JPH10186723A - Color two-component developer and multicolor image forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an image of high picture quality without making toner particle diameters too small by setting the relation between the weight of a toner on an image support and the level of picture quality to a specific range, controlling the particle diameters and the particle diameter distribution of the toner to specific ranges, adding an additive, and controlling a carrier configuration. SOLUTION: A color toner has average particle diameters of 3 to 9μm, and its particle diameter distribution satisfies formulae: D16v/D50v<=1.457-0.036×D50v and D50p/D84p<=1.45. The color toner has two kinds of inorganic oxide particles as additives, the additive with the greater average particle diameter covering the surfaces of toner particles by 10% or more to the total specific surface area of the toner particles, and the additive with the smaller average particle diameter covering the surfaces of the toner particles by 20% or more. In the formula, D16v and D50v represent volume average diameters (μm) at 16% and 50%, respectively, calculated from the large diameter side of average volume particle diameters, and D50p and D84p represent number average particle diameters (μm) at 50% and 84%, respectively, calculated from the large diameter side of number average diameters.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multicolor image forming method used in a copying machine and a printer utilizing or applying electrophotography and a full-color developer used therefor, and more particularly to a latent image using a laser beam. The present invention relates to a multi-color image forming method applied to a digital copying machine for forming an image and a full-color developer used for the method.

[0002]

2. Description of the Related Art Conventionally, in electrophotography, a magnetic brush method has been widely used as a method for visualizing an electrostatic latent image formed on a photoconductive photoreceptor using toner.
In recent years, a method of visualizing an electrostatic latent image by forming a thin toner layer on a developing roll, such as a non-magnetic one-component developing method, has also been put to practical use. As a toner used in these methods, a mixture of a binder resin and a colorant is generally used. The toner image formed on the photoconductive photoreceptor by the above method or the like is transferred onto a support such as paper and fixed by pressure and / or heating. recent years,
In copiers or printers utilizing or applying electrophotographic technology, there is a growing demand for high image quality.
Various improvements have been made. In particular, it is often practiced to improve the image quality by faithfully reproducing a miniaturized electrostatic latent image by reducing toner particles as a developer. For example, Japanese Patent Application Laid-Open No. 62-103675
Japanese Patent Application Laid-Open No. 2-13-13 proposes a toner having an average particle diameter of 7 to 14 μm.
Japanese Patent No. 2459 proposes a device having a sharp particle size distribution.

[0003] By the way, generally, when the particle size distribution becomes wide,
The chargeability of the developer decreases with the number of prints, and the life of the developer tends to be shortened. This is because the large particle diameter toner is developed and the small particle diameter toner stays in the developing device for a long time. Therefore, the sharper the particle size distribution of the toner, the better, but there are limitations in terms of manufacturing problems and costs. Further, even in the toner described in the above-mentioned publication, a high-quality image cannot be obtained because a large particle diameter side or a small particle diameter side includes a broad toner. In the case of JP-A-13259, there is a problem that the life of the developer is short because fine powder having a small particle diameter is contained.

In Japanese Patent Application Laid-Open No. 60-136775, a combination of hydrophobic titania and hydrophobic silica has been attempted in order to achieve both improvement in fluidity and environmental stability of charging. However, when a small particle size color toner is used, the transferability is poor and a stable image cannot be obtained simply by mixing them.

On the other hand, in JP-A-4-24653, JP-A-3-226563, and the like, a carrier resistance is specified in order to prevent leakage of an electrostatic latent image and improve developability. However, when a small particle size carrier is used for the purpose of high image quality, high image quality cannot be obtained simply by specifying the carrier resistance.

[0006]

SUMMARY OF THE INVENTION Accordingly, the present invention has been made to solve the above-mentioned problems in the prior art. That is, the object of the present invention is:
An object of the present invention is to provide a color two-component developer capable of obtaining a high-quality image without extremely reducing the toner particle diameter. Another object of the present invention is to provide a color two-component developer in which a toner image on an electrostatic latent image can form a good transfer image to obtain a high-quality image. Still another object of the present invention is to provide a multicolor image forming method capable of obtaining a full-color high-quality image.

[0007]

The present inventors have solved the above-mentioned problem by forming a multicolor image by setting the relationship between the toner weight on the image support and the image quality level in a specific range. And a full-color developer capable of obtaining a high-quality image by controlling the toner particle diameter and the particle size distribution to specific ranges, and controlling the external additive formulation and the carrier morphology. Was completed.

That is, the multicolor image forming method of the present invention comprises:
Forming a latent image on the latent image holding member, forming a toner image on the latent image holding member using a developer on a developer carrier, directly or indirectly transferring the toner image to an image support; And a step of fixing the toner image on the image support by heat and pressure, the image having a volume average particle diameter of toner particles [D50v] (μm) and a maximum density of a single color. Weight of toner on support [TMA] (mg / cm
² ) is developed and transferred so as to satisfy the relationship of the following formula (6). ρ × (4/3) πr ³ × (k / r ³ ) ^2/3 /10−0.10≦[TMA]≦ρ×(4/3)πr ³ × (k / r ³ ) ^2/3 / 10 + 0.25 (6) (where ρ is the specific gravity of the toner, π is the pi, r is the volume average particle radius (unit μm) of the toner particles, and k = 0.144.
Represents )

