JP2000194156A - Developer and image forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide developer capable of stably and satisfactorily electrifying toner for a long time, and also, capable of obtaining the high stability of the developing density without sacrificing the flowability and the transfer property, as to toner whose average particle size is small, and also, to provide an image forming method capable of forming an image of high quality for a long period. SOLUTION: The developer is constituted of the toner and carrier, the toner is constituted by adding inorganic fine particles at a specified ratio to color particles containing binding resin and coloring agent, and having the volume average particle size of 3 to 10 μm, and the carrier is constituted by adding covering resin layer dispersed fine particles with a specified numerical average primary particle size into the covering resin layer formed on the surface of a core particle at a specified ratio. As to the image forming method, a latent image formed on an image forming body is developed by carrying the developer layer formed of the developer and formed on a developer carrying/holding body to a developing area in non-contact with the image forming body.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a developer and an image forming method.

[0002]

2. Description of the Related Art Conventionally, in the field of toner for developing electrostatic latent images, the size of toner particles has been reduced for the purpose of forming high-quality images or color images. As the surface area of the toner per unit volume increases as the particle size decreases, the amount of inorganic fine particles added as an external additive to the toner to ensure good fluidity, developability and transferability needs to be increased. There is.

However, when the amount of the inorganic fine particles is increased, the inorganic fine particles do not adhere to the surface of the colored particles for toner.
So-called inorganic fine particles in a free state (hereinafter, also referred to as "free inorganic fine particles") are generated. Then, the free inorganic fine particles adhere to the surface of the carrier, which is a charging member of the toner. As a result, good triboelectric charging of the toner is inhibited. Is low.

[0004] In particular, the developer layer formed on the developer carrying carrier is transported to the developing area in a state where the developer layer is not in contact with the image forming body on which the latent image has been formed. In the image forming method for developing the above latent image, since no external force is applied to the developer layer in the development area, the stress applied to the toner particles and the carrier particles is small, and the surface of the particles is inorganic. Fine particles are hardly buried, and as a result, free inorganic fine particles are easily generated.

On the other hand, as an example of an electrophotographic carrier constituting a developer together with a toner, a carrier having a coating resin layer on the surface of core material particles, wherein the coating resin layer contains fine particles of titanium dioxide. JP-A-2-435
No. 66 is proposed. However, in this carrier, since the titanium dioxide fine particles do not have a sufficiently high charge providing ability, a sufficient charge amount cannot be obtained for the toner.

[0006]

DISCLOSURE OF THE INVENTION The present invention has been made based on the above circumstances, and its object is to provide:
Consisting of a toner having a small average particle diameter and a resin-coated carrier, it is possible to stably obtain a sufficiently high charge amount for a long period of time without sacrificing fluidity and transferability, An object of the present invention is to provide a developer capable of obtaining stable development density. Another object of the present invention is to provide an image forming method capable of forming a high-quality image for a long period of time.

[0007]

The developer of the present invention comprises a binder resin and a colorant, and has a volume average particle diameter of 3%.
Inorganic microparticles are added to colored particles having a particle size of 1.0 to 10 μm.
In the toner added at a ratio of 0% by weight and the coating resin layer formed on the surface of the core particles, fine particles of aluminum oxide having a number-average primary particle diameter of 5 to 1000 nm are contained in 0.5 to 5. And a carrier added at a ratio of 0% by weight.

[0008] Another developer of the present invention is a colored particle having a volume average particle diameter of 3 to 10 µm containing a binder resin and a colorant, and containing inorganic fine particles of 1.0 to 10.0% by weight. The number average primary particle diameter is 5 to 1000 in the toner added in the ratio and the coating resin layer formed on the surface of the core material particles.
fine particles of zirconium oxide having a thickness of 1.0 to 1 nm.
And a carrier added at a ratio of 0.0% by weight.

Still another developer according to the present invention comprises a binder resin and a colorant, and has a volume average particle diameter of 3 to 10 μm.
m to 1.0% by weight of inorganic particles in the colored particles
And the coating resin layer formed on the surface of the core material particles has a number average primary particle diameter of 10 to 1
It is characterized by comprising a carrier to which fine particles comprising a melamine-formaldehyde condensate of 000 nm are added at a ratio of 0.1 to 5.0% by weight.

According to the image forming method of the present invention, a developer layer formed of any one of the above-mentioned developers formed on a developer carrying carrier is placed in a developing area in a state where the developer layer is in non-contact with the image forming body. By transporting, the latent image on the image forming body is developed.

[0011]

According to the above-mentioned developer, since the volume average particle diameter of the colored particles for toner is 3 to 10 μm, a high-resolution visible image can be basically obtained.

[0012] In the toner, the coloring particles contain inorganic fine particles of 1.0.
By being added at a rate of ~ 10.0% by weight,
In the image forming process, good fluidity is obtained, and good transferability is obtained.

The carrier used together with the above-mentioned toner has a coating resin layer on the surface of core material particles, and specific fine particles (hereinafter referred to as “coated resin layer dispersed fine particles”) in the coating resin layer.
Also called. ) Is added at a specific ratio, whereby a sufficiently high charge amount can be obtained for the toner.

In the case where the fine particles dispersed in the coating resin layer are fine particles made of aluminum oxide, since the number average primary particle diameter is 5 to 1000 nm, the carrier has good polishing characteristics on the surface of the image forming body. Becomes

The fine particles made of aluminum oxide are:
Since it is harder than the resin forming the coating resin layer and is not deformed, it is added at a ratio of 0.5 to 5.0% by weight with respect to the core particles, so that free inorganic which is an external additive of the toner is used. The fine particles are less likely to be buried in the surface of the carrier, so that in the image forming process, the toner has good charging characteristics, and a sufficiently high charge amount can be stably obtained over a long period of time.

When the coating resin layer-dispersed fine particles are fine particles made of zirconium oxide, the fine particles are harder than the resin forming the coating resin layer and are not deformed, so that the number average primary particle diameter is 5 to 1000 nm. And
When the addition ratio is 1.0 to 10.0% by weight with respect to the core material particles, the same effect as the above-described aluminum oxide fine particles can be obtained.

Further, the fine particles dispersed in the coating resin layer are melamine-
In the case of fine particles made of formaldehyde condensate, the fine particles are harder than the resin forming the coating resin layer and are not deformed.
nm, and the addition ratio is 0.1 to
When the content is 5.0% by weight, the same effect as that of the above-described aluminum oxide fine particles can be obtained.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. <Developer> According to the present invention, a so-called two-component developer is constituted by a specific small particle diameter toner and a specific resin-coated carrier.

[A] Toner The toner constituting the developer of the present invention is composed of colored particles for toner having a defined volume average particle diameter and inorganic fine particles added thereto as an external additive. . The colored particles contain a binder resin, a colorant, and optionally an internal additive.

