JP2003107782A - Negatively charged dry process toner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide negatively charged dry process toner excellent in uniformity of electrified charge of toner particles, nearly free from fogging and capable of enhancing transfer efficiency, in a negatively charged dry process toner formed by adding particles of an aluminum oxide-silicon dioxide compound oxide obtained by an in-furnace hydrolysis method to toner base particles. SOLUTION: The negatively charged dry process toner is formed by adding the particles of the aluminum oxide-silicon dioxide compound oxide and fine particles of a silicon dioxide to the toner base particles.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a negative charging dry toner used in an image forming apparatus for transferring a visible toner image formed on a latent image carrier by an electrophotographic method onto a transfer material.

[0002]

2. Description of the Related Art Conventionally, as an image forming apparatus, a photoreceptor such as a photoreceptor drum or a photoreceptor belt, which is a latent image carrier, is rotatably supported on the main body of the image forming apparatus, and the photoreceptor is used during the image forming operation. After the electrostatic latent image is formed on the photosensitive layer, the latent image is visualized with toner, and then the visible image is directly transferred onto a transfer medium using corona transfer or a transfer roller, or a transfer drum or There is a method in which a visible image is once transferred using an intermediate transfer medium such as a transfer belt and then re-transferred onto a transfer material.

Although such a system is used in a monochrome image forming apparatus, in a color image forming apparatus, a visualized image on a transfer belt or a transfer drum is formed by using a plurality of photoconductors and developing mechanisms. A method is known in which a plurality of color images are sequentially superimposed and transferred onto a transfer material such as paper, and then fixed. Among these methods, those using a belt are classified as a tandem method, and those using a drum are classified as a transfer drum method. In addition to this, an intermediate transfer method is also known in which color images are sequentially primary-transferred onto an intermediate transfer medium, and the primary transfer images are collectively secondarily transferred onto a transfer material such as paper. Further, the photoconductor used in each of these transfer systems is equipped with a cleaning mechanism for cleaning the toner developed by the developing device and the untransferred toner after the transfer.

In these image forming apparatuses, a two-component toner is generally known as a toner, which enables relatively stable development, but the composite ratio of the developer and the magnetic carrier fluctuates. It is easy to do and needs to be maintained. Therefore, one-component magnetic toner has been developed,
There is a problem that a clear color image cannot be obtained due to the opacity of the magnetic material. On the other hand, although a one-component non-magnetic toner has been developed as a color toner, how to uniformly charge the toner has been a problem in order to obtain a high-quality recorded image.

However, in general, one-component non-magnetic toner particles have a particle size distribution, so that toner particles that do not come into contact with each other when contact charged by a regulating blade are generated, and even if externally added particles are added, a charge amount distribution is generated and negative charging is performed. Even dry toner cannot avoid containing positively charged toner particles. As a result, in the image forming apparatus that forms images by negative charging reversal development, toner adheres to the non-image portion of the latent image carrier (photoconductor), and as the number of printed sheets increases,
There is a problem that the amount of fog-adhered toner increases due to toner deterioration. Also, for the purpose of preventing toner deterioration, S
Even if an attempt is made to maintain the fluidity of the toner by adding a large amount of iO ₂ particles, there is a problem that the fixability is impaired.

In order to improve the negative charging ability of the toner particles, a small amount of Al ₂ O ₃ particles having a positive charging property opposite to the toner polarity is added to enhance the early-starting capability of the toner negative charging. If the primary particle size of the Al ₂ O ₃ particles is small, they are embedded in the toner particles during printing, and it is difficult to exert the desired effect. Further, if the primary particle diameter of the Al ₂ O ₃ particles is made large, the surface of the photoconductor is excessively polished as the number of printed sheets increases, which causes a problem that the film thickness of the photoconductor is reduced and the life is shortened.

Further, if the negative charging ability of the toner becomes too high, the density of the printed image decreases, so that titanium oxide particles having a relatively low electric resistance are added for the purpose of preventing it. Generally, titanium oxide particles are When the primary particle size is small and the number of printed sheets is increased, the particles are buried in the toner particles and it is difficult to exert a desired effect.

On the other hand, Japanese Unexamined Patent Publication No. 2000-181130 discloses toner particles composed of aluminum oxide-silicon dioxide composite oxide particles obtained by a flame hydrolysis method, and has good fluidity and stable toner powder. It is disclosed that the charge behavior (a quick charge retention property, a high charge, and a constant charge after a lapse of time is obtained) is obtained. However, the aluminum oxide-silicon dioxide composite oxide particles are used as negative external additive particles. In the case of the charge dry type toner, since the aluminum oxide component functions as a positive charge site, there arises a problem that a reverse transfer toner is generated and fog is increased, and transfer efficiency is lowered.

[0009]

DISCLOSURE OF THE INVENTION The present invention is directed to the use of aluminum oxide which is obtained by the internal hydrolysis method for toner mother particles.
Disclosed is a negatively charged dry toner containing silicon dioxide composite oxide particles as an external additive, which is excellent in the uniformity of the charge of the toner particles, has less fog, and can improve transfer efficiency. Is an issue.

[0010]

The negatively charged dry toner of the present invention is obtained by externally adding aluminum oxide-silicon dioxide composite oxide particles and silicon dioxide fine particles obtained by a flame hydrolysis method to toner mother particles. Characterize.

The aluminum oxide-silicon dioxide composite oxide particles obtained by the above-mentioned flame hydrolysis method have a primary particle diameter of 7 to 80 nm, and 20 nm or more on a number basis are 30% or more. And

The aluminum oxide-silicon dioxide composite oxide particles obtained by the above-mentioned flame hydrolysis method have a particle size of 5.0 to
It is characterized in that it shows two kinds of work functions, a first work function in the range of 5.4 and a second work function in the range of 5.4 to 5.7.

Aluminum oxide-silicon dioxide composite oxide particles are contained in an amount of 0.1 to 3% by weight based on the toner base particles.
It is characterized in that it is added in a ratio of.

The toner base particles are made of a polyester resin.

The toner base particles are made of a styrene-acrylic copolymer resin.

The circularity of the above negatively charged dry toner is 0.9.
It is characterized by being 4 or more.

The toner base particles are polymerized toners, and the number of negatively charged dry toners is 50% and the particle diameter is 8μ.
It is characterized by being m or less.

The above-mentioned negatively charged dry toner is a full-color toner.

It is characterized in that the above negatively charged dry toner is subjected to reversal development.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION The negatively charged dry toner of the present invention is a one-component non-magnetic toner, which is an aluminum oxide-silicon dioxide composite oxide obtained by a flame internal hydrolysis method, which is toner mother particles and externally added particles thereof. Particles ”(hereinafter referred to as composite oxide particles) and silicon dioxide (SiO ₂ ) particles. In addition,
In the present invention, the numerical range is, for example, 7 to 80 nm.
In the description, the former unit in the case of using the same unit as 7 nm to 80 nm is omitted, and the same applies to the description of the numerical range using other units.

The toner mother particles may be toner mother particles obtained by a pulverizing method or a polymerization method, but in the case of full color, the polymerization method is preferable. First, as the pulverized toner, at least a pigment is contained in a resin binder, a release agent and a charge control agent are optionally added, and the mixture is uniformly compounded with a Henschel mixer, and then 2
The toner is melted and kneaded by an axial extruder, cooled, and then subjected to a coarse pulverization-fine pulverization step, a classification treatment, and externally added particles are attached to obtain toner particles.