Further, the color two-component developer of the present invention comprises:
The toner comprises a color toner, that is, a yellow toner, a magenta toner, a cyan toner, a black toner, and a carrier. The color toner has an average particle size of 3 to 9 μm, and its particle size distribution is represented by the following formulas (1) and (2). The color toner has two types of inorganic oxide fine powders as external additives, and the external additive having a larger average particle diameter is 10% of the total specific surface area of the toner particles. % Of the toner particle area, and the external additive having the smaller average particle diameter covers the toner particle surface by 20% or more based on the total specific surface area of the toner particles, and the total coating amount of these two types of external additives Is 50% or more based on the total specific surface area of the toner particles, the carrier is obtained by coating magnetic particles with a resin, and the magnetic particles have an average particle diameter of 30 to 50 μm and a particle diameter of 33 μm to 44 μm The particles 50% by weight or more, are those containing the following particle diameter 22 .mu.m 40% by weight or less, and the carrier, the saturation magnetization at 3000 Oe, residual magnetization and coercive force, respectively 50em
u / g or more and 5 emu / g or less and 20 Oe or less, and the resistance of the magnetic brush developer layer of the developer per unit length in the sleeve longitudinal direction is 6.2 × under the electric field strength of 0.4 V / μm. 10 ^{4 to} 6.2 × 10 ⁸ Ω, 2.0 V
6.2 × 10 ⁴ to 6.2 × 10 ⁶ under an electric field strength of / μm.
Ω range. D16v / D50v ≦ 1.457−0.036 × D50v (1) D50p / D84p ≦ 1.45 (2) (in the formula, D16v is the 16% volume particle diameter calculated from the large particle side of the volume average particle diameter) (Μm), D50v is the 50% volume average particle diameter (μm) calculated from the large particle side of the volume particle diameter.
m), D50p is 50 calculated from the large particle side of the number particle diameter.
% Number average particle diameter (μm) and D84p represent the 84% number particle diameter (μm) calculated from the larger particle side of the number particle diameter. )

In the above multicolor image forming method of the present invention,
It is preferable to use the two-component color developer of the present invention since a higher quality color image can be obtained.

In the two-component color developer of the present invention, the colorant amount C (% by weight) in the toner is preferably represented by the following formula (3). 22 / D50v ≦ C ≦ 43 / D50v (3)

Further, it is preferable that the melt viscosity of the toner particles is represented by the following formulas (4) and (5). 1 × 10 ⁵ ≦ η (90 ° C.) ≦ 1 × 10 ⁶ (4) 1 × 10 ⁴ ≦ η (100 ° C.) ≦ 1 × 10 ⁵ (5) (where η (90 ° C.) and η (100 ° C.) ) Is the melt viscosity of the toner at 90 ° C. and 100 ° C. (Pa ·
s). )

Further, the two types of inorganic oxide fine powder added as external additives are preferably silica and titania, and the average particle size of silica is larger than the average particle size of titania. Is preferred. Further, it is preferable that the titania is a titanium compound having a specific gravity of 2.8 to 3.6 obtained by partially or completely reacting TiO (OH) ₂ produced by a wet method with a silane compound.

The carrier is preferably one in which magnetic particles are coated with a fluorine-containing matrix resin in which carbon black and crosslinked resin particles are dispersed. Further, the carrier is preferably coated with a fluorine-containing matrix resin in which basic carbon black and basic crosslinked resin particles are dispersed.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, a multicolor image forming method of the present invention will be described. Forming a latent image on the latent image holding member, forming a toner image on the latent image holding member using a developer on a developer carrier, directly or indirectly transferring the toner image to an image support; And fixing the toner image on the image support by heat and pressure. FIG. 1 is a schematic configuration diagram of a color image forming apparatus that performs the multicolor image forming method of the present invention.

A charging device 102, a rotary developing device 103, a transfer drum 1 are provided around a photoreceptor 101 rotating in the direction of the arrow.
04, a cleaner 105, a pre-exposure device 106, a potential sensor 108, and the like. The photoconductor 101 is uniformly charged by the charger 102 in a dark portion. R (red), G (green), B (blue) supplied from the image input device 110 and the like
The density signal of each color is converted into a Y signal by the color conversion processing circuit 140.
(Yellow), M (magenta), C (cyan), and K (black) are converted into density signals of the respective colors, and the light beam scanning device 120 causes the photosensitive member 1 to change in accordance with the converted density signals.
01 is performed to form an electrostatic latent image. The light beam scanning device 120 includes a semiconductor laser 121, a collimator lens 122, a polygon mirror 123, and the imaging optical system 12.
4. The photoreceptor 101 is scanned by the light beam which is configured by the light beam pulse width conversion (PWM) circuit 130 and the like, and converted into the pulse width signal corresponding to the density by the light beam PWM circuit 130.

The rotary developing device 103 includes yellow, cyan,
It is composed of four developing devices each having magenta and black toners. In this example, each developer is
A reversal development method using two-component magnetic brush development is employed. As appropriate, the rotary developing device 103 rotates to develop the electrostatic latent image with a desired toner. An alternating electric field is applied to the rotary developing device 103 by a developing bias circuit (not shown). The developing bias circuit includes a high-voltage AC power supply for supplying an AC bias and a high-voltage DC power supply for supplying a DC bias.

The transfer drum 104 rotates with a recording material mounted on the outer periphery. The developed toner image on the photoconductor is transferred to the recording material 107 for each color by the transfer charger 104b, and a multicolor toner image is formed on the recording material. In addition, 1
04a is a recording material absorbing charger, 104c is a peeling charger, 104d is a peeling claw, and 104e is a charge removing charger.

In this image forming apparatus, an electrostatic latent image is formed in the order of black, yellow, magenta, and cyan.
Development and transfer are respectively performed. The toner image on the transfer material formed by development is black, yellow, magenta,
It has a structure in which toner images of cyan colors are superimposed, and a black toner image is the lowermost layer. The transfer material on which the toner image obtained by these steps is transferred is separated from the transfer drum 104 by the peeling claw 104d.
The image is fixed by the fixing device 109 to form a multicolor image.