The colored particles for toner have a volume average particle diameter defined in a specific range in a volume-based particle size distribution. Here, the “volume average particle diameter” of the colored particles for toner means that when a fixed number of colored particles are counted in order from a particle having a large particle diameter or a particle having a small particle diameter, the total number (cumulative value) is It refers to the particle diameter of the colored particles when the number of particles reaches 50%.

The range of the volume average particle size of the colored particles for toner is 3 to 10 μm, preferably 4 to 7 μm. According to the colored particles having a volume average particle diameter of 3 to 10 μm, in the image forming process, the obtained visible image can be made to have excellent fine line reproducibility and high resolution.

The colored particles for toner preferably have a coefficient of variation (hereinafter also referred to as "CV value") of 15 to 27, and more preferably 15 to 27, calculated by the following equation in the particle size distribution on a volume basis. Preferably, it is 22.

[0023]

(Equation 1)

In this specification, the volume average particle diameter and the CV in the volume-based particle size distribution of the colored particles for toner are referred to.
Each value is the particle size data of the sample measured by Coulter Multisizer according to the following conditions,
The value is transferred to a computer via an I / O unit and calculated by the computer using a particle size distribution analysis program.

[Measurement conditions] (i) Aperture diameter: 100 μm (ii) Sample preparation method for measurement: electrolytic solution [ISOTON
R-II (manufactured by Coulter Scientific Japan Co., Ltd.)] To 50 to 100 ml, add an appropriate amount of a surfactant (neutral detergent), stir, add colored particles 1 to be measured.
0 to 20 mg is added, and this mixed system is subjected to a dispersion treatment for 1 minute by an ultrasonic disperser to prepare a measurement sample.

The particle size distribution of the colored particles for the toner may be determined by adjusting the production conditions, for example, by adjusting the composition of the polymer constituting the binder resin, or when the colored particles are produced by a polymerization method described later. Further, it can be controlled by selecting or adjusting the type and amount of the organic solvent used in the method, the conditions for pulverization, and the conditions for classification.

Hereinafter, each component constituting the toner will be described. (1) Binder Resin The binder resin which is a component of the colored particles for the toner is not particularly limited, and specific examples thereof include various conventionally known resins such as a styrene resin, an acrylic resin, and styrene. / Acrylic resins, polyester resins and the like.

(2) Colorant The colorant is not particularly limited, and specific examples thereof include various known materials such as carbon black, aniline blue, calcoil blue, chrome yellow, ultramarine blue, Examples include Dupont oil red, quinoline yellow, methylene blue chloride, phthalocyanine blue, malachite green oxalate, rose bengal, magnetic substances, various dyes and pigments, and the like.

Here, examples of the carbon black used as a coloring agent include channel black, furnace black, acetylene black, thermal black, and the like.
Lamp black and the like.

Examples of the magnetic substance include ferromagnetic metals such as iron, nickel and cobalt; alloys containing these metals; ferromagnetic metal compounds such as ferrite and magnetite; Alloys such as manganese-copper-aluminum, manganese-copper-tin, and the like, and alloys of a type called a Heusler alloy, chromium dioxide, and the like.

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.

As the pigment, 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
And the like. These can be used alone or in combination of two or more.

(3) Internal Additives As internal additives, release agents, charge control agents and the like can be used.

As the release agent, those conventionally used, specifically, polyolefins such as low molecular weight polypropylene, low molecular weight polyethylene and ethylene-propylene copolymer, microcrystalline wax, carnauba wax, Waxes such as sol wax, paraffin wax and amide wax can be used. In order to secure a favorable image forming process, the addition ratio of the release agent is 1 to 5% by weight based on the colored particles.
It is preferred that

Examples of the charge control agent include azo metal complexes, salicylic acid metal complexes, and calixarene compounds as negative charge agents, and nigrosine dyes and quaternary ammonium salt compounds as positive charge agents. And the like.

(4) Inorganic Fine Particles The compounds constituting the inorganic fine particles externally added to the colored particles for the toner include various inorganic oxides, nitrides, borides, and the like. , Silica, aluminum oxide, zirconium oxide, titania, barium titanate, aluminum titanate, strontium titanate, magnesium titanate, zinc oxide,
Examples include chromium oxide, cerium oxide, antimony oxide, tungsten oxide, tin oxide, tellurium oxide, manganese oxide, boron oxide, silicon carbide, boron carbide, titanium carbide, silicon nitride, titanium nitride, and boron nitride.

The surface of these inorganic fine particles is preferably subjected to hydrophobic treatment with various kinds of coupling agents such as titanium coupling agents and silane coupling agents, silicone oil, fatty acids and fatty acid metal salts.

As the titanium coupling agent, tetrabutyl titanate, tetraoctyl titanate, isopropyl triisostearoyl titanate, isopropyl tridecylbenzenesulfonyl titanate, bis (dioctyl pyrophosphate) oxyacetate titanate and the like can be used.

As the silane coupling agent, γ- (2
-Aminoethyl) aminopropyltrimethoxysilane,
γ- (2-aminoethyl) aminopropylmethyldimethoxysilane, γ-methacryloxypropyltrimethoxysilane, N-β- (N-vinylbenzylaminoethyl)
γ-aminopropyltrimethoxysilane hydrochloride, hexamethyldisilazane, methyltrimethoxysilane, butyltrimethoxysilane, isobutyltrimethoxysilane,
Hexyltrimethoxysilane, octyltrimethoxysilane, decyltrimethoxysilane, dodecyltrimethoxysilane, phenyltrimethoxysilane, o-methylphenyltrimethoxysilane, p-methylphenyltrimethoxysilane, and the like can be used.

As the silicone oil, dimethyl silicone oil, methylphenyl silicone oil, amino-modified silicone oil and the like can be used.

Fatty acids include undecylic acid, lauric acid, tridecylic acid, dodecylic acid, myristic acid, palmitic acid, pentadecylic acid, stearic acid, heptadecylic acid, arachidic acid, montanic acid, oleic acid, linoleic acid, arachidonic acid and the like. Long chain fatty acids can be used.

As the fatty acid metal salt, salts of the above long-chain fatty acids with metals such as zinc, iron, magnesium, aluminum, calcium, sodium, lithium and the like can be used, and among these, aluminum stearate And higher fatty acid metal salts such as zinc stearate and calcium stearate.

The addition ratio of the compound for hydrophobizing treatment is preferably from 1 to 10% by weight, more preferably from 3 to 7% by weight, based on the inorganic fine particles. Further, these compounds for hydrophobizing treatment can be used in combination.

The number average primary particle diameter of the above inorganic fine particles is:
It is preferably from 5 to 500 nm, particularly from 5 to 100 nm.
It is preferably nm. Here, the “number average primary particle size” refers to a number average primary particle size that is observed by transmission electron microscope observation and measured by image analysis.

