersed state.
It is preferable to set it to about nm.

In the flat toner of the present invention, more effects can be exhibited by adding and using fine particles such as inorganic fine particles and organic fine particles as an external additive. It is presumed that the reason for this is that since the burying and desorption of the external additive can be effectively suppressed, the effect is remarkable.

As the inorganic fine particles, inorganic oxide particles such as silica, titania and alumina are preferably used.
Further, it is preferable that these inorganic fine particles have been subjected to a hydrophobic treatment with a silane coupling agent, a titanium coupling agent, or the like. The degree of the hydrophobic treatment is not particularly limited, but a methanol wettability of 40 to 95 is preferable. Methanol wettability is to evaluate the wettability to methanol. In this method, 0.2 g of the inorganic fine particles to be measured is weighed and added to 50 ml of distilled water placed in a 200 ml beaker. Methanol is slowly dropped from a buret whose tip is immersed in the liquid until the whole of the inorganic fine particles is wet while being slowly stirred. When the amount of methanol required to completely wet the inorganic fine particles is a (ml), the degree of hydrophobicity is calculated by the following equation.

Degree of hydrophobicity = (a / (a + 50)) × 100 The amount of the external additive to be added is 0.1 to 0.1 in the flat toner.
5.0 mass% is preferred, and more preferably 0.5-4.
0% by mass. Various external additives may be used in combination.

The flattening of the salted-out / fused secondary particles can be carried out by an annular type continuous wet stirring mill, a piston type high-pressure homogenizer, an in-line screw pump or the like.

FIG. 4 is a sectional view of an essential part showing an example of an annular type continuous wet stirring mill. An annular type continuous wet stirring mill is a kind of a known mill. A rotor 502 having substantially the same shape rotates in an annular (annular) stator 501 having a triangular cross section.
Gap between the rotor and the rotor 502, that is, the crush zone 5
03 is filled with a medium 504, and a solution containing secondary particles, which has been polymerized to 80% and supplied to the mill, is given a mechanical impact to flatten the shape of the secondary particles. The solution passes through the crushing zone 503 having a W-shaped cross section by a pump from a supply port 505 of the mill, is separated from a medium 504 by an upper cap separator 506, and is discharged from an outlet 507. The temperature of the solution during the flattening process is controlled by circulating hot water 508 through the stator and the rotor. The media 504 sequentially moves through the W-shaped pulverizing zone due to centrifugal force, and returns to the entrance and circulates again. Pressure on the particles is applied by the walls or media of the grinding zone by circulating through a pressurized bottleneck. As the medium, zircon, glass, steel or the like having a diameter of 0.5 to 3 mm is usually used.

The flattening temperature of the solution containing the secondary particles using such an annular continuous wet stirring mill is preferably −5 ° C. to + 40 ° C., and 0 ° C., of the glass transition point (Tg) of the resin of the secondary particles. To + 30 ° C, more preferably +10 to + 30 ° C. 5 than the glass transition point
If the treatment is performed at a temperature lower than or equal to ° C., the polymer particles are crushed, and it is difficult to perform the intended flattening, which is not preferable. On the other hand, when the treatment is performed at a temperature higher than the glass transition point by 40 ° C. or more, the secondary particles fuse with each other to form agglomerates, and the flattened polymer particles are again spheroidized by their surface tension. Therefore, flattening cannot be performed efficiently, which is not preferable.

In the image forming method using the flat toner according to the present invention, an electrostatic latent image is formed on a photosensitive member having a photosensitive layer on a conductive support, and the electrostatic latent image is developed with the flat toner. It is preferable to use an image forming apparatus that forms a toner image by developing with a developer, transfers the toner image to a transfer material, and heat-fixes the toner image.