In the present invention, the weight [TMA] of the toner on the image support needs to satisfy the relationship of the following formula (6), in which case a good image can be obtained. ρ × (4/3) πr ³ × (k / r ³ ) ^2/3 /10−0.10≦[TMA]≦ρ×(4/3)πr ³ × (k / r ³ ) ^2/3 / 10 + 0.25 (6) (ρ is the specific gravity of the toner, π is the pi, r is the volume average particle radius of the toner particles (unit: μm), k = 0.144) In the present invention, the weight of the toner on the image support [TMA] =
ρ × (4/3) πr ³ × (k / r ³ ) ^2/3 / 10 means that the toner is a sphere using the volume average particle radius (unit: μm) of the particle size measuring device. And the weight of the toner on the image support when the toner layer is formed by filling the toner in a single layer hexagonally on the image support. The toner weight [TMA] on the image support is ρ × (4/3) πr ³ × (k /
If r ³ ) ^2/3 /10−0.10, the digital latent image such as a line or a halftone dot cannot be covered with a single layer, and the image will be rough, and ρ × (4 / 3) πr
If it is larger than ³ × (k / r ³ ) ^2/3 /10+0.25, toner scatters between lines, or between halftone dots, causing gradation and granularity. Sex is impaired.

The particle size in the present invention is a value measured using a Coulter counter TA-II as a particle size measuring device.

In the present invention, in order to make the weight of the toner [TMA] on the image support satisfy the relationship of the above formula (6), specifically, by controlling the developing electric field or the toner charge amount. And the weight of the toner can be changed.

Next, the two-component color developer in the present invention will be described. The color toner, which is a component of the two-component color developer, needs to have an average particle diameter in a range of 3 to 9 μm and a particle size distribution satisfying the following formulas (1) and (2). There is. D16v / D50v ≦ 1.457−0.036 × D50v (1) D50p / D84p ≦ 1.45 (2) (in the formula, D16v is the 16% volume particle diameter calculated from the large particle side of the volume average particle diameter) , D50v is the 50% volume average particle diameter calculated from the larger particle side of the volume particle diameter, D50
p represents the 50% number average particle diameter calculated from the large particle side of the number particle diameter, and D84p represents the 84% number particle diameter calculated from the large particle side of the number particle diameter. (Unit: μm) When the particle diameter of the toner particles is smaller than 3 μm, fogging occurs, and when the particle diameter is larger than 9 μm, the image quality is rough. When D16v / D50v does not satisfy the relationship of the expression (1), the image quality becomes rough, and when D16v / D50v does not satisfy the expression (2), the life of the developer is remarkably reduced.

In the present invention, the color toner contains two types of surface-treated inorganic oxide fine powders as external additives, and the external additive having a larger average particle diameter is used for the toner particles. 10% or more of the total specific surface area of the toner particles is covered, and the external additive having the smaller average particle size covers 20% or more of the total specific surface area of the toner particles. It is necessary that the total coating amount of the various external additives is 50% or more based on the total specific surface area of the toner particles. When the coating amount of the external additive having the larger average particle diameter is less than 10%, the development transferability is deteriorated. When the coating amount of the external additive having the smaller average particle diameter is less than 20%, the powder flow is reduced. Worse. In the present invention, the external additive having a larger average particle diameter preferably has a particle diameter of 30 to 100 nm, and the external additive having a smaller average particle diameter preferably has a particle diameter of 5 to 30 nm. Further, by setting the total coating amount of the external additive to 50% or more of the total specific surface area of the toner particles, a long-term stable image can be obtained. The coating amount of the external additive on the surface of the toner particles is determined by the following formula based on the weight average particle diameter D50v of the toner obtained by the Coulter counter, the average particle diameter d (nm) of the external additive obtained by observation with an electron microscope, and the specific gravity thereof. Can be obtained by Coverage% = 0.756 × D50v × ρt ÷ d ÷ ρa × C
× 100 (where ρt and ρa are the specific gravity of the toner and the specific gravity of the external additive, and C is a value obtained by dividing the external additive weight by the toner weight.)

In the present invention, the carrier as a component of the two-component color developer is obtained by coating magnetic particles with a resin, and the magnetic particles have an average particle size of 30 to 5 particles.
0 μm and particles having a particle diameter of 33 μm to 44 μm
0% by weight or more and particles having a particle size of 22 μm or less
It is necessary to be less than the weight%. As a result, a proper charge amount and proper developer fluidity can be provided. The carrier has saturation magnetization, residual magnetization and coercive force at 3000 Oe of 5
It is necessary to be 0 emu / g or more, 5 emu / g or less and 20 oersted or less, and preferably in the range of 55 to 90 emu / g, 0 to 3 emu / g, and 0 to 10 oersted, respectively. Things. Further, the carrier needs to have an electric resistance value of 10 ⁸ Ωcm to 10 ¹¹ Ωcm after being coated with the resin.
If the saturation magnetization is smaller than 50 emu / g, the carrier is developed and defects such as white spots occur.
When the residual magnetization is larger than 5 emu / g and when the coercive force is larger than 20, the chargeability of the additional toner deteriorates, and fogging occurs.

Further, the carrier according to the present invention has a resistance (hereinafter referred to as "electric resistance") per unit length in the sleeve longitudinal direction of the magnetic brush developer layer at a toner concentration at which an appropriate development weight is obtained. 6.2 × 10 ⁴ to 6.2 × 10 ⁸ Ω under an electric field strength of 0.4 V / μm;
6.2 × 10 ⁴ to 6.2 × 1 under an electric field strength of 0 V / μm
It is necessary to be in the range of 0 ⁶ Ω. The electric resistance value of the carrier in the present invention is the electric resistance in the actual developing nip configuration, and a magnetic brush is formed on the developing sleeve, and an aluminum pipe having the same size as the photoconductor is arranged in the same arrangement as the actual developing nip. The resistance obtained by applying a DC voltage between the sleeve and the aluminum pipe as described above and flowing current is divided by the length (unit: cm) of the sleeve covered with the developer. By controlling the resistance of the developer layer within the above range, it is possible to prevent image omission and generation of brush marks in a region from a low density portion to a high density portion. When the resistance under an electric field strength of 0.4 V / μm is higher than 6.2 × 10 ⁸ Ω, the trailing edge of a solid image portion, particularly a low density portion, becomes noticeable, and
It becomes lower than 0 ⁴ Omega, brush marks are generated. The resistance under an electric field strength of 2.0 V / μm is 6.2 × 10
^If it is higher than ⁶ Ω, the halftone trailing edge dropout becomes noticeable at the boundary where the halftone and the solid image are in contact,
When it is lower than 6.2 × 10 ⁴ Ω, brush marks are similarly generated.