The addition ratio of the inorganic fine particles is from 1.0 to 10.0% by weight based on the toner, and preferably from 1.5 to 10.0% by weight.
It is 5.0% by weight. When the addition ratio of the inorganic fine particles is 1.0
When the amount is less than the weight%, the toner does not have good fluidity and good transferability cannot be obtained. On the other hand, when the addition ratio of the inorganic fine particles exceeds 10.0% by weight, a large amount of free inorganic fine particles is generated, which is not preferable.

(5) Production Method of Toner The toner can be produced by the following pulverization method or polymerization method, but is not limited thereto. The pulverization method is performed by melting and kneading a toner raw material composed of a binder resin, a colorant and an internal additive, performing a pulverization treatment and a classification treatment on the kneaded mixture, or repeating a pulverization treatment and a classification treatment as necessary. In this method, toner particles having a volume average particle diameter are obtained, and inorganic fine particles are added thereto to obtain a toner.

In the polymerization method, the toner material particles directly obtained by the polymerization treatment are subjected to a classification treatment or, if necessary, the classification treatment is repeated to produce colored particles for toner having a specific volume average particle diameter. In this method, a toner is obtained by adding inorganic fine particles to the resultant toner.

An example of the polymerization method includes, for example, an emulsion polymerization step of preparing resin fine particles by emulsion polymerization, and adding a dispersion in which colorant fine particles are dispersed to a dispersion in which the resin fine particles are dispersed, Thereafter, the system is subjected to a salting-out treatment, and a salting-out / fusing step of forming toner material particles by associatively fusing each fine particle, and washing the resultant toner material particles by filtering them out of water to remove a surfactant and the like. Process, a drying step of drying the obtained toner material particles, a classification process for the obtained toner material particles, or by repeating the classification process as needed, coloring for a toner having a specific volume average particle diameter This is a method of obtaining a toner through a classification step of forming particles, and an external additive addition step of adding an external additive containing inorganic fine particles to the toner coloring particles obtained in the classification step.

In the above example, the case where the toner is obtained by a specific method utilizing emulsion polymerization has been described. However, the polymerization method for obtaining the toner of the present invention is not limited to this, and other polymerization methods may be used. Legal can also be used.

Examples of an apparatus used for adding the inorganic fine particles to the colored particles for the toner include a Henschel mixer, an OM dither, a turbular mixer, a Lodige mixer, and a V-type mixer.

In the toner obtained as described above, the volume average particle diameter of the toner coloring particles constituting the toner is 3 to 3.
When the thickness is 10 μm, preferably 4 to 7 μm, in the image forming process, the obtained visible image can be made to have excellent fine line reproducibility and high resolution.

Further, the toner has a good fluidity in the image forming process and a good transfer property can be obtained by adding the inorganic fine particles at a specific ratio.

[B] Carrier The carrier constituting the developer of the present invention together with the above-mentioned toner is a resin coating comprising magnetic core particles and a coating resin layer formed on the surface of the core particles. It is a mold carrier.

(1) Core particles Particles of iron, magnetite or various ferrites, or dispersed magnetic particles obtained by dispersing magnetic particles in binder resin particles are used as core particles of the carrier. In particular, the dispersion type magnetic particles are preferable because the carrier itself can be reduced in weight and the stress acting on the toner can be reduced.

As a method for producing the dispersion type magnetic particles, a method in which magnetic particles and an insulating binder resin are melt-mixed, the resulting molten mixture is cooled, then finely pulverized and classified, and a suspension stabilizer is used. In an aqueous medium containing
There is a method of polymerizing a monomer that forms a binder resin in the presence of magnetic fine particles, for example, phenols and aldehydes with a basic catalyst to obtain spherical polymer particles, and drying this. Dispersion-type magnetic particles obtained by the latter method are preferable because the uniform dispersibility of the magnetic fine particles and the uniformity of the shape of the formed resin particles are preferable.

Here, as the magnetic fine particles, magnetobranbite type ferrites such as spinel ferrite or barium ferrite containing magnetite or gamma iron oxide, or fine particles of iron or an alloy thereof having an oxide layer on the surface are preferable.

The content ratio of the magnetic fine particles in the dispersed magnetic particles is preferably 80 to 99% by weight.
In particular, the content is preferably 80 to 97% by weight.

The particle diameter of the core particles is 5 to 100 μm, preferably 15 to 35 μm, as a number average primary particle diameter.

(2) Coating Resin Layer The resin forming the coating resin layer of the carrier is not particularly limited, and examples thereof include a silicone resin, a fluorine-containing acrylate resin, a styrene-acryl resin, and others. it can.

Here, as the styrene-acrylic resin, a copolymer of styrene or a styrene derivative and a methacrylate or acrylate or a derivative thereof can be exemplified.

Specific examples of the styrene derivative include o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-chlorostyrene, 3,4
-Dichlorostyrene, p-phenylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, pt-butylstyrene, pn-hexylstyrene, pn-octylstyrene, pn-nonylstyrene, p -N-decylstyrene and pn-dodecylstyrene.

Specific examples of the methacrylate derivative include methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, n-octyl methacrylate, methacrylic acid 2 -Ethylhexyl, stearyl methacrylate, lauryl methacrylate,
Examples thereof include phenyl methacrylate, diethylaminoethyl methacrylate, and dimethylaminoethyl methacrylate.

Specific examples of the acrylate derivative include methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, and t-acrylate.
Examples thereof include butyl, isobutyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, lauryl acrylate, phenyl acrylate, dimethylaminoethyl acrylate, and diethylaminoethyl acrylate.

In the coating resin layer of the carrier, fine particles of aluminum oxide, fine particles of zirconium oxide, or fine particles of melamine-formaldehyde condensate, each having a specific number average primary particle diameter, are dispersed as fine particles dispersed in the coating resin layer. Are added at specific ratios.

The aluminum oxide fine particles dispersed in the coating resin layer have a number average primary particle diameter of 5 to 1,000.
nm, preferably 5 to 200 nm. If the number average primary particle size of the aluminum oxide fine particles exceeds 1000 nm, the resulting carrier has excessive polishing characteristics for the image forming body, and the surface thereof is severely damaged. On the other hand, when the number average primary particle diameter of the aluminum oxide fine particles is less than 5 nm, the obtained carrier is not preferable because the polishing characteristics for the image forming body are too small.

Further, the zirconium oxide fine particles used as the fine particles dispersed in the coating resin layer have a number average primary particle diameter of 5 to 1%.
000 nm, preferably 5 to 200 nm,
As a result, the obtained carrier has good polishing characteristics for the image forming body.

Further, the melamine-formaldehyde condensate fine particles used as the fine particles dispersed in the coating resin layer have a number average primary particle diameter of 10 to 1000 nm, preferably 10 to 30 nm.
0 nm, whereby the resulting carrier has good polishing characteristics for the image forming body.

