JP3242157B2 - Full color toner - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a full-color toner used for forming a full-color image by an electrophotographic system.

[0002]

2. Description of the Related Art A full-color toner for electrophotography is basically a combination of a yellow toner, a magenta toner cyan toner and, if necessary, a black toner. Nos. 776 and 53-47174 and 53-47175
And JP-A-53-47176. In a full-color copy image, toners of three colors or four colors including black are sequentially superimposed on transfer paper, and not only development characteristics but also transfer characteristics are important factors that determine image quality. Furthermore, in recent years, with the widespread use of image forming apparatuses such as electrophotographic copying machines, the uses thereof have been expanded in various ways, and the demands on the image quality have become strict. For example, in copying an image such as a general forehead, a catalog, or a map, it is required to reproduce extremely finely and faithfully without being crushed or interrupted even in a minute portion. Recently, in an image forming apparatus such as an electrophotographic color copying machine using a digital image signal, a latent image is formed by collecting dots of a constant potential, and a solid portion, a halftone portion, and a light portion are formed. Is expressed by changing the dot area. However, in a state where the toner particles do not exactly adhere to the dots and the toner particles protrude from the dots, it is not possible to obtain the gradation property of the toner image corresponding to the dot area ratio of the black portion and the white portion of the digital latent image. There is a problem. Further, when the resolution is improved by reducing the dot size in order to improve the image quality, the reproducibility of a latent image formed from minute dots becomes more difficult, and the resolution and especially the gradation of the highlight portion are increased. The image tends to be poor in quality and lacks in sharpness. Until now, for the purpose of improving the toner transferability and improving the image quality, it has been attempted to add various additives such as a lubricant to the toner, but the resistance of the colorant internally added to the toner, That is, without considering the resistance of the organic colorant of high resistance and the inorganic colorant such as carbon black of low resistance, even if the transfer characteristics and the charging characteristics of each color toner are balanced, the problem of toner scattering or the It has been found that it is difficult to satisfy all image characteristics such as high image density and high image quality of the obtained image.

[0003]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a full-color toner which solves the problems of the prior art as described above. Further, an object of the present invention is to provide a full-color toner having a high image density, excellent fine line reproducibility, and excellent highlight gradation. Further, an object of the present invention is to provide a full-color toner having excellent transferability. Further, an object of the present invention is to provide a full-color toner having no change in performance even when used for a long time.

[0004]

The above objects are achieved by the present invention described below. That is, the present invention provides a yellow toner comprising at least a colorant-containing resin particle containing a yellow colorant and a binder resin and an external additive, and a colorant containing at least a magenta colorant and a binder resin. Magenta toner comprising resin particles and an external additive, a cyan toner comprising colorant-containing resin particles and an external additive containing at least a cyan colorant and a binder resin, and at least carbon black and a binder resin In a full-color toner in which a colorant-containing resin particle containing: and a black toner comprising an external additive, each external additive contains at least flow improver fine particles, and the flow improver in the black toner Wherein the volume resistivity of the flow improver in the other yellow toner, magenta toner and cyan toner is higher than that of the other toners. It is a full-color toner.

[0005]