The color toner particles in the present invention are mainly composed of a binder resin and a colorant, and known ones can be used. Typical binder resins include polyester, polystyrene, styrene-alkyl acrylate copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyethylene, polypropylene and the like. Colorants include carbon black, aniline blue, calcoil blue, chrome yellow, ultramarine blue, Dupont oil red, quinoline yellow, methylene blue chloride, phthalocyanine blue, malachite green oxalate, lamp black, rose bengal, C.I.
I. Pigment Red 48: 1, C.I. I. Pigment Red 122, C.I. I. Pigment Red 57:
1, C.I. I. Pigment Yellow 97, C.I. I. Pigment Yellow 12, C.I. I. Pigment Blue 1
5: 1, Pigment Blue 15: 3 and the like can be exemplified as typical examples. Colorant amount C in toner
(% By weight) is preferably in the range of the following formula (3). 22 / D50v ≦ C ≦ 43 / D50v (3) That is, good gradation can be obtained by using in the range of the expression (3).

Further, the melt viscosity of the toner particles is preferably in the range of the following formulas (4) and (5) from the viewpoint of color development. The melt viscosity is a value measured by a flow tester. If the value is below the lower limit of these equations, the amount of seepage into the paper increases, and the image tends to be rough. On the other hand, if the value exceeds the upper limit, bubbles may be easily incorporated in the image, and color reproducibility may be reduced. 1 × 10 ⁵ ≦ η (90 ° C.) ≦ 1 × 10 ⁶ (4) 1 × 10 ⁴ ≦ η (100 ° C.) ≦ 1 × 10 ⁵ (5)

In the present invention, as the inorganic oxide fine particles externally added to the toner particles, SiO ₂ , TiO ₂ , Al
₂ O ₃ , CuO, ZnO, SnO ₂ , CeO ₂ , Fe ₂
O ₃ , MgO, BaO, CaO, K ₂ O, Na ₂ O, Z
rO ₂ , CaO.SiO ₂ , K ₂ O. (TiO ₂ ) n,
Al ₂ O ₃ · 2SiO ₂ , CaCO ₃ , MgCO ₃ , B
Examples thereof include aSO ₄ and MgSO ₄ , and those subjected to a hydrophobic treatment as necessary can be used. Of these, silica and titania are preferably used in combination, and in that case, silica preferably has a larger particle diameter. Further, as the titania, it is preferable to use a titanium compound having a specific gravity of 2.8 to 3.6 obtained by partially or completely reacting TiO (OH) ₂ produced by a wet method with a silane compound. This titanium compound is produced by reacting a silane compound with TiO (OH) ₂ produced by a wet method and drying it. As the silane compound,
Chlorosilanes, alkoxysilanes, silazanes and the like can be used. The above-mentioned titanium compound in the present invention has much lower carrier adhesion than ordinary titania, so that there is almost no carrier contamination, and the life of the developer can be further extended.

As the magnetic particles constituting the core of the carrier used in the present invention, magnetic metals such as iron, cobalt and nickel, and magnetic oxides such as ferrite and magnetite can be used. As the resin for coating the magnetic particles, polyolefin-based resins, for example, polyethylene, polypropylene; polyvinyl and polyvinylidene resins,
For example, polystyrene, acrylic resin, polyacrylonitrile, polyvinyl acetate, polyvinyl butyral, polyvinyl chloride, polyvinyl carbazole; vinyl chloride-vinyl acetate copolymer; styrene-acrylic acid copolymer; silicone resin; fluorine-containing resin;
Polyester; polyurethane; polycarbonate; phenolic resin; amino resin; epoxy resin and the like. Further, a resin containing fluorine is preferably used from the viewpoint of carrier contamination. For example, fluoropolymers such as copolymers of vinylidene fluoride and acrylic monomers, copolymers of vinylidene fluoride and vinyl fluoride, and terpolymers of tetrafluoroethylene, vinylidene fluoride and non-fluorinated monomers And terpolymers. Further, it is preferable that carbon black and crosslinked resin particles are dispersed in a fluorine-containing resin. By controlling the resistance value of the coating layer by carbon black, the carrier electric resistance value can be controlled, and also, by dispersing the carbon black and the crosslinked resin particles in the fluorine-containing resin, the fluorine-containing resin can be reinforced, Peeling of the resin coating layer can be suppressed. Further, since the basic carbon black and the basic crosslinked resin particles are uniformly dispersed in the fluorine-containing resin, it is more preferable to use them. Examples of the basic crosslinked resin particles include benzoguanamine resin particles, melamine resin particles, nitrogen-containing particles, and the like.

[0031]

【Example】

Example 1 Using a commercially available digital color copying machine, the toner weight per unit area of a solid image is changed by changing the toner charge amount, and the relationship between the roughness of image quality and the toner weight per unit area is evaluated. It was examined using a tone chart. As a digital color copier, A Color
630 (manufactured by Fuji Xerox) was used. The charge amount of the toner was changed by changing the toner / carrier ratio. In A Color 630, a latent image is formed on a negatively charged organic photoreceptor by a laser beam, and a developer including a negatively charged toner and a carrier is formed on a developing roll having a magnet therein by a magnetic brush. ,
A system in which a toner image is formed on the organic photoconductor by applying a developing bias by rubbing against the organic photoconductor, the toner image is transferred onto an image support such as paper, and fixed by a heat roll is adopted. The experiment was conducted using a polyester resin (bisphenol A ethylene oxide adduct / terephthalic acid /
Polycondensate of fumaric acid, Tg = 64 ° C., Tm = 110 ° C.,
Mw = 15,000) C.I. I. Pigment Red 57: 1 was dispersed in 8 parts by weight of magenta toner. The volume average particle diameter of the magenta toner is 7.5 μm, the specific gravity is 1.2, and the optimum toner weight is calculated as 0.52 mg / cm ² . When the weight of the toner on the support [TMA] = 0.35 mg / cm ² ,
The line is interrupted, and the weight of the toner on the support [TMA] = 0.
At 80 mg / cm ² , toner scattering occurs,
Image quality was rough. [TMA] = 0.42-0.
Good images were obtained in the range of 77 mg / cm ² .