FIG. 5 is a schematic view showing an example of the image forming method of the present invention. In FIG. 5, reference numeral 10 denotes a photoreceptor drum (photoreceptor) serving as an image forming body, which is a photoreceptor in which an organic photosensitive layer is applied on a drum (conductive support) and a resin layer of the present invention is applied thereon. , And is driven and rotated clockwise. 12
Reference numeral denotes a scorotron charger, which applies uniform charging to the peripheral surface of the photosensitive drum 10 by corona discharge. Prior to the charging by the charger 12, in order to eliminate the history of the photoconductor in the previous image formation, exposure by the exposure unit 11 using a light emitting diode or the like may be performed to remove electricity from the peripheral surface of the photoconductor.

After the photosensitive member is uniformly charged, the image exposure unit 13 performs image exposure based on the image signal. The image exposure device 13 in this figure uses a laser diode (not shown) as an exposure light source. The light on the photosensitive drum is scanned by the light whose optical path is bent by the reflection mirror 132 through the rotating polygon mirror 131, the fθ lens, and the like, and an electrostatic latent image is formed.

The electrostatic latent image is then developed by the developing device 14. A developing device 1 in which a developer containing a flat toner such as yellow (Y), magenta (M), cyan (C), and black (K) and a carrier is provided at the periphery of the photosensitive drum 10.
First, development of the first color is performed by a developing sleeve 141 which rotates with a built-in magnet and holding a developer. The developer is regulated to a layer thickness of 100 to 600 μm on the developing sleeve 141 by a layer thickness forming means (not shown), and is conveyed to a development area to be developed. At this time, usually, the photosensitive drum 10 and the developing sleeve 14
The development is performed by applying a DC and / or AC bias voltage during the period of 1.

In the color image forming method, after the visualization of the first color is completed, the image forming process of the second color is started, the uniform charging is performed again by the scorotron charger 12, and the latent image of the second color is changed to the image exposing device. 13. An image forming process similar to that for the second color is performed for the third color and the fourth color, and a visible image of four colors is formed on the peripheral surface of the photosensitive drum 10.

On the other hand, in a monochrome electrophotographic apparatus, the developing device 1
Reference numeral 4 denotes one kind of flat black toner, and an image can be formed by one development.

After the image is formed, the recording paper P is fed to the transfer area by the rotation of the paper feed roller 17 at the time when the transfer timing is adjusted.

In the transfer area, a transfer roller (transfer device) 1 is mounted on the peripheral surface of the photosensitive drum 10 in synchronization with the transfer timing.
8, the multicolor image is transferred collectively by sandwiching the fed recording paper P.

Next, the recording paper P is neutralized by a separation brush (separator) 19 brought into pressure contact with the transfer roller almost at the same time, separated by the peripheral surface of the photosensitive drum 10 and conveyed to a fixing device 20, where the heat roller 201 and pressure roller 2
After the flat toner is welded by heating and pressurizing of No. 02, the toner is discharged to the outside of the apparatus via the discharge roller 21. The transfer roller 18 and the separation brush 19 are retracted from the peripheral surface of the photosensitive drum 10 after passing the recording paper P to prepare for the formation of the next toner image.

On the other hand, the photosensitive drum 10 from which the recording paper P has been separated removes and cleans the residual toner by pressing the blade 221 of the cleaning device 22 and receives the charge removal by the exposure unit 11 and the charge by the charger 12 again. The next image forming process is started. When a color image is formed on the photoconductor by superimposition, the blade 221 moves immediately after cleaning the photoconductor surface and retreats from the peripheral surface of the photoconductor drum 10.

Reference numeral 30 denotes a detachable process cartridge in which a photosensitive member, a charger, a transfer device, a separator, and a cleaning device are integrated.

An electrophotographic image forming apparatus is constructed by integrally combining the above-described photoreceptor, a developing device, a cleaning device, and other components as a process cartridge, and this unit is configured to be detachable from the apparatus main body. You may.
In addition, a process cartridge is formed by integrally supporting at least one of a charger, an image exposing unit, a developing unit, a transfer or separating unit, and a cleaning unit together with a photoreceptor. It may be configured to be detachable using guide means such as a rail of the main body.