The full-color toner of the present invention is capable of faithfully transferring the developed toner developed on the latent image holding member, and is capable of converting a solid latent image from a minute dot latent image such as a halftone dot and a digital latent image. Until a stable transfer image is obtained. The reason why the above-mentioned effects are obtained in the full-color toner of the present invention is presumed as follows. In conventional color toners, a flow improver is used for the purpose of improving the flowability, but it is difficult to achieve both the flowability of the toner and the control of the charge amount, or if the transferability is excessively improved,
Conversely, the scattering of toner on the transfer paper increased, which was not always satisfactory. The present inventors have attempted to improve flowability and transferability by adding a flow improver for the purpose of improving transferability, but it is very difficult to achieve stable transferability in all four colors. It was confirmed.
Therefore, the present inventors have further studied the addition amount and type of the flow improver for each color of the toner, and found that by increasing the volume specific resistance of the flow improver in the black toner, the developability and The present invention was completed by solving the problem of transferability and finding that high image quality can be achieved. Although the reason is not clear yet, since the black toner in the present invention uses low-resistance carbon black as a colorant, transfer followability by an electric field is inferior to that of the other three colors. It is considered that the transfer followability was improved by increasing the resistance of the flow improver. Furthermore, it has been found that titanium oxide is most preferable as a flow improver to be used in consideration of environmental stability.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in more detail with reference to preferred embodiments of the present invention. The full color toner of the present invention is characterized in that the volume resistivity of the flow improver in the black toner is larger than the volume resistivity of the flow improvers of the other yellow, magenta and cyan toners. As described above, as the flow improver to be used, titanium oxide is most preferable in consideration of environmental stabilization.For example, as means for increasing the resistance of titanium oxide,
There is no particular limitation on a method based on surface treatment of titanium oxide, a method based on a crystal type, and the like. In a preferred embodiment of the present invention, rutile or amorphous titanium oxide having a volume resistivity of about 10 ¹⁴ Ωcm is used as the titanium oxide for the black toner, and 10 ⁷ Ω for the toners of other colors.
It is preferable to use titanium oxide of about cm. Particularly preferably, amorphous titanium oxide is used as the titanium oxide for the black toner. In this way, controlling the resistance by the crystal form of titanium oxide and achieving both development characteristics and transfer characteristics can be achieved only by using hydrophobic silica as a flow improver generally known conventionally. That was not. Also, JP-A-60-
In JP-A-136755 and the like, it is proposed to add titanium oxide as a flow improver, but it is not intended to improve transferability and is different from the present invention.

The titanium oxide used in the present invention is:
In light of imparting fluidity, the particle size is preferably from 10 to 200 mμ, more preferably from 10 to 100 mμ.
And In addition, from the viewpoint of storage stability and prevention of change in image density due to charge fluctuation, the degree of hydrophobicity is preferably 40 to 80%, more preferably 50 to 80%. If the particle diameter of the titanium oxide is larger than 200 μm, the toner charge becomes non-uniform due to poor fluidity, and as a result, toner scattering, fogging and the like occur. On the other hand, when the particle diameter is smaller than 10 μm, titanium oxide is easily embedded in the toner surface, and the toner deteriorates quickly, and the transfer characteristics are impaired. Such a tendency is more remarkable in the color toner of the sharp melt property used in the present invention. In addition, the degree of hydrophobicity is 40
%, The charge amount is greatly reduced particularly when left for a long time under high humidity, and a mechanism for accelerating the charge on the hardware side is required, which complicates the apparatus. On the other hand, when the hydrophobicity is more than 80%, charging co emissions Control of the inorganic fine particles themselves it is difficult, especially the toner under low humidity as a result will be charged up.

As a method for obtaining anatase or rutile type titanium oxide fine particles, for example, a production method using a general sulfuric acid method can be used, and the crystal type may be controlled by the firing conditions. Further, as a method of hydrophobizing the titanium oxide fine particles, a method of hydrolyzing the coupling agent in an aqueous system is preferable.

[0009] Further, as a method for obtaining a titanium oxide amorphous, volatile titanium compound can be used a method of thermally decomposing in a gas phase. For example, in the present invention, a method in which a volatile titanium compound such as a titanium alkoxide is thermally decomposed in a gas phase at a low temperature of 600 ° C. or less is particularly preferable. Further, as a preferable production method, the volatile titanium compound is vaporized or atomized at a relatively low temperature of 600 ° C. or lower, preferably 250 to 400 ° C., and then decomposed and oxidized at a relatively low temperature of not more than 600 ° C. Immediately after the decomposition, the titanium oxide particles are cooled to a temperature at which the titanium oxide particles do not coalesce, preferably to 100 ° C. or less, in a short time. Further, it is more effective to use a dispersing aid, a surface modifier or the like for the purpose of preventing coalescence of the titanium oxide fine particles during or after cooling, or for the purpose of improving collection and recovery.

The volatile titanium compound used in the present invention includes titanium alkoxides such as titanium tetramethoxide, titanium tetraethoxide, titanium tetrapropoxide, titanium tetrabutoxide, and diethoxy titanium oxide; Titanium halides such as titanium bromide, and volatile titanium compounds such as trihalogenated monoalkoxytitanium, dihalogenated dialkoxytitanium, and monohalogenated trialkoxytitanium can also be used.