As the binder resin, known toner resins can be used, for example polystyrene and poly-α-.
Methylstyrene, chloropolystyrene, styrene-chlorostyrene copolymer, styrene-propylene copolymer,
Styrene-butadiene copolymer, styrene-vinyl chloride copolymer, styrene-vinyl acetate copolymer, styrene-
Maleic acid copolymer, styrene-acrylic acid ester copolymer, styrene-methacrylic acid ester copolymer, styrene-acrylic acid ester-methacrylic acid ester copolymer, styrene-α-chloromethyl acrylate copolymer, styrene -Acrylonitrile-acrylic ester copolymer, styrene-styrene resin such as styrene-vinyl methyl ether copolymer homopolymer or copolymer containing styrene or styrene substitution, polyester resin, epoxy resin, urethane modified epoxy resin, Silicone modified epoxy resin, vinyl chloride resin, rosin modified maleic acid resin,
Phenyl resin, polyethylene, polypropylene, ionomer resin, polyurethane resin, silicone resin, ketone resin, ethylene-ethyl acrylate copolymer, xylene resin, polyvinyl butyral resin, terpene resin, phenol resin, aliphatic or alicyclic hydrocarbon resin, etc. Can be used alone or in combination. Particularly in the present invention, styrene-acrylic ester resin, styrene-
Methacrylic acid ester resins and polyester resins are preferred. The binder resin has a glass transition temperature of 50 to
It is preferably in the range of 75 ° C and the flow softening temperature of 100 to 150 ° C.

As the colorant, a known colorant for toner can be used. For example, carbon black, lamp black, magnetite, titanium black, chrome yellow, ultramarine blue, aniline blue, phthalocyanine blue, phthalocyanine green, Hansa yellow G, rhodamine 6G, calco oil blue, quinacridone, benzidine yellow, rose bengal, malachite green lake, quinoline. Yellow, C.I. I. Pigment Red 4
8: 1, C.I. I. Pigment Red 122, C.I. I.
Pigment Red 57: 1, C.I. I. Pigment Red 122, C.I. I. Pigment Red 184, C.I.
I. Pigment Yellow 12, C.I. I. Pigment
Yellow 17, C.I. I. Pigment Yellow 97,
C. I. Pigment Yellow 180, C.I. I. Solvent Yellow 162, C.I. I. Pigment Blue 5: 1, C.I. I. Pigment Blue 15: 3 and the like can be used alone or in combination.

As the release agent, a known release agent for toner can be used. Examples thereof include paraffin wax, microwax, microcrystalline wax, cadilla wax, carnauba wax, rice wax, montan wax, polyethylene wax, polypropylene wax, oxidized polyethylene wax, and oxidized polypropylene wax. Among them, polyethylene wax, polypropylene wax, carnauba wax, ester wax and the like are preferably used.

As the charge adjusting agent, a known charge adjusting agent for toner can be used. For example, oil black, oil black BY, Bontron S-22 (manufactured by Orient Chemical Industry Co., Ltd.), Bontron S-34 (manufactured by Orient Chemical Industry Co., Ltd.), salicylic acid metal complexes E-81, E-.
84 (manufactured by Orient Chemical Industry Co., Ltd.), thioindigo pigment, sulfonylamine derivative of copper phthalocyanine, Spiron Black TRH (manufactured by Hodogaya Chemical Industry Co., Ltd.),
Examples thereof include calixarene compounds, organic boron compounds, fluorine-containing quaternary ammonium salt compounds, monoazo metal complexes, aromatic hydroxylcarboxylic acid metal complexes, aromatic dicarboxylic acid metal complexes, and polysaccharides. Among them, colorless or white ones are preferable for color toners.

The component ratio (weight) in the pulverized toner is 100 parts by weight of the binder resin and 0.
5 to 15 parts, preferably 1 to 10 parts, the release agent is 1 to 10 parts, preferably 2.5 to 8 parts, and the charge control agent is 0.1 to 7 parts, preferably Is 0.5-5
It is a department.

The pulverized toner of the present invention is preferably spheroidized for the purpose of improving transfer efficiency.
For that purpose, the circularity can be up to 0.93 by using a device capable of crushing in a relatively round spherical shape in the crushing process, for example, a turbo mill known as a mechanical crusher (manufactured by Kawasaki Heavy Industries, Ltd.). Alternatively, if the crushed toner is used in a commercially available hot-air spheronizer, surfusing system SFS-3 type (manufactured by Nippon Pneumatic Industry Co., Ltd.), the circularity can be up to 1.00.

Examples of the polymerization method toner include toners obtained by suspension polymerization method, emulsion polymerization method, dispersion polymerization method and the like. In the suspension polymerization method, a polymerizable monomer, a color pigment, and a release agent are further dissolved, if necessary, or a dye, a polymerization initiator, a cross-linking agent, a charge control agent, or a composite containing other additives is dissolved or The dispersed monomer composition is added to a water phase containing a suspension stabilizer (water-soluble polymer, poorly water-soluble inorganic substance) with stirring, granulated, and polymerized to obtain a desired particle size. Colored polymerized toner particles having can be formed.

In the emulsion polymerization method, a monomer and a release agent are further dispersed in water as necessary to further carry out polymerization by dispersing a polymerization initiator, an emulsifier (surfactant), etc., and then a coloring agent and charge control are carried out in the aggregation process. By adding an agent and an aggregating agent (electrolyte) or the like, colored toner particles having a desired particle size can be formed.

In the materials used for preparing the polymerized toner, the same materials as the above-mentioned pulverized toner can be used for the colorant, the release agent, the charge control agent and the fluidity improving agent.

As the polymerizable monomer (monomer), a known vinyl-based monomer can be used, and examples thereof include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene and p. -Methoxystyrene, p-ethylstyrene, vinyltoluene, 2,4-
Dimethylstyrene, pn-butylstyrene, p-phenylstyrene, p-chlorostyrene, divinylbenzene, methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, isobutyl acrylate, n-octyl acrylate. , Dodecyl acrylate, hydroxyethyl acrylate, 2-ethylhexyl acrylate, phenyl acrylate, stearyl acrylate, 2-chloroethyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, methacrylic acid Isobutyl, methacrylic acid n
-Octyl, dodecyl methacrylate, hydroxyethyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, phenyl methacrylate, acrylic acid, methacrylic acid, maleic acid, fumaric acid, cinnamic acid,
Ethylene glycol, propylene glycol, maleic anhydride, phthalic anhydride, ethylene, propylene, butylene, isobutylene, vinyl chloride, vinylidene chloride, vinyl bromide, vinyl fluoride, vinyl acetate, vinyl propylene oxide, acrylonitrile, methacrylonitrile, vinyl methyl Ether, vinyl ethyl ether, vinyl ketone,
Examples thereof include vinyl hexyl ketone and vinyl naphthalene. Examples of the fluorine-containing monomer include 2,2
2-trifluoroethyl acrylate, 2,2,3,3
-Tetrafluoropropyl acrylate, vinylidene fluoride, ethylene trifluoride, tetrafluoroethylene, trifluoropropylene and the like can be used because the fluorine atom is effective for negative charge control.