The Konica 9028 used in the embodiment is an image forming apparatus having a similar configuration. In addition, an image forming apparatus that forms a toner image on an image forming body, sequentially transfers the toner images onto a transfer body (paper or an intermediate transfer body), and superimposes them to form a color toner image can also be used.

In the image exposure, when an image forming apparatus is used as a copying machine, an original is read by a sensor and converted into a signal.
Scanning of a laser beam, driving of an LED array or driving of a liquid crystal shutter array is performed in accordance with this signal to irradiate light to a photoconductor, or the like.

When used as a printer,
The image exposure is an exposure for printing received data.

[0071]

EXAMPLES The present invention will be described specifically with reference to Examples.
Embodiments of the present invention are not limited to these.

<< Production of Flat Toner >> (Toner Production Example 1: Black Flat Toner 1) 0.90 kg of sodium n-dodecyl sulfate and 10.0 l of pure water are added and stirred and dissolved. 1.20 kg of Regal 330R (carbon black manufactured by Cabot Corporation) was gradually added to this solution, and the mixture was stirred well for 1 hour, and then continuously dispersed for 20 hours using a sand grinder (medium type disperser). This is referred to as “colorant dispersion liquid 1”. A solution consisting of 0.055 kg of sodium dodecylbenzenesulfonate and 4.0 l of ion-exchanged water was referred to as “anionic surfactant solution A”.
And

Nonylphenol polyethylene oxide 10 mol adduct 0.014 kg and ion exchanged water 4.0 l
Is referred to as “nonionic surfactant solution B”.
223.8 g of potassium persulfate was added to 12.0 l of ion-exchanged water.
Is referred to as "initiator solution C".

A 100-liter glass-lined (GL) reactor equipped with a temperature sensor, a cooling pipe, and a nitrogen introducing device was charged with W.
3.41 kg of AX emulsion (polypropylene emulsion having a number average molecular weight of 3000: number average primary particle size = 120 nm / solid content = 29.9%), the total amount of “anionic surfactant solution A” and “nonionic surfactant solution B” "
Add the whole amount and start stirring. The shape of the stirring blade was configured as shown in FIG. Next, 44.0 l of ion-exchanged water was added.

Next, heating was started, and when the liquid temperature reached 75 ° C., the entire amount of “initiator solution C” was added dropwise. Thereafter, while controlling the liquid temperature to 75 ° C. ± 1 ° C., 12.1 kg of styrene and 2.88 k of n-butyl acrylate
g, 1.04 kg of methacrylic acid and 548 g of t-dodecylmercaptan were added dropwise. After the completion of the dropwise addition, the temperature of the solution was raised to 80 ° C. ± 1 ° C., and the mixture was heated and stirred for 6 hours. Next, the liquid temperature was cooled to 40 ° C. or lower, stirring was stopped, and the mixture was filtered with a pole filter, and this was designated as “latex 1-A”.

The resin particles in latex 1-A had a glass transition point of 57 ° C., a softening point of 121 ° C., a weight average molecular weight of 127,000 and a weight average particle size of 120 nm.

A solution obtained by dissolving 0.055 kg of sodium dodecylbenzenesulfonate in 4.0 l of ion-exchanged pure water is referred to as “anionic surfactant solution D”. Further, a solution obtained by dissolving 0.014 kg of a 10 mol adduct of nonylphenol polyethylene oxide in 4.0 l of ion-exchanged water is referred to as “nonionic surfactant solution E”.

Potassium persulfate (Kanto Chemical Co., Ltd.) 2
A solution obtained by dissolving 00.7 g in 12.0 l of ion-exchanged water is referred to as “initiator solution F”.