When the volatile titanium compound is vaporized or atomized, the volatile titanium compound is diluted with a diluent gas to a concentration of 0.1%.
It is preferable to dilute to a ratio of 1 to 10% by volume. This diluent gas serves as a carrier gas for introducing the vaporized volatile titanium compound into a decomposition furnace for decomposition. As the diluent gas used here, an inert gas such as argon, helium, nitrogen, or the like, water vapor, oxygen, or the like is used, and particularly, helium or nitrogen gas is preferably used. Further, as described above, a dispersing aid, a surface modifier and the like may be contained as necessary.

In the method for producing titanium oxide used in the present invention as described above, a volatile titanium compound is vaporized or atomized and then decomposed into titanium oxide fine particles, so that an oxygen-containing compound such as alkoxide is used. Except when using, an oxygen-containing gas is required. Further, the temperature at which the volatile titanium compound is decomposed is preferably 600 ° C. or lower, and more preferably 250 to 350 ° C. If the temperature is lower than this, a sufficient decomposition rate cannot be obtained,
On the other hand, when the decomposition temperature is high, it becomes difficult to obtain fine particles. In order to adjust the charging characteristics of the obtained titanium oxide fine particles and to improve the stability under high humidity, a surface treatment such as a hydrophobizing treatment can be performed as long as the characteristics of the titanium oxide are not impaired. There is no limitation on the method of hydrophobization, but in the present invention, when rapidly cooling,
For example, the most effective means is to treat the titanium oxide fine particles after thermal decomposition together with a refrigerant of an inert gas such as nitrogen gas to make them hydrophobic.

As the binder used in the colorant-containing resin particles of the present invention, various resin materials conventionally known as electrophotographic toner binder resins are preferably used. For example, styrene copolymers such as polystyrene, styrene, butanediene copolymer, styrene / acrylic copolymer, and ethylene copolymers such as polyethylene, ethylene / vinyl acetate copolymer, and ethylene / vinyl alcohol copolymer Phenolic resin, epoxy resin, acrylic phthalate resin, polyamide resin, polyester resin, maleic acid resin and the like. In addition, the method of manufacturing any resin is not particularly limited.

The effect of the present invention is remarkable when a polyester resin having a high negative chargeability is used among these resins. That is, the polyester resin has excellent fixability,
While suitable for use in color toners, it has a strong negative charging ability, tends to be excessively charged, tends to have high adhesion to the latent image carrier, and tends to have low transfer characteristics.
When a polyester resin is used in the constitution of the present invention, such adverse effects are improved, and an excellent toner can be obtained. In particular, a bisphenol derivative or a substituent represented by the following formula is used as a diol component, and a carboxylic acid component composed of a divalent or higher carboxylic acid or an acid anhydride thereof or a lower alkyl ester thereof (for example, fumaric acid, maleic acid) A polyester resin obtained by co-condensation polymerization of a polyester resin with maleic anhydride, phthalic acid, terephthalic acid, trimellitic acid and pyromellitic acid) is more preferably used because it has sharp melting properties.

[0015]

Embedded image

As colorants for yellow, magenta and cyan toners, conventionally known dyes and pigments, for example, phthalocyanine blue, induslen blue, peacock blue, permanent red, lake red, rhodamine lake, Hansa yellow, permanent yellow, benzidine Yellow and the like can be widely used. The content thereof is 12 parts by weight based on 100 parts by weight of the binder resin so as to be sensitive to the light transmittance of the OHP film.
It is at most 0.5 parts by weight, preferably 0.5 to 9 parts by weight.

On the other hand, carbon black as a colorant for a black toner has an average primary particle size of 50 to 70 mμ, a surface area of 10 to 40 m ² / g, and an oil supply amount of 50 to 100 cc / 10.
It is preferable that the pH is 0 g-DBP and the pH value is 6.0 to 9.0. Particularly preferred ranges of the physical properties of the above carbon black are 60 to 70 mμ, 30 to 40 m ² / g, and 6 respectively.
It is 0 to 70 cc / 100 g-DBP. The ranges of the respective physical property values are closely related to the resistance and the amount of titanium oxide as an external additive. If the average particle size of the carbon black is less than 50 μm, the amount of triboelectric charge between the toner particles and the carrier particles is reduced, which may cause toner scattering and fogging. On the other hand, when the surface area exceeds 40 m ² / g, toner scattering occurs at the edge of the obtained visible image. In addition, the oil absorption is 100c
If c / 100 g-DBP is exceeded, agglomeration of carbon black particles occurs during image fixing, and 50 cc / 100 g-D
If it is less than BP, a sufficient image density cannot be obtained. On the other hand, when the pH value is less than 6.0, the dispersion of carbon black in the binder resin becomes non-uniform, resulting in unstable charging ability.