When the coating resin layer-dispersed fine particles are aluminum oxide fine particles, the addition ratio of the coating resin layer to the core material particles is 0.5 to 5.0% by weight, preferably 0.5 to 4% by weight. 0.0% by weight. When the addition ratio of the aluminum oxide fine particles is less than 0.5% by weight, the obtained carrier is such that free inorganic fine particles easily adhere to the surface thereof, and as a result, a good charging property is obtained for the toner. Can not. On the other hand, when the addition ratio of the aluminum oxide fine particles exceeds 5.0% by weight, the obtained carrier particles are not preferable because the weight of the carrier particles themselves becomes large.

When the coated resin layer-dispersed fine particles are zirconium oxide fine particles, the addition ratio in the coated resin layer is 1.0 to 10.0% by weight, preferably 1.0 to 6% by weight, based on the core material particles. 0.0% by weight, whereby a sufficiently high charge amount can be obtained for the toner over a long period of time. When the addition ratio of the zirconium oxide fine particles is too small or too large, the same problem occurs when the addition ratio of the aluminum oxide fine particles is too small or too large, respectively.

When the fine particles dispersed in the coating resin layer are melamine-formaldehyde condensate fine particles, the content of the fine particles in the coating resin layer is 0.1 to 5.
The amount is 0% by weight, preferably 0.5 to 3.0% by weight, whereby a sufficiently high charge amount can be obtained in the toner for a long period of time. When the addition ratio of the melamine-formaldehyde condensate fine particles is too small or too large,
In each case, the addition ratio of aluminum oxide fine particles is too small
Or, the same problem as in the case of being excessive occurs.

(3) Method of Manufacturing Carrier The method of manufacturing the carrier is as follows. A core resin particle is sprayed with a solution of a resin for forming a coating resin layer in which fine particles dispersed in the coating resin layer are dispersed at a specific ratio, followed by drying. A method in which a specific ratio of the fine particles dispersed in the coating resin layer and the resin particles for forming the coating resin layer are electrostatically adhered to the core material particles, and then coated by applying mechanical energy to the core material particles; A method of applying a specific proportion of the coating resin layer-dispersed fine particles and the resin particles for forming the coating resin layer electrostatically and thereafter heating and melting the resin particles at a melting temperature or higher, core material particles, A method in which the coating resin layer-dispersed fine particles are dispersed at a specific ratio in a solution of a resin for forming a coating resin layer, which is immersed and applied in a solution of the resin. For forming a coating resin layer containing The method is cured by heating after coating fat, other methods may be used.

Of the above methods, the above-mentioned production method is preferable from the viewpoint of uniform dispersibility of the fine particles dispersed in the coating resin layer in the coating resin layer of the carrier and ease of production.

The method of (1) will be described in detail. First, core particles, resin particles for forming a coating resin layer, aluminum oxide fine particles, zirconium oxide fine particles, or melamine-formaldehyde condensate fine particles are mixed with a usual stirring device. By mixing and stirring, the resin particles for forming the coating resin layer are uniformly formed on the surface of the core material particles together with aluminum oxide fine particles, zirconium oxide fine particles or melamine-formaldehyde condensate fine particles by physical adhesion or electrostatic adhesion. Adhere to This step may be performed without heating, or may be performed under heating to such an extent that the resin particles for forming the coating resin layer are softened.

Next, the mixture obtained in the above step is agitated with or without heating to repeatedly apply an impact force to the mixture, whereby the surface of the core particles is coated with the coating resin. Resin particles for forming a layer, aluminum oxide fine particles, zirconium oxide fine particles or melamine-
The target carrier can be obtained by fixing the formaldehyde condensate fine particles.

In the above, the number average primary particle diameter of the resin particles for forming the coating resin layer to be fixed is 0.01 to 2.0.
μm, and preferably 0.05 to 1.0 μm. The addition ratio may be any ratio that can uniformly coat the surface of the core material particles, and specifically, is 0.1 to 10.0% by weight based on the core material particles, and is preferable. Is 0.5 to 6.0% by weight.

The carrier obtained as described above has 1
000 (Oe) when the external magnetic field is applied, the saturation magnetization is 15 to 80 emu / g, particularly 40 to 70 emu.
/ G.

The developer of the present invention can be obtained by mixing the above toner and carrier at a mixing ratio of 5:95 to 15:85 by weight. Further, it is preferable that the particle diameter ratio between the toner and the carrier is 1: 5 to 1: 2.

In such a developer, the colored particles constituting the toner have a volume average particle diameter of 3 to 10 μm.
m, and preferably 4 to 7 μm, a high-resolution visible image with excellent fine line reproducibility can be obtained in the image forming process.

Further, since the inorganic fine particles are added to the toner of the developer in a specific ratio, the toner has a good fluidity and a good transferability can be obtained. .

Further, the carrier of the above-mentioned developer is formed of fine particles of aluminum oxide, fine particles of zirconium oxide or fine particles of melamine-formaldehyde condensate in the coating resin layer, which are harder than the resin forming the coating resin layer and do not deform. Is added at a specific ratio to the core material particles, thereby effectively preventing free inorganic fine particles from being buried in the surface of the carrier particles, and as a result,
A sufficiently high charge amount can be stably obtained in the toner for a long period of time.

The carrier in the above developer is
Aluminum oxide fine particles which are coated resin layer dispersed fine particles,
When each of the zirconium oxide fine particles or the melamine-formaldehyde condensate fine particles has a specific specific number average primary particle diameter, the polishing properties on the surface of the image forming body are improved.

<Image Forming Method> The developer of the present invention may be applied to a contact developing method in which a developer layer formed on a developer carrying carrier is brought into contact with an image forming body having a latent image. However, it is preferable to apply the method to a non-contact developing method in which the developer layer is not brought into contact with the image forming body.

In the non-contact development method, since the stress applied to the toner particles and the carrier particles in the development area is small, the surface state is stable for a long period of time. As a result, when the alternating electric field is applied, Also, a large change in the developing property due to a minute change in the charged state of the toner does not occur.

Further, in the developer of the present invention, the coating resin layer-dispersed fine particles having a specific number average primary particle diameter are contained in the coating resin layer of the carrier constituting the developer at a specific ratio to the core material particles. As is clear from the results of Examples described later, the toner can obtain a sufficiently high charge amount over a long period of time, so that a stable image can be formed over a long period of time by a non-contact development method. be able to.

Hereinafter, an example of the non-contact developing method will be described with reference to the drawings. FIG. 1 is an explanatory diagram of a non-contact developing method in the image forming method of the present invention, wherein 1 is a photosensitive drum as an image forming body, 10 is a developing device, and a developing device 10 A developer carrying carrier 2 for carrying;
A developer amount regulating body 4 for forming the developer layer 6 is provided, and a developing area 5 is formed between the photoconductor drum 1 and the developer carrying carrier 2 by a gap. Reference numeral 7 denotes a power supply for forming an alternating electric field in the developing area 5.