A WAX emulsion (polypropylene emulsion having a number average molecular weight of 3,000: number average primary particle diameter: 120 nm / solid content = 29) was placed in a 100-liter GL reactor equipped with a temperature sensor, a cooling pipe, a nitrogen introducing device, and a comb baffle. 4.9%), 3.41 kg, the whole amount of “anionic surfactant solution D” and the whole amount of “nonionic surfactant solution E” are added, and stirring is started. Then, ion-exchanged water 44.0
1 is input. Heating is started, and when the liquid temperature reaches 70 ° C., “Initiator solution F” is added. Then, 11.0 kg of styrene and 4.00 k of n-butyl acrylate
g, 1.04 kg of methacrylic acid and 9.02 g of t-dodecylmercaptan are added dropwise. After completion of the dropwise addition, the mixture was heated and stirred for 6 hours while controlling the liquid temperature at 72 ° C. ± 2 ° C. Next, the liquid temperature was raised to 80 ° C. ± 2 ° C., and the mixture was heated and stirred for 12 hours. Next, when the liquid temperature is 40
The mixture was cooled to a temperature of not more than 0 ° C., the stirring was stopped, and the mixture was filtered through a Pall filter, which was designated as “latex 1-B”.

The resin particles in the latex 1-B had a glass transition point of 58 ° C., a softening point of 132 ° C., a weight average molecular weight of 245,000 and a weight average particle size of 110 nm.

5.36 kg of sodium chloride as salting-out agent
Is dissolved in 20.0 l of ion-exchanged water, and is referred to as "sodium chloride solution G".

A solution obtained by dissolving 1.00 g of a fluorinated nonionic surfactant in 1.00 l of ion-exchanged water is referred to as "nonionic surfactant solution H".

100 l of S with temperature sensor, cooling tube, nitrogen introduction device, particle size and shape monitoring device
In the US reactor, “Latex 1-A” prepared above =
20.0 kg, “Latex 1-B” = 5.2 kg,
“Colorant dispersion 1” = 0.4 kg and ion-exchanged water 2
Add 0.0kg and stir. Then, warm to 40 ° C,
“Sodium chloride solution G”, 6.00 kg of isopropanol (manufactured by Kanto Chemical Co., Ltd.) and “Nonionic surfactant solution H” were added in this order. Thereafter, after standing for 10 minutes, the temperature was raised, the temperature was raised to a liquid temperature of 85 ° C. in 60 minutes, and the mixture was heated and stirred at 85 ± 2 ° C. for 0.5 to 3 hours.
The grain size was grown while fusing. Next, 2.1 l of pure water was added to stop the particle size growth. This liquid is referred to as “fused particle dispersion liquid”.

Next, a temperature sensor and a cooling pipe were attached.
Into a 1 l reaction vessel, 5.0 kg of the above-mentioned fused particle dispersion is placed, and the mixture is heated and stirred at a liquid temperature of 85 ° C. ± 2 ° C. for 4 hours. It was continuously supplied to a mold continuous wet stirring mill (manufactured by Shinko Pantents Co., Ltd.), and flattened under the conditions of a temperature of 67 ° C., a rotor peripheral speed of 13 m / min, and an average residence time of 15 minutes. Then
The flattened solution was returned to the reaction vessel, 0.03 kg of sodium dodecylbenzenesulfonate was added, and the mixture was heated and stirred at a liquid temperature of 85 ° C. ± 2 ° C. for 4 hours to complete the polymerization. Thereafter, the mixture was cooled to 40 ° C. or lower and the stirring was stopped. Next, classification is performed in the liquid by a centrifugal sedimentation method using a centrifugal separator, and the classified product is filtered with a sieve having an opening of 45 μm, and this filtrate is referred to as “association liquid 1”. Next, the wet liquid black flat particles 1 were obtained from the association liquid 1 using a nutche.
Was collected by filtration. Thereafter, the substrate was washed with ion-exchanged water.

This “wet cake-like black flat particles 1”
Using a flash jet dryer
After preliminary drying at a temperature of 60 ° C., drying was performed at a temperature of 60 ° C. using a fluidized-bed dryer to obtain “black flat particles 1”.

The obtained “flat black toner 1” was externally mixed with 1% by mass of hydrophobized silica fine particles using a Henschel mixer to obtain “flat black toner 1”.