Example 2 Production of Toner: Polyester resin having molecular weight Mw: about 15,000 (polycondensate of bisphenol A ethylene oxide adduct / terephthalic acid / fumaric acid, Tg = 64 ° C., Tm
= 110 ° C) 100 parts, C.I. Pigment Yellow 17, C.I. Pigment Red 57: 1, C.I.
I. Pigment Blue 15: 3 and carbon black (Legal 330 manufactured by Cabot Corporation) were melt-kneaded using a Banbury mixer using 8 parts of each, cooled, pulverized by a jet mill, and further classified by a classifier to obtain an average particle. 7 μm diameter toner particles were obtained. D16v / D50v are 1.20, 1.19, 1.19, 1.20, respectively, and D50p / D84p are 1.35, 1.38, respectively.
1.30 and 1.40. For these toner particles, hydrophobic silica having an average particle diameter of 16 nm (R972,
50% of hydrophobic silica having an average particle diameter of 40 nm (RX50, manufactured by Nippon Aerosil Co., Ltd.) 50%
Was mixed with a Henschel mixer to obtain a toner.

Production of carrier: average particle diameter 35 μm, particle diameter 33 μm to 44 μm as measured by microtrack.
m particles are 60% by weight and particles having a particle size of 22 μm or less are 3%.
0 wt%, saturation magnetization, residual magnetization and coercive force at 3000 Oe are 70 emu / g and 2 e, respectively.
Mu / g and 12 Oersted Ferrite Particles 10
0 parts by weight, 0.5 parts by weight of a styrene-methyl methacrylate copolymer, and 14 parts by weight of toluene were placed in a vacuum degassing kneader, and the mixture was stirred at a temperature of 90 ° C. for 30 minutes. A carrier was obtained by forming a coating layer. The electric resistance value of the obtained carrier is 0.4 V / μ.
m under an electric field strength of 5.2 × 10 ⁶ Ω, and under an electric field strength of 2.0 V / μm, 4.2 × 10 ⁵ Ω.

Preparation of developer composition: A developer composition was prepared by mixing 5 parts of the above toner and 95 parts of a carrier so as to obtain an appropriate development weight. The electric resistance value of the obtained two-component developer was 5. at an electric field strength of 0.4 V / μm.
4.2 × under an electric field intensity of 2 × 10 ⁶ Ω and 2.0 V / μm
It was 10 ⁵ Ω.

Comparative Example 1 Production of Toner: Polyester resin having molecular weight Mw: about 15,000 (polycondensate of bisphenol A ethylene oxide adduct / terephthalic acid / fumaric acid, Tg = 64 ° C., Tm
= 110 ° C) 100 parts, C.I. Pigment Yellow 17, C.I. Pigment Red 57: 1, C.I.
I. Pigment Blue 15: 3 and 8 parts each of carbon black (Legal 330, manufactured by Cabot) are melt-kneaded by a Banbury mixer, cooled, finely pulverized by a jet mill, and further classified by a classifier to average particles. 7 μm diameter toner particles were obtained. D16v / D50v are 1.25, 1.25, 1.30, 1.35, respectively, and D50p / D84p are 1.47, 1.50,
1.50 and 1.55. For these toner particles, hydrophobic silica having an average particle diameter of 16 nm (R972,
A toner was obtained by mixing 50% of Nippon Aerosil Co., Ltd. and 20% of hydrophobic silica (RX50, Nippon Aerosil Co., Ltd.) having an average particle diameter of 40 nm with a Henschel mixer. Production of the carrier and preparation of the developer composition were performed in the same manner as in Example 2.

Comparative Example 2 Production of Toner: Polyester resin having molecular weight Mw: about 15,000 (polycondensate of bisphenol A ethylene oxide adduct / terephthalic acid / fumaric acid, Tg = 64 ° C., Tm)
= 110 ° C) 100 parts, C.I. Pigment Yellow 17, C.I. Pigment Red 57: 1, C.I.
I. Pigment Blue 15: 3 and 8 parts each of carbon black (Legal 330, manufactured by Cabot) are melt-kneaded by a Banbury mixer, cooled, finely pulverized by a jet mill, and further classified by a classifier to average particles. 7 μm diameter toner particles were obtained. D16v / D50v are 1.20, 1.19, 1.19, 1.20, respectively, and D50p / D84p are 1.35, 1.38, respectively.
1.30 and 1.40. For these toner particles, hydrophobic silica having an average particle diameter of 16 nm (R972,
70% (manufactured by Nippon Aerosil Co., Ltd.) was mixed with a Henschel mixer to obtain a toner. Production of the carrier and preparation of the developer composition were performed in the same manner as in Example 2.

Comparative Example 3 Production of carrier: 5 particles having an average particle diameter of 35 μm and a particle diameter of 33 μm to 44 μm as measured by microtrack
0% by weight; 43% by weight of particles having a particle size of 22 μm or less;
The saturation magnetization, residual magnetization and coercive force at 000 Oe are 70 emu / g, 100 parts by weight of ferrite particles of 2 emu / g and 12 oersted, 0.5 part by weight of a styrene-methyl methacrylate copolymer,
14 parts by weight of toluene was placed in a vacuum degassing type kneader and stirred at a temperature of 90 ° C. for 30 minutes, and then toluene was distilled off under reduced pressure to form a coating layer and obtain a carrier. The electric resistance of the obtained carrier was 5.2 × 10 ⁶ Ω under an electric field strength of 0.4 V / μm, and 4.2 × 10 ⁵ Ω under an electric field strength of 2.0 V / μm. The production of the toner and the preparation of the developer composition were carried out in the same manner as in Example 2.