The developer carrier 2 is provided with a developing sleeve 2A.
And a magnet 2B, and the developing sleeve 2A is made of aluminum, oxidized aluminum, stainless steel, or the like. The diameter of the developing sleeve 2A is 10 to 40.
mm. If the diameter is too small, it is difficult to ensure a sufficient mixing action to impart charging to the toner, and if the diameter is too large, the centrifugal force on the developer layer 6 is large. This causes a problem of toner scattering.

The developer 3 is carried by a magnetic force on a developer carrying carrier 2 having a magnet 2B inside, and the developer layer 6 is formed by the developer amount regulating body 4 by the movement of the developing sleeve 2A. Is transported to the developing area 5. The thickness of the developer layer 6 in the development area 5 is 20 to 5
It is preferably 00 μm.

The pressing force of the developer amount regulating body 4 against the developing sleeve 2A is preferably 1 to 15 gf / mm, and more preferably 3 to 10 gf / mm. When the pressing force is too small, the regulating force is insufficient, so that the developer layer tends to have no constant thickness. On the other hand, when the pressing force is too large, the stress on the developer is large. Therefore, the durability of the developer tends to decrease.
As a material of the developer amount regulating body 4, a urethane blade, a phosphor bronze plate, or the like can be used.

The minimum gap (D_sd) Is the current
Greater than the thickness of the developer layer 6 transported to the image area 5
Is necessary, for example, about 100 to 1000 μm.
You. A power supply 7 for forming an alternating electric field has a frequency of 1 to 1
0 kHz, voltage 1-3 kV _ppAC power supply
preferable. The power supply 7 is connected to a DC power supply as needed.
May be added in series to the power supply.
Voltage of the DC power supply is 300-800V
preferable. When adding a development bias, only the DC component
, Or applying an AC bias
It may be.

The non-contact developing method as described above can be suitably used for forming a color image. That is, a color image forming method includes a sequential transfer method in which a single-color image is formed on an image forming body and sequentially transferred to an image support, and a color image formed by superimposing a single-color image on an image forming body a plurality of times. Is formed, and then there is a batch transfer system in which the batch transfer is performed to the image support, but from the viewpoint of eliminating color misregistration at the time of transfer, the batch transfer system is preferable, and in this batch transfer system,
A non-contact development method is used.

On the other hand, when the developer of the present invention is applied to the contact developing method, the gap between the image forming body and the developer carrying carrier is preferably 0.15 to 7 mm.
More preferably, the thickness is 0.2 to 4 mm, and the thickness of the developer layer in the development area is set to a size such that the developer layer comes into contact with the image forming body in the development area.
８8 mm, more preferably 0.4 mm
５5 mm.

[0092]

Hereinafter, embodiments of the present invention will be described.
The present invention is not limited to these. In the following, the volume average particle diameter and CV value of the colored particles for toner were measured by the following methods.

(1) Measuring equipment: Coulter Multisizer (aperture diameter: 100 μm) (2) Preparation of measurement sample: electrolytic solution [ISOTON®
-II (manufactured by Coulter Scientific Japan)] A suitable amount of a surfactant (neutral detergent) is added to 50 to 100 ml, and the mixture is stirred.
0 to 20 mg was added, and this system was subjected to a dispersion treatment for 1 minute by an ultrasonic disperser to prepare a measurement sample. (3) Measuring method: The particle size data of the measurement sample is measured by a Coulter Multisizer, and the particle size data is transferred to a computer via an I / O unit.
It was calculated by a particle size distribution analysis program in the computer.

(1) Production of Colored Particles <Preparation Example 1 of Colored Particles> 100 parts by weight of a polyester resin as a binder resin, 10 parts by weight of carbon black as a colorant, and 5 parts by weight of polypropylene as a release agent Premixed with a Henschel mixer
Melt kneading with a twin screw extruder, coarsely pulverizing with a hammer mill, finely pulverizing with a jet pulverizer, classifying with an air classifier, and measuring the particle size distribution of the obtained powder with a Coulter Multisizer Repeatedly, colored particles for toner (A)
I got Table 1 shows the volume average particle size and CV value of the obtained colored particles (A).

<Preparation Examples of Colored Particles 2 to 4> As shown in Table 1, colored particles were prepared except that yellow, magenta and cyan pigments were used as colorants, and the conditions of pulverization and classification were appropriately changed. In the same manner as in Preparation Example 1, colored particles (B) to (D) for toner were obtained. Table 1 also shows the volume average particle diameters and CV values of the obtained colored particles (B) to (D).

<Preparation Example 5 of Colored Particles> [Preparation of Latex (1)] In a resin container having an inner volume of 20 liters, 0.90 kg of sodium n-dodecyl sulfate and 10.0 liters of pure water were stirred and dissolved. Then, 1.20 kg of carbon black was gradually added to this solution, stirred for 1 hour, and further subjected to continuous dispersion treatment for 20 hours using a medium type disperser to prepare a colorant dispersion. Separately, 0.55 kg of sodium dodecylbenzenesulfonate was placed in a stainless steel pot, 4.0 liters of ion-exchanged water was added, and the mixture was stirred and dissolved at room temperature to prepare an anionic surfactant solution A. Further, 0.14 kg of nonionic surfactant “Newcol 565C” (manufactured by Nippon Emulsion Co., Ltd.) was added to 4.0 liters of ion-exchanged water placed in a stainless steel pot, and the mixture was stirred and dissolved at room temperature to obtain a nonionic surfactant solution. B
Was prepared. Further, 223.8 g of potassium persulfate was added to 12.0 liters of ion-exchanged water and dissolved by stirring at room temperature to prepare a polymerization initiator solution C.

In the reactor, the number average primary particle size was 120 n.
m, 3.41 kg of a polypropylene emulsion having a number average molecular weight of 3000, an anionic surfactant solution A,
Nonionic surfactant solution B was added and stirred, and then
44.0 liters of ion-exchanged water was added and heated. When the liquid temperature reached 75 ° C., the polymerization initiator solution C was added. Then, while controlling the liquid temperature to 75 ° C., 12.1 kg of styrene and 2.88 kg of n-butyl acrylate
And 1.04 kg of methacrylic acid and 548 g of t-dodecylmercaptan were fed by a liquid sending pump. Further, the liquid temperature was raised to 80 ° C., and the mixture was heated and stirred for 6 hours to prepare a latex. This is called "latex (1)". The resin fine particles of the latex (1) have a glass transition temperature of 57 ° C., a softening point of 121 ° C., and a weight average molecular weight of 1270.
0, the weight average particle diameter was 120 nm.