(Toner Production Example 2: Black Flat Toner 2) The conditions of the annular continuous wet stirring mill of Toner Production Example 1 were as follows: temperature 70 ° C., rotor peripheral speed 20 m / min, average residence time 15
"Black Flat Toner 2" was obtained in the same manner except for the above.

(Toner Production Example 3: Flat Yellow Toner)
In toner production example 1, C.I. I. Pigment Yellow 17 1.05k
"yellow flat toner" was obtained in the same manner except that g was used.

(Toner Production Example 4: Magenta Flat Toner)
In toner production example 1, C.I. I. Pigment Red 122 1.20k
g magenta flat toner was obtained in the same manner except that g was used.

(Toner Production Example 5: Cyan flat toner) In Toner Production Example 1, C.I. I. Pigment Blue 15: 3 0.60k
"Cyan flat toner" was obtained in the same manner except that g was used.

Table 1 shows the glass transition point and the flattening conditions of Toner Production Examples 1 to 5.

[0092]

[Table 1]

(Toner Production Example 6: Black Amorphous Toner) “Black amorphous toner” was produced in the same manner as in Toner Production Example 1 except that the polymerization was completed without passing through the annular continuous wet stirring mill of Toner Production Example 1. Obtained.

(Toner Production Example 7: Yellow Amorphous Toner) A “yellow amorphous toner” was produced in the same manner as in Toner Production Example 3 except that the polymerization was completed without passing through the annular continuous wet stirring mill of Toner Production Example 3. Obtained.

(Toner Production Example 8: Magenta Amorphous Toner) A “magenta irregular toner” was produced in the same manner as in Toner Production Example 4 except that the polymerization was completed without passing through an annular continuous wet stirring mill of Toner Production Example 4. Obtained.

(Toner Production Example 9: Cyan amorphous toner)
"Cyan amorphous toner" was obtained in the same manner as in Toner Production Example 5, except that the polymerization was completed without passing through the annular continuous wet stirring mill of Toner Production Example 5.

(Toner Production Example 10: Black Uneven Toner) 100 kg of styrene-n-butyl acrylate copolymer resin,
The toner raw materials consisting of 10 kg of carbon black and 4 kg of polypropylene are premixed by a Henschel mixer, melt-kneaded by a twin-screw extruder, coarsely ground by a hammer mill, and ground by a jet mill to obtain ground black particles. Obtained. The pulverized black particles were repeatedly classified by an air classifier until the target particle size distribution was obtained, thereby obtaining “black particles”.

The obtained "black particles" were externally added and mixed with 1% by mass of hydrophobized silica fine particles using a Henschel mixer to obtain "black toner" by a pulverization method. Note that, unlike the toner obtained by the polymerization method, the toner was an irregular toner having irregularities on the surface.

<< Evaluation >> (Shape and Particle Size of Flat Toner) The average length (r ₁ and r ₂ ) of the flat toner particles is determined by uniformly dispersing and attaching the flat toner particles to a smooth surface, and the surface is viewed from above by a microscope. The maximum length (long side) and the minimum length (short side) of 100 flat toner particles are measured, and their arithmetic average values are defined as “r ₁ ” and “r ₂ ”.

The thickness (d) of the flat toner particles is determined by uniformly dispersing the flat toner particles on a smooth surface and enlarging the surface by 1000 times with a microscope from the upper surface.
The maximum height is measured for each piece, and the arithmetic average value is "d"
And

The volume average particle diameter of the flat toner is measured with a Coulter Counter TA-2 or Coulter Multisizer (manufactured by Coulter KK). In the present invention, a Coulter Multisizer was used, and an interface for outputting a particle size distribution (manufactured by Nikkagi) and a personal computer were connected. The aperture used in the Coulter Multisizer is 100 μm
Is used to measure the volume distribution of the flat toner of 2 μm or more and calculate the volume average particle diameter.

Table 2 shows the shapes and volume average particle diameters of Toner Production Examples 1 to 10.