Known emulsifiers (surfactants) can be used. For example, sodium dodecylbenzene sulfate, sodium tetradecyl sulfate, sodium pentadecyl sulfate, sodium octyl sulfate, sodium oleate, sodium laurate, potassium stearate, calcium oleate, dodecyl ammonium chloride, dodecyl ammonium bromide, dodecyl trimethyl ammonium bromide, dodecyl pyridinium chloride. , Hexadecyltrimethylammonium bromide, dodecyl polyoxyethylene ether, hexadecyl polyoxyethylene ether, lauryl polyoxyethylene ether, sorbitan monooleate polyoxyethylene ether and the like.

As the polymerization initiator, known ones can be used. For example, potassium persulfate, sodium persulfate, ammonium persulfate, hydrogen peroxide, 4,4′-azobiscyanovaleric acid, t-butyl hydroperoxide, benzoyl peroxide, 2,2′-azobis-isobutyronitrile, etc. is there.

Known coagulants (electrolytes) can be used. Examples thereof include sodium chloride, potassium chloride, lithium chloride, magnesium chloride, calcium chloride, sodium sulfate, potassium sulfate, lithium sulfate, magnesium sulfate, calcium sulfate, zinc sulfate, aluminum sulfate, iron sulfate and the like.

Polymerization method As a method of adjusting the circularity of the toner,
In the emulsion polymerization method, the circularity can be freely changed by controlling the temperature and the time during the aggregation process of the secondary particles, and the range is 0.94 to 1.00. Also, in the suspension polymerization method,
Circularity is 0.98-
It will be in the range of 1.00. Further, by heating and deforming the toner at a temperature higher than the Tg temperature in order to adjust the circularity, the circularity can be freely adjusted to 0.94 to 0.98.

Polymerization toners can be produced by a dispersion polymerization method other than the above-mentioned methods, for example, JP-A-63-30400.
It can be produced by the publication No. 2. In this case, the shape is close to a true sphere.
It is possible to pressurize at a temperature not lower than g to form a desired toner shape.

The externally added particles are for the purpose of stabilizing the charging characteristics and improving the fluidity of the dry toner.
In the dry toner of the present invention, composite oxide particles are used as externally added particles. The complex oxide particles are produced by the method for producing fine powder of silicon-aluminum complex oxide described in Japanese Patent No. 2533067.
It consists of the following manufacturing steps. (1) Evaporate a silicon halide and an aluminum halide and uniformly combine each vapor with air, oxygen and hydrogen in a composite unit together with a carrier gas. (2) Next, the obtained composite steam is supplied to a burner to cause a flame reaction in a combustion chamber, and the obtained gas and solid are cooled in a heat exchange unit. (3) The gas is separated from the solid, and the halide residue attached to the product is removed by heat treatment using moist air to obtain composite oxide particles.

Al ₂ O ₃ and SiO ₂ in the composite oxide particles
Is appropriately adjusted depending on the reaction conditions such as the supply amount of silicon halide and aluminum halide, the supply amount of hydrogen, the supply amount of air and the like.

Al ₂ O ₃ and Si in composite oxide particles
The weight ratio with O ₂ is such that the content of Al ₂ O ₃ is 55% by weight to
The content of 85 wt% and SiO ₂ can be in the range of 45 wt% to 15 wt%. Further, the composite oxide particles have an amorphous structure by being granulated in the flame and have sufficient fine graininess, and have a specific surface area by the BET method of 20 to ²⁰⁰ m ² / g.
Will be the one. The primary particle diameter of the composite oxide particles is 7 to 80.
nm, preferably 10 to 40 nm, and is 2 on a number basis.
0 nm or more is 30% or more.

The composite oxide particles are 0.1 to 3% by weight, preferably 0.2 to 2% by weight, based on the toner mother particles.
It is advisable to add it in the ratio of. Since the complex oxide particles have a broad particle size distribution, it is possible to prevent embedding of the externally added particles in the toner particles during continuous printing even if added in a small amount. Further, the transfer efficiency can be improved by the large particle diameter portion, and since the large particle diameter portion is not too large, abnormal uneven wear of the surface of the photoconductor can be prevented.

Further, the composite oxide particles in the present invention are
A first work function in the range of 5.0 to 5.4 and 5.4 to
It shows two types of work functions of the second work function in the range of 5.7. The work function is the energy required to take out electrons from the substance. The smaller the work function, the easier it is to emit electrons, and the larger the work function, the harder it is to emit electrons. Therefore, when a substance with a low work function is brought into contact with a substance with a high work function, a substance with a low work function is positively charged and a substance with a high work function is negatively charged, but the work function itself takes out electrons from the substance. Energy for eV
Is quantified as.

The details will be described in Example 1, but the work function of the externally added particles will be described with reference to data obtained by using a surface analyzer (AC-2 manufactured by Riken Keiki Co., Ltd., irradiation light amount 500 nW).

Data relating to the composite oxide particles of the present invention are shown in FIGS. Further, SiO ₂ particles (average particle diameter 12 nm), SiO ₂ particles (average particle diameter 40 nm), A
The data for each of the 1 ₂ O ₃ particles alone are shown in FIGS. 3 to 5, respectively. In addition, the data of mixed oxide particles obtained by simply mixing SiO ₂ particles and Al ₂ O ₃ particles are
It shows in FIGS.

In the surface analyzer, the excitation energy of monochromatic light is scanned from the lower side to the higher side, and the energy (work function) at which photoelectron emission starts is measured. Axis) and the normalized photoelectron yield (Emission Yield). For example, referring to FIG. 3 as an example, Si
The work function (WF) of O ₂ particles is 5.22 eV in excitation energy at the inflection point (A). Also, the slope (Sl
ope, normalized photoelectron yield / eV) indicates that the larger the value, the more easily the electron is emitted.

When the composite oxide particles were measured in the same manner as shown in FIG.
As shown in Fig. 2, as the relationship between the photoelectron energy and the photoelectron yield, it has two kinds of excitation energy of 5.18 eV at the inflection point (A) and 5.62 eV at the inflection point (B) as shown in Fig. 2. I understand. Also, similarly,
When the mixed oxide particles are measured, for example, FIGS.
As shown in FIG. 5, it is understood that two kinds of excitation energy of 5.22 eV and 5.52 eV are included. As is clear from Table 1 described below, the composite oxide particles have a large difference in work function as compared with simple mixed oxide particles, and when externally added to the toner mother particles, the composite oxide particles have a positive value as compared with the mixed oxide particles. It turns out that it is easy to give two negative triboelectric charging sites.
Although the detailed reason for this is unknown, the composite oxide particles are made of Si.
It is considered that it is not a simple mixture of O ₂ particles and Al ₂ O ₃ particles.

When the toner particles come into contact with the positive triboelectrification sites of such composite oxide particles, the toner particles can be positively and positively charged and the positively charged toner can be reduced as compared with the mixed oxide particles. Further, when the toner particles come into contact with the negative triboelectrification site, the excessive negative charging property of the toner particles can be controlled, so that a stable negatively charged dry toner can be obtained.

The composite oxide particles in the present invention evaporate silicon halides and aluminum halides, change the respective evaporation amounts according to the purpose, and together with the carrier gas, air, oxygen, and hydrogen in the mixing unit. It can be obtained by uniformly mixing with, and hydrolyzing in a flame, but by controlling the production conditions, the first and second
Can be controlled, and two types of work functions can be shown: a first work function in the range of 5.0 to 5.4 and a second work function in the range of 5.4 to 5.7. .