In the above measurement of the physical properties of carbon black, the particle diameter was measured by directly and selectively counting the particle diameter in a scanning electron microscope photograph. Next, a method for measuring the surface area, the oil absorption, and the pH value will be described. The surface area is measured in accordance with the BET measurement method in ASTM method D3037-78. According to the flow shown in FIG. 1, first, a mixed gas of N ₂ and He is flowed through carbon black to adsorb N ₂ , and the amount thereof is transferred to the thermal conductivity cell 7.
And the specific surface area of the sample is determined by calculation from the N ₂ adsorption amount. (1) After drying the carbon black of the sample at 105 ° C. for 1 hour, 0.1 to 1 g is precisely weighed, put into the U-shaped tube 4 and attached to the channel. (2) by a flow meter of a predetermined changing the N ₂ / the He mixing ratio P /
It is set to P _0. (3) After opening the cock and introducing the adsorbed gas into the sample layer,
The U-tube 4 is immersed in liquid nitrogen 3 to adsorb N ₂ . (4) After reaching the adsorption equilibrium, the liquid N ₂ is removed and about 30
Seconds, after exposure to air, immersed U-shaped tube 4 in water at room temperature, desorbing N _2. (5) A desorption curve is drawn on a recorder and the area is measured. (6) Prior to these operations, the amount of N ₂ adsorbed at a predetermined P / P ₀ is determined from the area obtained for the above sample using a calibration curve prepared by introducing a known amount of N ₂ . From the measured N ₂ adsorption amount, the following surface area is determined by applying the following equation.

[0019]

(Equation 1) P ₀ : Saturated vapor pressure of adsorbate at measurement temperature P: Pressure at adsorption equilibrium ν: Adsorption amount at adsorption equilibrium C: Constant

The relationship between P / P ₀ and P / ν (P ₀ -P) is a straight line, and ν _m is determined from the odor and intercept of the straight line. ν _m
Is determined, the specific surface area S is calculated by the following equation. S = A × ν _m × N / W where S: specific surface area A: cross-sectional area of adsorbed molecule N: Avogadro number W: sample amount

Oil absorption (DBP) The oil absorption is measured according to ASTM method D2414-79. Operate the cock of the absorption meter, fill DBP (dibutyl phthalate) completely so that no air bubbles remain in the automatic bured system, and make the specifications of the apparatus the following conditions. (1) Spring tension : 2.68 kg / cm (2) Rotor rotation speed : 125 rpm (3) Scale of torque limit switch : 5 (4) Dam bar valve : 0.150 (5) DBP dripping speed : 4 ml / min After adjusting the dropping speed of DBP by actual measurement, a fixed amount of the dried sample is put into the absorption meter mixing chamber, the buret counter is set to zero, and the switch is automatically turned on to start dropping. When the torque reaches the set point (5 in this case)
When the limit switch is activated, the dripping stops automatically, the scale (V) of the bullet counter at that time is read, and the oil absorption is calculated by the following equation.

[0022]

(Equation 2) OA: Oil absorption (ml / 100g) V: D used up to the end point (limit switch operating point)
Amount of BP used (ml) W: Weight of dried sample (g)

PH value 1 to 10 g of carbon black as a sample is weighed in a beaker, water is added at a rate of 10 ml per 1 g of the sample, covered with a watch glass, and boiled for 15 minutes. At this time, a few drops of ethyl alcohol may be added to make the sample easily wet. After boiling, the mixture is cooled to room temperature, and the supernatant is removed by a gradient method or a centrifugal separation method to leave a muddy substance. An electrode of a glass electrode pH meter is placed in the slurry, and the pH is measured according to JIS Z8802 (pH measurement method). In this case, the measured value may change depending on the insertion position of the electrode, so move the beaker to change the position of the electrode, measure carefully so that the electrode surface and the muddy surface are in sufficient contact, and measure the pH value. Read the value where it became constant.