[Preparation of Latex (2)] Sodium dodecylbenzenesulfonate (0.55 kg) was added to 4.0 liters of ion-exchanged water and dissolved by stirring at room temperature to prepare an anionic surfactant solution D. In addition, 4.0 liters of ion-exchanged water placed in a stainless steel pot was added to a nonionic surfactant “Newcol 565C” (manufactured by Nippon Emulsifier Co.).
0.14 kg was added and dissolved by stirring at room temperature to prepare a nonionic surfactant solution E. In addition, potassium persulfate 20
0.7 g was added to 12.0 liters of ion-exchanged water and dissolved by stirring at room temperature to prepare a polymerization initiator solution F.

In the reactor, the number average primary particle diameter was 120 n.
m, 3.41 kg of an emulsion of polypropylene having a number average molecular weight of 3000, an anionic surfactant solution D,
Nonionic surfactant solution E was added and stirred, and then
44.0 liters of ion-exchanged water was added and heated. When the liquid temperature reached 70 ° C., a polymerization initiator solution F was added. While controlling the liquid temperature to 70 ° C, styrene 11.0
8.00 kg, 4.00 kg of n-butyl acrylate, 1.04 kg of methacrylic acid, and t-dodecyl mercaptan.
02 g was fed by a liquid sending pump. And the liquid temperature is 7
The solution was heated to 2 ° C and stirred for 6 hours.
C. and heated and stirred for 12 hours to prepare a latex. This is called "latex (2)". The resin fine particles of this latex (2) have a glass transition temperature of 58.
° C, softening point 132 ° C, weight average molecular weight 245,000
It was.

[Preparation of Colored Particles]
5.36 kg of sodium chloride as a salting-out agent and 20.0 liters of ion-exchanged water were added and dissolved by stirring to prepare a sodium chloride solution G. In addition, the nonionic surfactant "F
1.00 g of "C-170C" (manufactured by Sumitomo 3M Ltd.) was added, and 1.00 liter of ion-exchanged water was added and dissolved by stirring to prepare a nonionic surfactant solution H.

In the reactor, 20.0 k of latex (1) was added.
g, 5.2 kg of latex (2), 0.4 kg of a colorant dispersion and 20.0 kg of ion-exchanged water, and the mixture was stirred. , 6.00 kg of isopropanol and nonionic surfactant solution H were added in this order. Thereafter, the temperature of the system was raised to 85 ° C., and the mixture was heated and stirred for 6 hours.
Salting out and association fusion of the fine particles were performed. Thereafter, the temperature of the system was cooled to 40 ° C. or lower, and toner material particles were obtained by filtering the system. The toner material particles were washed with ion-exchanged water, and then the toner material particles were dried and crushed. . The crushed toner material particles were appropriately classified by a classifier to obtain colored particles (E) for toner. Table 1 shows the volume average particle diameter and CV value of the obtained colored particles (E).

<Colored particle preparation examples 6 to 8> As shown in Table 1, the toner was prepared in the same manner as the color particle preparation example 5 except that a yellow pigment, a magenta pigment or a cyan pigment was used as the colorant. Colored particles (F) to (H) were obtained. Table 1 also shows the volume average particle diameters and CV values of the obtained colored particles (F) to (H).

<Preparation Examples of Colored Particles 9 to 12> As shown in Table 1, preparation examples of colored particles were the same as those described above except that yellow, magenta or cyan pigments were used as colorants, and the conditions for pulverization and classification were appropriately changed. In the same manner as in Example 1, colored particles (a) to (d) for toner were obtained. Table 1 also shows the volume average particle diameters and CV values of the obtained colored particles (a) to (d).

[0104]

[Table 1]

(2) Production of Toner Each of the colored particles (A) to (H) and the colored particles (a) to (d) obtained in the above colored particle preparation examples 1 to 12 was prepared according to the conditions shown in Table 2. By mixing inorganic fine particles with a Henschel mixer (FM-10),
Toners (A) to (H) and toners (a) to (h) were obtained.

[0106]

[Table 2]

(3) Manufacture of Carrier <Carrier Preparation Example 1-1> As shown in Table 3, the specific gravity was 3.7, the number average primary particle diameter was 25 μm, and 1000 (O
e) When the external magnetic field is applied, the saturation magnetization is 60 emu.
/ G of dispersible magnetic material particles and polymerizing methyl methacrylate and styrene at a weight ratio of 6: 4 to form a coating resin layer having a number average primary particle diameter of 0.10 μm. Oxide particles having a weight-average primary particle diameter of 15 nm and resin particles of 5.0% by weight.
% By weight into a high-speed stirring type mixing apparatus, and
Under a condition of 5 m / s, a mixing treatment was performed for 20 minutes to obtain a mixture in which resin particles for forming a coating resin layer and aluminum oxide fine particles were adhered to the surfaces of the dispersed magnetic particles.
Thereafter, the mixture was continuously applied with a mechanical impact force for 30 minutes under the conditions of a blade peripheral speed of 15 m / s and a temperature of 110 ° C. by a high-speed stirring type mixing apparatus, and cooled, whereby the carrier (X-1) was cooled. ) Got.

<Carrier Preparation Examples 1-2 to 1-6> A carrier (X-2) was prepared in the same manner as in Carrier Preparation Example 1-1, except that the addition ratio of the aluminum oxide fine particles was as shown in Table 3. ), Carrier (X-3) and carrier (x-3) for comparison. Except that no aluminum oxide fine particles were added, Carrier Preparation Example 1
In the same manner as -1, the carrier for comparison (x-1)
I got Further, instead of the aluminum oxide fine particles, titanium oxide fine particles having a number average primary particle diameter of 30 nm.
Carrier Preparation Example 1-1 except that 0% by weight was added.
In the same manner as in the above, a carrier (x-2) for comparison was obtained.

[0109]

[Table 3]

<Carrier Preparation Example 2-1> As shown in Table 4, the specific gravity was 3.7, the number average primary particle diameter was 25 μm,
When an external magnetic field of 00 (Oe) is applied, the saturation magnetization is 6
A coating resin layer having a number average primary particle diameter of 0.10 μm obtained by polymerizing methyl methacrylate and styrene at a weight ratio of 6: 4 with respect to dispersed magnetic particles of 0 emu / g. 5.0% by weight of resin particles for formation and 1.5% by weight of zirconium oxide fine particles having a number average primary particle diameter of 27 nm were charged into a high-speed stirring type mixing apparatus, and the conditions at a blade peripheral speed of 15 m / s were used. And mix for 20 minutes.
A mixture was obtained by adhering resin particles for forming a coating resin layer and zirconium oxide fine particles to the surface of the dispersed magnetic particles. Thereafter, the mixture was continuously applied with a mechanical impact force for 30 minutes under the conditions of a blade peripheral speed of 15 m / s and a temperature of 110 ° C. by using a high-speed stirring type mixing apparatus, and cooled, thereby cooling the carrier (Y-1). I got

<Carrier Preparation Example 2-2 to 2-4> The carrier (Y-2) was prepared in the same manner as in Carrier Preparation Example 2-1 except that the addition ratio of the zirconium oxide fine particles was as shown in Table 4. ), Carrier (Y-3) and carrier (y-1) for comparison.