Next, SiO ₂ particles may be added together with the composite oxide particles as externally added particles. SiO ₂ particles are
It is possible to prevent the toner in the present invention from being a negatively charged dry toner and to prevent a positively charged toner generated when the composite oxide particles are used as the externally added particles. If the composite oxide particles alone are used as externally added particles to form a negatively charged dry toner, the aluminum oxide component in the composite oxide particles functions as a positively charged site, causing reverse transfer toner and increasing fog, which in turn reduces transfer efficiency. However, by adding the negatively chargeable SiO ₂ particles together with the composite oxide particles, it is possible to prevent the toner particles from becoming positively charged toner. Further, by using the composite oxide particles and the SiO ₂ particles in combination, the amount of the SiO ₂ particles used can be reduced as compared with the case of using the conventional SiO ₂ particles alone, and the fixability is not deteriorated.

The system of externally added particles in the present invention includes
Other external additives may be added if necessary, for example, titanium dioxide, alumina, magnesium fluoride, silicon carbide, boron carbide, titanium carbide, zirconium carbide, boron nitride, titanium nitride, zirconium nitride, magnetite, Examples are fine particles of metal titanates such as molybdenum disulfide, aluminum stearate, magnesium stearate, zinc stearate, calcium stearate, barium titanate, and strontium titanate, and silicon metal salts. The average particle diameter of the primary particles of the externally added particles added together with the composite oxide particles is 1 to 500 nm, preferably 5 to 200 nm.

The externally added particles in the present invention are preferably hydrophobized with a silane coupling agent, a titanium coupling agent, a higher fatty acid, a silicone oil, etc., and used, for example, dimethyldichlorosilane, octyltrimethoxysilane, Hexamethyldisilazane, silicone oil, octyl-trichlorosilane, decyl-trichlorosilane, nonyl-trichlorosilane, (4-iso-propylphenyl) -trichlorosilane, (4-t-butylphenyl) -trichlorosilane, dipentyl-dichlorosilane. , Dihexyl-dichlorosilane, dioctyl-dichlorosilane, dinonyl-dichlorosilane, didecyl-
Dichlorosilane, didodecyl-dichlorosilane, (4-
t-butylphenyl) -octyl-dichlorosilane, didecenyl-dichlorosilane, dinonenyl-dichlorosilane, di-2-ethylhexyl-dichlorosilane, di-
3,3-dimethylpentyl-dichlorosilane, trihexyl-chlorosilane, trioctyl-chlorosilane, tridecyl-chlorosilane, dioctyl-methyl-chlorosilane, octyl-dimethyl-chlorosilane, (4-is
Examples include o-propylphenyl) -diethyl-chlorosilane and the like.

In the negatively charged dry toner of the present invention, the amount of the composite oxide particles added to the toner mother particles is 0.1 to 0.1%.
It is 3% by weight, preferably 0.2 to 2% by weight. Also,
The added amount of SiO ₂ particles is 0.3 to 3% by weight, preferably 0.5 to 2% by weight. The total amount of externally added particles to the toner mother particles is 0.5 to 5% by weight, preferably 1
It is preferable to set the ratio to 4% by weight.

The toner base particles and the externally added particles are put into a known complex machine such as a Henschel mixer, a V-type blender, a reversing mixer, a high speed mixer, a cyclomix, an axial mixer, etc., and the toner base particles are externally added to the toner base particles. The particles are subjected to an adhesion treatment to obtain the negatively charged dry toner according to the present invention.

The work function of the negatively charged dry toner thus obtained is 5.3 to 5.9 eV, preferably 5.4 to 5.85 eV. By making the work function of the negatively charged dry toner larger than the work function of the surface of the photoreceptor, fog can be further reduced and transfer efficiency can be further improved, as described in Examples. Also,
If the work function of negatively charged dry type toner is made smaller than the work function of the photoreceptor surface, the amount of charge in negatively charged dry type toner becomes extremely high when the toner regulating member regulates the thin layer of toner on the developing roller. May occur, but the phenomenon can be suppressed.

The negatively charged dry toner of the present invention has a number-based average particle diameter of 5 μm to 10 in the case of a pulverized toner.
μm, preferably 6 μm to 9 μm, and the polymerization method toner has a number 50% particle diameter of 8 μm or less, preferably 4.5 to 8 μm, and 3 μm or less is 10% or less, preferably 5% or less. It has a particle size distribution of

Generally, regardless of whether the toner is a pulverized toner or a polymerized toner, if the toner particle size is reduced, it is necessary to increase the amount of SiO ₂ particles added, which causes a problem that the toner charge amount becomes too large in the initial stage. . Further, as the printing progresses, the effective surface amount of SiO ₂ particles decreases due to embedding or scattering, the charge amount of the toner decreases, the image density fluctuation and the fog amount tend to increase, and the toner consumption tends to increase. There is a problem that it is difficult to use as a toner.
On the other hand, when the composite oxide particles are used as the externally added particles, the particle size distribution is broad, and it is possible to suppress the problems such as the burial of the externally added particles. Since the difference can be large, the negatively charged dry toner can be stable throughout the printing period.

The negatively charged dry toner of the present invention may have a circularity (sphericalization coefficient) of 0.94 or more, preferably 0.95 or more, in any of the pulverization method and the polymerization method. Is. Circularity (spheroidization coefficient) 0.9
It is recommended to use a cleaning blade up to 7 and brush cleaning for more than 7. By setting the circularity (sphericalization coefficient) to 0.94 or more, the transfer efficiency can be improved.

In the present invention, the average particle diameter and circularity (sphericalization coefficient) of toner mother particles and toner particles are values measured by "FPIA2100" manufactured by Sysmex Corporation. The average particle size of the externally added particles such as the composite oxide particles is a value measured by an electron microscope method.

Next, an image forming apparatus to which the negative charging dry toner of the present invention is applied will be described. FIG. 10 shows an example of a 4-cycle full-color printer. A rotary system or a tandem system may be used.

In FIG. 10, reference numeral 100 is an image carrier cartridge in which an image carrier unit is incorporated. In this example, the photoconductor cartridge is configured so that the photoconductor and the developing unit can be separately mounted, and the electrophotographic photoconductor (latent image carrier) 140 is illustrated by an appropriate driving unit (not illustrated). It is driven to rotate in the direction of the arrow. Around the photoconductor 140, along the rotation direction thereof, a charging roller 160 as a charging unit, a developing device 10 (Y, M, C, K) as a developing unit, an intermediate transfer device 30, and a cleaning unit 170 are arranged. It

The charging roller 160 contacts the outer peripheral surface of the photoconductor 140 to uniformly charge the outer peripheral surface. The exposure unit 40 selectively exposes L1 on the outer peripheral surface of the uniformly charged photoconductor 140 according to desired image information, and an electrostatic latent image is formed on the photoconductor 140 by this exposure L1. The electrostatic latent image is developed by the developing device 10 to which a developer is applied.