In the present invention, carbon black is 2.0 to 10% by weight, preferably 3.10% by weight, based on the total weight of the toner.
It is preferable to use 0 to 7% by weight. If the added amount of carbon black is less than 2.0% by weight, the resulting visible image may be rough and the image density may be reduced. Conversely, if the added amount is more than 10% by weight, scattering on the image and fog may occur. Is a factor that leads to The full-color toner of the present invention may contain a charge control agent in order to stabilize the charge characteristics. In that case, a colorless or light-colored charge control agent that does not affect the color tone of the toner is preferable. In the present invention, when a negatively charged developer is used, the present invention becomes more effective. Examples of the negative charge control agent at this time include metal complexes of alkyl-substituted salicylic acid (for example, di-
chromium or zinc complexes of tert-butylsalicylic acid). When the negative charge control agent as described above is blended in the toner, the binder resin 100
0.1 to 10 parts by weight, preferably 0.1 to 10 parts by weight, per part by weight.
It is preferable to add 5 to 8 parts by weight.

When the toner of the present invention is used as a two-component developer, the magnetic particles include, for example, metals such as iron, nickel, copper, zinc, cobalt, manganese, chromium, rare earths and the like, which have been oxidized or not oxidized. And their alloys or oxides and ferrites. In addition, there is no particular limitation on the manufacturing method.

In the present invention, the surface of the magnetic particles as described above is coated with a resin or the like. As a method, a coating material such as a resin is dissolved or suspended in a solvent and applied to adhere to the magnetic particles. Any of conventionally known methods such as a squeezing method and a method of simply mixing with a powder can be applied.
In order to stabilize the coating layer, a method in which the coating material is dissolved in a solvent is preferable. The most suitable material for the magnetic particles used in the present invention is ferrite having a composition of 98% or more of Cu—Zn—Fe [composition ratio (5 to 20) :( 5 to 20) :( 30 to 80)]. The ferrite particles are particles that can be easily smoothed on the surface, have a stable charge-imparting ability, and have a stable coating. The coating amount of the coating material such as a resin may be appropriately determined so that the charging property of the magnetic particles satisfies the above-described conditions. In general, the total amount is 0.1 to 30% by weight based on the magnetic particles ( Preferably 0.3 to 20% by weight). The magnetic particles preferably have a weight average particle diameter of 35 to 65 μm, preferably 40 to 60 μm. Further, 2 to 6% of particles having a weight distribution of 26 μm or less, and 1 to 2% of particles having a weight distribution of 26 to 35 μm.
A good image can be maintained when 0% by weight, 5% to 25% of particles having a weight distribution of 35 μm to 43 μm, and 2% or less of particles of 74 μm or more. In the present invention, the mixing ratio of the magnetic particles and the toner particles described above is generally good when the toner concentration in the developer is 2.0 to 9% by weight, preferably 3 to 8% by weight. Results are obtained. 1. The toner density is 2.
If it is less than 0%, the image density becomes too low to be practical, and 9%
If it is larger, fog and scattering in the machine are increased, and the useful life of the developer is shortened.

In the present invention, a fatty acid metal salt as an organic resin particle or a lubricant, for example, zinc stearate, aluminum stearate or the like, or a fine powder of a fluorine-containing polymer, for example, polytetrafluoroethylene, polyvinylidene Fluoride etc. and tetrafluoroethylene-
Fine powder or oxidation Nariumu of vinylene Li Den fluoride copolymer, such as abrasive silicon carbide, or tin oxide, may be added conductive agent such as zinc oxide.

To prepare the negatively-chargeable colorant-containing resin particles used in the present invention, a pigment or a dye as a colorant, a charge control agent, and other additives are added to the thermoplastic resin as necessary. After thoroughly mixing with a mixer such as a ball mill, a heating roll, a kneader, and a hot kneader such as an extruder are melted, kneaded and kneaded to make the resins compatible with each other. The colorant-containing resin particles used in the present invention can be obtained by dispersing or dissolving the dye, cooling and solidifying, and then performing pulverization and strict classification.