[0112]

[Table 4]

<Carrier Preparation Example 3-1> As shown in Table 5, the specific gravity was 3.7, the number average primary particle diameter was 25 μm,
When an external magnetic field of 00 (Oe) is applied, the saturation magnetization is 6
A coating resin layer having a number average primary particle diameter of 0.10 μm obtained by polymerizing methyl methacrylate and styrene at a weight ratio of 6: 4 with respect to dispersed magnetic particles of 0 emu / g. 5.0% by weight of resin particles for forming and 0.3% by weight of melamine-formaldehyde condensate fine particles having a number average primary particle diameter of 160 nm were charged into a high-speed stirring type mixing apparatus, and the blade peripheral speed was 15 m / s. Under the conditions of
After mixing for minutes, a mixture was obtained in which resin particles for forming a coating resin layer and melamine-formaldehyde condensate fine particles were adhered to the surfaces of the dispersed magnetic particles. afterwards,
Subsequently, a mechanical impact force is repeatedly applied to the mixture by a high-speed stirring type mixing device at a blade peripheral speed of 15 m / s and a temperature of 110 ° C. for 30 minutes, followed by cooling to obtain a carrier (Z-1). Was.

<Carrier Preparation Example 3-2 to 3-4> A carrier (carrier) was prepared in the same manner as in Carrier Preparation Example 3-1 except that the addition ratio of the melamine-formaldehyde condensate fine particles was as shown in Table 5. Z-2), carrier (Z
-3), a carrier (z-1) for comparison was obtained.

[0115]

[Table 5]

(4) Production of Developer The following Examples 1-1 to 1-4, Examples 2-1 to 2-4,
Further, a developer was manufactured according to Examples 3-1 to 3-4. Further, a comparative developer was prepared by using the following Comparative Examples 1-1 to 1-1.
-5, Comparative examples 2-1 to 2-3, and Comparative examples 3-1 to 3
-3.

<Example 1-1> 9 parts by weight of each of the toners (A) to (D) and 91 parts by weight of the carrier (X-2) were mixed for 20 minutes using a V-type mixer to obtain black, A total of four color developers of yellow, magenta and cyan (A
-1) to (A-4) were obtained.

<Example 1-2> 9 parts by weight of each of the toners (E) to (H) and 91 parts by weight of the carrier (X-1) were mixed for 20 minutes using a V-type mixer to obtain black, A total of four color developers of yellow, magenta and cyan (A
-5) to (A-8) were obtained.

<Example 1-3> 9 parts by weight of each of the toners (E) to (H) and 91 parts by weight of the carrier (X-2) were mixed for 20 minutes using a V-type mixer to obtain black, A total of four color developers of yellow, magenta and cyan (A
-9) to (A-12) were obtained.

<Example 1-4> 9 parts by weight of each of the toners (E) to (H) and 91 parts by weight of the carrier (X-3) were mixed for 20 minutes using a V-type mixer to obtain black, A total of four color developers of yellow, magenta and cyan (A
-13) to (A-16).

Comparative Example 1-1 9 parts by weight of each of the toners (a) to (d) and 91 parts by weight of the carrier (X-2) were mixed for 20 minutes using a V-type mixer to obtain black, Comparative color developers (a-1) to (a-4) of a total of four colors of yellow, magenta and cyan were obtained.

<Comparative Example 1-2> 9 parts by weight of each of the toners (e) to (h) and 91 parts by weight of the carrier (X-2) were mixed for 20 minutes using a V-type mixer. Comparative color developers (a-5) to (a-8) of a total of four colors of yellow, magenta and cyan were obtained.

Comparative Example 1-3 9 parts by weight of each of the toners (E) to (H) and 91 parts by weight of the carrier (x-1) were mixed for 20 minutes using a V-type mixer to obtain black, Comparative color developers (a-9) to (a-12) of a total of four colors of yellow, magenta and cyan were obtained.

<Comparative Example 1-4> 9 parts by weight of each of the toners (E) to (H) and 91 parts by weight of the carrier (x-2) were mixed for 20 minutes using a V-type mixer. Comparative color developers (a-13) to (a-16) of a total of four colors of yellow, magenta and cyan were obtained.

<Comparative Example 1-5> 9 parts by weight of each of the toners (E) to (H) and 91 parts by weight of the carrier (x-3) were mixed for 20 minutes using a V-type mixer. Comparative color developers (a-17) to (a-20) of a total of four colors of yellow, magenta and cyan were obtained.

<Example 2-1> 9 parts by weight of each of the toners (A) to (D) and 91 parts by weight of the carrier (Y-2) were mixed for 20 minutes using a V-type mixer to obtain black, A total of four color developers of yellow, magenta and cyan (B
-1) to (B-4) were obtained.

<Example 2-2> 9 parts by weight of each of the toners (E) to (H) and 91 parts by weight of the carrier (Y-1) were mixed for 20 minutes using a V-type mixer to obtain black, A total of four color developers of yellow, magenta and cyan (B
-5) to (B-8) were obtained.

<Example 2-3> 9 parts by weight of each of the toners (E) to (H) and 91 parts by weight of the carrier (Y-2) were mixed for 20 minutes using a V-type mixer to obtain black, A total of four color developers of yellow, magenta and cyan (B
-9) to (B-12).

<Example 2-4> 9 parts by weight of each of the toners (E) to (H) and 91 parts by weight of the carrier (Y-3) were mixed for 20 minutes using a V-type mixer. A total of four color developers of yellow, magenta and cyan (B
-13) to (B-16) were obtained.

<Comparative Example 2-1> 9 parts by weight of each of the toners (a) to (d) and 91 parts by weight of the carrier (Y-2) were mixed for 20 minutes using a V-type mixer to obtain black, Thus, a total of four comparative color developers (b-1) to (b-4) of yellow, magenta and cyan were obtained.

Comparative Example 2-2 9 parts by weight of each of the toners (e) to (h) and 91 parts by weight of the carrier (Y-2) were mixed for 20 minutes using a V-type mixer to obtain black, Comparative color developers (b-5) to (b-8) of a total of four colors of yellow, magenta and cyan were obtained.

<Comparative Example 2-3> 9 parts by weight of each of the toners (E) to (H) and 91 parts by weight of the carrier (y-1) were mixed for 20 minutes using a V-type mixer. Comparative color developers (b-9) to (b-12) of a total of four colors of yellow, magenta and cyan were obtained.

<Example 3-1> 9 parts by weight of each of the toners (A) to (D) and 91 parts by weight of the carrier (Z-2) were mixed for 20 minutes using a V-type mixer to obtain black, A total of four color developers of yellow, magenta and cyan (C
-1) to (C-4) were obtained.