Comparative Example 4 Production of Carrier: Particle 60 having an average particle diameter of 35 μm and a particle diameter of 33 μm to 44 μm as measured by a microtrack.
% By weight, 30% by weight of particles having a particle size of 22 μm or less,
The saturation magnetization, residual magnetization and coercive force at 00 Oe are 100 parts by weight of ferrite particles of 45 emu / g, 2 emu / g and 12 oersted, 0.5 part by weight of a styrene-methyl methacrylate copolymer, and 14 parts by weight of toluene. Place in a degassing kneader, temperature 9
After stirring at 0 ° C. for 30 minutes, the pressure was reduced and toluene was distilled off to form a coating layer and obtain a carrier. The obtained carrier has an electric resistance value of 5.2 × 10 ⁶ Ω under an electric field strength of 0.4 V / μm, and an electric resistance value of 4.times.4 under an electric field intensity of 2.0 V / μm.
It was 2 × 10 ⁵ Ω. The production of the toner and the preparation of the developer composition were carried out in the same manner as in Example 2.

Comparative Example 5 The average particle diameter was 35 μm as measured by Microtrack.
60% by weight of particles having a particle diameter of 33 μm to 44 μm, 30% by weight of particles having a particle diameter of 22 μm or less, saturation magnetization, residual magnetization, and coercive force are 70 emu / g, 2 emu / g, respectively.
100 parts by weight of 12 Oersted ferrite particles, 3 parts by weight of a styrene-methyl methacrylate copolymer, and 14 parts by weight of toluene were put into a vacuum degassing kneader, and the temperature was 90 ° C.
After stirring for 30 minutes, toluene was distilled off under reduced pressure to form a coating layer and obtain a carrier. The obtained carrier has an electric resistance of 7.7 under an electric field strength of 0.4 V / μm.
1.2 × under electric field intensity of 2 × 10 ⁹ Ω, 2.0 V / μm
It was 10 ⁸ Ω. The production of the toner and the preparation of the developer composition were carried out in the same manner as in Example 2.

Evaluation of Developers of Examples 2 to 5 As in Example 1, using A Color 630 (manufactured by Fuji Xerox Co., Ltd.), the TMA on the paper was 0.3% for each single color.
mg / cm ² , 0.5 mg / cm ² ,
The image quality level was evaluated at 0.8 mg / cm ² . The evaluation chart is a gradation chart, and was evaluated by a limit sample. The evaluation was performed with grades G1 to G6. G
6 means the best level. Table 1 shows the results
Shown in From the results shown in Table 1, it can be seen that good image quality can be obtained by the color developer and the image forming method of the present invention.

[0041]

[Table 1]

Example 3 A developer was prepared and evaluated in the same manner as in Example 2, except that 5 parts by weight of the coloring agent was used. Good image quality could be obtained using the obtained color developer.
Table 2 shows the results. Example 4 In Example 3, the binder resin was a polyester resin having a molecular weight Mw of 1,000,000 (bisphenol A ethylene oxide adduct / terephthalic acid / fumaric acid polycondensate, Tg =
A developer was prepared and evaluated in the same manner as in Example 3, except that the temperature was changed to 60 ° C. and Tm = 105 ° C.). This toner is 90
Melt viscosity at about 5 × 10 ⁵ Pa.C. s and 1
The melt viscosity at 00 ° C. is about 5 × 10 ⁴ Pa. s. Good image quality could be obtained using the obtained color developer. Table 2 shows the results.

[0043]

[Table 2]

Example 5 Example 4 was repeated except that the external additive having a smaller particle size was changed to rutile-type titania having an average particle size of 15 nm, the surface of which was treated with decyltrimethoxysilane so as to be 5% by weight. Was prepared and evaluated in the same manner as in Example 4. Although the image quality level was almost the same as that of the fourth embodiment, the image quality level was stable with respect to environmental fluctuation.

Example 6 TiO (OH) which is an intermediate product of the sulfuric acid method or the hydrochloric acid method
₂ was used. That is, TiO (OH) ₂ produced by using ilmenite as an ore, dissolving it in sulfuric acid to separate iron, and hydrolyzing TiOSO ₄ was used. Part 1
40 parts by weight of isobutyltrimethoxysilane was mixed with 00 parts by weight, and reacted by heating. Washing with water,
The solution was filtered, dried at 120 ° C., and soft agglomeration was removed with a pin mill to obtain titania having an average particle size of 25 nm and a specific gravity of 3.1. A developer was prepared and evaluated in the same manner as in Example 5, except that the smaller external additive in Example 5 was changed to the obtained titania. Good image quality could be obtained by using the obtained color developer. Table 3 shows the results
Shown in

Example 7 The average particle diameter was 35 μm as measured by Microtrac.
60% by weight of particles having a particle diameter of 33 μm to 44 μm, 25% by weight of particles having a particle diameter of 22 μm or less, and saturation magnetization, residual magnetization and coercive force are 65 emu / g and 3 emu / g, respectively.
g and 100 parts by weight of 10 Oe Mn-Mg ferrite particles were mixed with a perfluorooctylethyl acrylate-methyl methacrylate copolymer (copolymerization ratio 3:
7, weight average molecular weight: 60,000) 3 parts by weight, toluene 14 parts by weight, carbon black (REGAL 400, manufactured by Cabot Corporation) 0.24 parts by weight, polymethyl methacrylate particles having an average particle diameter of 0.3 μm 0.3 parts by weight Was stirred and mixed in advance, and the mixture was placed in a vacuum degassing kneader, stirred at a temperature of 90 ° C. for 30 minutes, and then toluene was distilled off under reduced pressure to form a coating layer and obtain a carrier. The electric resistance of the obtained carrier was 7.2 × 10 ⁶ Ω under an electric field strength of 0.4 V / μm and 6.2 × 10 ⁵ Ω under an electric field strength of 2.0 V / μm. The production of the toner and the preparation of the developer composition were carried out in the same manner as in Example 6. Good image quality could be obtained by using the obtained color developer. Table 3 shows the results.