Hereinafter, a measuring method used in producing the full-color toner of the present invention will be described. (1) Hydrophobicity measurement: The methanol titration test method is an experimental test for confirming the hydrophobicity of a titanium oxide powder having a hydrophobized surface.
The "methanol titration test" defined in this specification for evaluating the degree of hydrophobicity of the treated titanium oxide fine powder is performed as follows. The test titanium oxide powder 0.2 g, volume 25
Add to 50 ml of water in a 0 ml Erlenmeyer flask. Methanol is titrated from the burette until all of the titanium oxide is wetted. At this time, the solution in the flask is constantly stirred with a magnetic stirrer. The end point is titanium oxide
Observed by the total amount of emissions powder is suspended in a liquid, hydrophobicity is expressed as a percentage of the methanol of methanol and the liquid mixture of water when the reaction has reached the end point.

(2) Volume resistivity Pellets (20 mmφ × 2 to 3 mm thick) are 10 t × 3
It is made by pressure molding for 0 seconds. This pellet is heated at 22 ° C.
Leave for 24 hours in a 55% RH environment chamber. Takeda Riken TR-8601 HIGHMEGOHM
The resistance value is measured by changing the electric field by METER, and a value of 1 kv / cm is read by a data plot.

[0031]

EXAMPLES The present invention will be described in more detail with reference to the production examples of titanium oxide fine particles and examples and comparative examples of the present invention. The parts and percentages are based on weight. <Example 1 of producing titanium oxide fine particles> Titanium tetraisopropoxide is used as a raw material. Using a chemical pump, a small amount of the raw material was sent into glass wool of a vaporizer heated to 200 ° C. using nitrogen gas as a carrier gas to evaporate it, and then thermally decomposed at 320 ° C. in a reactor. Is subjected to hydrophobization treatment with hexamethyldisilazane gas as a carrier gas, and at the same time, rapid cooling is performed to collect the product. The average temporary particle diameter is 20 mμ, the BET is 130 m ² / g, the degree of hydrophobicity is 70%,
Spherical titanium oxide fine particles A having a volume resistivity of 10 ¹⁴ Ωcm were obtained. The titanium oxide fine particles thus obtained were confirmed to be amorphous by X-ray diffraction.

<Production Example 2 of Titanium Oxide Fine Particles> In Production Example 1, the hydrophobicity was 0%, the average primary particle diameter was 20 mμ, the BET was 150 m ² / g, and the volume resistivity was 10 in the same manner except that the treatment was not performed with hexamethyldisilazane gas. ¹²
Ωcm titanium oxide fine particles B were obtained.

<Titanium Oxide Fine Particle Production Example 3> Hydrophobizing treatment is performed while hydrolyzing 20 parts of n-butyltrimethoxysilane while stirring titanium oxide fine particles B in an aqueous system, followed by drying and crushing to make the particles hydrophobic. The titanium oxide fine particles C having a degree of 65%, an average primary particle diameter of 20 mμ, a BET of 120 m ² / g, and a volume resistivity of 10 ¹⁴ Ωcm were obtained.

<Production Example 4 of Titanium Oxide Fine Particles> In the same manner as in Production Example 3, except that anatase-type hydrophilic titanium oxide synthesized from titanium tetrachloride was used, the degree of hydrophobicity was 60%, the average primary particle diameter was 50 μm, and the BET was 100 m. ² /
g, titanium oxide fine particles D having a volume resistivity of 10 ¹⁰ Ωcm.

<Production Example 5 of Titanium Oxide> A hydrophobic degree of 65% was obtained in the same manner as in Production Example 3 except that rutile-type hydrophilic titanium oxide synthesized by a sulfuric acid method was used.
Titanium oxide fine particles E having an average primary particle diameter of 80 mμ, a BET of 80 m ² / g, and a volume resistivity of 10 ¹⁴ Ωcm were obtained.