[0103]

[Table 2]

(Preparation of Developer) Each of the toners of Toner Production Examples 1 to 10 and a 65 μm ferrite carrier coated with a silicone resin were mixed with toner / carrier = 50 g / 950.
g at a ratio of "g" to prepare "Developers 1 to 10" for evaluation.

(Image creation) Copiers are Konica, KL
9028 (a color printer manufactured by Konica Corporation) was used. Using a developer of 1 to 10 and a toner of Production Examples 1 to 10, a single-color image and a full-color image of an A-4 size color original (print rate 25%) are printed, and “evaluation images 1 to 5”
It was created.

(Evaluation of Toner Adhesion State on Image Forming Body) The state in which a toner image was formed on the image forming body of a copying machine was observed with a microscope to evaluate the toner adhesion state.

Table 3 shows the evaluation results of the toner adhesion state on the image forming body.

[0108]

[Table 3]

When the state of adhesion of the toner on the image forming body was confirmed, when the toners of the toner production examples 1 to 5 were used, the toner adhered to the image forming body with a flat surface.
On the other hand, when the toners of Toner Production Examples 6 to 10 which are not flat were used, the toner was attached to the image forming body in various directions.

(Evaluation of Image Quality) The toner consumption, image density and toner scattering of the obtained image were evaluated.

[0111] The toner consumption is as follows: 100 sheets of A-4 size white paper image (corresponding to 0% printing rate) and 100 sheets of A-4 size color original (25% printing rate). From the difference in mass of the transfer paper thus obtained, it was obtained by converting the amount of toner consumption per A-4 plate.

The image density was measured using an RD-918 densitometer (manufactured by Macbeth Co., Ltd.).

The toner scattering was determined by visually observing the toner scattering on the printed image. Table 4 shows the results of evaluation of toner consumption, image density, and toner scattering.

[0114]

[Table 4]

The flat toner of the present invention has a preferable result because it consumes a small amount of toner, has a small amount of toner scattering, and can obtain a high-density image.

[0116]

As demonstrated in the examples, the flat toner according to the present invention, the method for producing the flat toner, and the image forming method using the flat toner can provide a high-density image even if the toner consumption is small. And has an excellent effect of obtaining a high quality image with little unevenness and no toner scattering.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating an example of a flat toner according to the present invention.

FIG. 2 is a schematic diagram illustrating an example of flat toner adhered on an image forming body.

FIG. 3 is a perspective view showing an example of a stirring tank provided with stirring blades.

FIG. 4 is a sectional view of a main part showing an example of an annular type continuous wet stirring mill.

FIG. 5 is a schematic view showing an example of the image forming method of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Photoconductor drum (photoconductor) 11 Exposure part using light emitting diode etc. 12 Charging device 13 Image exposure device 14 Developing device 17 Paper feed roller 18 Transfer roller (transfer device) 19 Separation brush (separator) 20 Fixing device 21 Discharge Paper roller 22 Cleaning device 30 Process cartridge

Claims (5)

[Claims] 1. A toner obtained by salting out / fusing resin particles having a number average primary particle diameter of 10 to 500 nm to produce secondary particles, and subjecting the secondary particles to a flattening treatment to form a toner. Flat toner characterized by being flat. 2. The shape of the flat toner has a long side (r ₁ ) and a short side (r ₂ ) of an average length of 5 to 20 μm and an average thickness (d).
Is 1 to 5 μm, the ratio of the short side to the long side of the average length (r ₂ / r ₁ ) is 0.6 to 1.0, and the ratio of the average thickness of the flat toner to the average short side length (d / r ₂ ) is The flat toner according to claim 1, wherein the ratio is 0.1 to 0.4. 3. The flat toner according to claim 1 or 2,
A method for producing a flat toner, comprising circulating a pressurized bottleneck in a heated state to flatten the particle shape and producing the toner. 4. The adhesion state of the flat toner on the image forming body is as follows.
An image forming method, wherein a flat portion of flat toner adheres to an image forming body. 5. An image forming method in which a flat portion of flat toner adheres to an image forming body, wherein the flat toner according to claim 1 or 2 is used.