As a developing device, a yellow developing device 10Y,
Developing device 10M for magenta, developing device 10C for cyan,
Also, a developing device 10K for black is provided. Each of the developing devices 10Y, 10C, 10M, and 10K is configured to be swingable, and only the developing roller (developer carrying member) 11 of one developing device can selectively come into pressure contact with the photoconductor 140. ing. These developing devices 10 hold negatively charged toner on the developing roller,
These developing devices 10 use any one of yellow Y, magenta M, cyan C, and black K toners on the photoreceptor 14
It is applied to the surface of 0 to develop the electrostatic latent image on the photoconductor 140. The developing roller 11 is a hard roller, for example, a metal roller having a roughened surface. The developed toner image is transferred onto the intermediate transfer belt 36 of the intermediate transfer device 30. The cleaning unit 170 includes a cleaner blade that scrapes off the toner T adhering to the outer peripheral surface of the photoconductor 140 after the transfer, and a cleaning toner collecting unit that receives the toner scraped off by the cleaner blade.

The intermediate transfer device 30 includes a drive roller 31 and
Four driven rollers 32, 33, 34 and 35, and an endless intermediate transfer belt 36 stretched around these rollers.
And have. The drive roller 31 is rotationally driven at a peripheral speed substantially the same as that of the photoconductor 140 because a gear (not shown) fixed to the end of the drive roller 31 meshes with the drive gear of the photoconductor 140. Therefore, the intermediate transfer belt 36 is exposed to light. It is designed to be circulated and driven in the direction of the arrow in the figure at a peripheral speed substantially the same as that of the body 140.

Between the driven roller 35 and the driving roller 31, the intermediate transfer belt 36 is tensioned by itself, and the photosensitive member 1 is driven.
The photoconductor 140 is arranged at a position where it is pressed against the photoconductor 40.
A primary transfer portion T1 is formed in a pressure contact portion between the intermediate transfer belt 36 and the intermediate transfer belt 36. The driven roller 35 is arranged near the primary transfer portion T1 on the upstream side in the circulation direction of the intermediate transfer belt.

An electrode roller (not shown) is arranged on the drive roller 31 via the intermediate transfer belt 36, and a primary transfer voltage is applied to the conductive layer of the intermediate transfer belt 36 via the electrode roller. The driven roller 32 is a tension roller, and biases the intermediate transfer belt 36 in its tension direction by a biasing means (not shown). Driven roller 3
A backup roller 3 forms a secondary transfer portion T2. The intermediate transfer belt 3 is attached to the backup roller 33.
The secondary transfer roller 38 is disposed so as to be opposed to each other with the sheet No. 6 interposed therebetween.
A secondary transfer voltage is applied to the secondary transfer roller so that the secondary transfer roller can come into contact with and separate from the intermediate transfer belt 36 by a peeling mechanism (not shown). The driven roller 34 is a backup roller for the belt cleaner 39. Belt cleaner 39
Can be contacted and separated from the intermediate transfer belt 36 by a contacting and separating mechanism (not shown).

The intermediate transfer belt 36 is a multi-layer belt having a conductive layer and a resistance layer formed on the conductive layer and pressed against the photoconductor 140. The conductive layer is formed on an insulating base made of synthetic resin, and a primary transfer voltage is applied to the conductive layer via the electrode roller described above. At the side edge of the belt, the conductive layer is exposed in a strip shape by removing the resistive layer in a strip shape, and the electrode roller comes into contact with the exposed portion.

During the process of circulating the intermediate transfer belt 36, the toner image on the photoconductor 140 is transferred onto the intermediate transfer belt 36 at the primary transfer portion T1, and the toner image transferred onto the intermediate transfer belt 36 is transferred. Is transferred to a sheet (recording material) S such as a sheet supplied between the secondary transfer portion T2 and the secondary transfer roller 38. The sheet S is fed from the sheet feeding device 502 and is fed to the secondary transfer portion T2 by the gate roller pair G at a predetermined timing. Reference numeral 51 is a paper feed cassette, and 52 is a pickup roller.

The toner image is fixed at the secondary transfer portion T2, and is discharged onto the sheet receiving portion 81 formed on the case 80 of the apparatus main body through the paper discharge path 70. Note that this image forming apparatus has two independent paper discharge paths 71 and 72 as the paper discharge path 70, and a sheet passing through the fixing device 60 passes through either paper discharge path 71 or 72. Is discharged. Further, the paper discharge paths 71 and 72 also constitute a switchback path, and when images are formed on both sides of the sheet, the sheet once entering the paper discharge path 71 or 72 passes through the return roller 73. The sheet is fed toward the secondary transfer portion T2 again.

The outline of the operation of the entire image forming apparatus as described above is as follows. (1) Print command signal (image forming signal) from a host computer or the like (personal computer or the like) not shown
Is input to the control unit 90 of the image forming apparatus, the photoconductor 1
40, each roller 11 of the developing device 10, and the intermediate transfer belt 36 are rotationally driven. (2) The outer peripheral surface of the photoconductor 140 is uniformly charged by the charging roller 160. (3) The exposure unit 40 selectively exposes L1 according to the image information of the first color (for example, yellow) on the outer peripheral surface of the uniformly charged photoconductor 140 to form an electrostatic latent image for yellow. To be done. (4) Only the developing roller of the developing device 10Y for the first color, for example, yellow, contacts the photoconductor 140, whereby the electrostatic latent image is developed, and the yellow toner image of the first color is the photoconductor. Formed on 140. (5) A primary transfer voltage having a polarity opposite to the charging polarity of the toner is applied to the intermediate transfer belt 36, and the toner image formed on the photoconductor 140 is transferred onto the intermediate transfer belt 36 at the primary transfer portion T1. It At this time, the secondary transfer roller 38 and the belt cleaner 39 move the intermediate transfer belt 36.
Away from. (6) After the toner remaining on the photoconductor 140 is removed by the cleaning unit 170, the removing unit 41
Then, the photoconductor 140 is neutralized by the slow electrical charge L2. (7) The above operations (2) to (6) are repeated as necessary. That is, the second color, the third color, and the fourth color are repeated according to the print command signal, and toner images according to the content of the print command signal are formed on the intermediate transfer belt 36 in an overlapping manner. (8) Sheet S from sheet feeding device 50 at a predetermined timing
Immediately before or after the leading edge of the sheet S reaches the secondary transfer portion T2 (in short, at the timing when the toner image on the intermediate transfer belt 36 is transferred to a desired position on the sheet S). The transfer roller 38 is the intermediate transfer belt 3
The toner image on 6 (basically a full-color image in which toner images of four colors are superimposed) is transferred onto the sheet S.
Further, the belt cleaner 39 contacts the intermediate transfer belt 36, and the toner remaining on the intermediate transfer belt 36 after the secondary transfer is removed. (9) The toner image on the sheet S is fixed by the sheet S passing through the fixing device 60, and then the sheet S is directed to a predetermined position (when the sheet S is not duplex printing, the sheet S is directed to the sheet receiving portion 81, and the duplex printing is performed. In this case, it is conveyed to the return roller 73 via the switchback path 71 or 72.

In the image forming apparatus according to the present invention, the photosensitive member 1
The developing roller 11 and the intermediate transfer medium 36 may be in contact with 40, or the developing may be a non-contact jumping method.

Since the toner particles of the present invention can be a stable negatively-charged dry toner, it is possible to form a uniform high-quality toner image without fog on the photoconductor, and to form a transfer material or a transfer medium. Transfer efficiency is improved, and the amount of transfer residual toner is extremely reduced. Further, the load on the cleaning unit is reduced, the waste toner container for cleaning can be made small, and the toner consumption amount can be reduced, so that the running cost can be reduced. Hereinafter, the present invention will be described in more detail with reference to examples.