Example 8 The average particle diameter was 35 μm as measured by Microtrac.
60% by weight of particles having a particle diameter of 33 μm to 44 μm, 25% by weight of particles having a particle diameter of 22 μm or less, and saturation magnetization, residual magnetization and coercive force are 65 emu / g and 3 emu / g, respectively.
g and 100 parts by weight of 10 Oe Mn-Mg ferrite particles were mixed with a perfluorooctylethyl acrylate-methyl methacrylate copolymer (copolymerization ratio 3:
7, weight average molecular weight: 60,000) 3 parts by weight, toluene 14 parts by weight, basic carbon black (Vulcan XC72, manufactured by Cabot) 0.3 part by weight, basic crosslinked melamine particles having an average particle diameter of 0.3 μm. A mixture of 3 parts by weight in advance and stirring was added, and the mixture was placed in a vacuum degassing kneader, stirred at a temperature of 90 ° C. for 30 minutes, and then toluene was distilled off under reduced pressure to form a coating layer and obtain a carrier. . The electric resistance of the obtained carrier was 7.2 × 10 ⁶ Ω under an electric field strength of 0.4 V / μm and 6.2 × 10 ⁵ Ω under an electric field strength of 2.0 V / μm. The production of the toner and the preparation of the developer composition were carried out in the same manner as in Example 7. Good image quality was obtained by using the obtained color developer.
Table 3 shows the results. Further, the tribo reduction was halved in the 100,000-sheet print test compared to Example 2, and the developer life was greatly improved.

[0048]

[Table 3]

[0049]

Since the multicolor image forming method of the present invention has the above-described structure, a high-quality full-color image can be obtained. Further, the color two-component developer of the present invention can obtain a high-quality full-color image without extremely reducing the toner particle diameter.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a color image forming apparatus for performing a multicolor image forming method of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 101 ... Photoconductor, 102 ... Charging device, 103 ... Rotary developing device, 104 ... Transfer drum, 105 ... Cleaner, 106
... pre-exposure device, 107 ... recording material, 108 ... potential sensor, 1
09: fixing device, 110: image input device, 120: light beam scanning device, 121: semiconductor laser, 122: collimator lens, 123: polygon mirror, 124: imaging optical system, 130: light beam PWM circuit, 140: Color conversion processing circuit,

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Shuichi Taniguchi 1600 Takematsu, Minamiashigara, Kanagawa Prefecture Inside Fuji Xerox Co., Ltd. (72) Inventor Hiroshi Takano 1600 Takematsu, Minami Ashigara City, Kanagawa Prefecture Inside Fuji Xerox Co., Ltd. (72) Inventor Yuka Ishihara 1600 Takematsu, Minami Ashigara City, Kanagawa Prefecture Inside Fuji Xerox Co., Ltd. (72) Inventor Akihiro Iizuka 1600 Takematsu, Minami Ashigara City, Kanagawa Prefecture Inside Fuji Xerox Co., Ltd. 1600 Takematsu Fuji Xerox Co., Ltd. (72) Inventor Masanori Ichimura 1600 Takematsu Minami Ashigara, Kanagawa Prefecture Inside Fuji Xerox Co., Ltd. (72) Inventor Hiroshi Nakazawa 1600 Takematsu, Minami Ashigara City, Kanagawa Prefecture Fuji Xerox Co., Ltd. (72) Inventor Satoru Ishigaki 1600 Takematsu, Minamiashigara-shi, Kanagawa Inside Fuji Xerox Co., Ltd. (72) Inventor Hideyuki Akagi 1600 Takematsu, Minamiashigara, Kanagawa Prefecture Inside Fuji Xerox Co., Ltd. (72) Inventor Kazuya Furuta 1600 Takematsu, Minami Ashigara City, Kanagawa Prefecture Inside Fuji Xerox Co., Ltd. (72) Inventor Kensaku Togao 1600 Takematsu, Minamiashigara-shi, Kanagawa Prefecture Inside Fuji Xerox Co., Ltd.

Claims (17)