<Example 3-2> 9 parts by weight of each of the toners (E) to (H) and 91 parts by weight of the carrier (Z-1) were mixed for 20 minutes using a V-type mixer to obtain black, A total of four color developers of yellow, magenta and cyan (C
-5) to (C-8) were obtained.

<Example 3-3> 9 parts by weight of each of the toners (E) to (H) and 91 parts by weight of the carrier (Z-2) were mixed for 20 minutes using a V-type mixer to obtain black, A total of four color developers of yellow, magenta and cyan (C
-9) to (C-12).

<Example 3-4> 9 parts by weight of each of the toners (E) to (H) and 91 parts by weight of the carrier (Z-3) were mixed for 20 minutes using a V-type mixer to obtain black, A total of four color developers of yellow, magenta and cyan (C
-13) to (C-16).

<Comparative Example 3-1> 9 parts by weight of each of the toners (a) to (d) and 91 parts by weight of the carrier (Z-2) were mixed for 20 minutes using a V-type mixer. Comparative color developers (c-1) to (c-4) of a total of four colors of yellow, magenta and cyan were obtained.

<Comparative Example 3-2> 9 parts by weight of each of the toners (e) to (h) and 91 parts by weight of the carrier (Z-2) were mixed for 20 minutes using a V-type mixer. Comparative color developers (c-5) to (c-8) of a total of four colors of yellow, magenta and cyan were obtained.

<Comparative Example 3-3> 9 parts by weight of each of the toners (E) to (H) and 91 parts by weight of the carrier (z-1) were mixed for 20 minutes using a V-type mixer. Comparative color developers (c-9) to (c-12) of a total of four colors of yellow, magenta and cyan were obtained.

<Evaluation of Image> A commercially available color printer for electrophotography "KL2010" (manufactured by Konica Corporation) was modified and used with four-color developers based on combinations of Examples and Comparative Examples shown in Tables 6 to 8. A color image was formed, and the following items were evaluated. Tables 6 to 8 also show the results. The image forming method is performed by a non-contact developing method of a batch transfer method, and the minimum gap of the developing area is 400 to 600 μm.
And the alternating electric field in the developing area has a voltage of 2.4 to
The measurement was performed at 2.9 kV and a frequency of 6 kHz.

(1) Stability of Charge Amount While forming an image on 200,000 sheets, the charge amount of the toner was measured appropriately, and the difference between the maximum value and the minimum value of the charge amount was determined.
That is, when the charge amount variation width is 6 μC / g or less, “「 ”indicates
The case of 20 C / g or more was evaluated as “×”, and the other cases were evaluated as “△”.

(2) Development Density Stability Image formation on 200,000 sheets is performed, and the density of the image formed as appropriate is measured using an image density measurement apparatus “PDA65 SA”.
The transmission density was measured by "KURA DENSITOMETER". The difference between the maximum value and the minimum value of the measured density of the image, that is, the case where the density variation width is 0.1 or less is “○”, and the case of 0.2 or more is “×”, The case was marked with “△”. Here, the density of the image is an average value of the densities of the four colors.

(3) Transferability An image was formed on 200,000 sheets. The obtained image was evaluated for transfer omission of a solid image portion by uneven image density, and the reproducibility of a thin line portion was observed with a microscope. And
In all the images, there is no transfer omission, and the case where the thin line portion is sufficiently reproduced is represented by “○”, and the case where either the transfer omission or the reproducibility of the thin line portion is insufficient is formed. “△”, and “×” when an image with insufficient transfer omission and insufficient reproducibility of the fine line portion is formed.
And

(4) Toner Scattering A particle counter was set in the above-mentioned machine, and 0.5
Under the suction condition of liter / min, the number of toners to be sucked was measured every 20 seconds, and the number of image formed when the measured number of toners exceeded 20 was recorded.

[0145]

[Table 6]

[0146]

[Table 7]

[0147]

[Table 8]

[0148]

As described above, according to the developer of the present invention, a toner having a small average particle diameter and a resin-coated carrier can be used without sacrificing fluidity and transferability. In addition, a sufficiently high charge amount can be stably obtained over a long period of time, and high development density stability can be obtained. Further, according to the image forming method of the present invention, a high-quality image can be formed for a long period of time. Therefore, according to the present invention, it can be suitably used for a color image forming method.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a non-contact developing method in an image forming method of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 photoreceptor drum 2 developer transport carrier 3 developer 4 developer amount regulator 5 development area 6 developer layer 7 power supply 10 developer

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G03G 13/00 G03G 9/10 331 15/08 507 361 362 15/08 507L (72) Inventor Tomomi Oshiba Tokyo Konica Corporation, 2970, Ishikawa-cho, Hachioji-shi, Tokyo Inventor Takao Yamanouchi Konica Corporation, 2970, Ishikawa-cho, Hachioji-shi, Tokyo (72) Kazuya Isobe 2970, Ishikawacho, Hachioji-shi, Tokyo (72) Inventor Yukio Hosoya 2970 Ishikawa-cho, Hachioji-shi, Tokyo F-term in Konica Corporation (Reference) 2H005 AA01 AA08 AA21 BA03 BA06 BA07 CA15 CA21 CB07 CB13 CB18 DA05 EA05 EA07 FA01 2H070 AA01 BB14 CC09 2H077 AD36 FA12 EA03

Claims (4)

[Claims] 1. A composition comprising a binder resin and a colorant.
A toner in which inorganic fine particles are added at a ratio of 1.0 to 10.0% by weight to colored particles having a volume average particle diameter of 3 to 10 μm, and a coating resin layer formed on the surface of core material particles, A developer comprising a carrier to which fine particles of aluminum oxide having a number average primary particle diameter of 5 to 1000 nm are added at a ratio of 0.5 to 5.0% by weight. 2. A composition comprising a binder resin and a colorant.
A toner in which inorganic fine particles are added at a ratio of 1.0 to 10.0% by weight to colored particles having a volume average particle diameter of 3 to 10 μm, and a coating resin layer formed on the surface of core material particles, A developer comprising a carrier to which fine particles made of zirconium oxide having a number average primary particle diameter of 5 to 1000 nm are added at a ratio of 1.0 to 10.0% by weight. 3. A composition comprising a binder resin and a coloring agent.
A toner in which inorganic fine particles are added at a ratio of 1.0 to 10.0% by weight to colored particles having a volume average particle diameter of 3 to 10 μm, and a coating resin layer formed on the surface of core material particles, A developer comprising a carrier to which fine particles comprising a melamine-formaldehyde condensate having a number average primary particle diameter of 10 to 1000 nm are added at a ratio of 0.1 to 5.0% by weight. 4. A developer layer made of a developer according to claim 1 formed on a developer carrying carrier in a state in which the developer layer is in non-contact with the image forming body. An image forming method comprising developing a latent image on an image forming body by transporting the latent image to a developing area.