[0071]

EXAMPLE A method for producing externally added particles such as complex oxide particles and a work function used in Example 1 will be described.

(Production of Composite Oxide Particles) FIG. 11 shows a burner device for producing composite oxide particles. 1 in the figure
Is a combustion chamber, 2 is a double jacket tube, 3 is an annular diaphragm, 4 is an inner tube, 5 is an outer tube, and 6 is a water-cooled flame tube. A double jacket tube 2 is projected into the combustion chamber 1, and hydrogen is supplied from the inner tube 4 of the double jacket tube 2 to 1.4 Nm ³ / h,
Air 5.5 Nm ³ / h and pre-evaporated gaseous Si
A mixed steam of 200 ° C. mixed at a rate of 1.30 kg / h of Cl ₄ was introduced, and the mixed steam of 3
2.34 kg / g of gaseous AlCl ₃ evaporated at 00 ° C.
At a rate of h, it is additionally supplied and introduced into the flame tube, and 12 Nm ³ / h of air is additionally supplied and burned. At this time, air is introduced into the combustion chamber, and air is additionally introduced from the annular diaphragm 3. In the flame, a rapid reaction between the produced water and chloride occurs to form composite oxide particles. After passing through the flame tube, the resulting powder is separated using a filter or cyclone, and
The hydrochloric acid content adhering to the powder is removed. The composition of the obtained composite oxide particles was 65% by weight of Al ₂ O _{3 and} 35% by weight of SiO ₂ , the average particle size of the primary particles was 14 nm, the BET specific surface area was 74 m ² / g, and the volume resistivity was 10 ¹² Ω · cm. Is. The obtained composite oxide particles are treated with dimethylsilane (DM
Hydrophobic treatment by S).

The data obtained by measuring the work function of the obtained composite oxide particles using a surface analyzer (AC-2, manufactured by Riken Keiki Co., Ltd.) with an irradiation light amount of 500 nW is shown in FIGS.
1 and 2 are diagrams for explaining that two types of work functions are obtained, and are the same measurement data.

(SiO ₂ particles-1) Hexamethyldisilazane (H 2
Hydrophobized by MDS). Data similarly measured using a surface analyzer is shown in FIG.

(SiO ₂ particles-2) Hexamethyldisilazane (H
Hydrophobized by MDS). The data similarly measured by the surface analyzer is shown in FIG.

(Al ₂ O ₃ particles) Vapor phase method alumina particles (average particle diameter 13 nm). The data similarly measured by the surface analyzer is shown in FIG.

(Mixed product of SiO ₂ particles and Al ₂ O ₃ particles, mixed oxide particles-1) Alumina particles of vapor phase method (average particle diameter 13 nm) and silica particles of vapor phase method (average particle diameter 12 n
m) was mixed with the hexamethyldisilazane (HMDS) treated product at 65:35 (weight ratio) by dry mixing, and then at room temperature 25 ° C.
Data similarly measured by a surface analyzer for a product left for 24 hours at a humidity of 55% are shown in FIGS. 6 and 7. 6,
FIG. 7 is a diagram for explaining that two types of work functions are obtained, and the same measurement data.

(Mixed product of SiO ₂ particles and Al ₂ O ₃ particles, mixed oxide particles-2) Alumina particles of vapor phase method (average particle diameter 13 nm) and silica particles of vapor phase method (average particle diameter 40 n)
m) was mixed with the hexamethyldisilazane (HMDS) treated product at 65:35 (weight ratio) by dry mixing, and then at room temperature 25 ° C.
8 and 9 show the data similarly measured by a surface analyzer for a product left for 24 hours at a humidity of 55%. 8 and 9 are diagrams for explaining that two types of work functions can be obtained, and are the same measurement data.

The work functions of the externally added particles obtained from FIGS. 1 to 9 are summarized in Table 1 below.

[0080]

[Table 1]

SiO ₂ particles-1, SiO ₂ particles-2, A
The l ₂ O ₃ particles show only one work function, but in the case of the mixed oxide particles-1, the mixed oxide particles-2, and the composite oxide particles, they have two kinds of work functions, and It can be seen that the work function difference in the composite oxide particles is larger than the work function difference in the mixed oxide particles.

Next, a manufacturing example or a manufacturing method of the toner 1, the organic photoconductor, the developing roller, and the transfer medium used in this embodiment will be described. In addition, "part" in an Example shows a weight part.

(Production Example of Toner 1) Styrene Monomer 8
A monomer mixture consisting of 0 parts, 20 parts butyl acrylate, and 5 parts acrylic acid was added to an aqueous mixture of 105 parts water, 1 part nonionic emulsifier, 1.5 parts anionic emulsifier, and 0.55 parts potassium persulfate. Polymerization was carried out at 70 ° C. for 8 hours with stirring in a nitrogen stream. After the polymerization reaction, the mixture was cooled to obtain a milky-white resin emulsion having a particle size of 0.25 μm.

Next, 200 parts of this resin emulsion and polyethylene wax emulsion (manufactured by Sanyo Kasei Co., Ltd.)
20 parts, phthalocyanine blue 7 parts, and a surfactant containing 0.2 parts of sodium dodecylbenzenesulfonate, and dispersed in water. Diethylamine was added to adjust the pH to 5.
After adjusting to 5, while stirring, aluminum sulfate as an electrolyte was added.
3 parts were added, and then the mixture was stirred with a TK homomixer at high speed for dispersion.

Further, 40 parts of styrene monomer, 10 parts of butyl acrylate, and 5 parts of zinc salicylate were added together with 40 parts of water, and the mixture was heated to 90 ° C. under stirring in a nitrogen stream in the same manner, and hydrogen peroxide was added. Polymerization was carried out for 5 hours to grow particles. After termination of the polymerization, the pH was adjusted to 5 or higher to raise the bonding strength of the associated particles, the temperature was raised to 95 ° C., and the temperature was maintained for 6 hours. Then, the obtained particles were washed with water and vacuum dried at 45 ° C. for 10 hours. The obtained cyan toner mother particles had an average particle size of 6.8 μm and a circularity of 0.98.

Hydrophobic silica surface-treated with hexamethyldisilane (HMDS) in a weight ratio to the toner mother particles (average particle diameter 12 nm, specific surface area 140 / m ² /
g) 0.5% by weight, and 0.5% of hydrophobic silica (average particle size 40 nm, specific surface area 45 m ² / g) subjected to the same treatment.
Toner 1 was prepared by adding it in a weight percentage. Toner 1 obtained
When the work function of is measured using a surface analyzer (AC-2 type, manufactured by Riken Keiki Co., Ltd.) with an irradiation light amount of 500 nW,
It was 5.58 eV.