[Claims] 1. A two-component color developer comprising a color toner and a carrier, wherein the color toner has an average particle diameter of 3 to 9 μm and a particle size distribution represented by the following formulas (1) and (2). Satisfactory, the color toner has two kinds of inorganic oxide fine powders as external additives, and the external additive having a larger average particle diameter is 10% of the total specific surface area of the toner particles. Above the toner particle surface is coated,
The external additive having the smaller average particle diameter coats the toner particle surface by 20% or more based on the total specific surface area of the toner particles, and the total coating amount of these two types of external additives is based on the total specific surface area of the toner particles. The carrier is a magnetic particle coated with a resin, and the magnetic particle has an average particle diameter of 3% or more.
0 to 50 μm, particles having a particle diameter of 33 μm to 44 μm are 50% by weight or more and particles of 22 μm or less are 40% by weight.
The following are contained, and the carrier is 3000
The saturation magnetization, the residual magnetization and the coercive force in Oersted are 50 emu / g or more and 5 emu / g or less and 20 oersted or less, respectively. The resistance per unit length in the sleeve longitudinal direction of the magnetic brush developer layer of the developer is:
6.2 × 10 ⁴ to 6.2 under an electric field strength of 0.4 V / μm
6.2 × 1 under an electric field strength of × 10 ⁸ Ω and 2.0 V / μm
0 ⁴ color two-component developer, characterized in that in the range of ~6.2 × 10 ⁶ Ω. D16v / D50v ≦ 1.457−0.036 × D50v (1) D50p / D84p ≦ 1.45 (2) (in the formula, D16v is the 16% volume particle diameter calculated from the large particle side of the volume average particle diameter) (Μm), D50v is the 50% volume average particle diameter (μm) calculated from the large particle side of the volume particle diameter.
m), D50p is 50 calculated from the large particle side of the number particle diameter.
% Number average particle diameter (μm) and D84p represent the 84% number particle diameter (μm) calculated from the larger particle side of the number particle diameter. ) 2. The color two-component developer according to claim 1, wherein the amount C (% by weight) of the colorant in the toner is within a range represented by the following formula (3). 22 / D50v ≦ C ≦ 43 / D50v (3) 3. The two-component color developer according to claim 1, wherein the melt viscosity of the toner particles is within a range represented by the following formulas (4) and (5). 1 × 10 ⁵ ≦ η (90 ° C.) ≦ 1 × 10 ⁶ (4) 1 × 10 ⁴ ≦ η (100 ° C.) ≦ 1 × 10 ⁵ (5) (where η (90 ° C.) and η (100 ° C.) ) Is the melt viscosity of the toner at 90 ° C. and 100 ° C. (Pa ·
s). ) 4. The color two-component developer according to claim 1, wherein the external additive contains silica and a titanium oxide-based compound. 5. The two-component color developer according to claim 4, wherein the titanium oxide compound has a smaller average particle diameter than silica. 6. The method according to claim 1, wherein the titanium oxide compound is TiO (OH) ₂
The two-component color developer according to claim 4, wherein the titanium compound has a specific gravity of 2.8 to 3.6 obtained by partially or completely reacting with the silane compound. 7. The carrier according to claim 1, wherein the carrier is magnetic particles coated with a matrix resin containing carbon black and fluorine dispersed in resin particles.
2. The two-component color developer according to item 1. 8. The two-component color developer according to claim 7, wherein the carbon black is a basic carbon black. 9. The color two-component developer according to claim 7, wherein the resin particles are crosslinked resin particles. 10. The color two-component developer according to claim 9, wherein the resin particles are basic crosslinked resin particles. 11. A step of forming a latent image on a latent image holding member,
Forming a toner image on the latent image holding member using a developer on a developer carrier, transferring the toner image directly or indirectly to an image support, and transferring the toner image onto the image support; In a multicolor image forming method having a step of fixing by heat and pressure, the volume average particle diameter of toner particles [D50v]
(Μm) and the toner weight [TMA] (mg / cm ² ) on the image support when the maximum density of a single color is developed is represented by the following formula (6).
A multicolor image forming method, wherein development and transfer are performed so as to satisfy the following relationship. ρ × (4/3) πr ³ × (k / r ³ ) ^2/3 /10−0.10≦[TMA]≦ρ×(4/3)πr ³ × (k / r ³ ) ^2/3 / 10 + 0.25 (6) (where ρ is the specific gravity of the toner, π is the pi, r is the volume average particle radius (unit μm) of the toner particles, and k = 0.144.
Represents ) 12. The developer on the developer carrier comprises a color toner and a carrier, the color toner has an average particle diameter of 3 to 9 μm, and its particle size distribution is represented by the following formulas (1) and (1). 2), wherein the color toner has two kinds of inorganic oxide fine powders as external additives, and the external additive having a larger average particle diameter is larger than the total specific surface area of the toner particles. To cover the toner particle surface by 10% or more,
The external additive having the smaller average particle diameter covers the toner particle surface by 20% or more based on the total specific surface area of the toner particles, and the total coating amount of these two types of external additives is based on the total specific surface area of the toner particles. The carrier is a magnetic particle coated with a resin, and the magnetic particle has an average particle diameter of 3% or more.
0 to 50 μm, particles having a particle diameter of 33 μm to 44 μm are 50% by weight or more and particles having a particle diameter of 22 μm or less are 40% by weight.
% By weight and the carrier is 3% by weight or less.
The saturation magnetization, remnant magnetization and coercive force at 000 Oe are 50 emu / g or more and 5 emu / g, respectively.
And the resistance per unit length in the sleeve longitudinal direction of the magnetic brush developer layer of the developer is 6.2 × 10 ⁴ or less under an electric field strength of 0.4 V / μm.
6.2 × 10 ⁸ Ω, under an electric field strength of 2.0 V / μm.
The multicolor image forming method according to claim 11, wherein the value is in a range of 2 × 10 ^{4 to} 6.2 × 10 ⁶ Ω. D16v / D50v ≦ 1.457−0.036 × D50v (1) D50p / D84p ≦ 1.45 (2) (in the formula, D16v is the 16% volume particle diameter calculated from the large particle side of the volume average particle diameter) (Μm), D50v is the 50% volume average particle diameter (μm) calculated from the large particle side of the volume particle diameter.
m), D50p is 50 calculated from the large particle side of the number particle diameter.
% Number average particle diameter (μm) and D84p represent the 84% number particle diameter (μm) calculated from the larger particle side of the number particle diameter. ) 13. The multicolor image forming method according to claim 12, wherein the amount C (% by weight) of the colorant in the toner is within a range represented by the following formula (3). 22 / D50v ≦ C ≦ 43 / D50v (3) 14. The toner particle having a melt viscosity represented by the following formula (4):
13. The multicolor image forming method according to claim 12, wherein the value is within the range represented by (5). 1 × 10 ⁵ ≦ η (90 ° C.) ≦ 1 × 10 ⁶ (4) 1 × 10 ⁴ ≦ η (100 ° C.) ≦ 1 × 10 ⁵ (5) (where η (90 ° C.) and η (100 ° C.) ) Is the melt viscosity of the toner at 90 ° C. and 100 ° C. (Pa ·
s). ) 15. The multicolor image forming method according to claim 12, wherein the external additive contains silica and a titanium oxide-based compound. 16. The multicolor image forming method according to claim 15, wherein the titanium oxide compound has an average particle diameter smaller than that of silica. 17. The carrier according to claim 12, wherein the carrier is magnetic particles coated with a matrix resin containing carbon black and fluorine dispersed resin particles.
2. The multicolor image forming method according to 1. above.