Example 1 100 parts of a polyester resin obtained by condensing propoxylated bisphenol and fumaric acid I. Pigment Yellow 17 3.5 parts ・ Chromium complex salt of di-tert-butylsalicylic acid 4 parts After sufficiently premixing the above components with a Henschel mixer, melt kneading with a twin screw extruder, and after cooling, use a hammer mill. And roughly crushed to a particle size of about 1-2 mm. Next, it was pulverized by a pulverizer using an air jet method.
Furthermore, the obtained finely pulverized material is classified by a multi-segment classification device,
Yellow colorant-containing resin particles having a volume average particle size of 8.3 μm were obtained. The above-mentioned yellow colorant-containing resin particles 10
To 0 part, 1.0% of titanium oxide fine particles D was externally added to obtain a yellow toner. Next, C.I. I. Pigment Yellow 17 was replaced by 3 parts of a rhodamine pigment and 5 parts of a phthalocyanine pigment. Magenta toner and cyan toner were obtained in the same manner as above. Further, carbon black (average particle diameter 60 mμ, surface area 30 m ² / g, oil absorption 65
Using 4 parts of cc / 100 g, pH 8), resin particles containing a black colorant were obtained. The above-mentioned black resin particles 1
0.5% of amorphous titanium oxide fine particles A in 00 parts
A black toner was externally added. C. The above yellow, magenta, cyan and black toners were surface-coated with methyl methacrylate-butyl acrylate (75:25).
u-Zn-Fe-based ferrite particles and a toner concentration of 5
% To obtain a developer.

Using this developer, a running test of 20,000 sheets was conducted in a commercially available color copying machine (manufactured by CLC300 Canon) in an environment of 23 ° C./65%, and the results were 1.45 to 1.45. A high quality image having a sufficient image density of 60 was obtained. Furthermore, under an environment of 20 ° C./10%, 30
Similarly, good results were obtained in an environment of ° C / 80%.

Comparative Example 1 A developer was prepared in the same manner as in Example 1 except that the black toner of Example 1 was changed to the anatase type titanium oxide D used for the yellow toner, and a similar running test was performed. Although a good image was obtained in the case of black single color, in the case of the full-color image, under the environment of 30 ° C./80%, density unevenness which was considered to be due to transfer failure was slightly observed in the solid image of the black portion. For confirmation, when the black transfer electric field was reduced by 20%, a good image was obtained even in a full-color image, but under the environment of 20 ° C./10%, density unevenness was generated.

Comparative Example 2 Instead of the carbon black of Example 1, C.I. I. Pigment Yellow 17 and 1.2 parts of C.I. I. Pigment Red 5 and C.I. I. Pigment Blue 15
Example 1 except that 5 parts were used and a black toner was used.
A developer was prepared in the same manner as described above, and the same running test was performed . As a result, the same results as in Comparative Example 1 were obtained .

Reference Example The procedure of Example 1 was repeated, except that the titanium oxide fine particles B were used as the black toner used in Example 1.
At 0 ° C./80%, the image density becomes too high as 1.78,
Some toner scattering also occurred.

Example 2 The procedure of Example 1 was repeated, except that the titanium oxide fine particles C were used as the black toner.
An image density of 1.50 to 1.65 under an environment of 0 ° C./80%
, But good results were obtained.

Example 3 The same procedure as in Example 1 was carried out except that the titanium oxide fine particles E were used as the black toner. As a result, good results were obtained although highlight reproduction was slightly inferior.

[0043]

As described above, according to the full-color toner of the present invention, an image having high image quality and good color reproducibility can be obtained. Further, according to the full-color toner of the present invention, good transfer characteristics can be exhibited even when the environment changes.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a method for measuring a specific surface area.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G03G 9/08 G03G 9/09

Claims (4)

(57) [Claims] 1. A yellow toner comprising a colorant-containing resin particle containing at least a yellow colorant and a binder resin and an external additive, and a colorant containing at least a magenta colorant and a binder resin. A magenta toner comprising resin particles and an external additive, a cyan toner comprising colorant-containing resin particles containing at least a cyan-based colorant and a binder resin and an external additive, and at least carbon black and a binder resin. In a full-color toner in which a colorant-containing resin particle containing a black toner comprising an external additive, each external additive contains at least flow improver fine particles, and a flow improver in the black toner. The volume resistivity is higher than the volume resistivity of the flow improver in other yellow toner, magenta toner and cyan toner. Color toner. 2. The full-color toner according to claim 1, wherein the flow improver in the yellow, magenta and cyan toners is titanium oxide. 3. The full color as claimed in claim 2 , wherein the titanium oxide has been subjected to a hydrophobic treatment with a coupling agent, and has a hydrophobicity of 40 to 80% and an average particle diameter of 0.01 to 0.2 μm. toner. 4. The full-color toner according to claim 1, wherein the flow improver in the yellow, magenta, cyan and black toners is titanium oxide.