(Production Example of Organic Photoreceptor (OPC1)) Seamless thickness as conductive support is 40 μm and diameter is 85.5.
6 parts by weight of alcohol-soluble nylon (“CM8000” manufactured by Toray Industries, Inc.) as an undercoat layer and 4 parts by weight of aminosilane-treated titanium oxide fine particles were dissolved and dispersed in 100 parts by weight of methanol in a nickel electroformed tube of mm. The coating liquid thus obtained was applied by a ring coating method and dried at a temperature of 100 ° C. for 40 minutes to form an undercoat layer having a film thickness of 1.5 to 2 μm. On this undercoat layer, 1 part by weight of oxytitanium phthalocyanine as a charge generating pigment, butyral resin (BX-
1 part by weight of Sekisui Chemical Co., Ltd. and 100 parts by weight of dichloroethane were dispersed in a sand mill using glass beads of φ1 mm for 8 hours. The obtained pigment dispersion was applied by a ring coating method and dried at 80 ° C. for 20 minutes to form a charge generation layer having a thickness of 0.3 μm. On this charge generation layer, 40 parts by weight of a charge transporting material of a styryl compound represented by the following structural formula (1) and 60 parts by weight of a polycarbonate resin (Panlite TS, Teijin Chemicals Ltd.) were added to toluene 40 parts.
An organic photoreceptor (OP) having a photosensitive layer composed of two layers is prepared by dissolving in 0 part by weight, coating by a dip coating method to a dry film thickness of 22 μm, and drying to form a charge transport layer.
C1) was produced. A part of the obtained organic photoreceptor is cut out to form a sample piece, and its work function is measured by a surface analyzer (AC-
Type II, manufactured by Riken Keiki Co., Ltd., irradiation light amount 500 nW
It showed 5.48 eV.

[0088]

[Chemical 1]

(Production of Developing Roller) The surface of an aluminum pipe having a diameter of 18 mm was plated with nickel (thickness: 23 μm) to obtain a surface having a surface roughness (Ra) of 4 μm. The work function of the surface of the developing roller was measured and found to be 4.58 eV.

(Production Example of Transfer Medium) 30 parts by weight of vinyl chloride-vinyl acetate copolymer, 10 parts by weight of conductive carbon black and 70 parts by weight of methyl alcohol were placed on a polyethylene terephthalate resin film having a thickness of 130 μm and aluminum was vapor deposited. The uniform dispersion liquid of was coated and dried by a roll coating method so as to have a thickness of 20 μm to form an intermediate conductive layer. Then, on the intermediate conductive layer, 55 parts by weight of a nonionic water-based urethane resin (solid content 62%),
Polytetrafluoroethylene emulsion resin (solid content 60%) 11.6 parts, conductive tin oxide 25 parts by weight, polytetrafluoroethylene fine particles (max particle diameter 0.3 μ
m or less) 34 parts by weight, 5 parts by weight of polyethylene emulsion (solid content 35%) and 20 parts by weight of ion-exchanged water are mixed and dispersed so as to have a thickness of 10 μm and similarly dried by roll coating. Then, a transfer layer was formed. This coating sheet was cut to a length of 540 mm, the coated surface was faced up, the ends were aligned, and ultrasonic welding was performed to produce a transfer belt. The volume resistance of this transfer belt is
It was 2.5 × 10 ¹⁰ Ω · cm. The work function was 5.37, and the normalized photoelectron yield was 6.90.

(Example 1) For the toner 1 obtained above, SiO ₂ particles-1 and Si of the externally added particles produced above were used.
O ₂ particles-2, Al ₂ O ₃ particles, mixed oxide particles-1,
The mixed oxide particles-2 and the composite oxide particles were respectively adjusted to 0.
Add and mix 5% by weight using a commercial blender,
Toner 1-1 to Toner 1-6 were prepared.

As the full-color printer shown in FIG. 10, the developing roller, the organic photoconductor and the transfer medium produced as described above are mounted to be a contact developing type, and each toner is put in a cyan developing device to obtain a solid image density of about 10%. Imaged so as to be 1.3. The image forming conditions were dark potential −600 V, bright potential −100 V, developing bias −200 V, supply roller and developing roller having the same potential, and primary transfer voltage +300 V.

The transfer efficiency to the photoconductor and the amount of fog on the photoconductor were determined by the tape transfer method, and Table 2 is shown. Further, when a solid image is formed in the same manner for the first color and then a white solid image for the second color is formed, the first color reversely transferred onto the photoconductor corresponding to the non-image portion corresponding to the white solid image. The cyan toner was determined as the reverse transfer toner density by the tape transfer method, and is also shown in Table 2.

In the tape transfer method, a mending tape manufactured by Sumitomo 3M is attached onto the toner existing on the photoconductor,
The tape before and after attachment was adhered to a white paper, the reflection density was measured, the reflection density of the tape was subtracted from the value, and the obtained value was taken as the reflection density of the fog and the reverse transfer toner. The transfer efficiency was determined by attaching a tape to the toner existing on the photoconductor before and after the transfer, measuring the weight of the tape, and calculating from the weight difference.

[0095]

[Table 2]

As in Toner 1-1 to Toner 1-3, silica particles alone as externally added particles, or toner particles in which alumina particles are externally added to toner particles in which silica particles are externally added to toner mother particles, Toner 1-4, Toner 1-
As shown in No. 5, toner particles obtained by externally adding silica particles to the toner mother particles and externally added external additive particles obtained by dry-mixing alumina particles and silica particles in advance were shown to have less fog. However, it was shown that the reverse transfer toner was more than the silica alone toner. On the other hand, with the toner 1-6 of the present invention, both the fog and the reverse transfer toner were reduced, and at the same time, the transfer efficiency could be improved.

Example 2 Toner 1 prepared in Example 1
On the other hand, composite oxide particles (65% by weight of Al ₂ O ₃ and SiO ₂ 3) that have been subjected to a hydrophobic treatment with dimethylsilane (DMS).
5% by weight, the average particle diameter of primary particles was 17 nm, and the BET specific surface area was 110 m ² / g) were externally added in the proportions shown in Table 3 below to produce toner particles. While measuring the work function of each toner particle, each toner was loaded in the cyan developing device of the full-color printer shown in FIG. 10 as in Example 1, 10% printing with 5% duty was performed, and then the developing roller was removed. , E-SPART II of Hosokawa Micron Co., Ltd.
The results measured using "I" are shown at the same time.

[0098]

[Table 3]

It can be seen that as the external additive of the present invention is added, the average charge amount increases or does not change so much, but the positively charged toner amount decreases. This indicates that fogging is likely to be reduced, and at the same time, the reverse transfer toner amount is also likely to be reduced.

(Example 3) (Production Example of Toner 2) The toner 1 was changed to quinacridone as the pigment in Toner 1, and the temperature for raising the association of the secondary particles and the film-forming bond strength was maintained at 90 ° C. Was similarly prepared. This magenta toner had an average particle diameter of 6.9 μm and a circularity of 0.97. The same kind and amount of the external additive as in the toner 1 were added to this toner, and 0.5% of the hydrophobic alumina-silica composite oxide fine particles of the present invention was further added and mixed. The work function of Toner 2 was measured and found to be 5.67 eV.

(Production Example of Organic Photoreceptor (OPC2)) In the organic photoreceptor (OPC1), the diameter of the conductive support is 8 mm.
An organophotoreceptor (2) was prepared in the same manner except that a 5.5 mm aluminum tube, titanyl phthalocyanine as a charge generating pigment, and a distyryl compound (2) represented by the following structural formula (2) were used as the charge transport material. The work function of this organic photoreceptor was 5.50 eV.

[0102]

[Chemical 2]

As the full-color printer shown in FIG. 10, when the developing roller prepared in Example 1 and the transfer medium are mounted and the contact developing type is used, OPC1 is used.
In the case of the non-contact developing system, OPC2 was attached, and toner 2 was put in the magenta developing device, and images were formed by the contact developing system and the non-contact developing system so that the solid image density was about 1.3. The image forming conditions are as follows: dark potential −600 V, bright potential −100 V, developing bias −20 in the case of the contact developing method.
0 V, the supply roller and the developing roller have the same potential, the primary transfer voltage +300 V, and in the case of the non-contact developing method, the gap roller is attached to both ends of the developing roller so that the developing gap is 210 μm, and the DC developing bias is −350 V. The superposed AC was applied under the condition of PP voltage of 1400V, and other conditions were the same as in the contact development system.

In the case of the contact developing method, the fog OD value, the reverse transfer toner OD value, and the transfer efficiency (%) were measured in the same manner as in Example 1, and the results are shown in Table 4. Similarly, in the case of the non-contact developing method, shown in Table 5.

[0105]

[Table 4]

[0106]

[Table 5]

As can be seen from Tables 4 and 5, fog and reverse transfer toner are decreased and transfer efficiency is improved by adding the externally added particles of the present invention.

Example 4 (Production Example of Toner 3) Polycondensation polyester of aromatic dicarboxylic acid and alkylene etherified bisphenol A and partially crosslinked product of polycondensation polyester with polyvalent metal compound 50:50 ( Weight ratio) Mixture (Sanyo Chemical Co., Ltd.)
Made of 100 parts cyan cyan pigment phthalocyanine blue 5
Part, 3 parts of polypropylene having a melting point of 152 ° C. and Mw of 4000 as a release agent, and salicylic acid metal complex E-81 (manufactured by Orient Chemical Industry Co., Ltd.) as a charge control agent 4
After uniformly mixing the parts using a Henschel mixer, the internal temperature 1
Kneading with a twin-screw extruder at 50 ° C., the cooled product was roughly crushed to 2 mm square or less, then finely crushed with a turbo mill, and classified with a classifier by rotating a rotor to obtain a circularity of an average particle size of 7.5 μm, 0.925. Cyan toner mother particles were obtained. To the toner base particles, 0.5% of each of the two types of hydrophobic silica used in Toner 1 was added, and 0.5% of the composite oxide fine particles subjected to the hydrophobic treatment was added and mixed to prepare Toner 3. When the work function of Toner 3 was measured, it was 5.47e.
It was V.

(Production Example of Toners 4, 5 and 6) Toner 4 (using quinacridone as a magenta toner pigment), Toner 5 (using Pigment Yellow 180 as a yellow toner pigment) and Toner 6 (using carbon black as a black toner pigment) was prepared. The average particle diameter and the circularity of the manufactured toners are almost the same as those of the toner 3, and the work functions of the respective toners are 5.66 eV (magenta) and 5.63.
It was eV (yellow) and 5.72 eV (black).

Toners 3 to 6 of each color are used and a full-color original document (duty of each color 5
%) Was printed on 10,000 sheets, and the first sheet and the 10,000th sheet were compared. As a result, there was no deterioration in image quality and no toner scattering in the apparatus, and the toner had stable toner charging characteristics. Also, when using four types of toner colors,
When the total weight of the container containing the cleaning toner was measured, it was 96 g, and it was confirmed that the amount of toner to be cleaned was small. The total collected weight corresponds to 34% of the planned cleaning toner capacity of the photoconductor portion, and the collected toner amount could be suppressed.

[0111]

The negatively charged dry toner of the present invention is a negatively charged dry toner obtained by externally adding aluminum oxide-silicon dioxide composite oxide particles obtained by a flame hydrolysis method to toner mother particles. It is excellent in uniformity of electrified charge, has less fog, and can improve transfer efficiency. Also, transfer efficiency to a transfer material or transfer medium is improved, and the amount of toner remaining after transfer is extremely small. Become. Further, the load on the cleaning unit is reduced, the waste toner container for cleaning can be made small, and the toner consumption amount can be reduced, so that the running cost can be reduced.

[Brief description of drawings]

FIG. 1 is a diagram for explaining that two types of work functions can be obtained from data obtained by measuring a complex oxide particle according to the present invention using a surface analyzer.

FIG. 2 is a diagram for explaining that two types of work functions can be obtained with the same data as in FIG.

FIG. 3 SiO ₂ particles (average particle size 12
nm) is data measured using a surface analyzer.

FIG. 4 SiO ₂ particles (average particle diameter 40
nm) is data measured using a surface analyzer.

FIG. 5 is data obtained by measuring Al ₂ O ₃ particles, which are externally added particles, using a surface analyzer.

FIG. 6 is data obtained by using a surface analyzer to measure mixed oxide particles-1 that is a mixture of externally added particles SiO ₂ particles and Al ₂ O ₃ particles.

FIG. 7 is a diagram for explaining that two types of work functions can be obtained with the same data as in FIG.

FIG. 8 is data obtained by using a surface analyzer to measure mixed oxide particles-2, which is a mixture of externally added particles SiO ₂ particles and Al ₂ O ₃ particles.

FIG. 9 is a diagram for explaining that two types of work functions can be obtained with the same data as in FIG.

FIG. 10 is an explanatory diagram showing an example of a rotary type full-color printer used in the present invention.

FIG. 11 is a burner device for producing composite oxide particles according to the present invention.

[Description of Reference Signs] 1 is a combustion chamber, 2 is a double jacket tube, 3 is an annular diaphragm, 4 is an inner tube, 5 is an outer tube, 6 is a water-cooled flame tube, 10 is a developing device, 30 is an intermediate transfer device, 40 Is an exposure unit, 5
0 is a paper feeding device, 60 is a fixing device, 70 is a paper discharge path, and 10
Reference numeral 0 is an image carrier cartridge, 140 is an electrophotographic photosensitive member (latent image carrier), 160 is a charging roller, and 170 is a cleaning means.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G03G 9/08 361

Claims (10)

[Claims] 1. A negatively charged dry toner comprising externally added aluminum oxide-silicon dioxide composite oxide particles and silicon dioxide fine particles obtained by a flame hydrolysis method to toner mother particles. 2. The aluminum oxide-silicon dioxide composite oxide particles obtained by the flame hydrolysis method have a primary particle diameter of 7 to 80 nm, and 20 nm or more on a number basis are 30% or more. The negatively charged dry toner according to claim 1. 3. Aluminum oxide-silicon dioxide composite oxide particles obtained by the in-flame hydrolysis method are 5.0 to 5.
4. The negative charge dry system according to claim 1, which shows two types of work functions, a first work function in the range of 4 and a second work function in the range of 5.4 to 5.7. toner. 4. The aluminum oxide-silicon dioxide composite oxide particles are added in a proportion of 0.1 to 3% by weight with respect to the toner mother particles. 5. The negatively charged dry toner according to item 3. 5. The negatively charged dry toner according to claim 1, wherein the toner mother particles are made of polyester resin. 6. The negatively charged dry toner according to claim 1, wherein the toner mother particles are made of a styrene-acrylic copolymer resin. 7. The negatively charged dry toner according to claim 1, wherein the negatively charged dry toner has a circularity of 0.94 or more. 8. The toner mother particles are polymerized toners,
8. The negatively charged dry toner according to claim 7, wherein the number of particles of the negatively charged dry toner is 50% and the particle diameter is 8 μm or less. 9. The negatively charged dry toner according to claim 1, wherein the negatively charged dry toner is a full color toner. 10. The negatively charged dry toner according to claim 1, wherein the negatively charged dry toner is subjected to reversal development.